Title of Invention	"INTAKE DEVICE OF ENGINE"
Abstract	A purpose is to enhance workability of a bypass passage for downsizing of an entire intake device. A throttle body 2 of an intake device 1 includes a bore 4 and a throttle valve 5. The bore 4 is provided with a bypass passage 10 which bypasses the throttle valve 5 and a bypass valve 11 for opening and closing the bypass passage 10. A device block 3 is fixed to a mounting surface 9a of the body 2. The block 3 includes a covering surface 3a covering the mounting surface 9a. The block 3 houses the bypass valve 11 and a motor 12. The body 2 is formed with a bypass inlet port 16 and a bypass outlet port 17 in the mounting surface 9a upstream and downstream of the bore 4 from the throttle valve 5. The mounting surface 9a is formed with a bypass groove 18 providing communication between the inlet port 16 and the outlet port 17. The block 3 is fixed to the mounting surface 9a, covering the groove 18 by the covering surface 9a, so that the bypass passage 10 is formed of the inlet port 16, outlet port 17, groove 18, and covering surface 3a.

Title of Invention

"INTAKE DEVICE OF ENGINE"

Abstract

A purpose is to enhance workability of a bypass passage for downsizing of an entire intake device. A throttle body 2 of an intake device 1 includes a bore 4 and a throttle valve 5. The bore 4 is provided with a bypass passage 10 which bypasses the throttle valve 5 and a bypass valve 11 for opening and closing the bypass passage 10. A device block 3 is fixed to a mounting surface 9a of the body 2. The block 3 includes a covering surface 3a covering the mounting surface 9a. The block 3 houses the bypass valve 11 and a motor 12. The body 2 is formed with a bypass inlet port 16 and a bypass outlet port 17 in the mounting surface 9a upstream and downstream of the bore 4 from the throttle valve 5. The mounting surface 9a is formed with a bypass groove 18 providing communication between the inlet port 16 and the outlet port 17. The block 3 is fixed to the mounting surface 9a, covering the groove 18 by the covering surface 9a, so that the bypass passage 10 is formed of the inlet port 16, outlet port 17, groove 18, and covering surface 3a.

Full Text	DESCRIPTION INTAKE DEVICE OF ENGINE TECHNICAL FIELD [0001] The present invention relates to an intake device for controlling an amount of intake air to an engine, and to an intake device of an engine, including a throttle body housing a throttle valve in a bore through which intake air flows, the throttle valve being arranged to open and close the bore, and a device block fixed to the throttle body and housing at least one of sensors and device units. BACKGROUND ART [0002] As a device of this type, there are conventionally devices disclosed in Patent documents 1 and 2 mentioned below. An intake device disclosed in Patent document 1 is configured as below to improve workability and ease of assembly. Specifically, one side of a throttle body is formed as a mounting surface to which a device block is detachably fixed. The throttle body is formed with a bypass inlet port and a bypass outlet port which open in the mounting surface upstream and downstream of a bore relative to a throttle valve. The device block is formed with a bypass intermediate portion whose both ends are connected to the bypass inlet and outlet ports. The device block is also provided with a bypass valve, a throttle sensor, and others. The device block is fixed to the mounting surface, connecting the bypass inlet and outlet ports with the bypass intermediate part to form a bypass passage. [0003] Further, an intake amount control device disclosed in Patent document 2 is configured as below to enable downsizing and improve workability and easy of assembly. Specifically, one side of a throttle body is formed as a mounting surface parallel to a bore, and a mating surface of a control block is connected to the mounting surface. At least one of the mounting surface and the mating surface is formed with a bypass upstream groove communicating with an upstream portion of the bore and a bypass downstream groove communicating with a downstream portion of the bore. The control block is formed with a valve port providing communication between the bypass upstream groove and the bypass downstream groove. In this valve port, a bypass valve and its actuator are placed. These bypass valve and actuator are arranged in the control block in such a manner as to be parallel to the bore. [0004] [Patent Document l] International publication No. WO2002/044541 (Jpn. Unexamined Patent Republication) [Patent Document 2] Jpn. unexampled patent publication No. 2003-148303 DISCLOSURE OF INVENTION PROBLEMS TO BE SOLVED BY THE INVENTION [0005] However, the devices disclosed in Patent documents 1 and 2 have to be formed with a vertical hole perpendicular to the bore or a lateral hole parallel to the bore in order to provide the bypass intermediate part or the valve port in the device block or the control block. Workability (die-cast molding, cutting, etc.) of such holes would be complicated, resulting in low flexibility in working. This restriction in working would cause an increase in size of the device, which is a stumbling block to downsizing. Air-fuel mixture from an engine may blow back to the bypass intermediate portion and the valve port. Therefore, inner walls of the bypass intermediate portion and the valve port have to be made of a material resistant to gasoline and also there is concern that deposits adhere thereon. The complicated shapes of the ports would result in difficult maintenance for removing the deposits when have adhered to the bypass intermediate portion and the valve port. Furthermore, though relatively speaking, the deposits are likely to fix to the valve port, thereby causing an operation failure of the bypass valve. [0006] The present invention has been made in view of the above circumstances and has a first purpose to provide an intake device of an engine, with enhanced workability of a bypass passage to achieve an entirely downsized design. A second purpose of the present invention is, besides the first purpose, to provide an intake device of an engine, with a simplified structure associated with a bypass valve for entirely downsizing. A third purpose of the present invention is, besides the first and second purposes, to provide an intake device of an engine, with a space-saving device block for compact design. MEANS FOR SOLVING THE PROBLEMS [0007] To achieve the above first purpose, the invention set forth in claim 1 provides an intake device of an engine, comprising a throttle body housing a throttle valve in a bore through which intake air is allowed to flow, the throttle valve being arranged to open and close the bore, and a device block that is fixed to the throttle body and houses at least one of sensors and device units, the intake device being characterized in that only the throttle body is formed with a bypass passage for bypassing the intake air flowing in the bore. [0008] According to the above configuration, the bypass passage is provided only in the throttle body. This facilitates working (die-cast molding, cutting, etc.) of the bypass passage, and the working flexibility can also be obtained. There is no need to form any passage in the device block and therefore no intake air is allowed to flow in the device block. [0009] To achieve the first purpose, the invention set forth in claim 2 provides that, in the invention set forth in claim 1, the bypass passage is formed in an arbitrary shape in the throttle body by casting. [0010] According to the above configuration of the invention, besides the operation of the invention set forth in claim 1, the bypass passage is formed in any shape by casting, so that flexible working (die cast molding, cutting, etc.) can be conducted at once. [0011] To achieve the first purpose, the invention set forth in claim 3 provides that, in the invention set forth in claim 1 or 2, the device block is detachably coupled to the throttle body, the bypass passage is formed in substantially parallel to the bore, a portion around a port of the bypass passage serves as a valve seat for an idle speed control valve (ISCV). [0012] According to the above configuration of the invention, besides the operation of the invention set forth in claim 1 or 2, the portion around the port of the bypass passage functions as the valve seat for the ISCV and no additional valve seat is required. Further, the device block is detachably coupled to the throttle body, so that the device block can be detached as needed. [0013] To achieve the first purpose, the invention set forth in claim 4 provides that, in the invention set forth in claim 3, the ISCV is provided in the device block, and a valve element of the ISCV and the valve seat are initialized when the device block is coupled to the throttle body. [0014] According to the above configuration of the invention, besides the operation of the invention set forth in claim 3, initialization of the valve element and the valve seat is carried out at the time when the throttle body is coupled to the device block. This makes it possible to easily ensure a normal operation of the ISCV. [0015] To achieve the first purpose, the invention set forth in claim 5 provides that, in the invention set forth in claim 4, the device block is provided with an mounting section for mounting a motor of the ISCV, and the mounting section is formed with a attaching section in which the sealing means is seated, and this attaching section is formed with a groove communicating to atmosphere. [0016] According to the above configuration of the invention, besides the operation of the invention set forth in claim 4, a difference in pressure between the inside and the outside of the device block can be kept low through the groove. [0017] To achieve the first purpose, the invention set forth in claim 6 provides that, in the invention set forth in claim 4 or 5, the device block is provided with a sleeve covering the valve element of the ISCV, the valve element is provided to be able to protrude from an opening of the sleeve, and the sleeve is provided with a foreign body guard in the opening. [0018] According to the above configuration of the invention, besides the operation of the invention set forth in claim 4 or 5, the foreign-body guard restricts the flow of foreign-bodies tending to enter the sleeve through its opening. [0019] To achieve the second purpose, the invention set forth in claim 7 provides that, in the invention set forth in claim 6, urging means is placed between the foreign-body guard and the valve element for urging the valve element in a direction to move away from the valve seat, and an urging force of the urging means is determined to be larger than a sum of a force applied to the valve element by negative pressure acting on the bypass passage and a force of the output shaft of the motor tending to move in an axis direction by vibration. [0020] According to the above configuration of the invention, besides the operation of the invention set forth in claim 6, the output shaft of the motor is constantly urged to one side of the axial direction and positioned in place by the urging force of the urging means. It is possible to eliminate the need for an axially positioning member such as a ball bearing. [0021] To achieve the second purpose, the invention set forth in claim 8 provides that in the invention set forth in claim 7, the throttle body is provided with a throttle shaft placed across the bore, the throttle valve is supported on the throttle shaft, the valve element is arranged to reciprocate relative to the valve seat, and the throttle shaft and the valve element are located so that an axis line of the throttle shaft and a moving direction of the valve element are parallel to each other. [0022] According to the above configuration of the invention, besides the operation of the invention set forth in claim 7, the throttle body is placed in a vehicle so that the axis line of the throttle shaft is perpendicular to the vibration direction of the engine. Thus, the vibrations of the throttle shaft in the axial direction can be comparatively reduced. Here, the valve element and the throttle shaft are arranged so that the moving direction of the valve element and the axis line of the throttle shaft are parallel to each other, and therefore the vibrations acting on the valve element in the moving direction thereof can be comparatively reduced. Consequently, the vibrations acting on the valve element are small and correspondingly the urging force of the urging means that urges the valve element can be set to be smaller. This smaller urging force of the urging means can contribute to a comparative reduction in power of the motor for driving the valve element. [0023] To achieve the first purpose, the invention set forth in claim 9 provides an intake device of an engine, comprising a throttle body including a bore through which intake air is allowed to flow and a throttle valve arranged to open and close the bore, the bore being provided with a bypass passage which bypasses the throttle valve, and a bypass valve is provided for opening and closing the bypass passage, the intake device being characterized in that the throttle body is provided with a mounting surface on one side, the intake device further comprises a device block including a covering surface which covers the mounting surface, the device block being detachably fixed to the mounting surface, the device block includes at least the bypass valve and an actuator for driving the bypass valve, the throttle body is formed with a bypass inlet port and a bypass outlet port which open in the mounting surface upstream and downstream of the bore from the throttle valve, the mounting surface is formed with a bypass groove providing communication between the bypass inlet port and the bypass outlet port, and the device block is fixed to the mounting surface, covering the bypass groove by the covering surface, so that the bypass passage is formed of the bypass inlet port, the bypass outlet port, the bypass groove, and the covering surface. [0024] According to the above configuration of the invention, working (die cast molding, cutting, etc.) for forming the bypass passage is required only to make the bypass inlet port, the bypass outlet port, and the bypass groove in the mounting surface of the throttle body. This working can be conducted at, once by for example casting and cutting with a drill press. Working flexibility can also be obtained. Further, no passage needs to be formed in the device block and therefore no intake air is allowed to flow in the device block. [0025] To achieve the second purpose, the invention set forth in claim 10 provides that, in the invention set forth in claim 9, the bypass valve is located corresponding to the bypass outlet port, a portion around the bypass outlet port opening in the mounting surface serves as a valve seat for the bypass valve. [0026] According to the above configuration of the invention, besides the operation of the invention set forth in claim 9, the portion around the bypass outlet port functions as a valve seat of the bypass valve, which can eliminate the need to provide an additional valve seat. [0027] To achieve the third purpose, the invention set forth in claim 11 provides that, in the invention set forth in any of claims 1 through 10, the device block includes a wiring connector extending obliquely downward or upward of the throttle body from the device block. [0028] According to the above configuration of the invention, besides the operation of the invention set forth in any of claims 1 through 10, the connector provided in the device block protrudes downward or upward of the throttle body so that the connector is placed in a space above or under the throttle body without protruding outside. EFFECTS OF THE INVENTION [0029] According to the invention set forth in claim 1, working (die cast molding, cutting, etc.) for the bypass passage is easy and working flexibility is attained. This can improve workability of the bypass passage and downsize the intake device. [0030] According to the invention set forth in claim 1, besides the effects of the invention set forth in claim 1, flexible working (die cast molding, cutting, etc.) for the bypass passage can be performed at once, thereby improving workability of the bypass passage and downsizing the intake device. [0031] According to the invention set forth in claim 3, besides the effects of the invention set forth in claim 1 or 2, no additional valve seat needs to be provided and therefore a simplified structure associated with the valve element can be achieved with a size reduction. In this regard, the intake device can also be downsized. Further, the device block can be detached from the throttle body as required, so that maintenance of the device block and the throttle body can be conducted readily. [0032] According to the invention set forth in claim 4, besides the effects of the invention set forth in claim 3, it is possible to enhance assembling workability of the throttle body and the device block. [0033] According to the invention set forth in claim 5, besides the effects of the invention set forth in claim 4, the difference in pressure between the inside and the outside of the device block can be kept small through the groove. This makes it possible to restrain water or the like from entering the device block. [0034] According to the invention set forth in claim 6, besides the effects of the invention set forth in claim 4 or 5, the foreign-body guard can prevent foreign-bodies such as deposits contained in the intake air from entering the sleeve. [0035] According to the invention set forth in claim 7, besides the effects of the invention set forth in claim 6, positioning of the output shaft of the motor can be performed without using any axially positioning member such as a ball bearing. Thus, the intake device can be manufactured at low cost and can provide enhanced accuracy of a flow rate. [0036] According to the invention set forth in claim 8, besides the effects of the invention set forth in claim 7, the motor can be downsized as the power of the motor can be reduced, resulting in a downsized device block which houses the motor, thus achieving a more compact intake device. [0037] According to the invention set forth in claim 9, workability of the bypass passage can be enhanced, thereby enabling downsizing of the intake device. [0038] According to the invention set forth in claim 10, besides the effects of the invention set forth in claim 9, a simplified structure associated with the bypass valve can be achieved, thereby enabling further downsizing the intake device! [0039] According to the invention set forth in claim 11, besides the effects of the invention set forth in any of claims 1 through 10, space-saving device block can be achieved, thereby further downsizing the intake device. BRIEF DESCRIPTION OF DRAWINGS [0040] Fig. 1 is a plan view showing an intake device. Fig. 2 is a plan sectional view of the intake device. Fig. 3 is a sectional view of the intake device taken along a throttle shaft. Fig. 4 is a front view showing a mounting surface of a base. Fig. 5 is a front view of part of the mounting surface. Fig. 6 is a front view of part of the mounting surface. Fig. 7 is a sectional view showing a circled part in Fig. 6. Fig. 8 is a front view showing a covering surface of a device block. Fig. 9 is a conceptual view showing a positional relationship between a bypass passage, a bypass valve, and a motor in a throttle body. Fig. 10 is a sectional view showing the bypass valve and the motor. Fig. 11 is an enlarged sectional view showing part of Fig. 10. Fig. 12 is a sectional view showing a conventional structure related to a bypass valve and a step motor. Fig. 13 is an enlarged sectional view showing a threaded portion of the conventional structure. Fig. 14 is an enlarged sectional view showing the threaded portion of the conventional structure. Fig. 15 is a sectional view of a present embodiment shown in comparison with Fig. 12. Fig. 16 is an enlarged sectional view a threaded portion of the present embodiment. Fig, 17 is a front view showing the inside of the device block opposite to the covering surface. Fig. 18 is a sectional view corresponding to Fig. 15. Fig. 19 is a sectional view corresponding to Fig. 15. EXPLANATION OF REFERENCE CODES [0041] 1 Intake device 2 Throttle body 3 Device block 3a Covering surface 4 Bore 5 Throttle valve 9a Mounting surface 10 Bypass passage 11 Bypass valve Ha Distal end 12 Motor (Actuator) 12a Output shaft 14 Throttle sensor 16 Bypass inlet port 17 Bypass outlet port 18 Bypass groove 27 Valve seat 28 pressure-introducing port 29 Intake temperature sensor 30 Connector 32 ISCV 33 Receiving cavity (Mounting section) 33a Shoulder portion (Attaching section) 33b Aspiration groove (Groove) 35 0-ring (Sealing means) 38 Sleeve 39 Foreign-body guard 40 Auxiliary spring (Urging means) BEST MODE FOR CARRYING OUT THE INVENTION [0042] A detailed description of a preferred embodiment of an intake device of an engine according to the present invention will now be given referring to the accompanying drawings. [0043] Fig. 1 shows a plan view of the intake device 1 of engine in the present embodiment. Fig. 2 is a plan sectional view of the same intake device 1. This intake device 1 is placed in use in an intake passage of an engine of a motorcycle. This intake device 1 mainly includes a throttle body 2 and a device block 3 mounted and fixed to one side of the throttle body 2. [0044] The throttle body 2 is made of synthetic resin in nearly cylindrical form, internally formed with a bore 4 through which intake air is allowed to flow. In this bore 4, a butterfly throttle valve 5 is placed to open and close the bore 4. The bore 4 forms an intake passage for supplying air to the engine. The throttle valve 5 is fixed on a throttle shaft 6 rotatably disposed across the bore 4. One end of the throttle shaft 6 (a left end in Figs. 1 and 2) is fixedly coupled to a wire drum 7. This wire drum 7 is connected to a wire (not shown) connected to a throttle operating device. On the wire drum 7, a return spring 8 is mounted to urge the throttle valve 5 in a full closing direction. [0045] On the other end of the throttle shaft 6 (a right end in Figs. 1 and 2), the throttle body 2 is integrally formed with a base 9 for fixing the device block 3. When the device block 3 is fixed to this base 9, a bypass passage 10 bypassing the throttle valve 5 in the bore 4 is formed. The device block 3 houses at least one of sensors and device units. In the present embodiment, the device units provided in the device block 3 are a bypass valve 11 corresponding to a valve element of the invention for opening/closing the bypass passage 10 and a step motor (hereinafter, simply referred to as a "motor") corresponding to an actuator of the invention for driving the valve 11. In the present embodiment, the device block 3 further mounts therein other device units such as a throttle sensor for detecting an opening degree of the throttle valve 5, a temperature sensor for detecting the temperature of intake air in the bore 4, and a pressure sensor for detecting the pressure of the intake air, as well as the bypass valve 11 and the motor 12. [0046] Fig. 3 is a sectional view of the intake device 1 taken along the throttle shaft 6. Both ends of the throttle shaft 6 are rotatably supported by bearings 13. The right end of the throttle shaft 6 is coupled to a throttle sensor 14 built in the device block 3. [0047] As shown in Figs. 1 and 2, the base 9 includes a mounting surface 9a to which the device block 3 is joined and fixed in such a manner as to be detachable. Fig. 4 is a front view of this mounting surface 9a. At substantially the center of this mounting surface 9a, a boss 15 supporting the throttle shaft 6 is formed. In the mounting surface 9a, a bypass inlet port 16 and a bypass outlet port 17 are formed on both sides of the boss 15 in such a manner as to extend perpendicular to the bore 4. These bypass inlet port 16 and bypass outlet port 17 are formed in the mounting surface 9a of the throttle body 2 to open into an upstream side and a downstream side of the bore 4 respectively relative to the throttle valve 5. In the mounting surface 9a, further, a bypass groove 18 is formed in parallel to the bore 4 to connect the bypass inlet port 16 and the bypass outlet port 17. This bypass groove 18 is formed to curve along the upper side of the boss 15. In the present embodiment, the bypass inlet port 16, the bypass outlet port 17, and the bypass groove 18, which form the bypass passage 10 for bypass of the intake air flowing in the bore 4, are provided only in the throttle body 2. In the mounting surface 9a, besides, a sensing-part mounting hole 19 for the intake temperature sensor and a pressure-intake hole 20 for the pressure sensor are formed below the bypass inlet port 16 and the bypass outlet port 17 respectively. Around the pressure-intake hole 20, a fluid receiver 21 for receiving deposits or the like in case of entry of the deposits or the like. In the mounting surface 9a, a seal groove 22 is formed for receiving a gasket surrounding the aforementioned boss 15, bypass groove 18, sensing-part mounting hole 19, pressure-intake hole 20, fluid receiver 21, and others. In addition, a plurality of bolt holes 23 for fixing the device block 3 is provided on the periphery of the base 9. [0048] Here, the seal groove 22 is of a unique shape with a combination of entirely complicated curves. Accordingly, as shown in Fig. 5, adjacent portions of the gasket 24 are separated especially at a boundary between the fluid receiver 21 and the bypass groove 18 and therefore each end of the portions is likely to be broken and thus caught between the device block 3 and the throttle body 2 during assembly. In the present embodiment, therefore, as shown in Fig. 6 different from a configuration shown in Fig. 5, adjacent portions of the gasket 24 at the boundary between the fluid receiver 21 and the bypass groove 18 are formed continuous with each other so that part of the gasket 24 is placed in intersecting form with part of the fluid receiver 21. In Fig. 6, the intersecting area of the fluid receiver 21 and the gasket 24 is indicated by a circle S. Fig. 7 is a sectional view showing the area surrounded by the circle S of Fig. 6 in the state where the device block 3 is fixed to the base 9. As shown in Fig. 7, a communication portion 25 is formed in the device block 3. With this configuration, the communication portion 25 prevents part of the fluid receiver 21 from being blocked even when the device block 3 is fixed to the base 9. Since the adjacent portions of the gasket 24 are not separated, the gasket 24 can be set stably, ensuring sealing performance and easing assembly of the device block 3. [0049] On the other hand, the device block 3 is provided with a covering surface 3a which covers the mounting surface 9a of the base 9. Fig. 8 is a front view of this covering surface 3 a. In substantially the center of this covering surface 3 a, a shaft hole 26 for the throttle shaft 6 is formed. In a nearly upper right part of the covering surface 3a, a bypass valve 11 is provided corresponding to the bypass outlet port 17. Accordingly, the portion around the bypass outlet port 17 functions as a valve seat 27 for the bypass valve 11. In other words" the portion around the opening forming the bypass passage 10 functions as the valve seat 27 for the bypass valve 11. In a right part of the covering surface 3 a, a pressure-introducing port 28 for a pressure sensor (not shown) is provided. This pressure-introducing port 28 is arranged to face the pressure-intake hole 20 shown in Fig. 4. In a left part of the covering surface 3 a, an intake temperature sensor 29 is provided. This intake temperature sensor 29 is arranged to face the sensing-part mounting hole 19 shown in Fig. 4. The device block 3 also includes a connector 30 for wiring. This connector 30 is provided protruding from the lower side of the covering surface 3a to extend obliquely downward of the throttle body 2. The inclination of this connector 30 is determined to form an angle ranging from 20° to 70° with the center line of the throttle shaft 6 in Fig. 3. Furthermore, as shown in Fig. 8, a plurality of unloaded holes 31 is formed on the periphery of the device block 3, corresponding to the bolt holes 23 of the base 9. [0050] The device block 3 is fixed to the base 9 in such a way that the covering surface 3a of the device block 3 contacts with the mounting surface 9a. This fixation is made by tightening bolts in the unloaded holes 32 and the bolt holes 23. When the bypass groove 18 is covered by the covering surface 3a as above, the bypass inlet port 16, the bypass outlet port 17, the bypass groove 18, and the covering surface 3a form the bypass passage 10. [0051] Fig. 9 is a conceptual view showing a positional relationship between the bypass passage 10, the bypass valve 11, and the motor 12 in the throttle body 2. As seen in Fig. 9, the bypass valve 11 is arranged on the downstream side of the bypass passage 10 to face the bypass outlet port 17. This bypass valve 11 is movable toward or away from the bypass outlet port 17 by operation of the motor 12. At this time, the portion around the outlet port 17 serves as a valve seat 27 to allow opening/closing of the bypass passage 10, thereby controlling the opening degree of the bypass valve 11. By this control of opening degree, a flow rate of air allowed to flow in the bypass passage 10 is controlled. This bypass valve 11 is mostly driven while the throttle valve 5 is in a full closed position. For idling control of an engine, the opening degree of the bypass valve 11 is adjusted to finely regulate an intake amount of air to be supplied to the engine through the bypass passage 10. In other words, these bypass valve 11 and motor 12 constitute a so-called idle speed control valve (ISCV) 32. In the present embodiment, this ISCV 32 is provided in the device block 3. [0052] Fig. 10 is a sectional view showing the bypass valve 11 and the motor 12 in the intake device 1. Fig. 11 is an enlarged view of part of Fig. 10. The device block 3 is formed with a receiving cavity 33 serving as a mounting section of the present invention for mounting the motor 12. The motor 12 is mounted in this receiving cavity 33 so that a pressurization spring 34 is interposed therebetween. An Oring 35 is placed between the outer periphery of the motor 12 and the receiving cavity 33. An output shaft 12a of the motor 12 is externally formed with a threaded portion 36. The bypass valve 11 is mounted on the output shaft 12a through a nut 37 engaging with the threaded portion 36. The bypass valve 11 is of a cap shape placed to sheathe the output shaft 12a. A distal end lla of the bypass valve 11 is sized to be insertable in the bypass outlet port 17. This distal end lla has a tapered conical shape with a shoulder portion lib at an end of an outer tapered surface. The bypass valve 11 is formed, at its base end, with a flange lie. The device block 3 is provided with a sleeve 38 which covers the bypass valve 11 and fitted in the bypass groove 18 of the base 9. The bypass valve 11 is movable, whereas the sleeve 38 is immovable. The distal end lla of the bypass valve 11 can be projected from an opening of the sleeve 38. The sleeve 38 includes a foreign body guard 39 extending inward in annular form in an opening of the sleeve 38. An auxiliary spring 40 serving as an urging means of the present invention is placed between this foreign body guard 39 and the flange lie of the bypass valve 11. This auxiliary spring 40 urges the bypass valve 11 in a direction to move away from the valve seat 27. [0053] Herein, the bypass valve 11 is configured to reciprocate rightward and leftward in Fig. 10 relative to valve seat 27 and also arranged so that the moving direction of the bypass valve 11 is parallel to an axial direction of the throttle shaft 6 (a horizontal direction in Fig. 10). In the present embodiment, the throttle body 2 is mounted in a two-wheel vehicle so that the axis line of the throttle shaft 6 is perpendicular to a vibration direction of the engine. [0054] According to the configuration of the aforementioned bypass passage 10, the work of forming the bypass passage 10 is to make the bypass inlet port 16, bypass outlet port 17, and bypass groove 18 in the mounting surface 9a of the base 9 of the throttle body 2. This work can be performed at once by casting, cutting with a drill press, or others. In the present embodiment, the throttle body 3 is made of resin by integral molding. The bypass inlet port 16, the bypass outlet port 17, and the bypass groove 18 are formed at once by casting. In the present embodiment, accordingly, the inlet port 16, the bypass outlet port 17, and the bypass groove 18 are made by casting into arbitrary shapes to form the bypass passage 10. It is therefore possible to perform flexible working (die cast molding, cutting, etc.) at once. In the present embodiment, furthermore, the inlet port 16, the bypass outlet port 17, and the bypass groove 18 are provided only in the throttle body 2, which facilitates the working (die cast molding, cutting, etc.) for those ports 16 and 17, and groove 18 and provides flexibility in the working. Because of adoption of the casting, the bypass groove 18 can be formed in a curve extending along; the boss 15 as shown in Fig. 4. There is no need for making any passages in the device block 3 for forming the bypass passage 10. Thus, no intake air is allowed to flow in the device block 3. The throttle body 2 and the device block 3 are therefore less subjected to restrictions in the work to form the bypass passage 10. Owing to no working restrictions, an increase in size of the throttle body 2 and the device block 3 can be restrained. This makes it possible to improve the workability of the inlet port 16, the bypass outlet port 17, and the bypass groove 18, and hence the workability of the bypass passage 10. Thus, the intake device 1 can be entirely compact in size. Since no passage is formed in the device block 3, no air-fuel mixture is allowed to flow back in the device block 3 from the engine. Accordingly, the inner structure of the device block 3 does not have to be made of a material resistant to gasoline, and therefore any concern about adhesion of deposits to the inner structure is not caused. Even if deposits adhere to the bypass groove 18, the device block 3 has only to be detached from the mounting surface 9a to open the bypass groove 18 and then a maintenance work to remove the deposits from the bypass groove 18 can be made readily. [0055] According to the configuration of the aforementioned bypass passage 10, as shown in Fig. 10, the portion around the bypass outlet port 17 serves as the valve seat 27 for the bypass valve 11. No separate part needs to be added as the valve seat 27. This can simplify the structure associated with the bypass valve 11, avoiding a bulky configuration. In this view, the intake device 1 can also be compact in size. In the present embodiment, furthermore, the bypass valve 11 is configured to be driven vertically relative to the valve seat 27. The aforementioned bypass valve disclosed in Patent Document 2, configured to slide in parallel, is likely to cause deposits to enter and adhere to a portion in a narrow clearance.) However, the present embodiment is unlikely to cause such problem. Further, the device block 3 is detachably fixed to the throttle body 2, so that the device block 3 can be detached from the throttle body 2 as needed. Detaching the device block 3 from the throttle body 2 can facilitate maintenance of the device block 3 and the throttle body 2. [0056] The threaded portion 36 of the output shaft 12a of the motor 12 is extremely precise and has small clearance. Due to this configuration, the performance of the bypass valve 11 may be deteriorated if foreign bodies enter the threaded portion 36. In the present embodiment, as shown in Fig. 10, the foreign-body guard 39 is provided in the opening of the sleeve 38, so that the flow of foreign bodies tending to enter the inside of the sleeve 38 through its opening can be restricted by the foreign body guard 39. Thus, the foreign body guard 39 can prevent foreign bodies such as deposits contained in intake air from entering the inside of the sleeve 38. Even if the foreign bodies pass through the foreign body guard 39 to enter the inside of the sleeve 38, the flange lie of the bypass valve 11 can serve as a second foreign-body guard for preventing entry of the foreign bodies into the threaded portion 36. As illustrated by an arrow in Fig. 11, when the deposits blow back and collide with the distal end Ha of the bypass valve 11, the blowing-back deposits flow along the outer periphery of the distal end lla and is deflected outward at the shoulder portion 11. This action can also prevent the deposits from entering the inside of the sleeve 38. Since entry of the deposits into the inside of the sleeve 38 and the threaded portion 36 can be prevented as above, it is possible to prevent any operation failures of the motor 12 and the bypass valve 11 that are caused by deposits. The foreign-body guard 39 is provided in the immovable sleeve 38, so that the bypass valve 11 can be compact in size and light in weight and the bypass valve 11 can have a lower vibration-proof spring, load. This can downsize the motor 12. This downsizing of the motor 12 contributes to a compact design of the intake device 1. [0057] According to the configuration of the aforementioned bypass passage 10, the device block 3 is formed with the connector 30 protruding obliquely downward of the throttle body 2 as shown in Fig. 3. Thus, the connector 30 is located in a space under the throttle body 2 without protruding outside. This makes it possible to save the space for placement of the device block 3. Also in this view, the intake device 1 can be compact in size. Since the connector 30 is hidden under the throttle body 2, the connector 30 can be protected and the appearance design of the intake device 1 can also be improved. [0058] In general, protruding parts such as a connector tend to largely vibrate as they are positioned farther away from a holding portion (a central portion) of the throttle body. Thus, those parts are preferably provided as close to the central portion as possible. In the present embodiment, the connector 30 is provided at a slant relative to the device block 3, so that a compact design can be attained and the connector 30 can be positioned closer to the central portion of the throttle body 2 as compared with the case where the connector is positioned horizontally or vertically. It is therefore possible to reduce vibrations of the connector 30. This vibration reduction allows adoption of a narrow connector terminal, thus ensuring downsizing of the connector 30. An inclination angle of the connector 30 herein is set in a range of 20° to 70° relative to the center line of the throttle shaft 6 so that the connector 30 may be arranged in efficient and space-saving manner. [0059] Other features of the intake device 1 in the present embodiment will be explained below. Fig. 12 is a sectional view of a conventional structure related to a, bypass valve and a step motor. A bypass valve 101 of the conventional structure is threadably mounted on a threaded portion 103 of an output shaft 102a of a step motor 102 of the conventional structure. A flange lOla is formed in the distal end portion of the bypass valve 101. An auxiliary spring 105 is placed between the flange lOla and a ball bearing 104 of the output shaft 102a. This auxiliary spring 105 urges the bypass valve 101 toward a valve seat 106. The direction in which bypass valve 101 is urged by the auxiliary spring 105 is the direction in which the valve 101 moves at the time of initialization. [0060] Fig. 13 is an enlarged sectional view showing a state of the threaded portion 103 at the time of controlling a flow rate of intake air allowed to flow in the bypass passage by the bypass valve 101 of the conventional structure. In the conventional structure configuration, by the full-closing initialization in which the bypass valve 101 is caused to abut against the valve seat 106, the auxiliary spring 105 urges the bypass valve 101 in a direction to be influenced by backlash of the threaded portion 103. In other words, as shown in Fig. 13, the bypass valve 101 is urged in a direction (an arrow direction) to move away from the step motor 102 by the auxiliary spring 105. The output shaft 102a is restricted in its axial movement by the ball bearing 104. Thus, backlash BR occurs in the threaded portion 103. [0061] Fig. 14 is an enlarged sectional view showing the threaded portion 103 at the time of initialization. In the conventional structure, by the initialization, the bypass valve 101 abuts against the valve seat 106 and is restrained from moving. On the other hand, the threaded portion 103 of the output shaft 102a is moved by a clearance corresponding to the backlash BR. This backlash BR is an allowance of movement of the bypass valve 101, which causes variations in the flow rate of intake air. [0062] Fig. 15 is a sectional view of the configuration of the present embodiment shown in comparison with Fig. 12. In the present embodiment, the bypass valve 11 and the valve seat 27 can be initialized at the time when the device block 3 is fixed to the throttle body 2. In Fig. 15, the pressurization spring 34 presses the motor 12 against the device block 3 to prevent the motor 12 from shaking due to the vibration. Here, the "load" of the pressurization spring 34 is set at a value equal to or larger than the value obtained by multiplying the "mass" of the motor 12 by the "guaranteed vibration acceleration". Assuming that the "mass" is "15g" and the "guarantee vibration acceleration" is "30G", for example, the "load" of the pressurization spring 34 is "450 gf or larger. [0063] As the auxiliary spring 40, a spring having a tapered shape (a taper spring) is used, which can reduce a contact length, and the ISCV 32 can be reduced in length in an extension and contraction direction. Here, the auxiliary spring 40 presses the output shaft 12a against a plate 41 opposite the auxiliary spring 40, making it possible to hold the bypass valve 11 in place in its axial direction. The "load" of the auxiliary spring 40 is determined according to the force (1) applied to the bypass valve 11 by negative pressure and the force (2) of the mass of a rotor system tending to move away from the plate 41 by vibration. For example, for the force (1), the bypass valve 11 is pulled down by a force of " 1.7N" at the maximum in the case where the inner diameter of the valve seat 27 is "Φ6" (6 mm in diameter) and a positive/negative differential pressure of the bypass valve 11 is "60 kPa". For the force (2), a force of "0.9 N" is applied in the case where the vibration is "30 G" and the mass of the rotor system (a total mass of the rotor, the bypass valve and the nut) is '"3 g". In the present embodiment, the load of the auxiliary spring 40 is determined to be larger than the sum of the above forces (1) and (2). Specifically, the urging force of the auxiliary spring 40 is determined to be larger than the sum of the force applied to the bypass valve 11 by the negative pressure acting on the bypass groove 18 and the moving force of the output shaft 12a of the motor 12 tending to move in the axial direction by the vibration. Because of the load of the auxiliary spring 40 being determined to be larger than the sum of the forces (l) and (2), the output shaft 12a is normally pressed against the plate 41. As to the motor 12, the positioning of the output shaft 12a can be conducted by use of only a slide bearing 42 without using any positioning member such as a ball bearing. Accordingly, the intake device 1 can be manufactured at low cost and the flow rate accuracy of the intake device 1 can be enhanced. [0064] In the present embodiment, furthermore, the throttle body 2 is mounted in a two-wheel vehicle so that the axis line of the throttle shaft 6 is perpendicular to a vibration direction of the engine. Accordingly, the engine vibration acting on the throttle shaft 6 in the axial direction can be relatively reduced. Here, the bypass valve 11 and the throttle shaft 6 are located so that the moving direction of the bypass valve 11 and the axis line of the throttle shaft 6 are parallel to each other. The vibration acting on the valve 11 in the moving direction of the valve 11 will be relatively reduced. By the reduction in vibration acting on the bypass valve 11, it is consequently possible to determine the urging force of the auxiliary spring 40 to be relatively small for urging the valve 11. Further, the smaller the urging force of the auxiliary spring 40, the output of the motor 12 for driving the bypass valve 11 can be determined to be relatively smaller. This makes it possible to downsize the motor 12 by the reduction of output of the motor 12, leading to size reduction of the device block 3 which houses the motor 12. In this regard, the intake device 1 can be made more compact. [0065] The auxiliary spring 40 is designed to have an urging force that acts in a direction opposite the direction to pull the bypass valve 11 by negative pressure and is almost equal to the load calculated by summing up the forces (l) and (2). Thus, the force of pulling the bypass valve 11 by negative pressure acts in a direction to be canceled by the force of the auxiliary spring 40. Therefore, the stress on the threaded portion 36 that repeatedly reciprocates for controlling a flow rate of intake air is mitigated, reducing abrasion of a sliding part to ensure a long life. In the ISCV 32 of the present embodiment where the valve seat 27 is placed downstream from the bypass valve 11, the bypass valve 11 is urged by the auxiliary spring 40 in a direction opposite to the direction to pull down the bypass valve 11 by negative pressure. This makes it possible to make the moving direction of the output shaft 12a opposite to the urging force on the nut 37 as shown in Fig. 16 at the initialization executed by abutment against the valve seat 27. This configuration can cancel the backlash of the threaded portion 36 and, differently from the conventional structure shown in Fig. 12, it is therefore possible to restrain the flow rate of intake air from varying under the influence of the backlash. [0066] Fig. 17 shows the inside of the device block 3 opposite to the covering surface 3a. In an upper left part in Fig. 17, a receiving cavity 33 in which the motor 12 is assembled. In an upper right part in Fig. 17, further, the throttle sensor 14 is located. When the thus configured device block 3 is to be fixed to the base 9, it is positioned with reference to the throttle sensor 14. At this time, accordingly, an axis deviation Ad occurs between the bypass valve 11 coupled to the motor 12 and the valve seat 27 of the base 9 as shown in Fig. 18. This may cause the bypass valve 11 to abut against one side of the valve seat 27 at the time of initialization of the ISCV 32, which makes it impossible to execute normal initialization. In the present embodiment, however, there is a difference between the inner diameter D of the receiving cavity 33 and the outer diameter d of the motor 12, as shown in Fig. 18. In other word, the inner diameter D is determined to be slightly larger than the outer diameter d. In the present embodiment, the inner diameter D is set at "15 mm" and the outer diameter d is set in a range of "14 mm to 14.8 mm". Further, the receiving cavity 33 is provided with a shoulder portion 33a on which an 0-ring 35 is placed, so that the motor 12 is made floating in a radial direction by the 0-ring 35 and is held in a thrust direction by the pressurization spring 34. In this way, the motor 12 is circumferentially made floating by the 0-ring 35. At the initialization of the ISCV 32, although the distal end Ha of the bypass valve 11 may abut against one side of the valve seat 27, the inclination of the motor 12 can be accepted by a reactive force of the 0-ring 35, thereby allowing the bypass valve 11 to go in the bypass outlet port 17 along the valve seat 27 as shown in Fig. 19. This can absorb the axis deviation Ad between the bypass valve 11 and the valve seat 27 accordingly. [0067] In the ISCV of the conventional structure shown in Fig. 12, having no stopper element for the bypass valve 101, the bypass valve 101 tends to slip off the threaded portion 103 when the initialization of the ISCV is made in error while the ISCV remains demounted from a counterpart member having the valve seat 106. Then, returning of the bypass valve 101 could not be easily made without a special drive circuit. In the present embodiment, on the other hand, the inner diameter of the foreign body guard 39 is smaller than the outer diameter of the flange He of the bypass valve 11 as shown in Figs. 10 and 11. Accordingly, even where the bypass valve 11 is moved in a protruding direction while the device block 3 remains detached from the throttle body 2, the movement of the flange He is restricted by the foreign body guard 39 to prevent the bypass valve 11 from slipping off the threaded portion 36. This makes it possible to enhance ease of maintenance. [0068] In the present embodiment, further, simply fixing the device block 3 to the throttle body 2 enables the initialization of the bypass valve 11 and the valve seat 27. This makes it easy to ensure normal operations of the ISCV 32. Thus, assembling workability of the throttle body 2 and the device block 3 can be improved. [0069] In the present embodiment, as shown in Fig. 17, the annular shoulder portion 33a is formed in the receiving cavity 33 for the motor 12, and the Oring 35 is seated on the shoulder portion 33a. This Oring 35 corresponds to a sealing member of the present invention and the shoulder portion 33a corresponds to an attaching section on which the sealing means is seated. An aspiration groove 33b serving as a groove portion of the present invention communicating to atmosphere is formed in part of the shoulder portion 33a. This aspiration groove 33b provides communication between the inside and the outside of the shoulder portion 33a even when the Oring 35 is seated on the shoulder portion 33a. This aspiration groove 33b is located above the center axis of the receiving cavity 33 in Fig. 17. Accordingly, in case water enters through the aspiration groove 33b, a lower half of the shoulder portion 33a in Fig. 17 can serve as a water trap area for collecting the water therein. The aspiration groove 33b can contribute to keep a pressure difference low between the inside and the outside of the device block 3, thereby preventing water or the like from entering the inside of the device block 3. [0070] The present invention is not limited to the aforementioned embodiment and may be partially modified appropriately in configuration without departing from the essential characteristics thereof. [0071] (l) In the above embodiment, the device units provided in the device block 3 are the motor 12, the throttle sensor 14, a pressure sensor and an intake temperature sensor 29. At least one of the sensor 14, the pressure sensor and the intake temperature sensor 29 may be omitted. [0072] (2) In the above embodiment, the connector 30 is formed protruding obliquely downward of the throttle body 2. This connector may be provided protruding from the device block to extend upward of the throttle body. [0073] (3) In the above embodiment, the throttle body 2 is made of synthetic resin but may be made of metal such as aluminum by die-casting or other techniques. [0074] (4) In the above embodiment, the flange lie of the bypass valve 11 is used as a second foreign-body guard to prevent foreign bodies from entering the threaded portion 36. Alternatively, a small clearance enough to restrict passage of foreign bodies such as deposits is provided between the outer periphery of the base end of the bypass valve and the inner periphery of the sleeve to function as the second foreign-body guard in order to prevent entry of the foreign bodies to the threaded portion. INDUSTRIAL APPLICABILITY [0075] According to the present invention, as clearly from the above explanation, as to the engine intake device comprising the throttle body housing the throttle valve in a bore through which intake air is allowed to flow, the throttle valve being arranged to open and close the bore, and the device block fixed to the throttle body and housing at least one of sensors and device units, the engine intake device can be provided with improved workability of the bypass passage to ensure a reduction in entire size. As to the bypass valve arranged to open and close the bypass passage, furthermore, associated structures are simplified to provide an entirely compact engine intake device. Space saving for placing the device block can be attained to provide an entirely compact engine intake device. We Claim: 1. An intake device (1) of an engine, comprising a throttle body housing a throttle valve (5) in a bore (4) through which intake air is allowed to flow, the throttle valve (5) being arranged to open and close the bore (4), and a device block (3) that is fixed to the throttle body (2) and houses at least one of sensors and device units, the intake device (1) being characterized in that the throttle body (2) is provided with a mounting surface (9a) one side to which the device block (3) is attached, the mounting surface (9a) is provided with a bypass inlet port (16) and a bypass outlet port (17) respectively opening in the mounting surface (9a) on an upstream side and a downstream side of the bore with respect to the throttle valve (5) and also provided with a bypass groove (18) providing communication between the bypass inlet port (16) and the bypass outlet port (17), and the bypass inlet port (16), the bypass outlet port (17) and the bypass groove (18) constitute a bypass passage (10) for bypassing the intake air flowing in the bore (4), and the bypass inlet port (16), the bypass outlet port (17) and the bypass groove (18) are formed at once by casting. 2. The intake device (1) of an engine as claimed in claim 1, wherein the device block (3) is detachably coupled to the throttle body (2), the bypass passage (10) is formed substantially parallel to the bore (4), a portion around a port (16/17) of the bypass passage (10) serves as a valve seat (27) for an idle speed control valve (ISCV (32)). 3. The intake device (1) of an engine as claimed in claim 2, wherein the ISCV (32) is provided in the device block (3), and a valve element (11) of the ISCV (32) and the valve seat (27) are initialized when the device block (3) is coupled to the throttle body (2). 4. The intake device (1) of an engine as claimed in claim 2 or 3, wherein the device block (3) is provided with a mounting section (33) for mounting a motor of the ISCV (32), and the mounting section (33) is formed with an attaching section (33a) in which the sealing means is seated, and this attaching section (33 a) is formed with a groove (33b) communicating to atmosphere. 5. The intake device (1) of an engine as claimed in claim 4, wherein the device block (3) is provided with a sleeve (38) covering the valve element (11) of the ISCV (32), the valve element (11) is provided to be able to protrude from an opening of the sleeve (38), and the sleeve (38) is provided, in the inside of the opening, with a section protruding in an annular form toward the valve element (11) to restrict the flow of foreign body from the opening of the sleeve to the inside of the sleeve (38). 6. The intake device (1) of an engine as claimed in claim 5, wherein urging means is placed between the section for restricting the flow of foreign-body and the valve element (11) to urge the valve element (11) in a direction to move away from the valve seat (27), and an urging force of the urging means is determined to be larger than a sum of a force applied to the valve element (11) by negative pressure acting on the bypass passage (10) and a force of the output shaft (12a) of the motor (12) tending to move in an axis direction by vibration. 7. The intake device (1) of an engine as claimed in claim 6, wherein the throttle body (2) is provided with a throttle shaft (6) placed across the bore (4), the throttle valve (5) is supported on the throttle shaft (6), the valve element (11) is arranged to reciprocate relative to the valve seat (27), and the throttle shaft (6) and the valve element (11) are located so that an axis line of the throttle shaft (6) and a moving direction of the valve element (11) are parallel to each other. 8. The intake device (1) of an engine as claimed in claim 1, wherein: the device block (3) comprises a covering surface (3a) which covers the mounting surface (9a), the device block (3) is provided with at least the bypass valve (11) and an actuator for driving the bypass valve, the device block (3) is fixed to the mounting surface (9a), covering the bypass groove (18) by the covering surface, so that the bypass passage is formed of the bypass inlet port (16), the bypass outlet port (17), the bypass groove (18) and the covering surface. 9. The intake device (1) of an engine as claimed in claim 8, wherein the bypass valve (11) is located corresponding to the bypass outlet port (17), a portion around the bypass outlet port (17) opening in the mounting surface serves as a valve seat for the bypass valve. 10. The intake device (1) of an engine as claimed in claim 1, 2, 3, 8 and 9, wherein the device block (3) comprises a wiring connector protruding from the device toward an exterior space adjacent to an outer wall defining the bore (4) of the throttle body (2).

Full Text

DESCRIPTION INTAKE DEVICE OF ENGINE
TECHNICAL FIELD
[0001] The present invention relates to an intake device for controlling an amount of intake air to an engine, and to an intake device of an engine, including a throttle body housing a throttle valve in a bore through which intake air flows, the throttle valve being arranged to open and close the bore, and a device block fixed to the throttle body and housing at least one of sensors and device units.
BACKGROUND ART
[0002] As a device of this type, there are conventionally devices disclosed in Patent documents 1 and 2 mentioned below. An intake device disclosed in Patent document 1 is configured as below to improve workability and ease of assembly. Specifically, one side of a throttle body is formed as a mounting surface to which a device block is detachably fixed. The throttle body is formed with a bypass inlet port and a bypass outlet port which open in the mounting surface upstream and downstream of a bore relative to a throttle valve. The device block is formed with a bypass intermediate portion whose both ends are connected to the bypass inlet and outlet ports. The device block is also provided with a bypass valve, a throttle sensor, and others. The device block is fixed to the mounting surface, connecting the bypass inlet and outlet ports with the bypass intermediate part to form a bypass passage.
[0003] Further, an intake amount control device disclosed in Patent document 2 is configured as below to enable downsizing and improve
workability and easy of assembly. Specifically, one side of a throttle body is formed as a mounting surface parallel to a bore, and a mating surface of a control block is connected to the mounting surface. At least one of the mounting surface and the mating surface is formed with a bypass upstream groove communicating with an upstream portion of the bore and a bypass downstream groove communicating with a downstream portion of the bore. The control block is formed with a valve port providing communication between the bypass upstream groove and the bypass downstream groove. In this valve port, a bypass valve and its actuator are placed. These bypass valve and actuator are arranged in the control block in such a manner as to be parallel to the bore. [0004]
[Patent Document l] International publication No. WO2002/044541 (Jpn. Unexamined Patent Republication)
[Patent Document 2] Jpn. unexampled patent publication No. 2003-148303
DISCLOSURE OF INVENTION PROBLEMS TO BE SOLVED BY THE INVENTION
[0005] However, the devices disclosed in Patent documents 1 and 2 have to be formed with a vertical hole perpendicular to the bore or a lateral hole parallel to the bore in order to provide the bypass intermediate part or the valve port in the device block or the control block. Workability (die-cast molding, cutting, etc.) of such holes would be complicated, resulting in low flexibility in working. This restriction in working would cause an increase in size of the device, which is a stumbling block to downsizing. Air-fuel mixture from an engine may blow back to the bypass intermediate portion and the valve port. Therefore, inner walls of the bypass intermediate
portion and the valve port have to be made of a material resistant to gasoline and also there is concern that deposits adhere thereon. The complicated shapes of the ports would result in difficult maintenance for removing the deposits when have adhered to the bypass intermediate portion and the valve port. Furthermore, though relatively speaking, the deposits are likely to fix to the valve port, thereby causing an operation failure of the bypass valve.
[0006] The present invention has been made in view of the above circumstances and has a first purpose to provide an intake device of an engine, with enhanced workability of a bypass passage to achieve an entirely downsized design. A second purpose of the present invention is, besides the first purpose, to provide an intake device of an engine, with a simplified structure associated with a bypass valve for entirely downsizing. A third purpose of the present invention is, besides the first and second purposes, to provide an intake device of an engine, with a space-saving device block for compact design.
MEANS FOR SOLVING THE PROBLEMS
[0007] To achieve the above first purpose, the invention set forth in claim 1 provides an intake device of an engine, comprising a throttle body housing a throttle valve in a bore through which intake air is allowed to flow, the throttle valve being arranged to open and close the bore, and a device block that is fixed to the throttle body and houses at least one of sensors and device units, the intake device being characterized in that only the throttle body is formed with a bypass passage for bypassing the intake air flowing in the bore.
[0008] According to the above configuration, the bypass passage is provided only in the throttle body. This facilitates working (die-cast
molding, cutting, etc.) of the bypass passage, and the working flexibility can also be obtained. There is no need to form any passage in the device block and therefore no intake air is allowed to flow in the device block. [0009] To achieve the first purpose, the invention set forth in claim 2 provides that, in the invention set forth in claim 1, the bypass passage is formed in an arbitrary shape in the throttle body by casting. [0010] According to the above configuration of the invention, besides the operation of the invention set forth in claim 1, the bypass passage is formed in any shape by casting, so that flexible working (die cast molding, cutting, etc.) can be conducted at once.
[0011] To achieve the first purpose, the invention set forth in claim 3 provides that, in the invention set forth in claim 1 or 2, the device block is detachably coupled to the throttle body, the bypass passage is formed in substantially parallel to the bore, a portion around a port of the bypass passage serves as a valve seat for an idle speed control valve (ISCV). [0012] According to the above configuration of the invention, besides the operation of the invention set forth in claim 1 or 2, the portion around the port of the bypass passage functions as the valve seat for the ISCV and no additional valve seat is required. Further, the device block is detachably coupled to the throttle body, so that the device block can be detached as needed.
[0013] To achieve the first purpose, the invention set forth in claim 4 provides that, in the invention set forth in claim 3, the ISCV is provided in the device block, and a valve element of the ISCV and the valve seat are initialized when the device block is coupled to the throttle body. [0014] According to the above configuration of the invention, besides the operation of the invention set forth in claim 3, initialization of the valve element and the valve seat is carried out at the time when the throttle
body is coupled to the device block. This makes it possible to easily ensure a normal operation of the ISCV.
[0015] To achieve the first purpose, the invention set forth in claim 5 provides that, in the invention set forth in claim 4, the device block is provided with an mounting section for mounting a motor of the ISCV, and the mounting section is formed with a attaching section in which the sealing means is seated, and this attaching section is formed with a groove communicating to atmosphere.
[0016] According to the above configuration of the invention, besides the operation of the invention set forth in claim 4, a difference in pressure between the inside and the outside of the device block can be kept low through the groove.
[0017] To achieve the first purpose, the invention set forth in claim 6 provides that, in the invention set forth in claim 4 or 5, the device block is provided with a sleeve covering the valve element of the ISCV, the valve element is provided to be able to protrude from an opening of the sleeve, and the sleeve is provided with a foreign body guard in the opening. [0018] According to the above configuration of the invention, besides the operation of the invention set forth in claim 4 or 5, the foreign-body guard restricts the flow of foreign-bodies tending to enter the sleeve through its opening.
[0019] To achieve the second purpose, the invention set forth in claim 7 provides that, in the invention set forth in claim 6, urging means is placed between the foreign-body guard and the valve element for urging the valve element in a direction to move away from the valve seat, and an urging force of the urging means is determined to be larger than a sum of a force applied to the valve element by negative pressure acting on the bypass passage and a force of the output shaft of the motor tending to move in an
axis direction by vibration.
[0020] According to the above configuration of the invention, besides the operation of the invention set forth in claim 6, the output shaft of the motor is constantly urged to one side of the axial direction and positioned in place by the urging force of the urging means. It is possible to eliminate the need for an axially positioning member such as a ball bearing.
[0021] To achieve the second purpose, the invention set forth in claim 8 provides that in the invention set forth in claim 7, the throttle body is provided with a throttle shaft placed across the bore, the throttle valve is supported on the throttle shaft, the valve element is arranged to reciprocate relative to the valve seat, and the throttle shaft and the valve element are located so that an axis line of the throttle shaft and a moving direction of the valve element are parallel to each other. [0022] According to the above configuration of the invention, besides the operation of the invention set forth in claim 7, the throttle body is placed in a vehicle so that the axis line of the throttle shaft is perpendicular to the vibration direction of the engine. Thus, the vibrations of the throttle shaft in the axial direction can be comparatively reduced. Here, the valve element and the throttle shaft are arranged so that the moving direction of the valve element and the axis line of the throttle shaft are parallel to each other, and therefore the vibrations acting on the valve element in the moving direction thereof can be comparatively reduced. Consequently, the vibrations acting on the valve element are small and correspondingly the urging force of the urging means that urges the valve element can be set to be smaller. This smaller urging force of the urging means can contribute to a comparative reduction in power of the motor for driving the valve element. [0023] To achieve the first purpose, the invention set forth in claim 9
provides an intake device of an engine, comprising a throttle body including a bore through which intake air is allowed to flow and a throttle valve arranged to open and close the bore, the bore being provided with a bypass passage which bypasses the throttle valve, and a bypass valve is provided for opening and closing the bypass passage, the intake device being characterized in that the throttle body is provided with a mounting surface on one side, the intake device further comprises a device block including a covering surface which covers the mounting surface, the device block being detachably fixed to the mounting surface, the device block includes at least the bypass valve and an actuator for driving the bypass valve, the throttle body is formed with a bypass inlet port and a bypass outlet port which open in the mounting surface upstream and downstream of the bore from the throttle valve, the mounting surface is formed with a bypass groove providing communication between the bypass inlet port and the bypass outlet port, and the device block is fixed to the mounting surface, covering the bypass groove by the covering surface, so that the bypass passage is formed of the bypass inlet port, the bypass outlet port, the bypass groove, and the covering surface.
[0024] According to the above configuration of the invention, working (die cast molding, cutting, etc.) for forming the bypass passage is required only to make the bypass inlet port, the bypass outlet port, and the bypass groove in the mounting surface of the throttle body. This working can be conducted at, once by for example casting and cutting with a drill press. Working flexibility can also be obtained. Further, no passage needs to be formed in the device block and therefore no intake air is allowed to flow in the device block.
[0025] To achieve the second purpose, the invention set forth in claim 10 provides that, in the invention set forth in claim 9, the bypass valve is
located corresponding to the bypass outlet port, a portion around the bypass outlet port opening in the mounting surface serves as a valve seat for the bypass valve.
[0026] According to the above configuration of the invention, besides the operation of the invention set forth in claim 9, the portion around the bypass outlet port functions as a valve seat of the bypass valve, which can eliminate the need to provide an additional valve seat.
[0027] To achieve the third purpose, the invention set forth in claim 11 provides that, in the invention set forth in any of claims 1 through 10, the device block includes a wiring connector extending obliquely downward or upward of the throttle body from the device block.
[0028] According to the above configuration of the invention, besides the operation of the invention set forth in any of claims 1 through 10, the connector provided in the device block protrudes downward or upward of the throttle body so that the connector is placed in a space above or under the throttle body without protruding outside.
EFFECTS OF THE INVENTION
[0029] According to the invention set forth in claim 1, working (die cast molding, cutting, etc.) for the bypass passage is easy and working flexibility is attained. This can improve workability of the bypass passage and downsize the intake device.
[0030] According to the invention set forth in claim 1, besides the effects of the invention set forth in claim 1, flexible working (die cast molding, cutting, etc.) for the bypass passage can be performed at once, thereby improving workability of the bypass passage and downsizing the intake device. [0031] According to the invention set forth in claim 3, besides the effects
of the invention set forth in claim 1 or 2, no additional valve seat needs to be provided and therefore a simplified structure associated with the valve element can be achieved with a size reduction. In this regard, the intake device can also be downsized. Further, the device block can be detached from the throttle body as required, so that maintenance of the device block and the throttle body can be conducted readily.
[0032] According to the invention set forth in claim 4, besides the effects of the invention set forth in claim 3, it is possible to enhance assembling workability of the throttle body and the device block.
[0033] According to the invention set forth in claim 5, besides the effects of the invention set forth in claim 4, the difference in pressure between the inside and the outside of the device block can be kept small through the groove. This makes it possible to restrain water or the like from entering the device block.
[0034] According to the invention set forth in claim 6, besides the effects of the invention set forth in claim 4 or 5, the foreign-body guard can prevent foreign-bodies such as deposits contained in the intake air from entering the sleeve.
[0035] According to the invention set forth in claim 7, besides the effects of the invention set forth in claim 6, positioning of the output shaft of the motor can be performed without using any axially positioning member such as a ball bearing. Thus, the intake device can be manufactured at low cost and can provide enhanced accuracy of a flow rate.
[0036] According to the invention set forth in claim 8, besides the effects of the invention set forth in claim 7, the motor can be downsized as the power of the motor can be reduced, resulting in a downsized device block which houses the motor, thus achieving a more compact intake device. [0037] According to the invention set forth in claim 9, workability of the
bypass passage can be enhanced, thereby enabling downsizing of the
intake device.
[0038] According to the invention set forth in claim 10, besides the
effects of the invention set forth in claim 9, a simplified structure
associated with the bypass valve can be achieved, thereby enabling further
downsizing the intake device!
[0039] According to the invention set forth in claim 11, besides the
effects of the invention set forth in any of claims 1 through 10,
space-saving device block can be achieved, thereby further downsizing the
intake device.
BRIEF DESCRIPTION OF DRAWINGS [0040] Fig. 1 is a plan view showing an intake device.
Fig. 2 is a plan sectional view of the intake device.
Fig. 3 is a sectional view of the intake device taken along a throttle shaft.
Fig. 4 is a front view showing a mounting surface of a base.
Fig. 5 is a front view of part of the mounting surface.
Fig. 6 is a front view of part of the mounting surface.
Fig. 7 is a sectional view showing a circled part in Fig. 6.
Fig. 8 is a front view showing a covering surface of a device block.
Fig. 9 is a conceptual view showing a positional relationship between a bypass passage, a bypass valve, and a motor in a throttle body.
Fig. 10 is a sectional view showing the bypass valve and the motor.
Fig. 11 is an enlarged sectional view showing part of Fig. 10.
Fig. 12 is a sectional view showing a conventional structure related to a bypass valve and a step motor.
Fig. 13 is an enlarged sectional view showing a threaded portion of
the conventional structure.
Fig. 14 is an enlarged sectional view showing the threaded portion of the conventional structure.
Fig. 15 is a sectional view of a present embodiment shown in comparison with Fig. 12.
Fig. 16 is an enlarged sectional view a threaded portion of the present embodiment.
Fig, 17 is a front view showing the inside of the device block opposite to the covering surface.
Fig. 18 is a sectional view corresponding to Fig. 15.
Fig. 19 is a sectional view corresponding to Fig. 15.
EXPLANATION OF REFERENCE CODES [0041] 1 Intake device
2 Throttle body
3 Device block
3a Covering surface
4 Bore
5 Throttle valve
9a Mounting surface
10 Bypass passage
11 Bypass valve
Ha Distal end
12 Motor (Actuator)
12a Output shaft
14 Throttle sensor
16 Bypass inlet port
17 Bypass outlet port
18 Bypass groove
27 Valve seat
28 pressure-introducing port
29 Intake temperature sensor
30 Connector
32 ISCV
33 Receiving cavity (Mounting section)
33a Shoulder portion (Attaching section)
33b Aspiration groove (Groove)
35 0-ring (Sealing means)
38 Sleeve
39 Foreign-body guard
40 Auxiliary spring (Urging means)
BEST MODE FOR CARRYING OUT THE INVENTION [0042] A detailed description of a preferred embodiment of an intake device of an engine according to the present invention will now be given referring to the accompanying drawings.
[0043] Fig. 1 shows a plan view of the intake device 1 of engine in the present embodiment. Fig. 2 is a plan sectional view of the same intake device 1. This intake device 1 is placed in use in an intake passage of an engine of a motorcycle. This intake device 1 mainly includes a throttle body 2 and a device block 3 mounted and fixed to one side of the throttle body 2.
[0044] The throttle body 2 is made of synthetic resin in nearly cylindrical form, internally formed with a bore 4 through which intake air is allowed to flow. In this bore 4, a butterfly throttle valve 5 is placed to open and close the bore 4. The bore 4 forms an intake passage for
supplying air to the engine. The throttle valve 5 is fixed on a throttle shaft 6 rotatably disposed across the bore 4. One end of the throttle shaft 6 (a left end in Figs. 1 and 2) is fixedly coupled to a wire drum 7. This wire drum 7 is connected to a wire (not shown) connected to a throttle operating device. On the wire drum 7, a return spring 8 is mounted to urge the throttle valve 5 in a full closing direction.
[0045] On the other end of the throttle shaft 6 (a right end in Figs. 1 and 2), the throttle body 2 is integrally formed with a base 9 for fixing the device block 3. When the device block 3 is fixed to this base 9, a bypass passage 10 bypassing the throttle valve 5 in the bore 4 is formed. The device block 3 houses at least one of sensors and device units. In the present embodiment, the device units provided in the device block 3 are a bypass valve 11 corresponding to a valve element of the invention for opening/closing the bypass passage 10 and a step motor (hereinafter, simply referred to as a "motor") corresponding to an actuator of the invention for driving the valve 11. In the present embodiment, the device block 3 further mounts therein other device units such as a throttle sensor for detecting an opening degree of the throttle valve 5, a temperature sensor for detecting the temperature of intake air in the bore 4, and a pressure sensor for detecting the pressure of the intake air, as well as the bypass valve 11 and the motor 12.
[0046] Fig. 3 is a sectional view of the intake device 1 taken along the throttle shaft 6. Both ends of the throttle shaft 6 are rotatably supported by bearings 13. The right end of the throttle shaft 6 is coupled to a throttle sensor 14 built in the device block 3.
[0047] As shown in Figs. 1 and 2, the base 9 includes a mounting surface 9a to which the device block 3 is joined and fixed in such a manner as to be detachable. Fig. 4 is a front view of this mounting surface 9a.
At substantially the center of this mounting surface 9a, a boss 15 supporting the throttle shaft 6 is formed. In the mounting surface 9a, a bypass inlet port 16 and a bypass outlet port 17 are formed on both sides of the boss 15 in such a manner as to extend perpendicular to the bore 4. These bypass inlet port 16 and bypass outlet port 17 are formed in the mounting surface 9a of the throttle body 2 to open into an upstream side and a downstream side of the bore 4 respectively relative to the throttle valve 5. In the mounting surface 9a, further, a bypass groove 18 is formed in parallel to the bore 4 to connect the bypass inlet port 16 and the bypass outlet port 17. This bypass groove 18 is formed to curve along the upper side of the boss 15. In the present embodiment, the bypass inlet port 16, the bypass outlet port 17, and the bypass groove 18, which form the bypass passage 10 for bypass of the intake air flowing in the bore 4, are provided only in the throttle body 2. In the mounting surface 9a, besides, a sensing-part mounting hole 19 for the intake temperature sensor and a pressure-intake hole 20 for the pressure sensor are formed below the bypass inlet port 16 and the bypass outlet port 17 respectively. Around the pressure-intake hole 20, a fluid receiver 21 for receiving deposits or the like in case of entry of the deposits or the like. In the mounting surface 9a, a seal groove 22 is formed for receiving a gasket surrounding the aforementioned boss 15, bypass groove 18, sensing-part mounting hole 19, pressure-intake hole 20, fluid receiver 21, and others. In addition, a plurality of bolt holes 23 for fixing the device block 3 is provided on the periphery of the base 9.
[0048] Here, the seal groove 22 is of a unique shape with a combination of entirely complicated curves. Accordingly, as shown in Fig. 5, adjacent portions of the gasket 24 are separated especially at a boundary between the fluid receiver 21 and the bypass groove 18 and therefore each end of
the portions is likely to be broken and thus caught between the device block 3 and the throttle body 2 during assembly. In the present embodiment, therefore, as shown in Fig. 6 different from a configuration shown in Fig. 5, adjacent portions of the gasket 24 at the boundary between the fluid receiver 21 and the bypass groove 18 are formed continuous with each other so that part of the gasket 24 is placed in intersecting form with part of the fluid receiver 21. In Fig. 6, the intersecting area of the fluid receiver 21 and the gasket 24 is indicated by a circle S. Fig. 7 is a sectional view showing the area surrounded by the circle S of Fig. 6 in the state where the device block 3 is fixed to the base 9. As shown in Fig. 7, a communication portion 25 is formed in the device block 3. With this configuration, the communication portion 25 prevents part of the fluid receiver 21 from being blocked even when the device block 3 is fixed to the base 9. Since the adjacent portions of the gasket 24 are not separated, the gasket 24 can be set stably, ensuring sealing performance and easing assembly of the device block 3.
[0049] On the other hand, the device block 3 is provided with a covering surface 3a which covers the mounting surface 9a of the base 9. Fig. 8 is a front view of this covering surface 3 a. In substantially the center of this covering surface 3 a, a shaft hole 26 for the throttle shaft 6 is formed. In a nearly upper right part of the covering surface 3a, a bypass valve 11 is provided corresponding to the bypass outlet port 17. Accordingly, the portion around the bypass outlet port 17 functions as a valve seat 27 for the bypass valve 11. In other words" the portion around the opening forming the bypass passage 10 functions as the valve seat 27 for the bypass valve 11. In a right part of the covering surface 3 a, a pressure-introducing port 28 for a pressure sensor (not shown) is provided. This pressure-introducing port 28 is arranged to face the pressure-intake hole 20 shown in Fig. 4. In a left part of the covering surface 3 a, an
intake temperature sensor 29 is provided. This intake temperature sensor 29 is arranged to face the sensing-part mounting hole 19 shown in Fig. 4. The device block 3 also includes a connector 30 for wiring. This connector 30 is provided protruding from the lower side of the covering surface 3a to extend obliquely downward of the throttle body 2. The inclination of this connector 30 is determined to form an angle ranging from 20° to 70° with the center line of the throttle shaft 6 in Fig. 3. Furthermore, as shown in Fig. 8, a plurality of unloaded holes 31 is formed on the periphery of the device block 3, corresponding to the bolt holes 23 of the base 9.
[0050] The device block 3 is fixed to the base 9 in such a way that the covering surface 3a of the device block 3 contacts with the mounting surface 9a. This fixation is made by tightening bolts in the unloaded holes 32 and the bolt holes 23. When the bypass groove 18 is covered by the covering surface 3a as above, the bypass inlet port 16, the bypass outlet port 17, the bypass groove 18, and the covering surface 3a form the bypass passage 10.
[0051] Fig. 9 is a conceptual view showing a positional relationship between the bypass passage 10, the bypass valve 11, and the motor 12 in the throttle body 2. As seen in Fig. 9, the bypass valve 11 is arranged on the downstream side of the bypass passage 10 to face the bypass outlet port 17. This bypass valve 11 is movable toward or away from the bypass outlet port 17 by operation of the motor 12. At this time, the portion around the outlet port 17 serves as a valve seat 27 to allow opening/closing of the bypass passage 10, thereby controlling the opening degree of the bypass valve 11. By this control of opening degree, a flow rate of air allowed to flow in the bypass passage 10 is controlled. This bypass valve 11 is mostly driven while the throttle valve 5 is in a full closed position.
For idling control of an engine, the opening degree of the bypass valve 11 is adjusted to finely regulate an intake amount of air to be supplied to the engine through the bypass passage 10. In other words, these bypass valve 11 and motor 12 constitute a so-called idle speed control valve (ISCV) 32. In the present embodiment, this ISCV 32 is provided in the device block 3. [0052] Fig. 10 is a sectional view showing the bypass valve 11 and the motor 12 in the intake device 1. Fig. 11 is an enlarged view of part of Fig. 10. The device block 3 is formed with a receiving cavity 33 serving as a mounting section of the present invention for mounting the motor 12. The motor 12 is mounted in this receiving cavity 33 so that a pressurization spring 34 is interposed therebetween. An Oring 35 is placed between the outer periphery of the motor 12 and the receiving cavity 33. An output shaft 12a of the motor 12 is externally formed with a threaded portion 36. The bypass valve 11 is mounted on the output shaft 12a through a nut 37 engaging with the threaded portion 36. The bypass valve 11 is of a cap shape placed to sheathe the output shaft 12a. A distal end lla of the bypass valve 11 is sized to be insertable in the bypass outlet port 17. This distal end lla has a tapered conical shape with a shoulder portion lib at an end of an outer tapered surface. The bypass valve 11 is formed, at its base end, with a flange lie. The device block 3 is provided with a sleeve 38 which covers the bypass valve 11 and fitted in the bypass groove 18 of the base 9. The bypass valve 11 is movable, whereas the sleeve 38 is immovable. The distal end lla of the bypass valve 11 can be projected from an opening of the sleeve 38. The sleeve 38 includes a foreign body guard 39 extending inward in annular form in an opening of the sleeve 38. An auxiliary spring 40 serving as an urging means of the present invention is placed between this foreign body guard 39 and the flange lie of the bypass valve 11. This auxiliary spring 40 urges the bypass valve 11 in a
direction to move away from the valve seat 27.
[0053] Herein, the bypass valve 11 is configured to reciprocate rightward and leftward in Fig. 10 relative to valve seat 27 and also arranged so that the moving direction of the bypass valve 11 is parallel to an axial direction of the throttle shaft 6 (a horizontal direction in Fig. 10). In the present embodiment, the throttle body 2 is mounted in a two-wheel vehicle so that the axis line of the throttle shaft 6 is perpendicular to a vibration direction of the engine.
[0054] According to the configuration of the aforementioned bypass passage 10, the work of forming the bypass passage 10 is to make the bypass inlet port 16, bypass outlet port 17, and bypass groove 18 in the mounting surface 9a of the base 9 of the throttle body 2. This work can be performed at once by casting, cutting with a drill press, or others. In the present embodiment, the throttle body 3 is made of resin by integral molding. The bypass inlet port 16, the bypass outlet port 17, and the bypass groove 18 are formed at once by casting. In the present embodiment, accordingly, the inlet port 16, the bypass outlet port 17, and the bypass groove 18 are made by casting into arbitrary shapes to form the bypass passage 10. It is therefore possible to perform flexible working (die cast molding, cutting, etc.) at once. In the present embodiment, furthermore, the inlet port 16, the bypass outlet port 17, and the bypass groove 18 are provided only in the throttle body 2, which facilitates the working (die cast molding, cutting, etc.) for those ports 16 and 17, and groove 18 and provides flexibility in the working. Because of adoption of the casting, the bypass groove 18 can be formed in a curve extending along; the boss 15 as shown in Fig. 4. There is no need for making any passages in the device block 3 for forming the bypass passage 10. Thus, no intake air is allowed to flow in the device block 3. The throttle body 2 and the
device block 3 are therefore less subjected to restrictions in the work to form the bypass passage 10. Owing to no working restrictions, an increase in size of the throttle body 2 and the device block 3 can be restrained. This makes it possible to improve the workability of the inlet port 16, the bypass outlet port 17, and the bypass groove 18, and hence the workability of the bypass passage 10. Thus, the intake device 1 can be entirely compact in size. Since no passage is formed in the device block 3, no air-fuel mixture is allowed to flow back in the device block 3 from the engine. Accordingly, the inner structure of the device block 3 does not have to be made of a material resistant to gasoline, and therefore any concern about adhesion of deposits to the inner structure is not caused. Even if deposits adhere to the bypass groove 18, the device block 3 has only to be detached from the mounting surface 9a to open the bypass groove 18 and then a maintenance work to remove the deposits from the bypass groove 18 can be made readily.
[0055] According to the configuration of the aforementioned bypass passage 10, as shown in Fig. 10, the portion around the bypass outlet port 17 serves as the valve seat 27 for the bypass valve 11. No separate part needs to be added as the valve seat 27. This can simplify the structure associated with the bypass valve 11, avoiding a bulky configuration. In this view, the intake device 1 can also be compact in size. In the present embodiment, furthermore, the bypass valve 11 is configured to be driven vertically relative to the valve seat 27. The aforementioned bypass valve disclosed in Patent Document 2, configured to slide in parallel, is likely to cause deposits to enter and adhere to a portion in a narrow clearance.) However, the present embodiment is unlikely to cause such problem. Further, the device block 3 is detachably fixed to the throttle body 2, so that the device block 3 can be detached from the throttle body 2 as needed.
Detaching the device block 3 from the throttle body 2 can facilitate maintenance of the device block 3 and the throttle body 2. [0056] The threaded portion 36 of the output shaft 12a of the motor 12 is extremely precise and has small clearance. Due to this configuration, the performance of the bypass valve 11 may be deteriorated if foreign bodies enter the threaded portion 36. In the present embodiment, as shown in Fig. 10, the foreign-body guard 39 is provided in the opening of the sleeve
38, so that the flow of foreign bodies tending to enter the inside of the
sleeve 38 through its opening can be restricted by the foreign body guard
39. Thus, the foreign body guard 39 can prevent foreign bodies such as
deposits contained in intake air from entering the inside of the sleeve 38.
Even if the foreign bodies pass through the foreign body guard 39 to enter
the inside of the sleeve 38, the flange lie of the bypass valve 11 can serve
as a second foreign-body guard for preventing entry of the foreign bodies
into the threaded portion 36. As illustrated by an arrow in Fig. 11, when
the deposits blow back and collide with the distal end Ha of the bypass
valve 11, the blowing-back deposits flow along the outer periphery of the
distal end lla and is deflected outward at the shoulder portion 11. This
action can also prevent the deposits from entering the inside of the sleeve
38. Since entry of the deposits into the inside of the sleeve 38 and the
threaded portion 36 can be prevented as above, it is possible to prevent any
operation failures of the motor 12 and the bypass valve 11 that are caused
by deposits. The foreign-body guard 39 is provided in the immovable
sleeve 38, so that the bypass valve 11 can be compact in size and light in
weight and the bypass valve 11 can have a lower vibration-proof spring,
load. This can downsize the motor 12. This downsizing of the motor 12
contributes to a compact design of the intake device 1.
[0057] According to the configuration of the aforementioned bypass
passage 10, the device block 3 is formed with the connector 30 protruding obliquely downward of the throttle body 2 as shown in Fig. 3. Thus, the connector 30 is located in a space under the throttle body 2 without protruding outside. This makes it possible to save the space for placement of the device block 3. Also in this view, the intake device 1 can be compact in size. Since the connector 30 is hidden under the throttle body 2, the connector 30 can be protected and the appearance design of the intake device 1 can also be improved.
[0058] In general, protruding parts such as a connector tend to largely vibrate as they are positioned farther away from a holding portion (a central portion) of the throttle body. Thus, those parts are preferably provided as close to the central portion as possible. In the present embodiment, the connector 30 is provided at a slant relative to the device block 3, so that a compact design can be attained and the connector 30 can be positioned closer to the central portion of the throttle body 2 as compared with the case where the connector is positioned horizontally or vertically. It is therefore possible to reduce vibrations of the connector 30. This vibration reduction allows adoption of a narrow connector terminal, thus ensuring downsizing of the connector 30. An inclination angle of the connector 30 herein is set in a range of 20° to 70° relative to the center line of the throttle shaft 6 so that the connector 30 may be arranged in efficient and space-saving manner.
[0059] Other features of the intake device 1 in the present embodiment will be explained below.
Fig. 12 is a sectional view of a conventional structure related to a, bypass valve and a step motor. A bypass valve 101 of the conventional structure is threadably mounted on a threaded portion 103 of an output shaft 102a of a step motor 102 of the conventional structure. A flange
lOla is formed in the distal end portion of the bypass valve 101. An auxiliary spring 105 is placed between the flange lOla and a ball bearing 104 of the output shaft 102a. This auxiliary spring 105 urges the bypass valve 101 toward a valve seat 106. The direction in which bypass valve 101 is urged by the auxiliary spring 105 is the direction in which the valve
101 moves at the time of initialization.
[0060] Fig. 13 is an enlarged sectional view showing a state of the threaded portion 103 at the time of controlling a flow rate of intake air allowed to flow in the bypass passage by the bypass valve 101 of the conventional structure. In the conventional structure configuration, by the full-closing initialization in which the bypass valve 101 is caused to abut against the valve seat 106, the auxiliary spring 105 urges the bypass valve 101 in a direction to be influenced by backlash of the threaded portion 103. In other words, as shown in Fig. 13, the bypass valve 101 is urged in a direction (an arrow direction) to move away from the step motor
102 by the auxiliary spring 105. The output shaft 102a is restricted in its
axial movement by the ball bearing 104. Thus, backlash BR occurs in the
threaded portion 103.
[0061] Fig. 14 is an enlarged sectional view showing the threaded portion 103 at the time of initialization. In the conventional structure, by the initialization, the bypass valve 101 abuts against the valve seat 106 and is restrained from moving. On the other hand, the threaded portion
103 of the output shaft 102a is moved by a clearance corresponding to the
backlash BR. This backlash BR is an allowance of movement of the
bypass valve 101, which causes variations in the flow rate of intake air.
[0062] Fig. 15 is a sectional view of the configuration of the present
embodiment shown in comparison with Fig. 12. In the present
embodiment, the bypass valve 11 and the valve seat 27 can be initialized at
the time when the device block 3 is fixed to the throttle body 2. In Fig. 15, the pressurization spring 34 presses the motor 12 against the device block 3 to prevent the motor 12 from shaking due to the vibration. Here, the "load" of the pressurization spring 34 is set at a value equal to or larger than the value obtained by multiplying the "mass" of the motor 12 by the "guaranteed vibration acceleration". Assuming that the "mass" is "15g" and the "guarantee vibration acceleration" is "30G", for example, the "load" of the pressurization spring 34 is "450 gf or larger. [0063] As the auxiliary spring 40, a spring having a tapered shape (a taper spring) is used, which can reduce a contact length, and the ISCV 32 can be reduced in length in an extension and contraction direction. Here, the auxiliary spring 40 presses the output shaft 12a against a plate 41 opposite the auxiliary spring 40, making it possible to hold the bypass valve 11 in place in its axial direction. The "load" of the auxiliary spring 40 is determined according to the force (1) applied to the bypass valve 11 by negative pressure and the force (2) of the mass of a rotor system tending to move away from the plate 41 by vibration. For example, for the force (1), the bypass valve 11 is pulled down by a force of " 1.7N" at the maximum in the case where the inner diameter of the valve seat 27 is "Φ6" (6 mm in diameter) and a positive/negative differential pressure of the bypass valve 11 is "60 kPa". For the force (2), a force of "0.9 N" is applied in the case where the vibration is "30 G" and the mass of the rotor system (a total mass of the rotor, the bypass valve and the nut) is '"3 g". In the present embodiment, the load of the auxiliary spring 40 is determined to be larger than the sum of the above forces (1) and (2). Specifically, the urging force of the auxiliary spring 40 is determined to be larger than the sum of the force applied to the bypass valve 11 by the negative pressure acting on the bypass groove 18 and the moving force of the output shaft 12a of the motor
12 tending to move in the axial direction by the vibration. Because of the load of the auxiliary spring 40 being determined to be larger than the sum of the forces (l) and (2), the output shaft 12a is normally pressed against the plate 41. As to the motor 12, the positioning of the output shaft 12a can be conducted by use of only a slide bearing 42 without using any positioning member such as a ball bearing. Accordingly, the intake device 1 can be manufactured at low cost and the flow rate accuracy of the intake device 1 can be enhanced.
[0064] In the present embodiment, furthermore, the throttle body 2 is mounted in a two-wheel vehicle so that the axis line of the throttle shaft 6 is perpendicular to a vibration direction of the engine. Accordingly, the engine vibration acting on the throttle shaft 6 in the axial direction can be relatively reduced. Here, the bypass valve 11 and the throttle shaft 6 are located so that the moving direction of the bypass valve 11 and the axis line of the throttle shaft 6 are parallel to each other. The vibration acting on the valve 11 in the moving direction of the valve 11 will be relatively reduced. By the reduction in vibration acting on the bypass valve 11, it is consequently possible to determine the urging force of the auxiliary spring 40 to be relatively small for urging the valve 11. Further, the smaller the urging force of the auxiliary spring 40, the output of the motor 12 for driving the bypass valve 11 can be determined to be relatively smaller. This makes it possible to downsize the motor 12 by the reduction of output of the motor 12, leading to size reduction of the device block 3 which houses the motor 12. In this regard, the intake device 1 can be made more compact.
[0065] The auxiliary spring 40 is designed to have an urging force that acts in a direction opposite the direction to pull the bypass valve 11 by negative pressure and is almost equal to the load calculated by summing
up the forces (l) and (2). Thus, the force of pulling the bypass valve 11 by negative pressure acts in a direction to be canceled by the force of the auxiliary spring 40. Therefore, the stress on the threaded portion 36 that repeatedly reciprocates for controlling a flow rate of intake air is mitigated, reducing abrasion of a sliding part to ensure a long life. In the ISCV 32 of the present embodiment where the valve seat 27 is placed downstream from the bypass valve 11, the bypass valve 11 is urged by the auxiliary spring 40 in a direction opposite to the direction to pull down the bypass valve 11 by negative pressure. This makes it possible to make the moving direction of the output shaft 12a opposite to the urging force on the nut 37 as shown in Fig. 16 at the initialization executed by abutment against the valve seat 27. This configuration can cancel the backlash of the threaded portion 36 and, differently from the conventional structure shown in Fig. 12, it is therefore possible to restrain the flow rate of intake air from varying under the influence of the backlash.
[0066] Fig. 17 shows the inside of the device block 3 opposite to the covering surface 3a. In an upper left part in Fig. 17, a receiving cavity 33 in which the motor 12 is assembled. In an upper right part in Fig. 17, further, the throttle sensor 14 is located. When the thus configured device block 3 is to be fixed to the base 9, it is positioned with reference to the throttle sensor 14. At this time, accordingly, an axis deviation Ad occurs between the bypass valve 11 coupled to the motor 12 and the valve seat 27 of the base 9 as shown in Fig. 18. This may cause the bypass valve 11 to abut against one side of the valve seat 27 at the time of initialization of the ISCV 32, which makes it impossible to execute normal initialization. In the present embodiment, however, there is a difference between the inner diameter D of the receiving cavity 33 and the outer diameter d of the motor 12, as shown in Fig. 18. In other word, the inner
diameter D is determined to be slightly larger than the outer diameter d. In the present embodiment, the inner diameter D is set at "15 mm" and the outer diameter d is set in a range of "14 mm to 14.8 mm". Further, the receiving cavity 33 is provided with a shoulder portion 33a on which an 0-ring 35 is placed, so that the motor 12 is made floating in a radial direction by the 0-ring 35 and is held in a thrust direction by the pressurization spring 34. In this way, the motor 12 is circumferentially made floating by the 0-ring 35. At the initialization of the ISCV 32, although the distal end Ha of the bypass valve 11 may abut against one side of the valve seat 27, the inclination of the motor 12 can be accepted by a reactive force of the 0-ring 35, thereby allowing the bypass valve 11 to go in the bypass outlet port 17 along the valve seat 27 as shown in Fig. 19. This can absorb the axis deviation Ad between the bypass valve 11 and the valve seat 27 accordingly.
[0067] In the ISCV of the conventional structure shown in Fig. 12, having no stopper element for the bypass valve 101, the bypass valve 101 tends to slip off the threaded portion 103 when the initialization of the ISCV is made in error while the ISCV remains demounted from a counterpart member having the valve seat 106. Then, returning of the bypass valve 101 could not be easily made without a special drive circuit. In the present embodiment, on the other hand, the inner diameter of the foreign body guard 39 is smaller than the outer diameter of the flange He of the bypass valve 11 as shown in Figs. 10 and 11. Accordingly, even where the bypass valve 11 is moved in a protruding direction while the device block 3 remains detached from the throttle body 2, the movement of the flange He is restricted by the foreign body guard 39 to prevent the bypass valve 11 from slipping off the threaded portion 36. This makes it possible to enhance ease of maintenance.
[0068] In the present embodiment, further, simply fixing the device block 3 to the throttle body 2 enables the initialization of the bypass valve 11 and the valve seat 27. This makes it easy to ensure normal operations of the ISCV 32. Thus, assembling workability of the throttle body 2 and the device block 3 can be improved.
[0069] In the present embodiment, as shown in Fig. 17, the annular shoulder portion 33a is formed in the receiving cavity 33 for the motor 12, and the Oring 35 is seated on the shoulder portion 33a. This Oring 35 corresponds to a sealing member of the present invention and the shoulder portion 33a corresponds to an attaching section on which the sealing means is seated. An aspiration groove 33b serving as a groove portion of the present invention communicating to atmosphere is formed in part of the shoulder portion 33a. This aspiration groove 33b provides communication between the inside and the outside of the shoulder portion 33a even when the Oring 35 is seated on the shoulder portion 33a. This aspiration groove 33b is located above the center axis of the receiving cavity 33 in Fig. 17. Accordingly, in case water enters through the aspiration groove 33b, a lower half of the shoulder portion 33a in Fig. 17 can serve as a water trap area for collecting the water therein. The aspiration groove 33b can contribute to keep a pressure difference low between the inside and the outside of the device block 3, thereby preventing water or the like from entering the inside of the device block 3. [0070] The present invention is not limited to the aforementioned embodiment and may be partially modified appropriately in configuration without departing from the essential characteristics thereof. [0071] (l) In the above embodiment, the device units provided in the device block 3 are the motor 12, the throttle sensor 14, a pressure sensor and an intake temperature sensor 29. At least one of the sensor 14, the
pressure sensor and the intake temperature sensor 29 may be omitted. [0072] (2) In the above embodiment, the connector 30 is formed protruding obliquely downward of the throttle body 2. This connector may be provided protruding from the device block to extend upward of the throttle body.
[0073] (3) In the above embodiment, the throttle body 2 is made of synthetic resin but may be made of metal such as aluminum by die-casting or other techniques.
[0074] (4) In the above embodiment, the flange lie of the bypass valve 11 is used as a second foreign-body guard to prevent foreign bodies from entering the threaded portion 36. Alternatively, a small clearance enough to restrict passage of foreign bodies such as deposits is provided between the outer periphery of the base end of the bypass valve and the inner periphery of the sleeve to function as the second foreign-body guard in order to prevent entry of the foreign bodies to the threaded portion.
INDUSTRIAL APPLICABILITY
[0075] According to the present invention, as clearly from the above explanation, as to the engine intake device comprising the throttle body housing the throttle valve in a bore through which intake air is allowed to flow, the throttle valve being arranged to open and close the bore, and the device block fixed to the throttle body and housing at least one of sensors and device units, the engine intake device can be provided with improved workability of the bypass passage to ensure a reduction in entire size. As to the bypass valve arranged to open and close the bypass passage, furthermore, associated structures are simplified to provide an entirely compact engine intake device. Space saving for placing the device block can be attained to provide an entirely compact engine intake device.

We Claim:
1. An intake device (1) of an engine, comprising a throttle body housing a throttle
valve (5) in a bore (4) through which intake air is allowed to flow, the throttle
valve (5) being arranged to open and close the bore (4), and a device block (3)
that is fixed to the throttle body (2) and houses at least one of sensors and device
units, the intake device (1) being characterized in that
the throttle body (2) is provided with a mounting surface (9a) one side to which the device block (3) is attached,
the mounting surface (9a) is provided with a bypass inlet port (16) and a bypass outlet port (17) respectively opening in the mounting surface (9a) on an upstream side and a downstream side of the bore with respect to the throttle valve (5) and also provided with a bypass groove (18) providing communication between the bypass inlet port (16) and the bypass outlet port (17), and
the bypass inlet port (16), the bypass outlet port (17) and the bypass groove (18) constitute a bypass passage (10) for bypassing the intake air flowing in the bore (4), and the bypass inlet port (16), the bypass outlet port (17) and the bypass groove (18) are formed at once by casting.
2. The intake device (1) of an engine as claimed in claim 1, wherein the device block (3) is detachably coupled to the throttle body (2), the bypass passage (10) is formed substantially parallel to the bore (4), a portion around a port (16/17) of the bypass passage (10) serves as a valve seat (27) for an idle speed control valve (ISCV (32)).
3. The intake device (1) of an engine as claimed in claim 2, wherein the ISCV (32) is provided in the device block (3), and a valve element (11) of the ISCV (32) and the valve seat (27) are initialized when the device block (3) is coupled to the throttle body (2).
4. The intake device (1) of an engine as claimed in claim 2 or 3, wherein the device block (3) is provided with a mounting section (33) for mounting a motor of the ISCV (32), and the mounting section (33) is formed with an attaching section (33a) in which the sealing means is seated, and this attaching section (33 a) is formed with a groove (33b) communicating to atmosphere.

5. The intake device (1) of an engine as claimed in claim 4, wherein the device block (3) is provided with a sleeve (38) covering the valve element (11) of the ISCV (32), the valve element (11) is provided to be able to protrude from an opening of the sleeve (38), and the sleeve (38) is provided, in the inside of the opening, with a section protruding in an annular form toward the valve element (11) to restrict the flow of foreign body from the opening of the sleeve to the inside of the sleeve (38).
6. The intake device (1) of an engine as claimed in claim 5, wherein urging means is placed between the section for restricting the flow of foreign-body and the valve element (11) to urge the valve element (11) in a direction to move away from the valve seat (27), and an urging force of the urging means is determined to be larger than a sum of a force applied to the valve element (11) by negative pressure acting on the bypass passage (10) and a force of the output shaft (12a) of the motor (12) tending to move in an axis direction by vibration.
7. The intake device (1) of an engine as claimed in claim 6, wherein the throttle body (2) is provided with a throttle shaft (6) placed across the bore (4), the throttle valve (5) is supported on the throttle shaft (6), the valve element (11) is arranged to reciprocate relative to the valve seat (27), and the throttle shaft (6) and the valve element (11) are located so that an axis line of the throttle shaft (6) and a moving direction of the valve element (11) are parallel to each other.
8. The intake device (1) of an engine as claimed in claim 1, wherein:
the device block (3) comprises a covering surface (3a) which covers the mounting
surface (9a),
the device block (3) is provided with at least the bypass valve (11) and an actuator
for driving the bypass valve,
the device block (3) is fixed to the mounting surface (9a), covering the bypass
groove (18) by the covering surface, so that the bypass passage is formed of the
bypass inlet port (16), the bypass outlet port (17), the bypass groove (18) and the
covering surface.

9. The intake device (1) of an engine as claimed in claim 8, wherein the bypass valve (11)
is located corresponding to the bypass outlet port (17), a portion around the bypass
outlet port (17) opening in the mounting surface serves as a valve seat for the bypass
valve.
10. The intake device (1) of an engine as claimed in claim 1, 2, 3, 8 and 9, wherein the device block (3) comprises a wiring connector protruding from the device toward an exterior space adjacent to an outer wall defining the bore (4) of the throttle body (2).

Documents:

http://ipindiaonline.gov.in/patentsearch/GrantedSearch/viewdoc.aspx?id=wqA2Jd4vW/DYTL1TGLsbKw==&loc=+mN2fYxnTC4l0fUd8W4CAA==

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Patent Number

268385

Indian Patent Application Number

5324/DELNP/2007

PG Journal Number

36/2015

Publication Date

04-Sep-2015

Grant Date

27-Aug-2015

Date of Filing

10-Jul-2007

Name of Patentee

AISAN KOGYO KABUSHIKI KAISHA

Applicant Address

1-1, KYOWA-CHO 1-CHOME, OBU-SHI, AICHI, 474-8588 (JP)

Inventors:

#	Inventor's Name	Inventor's Address
1	MIKIO HAMADA	C/O AISAN KOGYO KABUSHIKI KAISHA,1-1, KYOWA-CHO 1-CHOME, OBU-SHI, AICHI, 474-8588 (JP)
2	TAKEHIDE NAKAMURA	C/O AISAN KOGYO KABUSHIKI KAISHA,1-1, KYOWA-CHO 1-CHOME, OBU-SHI, AICHI, 474-8588 (JP)
3	NARUTO ITO	C/O AISAN KOGYO KABUSHIKI KAISHA,1-1, KYOWA-CHO 1-CHOME, OBU-SHI, AICHI, 474-8588 (JP)

PCT International Classification Number

F02M 69/32

PCT International Application Number

PCT/JP2006/300722

PCT International Filing date

2006-01-19

PCT Conventions:

#	PCT Application Number	Date of Convention	Priority Country
1	2005-028486	2005-02-04	Japan