Title of Invention	INSULATOR STRUCTURE
Abstract	To provide an insulator structure capable of expanding an adjustable range of engine output characteristics, while allowing a restricted opening to be made even smaller. [Solving Means] The structure is for an insulator 11 that connects an intake path 5 on a side of an internal combustion engine with an intake path 8 on a side of a throttle device 3, The intake path 5 connects to a combustion chamber 4. The throttle device 3 adjusts and sets a flow rate of fuel and air supplied to the combustion chamber 4. An intake path is thereby formed that provides communication between the two intake paths 5, 8. The insulator 11 includes a limiter 65 for restricting an area through which the fuel and the air flow. Further, the limiter 65 is formed into a funnel-like shape having a smaller path cross-sectional area toward a downstream direction of the intake path. [Selected Drawing] Fig, 2

Title of Invention

INSULATOR STRUCTURE

Abstract

To provide an insulator structure capable of expanding an adjustable range of engine output characteristics, while allowing a restricted opening to be made even smaller. [Solving Means] The structure is for an insulator 11 that connects an intake path 5 on a side of an internal combustion engine with an intake path 8 on a side of a throttle device 3, The intake path 5 connects to a combustion chamber 4. The throttle device 3 adjusts and sets a flow rate of fuel and air supplied to the combustion chamber 4. An intake path is thereby formed that provides communication between the two intake paths 5, 8. The insulator 11 includes a limiter 65 for restricting an area through which the fuel and the air flow. Further, the limiter 65 is formed into a funnel-like shape having a smaller path cross-sectional area toward a downstream direction of the intake path. [Selected Drawing] Fig, 2

Full Text	[Name of Document] Specification [Title of the Invention] Insulator Structure [Technical Field] [0001] The present invention relates to a structure of an insulator that connects an intake path on the side of an internal combustion engine and an intake path on the side of a throttle device, thereby guiding fuel and air supplied from the throttle device into a combustion chamber. [Background Art] [0002] Conventionally, an insulator is known that guides fuel and air supplied from a throttle device into a combustion chamber of an internal combustion engine, while shutting down vibration from the internal combustion engine. Such an insulator typically connects an intake path on the side of the internal combustion engine and an intake path on the side of the throttle device of a carburetor type or a fuel injection type for adjusting and setting a flow rate of the fuel and the air supplied to the internal combustion engine. The insulator thereby forms an intake path providing communication between the intake path on the side of the internal combustion engine and the intake path on the side of the throttle device. Typically, the insulator is a connection member connecting the intake path on the side of the internal combustion engine and the intake path on the side of the throttle device. The insulator is to be capable of changing an internal path configuration without changing an appearance thereof. To achieve this end, a known insulator includes therein an orifice plate having a restricted opening that reduces a cross-sectional area of the path. The known insulator thereby restricts the amount of air flowing into the combustion chamber, so that engine output characteristics according to the specifications of a vehicle can be achieved. (See, for example, Patent Document 1.) [Patent Document 1] Japanese Patent Laid-open No. Hei 6-285872 [Disclosure of the Invention] [Problem to be Solved by the Invention] [0004] As described above, the known insulator is capable of varying the engine output characteristics using the restricted opening of variable opening area formed therein. Accordingly, there is a need for expanding an adjustable range of the output characteristics by making the restricted opening even smaller. Decreasing the opening area of the restricted opening, however, results in part of an atomized fuel flowing down with the air being unable to flow past the restricted opening. That part of the atomized fuel then collides with a peripheral edge of the restricted opening, being liquefied and then stagnating inside the intake path. As a result, an air-fuel mixture having an unstable air-fuel ratio is supplied to the combustion chamber. This leads to a problem of reduced engine combustion efficiency, making it impossible to improve driveability or exhaust emission performance. [0005] The throttle device of the carburetor type has an arrangement, in which fuel atomized by an intake air stream flows through the insulator with the intake air. Thanks to this arrangement, the restricted opening can be made smaller to a certain degree if the restricted opening is disposed near a peripheral wall on the side of a fuel delivery jet. With the throttle device using a fuel injection valve injecting fuel into the intake path, however, the atomized fuel is injected having a vector different from that of the intake air stream. This makes it particularly difficult to make the restricted opening smaller, [0006] The present invention has been made to solve these problems and it is an object of the present invention to provide a structure for the insulator capable of expanding the adjustable range of the engine output characteristics, while allowing the restricted opening to be made even smaller. [Means for Solving the Problem] [0007] To achieve the foregoing object, according to an embodiment of the present invention, there is provided a structure of an insulator. The insulator structure connects a first intake path on a side of an internal combustion engine (for example, an intake path 5 according to an embodiment of the present invention) with a second intake path on a side of a throttle device (for example, an intake path 8 according to the embodiment of the present invention), The first intake path connects to a combustion chamber. The throttle device adjusts and sets a flow rate of fuel and air supplied to the combustion chamber. An intake path providing communication between the first and the second intake paths is thereby formed- The insulator functions to guide the fuel and the air supplied from the throttle device into the combustion chamber. In this insulator structure, the insulator includes a limiter for restricting an area through which the fuel and the air flow. Further, the limiter is formed into a funnel-like shape having a smaller path cross-sectional area toward a downstream direction of the intake path, [0008] In accordance with the embodiment of the present invention, the throttle device includes a fuel injection valve (for example, an injector 3 5 according to the embodiment of the present invention) injecting fuel into the intake path. The fuel injection valve is disposed in an inclined position, in which an injection direction of the fuel is inclined toward a downstream direction of the intake path. Further, the limiter is opened and formed so as to be oriented toward an injection port of fuel in the fuel injection valve, [0009] Preferably, the insulator includes thereinside a partition wall connecting to an outer tube for covering an outer periphery to thereby partition the intake path between an upstream side and a downstream side. The limiter should be formed with the outer tube into the partition wall through one piece molding. [0010] Preferably, the insulator includes thereinside a sheet member (for example, orifice plates 60, 70, 80 according to embodiments of the present invention) that partitions the intake path between an upstream side and a downstream side. The limiter should be formed in the sheet member. [0011] Preferably, the opening in the limiter (for example, restricted openings 67, 77, 77', 87 according to the embodiments of the present invention) is offset on a side of the fuel injection valve (the side, on which the fuel injection valve is disposed) relative to an inside diameter centerline of a connection portion in the insulator with the second intake path on the side of the throttle device (for example, a centerline C8 according to the embodiment of the present invention), Further, a connection portion in the insulator with the first intake path on the side of the internal combustion engine should be offset on a side opposite to the fuel injection valve relative to the inside diameter centerline (on the side opposite to that on which the fuel injection valve is disposed). It is further preferable that the limiter be open at an upward position in the intake path, and the limiter include a communication hole formed downwardly therein along an inner wall surface of the outer tube. Such a communication hole provides communication between the upstream side and the downstream side. [Effects of the Invention] [0013] The arrangement, in which the insulator includes the limiter and the limiter is formed into a funnel-like shape having a smaller path cross-sectional area toward the downstream direction of the intake path, offers the following advantages. Specifically, an intake air and an atomized fuel are deflected by the funnel-like limiter, flowing downwardly along a wall surface of the limiter. Accordingly, the atomized fuel can be guided efficiently into the intake path on the internal combustion engine side. This makes it possible to make the limiter opening even smaller, thereby expanding the adjustable range of engine output characteristics. [0014] If a throttle device of the fuel injection type having a fuel injection valve is used, arrangements can be made, in which the fuel injection valve is disposed in an inclined position, in which the injection direction of the fuel is inclined toward the downstream direction of the intake path, and the limiter is opened and formed so as to be oriented toward the injection port of fuel in the fuel injection valve. According to these arrangements, a vector direction of an intake air stream and a vector direction of an injected fuel can be brought mutually close together. In addition, of the injected fuel, which expands conically from the injection port, that part closest to the limiter (for example, an upper area according to the embodiment of the present invention) is allowed to smoothly flow downwardly along the funnel shape of the limiter. Accordingly, the injected fuel can be efficiently guided into the intake path of the internal combustion engine side even in the throttle device of the fuel injection type, in which a fuel passage rate poses a major problem and it is difficult to make the limiter smaller in diameter. The restricted opening can therefore be made smaller in diameter and the adjustable range of the engine output characteristics can be expanded. [0015] The arrangements, in which the insulator includes thereinside the partition wall that partitions the intake path between the upstream side and the downstream side, and the limiter is formed with the outer tube into the partition wall through one piece molding, offers the following advantages. Specifically, the insulator structure can be simplified for streamlined production processes and enhanced productivity. According to the arrangements, in which the insulator includes thereinside the sheet member that partitions the intake path between the upstream side and the downstream side, and the limiter is formed in the sheet member, molding the sheet member having different opening areas and opening shapes permits easy production of insulators according to varying engine characteristics without having to change the molds of the insulators. [0016] The arrangements, in which the opening in the limiter is offset on the side of the fuel injection valve relative to the inside diameter centerline of the connection portion in the insulator with the second intake path on the side of the throttle device, and the connection portion in the insulator with the first intake path on the side of the internal combustion engine is offset on the side opposite to the fuel injection valve relative to the inside diameter centerline, offers the following advantages. Specifically, according to these arrangements, the first intake path on the side of the internal combustion engine is offset in the vector direction of the injected fuel. This allows the injected fuel to flow smoothly to an area near a center of the first intake path on the side of the internal combustion engine. Further, the intake path from the throttle device to the combustion chamber can be formed into a mild curve, while the connection portion with the first intake path on the side of the internal combustion engine can be made smaller to build a compact insulator. [0017] The arrangements, in which the limiter is open at the upward position in the intake path, and the limiter includes the communication hole, which provides communication between the upstream side and the downstream side, formed downwardly therein along the inner wall surface of the outer tube, offers the following advantages. Specifically, any part of the fuel, if liquefied in the intake path as a result of its having been in contact with the limiter, is made to flow downwardly so as to be prevented from stagnating. Further, the communication hole is isolated from the limiter. The stagnant gas near the communication hole is therefore less subject to effect from the intake air flowing backward. This leads to a stabilized mixture, thus enhancing engine performance. [0018] The present invention can therefore provide an insulator structure capable of expanding the adjustable range of the engine output characteristics, while allowing the restricted opening to be made even smaller, [Best Mode for Carrying out the Invention] [0019] An insulator structure according to preferred embodiments of the present invention will be described below with reference to the accompanying drawings. Figs. 1 and 2 are views showing an arrangement of the insulator structure according to a first embodiment of the present invention, as applied to a motorcycle. The arrangement of the insulator structure according to the first embodiment of the present invention will be first briefly described with reference to Figs. 1 and 2. For convenience sake, an arrow U in Fig* 1 is an upward direction and an arrow R (rearward of a vehicle body) in Fig. 1 is a rightward direction unless otherwise specified. [0020] An insulator 11 is disposed between an engine 2 and a throttle device 3. The engine 2 produces a power drive. The throttle device 3 adjusts and sets a flow rate of fuel and air supplied to the engine 2. The insulator 11 connects an intake path 5 on the side of the engine 2 with an intake path 8 on the side of the throttle device 3, The intake path 5 on the engine side connects to a combustion chamber 4. The intake path 8 on the throttle device side connects to an air cleaner 7, The insulator 11 thereby forms an intake path providing communication between the intake path 5 on the engine side and the intake path 8 on the throttle device side. In this configuration, the insulator 11 guides fuel and air supplied from the throttle device 3 into the combustion chamber 4. [0021] The engine 2 is illustrated as a water-cooled engine of an overhead camshaft (OHC) type. A cylinder head 21 includes an intake path 5 and an exhaust path 6 formed therein. Both the intake path 5 and the exhaust path 6 connect to the combustion chamber 4. The cylinder head 21 vertically slidably supports an intake valve 22 and an exhaust valve 23. The intake valve 22 opens and closes an intake port 5p opening to the combustion chamber 4, The exhaust valve 23 opens and closes an exhaust port 6p opening to the combustion chamber 4. The intake valve 22 and the exhaust valve 23 are urged at all times upwardly by valve springs 24, 24, respectively, inserted between the cylinder head 21 and the respective valves. Rocker arms 26a, 26b are pivotally supported, respectively, by the cylinder head 21. The rocker arms 26a, 26b are pivotally moved by a cam formed on a camshaft 25. An upper end of each of the intake valve 22 and the exhaust valve 23 is supported in abutment with the rocker arms 26a, 26b, respectively. The rocker arms 26a, 26b are pivotally moved by rotation of the camshaft 25 connected via a cam chain and a sprocket not shown. In accordance with the pivotal motion of the rocker arms 26a, 26b, the intake valve 22 and the exhaust valve 23 are pushed downwardly to thereby open or close the intake port 5p and the exhaust port 6p, respectively. Specifically, the intake valve 22 and the exhaust valve 23 are raised or lowered according to the position in a vertical direction of a piston 29 connected to a crankshaft 28 via a connecting rod 27. The intake port 5p and the exhaust port 6p are opened or closed in synchronism with the rotation of the crankshaft 28, The throttle device 3 is illustrated as being a fuel injection type using an injector (a fuel injection valve) as fuel delivery means. The throttle device 3 includes a throttle valve 32 and an injector 35. The throttle valve 32 of a disk shape is pivotally movably disposed about an axis extending in a direction orthogonal to an axis of the intake path 8 (in a direction orthogonal to the paper surface in Figs. 1 and 2) . The throttle valve 32 thereby opens or closes the intake path 8. The injector 35, disposed on a downstream side of the throttle valve 32, injects fuel into the intake path 8, [0023] The injector 35 is secured to a throttle body 31 in an inclined position, in which a fuel injection direction is inclined toward a downstream direction of the intake path 8* More specifically, an injection port 35a of fuel faces an opening made in a pipe wall of the intake path 8 With the injection port 35a in that position, a centerline C35 of an injected fuel injected in a conically shape from the injection port 35a comes into a smooth contact with a centerline C5 of the intake path 5 on the engine side that arcuately curves (see Fig. 5). Fuel injection by the injector 35 is controlled by an ECU (Electronic Control Unit) for controlling an operation of the engine 2. An atomized fuel is injected from the injection port 35a in time with a timing at which the intake valve 22 opens on an intake stroke of the engine 2 (a corresponding cylinder for a multi-cylinder engine) . The amount of fuel injected is set according to an engine speed, a valve opening of the throttle valve 32, an intake air pressure, and the like. More specifically, an injection time of fuel is set based on a fuel injection map created in a map format corresponding to the above-referenced parameters and stored in advance in ROM of the ECU. Accordingly, the atomized fuel is injected toward an obliquely downstream direction oriented toward the intake path 5 on the engine side) for an injection time appropriate according to a driving condition (a required air-fuel ratio) of the engine 2. An air-fuel mixture flows into the intake path 5 on the engine side, as the air, which is cleaned by the air cleaner 7 and the flow rate of which is adjusted by the throttle valve 32, is mixed with the fuel injected from the injector 35. The air-fuel mixture flows past a restricted opening 67 in the insulator 11 before flowing into the intake path 5 on the engine side. The intake path 5 on the engine side smoothly arcuately curves to connect to the combustion chamber 4, The air and the fuel that have flowed into the intake path 5 through the restricted opening 67 flow downwardly, while being mixed together further uniformly in the intake path 5, before being supplied to the combustion chamber 4 through the intake port 5p. The uniformly mixed air-fuel mixture is compressed by the piston 29 during a compression stroke. The mixture is thereafter fired by an ignition plug (not shown) disposed in the cylinder head 21. The mixture is thereby burned to rotate the crankshaft 28 via the piston 29 and the connecting rod 27 An exhaust gas after burning is displaced by the piston 29 during an exhaust stroke and discharged to an outside through the exhaust path 6 by way of the exhaust port 6p. [0026] Fig. 3 is a view showing an appearance of the insulator 11, which is inserted between the engine 2 and the throttle device 3 and connects the intake path 5 on the engine side with the intake path 8 on the throttle device side. Fig. 4(a) is a vertical cross-sectional view (cross-sectional view taken along a view on arrow IVa in Fig. 4(b)) showing the insulator 11 according to the first embodiment of the present invention along a direction in which the intake path 5 extends. Fig. 4(b) is a front view showing the insulator 11 as viewed from the side of the throttle device 3. [0027] The insulator 11 includes an outer tube 51 covering an outer periphery thereof. The insulator 11 thus generally forms a cylinder. An orifice plate 60 is integrally embedded into an annular partition wall 55 formed inside the insulator 11. The insulator 11 further includes an engine connection portion 52 and a throttle connection portion 53, Specifically, the engine connection portion 52 is disposed on a first end (on a right end side in Fig. 4(a)) of the insulator 11 across the partition wall 55. The engine connection portion 52 is fitted and connected to an intake hole protrusion 42 of a shouldered cylinder disposed on the cylinder head 21 in a protruding condition. The throttle connection portion 53 is disposed on a second end (on a left end side in Fig, 4(a)) of the insulator 11 across the partition wall 55. The throttle connection portion 53 is fitted and connected to a connector 43 of a shouldered cylinder formed on the throttle device 3. Band locking portions 54a, 54b are formed on outer peripheral sides of the engine connection portion 52 and the throttle connection portion 53, respectively. Clamp bands 44a, 44b are wound around the band locking portions 54a, S4b, respectively. [0028] The engine connection portion 52 is fitted and connected to the intake hole protrusion 42 of the engine 2. The connector 43 of the throttle device 3 is fitted and connected to the throttle connection portion 53. This connects the intake path 5 on the engine side with the intake path 8 on the throttle device side with the orifice plate 60 interposed therebetween. When the clamp bands 44a, 44b wound around the band locking portions 54a, 54b, respectively, are then tightened, the intake path 5 on the engine side and the intake path 8 on the throttle device side are rigidly hermetically connected with no gap produced in the fitted connection portion. The insulator 11 is integrally formed with the orifice plate 60 through an insert mold using a rubber material offering an outstanding oil resistance and weather resistance and molding a peripheral edge of the orifice plate 60. The insulator 11 is thus adapted to shut down vibration of the engine 2 and prevent the vibration from being directly transmitted to the throttle device 3, The orifice plate 60 embedded in the partition wall 55 includes a plate 61, a limiter 65, a communication hole 63, and the like. The plate 61 is a flat disk that separates the intake path between an upstream side (on the side of the throttle device 3) and a downstream side (on the side of the engine 2) . The limiter 65 is disposed at a position near a center of the plate 61. This limiter 65 restricts an area through which the fuel and air flow. The communication hole 63 is formed at a position near a peripheral edge of the plate 61. The communication hole 63 penetrates through the plate 61. Typically, the orifice plate 60 is formed from an aluminum alloy sheet or a stainless steel sheet with a thickness of about 1 mm. The communication hole 63 is formed into a slot for providing communication between the upstream side and the downstream side. The communication hole 63 is formed along a bottom wall surface of the partition wall 55. Fuel, if liquefied in the intake path, is made to flow downwardly so as to be prevented from stagnating. [0030] The limiter 65 is formed into a funnel-like or bell-mouthed shape having a smaller path cross-sectional area toward the downstream direction (leftward in Fig, 4(a)) of the intake path. The circular restricted opening 67 is provided in an open condition in a protruded end drawn up toward the downstream side from the plate 61. The restricted opening 67 connects to a smoothly conical or arcuate intake wall surface 66. A fluid (a gas-liquid mixture fluid of air and atomized fuel) flowing downwardly along the intake path is deflected by a deflecting action of the limiter 65, flowing smoothly downwardly along the intake wall surface 66. This allows the atomized fuel to be effectively guided to the intake path 5 on the engine side. In addition, the restricted opening 67 is formed on the protruded end that is drawn up toward the downstream side from the plate 61. This arrangement blocks to prevent fuel components or carbon or other particulate components from flowing backward when the mixture flows backward from the intake path 5 on the engine side. The throttle device 3 can thereby be prevented from being contaminated. [0031] Referring to Figs. 4(a), 4(b), and 5, the intake wall surface 66 is not symmetrical about a centerline C67 that passes through a center of the restricted opening 67 The intake wall surface 66 is formed into an eccentric funnel shape oriented toward the injection port 35a of the injector 3 5 disposed upwardly of the intake path 8, so as to flare more largely on an upper side thereof. The injection port 35a of the injector 35 is disposed near a peripheral edge (near an upper pipe wall) on the downstream side of the throttle valve 32. This allows a vector direction of the intake air stream and a vector direction of the injected fuel to be brought mutually close together. This allows the injected fuel, which expands conically in an obliquely downstream direction from the injection port 35a, to smoothly flow downwardly along the eccentrically funnel-shaped intake wall surface 66 (see an outline Fj of the injected fuel shown by a dash-double-dot line in Fig. 5), without allowing part of the fuel closest to the orifice plate 60 to collide thereagainst-[0032] Reference is now made, in Figs. 4(a) and 4(b), to an inside diameter centerline (specifically, a centerline of the intake path 8 on the throttle device side) C8 of the throttle connection portion 53, the centerline C67 of the restricted opening 67, and an inside diameter centerline C5 of the engine connection portion 52 (specifically, the centerline of the intake path 5 on the engine side). The restricted opening 67 is offset upwardly on the injector side relative to the inside diameter centerline (the centerline of the intake path 8 on the throttle device side) C8 of the throttle connection portion 53. The engine connection portion 52, on the other hand, is offset downwardly on the side opposite to the injector 35 relative to the inside diameter centerline (the centerline of the intake path 8 on the throttle device side) C8 of the throttle connection portion 53. Specifically, the intake path 5 on the engine side is offset toward the vector direction of the injected fuel (obliquely downwardly) relative to the intake path 8 on the throttle device side. As a result, the fuel, which has been injected obliquely downwardly and which has flowed past the restricted opening 67, flows into an area near the center of the intake path 5 on the engine side. The gas-liquid mixture fluid after the restricted opening 67 can thereby flow smoothly downwardly. Moreover, an arrangement can be made, in which the intake path 5 from the throttle device 3 to the combustion chamber 4 can be formed into a mild curve, while the engine connection portion 52 can be made smaller to build a compact insulator 11. [0033] In the insulator 11, the restricted opening 67 is isolated from the communication hole 63 and disposed opposite thereto relative to the inside diameter centerline C5 of the engine connection portion 52, This helps suppress flow of gas near the communication hole 63 The gas is thereby prevented from being subject to effect from the intake air flowing backward, which helps suppress dragging of a stagnant gas. [0034] As described heretofore, the insulator 11 according to the first embodiment of the present invention can achieve the following advantages. Specifically, the atomized fuel can be efficiently guided into the intake path 5 on the engine side. Even if a throttle device of the injector type is used, therefore, the restricted opening 67 can be made smaller, so that the adjustable range of the engine output characteristics can be expanded. [0035] Insulator structures according to other embodiments of the present invention will be described with reference to Figs. 6 through 9. Figs. 6 through 9 correspond to Fig 4(a), being cross-sectional views showing, respectively, insulators 12 to 15 according to second to fifth embodiments of the present invention. Except that the limiter is constructed differently, each of the insulators 12 to 15 shares the same arrangements as the insulator 11 according to the first embodiment of the present invention. Like reference numerals refer to like parts and duplicate descriptions are omitted. The arrangement of the limiter in each insulator according to the second to fifth embodiments of the present invention will be mainly described below. [0036] Referring to Fig. 6, an insulator 12 according to the second embodiment of the present invention includes a partition wall 55' that is connected to an outer tube 51 and formed so as to partition an intake path between an upstream side and a downstream side. A limiter 75 and a communication hole 73, together with the outer tube 51, are formed with the partition wall 55' through one piece molding. Specifically, in the insulator 12 according to the second embodiment of the present invention, an intake wall surface 76, formed into the same eccentric funnel shape as the intake wall surface 66 of the insulator 11 according to the first embodiment of the present invention, is integrally formed with the partition wall 55'. A restricted opening 77 having a centerline C77 as a center of the opening is formed in a surface of the partition wall 55' on the downstream side. These arrangements eliminate the need for insert-molding an orifice plate manufactured separately. Production processes can thereby be simplified and productivity enhanced. [0037] Referring to Fig. 7, an insulator 13 according to the third embodiment of the present invention includes a communication hole 73 and an intake wall surface 76 in a limiter 75, both integrally molded in a partition wall 55', together with an outer tube 51, in the same manner as in the insulator 12 according to the second embodiment of the present invention. A restricted opening 77' having a centerline C77 in the limiter 75 as a center of the opening is provided in an open condition in a thin flat orifice plate 70 insert-molded in the partition wall 55'. Both integrally form the limiter 75, These arrangements help simplify the structure of the orifice plate 70, while maintaining accuracy of dimensions of the restricted opening 77' at a high level. Further, use of the orifice plate having different opening areas and opening shapes allows a common mold of the insulator 13 to be used for a given range. An insulator 14 according, to the fourth embodiment of the present invention shown in Fig, 8 and an insulator 15 according to the fifth embodiment of the present invention shown in Pig, 9 represent an arrangement, in which a limiter 85 and a communication hole 83 are formed internally in a wall thickness direction of thick-wall, disk-like orifice plates 80, 80', respectively. The components are integrally formed typically through aluminum diecasting or other forming means, and machined as may be necessary to form an intake wall surface. The resultant casting is then insert-molded in a partition wall 55. Specifically, in the insulators 14, 15 according to the fourth and fifth embodiments of the present invention, an intake wall surface 86 of the same eccentric funnel shape as the intake wall surfaces 66, 76 described earlier is formed as a flow path wall surface penetrating through the orifice plates 80, 80'. A restricted opening 87 connecting smoothly to the intake wall surface 86 is opened to have a centerline C87 as a center of the opening in a plate surface on the downstream side. The insulator 15 according to the fifth embodiment of the present invention includes a receiver port 88 for receiving the injected fuel. The receiver port 88 is formed by forming an intake edge of the limiter 85 into a condition protruding toward the upstream side. Through the foregoing arrangements, it is possible to manufacture and maintain dimensions of the limiter to an even higher accuracy than in the insulators according to the first and third embodiments of the present invention. It is also possible to create a wall surface shape, which it would be difficult to make using drawing of a thin sheet. In addition, use of the orifice plate having different opening areas and opening shapes permits easy production of insulators according to varying engine characteristics without having to change the molds of the insulators 14, 15, [0039] The insulator may be structured still differently. Referring to an insulator 16 shown in Fig, 10, an upper portion of a partition plate 90 is bulged to the upstream side to form an upward facing receiver plate 91 that opposes an injector 35. A restricted opening 97 penetrating through the sheet surface may then be provided in the receiver plate 91, It is also possible to form, in the receiver plate 91, a funnel-like limiter extending obliquely downwardly to the left in alignment with the fuel injection direction, so that a restricted opening is formed in a lower end of the limiter. [0040] In the insulators 12 to 16 described above, the atomized fuel can be efficiently guided into the intake path 5 on the engine side, as in the insulator 11 according to the first embodiment of the present invention. As a result, the restricted opening can be made smaller and the adjustable range of the engine output characteristics can be expanded, [0041] The present invention has been described in detail with particular reference to certain preferred embodiments thereof, in which the insulator structure is applied to the internal combustion engine having the throttle device 3 of the carburetor type. For the internal combustion engine having the throttle device of the carburetor type, the present invention can be applied by changing the orientation and the like of the funnel-like limiter according to the position, at which a fuel delivery jet is formed, or flying of fuel. In addition, the same effects can be yielded when the insulator structure according to the embodiments of the present invention is applied to internal combustion engines of four-wheel vehicles, special vehicles, and the like, in addition to the motorcycle. [Brief Description of the Drawings] [0042] [Fig. 1] Fig, 1 is a side elevational view showing the position of an insulator in a motorcycle, to which an insulator structure according to an embodiment of the present invention is applied. [Fig. 2] Fig, 2 is a side cross-sectional view showing positional relationships among an engine, a throttle device, and the insulator, [Fig. 3] Fig. 3 is a view showing an appearance of the insulator, [Figs. 4(a) and 4(b)] Fig, 4(a) is a cross-sectional view (cross-sectional view taken along a view on arrow IVa in Fig, 4(b)) showing the insulator according to the first embodiment of the present invention along a direction in which an intake path extends; and Fig. 4(b) is a front view showing the insulator as viewed from the side of a throttle device, [Fig. 5]. Pig. 5 is a cross-sectional view showing a relationship between fuel injection of an injector relative to the intake path and a limiter of the insulator. [Fig. 6] Fig. 6 is a cross-sectional view showing an insulator according to a second embodiment of the present invention, [Fig. 7] Fig. 7 is a cross-sectional view showing an insulator according to a third embodiment of the present invention, [Fig. 8] Fig. 8 is a cross-sectional view showing an insulator according to a fourth embodiment of the present invention. [Fig. 9] Fig. 9 is a cross-sectional view showing an insulator according to a fifth embodiment of the present invention. [Fig. 10] Fig, 10 is a cross-sectional view showing an insulator according to a further embodiment of the present invention. [Description of Reference Symbols] C5: Inside diameter centerline or an engine connection portion C8: Inside diameter centerline of a throttle connection portion C35: Centerline of an injected fuel C67: Centerline of a restricted opening 2: Engine (internal combustion engine) 3: Throttle device 4: Combustion chamber 5: Intake path on the engine side 8: Intake path on the throttle device side 11: Insulator (first embodiment) 12: Insulator (second embodiment) 13: Insulator (third embodiment) 14: Insulator (fourth embodiment) 15: Insulator (fifth embodiment) 31: Throttle body 32: Throttle valve 35: Injector (fuel injection valve, 35a: injection port) 51: Outer tube 52: Engine connection portion (connection to the intake path on the engine side) 53: Throttle connection portion (connection to the intake path on the throttle device side) 55, 55'; Partition wall 60: Orifice plate (sheet member) 63: Communication hole 65: Limiter 67: Restricted opening 70: Orifice plate (sheet member) 73: Communication hole 75: Limiter 77, 77'; Restricted opening 80: Orifice plate (sheet member) 83: Communication hole 85: Limiter 87: Restricted opening [Name of Document] Claims [Claim 1] A structure of an insulator connecting a first intake path on a side of an internal combustion engine, the first intake path connecting to a combustion chamber, with a second intake path on a side of a throttle device adjusting and setting a flow rate of fuel and air supplied to the combustion chamber, thereby forming an intake path providing communication between the first and the second intake paths, the insulator for guiding the fuel and the air supplied from the throttle device into the combustion chamber; wherein the insulator includes a limiter for restricting an area through which the fuel and the air flow; and wherein the limiter is formed into a funnel-like shape having a smaller path cross-sectional area toward a downstream direction of the intake path. [Claim 2] The insulator structure according to claim 1, wherein the throttle device includes a fuel injection valve injecting fuel into the intake path; wherein the fuel injection valve is disposed in an inclined position, in which an injection direction of the fuel is inclined toward a downstream direction of the intake path; and wherein the limiter is opened and formed so as to be oriented toward an injection port of fuel in the fuel injection valve. [Claim 3] The insulator structure according to claim 2, wherein the insulator includes thereinside a partition wall connecting to an outer tube for covering an outer periphery to thereby partition the intake path between an upstream side and a downstream side; and wherein the limiter is formed with the outer tube into the partition wall through one piece molding. [Claim 4] The insulator structure according to claim 2, wherein the insulator includes thereinside a sheet member partitioning the intake path between an upstream side and a downstream side; and wherein the limiter is formed in the sheet member. [Claim 5] The insulator structure according to claim 3 or 4, wherein the opening in the limiter is offset on a side of the fuel injection valve relative to an inside diameter centerline of a connection portion in the insulator with the second intake path on the side of the throttle device; and wherein a connection portion in the insulator with the first intake path on the side of the internal combustion engine is offset on a side opposite to the fuel injection valve relative to the inside diameter centerline, [Claim 6] The insulator structure according to any one of claims 2 to 5, wherein the limiter is open at an upward position in the intake path; and wherein the limiter includes a communication hole formed downwardly therein along an inner wall surface of the outer tube, the communication hole for providing communication between the upstream side and the downstream side,

Full Text

[Name of Document] Specification
[Title of the Invention] Insulator Structure
[Technical Field]
[0001]
The present invention relates to a structure of an insulator that connects an intake path on the side of an internal combustion engine and an intake path on the side of a throttle device, thereby guiding fuel and air supplied from the throttle device into a combustion chamber. [Background Art] [0002]
Conventionally, an insulator is known that guides fuel and air supplied from a throttle device into a combustion chamber of an internal combustion engine, while shutting down vibration from the internal combustion engine. Such an insulator typically connects an intake path on the side of the internal combustion engine and an intake path on the side of the throttle device of a carburetor type or a fuel injection type for adjusting and setting a flow rate of the fuel and the air supplied to the internal combustion engine. The insulator thereby forms an intake path providing communication between the intake path on the side of the internal

combustion engine and the intake path on the side of the throttle device. Typically, the insulator is a connection member connecting the intake path on the side of the internal combustion engine and the intake path on the side of the throttle device. The insulator is to be capable of changing an internal path configuration without changing an appearance thereof. To achieve this end, a known insulator includes therein an orifice plate having a restricted opening that reduces a cross-sectional area of the path. The known insulator thereby restricts the amount of air flowing into the combustion chamber, so that engine output characteristics according to the specifications of a vehicle can be achieved. (See, for example, Patent Document 1.) [Patent Document 1]
Japanese Patent Laid-open No. Hei 6-285872 [Disclosure of the Invention] [Problem to be Solved by the Invention] [0004]
As described above, the known insulator is capable of varying the engine output characteristics using the restricted opening of variable opening area formed therein. Accordingly, there is a need for expanding an adjustable range of the output characteristics by making

the restricted opening even smaller. Decreasing the opening area of the restricted opening, however, results in part of an atomized fuel flowing down with the air being unable to flow past the restricted opening. That part of the atomized fuel then collides with a peripheral edge of the restricted opening, being liquefied and then stagnating inside the intake path. As a result, an air-fuel mixture having an unstable air-fuel ratio is supplied to the combustion chamber. This leads to a problem of reduced engine combustion efficiency, making it impossible to improve driveability or exhaust emission performance. [0005]
The throttle device of the carburetor type has an arrangement, in which fuel atomized by an intake air stream flows through the insulator with the intake air. Thanks to this arrangement, the restricted opening can be made smaller to a certain degree if the restricted opening is disposed near a peripheral wall on the side of a fuel delivery jet. With the throttle device using a fuel injection valve injecting fuel into the intake path, however, the atomized fuel is injected having a vector different from that of the intake air stream. This makes it particularly difficult to make the restricted opening

smaller,
[0006]
The present invention has been made to solve these problems and it is an object of the present invention to provide a structure for the insulator capable of expanding the adjustable range of the engine output characteristics, while allowing the restricted opening to be made even smaller.
[Means for Solving the Problem]
[0007]
To achieve the foregoing object, according to an embodiment of the present invention, there is provided a structure of an insulator. The insulator structure connects a first intake path on a side of an internal combustion engine (for example, an intake path 5 according to an embodiment of the present invention) with a second intake path on a side of a throttle device (for example, an intake path 8 according to the embodiment of the present invention), The first intake path connects to a combustion chamber. The throttle device adjusts and sets a flow rate of fuel and air supplied to the combustion chamber. An intake path providing communication between the first and the second intake paths is thereby formed- The insulator functions to guide

the fuel and the air supplied from the throttle device into the combustion chamber. In this insulator structure, the insulator includes a limiter for restricting an area through which the fuel and the air flow. Further, the limiter is formed into a funnel-like shape having a smaller path cross-sectional area toward a downstream direction of the intake path, [0008]
In accordance with the embodiment of the present invention, the throttle device includes a fuel injection valve (for example, an injector 3 5 according to the embodiment of the present invention) injecting fuel into the intake path. The fuel injection valve is disposed in an inclined position, in which an injection direction of the fuel is inclined toward a downstream direction of the intake path. Further, the limiter is opened and formed so as to be oriented toward an injection port of fuel in the fuel injection valve, [0009]
Preferably, the insulator includes thereinside a partition wall connecting to an outer tube for covering an outer periphery to thereby partition the intake path between an upstream side and a downstream side. The limiter should be formed with the outer tube into the

partition wall through one piece molding. [0010]
Preferably, the insulator includes thereinside a sheet member (for example, orifice plates 60, 70, 80 according to embodiments of the present invention) that partitions the intake path between an upstream side and a downstream side. The limiter should be formed in the sheet member. [0011]
Preferably, the opening in the limiter (for example, restricted openings 67, 77, 77', 87 according to the embodiments of the present invention) is offset on a side of the fuel injection valve (the side, on which the fuel injection valve is disposed) relative to an inside diameter centerline of a connection portion in the insulator with the second intake path on the side of the throttle device (for example, a centerline C8 according to the embodiment of the present invention), Further, a connection portion in the insulator with the first intake path on the side of the internal combustion engine should be offset on a side opposite to the fuel injection valve relative to the inside diameter centerline (on the side opposite to that on which the fuel injection valve is disposed).

It is further preferable that the limiter be open at an upward position in the intake path, and the limiter include a communication hole formed downwardly therein along an inner wall surface of the outer tube. Such a communication hole provides communication between the upstream side and the downstream side. [Effects of the Invention] [0013]
The arrangement, in which the insulator includes the limiter and the limiter is formed into a funnel-like shape having a smaller path cross-sectional area toward the downstream direction of the intake path, offers the following advantages. Specifically, an intake air and an atomized fuel are deflected by the funnel-like limiter, flowing downwardly along a wall surface of the limiter. Accordingly, the atomized fuel can be guided efficiently into the intake path on the internal combustion engine side. This makes it possible to make the limiter opening even smaller, thereby expanding the adjustable range of engine output characteristics. [0014]
If a throttle device of the fuel injection type having a fuel injection valve is used, arrangements can

be made, in which the fuel injection valve is disposed in an inclined position, in which the injection direction of the fuel is inclined toward the downstream direction of the intake path, and the limiter is opened and formed so as to be oriented toward the injection port of fuel in the fuel injection valve. According to these arrangements, a vector direction of an intake air stream and a vector direction of an injected fuel can be brought mutually close together. In addition, of the injected fuel, which expands conically from the injection port, that part closest to the limiter (for example, an upper area according to the embodiment of the present invention) is allowed to smoothly flow downwardly along the funnel shape of the limiter. Accordingly, the injected fuel can be efficiently guided into the intake path of the internal combustion engine side even in the throttle device of the fuel injection type, in which a fuel passage rate poses a major problem and it is difficult to make the limiter smaller in diameter. The restricted opening can therefore be made smaller in diameter and the adjustable range of the engine output characteristics can be expanded. [0015]
The arrangements, in which the insulator includes

thereinside the partition wall that partitions the intake path between the upstream side and the downstream side, and the limiter is formed with the outer tube into the partition wall through one piece molding, offers the following advantages. Specifically, the insulator structure can be simplified for streamlined production processes and enhanced productivity. According to the arrangements, in which the insulator includes thereinside the sheet member that partitions the intake path between the upstream side and the downstream side, and the limiter is formed in the sheet member, molding the sheet member having different opening areas and opening shapes permits easy production of insulators according to varying engine characteristics without having to change the molds of the insulators. [0016]
The arrangements, in which the opening in the limiter is offset on the side of the fuel injection valve relative to the inside diameter centerline of the connection portion in the insulator with the second intake path on the side of the throttle device, and the connection portion in the insulator with the first intake path on the side of the internal combustion engine is offset on the side opposite to the fuel injection valve

relative to the inside diameter centerline, offers the following advantages. Specifically, according to these arrangements, the first intake path on the side of the internal combustion engine is offset in the vector direction of the injected fuel. This allows the injected fuel to flow smoothly to an area near a center of the first intake path on the side of the internal combustion engine. Further, the intake path from the throttle device to the combustion chamber can be formed into a mild curve, while the connection portion with the first intake path on the side of the internal combustion engine can be made smaller to build a compact insulator. [0017]
The arrangements, in which the limiter is open at the upward position in the intake path, and the limiter includes the communication hole, which provides communication between the upstream side and the downstream side, formed downwardly therein along the inner wall surface of the outer tube, offers the following advantages. Specifically, any part of the fuel, if liquefied in the intake path as a result of its having been in contact with the limiter, is made to flow downwardly so as to be prevented from stagnating. Further, the communication hole is isolated from the limiter. The

stagnant gas near the communication hole is therefore less subject to effect from the intake air flowing backward. This leads to a stabilized mixture, thus enhancing engine performance.
[0018]
The present invention can therefore provide an insulator structure capable of expanding the adjustable range of the engine output characteristics, while allowing the restricted opening to be made even smaller,
[Best Mode for Carrying out the Invention]
[0019]
An insulator structure according to preferred embodiments of the present invention will be described below with reference to the accompanying drawings. Figs. 1 and 2 are views showing an arrangement of the insulator structure according to a first embodiment of the present invention, as applied to a motorcycle. The arrangement of the insulator structure according to the first embodiment of the present invention will be first briefly described with reference to Figs. 1 and 2. For convenience sake, an arrow U in Fig* 1 is an upward direction and an arrow R
(rearward of a vehicle body) in Fig. 1 is a rightward direction unless otherwise specified.
[0020]

An insulator 11 is disposed between an engine 2 and a throttle device 3. The engine 2 produces a power drive. The throttle device 3 adjusts and sets a flow rate of fuel and air supplied to the engine 2. The insulator 11 connects an intake path 5 on the side of the engine 2 with an intake path 8 on the side of the throttle device 3, The intake path 5 on the engine side connects to a combustion chamber 4. The intake path 8 on the throttle device side connects to an air cleaner 7, The insulator 11 thereby forms an intake path providing communication between the intake path 5 on the engine side and the intake path 8 on the throttle device side. In this configuration, the insulator 11 guides fuel and air supplied from the throttle device 3 into the combustion chamber 4. [0021]
The engine 2 is illustrated as a water-cooled engine of an overhead camshaft (OHC) type. A cylinder head 21 includes an intake path 5 and an exhaust path 6 formed therein. Both the intake path 5 and the exhaust path 6 connect to the combustion chamber 4. The cylinder head 21 vertically slidably supports an intake valve 22 and an exhaust valve 23. The intake valve 22 opens and closes an intake port 5p opening to the combustion

chamber 4, The exhaust valve 23 opens and closes an exhaust port 6p opening to the combustion chamber 4. The intake valve 22 and the exhaust valve 23 are urged at all times upwardly by valve springs 24, 24, respectively, inserted between the cylinder head 21 and the respective valves. Rocker arms 26a, 26b are pivotally supported, respectively, by the cylinder head 21. The rocker arms 26a, 26b are pivotally moved by a cam formed on a camshaft 25. An upper end of each of the intake valve 22 and the exhaust valve 23 is supported in abutment with the rocker arms 26a, 26b, respectively. The rocker arms 26a, 26b are pivotally moved by rotation of the camshaft 25 connected via a cam chain and a sprocket not shown. In accordance with the pivotal motion of the rocker arms 26a, 26b, the intake valve 22 and the exhaust valve 23 are pushed downwardly to thereby open or close the intake port 5p and the exhaust port 6p, respectively. Specifically, the intake valve 22 and the exhaust valve 23 are raised or lowered according to the position in a vertical direction of a piston 29 connected to a crankshaft 28 via a connecting rod 27. The intake port 5p and the exhaust port 6p are opened or closed in synchronism with the rotation of the crankshaft 28,

The throttle device 3 is illustrated as being a fuel injection type using an injector (a fuel injection valve) as fuel delivery means. The throttle device 3 includes a throttle valve 32 and an injector 35. The throttle valve 32 of a disk shape is pivotally movably disposed about an axis extending in a direction orthogonal to an axis of the intake path 8 (in a direction orthogonal to the paper surface in Figs. 1 and 2) . The throttle valve 32 thereby opens or closes the intake path 8. The injector 35, disposed on a downstream side of the throttle valve 32, injects fuel into the intake path 8, [0023]
The injector 35 is secured to a throttle body 31 in an inclined position, in which a fuel injection direction is inclined toward a downstream direction of the intake path 8* More specifically, an injection port 35a of fuel faces an opening made in a pipe wall of the intake path 8 With the injection port 35a in that position, a centerline C35 of an injected fuel injected in a conically shape from the injection port 35a comes into a smooth contact with a centerline C5 of the intake path 5 on the engine side that arcuately curves (see Fig. 5).

Fuel injection by the injector 35 is controlled by an ECU (Electronic Control Unit) for controlling an operation of the engine 2. An atomized fuel is injected from the injection port 35a in time with a timing at which the intake valve 22 opens on an intake stroke of the engine 2 (a corresponding cylinder for a multi-cylinder engine) . The amount of fuel injected is set according to an engine speed, a valve opening of the throttle valve 32, an intake air pressure, and the like. More specifically, an injection time of fuel is set based on a fuel injection map created in a map format corresponding to the above-referenced parameters and stored in advance in ROM of the ECU. Accordingly, the atomized fuel is injected toward an obliquely downstream direction oriented toward the intake path 5 on the engine side) for an injection time appropriate according to a driving condition (a required air-fuel ratio) of the engine 2. An air-fuel mixture flows into the intake path 5 on the engine side, as the air, which is cleaned by the air cleaner 7 and the flow rate of which is adjusted by the throttle valve 32, is mixed with the fuel injected from the injector 35. The air-fuel mixture flows past a restricted opening 67 in the insulator 11 before flowing into the intake path 5 on the engine side.

The intake path 5 on the engine side smoothly arcuately curves to connect to the combustion chamber 4, The air and the fuel that have flowed into the intake path 5 through the restricted opening 67 flow downwardly, while being mixed together further uniformly in the intake path 5, before being supplied to the combustion chamber 4 through the intake port 5p. The uniformly mixed air-fuel mixture is compressed by the piston 29 during a compression stroke. The mixture is thereafter fired by an ignition plug (not shown) disposed in the cylinder head 21. The mixture is thereby burned to rotate the crankshaft 28 via the piston 29 and the connecting rod 27 An exhaust gas after burning is displaced by the piston 29 during an exhaust stroke and discharged to an outside through the exhaust path 6 by way of the exhaust port 6p. [0026]
Fig. 3 is a view showing an appearance of the insulator 11, which is inserted between the engine 2 and the throttle device 3 and connects the intake path 5 on the engine side with the intake path 8 on the throttle device side. Fig. 4(a) is a vertical cross-sectional view (cross-sectional view taken along a view on arrow IVa in Fig. 4(b)) showing the insulator 11 according to the

first embodiment of the present invention along a direction in which the intake path 5 extends. Fig. 4(b) is a front view showing the insulator 11 as viewed from the side of the throttle device 3. [0027]
The insulator 11 includes an outer tube 51 covering an outer periphery thereof. The insulator 11 thus generally forms a cylinder. An orifice plate 60 is integrally embedded into an annular partition wall 55 formed inside the insulator 11. The insulator 11 further includes an engine connection portion 52 and a throttle connection portion 53, Specifically, the engine connection portion 52 is disposed on a first end (on a right end side in Fig. 4(a)) of the insulator 11 across the partition wall 55. The engine connection portion 52 is fitted and connected to an intake hole protrusion 42 of a shouldered cylinder disposed on the cylinder head 21 in a protruding condition. The throttle connection portion 53 is disposed on a second end (on a left end side in Fig, 4(a)) of the insulator 11 across the partition wall 55. The throttle connection portion 53 is fitted and connected to a connector 43 of a shouldered cylinder formed on the throttle device 3. Band locking portions 54a, 54b are formed on outer peripheral sides of

the engine connection portion 52 and the throttle connection portion 53, respectively. Clamp bands 44a, 44b are wound around the band locking portions 54a, S4b, respectively. [0028]
The engine connection portion 52 is fitted and connected to the intake hole protrusion 42 of the engine 2. The connector 43 of the throttle device 3 is fitted and connected to the throttle connection portion 53. This connects the intake path 5 on the engine side with the intake path 8 on the throttle device side with the orifice plate 60 interposed therebetween. When the clamp bands 44a, 44b wound around the band locking portions 54a, 54b, respectively, are then tightened, the intake path 5 on the engine side and the intake path 8 on the throttle device side are rigidly hermetically connected with no gap produced in the fitted connection portion. The insulator 11 is integrally formed with the orifice plate 60 through an insert mold using a rubber material offering an outstanding oil resistance and weather resistance and molding a peripheral edge of the orifice plate 60. The insulator 11 is thus adapted to shut down vibration of the engine 2 and prevent the vibration from being directly transmitted to the throttle device 3,

The orifice plate 60 embedded in the partition wall 55 includes a plate 61, a limiter 65, a communication hole 63, and the like. The plate 61 is a flat disk that separates the intake path between an upstream side (on the side of the throttle device 3) and a downstream side (on the side of the engine 2) . The limiter 65 is disposed at a position near a center of the plate 61. This limiter 65 restricts an area through which the fuel and air flow. The communication hole 63 is formed at a position near a peripheral edge of the plate 61. The communication hole 63 penetrates through the plate 61. Typically, the orifice plate 60 is formed from an aluminum alloy sheet or a stainless steel sheet with a thickness of about 1 mm. The communication hole 63 is formed into a slot for providing communication between the upstream side and the downstream side. The communication hole 63 is formed along a bottom wall surface of the partition wall 55. Fuel, if liquefied in the intake path, is made to flow downwardly so as to be prevented from stagnating. [0030]
The limiter 65 is formed into a funnel-like or bell-mouthed shape having a smaller path cross-sectional area toward the downstream direction (leftward in Fig,

4(a)) of the intake path. The circular restricted opening 67 is provided in an open condition in a protruded end drawn up toward the downstream side from the plate 61. The restricted opening 67 connects to a smoothly conical or arcuate intake wall surface 66. A fluid (a gas-liquid mixture fluid of air and atomized fuel) flowing downwardly along the intake path is deflected by a deflecting action of the limiter 65, flowing smoothly downwardly along the intake wall surface 66. This allows the atomized fuel to be effectively guided to the intake path 5 on the engine side. In addition, the restricted opening 67 is formed on the protruded end that is drawn up toward the downstream side from the plate 61. This arrangement blocks to prevent fuel components or carbon or other particulate components from flowing backward when the mixture flows backward from the intake path 5 on the engine side. The throttle device 3 can thereby be prevented from being contaminated. [0031]
Referring to Figs. 4(a), 4(b), and 5, the intake wall surface 66 is not symmetrical about a centerline C67 that passes through a center of the restricted opening 67 The intake wall surface 66 is formed into an eccentric funnel shape oriented toward the injection port 35a of

the injector 3 5 disposed upwardly of the intake path 8, so as to flare more largely on an upper side thereof. The injection port 35a of the injector 35 is disposed near a peripheral edge (near an upper pipe wall) on the downstream side of the throttle valve 32. This allows a vector direction of the intake air stream and a vector direction of the injected fuel to be brought mutually close together. This allows the injected fuel, which expands conically in an obliquely downstream direction from the injection port 35a, to smoothly flow downwardly along the eccentrically funnel-shaped intake wall surface 66 (see an outline Fj of the injected fuel shown by a dash-double-dot line in Fig. 5), without allowing part of the fuel closest to the orifice plate 60 to collide thereagainst-[0032]
Reference is now made, in Figs. 4(a) and 4(b), to an inside diameter centerline (specifically, a centerline of the intake path 8 on the throttle device side) C8 of the throttle connection portion 53, the centerline C67 of the restricted opening 67, and an inside diameter centerline C5 of the engine connection portion 52 (specifically, the centerline of the intake path 5 on the engine side). The restricted opening 67 is offset

upwardly on the injector side relative to the inside diameter centerline (the centerline of the intake path 8 on the throttle device side) C8 of the throttle connection portion 53. The engine connection portion 52, on the other hand, is offset downwardly on the side opposite to the injector 35 relative to the inside diameter centerline (the centerline of the intake path 8 on the throttle device side) C8 of the throttle connection portion 53. Specifically, the intake path 5 on the engine side is offset toward the vector direction of the injected fuel (obliquely downwardly) relative to the intake path 8 on the throttle device side. As a result, the fuel, which has been injected obliquely downwardly and which has flowed past the restricted opening 67, flows into an area near the center of the intake path 5 on the engine side. The gas-liquid mixture fluid after the restricted opening 67 can thereby flow smoothly downwardly. Moreover, an arrangement can be made, in which the intake path 5 from the throttle device 3 to the combustion chamber 4 can be formed into a mild curve, while the engine connection portion 52 can be made smaller to build a compact insulator 11. [0033]
In the insulator 11, the restricted opening 67 is

isolated from the communication hole 63 and disposed opposite thereto relative to the inside diameter centerline C5 of the engine connection portion 52, This helps suppress flow of gas near the communication hole 63 The gas is thereby prevented from being subject to effect from the intake air flowing backward, which helps suppress dragging of a stagnant gas.
[0034]
As described heretofore, the insulator 11 according to the first embodiment of the present invention can achieve the following advantages. Specifically, the atomized fuel can be efficiently guided into the intake path 5 on the engine side. Even if a throttle device of the injector type is used, therefore, the restricted opening 67 can be made smaller, so that the adjustable range of the engine output characteristics can be expanded.
[0035]
Insulator structures according to other embodiments of the present invention will be described with reference to Figs. 6 through 9. Figs. 6 through 9 correspond to Fig 4(a), being cross-sectional views showing, respectively, insulators 12 to 15 according to second to fifth embodiments of the present invention. Except that the

limiter is constructed differently, each of the insulators 12 to 15 shares the same arrangements as the insulator 11 according to the first embodiment of the present invention. Like reference numerals refer to like parts and duplicate descriptions are omitted. The arrangement of the limiter in each insulator according to the second to fifth embodiments of the present invention will be mainly described below. [0036]
Referring to Fig. 6, an insulator 12 according to the second embodiment of the present invention includes a partition wall 55' that is connected to an outer tube 51 and formed so as to partition an intake path between an upstream side and a downstream side. A limiter 75 and a communication hole 73, together with the outer tube 51, are formed with the partition wall 55' through one piece molding. Specifically, in the insulator 12 according to the second embodiment of the present invention, an intake wall surface 76, formed into the same eccentric funnel shape as the intake wall surface 66 of the insulator 11 according to the first embodiment of the present invention, is integrally formed with the partition wall 55'. A restricted opening 77 having a centerline C77 as a center of the opening is formed in a surface of the

partition wall 55' on the downstream side. These arrangements eliminate the need for insert-molding an orifice plate manufactured separately. Production processes can thereby be simplified and productivity enhanced. [0037]
Referring to Fig. 7, an insulator 13 according to the third embodiment of the present invention includes a communication hole 73 and an intake wall surface 76 in a limiter 75, both integrally molded in a partition wall 55', together with an outer tube 51, in the same manner as in the insulator 12 according to the second embodiment of the present invention. A restricted opening 77' having a centerline C77 in the limiter 75 as a center of the opening is provided in an open condition in a thin flat orifice plate 70 insert-molded in the partition wall 55'. Both integrally form the limiter 75, These arrangements help simplify the structure of the orifice plate 70, while maintaining accuracy of dimensions of the restricted opening 77' at a high level. Further, use of the orifice plate having different opening areas and opening shapes allows a common mold of the insulator 13 to be used for a given range.

An insulator 14 according, to the fourth embodiment of the present invention shown in Fig, 8 and an insulator 15 according to the fifth embodiment of the present invention shown in Pig, 9 represent an arrangement, in which a limiter 85 and a communication hole 83 are formed internally in a wall thickness direction of thick-wall, disk-like orifice plates 80, 80', respectively. The components are integrally formed typically through aluminum diecasting or other forming means, and machined as may be necessary to form an intake wall surface. The resultant casting is then insert-molded in a partition wall 55. Specifically, in the insulators 14, 15 according to the fourth and fifth embodiments of the present invention, an intake wall surface 86 of the same eccentric funnel shape as the intake wall surfaces 66, 76 described earlier is formed as a flow path wall surface penetrating through the orifice plates 80, 80'. A restricted opening 87 connecting smoothly to the intake wall surface 86 is opened to have a centerline C87 as a center of the opening in a plate surface on the downstream side. The insulator 15 according to the fifth embodiment of the present invention includes a receiver port 88 for receiving the injected fuel. The receiver port 88 is formed by forming an intake edge of the

limiter 85 into a condition protruding toward the upstream side. Through the foregoing arrangements, it is possible to manufacture and maintain dimensions of the limiter to an even higher accuracy than in the insulators according to the first and third embodiments of the present invention. It is also possible to create a wall surface shape, which it would be difficult to make using drawing of a thin sheet. In addition, use of the orifice plate having different opening areas and opening shapes permits easy production of insulators according to varying engine characteristics without having to change the molds of the insulators 14, 15, [0039]
The insulator may be structured still differently. Referring to an insulator 16 shown in Fig, 10, an upper portion of a partition plate 90 is bulged to the upstream side to form an upward facing receiver plate 91 that opposes an injector 35. A restricted opening 97 penetrating through the sheet surface may then be provided in the receiver plate 91, It is also possible to form, in the receiver plate 91, a funnel-like limiter extending obliquely downwardly to the left in alignment with the fuel injection direction, so that a restricted opening is formed in a lower end of the limiter.

[0040]
In the insulators 12 to 16 described above, the atomized fuel can be efficiently guided into the intake path 5 on the engine side, as in the insulator 11 according to the first embodiment of the present invention. As a result, the restricted opening can be made smaller and the adjustable range of the engine output characteristics can be expanded, [0041]
The present invention has been described in detail with particular reference to certain preferred embodiments thereof, in which the insulator structure is applied to the internal combustion engine having the throttle device 3 of the carburetor type. For the internal combustion engine having the throttle device of the carburetor type, the present invention can be applied by changing the orientation and the like of the funnel-like limiter according to the position, at which a fuel delivery jet is formed, or flying of fuel. In addition, the same effects can be yielded when the insulator structure according to the embodiments of the present invention is applied to internal combustion engines of four-wheel vehicles, special vehicles, and the like, in addition to the motorcycle.

[Brief Description of the Drawings]
[0042]
[Fig. 1]
Fig, 1 is a side elevational view showing the position of an insulator in a motorcycle, to which an insulator structure according to an embodiment of the present invention is applied. [Fig. 2]
Fig, 2 is a side cross-sectional view showing positional relationships among an engine, a throttle device, and the insulator, [Fig. 3]
Fig. 3 is a view showing an appearance of the insulator, [Figs. 4(a) and 4(b)]
Fig, 4(a) is a cross-sectional view (cross-sectional view taken along a view on arrow IVa in Fig, 4(b)) showing the insulator according to the first embodiment of the present invention along a direction in which an intake path extends; and Fig. 4(b) is a front view showing the insulator as viewed from the side of a throttle device, [Fig. 5].
Pig. 5 is a cross-sectional view showing a

relationship between fuel injection of an injector relative to the intake path and a limiter of the insulator. [Fig. 6]
Fig. 6 is a cross-sectional view showing an insulator according to a second embodiment of the present invention, [Fig. 7]
Fig. 7 is a cross-sectional view showing an insulator according to a third embodiment of the present invention, [Fig. 8]
Fig. 8 is a cross-sectional view showing an insulator according to a fourth embodiment of the present invention. [Fig. 9]
Fig. 9 is a cross-sectional view showing an insulator according to a fifth embodiment of the present invention. [Fig. 10]
Fig, 10 is a cross-sectional view showing an insulator according to a further embodiment of the present invention. [Description of Reference Symbols]

C5: Inside diameter centerline or an engine connection
portion
C8: Inside diameter centerline of a throttle connection
portion
C35: Centerline of an injected fuel
C67: Centerline of a restricted opening
2: Engine (internal combustion engine)
3: Throttle device
4: Combustion chamber
5: Intake path on the engine side
8: Intake path on the throttle device side
11: Insulator (first embodiment)
12: Insulator (second embodiment)
13: Insulator (third embodiment)
14: Insulator (fourth embodiment)
15: Insulator (fifth embodiment)
31: Throttle body
32: Throttle valve
35: Injector (fuel injection valve, 35a: injection port)
51: Outer tube
52: Engine connection portion (connection to the intake
path on the engine side)
53: Throttle connection portion (connection to the intake

path on the throttle device side)
55, 55'; Partition wall
60: Orifice plate (sheet member)
63: Communication hole
65: Limiter
67: Restricted opening
70: Orifice plate (sheet member)
73: Communication hole
75: Limiter
77, 77'; Restricted opening
80: Orifice plate (sheet member)
83: Communication hole
85: Limiter
87: Restricted opening

[Name of Document] Claims [Claim 1]
A structure of an insulator connecting a first intake path on a side of an internal combustion engine, the first intake path connecting to a combustion chamber, with a second intake path on a side of a throttle device adjusting and setting a flow rate of fuel and air supplied to the combustion chamber, thereby forming an intake path providing communication between the first and the second intake paths, the insulator for guiding the fuel and the air supplied from the throttle device into the combustion chamber;
wherein the insulator includes a limiter for restricting an area through which the fuel and the air flow; and
wherein the limiter is formed into a funnel-like shape having a smaller path cross-sectional area toward a downstream direction of the intake path. [Claim 2]
The insulator structure according to claim 1,
wherein the throttle device includes a fuel injection valve injecting fuel into the intake path;
wherein the fuel injection valve is disposed in an inclined position, in which an injection direction of the

fuel is inclined toward a downstream direction of the
intake path; and
wherein the limiter is opened and formed so as to
be oriented toward an injection port of fuel in the fuel
injection valve.
[Claim 3]
The insulator structure according to claim 2, wherein the insulator includes thereinside a
partition wall connecting to an outer tube for covering
an outer periphery to thereby partition the intake path
between an upstream side and a downstream side; and
wherein the limiter is formed with the outer tube
into the partition wall through one piece molding. [Claim 4]
The insulator structure according to claim 2, wherein the insulator includes thereinside a sheet
member partitioning the intake path between an upstream
side and a downstream side; and
wherein the limiter is formed in the sheet member. [Claim 5]
The insulator structure according to claim 3 or 4, wherein the opening in the limiter is offset on a
side of the fuel injection valve relative to an inside
diameter centerline of a connection portion in the

insulator with the second intake path on the side of the throttle device; and
wherein a connection portion in the insulator with the first intake path on the side of the internal combustion engine is offset on a side opposite to the fuel injection valve relative to the inside diameter centerline, [Claim 6]
The insulator structure according to any one of claims 2 to 5,
wherein the limiter is open at an upward position in the intake path; and
wherein the limiter includes a communication hole formed downwardly therein along an inner wall surface of the outer tube, the communication hole for providing communication between the upstream side and the downstream side,

Documents:

549-CHE-2008 CORRESPONDENCE OTHERS 12-03-2014.pdf

549-CHE-2008 CORRESPONDENCE OTHERS 30-10-2012.pdf

549-CHE-2008 EXAMINATION REPORT REPLY RECEIVED 22-11-2013.pdf

549-CHE-2008 FORM-3 22-11-2013.pdf

549-CHE-2008 POWER OF ATTORNEY 22-11-2013.pdf

549-CHE-2008 AMENDED CLAIMS 22-11-2013.pdf

549-CHE-2008 CORRESPONDENCE OTHERS 14-08-2014.pdf

549-CHE-2008 CORRESPONDENCE OTHERS 20-03-2014.pdf

549-CHE-2008 FORM-1 14-08-2014.pdf

549-CHE-2008 OTHER PATENT DOCUMENT 14-08-2014.pdf

549-CHE-2008 OTHER PATENT DOCUMENT 22-11-2013.pdf

549-CHE-2008 OTHER PATENT DOCUMENT 1 14-08-2014.pdf

549-che-2008-abstract.pdf

549-che-2008-claims.pdf

549-che-2008-correspondnece-others.pdf

549-che-2008-description(complete).pdf

549-che-2008-drawings.pdf

549-che-2008-form 1.pdf

549-che-2008-form 18.pdf

549-che-2008-form 26.pdf

549-che-2008-form 3.pdf

549-che-2008-form 5.pdf

549-CHE-2008-Petition for POR.pdf

549-CHE-2008-Petition.pdf

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Patent Number

262665

Indian Patent Application Number

549/CHE/2008

PG Journal Number

36/2014

Publication Date

05-Sep-2014

Grant Date

03-Sep-2014

Date of Filing

04-Mar-2008

Name of Patentee

HONDA MOTOR CO., LTD.

Applicant Address

1-1, MINAMI-AOYAMA 2-CHOMEMINATO-KU, TOKYO 107-8556

Inventors:

#	Inventor's Name	Inventor's Address
1	HARADA, MAKOTO	C/O HONDA R&D CO. LTD 4-1, CHUO 1-CHOME WAKO-SHI, SAITAMA 351-0193
2	OGASAWARA, MAKOTO	C/O HONDA R&D CO. LTD 4-1, CHUO 1-CHOME WAKO-SHI, SAITAMA 351-0193
3	ONO, YUTAKA	C/O HONDA R&D CO. LTD 4-1, CHUO 1-CHOME WAKO-SHI, SAITAMA 351-0193
4	KAWAKUBO, HIROYUKI	C/O HONDA R&D CO. LTD 4-1, CHUO 1-CHOME WAKO-SHI, SAITAMA 351-0193

PCT International Classification Number

F 16 F 19/00

PCT International Application Number

N/A

PCT International Filing date

PCT Conventions:

#	PCT Application Number	Date of Convention	Priority Country
1	2007-057040	2007-03-07	Japan