Title of Invention

"TEMPERATURE-SENSITIVE VALVE FITTING STRUCTURE FOR AN AIR FUEL RATIO CONTROLLER"

Abstract

[OBJECT] To provide a temperature-sensitive valve fitting structure capable of attaching a temperature-sensitive valve to a compact air cleaner case included in an air cleaner unit. [CONSTITUTION] The interior of an air cleaner case 18 is divided into a dirty chamber 34 and a clean chamber 35 by a longitudinally elongate air cleaner element 33. An extension 36 of an intake duct 20 is extended from the front end into the dirty chamber 34. A temperature-sensiti ve valve 26 is fixedly disposed substantially in parallel to the air cleaner element 33 in the clean chamber 35. A bypass tube 27 has one end connected to the front end of the temperature-sensitive valve 26 and the other end connected to a bypass passage formed in a carburetor 22, and is extended substantially in parallel to a connecting tube 21 extended forward from the front wall 47 and connected to the carburetor 22.

Full Text

The present invention relates to a temperature-sensitive valve fitting structure for an air-fuel ratio controller. The present invention relates to a fitting structure for fitting a temperature-sensitive valve for the temperature-correction of air-fuel ratio regulated by a carburetor. [Related Art] A known air-fuel ratio controller such as disclosed in JP-A No. 59-206655 or 61-40454 varies the flow of air that flows through the air bleeder of a carburetor according to engine temperature or intake air temperature to control the air-fuel ratio of an air-fuel mixture so that a rich air-fuel mixture is supplied while the engine is cold to improve drivability and lean air-fuel mixture is supplied while the engine is hot to improve the quality of the exhaust gas. A technique disclosed in JP-A No. 61-40454 disposed a temperature-sensitive valve in a clean section of an air cleaner case included in an air cleaner unit, and supplies auxiliary air through a bypass passage to a carburetor. [Problem to be Solved by the Invention] If the temperature- sensitive valve is disposed inside the air cleaner case as mentioned in JP-A No. 61- 40454, a plurality of portions of the temperature-sensitive valve are fastened to the air cleaner case requiring a large space for fastening the temperature-sensitive valve to the air cleaner case. Consequently, resistance against air intake increases, the dimensions, particularly, the lateral dimension, of the air cleaner case increases, so that the width of the body of the vehicle increases. The use of such a temperature-sensitive valve entails increase in time and labor and the resultant increase of costs. If the temperature-sensitive valve is disposed near one end connected to the air cleaner case of the connecting tube having the other end connected to the carburetor, the air cleaner case must be formed in increased dimensions because the least space is available for disposing the temperature-sensitive valve in the vicinity of the end of the connecting tube connected to the air cleaner case and hence it is difficult to form the air cleaner case in a compact construction. In a motorcycle in which an air cleaner case included in an air cleaner unit is supported on top of the belt transmission case of a swing power unit, a connecting tube extends forward from the front wall of the air cleaner case toward a carburetor. Therefore, space for installing the temperature-sensitive valve is further reduced if an intake duct is disposed there and hence it is difficult to dispose the temperature-sensitive valve without increasing the lateral dimension of the air cleaner case. Accordingly, there is provided A temperature-sensitive valve fitting structure for an air-fuel ratio controller which adjusts the supply of auxiliary air through a bypass passage to a carburetor by operating a temperature-sensitive valve to control air-fuel ratio in a vehicle wherein: an air cleaner case having a body and a cover is divided by an air cleaner element into a right section and a left section, an air intake duct is connected to said cover, a connecting tube supplies air to said carburetor air and said temperature-sensitive valve placed in parallel to an air cleaner element are connected to said body, said temperature sensitive valve is connected to said carburetor by bypass tube placed outside of said connecting tube. In the temperature-sensitive valve fitting structure for an air-fuel ratio controller, the temperature-sensitive valve may be attached at two portions thereof on a longitudinal line to the inner surface of the air cleaner case, and one portion other than the foregoing two portions may be fastened to the air cleaner case with a screw. In the temperature- sensitive valve fitting structure for an air-fuel ratio controller, the screw fastening the portion of the temperature-sensitive valve to the air cleaner case may be pressed and held in place at its head by the air cleaner element. In the temperature-sensitive valve fitting structure for an air-fuel ratio controller, the temperature-sensitive valve may be disposed in a clean section of the air cleaner case at a position on the upstream side with respect to an air intake direction of one end connected to the air cleaner case of a connecting tube having the other end connected to the carburetor, and the temperature-sensitive valve may be connected to a bypass passage formed in the carburetor by a bypass tube. In the temperature-sensitive valve fitting structure for an air-fuel ratio controller, the air cleaner case may be held on top of a belt transmission case included in a swing power unit for a motorcycle, and an air intake passage may be formed in the front surface of the air cleaner case. (Effect of the Invention] Since the interior of the air cleaner case is divided into the right and the left section by the air cleaner element, the temperature-sensitive valve does not increase significantly the dimension of a space for installing the temperature-sensitive valve in a direction perpendicular to the air cleaner element, i.e., a lateral direction, if the air cleaner element is disposed substantially in parallel to the air cleaner element. therefore, the lateral dimension of the air cleaner case is not increased greatly and the air cleaner case can be formed in a compact construction even though the temperature-sensitive valve is installed within the air cleaner case and, consequently, the width of thp body of the vehicle need not be greatly increased and the body can be formed in a compact construction. When the temperature-sensitive valve is attached at the two portions thereof on a longitudinal line to the inner surface of the air cleaner case and the one portion is screwed to the air cleaner case, the number of portions to be fastened to the air cleaner case is reduced and the resistance against air intake is reduced accordingly, so that drivability is improved. The air cleaner case can be formed in small dimensions, fastening work requires less time and labor, cost can be reduced and maintainability is improved. Since the air cleaner element is pressed against the head of the screw fastening the temperature-sensitive valve to the air cleaner case, the head of the screw can be securely held by the air cleaner element. Since the temperature-sensitive valve is disposed on the upstream side with respect to the direction of flow of air of one end connected to the air cleaner case of the connecting tube having the other end connected to the carburetor and the temperature-sensitive valve is connected to the bypass passage of the carburetor by the bypass tube, the temperature-sensitive valve can be disposed at a position other than that in the vicinity of the end of the connecting tube connected to the air cleaner case where the least space is available, so that the air cleaner case can be formed in a further compact construction. Even if the air cleaner case is used on a motorcycle which supports the air cleaner case on top of a belt transmission case of a swing power unit and an air intake passage is formed in front of the air cleaner case, a sufficient space for installing the temperature-sensitive valve therein can be secured without increasing the lateral dimension of the air cleaner case. [BRIEF DESCRIPTION OF THE DRAWINGS] [Fig. 1] Fig. 1 is a top view of an intake system, in which an air cleaner unit is shown in a sectional view. [Fig. 2] Fig. 2 is a side view of the motor scooter. [Fig. 3] Fig. 3 is a plan view of the motor scooter. [Fig. 4] Fig. 4 is a side view of an engine and the intake system. [Fig. 5] Fig. 5 is an enlarged side view of a portion including a temperature-sensitive valve of Fig. 4. [Fig. 6] Fig. 6 is a sectional view taken on line 6-6 in Fig. 5. [Fig. 7] Fig. 7 is a sectional view taken on line 7-7 in Fig. 5. [Fig. 8] Fig. 8 is a sectional view of the temperature-sensitive valve. [Fig. 9] Fig. 9 is a top view of the temperature-sensitive valve. [Fig. 10] Fig. 10 is a sectional view taken on line 10-10 in Fig. 9. [Fig. 11] Fig. 11 is a sectional view of a carburetor. [Fig. 12] Fig. 12 is a view taken along the direction of the arrow X in Fig. 11. [Preferred Embodiment of the Invention] Fig. 1 is a top view of an intake system incorporated into a motor scooter in accordance with the present invention, in which an air cleaner unit is shown in a sectional view, Fig. 2 is a side view of the motor scooter, Fig. 3 is a plan view of the motor scooter, Fig. 4 is a side view of an engine and the intake system, Fig. 5 is an enlarged side view of a portion including a temperature-sensitive valve of Fig. 4, Fig. 6 is a sectional view taken on line 6-6 in Fig. 5, Fig. 7 is a sectional view taken on line 7-7 in Fig. 5, Fig. 8 is a sectional view of the temperature-sensitive valve, Fig. 9 is a top view of the temperature-sensitive valve, Fig. 10 is a sectional view taken on line 10-10 in Fig. 9, Fig. 11 is a sectional view of a carburetor, and Fig. 12 is a view taken along the direction of the arrow X in Fig. 11, i.e., from the upstream side of the carburetor. Referring to Figs. 2 and 3, a front fork 2 supporting a front wheel 1 is supported on a head pipe 3, and a front frame pipe 5 included in a body frame 4 is attached to the head pipe 3. The front frame pipe 5 extends from the head pipe 3 backward along the longitudinal axis of the body in a position inclined downward toward the rear. Front ends of a pair of floor frame pipes 6 are joined to a lower end portion of the front frame pipe 5. Rear ends of the floor frame pipes 6 are joined to rear frame pipes 7 rising obliquely upward toward the rear. A fuel tank 8 is disposed between and supported on the right and left floor frame pipes 6, a box 10 of a large capacity large enough to contain a helmet 9 is mounted on the rear frame pipes 7 and is supported at a front portion of a bottom wall and an upper portion of a rear wall on the rear frame pipes 7, and a seat 11 is hinged on the box 10. A swing power unit 13 is supported lor swing motion on bent portions of the floor frame pipes 6 connected to the rear frame pipes 7 by links 12. The swing power unit 13 comprises a horizontal engine 14, and a belt transmission case 15 containing a V belt transmission. A rear wheel 16 is supported on a rear end portion of the belt transmission case, and a shock absorber 17 is extended between the rear frame pipe 7 and the belt transmission case 15. An air cleaner case 18 included in the air cleaner unit integrally provided with a rear fender F (Fig. 1) is supported on top of the belt transmission case 15. Air is sucked through an air inlet 19 formed in the rear frame pipe 7, and an air intake duct 20 into the air cleaner case 18. Air purified by the air cleaner case 18 is sucked into a carburetor 22 by a connecting tube 21 connected to the front wall of the air cleaner case 18. Then, the carburetor 22 produces an air-fuel mixture of an appropriate air-fuel ratio, and the air-fuel mixture is sucked through an inlet port into the horizontal engine 14. The entire body frame 4 serves as an air passage. Air to be supplied to the air cleaner case 18 is taken into the body frame 4 through an air inlet 23 formed in the rear frame pipe 7 on a level higher than that of the air outlet 19. The air inlet 23 opens into a space enclosed by a body cover C (Fig. 2) on one side of the box 10. An air inlet 5a is formed in the front frame pipe 5 I at a position near the head pipe 3. Air taken in through the air inlet 5a supplied through a cooling duct 25 extending backward from a cross pipe disposed behind the fuel tank 8 into a front portion of the belt transmission case 15 to cool the interior of the belt transmission case 15. As shown in Figs 1 and 4, a well-known temperature-sensitive valve 26 is disposed inside the air cleaner case 18 with its longitudinal axis extended substantially in parallel to the longitudinal axis of the body. A joint 26a projects from the front end of the temperature-sensitive valve 26 along the longitudinal axis, and one end of a bypass tube 27 is connected to the joint 26a. The bypass tube 27 extends forward alongside the connecting tube 21 substantially in parallel to the connecting tube 21, and the front end of the bypass tube 27 is connected to a bypass joint pipe 28. The bypass tube 27 is connected to a bypass passage, which will be described later, formed in the carburetor 22 to supply auxiliary air to a position in the intake air passage of the carburetor 22 on the downstream side of a main nozzle. Thus, a lean air-fuel mixture is supplied to the engine while the engine is hot to improve exhaust gas purifying efficiency. The temperature-sensitive valve 26 regulates the flow of auxiliary air through the bypass tube 27. The temperature-sensitive valve 26 remains closed while the temperature of intake air is below a predetermined temperature, such as during a cold time immediately after the start of the engine to stop the supply of auxiliary air in order that a rich air- fuel mixture is supplied from the carburetor 22 to the engine. The temperature-sensitive valve 26 opens gradually as the temperature of intake air rises to vary the flow of auxiliary air through the bypass joint pipe 28 according to the temperature of intake air to increase the air-fuel ratio of the air-fuel mixture. The temperature-sensitive valve 26 is fully opened after the temperature of intake air has increased beyond a predetermined temperature. The opening of the temperature-sensitive valve 26 may be controlled according to the temperature of the engine 14. The air cleaner case 18 is constructed by fastening a cover 31 to a body 30 with a screw 32. The interior of the air cleaner case 18 is divided into a dirty chamber 34 and a clean chamber 35 by an air cleaner element 33 longitudinally attached to the body 30. An extension 36 of the air intake duct 20 extending rearward from the air outlet 19 of the rear frame pipe 7 extends through a front wall 31a of the cover 31 into the dirty chamber 34. The extension 36 extends rearward beyond the temperature-sensitive valve 26. A lug formed integrally with the extension 36 so as to project from one side of the extension 36 is screwed to the cover 31 to hold the extension 36 fixedly on the cover 31. The temperature-sensitive valve 26 is disposed in the clean side 35 of the air cleaner case 18 at a position on the upstream side with respect to the flowing direction of air, i.e., on the back side with respect to the traveling direction of the motor scooter, of the end 2la of the connecting tube 21 connected to the air cleaner case 18. As shown in Figs. 5 to 9, the temperature-sensitive valve 26 is disposed with its longitudinal axis extended substantially in parallel to the longitudinal axis of the motor scooter, and a lug 37 projecting upward from the side surface of the temperature-sensitive valve 26 is fastened to a boss 39 (Fig. 6) formed integrally with the body 30 with a screw 38. Longitudinally spaced ribs 41 and 43 are formed in a longitudinal arrangement on the inner surface 30a of the body 30. Projections 40 project from the valve casing of the temperature-sensitive valve 26 so as to be pressed against the ribs 41 and 43. As shown in Figs. 9 and 10, the extremities of the projections 40 to be pressed against the ribs 41 and 43 lie substantially on a tangent plane tangent to the outer circumference of the valve casing of the temperature-sensitive valve 26 at a position opposite the lug 37 with respect to the temperature-sensitive valve 26 and substantially parallel to a direction in which the lug 37 extends . The projections 40 are upward open, substantially U-shaped ribs as viewed from the side of the extremities thereof to be pressed against the ribs 41 and 43, and have flat lower surfaces 45 substantially parallel to a plane perpendicular to the direction in which the lug 37 extends. As shown in Fig. 6, projection 42 is formed integrally with the rib 41 so as to project from the lower end of the rib 41 toward the temperature-sensitive valve 26. The valve casing of the temperature-sensitive valve 26 is fitted and positioned in a space defined by the inner end surface of the rib 41 facing the temperature-sensitive valve 26, the projection 42 and the boss 39 with the projection 40 pressed against the inner end surface of the rib 41 and the lower surface 45 seated on the projection 42. As shown in Fig. 7, the rib 43 disposed on the front side of the rib 41 has projections 44 extending from the upper and the lower end thereof. The temperature-sensitive valve 26 is fitted and positioned in a space defined by the projections 44 and the inner end surface of the rib 43 with the projection pressed against the inner end surface of the rib 43 and the lower end 45 seated on the projection 44. Thus the temperature-sensitive valve 26 is held at two positions thereon in a longitudinal position and held in place by the ribs 41 and 43, and is secured to the body 30 by fastening the lug 37 to the inner surface 30a of the body 30 with the single screw 38. As shown in Fig. 6, a push rod 46 projects inward from the cover 31 compresses a portion of the air cleaner element 33 and presses the compressed portion of the air cleaner element 33 against the head 38a of the screw 38. Thus, the push rod 46 applies pressure to the head 38a of the screw 38. As shown in Fig. 1, the rear end of the bypass tube 27 is fitted on the joint 26a of the temperature-sensitive valve 26. The bypass tube 27 extends forward substantially alongside the connecting tube 21 through the front wall 47 of the body 30 to which the rear end 2la of the connecting tube 21 is attached. As shown in Fig. 8, the temperature-sensitive valve 26 has a wax chamber 26c in one end portion thereof, and wax is sealed in the wax chamber 26c. When the ambient temperature is higher than a predetermined temperature, the wax expands and pushes a rod 29a to the left as viewed in Fig. 8 to move a valve element 29 attached to the extremity of the rod 29a to the left as viewed in Fig. 8 against the force of a valve spring 29b. When the valve element 29 is thus moved to the left, a lip 29d is separated from a valve seat 29c to open the temperature-sensitive valve 26. Consequently, clean air flows through an inlet 26b opened into the clean chamber 35 into the temperature-sensitive valve 26 as indicated by the arrow in an enlarged view and flows toward the joint 26a. The enlarged view shows a portion of the temperature-sensitive valve 26 in an open state. As shown in Figs. 11 and 12, the carburetor 22 is provided with a throttle valve 52 which is moved vertically by a throttle cable 51 to regulate the opening of an intake air passage 50. The opening of a main nozzle 54 is regulated by a jet needle 53 attached to the throttle.valve 52. Fuel metered by a main jet 56 flows from a float chamber 55, the fuel metered by the main jet 56 and mixed with air supplied through a main air bleeder 57 is supplied to the main nozzle 54. A slow port 58 opens into the air passage 50 at a position near the main nozzle 54 on the downstream side of the throttle valve 52. An auxiliary air bleed passage 60 connected to the bypass joint pipe 28 is connected to a bypass passage 59 connected to the slow port 58. Also connected to the bypass passage 59 is a slow air bleed passage 61. An upstream end of the slow air bleed passage 61 and the main air bleed passage 57 open into an upstream section of the intake air passage 50 as shown in Fig. 12. Air flowing through the slow air bleed passage 61 is mixed with fuels metered by a slow jet 62 and flows through the slow port 58. While the engine speed is low and the opening of the throttle valve is small, an air-fuel mixture is supplied through the slow port 58 to a position in the intake air passage 50 on the downstream side of the throttle valve 52, and, while the engine is hot, additional air is supplied through the auxiliary air bleed passage 60 into the intake air passage 50 in order that the air-fuel ratio of the air-fuel mixture to be supplied through the air intake passage 50 to the engine is increased. The function of the embodiment will be described hereinafter. When mounting the pressure-sensitive valve 26 on the air cleaner case 18, the cover 31 is removed, and then the pressure-sensitive valve 26 is placed substantially in parallel to the air cleaner element 33 in the clean chamber 35 formed in the body 30. The two projections 40 are pressed against the inner end surfaces of the ribs 41 and 43 with the bottom surfaces 45 seated on the projections 42 and 44, respectively, to position the pressure-sensitive valve 26, and then the lug 37 is fastened to the body 30 with the single screw 38. Subsequently, one end of the bypass tube 27 is connected to the joint 26a of the pressure-sensitive valve 26, the bypass tube 27 is extended forward substantially in parallel to the connecting tube 21, the other end of the bypass tube 27 is fitted from above on the bypass joint pipe 28, and the cover 31 is fastened to the body 30 with the screw 32. Since the pressure-sensitive valve 26 is extended along the air cleaner element 33, the lateral dimension of the space for containing the pressure-sensitive valve 26 need not be very large. Therefore, although the air cleaner case 18 contains the pressure-sensitive valve 26, the lateral dimension of the air cleaner case 18 need not be very large, the air cleaner case 18 is compact, and the body of the motor scooter can be formed in a compact construction of a relatively small width. Since the pressure-sensitive valve 26 is disposed on the upstream side of the end 2la of the connecting tube 21 connected to the air cleaner case 18 with respect to the flowing direction of air in the clean chamber 35, and is connected by the bypass tube 27 to the carburetor 22, the pressure-sensitive valve 26 can be disposed in a high space efficiency at a position other than a position near the end 2la of the connecting tube 21 where only a limited space is available, so that the air cleaner case 18 can be formed in a compact construction. Moreover, Since the connecting tube 21 is connected to the front wall 47 of the body 30 of the air cleaner case 18, the air intake duct 20 is connected to the front wall 31a of the cover 31, and the extension 36 is extended in the dirty chamber 34, the pressure-sensitive valve 26 can be disposed in the limited space without being interfered with by connecting tube 21 and the extension 36. The bypass tube 27 is extended longitudinally in parallel to the connecting tube 21 to connect the pressure-sensitive valve 26 to the carburetor 22 by the bypass tube 27 of the shortest length, which enables the omission of complicated piping, clamps and molded tubes, which has been difficult to achieve. Only the cover 31 needs to be removed when changing the air cleaner element 33, and any work for removing and attaching the pressure-sensitive valve 26 and the bypass tube 27 supported on the body 30 is not necessary, which improves maintainability. When changing the air cleaner case 18, it is necessary to disconnect only the bypass tube 27 from the bypass joint pipe 28. Since the pressure-sensitive valve 26 is screwed only at a single portion thereof to a position displaced from the extension of the end 2 la of the connecting tube 21 on one side of the same, resistance against the flow of air is reduced to improve drivability, the air cleaner case 18 can be formed in small dimensions, and work for fastening the pressure-sensitive valve 26 is reduced, the cost can be reduced and maintainability is improved. Since a portion of the air cleaner element 33 is compressed and pressed against the head 38a of the screw 38 fastening the pressure-sensitive valve 26 to the body 30 by the push rod 46 formed integrally with the cover 31, the head 38a of the screw 38 can be effectively held in place by the air cleaner element 33. The present invention is not limited in its practical application in the foregoing embodiment specifically describe herein and many changes may be made therein. For example, the bypass tube 27 may be extended along the upper or the lower surface of the cover 31 instead of laying the same inside the dirty chamber 34, and may be connected to the pressure-sensitive valve 26 disposed substantially in parallel to the air cleaner element 33 in a vertical position. WE CLAIM : 1. A temperature-sensitive valve (26) fitting structure for an air- fuel ratio controller which adjusts the supply of auxiliary air through a bypass passage (59) to a carburetor (22) by operating a temperature-sensitive valve (26) to control air-fuel ratio in a vehicle wherein: an air cleaner case (18) having a body (30) and a cover (31) is divided by an air cleaner element (33) into a right section and a left section, an air intake duct (20) is connected to said cover (31), a connecting tube (21) supplies air to said carburetor (22) air and said temperature-sensitive valve (26) placed in parallel to an air cleaner element (33) are connected to said body (30), said temperature sensitive valve (26) is connected to said carburetor (22) by bypass tube (27) placed outside of said connecting tube (21). 2. The temperature-sensitive valve fitting structure for an air-fuel ratio controller as claimed in claim 1, wherein two portions of the temperature-sensitive valve on a longitudinal line are attached to the inner surface of the air cleaner case, and one portion other than the foregoing two positions is attached to the air cleaner case with a screw. 3. The temperature-sensitive valve fitting structure for an air-fuel ratio controller as claimed in claim 2, wherein the screw fastening the portion of the temperature-sensitive valve to the air cleaner case is pressed and held in place at its head by the air cleaner element. 4. The temperature-sensitive valve fitting structure for an air-fuel ratio controller as claimed in claim 1, wherein the temperature- sensitive valve is disposed in a clean section of the air cleaner case at a position on the upstream side with respect to an air intake direction of one end connected to the air cleaner case of a connecting tube having the other end connected to the carburetor, and the temperature-sensitive valve is connected to a bypass passage formed in the carburetor by a bypass tube. 5. The temperature-sensitive valve fitting structure for an air-fuel ratio controller as claimed in claim 4, wherein the air cleaner case is held on top of a belt transmission case within a swing power unit for a motorcycle, and an air intake passage is formed in the front surface of the air cleaner case. 6. A temperature-sensitive valve fitting structure for an air-fuel ratio controller substantially as hereinbefore described with reference to the accompanying drawings.

Documents:

332-del-1998-abstract.pdf

332-del-1998-claims.pdf

332-del-1998-correspondence-others.pdf

332-del-1998-correspondence-po.pdf

332-del-1998-description (complete).pdf

332-del-1998-drawings.pdf

332-del-1998-form-1.pdf

332-del-1998-form-13.pdf

332-del-1998-form-19.pdf

332-del-1998-form-2.pdf

332-del-1998-form-3.pdf

332-del-1998-form-4.pdf

332-del-1998-form-6.pdf

332-del-1998-gpa.pdf

332-del-1998-petition-137.pdf

332-del-1998-petition-138.pdf

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