Title of Invention

STRUCTURE OF DISPOSITION OF EXHAUST SECONDARY AIR CONTROL VALVE IN MOTORCYCLE

Abstract

In a motorcycle in which an engine disposed below a main frame included in a vehicle body frame assembly and extending rearwards and downwards from a head pipe is suspended on the vehicle body frame assembly with its cylinder axis inclined forwards, and an intake device including an air cleaner and a carburetor is disposed above said engine, a secondary air control valve (48) for controlling the supplying of exhaust secondary air to an exhaust port in the engine (E) is disposed between a cell motor (50) mounted to an upper portion of the engine (E) and the carburetor (38) and between the engine (E) and the main frame(13). Thus,thesecondaryaircontrolvalvecanbedisposed effectively utilizing a space between the main frame and the engine, whereby a secondary air supply line can be shortened.

Full Text

DESCRIPTION STRUCTURE OF DISPOSITION OF EXHAUST SECONDARY AIR CONTROL VALVE IN MOTORCYCLE FIELD OF THE INVENTION The present invention relates to a motorcycle in which an engine disposed below a main frame included in a vehicle body frame assembly and extending rearwards and downwards from a head pipe is suspended on the vehicle body frame assembly with a cylinder axis thereof inclined forwards , and an intake device including an air cleaner and a carburetor is disposed above the engine, and particularly, to an improvement in a structure of disposition of an exhaust secondary air control valve. BACKGROUND ART There is a conventionally known structure in which a secondary air control valve for controlling the supplying of exhaust secondary air to an engine disposed below a main frame is disposed below a riding seat supported on a seat rail extending rearwards from the main frame, as disclosed in, for example, Japanese Patent Application Laid-open No,2000-320326. In the conventionally known structure, however, the secondary air control valve is disposed at the rear of the engine, irrespective of the presence of an unoccupied space between the main frame and the engine, because the cylinder axis of the engine is inclined forwards. As a result, a secondary air supply line connecting the secondary air control valve and the engine to each other Is lengthened. The present invention has been accomplished with such circumstances in view, and it is an object of the present invention to provide a structure of disposition of an exhaust secondary air control valve in a motorcycle, wherein the secondary air control valve is disposed effectively utilizing a space between a main freime and an engine, whereby a secondary air supply line is shortened. DISCLOSURE OF THE INVENTION To achieve the above object, according to a first aspect and feature of the present invention, there is provided a structure of disposition of an exhaust secondary air control valve in a motorcycle, the motorcycle comprising an engine disposed below a main frame included in a vehicle body frame assembly and extending rearwards and downwards from a head pipe, the engine being suspended on the vehicle body frame assembly with a cylinder axis thereof inclined forwards, and an intake device including an air cleaner and a carburetor and disposed above the engine, the structure being characterized in that a secondary air control valve for controlling the supplying of exhaust secondary air to an exhaust port in the engine is disposed between a cell motor mounted to an upper portion of the engine and the carburetor and between the engine and the main frame. With such arrangement of the first feature, the secondary air control valve can be disposed effectively in a space created between the engine having the cylinder axis inclined forwards and the main frame and between the carburetor of the intake device aisposed above the engine and the cell motor mounted to the upper portion of the engine. Moreover, the secondary air control valve is disposed in the vicinity of the engine and hence, a secondary air supply line connecting the secondary air control valve and the engine to each other can be shortened. According to a second aspect and feature of the present invention, in addition to the arrangement of the first feature, a secondary air cleaner connected to the secondary air control valve at a location upstream of the secondary air control valve is disposed on the side opposite from the carburetor with respect to a centerline passing through the widthwise center of the main frame. With such arrangement, the carburetor and the secondary air cleaner can be disposed effectively in the narrow space between the engine and the main frame in such a manner that they are disposed at locations displaced in a widthwise direction of the vehicle body frame assembly. According to a third aspect and feature of the present invention, in addition to the arrangement of the first feature, most of a secondary air supply line connecting the secondary air control valve and an exhaust port in the engine is disposed on the side opposite from the carburetor with respect to a centerline passing through the widthwise center of the main frame. With such arrangement, the carburetor and the secondary air supply line can be disposed compactly at locations closer to the main frame. BRIEF DESCRIPTION OF THE DRAWINGS Figs. 1 to 6 show an embodiment of the present invention. Fig.l is a side view of a motorcycle; Fig. 2 is a left side view of a section of the motorcycle in the vicinity of an engine; Fig.3 is a right side view of a section of the motorcycle in the vicinity of the engine; Pig. 4 is a view taken in the direction of an arrow 4 in Fig.2 with a main frame omitted; Fig.5 is an enlarged sectional view taken along a line 5-5 in Fig.3; and Fig.6 is an enlarged sectional view taken along a line 6-6 in Fig.2. BEST MODE FOR CARRYING OUT THE INVENTION Referring first to Fig.l, a vehicle body frame assembly F of a motorcycle includes a head pipe 12 for carrying a front fork 11 steerably, a main frame 13 extending rearwards and downwards from the head pipe 12, and a pair of left and right rear frames 14 connected to a rear portion of the main frame 13 and extending rearwards and upwards. A front wheel WF is rotatably carried at a lower end of the front fork 11, and a steering handlebar 15 is connected to an upper end of the front fork 11. Referring also to Figs . 2 and 3, hanger plates 16 are secured to opposite sides of an intermediate portion of the main frame 13, respectively, and pivot plates 17 are secured to opposite sides of a rear portion of the main frame 13. An engine E having a cylinder axis 01 inclined forwards is disposed below the main frame 13 and suspended on the vehicle body frame assembly F, so that it is supported on the hanger plates 16 and the pivot plates 17. Foot steps 18, on which an occupant puts his feet, are mounted on opposite sides of the engine E. A cylindrical support shaft 20 is provided on the pivot plate 17. A pair of left and right rear forks 21 are vertically oscillatably carried at their front ends on opposite ends of the support shaft 20, and a rear wheel WR is pivotally carried between rear ends of the rear forks 21. An upper portion of the rear wheel WR is covered with a rear fender 24 mounted on the rear frames 14, and a fuel tank 25 is disposed above the rear fender 24 and supported on the rear frames 14. A tandem seat 26 which is a riding seat is disposed to cover the fuel tank 25, and rear cushion units 27 are mounted between the rear frames 14 and the rear forks 21, respectively. The vehicle body frame assembly F is covered with a vehicle body cover 30 made of a synthetic resin. The vehicle body cover 30 includes a pair of left and right main frame side cover elements 31 for covering opposite sides of the main frame 13, a pair of left and right leg shields 32 fastened to front portions of the main frsmie side cover elements 31 so as to cover an occupant"s legs from the front, a front top cover element 33 leading to the leg shields 32 to cover the head pipe 12 from the front, an upper cover element 34 leading to the front top cover element 33 to cover the head pipe 12 from the rear and to cover the main frame 13 from above, an under cover element 35 leading to lower portions of the main frame side cover elements 31, and a pair of left and right rear side cover elements 36 for covering a rear portion of the vehicle body frame assembly F along with most of the fuel tank 25 from opposite sides. Referring also to Fig.4, an intake device 40 including an air cleaner 37, a carburetor 38 and an Intake pipe 39 is disposed above the engine E. A pair of mounting plate sections 37a, 37a are integrally provided at an upper portion of the air cleaner 37 to sandwich the main frame 13 from opposite sides and are fastened to opposite sides of the main frame 13 by bolts 41, 41. Namely, the air cleaner 37 is fixed to the main frame 13. The carburetor 38 disposed above a cylinder head 42 of the engine E is connected at its upstream end directly to the air cleaner 37, and the intake pipe 39 connected at its upstream end to a dovmstream end of the carburetor 38 is formed curved into a substantially C-shape and connected at its downstream end to a sidewall of an upper portion of the cylinder head 42, so that it is connected to an intake port 43 disposed in the upper portion of the cylinder head 42. An exhaust pipe 45 is connected at its upstreeim end to a sidewall of a lower portion of the cylinder head 42, so that it is connected to an exhaust port 44 disposed in the lower portion of the cylinder head 42. The exhaust pipe 45 is extended rearwards from the cylinder head 42 and connected to an exhaust muffler 46 (see Fig.l) disposed on the right of the rear wheel WR. Exhaust secondary air is supplied to the exhaust port 44 in the cylinder head 42 of the engine E, and a secondary air control valve 48 for controlling the supplying of the secondary air to the exhaust port 44 is disposed between a cell motor 50 mounted to an upper portion of a crankcase 49 in the engine E and the carburetor 38 and between the engine E and the main frame 13. Referring to Fig.5, the secondary air control valve 48 is comprised of a diaphragm actuator 52, an on-of f valve 53 driven to be closed by the diaphragm actuator 52, and a reed valve 54 for permitting only the flowing of air toward the exhaust port 44 in the engine E. The diaphragm actuator 5 2 includes a casing 5 5, a diaphragm 55 having a peripheral edge cleimped by the casing 55, and a rod 57 made of a metal and connected at one end to a central portion of the diaphragm 56. The casing 55 comprises a body 58, and a cover 59 fastened to the body 58 with the peripheral edge of the diaphragm 56 air-tightly clamped therebetween. A negative pressure chamber 60 is defined between the cover 59 and the diaphragm 56, so that one surface of the diaphragm 56 faces into the negative pressure chamber 60, and an atmospheric pressure chamber 61 is defined between the body 58 and the diaphragm 56. A connecting tube 63 having a throttle bore 62 at its tip end is connected to a central portion of the cover 59, and a negative pressure take-off line 64 leading to the Inside of the negative pressure chamber 60 through the throttle bore 62 is connected to the connecting tube 63. The negative pressure take-off line 64 Is connected to the intake pipe 39 of the intake device 40, as shown in Fig.3. Thus, a negative pressure in the intake pipe 39 is applied to the negative pressure chamber 60. The rod 57 is axially movably supported by the body 58 and connected at one end directly to a central portion of the diaphragm 56 on the side of the atmospheric pressure chamber 61. In such diaphragm actuator 52, when the negative pressure in the Intake pipe 39 is raised, the diaphragm 56 is flexed in a direction to decrease the volume of the negative pressure chamber 60, and the rod 57 is operated upwards in Fig.5. The on-off valve 53 Includes a valve housing 67, a valve member 68 secured to the other end of the rod 57, and a return spring 69 mounted between the valve housing 67 and the valve member 68. The valve housing 67 is comprised of the body 58, and a suction cover 70 air-tightly fastened to the body 58. The body 58 includes an air flow passage 71, a communication bore 72 for permitting the air flow passage 71 to communicate with the atmospheric pressure chamber 61, a valve bore 73 disposed coaxially with the rod 57 and leading to an upstream end of the air flow passage 71, a valve seat 74, Into a central portion of which the valve bore 73 opens on the side opposite from the air flow passage 71, and a support tube portion 75 inserted partially and coaxially into the valve bore 73. The rod 57 passing coaxially through the valve bore 73 is axlally slidably fitted into the support tube portion 75. A valve chest 76 is defined between the body 58 and the suction cover 70. The suction cover 70 is integrally provided with a connecting tube portion 77 leading to the valve chest 76, and the line 78 is connected at its downstream end to the connecting tube portion 77. The line 78 is connected at its upstream end to the secondary air cleaner 79 and further, an air-introducing line 80 leading to an upstream end of the secondary air cleaner 79 is extended forwards along the main frame 13 up to a point closer to the head pipe 12. Moreover, the secondary air cleaner 79 is disposed on the side opposite from the carburetor 38 with respect to a centerline C2 passing through a widthwise center of the main frame 13. The valve seat 74 is formed on the body 58 to face into the valve chest 76, and the valve member 68 is fixedly mounted at the other end of the rod 57 and accommodated in the valve chest 76, so that it can be seated on the valve seat 74. The return spring 69 is in the form of a coil surrounding the support tube portion 75 and is mounted between the body 58 and the valve member 68 to exhibit a spring force in a direction to move the valve member 68 away from the valve seat 74, i.e. , in a direction to flex the diaphragm 56 of the diaphragm actuator 52 toward the atmospheric pressure chamber 61. The reed valve 54 is supported on a valve support plate 82 formed into a disk shape and having a valve bore 81 at its central portion, so that it can open and close the valve bore 81. The valve support plate 82 is air-tightly clamped between the body 58 and a third cover 83 fastened to the body 58 to permit the valve bore 81 to communicate with the downstream of the air flow passage. A valve chest 84 is defined between the third cover 83 and the valve support plate 82, and the reed valve 54 is accommodated in the valve chest 84. A secondary air supply line 86 is connected at its upstream end to a connecting tube portion 85 which is integrally provided on the third cover 83 to lead to the valve chest 84. The secondary air supply line 86 is connected at its downstream end to a lower portion of the cylinder head 42 to lead to the exhaust port 44 in the cylinder head 42 of the engine E. Moreover, most of the secondary air supply line 86 is disposed on the side opposite from the carburetor 38 with respect to the centerline C2 passing through the wldthwise center of the main frame 13. Such secondary air control valve 48 is fixed to the main frame 13of the vehicle body frame assembly F. More specifically, a stay 87 is fastened to a side of the main frame 13, and a support flange 58a integrally provided on the body 58 to abut against the stay 87 from below is fastened to the stay 87. The fuel tank 25 disposed below the tandem seat 26 and the carburetor 38 disposed in front of and below the fuel tank 25 are connected to each other by a fuel supply line 88 extending forwards and downwards from the fuel tank 25, and a fuel cock 90 of a negative pressure operated type, which is operated by an intake negative pressure in the engine E, is Incorporated in an intermediate portion of the fuel supply line 88. Referring to Fig.6, the fuel cock 90 includes a casing 91, a diaphragm 9 2 having a peripheral edge clamped by the casing 91, a valve member 93 fixed to a central portion of the diaphragm 92, and a return spring 94 mounted between the casing 91 and the diaphragm 92. The casing 91 comprises a body 95. and a cover 96 caulked to the body 95 with the peripheral edge of the diaphragm 92 air-tightly cleunped therebetween. A negative pressure chamber 97 is defined between the cover 96 and the diaphragm 92, so that one surface of the diaphragm 92 faces into the negative pressure chamber 97. Moreover, a spring-receiving plate 98 is mounted in the negative pressure chamber 97 to abut against an inner surface of the cover 96, and the return spring 94 is mounted under compression between the diaphragm 92 and the spring-receiving plate 98 to exhibit a spring force in a direction of flexing the diaphragm 92 in a direction of increasing the volume of the negative pressure chamber 97. The cover 96 is integrally provided with a connecting tube portion 99 leading to the negative pressure chamber 97. The connecting tube portion 99 and the intake pipe 39 of the intake device 40 are connected to each other by a negative pressure take-off line 100. Thus, a negative pressure in the intake pipe 39 is introduced into the negative pressure chamber 97. A valve chest 101 is defined between the diaphragm 92 and the body 95. The body 95 is provided with a valve seat 102 on which a valve member 93 secured to a central portion of the diaphragm 92 is seated, and a valve bore 103 which opens at its downstream end into a central portion of the valve seat 102. Moreover, a line section 88a of the fuel supply line 88, which connects the fuel tank 25 and the fuel cock 90 to each other, is connected to the body 95 to lead to the valve bore 103, and a line section 88b of the fuel supply line 88, which connects the carburetor 38 and the fuel cock 90 to each other, is connected to the body 95 to lead to the valve chest 101. The intake pipe 39 is integrally provided with a mounting stay 39a overhanging toward the fuel cock 90, and a flange 95a integrally provided on the body 95 of the fuel cock 90 is fastened to a support plate 104 fastened to the mounting stay 39a. In other words, the fuel cock 90 is mounted to the intake pipe 39. In a state in which the fuel cock 90 has been mounted to the intake pipe 3 9 in this manner, the fuel cock 90 is disposed sideways of the secondary air control valve 48 below the main frame 13 and on the side opposite from the carburetor 38 with respect to the main frame 13. A bleed air supply line 105 for conducting bleed air to the carburetor 38 is mounted between the air cleaner 37 and the carburetor 38, and a bleed air cleaner 106 is mounted in an intermediate portion of the bleed air supply line 105, so that it is disposed above the secondary air cleaner 79. The operation of the present embodiment will be described below. The secondary air control valve 48 for controlling the supplying of the exhaust secondary air to the exhaust port 44 in the engine E disposed below the main frame 13 with the cylinder axis CI inclined forwards is disposed the carburetor 38 of the intake device 40 disposed above the engine E and the cell motor 50 mounted to the upper portion of the engine E and between the engine E and the main frame 13. Therefore, the secondary air control valve 48 can be disposed effectively in a space created between the engine E having the cylinder axis CI inclined forwards and the main ftame 13 and between the carburetor 38 and the cell motor 50, respectively. Moreover, the secondary air control valve 48 is disposed in the vicinity of the engine E and hence, the secondary air supply line 86 connecting the secondary air control valve 48 and the exhaust port 44 in the engine E to each other can be shortened. The secondary air cleaner 79 connected to the seconaary air control valve 48 at a location upstream of the secon(iary air control valve 48 is disposed on the side opposite from the carburetor 38 with respect to the centerline C2 passing through the widthwise center of the main frame 13, and the carburetor 38 and the secondary air cleaner 79 can be disposed effectively in the narrow space between the engine E and the main frame 13, so that they are disposed at locations displaced In a wldthwise direction of the vehicle body frame assembly F. Further, since most of the secondary air supply line 86 is disposed on the side opposite from the carburetor 38 with respect to the centerline C2 passing through the wldthwise center of the main frame 13, the carburetor 38 and the secondary air supply line 86 can be disposed compactly at locations closer to the main frame 13. Yet further, the fuel cocJc 90 of the negative pressure operated type Incorporated in an intermediate portion of the fuel supply line 88 for supplying fuel to the carburetor 48 is disposed sideways of the secondary air control valve 48 below the main frame 13 and disposed sideways of the secondary air control valve 48 disposed between the carburetor 38 and the cell motor 50. Therefore, the fuel cock 90 can be disposed in proximity to the carburetor 38, and the negative pressure take-off line 100 for conducting the negative pressure from the intake device 40 to the fuel cock 90 can be shortened. Since the fuel cock 90 is disposed on the side opposite from the carburetor 38 with respect to the main frame 13, it is possible to facilitate the arrangement of the fuel supply line 88 and the negative pressure take-off line 100. Moreover, since the fuel cock 90 is incorporated in an intermediate portion of the fuel supply line 88 extending forwards and downwards from the fuel tank 25 and connected to the carburetor 38, even If the air enters the line section 88b of the fuel supply line 88 connecting the carburetor 38 and the fuel cock 90 to each other with the stoppage of the supplying of the fuel from the fuel tank 25, the fuel can be filled quickly into the line section 88b during subsequent supplying of the fuel, even if an operation for withdrawing the air from the line section 88b is omitted. Thus, it is possible to quickly supply the fuel to the carburetor 38, while eliminating the need for a part such as a relief valve for withdrawing the air to enable a reduction in number of parts. Further, since the fuel cock 90 is mounted to the intake pipe 39 of the intake device 40, the degree of freedom for the disposition of the fuel cock 90 can be increased, as compared with a system in which a fuel cock 90 is mounted to a fuel tank 25. Although the embodiment of the present invention has been described in detail, it will be understood that the present invention is not limited to the above-described embodiment, and various modifications in design may be made without departing from the spirit and scope of the invention defined in claims. We Claim : 1. An engine of a motor cycle, said motorcycle comprises a main frame (13) in a vehicle body frame assembly (F) and extending rearwards and downwards from a head pipe (12), the engine being suspended on the vehicle body frame assembly (F) with a calmer axis (CI) thereof inclined forwards and an intake device (40) including an air cleaner (37) and a carburetor (38) and disposed above said engine (E), characterized in that a secondary air control valve (48) for controlling the supplying of exhaust secondary air to an exhaust port (44) in said engine (E) is disposed between a cell motor (50) mounted to an upper portion of said engine (E) and said carburetor (38) and between said engine (E) and the main frame (13). 2. The engine of a motorcycle according to claim 1, wherein a secondary air cleaner (79) connected to said secondary air control valve (48) at a location upstream of said secondary air control valve (48) is disposed on the side opposite from said carburetor (38) with respect to a centerline (C2) passing through the widthwise center of said main frame (13). 3. The engine of a motorcycle according to claim 1, wherein most of a secondary air supply line connecting said secondary air control valve (48) and an exhaust port (44) in said engine (E) is disposed on the side opposite fix)m said carburetor (38) with respect to a centerline (C2) passing through the widthwise center of said frame (13).

Documents:

1095-chenp-2004 abstract-duplicate.pdf

1095-chenp-2004 abstract.pdf

1095-chenp-2004 claims-duplicate.pdf

1095-chenp-2004 claims.pdf

1095-chenp-2004 correspondence-others.pdf

1095-chenp-2004 correspondence-po.pdf

1095-chenp-2004 description(complete)-duplicate.pdf

1095-chenp-2004 descritpion(complete).pdf

1095-chenp-2004 drawings-duplicate.pdf

1095-chenp-2004 drawings.pdf

1095-chenp-2004 form-1.pdf

1095-chenp-2004 form-19.pdf

1095-chenp-2004 form-26.pdf

1095-chenp-2004 form-3.pdf

1095-chenp-2004 form-5.pdf

1095-chenp-2004 pct.pdf

1095-chenp-2004 petition.pdf