Title of Invention	SWING-ARM-TYPE SUSPENSION DEVICE
Abstract	A swing-arm-type suspension device which can enhance the degree of freedom of layout of peripheral parts by making the device per se compact. In a swing-arm-type suspension device in which a swing arm which pivotally supports a rear wheel thereon is pivotally supported on a vehicle body of a motorcycle in a vertically rocking manner, and a cushion unit which attenuates the rocking of the swing arm is mounted between the vehicle body and the swing arm, the cushion unit is arranged in a laterally extending manner, and a link mechanism 31 which converts a rocking displacement of the swing arm into a stroke of the cushion unit is provided between the cushion unit and the swing arm.

Title of Invention

SWING-ARM-TYPE SUSPENSION DEVICE

Abstract

A swing-arm-type suspension device which can enhance the degree of freedom of layout of peripheral parts by making the device per se compact. In a swing-arm-type suspension device in which a swing arm which pivotally supports a rear wheel thereon is pivotally supported on a vehicle body of a motorcycle in a vertically rocking manner, and a cushion unit which attenuates the rocking of the swing arm is mounted between the vehicle body and the swing arm, the cushion unit is arranged in a laterally extending manner, and a link mechanism 31 which converts a rocking displacement of the swing arm into a stroke of the cushion unit is provided between the cushion unit and the swing arm.

Full Text	[Designation of Document] Specification [Title of the Invention] SWING-ARM-TYPE SUSPENSION DEVICE [Technical Field] [0001] The present invention relates to a swing-arm-type suspension device which is suitably applicable to a motorcycle . [Background Art] [0002] Conventionally, in the above-mentioned swing-arm-type suspension device, a cushion unit is arranged in a state that the cushion unit vertically penetrates a front portion of a swing arm, a lower portion of the cushion unit is mounted on a lower portion of the swing arm, an upper portion of the cushion unit is mounted on an upper portion of the swing arm by way of an upper link, and the upper link and a lower portion of a swing arm pivot of a vehicle body are connected to each other using a link member (for example, see patent document 1) . The link member is arranged along the cushion unit in a state that the link member penetrates the swing arm vertically. [Patent Document 1] JP-A-2004-26154 [Disclosure of the Invention] [Problems to be Solved by the Invention] [0003] The above-mentioned swing-arm-type suspension device enables the progressive attenuation using a link mechanism and facilitates the mounting and dismounting of the suspension device with respect to the vehicle body by forming the swing arm, the cushion unit and the link mechanism as a unit. However, a vertical thickness and a longitudinal length of the periphery of the cushion unit of the device per se are liable to be easily increased and, at the same time, it is also necessary to ensure a sufficient gap between the swing arm and the link member and hence, the device per se becomes large-sized thus influencing the degree of freedom in the layout of peripheral parts. There has been a demand for overcoming such a situation. Accordingly, the present invention provides a swing-arm-type suspension device which can enhance the degree of freedom in the layout of peripheral parts while making the device per se compact [Means for Solving the Problem] [0004] As means to overcome the above-mentioned drawbacks, the invention which is described in claim 1 is directed to a swing-arm-type suspension device (for example, a swing-arm-type suspension device 32, 132 of the embodiment) in which a swing arm (for example, a swing arm 25, 125 of the embodiment) which pivotally supports a wheel (for example, a rear wheel 9 of the embodiment) thereon is pivotally supported on a vehicle body (for example, a transmission case 18 of the embodiment) of a motorcycle (for example, a motorcycle 1 of the embodiment) in a vertically rocking manner, and a cushion unit (for example, a cushion unit 30 in the embodiment) which attenuates the rocking of the swing arm is mounted between the vehicle body and the swing arm, wherein the cushion unit is arranged in a laterally extending manner, and an operational direction converting mechanism (for example, a link mechanism 31 of the embodiment) which converts a rocking displacement of the swing arm into a stroke of the cushion unit is provided between the cushion unit and the swing arm. [0005] The invention described in claim 2 is characterized in that the cushion unit is arranged orthogonal to the vehicle longitudinal direction. [0006] The invention described in claim 3 is characterized in that the cushion unit is arranged within a lateral width of the swing arm. [0007] The invention described in claim 4 is characterized in that the operational direction converting mechanism is constituted by connecting a link member (for example, a link member 90 of the embodiment) and a bell crank (for example, a bell crank 80 of the embodiment). [0008] The invention described in claim 5 is characterized in that the swing arm (for example, a swing arm 25 of the embodiment) is constituted by connecting left and right arm members (for example, left and right arm members 27, 28 of the embodiment) using a cross member (for example, a cross member 29 of the embodiment) , and the cushion unit is arranged above or below the cross member, [0009] The invention described in claim 6 is characterized in that one (for example, the left arm member 27 of the embodiment) of the left and right arm members is provided linearly as viewed in a side view of a vehicle, a power transmission belt (for example, a drive chain 3 6 of the embodiment) which extends between an engine on the vehicle body side and the wheel is arranged around one arm member, another one (for example, the right arm member 28 of the embodiment) of the left and right arm members is formed in a gull shape which curves as viewed in a side view of a vehicle, and the cushion unit has one end portion thereof mounted on one arm member and another end portion thereof mounted on the operational direction converting mechanism at an inner peripheral side of a curved portion (for example, a curved portion 28b of the embodiment) of another arm member. [0010] The invention described in claim 7 is characterized in that the swing arm (for example, the swing arm 125 of the embodiment of the embodiment) is constituted by connecting the left and right arm members (for example, the left and right arm members 127, 128 of the embodiment) using a cross member (for example, a cross member 129 of the embodiment), and the cushion unit is arranged in the inside of the cross member. [0011] The invention described in claim 8 is characterized in that a vertical width of the cushion unit is set to a value which falls within a vertical width of the swing arm as viewed in a side view of a vehicle. [Advantage of the Invention] [0012] According to the invention described in claim 1, by extending the cushion unit laterally and by performing a stroke of the cushion unit by way of the operational direction converting mechanism along with the vertical rocking of the swing arm, it is possible to restrict a vertical thickness and a longitudinal length of the device per se compared to a case in which the cushion unit is extended vertically or longitudinally and hence, it is possible to enhance the degree of freedom of the layout of peripheral parts. [0013] According to the invention described in claim 2, it is possible to further restrict the longitudinal length of the device per se. [0014] According to the invention described in claim 3, it is possible to restrict a lateral width of the device per se. [0015] According to the invention described in claim 4, by allowing the operational direction converting mechanism to possess the simple constitution, it is possible to realize the enhancement of the reliability and the reduction of a manufacturing cost. [0016] According to the invention described in claim 5, the cushion unit is arranged at a portion of the swing arm in the vicinity of the cross member which exhibits the high rigidity and hence, it is possible to increase the cushion unit mounting rigidity of the swing arm. [0017] According to the invention described in claim 6, the cushion unit is arranged in a state that the cushion unit extends from one arm member which is formed linearly shape as viewed in a side view of a vehicle and another arm member which is formed in a gull shape, and the cushion unit and the operational direction converting mechanism are connected with each other on an inner peripheral side of a curved portion of another arm member, it is possible to efficiently arrange the cushion unit by effectively making use of a space around the swing arm whereby the device per se can be formed into a compact unit. [0018] According to the invention described in claim 7, it is possible to efficiently arrange the cushion unit by effectively making use of the inner space of the cross member in the swing arm and hence, the device per se can be formed into a compact unit. [0019] According to the invention described in claim 8, a vertical thickness of the device per se can be further restricted thus increasing the degree of freedom of the layout of the peripheral parts. [Best Mode for Carrying out the Invention] [0020] Hereinafter, embodiments of the present invention are explained in conjunction with drawings. Here, the directions of front, rear, left, right and the like in the explanation made hereinafter are, unless other wise specified, assumed to be equal to the corresponding directions of the vehicle. Further, in the drawings, an arrow FR indicates the frontward direction of the vehicle, an arrow LH indicates the leftward direction of the vehicle, and an arrow UP indicates upward direction of the vehicle. [Embodiment 1] [0021] A motorcycle 1 shown in Fig. 1 is a scooter-type vehicle which includes a low floor portion 2 which constitutes a footrest portion for a rider, wherein a front wheel 3 is pivotally supported on left and right front forks 4, the respective front forks 4 are pivotally supported on a head pipe 7 of a front end upper portion of a vehicle body frame 6 in a steerable manner by way of a handle stem 5, and a steering handle 8 is mounted on an upper portion of the handle stem 5. [0022] The vehicle body frame 6 is formed by integrally joining plural kinds of steel members by welding or the like. Here, the vehicle body frame 6 is mainly constituted of a down frame 11 which extends obliquely in the downward and rearward direction from the head pipe 7, a main frame 12 which extends in the rearward direction from a lower portion of the down frame 11 and passes above an engine 15 which is arranged in the inside of the low floor portion 2, and a seat frame 13 which extends obliquely in the upward and rearward directions from a rear portion of the main frame 12. [0023] The engine 15 which constitutes a prime motor of the motorcycle 1 is, for example, a water-cooled four-stroke single-cylinder engine and is configured such that a crankshaft is arranged in parallel in the lateral direction and a cylinder 17 is approximately frontwardly mounted on a front end portion of a crankcase 16 in an erected manner. A transmission case 18 is contiguously mounted on a rear portion of the crankcase 16, and a front end portion of a swing arm 25 which pivotally supports a rear wheel (a wheel) 9 is pivotally supported on a rear end portion of the transmission case 18 in a vertically rocking manner by way of a pivot shaft 26 which extends in the lateral direction. [0024] The swing arm 25 is constituted by connecting inner sides of front portions of left and right arm members 27, 28 with each other by a cross member 29, wherein the rear wheel 9 is pivotally supported on a rear end portion of the swing arm 25. A cushion unit 30 which absorbs (attenuates) the vibrations and impacts which are generated along with the vertical movement of the rear wheel 9 is arranged right below the cross member 29. The cushion unit 30 is mainly constituted of a buffer coil spring 30a and a tubular damper 30b which is arranged inside the coil spring 30a (see Fig. 3) and has the longitudinal direction (the stroke direction) thereof arranged substantially parallel to the vehicle width direction. The lateral displacement is inputted to this cushion unit 30 after the vertical locking displacement of the swing arm 25 is converted into lateral displacement by way of the link mechanism (the operational direction converting mechanism) 31. Accordingly, the swing-arm-type suspension device 32 of the motorcycle 1 is mainly constituted of the swing arm 25, the cushion unit 30 and the link mechanism 31. [0025] In the inside of the transmission case 18, a continuously variable transmission 20 which is mainly constituted of a drive pulley 21 which is arranged coaxially with the crankshaft, a driven pulley 22 which is arranged coaxially with a power transmission shaft arranged behind the crankshaft, and an endless drive belt 23 which is extended between and wound around both pulleys is housed. A rotational power of the crankshaft has a speed thereof continuously changed by way of the continuously variable transmission 20 and, at the same time, is outputted to the left side drive sprocket wheel 34 which is mounted on a rear end portion of the transmission case 18 by way of a centrifugal clutch (not shown in the drawing) and a final reduction gear mechanism 76(see Fig. 3). [0026] An endless drive chain (a power transmission belt) 36 is extended between and wound around the drive sprocket wheel 34 and a driven sprocket wheel 35 arranged on a left side of a rear wheel 9, and power transmission can be conducted between the engine 15 and the rear wheel 9 by way of the drive chain 36. Here, the drive sprocket wheel 34 is arranged coaxially with the pivot shaft 26 of the swing arm 25. [0027] A radiator 39 is arranged in front of the cylinder head 17a, an air cleaner case 40 is arranged above the radiator 39, and an intake pipe 42 which extends obliquely in the downward ^ and rearward direction from a throttle body 41 which is connected to a rear portion of the air cleaner case 4 0 is connected to an intake port formed in an upper portion of the cylinder head 17a, Further, an exhaust pipe 43 is connected to an exhaust port formed in a lower portion of the cylinder head 17a, while the exhaust pipe 43 is curved below the cylinder head 17a, passes below the crankcase 16 in the rearward direction and, thereafter, is raised obliquely in the upward and rearward direction behind the engine 15, and is connected to a silencer 44 which is arranged on a right side of a rear portion of the vehicle body. [0028] The vehicle body frame 6 and the engine 15 are covered with a synthetic resin-made vehicle body cover 46. The vehicle body cover 4 6 includes a front cowl 4 7 which covers a range which extends from a front portion of the head pipe 7 to both sides of the head pipe 7, an inner cover 4 8 which covers a rear portion of the head pipe 7, and an under cowl 49 which is contiguously formed with a lower portion of the front cowl 47 and covers both sides of a lower portion of the engine 15, a floor cover 50 which is contiguously formed with a lower portion of the inner cover 48 and covers an upper portion of the engine 15, and a rear side cover 51 which is formed on both sides of a lower portion of a seat 53 and covers both sides of the rear portion of the vehicle body. [0029] On the seat frame 13 and the rear side cover 51, a seat 53 which is integrally formed of a front seat portion for a rider and a rear seat portion for a rear pillion passenger is supported. The seat 53 is vertically rotatable about a hinge shaft 54 which is mounted on a front end portion thereof and hence, the rider can open or close an article accommodating box 55 which is arranged below the front seat portion and, at the same time, can get access to a fuel tank 56 which is arranged below the rear seat portion. The article accommodating box 55 has a front portion thereof positioned above a rear portion of the crankcase 16 and a rear portion thereof positioned above a front portion of the swing arm 25. Further, the article accommodating box 55 has a rear side of the bottom portion thereof inclined in the rearward and upward direction so as to ensure a gap which is used at the time of rocking the swing arm 25. [0030] The down frame 11 of the vehicle body frame 6 is mainly constituted of an upper down pipe 58 which is bifurcated to left and right sides from an upper portion of the head pipe 7 and extends obliquely in the downward and rearward direction, and a lower down pipe 59 which is bifurcated to a left and right sides from a lower portion of the head pipe 7 and extends obliquely in the downward and rearward direction more steeply than the upper down pipe 58. [0031] Between the lower portion of the head pipe 7 and the upper middle portion of the upper down pipe 58, a gusset pipe 60 which is arranged substantially horizontally is extended, wherein an upper end portion of the lower down pipe 59 is joined to a lower portion of the head pipe 7 by way of the gusset pipe 60. Here, in the drawing, numeral 61 indicates a gusset plate which strides over an upper portion of the lower down pipe 59, a front portion of the gusset pipe 60 and a lower portion of the head pipe 7. [0032] On a lower portion of the lower down pipe 59, a front engine hanger bracket 62 which extends obliquely in the downward and rearward direction in the same manner is contiguously formed, a front lower engine hanger 63 is fastened to a lower end portion of the engine hanger bracket 62, and a rear end portion of the front lower engine hanger 63 is fastened to a lower side of a front portion of the crankcase 16 of the engine 15 thus supporting the engine 15. [0033] The main frame 12 is mainly constituted of a pair of left and right main pipes 65 which correspond to left and right upper down pipes 58 and lower down pipes 59. The main pipes 65 are arranged substantially horizontally at a center portion of the vehicle body and have middle portions thereof slightly curved to project upwardly as viewed in a side view of the vehicle. Front end portions of the main pipes 65 are joined to lower portions of the lower down pipes 59 from behind and, at the same time, lower end portions of the upper down pipes 58 are joined to front portions of the main pipes 65 from above. [0034] The main pipes 65 (main frames 12) extend from a position above the cylinder head 17a of the engine 15 to a position above the swing arm pivotally supporting portion 18a formed on a rear end portion of the transmission case 18, while rear engine hanger brackets 66 which extend rearwardly are mounted on rear end portions of the main pipes 65 contiguously. Further, on lower portions of the engine hanger brackets 66, rear upper engine hangers 67 which project downwardly are mounted, and lower end portions of the rear upper engine hangers 67 are connected to an upper side of a rear portion of the transmission case 18 thus supporting the transmission case 18. [0035] Further, the front upper engine hangers 68 are fastened to the front portions of the main pipes 65 which constitute a joining portion with the upper down pipes 58, and lower end portions of the front upper engine hangers 68 are fastened to an upper side of a front portion of the crankcase 16 of the engine 15 thus supporting the engine 15. The engine 15 is suspended from the vehicle body frame 6 using the front upper engine hanger 68 and the respective engine hangers 63, 67. [0036] The seat frame 13 is mainly constituted of left and right seat pipes 70 which extend obliquely in the upward and rearward direction from the vicinity of the curved portions of the left and right main pipes 65, and left and right rear pipes 71 which extend obliquely in the upward and rearward direction from rear end portions of the left and right main pipes 65. The seat pipes 7 0 have middle portions thereof bent such that the middle portions project obliquely in the front and upward direction as viewed in a side view of the vehicle and have rear end portions thereof connected to each other and hence, the seat pipes 70 are integrally formed in the lateral direction. Rear portions of the seat pipes 70 and rear portions of the rear pipes 71 are joined by way of rear side plates 72. Further, to bent portions of the seat pipes 70, upper end portions of rear gusset pipes 73 which extend obliquely in the upward and rearward direction with a steep inclination from rear end portions of the main pipes 65 are joined from below. [0037] As shown in Fig. 2, in the swing-arm-type suspension device 32, a front end portion of the swing arm 25 which pivotally supports the rear wheel 9 is vertically mounted in a rocking manner on the transmission case 18 of the engine 15 which constitutes the vehicle body side, and one side of the cushion unit 30 which attenuates the rocking of the swing arm 25 is mounted on the swing arm 25 and another side of the cushion unit 30 is mounted on a lower side of a rear end portion of the engine 15 (below the pivot shaft 26) by way of the link mechanism 31. [0038] To explain this embodiment also in conjunction with Fig. 3, in a vehicle-width-direction center portion in the inside of the rear end portion of the transmission case 18, a final reduction gear mechanism 76 which is constituted of a pair of reduction gears which performs the speed reduction of an output of the continuous variable transmission 20 is housed. On a left side of the rear end portion of the transmission case 18, a cylindrical left pivot shaft 26L which rotatably and pivotally supports a distal end portion of the left arm member 27 of the swing arm 25 is mounted in a projecting manner, while on a right side of the rear end portion of the transmission case 18, a cylindrical right pivot shaft 26R which pivotally and rotatably supports a distal end portion of the right arm member 28 of the swing arm 25 is fixedly mounted. [0039] In the inside of the left pivot shaft 2 6L, an output shaft (an engine output shaft) 77 of the final reduction gear mechanism 76 is rotatably and pivotally supported. Here, on a vehicle-width-direction inner side of the output shaft 77 (a projecting portion in the inside of the transmission case 18) , a final gear 7 8 which constitutes a final power transmission member of the final reduction gear mechanism 76 is mounted. On the other hand, on a vehicle-width-direction outer side of the output shaft 77 (a projecting portion to the outside of the transmission case 18), the drive sprocket 34 is mounted. The end portion on the vehicle-width-direction outer side of the output shaft 77 (eventually the left pivot shaft 26L) is supported on a rear-end-portion left side of the transmission case 18 by way of the holder 37. [0040] Between a rear end portion of the left arm member 27 and a hub portion of the rear wheel 9 of the vehicle-width-direction inner side, a driven sprocket wheel 35 is arranged. The above-mentioned drive chain 3 6 is extended between and wound around the driven sprocket wheel 35 and the drive sprocket wheel 34 mounted on the vehicle-width-direction outer side of the front end portion of the left arm member 27. Accordingly, when the swing arm is viewed in a plan view, the left arm member 27 is displaced to the vehicle-width-direction outer side to avoid the drive chain 36 behind a left pivot inserting portion 27a which constitutes a distal end portion of the left arm member 27 and, thereafter, extends toward the vehicle-width-direction outer side of the driven sprocket wheel 35 and pivotally supports the left side of the rear wheel 9. On the other hand, the right arm member 28 extends rearwardly substantially linearly from the right pivot inserting portion 28a which constitutes the distal end portion to pivotally support the rear wheel 9. [0041] Further, when the swing arm 25 is viewed in a side view (as viewed in a side view of the vehicle) , the left arm member 27 extends substantially linearly to an axle position of the rear wheel 9 from the left pivot inserting portion 27a. Due to such a constitution, it is possible to ensure the rigidity against a compressive weight inputted to the left arm member 27 by way of the drive chain 36. On the other hand, the right arm member 28 is formed into a so-called gull shape which is curved in an L-shape as viewed in a side view to project a portion of the right arm member 28 which is positioned between a rear end portion of the transmission case 18 and a front end portion of the rear wheel 9 (a front side than a longitudinal center portion of the right arm member 28 per se) upwardly. [0042] To explain this embodiment also in conjunction with Fig. 4, on the vehicle-width-direction inner side of a curved portion 28b of the right arm member 28 which is positioned between the transmission case 18 and the rear wheel 9, a cross member 29 which integrally connects the left and right arm members 27, 28 is arranged. The cross member 29 has a right end portion thereof joined to the vehicle-width-direction inner side of the curved portion 28b, extends to the vicinity of the left arm member 27 while maintaining a shape which allows the cross member 29 to be substantially overlapped to the curved portion 28b in a side view of the swing arm and, thereafter, is gradually changed downwardly, and has a left end portion thereof joined to the front vehicle-width-direction inner side of the left arm member 27. Such a cross member 29 is formed of a hollow structural body made of aluminum alloy, for example, in the same manner as the left and right arm members 27, 28. The cross member 29 has, to attenuate the stress concentration at joining portions thereof with the left and right arm members 27, 28, particularly a rear side thereof curved and extended rearwardly to form a spreading fan shape in a plan view of the swing arm. [0043] The cushion unit 30 is arranged such that the cushion unit 30 extends laterally between the transmission case 18 and the rear wheel 9 and right below the cross member 29 of the swing arm 25 . The cushion unit 30 has a left end portion thereof mounted on the vehicle-width-direction inner side of the left arm member 27 of the swing arm 25 in an abutting manner and has a right end portion thereof mounted on a lower side of a rear end portion of the transmission case 18 by way of the link mechanism 31. In such a state, a total length of the cushion unit 30 substantially falls within a lateral width of the swing arm 25. [0044] By converting the vertical movement of the rear wheel 9, that is, the vertical rocking displacement of the swing arm 25 into the lateral displacement and by inputting the lateral displacement to the right end portion of the cushion unit 30 by way of the link mechanism 31, the cushion unit 30 performs a stroke so that an impact or vibrations attributed to the vertical movement of the rear wheel 9 is converted into the elongation and contraction of the coil spring 30a and, at the same time, the impact or vibrations are attenuated and are gradually absorbed by the elongation and contraction of the damper 30b. [0045] The link mechanism 31 includes a bell crank 80 which is supported on the swing arm 25 in a rocking manner, and a link member 90 which is extended between the bell crank 80 and the transmission case 18. The bell crank 80 is pivotally supported on a bell crank support shaft 28c which is formed on the right arm member 28 located at an oblique downward and rearward position from the right pivot inserting portion 28a. The bell crank 80 can be rocked about a rocking shaft 81 which is inclined frontwardly in a state that the rocking shaft 81 is inclined more frontwardly corresponding to a distance in the upward direction. [0046] The bell crank 80 includes a first arm portion 83 which extends toward the vehicle-width-direction inner side obliquely and rearwardly from the shaft inserting portion 82 in which the rocking shaft 81 is inserted, and a second arm portion 84 which extends toward the vehicle-width-direction outer side obliquely and rearwardly from the shaft inserting portion 82. The respective arm portions 83, 84 are arranged to make a right angle therebetween as viewed in a plan view along the rocking shaft 81, and a length of the second arm portion 84 is set larger than the first arm portion 83. [0047] To a first connecting portion 85 which constitutes a distal end of the first arm portion 83, a rear end portion of the link member 90 which is inclined frontwardly and downwardly is connected by way of a first connecting shaft 87 which is arranged parallel to the rocking shaft 81 in a rocking manner. On the other hand, to a second connecting portion 8 6 which constitutes a distal end portion of the second arm portion 84, a right end portion of the cushion unit 30 is connected in a rocking manner by way of a second connecting shaft 88 which is arranged parallel to the rocking shaft 81. [0048] Here, the second arm portion 84 and the right end portion of the cushion unit 30 are arranged on an inner peripheral side (a lower side) of the curved portion 28b of the right arm member 28. In other words, the right arm member 28 is formed in a gull shape to avoid the cushion unit 30 and the bell crank 80. In such a state, the cushion unit 30 falls within a vertical width of the left arm member 27 as viewed in a side view of the vehicle and, at the same time, the bell crank 80 also falls within a vertical width of the left arm member 27 as viewed in a side view of the vehicle. [0049] A front end portion of the link member 90 is connected in a rocking manner to an arm connecting portion 90a which is formed on a lower side of a rear end portion (lower than the pivot shaft 26) of the transmission case 18 by way of an arm connecting shaft 90b which is arranged parallel to the vehicle width direction. When the swing arm 25 is vertically rocked along with the vertical movement of the rear wheel 9, due to an input from the link member 90 which is connected to the vehicle body side, the bell crank 80 is rocked about the rocking shaft 81 thus imparting a stroke to the cushion unit 30. Here, front and rear end portions of the link member 90 are configured to be rocked also in the direction orthogonal to the first connecting portion 85 and the arm connecting shaft 90b. [0050] The link member 90 which receives a reaction (a cushion weight) at the time of imparting a stroke to the cushion unit 30 is connected to the vehicle body side at a position below the pivot shaft 26. Accordingly, a frame member or the like which receives the cushion load is unnecessary above the pivot shaft 26. [0051] Further, by arranging the cushion unit 30 below the cross member 29 of the swing arm 25 in a state that the longitudinal direction of the cushion unit 30 is arranged along the vehicle-width direction, compared to a case in which the longitudinal direction of the cushion unit 30 is arranged in the vertical direction or in the longitudinal direction of the vehicle, it is possible to restrict a longitudinal length and a vertical thickness of the swing-arm-type suspension device around the cushion unit 30. [0052] Due to such a constitution, it is possible to easily ensure a rocking space of the swing-arm-type suspension device 32 and hence, it is possible to enhance the degree of freedom in the layout of peripheral parts of the swing-arm-type suspension device 32. Particularly, in a vehicle which has the large article accommodating box 55 below the seat 53 as in the case of the motorcycle 1, a volume of the article accommodating box 55 can be enlarged and hence, this constitution is preferably adopted. [0053] As has been explained above, the swing-arm-type suspension device 32 of the above-mentioned embodiment is configured such that the swing arm 25 which pivotally supports the rear wheel 9 thereon is pivotally supported on the vehicle body (the transmission case 18) of the motorcycle 1 in a vertically rocking manner, and the cushion unit 30 which attenuates the rocking of the swing arm 25 is mounted between the vehicle body and the swing arm 25, wherein the cushion unit 30 is arranged in a laterally extending manner, and the link mechanism 31 which converts a rocking displacement of the swing arm 25 into a stroke of the cushion unit 30 is provided between the cushion unit 30 and the swing arm 25. [0054] According to such a constitution, by extending the cushion unit 30 laterally and by imparting a stroke to the cushion unit 30 by way of the link mechanism 31 along with the vertical rocking of the swing arm 25, it is possible to restrict a vertical thickness and a longitudinal length of the device per se compared to a case in which the cushion unit 30 is extended vertically or longitudinally and hence, it is possible to enhance the degree of freedom in the layout of the peripheral parts. Particularly, this embodiment is preferably applicable to the motorcycle 1 which includes the large article accommodating space below the seat 53. [0055] Further, in the above-mentioned swing-arm-type suspension device 32, by arranging the cushion unit 30 orthogonal to the longitudinal direction of the vehicle, it is possible to further restrict the longitudinal length of the device per se. [0056] Further, in the above-mentioned swing-arm-type suspension device 32, by arranging the cushion unit 30 within the lateral width of the swing arm 25, it is possible to restrict the lateral width of the device per se. [0057] Still further, in the above-mentioned swing-arm-type suspension device 32, by constituting the link mechanism 31 by connecting the link member 90 and the bell crank 80, it is possible to simplify the link mechanism 31 and hence, it is possible to realize the enhancement of the reliability and the reduction of a manufacturing cost. [0058] Further, in the above-mentioned swing-arm-type suspension device 32, the swing arm 25 is constituted by connecting the left and right arm members 27, 28 using the cross member 29, and the cushion unit 30 is arranged below the cross member 29 and hence, the cushion unit 30 is arranged at a portion of the swing arm 25 in the vicinity of the cross member 29 which exhibits the high rigidity whereby it is possible to increase the mounting rigidity of the cushion unit 30. [0059] Here, in the above-mentioned swing-arm-type suspension device 32, the left arm member 27 is formed linearly as viewed in a side view of the vehicle, and the drive chain 36 which extends between the vehicle-body-side engine 15 and the rear wheel 9 is arranged around the left arm member 27. On the other hand, the right arm member 28 is formed in the curved gull shape as viewed in a side view of the vehicle, a left end portion of the cushion unit 30 is mounted on the left arm member 27, and a right end portion of the cushion unit 30 is mounted on the link mechanism 31 on the inner peripheral side of the curved portion 28b of the right arm member 28. [0060] Due to such a constitution, the cushion unit 30 is arranged in a state that the cushion unit 30 extends from the left arm member 27 which is formed linearly as viewed in a side view of the vehicle to the right arm member 28 which is formed in a gull shape, and the cushion unit 30 and the link mechanism 31 are connected with each other on the inner peripheral side of the curved portion 28b of the right arm member 28 and hence, it is possible to efficiently arrange the cushion unit 30 by making use of a space around the swing arm 25 whereby the device per se can be formed into a compact unit. [0061] Further, in the above-mentioned swing-arm-type suspension device 32, by setting the vertical widths of the cushion unit 30 and the bell crank 80 to values which fall within the vertical width of the left arm member 27 of the swing arm 25 as viewed in a side view of the vehicle, the vertical thickness of the device per se can be further restricted thus increasing the degree of freedom in the layout of the peripheral parts. [Embodiment 2] [0062] Next, a second embodiment of the present invention is explained. The second embodiment differs from the first embodiment mainly with respect to a point that both of left and right arm members of the swing arm are formed linearly as viewed in a side view of the vehicle, and the cushion unit which extends in the vehicle-width direction is arranged in the inside of the cross member which connects the left and the right arm members and hence, parts identical with the parts of the first embodiment are given same symbols and their explanation is omitted. [0063] As shown in Fig. 5, in a swing-arm-type suspension device 132, a front end portion of a swing arm 125 which pivotally supports a rear wheel 9 is mounted in a vertically rocking manner on a transmission case 18 of an engine 15 which constitutes a vehicle body side, and one side of the cushion unit 30 which attenuates the rocking of the swing arm 125 is mounted on the swing arm 125 and another side of the cushion unit 30 is mounted on a lower side of a rear end portion of the engine 15 by way of the link mechanism 31. [0064] To explain also in conjunction with Fig. 6, the swing arm 125 has front inner sides of left and right arm members 127,128 thereof connected to each other using a cross member 129. A distal end portion (a left pivot inserting portion 127a) of the left arm member 127 is rotatably and pivotally supported on a left pivot shaft 26L on a left side of a rear end portion of the transmission case 18, while a distal end portion (a right pivot inserting portion 128a) of the right arm member 128 is rotatably and pivotally supported on a right pivot shaft 2 6R on a right side of the rear end portion of the transmission case 18. These left and right arm members 127, 128 extend rearwardly substantially linearly to an axle position of the rear wheel 9 from the left and right pivot inserting portions 127a, 128a and pivotally support the rear wheel 9 as viewed in a plan view and a side view of the swing arm. [0065] Between the transmission case 18 and the rear wheel 9, a cross member 129 which integrally connects the left and right arm members 127, 128 to each other is arranged. The cross member 129 is configured to extend between the left and right arm members 127, 128 as viewed in a side view of the swing arm while maintaining a shape which allows the cross member 129 to be substantially overlapped to the left and right pivot inserting portions 127a, 128a in a side view of the swing arm, and such a cross member 129 is formed of a hollow structural body made of aluminum alloy, for example, in the same manner as the left and right arm members 127, 128. Both end portions of the cross member 129 are extended rearwardly by curving particularly rear sides of such both end portions to form a spreading fan shape in a plan view of the swing arm. [0066] To explain also in conjunction with Fig. 7, the cushion unit 30 is arranged such that the cushion unit 30 extends in the lateral direction in the inside of the cross member 129, wherein a left end portion of the cushion unit 30 is mounted on the left arm member 127 in a state that the left end portion is inserted into the inside of the left arm member 127 and, at the same time, a right end portion of the cushion unit 30 is connected to a lower side of a rear end portion of the transmission case 18 by way of the link mechanism 31. In such a state, the cushion unit 30 and the link mechanism 31 are arranged on a slightly left side compared to the first embodiment and a total length of the cushion unit 30 falls within a lateral width of the swing arm 125. [0067] At an oblique, downward and rearward position of the right pivot inserting portion 12 8a and on a slightly vehicle-width-direction inner side of the right armmember 128, a bell-crank support portion 128c which pivotally supports a bell crank 80 of the link mechanism 31 by way of a rocking shaft 81 which is inclined such that an upper side is positioned more frontwardly is formed. In the bell-crank support portion 128c and a vehicle-width-direction outer side of the right arm member 128, an opening 128d for mounting and dismounting the cushion unit 30 and the link mechanism 31 is formed. [0068] When the swing arm 125 is vertically rocked along with the vertical movement of the rear wheel 9, due to an input imparted from the link member 90 which is connected to the vehicle body side, the bell crank 80 is rocked about the rocking shaft 81 thus imparting a stroke to the cushion unit 30 and hence, impacts and vibrations which are generated due to the vertical movement of the rear wheel 9 can be attenuated and gradually absorbed. [0069] As has been explained above, in the swing-arm-type suspension device 132 of the above-mentioned second embodiment, by arranging the cushion unit 30 which extends laterally in the inside of the cross member 129 of the swing arm 125, it is possible to restrict the longitudinal length about the cushion unit 30 of the device per se as well as the vertical thickness of the device per se . Further, by effectively making use of the inner space of the cross member 129 of the swing arm 125, it is possible to efficiently arrange the cushion unit 30. Accordingly, it is possible to more surely acquire a rocking space for the device per se and hence, the degree of freedom in the layout of the peripheral parts can be further enhanced, and device per se can be formed into a compact unit. [0070] Here, the present invention is not limited to the above-mentioned embodiments. For example, in the first embodiment, the cushion unit 30 which extends laterally is configured to be arranged above the cross member 29 of the swing arm 25 in place of being arranged below the cross member 29 of the swing arm 25. Here, the right arm member 28 of the swing arm 25 may be curved such that the right arm member 28 projects downwardly and the cushion unit 30 is arranged on an inner peripheral side (an upper side) of the curved portion. In this case, it is possible to obtain an advantageous effect that the cushion unit 30 is protected by the cross member 29. Further, the cushion unit 30 which extends laterally may be configured such that the cushion unit 30 is arranged above or below the transmission case 18 and has one side thereof mounted on the transmission case 18 and another side thereof mounted on the swing arm 25 by way of the link mechanism 31. Further, the swing arms 25, 125 may be configured such that the swing arms 25, 125 are pivotally supported on the vehicle body frame 6 in place of the engine 15 or are pivotally supported on both of the engine 15 and the vehicle body frame 6. Further, the constitutions of the above-mentioned embodiments merely constitute one example of the present invention and it is needless to say that the engine type and the detailed constitution of the vehicle body frame are not limited to the above-mentioned embodiments and various modifications are conceivable without departing from the gist of the present invention. [Brief Description of the Drawings] [0071] [Fig. 1] A side view of a motorcycle of a first embodiment of the present invention. [Fig. 2] A side view of a swing-arm-type suspension device of the above-mentioned motorcycle. [Fig. 3] A planar explanatory view of the above-mentioned swing-arm-type suspension device. [Fig. 4] A perspective view of a front portion of the above-mentioned swing-arm-type suspension device as viewed from an oblique downward direction. [Fig. 5] A side view of a swing-arm-type suspension device of a second embodiment of the present invention. [Fig. 6] A planar explanatory views of the swing-arm-type suspension device in Fig. 5. [Fig. 7] A perspective view of a front portion of the swing-arm-type suspension device as viewed from an oblique downward direction in Fig. 5. [Description of Reference Numerals and Signs] [0072] 1: motorcycle 9: rear wheel (wheel) 18: transmission case (vehicle body) 25, 125: swing arm 27, 127: left arm member 28, 128: right arm member 28b: curved portion 29, 129: cross member 30: cushion unit 31: link mechanism (operational direction converting mechanism) 32, 132: swing-arm-type suspension device 36: driving chain (power transmission belt) 80: bell crank 90: link member [Designation of Document] Claims [Claim 1] A swing-arm-type suspension device in which a swing arm which pivotally supports a wheel thereon is pivotally supported on a vehicle body of a motorcycle in a vertically rocking manner, and a cushion unit which attenuates the rocking of the swing arm is mounted between the vehicle body and the swing arm, wherein the cushion unit is arranged in a laterally extending manner, and an operational direction converting mechanism which converts a rocking displacement of the swing arm into a stroke of the cushion unit is provided between the cushion unit and the swing arm. [Claim 2] A swing-arm-type suspension device according to claim 1, wherein the cushion unit is arranged orthogonal to the vehicle longitudinal direction. [Claim 3] A swing-arm-type suspension device according to claim 1 or claim 2, wherein the cushion unit is arranged within a lateral width of the swing arm. [Claim 4] A swing-arm-type suspension device according to any one of claim 1 to claim 3, wherein the operational direction converting mechanism is constituted by connecting a link member and a bell crank. [Claim 5] A swing-arm-type suspension device according to any one of claim 1 to claim 4, wherein the swing arm is constituted by connecting left and right arm members using a cross member, and the cushion unit is arranged above or below the cross member. [Claim 6] A swing-arm-type suspension device according to any one of claim 1 to claim 5, wherein one of the left and right arm members is provided linearly as viewed in a side view of a vehicle, a power transmission belt which extends between an engine on the vehicle body side and the wheel is arranged around one arm member, another one of the left and right arm members is formed in a gull shape which curves as viewed in a side view of a vehicle, and the cushion unit has one end portion thereof mounted on one arm member and another end portion thereof mounted on the operational direction converting mechanism at an inner peripheral side of a curved portion of another arm member. [Claim 7] A swing-arm-type suspension device according to any one of claim 1 to claim 4, wherein the swing arm is constituted by connecting the left and right arm members using a cross member, and the cushion unit is arranged in the inside of the cross member. [Claim 8] A swing-arm-type suspension device according to any one of claim 4 to claim 7, wherein a vertical width of the cushion unit is set to a value which falls within a vertical width of the swing arm as viewed in a side view of a vehicle.

Full Text

[Designation of Document] Specification
[Title of the Invention] SWING-ARM-TYPE SUSPENSION DEVICE
[Technical Field]
[0001]
The present invention relates to a swing-arm-type suspension device which is suitably applicable to a motorcycle . [Background Art] [0002]
Conventionally, in the above-mentioned swing-arm-type suspension device, a cushion unit is arranged in a state that the cushion unit vertically penetrates a front portion of a swing arm, a lower portion of the cushion unit is mounted on a lower portion of the swing arm, an upper portion of the cushion unit is mounted on an upper portion of the swing arm by way of an upper link, and the upper link and a lower portion of a swing arm pivot of a vehicle body are connected to each other using a link member (for example, see patent document 1) . The link member is arranged along the cushion unit in a state that the link member penetrates the swing arm vertically. [Patent Document 1] JP-A-2004-26154 [Disclosure of the Invention] [Problems to be Solved by the Invention] [0003]
The above-mentioned swing-arm-type suspension device enables the progressive attenuation using a link mechanism and

facilitates the mounting and dismounting of the suspension device with respect to the vehicle body by forming the swing arm, the cushion unit and the link mechanism as a unit. However, a vertical thickness and a longitudinal length of the periphery of the cushion unit of the device per se are liable to be easily increased and, at the same time, it is also necessary to ensure a sufficient gap between the swing arm and the link member and hence, the device per se becomes large-sized thus influencing the degree of freedom in the layout of peripheral parts. There has been a demand for overcoming such a situation.
Accordingly, the present invention provides a swing-arm-type suspension device which can enhance the degree of freedom in the layout of peripheral parts while making the device per se compact [Means for Solving the Problem] [0004]
As means to overcome the above-mentioned drawbacks, the invention which is described in claim 1 is directed to a swing-arm-type suspension device (for example, a swing-arm-type suspension device 32, 132 of the embodiment) in which a swing arm (for example, a swing arm 25, 125 of the embodiment) which pivotally supports a wheel (for example, a rear wheel 9 of the embodiment) thereon is pivotally supported on a vehicle body (for example, a transmission case 18 of the embodiment) of a motorcycle (for example, a motorcycle 1 of

the embodiment) in a vertically rocking manner, and a cushion unit (for example, a cushion unit 30 in the embodiment) which attenuates the rocking of the swing arm is mounted between the vehicle body and the swing arm, wherein the cushion unit is arranged in a laterally extending manner, and an operational direction converting mechanism (for example, a link mechanism 31 of the embodiment) which converts a rocking displacement of the swing arm into a stroke of the cushion unit is provided between the cushion unit and the swing arm. [0005]
The invention described in claim 2 is characterized in that the cushion unit is arranged orthogonal to the vehicle longitudinal direction. [0006]
The invention described in claim 3 is characterized in that the cushion unit is arranged within a lateral width of the swing arm. [0007]
The invention described in claim 4 is characterized in that the operational direction converting mechanism is constituted by connecting a link member (for example, a link member 90 of the embodiment) and a bell crank (for example, a bell crank 80 of the embodiment). [0008]
The invention described in claim 5 is characterized in

that the swing arm (for example, a swing arm 25 of the embodiment) is constituted by connecting left and right arm members (for example, left and right arm members 27, 28 of the embodiment) using a cross member (for example, a cross member 29 of the embodiment) , and the cushion unit is arranged above or below the cross member, [0009]
The invention described in claim 6 is characterized in that one (for example, the left arm member 27 of the embodiment) of the left and right arm members is provided linearly as viewed in a side view of a vehicle, a power transmission belt (for example, a drive chain 3 6 of the embodiment) which extends between an engine on the vehicle body side and the wheel is arranged around one arm member, another one (for example, the right arm member 28 of the embodiment) of the left and right arm members is formed in a gull shape which curves as viewed in a side view of a vehicle, and the cushion unit has one end portion thereof mounted on one arm member and another end portion thereof mounted on the operational direction converting mechanism at an inner peripheral side of a curved portion (for example, a curved portion 28b of the embodiment) of another arm member. [0010]
The invention described in claim 7 is characterized in that the swing arm (for example, the swing arm 125 of the

embodiment of the embodiment) is constituted by connecting the left and right arm members (for example, the left and right arm members 127, 128 of the embodiment) using a cross member (for example, a cross member 129 of the embodiment), and the cushion unit is arranged in the inside of the cross member. [0011]
The invention described in claim 8 is characterized in that a vertical width of the cushion unit is set to a value which falls within a vertical width of the swing arm as viewed in a side view of a vehicle. [Advantage of the Invention] [0012]
According to the invention described in claim 1, by extending the cushion unit laterally and by performing a stroke of the cushion unit by way of the operational direction converting mechanism along with the vertical rocking of the swing arm, it is possible to restrict a vertical thickness and a longitudinal length of the device per se compared to a case in which the cushion unit is extended vertically or longitudinally and hence, it is possible to enhance the degree of freedom of the layout of peripheral parts. [0013]
According to the invention described in claim 2, it is possible to further restrict the longitudinal length of the device per se.

[0014]
According to the invention described in claim 3, it is possible to restrict a lateral width of the device per se.
[0015]
According to the invention described in claim 4, by allowing the operational direction converting mechanism to possess the simple constitution, it is possible to realize the enhancement of the reliability and the reduction of a manufacturing cost.
[0016]
According to the invention described in claim 5, the cushion unit is arranged at a portion of the swing arm in the vicinity of the cross member which exhibits the high rigidity and hence, it is possible to increase the cushion unit mounting rigidity of the swing arm.
[0017]
According to the invention described in claim 6, the cushion unit is arranged in a state that the cushion unit extends from one arm member which is formed linearly shape as viewed in a side view of a vehicle and another arm member which is formed in a gull shape, and the cushion unit and the operational direction converting mechanism are connected with each other on an inner peripheral side of a curved portion of another arm member, it is possible to efficiently arrange the cushion unit by effectively making use of a space around the

swing arm whereby the device per se can be formed into a compact unit.
[0018]
According to the invention described in claim 7, it is possible to efficiently arrange the cushion unit by effectively making use of the inner space of the cross member in the swing arm and hence, the device per se can be formed into a compact unit.
[0019]
According to the invention described in claim 8, a vertical thickness of the device per se can be further restricted thus increasing the degree of freedom of the layout of the peripheral parts.
[Best Mode for Carrying out the Invention]
[0020]
Hereinafter, embodiments of the present invention are explained in conjunction with drawings. Here, the directions of front, rear, left, right and the like in the explanation made hereinafter are, unless other wise specified, assumed to be equal to the corresponding directions of the vehicle. Further, in the drawings, an arrow FR indicates the frontward direction of the vehicle, an arrow LH indicates the leftward direction of the vehicle, and an arrow UP indicates upward direction of the vehicle. [Embodiment 1]

[0021]
A motorcycle 1 shown in Fig. 1 is a scooter-type vehicle which includes a low floor portion 2 which constitutes a footrest portion for a rider, wherein a front wheel 3 is pivotally supported on left and right front forks 4, the respective front forks 4 are pivotally supported on a head pipe 7 of a front end upper portion of a vehicle body frame 6 in a steerable manner by way of a handle stem 5, and a steering handle 8 is mounted on an upper portion of the handle stem 5. [0022]
The vehicle body frame 6 is formed by integrally joining plural kinds of steel members by welding or the like. Here, the vehicle body frame 6 is mainly constituted of a down frame 11 which extends obliquely in the downward and rearward direction from the head pipe 7, a main frame 12 which extends in the rearward direction from a lower portion of the down frame 11 and passes above an engine 15 which is arranged in the inside of the low floor portion 2, and a seat frame 13 which extends obliquely in the upward and rearward directions from a rear portion of the main frame 12. [0023]
The engine 15 which constitutes a prime motor of the motorcycle 1 is, for example, a water-cooled four-stroke single-cylinder engine and is configured such that a crankshaft is arranged in parallel in the lateral direction and a cylinder

17 is approximately frontwardly mounted on a front end portion
of a crankcase 16 in an erected manner. A transmission case
18 is contiguously mounted on a rear portion of the crankcase
16, and a front end portion of a swing arm 25 which pivotally
supports a rear wheel (a wheel) 9 is pivotally supported on
a rear end portion of the transmission case 18 in a vertically
rocking manner by way of a pivot shaft 26 which extends in the
lateral direction.
[0024]
The swing arm 25 is constituted by connecting inner sides of front portions of left and right arm members 27, 28 with each other by a cross member 29, wherein the rear wheel 9 is pivotally supported on a rear end portion of the swing arm 25. A cushion unit 30 which absorbs (attenuates) the vibrations and impacts which are generated along with the vertical movement of the rear wheel 9 is arranged right below the cross member 29. The cushion unit 30 is mainly constituted of a buffer coil spring 30a and a tubular damper 30b which is arranged inside the coil spring 30a (see Fig. 3) and has the longitudinal direction (the stroke direction) thereof arranged substantially parallel to the vehicle width direction. The lateral displacement is inputted to this cushion unit 30 after the vertical locking displacement of the swing arm 25 is converted into lateral displacement by way of the link mechanism (the operational direction converting mechanism) 31.

Accordingly, the swing-arm-type suspension device 32 of the motorcycle 1 is mainly constituted of the swing arm 25, the cushion unit 30 and the link mechanism 31. [0025]
In the inside of the transmission case 18, a continuously variable transmission 20 which is mainly constituted of a drive pulley 21 which is arranged coaxially with the crankshaft, a driven pulley 22 which is arranged coaxially with a power transmission shaft arranged behind the crankshaft, and an endless drive belt 23 which is extended between and wound around both pulleys is housed. A rotational power of the crankshaft has a speed thereof continuously changed by way of the continuously variable transmission 20 and, at the same time, is outputted to the left side drive sprocket wheel 34 which is mounted on a rear end portion of the transmission case 18 by way of a centrifugal clutch (not shown in the drawing) and a final reduction gear mechanism 76(see Fig. 3). [0026]
An endless drive chain (a power transmission belt) 36 is extended between and wound around the drive sprocket wheel 34 and a driven sprocket wheel 35 arranged on a left side of a rear wheel 9, and power transmission can be conducted between the engine 15 and the rear wheel 9 by way of the drive chain 36. Here, the drive sprocket wheel 34 is arranged coaxially with the pivot shaft 26 of the swing arm 25.

[0027]
A radiator 39 is arranged in front of the cylinder head 17a, an air cleaner case 40 is arranged above the radiator 39, and an intake pipe 42 which extends obliquely in the downward ^ and rearward direction from a throttle body 41 which is connected to a rear portion of the air cleaner case 4 0 is connected to an intake port formed in an upper portion of the cylinder head 17a, Further, an exhaust pipe 43 is connected to an exhaust port formed in a lower portion of the cylinder head 17a, while the exhaust pipe 43 is curved below the cylinder head 17a, passes below the crankcase 16 in the rearward direction and, thereafter, is raised obliquely in the upward and rearward direction behind the engine 15, and is connected to a silencer 44 which is arranged on a right side of a rear portion of the vehicle body. [0028]
The vehicle body frame 6 and the engine 15 are covered with a synthetic resin-made vehicle body cover 46. The vehicle body cover 4 6 includes a front cowl 4 7 which covers a range which extends from a front portion of the head pipe 7 to both sides of the head pipe 7, an inner cover 4 8 which covers a rear portion of the head pipe 7, and an under cowl 49 which is contiguously formed with a lower portion of the front cowl 47 and covers both sides of a lower portion of the engine 15, a floor cover 50 which is contiguously formed with a lower portion

of the inner cover 48 and covers an upper portion of the engine 15, and a rear side cover 51 which is formed on both sides of a lower portion of a seat 53 and covers both sides of the rear portion of the vehicle body. [0029]
On the seat frame 13 and the rear side cover 51, a seat 53 which is integrally formed of a front seat portion for a rider and a rear seat portion for a rear pillion passenger is supported. The seat 53 is vertically rotatable about a hinge shaft 54 which is mounted on a front end portion thereof and hence, the rider can open or close an article accommodating box 55 which is arranged below the front seat portion and, at the same time, can get access to a fuel tank 56 which is arranged below the rear seat portion. The article accommodating box 55 has a front portion thereof positioned above a rear portion of the crankcase 16 and a rear portion thereof positioned above a front portion of the swing arm 25. Further, the article accommodating box 55 has a rear side of the bottom portion thereof inclined in the rearward and upward direction so as to ensure a gap which is used at the time of rocking the swing arm 25. [0030]
The down frame 11 of the vehicle body frame 6 is mainly constituted of an upper down pipe 58 which is bifurcated to left and right sides from an upper portion of the head pipe

7 and extends obliquely in the downward and rearward direction, and a lower down pipe 59 which is bifurcated to a left and right sides from a lower portion of the head pipe 7 and extends obliquely in the downward and rearward direction more steeply than the upper down pipe 58. [0031]
Between the lower portion of the head pipe 7 and the upper middle portion of the upper down pipe 58, a gusset pipe 60 which is arranged substantially horizontally is extended, wherein an upper end portion of the lower down pipe 59 is joined to a lower portion of the head pipe 7 by way of the gusset pipe 60. Here, in the drawing, numeral 61 indicates a gusset plate which strides over an upper portion of the lower down pipe 59, a front portion of the gusset pipe 60 and a lower portion of the head pipe 7. [0032]
On a lower portion of the lower down pipe 59, a front engine hanger bracket 62 which extends obliquely in the downward and rearward direction in the same manner is contiguously formed, a front lower engine hanger 63 is fastened to a lower end portion of the engine hanger bracket 62, and a rear end portion of the front lower engine hanger 63 is fastened to a lower side of a front portion of the crankcase 16 of the engine 15 thus supporting the engine 15. [0033]

The main frame 12 is mainly constituted of a pair of left and right main pipes 65 which correspond to left and right upper down pipes 58 and lower down pipes 59. The main pipes 65 are arranged substantially horizontally at a center portion of the vehicle body and have middle portions thereof slightly curved to project upwardly as viewed in a side view of the vehicle. Front end portions of the main pipes 65 are joined to lower portions of the lower down pipes 59 from behind and, at the same time, lower end portions of the upper down pipes 58 are joined to front portions of the main pipes 65 from above. [0034]
The main pipes 65 (main frames 12) extend from a position above the cylinder head 17a of the engine 15 to a position above the swing arm pivotally supporting portion 18a formed on a rear end portion of the transmission case 18, while rear engine hanger brackets 66 which extend rearwardly are mounted on rear end portions of the main pipes 65 contiguously. Further, on lower portions of the engine hanger brackets 66, rear upper engine hangers 67 which project downwardly are mounted, and lower end portions of the rear upper engine hangers 67 are connected to an upper side of a rear portion of the transmission case 18 thus supporting the transmission case 18. [0035]
Further, the front upper engine hangers 68 are fastened to the front portions of the main pipes 65 which constitute

a joining portion with the upper down pipes 58, and lower end portions of the front upper engine hangers 68 are fastened to an upper side of a front portion of the crankcase 16 of the engine 15 thus supporting the engine 15. The engine 15 is suspended from the vehicle body frame 6 using the front upper engine hanger 68 and the respective engine hangers 63, 67. [0036]
The seat frame 13 is mainly constituted of left and right seat pipes 70 which extend obliquely in the upward and rearward direction from the vicinity of the curved portions of the left and right main pipes 65, and left and right rear pipes 71 which extend obliquely in the upward and rearward direction from rear end portions of the left and right main pipes 65. The seat pipes 7 0 have middle portions thereof bent such that the middle portions project obliquely in the front and upward direction as viewed in a side view of the vehicle and have rear end portions thereof connected to each other and hence, the seat pipes 70 are integrally formed in the lateral direction. Rear portions of the seat pipes 70 and rear portions of the rear pipes 71 are joined by way of rear side plates 72. Further, to bent portions of the seat pipes 70, upper end portions of rear gusset pipes 73 which extend obliquely in the upward and rearward direction with a steep inclination from rear end portions of the main pipes 65 are joined from below. [0037]

As shown in Fig. 2, in the swing-arm-type suspension device 32, a front end portion of the swing arm 25 which pivotally supports the rear wheel 9 is vertically mounted in a rocking manner on the transmission case 18 of the engine 15 which constitutes the vehicle body side, and one side of the cushion unit 30 which attenuates the rocking of the swing arm 25 is mounted on the swing arm 25 and another side of the cushion unit 30 is mounted on a lower side of a rear end portion of the engine 15 (below the pivot shaft 26) by way of the link mechanism 31. [0038]
To explain this embodiment also in conjunction with Fig. 3, in a vehicle-width-direction center portion in the inside of the rear end portion of the transmission case 18, a final reduction gear mechanism 76 which is constituted of a pair of reduction gears which performs the speed reduction of an output of the continuous variable transmission 20 is housed. On a left side of the rear end portion of the transmission case 18, a cylindrical left pivot shaft 26L which rotatably and pivotally supports a distal end portion of the left arm member 27 of the swing arm 25 is mounted in a projecting manner, while on a right side of the rear end portion of the transmission case 18, a cylindrical right pivot shaft 26R which pivotally and rotatably supports a distal end portion of the right arm member 28 of the swing arm 25 is fixedly mounted.

[0039]
In the inside of the left pivot shaft 2 6L, an output shaft
(an engine output shaft) 77 of the final reduction gear mechanism 76 is rotatably and pivotally supported. Here, on a vehicle-width-direction inner side of the output shaft 77
(a projecting portion in the inside of the transmission case 18) , a final gear 7 8 which constitutes a final power transmission member of the final reduction gear mechanism 76 is mounted. On the other hand, on a vehicle-width-direction outer side of the output shaft 77 (a projecting portion to the outside of the transmission case 18), the drive sprocket 34 is mounted. The end portion on the vehicle-width-direction outer side of the output shaft 77 (eventually the left pivot shaft 26L) is supported on a rear-end-portion left side of the transmission case 18 by way of the holder 37.
[0040]
Between a rear end portion of the left arm member 27 and a hub portion of the rear wheel 9 of the vehicle-width-direction inner side, a driven sprocket wheel 35 is arranged. The above-mentioned drive chain 3 6 is extended between and wound around the driven sprocket wheel 35 and the drive sprocket wheel 34 mounted on the vehicle-width-direction outer side of the front end portion of the left arm member 27. Accordingly, when the swing arm is viewed in a plan view, the left arm member 27 is displaced to the vehicle-width-direction outer side to

avoid the drive chain 36 behind a left pivot inserting portion 27a which constitutes a distal end portion of the left arm member 27 and, thereafter, extends toward the vehicle-width-direction outer side of the driven sprocket wheel 35 and pivotally supports the left side of the rear wheel 9. On the other hand, the right arm member 28 extends rearwardly substantially linearly from the right pivot inserting portion 28a which constitutes the distal end portion to pivotally support the rear wheel 9. [0041]
Further, when the swing arm 25 is viewed in a side view (as viewed in a side view of the vehicle) , the left arm member 27 extends substantially linearly to an axle position of the rear wheel 9 from the left pivot inserting portion 27a. Due to such a constitution, it is possible to ensure the rigidity against a compressive weight inputted to the left arm member 27 by way of the drive chain 36. On the other hand, the right arm member 28 is formed into a so-called gull shape which is curved in an L-shape as viewed in a side view to project a portion of the right arm member 28 which is positioned between a rear end portion of the transmission case 18 and a front end portion of the rear wheel 9 (a front side than a longitudinal center portion of the right arm member 28 per se) upwardly. [0042]
To explain this embodiment also in conjunction with Fig.

4, on the vehicle-width-direction inner side of a curved portion 28b of the right arm member 28 which is positioned between the transmission case 18 and the rear wheel 9, a cross member 29 which integrally connects the left and right arm members 27, 28 is arranged. The cross member 29 has a right end portion thereof joined to the vehicle-width-direction inner side of the curved portion 28b, extends to the vicinity of the left arm member 27 while maintaining a shape which allows the cross member 29 to be substantially overlapped to the curved portion 28b in a side view of the swing arm and, thereafter, is gradually changed downwardly, and has a left end portion thereof joined to the front vehicle-width-direction inner side of the left arm member 27. Such a cross member 29 is formed of a hollow structural body made of aluminum alloy, for example, in the same manner as the left and right arm members 27, 28. The cross member 29 has, to attenuate the stress concentration at joining portions thereof with the left and right arm members 27, 28, particularly a rear side thereof curved and extended rearwardly to form a spreading fan shape in a plan view of the swing arm. [0043]
The cushion unit 30 is arranged such that the cushion unit 30 extends laterally between the transmission case 18 and the rear wheel 9 and right below the cross member 29 of the swing arm 25 . The cushion unit 30 has a left end portion thereof

mounted on the vehicle-width-direction inner side of the left arm member 27 of the swing arm 25 in an abutting manner and has a right end portion thereof mounted on a lower side of a rear end portion of the transmission case 18 by way of the link mechanism 31. In such a state, a total length of the cushion unit 30 substantially falls within a lateral width of the swing arm 25. [0044]
By converting the vertical movement of the rear wheel 9, that is, the vertical rocking displacement of the swing arm 25 into the lateral displacement and by inputting the lateral displacement to the right end portion of the cushion unit 30 by way of the link mechanism 31, the cushion unit 30 performs a stroke so that an impact or vibrations attributed to the vertical movement of the rear wheel 9 is converted into the elongation and contraction of the coil spring 30a and, at the same time, the impact or vibrations are attenuated and are gradually absorbed by the elongation and contraction of the damper 30b. [0045]
The link mechanism 31 includes a bell crank 80 which is supported on the swing arm 25 in a rocking manner, and a link member 90 which is extended between the bell crank 80 and the transmission case 18.
The bell crank 80 is pivotally supported on a bell crank

support shaft 28c which is formed on the right arm member 28 located at an oblique downward and rearward position from the right pivot inserting portion 28a. The bell crank 80 can be rocked about a rocking shaft 81 which is inclined frontwardly in a state that the rocking shaft 81 is inclined more frontwardly corresponding to a distance in the upward direction. [0046]
The bell crank 80 includes a first arm portion 83 which extends toward the vehicle-width-direction inner side obliquely and rearwardly from the shaft inserting portion 82 in which the rocking shaft 81 is inserted, and a second arm portion 84 which extends toward the vehicle-width-direction outer side obliquely and rearwardly from the shaft inserting portion 82. The respective arm portions 83, 84 are arranged to make a right angle therebetween as viewed in a plan view along the rocking shaft 81, and a length of the second arm portion 84 is set larger than the first arm portion 83. [0047]
To a first connecting portion 85 which constitutes a distal end of the first arm portion 83, a rear end portion of the link member 90 which is inclined frontwardly and downwardly is connected by way of a first connecting shaft 87 which is arranged parallel to the rocking shaft 81 in a rocking manner. On the other hand, to a second connecting portion 8 6 which

constitutes a distal end portion of the second arm portion 84, a right end portion of the cushion unit 30 is connected in a rocking manner by way of a second connecting shaft 88 which is arranged parallel to the rocking shaft 81. [0048]
Here, the second arm portion 84 and the right end portion of the cushion unit 30 are arranged on an inner peripheral side (a lower side) of the curved portion 28b of the right arm member 28. In other words, the right arm member 28 is formed in a gull shape to avoid the cushion unit 30 and the bell crank 80. In such a state, the cushion unit 30 falls within a vertical width of the left arm member 27 as viewed in a side view of the vehicle and, at the same time, the bell crank 80 also falls within a vertical width of the left arm member 27 as viewed in a side view of the vehicle. [0049]
A front end portion of the link member 90 is connected in a rocking manner to an arm connecting portion 90a which is formed on a lower side of a rear end portion (lower than the pivot shaft 26) of the transmission case 18 by way of an arm connecting shaft 90b which is arranged parallel to the vehicle width direction.
When the swing arm 25 is vertically rocked along with the vertical movement of the rear wheel 9, due to an input from the link member 90 which is connected to the vehicle body side,

the bell crank 80 is rocked about the rocking shaft 81 thus imparting a stroke to the cushion unit 30. Here, front and rear end portions of the link member 90 are configured to be rocked also in the direction orthogonal to the first connecting portion 85 and the arm connecting shaft 90b. [0050]
The link member 90 which receives a reaction (a cushion weight) at the time of imparting a stroke to the cushion unit 30 is connected to the vehicle body side at a position below the pivot shaft 26. Accordingly, a frame member or the like which receives the cushion load is unnecessary above the pivot shaft 26. [0051]
Further, by arranging the cushion unit 30 below the cross member 29 of the swing arm 25 in a state that the longitudinal direction of the cushion unit 30 is arranged along the vehicle-width direction, compared to a case in which the longitudinal direction of the cushion unit 30 is arranged in the vertical direction or in the longitudinal direction of the vehicle, it is possible to restrict a longitudinal length and a vertical thickness of the swing-arm-type suspension device around the cushion unit 30. [0052]
Due to such a constitution, it is possible to easily ensure a rocking space of the swing-arm-type suspension device

32 and hence, it is possible to enhance the degree of freedom in the layout of peripheral parts of the swing-arm-type suspension device 32. Particularly, in a vehicle which has the large article accommodating box 55 below the seat 53 as in the case of the motorcycle 1, a volume of the article accommodating box 55 can be enlarged and hence, this constitution is preferably adopted. [0053]
As has been explained above, the swing-arm-type suspension device 32 of the above-mentioned embodiment is configured such that the swing arm 25 which pivotally supports the rear wheel 9 thereon is pivotally supported on the vehicle body (the transmission case 18) of the motorcycle 1 in a vertically rocking manner, and the cushion unit 30 which attenuates the rocking of the swing arm 25 is mounted between the vehicle body and the swing arm 25, wherein the cushion unit 30 is arranged in a laterally extending manner, and the link mechanism 31 which converts a rocking displacement of the swing arm 25 into a stroke of the cushion unit 30 is provided between the cushion unit 30 and the swing arm 25. [0054]
According to such a constitution, by extending the cushion unit 30 laterally and by imparting a stroke to the cushion unit 30 by way of the link mechanism 31 along with the vertical rocking of the swing arm 25, it is possible to restrict

a vertical thickness and a longitudinal length of the device per se compared to a case in which the cushion unit 30 is extended vertically or longitudinally and hence, it is possible to enhance the degree of freedom in the layout of the peripheral parts. Particularly, this embodiment is preferably applicable to the motorcycle 1 which includes the large article accommodating space below the seat 53. [0055]
Further, in the above-mentioned swing-arm-type suspension device 32, by arranging the cushion unit 30 orthogonal to the longitudinal direction of the vehicle, it is possible to further restrict the longitudinal length of the device per se. [0056]
Further, in the above-mentioned swing-arm-type suspension device 32, by arranging the cushion unit 30 within the lateral width of the swing arm 25, it is possible to restrict the lateral width of the device per se. [0057]
Still further, in the above-mentioned swing-arm-type suspension device 32, by constituting the link mechanism 31 by connecting the link member 90 and the bell crank 80, it is possible to simplify the link mechanism 31 and hence, it is possible to realize the enhancement of the reliability and the reduction of a manufacturing cost.

[0058]
Further, in the above-mentioned swing-arm-type suspension device 32, the swing arm 25 is constituted by connecting the left and right arm members 27, 28 using the cross member 29, and the cushion unit 30 is arranged below the cross member 29 and hence, the cushion unit 30 is arranged at a portion of the swing arm 25 in the vicinity of the cross member 29 which exhibits the high rigidity whereby it is possible to increase the mounting rigidity of the cushion unit 30. [0059]
Here, in the above-mentioned swing-arm-type suspension device 32, the left arm member 27 is formed linearly as viewed in a side view of the vehicle, and the drive chain 36 which extends between the vehicle-body-side engine 15 and the rear wheel 9 is arranged around the left arm member 27. On the other hand, the right arm member 28 is formed in the curved gull shape as viewed in a side view of the vehicle, a left end portion of the cushion unit 30 is mounted on the left arm member 27, and a right end portion of the cushion unit 30 is mounted on the link mechanism 31 on the inner peripheral side of the curved portion 28b of the right arm member 28. [0060]
Due to such a constitution, the cushion unit 30 is arranged in a state that the cushion unit 30 extends from the left arm member 27 which is formed linearly as viewed in a side

view of the vehicle to the right arm member 28 which is formed in a gull shape, and the cushion unit 30 and the link mechanism 31 are connected with each other on the inner peripheral side of the curved portion 28b of the right arm member 28 and hence, it is possible to efficiently arrange the cushion unit 30 by making use of a space around the swing arm 25 whereby the device per se can be formed into a compact unit. [0061]
Further, in the above-mentioned swing-arm-type suspension device 32, by setting the vertical widths of the cushion unit 30 and the bell crank 80 to values which fall within the vertical width of the left arm member 27 of the swing arm 25 as viewed in a side view of the vehicle, the vertical thickness of the device per se can be further restricted thus increasing the degree of freedom in the layout of the peripheral parts.
[Embodiment 2] [0062]
Next, a second embodiment of the present invention is explained.
The second embodiment differs from the first embodiment mainly with respect to a point that both of left and right arm members of the swing arm are formed linearly as viewed in a side view of the vehicle, and the cushion unit which extends in the vehicle-width direction is arranged in the inside of

the cross member which connects the left and the right arm members and hence, parts identical with the parts of the first embodiment are given same symbols and their explanation is omitted. [0063]
As shown in Fig. 5, in a swing-arm-type suspension device 132, a front end portion of a swing arm 125 which pivotally supports a rear wheel 9 is mounted in a vertically rocking manner on a transmission case 18 of an engine 15 which constitutes a vehicle body side, and one side of the cushion unit 30 which attenuates the rocking of the swing arm 125 is mounted on the swing arm 125 and another side of the cushion unit 30 is mounted on a lower side of a rear end portion of the engine 15 by way of the link mechanism 31. [0064]
To explain also in conjunction with Fig. 6, the swing arm 125 has front inner sides of left and right arm members 127,128 thereof connected to each other using a cross member 129. A distal end portion (a left pivot inserting portion 127a) of the left arm member 127 is rotatably and pivotally supported on a left pivot shaft 26L on a left side of a rear end portion of the transmission case 18, while a distal end portion (a right pivot inserting portion 128a) of the right arm member 128 is rotatably and pivotally supported on a right pivot shaft 2 6R on a right side of the rear end portion of the transmission

case 18. These left and right arm members 127, 128 extend rearwardly substantially linearly to an axle position of the rear wheel 9 from the left and right pivot inserting portions 127a, 128a and pivotally support the rear wheel 9 as viewed in a plan view and a side view of the swing arm. [0065]
Between the transmission case 18 and the rear wheel 9, a cross member 129 which integrally connects the left and right arm members 127, 128 to each other is arranged. The cross member 129 is configured to extend between the left and right arm members 127, 128 as viewed in a side view of the swing arm while maintaining a shape which allows the cross member 129 to be substantially overlapped to the left and right pivot inserting portions 127a, 128a in a side view of the swing arm, and such a cross member 129 is formed of a hollow structural body made of aluminum alloy, for example, in the same manner as the left and right arm members 127, 128. Both end portions of the cross member 129 are extended rearwardly by curving particularly rear sides of such both end portions to form a spreading fan shape in a plan view of the swing arm. [0066]
To explain also in conjunction with Fig. 7, the cushion unit 30 is arranged such that the cushion unit 30 extends in the lateral direction in the inside of the cross member 129, wherein a left end portion of the cushion unit 30 is mounted

on the left arm member 127 in a state that the left end portion is inserted into the inside of the left arm member 127 and, at the same time, a right end portion of the cushion unit 30 is connected to a lower side of a rear end portion of the transmission case 18 by way of the link mechanism 31. In such a state, the cushion unit 30 and the link mechanism 31 are arranged on a slightly left side compared to the first embodiment and a total length of the cushion unit 30 falls within a lateral width of the swing arm 125. [0067]
At an oblique, downward and rearward position of the right pivot inserting portion 12 8a and on a slightly vehicle-width-direction inner side of the right armmember 128, a bell-crank support portion 128c which pivotally supports a bell crank 80 of the link mechanism 31 by way of a rocking shaft 81 which is inclined such that an upper side is positioned more frontwardly is formed. In the bell-crank support portion 128c and a vehicle-width-direction outer side of the right arm member 128, an opening 128d for mounting and dismounting the cushion unit 30 and the link mechanism 31 is formed. [0068]
When the swing arm 125 is vertically rocked along with the vertical movement of the rear wheel 9, due to an input imparted from the link member 90 which is connected to the vehicle body side, the bell crank 80 is rocked about the rocking

shaft 81 thus imparting a stroke to the cushion unit 30 and hence, impacts and vibrations which are generated due to the vertical movement of the rear wheel 9 can be attenuated and gradually absorbed. [0069]
As has been explained above, in the swing-arm-type suspension device 132 of the above-mentioned second embodiment, by arranging the cushion unit 30 which extends laterally in the inside of the cross member 129 of the swing arm 125, it is possible to restrict the longitudinal length about the cushion unit 30 of the device per se as well as the vertical thickness of the device per se . Further, by effectively making use of the inner space of the cross member 129 of the swing arm 125, it is possible to efficiently arrange the cushion unit 30. Accordingly, it is possible to more surely acquire a rocking space for the device per se and hence, the degree of freedom in the layout of the peripheral parts can be further enhanced, and device per se can be formed into a compact unit. [0070]
Here, the present invention is not limited to the above-mentioned embodiments. For example, in the first embodiment, the cushion unit 30 which extends laterally is configured to be arranged above the cross member 29 of the swing arm 25 in place of being arranged below the cross member 29 of the swing arm 25. Here, the right arm member 28 of the swing

arm 25 may be curved such that the right arm member 28 projects downwardly and the cushion unit 30 is arranged on an inner peripheral side (an upper side) of the curved portion. In this case, it is possible to obtain an advantageous effect that the cushion unit 30 is protected by the cross member 29.
Further, the cushion unit 30 which extends laterally may be configured such that the cushion unit 30 is arranged above or below the transmission case 18 and has one side thereof mounted on the transmission case 18 and another side thereof mounted on the swing arm 25 by way of the link mechanism 31.
Further, the swing arms 25, 125 may be configured such that the swing arms 25, 125 are pivotally supported on the vehicle body frame 6 in place of the engine 15 or are pivotally supported on both of the engine 15 and the vehicle body frame 6.
Further, the constitutions of the above-mentioned embodiments merely constitute one example of the present invention and it is needless to say that the engine type and the detailed constitution of the vehicle body frame are not limited to the above-mentioned embodiments and various modifications are conceivable without departing from the gist of the present invention. [Brief Description of the Drawings] [0071] [Fig. 1]

A side view of a motorcycle of a first embodiment of the present invention. [Fig. 2]
A side view of a swing-arm-type suspension device of the above-mentioned motorcycle. [Fig. 3]
A planar explanatory view of the above-mentioned swing-arm-type suspension device. [Fig. 4]
A perspective view of a front portion of the above-mentioned swing-arm-type suspension device as viewed from an oblique downward direction. [Fig. 5]
A side view of a swing-arm-type suspension device of a second embodiment of the present invention. [Fig. 6]
A planar explanatory views of the swing-arm-type suspension device in Fig. 5. [Fig. 7]
A perspective view of a front portion of the swing-arm-type suspension device as viewed from an oblique downward direction in Fig. 5. [Description of Reference Numerals and Signs] [0072] 1: motorcycle

9: rear wheel (wheel)
18: transmission case (vehicle body)
25, 125: swing arm
27, 127: left arm member
28, 128: right arm member
28b: curved portion
29, 129: cross member
30: cushion unit
31: link mechanism (operational direction converting
mechanism)
32, 132: swing-arm-type suspension device
36: driving chain (power transmission belt)
80: bell crank
90: link member

[Designation of Document] Claims [Claim 1]
A swing-arm-type suspension device in which a swing arm which pivotally supports a wheel thereon is pivotally supported on a vehicle body of a motorcycle in a vertically rocking manner, and a cushion unit which attenuates the rocking of the swing arm is mounted between the vehicle body and the swing arm, wherein
the cushion unit is arranged in a laterally extending manner, and an operational direction converting mechanism which converts a rocking displacement of the swing arm into a stroke of the cushion unit is provided between the cushion unit and the swing arm. [Claim 2]
A swing-arm-type suspension device according to claim 1, wherein the cushion unit is arranged orthogonal to the vehicle longitudinal direction. [Claim 3]
A swing-arm-type suspension device according to claim 1 or claim 2, wherein the cushion unit is arranged within a lateral width of the swing arm. [Claim 4]
A swing-arm-type suspension device according to any one of claim 1 to claim 3, wherein the operational direction converting mechanism is constituted by connecting a link member

and a bell crank. [Claim 5]
A swing-arm-type suspension device according to any one of claim 1 to claim 4, wherein the swing arm is constituted by connecting left and right arm members using a cross member, and the cushion unit is arranged above or below the cross member. [Claim 6]
A swing-arm-type suspension device according to any one of claim 1 to claim 5, wherein one of the left and right arm members is provided linearly as viewed in a side view of a vehicle, a power transmission belt which extends between an engine on the vehicle body side and the wheel is arranged around one arm member, another one of the left and right arm members is formed in a gull shape which curves as viewed in a side view of a vehicle, and the cushion unit has one end portion thereof mounted on one arm member and another end portion thereof mounted on the operational direction converting mechanism at an inner peripheral side of a curved portion of another arm member. [Claim 7]
A swing-arm-type suspension device according to any one of claim 1 to claim 4, wherein the swing arm is constituted by connecting the left and right arm members using a cross member, and the cushion unit is arranged in the inside of the

cross member. [Claim 8]
A swing-arm-type suspension device according to any one of claim 4 to claim 7, wherein a vertical width of the cushion unit is set to a value which falls within a vertical width of the swing arm as viewed in a side view of a vehicle.

Documents:

1317-CHE-2006 CORRESPONDENCE OTHERS.pdf

1317-CHE-2006 CORRESPONDENCE PO.pdf

1317-CHE-2006 PCT.pdf

1317-CHE-2006 POWER OF ATTORNEY.pdf

1317-che-2006 abstract-duplicate.pdf

1317-che-2006 claims-duplicate.pdf

1317-che-2006 description (complete)-duplicate.pdf

1317-che-2006 drawings-duplicate.pdf

1317-che-2006-abstract.pdf

1317-che-2006-claims.pdf

1317-che-2006-correspondnece-others.pdf

1317-che-2006-description(complete).pdf

1317-che-2006-drawings.pdf

1317-che-2006-form 1.pdf

1317-che-2006-form 18.pdf

1317-che-2006-form 26.pdf

1317-che-2006-form 3.pdf

1317-che-2006-form 5.pdf

1317-che-2006-priority document.pdf

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Patent Number

230639

Indian Patent Application Number

1317/CHE/2006

PG Journal Number

13/2009

Publication Date

27-Mar-2009

Grant Date

27-Feb-2009

Date of Filing

27-Jul-2006

Name of Patentee

HONDA MOTOR CO., LTD.

Applicant Address

1-1, MINAMIAOYAMA 2-CH0ME, MINATO-KU, TOKYO,

Inventors:

#	Inventor's Name	Inventor's Address
1	IIZUKA, CHIKASHI	C/O HONDA R&D CO., LTD., 4-1, CHUO 1-CHOME, WAKO-SHI, SAITAMA 351-0193,
2	MAEDA, TADAYUKI	C/O HONDA R&D CO., LTD., 4-1, CHUO 1-CHOME, WAKO-SHI, SAITAMA 351-0193,

PCT International Classification Number

B62K25/04

PCT International Application Number

N/A

PCT International Filing date

PCT Conventions:

#	PCT Application Number	Date of Convention	Priority Country
1	2005-220899	2005-07-29	Japan