motorcycle

Abstract

Motorcycle (10), containing: a crankcase (36) which supports a crankshaft (35) of an engine (23), a drive force transmission device (24) located at an intermediate position between the crankshaft (35) and a drive wheel to transmit a torque from the crankshaft (35) to the drive wheel, and a swing arm (27) which mounts the drive wheel so that it can oscillate, wherein the drive force transmission device (24) comprises a continuously variable transmission (48) which is provided with a flexible endless element extending between a drive pulley (53) and a driven pulley (54), and a transmission housing (49) for the continuously variable transmission (48) which covers the continuously variable transmission (48), and in which a central rotation shaft of the driven pulley (54) is arranged behind and above the central rotation shaft of the drive pulley (53), viewed in a side view of the motorcycle (10), wherein the swing arm (27) includes a pivot section provided at one end of the swing arm so that it can be pivotably attached to a motorcycle body frame (15) or to the crankcase (36), and has a drive wheel bearing part at another end of the swing arm (27) to rotatably mount the drive wheel, characterized in that the pivot section is arranged below a bottom surface of the gearbox housing (49) for the continuously variable transmission (48) when viewed in a side view of the motorcycle (10), such that at least a part of the swingarm (27) overlaps vertically with a part of the gearbox housing (49) for the continuously variable transmission (48), wherein the drive force transmission device (24) further comprises a clutch (50) with a clutch body which transmits or interrupts a torque from the crankshaft (35) or a gearbox (48), and a clutch housing (51) covering the clutch (50), wherein the clutch (50) includes a lower end of the clutch body which is positioned above a lubricant oil level in the crankcase (36) when viewed from the side of the motorcycle (10), wherein the pivot section is located below a bottom surface of the clutch housing (51) in the side view of the motorcycle (10) in order to bring at least a part of the swingarm (27) vertically overlapping with the clutch housing (51), and wherein the clutch (50) is arranged on either the right or the left side with respect to a center line of the motorcycle (10) in the motorcycle's width direction, and the swing arm (27) includes at least a part of the pivot section on one side inside an outer end of the clutch housing (51) in the motorcycle's width direction in a ground view of the motorcycle (10).

Description

Background of the inventionField of the invention

[0001] The present invention relates to a motorcycle, in particular to a motorcycle in which the arrangement of a continuously variable transmission in a drive power transmission line is improved. Description of the state of the art

[0002] JP 2002-19 682 A discloses a power transmission device for a scooter. This power transmission device transmits torque from a crankshaft of a chain transmission mechanism in a swing arm via a continuously variable transmission mechanism including a V-belt and a clutch mechanism for driving a rear wheel rotatably supported by the swing arm.

[0003] However, in the power transmission device described in JP 2002-19 682 A, the crankshaft, a central rotational axis of a drive pulley (coaxial with the crankshaft) and a central rotational shaft of the driven pulley (main shaft) of the continuously variable transmission mechanism, and a pivot point (drive shaft) of the swing arm are arranged substantially linearly in the longitudinal direction of the vehicle.

[0004] Therefore, if the drive pulley and driven pulley of a continuously variable transmission mechanism are manufactured with larger diameters to increase the power of a vehicle, the overall dimension from the crankshaft to the pivot point of the swing arm must be increased. As a result, the vehicle's maneuverability and the like deteriorate.

[0005] Furthermore, in a power transmission device of a motorcycle configured as a conventional scooter, as described in JP 2002-19682 A, a portion of the clutch mechanism is located below a lubricant oil level in an engine crankcase and immersed in the lubricant. With such an arrangement, if a portion of the clutch mechanism is immersed in the lubricant, the responsiveness of the clutch mechanism during engagement and disengagement is impaired, which may lead to deterioration of the vehicle's operability.

[0006] To avoid such a disadvantage, a lubricant discharge device (e.g., in the form of a scavenging pump) is provided to discharge the lubricant from a clutch mechanism so that it is not easily saturated with lubricant. However, such an additional lubricant discharge device not only complicates the vehicle structure but also causes power loss due to the drive of the lubricant discharge device, thereby affecting the vehicle's output.

[0007] Furthermore, US 2008 / 0 121 454 A1 discloses a generic motorcycle. Disclosure of the invention

[0008] The present invention has been made in view of the circumstances encountered in the above-mentioned prior art, and an object of the invention is to provide a motorcycle in which operability, comfort and driving performance are improved by improving the arrangement or layout of a continuously variable transmission in a driving force transmitting device.

[0009] Another object of the present invention is to provide a motorcycle in which the output power and the vehicle maneuverability are improved while a structure of the vehicle is simplified due to an improvement in the arrangement of a clutch in a driving force transmission device.

[0010] According to the invention, a motorcycle having the features of claim 1 is provided.

[0011] The above-mentioned objects and other objects can be achieved according to the invention by providing, in one aspect, a motorcycle comprising a crankcase supporting a crankshaft of an engine, a drive force transmission device located at an intermediate position between the crankshaft and a drive wheel for transmitting torque from the crankshaft to the drive wheel, and a swing arm swingably supporting the drive wheel, wherein the drive force transmission device comprises a continuously variable transmission provided with a flexible endless element extending between a drive pulley and a driven pulley, and a transmission case for the continuously variable transmission covering the continuously variable transmission,and in which a rotating center shaft of the driven pulley is arranged behind and above the rotating center shaft of the drive pulley, as viewed in a side view of a vehicle configured as a motorcycle, and wherein the swing arm includes a pivot portion provided at one end of the swing arm for pivotally mounting the swing arm on a vehicle body frame or the crankcase, and a drive gear support portion at another end of the swing arm for rotatably supporting the drive gear, the pivot portion being arranged below a bottom surface of the transmission case for the continuously variable transmission as viewed in a side view of the vehicle, so that at least a part of the swing arm vertically overlaps a part of the transmission case for the continuously variable transmission.

[0012] According to this aspect, the present invention includes the following preferred embodiment:

[0013] It may be desirable that the continuously variable transmission is disposed on either the right or left side with respect to a center line of the motorcycle in a vehicle width direction, and the swing arm includes at least a part of the pivot portion on one side disposed inside an outer end of the transmission case for the continuously variable transmission in the vehicle width direction when viewed in a bottom view of the vehicle.

[0014] Furthermore, it may be desirable for the swing arm to include an outer end of the pivot portion on one side disposed inside the outer end of the transmission housing of the continuously variable transmission in the vehicle width view, viewed in the bottom view of the vehicle.

[0015] The invention also provides, in another aspect, a motorcycle including: a crankcase supporting a crankshaft of an engine, a drive force transmission device located at an intermediate position between the crankshaft and a drive wheel for transmitting torque from the crankshaft to the drive wheel, and a swing arm swingably supporting the drive wheel, wherein the drive force transmission device includes a clutch having a clutch body that transmits or interrupts torque from the crankshaft or a transmission, and a clutch case covering the clutch, wherein the clutch includes a lower end of the clutch body positioned above a lubricating oil level in the crankcase when the vehicle is configured as a motorcycle.

[0016] According to this aspect, the present invention includes the following preferred embodiment: It may be desirable for the swing arm to include a pivot portion located at one end side of the swing arm for pivotally mounting the swing arm on the vehicle body frame or the crankcase, and a drive wheel support portion provided at the other end side of the swing arm for rotatably supporting the drive wheel, the pivot portion being located below a bottom side of the clutch housing in the side view of the vehicle to vertically overlap at least a portion of the swing arm with the clutch housing.

[0017] Furthermore, it may be desirable for the clutch to be arranged on either the right or left side with respect to a center line of the motorcycle in the vehicle width direction, and the swing arm to include at least a part of the pivot portion on one side inside an outer end of the clutch housing in the vehicle width direction in a bottom view of the vehicle.

[0018] In addition, it may be desirable for the swing arm to include an outer end of the pivot portion on one side inside the outer end of the clutch housing in the vehicle width direction in a bottom view of the vehicle.

[0019] According to the present invention, since the central rotating shaft of the driven pulley of the continuously variable transmission is arranged rearward and above the central rotating shaft of the drive pulley in a side view of the vehicle, and further, since the continuously variable transmission is configured to extend obliquely rearward and upward, it is possible to increase the diameters of the drive pulley and the driven pulley while preventing an increase in the length in the vehicle's longitudinal direction. Therefore, since it is possible to expand the adjustable range of a reduction ratio of the continuously variable transmission, the acceleration and top speed of the vehicle can be increased, thus improving the driving performance of the vehicle, i.e., the motorcycle.

[0020] Furthermore, as explained above, since the rotating center shaft of the driven pulley of the continuously variable transmission is arranged rearward and above the rotating center shaft of the drive pulley when viewed from the side of the vehicle, and the continuously variable transmission is configured to extend rearward and obliquely upward, it is possible to form a clearance below the driven pulley when viewed from the side of the vehicle. As a result, by arranging the swing range of the swing arm in this clearance, the swing range can be shifted in the forward direction of the vehicle and it is possible to reduce the length in the vehicle's longitudinal direction, further improving the operability of the vehicle.

[0021] Since such a design simultaneously makes it possible to provide a sufficient length for the swing arm, the vertically movable stroke range of the rear wheel of the vehicle, i.e. the motorcycle, is increased, thereby increasing the riding comfort for the driver, which overall improves the vehicle riding comfort.

[0022] Furthermore, according to the invention, since the clutch of the drive transmission device is located at an upper location within the crankcase, the clutch is less easily wetted by the lubricant contained in the crankcase. Consequently, the responsiveness during clutch engagement and disengagement can be improved, which also improves the operability of the vehicle.

[0023] Furthermore, since the clutch is less easily wetted by the lubricant in the crankcase, responsive clutch engagement and disengagement can be ensured without the need for a lubricant discharge device in the crankcase. As a result, power loss that would otherwise be incurred due to the operation of the lubricant discharge device is avoided, thus improving the vehicle's output, simplifying the vehicle structure, and thus increasing vehicle maintainability.

[0024] The nature and other characteristics of the present invention will become more apparent from the following description with reference to the accompanying drawings. Short description of the drawings Fig. 1 is a right side view of an embodiment of a motorcycle as a vehicle according to the invention; Fig. 2 is a right side view of an engine unit, a vehicle body frame and the like of the Fig. 1 motorcycle shown; Fig. 3 is a left side view showing the engine unit, the vehicle body frame and the like of the Fig. 1 illustrated motorcycle; Fig. 4 is a plan view of the Fig. 2 engine unit shown; Fig. 5 is a bottom view of the Fig. 2 shown motor unit; Fig. 6 is a side view showing a periphery of a continuously variable transmission in a driving force transmission device according to Fig. 2 illustrates; Fig. 7 is a side view of a periphery of a coupling in the Fig. 3 shown drive force transmission device; Fig. 8 is an enlarged plan view showing a part of Fig. 4 illustrates; and Fig. 9 is an enlarged bottom view of a part of Fig. 5. Description of the preferred embodiment

[0025] An embodiment for carrying out the present invention will now be described with reference to the accompanying drawings.

[0026] Fig. 1 is a right side view of an embodiment of a motorcycle according to the invention, Fig. 2 is a right side view of an engine unit, a vehicle body frame and the like of the Fig. 1 shown motorcycle, and Fig. 3 is a left side view showing the engine unit, the vehicle body frame and the like of the Fig. 1 shown motorcycle.

[0027] It should also be noted that terms such as front and rear, right and left, upper and lower (top and bottom) and the like indicating a direction are used herein with reference to the accompanying drawings or with reference to a motorcycle on which a rider is seated.

[0028] Referring to Fig. 1 to 3, the motorcycle 10 of this embodiment is a large two-seat scooter. The motorcycle 10 has a front section 11 with a foot guard 12 extending in the vehicle's lateral direction (right and left), a windshield 13, and a handlebar 14.

[0029] The steering rod 14 is integrally rotatably coupled to a steering shaft 13 which is pivotally mounted in a head tube 16 of a vehicle body frame 15 according to Fig. 1 and Fig. 2. The steering shaft 17 supports a front wheel 19 by means of a pair of left and right front forks 18. The steering shaft 17 is pivotally supported by the head tube 16 in the right and left directions, so that the front wheel 19 can be steered to the right and left by operating the steering rod 14.

[0030] As in Fig. As shown in Figure 1, the motorcycle 10 is equipped with a double seat 20 for two passengers at the rear relative to the vehicle front portion 11. In an area between the vehicle front portion 11 and the double seat 20, a pair of left and right plate-shaped footrests 21 are provided, on which the respective passengers (driver and pillion passenger) sitting on the double seat 20 can rest their feet. The plate-shaped footrests 21 extend in the vehicle longitudinal direction, and an upwardly extending center tunnel portion 22 is formed in a space between the footrests 21.

[0031] In a lower central region of the vehicle body frame 15 according to Fig. 2, a motor unit 25 is mounted, into which a motor 23 and a drive force transmission device 24 are integrated. Behind the motor unit 25, a swing arm 27 is pivotally mounted, which supports a rear wheel 26 acting as a drive wheel. The swing arm 27 contains a gear transmission (not shown) for transmitting torque from the motor unit 25 to the rear wheel 26, and it supports the rear wheel 26 in a swingable manner.

[0032] As in the Fig. 1 and Fig. As shown in FIG. 2, the vehicle body frame 15 is equipped with the head pipe 16 at its front end, and further includes a pair of left and right paired down pipes 28 and a pair of left and right down pipes 29 extending from a lower part and an upper part of the head pipe 16, respectively. The down pipes 28 on the front side are bent downward at their lower portions and are connected to a pair of left and right down beams 30.

[0033] Furthermore, a pair of left and right main tubes 31 extend rearwardly from approximately midpoints in the vertical direction of the down tubes 28 on the front side. Lower ends of the down tubes 29 on the rear side and rear ends of the down beams 30 are connected to the corresponding main tubes 31.

[0034] Seat rails 32 extend rearward and are connected to the respective rear portions of the main tubes 31.

[0035] As in Fig. 1, a receiving chamber (not shown) is formed above the rear wheel 26, wherein the double seat serves as a cover for the receiving chamber and is arranged above the receiving chamber so that it can be opened.

[0036] The vehicle body frame 15, the engine unit 25, the receiving chamber and the like are covered by a vehicle body cover 33 made of synthetic resin.

[0037] As in the Fig. 2 to 5, the engine 23 located in the engine unit 25 includes a crankcase 36, which accommodates and rotatably supports a crankshaft 35, and a cylinder assembly 37, which is located approximately horizontally in a front part of the crankcase 36. The cylinder assembly 37 includes a cylinder 38, a cylinder head 39, and a head cover 40, which are arranged one behind the other in a stacked manner starting from the crankcase 36. In the cylinder head 39, an intake pipe (not shown) and an exhaust pipe 41 (see Fig. 1) with their upper and lower sections, respectively. One leading end of the exhaust pipe 41 is connected to a muffler 42.

[0038] The crankcase 36 has a fitting surface 43 running in the longitudinal direction of the vehicle (see Fig. 4 and Fig. 5), and it is composed of a left-side crankcase 36A and a right-side crankcase 36B, which are separable in the width direction of the vehicle. The crankcase 36 accommodates the crankshaft 35, which is connected on one side (a right side in the present embodiment) to a primary drive gear 45 according to Fig. 8, and the crankcase 36 also accommodates a countershaft 46 which is rotatably mounted behind the crankshaft 35 and parallel to it.

[0039] The countershaft 46 is equipped with a driven primary gear 47 which engages with the primary drive gear 45 so that torque is transmitted from the crankshaft 35 to the countershaft 46.

[0040] As in Fig. 2 and Fig. 3, the drive force transmission device 24 located in the engine unit 25 is arranged at an intermediate position between the crankshaft 25 and the rear wheel 26, so that the torque transmitted from the crankshaft 35 to the countershaft 46 via the primary drive gear 45 and the driven primary gear 47 is transmitted to the rear wheel 26.

[0041] The drive force transmission device 24 contains, as Fig. 6 and Fig. 7, a continuously variable transmission 48, a continuously variable transmission housing 49, a clutch 50, and a clutch housing 51.

[0042] In a Fig. In the top view of the vehicle shown in Figure 8, the continuously variable transmission 48 and the clutch 50 are arranged on one side (here, the right side) and the other side (here, the left side) relative to a center line M in the vehicle width direction. The continuously variable transmission 48 and the clutch 50 may also be arranged on the left side and the right side, respectively.

[0043] As in the Fig. 6 and Fig. 8, the continuously variable transmission 48 is a continuously variable belt drive in which a V-belt 52 as a flexible endless element extends between the drive pulley 53 and the driven pulley 54. The drive pulley 53 and the driven pulley 54 are mounted on a drive shaft 55 and a driven shaft 56, respectively. The drive shaft 55 is keyed (i.e., splined) to the countershaft 46, for example, to rotate in unison with the countershaft 46.

[0044] Thus, the torque transmitted from the crankshaft 35 to the countershaft 46 via the drive shaft 55, the drive pulley 53, the V-belt 52, and the driven pulley 54 is transmitted to the driven shaft 56. At this time, the effective diameter of a belt wound around the drive pulley 53 in the continuously variable transmission 48 is changed, so that the rotational speed of the driven pulley 54 can be changed with respect to that of the drive pulley 53, that is, a transmission ratio is continuously and steplessly changed. The effective diameter of a belt wound around the drive pulley 53 is changed by centrifugal force, engine driving force, or the like.

[0045] As in Fig. As shown in Fig. 8, the transmission case 49 was a case that covers the V-belt 52 of the continuously variable transmission 48, the drive pulley 53, the driven pulley 54, the drive shaft 55, the driven shaft 56, and the like. The transmission case 49 is formed by joining a left-side transmission case 49A, which is molded integrally with the left-side crankcase 36A, with a right-side transmission case 49B, which is molded integrally with the right-side crankcase 36B.

[0046] The clutch 50 of the drive force transmission device 24 is a centrifugal wet clutch, and as shown in the Fig. 7 and Fig. 8, it includes a clutch body which transmits or interrupts the torque transmitted to the continuously variable transmission 48 from the crankshaft 35 via the primary drive gear 45 and the driven primary gear 47.

[0047] The clutch body is composed of a clutch bell 58 integrally rotatably connected to a clutch shaft 57, and a clutch plate 59 located within the clutch bell 58 for sliding contact with the clutch bell 58. The clutch shaft 57 is coaxially and integrally rotatably disposed with the driven shaft 56. Furthermore, the clutch plate 59 is coupled to a gear train within the swing arm 57 via a clutch hub 60 and a reduction gear mechanism (not shown).

[0048] Accordingly, when the clutch plate 59 is brought into sliding contact with and engaged with the clutch bell 58, the torque transmitted from the crankshaft 35 to the continuously variable transmission 48 via the primary drive gear 45 and the driven primary gear 47 is applied to the reduction gear mechanism and gear train within the swing arm 27 from the driven shaft 56 of the transmission 48 via the clutch shaft 57, the clutch bell 58, the clutch plate 49, and the clutch hub 60 of the clutch 50. Consequently, the torque is transmitted to an axle shaft 56 described below to drive the rear wheel 26.The clutch shaft 57, the clutch bell 58, the clutch plate 59 and the clutch hub 60 of the clutch 50 are covered by the clutch housing 51, which is connected to the transmission case 49A for the continuously variable transmission from the outside of the vehicle.

[0049] As in the Fig. 4 and Fig. 5, the swing arm 27 is formed by joining a left swing arm 27a and a right swing arm 27b in the vehicle width direction. Furthermore, the swing arm 27 includes, as shown in Fig. 2 and Fig. 3: a pivot portion 61 located at the front end of the swing arm 27, into which a pivot pin 64 is inserted to pivotally secure the pivot portion 61 to the crankcase 36; a rear wheel support portion 62 functioning as a drive wheel support portion at the rear end of the swing arm 27, in which the axle shaft 65 is provided to rotatably support the rear wheel 26; and an arm 63 coupling the pivot portion 61 and the rear wheel support portion 62 to each other. The arm 63 in the left swing arm 27A contains the gear train for driving force transmission.

[0050] In the continuously variable transmission 48 of this embodiment, as shown in Fig. 6, the driven shaft 56, which forms a rotational center shaft for the driven pulley 54, is arranged rearward and above the drive shaft 55 as the rotational center shaft of the drive pulley 53. Accordingly, a straight line L connecting the drive shaft 55 and the driven shaft 56 extends rearward and obliquely upward, and consequently, the continuously variable transmission 46 extends rearward and obliquely upward.

[0051] The driven pulley 54 is also arranged such that its lower end point A is located above the lower end point B of the pivot pin 64 supporting the rocker arm 27, viewed in a side view of the vehicle according to Fig. 6.

[0052] In the Fig. 6, the gearbox housing 49 is configured such that its rear end point C is located behind a front end point D of the pivot pin 64 supporting the rocker arm 27. In addition, in the Fig. 6, the transmission case 49 is configured such that the pivot portion 61 on the right side of the swing arm 27 (the right pivot portion 61B) is located below a bottom surface 66 of the transmission case 49 (the right side of the transmission case 49B), that is, at least a part of the swing arm 27 or a front portion including the right pivot portion 61B vertically overlaps with a rear portion of the transmission case 49 for the continuously variable transmission (the right transmission case 49B).

[0053] In the present embodiment, the continuously variable transmission 48 is arranged with respect to the center line M in the vehicle width direction as shown in Fig. 8 and Fig. 9 on the right side. In the Fig. 9, the swing arm 27 is configured such that at least a part of the right swing part 61B or an outer end 67 of the right swing part 61B is located inside an extension line 68A including an outer end 68 of the transmission case 49 (the right side of the transmission case part 49B) in the vehicle width direction.

[0054] In the clutch 50 of the present embodiment, the clutch shaft 57, which is a rotation center shaft, is arranged behind and above the crankshaft 35 in the direction shown in Fig. 7. Furthermore, the clutch 50 is configured such that a lower end point E of the clutch bell 58 having a large diameter in the clutch body is located above an oil level H of the lubricant 70 located in the crankcase 36. Specifically, when the diameter of the clutch bell 58 is indicated by K, the lower end point E of the clutch bell 58 and the oil level H of the lubricant 70 are set to be separated from each other by K / 3 or more.

[0055] In the Fig. 7, the coupling 50 is further configured such that the pivot part 61 on the left side of the swing arm 27 (a left pivot part 61A) is located below a bottom surface 71 of the coupling housing 51 which houses the coupling 50, and at least a part of the swing arm 27 or its front portion with the left pivot part 61 of the swing arm 27 vertically overlaps with the coupling housing 51.

[0056] As in the Fig. 8 and Fig. 9, the coupling 50 is arranged on a left side with respect to the center line M in the vehicle width direction in this embodiment. In the Fig. 9, the swing arm 27 is configured such that at least a part of the left swing part 61A or an outer end 72 of the left swing part 61A of this embodiment is arranged inside the extension line 73A including the outer end 73 of the clutch housing 51 in the vehicle width direction.

[0057] By the structure or configuration of the embodiment described above, the following advantageous effects and functions (1) to (8) can be achieved: (1) With regard to the Fig. 6, the continuously variable transmission 48 is positioned to extend rearward and obliquely upward because the driven shaft 56 of the driven pulley 54 of the transmission 58 is located behind and above the drive shaft 55 of the drive pulley 53. Consequently, it becomes possible to increase the diameters of the drive pulley 53 and the driven pulley 54 while simultaneously preventing an increase in the length of the transmission 58 in the vehicle longitudinal direction, so that the range available for adjusting the reduction ratio of the continuously variable transmission 48 can be expanded and, accordingly, the acceleration and top speed can be improved, thereby enhancing the driving performance of the vehicle. (2) In the Fig. 6, the arrangement of the driven shaft 56 of the driven pulley 54 of the continuously variable transmission 46 is such that the driven shaft is located rearward and above the drive shaft 55 of the drive pulley 53, as mentioned in (1) above, and consequently, the continuously variable transmission 48 extends rearward and obliquely upward. This makes it possible to form a clearance below the driven pulley 54 when viewed from the side of the vehicle. As a result, by disposing the swing portion 61 (the right swing portion 61B) of the swing arm 27 within this clearance, the swing portion 61 (the right swing portion 61B) can be disposed at the front of the vehicle.

[0058] Furthermore, as explained here, since it is possible to dispose the swing part 61 (the left swing part 61A) at the front of the vehicle and reduce the length of the motorcycle 10 in the vehicle's longitudinal direction, the operability of the vehicle can be increased. Furthermore, since it is possible to simultaneously ensure the considerable length of the swing arm, the vertical travel range of the rear wheel 26 can be increased, thereby improving the ride comfort of the vehicle and improving overall vehicle comfort. (3) As in Fig. 6 and Fig. As shown in Fig. 9, at least a part of the right pivot portion 61B of the swing arm 27 is located inside the extension line 68A including the outer end 68 of the transmission case 49 (the right transmission case portion 49B) that houses the continuously variable transmission 48, to be accommodated in a space below the transmission case 49. Consequently, the peripheral space around the transmission case 49 is effectively utilized to make the layout of the parts or components simple and compact. (4) As in Fig. 6 and Fig. As shown in FIG. 9, the outer end 67 of the right pivot part 61B of the swing arm 27 is located inside the extension line 68A that includes the outer end 68 of the transmission case 49 in the vehicle width direction. Consequently, there is no projection of the outer end 67 protruding outward from the transmission case 49 in the vehicle width direction. As a result, it is possible to prevent the width of the lower part of the vehicle 10 from increasing, thereby ensuring the inclination angle (banking) of the vehicle and improving the vehicle's usability. (5) As in the Fig. 7 and Fig. As can be seen in Fig. 8, since the clutch 50 of the drive force transmission device 24 is located in the crankcase 36 above the oil level H of the lubricant 70 within the crankcase 36, the clutch 50 is not easily wetted by the lubricant 70 located in the crankcase 36. As a result, the engagement / disengagement response of the clutch 50 between the clutch bell 58 and the clutch plate 59 can be improved, which further enhances the operability of the vehicle.

[0059] Furthermore, since the clutch 50 is less easily wetted by the lubricant 70 within the crankcase 36, it is possible to ensure the responsiveness of clutch engagement and / or disengagement without requiring any lubricant discharge device within the crankcase 36. Accordingly, the power loss during operation of this lubricant discharge device is avoided, and the output of the motorcycle 10 can be improved. Furthermore, the structure of the motorcycle 10 is simplified, and the maintainability of the vehicle can be increased. (6) As in Fig. As shown in Fig. 7, because the clutch shaft 57 of the clutch 50 is located above the crankshaft 35 and the left pivot portion 61A of the swing arm 27 is located below the bottom surface 71 of the clutch housing 51, the front portion of the swing arm 27 including the left pivot portion 61A and the clutch housing 51 are arranged in a vertically overlapping arrangement. Therefore, by disposing the swing portion 61 (the left pivot portion 61A) of the swing arm in a space below the clutch housing 51, the swing portion 61 (the left pivot portion 61A) can be arranged at the front of the vehicle.

[0060] As explained above, this makes it possible to dispose the swing part 61 (the right swing part 61B) at the front of the vehicle and reduce the length of the motorcycle 10 in the vehicle's longitudinal direction, thus improving the operability of the vehicle. Furthermore, since it becomes possible to provide a sufficient length for the swing arm 27, the vertical travel range of the rear wheel 26 is increased, which improves the riding comfort of the motorcycle 10 and the overall vehicle comfort. (7) As in the Fig. 7 and Fig. As shown in Fig. 9, at least a portion of the left-side pivot portion 61A of the rocker arm 27 is located inside the outer end 73 of the clutch housing 51 accommodating the clutch 50, to be received in a space below the clutch housing 51. Accordingly, the peripheral space around the clutch housing 51 is effectively utilized for facilitating component layout. (8) As in Fig. 7 and Fig. As shown in Fig. 9, since the outer end 72 of the left pivot part 61A of the swing arm 27 is located inside the extension line 73A including the outer end 73 of the clutch housing 51 in the vehicle width direction, there is no projection of the outer end 72 projecting outward from the transmission case 49 in the vehicle width direction. As a result, it becomes possible to prevent the width of the lower portion of the motorcycle 10 from increasing, which guarantees the lean angle (banking) of the vehicle, and also makes it possible to improve the operability of the vehicle.

[0061] It should be noted that the present invention is not limited to the embodiment described herein, but that numerous changes and modifications or variations are possible within the spirit of the invention and without departing from the scope of the appended claims.

[0062] For example, the clutch 50 may be a multi-disk wet clutch or a single-disk wet clutch.

[0063] Although the described embodiment provides the clutch 50 which transmits or interrupts a torque transmitted from the crankshaft 35 to the continuously variable transmission 68, the clutch 50 may also be configured to transmit the torque from the crankshaft 35 to the continuously variable transmission 48 or to interrupt the torque.

[0064] Although the swing arm 27 has been described here as being pivotally mounted to the crankcase 36 via the pivot pin 64, the swing arm 27 can also be pivotally mounted to the body frame 15 of the vehicle via the pivot pin 64.

Claims

[1] Motorcycle (10), containing: a crankcase (36) which supports a crankshaft (35) of an engine (23), a drive force transmission device (24) located at an intermediate position between the crankshaft (35) and a drive wheel for transmitting torque from the crankshaft (35) to the drive wheel, and a swing arm (27) which supports the drive wheel in a swingable manner, wherein the drive force transmission device (24) comprises a continuously variable transmission (48) provided with a flexible endless member extending between a drive pulley (53) and a driven pulley (54), and a transmission case (49) for the continuously variable transmission (48) covering the continuously variable transmission (48), and in which a rotational center shaft of the driven pulley (54) is arranged behind and above the rotational center shaft of the drive pulley (53), as viewed in a side view of the motorcycle (10), wherein the swing arm (27) includes a pivot portion provided at one end side of the swing arm for pivotally mounting the swing arm on a motorcycle body frame (15) or on the crankcase (36), and a drive wheel support portion at another end side of the swing arm (27) for rotatably supporting the drive wheel, characterized by that the pivoting portion is arranged below a bottom side of the transmission housing (49) for the continuously variable transmission (48) when viewed in a side view of the motorcycle (10), so that at least a part of the swing arm (27) vertically overlaps a part of the transmission housing (49) for the continuously variable transmission (48), wherein the drive force transmission device (24) further comprises a clutch (50) with a clutch body that transmits or interrupts a torque from the crankshaft (35) or a transmission (48), and a clutch housing (51) covering the clutch (50), the clutch (50) including a lower end of the clutch body that is positioned above a lubricant oil level in the crankcase (36) when viewed from the side of the motorcycle (10), wherein the pivoting portion is located below a bottom of the clutch housing (51) in the side view of the motorcycle (10) to cause at least a part of the swing arm (27) to overlap vertically with the clutch housing (51), and wherein the clutch (50) is arranged on either the right or left side with respect to a center line of the motorcycle (10) in the motorcycle width direction, and the swing arm (27) includes at least a part of the pivot portion on the one side inside an outer end of the clutch housing (51) in the motorcycle width direction in a bottom view of the motorcycle (10). [2] A motorcycle (10) according to claim 1, wherein the continuously variable transmission (48) is arranged on either the right or left side with respect to a center line of the motorcycle (10) in the motorcycle width direction, and the swing arm (27) includes at least a part of the pivot portion on one side arranged inside an outer end of the transmission case (49) for the continuously variable transmission (48) in the motorcycle width direction when viewed in a bottom view of the motorcycle (10). [3] A motorcycle (10) according to claim 2, wherein the swing arm (27) includes an outer end of the pivoting portion on one side disposed inside the outer end of the transmission case (49) of the continuously variable transmission (48) in the motorcycle width view, as viewed in the bottom view of the motorcycle (10). [4] A motorcycle (10) according to any one of claims 1 to 3, wherein the swing arm (27) includes an outer end of the pivot portion on one side inside the outer end of the clutch housing (51) in the motorcycle width direction in a bottom view of the motorcycle (10).

Images