JP5687136B2 - Power unit for small vehicles - Google Patents

Description

  The present invention provides a transmission shaft that rotates in response to power transmission from an engine, a drive rotation member that rotates together with the transmission shaft, and a power that is transmitted from the drive rotation member so as to be relatively rotatable with respect to the transmission shaft. A continuously variable transmission having a driven rotary member to be supported and capable of continuously changing a gear ratio between the drive rotary member and the driven rotary member is provided between the engine and the drive wheel. The present invention relates to a vehicle power unit.

  If a neutral clutch is provided between the continuously variable transmission and the drive wheels to enable a small vehicle such as a motorcycle to be pushed and walked with light force, the number of parts and the size of the continuously variable transmission will increase. Patent Document 1 discloses a continuously variable transmission in which a power cut-off means capable of releasing one of a frictional contact between a driving rotating member and a planetary rotating member of a machine and a frictional contact between a driven rotating member and a planetary rotating member is provided. Is known.

JP 2001-214958 A

  However, in the case where the power cutoff means is built in the continuously variable transmission, such as that disclosed in Patent Document 1, the continuously variable transmission is operated when the small vehicle is pushed by operating the power cutoff means. Among the plurality of operating members that constitute, the operating member that rotates according to the rotation of the drive wheel generates resistance due to stirring of the oil and mechanical resistance due to spinning, and it is an issue to reduce the resistance Become.

  The present invention has been made in view of such circumstances, and an object of the present invention is to provide a power unit for a small vehicle that can reduce friction during pushing while avoiding an increase in the number of parts and an increase in size.

In order to achieve the above object, the present invention provides a transmission shaft that rotates in response to power transmission from an engine, a drive rotation member that rotates together with the transmission shaft, and power that is transmitted from the drive rotation member. A continuously variable transmission that includes a driven rotation member that is rotatably supported on the transmission shaft and that can change a transmission gear ratio between the drive rotation member and the driven rotation member steplessly; and et provided between the drive wheels is, between the driven rotary member and said drive wheel, in the small vehicle power unit centrifugal clutch Ru is interposed a transfer disconnecting-to the drive wheels of the output of the continuously variable transmission In the crankcase of the engine mounted on the vehicle body frame with the axis of the crankshaft along the vehicle width direction, the centrifugal clutch and the rotational axis of the centrifugal clutch are below The continuously variable transmission having the transmission shaft disposed therein is accommodated, a generator is connected to one end of the crankshaft, and the continuously variable transmission corresponds to an axially intermediate portion of the crankshaft in plan view A drive sprocket that is fixed to the crankshaft so that a cam chain is wound around the centrifugal clutch is disposed at a position corresponding to the other end of the crankshaft in plan view. A first power transmission means disposed between the cylinder axis and the generator on one side of a plane that includes the cylinder axis and is orthogonal to the axis of the crankshaft, and transmits power from the crankshaft to the continuously variable transmission; And second power transmission means for transmitting power from the continuously variable transmission to the centrifugal clutch with respect to the plane, the generator, the cam Wherein in En and the drive sprocket opposite disposed between the continuously variable transmission and the centrifugal clutch to the first aspect of Rukoto.

The present invention, in addition to the first feature, in the engine body including the crankcase, and a clutch chamber for accommodating the centrifugal clutch, the continuously variable transmission with the exception of the portion of the transmission shaft a transmission chamber housing to is formed, the first power transmission means disposed in said clutch chamber, the second power transmission means and the second being disposed on the transmission chamber.

  The rear wheel WR of the embodiment corresponds to the drive wheel of the present invention.

  According to the first feature of the present invention, the centrifugal clutch can start smoothly, and when the engine is stopped, the centrifugal clutch interrupts power transmission between the driven rotating member of the continuously variable transmission and the drive wheels. The members constituting the continuously variable transmission do not rotate when the small vehicle is pushed. Therefore, the centrifugal clutch for start-up also serves as a power cut-off mechanism during push-walking, avoiding an increase in the number of parts and an increase in size, while reducing friction during push-walking and pushing with a lighter force. become able to.

In addition, since the centrifugal clutch is housed in the crankcase, and the continuously variable transmission having the transmission shaft disposed below the rotational axis of the centrifugal clutch is housed, the continuously variable transmission is placed in the lower part of the crankcase. It is possible to suppress the oil surface height of the lubricating oil, reduce the friction due to the lubricating oil of the upper centrifugal clutch, further reduce the friction during pushing walking, and improve the pushing walking .

In addition, a generator is connected to one end of the crankshaft along the vehicle width direction, the continuously variable transmission is disposed at a position corresponding to the intermediate portion in the axial direction of the crankshaft in plan view, and the centrifugal clutch is cranked in plan view. Since it arrange | positions in the position corresponding to the other end part of a shaft, it can contribute to the improvement of riding comfort by making the right-and-left weight balance of a small vehicle favorable. Moreover, since the continuously variable transmission is arranged in the center of the vehicle body in the vehicle width direction, the oil level fluctuation of the lubricating oil accompanying the left and right tilting of the vehicle body can be kept small in the part corresponding to the continuously variable transmission. And increase in the amount of lubricating oil can be suppressed.

In particular, the cam chain and the drive sprocket fixed to the crankshaft so as to wind the cam chain are arranged on one side of a plane that includes the cylinder axis and is orthogonal to the axis of the crankshaft. The first power transmission means between the crankshaft and the continuously variable transmission and the second power transmission means between the continuously variable transmission and the centrifugal clutch are opposite to the generator, the cam chain and the drive sprocket with respect to the plane. Since it is arranged between the continuously variable transmission and the centrifugal clutch, the first and second power transmission means are arranged compactly while preventing the first and second power transmission means from affecting the arrangement of the cam chain. can do.

Further, according to the second feature of the present invention, the clutch chamber that houses the centrifugal clutch contains the first power transmission means for transmitting power from the crankshaft to the continuously variable transmission, except for a part of the transmission shaft. Since the second power transmission means for transmitting power from the continuously variable transmission to the centrifugal clutch is accommodated in the transmission chamber that accommodates the continuously variable transmission, the crankshaft The lubricating oil can be splashed onto the centrifugal clutch as it rotates, and the lubricity of the centrifugal clutch can be improved.

1 is a side view of a motorcycle. It is a side view of a power unit. FIG. 3 is a sectional view taken along line 3-3 in FIG. 2. FIG. 4 is a circumferential development cross-sectional view of a main part of a damper mechanism.

  The embodiment of the present invention will be described with reference to FIGS. 1 to 4 attached herewith. First, in FIG. 1, a body frame F of this motorcycle can steer a front fork 5 that supports a front wheel WF. A head pipe 6 to be supported, a main frame 7 extending rearward and downward from the head pipe 6, and a pair of left and right seat rails 8 extending rearward and continuing to the lower portion of the main frame 7 are provided. A steering handle 9 is connected to the upper portion of the front fork 5, and a passenger seat 10 for a passenger to sit on the seat rail 8 is provided to be openable and closable.

  A storage box 11 covered from above is disposed below the front portion of the riding seat 10, and a fuel tank 12 is disposed below the rear portion of the riding seat 10. 11 and the fuel tank 12 are supported by the seat rails 8.

  A power unit P disposed below the vehicle body frame F is suspended and supported on the main frame 7, and a driving wheel is mounted on the rear portion of the swing arm 13 whose front end is supported so as to be swingable. A certain rear wheel WR is pivotally supported, and the output of the power unit P is transmitted to the rear wheel WR via the chain transmission means 16 (see FIG. 3) arranged on the left side of the vehicle body frame F, so that the swing arm 13 and the seat rail 8 A rear cushion 14 is provided between them. The vehicle body frame F, a part of the power unit P, the storage box 11 and the fuel tank 12 are covered with a vehicle body cover 15.

  2 and 3, the power unit P includes a four-cycle engine E, and a continuously variable transmission T built in a crankcase 18 of the engine E so that the output of the engine E is continuously variable. A centrifugal clutch 80 and a damper mechanism 82 are provided.

  The engine body 17 of the engine E is coupled to the crankcase 18, a cylinder block 19 coupled to the front end of the crankcase 18 in a forward tilted posture in which the cylinder axis C is tilted forward, and a front end of the cylinder block 19. And a crankshaft 21 having an axis extending in the vehicle width direction is rotatably supported by the crankcase 18.

  The crankcase 18 is formed by joining a left case half 22 and a right case half 23 with a joining surface 24 along a plane perpendicular to the axis of the crankshaft 21. A left cover 25 is fastened to the left case half 22 from the outside, and a right cover 26 is fastened to the right case half 23 from the outside. The left cover 25 and the right cover 26 are also A part of the engine body 17 is configured.

  An intake system 28 is connected to an intake port 27 (see FIG. 3) provided on the upper side surface of the cylinder head 20, and the intake system 28 communicates with the intake port 27 to the cylinder head 20 at a downstream end. And an intake pipe 29 formed to bend forward, a carburetor 30 disposed above the cylinder head 20 and having a downstream end connected to the upstream end of the intake pipe 29, and the vaporization The air cleaner 31 (refer FIG. 1) which is arrange | positioned at the front upper side of the vaporizer 30 and to which the upstream end of the vaporizer 30 is connected.

  An exhaust system 33 is connected to an exhaust port (not shown) that opens to the lower side surface of the cylinder head 20, and the exhaust system 33 is connected to the cylinder head 20 at an upstream end so as to communicate with the exhaust port. In addition, an exhaust pipe 34 (see FIG. 1) extending rearward through the lower right side of the power unit P, and an exhaust muffler 35 disposed on the right side of the rear wheel WR and connected to the downstream end of the exhaust pipe 34. (See FIG. 1).

  Further, a spark plug 36 is attached to the right side surface of the cylinder head 20, and a plurality of fins 37, 37, 38, 38, etc. are projected from the outer surface of the cylinder block 19 and the cylinder head 20.

  Referring to FIG. 3, a generator chamber 39 is formed between the left case half 22 and the left cover 25 of the engine main body 17, and the left case half 22 and the right case that cooperate with the crankcase 18 are configured. A transmission chamber 40 is formed between the case halves 23, and a clutch chamber 41 is formed between the right case halves 23 and the right cover 26.

  One end of the crankshaft 21 rotatably supported by the left and right case halves 22 and 23 of the crankcase 18 via ball bearings 42 and 43 is inserted into the generator chamber 39 from the left case halves 22. The other end of the crankshaft 21 that has entered the clutch chamber 41 is supported by the right cover 26 via a ball bearing 44.

  A generator 45 is accommodated in the generator chamber 39, and the generator 45 is a rotor 46 fixed to one end of the crankshaft 21, and is surrounded by the rotor 46. The stator 47 is fixed to the left cover 25. That is, the generator 45 is connected to one end of the crankshaft 21.

  A gear 48 is supported on the crankshaft 21 so as to be relatively rotatable at a position adjacent to the rotor 46, and the gear 48 has a starter motor 49 (see FIG. 2) disposed above the crankcase 18. Rotation power from (see) can be transmitted. In addition, a one-way clutch 50 capable of only transmitting power from the gear 48 to the rotor 46 is interposed between the gear 48 and the rotor 46.

  The crankshaft 21 is fixedly provided with a drive sprocket 52 around which a cam chain 51 for transmitting power from the crankshaft 21 is wound around a camshaft of a valve gear (not shown). The sprocket 52 is disposed between the cylinder axis C and the generator 45 on one side of a plane PL that includes the cylinder axis C of the engine E and is orthogonal to the axis of the crankshaft 21.

  The continuously variable transmission T has a transmission shaft 53 that rotates in response to power transmission from the crankshaft 21 of the engine E, a drive rotation member 54 that rotates together with the transmission shaft 53, and power from the drive rotation member 54. A driven rotating member 55 that is transmitted to the transmission shaft 53 so as to be rotatable relative to the transmission shaft 53 and that can change the transmission gear ratio between the driving rotating member 54 and the driven rotating member 55 steplessly. In this embodiment, a plurality of planetary rotating members 56, 56 slidably contacting the drive rotating member 54 and the driven rotating member 55, and a carrier that rotatably supports the planetary rotating members 56, 56. 57, and continuously variable speed change by axial movement of the carrier 57 is possible. The continuously variable transmission T is provided between the engine E and the rear wheel WR. The continuously variable transmission T is disposed at a position corresponding to an intermediate portion in the axial direction of the crankshaft 21 in a plan view, while the transmission shaft 53 It is accommodated in the transmission chamber 40 except for a part.

  One end of the transmission shaft 53 having an axis parallel to the axis of the crankshaft 21 is rotatably supported on the left case half 22 via a ball bearing 58. The other end portion of the transmission shaft 53 passes through the right case half 23 rotatably and enters the clutch chamber 41. Between the right case half 23 and the transmission shaft 53, a ball bearing 59, An annular seal member 60 disposed on the clutch chamber 41 side with respect to the ball bearing 59 is interposed.

  Rotational power of the crankshaft 21 is transmitted to the transmission shaft 53 of the continuously variable transmission T via first power transmission means 61 disposed in the clutch chamber 41. This first power transmission means 61 is engaged with the first drive gear 62 and the first drive gear 62 fixed to the crankshaft 21 in the vicinity of the ball bearing 44 interposed between the other end of the crankshaft 21 and the right cover 26. A first driven gear 63, a gear receiving member 64 that supports the first driven gear 63 and is fixed to the other end of the transmission shaft 53, and the first driven gear 63 and the gear receiving member 64. It consists of a damper rubber 65.

  The drive rotation member 54 is formed in a ring shape having a friction contact surface 54a facing outward along the radial direction of the transmission shaft 53 on the outer periphery, and coaxially surrounding the transmission shaft 53. The transmission shaft 53 is supported by the transmission shaft 53 so that rotational power is transmitted from the transmission shaft 53. The driven rotation member 55 is formed in a bowl shape opened to the drive rotation member 54 side and is supported on the transmission shaft 53 so as to be relatively rotatable. A radius of the driven rotation member 55 is formed on the inner surface of the open end of the driven rotation member 55. A friction contact surface 55a facing inward is provided.

  The carrier 57 is formed in a substantially conical first carrier half 66 having a small diameter on the driven rotation member 55 side, and a large disk end side of the first carrier half 66, that is, the driven rotation. The carrier 57 comprises a second carrier half 67 fastened to the end opposite to the member 55, and the carrier 57 is supported on the transmission shaft 53 so as to be relatively rotatable and axially movable.

  The first carrier half 66 is provided with a plurality of window holes 68 at equal intervals in the circumferential direction, and has an axis along a conical generatrix centered on the axis of the transmission shaft 53. Both ends of a plurality of support shafts 69 crossing the window holes 68 are supported by the first carrier half body 66.

  The planetary rotating members 56, 56 are supported by the support shafts 69 so as to be rotatable and movable in the axial direction, and the planetary rotating members 56, 56 are supported on the friction contact surfaces of the drive rotating member 54. Conical first frictional transmission surfaces 70 that make frictional contact with 54a and conical second frictional transmission surfaces 71 that make frictional contact with the frictional contact surface 55a of the driven rotary member 55 are provided.

Wherein the transmission shaft 53 is provided integrally flange portion 53a opposed to the driving rotary member 54 from the second carrier half 67 side so as to protrude radially outward, the flange portion 5 3a and A first transmission pressure adjusting mechanism 72 is provided between the drive rotating members 54. When the transmission shaft 53 rotates, the first transmission pressure adjusting mechanism 72 contacts the first friction transmission surfaces 70 of the friction contact surface 54a. The rotational power of the transmission shaft 53 is transmitted to the drive rotation member 54 while adjusting the pressure.

  A driven screw 73 that is coaxial with the transmission shaft 53 is fastened to the second carrier half 67 of the carrier 57, and a driving screw 74 that is supported on the driven shaft 73 so as to be relatively rotatable with respect to the transmission shaft 53. Are screwed together. In addition, a gear 75 is fixed to the drive screw 74, and rotational power from an actuator (not shown) is applied to the drive screw 74 through a transmission gear mechanism 76 including the gear 75. Thus, when the drive screw 74 rotates, the carrier 57, to which the driven screw 73 is fastened, moves in the axial direction of the transmission shaft 53, and as shown in FIG. 3, the driven screw 73 and the carrier 57 are driven. When the rotation member 55 is located as close as possible to the rotation member 55, the ratio of the rotation number of the drive rotation member 54 to the rotation number of the driven rotation member 55 becomes low, and the driven screw 73 and the carrier 57 are connected to the driven rotation member. When it is far from the maximum, the ratio of the rotational speed of the drive rotary member 54 to the rotational speed of the driven rotary member 55 becomes the top speed ratio.

  By the way, the rotational power of the driven rotation member 55 is transmitted to the output shaft 83 via the second power transmission means 79, the centrifugal clutch 80, the third power transmission means 81 and the damper mechanism 82, and the rotation of the output shaft 83 is achieved. Power is transmitted to the rear wheel WR via the chain transmission means 16, and the output of the continuously variable transmission T is transmitted to the rear wheel WR between the driven rotating member 55 and the rear wheel WR. The centrifugal clutch 80 for connecting / disconnecting is connected.

  One end of a clutch shaft 84 having an axis parallel to the crankshaft 21 and the transmission shaft 53 and rotatably passing through the right case half 23 of the crankcase 18 is the left case half of the crankcase 18. The other end of the clutch shaft 84 is rotatably supported by the right cover 26 via a ball bearing 86.

  The second power transmission means 79 is supported by the transmission shaft 53 through an angular contact bearing 87 and a needle bearing 88 so as to be relatively rotatable, and is supported by the clutch shaft 84 so as to be relatively rotatable. The second driven gear 90 meshes with the second drive gear 89 and is accommodated in the transmission chamber 40.

  Thus, the first power transmission means 61 for transmitting power from the crankshaft 21 to the continuously variable transmission T and the second power transmission means 79 for transmitting power from the continuously variable transmission T to the centrifugal clutch 80 are the cylinder axis. C is disposed between the continuously variable transmission T and the centrifugal clutch 80 on the opposite side of the generator 45, the cam chain 51 and the drive sprocket 52 with respect to the plane PL perpendicular to the axis of the crankshaft 21 including C. .

  The second drive gear 89 is rotatably supported on the transmission shaft 53 at a position facing the driven rotation member 55 of the continuously variable transmission T from the side opposite to the drive rotation member 54, The small-diameter end of the driven rotating member 55 is supported by the second drive gear 89 so as to be relatively rotatable.

  In addition, a leaf spring 91 for biasing the driven rotary member 55 toward the carrier 57 is interposed between the driven rotary member 55 and the second drive gear 89, and the second friction transmission surface 71 of the friction contact surface 55a. A second pressure adjusting transmission mechanism 92 that transmits the rotational power from the driven rotating member 55 while adjusting the contact pressure to the second drive gear 89 is provided. A thrust bearing 93 capable of rolling contact with the driven rotary member 55 and the second drive gear 89 is attached to the small diameter end portion of the first carrier half 66 in the carrier 57.

  The centrifugal clutch 80 is coupled to the clutch shaft 84 so as not to rotate relative to the clutch shaft 84 and is fixed to a transmission cylinder shaft 96 that rotatably passes through the right case half 23 of the crankcase 18. Centrifugal weights 98 supported at a plurality of locations, a clutch outer 99 fixed to the clutch shaft 84 so that these centrifugal weights 98 can be frictionally engaged with the inner periphery, and each centrifugal weight 98. The clutch springs 100 are provided between the drive plates 97 and are accommodated in the clutch chamber 41 while being arranged at a position corresponding to the other end of the crankshaft 21 in plan view.

  The centrifugal clutch 80 has centrifugal weights 98 when the centrifugal force acting on the centrifugal weights 98 in response to the rotation of the transmission cylinder shaft 96 and the drive plate 97 exceeds the spring biasing force of the clutch springs 100. Frictionally engages the inner periphery of the clutch outer 99 to bring the transmission cylinder shaft 96 and the clutch shaft 84 into a power transmission state, and when the rotational speed of the transmission cylinder shaft 96 and the drive plate 97 is below a predetermined value, Power transmission between the transmission cylinder shaft 96 and the clutch shaft 84 is cut off.

  By the way, as shown in FIG. 2, lubricating oil is stored up to the oil level L in the lower part of the crankcase 18, and the continuously variable transmission is partially immersed in the lubricating oil. The centrifugal clutch 80 is arranged such that its rotational axis, that is, the axis of the clutch shaft 84 is located above the transmission shaft 84 of the continuously variable transmission T, while T is disposed in the lower portion of the crankcase 18. And accommodated in the crankcase 18. In other words, the crankcase 18 accommodates the centrifugal clutch 80 and the continuously variable transmission T in which the transmission shaft 53 is disposed below the rotational axis of the centrifugal clutch 80 (the axis of the clutch shaft 84).

  The output shaft 83 is rotatably penetrated through the left case half 22 of the crankcase 18 so that one end thereof protrudes leftward from the crankcase 18, and the output shaft 83 and the left case half 22, a ball bearing 101 and an annular seal member 102 are interposed, and the other end of the output shaft 83 is rotatably supported by the right case half 23 of the crankcase 18 via the ball bearing 103. The

  A drive sprocket 109 is fixed to one end portion of the output shaft 83 protruding leftward from the crankcase 18, and a drive chain 110 for transmitting power to the rear wheel WR is wound around the drive sprocket 109. Thus, the chain transmission means 16 comprises the drive sprocket 109 and the drive chain 110 and a driven sprocket (not shown) provided on the axle of the rear wheel WR so that the drive chain 110 is wound around. Is done.

  The third power transmission means 81 includes a third drive gear 104 formed integrally with the clutch shaft 84, and a third driven gear 105 that is rotatably supported by the output shaft 83 and meshes with the third drive gear 104. A damper mechanism 82 is provided between the third driven gear 105 and the output shaft 83.

  The output shaft 83 is integrally provided with a flange portion 83a projecting outward in the radial direction, and the output shaft 83 has a rotation transmission member at a position where the third driven gear 105 is sandwiched between the output shaft 83 and the flange portion 83a. 106 is fixed.

  Referring also to FIG. 4, the damper mechanism 82 plunges into a plurality of recesses 107 provided on the surface of the third driven gear 105 facing the rotary transmission member 106, and the recesses 107. The plurality of protrusions 106a... Projecting integrally with the rotation transmission member 106, and the spring force that causes the third driven gear 105 to slidably contact the rotation transmission member 106. The width W1 of the protrusions 106a along the circumferential direction of the output shaft 83 is greater than the width W2 of the recesses 107 along the circumferential direction of the output shaft 83. Is also set small.

  According to such a damper mechanism 82, the centrifugal clutch 80 accompanying the vibration of the drive chain 11 and the excessive rotational torque in the acceleration / deceleration direction to the continuously variable transmission T are applied to the concave portion 107 and the protruding portion 106a. ... can be absorbed by gaps (play) between them and contribute to improvement of durability.

  Next, the operation of this embodiment will be described. The continuously variable transmission T provided between the engine E and the rear wheel WR is rotated together with a transmission shaft 53 that rotates in response to power transmission from the engine E, and the transmission shaft 53. A rotating drive rotating member 54, a driven rotating member 55 that is rotatably supported by the transmission shaft 53, a plurality of planetary rotating members 56 that are in sliding contact with the driving rotating member 54 and the driven rotating member 55, and their planetary rotations. The carrier 56 has a carrier 57 that rotatably supports the member 56 and enables a continuously variable transmission by the axial movement of the carrier 57. The continuously variable transmission T is provided between the driven rotating member 55 and the rear wheel WR. Since the centrifugal clutch 80 for connecting / disconnecting the output of the output to the rear wheel WR is interposed, the centrifugal clutch 80 can smoothly start and When the engine E stops, the centrifugal clutch 80 cuts off the power transmission between the driven rotation member 55 of the continuously variable transmission T and the rear wheel WR, so that the members constituting the continuously variable transmission T when the motorcycle is pushed It does not rotate. Therefore, the centrifugal clutch 80 for start-up also serves as a power cut-off mechanism during push-walking, avoiding an increase in the number of parts and an increase in size, while reducing friction during push-walking and pushing with a lighter force. Will be able to.

  In addition, the crankcase 18 of the engine E accommodates the centrifugal clutch 80 and the continuously variable transmission T in which the transmission shaft 53 is disposed below the rotational axis of the centrifugal clutch 80. Is placed in the lower part of the crankcase 18 to suppress the oil level of the lubricating oil, to reduce the friction caused by the lubricating oil of the upper centrifugal clutch 80, to further reduce the friction during pushing and walking. It can be good.

The engine E is mounted on the vehicle body frame F with the axis of the crankshaft 21 extending in the vehicle width direction, a generator 45 is connected to one end of the crankshaft 21, and the continuously variable transmission T is viewed in plan view. is disposed at a position corresponding to the axially intermediate portion of 21, the centrifugal clutch 80 is disposed at a position corresponding to the other end of the crank shaft 21 in a plan view, the lateral weight balance of the motorcycle as good It can contribute to the improvement of riding comfort. In addition, since the continuously variable transmission T is disposed at the center of the vehicle body in the vehicle width direction, the oil level fluctuation of the lubricating oil accompanying the left and right tilting of the vehicle body is kept small in the portion corresponding to the continuously variable transmission T. And increase in the amount of lubricating oil can be suppressed.

  A drive sprocket 52 fixed to the crankshaft 21 so that the cam chain 51 is wound around the cylinder axis C and the generator on one side of the plane PL including the cylinder axis C and orthogonal to the axis of the crankshaft 21. The first power transmission means 61 that transmits power from the crankshaft 21 to the continuously variable transmission T and the second power that transmits power from the continuously variable transmission T to the centrifugal clutch 80 are disposed between the two. Since the transmission means 79 is disposed between the continuously variable transmission T and the centrifugal clutch 80 on the opposite side of the generator 45, the cam chain 51, and the drive sprocket 52 with respect to the plane PL, The first and second power transmission means 61 and 79 are made compact while preventing the second power transmission means 61 and 79 from affecting. It can be arranged.

  Further, in the engine body 17 of the engine E, a clutch chamber 41 that houses the centrifugal clutch 80 and a transmission chamber 40 that houses the continuously variable transmission T except for a part of the transmission shaft 53 are formed. Since the transmission means 61 is disposed in the clutch chamber 41 and the second power transmission means 79 is disposed in the transmission chamber 40, the centrifugal clutch 80 accompanying the rotation of the crankshaft 21 regardless of the gear ratio in the continuously variable transmission T. It is possible to splash the lubricating oil on the centrifugal clutch 80 and improve the lubricity of the centrifugal clutch 80.

  Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and various design changes can be made without departing from the present invention described in the claims. Is possible.

  For example, the present invention can be applied not only to motorcycles but also to other small vehicles such as motor tricycles.

17 ... Engine body 18 ... Crankcase 21 ... Crankshaft 40 ... Transmission chamber 41 ... Clutch chamber 45 ... Generator 51 ... Cam chain 52 ... Drive sprocket 53 ... Transmission shaft 54 ... Drive rotation member 55 ... Driven rotation member 61 ... First power transmission means 79 ... Second power transmission means 80 ... Centrifuge clutch C ... Cylinder axis E ... Engine F ... Body frame P ... Power unit PL ... Plane T ... Continuously variable transmission WR ... Rear wheel as drive wheel

Claims (2)

A transmission shaft (53) that rotates in response to power transmission from the engine (E), a drive rotation member (54) that rotates together with the transmission shaft (53), and power is transmitted from the drive rotation member (54). In this way, there is a driven rotation member (55) that is rotatably supported on the transmission shaft (53), and the gear ratio between the drive rotation member (54) and the driven rotation member (55) is stepless. continuously variable transmission as may be varied (T) is, the engine (E) and is al provided between the drive wheel (WR), while the driven rotating member (55) and said drive wheel (WR), the wherein in the small vehicle power unit the centrifugal clutch (80) Ru is interposed a transfer cross-contact of the drive wheel (WR) of the output of the continuously variable transmission (T), the vehicle width of the axis of the crankshaft (21) Body frame along the direction The centrifugal clutch (80) and the transmission shaft (53) are disposed below the rotational axis of the centrifugal clutch (80) in the crankcase (18) of the engine (E) mounted on F). The continuously variable transmission (T) is accommodated, a generator (45) is connected to one end of the crankshaft (21), and the continuously variable transmission (T) is viewed in plan view from the crankshaft (21). The centrifugal clutch (80) is arranged at a position corresponding to the other end of the crankshaft (21) in plan view, and the cam chain (51) is wound around the centrifugal clutch (80). Thus, the drive sprocket (52) fixed to the crankshaft (21) includes the cylinder axis (C) of the engine (E) and is orthogonal to the axis of the crankshaft (21). A first power transmission is disposed between the cylinder axis (C) and the generator (45) on one side of the surface (PL) and transmits power from the crankshaft (21) to the continuously variable transmission (T). Means (61) and second power transmission means (79) for transmitting power from the continuously variable transmission (T) to the centrifugal clutch (80), the generator (45) with respect to the plane (PL), small vehicle power unit, characterized in Rukoto disposed in the cam chain (51) and said drive sprocket (52) and said opposite continuously variable transmission (T) and the centrifugal clutch (80) between. Before SL engine body (17) in including a crankcase (18), said clutch chamber containing the centrifugal clutch (80) and (41), said transmission shaft (53) the continuously variable transmission except for some (T) is formed, a first power transmission means (61) is arranged in the clutch chamber (41), and a second power transmission means (79) is arranged in the transmission chamber (41). 40) The power unit for a small vehicle according to claim 1, wherein the power unit is disposed at 40).

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