JP6000394B1 - Power unit - Google Patents

Abstract

A kick shaft and a crankshaft in which a continuously variable transmission is housed in a transmission case that has a case cover that covers the continuously variable transmission from the outside and is connected to the crankcase, and that freely passes through the case cover. In the meantime, in the power unit in which the kick start mechanism is interposed, it is not necessary that the case cover has high rigidity. An inner end portion of a kick shaft 55 that penetrates a through hole 63 provided in a case cover 44 is rotatably supported by a crankcase 14. [Selection] Figure 2

Description

  According to the present invention, a V-belt type continuously variable transmission having a drive pulley provided on a crankshaft of an internal combustion engine has a case cover that covers the continuously variable transmission from the outside. Between the kick shaft and the crankshaft that is housed in a transmission case that is continuously provided and that is rotatably disposed through the case cover so that a kick lever disposed outside the case cover is provided at an outer end portion. A drive gear fixed to the kick shaft, a driven gear movable in the axial direction of the crankshaft in accordance with power transmission from the drive gear, a drive-side ratchet that operates with the driven gear, and the crankshaft The drive side ratchet can be detachably engaged in accordance with the movement of the drive side ratchet in a direction along the axis of the About power unit kick starting mechanism is interposed and a driven-side ratchet provided so as to rotate together with the rank shaft on the crankshaft.

A portion of a transmission case that accommodates a V-belt type continuously variable transmission, and a kick shaft that passes through a case cover that covers the continuously variable transmission from the outside, and a crankshaft between the kick shaft, a power unit which is adapted kick startup mechanism so as to rotate the crank shaft is provided by the rotation operation are known in US Pat.

JP-A-8-170574

  However, in the one disclosed in Patent Document 1, the kick shaft is rotatably supported by the case cover, and the case cover must be formed of a highly rigid material such as metal.

  The present invention has been made in view of such circumstances, and an object thereof is to provide a power unit that does not require a case cover to have high rigidity.

In order to achieve the above object, the present invention provides a V-belt type continuously variable transmission having a drive pulley provided on a crankshaft of an internal combustion engine, having a case cover that covers the continuously variable transmission from the outside. And a kick lever, which is housed in a transmission case connected to the crankcase of the internal combustion engine and is arranged on the outer side of the case cover, is rotatably provided through the case cover. A drive gear fixed to the kick shaft between the kick shaft and the crankshaft, a driven gear movable in the axial direction of the crankshaft in accordance with power transmission from the drive gear, and the driven gear operate together The drive-side ratchet is engaged with the drive-side ratchet detachably according to the movement of the drive-side ratchet in the direction along the axis of the crankshaft. In a power unit in which a kick start mechanism having a driven ratchet provided on the crankshaft so as to rotate together with the crankshaft is made to pass through a through hole provided in the case cover An inner end portion of the kick shaft is rotatably supported by the crankcase, and the crankcase is formed by joining a pair of crankcase halves that can be divided in the axial direction of the crankshaft. A first feature is that an inner end portion of the kick shaft penetrating through a through hole provided in the shaft is rotatably supported by the pair of crankcase halves .

According to the present invention, a V-belt continuously variable transmission having a drive pulley provided on a crankshaft of an internal combustion engine has a case cover for covering the continuously variable transmission from the outside, and the crankcase of the internal combustion engine is provided. Between the kick shaft and the crankshaft, which is housed in a transmission case connected to the outer periphery of the case cover and rotatably disposed through the case cover so that a kick lever disposed outside the case cover is provided at an outer end portion A driving gear fixed to the kick shaft, a driven gear movable in the axial direction of the crankshaft in accordance with power transmission from the driving gear, a driving side ratchet that operates with the driven gear, and the crank While enabling the drive side ratchet to be detachably engaged in accordance with the movement of the drive side ratchet in the direction along the axis of the shaft, An inner end of the kick shaft passing through a through hole provided in the case cover in a power unit having a kick start mechanism having a driven ratchet provided on the crankshaft so as to rotate with the crankshaft And a cylindrical support tube portion that coaxially surrounds the crankshaft and projects into the transmission case, and is provided on the crankcase. A second feature is that an outer periphery of the driven gear, which is formed in a cylindrical shape by forming an annular gap therebetween, is supported rotatably and axially movable on the inner periphery of the support cylinder portion.

According to the present invention, a V-belt type continuously variable transmission having a drive pulley provided on a crankshaft of an internal combustion engine has a case cover that covers the continuously variable transmission from the outside. Between the kick shaft and the crankshaft that is housed in a transmission case that is continuously provided and that is rotatably disposed through the case cover so that a kick lever disposed outside the case cover is provided at an outer end portion. A drive gear fixed to the kick shaft, a driven gear movable in the axial direction of the crankshaft in accordance with power transmission from the drive gear, a drive-side ratchet that operates with the driven gear, and the crankshaft The drive side ratchet can be detachably engaged in accordance with the movement of the drive side ratchet in a direction along the axis of the In a power unit having a kick start mechanism having a driven ratchet provided on the crankshaft so as to rotate with a rank shaft, an inner end portion of the kick shaft passing through a through hole provided in the case cover Is rotatably supported by the crankcase, and the drive pulley is fixed to the crankshaft, and the fixed sheave and the crank are supported by the crankshaft so as to be able to approach and move away from the fixed sheave. A weight holding plate that constitutes a part of a centrifugal shift mechanism that includes a movable sheave disposed between cases and serves to bring the movable sheave closer to the fixed sheave in accordance with an increase in the number of rotations of the crankshaft. It faces the movable sheave from the side opposite to the fixed sheave. One fixed to said crankshaft, said driven-side ratchet, the third being disposed in a portion overlapping with the position of said weight holding plate as viewed from a direction perpendicular to the axis of the crankshaft.

According to the present invention, in addition to the structure of the third feature, the crankcase is provided with a cylindrical support tube portion that coaxially surrounds the crankshaft and enters the transmission case. Fourth, the outer periphery of the driven gear formed in a cylindrical shape with an annular gap formed between the outer surface of the crankshaft and the inner periphery of the support cylinder portion is supported rotatably and axially movable. It is characterized by.

According to the present invention, in addition to any one of the configurations of the second to fourth features, the crankcase is formed by combining a pair of crankcase halves that can be divided in the axial direction of the crankshaft, and the kick shaft A fifth feature is that the inner end portions of the crankcase are rotatably supported by the pair of crankcase halves.

Furthermore, the present invention provides that, in addition to any of the first to fifth features, the kick start mechanism is disposed between the crankcase and the drive pulley in a direction along the axis of the crankshaft. Six features.

According to the first feature of the present invention, since the inner end of the kick shaft is rotatably supported by the crankcase, the case cover through which the kick shaft passes does not need to have high rigidity, and the case cover is formed. The degree of freedom in selecting the material to be used increases. Further, since the inner end portion of the kick shaft is supported by a pair of crankcase halves that are coupled to each other so as to constitute the crankcase in cooperation, the long portion of the kick shaft is supported by the crankcase. Therefore, the support rigidity of the kick shaft can be increased.

According to the second feature of the present invention, a cylindrical driven gear which is provided in the crankcase and which forms an annular gap between the cylindrical support tube portion coaxially surrounding the crankshaft and the outer surface of the crankshaft. Therefore, it is possible to prevent friction between the crankshaft and the driven gear by preventing the driven gear from being supported by the crankshaft.

According to the third aspect of the present invention, a part of the weight holding plate that constitutes a part of the centrifugal shift mechanism that works to bring the movable sheave closer to the fixed sheave in response to an increase in the rotational speed of the crankshaft, side ratchet, since overlap when viewed from a direction perpendicular to the axis of the crankshaft, the continuously variable transmission and a kick start rotation mechanism can be arranged compactly in a direction along the axis of the crankshaft.

  According to the fourth aspect of the present invention, a cylindrical driven gear which is provided in the crankcase and which forms an annular gap between the cylindrical support tube portion coaxially surrounding the crankshaft and the outer surface of the crankshaft. Therefore, it is possible to prevent friction between the crankshaft and the driven gear by preventing the driven gear from being supported by the crankshaft.

According to the fifth aspect of the present invention, the inner end of the kick shaft is supported by the pair of crankcase halves that are coupled to each other so as to cooperate with the crankcase. Thus, the long part is supported by the crankcase, so that the support rigidity of the kick shaft can be increased.

Further, according to the sixth aspect of the present invention, since the kick start mechanism is disposed between the crankcase and the drive pulley in a direction along the axis of the crankshaft, the kick start mechanism is disposed compactly in the transmission case. Can do.

Fig. 2 is a left side view of a power unit mounted on a motorcycle. FIG. 2 is a sectional view taken along line 2-2 of FIG. FIG. 3 is a sectional view taken along line 3-3 in FIG. 2. It is a perspective view showing a kick startup mechanism. FIG. 5 is an enlarged view of a portion indicated by an arrow 5 in FIG. 2. It is a perspective view of a driven gear and a drive side ratchet. It is a perspective view which shows a support cylinder part vicinity.

  Embodiments of the present invention will be described with reference to the accompanying drawings. In the following description, the front, rear, top and bottom, and left and right directions refer to directions viewed from a passenger on a motorcycle on which an internal combustion engine is mounted.

  First, in FIGS. 1 and 2, a motorcycle body frame (not shown) has a single-cylinder internal combustion engine E that exerts power for driving the rear wheels WR, and the power of the internal combustion engine E is continuously variable. A power unit P having a V-belt type continuously variable transmission M that is suspended in a vertically swingable manner, is connected to the engine body 11 of the internal combustion engine E, and extends to the right side of the rear wheel WR. A continuously variable transmission M is accommodated therein, and the rear wheel WR is pivotally supported by the rear portion of the transmission case 12.

  The engine body 11 includes a crankcase 14 that rotatably supports a crankshaft 13 whose axis is aligned in the vehicle width direction, a cylinder body 15 that has a cylinder bore 18 and is coupled to the crankcase 14, and the cylinder A cylinder head 16 coupled to the body 15 and a head cover 17 coupled to the cylinder head 16 are provided.

  The crankcase 14 is formed by connecting a right crankcase half 20 and a left crankcase half 21. The crankshaft 13 rotatably passes through the right crankcase half 20 and the left crankcase half 21 and is rotatably supported by the crankcase halves 20 and 21. 13 and the right crankcase half 20 are provided with a first ball bearing 25. Between the crankshaft 13 and the left crankcase half 21, a second ball bearing 26 and a second ball bearing are provided. 26 and an annular seal member 27 disposed outside in the axial direction. A piston 23 slidably fitted to the cylinder bore 18 is connected to a crank pin 13a of the crankshaft 13 via a connecting rod 24.

Wherein the right crankcase half 20, a generator cover 28 is formed into a bottomed cylindrical shape is coupled so as to form a generator chamber 29 between the right crankcase half 20, the generator A generator 30 is accommodated in the machine room 29.

  The cylinder head 16 is provided with an intake valve and an exhaust valve (not shown) that can be opened and closed. The valve chamber 31 formed between the cylinder head 16 and the head cover 17 includes the intake valve and the exhaust valve. A valve operating mechanism 32 that opens and closes the exhaust valve is accommodated.

  The valve mechanism 32 includes a camshaft 33 having an axis parallel to the crankshaft 13 and rotatably supported by the cylinder head 16, and an intake side rocker arm provided between the camshaft 33 and the intake valve. 34 and an exhaust side rocker arm 35 provided between the camshaft 33 and the exhaust valve.

  Rotational power from the crankshaft 13 is transmitted to the camshaft 33 of the valve mechanism 32 by a timing transmission mechanism 36 with a reduction ratio of 1/2.

  The timing transmission mechanism 36 includes a cam chain drive sprocket 37 disposed between the first ball bearing 25 and the generator 30 and fixed to the crankshaft 13, and a cam fixed to the camshaft 33. An endless cam chain 39 is wound around a chain driven sprocket 38, and a cam chain chamber 40 for running the cam chain 39 is located on the right side of the engine body 11 on the right side of the cylinder bore 18. A crankcase half 20, the cylinder body 15 and the cylinder head 16 are formed.

  A partition wall member 41 that separates the cam chain chamber 40 and the generator chamber 39 is fastened to the right crankcase half 20, and the crankshaft that penetrates the partition wall member 41 in a liquid-tight and rotatable manner. The outer rotor 42 of the generator 30 is fixed to the right end of the generator 13, and the inner stator (not shown) of the generator 30 is fixed to the generator cover 28.

  The transmission case 12 is fastened to the case main portion 43 so as to cover the continuously variable transmission M from the outer side with a case main portion 43 provided integrally with the left crankcase half 21 of the crankcase 14. A part of the continuously variable transmission M is formed at the right end of the crankshaft 13 projecting from the left crankcase half 21 and projecting into the transmission case 12. A driving pulley 46 is provided. The drive pulley 46 is fixed to the crankshaft 13, and a fixed sheave 47 is disposed on the inner side in the axial direction of the fixed sheave 47, and is supported on the crankshaft 13 so as to be axially movable. A V-belt 49 is wound between the fixed sheave 47 and the movable sheave 48.

  The movable sheave 48 is driven to the side closer to the fixed sheave 47 according to the increase in the rotational speed of the crankshaft 13 by the action of the centrifugal shift mechanism 50, and the centrifugal shift mechanism 50 is A cam surface 51 is formed on the surface of the movable sheave 48 opposite to the fixed sheave 47, and is fixed to the crankshaft 13 so as to face the movable sheave 48 from the opposite side of the fixed sheave 47. A weight holding plate 52 and a plurality of weights 53 held between the cam surface 51 and the weight holding plate 52 are provided.

  3 and 4 together, a kick shaft 55 that rotatably passes through the case cover 44 such that a kick lever 54 disposed outside the case cover 44 is provided at an outer end portion, and A kick start mechanism 56 is provided between the crank shafts 13 so as to start the internal combustion engine E by rotationally driving the crank shaft 13 in accordance with the rotation of the kick shaft 55.

  The kick start mechanism 56 includes a drive gear 57 fixed to the kick shaft 55, a driven gear 58 that can move in the axial direction of the crankshaft 13 in accordance with power transmission from the drive gear 57, and the driven gear. The drive side ratchet 59 that operates together with the drive shaft 58 and the drive side ratchet 59 that can be engaged and disengaged in accordance with the movement of the drive side ratchet 59 in the direction along the axis of the crankshaft 13. And a driven ratchet 60 provided on the crankshaft 13 so as to rotate together with the crankshaft 13. In this embodiment, the kick starting mechanism 56 includes the drive gear 57, the driven gear 58, and the drive. In addition to the side ratchet 59 and the driven side ratchet 60, the first intermediate teeth meshing with the drive gear 57 61 and a second intermediate gear 62 meshing with the driven gear 58 so as to rotate together with the first intermediate gear 61, and the crankcase 14 and the drive in a direction along the axis of the crankshaft 13. Arranged between pulleys 46.

  By the way, the case cover 44 is provided with a through hole 63 that penetrates the kick shaft 55 behind the crankshaft 13, and the inner end of the kick shaft 55 that penetrates the through hole 63 The crankcase 14 is rotatably supported.

  In addition, the inner end portion of the kick shaft 55 is rotatably supported by the right crankcase half 20 and the left crankcase half 21 which are coupled to each other so as to constitute the crankcase 14 in cooperation. The right crankcase half 20 is provided with a bottomed support hole 64 that opens to the left crankcase half 21 side in parallel with the axis of the crankshaft 13 and is coaxial with the support hole 64. A support hole 65 is provided in the left crankcase half 21 as a through hole open at both ends, and the inner end of the kick shaft 55 is fitted so as to be rotatably supported by the support holes 64 and 65. Combined.

  The drive gear 57 is a sector gear, and a coiled torsion spring 66 surrounding the kick shaft 55 is interposed between the drive gear 57 fixed to the kick shaft 55 and the left crankcase half 21. It is interposed so as to exert a spring force that urges the kick shaft 55 to the return side.

  The first intermediate gear 61 is formed to have a small diameter so as to mesh with the drive gear 57, and a shaft 67 integrally formed with the first intermediate gear 61 is provided between the kick shaft 55 and the crankshaft 13. Thus, it is rotatably fitted in a support recess 68 provided in the left crankcase half 21. The second intermediate gear 62 is a worm wheel, is formed with a larger diameter than the first intermediate gear, and is coaxially fixed to the first intermediate gear 61.

Referring also to FIGS. 5 to 7, the driven gear 58 is formed in a cylindrical shape as a worm that meshes with a second intermediate gear 62 that is a worm wheel. The left crankcase half 21 of the crankcase 14 is provided with a cylindrical support tube portion 21a that coaxially surrounds the crankshaft 13 and enters the transmission case 12, and the crankshaft the outer periphery of the driven gear 58 to form an annular gap 6 9 is formed in a cylindrical shape between the 13 outer surface of is rotatably and axially movably supported by the inner periphery of the support cylinder portion 21a.

  In addition, a notch 70 for engaging the second intermediate gear 62 with the driven gear 58 is provided at the tip of the support cylinder portion 21a. In addition, a friction spring 71 is wound around the driven gear 58, and both ends of the friction spring 71 are provided in the support cylinder portion 21a so as to be continuous with the notch 70 and are formed long in the axial direction. The guide recess 72 is slidably engaged with side edges on both sides in the circumferential direction.

  The driving side ratchet 59 is formed integrally with the driven gear 58, and the driven side ratchet 60 is fixed to the crankshaft 13 so as to face the driving side ratchet 59.

  Incidentally, the crankshaft 13 is regulated with an annular stepped portion 76 that faces the opposite side of the drive side ratchet 59, and the driven ratchet 60 that is splined to the crankshaft 13 has the annular stepped portion 76. Abut. In addition, the driven ratchet 60 is sandwiched between the inner peripheral portion of the weight holding plate 52 and the annular stepped portion 76 that are splined to the crankshaft 13. Further, a fixed sheave 47 sandwiching a cylindrical sleeve 73 surrounding the crankshaft 13 between the weight holding plate 52 and the inner peripheral portion is splined to the crankshaft 13, and the left end of the crankshaft 13 is The driven ratchet 60, the weight holding plate 52, and the fixed sheave 47 are fixed to the crankshaft 13 by tightening the nut 74 that is screwed into the portion.

  The driven ratchet 60 is disposed at a position overlapping with a part of the weight holding plate 52 when viewed from a direction orthogonal to the axis of the crankshaft 13, and in this embodiment, the weight holding plate The driven ratchet 60 is disposed in a recess 75 that 52 has on its inner periphery.

  Next, the operation of this embodiment will be described. The continuously variable transmission M is accommodated in a transmission case 12 that has a case cover 44 that covers the continuously variable transmission M from the outside and is connected to the crankcase 14. A kick start mechanism 56 is interposed between the kick shaft 55 and the crankshaft 13 that rotatably penetrates the case cover 44 so that a kick lever 54 disposed outside the case cover 44 is provided at the outer end. Since the inner end of the kick shaft 55 penetrating through the through hole 63 provided in the case cover 44 is rotatably supported by the crank case 14, the case cover 44 through which the kick shaft 55 passes is high. It is not necessary to have rigidity, and the degree of freedom in selecting a material for forming the case cover 44 is increased.

  The crankcase 14 is formed by combining a right crankcase half 20 and a left crankcase half 21 that can be divided in the axial direction of the crankshaft 13, and an inner end portion of the kick shaft 55 is a right crankcase half. 20 and the left crankcase half 21 are rotatably supported, so that a long portion of the kick shaft 55 is supported by the crankcase 14, and the support rigidity of the kick shaft 55 can be increased.

  Further, since the kick start mechanism 56 is disposed between the crankcase 14 and the drive pulley 46 in the direction along the axis of the crankshaft 13, the kick start mechanism 56 can be compactly disposed in the transmission case 12.

Also the kick starting mechanism 56, a driving gear 57 fixed to the kick shaft 5 5, a driven gear 58 which is movable in the axial direction of the crankshaft 13 depending on the power transmission from the drive gear 57,該被dynamic A drive side ratchet 59 that operates together with the gear 58 and a drive side ratchet 59 that can be engaged and disengaged in accordance with the movement of the drive side ratchet 59 in a direction along the axis of the crankshaft 13 can be engaged. And a driven ratchet 60 provided on the crankshaft 13 so as to rotate together with the crankshaft 13. The crankcase 13 is coaxially surrounded in the transmission case 12. A cylindrical support cylinder portion 21 a is provided, and an annular gap 6 is formed between the outer surface of the crankshaft 13. 9, the outer periphery of the driven gear 58 formed in a cylindrical shape is supported by the inner periphery of the support cylinder portion 21a so as to be rotatable and axially movable, so that the driven gear 58 is supported by the crankshaft 13. Thus, friction can be prevented from occurring between the crankshaft 13 and the driven gear 58.

Further, the drive pulley 46 is disposed between the fixed sheave 47 and the crankcase 14 so as to be fixed to the crankshaft 13 and supported by the crankshaft 13 so as to be able to move close to and away from the fixed sheave 47. A weight holding plate 52 that constitutes a part of a centrifugal shift mechanism 50 that serves to bring the movable sheave 48 close to the fixed sheave 47 in response to an increase in the rotational speed of the crankshaft 13. but wherein the fixed sheave 47 is fixed to the crank shaft 13 while facing the opposite side to the movable sheave 4 8, wherein the driven side ratchet 60, the weight as seen from a direction perpendicular to the axis of the crankshaft 13 Since it is arranged at a position overlapping with a part of the holding plate 52, the continuously variable transmission M and kick start rotation mechanism 56 can be arranged compactly in a direction along the axis of the crankshaft 13.

  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.

12 ... transmission case 13 ... crankshaft 14 ... crankcase 20, 21 ... crankcase half 21a ... support cylinder 44 ... case cover 46 ... drive pulley 54 ... · Kick lever 47 ··· fixed sheave 48 ··· movable sheave 50 ··· centrifugal shift mechanism 52 ··· weight holding plate 55 ··· kick shaft 56 · · · kick starting mechanism 57 · · · drive gear 58 ... Driven gear 59 ... Drive side ratchet 60 ... Driven side ratchet 63 ... Through hole 69 ... Annular gap E ... Internal combustion engine M ... Continuously variable transmission P ... Power unit

Claims (6)

A case cover having a V-belt type continuously variable transmission (M) having a drive pulley (46) provided on a crankshaft (13) of an internal combustion engine (E) covers the continuously variable transmission (M) from the outside. A kick lever (44), which is accommodated in a transmission case (12) connected to the crankcase (14) of the internal combustion engine (E) and disposed outside the case cover (44). 54) is fixed to the kick shaft (55) between the kick shaft (55) and the crankshaft (13) rotatably passing through the case cover (44) so as to be provided at the outer end. A gear (57), a driven gear (58) that can move in the axial direction of the crankshaft (13) in response to power transmission from the drive gear (57), and a drive side that operates with the driven gear (58) Ratchet (59) and the drive side ratchet (59) can be engaged and disengaged in accordance with the movement of the drive side ratchet (59) in the direction along the axis of the crankshaft (13). In a power unit in which a kick starting mechanism (56) having a driven ratchet (60) provided on the crankshaft (13) so as to rotate with the crankshaft (13) is interposed,
The crankcase (14) is formed by combining a pair of crankcase halves (20, 21) that can be divided in the axial direction of the crankshaft (13), and is provided with a through hole ( 63) A power unit characterized in that an inner end portion of the kick shaft (55) penetrating through 63) is rotatably supported by the pair of crankcase halves (20, 21) . A case cover having a V-belt type continuously variable transmission (M) having a drive pulley (46) provided on a crankshaft (13) of an internal combustion engine (E) covers the continuously variable transmission (M) from the outside. A kick lever (44), which is accommodated in a transmission case (12) connected to the crankcase (14) of the internal combustion engine (E) and disposed outside the case cover (44). 54) is fixed to the kick shaft (55) between the kick shaft (55) and the crankshaft (13) rotatably passing through the case cover (44) so as to be provided at the outer end. A gear (57), a driven gear (58) that can move in the axial direction of the crankshaft (13) in response to power transmission from the drive gear (57), and a drive side that operates with the driven gear (58) Ratchet (59) and the drive side ratchet (59) can be engaged and disengaged in accordance with the movement of the drive side ratchet (59) in the direction along the axis of the crankshaft (13). In a power unit in which a kick starting mechanism (56) having a driven ratchet (60) provided on the crankshaft (13) so as to rotate with the crankshaft (13) is interposed,
An inner end portion of the kick shaft (55) passing through a through hole (63) provided in the case cover (44) is rotatably supported by the crankcase (14), and the crankcase (14) A cylindrical support tube portion (21a) that surrounds the crankshaft (13) coaxially and enters the transmission case (12) is provided, and an annular gap (with an outer surface of the crankshaft (13)) is provided. 69), and the outer periphery of the driven gear (58) formed in a cylindrical shape is supported on the inner periphery of the support cylinder (21a) so as to be rotatable and axially movable. . A case cover having a V-belt type continuously variable transmission (M) having a drive pulley (46) provided on a crankshaft (13) of an internal combustion engine (E) covers the continuously variable transmission (M) from the outside. A kick lever (44), which is accommodated in a transmission case (12) connected to the crankcase (14) of the internal combustion engine (E) and disposed outside the case cover (44). 54) is fixed to the kick shaft (55) between the kick shaft (55) and the crankshaft (13) rotatably passing through the case cover (44) so as to be provided at the outer end. A gear (57), a driven gear (58) that can move in the axial direction of the crankshaft (13) in response to power transmission from the drive gear (57), and a drive side that operates with the driven gear (58) Ratchet (59) and the drive side ratchet (59) can be engaged and disengaged in accordance with the movement of the drive side ratchet (59) in the direction along the axis of the crankshaft (13). In a power unit in which a kick starting mechanism (56) having a driven ratchet (60) provided on the crankshaft (13) so as to rotate with the crankshaft (13) is interposed,
An inner end portion of the kick shaft (55) passing through a through hole (63) provided in the case cover (44) is rotatably supported by the crankcase (14), and the drive pulley (46) is A fixed sheave (47) fixed to the crankshaft (13), and the fixed sheave (47) and the crankcase ( 14) a movable sheave (48) disposed between, and a centrifugal type that works to bring the movable sheave (48) close to the fixed sheave (47) in response to an increase in the rotational speed of the crankshaft (13). A weight holding plate (52) constituting a part of the shift mechanism (50) faces the movable sheave (48) from the side opposite to the fixed sheave (47). One fixed to the crankshaft (13), and the driven ratchet (60) is disposed at a position overlapping a part of the weight holding plate (52) when viewed from a direction orthogonal to the axis of the crankshaft (13). Power unit characterized by being made . The crankcase (14) is provided with a cylindrical support tube portion (21a) that coaxially surrounds the crankshaft (13) and enters the transmission case (12), and the crankshaft (13) An outer periphery of the driven gear (58) formed in a cylindrical shape by forming an annular gap (69) between the outer surface and the outer surface is supported to be rotatable and axially movable on the inner periphery of the support cylinder portion (21a). The power unit according to claim 3 , wherein: The crankcase (14) is formed by combining a pair of crankcase halves (20, 21) that can be divided in the axial direction of the crankshaft (13), and the inner end of the kick shaft (55) is The power unit according to any one of claims 2 to 4, wherein the power unit is rotatably supported by a pair of crankcase halves (20, 21).   The kick start mechanism (56) is disposed between the crankcase (14) and the drive pulley (46) in a direction along the axis of the crankshaft (13). The power unit according to claim 1.

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