JP2009083665A - Power unit of small-sized vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a power unit of a small-sized vehicle which is easily kick-started, performing the oil lubrication of a kick force transmission mechanism with oil, reducing friction loss, and enhancing the durability. <P>SOLUTION: In the power unit of the small-sized vehicle, the power of a driven pulley shaft 80 is transmitted to an output shaft 25 via an intermediate shaft 101 and then transmitted to a rear wheel via a power transmission mechanism. The output shaft 25 is placed behind the driven pulley shaft 80, the intermediate shaft 101 is placed above the output shaft 25 and the driven pulley shaft 80, and a kick shaft 123 of a start-up kick arm 122 is placed below the driven pulley shaft 80 and parallel to a crankshaft 40. A kick force transmission mechanism 120 for transmitting the power of the kick shaft 123 to the crankshaft 40 is placed on the side opposite, in the vehicle lateral direction, to a belt-type continuously variable transmission 70. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a power unit for a small vehicle including a belt type continuously variable transmission and a kick starter.

  There is an example in which a kick starter is incorporated in a power unit having a belt type continuously variable transmission and mounted on a motorcycle (see, for example, Patent Document 1).

Noto 2513407

  The power unit disclosed in Patent Document 1 is fixedly supported on a body frame of a motorcycle, and the power of the output shaft of the power unit is transmitted to a rear wheel supported on the rear end of a rear fork via a chain. This is a motorcycle power unit.

  The belt type continuously variable transmission in the power unit is arranged on the left side in the vehicle width direction, the drive pulley is provided on the left side of the crankshaft, and the endless belt is bridged between the driven pulley arranged behind the drive pulley. An output shaft is disposed behind the driven pulley shaft, and an intermediate shaft disposed below the output shaft and the driven pulley shaft transmits the power of the driven pulley shaft to the output shaft.

  On the other hand, the kick shaft of the kicking starter arm of the kick starter is disposed in front of the driven pulley shaft, avoiding the lower side of the driven pulley shaft where the intermediate shaft is disposed, and the drive helical gear fitted to the kick shaft is Engaged with a driven helical gear coaxial with the driven pulley shaft, a ratchet mechanism is provided between the driven helical gear and the driven pulley shaft, and power is transmitted from the driven pulley shaft to the crankshaft via an endless belt to start the internal combustion engine. Executed.

  Therefore, the kick shaft is on the same left side as the belt-type continuously variable transmission in the vehicle width direction, and is pivotally supported by a transmission case cover that covers the belt-type continuously variable transmission from the left side, and a return spring is wound thereon.

The kick shaft disposed in front of the driven pulley shaft is substantially at the center in the front-rear direction of the power unit and is at the same height as the driven pulley shaft, avoiding an endless belt or the like.
Therefore, the kick pedal at the tip of the kick arm is at a high position in the front.

  Further, since the kick starter is disposed on the same left side as the belt type continuously variable transmission in the power unit, the gear of the kick starter is dry, so that it is difficult to lubricate with oil.

  The present invention has been made in view of the above points, and the intended process is that it is easy to perform a kick start operation, and the kick force transmission mechanism can be oil lubricated to reduce friction loss and improve durability. The power unit for small vehicles is provided.

  In order to achieve the above object, the invention according to claim 1 is an endless engine between an internal combustion engine having a crankshaft oriented in the vehicle body width direction and a drive pulley shaft and a driven pulley shaft that are coaxial or parallel to the crankshaft. A power unit that is integrally provided with a belt-type continuously variable transmission on which a belt-like belt is stretched and is supported by a body frame of a small vehicle, wherein the power of the driven pulley shaft is transmitted to an output shaft via an intermediate shaft. In a power unit of a small vehicle in which power is transmitted from the output shaft to a rear wheel via a power transmission mechanism, the output shaft is disposed behind the driven pulley shaft, and the intermediate shaft is the output shaft and the driven pulley. A kick shaft of a starting kick arm is disposed below the driven pulley shaft and parallel to the crankshaft, and transmits the power of the kick shaft to the crankshaft. Kick force transmission mechanism has a power unit for small vehicles disposed in the vehicle width direction opposite to the belt-type continuously variable transmission.

  According to a second aspect of the present invention, in the power unit of the small vehicle according to the first aspect, the body frame includes a main frame extending obliquely downward and rearward from the head pipe and a main frame, and a lower part from a rear portion of the main frame. And a pivot bracket that pivotally supports the rear fork so that the power unit is swingably supported. The power unit is suspended below the main frame and in front of the pivot bracket, and is formed by the main frame and the pivot bracket. The intermediate shaft is located at an inner corner of the bent portion.

  According to a third aspect of the present invention, in the power unit of the small vehicle according to the second aspect, the transmission case housing the belt-type continuously variable transmission is in a positional relationship so as not to overlap the main frame in a top view. And

  According to a fourth aspect of the present invention, in the power unit of the small vehicle according to any one of the first to third aspects, the kick force transmission mechanism includes a kick gear and a crankshaft provided coaxially with the kick shaft. A kick intermediate gear is interposed between the kick driven gear and the kick intermediate gear, a return spring is wound around the kick shaft, and a ratchet mechanism is provided on the kick intermediate shaft of the kick intermediate gear. To do.

According to a fifth aspect of the present invention, in the power unit of the small vehicle according to the fourth aspect, the vehicle body frame includes a main frame extending obliquely downward and rearward from the head pipe.
In the internal combustion engine, a cylinder head is largely inclined forward, an intake pipe extending upward from the cylinder head is disposed below the main frame, and a crankshaft is directed upward with respect to a cylinder central axis of the cylinder of the internal combustion engine. The kick intermediate shaft is offset and disposed below the crankshaft.

  According to a sixth aspect of the present invention, in the power unit of the small vehicle according to the fourth or fifth aspect, the kick pedal at the rotation tip of the starting kick arm is disposed outside the power unit in the vehicle width direction. It is characterized by.

  According to the power unit of the small vehicle according to claim 1, the kick shaft for starting is arranged using the space below the driven pulley shaft, the intermediate shaft being disposed above the output shaft behind the driven pulley shaft and the driven pulley shaft. Since the kick shaft is located at the lower rear side of the power unit, the kick pedal operation start position at the tip of the starting kick arm with the base end fitted to the kick shaft is located at the rear of the power unit. The driver is in a low position and can easily perform the starting operation with a natural posture by easily placing the foot on the kick pedal.

  In addition, since the operation start position of the kick pedal can be set to a low position behind the power unit, the degree of freedom of mounting the power unit on the vehicle body is improved and the center of gravity of the power unit can be kept low.

In addition, the kick force transmission mechanism that transmits the power of the kick shaft to the crankshaft is arranged on the opposite side of the belt-type continuously variable transmission, so that the kick force transmission mechanism is separated from the belt-type continuously variable transmission. As a result, oil lubrication can be achieved, and as a result, friction loss can be reduced to improve startability and to improve durability.
Furthermore, by providing the kick force transmission mechanism and the belt-type continuously variable transmission opposite to each other in the vehicle width direction, the left and right balance can be easily maintained.

  According to the power unit of the small vehicle according to claim 2, since the intermediate shaft is located above the output shaft and the driven pulley shaft at the inner corner of the connecting bent portion formed by the main frame and the pivot bracket, The rear upper part of the power unit is housed in the inner corner of the joint bend formed by the main frame and pivot bracket with the gap as small as possible, and as a result the stride when seated on the seat while raising the minimum ground clearance High maintainability.

  According to the power unit of the small vehicle according to claim 3, since the transmission case housing the belt-type continuously variable transmission is in a positional relationship so as not to overlap the main frame when viewed from above, the drive pulley of the belt-type continuously variable transmission In addition, the power unit can be brought closer to the main frame without causing the transmission case, which is bulky by the driven pulley, to interfere with the main frame, and as a result, the straddling performance can be further improved while raising the minimum ground clearance.

  According to the power unit of the small vehicle according to claim 4, since the return spring is wound around the kick shaft in the kick force transmission mechanism and the ratchet mechanism is provided on the kick intermediate shaft of the kick intermediate gear, the arrangement of the return spring and the ratchet mechanism And can be configured compactly in the axial direction, and the width of the power unit can be suppressed.

  According to the power unit of the small vehicle according to claim 5, the crankshaft is offset upward with respect to the cylinder center axis, and the kick intermediate shaft is disposed below the crankshaft, thereby narrowing the space for arranging the intake pipe. Since the kick intermediate shaft can be moved closer to the crank shaft in the front-rear direction, the degree of freedom of the arrangement of the kick shaft and the kick intermediate shaft is increased, and the power unit can be further downsized.

  According to the power unit of the small vehicle according to claim 6, since the kick pedal at the turning tip of the starting kick arm is disposed outside the power unit in the vehicle width direction, a wide space for placing the driver's feet is secured. it can.

Hereinafter, an embodiment according to the present invention will be described with reference to FIGS.
FIG. 1 is a side view of a motorcycle 1 according to an embodiment to which the present invention is applied.
The body frame of the motorcycle 1 is inclined obliquely downward from the upper part of the head pipe 2 of the entire body to extend one main frame 3, and a pair of left and right pivot brackets 4 are disposed at the rear of the main frame 3. 4 is fixed so as to extend downward.

A pair of left and right seat rails 5 and 5 extends rearward and obliquely upward from the front of the pivot position of the pivot brackets 4 and 4 at the rear of the main frame 3 and bend substantially horizontally in the middle to reach the rear end.
Middle frames 6 and 6 are interposed between the bent portions of the seat rails 5 and 5 and the pivot brackets 4 and 4.

A storage box 7 or the like is constructed between the pair of left and right seat rails 5 and 5 of the body frame as described above, and a seat 8 covers the storage box 7 and the like so as to be freely opened and closed.
A handle 9 is provided above and supported by the head pipe 2 at the front of the vehicle body, and a front fork 10 extends downward and a front wheel 11 is supported at the lower end thereof.

A rear fork 13 is pivotally supported by a pivot shaft 12 on the pivot brackets 4 and 4 at the center of the vehicle body and extends rearward. A rear wheel 14 is pivotally supported at a rear end portion of the rear fork 13.
Rear cushions 15, 15 are interposed between the rear portion of the rear fork 13 that swings up and down around the pivot shaft 12 and the seat rails 5, 5.

A power unit 20 is suspended below the main frame 3 and in front of the pivot brackets 4 and 4.
2 is a left side view of the power unit 20 and a part of the periphery thereof omitted, and FIG. 3 is a right side view of the power unit 20. Referring to FIGS. A support bracket 3a is suspended, and a mount bracket 20a protruding from the upper surface of the left and right unit cases 21L, 21R of the power unit 20 is suspended from the support bracket 3a via a support shaft 16, while the unit cases 21L, 21R A mount bracket 20b protruding from the upper rear surface is supported on the upper portion of the pivot bracket 4 by a support shaft 17, and a mount bracket 20c protruding from the lower rear surface of the unit cases 21L and 21R is supported on the lower portion of the pivot bracket 4 by the support shaft 18. As a result, the power unit 20 is positioned below the main frame 3 and in front of the pivot brackets 4, 4. It is fixed to and supported by the.

  Therefore, the motorcycle 1 is a saddle-ride type motorcycle having a main frame 3 above the power unit 20, and the body frame is covered with a synthetic resin cover member divided into various parts.

  In the power unit 20, an endless belt is bridged between a drive pulley shaft 51 and a driven pulley shaft 52, which are the crankshaft 40 and a coaxial integral shaft, with the internal combustion engine 30 with the crankshaft 40 oriented in the vehicle body width direction in the front half. The belt type continuously variable transmission 50 is integrated in the latter half.

The output shaft 25 of the power unit 20 protrudes leftward from the rear part of the left unit case 21L, and a drive sprocket 26 fitted to the output shaft 25 and a driven sprocket 27 provided integrally with the rear wheel 14 on the left side. The chain 28 is bridged between the two and the rotational power of the output shaft 25 is transmitted to the rear wheel 14 via the chain 28, and the rear wheel 14 rotates and travels.
The output shaft 25 is located somewhat forward by the pivot shaft 12 that supports the rear fork 13.
The chain 28 is covered with a chain cover 28C.

The internal combustion engine 30 is a single-cylinder four-cycle internal combustion engine, and has a posture in which the cylinder block 31, the cylinder head 32, and the cylinder head cover 33 are overlapped from the front surface of the unit cases 21L and 21R and are largely inclined to a substantially horizontal state. It protrudes.
A throttle body 35 is connected to an intake pipe 34 that extends upward from the upper intake port of the cylinder head 32.
An exhaust pipe 36 extending downward from the lower exhaust port of the cylinder head 32 and bent rearward is biased to the right and extends rearward and is connected to the right muffler 37 of the rear wheel 14.

4 is a sectional view taken along the line IV-IV in FIGS. 2 and 3 and developed.
Referring to FIG. 4, a crank chamber and a gear chamber are formed in an inner space formed by the combination of left and right unit case 21L and right unit case 21R, and oriented in the vehicle width direction (left and right direction). The disposed crankshaft 40 is rotatably supported by the left and right unit cases 21L and 21R via bearings 41L and 41R.

In the internal combustion engine 30, a connecting rod 43 connects a piston 42 that reciprocates in a cylinder liner 44 of a cylinder block 32 and a crank pin 40 a of a crankshaft 40.
The crankshaft 40 extends in the horizontal direction from left and right bearings 41L and 41R that support the shaft. A cam drive sprocket 54, a motor start driven gear 114, and an AC generator 60 are provided in the left extension 40L, and The extension portion 40R is provided with a kick start driven gear 136 and a belt drive pulley 71 of the belt type continuously variable transmission 70.

  The four-cycle internal combustion engine 30 employs an SOHC type valve system. A valve mechanism 50 is provided in the cylinder head cover 34, and a cam chain 51 that transmits drive to the valve mechanism 50 includes a camshaft 53. The cam chain chamber 52 is provided in communication with the left unit case 21L, the cylinder block 32, and the cylinder head 33.

That is, the cam chain driven sprocket 55 fitted to the left end of the cam shaft 53 oriented in the horizontal direction and the cam chain drive sprocket fitted adjacent to the left bearing 41L in the left extension 40L of the crankshaft 40. A cam chain 51 is passed between the cam chain chamber 52 and the cam chain chamber 52.
In the cylinder head 33, an ignition plug 45 is fitted obliquely from the opposite side (right side) of the cam chain chamber 52 toward the combustion chamber.

  A motor start driven gear 114 is rotatably supported on the left extension portion 40L of the crankshaft 40 on the left side of the cam chain drive sprocket 54, and the outer boss portion 61 of the AC generator 60 is fitted on the left side thereof. A one-way clutch 59 is interposed between the motor start driven gear 114 and the outer boss portion 61.

In the AC generator 60, a bowl-shaped outer rotor 62 is fixed to the outer boss portion 61, and a stator coil 65 is wound inside a magnet 63 disposed on the inner peripheral surface of the outer rotor 62 in the circumferential direction. A stator 64 is fixed to the central cylindrical portion 22 a on the inner surface of the ACG cover 22.
The crankshaft 40 extends leftward through an opening formed in the side wall of the left unit case 21L, an outer boss portion 61 is fitted in the vicinity of the left end portion thereof, and an outer rotor 62 is provided. The outer rotor 62 is covered and attached to the opening peripheral wall 21L (see FIG. 2) communicating with the cam chain chamber 52 on the side wall of the left unit case 21L.

  On the other hand, on the right side of the right unit case 21R, the transmission case 23 covers the right unit case 21R by forming a gear chamber 23a, and on the right side of the transmission case 23, the transmission case cover 24 is between the transmission case 23 and the right case 21R. Further, a transmission chamber 24a for accommodating the belt type continuously variable transmission 70 is formed and covered.

  A right extending portion 40R extending from the right bearing 41R of the crankshaft 40 passes through the transmission case 23 through the seal member 23b and protrudes into the transmission chamber 24a, and is formed between the right unit case 21R and the transmission case 23. In the gear chamber 23a, the kick start driven gear 136 is spline-fitted to the right extension 40R of the crankshaft 40, and the belt drive pulley 71 is connected to the crankshaft in the transmission chamber 24a between the transmission case 23 and the transmission case cover 24. Forty right extending portions 40R are provided so as to be integrally rotatable.

The belt drive pulley 71 includes a fixed pulley half 72 and a movable pulley half 73. The fixed pulley half 72 is integrally fixed in the vicinity of the right end of the crankshaft 40, and the movable pulley on the left side thereof. The half body 73 is supported by a sleeve 74 that is fitted to the crankshaft 40 and fixes a cam plate 76, which will be described later, through a copper bush so as to be slidable in the axial direction. The movable pulley half 73 rotates together with the crankshaft 40 and slides in the axial direction so that it can move toward and away from the fixed pulley half 72. A V-belt 75 is sandwiched between 72 and 73 and wound.
Therefore, the crankshaft 40 corresponds to a drive pulley shaft that supports the belt drive pulley 71.

A cam plate 76 is provided at a predetermined position near the seal member 23b on the left side of the movable pulley half 73, and a slide piece 76a provided on the outer peripheral end of the cam plate 76 extends axially toward the outer peripheral end of the movable pulley half 73. Is slidably engaged with the cam plate sliding boss portion 73a formed in FIG.
The side surface on the cam plate 76 side of the movable pulley half 73 is tapered toward the cam plate 76 side, and a dry weight roller 77 is accommodated between the cam plate 76 inside the tapered surface.

  Therefore, when the rotational speed of the crankshaft 40 increases, the dry weight roller 77 that rotates between the movable pulley half 73 and the cam plate 76 moves in the centrifugal direction due to centrifugal force, and the movable pulley half 73 moves in the same direction. Pressed by the weight roller 77 and moves to the right to approach the stationary pulley half 72 and move the V belt 75 sandwiched between the pulley halves 72 and 73 in the centrifugal direction to increase the winding diameter. It is configured as follows.

A rear belt driven pulley 83 corresponding to the belt driving pulley 71 is provided on a driven pulley shaft 80 disposed in parallel to a position near the front of the output shaft 25 behind the crankshaft 40 (corresponding to the driving pulley shaft). .
While the crankshaft 40 and the output shaft 25 are at substantially the same height, the driven pulley shaft 80 is at a slightly higher position (see FIGS. 2 and 3).

  The driven pulley shaft 80 is rotatably supported by bearings 78 and 79 at the rear and the rear of the right case 21R and the rear of the right case 21R. The driven pulley shaft 80 passes through the transmission case 23. The belt driven pulley 83 is supported by the portion protruding into the transmission chamber 24a.

A sleeve 81 fitted to the driven pulley shaft 80 from the right side is fastened to the inner race of the bearing 79 by fastening of the nut 82 and is fixed integrally with the driven pulley shaft 80. The fixed pulley half body 84 is fixed to the sleeve 81. The movable pulley half body 85 is supported by the sleeve 81 on the right side of the fixed pulley half body 84 through the annular slider 86 so that it can freely slide in the axial direction, and is attached to the left by the spring 87. It is energized.
The belt driven pulley 83 is composed of both pulley halves 84 and 85, and the V belt 75 is sandwiched between the pulley halves 84 and 85.

  Since the belt-type continuously variable transmission 70 is configured as described above, the power of the crankshaft (drive pulley shaft) 40 is transmitted to the driven pulley shaft 80 via the V-belt 75. As the rotational speed increases, the movable pulley half 73 approaches the fixed pulley half 72 due to the centrifugal movement of the dry weight roller 77, and the V belt 75 sandwiched between the pulley halves 72 and 73 By continuously increasing the winding diameter and decreasing the winding diameter of the V belt 75 sandwiched between the two pulley halves 84 and 85 on the driven pulley shaft 80, a continuously variable transmission is automatically performed.

A seal member 23c is interposed in the bearing opening of the transmission case 23 through which the driven pulley shaft 80 passes through the bearing 79.
Accordingly, the transmission chamber 24a in which the belt type continuously variable transmission 70 is accommodated is separated from the gear chamber 23a by the transmission case 23, and the opening communicating with the gear chamber 23a is sealed watertight by the seal members 23b and 23c. The oil in the gear chamber 23a is prevented from leaking into the transmission chamber 24a.

A centrifugal clutch 90 is provided on the driven pulley shaft 80 in the gear chamber 23a.
In the centrifugal clutch 90, an inner boss portion 92 that holds the base end of the clutch inner 91 is spline-fitted to the driven pulley shaft 80, and a plurality of supports protruding in parallel with the driven pulley shaft 80 on the outer peripheral end side of the clutch inner 91 are provided. Clutch weights 94 are pivotally supported on the shafts 93, respectively.
The clutch outer 95 has a cylindrical portion that covers the inner surface of the clutch weight 94 so that the inner peripheral surface thereof is opposed, and an outer boss portion 96 that holds the base end of the clutch outer 95 is rotatable relative to the driven pulley shaft 80 via a bearing 97. The clutch output gear 98 is supported by spline fitting.

  If the rotational speed of the driven pulley shaft 80 exceeds a predetermined speed, the tilting of the clutch weight 94 increases and acts on the clutch outer 95 to engage the clutch, causing the clutch outer 95 to rotate integrally with the clutch output gear 98.

A reduction gear mechanism 100 is provided between the driven pulley shaft 80 and the output shaft 25 behind it.
An intermediate shaft 101 is disposed above the driven pulley shaft 80 and the output shaft 25 and substantially above the output shaft 25 (see FIGS. 2 and 3).

  Referring to FIG. 4, the intermediate shaft 101 is rotatably supported by the left unit case 21 </ b> L and the right unit case 21 </ b> R via bearings 103 and 104, and a small diameter gear 105 is formed between the left and right bearings 103 and 104. The large-diameter gear 102 is attached to the right end protruding rightward from the right bearing 104 so as to be spline-fitted and rotated integrally, and the large-diameter gear 102 meshes with the clutch output gear 98.

  The output shaft 25 is rotatably supported by the left unit case 21L and the right unit case 21R via bearings 107 and 108, and a large-diameter gear 106 is fitted between the left and right bearings 107 and 108. 106 meshes with the small diameter gear 105 of the intermediate shaft 101.

  The reduction gear mechanism 100 is configured as described above, and the rotation of the clutch output gear 98 is reduced and transmitted to the intermediate shaft 101 by meshing with the large diameter gear 102, and the rotation of the intermediate shaft 101 is large with the small diameter gear 105. The drive sprocket 26 is transmitted at a reduced speed to the output shaft 25 by meshing with the diameter gear 106, and the drive sprocket 26 fitted to the left end protruding through the left unit case 21L of the output shaft 25 is rotated at a reduced speed. The reduced rotational power causes the rear wheel 14 to rotate via the chain 28 and cause the motorcycle 1 to travel.

  The power unit 20 supported by the main frame 3 and the pivot bracket 4 is disposed below the main frame 3 and in front of the pivot bracket 4. From the output shaft 25 and the driven pulley shaft 80 of the reduction gear mechanism 100 at the rear of the power unit 20. 2 and FIG. 3, the power unit is positioned so that the intermediate shaft 101 is positioned at the inner corner of the connecting bent portion formed as a normal dead space formed by the main frame 3 and the pivot bracket 4 as shown in FIGS. By arranging 20, the gap between the main frame 3 and the power unit 20 can be made as small as possible, and as a result, the minimum ground clearance can be raised.

The internal combustion engine 30 of the power unit 20 can be started in two ways: motor start by a starter motor 111 and kick start by stepping on a kick pedal.
Referring to FIG. 2, the opening peripheral wall 21La covering the AC generator 60 at the front of the left unit case 21L and covering the ACG cover 22 bulges upward, and the motor starting mechanism 110 is located in the vicinity of the opening peripheral wall 21La. Is configured.

A side wall is formed in the upward bulging portion of the opening peripheral wall 21La, and a starter motor 111 is attached to the side wall from the right side. A drive gear is provided on the drive shaft that protrudes leftward through the side wall of the starter motor 111. 112 is formed.
An intermediate shaft 113 is rotatably supported below the drive gear 112, a large-diameter gear 113a formed on the intermediate shaft 113 meshes with the drive gear 112, and a small-diameter gear 113b also formed on the intermediate shaft 113 It meshes with a large-diameter motor start driven gear 114 that is pivotally supported by the left extension 40L of the crankshaft 40.

  Therefore, the motor start mechanism 110 drives the starter motor 111 to decelerate and rotate the motor start driven gear 114 via the large diameter gear 113a and the small diameter gear 113b of the intermediate shaft 113, and the rotation of the motor start driven gear 114 is rotated in the one-way clutch. The crankshaft 40 can be forcibly driven to rotate via 59 and the outer boss portion 61 to start the internal combustion engine 30.

On the other hand, the kick start mechanism 120 is disposed below the unit cases 21L and 21R.
FIG. 5 is a cross-sectional view showing the kick start mechanism of the internal combustion engine 30 (cross-sectional view taken along the line VV in FIGS. 2 and 3).
2 and 5, a kick shaft 123 is disposed below the driven pulley shaft 80, and a base end portion of a starting kick arm 122 is fitted to the kick shaft 123.
A kick pedal 121 is attached to the tip of the kick arm 122 so as to be able to fall down.

  The rear half of the right unit case 21R protrudes to the left and approaches the left unit case 21L so that the space between the left and right unit cases 21L and 21R is narrow. The kick shaft 123 has a narrow left and right unit case 21L and 21R. Is pivotally supported by the shaft.

  The bearing portion 21Lb of the left unit case 21L has a thick cylindrical shape and bulges to the left, and the kick shaft 123 protrudes to the left through the bearing portion 21Lb. The worn kick arm 122 is positioned to the left of the pivot bracket 4 as well as the output shaft 25, and does not interfere with the pivot bracket 4 when the kick arm 122 swings.

  The right end of the kick shaft 123 is pivotally supported by a ridge-like bulged portion 21Rb to the right of the right unit case 21R, and a return spring 124 housed in the bulged portion is wound around the kick shaft 123. The return spring 124 biases the kick shaft 123 together with the kick arm 122 so as to rotate counterclockwise in FIG.

A stopper member 125 is spline-fitted to the kick shaft 123 toward the bearing portion 21Lb, and the protrusion 125a of the stopper member 125 abuts against the protrusion 21Lc of the left unit case 21L and is urged by the return spring 124. Is held at a predetermined rotation position (operation start position).
The kick arm 122 extends rearward and obliquely upward from the kick shaft 123 (see FIG. 2).

A large-diameter kick drive gear 126 is serrated between the return spring 124 of the kick shaft 123 and the stopper member 125.
A short first intermediate shaft 127 is rotatably supported by the left and right unit cases 21L and 21R having a small interval in front of the kick shaft 123, and a long second intermediate shaft 130 is further forward of the first intermediate shaft 127. Are rotatably supported by the left and right unit cases 21L and 21R and the transmission case 23, which are spaced apart from each other.

The kick shaft 123, the first intermediate shaft 127, and the second intermediate shaft 130 are all parallel to the crankshaft 40 and oriented in the horizontal direction, and the second intermediate shaft 130 is at a position obliquely below the crankshaft 40.
A small-diameter gear 128 is formed on the first intermediate shaft 127, and a large-diameter gear 129 is serration-fitted, and the small-diameter gear 128 meshes with the large-diameter kick drive gear 126.

The long second intermediate shaft 130 is pivotally supported at the left end by the left unit case 21L, the right end is pivotally supported by the transmission case 23, and the portion near the transmission case 23 from the center is pivoted by the right unit case 21R. It is supported.
A small diameter gear 131 is formed in the vicinity of the left end shaft support portion of the second intermediate shaft 130, and the small diameter gear 131 meshes with the large diameter gear 129.

  Helical external teeth 130h are formed on the outer peripheral surface of the right unit case 21R side between the right unit case 21R and the transmission case 23 of the second intermediate shaft 130. Helical inner teeth 132h carved on the inner peripheral surface mesh with the helical outer teeth 130h, and the driven helical gear 132 is combined.

Friction is applied to the rotation of the driven helical gear 132 by fitting and tightening a ring portion 133a partially missing of the friction spring 133 in a groove formed on the outer peripheral surface of the driven helical gear 132 in the circumferential direction. ing.
The tip of the handle portion 133b extending in the centrifugal direction from the annular portion 133a of the friction spring 133 is slidably fitted into a groove 21Rv formed in the right unit case 21R and oriented in the left-right direction. is doing.

Ratchet teeth 132r project from the right side surface of the driven helical gear 132 along the periphery.
A large-diameter gear 134 is rotatably supported by the second intermediate shaft 130 on the right side of the driven helical gear 132, and the large-diameter gear 134 is spline-fitted to the crankshaft 40. Engage with gear 136.
The large-diameter gear 134 is formed with a ratchet mechanism 135 having a left side surface opposed to the ratchet teeth 132r of the driven helical gear 132 and capable of meshing with the ratchet teeth 134r.

  The kick start mechanism 120 is configured as described above. When the kick pedal 121 is depressed and the kick shaft 123 rotates against the return spring 124, the kick start gear 120 is integrated with the kick shaft 123 and has a large-diameter kick drive gear. 126 rotates, the first intermediate shaft 127 rotates at an increased speed by meshing the kick drive gear 126 and the small diameter gear 128, and the large diameter gear 129 that rotates integrally with the first intermediate shaft 127 is the second intermediate shaft 130. The second intermediate shaft 130 is further rotated at a higher speed.

  When the second intermediate shaft 130 rotates, the driven helical gear 132 in which the helical inner teeth 132h mesh with the helical outer teeth 130h that rotate integrally is caused to generate frictional resistance against rotation by the friction spring 133, thereby preventing rotation. The driven helical gear 132 moves in the axial direction (right direction), and its ratchet teeth 132r mesh with the ratchet teeth 134r of the large-diameter gear 134, and is substantially integrated with the second intermediate shaft 130 against the resistance of the friction spring 133. The large-diameter gear 134 rotates together with the rotating driven helical gear 132, and the crankshaft 40 is forcibly rotated by the meshing of the large-diameter gear 134 and the kick start driven gear 136 to start the internal combustion engine 30.

  When stepping on the kick pedal 121 is stopped and the kick pedal 121 is released, the kick shaft 123 is returned to the original operation start position together with the kick arm 122 by the return spring 124. Therefore, the first intermediate shaft 127 and the second intermediate shaft 130 are The reverse rotation causes the driven helical gear 132 to move to the left by the meshing of the helical teeth 132h and 130h, and the engagement of the ratchet teeth 132r and 134r is released.

  The meshing of the gears between the kick shaft 123, the first intermediate shaft 127 and the second intermediate shaft 130 including the kick pedal 121 and the kick arm 122, which are the main kick force transmission mechanisms of the kick starting mechanism 110, is as shown in FIG. Further, it is disposed on the left side of the cylinder center axis C, and is provided opposite to the belt type continuously variable transmission 70 disposed on the right side of the cylinder center axis C. Therefore, the kick force transmission mechanism is provided. Oil lubrication can be performed away from the dry belt-type continuously variable transmission 70. As a result, friction loss can be reduced to improve startability and to improve durability.

  Furthermore, since the main kick force transmission mechanism of the kick start mechanism 110 and the belt-type continuously variable transmission 70 are provided opposite to the vehicle width direction, the left and right balance of the power unit 20 can be easily maintained.

  The power unit 20 of the motorcycle has a driven pulley shaft 80 of the belt-type continuously variable transmission 70 and an intermediate shaft 101 disposed above the output shaft 25 behind the driven pulley shaft 80 and below the driven pulley shaft 80. Since the kick shaft 123 is arranged using the space of the kick shaft 123, the kick shaft 123 can be positioned at the lower rear side of the power unit 20, and the start end of the starting kick arm 122 with the base end portion fitted to the kick shaft 123 The operation start position of the kick pedal 121 becomes a low position behind the power unit 20, so that the driver does not have to raise his / her foot greatly and can easily put the foot on the kick pedal 121 and perform the start operation easily Can do.

  Since the operation start position of the kick pedal 121 can be set at a low position behind the power unit 20, the degree of freedom of mounting the power unit 20 on the vehicle body is improved and the center of gravity of the power unit 20 can be kept low.

  Since the power unit 20 is arranged so that the intermediate shaft 101 is located above the output shaft 25 and the driven pulley shaft 80 at the inner corner of the connecting bent portion formed by the main frame 3 and the pivot bracket 4, The power unit 20 can be brought close to the main frame 3 so that the gap between the two can be as small as possible. As a result, the minimum ground clearance can be increased and the strideability when the seat 8 is seated can be maintained high.

  A return spring 124 is wound around the kick shaft 123 in the kick force transmission mechanism of the kick start mechanism 110, and a helical gear 132 driven by a small intermediate gear 131 of the kick intermediate gear and a second intermediate shaft 130 which is a kick intermediate shaft of the large gear 134, and Since the ratchet mechanism 135 including the ratchet teeth 132r, 134r, etc. is provided, the arrangement of the return spring 124 and the ratchet mechanism 135 can be divided into a compact configuration in the axial direction, and the lateral width (left-right width) of the power unit 20 can be suppressed. Can do.

  Since the kick pedal 121 at the rotation tip of the start kick arm 122 is disposed outside the power unit 20 in the vehicle width direction, a wide space for placing the driver's feet can be secured.

  Further, one main frame 3 extending rearward from the head pipe 2 in the center in the vehicle body width direction is on the cylinder axis at the center of the power unit 20 as shown by a two-dot chain line in FIG. The transmission case 23, which is a transmission case for housing the machine 70, is located on the right side of the central main frame 3 in a top view and does not overlap the main frame 3, so that the belt-type continuously variable transmission 70 The power unit 20 can be brought closer to the main frame 3 without interfering with the main frame 3 by the belt drive pulley 71 and the belt driven pulley 83 so as to interfere with the main frame 3, and as a result, the straddle is further improved while raising the minimum ground clearance. be able to.

  2 and 3, the crankshaft 40 is offset upward with respect to the cylinder center axis C, and the kick intermediate shafts 127 and 130 are disposed below the crankshaft 40. Since the kick intermediate shafts 127 and 130 can be brought closer to the crankshaft 40 in the front-rear direction without narrowing the arrangement space, the degree of freedom of the arrangement of the kick shaft 123 and the kick intermediate shafts 127 and 130 is increased. This can contribute to downsizing.

1 is a side view of a motorcycle according to an embodiment to which the present invention is applied. It is the left view which abbreviate | omitted the power unit and its periphery partially. It is the same right view. FIG. 4 is a cross-sectional view taken along line IV-IV in FIGS. 2 and 3. FIG. 4 is a cross-sectional view taken along line VV in FIGS. 2 and 3 and developed.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Motorcycle, 2 ... Head pipe, 3 ... Main frame, 4 ... Pivot bracket, 11 ... Front wheel, 12 ... Pivot shaft, 13 ... Rear fork, 14 ... Rear wheel,
20 ... Power unit, 21L ... Left unit case, 21R ... Right unit case, 22 ... ACG cover, 23 ... Transmission case, 24 ... Transmission case cover, 25 ... Output shaft,
30 ... Internal combustion engine, 40 ... Crankshaft, 50 ... Valve mechanism, 60 ... AC generator,
70 ... belt type continuously variable transmission, 71 ... belt drive pulley, 75 ... V belt, 80 ... driven pulley shaft, 83 ... belt driven pulley, 90 ... centrifugal clutch, 100 ... reduction gear mechanism, 101 ... intermediate shaft,
120 ... kick start mechanism, 121 ... kick pedal, 122 ... kick arm, 123 ... kick shaft, 124 ... return spring, 126 ... kick drive gear, 127 ... first intermediate shaft, 130 ... second intermediate shaft, 132 ... driven helical gear 133 ... Friction spring, 134 ... Large gear, 135 ... Ratchet mechanism, 136 ... Kick start driven gear.

Claims (6)

An internal combustion engine with the crankshaft oriented in the vehicle body width direction and a belt-type continuously variable transmission in which an endless belt is bridged between a drive pulley shaft and a driven pulley shaft that are coaxial or parallel to the crankshaft A power unit supported by a body frame of a small vehicle in preparation for
The power of the driven pulley shaft is transmitted to the output shaft through the intermediate shaft,
In a power unit of a small vehicle in which power is transmitted from the output shaft to a rear wheel via a power transmission mechanism,
The output shaft is disposed behind the driven pulley shaft;
The intermediate shaft is disposed above the output shaft and the driven pulley shaft;
The kick shaft of the starting kick arm is disposed below the driven pulley shaft in parallel with the crank shaft,
A power unit for a small vehicle, characterized in that a kick force transmission mechanism for transmitting the power of the kick shaft to the crank shaft is disposed on the opposite side to the belt-type continuously variable transmission in the vehicle width direction. The vehicle body frame includes a head pipe, a main frame extending obliquely downward and downward from the head pipe, and a pivot bracket extending downward from a rear portion of the main frame and pivotally supporting a rear fork.
The power unit is suspended below the main frame and in front of the pivot bracket, and the intermediate shaft is located at an inner corner of a connecting bent portion formed by the main frame and the pivot bracket. Item 2. A power unit for a small vehicle according to Item 1.   The power unit for a small vehicle according to claim 2, wherein a transmission case housing the belt-type continuously variable transmission is in a positional relationship so as not to overlap the main frame when viewed from above.   The kick force transmission mechanism includes a kick intermediate gear interposed between a kick gear provided coaxially with the kick shaft and a kick driven gear provided coaxially with the crank shaft, and a return spring is wound around the kick shaft. The power unit for a small vehicle according to any one of claims 1 to 3, wherein a ratchet mechanism is provided on the kick intermediate shaft of the kick intermediate gear. The vehicle body frame includes a main frame extending obliquely rearward and downward from the head pipe,
In the internal combustion engine, the cylinder head is greatly inclined forward,
An intake pipe extending upward from the cylinder head is disposed below the main frame;
The crankshaft is offset upward with respect to the cylinder center axis of the cylinder of the internal combustion engine,
The power unit of the small vehicle according to claim 4, wherein the kick intermediate shaft is disposed below the crankshaft.   6. The power unit for a small vehicle according to claim 4, wherein a kick pedal at a rotation tip of the starting kick arm is disposed outside the power unit in the vehicle width direction.

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