WO2009119207A1

WO2009119207A1 - Power unit for vehicle

Info

Publication number: WO2009119207A1
Application number: PCT/JP2009/052984
Authority: WO
Inventors: 親司滝口
Original assignee: 本田技研工業株式会社
Priority date: 2008-03-25
Filing date: 2009-02-20
Publication date: 2009-10-01
Also published as: AR070725A1; TW200949104A; JP2009236128A; JP5145095B2; TWI367998B

Abstract

A power unit for a vehicle, having crankcases (25L, 25R) for housing a crankshaft (65), a belt type stepless transmission (23), and a transmission case (63) having an air path (115) for sucking air therein for cooling the stepless transmission (23), wherein the crankshaft (65) is mounted on the vehicle so as to be oriented in the vehicle's lateral direction. The power unit has an air discharge structure provided with an air discharge path (124) and an air discharge exit (136) which are adapted for cooling air and through which water and dust are less likely to enter into the stepless transmission (23). The transmission case (63) has an outer transmission case (63B) for covering the stepless transmission (23) from the outside in the vehicle's lateral direction and also has an inner transmission case (63A) for covering the stepless transmission (23) from the inside in the vehicle's lateral direction. The inner transmission case (63A) is provided with an entrance (123) for the air discharge path (124) for discharging cooling air sucked into the transmission case (63), and the air discharge path (124) is located in the upper parts of the crankcases (25L, 25R) so as to be oriented in the substantially vehicle's lateral direction. A downwardly directed section (135) is formed in that side face of the crankcase (25L) which is on the side opposite the stepless transmission (23).

Description

Vehicle power unit

The present invention relates to a power unit of a vehicle having a belt type continuously variable transmission cooling air exhaust structure.

In a vehicle power unit in which a belt type continuously variable transmission is arranged on one side of the crankshaft in the transmission case, the cooling air inlet of the belt type continuously variable transmission is arranged on the belt type continuously variable transmission side of the transmission case. The cooling air discharge port is opened in the lower part of the transmission case opposite to the belt type continuously variable transmission, and the cooling air passage connecting the cooling air introduction port and the cooling air discharge port is provided in the lower part of the transmission case. A continuously variable transmission cooling structure is known (for example, see Patent Document 1). Since the cooling air passage and the cooling air discharge port are provided in the lower part of the transmission case, there is a problem that water and dust easily enter here, and in particular, when water enters the belt type continuously variable transmission, Life may be shortened.

Japanese Patent Publication No. 61-40864 (FIGS. 4 and 5)

The present invention seeks to provide a power unit for a vehicle having a belt-type continuously variable transmission exhaust structure provided with a cooling-air exhaust passage and an exhaust outlet that prevent water and dust from entering the belt-type continuously variable transmission. Is.

In order to solve the above problems, the present invention provides a crankcase that houses a crankshaft of an internal combustion engine, a drive pulley shaft and a driven pulley shaft that are driven by the crankshaft in parallel with the crankshaft of the internal combustion engine, and both A belt-type continuously variable transmission having a belt wound between pulleys provided on a pulley shaft, and the above-described belt-type continuously variable transmission, and cooling air for cooling the belt-type continuously variable transmission. And a transmission case provided on one side of the crankshaft. The transmission case is a part of the transmission case and is an outer side that covers the belt-type continuously variable transmission from the outside in the vehicle width direction. The transmission case and the other part of the transmission case, which is attached to the crankcase, covers the belt type continuously variable transmission from the inside in the vehicle width direction, and forms the transmission case together with the outer transmission case. A power unit for a vehicle mounted on the vehicle so that the crankshaft faces in the vehicle width direction, and the cooling air that is provided in the inner transmission case and sucked into the transmission case is An exhaust passage entrance for exhausting air, an exhaust passage communicating with the exhaust passage entrance and provided substantially in the vehicle width direction at the upper portion of the crankcase, and a side surface of the crankcase opposite to the transmission A vehicle power unit comprising: a downward portion of an exhaust passage provided continuously to the exhaust passage.

In the vehicle power unit, the exhaust passage can be formed integrally with the crankcase.

Preferably, the power unit of the vehicle includes a generator at the end of the crankshaft opposite to the pulley of the drive pulley shaft, and drives the rear wheel of the vehicle by using the power of the driven shaft pulley disposed behind the drive pulley. Means for transmitting to the output shaft of the power unit, and the downward portion of the exhaust passage is between the generator housing portion that houses the generator and the output shaft housing portion that covers the output shaft from the outside in a top view. It is arrange | positioned at the recessed part which can be made.

An oil inlet for lubricating oil to be supplied to the crankcase can be provided in the vicinity of the outlet of the downward portion of the exhaust passage.

The downward portion of the exhaust passage can be formed by a rib extending from the outer side surface of the crankcase to the outside in the vehicle width direction and a cover that covers the rib from the outside.

Preferably, the downward portion cover of the exhaust passage constitutes an output shaft cover that covers the power unit output shaft from the outside in the vehicle width direction.

The peripheral wall of the air exhaust passage can constitute a reinforcing wall for the power unit hanger boss.

According to the present invention, the exhaust passage of the belt-type continuously variable transmission is passed through the upper part of the crankcase, and the exhaust passage downward portion is disposed on the side surface opposite to the transmission of the crankcase. It is possible to effectively prevent dust and water from entering the transmission case.

When the exhaust passage is manufactured integrally with the crankcase, the number of parts can be reduced.

The power unit is disposed by the downward portion of the exhaust passage being disposed in a recess formed between the generator housing portion that houses the generator in top view and the output shaft housing portion that covers the output shaft from the outside. The power unit can be made compact without projecting in the vehicle width direction.

If the oil inlet is disposed in the concave portion of the downward portion of the exhaust passage, the power unit member does not protrude in the vehicle width direction.

When the downward portion of the exhaust passage is formed by a rib extending outward in the vehicle width direction from the outer side surface of the crankcase and a cover that covers the rib from the outside, the downward portion of the exhaust passage is protected. .

If the cover of the downward section of the exhaust passage constitutes an output shaft cover that covers the power unit output shaft from the outside in the vehicle width direction, the number of parts can be reduced.

The power unit hanger boss is reinforced by making the peripheral wall of the exhaust passage constitute a reinforcing wall of the power unit hanger boss.

1 is a side view of a motorcycle 1 according to an embodiment of the present invention. It is the side view which looked at the above-mentioned power unit from the right side. FIG. 3 is a developed sectional view taken along the line III-III in FIG. 2. FIG. 4 is a developed sectional view taken along the line IV-IV in FIG. 2. It is the figure which looked at the longitudinal cross-section which cut the outer side transmission case between the outer wall and the baffle plate from the right. It is the figure which looked at the left side fitting surface of the said outside transmission case, and the inside of a transmission chamber from the left. It is the figure which looked at the right side surface of an inner side transmission case, and the inside of a transmission chamber from the right side. It is a figure which shows the inside of the right surface of a right crankcase and a centrifugal clutch chamber. It is a figure which shows the inside of the right surface of a left crankcase, a crank chamber, a reduction gear chamber, and a kick start mechanism gear chamber. It is a left view of a left crankcase. It is XI-XI sectional drawing of FIG.

Explanation of symbols

23 ... Belt type continuously variable transmission, 24 ... Reduction gear mechanism, 25 ... Crankcase, 25L ... Left crankcase, 25R ... Right crankcase, 40 ... Drive pulley, 41 ... Driven pulley, 42 ... V belt, 43 ... Wet Centrifugal clutch, 62 ... generator cover, 63 ... transmission case, 63A ... inner transmission case, 63B ... outer transmission case, 65 ... crank chamber, 66 ... reduction gear chamber, 67 ... generator chamber, 71 ... centrifugal clutch , 72 ... Air guide plate, 73 ... Transmission room, 74 ... Air guide room, 95 ... Kick start mechanism gear chamber, 115 ... First air passage, 116 ... Second air passage, 117 ... Driven pulley shaft through hole, 121 ... Cooling air, 122 ... Foot step, 123 ... Exhaust passage inlet, 124 ... Exhaust passage, 127 ... Lubricating oil inlet, 130 ... Exhaust guide rib, 131 ... Output shaft protection rib, 132 ... Rear power unit cover 133 ... Lubrication cap, 134 ... Generator housing, 135 ... Downward passage of the exhaust passage, 136 ... Exhaust outlet.

FIG. 1 is a side view of a motorcycle 1 having a power unit 20 of the present invention. In the motorcycle 1, the vehicle body frame 2 includes a head pipe 3 at the front of the vehicle body, a single main frame 4 that extends obliquely downward from the head pipe 3 and a rear portion of the main frame 4. A pair of left and

right pivot brackets

5 and 5 that are fixedly extended downward and the rear part of the main frame 4 are extended obliquely upward from the front of the fixed position of the

pivot brackets

5 and 5 to the rear and bent in the middle. And a pair of left and right seat rails 6, 6 reaching the rear end, and

middle frames

7, 7 interposed between the

pivot brackets

5, 5 and the central portion of the seat rails 6, 6. ing.

A riding seat 8 is provided above the pair of left and right seat rails 6, 6 of the body frame 2, and a lower portion is a storage portion 9. A handle 10 pivotally supported by the head pipe 3 is provided above the front of the vehicle body. A front fork 11 extends below the handle 10 and a front wheel 12 is pivotally supported at the lower end thereof. A pivotal shaft 13 pivotally supports a rear fork 14 pivotably on the

pivot brackets

5 and 5 at the center of the vehicle body and extends rearward. A rear wheel 15 is pivotally supported at the rear end of the rear fork 14. . Rear cushions 16 and 16 are interposed between the rear portion of the rear fork 14 and the seat rails 6 and 6.

The power unit 20 is suspended below the main frame 4 and in front of the

pivot brackets

5 and 5. The upper part of the power unit 20 is suspended from

support brackets

17 and 17 suspended from the center of the main frame 4, and the rear part of the power unit 20 is fixed to the

pivot brackets

5 and 5 at two locations. The body frame 2 is covered with a synthetic resin body cover 18 divided into various parts.

The power unit 20 includes a front internal combustion engine 21 and a rear power transmission device 22. The internal combustion engine 21 is a single-cylinder four-cycle internal combustion engine, and the cylinder portion protrudes from the front surface of the crankcase 25 to a substantially horizontal state in a posture that is largely inclined forward. A throttle body 27 and an internal combustion engine intake air cleaner 28 are connected to an intake pipe 26 extending above the internal combustion engine 21. Further, an exhaust pipe 29 extending downward and bent rearward of the internal combustion engine 21 extends rearward and is connected to a muffler 30 on the right side of the rear wheel 15. A power transmission chain 34 is bridged between a power transmission chain drive sprocket 32 fitted to the output shaft 31 of the power unit 20 and a power transmission chain driven sprocket 33 provided integrally with the rear wheel 15, and the rear wheel 15 Is driven. A footrest step 122 for the driver is provided from the lower part of the power unit 20 to both sides. A lubricating oil filling port 127 (FIG. 11) is provided on the left side surface of the power unit 20 inside the footrest step 122, and a lid 133 for the filling port is visible.

FIG. 2 is a side view of the power transmission device 22 of the power unit 20 as viewed from the right side, and shows the positions of the main rotary shaft, pulleys, and gears of the power transmission device 22 as viewed from the side. A cylinder axis 141 is also shown. A crankshaft 37 of the internal combustion engine 21 is provided at the front portion of the crankcase 25. A right extension of the crankshaft 37 is a drive pulley shaft 38 of the belt type continuously variable transmission 23. The driven pulley shaft 39 of the belt type continuously variable transmission 23 is provided at the rear portion of the crankcase 25. A driving pulley 40 is provided on the driving pulley shaft 38, a driven pulley 41 is provided on the driven pulley shaft 39, and a V-belt 42 is wound around these pulleys.

A wet centrifugal clutch 43 having the same diameter as that of the driven pulley 41 of the driven pulley shaft 39 of the belt type continuously variable transmission 23 is provided. The reduction gear mechanism 24 includes a centrifugal clutch output gear 76, a reduction gear mechanism intermediate shaft 45, and a gear group provided on the power unit output shaft 31.

In FIG. 2, a kick start mechanism 46 is shown below the crankcase 25. The kick start mechanism 46 includes a gear group provided on a kick shaft 47 having a kick arm, a first intermediate shaft 48, and a second intermediate shaft 49, and a kick start mechanism driven gear 50 provided on the crank shaft 37. It is prepared for. An oil pump 125 is provided obliquely in front of the crankshaft 37. A starter motor 108 is provided above the front part of the crankcase.

FIG. 3 is a developed sectional view taken along the line III-III in FIG. A cylinder block 53, a cylinder head 54, and a cylinder head cover 55 are sequentially provided in front of the crankcase 25. A piston 56 that reciprocates in the cylinder bore 53 a of the cylinder block 53 is connected to the crankshaft 37 by a connecting rod 57.

This internal combustion engine 21 employs an SOHC type valve system, and a valve mechanism 58 is provided in the cylinder head cover 55 and is driven by a crankshaft 37 via a cam chain 59. A combustion chamber 60 is formed on the end face of the cylinder head 54 on the cylinder block 53 side, and a spark plug 61 is fitted from the right outer side of the cylinder head 54.

The shell of the power transmission device 22 of the power unit 20 includes a left crankcase 25L and a right crankcase 25R constituting the crankcase 25, a generator cover 62 provided on the left side of the left crankcase 25L, and a right crankcase 25R. It consists of an inner transmission case 63A and an outer transmission case 63B that constitute a transmission case 63 provided on the right side of this. These cases and covers are castings.

A crank chamber 65 and a reduction gear chamber 66 communicating with the crank chamber 65 are formed in the inner space of the crankcase 25. The crankshaft 37 is oriented in the vehicle width direction (left-right direction), and is rotatably supported by the left and

right crankcases

25L and 25R via bearings. A part of the gear train of the reduction gear mechanism 24 is accommodated in the reduction gear chamber 66.

A generator chamber 67 is provided between the left crankcase 25L and the generator cover 62. A crankshaft 37 extending to the crankcase 37 extends to a cam chain drive sprocket 68, a motor start mechanism driven gear 69, and an AC generator. 70 is provided.

A centrifugal clutch chamber 71 is provided between the right crankcase 25R and the inner transmission case 63A. A transmission chamber 73 and a baffle chamber 74 separated by a baffle plate 72 are provided in a transmission case 63 formed by the inner transmission case 63A and the outer transmission case 63B. The right portion of the crankshaft 37 extends to the centrifugal clutch chamber 71, and the tip further extends to the transmission chamber 73 through the opening seal member 75 of the inner transmission case 63A. A portion of the crankshaft 37 extending to the centrifugal clutch chamber 71 is provided with a kick start mechanism driven gear 50 by spline fitting. A portion of the crankshaft 37 extending to the transmission chamber 73 is a drive pulley shaft 38 of the belt-type continuously variable transmission 23, and a drive pulley 40 of the belt-type continuously variable transmission 23 is provided integrally therewith. is there.

The driven pulley shaft 39 of the belt type continuously variable transmission 23 is provided behind the drive pulley shaft 38, and is supported by the right crankcase 25R and the inner transmission case 63A via bearings. A driven pulley 41 of the belt type continuously variable transmission 23 is provided in a portion of the driven pulley shaft 39 in the transmission chamber 73. A wet centrifugal clutch 43 and a clutch output gear 76 are provided in a portion of the driven pulley shaft 39 in the centrifugal clutch chamber 71. A bearing seal member 77 is interposed in the bearing opening of the inner transmission case 63A through which the driven pulley shaft 39 passes through the bearing.

The drive pulley 40 of the belt type continuously variable transmission 23 includes a fixed half body 78 and a movable half body 79.
The movable half 79 rotates with the driving pulley shaft 38 and slides in the axial direction by the action of a weight roller 80 that moves in the centrifugal direction due to centrifugal force, and approaches or separates from the fixed half 78. , 79, the winding diameter of the V belt 42 sandwiched between them is changed.

The driven pulley 41 of the belt-type continuously variable transmission 23 includes a fixed half 81 and a movable half 82. On the right side of the fixed half 81, a movable half 82 is supported by the sleeve 84 through an annular slider 83 so as to be slidable in the axial direction, and is biased to the left by a coil spring 85. When the winding diameter of the V belt 42 sandwiched between the two

halves

78 and 79 of the drive pulley 40 increases, the distance between the halves 81 and 82 of the driven pulley 41 resists the biasing force of the coil spring 85. As a result, the winding diameter of the V-belt 42 is reduced, and a continuously variable transmission is automatically performed.

The wet centrifugal clutch 43 is provided on the left side of the driven pulley shaft 39 in the centrifugal clutch chamber 71. In the wet centrifugal clutch 43, the center portion of the clutch inner 87 is spline-fitted to the driven pulley shaft 39, and the clutch weights 89 are rotatable on a plurality of support shafts 88 protruding from the outer peripheral end side of the clutch inner 87. It is pivotally supported.

The clutch output gear 76 is supported on the left end portion of the driven pulley shaft 39 through a needle bearing so as to be relatively rotatable, and the center portion of the clutch outer 90 is fixed to the boss portion of the clutch output gear 76. When the rotational speed of the driven pulley shaft 39 exceeds a predetermined speed, the clutch weight 89 is engaged with the clutch outer 90, the clutch outer 90 is rotated, and the clutch output gear 76 is also rotated.

The reduction gear mechanism 24 is provided between the driven pulley shaft 39 of the belt type continuously variable transmission 23 and the power unit output shaft 31 behind the pulley shaft 39. The reduction gear mechanism intermediate shaft 45 is supported by the left and

right crankcases

25L and 25R via bearings, and an intermediate shaft large-diameter gear 91 is fitted in a portion of the centrifugal clutch chamber 71 and meshed with the clutch output gear 76. ing. An intermediate shaft small-diameter gear 92 is cut in a portion of the intermediate shaft 45 in the reduction gear chamber 66.

The power unit output shaft 31 is supported on the left and

right crankcases

25L and 25R via bearings, and an output shaft large-diameter gear 93 is fitted in a portion of the reduction gear chamber 66, and the reduction gear mechanism intermediate shaft 45 has a small diameter. The gear 92 is engaged. A power transmission chain drive sprocket 32 is fitted on a portion of the power unit output shaft 31 that extends to the left of the left crankcase 25L, and a power transmission chain 34 is wound around. The rotation of the clutch output gear 76 is reduced and transmitted to the power unit output shaft 31 through the reduction gear mechanism intermediate shaft 45, and is fitted to the left end of the power unit output shaft 31 and the power transmission chain drive sprocket 32 and the power transmission chain 34 (see FIG. It is transmitted to the rear wheel 15 via 1).

In FIG. 2, the kick start mechanism 46 is provided below the crankshaft 37 and the wet centrifugal clutch 43. The kick shaft 47 is disposed below the driven pulley shaft 39 of the belt type continuously variable transmission 23.

FIG. 4 is a sectional development view taken along the line IV-IV in FIG. The kick shaft 47 is pivotally supported by the left and

right crankcases

25L and 25R, and is provided in the kick start mechanism gear chamber 95. The kick start mechanism gear chamber 95 communicates with the crank chamber 65. The left end of the kick shaft 47 penetrates the thick cylindrical bearing portion 96 of the left crankcase 25L and protrudes to the left. A base end portion of a starting kick arm 98 is fitted to the protruding portion of the kick shaft 47, and a kick pedal 106 is provided at the distal end portion of the kick arm 98. The right end of the kick shaft 47 is pivotally supported by the right crankcase 25R, and a return spring 97 accommodated therein is wound around the kick shaft 47, and the kick shaft 47 rotates together with the kick arm 98 to the operation start position. It is energized to do. A stopper member 99 that holds the kick arm 98 biased by the return spring 97 at a predetermined operation start position is provided at the right end of the kick shaft 47.

A large-diameter kick drive gear 100 is spline-fitted to the kick shaft 47 adjacent to the bearing portion 96. A first intermediate shaft 48 is rotatably supported by the left and

right crankcases

25L and 25R in front of the kick shaft 47. The first intermediate shaft 48 is cut with a first intermediate shaft small-diameter gear 101 and a first intermediate shaft large-diameter gear 102 is spline-fitted. The first intermediate shaft small-diameter gear 101 is a kick drive gear 100. Is engaged.

A second intermediate shaft 49 is rotatably supported by the left and

right crankcases

25L and 25R and the inner transmission case 63A in front of the first intermediate shaft 48. Since the second intermediate shaft 49 penetrates the right crankcase 25R, the second intermediate shaft 49 is provided across the crank chamber 65 and the centrifugal clutch chamber 71. A second intermediate shaft small diameter gear 103 is formed in the vicinity of the left end shaft support portion of the second intermediate shaft 49 and meshes with the first intermediate shaft large diameter gear 102.

A driven helical gear mechanism 105 is provided in a portion of the second intermediate shaft 49 in the centrifugal clutch chamber 71. This is a mechanism that unilaterally transmits the rotation of the second intermediate shaft 49 to the second intermediate shaft large-diameter gear 104 that is pivotally supported by the second intermediate shaft 49 and prevents rotational force transmission in the reverse direction. It is. The second intermediate shaft large-diameter gear 104 meshes with a kick start mechanism driven gear 50 that is spline-fitted to the crankshaft 37.

The kick start mechanism 46 is configured as described above, and when the kick pedal 106 is depressed, the driving force is kicked via the gears of the first intermediate shaft 48 and the second intermediate shaft 49 and the driven helical gear mechanism 105. The crankshaft 37 is forcibly rotated by being transmitted to the starting mechanism driven gear 50.

In FIG. 4, the power unit 20 is also provided with a motor starting mechanism 107. The motor start mechanism 107 is provided on the left part of the starter motor 108, the drive pinion 109 provided on the rotation shaft of the starter motor 108, the large diameter gear 111, the small diameter gear 112 of the motor start mechanism intermediate shaft 110, and the crankshaft 37. The motor start mechanism driven gear 69 and the one-way clutch 113 interposed between the motor start mechanism driven gear 69 and the crankshaft 37. The start of the starter motor 108 causes the crankshaft 37 to be forcibly rotated. Be made.

3, a first air passage 115 that guides outside air into the transmission case 63 is provided in the upper rear portion of the outer transmission case 63B. As described above, since the air guide plate 72 is fixed inside the outer transmission case 63B, the transmission case 63 is divided into the transmission chamber 73 and the air guide chamber 74 by the air guide plate 72. Yes.

FIG. 5 is a view in which a longitudinal section of the outer transmission case 63B cut between the outer wall and the air guide plate 72 is viewed from the right. A first air passage 115 is provided in the rear upper part of the outer transmission case 63B, and air is introduced. The air guide plate 72 has a shape covering almost the entire inner surface of the outer transmission case 63B, and is disposed on the outer side in the vehicle width direction of the belt type continuously variable transmission 23. The air guide plate 72 is provided with a second air passage 116 (see also FIG. 3) that penetrates the air guide plate 72 at a position facing the end of the drive pulley shaft 38. This is for guiding the air in the air guide chamber 74 to the transmission chamber 73. A portion of the air guide plate 72 facing the end of the driven pulley shaft 39 is provided with a driven pulley shaft through-hole 117 (see also FIG. 3) that penetrates the air guide plate 72. Here, the end of the driven pulley shaft 39 penetrates. Since a cylindrical portion 118 (see also FIG. 3) that reaches the peripheral edge of the driven pulley shaft through-hole 117 from the inside of the outer transmission case 63B is formed to protrude, air does not flow into the driven pulley shaft through-hole 117. A wall 138 is provided from the outer transmission case 63B toward the periphery of the air guide plate 72 (see also FIGS. 3 and 4). Since the wall 138 is in contact with the air guide plate 72, air basically does not flow from the periphery of the air guide plate 72, but there may be some air flow.

As shown in FIG. 3, the driving pulley fixing half 78 is provided with a wind guide fin 119, and the air in the wind guide chamber 74 is forcibly sucked into the transmission chamber 73 by the rotation of the drive pulley 40. Is done. Since the fins 119 are provided on the driving pulley fixing half 78, the distance between the air guide fins 119 and the air guide plate 72 is kept constant, and stable suction is possible. Since the driven pulley fixing half 81 is also provided with the fins 125, the pulley cooling effect is improved.

As shown in FIG. 1, an air cleaner 120 for continuously variable transmission cooling is provided in the body cover 18 at the rear of the vehicle on the upstream side of the first air passage 115. This is different from the air cleaner 28 for intake air of the internal combustion engine. Since the first air passage 115 is at the rear and upper part of the power unit 20, even if there is no continuously variable transmission cooling air cleaner 120 upstream of the first air passage 115, the sand or dust flying from the front is the first air. Difficult to enter passage 115. Sand and dust are temporarily removed by the above-described continuously variable transmission cooling air cleaner 120. However, even if the continuously variable transmission cooling air cleaner 120 is not provided, the air remains in the air guide chamber 74. Thus, sand and dust are dropped on the way from the first air passage 115 to the second air passage 116. Further, since the first air passage 115 and the second air passage 116 are separated from each other, sand and dust are likely to fall between them. Further, since the direction of the cooling air 121 flowing from the first air passage 115 is directed to the lower part of the air guiding chamber 74, the cooling air 121 flows through the lower part of the air guiding chamber 74, and sand or Dust is easier to fall.

As shown in FIG. 1, a footrest step 122 for passengers is provided on the side of the transmission case 63 of the power unit 20. As described above, the air guide chamber 74 is provided on the outer surface of the transmission case 63, and is cooled by air, and the heat of the belt type continuously variable transmission 23 is blocked by the air guide chamber 74. The feet do not feel heat and can ride comfortably.

FIG. 6 is a view of the left mating surface of the outer transmission case 63B and the inside of the transmission chamber 73 as viewed from the left. In the figure, on the inside of the peripheral wall of the outer transmission case 63B, a drive pulley shaft 38, a drive pulley 40 provided on the shaft, a driven pulley shaft 39, a driven pulley 41 provided on the shaft, and both pulleys are hung. A rotated V-belt 42 is shown. On the upper part of the outer transmission case 63B, there is provided a discharge passage inlet guide rib 63Ba for guiding the cooling air 121 discharged to the discharge passage 124 of the later-described inner transmission case 63A.

FIG. 7 is a view of the right mating surface of the inner transmission case 63A and the inside of the transmission chamber 73 as viewed from the right. In the figure, the drive pulley shaft 38, the drive pulley 40 provided on the shaft, the driven pulley shaft 39, the driven pulley 41 provided on the shaft, and both pulleys are hung inside the peripheral wall of the inner transmission case 63A. A rotated V-belt 42 is shown. An exhaust passage inlet 123 is provided in the upper part of the inner transmission case 63A, and a cross section of the exhaust passage 124 is visible in the back. Inside the inner transmission case 63A, there is provided a discharge passage inlet guide rib 63Aa for guiding the discharge of the cooling air 121 toward the discharge passage 124.

FIG. 8 is a view showing the right side of the right crankcase 25R and the inside of the centrifugal clutch chamber 71. As shown in FIG. In the figure, on the inner side of the peripheral wall of the right crankcase 25R, an extension part of the crankshaft 37, a kick starter driven gear 50 provided on the extension part, a kick starter mechanism second intermediate shaft 49, a second intermediate shaft large diameter Gear 104, driven helical gear mechanism 105 of kick starting mechanism 46, driven pulley shaft 39, wet centrifugal clutch 43, clutch output gear 76, reduction gear mechanism intermediate shaft 45, intermediate shaft large diameter gear 91, output shaft 31 of power unit 20, oil A pump 125 and a starter motor 108 are shown. An exhaust passage 124 for cooling air is provided in the upper part of the right crankcase 25R, and its cross section is visible. The peripheral wall 140 of the exhaust passage 124 also serves as a reinforcing wall of the power unit hanger boss 139.

FIG. 9 is a view showing the right side of the left crankcase 25L and the inside of the crank chamber 65, the kick start mechanism gear chamber 95, and the reduction gear chamber 66. As shown in FIG. In the figure, the crankshaft 37, the crank web 37a, the kick shaft 47 of the kick start mechanism 46, the kick drive gear 100, the first intermediate shaft 48, the first intermediate shaft small diameter gear 101, the first intermediate shaft large diameter gear 102, the first 2 shows an intermediate shaft 49, a second intermediate shaft small diameter gear 103, an intermediate shaft 45 of the reduction gear mechanism 24, an intermediate shaft small diameter gear 92, an output shaft 31, an output shaft large diameter gear 93, and a starter motor 108. An exhaust passage 124 is provided in the upper part of the left crankcase 25L, and its cross section is visible.

FIG. 10 is a left side view of the left crankcase 25L. A crankshaft 37, a cam chain 59, a cam chain tensioner mechanism 126, a lubricating oil injection port 127, an output shaft 31, a power transmission chain drive sprocket 32, a power transmission chain 34, and a kick shaft 47 are shown. An exhaust passage 124 is provided in the upper part of the left crankcase 25L, and its cross section is visible.

An exhaust guide rib 130 is provided below the exhaust passage 124, and an output shaft protection rib 131 is provided around the front portion of the output shaft 31 to form an output shaft protection portion 137. The exhaust passage 124, the exhaust passage downward portion 135, the output shaft 31, the power transmission chain drive sprocket 32, and the sprocket vicinity of the power transmission chain 34 are one rear power unit cover 132 (indicated by a two-dot chain line) Covered by. However, since the rear power unit cover 132 is provided with an opening 132a through which the lubricating oil inlet 127 can be seen from the outside, the lubricating oil inlet 127 is not covered.

FIG. 11 is a sectional view taken along line XI-XI in FIG. From the right, the cross-sections of the outer transmission case 63B, the inner transmission case 63A, the right crankcase 25R, the left crankcase 25L, and the rear power unit cover 132 are shown from the right. The formed exhaust air passage portions are connected to form a series of air exhaust passages 124, and the used cooling air 121 is discharged. The lubricating oil inlet 127 is provided with an oil inlet lid 133 that also serves as an oil level gauge, and protrudes from the opening 132 a of the rear power unit cover 132. The rear power unit cover 132 is provided with a guide portion 132 b that guides the tip of the oil supply to the oil filling port 127. The cooling air 121 that flows from the transmission chamber 73 through the exhaust passage inlet 123 into the exhaust passage 124 and flows to the left through the exhaust passage 124 collides with the rear power unit cover 132 and turns downward. The air flows downward in the exhaust passage 135 between the left crankcase 25L and the rear power unit cover 132, and is discharged from the exhaust outlet 136 into the atmosphere.

In FIG. 10, the cooling air 121 flows downward in the exhaust air passage downward portion 135 formed by being surrounded by the exhaust air guide rib 130, the output shaft protection rib 131, and the rear portion of the lubricating oil injection port 127. The air is then discharged from the exhaust outlet 136 into the atmosphere. The exhaust air passage downward portion 135 is protected by the rear power unit cover 132.

In FIG. 3, the lubricating oil injection port 127 is provided in a recess between the generator housing 134 and the output shaft protection rib 131, and the rear power unit cover 132 avoids the lubricating oil injection port 127, Covering. An exhaust air passage downward portion 135 that is continuous with the exhaust air passage 124 is formed on the rear side of the lubricating oil injection port 127. The exhaust passage downward portion 135 is formed in a recess between the generator housing portion 134 of the crankcase 25 and the output shaft protection rib 131 when viewed from above, so that the members of the power unit are stretched in the vehicle width direction. I do not put out. Since the lubricating oil injection port 127 is provided in the recess, the oil injection port 127 and the oil supply port lid 133 do not protrude in the vehicle width direction.

In FIG. 10, since the lubricating oil injection port 127 is disposed in the recess between the generator housing 134 and the kick shaft 47, the lubricating oil injection port 127 and the lubrication port lid 133 can be disposed without overhanging. The power unit 20 can be made compact.

As described above in detail, the present embodiment provides the following effects.
(1) Since the exhaust passage 124 of the belt type continuously variable transmission 23 passes through the upper part of the crankcase 25, the exhaust passage downward portion 135 is formed on the side surface of the crankcase 25 opposite to the transmission 23. Thus, it is possible to effectively prevent dust and water from entering the transmission case 63 through the exhaust passage 124.
(2) Since the exhaust passage 124 is manufactured integrally with the left and

right crankcases

25L, 25R and the inner transmission case 63A, the number of parts can be reduced.
(3) Since the exhaust passage downward portion 135 is disposed in a recess formed between the generator chamber 67 of the crankcase 25 and the housing portion of the output shaft 31 in a top view, the power unit 20 is arranged in the vehicle width direction. The power unit 20 can be made compact without overhanging.
(4) Since the lubricating oil injection port 127 is disposed in the concave portion of the exhaust air passage downward portion 135, the member of the power unit 20 does not protrude in the vehicle width direction.
(5) The exhaust air passage downward portion 135 includes an exhaust air guide rib 130 and an output shaft protection rib 131 that extend outward from the outer surface of the left crankcase 25L, and a rear power unit cover that covers the rib from the outside. Since it is formed by 132, the exhaust passage downward portion 135 is protected.
(6) The cover that covers the exhaust passage downward portion 135 is the same rear power unit cover 132 that covers the output shaft 31 of the power unit from the outside in the vehicle width direction, so the number of parts can be reduced.
(7) Since the peripheral wall 140 of the exhaust passage 124 also serves as a reinforcing wall of the power unit hanger boss 139, the power unit hanger boss 139 is reinforced.

Claims

A crankcase that houses the crankshaft of the internal combustion engine;
A belt-type continuously variable transmission having a drive pulley shaft and a driven pulley shaft that are driven by the crankshaft in parallel with a crankshaft of an internal combustion engine, and a belt wound between pulleys provided on both pulley shafts;
A transmission case that houses the belt-type continuously variable transmission, has an air passage for sucking cooling air for cooling the belt-type continuously variable transmission, and is provided on one side of the crankshaft;
With
The transmission case forms a part thereof, an outer transmission case that covers the belt-type continuously variable transmission from the outside in the vehicle width direction, and another part of the transmission case, which is attached to the crankcase, An inner transmission case that covers the belt-type continuously variable transmission from the inner side in the vehicle width direction and forms the transmission case together with the outer transmission case;
In the vehicle power unit mounted on the vehicle so that the crankshaft faces the vehicle width direction,
An exhaust passage inlet provided in the inner transmission case for exhausting cooling air sucked into the transmission case;
An exhaust passage that communicates with the exhaust passage entrance and is provided substantially in the vehicle width direction at the top of the crankcase;
On the side of the crankcase opposite to the transmission, the exhaust passage downwardly provided continuously to the exhaust passage;
A vehicle power unit characterized by comprising:
2. The vehicle power unit according to claim 1, wherein the exhaust passage is integral with a crankcase.
A generator is provided at the end of the crankshaft opposite the pulley of the drive pulley shaft,
Means for transmitting the power of the pulley of the driven shaft disposed behind the drive pulley to the output shaft of the power unit that drives the vehicle rear wheel;
The downward portion of the exhaust passage is disposed in a recessed portion formed between a generator housing portion that houses the generator in a top view and an output shaft housing portion that covers the output shaft from the outside. The vehicle power unit according to claim 1 or 2.
4. The power unit according to claim 3, wherein an oil inlet for lubricating oil supplied to the crankcase is provided in the vicinity of the outlet of the downward portion of the exhaust passage.
The power unit according to claim 4, wherein the downward portion of the exhaust passage is formed by a rib extending outward in the vehicle width direction from the outer side surface of the crankcase and a cover that covers the rib from the outside.
6. The power unit according to claim 5, wherein the cover of the downward portion of the exhaust passage constitutes an output shaft cover that covers the power unit output shaft from the outside in the vehicle width direction.
The power unit according to claim 2, wherein the wall of the exhaust passage constitutes a reinforcing wall of a power unit hanger boss.