JPH11311126A - Power unit for off-road traveling vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a power unit for an off-road traveling vehicle wherein an oil pump does not suck air at all even if a car body is largely tilted. SOLUTION: This power unit 5 comprises an engine 6 and a shaft-driving type transmission gear 9. A driving shaft 41 of the transmission gear 9 is installed in an auxiliaries storage housing H being situated at the outside of a transmission case 27 in a crankcase 10 and partitioned off the transmission case 27. In addition, the driving shaft 41 is geared with a countershaft 39 for a geared transmission piercing through a sidewall (a vertical wall 31) of the transmission case 27.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power unit for an irregular terrain vehicle, in which a crankshaft of an engine is provided with a drive shaft for driving a wheel extending in a front-rear direction of a vehicle body and stores oil of a lubricating device.

[0002]

2. Description of the Related Art Conventionally, as a small-sized vehicle for traveling on uneven terrain, there is a vehicle that drives by driving both front wheels and rear wheels.
A power unit mounted on this type of vehicle has a structure in which power of an engine is transmitted to a front wheel and a rear wheel via a shaft drive type transmission.

The shaft drive type transmission has a drive shaft which is positioned in a crankcase of the engine so as to extend in the front-rear direction of the vehicle body and is rotatably supported. The power of the engine transmitted to the drive shaft is transmitted to the drive shaft. Of the drive shaft to the front wheels via a front-wheel driven shaft, and from the rear end of the drive shaft to the rear wheels via a rear-wheel driven shaft. The drive shaft is disposed so as to penetrate the inside of a transmission room formed in the crankcase in a longitudinal direction of the vehicle body, and is connected to a crankshaft of the engine via a transmission.

On the other hand, a lubricating device provided in the power unit draws up oil stored in the transmission chamber from an area near the bottom wall of the transmission chamber by an oil pump, and supplies the oil to a crankshaft side and a valve head side of a cylinder head. The structure is adopted to feed the lubricated part to the lubrication part.

[0005]

However, a vehicle for rough terrain travels in a state where the vehicle body is largely inclined, and thus there is a problem with the lubrication device. That is, depending on the inclination angle of the vehicle body, the oil pump sucks air, and the air enters the oil supply system. This is because when the drive shaft of the shaft drive type transmission device is housed in the transmission room, it is necessary to prevent the wall forming the transmission room from coming into contact with the drive shaft, so that the volume of the transmission room becomes large, As a result, the volume of the air chamber portion in the transmission room becomes large, and when the vehicle body is greatly inclined, oil easily flows into the air chamber portion of the transmission room, and the oil suction port is located above the oil level of the oil. The cause is that it becomes.

SUMMARY OF THE INVENTION The present invention has been made to solve such a problem, and an object of the present invention is to provide a power unit for an irregular terrain vehicle in which an oil pump does not take in air even when the vehicle body is greatly inclined. And

[0007]

In order to achieve this object, a power unit for an off-road vehicle according to the present invention includes a drive shaft of a shaft drive type transmission device which is located outside a transmission room in a crankcase. The transmission room is provided in a defined accessory housing room, and is gear-coupled to a transmission output shaft penetrating the side wall of the transmission room.

According to the present invention, the volume of the air chamber portion in the transmission room can be reduced as compared with the conventional case because the drive shaft of the shaft drive type transmission device does not exist in the transmission room. Therefore, the amount of oil flowing into the air chamber portion when the vehicle body is greatly inclined can be reduced.

According to another aspect of the present invention, there is provided a power unit for an irregular terrain vehicle according to the above-described invention, wherein the auxiliary unit accommodating chamber accommodates a V-belt type automatic transmission. A cooling air inlet for introducing cooling air for cooling the V-belt type automatic transmission and a cooling air outlet for discharging warmed cooling air are provided in the machine accommodation room.

According to the present invention, the drive shaft of the shaft drive type transmission device housed in the accessory housing is cooled by the cooling air introduced into the accessory housing.

According to another aspect of the present invention, there is provided a power unit for an uneven terrain vehicle according to the above-described invention, wherein a V-belt type automatic transmission is accommodated in an auxiliary equipment accommodation room. A belt-type automatic transmission is connected to a crankshaft via a centrifugal clutch housed in a clutch chamber separated from an accessory housing, and at least a part of a drive shaft of a shaft drive type transmission is connected to a V in a crankcase. It is positioned in a space formed by a side wall on the belt type automatic transmission side, a side surface on the crankcase side of the V-belt type automatic transmission, and a bottom surface of the clutch chamber.

According to the present invention, it is possible to dispose at least a part of the drive shaft of the shaft drive type transmission in the dead space formed in the power unit.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of a power unit of a vehicle for running on uneven terrain according to the present invention will be described below in detail with reference to FIGS. FIG. 1 is a side view of a small four-wheeled vehicle for running on uneven terrain equipped with a power unit according to the present invention, FIG. 2 is a side view of a crankcase, FIG. 3 is a plan view of a crankcase, and FIG. The portion supporting the transmission is shown broken away. FIG. 4 is a sectional view showing a drive system of the oil pump. The broken position in the figure is indicated by the line IV-IV in FIG. FIG. 5 is an enlarged sectional view showing an oil pump portion, and FIG. 5 is a sectional view taken along line VV in FIG.
6 is a sectional view taken along line VI-VI in FIG. 2, and FIG. 7 is a sectional view taken along line VII-VII in FIG.

In these figures, reference numeral 1 denotes a small-sized four-wheeled vehicle for running on uneven terrain according to this embodiment.
In this small four-wheeled vehicle 1, an occupant sits across a seat 2,
The vehicle travels while holding the steering handle 3 in front of the seat 2, and a fuel tank 4 is provided between the seat 2 and the steering handle 3.
And a power unit 5 for driving four wheels is mounted below the fuel tank 4.

The power unit 5 includes a water-cooled single-cylinder engine 6 and a front wheel 7 and a rear wheel 8
And a shaft drive type transmission 9 for transmitting power to the shaft. The crankcase 10 of the engine 6
Is formed by a crankcase half 11 on the right side of the vehicle body and a crankcase half 12 on the left side of the vehicle body. As shown in FIGS.
A V-belt type automatic transmission 13 is supported, and a gear type transmission 15 is provided behind the vehicle body with respect to the crankshaft 14.
The transmission is transmitted to the shaft drive type transmission 9 via a gear type transmission 15.

The crankshaft 14 of the engine 6 has a centrifugal clutch 16 (see FIGS. 3, 4 and 6) at the right end of the vehicle body.
A V-belt type automatic transmission 13 is connected via a, and a flywheel magneto 17 is mounted on the left end of the vehicle body. 4 and 6, a balancer driving gear 18 is fixed to the crankshaft 14 on the left side of the vehicle body with respect to the crank web 14a, and a balancer 20 is gear-coupled via a driven gear 19 meshed with the gear 18. Let me. Since the centrifugal clutch 16 has the same structure as a conventionally known clutch, it is illustrated in a simplified state in FIG.

The V-belt type automatic transmission 13 has a drive shaft 21 connected to the right end of the crankshaft 14 via the centrifugal clutch 16 so as to extend in the vehicle width direction. A driven pulley 22, a driven shaft 24 having a driven pulley 23 axially mounted on the rear of the vehicle body with respect to the drive shaft 21 so as to be parallel to the drive shaft 21, and a drive pulley 22 and a driven pulley 23. V belt 2 wrapped around
5 and is disposed outside the crank chamber 26 (see FIG. 4) and the transmission chamber 27 that accommodates the gear transmission 15 described later.

The drive shaft 21 has an end on the left side of the vehicle body as shown in FIG.
It is rotatably supported by the crankcase half 11 on the right side of the vehicle body via a cylindrical bearing bracket and bearing 29 indicated by reference numeral 28, and the right end of the vehicle body is attached to an outer cover indicated by reference numeral 30 in FIG. It is rotatably supported. As shown in FIG. 6, the bearing bracket 28 has a structure in which a clutch chamber C is formed inside when mounted on the crankcase half 11 on the right side of the vehicle body. The clutch chamber C is defined as a space outside the bearing bracket 28 (an auxiliary equipment chamber H described later), and houses the centrifugal clutch 16. The bearing bracket 28
As shown in FIGS. 6 and 7, a shroud 13a for covering the drive pulley 22 of the V-belt type automatic transmission 13 on the engine 6 side is fixed.

The outer cover 30 is for covering the V-belt type automatic transmission 13, and is fixed to the right end of the right half of the crankcase half 11 on the right side of the vehicle. In addition, since the crankcase half 11 on the right side of the vehicle body covers the V-belt type automatic transmission 13 together with the outer cover 30, as shown in FIG. It is formed to be larger than the machine 13. The space between the crankcase half 11 on the right side of the vehicle body and the outer cover 30, that is, the V-belt type automatic transmission 1
The space for accommodating 3 forms an auxiliary equipment accommodating room according to the present invention. This auxiliary machine accommodation room is indicated by reference numeral H in the figure.

The auxiliary equipment accommodating chamber H is provided with a V-belt type automatic transmission 1
A cooling air inlet for introducing cooling air for cooling the cooling air 3 is provided on the front side of the vehicle body, and a cooling air outlet for discharging warm cooling air is provided on the rear side of the vehicle body. Fig. 3
A cooling air inlet duct denoted by reference numeral 5a is connected to the inside, and a cooling air outlet duct denoted by reference numeral 5b in the drawing is connected to the cooling air outlet.

The driven shaft 24 penetrates a vertical wall 31 (see FIG. 3) extending in the vertical direction of the crankcase half 11 on the right side of the vehicle body and in the front-rear direction of the vehicle body. It extends to the vertical wall 32 and is rotatably supported by the vertical walls 31 and 32 via bearings 33 and 34. As shown in FIG. 2, the left crankcase half 12 supporting the shaft end of the driven shaft 24 on the left side of the vehicle body has an upper wall 35 on the rear side of the vehicle body near the upper side of the driven shaft 24 in the front-rear direction of the vehicle body. It is formed to extend.

The reason why the upper wall 35 is formed to be lower than the upper wall of the other crankcase half 11 is to reduce the size of the crankcase 10. With this configuration, a space formed above the left side of the vehicle body of the crankcase 10, that is, as shown in FIG. 5, the upper wall 35 and the crankcase half 1 on the right side of the vehicle body
In the space S at the corner formed by the one vertical wall 31,
A cartridge type oil filter 36 is provided. In this embodiment, an oil filter 36 is detachably attached to the vertical wall 31 in order to form an oil passage in the vertical wall 31 of the crankcase half 11 on the right side of the vehicle body, as described later.

The gear type transmission 15 is shown in FIGS.
As shown in FIG. 3, a main shaft 38 connected to the driven shaft 24 of the V-belt type automatic transmission 13 via a speed change gear 37, a sub shaft 39 gear-coupled to the main shaft 38, and the speed change gear 37 Transmission mechanism 1 having shift fork 40 for moving a shifter (not shown) to be engaged along main shaft 38
5a. The main shaft 38 and the sub-shaft 39 are rotatably supported at portions of the crankcase halves 11, 12 behind the crankshaft 14 in the vehicle body. The gear type transmission 15 is provided with an operation lever 15 disposed on the left side of the vehicle body with respect to the fuel tank 4.
b (see FIG. 1) to shift.

The shaft drive type transmission 9 includes a drive shaft 41 rotatably supported below the crankcase half 11 on the right side of the vehicle body so as to extend in the front-rear direction of the vehicle body.
(See FIGS. 2 and 3 and FIGS. 5 and 6).
1 is transmitted to the front wheels 7 and the rear wheels 8
The structure to transmit to is adopted. The drive shaft 41 is located outside the transmission room 27 of the crankcase 10 (right side of the vehicle body).
And the auxiliary equipment accommodating chamber H defined with the transmission chamber 27.
The front end of the vehicle body projects from the front end of the crankcase half 11 on the right side of the vehicle body, and the rear end of the vehicle body projects from the rear end of the crankcase half 11. The front part of the drive shaft 41 is, as shown in FIG.
A side wall (the vertical wall 31) of the V-belt type automatic transmission 13 in the crankcase half portion 11 on the right side of the vehicle body, and a side surface of the V-belt type automatic transmission on the crankcase side (the engine of the shroud 13a in this embodiment). 6 inner surfaces)
And the bottom surface of the clutch chamber C.

As shown in FIG. 7, the front end of the drive shaft 41 and the rear end of the drive shaft 41 are rotatably supported by the crankcase half 11 on the right side of the vehicle by bearings 41a and 41b. ing. In FIG. 7, the direction indicated by a white arrow F in FIG. 7 is forward of the vehicle body. Further, the drive shaft 41 is connected to the crankcase half 11.
Are provided between the drive shaft 41 and the crankcase half 11 with seal members 41c and 41d.

The front wheel 7 is connected to the front end of the drive shaft 41 via a front wheel-side driven shaft indicated by reference numeral 41e in FIG. The rear end of the drive shaft 41 on the vehicle body is
As shown in FIG. 5, the bevel gear 42 is connected via an engaging member 41f, and a universal joint 42a attached to the bevel gear 42 and a rear wheel-side driven shaft (not shown) connected to the universal joint 42a. And the rear wheel 8 is connected. The engaging member 41f is connected to the drive shaft 41 so as to be movable in the front-rear direction by spline fitting the front portion of the vehicle body to the drive shaft 41, and engages the rear portion of the vehicle body so that rotation is transmitted to the bevel gear 42. And are urged toward the bevel gear 42 by the compression coil spring 41g.

The bevel gear 42 is mounted on the gear type transmission 15
And the bevel gear 43 attached to the sub shaft 39 of FIG. That is, the rotation of the sub shaft 39 is transmitted to the drive shaft 41 via the bevel gears 42 and 43 and the engaging member 41f.
These bevel gears 42 and 43 are housed in a gear chamber 44 which is partitioned from the crank chamber 26, the transmission chamber 27, and the auxiliary equipment housing chamber H. The gear chamber 44 is supplied with oil. The right end of the countershaft 39 on the vehicle body passes through the wall member 11a attached to the crankcase half 11 on the right side of the vehicle body and faces the gear chamber 44. A portion located in the gear chamber 44 , The bevel gear 43 is fixed.

The balancer 20, which is gear-coupled to the crankshaft 14, is formed in a rod shape as shown in FIGS. 3 and 4, and the vertical walls 3 of the two crankcase halves 11, 12 are formed.
1, 32 are rotatably supported by bearings 45, 45. The gears 18 and 19 interposed between the crankshaft 14 and the balancer 20 are such that the balancer 20
4, the number of teeth is set so that the balancer 20 is positioned at a position where the weight 20a at the center of the balancer 20 is close to the crank web 14a.

The balancer 20 has an end on the left side of the vehicle body protruding outwardly from the vertical wall 32 of the half crankcase 12 on the left side of the vehicle body, and will be described later via an auxiliary device driving gear 46 fixed to the protruding portion. The input shaft 49 of the cooling water pump 47 and the oil pump 48 is gear-coupled.

The input shaft 49 includes a crankcase cover 12a fixed to the left end of the vehicle body left crankcase half 12 and the vehicle body left crankcase half 1
2 and extends to the vertical wall 31 of the crankcase half 11 on the right side of the vehicle body, and is rotatably supported by the crankcase cover 12a and the vertical walls 31, 32. A gear 50 that meshes with the auxiliary device driving gear 46 on the balancer 20 side is fixed to the input shaft 49 so that the rotation of the crankshaft 14 is transmitted through the balancer 20.

A cooling water pump 47 is connected to the left end of the input shaft 49 on the vehicle body, and an oil pump 48 is connected to an end portion on the right side of the vehicle body. The cooling water pump 47 is a conventionally known centrifugal pump in which the impeller 51 rotates together with the input shaft 49, and is attached to the crankcase cover 43. The position where this cooling water pump 47 is mounted is shown in FIG.
As shown in FIG. 2, the V-belt type automatic transmission 13 is positioned at a position overlapping the V-belt 25 between the drive shaft 21 and the driven shaft 24 when viewed from the axial direction of the crankshaft 14.

A cooling water inlet of the cooling water pump 47 is connected to a cooling water outlet of a radiator indicated by reference numeral 52 in FIG. 1 via a cooling water hose 53, and a cooling water hose 54 is connected to the cooling water outlet. The cooling water passage of the engine 6 is connected to the cooling water passage. The cooling water passage of the engine 6 is
a, a cooling water inlet formed in the cylinder body 6a and a cooling water flowing from the water jacket in the cylinder head 6b to the water jacket in the cylinder head 6b. The cooling water inlet of the radiator 52 is connected via a cooling water hose 55. These cooling water hoses 53 to 55 are
The pipe is arranged so as to surround the cylinder of the engine 6 when viewed from above. The radiator 52 is provided at the front end of the vehicle body, and is connected to the body frame 5 via a bracket (not shown).
6 is supported.

An oil pump 48 connected to the right end of the input shaft 49 on the vehicle body is of a trochoid type, and is supported by the vertical wall 31 of the crankcase half 11 on the right side of the vehicle body. Is supported by the vertical wall 31 via the oil pump 48.

Here, the structure of the lubricating device having the oil pump 48 will be described. The lubricating device employs a structure in which oil stored in the transmission chamber 27 is sucked up by an oil pump 48, passes through the oil filter 36, and is then pressure-fed to a portion to be lubricated. The oil level at the time of running of the oil is indicated by the symbol L in FIG.

The oil pump 48 is, as shown in FIG.
The oil inlet 48a is located between the drive shaft 21 and the driven shaft 24 of the V-belt type automatic transmission 13 as viewed from above, and as shown in FIG.
Through an oil suction passage 58 and an oil outlet 48
b to the upper oil filter 36 in the oil discharge passage 59
Connected through. The oil strainer 57 includes:
A structure is adopted in which the periphery of the oil suction port 57a that opens downward is covered with a wire net 57b. As shown in FIGS. 2 and 5, the oil suction passage 58 has a horizontally extending portion 58 extending from the oil strainer 57 to the front of the vehicle body.
a and a vertically extending portion 58b extending vertically so that the front end of the horizontal extending portion 58a is connected. The horizontal extending portion 58a is formed at a portion where the two crankcase halves 11, 12 are joined, and the vertical extending portion 58b is formed at the vertical wall 31 of the crankcase half 11 on the right side of the vehicle body.

The oil discharge passage 59 has a vertically extending portion 59a formed in the vertical wall 31 so as to extend upward from the oil pump 48, and a vertically extending portion 59a.
and a horizontal extending portion 59b formed on the vertical wall 31 so as to extend to the left of the vehicle body from the upper end of the oil filter 36 toward the oil inlet 36a on the outer periphery of the oil filter 36. The vertically extending portion 59 of the oil discharge passage 58
a is formed between the drive shaft 21 and the driven shaft 24 of the V-belt type automatic transmission 13 as shown in FIG.

The oil filter 36 has a structure in which oil supplied from an oil inlet 36a at the outer peripheral portion passes through an internal element (not shown) and is then discharged to an oil outlet 36b at an axial center portion. It is connected to an oil distribution passage 60 described later. Oil distribution passage 6
2, an upstream portion 60a extending forward and downward from the oil outlet 36b, as shown in FIG. 2, and a downstream portion 60b extending forward and upward from the front end of the upstream portion 60a. The upstream portion 60a is formed on the vertical wall 31 of the crankcase half 11 on the right side of the vehicle body, and the downstream portion 60b is formed on a portion where the two crankcase halves 11 and 12 meet. This lubricating device is a valve operating device (not shown) between the downstream portion 60b and the crankshaft 14 side and the cylinder head 6b.
The structure distributes oil to the side.

An oil introduction passage for guiding oil from the downstream portion 60b to the crankshaft 14 is indicated by reference numeral 61 in FIG. The oil introduction passage 61 passes through the vertical wall 31 of the crankcase half portion 11 on the right side of the vehicle body and the oil passage forming member 62 fixed to the vertical wall 31 so that the crankshaft 1
4 and extend from the inside of the crankshaft 14 to the large end of the connecting rod 63 and the sliding portion (not shown) of the centrifugal clutch 16. An oil introduction passage for guiding oil from the downstream portion 60b to the valve gear of the cylinder head 6b is formed using a bolt hole of the head bolt 64. This oil introduction passage is indicated by reference numeral 65 in FIGS.

In the lubricating device thus configured, the oil stored in the bottom of the crankcase 10 passes from the oil inlet 57 a of the oil strainer 57 through the oil suction passage 58 when the oil pump 48 rotates together with the crankshaft 14. The oil is sucked into the oil pump 48 and is supplied from the oil pump 48 to the oil filter 36 through the oil discharge passage 59. Then, the oil is pressure-fed from the oil filter 36 to each lubricated portion of the engine 6 through the oil distribution passage 60 and the oil introduction passages 61 and 65.

The power unit 5 configured as described above
The drive shaft 41 of the shaft drive type transmission 9 is disposed outside the transmission room 27 and in the accessory housing H which is defined from the transmission room 27, and the side wall of the transmission room 27 ( Since the gear shaft is gear-coupled to the countershaft 39 of the gear transmission 15 that penetrates the vertical wall 31) of the crankcase half 11, the air chamber portion in the transmission chamber 27 is conventionally provided because the drive shaft 41 does not exist. The volume can be reduced in comparison.

Therefore, when the small four-wheeled vehicle 1 for running on uneven terrain equipped with the power unit 5 travels in a greatly inclined state, the amount of oil flowing into the air chamber portion is reduced as compared with the prior art. The oil level L of the oil can be relatively increased. For this reason, at this time, the oil suction port 57a of the oil strainer 57 is not exposed above the oil level.

The drive shaft 41 of the shaft drive type transmission 9 housed in the accessory housing H is cooled by the cooling air introduced into the accessory housing H from the cooling air inlet duct 5a. The drive shaft 41 is prevented from extending in the axial direction due to thermal expansion due to heat from the engine 6. For this reason, it is possible to prevent the drive shaft 41 extending in the axial direction from applying an excessive force to the drive system of the front wheels 7 and 8.

Further, the front portion of the drive shaft 41 is connected to the V-belt type automatic transmission 13 in the crankcase 11 on the right side of the vehicle body.
The engine 6 is large in size because it is located in a dead space in the accessory housing chamber H formed by the vertical wall 31 on the side, the crankcase side of the V-belt type automatic transmission 13 and the bottom surface of the clutch chamber C. The drive shaft 41 can be housed in the accessory housing chamber H without any modification.

In this embodiment, an example is shown in which the power unit according to the present invention is mounted on a small-sized four-wheeled vehicle for running on rough terrain. It can also be mounted on a tricycle.

[0045]

As described above, according to the present invention, the space above the oil level in the transmission room, that is, the air chamber portion in the transmission room does not have the drive shaft of the shaft drive type transmission. Therefore, the volume can be reduced as compared with the related art. Therefore, the amount of oil flowing into the air chamber portion when the vehicle body is greatly inclined can be reduced as compared with the conventional case, and the oil level of the oil can be relatively increased. The suction port is not exposed above the oil level.

Therefore, it is possible to provide a power unit for an uneven terrain vehicle in which the oil pump does not suck air even when the vehicle body is greatly inclined.

According to another invention in which the V-belt type automatic transmission is housed in the accessory housing, and the cooling air inlet and the cooling air outlet are provided in the accessory housing, the shaft drive housed in the accessory housing is provided. Since the drive shaft of the transmission is cooled by the cooling air introduced into the accessory housing, it is possible to prevent the drive shaft from thermally expanding due to heat from the engine and extending in the axial direction. Accordingly, it is possible to prevent the drive shaft from extending in the axial direction and applying an excessive force to the drive system of the wheels.

The V-belt type automatic transmission accommodated in the auxiliary equipment accommodating chamber is connected to the crankcase via a centrifugal clutch in the clutch chamber, and at least a part of the drive shaft of the shaft drive type transmission is connected to the V-belt in the crankcase. According to another invention located in a space formed by a side wall on the automatic transmission side, a side surface on the crankcase side of the V-belt automatic transmission, and a bottom surface of the clutch chamber, the invention is formed in the power unit. Since at least a part of the drive shaft of the shaft drive type transmission can be disposed in the dead space, the drive shaft can be housed in the accessory housing room without increasing the size of the engine.

[Brief description of the drawings]

FIG. 1 is a side view of a small four-wheeled vehicle for running on uneven terrain, equipped with a power unit according to the present invention.

FIG. 2 is a side view of a crankcase.

FIG. 3 is a plan view of a crankcase.

FIG. 4 is a sectional view showing a drive system of the oil pump.

FIG. 5 is an enlarged sectional view showing an oil pump portion.

FIG. 6 is a sectional view taken along line VI-VI in FIG. 2;

FIG. 7 is a sectional view taken along line VII-VII in FIG.

[Explanation of symbols]

1: small four-wheeled vehicle for running on uneven terrain, 5: power unit, 6 ...
Engine 7, front wheel, 8 rear wheel, 9 shaft drive transmission, 10 crankcase, 11, 12 half crankcase, 13 V-belt automatic transmission, 13a
... shroud, 14 ... crankshaft, 15 ... gear type transmission, 16 ... centrifugal clutch, 27 ... transmission room, 31 ... vertical wall, 39 ... sub shaft, 41 ... drive shaft, 42, 43 ... bevel gear,
48: oil pump, H: auxiliary equipment accommodation room, C: clutch room.

Claims (3)

[Claims] 1. A shaft drive type transmission device in which a drive shaft for transmitting the power of an engine to wheels is supported by a crankcase so as to extend in the front-rear direction of a vehicle body, and an oil stored in a transmission chamber of the crankcase. In a power unit for an all-terrain vehicle having an oil pump and a lubricating device for pumping the lubricated portion to an lubricated portion, the drive shaft is located outside the transmission room and an auxiliary machine housing is defined from the transmission room. A power unit for an all-terrain vehicle, wherein the power unit is arranged in a vehicle room and gear-coupled to a transmission output shaft penetrating a side wall of the transmission room. 2. A power unit for a vehicle for traveling on uneven terrain according to claim 1, wherein a V-belt type automatic transmission is accommodated in an accessory accommodation room, and the V-belt automatic transmission is cooled in the accessory accommodation room. A power unit for a vehicle for traveling on uneven terrain, comprising a cooling air inlet for introducing cooling air to be cooled and a cooling air outlet for discharging warmed cooling air. 3. The power unit for a vehicle for running on uneven terrain according to claim 1, wherein a V-belt type automatic transmission is accommodated in an accessory accommodation room, and the V-belt automatic transmission is partitioned from the auxiliary equipment accommodation room. And at least a part of the drive shaft of the shaft drive type transmission is connected to a V-belt type automatic transmission side wall of the crankcase and a V-belt type transmission. A power unit for an all-terrain vehicle, wherein the power unit is located in a space formed by a side surface on a crankcase side of an automatic transmission and a bottom surface of a clutch chamber.