Utility vehicle

A utility vehicle comprises a traveling driving power source which generates rotational driving power for driving a drive wheel; a continuously variable transmission including an input shaft to which the rotational driving power transmitted from the traveling driving power source is input, an output shaft which outputs the rotational driving power toward the drive wheel, a drive pulley provided at the input shaft, a driven pulley provided at the output shaft, and a belt wrapped around the drive pulley and the driven pulley; a clutch which is disposed in a driving power transmission path at a location that is between the belt and the drive wheel and is capable of disconnecting the driving power transmission path; and a clutch actuator which operates the clutch.

BACKGROUND OF THE INVENTION

Field of the Invention

The present invention relates to a utility vehicle including a belt-type continuously variable transmission (CVT).

Description of Related Art

U.S. Pat. No. 8,613,336 discloses a utility which is able to travel on an uneven road (travels off-road). The utility vehicle includes an engine which generates rotational driving power for allowing the vehicle to travel, and a continuously variable transmission (CVT) which changes the rotational driving power generated in the engine.

The CVT includes a belt used to transmit driving power. In a case where a drive wheel grips a ground surface after a quick wheel spin, or a case where the vehicle jumps and then the drive wheel grips the ground surface, an excessive load is applied from the ground surface to the drive wheel and then transmitted to the belt of the CVT. If an excessive load is frequently applied to the belt, the life of the belt is reduced, and the belt is required to be changed frequently.

SUMMARY OF THE INVENTION

The present invention addresses the above-described conditions, and an object of the present invention is to provide a utility vehicle which is capable of protecting a belt of a CVT from an excessive load.

According to an aspect of the present invention, a utility vehicle comprises a traveling driving power source which generates rotational driving power for driving a drive wheel; a continuously variable transmission including an input shaft to which the rotational driving power transmitted from the traveling driving power source is input, an output shaft which outputs the rotational driving power toward the drive wheel, a drive pulley provided at the input shaft, a driven pulley provided at the output shaft, and a belt wrapped around the drive pulley and the driven pulley; a clutch which is disposed in a driving power transmission path at a location that is between the belt and the drive wheel and is capable of disconnecting the driving power transmission path; and a clutch actuator which operates the clutch.

In accordance with this configuration, the clutch which can be operated by the clutch actuator is disposed in the driving power transmission path at a location that is between the belt of the CVT and the drive wheel. Therefore, in a case where an excessive load will be (is likely to be) transmitted from the drive wheel to the belt of the CVT, the clutch is disengaged, and thus the belt of the CVT can be protected from an excessive load.

According to another aspect of the present invention, a utility vehicle comprises a traveling driving power source which generates rotational driving power for driving a drive wheel; a continuously variable transmission including an input shaft to which the rotational driving power transmitted from the traveling driving power source is input, an output shaft which outputs the rotational driving power toward the drive wheel, a drive pulley provided at the input shaft, a driven pulley provided at the output shaft, and a belt wrapped around the drive pulley and the driven pulley; an excessive load detector which detects that an excessive load will be applied to the drive wheel; and a belt protection controller which suppresses a force transmitted to the belt, in a case where the excessive load detector detects that the excessive load will be applied to the drive wheel.

In accordance with this configuration, in a case where an excessive load will be (is likely to be) transmitted from the drive wheel to the belt of the CVT, the force transmitted to the belt is suppressed (reduced). Therefore, the belt of the CVT can be protected from an excessive load.

According to a further aspect of the present invention, there is provided a controller of a vehicle including: a traveling driving power source which generates rotational driving power for driving a drive wheel; and a continuously variable transmission including an input shaft to which the rotational driving power transmitted from the traveling driving power source is input, an output shaft which outputs the rotational driving power toward the drive wheel, a drive pulley provided at the input shaft, a driven pulley provided at the output shaft, and a belt wrapped around the drive pulley and the driven pulley, wherein the controller disengages a clutch disposed in a driving power transmission path at a location that is between the belt and the drive wheel, or suppresses the rotational driving power of the traveling driving power source, to suppress a force transmitted to the belt, in a case where it is detected that an excessive load will be applied to the drive wheel.

The above and further objects, features and advantages of the present invention will more fully be apparent from the following detailed description of a preferred embodiment with reference to the accompanying drawings.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Hereinafter, the embodiments of the present invention will be described with reference to the drawings. The stated directions are from the perspective of a driver riding in a utility vehicle.

FIG. 1is a perspective view of a utility vehicle1according to Embodiment 1. As shown inFIG. 1, the utility vehicle1includes a pair of right and left front wheels3supported by the front portion of a vehicle body frame2, and a pair of right and left rear wheels4supported by the rear portion of the vehicle body frame2. A space formed between the right and left front wheels3is covered from above by a resin-made hood5. A pair of riding seats6(driver seat and passenger seat) are disposed behind the hood5. The riding seats6are arranged side by side in a region that is in in the vicinity of a center of the vehicle body frame2in a forward and rearward direction.

The vehicle body frame2includes a cabin frame member7, a pair of right and left rear gusset frame members8, and the like. The vehicle body frame2is a pipe frame including a plurality of pipe members connected to each other. The cabin frame member7is disposed to surround a riding space in which the riding seats6are placed. The riding space surrounded by the cabin frame member7is exposed. The rear gusset frame members8couple the upper portions of the cabin frame member7to the rear portions of rear frame members (not shown), respectively. Behind the riding seats6, a cargo carrier9defining a recessed loading space is provided.

Below the cargo carrier9, an engine EG and a continuously variable transmission (CVT) which will be described later are disposed (seeFIG. 2). The engine EG generates rotational driving power for driving drive wheels. In a case where the utility vehicle1is a two-wheel-drive vehicle, the front wheels3or the rear wheels4are the drive wheels. In a case where the utility vehicle1is a four-wheel-drive vehicle, the front wheels3and the rear wheels4are the drive wheels.

FIG. 2is a horizontal sectional view of a driving power transmission structure10of the utility vehicle1ofFIG. 1. As shown inFIG. 2, the driving power transmission structure10is configured to transmit the rotational driving power generated in the engine EG to the drive wheels (the front wheels3and/or the rear wheels4). In the driving power transmission structure10, the rotational driving power of a crankshaft17of the engine EG is transmitted to the CVT, a manual transmission (MT) and a drive shaft12in this order. In the driving power transmission structure10, a clutch13is disposed between the MT and the drive shaft12.

A CVT accommodating section15is provided at the outer side wall of a crankcase14of the engine EG. The CVT accommodating section15is adjacent to the engine EG The CVT accommodating section15has a CVT accommodating space S1which is covered by a CVT cover16and is elongated in a forward and rearward direction. Inside the crankcase14, the crankshaft17extending in a vehicle width direction is placed and protrudes into the CVT accommodating space S1. In the CVT accommodating space S1, the CVT is placed.

The CVT is, for example, a CVT of a V-belt type and is accommodated in the CVT accommodating space S1. The CVT includes an input shaft18which is connected to the crankshaft17and receives as an input the rotational driving power transmitted from the engine EG, and an output shaft19which outputs the rotational driving power toward the drive shaft12(toward the drive wheels). The both end portions of the input shaft18are supported by the side wall of the crankcase14and the CVT cover16. Although in the present embodiment, the crankshaft17and the input shaft18are directly coupled to each other, a centrifugal clutch may be interposed between the crankshaft17and the input shaft18. The output shaft19includes a solid inner shaft portion40(first shaft portion) and a tubular outer shaft portion41(second shaft portion) externally fitted to the inner shaft portion40. The both end portions of the inner shaft portion40extend in an axial direction and protrude outward farther than those of the outer shaft portion41.

The input shaft18is provided with a drive pulley20. The output shaft19is provided with a driven pulley21. A V-shaped belt22is wrapped around the drive pulley20and the driven pulley21. The drive pulley20includes a fixed sheave23fixed to the input shaft18, a movable sheave24fitted to the input shaft18in such a manner that the movable sheave24is axially movable, and a sheave thrust generating mechanism25(e.g., flyweight type). The belt22is retained on conical retaining surfaces of the sheaves23and24. When the movable sheave24moves on the input shaft18and a gap (space) formed between the movable sheave24and the fixed sheave23changes, a radial position where the belt22is retained (namely, effective diameter of the drive pulley20) changes.

A receiver plate27is coupled to the back surface of the movable sheave24via a plurality of coupling arms26extending outward. The receiver plate27is configured to be movable in the axial direction of the input shaft18together with the movable sheave24. The sheave thrust generating mechanism25is provided between the movable sheave24and the receiver plate27. For example, in the sheave thrust generating mechanism25, a plurality of flyweights28rotate away from the movable sheave24by a centrifugal force, and the movable sheave24is movable to approach the fixed sheave23by a reaction force pressing a pressure receiving roller29. In other words, the sheave thrust generating mechanism25generates a thrust which reduces the gap formed between the movable sheave24and the fixed sheave23by a rotation centrifugal force of the drive pulley20.

The driven pulley21includes a fixed sheave29fixed to the inner shaft portion40of the output shaft19, and a movable sheave30fitted to the inner shaft portion40of the output shaft19in such a manner that the movable sheave30is axially movable. For example, a cam tube32with a plurality of spiral cam grooves is secured to the outer peripheral surface of the inner shaft portion40of the output shaft19. The cam tube32and the fixed sheave29are rotatable together with the inner shaft portion40of the output shaft19. A sleeve33is integrally coupled to the inner peripheral end of the movable sheave30. The sleeve33is fitted to the outer peripheral surface of the cam tube32in such a manner that the sleeve33is axially movable. The sleeve33supports a roller (not shown) movable along the cam groove of the cam tube32.

When the movable sheave30receives a rotational force by a tension of the belt22, a thrust is generated in the movable sheave30to cause the movable sheave30to approach the fixed sheave29by a cam action of the cam tube32and the roller. The sleeve33is biased toward the fixed sheave29by a pressure adjustment spring34. The movable sheave30is pressed against the fixed sheave29.

With this configuration, in a state in which the input shaft18is rotating at a low speed, the effective diameter of the drive pulley20is small and the effective diameter of the driven pulley21is large (speed reduction ratio is high). When an engine speed of the engine EG increases, a thrust is generated in the sheave thrust generating mechanism25due to an increase in the centrifugal force of the drive pulley20, the movable sheave24approaches the fixed sheave23, and the effective diameter of the drive pulley20increases. In the driven pulley21, the tension of the belt22increases, a radially inward force of the belt22increases, the movable sheave30moves away from the fixed sheave29against a spring force of the pressure adjustment spring34and a cam thrust of the cam tube32, and the effective diameter of the driven pulley21reduces. In the above-described manner, the speed reduction ratio of the CVT reduces continuously with an increase in the engine speed.

The output shaft19protrudes into an inner space S2of the crankcase14. More specifically, the inner shaft portion40of the output shaft19extends over the inner space S2of the crankcase14and the CVT accommodating space S1. The outer shaft portion41of the output shaft19is not placed in the CVT accommodating space S1and placed in the inner space S2of the crankcase14. The inner shaft portion40is rotatable together with the driven pulley21. The clutch13is disposed between the inner shaft portion40and the outer shaft portion41. The outer shaft portion41is coaxial with the inner shaft portion40. The outer shaft portion41is rotatable relative to the inner shaft portion40. The outer shaft portion41outputs the rotational driving power toward the drive shaft12through the MT.

The clutch13is a friction clutch which is able to change a driving power transmission ratio continuously between a fully disengaged (disconnected) state and a fully engaged (connected) state. In the present embodiment, the clutch13is a wet type multiple disc clutch. An inner peripheral member42(input member) of the clutch13is spline-coupled to the end portion of the inner shaft portion40so that the inner peripheral member42is rotatable together with the inner shaft portion40. An outer peripheral member43(output member) of the clutch13is spline-coupled to the end portion of the outer shaft portion41so that the outer peripheral member43is rotatable together with the outer shaft portion41.

A friction plate44is provided on the outer peripheral portion of the inner peripheral member42and is axially movable. An opposing plate45is provided on the inner peripheral portion of the outer peripheral member43and is axially movable. A pressure plate46faces an assembly of the friction plate44and the opposing plate45and is able to press the assembly in the axial direction and move in the axial direction away from the assembly. The pressure plate46is coupled to a clutch actuator47. The pressure plate46is biased by a biasing spring48so that the clutch13is engaged (connected). In a state in which the clutch actuator47does not apply a force to the pressure plate46, the pressure plate46presses the assembly of the friction plate44and the opposing plate45by a spring force of the biasing spring48. The clutch13is engaged in a state in which the clutch actuator47is not activated.

The clutch actuator47is a hydraulic actuator. The clutch actuator47includes a hydraulic cylinder49, and a hydraulic control unit51which is able to feed a hydraulic (oil) pressure to the hydraulic cylinder49. A piston rod50of the hydraulic cylinder49is coupled to the pressure plate46. In this configuration, the hydraulic control unit51controlled by a controller60feeds the hydraulic (oil) pressure to the hydraulic cylinder49. Thus, the piston rod50moves away from the clutch13and is disengaged.

As described above, the clutch13is disposed in a driving power transmission path at a location that is between the belt22of the CVT and the drive shaft12. Therefore, in a case where an excessive load will be (is likely to be) transmitted from the drive wheel to the belt22, the clutch13is disengaged (disconnected). This makes it possible to protect the belt22of the CVT from an excessive load.

The CVT is disposed on a first side (e.g., right side) in the vehicle width direction (rightward and leftward direction) when viewed from the engine EG In contrast, the clutch13is disposed on a second side (e.g., left side) in the vehicle width direction when viewed from the engine EG Specifically, the CVT is disposed outward of the crankcase14on the first side in the vehicle width direction, while the clutch13is disposed outward of the crankcase14on the second side in the vehicle width direction.

As described above, the clutch13is disposed on a side opposite to a side where the CVT is disposed. In this layout, the clutch13and the clutch actuator47do not interfere with the CVT, when the clutch13and the clutch actuator47are placed. For this reason, design flexibility of the layout of the clutch13and the clutch actuator47can be improved. The CVT accommodating space S1is a dry space and a space in which the clutch13is placed is a wet space. This makes it possible to place the clutch13and the clutch actuator47without changing the conventional CVT. As a result, the design can be simplified.

The MT includes the outer shaft portion41as an input shaft, and an output shaft61disposed in parallel with the output shaft portion41. The MT is configured to transmit the driving power from the outer shaft portion41to the output shaft61via selected one of plural sets (e.g., two sets) of gear trains62with different gear ratios. The MT is, for example, a dog-gear type transmission, which changes the driving power via the selected one of the gear trains62. In the MT, a shift fork64is slidably supported by a support shaft63placed in parallel with the outer shaft portion41and the output shaft61. The first end portion of the shift fork64is connected to a dog gear62aof the outer shaft portion41. The second end portion of the shift fork64is fitted to a guide groove of a shift drum (not shown). The shift drum is mechanically rotatable in response to the driver's operation (manipulation) of a shift lever (not shown). According to the rotation of the shift drum, the shift fork64guided to the guide groove causes the dog gear62ato slide along the outer shaft portion41, one of the gear trains62with a reduction gear ratio which is desired by the driver is placed in a driving power transmission state, and a driving power transmission path with a desired transmission gear position is selected.

As described above, the MT is disposed between the output shaft19of the CVT and the drive shaft12. By combining a speed change range of the MT and a speed change range of the CVT, a wide speed range can be obtained as a whole. Therefore, the size of the CVT can be reduced, in a case where a desired speed change range is obtained.

FIG. 3is a block diagram of the controller60ofFIG. 2. As shown inFIG. 3, the controller60includes as software, a drive wheel spin (slip) detecting section71(drive wheel spin detector), a drive wheel lift-off detecting section72(drive wheel lift-off detector), an excessive load detecting section73(excessive load detector), and a belt protection control section74(belt protection controller). The controller60includes as hardware, a processor, a volatile memory, a non-volatile memory, an I/O interface, or the like. These sections71to74are performed in such a manner that the processor performs calculation (computation) by use of the volatile memory based on programs stored in the non-volatile memory.

A drive shaft rotational speed sensor80, a vehicle speed sensor81, a drive wheel speed sensor82, an engine speed sensor83, an acceleration rate sensor84, and a suspension stroke sensor85are connected to the input side of the controller60. The drive shaft rotational speed sensor80is configured to detect the rotational speed of the drive shaft12. The vehicle speed sensor81is configured to detect a traveling speed of the utility vehicle1. The drive wheel speed sensor82is configured to detect the rotational speed of the drive wheel. The engine speed sensor83is configured to detect the rotational speed of the crankshaft17of the engine EG The acceleration rate sensor84is mounted on the vehicle body frame2to detect a vertical acceleration rate of the utility vehicle1. The suspension stroke sensor85is configured to detect a stroke of a suspension connecting the vehicle body frame2to the drive wheel.

The drive wheel spin (slip) detecting section71is configured to detect a slip ratio indicative of a degree of a spin of the drive wheel. For example, the slip ratio SL is calculated based on a speed difference between a drive wheel speed and the traveling speed. Specifically, in a case where the vehicle speed detected by the vehicle speed sensor81is VV, and the drive wheel speed detected by the drive wheel speed sensor82is VD, the slip ratio SL is calculated according to a formula SL=(VD−VV)/VV. In a case where the slip ratio SL becomes higher than a predetermined value, it is determined that the drive wheel is spinning on the ground surface. Alternatively, the slip ratio SL may be calculated based on a rotational acceleration rate of a driving power system from the engine EG to the drive wheel. More specifically, in a case where a change rate of the drive wheel speed VDdetected by the drive wheel speed sensor82is ΔVD, the slip ratio SL may be calculated according to a formula SL=ΔVD. Or, in a case where a change rate of an engine speed VEdetected by the engine speed sensor83is ΔVE, the slip ratio SL may be calculated according to a formula SL=ΔVE.

The drive wheel lift-off detecting section72is configured to detect that the drive wheel is lifting-off the ground surface. For example, in a case where an upward acceleration rate detected by the acceleration rate sensor84has exceeded a predetermined threshold, the drive wheel lift-off detecting section72determines that the drive wheel is lifting-off the ground surface. Alternatively, in a case where a suspension stroke detected by the suspension stroke sensor85has exceeded the predetermined threshold, the drive wheel lift-off detecting section72determines that the drive wheel is lifting-off the ground surface.

The excessive load detecting section73is configured to detect that an excessive load will be (is likely to be) applied from the ground surface to the drive wheel. For example, in a case where the slip ratio SL detected by the drive wheel spin (slip) detecting section71has exceeded a predetermined start threshold Th1and then has been reduced, the excessive load detecting section73determines that an excessive load will be applied to the drive wheel. In accordance with this, in a case where the drive wheel changes from a spin state to a gripping state, the excessive load detecting section73can suitably detect that an excessive load will be applied to the drive wheel.

Alternatively, in a case where the drive wheel lift-off detecting section72detects that the drive wheel is lifting-off the ground surface, the excessive load detecting section73may determine that an excessive load will be (is likely to be) applied to the drive wheel. This makes it possible to suitably detect that an excessive load will be applied to the drive wheel, based on an event that the utility vehicle1jumps, the drive wheel spins, the drive wheel is grounded, and the drive wheel grips the ground surface. The excessive load detecting section73may detect that an excessive load will be applied to the drive wheel, based on the information from only one of the drive wheel spin (slip) detecting section71and the drive wheel lift-off detecting section72, or both of the drive wheel spin detecting section71and the drive wheel lift-off detecting section72.

In a case where the excessive load detecting section73detects that an excessive load will be applied to the drive wheel, the belt protection control section74initiates the belt protection control. In the belt protection control, the clutch actuator47disengages the clutch13. In a case where an excessive load will be (is likely to be) transmitted from the drive wheel to the belt22of the CVT, the clutch13is disengaged and the driving power is not permitted to be transmitted from the drive wheel to the belt22. In this way, the belt22can be protected from an excessive load.

In the belt protection control, the driving power of the engine EG is suppressed (reduced). In the belt protection control, the driving power of the engine EG is compensated to be reduced compared to a state in which the belt protection control is not performed. In accordance with this control, in a case where an excessive load will be (is likely to be) transmitted from the drive wheel to the belt22of the CVT, the driving power transmitted from the engine EG to the belt22is suppressed (reduced). Therefore, the belt22of the CVT can be protected from an excessive load. In the belt protection control, only the control for disengaging the clutch13by the clutch actuator47may be performed, or only the control for suppressing the driving power of the engine EG may be performed.

FIG. 4is a timing chart of the belt protection control performed by the controller60ofFIG. 3. As shown inFIG. 4, in a case where the excessive load detecting section73detects that the drive wheel starts to shift from a spin state to a gripping state, the belt protection control section74initiates the belt protection control. For example, in a case where the excessive load detecting section73detects that the slip ratio SL has exceeded the start threshold Thl and then has been reduced, the belt protection control section74initiates the belt protection control. Specifically, the belt protection control section74directs the clutch actuator47to disengage the clutch13, and directs the engine EG to suppress (reduce) the driving power of the engine EG In the belt protection control, only one of disengagement of the clutch13and suppressing the driving power of the engine EG may be performed (either disengagement of the clutch13or suppressing the driving power of the engine EG may be performed).

In a case where the excessive load detecting section73detects that shifting of the drive wheel from the spin state to the gripping state is completed, the belt protection control section74terminates the belt protection control. For example, in a case where the excessive load detecting section73detects that the slip ratio SL has exceeded the start threshold Thl and then has fallen below a termination threshold Th2, the belt protection control section74terminates the belt protection control. Although the termination threshold Th2is smaller than the start threshold Th1, the termination threshold Th2may be equal to the start threshold Thl. Specifically, the belt protection control section74may direct the clutch actuator47to gradually engage the clutch13so that the clutch13is shifted from a fully disengaged state to a completely engaged state through a semi-clutch state. In addition, the belt protection control section74directs the engine EG to gradually reduce the amount of the engine power to be suppressed (reduced), to zero.

In accordance with the above-described configuration, the clutch13is disengaged in a case where an excessive load will be (is likely to be) transmitted from the drive wheel to the belt22of the CVT. Therefore, the belt22of the CVT can be protected from an excessive load. As a result, a frequency of change of the belt22can be reduced. Alternatively, the belt protection control section74may terminate the belt protection control when a predetermined lag time has passed, after the excessive load detecting section73detected that shifting of the drive wheel from the spin state to the gripping state is completed. Further, the belt protection control section74may make a difference between a time point when the belt protection control performed by disengaging the clutch13is terminated and a time point when the belt protection control performed by suppressing (reducing) the engine driving power is terminated.

FIG. 5is a horizontal sectional view of a driving power transmission structure110of a utility vehicle according to Embodiment 2. The constituents which are the same as those of Embodiment 1 are designated by the same reference symbols and will not be described. As shown inFIG. 5, in Embodiment 2, in the driving power transmission structure110in which the rotational driving power of the engine EG is transmitted to the drive wheels (the front wheels3and/or the rear wheels4), the rotational driving power of the crankshaft17of the engine EG is transmitted to the CVT, the MT and the drive shaft12in this order, and a clutch113is disposed between a driven pulley121of the CVT and an output shaft119of the CVT.

A fixed sheave129and a movable sheave130of the driven pulley121are fitted to the output shaft119in such a manner that the fixed sheave129and the movable sheave130are rotatable relative to the output shaft119. The clutch113is a friction clutch (e.g., multi-disc clutch) as in Embodiment 1. An outer peripheral member143(input member) of the clutch113is secured to the fixed sheave129in such a manner that the outer peripheral member143is rotatable together with the driven pulley121. An inner peripheral member142(output member) of the clutch113is spline-coupled to the end portion of the output shaft119in such a manner that the inner peripheral member142is rotatable together with the output shaft119.

The friction plate44is provided on the outer peripheral portion of the inner peripheral member142and is axially movable. The opposing plate45is provided on the inner peripheral portion of the outer peripheral member143and is axially movable. A pressure member142ais provided at the outer peripheral portion of the inner peripheral member142to face an assembly of the friction plate44and the opposing plate45so that the pressure member142ais able to press the assembly of the friction plate44and the opposing plate45in the axial direction and move away from the assembly in the axial direction. The inner peripheral member142is biased by a biasing spring148so that the clutch113is engaged. In a state in which the pressure member142aof the inner peripheral member142is kept to press the assembly of the friction plate44and the opposing plate45by a spring force applied by the biasing spring148in a state in which a clutch actuator147is not applying a force to the pressure member142a.

The output shaft119has a tubular shape. A clutch rod190is slidably inserted into a hollow space of the output shaft119. The tip end portion of the clutch rod190faces the center portion of the inner peripheral member142in such a manner that the tip end portion is able to press the center portion. More specifically, the clutch rod190presses the inner peripheral member142in the axial direction. This causes the pressure member142ato move away from the assembly of the friction plate44and the opposing plate45. As a result, the clutch113is disengaged.

The clutch actuator147includes a hydraulic cylinder149, and the hydraulic control unit51which is capable of feeding a hydraulic pressure (oil pressure) to the hydraulic cylinder149. A piston150of the hydraulic cylinder149is secured to the clutch rod190. In this structure, the hydraulic control unit51controlled by the controller60feeds the hydraulic pressure to the hydraulic cylinder149so that the piston150advances the clutch rod190. In this way, the clutch113is disengaged.

As described above, the clutch113is disposed in the driving power transmission path at a location that is between the belt22of the CVT and the drive shaft12. In a case where an excessive load is likely to be transmitted from the drive wheel to the belt22of the CVT, the clutch113is disengaged. In this way, the belt22of the CVT can be protected from an excessive load. Since the clutch113is disposed in the CVT accommodating space51, the members can be arranged densely. The other constituents of Embodiment 2 are the same as those of Embodiment 1 and will not be described in repetition.