Patent ID: 12228178

DETAILED DESCRIPTION OF EMBODIMENTS

Hereinafter, a vehicle1according to an embodiment of the present disclosure will be described with reference to the accompanying drawings. Note that the following description is merely exemplary in nature, and is not intended to limit the present disclosure, its application, or its use.

In the following description, the front-rear direction, the left-right direction, and the up-down direction as viewed from the driver are referred to as the front-rear direction, the left-right direction, and the up-down direction of the vehicle and each component.

FIG.1is a plan view illustrating a schematic configuration of the vehicle1. As illustrated inFIG.1, a vehicle1includes left and right front wheels2disposed at a front end portion of a vehicle body9and left and right rear wheels3disposed at a rear end portion of the vehicle body9. A riding space R of the vehicle1is provided with an accelerator pedal7to be depressed by a driver and a display5that displays various types of information such as a vehicle speed and an engine speed.

The vehicle1also includes an engine10as a driving source, a transmission21, and a clutch30. In the present embodiment, the transmission21is disposed behind the engine10. The clutch30is disposed on the left side of the transmission21. A rear differential device23for the rear wheels3is disposed on the rear side of the transmission21. A two-wheel-drive and four-wheel-drive switch24is disposed on the right side of the transmission21. A front differential device25for the front wheels2is disposed between the left and right front wheels2.

The two-wheel-drive and four-wheel-drive switch24switches the driving state between a four-wheel drive state in which the driving force shifted by the transmission21is transmitted to the front wheel2side in addition to the rear wheel3side and a two-wheel drive state in which the power transmission to the front wheel2side is interrupted and only the rear wheel3side is driven. That is, in the present embodiment, the rear wheels3are configured as driving wheels in the two-wheel drive state, and the front wheels2and the rear wheels3are configured as driving wheels in the four-wheel drive state.

The driving force output from the engine10is input to the transmission21via the clutch30, and is changed to a gear ratio corresponding to the drive state in the transmission21. The driving force shifted in the transmission21is distributed to the left and right rear wheels3via the rear differential device23. In the four-wheel drive state, the driving force output from the two-wheel-drive and four-wheel-drive switch24is also distributed to the left and right front wheels2via the front differential device25. That is, a driving force transmission path from the engine10to the driving wheels2and3via the clutch30and the transmission21is configured.

In the present embodiment, the engine10is a gasoline engine disposed such that a crankshaft11as an output shaft is oriented in the vehicle width direction. The engine10may be a single-cylinder engine, a multi-cylinder engine, or a diesel engine. The engine10includes a throttle valve12that adjusts an intake air amount. The opening degree of the throttle valve12is electronically controlled by a controller50described later.

The rotation of the crankshaft11is transmitted to a clutch drive shaft40of the clutch30via a power transmission mechanism16. The power transmission mechanism16includes a drive gear13integrally rotatably attached to the crankshaft11, a driven gear15integrally rotatably attached to the clutch drive shaft40that is an input shaft to the clutch30, and an idle gear14disposed between the drive gear13and the driven gear15and meshing with the drive gear13and the driven gear15. That is, the rotation of the crankshaft11is transmitted to the clutch drive shaft40via the drive gear13, the idle gear14, and the driven gear15.

FIG.2is a cross-sectional view of the clutch30taken along the clutch drive shaft40, illustrating a schematic configuration of the clutch30. As illustrated inFIG.2, the clutch30includes an outer drum31provided so as to be rotatable integrally with the clutch drive shaft40, and an inner hub32provided on the inner peripheral side of the outer drum31and provided so as to be rotatable integrally with the transmission input shaft22of the transmission21.

The outer drum31is formed in a cylindrical shape. A plurality of first friction plates33, which are movable in an axial direction O1of the clutch30and provided to be integrally rotatable in the circumferential direction with the outer drum31, are spline-fitted to the inner peripheral portion of the outer drum31.

The inner hub32is formed in a cylindrical shape. A plurality of second friction plates34, which are movable in the axial direction O1of the clutch30and provided to be integrally rotatable in the circumferential direction with the inner hub32, are spline-fitted to the outer peripheral portion of the inner hub32. The plurality of first friction plates33and the plurality of second friction plates34(hereinafter, may be collectively referred to as a plurality of friction plates46) are alternately arranged in the axial direction O1. The inner hub32has a stopper32afacing the plurality of friction plates46from the right side.

The clutch30further includes a piston35provided to be movable in the axial direction O1, a piston chamber36that generates a hydraulic pressure for moving the piston35in the axial direction O1, and a spring37that biases the piston35to the opposite side against the hydraulic pressure. In the present embodiment, the piston35is located on the left side of the plurality of friction plates46, and biases the plurality of friction plates46to the right side by the hydraulic pressure applied from the piston chamber36. The spring37is located on the right side of the piston35and biases the piston35to the left side.

The clutch drive shaft40is formed with a first oil passage41and a second oil passage42, each extending in the axial direction O1. The first oil passage41communicates with the piston chamber36. The second oil passage42communicates with a space in which the plurality of friction plates46are accommodated.

The clutch30further includes, for example, an oil pump38rotationally driven by the clutch drive shaft40and an oil control valve39attached to a left end portion of the clutch drive shaft40. The oil discharged from the oil pump38is supplied to the second oil passage42via the line pipe47.

The oil supplied to the second oil passage42is supplied to the plurality of friction plates46to cool the plurality of friction plates46, and also acts as lubricating oil for reducing friction between the plurality of friction plates46when the friction plates are not completely fastened. The oil supplied to the plurality of friction plates46is collected in an oil receiver44via a drain pipe43. The oil stored in the oil receiver44is sucked up to the oil pump38via a strainer45.

Oil is supplied to the oil control valve39through a branch pipe48branched from a line pipe47. The oil control valve39is a linear control valve whose operation is electrically controlled by a controller50to continuously change the hydraulic pressure of the supplied oil. The oil whose hydraulic pressure is adjusted by the oil control valve39is supplied to the piston chamber36via the first oil passage41.

As a result, the piston35receives a force corresponding to the hydraulic pressure in the piston chamber36and moves to the right. Therefore, when the piston35moves to the right side, the plurality of friction plates46are sandwiched between the piston35and the stopper32aand are fastened with a load corresponding to the hydraulic pressure in the piston chamber36. On the other hand, when the force acting on the piston35by the hydraulic pressure is weaker than the biasing force by the spring37, the piston35moves to the left side and the fastening of the plurality of friction plates46is released.

Therefore, the oil control valve39, the first oil passage41, the piston chamber36, and the piston35constitute a clutch actuator70that applies a fastening load to the clutch30and provides a torque transmission capacity according to the fastening load. The clutch30is configured as a multiple disc hydraulic clutch configured to be switchable by the clutch actuator70to an arbitrary fastening position between a connection state that enables transmission of the driving force between the engine10and the transmission21and a disconnection state that disconnects the transmission.

The clutch30can be controlled by the clutch actuator70to the half-clutch state in which connection of the clutch30is not completely connected, whereby the half-clutch operation, for example, at the time of starting the vehicle1and at the time of shifting the transmission21, can be automated. That is, the clutch30is a so-called automatic clutch.

Here, for example, there may be a case where it is difficult to rotate the driving wheel even if the vehicle1tries to start, such as a case where the driving wheel is fitted in the recess and stops, a case where the vehicle1stops on a steep slope, and the like. In that case, when the clutch30is brought into a connected state, the rotation of the engine10is stopped by the driving wheel that is stopped, so that the half-clutch operation by the clutch actuator70cannot be completed. As a result, the temperature of the plurality of friction plates46may rise due to frictional heat generated between the friction plates46, and the friction plates46may be seized. Therefore, the vehicle1according to the present disclosure includes the controller50that performs clutch protection control for preventing the seizure.

FIG.3is a diagram schematically illustrating a control system90related to the clutch protection control of vehicle1. As illustrated inFIG.3, the control system90includes the controller50, an input device91, and an output device92. The controller50determines the necessity of the clutch protection control on the basis of the signal from the input device91, and controls the operation of the output device92related to the clutch protection control on the basis of the determination result.

Referring also toFIGS.1and2, the input device91includes an engine speed sensor61, a vehicle speed sensor62, a clutch oil temperature sensor63, and an accelerator opening sensor64. The engine speed sensor61is provided in the engine10and detects the speed of the crankshaft11. The vehicle speed sensor62is provided in the transmission21and detects the rotation speed of an output shaft (not illustrated) output from the transmission21. The clutch oil temperature sensor63is provided in the drain pipe43and measures the temperature of the clutch oil flowing through the drain pipe43. The accelerator opening sensor64is provided on the accelerator pedal7and detects a driver's operation of depressing the accelerator pedal7.

The output device92includes the throttle valve12as a device for controlling the operating state of the engine20, specifically, a device for controlling the engine speed N, the oil control valve39as a device for controlling the operation of the clutch actuator70, and the display5as a notifier for notifying a display related to the clutch protection control. In addition, as the notifier, a display lamp and/or a speaker may be provided instead of or in addition to the display5.

The controller50includes a memory51that is a storage device and a processor52that is an arithmetic processing device. The memory51stores various data and programs related to the clutch protection control.

Functions implemented by the components described in the present specification may be implemented in a circuitry or processing circuitry, including a general purpose processor, an application specific processor, an integrated circuit, an application specific integrated circuit (ASICs), a central processing unit (CPU), a conventional circuit, and/or combinations thereof, programmed to implement the described functions. The processor includes a transistor and other circuits, and is regarded as circuitry or processing circuitry. The processor may be a programmed processor that executes a program stored in a memory. In the present specification, the circuitry, the unit, and the means are hardware programmed to realize the described functions or hardware executing the functions. The hardware may be any hardware disclosed herein or any hardware programmed or known to perform the described functions. In a case where the hardware is a processor regarded as a type of circuitry, the circuitry, means, or unit is a combination of hardware and software used to configure the hardware and/or the processor.

The processor52includes a current clutch temperature estimation circuit53, a driving force adjustment circuit54, a drive source control circuit55, a clutch actuator control circuit56, a differential rotation speed detection circuit57, and a notifier control circuit58, as circuits that realize each function related to the clutch protection control.

The current clutch temperature estimation circuit53estimates the temperature of clutch30, for example, the current temperature of the plurality of friction plates46. In the present embodiment, the current clutch temperature estimation circuit53estimates the temperature of the clutch30on the basis of a calorific value Q1generated in the clutch30, a heat release amount Q2radiated from the clutch30, and a heat capacity C of the clutch30. Hereinafter, the estimated current temperature of the clutch30may be referred to as a clutch estimated temperature TCL.

The calorific value Q1can be calculated on the basis of, for example, the clutch transmission torque acting on the plurality of friction plates46and the differential rotation speed that is a difference between the rotation speed on the upstream side (that is, the clutch drive shaft40) and the rotation speed on the downstream side (that is, the transmission input shaft22) of the driving force transmission path in the clutch30. For example, the calorific value Q1may be calculated by further correcting a value based on the clutch transmission torque and the differential rotation speed with use of a heat generation coefficient k1.

The clutch transmission torque can be calculated, for example, on the basis of the pressing force of the piston35generated by the hydraulic pressure acting on the piston chamber36, the area of the abutment region where the plurality of friction plates46abut on each other, and the radial position from the central axis O1. The differential rotation speed can be detected by the differential rotation speed detection circuit57as described later. The heat generation coefficient k1can be determined by, for example, an experiment. The clutch transmission torque means a torque that can be transmitted by the clutch, and may also be referred to as a torque transmission capacity in the present specification.

The heat release amount Q2can be calculated on the basis of, for example, the clutch estimated temperature TCLcalculated immediately before and the temperature of the clutch oil. For example, the heat release amount Q2may be calculated by further correcting the value based on the clutch estimated temperature TCLcalculated immediately before and the temperature of the clutch oil, with use of the heat release coefficient k2. The temperature of the clutch oil can be measured by the clutch oil temperature sensor63. The heat release coefficient k2can be determined by, for example, an experiment.

The driving force adjustment circuit54determines the opening degree of the throttle valve12in order to perform driving force adjustment control for adjusting the driving force transmitted to the downstream side of the clutch30on the basis of the clutch estimated temperature TCL. For example, when the estimated temperature of the clutch30is larger than the predetermined threshold T1, the driving force adjustment circuit54determines the opening degree of the throttle valve12in order to perform the driving force adjustment control. The threshold T1is set, for example, as a value with a margin with respect to the temperature at which seizure of the clutch30immediately occurs.

For example, when the clutch estimated temperature TCLis larger than the predetermined threshold T1, the driving force adjustment circuit54determines the throttle opening degree to be a closed-side throttle opening degree adjusted in the closing direction with respect to the user requested throttle opening degree according to the accelerator opening degree detected by the accelerator opening sensor64so as to reduce the driving force of the engine10.

In the present embodiment, as illustrated inFIG.6, the driving force adjustment circuit54obtains a correction gain value G at the clutch estimated temperature TCLon the basis of a correction gain function G(T), and determines the closed-side throttle opening amount by multiplying the user requested throttle opening amount by the correction gain value G. In the present embodiment, the correction gain function G(T) is set such that the correction gain function G(T) is 1 when the temperature T of the clutch oil is equal to or lower than the threshold T1, decreases linearly when the temperature T exceeds the threshold T1, and is 0 when the temperature T becomes equal to or higher than a threshold T2. The threshold T2is set to a temperature at which seizure of the clutch30is likely to occur when the temperature of the clutch30exceeds T2, for example.

The drive source control circuit55controls the throttle valve12so as to realize a throttle valve opening amount corresponding to the accelerator opening degree detected by the accelerator opening sensor64. However, when the throttle valve opening amount is determined by the driving force adjustment circuit54, the throttle valve12is controlled so as to realize the determined throttle valve opening amount.

The clutch actuator control circuit56controls the operation of the clutch actuator70so as to realize a clutch transmission torque that is balanced with the engine torque output from the engine10. Specifically, the clutch actuator control circuit56controls the operation of the oil control valve39to adjust the hydraulic pressure of the clutch oil supplied to the piston chamber36, thereby generating a predetermined fastening load on the plurality of friction plates46via the piston35to realize the clutch transmission torque balanced with the engine torque.

Further, the clutch actuator control circuit56performs the half-clutch control when the vehicle1starts and when the transmission21shifts. In the half-clutch control, the oil control valve39first adjusts the hydraulic pressure of the clutch oil so that the clutch transmission torque in the clutch30is lower than the engine torque, and then gradually increases after the rotations of the plurality of friction plates46are synchronized, to finally achieve the clutch transmission torque balanced with the engine torque.

The differential rotation speed detection circuit57detects a rotation speed difference that is a difference between the rotation speed of the clutch drive shaft40and the rotation speed of the transmission input shaft22. The differential rotation speed detection circuit57calculates the rotation speed of the clutch drive shaft40on the basis of the rotation speed of the crankshaft11detected by the engine speed sensor61and a gear ratio by power transmission via the drive gear13, the idle gear14, and the driven gear15. The differential rotation speed detection circuit57calculates the rotation speed of the transmission input shaft22on the basis of the rotation speed of the output shaft of the transmission21detected by the vehicle speed sensor62and the gear ratio in the transmission21corresponding to the current gear.

The notifier control circuit58causes the display5to display that the clutch protection control is being executed, that is, that the driving force adjustment control is being executed, to notify the driver.

Next, the flow of the clutch protection control will be described with reference to the flowchart illustrated inFIG.4and the subroutine illustrated inFIG.5. A series of procedures in the flowchart ofFIG.4and the subroutine ofFIG.5is repeatedly executed at a predetermined control cycle.

First, referring toFIG.4, the controller50determines whether the vehicle speed is 0 on the basis of a value detected by the vehicle speed sensor62(step S001). When the vehicle speed is 0 (YES in step S001), the controller50determines whether the accelerator pedal7is depressed on the basis of the value detected by the accelerator opening sensor64(step S002). When the depression operation of the accelerator pedal7is determined (YES in step S002), the drive source control circuit55and the clutch actuator control circuit56perform start control (step S003). In the case where step S001is NO and in the case where step S002is NO, the clutch protection control is not executed, and the processing in this flowchart ends.

In the start control in step S003, the opening degree of the throttle valve12is controlled by the drive source control circuit55so that the engine10outputs the engine torque corresponding to a detected accelerator opening degree, and the half-clutch control is performed by the clutch actuator control circuit56.

Next, the differential rotation speed detection circuit57detects the differential rotation speed of the clutch30(step S004). In step S005, it is determined whether the differential rotation speed is not 0. When the differential rotation speed is not 0 (YES in step S005), the clutch30is not in the connected state, and the process proceeds to step S006. On the other hand, when the differential rotation speed is 0 (NO in step S005), it is determined that the clutch30is in the connected state, and in this case, the frictional heat between the plurality of friction plates46in the clutch30does not increase, so that the clutch protection control will not be executed and the process in this flowchart ends.

In step S006, the current clutch temperature estimation circuit53calculates the clutch estimated temperature TCLthat is the current estimated temperature of the clutch30. In step S007, it is determined whether the clutch estimated temperature TCLexceeds a predetermined threshold T1. When the clutch estimated temperature TCLexceeds the predetermined threshold T1(YES in step S007), the process proceeds to step S100to perform the clutch protection control. On the other hand, when the clutch estimated temperature TCLis equal to or lower than the predetermined threshold T1(NO in step S007), the clutch protection control is not executed, and the process in this flowchart ends.

As shown inFIG.5, in the clutch protection control, first, in step S101, the driving force adjustment circuit54calculates a correction gain value G of the throttle opening degree on the basis of the clutch estimated temperature TCL, and corrects the throttle valve opening amount on the basis of the correction gain value G. Next, in step S102, the drive source control circuit55controls the operation of the throttle valve12so that the corrected throttle valve opening amount is obtained.

Next, the clutch actuator control circuit56calculates the engine torque output from the engine10on the basis of the corrected throttle valve opening amount (step S103), calculates the hydraulic pressure of the clutch oil so as to realize the clutch transmission torque balanced with the engine torque (step S104), controls the oil control valve39so as to realize the calculated hydraulic pressure of the clutch oil (step S105), and ends the processing in this subroutine.

Returning toFIG.4, the notifier control circuit58causes the display5to display that the clutch protection control is being executed (step S009).

Then, in step S010, the current clutch temperature estimation circuit53calculates the clutch estimated temperature TCLthat is the current estimated temperature of the clutch30. In step S011, it is determined whether the clutch estimated temperature TCLis equal to or lower than a predetermined threshold T1. When the clutch estimated temperature TCLstill exceeds the predetermined threshold T1(NO in step S011), the differential rotation speed detection circuit57detects the differential rotation speed (step S012) and determines whether the differential rotation speed is 0 (step S013).

When the differential rotation speed is not 0 (NO in step S013), the process returns to S100and the clutch protection control is repeated. When the clutch estimated temperature TCLis equal to or lower than the threshold T1(YES in step S011) or when the differential rotation speed is 0 (YES in step S013), the clutch protection control ends (step S014), and the process proceeds to step S015. In step S015, the notifier control circuit58ends the display on the display5indicating that the clutch protection control is being executed.

That is, when the heat generation in the clutch30is suppressed by the clutch protection control and the temperature of the clutch30becomes equal to or lower than the threshold T1, or when the clutch30is fastened and the frictional heat between the plurality of friction plates46is no longer increased, the seizure of the clutch30is suppressed, and thus the clutch protection control is terminated.

The vehicle1according to the above-described embodiment has the following effects.

(1) The vehicle1according to the present disclosure includes:the engine10;the front wheel2and the rear wheel3driven by a driving force output from the engine10;the clutch30disposed on a driving force transmission path between the engine10and the front wheel2and the rear wheel3, the clutch being switchable to an arbitrary fastening position between a connection state that enables transmission of the driving force therebetween and a disconnection state that disconnects the transmission; andthe clutch actuator70that applies a fastening load to the clutch30and provides a torque transmission capacity corresponding to the fastening load to the clutch30; andthe controller50that controls operation of the engine10and operation of the clutch actuator70.

The controller50includes:the current clutch temperature estimation circuit53that estimates a current temperature of the clutch30; andthe driving force adjustment circuit54that performs driving force adjustment control to adjust the driving force transmitted to the downstream side of the clutch30on the basis of the estimated clutch estimated temperature TCL.

As a result, the driving force transmitted to the downstream side of the clutch30is limited on the basis of the clutch estimated temperature TCL, so that the clutch30is prevented from being seized.

(2) Further, in the vehicle1according to the present disclosure,the driving force adjustment circuit54performs driving force adjustment control when the vehicle1starts.

As a result, the driving force adjustment control is performed at the start of the vehicle1in which the temperature of the clutch30is likely to rise.

(3) Further, in the vehicle1according to the present disclosure,the controller50further includes the clutch actuator control circuit56that controls operation of the clutch actuator70.

The clutch actuator control circuit56performs half-clutch control in which the fastening position of the clutch30is set to the half-clutch when the vehicle1starts.

As a result, the clutch30can be automatically controlled to the half-clutch state.

(4) Further, in the vehicle1according to the present disclosure,the driving force adjustment circuit54performs driving force adjustment control when the half-clutch control is performed.

As a result, the driving force adjustment control is performed in the half-clutch state in which the temperature of the clutch30is likely to rise.

(5) Further, in the vehicle1according to the present disclosure,in the driving force adjustment control, the driving force adjustment circuit54adjusts the power of the engine10.

As a result, the temperature rise of the clutch30is suppressed. When the power of the engine10is limited, the rotation speed of the engine10decreases, so that the differential rotation speed decreases, whereby the calorific value in the clutch30decreases. In addition, the fastening load of the clutch30may be limited, and in that case, the friction in the clutch30decreases, and thus the calorific value in the clutch30also decreases.

(6) Further, in the vehicle1according to the present disclosure,in the driving force adjustment control, the driving force adjustment circuit54may adjust both the power of the engine10and the fastening load by the clutch actuator70.

As a result, the temperature rise of the clutch30is further suppressed by the synergistic effect of the decrease in the calorific value in the clutch30due to the decrease in the rotation speed accompanying the decrease in the power of the engine10and the decrease in the calorific value in the clutch30due to the decrease in the fastening load of the clutch30.

(7) Further, in the vehicle1according to the present disclosure,in the driving force adjustment control, the driving force adjustment circuit54adjusts the driving force transmitted to the downstream side of the clutch30when the clutch estimated temperature TCLexceeds the predetermined threshold T1.

As a result, since the power of the vehicle1is limited when the temperature of the clutch30exceeds the predetermined threshold T1, it is easy to prevent seizure of the clutch30.

(8) Further, in the vehicle1according to the present disclosure,regarding the driving force adjustment control, the driving force adjustment circuit54cancels the driving force adjustment control when the clutch estimated temperature TCLbecomes equal to or lower than the predetermined threshold T1or when the starting of the vehicle1is completed. Completion of the starting of the vehicle1is determined by confirming that the differential rotation speed is zero. In place of or in addition to the determination on the basis of the differential rotation speed, it may be determined that the starting of the vehicle1is completed on the basis of the detection result by the vehicle speed sensor62.

As a result, the clutch30is prevented from being seized when the clutch estimated temperature TCLis less than the predetermined threshold T1, and the half-clutch state of the clutch30is not continued after the start of the vehicle1is completed, so that the clutch30is prevented from being seized due to the temperature rise of the clutch30. Therefore, the driving force adjustment control is prevented from being unnecessarily performed while the seizure of the clutch30is prevented.

(9) Further, in the vehicle1according to the present disclosure,the current clutch temperature estimation circuit53estimates the temperature of clutch30on the basis of at least the clutch transmission torque, the differential rotation speed in clutch30, and the temperature of the clutch oil.

As a result, it is easy to accurately estimate the temperature of the clutch30on the basis of at least the clutch transmission torque, the differential rotation speed, and the temperature of the clutch oil.

(10) Further, in the vehicle1according to the present disclosure,the current clutch temperature estimation circuit53may estimate the temperature of the clutch30on the basis of the temperature of the clutch oil.

For example, the current clutch temperature estimation circuit53may acquire the correlation between the temperature of the clutch oil and the temperature of the clutch30by experiment, and estimate the temperature of the clutch30by calculation on the basis of the temperature of the clutch oil or by referring to a table prepared in advance.

As a result, it is easy to accurately estimate the temperature of the clutch30on the basis of the temperature of the clutch oil.

(11) Further, in the vehicle1according to the present disclosure,the current clutch temperature estimation circuit53estimates the temperature of the clutch30on the basis of an estimated calorific value in the clutch30, and an estimated heat release amount from the clutch30.

As a result, the temperature of the clutch30can be easily estimated more accurately on the basis of the calorific value in the clutch30and the heat release amount from the clutch30.

(12) Further, the vehicle1according to the present disclosure further includesa display5, andthe controller50further includes the notifier control circuit58that causes the display5to notify that the driving force adjustment control is being executed when the driving force adjustment control is being executed.

As a result, it is easy to notify the driver that the driving force adjustment control is being executed via the display5.

Further, another aspect of the present disclosure isa method for controlling a vehicle,the vehicle including:the engine10;the front wheel2and the rear wheel3driven by the driving force output from the engine10;the clutch30disposed on a driving force transmission path between the engine10and the front wheel2and the rear wheel3, the clutch being switchable to an arbitrary fastening position between a connection state that enables transmission of the driving force therebetween and a disconnection state that disconnects the transmission;the clutch actuator70that applies a fastening load to the clutch30and provides a torque transmission capacity corresponding to the fastening load to the clutch30; andthe controller50that controls operation of the engine10and operation of the clutch actuator70.

The method includes:estimating the current temperature of the clutch30; andadjusting the driving force transmitted to the downstream side of the clutch30on the basis of the estimated temperature of the clutch30.

Further, still another aspect of the present disclosure is a controller for a vehicle,the vehicle including:the engine10;the front wheel2and the rear wheel3driven by the driving force output from the engine10;the clutch30disposed on a driving force transmission path between the engine10and the front wheel2and the rear wheel3, the clutch being switchable to an arbitrary fastening position between a connection state that enables transmission of the driving force therebetween and a disconnection state that disconnects the transmission; andthe clutch actuator70that applies a fastening load to the clutch30and provides a torque transmission capacity corresponding to the fastening load to the clutch30.

The controller50includes:a current clutch temperature estimation circuit53that estimates the temperature of the clutch30; anda driving force adjustment circuit54that performs driving force adjustment control to adjust the driving force transmitted to the downstream side of the clutch30on the basis of the estimated temperature of the clutch30.

In the above embodiment, the clutch protection control is performed on the basis of the clutch estimated temperature TCLestimated by the current clutch temperature estimation circuit53. Alternatively or additionally, the clutch protection control may be performed in the case where a predicted clutch temperature that is a future temperature of the clutch30is predicted and it is predicted that the predicted clutch temperature exceeds the predetermined threshold T1. That is, as illustrated inFIG.3, in order to predict the predicted clutch temperature, a future clutch temperature prediction circuit59indicated by a two-dot chain line may be provided in the controller50.

For example, the future clutch temperature prediction circuit59may estimate the future temperature of the clutch30on the basis of the transition of the temperature of the clutch30estimated by the current clutch temperature estimation circuit53.

In the above embodiment, the clutch actuator70is configured to adjust the clutch fastening load by hydraulic pressure using the oil control valve39, but any actuator may be used. For example, the fastening load may be adjusted by adjusting the position of the piston35by a moving mechanism using a motor, a ball screw, or the like.

In the above embodiment, the case where the drive source is the engine10has been described as an example, but any drive source such as an electric motor can be used.

In the above embodiment, the driving force adjustment circuit54is configured to adjust the power of the engine10by adjusting the opening degree of the throttle valve12, but the power of the engine10may be adjusted by adjusting the ignition timing, the fuel injection timing, the fuel injection amount, and the like. The driving force adjustment circuit54may be configured only to adjust, specifically, only to decrease, the clutch fastening load of the clutch actuator70. By reducing the clutch fastening load, frictional heat that can be generated between the plurality of friction plates46can be reduced.

Various modifications and alterations can be made without departing from the scope of the present disclosure.