Control device for vehicle differential motion limiting clutch

Abstract

To provide a control device for a vehicle differential motion limiting device that suppresses sliding of a differential motion limiting clutch, and heat generation or durability reduction caused by such sliding.SOLUTION: With an electronic control device 60, when a differential motion occurs on right and left driving wheels 16, 18 because of occurence of sliding of a differential limitation clutch 46 exceeding a torque capacity of the differential motion limiting clutch 46, a pressing load (engagement pressure) on the differential motion limiting clutch 46 is reduced and a differential motion limiting torque is reduced during braking of either of the driving wheels 16, 18 with either of wheel brakes 52, 54. By doing so, sliding of the differential motion limitation clutch 46, heat generation and durability reduction caused by such sliding are suppressed when the driving wheel on the high torque side of the driving wheels 16, 18 is braked using either of the wheel brakes 52, 54.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a control device for a differential limiting clutch for a vehicle, which suppresses heat generation in a differential limiting clutch used to limit differential rotation in a differential gear device of a vehicle. [Background technology]

[0002] In a vehicle equipped with a differential gear device provided between left and right drive shafts and distributing drive torque transmitted from a drive source to left and right drive wheels while allowing differential rotation between the left and right drive wheels, a differential limiting clutch that limits the differential between the left and right drive wheels, and a wheel brake device that controls the rotation speed of each of the drive wheels, a device has been proposed in which, when a sudden increase in drive torque transmitted from the drive source to the differential gear device exceeds the torque capacity of the differential limiting clutch and causes slippage in the differential limiting clutch, the drive torque transmitted to the drive wheel with a higher torque among the drive wheels is suppressed by using the wheel brake, thereby improving the straight-line stability of the vehicle. For example, the vehicle described in Patent Document 1 is one example. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2014-46727 A Summary of the Invention [Problem to be solved by the invention]

[0004] However, as described above, when the drive torque transmitted to the high torque side drive wheel among the drive wheels is suppressed by using the wheel brake, the slippage of the differential limiting clutch occurs, and the slippage may cause the differential limiting clutch to heat up or reduce its durability. Although it is considered that the slippage of the differential limiting clutch decreases while the wheel brake is operating, the slippage does not become zero completely, and a slight slippage continues. Since a large drive torque exceeding the torque capacity of the differential limiting clutch is transmitted and a slippage occurs, even a slight slippage has a relatively large effect on the slippage of the differential limiting clutch.

[0005] The present invention has been made against the background of the above circumstances, and its object is to provide a control device for a vehicle differential limiting device that can suppress the sliding of the differential limiting clutch and the resulting heat generation and decrease in durability. [Means for solving the problem]

[0006] In order to achieve the above-mentioned object, the gist of the present invention is (a) a control device for a vehicle differential limiting clutch that is provided between left and right drive shafts and distributes driving torque transmitted from a driving source to the left and right driving wheels while allowing a rotational difference between them, a differential limiting clutch that limits the differential between the left and right driving wheels, and a wheel brake device that controls the rotational speed of each of the driving wheels, and when the torque capacity of the differential limiting clutch is exceeded and slippage occurs in the differential limiting clutch and differential speed occurs between the left and right driving wheels, the control device uses the wheel brake to brake the driving wheel with the higher torque among the driving wheels, and (b) reduces the differential limiting torque of the differential limiting clutch while the driving wheels are being braked by the wheel brake. Effect of the Invention

[0007] In the case where the torque capacity of the differential limiting clutch is exceeded and slippage occurs in the differential limiting clutch, causing differential motion between the left and right drive wheels, the differential limiting torque of the differential limiting clutch is reduced while the drive wheels are being braked by the wheel brakes. This makes it possible to suppress slippage of the differential limiting clutch and the resulting heat generation and deterioration of durability when the drive wheel with a higher torque is braked by the wheel brake.

[0008] Preferably, the vehicle is equipped with a plurality of differential gear units, and the control device identifies the differential gear unit in which a differential is occurring based on the rotation speed of the drive wheels, and reduces the differential limiting torque of the differential limiting clutch only in the differential gear unit in which a differential is occurring, thereby making it possible to suppress a reduction in the transmitted driving force caused by releasing an unnecessary differential limiting clutch.

[0009] Preferably, the control device gradually reduces the differential limiting torque of the differential limiting clutch continuously or in a stepwise manner, thereby suppressing the generation of vehicle body vibrations and abnormal noise that accompany a sudden release of the differential limiting clutch.

[0010] Preferably, when reducing the differential limiting torque of the differential limiting clutch, the control device does not completely release the differential limiting clutch, but leaves a certain amount of differential braking torque. This makes the sudden increase in the differential and the change in wheel speed during the reduction of the differential limiting torque gentle, so that the operation of the wheel brakes used in combination is gentle, and the occurrence of discomfort is suppressed.

[0011] Preferably, the control device reduces the limiting differential torque of the limiting differential clutch on the condition that a differential rotation equal to or greater than a preset differential rotation judgment value occurs during braking of the drive wheels by the wheel brakes, but does not reduce the limiting differential torque of the limiting differential clutch when a differential rotation below the preset differential rotation judgment value occurs. As a result, when a differential rotation below the preset differential rotation judgment value occurs, the limiting differential torque of the limiting differential clutch is not reduced, so that driving can be continued without reducing the limiting differential torque of the limiting differential clutch, thereby suppressing a sudden decrease in the transmitted driving force.

[0012] Preferably, the control device reduces the differential limiting torque of the differential limiting clutch when the temperature of the differential limiting clutch is equal to or higher than a preset clutch temperature determination value during braking of the drive wheels by the wheel brakes, thereby suppressing heating of the differential limiting clutch and deterioration of its durability.

[0013] Preferably, the control device reduces the differential limiting torque of the differential limiting clutch when the time elapsed since the start of the operation of the wheel brakes exceeds a preset elapsed time determination threshold during braking of the drive wheels by the wheel brakes, thereby suppressing heating of the differential limiting clutch and deterioration of its durability.

[0014] Preferably, when the differential rotation of the differential gear device is increasing during braking of the drive wheels by the wheel brakes, the control device preferentially reduces the differential limiting torque of the differential limiting clutch. This prevents the combined use time of the differential limiting clutch control and the wheel brake control from becoming unnecessarily long or short depending on the differential rotation judgment value and the clutch temperature judgment value, thereby reducing the chance of slipping of the differential limiting clutch and loss of driving force. [Brief description of the drawings]

[0015] [Figure 1] 1 is a diagram illustrating a main part of a vehicle including a control device according to an embodiment of the present invention; [Diagram 2] 2 is a flowchart illustrating a main part of the control operation of the control device in the embodiment of FIG. 1. [Diagram 3] 2 is a time chart illustrating a main part of the control operation of the control device of FIG. 1. [Figure 4] 5 is a flowchart illustrating a main part of a control operation of a control device according to another embodiment of the present invention. [Diagram 5] 5 is a flowchart illustrating a main part of a control operation of a control device according to another embodiment of the present invention. [Figure 6] 6 is a time chart for explaining a main part of the control operation of the control device of FIG. 5. [Figure 7] 7 is a time chart illustrating the control operation of a conventional control device in comparison with FIG. 6. [Figure 8] 6 is a time chart illustrating a main part of another control operation of the control device of FIG. 5. [Figure 9] 9 is a time chart illustrating the control operation of a conventional control device in comparison with FIG. 8. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0016] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. Note that in the following embodiments, the drawings are appropriately simplified or modified, and the dimensional ratios and shapes of the various parts are not necessarily drawn accurately. EXAMPLES

[0017] 1 is a diagram illustrating a main part of a vehicle 10 to which the present invention is applied, and also a diagram illustrating a main part of a control system provided in the vehicle 10. The vehicle 10 is a FF vehicle, a FR vehicle, or a four-wheel drive vehicle.

[0018] In FIG. 1, a vehicle 10 includes a prime mover 12, such as an engine or an electric motor, a transmission 14 that changes the rotation speed of the prime mover 12, a pair of left and right drive wheels 16, 18, and a differential gear device 26 connected to the pair of left and right drive wheels 16, 18 via a pair of left and right drive shafts 20, 22.

[0019] The differential gear device 26 has a large bevel gear 30 that meshes with a small bevel gear 28 connected to the transmission 14 via the propeller shaft 24, a differential case 32 to which the large bevel gear 30 is fixed, and a pair of side gears 38, 40 that are provided in the differential case 32 and mesh with each other via a pinion 36 rotatably supported by a pinion shaft 34. The differential gear device 26 transmits driving torque transmitted from the transmission 14 via the propeller shaft 24 to a pair of left and right drive wheels 16, 18 that are connected to the pair of side gears 38, 40 via a pair of drive shafts 20, 22, respectively, while allowing differential rotation therebetween.

[0020] The differential limiting clutch 46 is provided in the differential gear unit 26 and limits the differential rotation between the pair of left and right drive shafts 20, 22 and the pair of left and right drive wheels 16, 18 connected thereto. The differential limiting clutch 46 is configured, for example, by stacking a plurality of fixed side friction plates 48 that are non-rotatably provided in the differential case 32 and rotating side friction plates 50 that rotate together with the drive shafts 22 in a staggered manner, and a pressing load is applied to the fixed side friction plates 48 and the rotating side friction plates 50 by an electric actuator (not shown) using an electric motor, which presses the fixed side friction plates 48 and the rotating side friction plates 50 against each other.

[0021] The wheels, i.e., the drive wheels 16, 18 of the vehicle 10 are provided with wheel brakes 52, 54 for controlling the rotation thereof, respectively. The wheel brakes 52, 54 and the aforementioned limited slip differential clutch 46 are controlled by an electronic control unit 60 which functions as a control unit for the vehicle 10.

[0022] The electronic control unit 60 includes a so-called microcomputer, and is configured to process input signals according to a pre-stored program. The electronic control unit 60 functionally includes a differential limiting clutch slip determination unit 62, a differential limiting clutch control unit 64, and a wheel brake control unit 66.

[0023] The differential limiting clutch slip judgment unit 62 calculates the differential rotational speed ΔNdf (rpm) of the differential gear device 26, which is the difference between the rotational speeds of the left and right drive wheels 16, 18 detected by the left and right wheel rotation sensors 68, 70, respectively, and judges whether the differential rotational speed ΔNdf is greater than or equal to a predetermined clutch slip judgment threshold value ΔNdf1.

[0024] The differential limiting clutch control unit 64 performs differential limiting control (basic control) to apply a predetermined pressure load from an electric actuator to the fixed side friction plate 48 and the rotating side friction plate 50 of the differential limiting clutch 46 to prevent a decrease in the driving force of the pair of driving wheels 16, 18 when one of the pair of driving wheels 16, 18 spins while the vehicle 10 is traveling on an icy road, a muddy road, or the like.

[0025] During such differential limiting control of the differential limiting clutch 46, if, for example, one of the drive wheels 16, 18 slips and a large torque is transmitted to the other, resulting in a large drive torque that exceeds the torque capacity of the differential limiting clutch 46 being transmitted, the straight-line running of the vehicle is impaired, so in order to suppress the torque of the other drive wheel, the wheel brake control unit 66 uses one of the wheel brakes 52, 54 to suppress the torque of the other drive wheel. However, during such wheel brake control, slight slippage occurs in the differential limiting clutch 46, which may cause heat generation or a decrease in durability of the differential limiting clutch 46.

[0026] In contrast, when the differential limiting clutch slippage determination unit 62 determines that slippage has occurred in the differential limiting clutch 46 during wheel brake control, and the wheel brake control unit 66 uses one of the wheel brakes 52, 54 to suppress the rotation of the wheel on the higher rotation (high torque) side of the pair of drive wheels 16, 18, the differential limiting clutch control unit 64 limits the differential limiting control of the differential limiting clutch 46. In other words, the differential limiting clutch 46 is released or the pressure load on the differential limiting clutch 46 is reduced.

[0027] FIG. 2 is a flow chart for explaining the main part of the control operation of the electronic control device 60. In FIG. 2, in step S1 (hereinafter, step is omitted), it is determined whether or not the differential limiting clutch control unit 64 is performing differential limiting control (LSD control). If the determination in S1 is negative, the routine is terminated, but if the determination is positive, in S2 corresponding to the differential limiting clutch slip determination unit 62, it is determined whether or not slippage has occurred in the differential limiting clutch 46 during the differential limiting control, based on whether or not the differential rotation speed ΔNdf (rpm) of the differential gear device 26 has become equal to or greater than a preset clutch slip determination threshold value ΔNdf1. If the determination in S2 is negative, in S3, the differential limiting control is continued. However, if the determination in S3 is positive, it is determined whether or not the rotation of the wheel on the high rotation (high torque) side of the pair of driving wheels 16, 18 is suppressed using one of the wheel brakes 52, 54. If the determination in S3 is negative, the differential limiting control is continued in S3, but if the determination is positive, the pressure load (engagement pressure) of the differential limiting clutch 46 is reduced in S5, and the differential limiting control is limited.

[0028] In the case where the vehicle 10 is provided with a plurality of differential gear units 26, such as a 4WD vehicle, the pressure load of the differential limiting clutch 46 is reduced and the differential limiting control is limited only for the differential gear units 26 among the plurality of differential gear units 26 that generate differential rotation even during the differential limiting control. This suppresses a reduction in the transmitted driving force due to unnecessary release of the differential limiting clutch 46. In addition, in the case where the differential gear units 26 provided with the differential limiting clutch 46 are provided only on the rear wheels among the differential gear units of the vehicle 10, if the brake control is operated due to the differential of the differential gear unit of the front wheels, this is determined, and the pressure load of the differential limiting clutch 46 of the rear wheels is not reduced, and normal clutch control is continued. In addition, in the case where the differential gear units 26 provided with the differential limiting clutch 46 are provided on the front and rear wheels of the vehicle 10, if the brake control is operated due to the differential of the differential gear unit of the front wheels, the pressure load of the differential limiting clutch 46 of the front wheels is reduced, but the normal control is continued for the rear wheels.

[0029] Fig. 3 shows a number of control modes in which the pressure load of the differential limiting clutch 46 is reduced in S5. Time t2 in Fig. 3 indicates the time point at which reduction in the pressure load (engagement pressure) of the differential limiting clutch 46 begins in response to the use of one of the wheel brakes 52, 54 to suppress rotation of the wheel on the higher rotation (high torque) side of the pair of drive wheels 16, 18. In Fig. 3, the solid line indicates an example in which the clutch pressure load during differential limiting control, which is shown as a constant value, is reduced to zero at time t2.

[0030] 3 shows an example in which the clutch pressure load during the differential limiting control, which is shown as a constant value, is gradually reduced to a certain remaining value at time t2. In this case, by reducing the clutch pressure load to the remaining value within a range that does not cause problems with the sliding of the differential limiting clutch 46, the sudden reduction in the amount of transmitted drive torque and the change in wheel speed during pressure load reduction control are made gradual, and the brake control operation of the wheel brake 52 or 54 used in combination can be made gradual.

[0031] 3 shows an example in which the clutch pressure load during the differential limiting control, which is shown as a constant value, is continuously decreased at a constant gradient from time t2. In this case, the generation of vehicle body vibrations and abnormal noises due to the sudden release of the differential limiting clutch 46 is suppressed, and a sudden change in vehicle behavior due to a sudden loss of drive torque caused by a sudden increase in the differential rotation of the differential limiting clutch 46 and a sudden change in vehicle behavior and abnormal noises caused by a sudden increase in the braking force of the brake control are suppressed.

[0032] According to the electronic control device 60 of this embodiment, when the torque capacity of the differential limiting clutch 46 is exceeded and slippage occurs in the differential limiting clutch 46, causing differential motion between the left and right drive wheels 16, 18, the pressing load (engagement pressure) of the differential limiting clutch 46 is reduced and the differential limiting torque is reduced during single braking of the drive wheels 16, 18 using one of the wheel brakes 52, 54. As a result, when the drive wheel with a higher torque out of the drive wheels 16, 18 is braked using one of the wheel brakes 52, 54, slippage of the differential limiting clutch 46 and the resulting heat generation and deterioration of durability are suppressed. EXAMPLES

[0033] Another embodiment of the present invention will be described below. In the following description, parts common to the above embodiment are designated by the same reference numerals and description thereof will be omitted.

[0034] Fig. 4 is a flowchart for explaining other essential control operations of the electronic control device 60. Fig. 4 differs from the flowchart in Fig. 2 in that S6, which is executed when the determination in S4 is positive, is provided between S4 and S5, but the rest is the same. The differences will be explained below.

[0035] 4, in S6, it is determined whether or not a predetermined condition for limiting the differential limiting control (LSD control) is satisfied (corresponding to an LSD control limiting condition) prior to the control of reducing the pressing load (engagement pressure) of the differential limiting clutch 46 in S5. This predetermined start condition is any one of (1) to (3). (1) One of the wheel brakes 52, 54 is used to suppress the rotation of the higher-rotation (high-torque) wheel of the pair of driving wheels 16, 18, but the differential rotation speed ΔNdf (rpm) of the differential gear device 26 has become equal to or greater than the predetermined clutch slip judgment threshold ΔNdf1. (2) The temperature Tc (° C.) of the differential limiting clutch 46 becomes equal to or higher than a preset heating determination threshold value Tc1. (3) The elapsed time te from the start of braking (brake control) of the wheel on the higher rotation (high torque) side by one of the wheel brakes 52, 54 becomes equal to or greater than a preset elapsed time determination threshold te1.

[0036] If the determination in S6 is negative, the differential limiting control is continued in S3, but if the determination is positive, the pressure load (engagement pressure) of the differential limiting clutch 46 is reduced in S5, and the differential limiting control is limited.

[0037] According to the electronic control device 60 of this embodiment, in addition to obtaining the same effect as in the above-described first embodiment, when the differential rotation speed ΔNdf (rpm) of the differential gear device 26 falls below the preset clutch slip judgment threshold value ΔNdf1 while the brake control is operating, normal differential limiting control can be continued without reducing the pressure load on the differential limiting clutch 46, thereby obtaining the effect of suppressing a decrease in the transmitted driving force. EXAMPLES

[0038] Fig. 5 is a flowchart for explaining other essential control operations of the electronic control device 60. Fig. 5 differs from the flowchart in Fig. 4 in that S7 and S8, which are executed when the determination in S4 is positive, are provided between S4 and S5, and S9, which determines whether the differential rotation speed ΔNdf of the differential gear device 26 is on the increase, is provided between S4 and S5, and S10, which similarly determines whether the differential rotation speed ΔNdf of the differential gear device 26 is on the increase, is provided between S8 and S5, but the rest are the same. The differences will be described below.

[0039] In S7, it is determined whether a predetermined condition A for limiting the differential limiting control (LSD control) is satisfied (corresponding to the LSD control limiting condition A). This condition A is a condition for transitioning to differential limiting by the differential limiting clutch 46 without being affected by an increase in the differential speed ΔNdf of the differential gear device 26, for example, that the temperature Tc (°C) of the differential limiting clutch 46 is equal to or higher than a preset heating judgment threshold Tc1. If the determination in S7 is positive, then in S5, the pressing load (engagement pressure) of the differential limiting clutch 46 is reduced and the differential limiting control is limited. However, if the determination in S7 is negative, then in S8, it is determined whether a predetermined condition B for limiting the differential limiting control (LSD control) is satisfied (corresponding to the LSD control limiting condition B). This condition B is, for example, that the elapsed time te from the start of braking (brake control) of the wheel on the high rotation (high torque) side by one of the wheel brakes 52, 54 is equal to or higher than a preset elapsed time judgment threshold te1. If the determination in S8 is negative, S9 is executed, and if the determination is positive, S10 is executed.

[0040] In S9, which is executed when S4 is negative and when S8 is negative, it is determined whether the differential rotation speed ΔNdf of the differential gear device 26 is increasing. If the determination in S9 is negative, the differential limiting control is continued in S3, but if the determination is positive, the pressing load (engagement pressure) of the differential limiting clutch 46 is reduced in S5, and the differential limiting control is restricted. In S10, which is executed when S8 is positive, it is also determined whether the differential rotation speed ΔNdf of the differential gear device 26 is increasing. If the determination in S10 is negative, the differential limiting control is continued in S3, but if the determination is positive, the pressing load (engagement pressure) of the differential limiting clutch 46 is reduced in S5, and the differential limiting control is restricted.

[0041] According to the electronic control device 60 of this embodiment, in addition to obtaining the same effects as those of the above-mentioned embodiments 1 and 2, depending on whether the differential rotation speed ΔNdf of the differential gear device 26 is tending to increase or not, it is determined whether to continue the differential limiting control or to execute the pressure load reduction control of the differential limiting clutch 46, regardless of other threshold value judgments (taking priority over other threshold value judgments), so that sliding of the differential limiting clutch 46 and failure of the transmitted driving force can be suppressed.

[0042] According to the electronic control device 60 of this embodiment, as shown in the time chart of FIG. 6, even before the establishment of a predetermined condition B for executing the limiting differential control (LSD control) (negation in S8), if it is determined that the differential speed ΔNdf of the differential gear device 26 is increasing (positive in S9), the pressing load reduction control of the differential limiting clutch 46 is executed (S5), so that the unnecessary sliding of the differential limiting clutch 46 is suppressed. In FIG. 6, the solid line indicates the differential speed ΔNdf, the one-dot chain line indicates the pressing load of the differential limiting clutch 46, and the two-dot chain line indicates the temperature Tc of the differential limiting clutch 46. In FIG. 6, after the start of the differential limiting control of the differential gear device 26 (time t0), the brake control by one of the wheel brakes 52, 54 is started (time t1), and the reduction of the pressing load (engagement pressure) of the differential limiting clutch 46 is started (time t2) before the elapsed time determination threshold value te1, so that the unnecessary sliding of the differential limiting clutch 46 is suppressed.

[0043] 7 is a time chart for explaining a conventional control operation. In this case, the elapsed time determination threshold te1 and the point (time t2) when the pressure load (engagement pressure) of the differential limiting clutch 46 starts to be reduced are the same, so the differential limiting clutch 46 continues to slide until the elapsed time te from the start of braking (brake control) of the high rotation (high torque) wheel by one of the wheel brakes 52, 54 reaches the elapsed time determination threshold te1.

[0044] 8, when a decreasing trend in the differential rotation ΔNdf of the braking (brake control) of the wheel on the high rotation (high torque) side by one of the wheel brakes 52, 54 is confirmed (No in S10), the pressing load of the differential limiting clutch 46 is not decreased (continuation of S3) even if the elapsed time te exceeds the elapsed time determination threshold te1. As a result, stable operation of the vehicle 10 is prioritized, and the differential limiting control of the differential limiting clutch 46 is continued.

[0045] 9 is a time chart for explaining a conventional control operation. In this case, when the elapsed time te reaches the elapsed time determination threshold te1, the differential limiting control by the differential limiting clutch 46 ends and the pressure load of the differential limiting clutch 46 is reduced, so that the sliding of the differential limiting clutch 46 is suppressed, while the driving force of the vehicle 10 decreases, and the vehicle 10 may vibrate accordingly.

[0046] Although the embodiment of the present invention has been described in detail above with reference to the drawings, the present invention can be applied to other embodiments.

[0047] For example, in the above-described embodiment, the differential limiting clutch 46 was provided between the differential case 32 and the drive shaft 22 of the differential gear device 26, but it may also be provided between the differential case 32 and the drive shaft 20, between the side gears 38 and 40, etc.

[0048] In addition, in the above-mentioned differential limiting clutch 46, a pressing load is applied to the fixed side friction plates 48 and the rotating side friction plates 50 by an electric actuator, but the pressing load may be applied by a hydraulic actuator.

[0049] Furthermore, the vehicle 10 described above does not necessarily have to be equipped with the transmission 14 .

[0050] It should be noted that the above is merely one embodiment, and the present invention can be embodied in various modified and improved forms based on the knowledge of those skilled in the art. [Explanation of symbols]

[0051] 10: vehicle, 12: prime mover, 14: transmission, 16, 18: drive wheels, 20, 22: drive shaft, 24: propeller shaft, 26: differential gear device, 28: small diameter bevel gear, 30: large diameter bevel gear, 32: differential case, 34: pinion shaft, 36: pinion, 38, 40: side gear, 46: limited slip clutch, 48: fixed side friction plate, 50: rotating side friction plate, 52, 54: wheel brake, 60: electronic control device (control device), 62: limited slip clutch slip determination unit, 64: limited slip clutch control unit, 66: wheel brake control unit, 68, 70: wheel rotation sensor

Claims

1. A vehicle is provided with a differential gear device provided between left and right drive shafts, which distributes drive torque transmitted from a drive source to left and right drive wheels while allowing a rotational difference between them, a differential limiting clutch which limits the differential between the left and right drive wheels, and a wheel brake device which controls the rotational speed of each of the drive wheels. In this vehicle, when the torque capacity of the differential limiting clutch is exceeded and slippage occurs in the differential limiting clutch and a differential rotation occurs between the left and right drive wheels, a control device for a vehicle differential limiting clutch is provided which brakes the drive wheel with a higher rotational speed among the drive wheels using the wheel brake, When the drive wheels are being braked by the wheel brakes, the differential limiting torque of the differential limiting clutch is reduced.

2. A control device for a limited differential clutch for a vehicle.

2. The control device reduces the differential limiting torque of the differential limiting clutch on the condition that a differential rotation equal to or greater than a preset differential rotation determination value occurs during braking of the drive wheels by the wheel brakes, but does not reduce the differential limiting torque of the differential limiting clutch when a differential rotation below the preset differential rotation determination value occurs.

2. The control device for a limited differential clutch for a vehicle according to claim 1.

3. The control device reduces a differential limiting torque of the differential limiting clutch on condition that the temperature of the differential limiting clutch is equal to or higher than a preset clutch temperature determination value while the drive wheels are being braked by the wheel brakes.

2. The control device for a limited differential clutch for a vehicle according to claim 1.

4. The control device reduces a differential limiting torque of the differential limiting clutch on condition that an elapsed time from a start of operation of the wheel brake exceeds a preset elapsed time determination threshold while the drive wheels are being braked by the wheel brake.

2. The control device for a limited differential clutch for a vehicle according to claim 1.

5. The control device, when the differential rotation of the differential gear device tends to increase during braking of the drive wheels by the wheel brakes, preferentially reduces the differential limiting torque of the differential limiting clutch.

2. The control device for a limited differential clutch for a vehicle according to claim 1.

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