JP2010281361A - Differential gear with differential limiting mechanism - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent a situation that differential limiting torque generated by a differential limiting mechanism quickly drops and a sense of incongruity is given to a driver at the time of reduction of steering angle in a differential gear with a differential limiting mechanism. <P>SOLUTION: A differential limiting torque control means increases differential limiting torque generated by the differential limiting mechanism of the differential gear in response to increase of difference between actual yaw rate and model yaw rate increasing as steering angle increases. When the steering angle decreases under a condition where differential limiting torque exceeds threshold T1, the differential limiting torque means executes differential limiting torque progressive reduction control reducing differential control torque (output differential limiting torque TOBJA) at reduction rate gentler than that of differential limiting torque (target differential limiting torque TOBJAorg) defined according to the difference. Consequently, deterioration of steering feeling is prevented by avoiding the situation that differential limiting torque quickly reduces and a sense of incongruity is given to the driver at the time of reduction of steering angle. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention provides a differential differential torque control means for increasing a differential limit torque generated by a differential limit mechanism of a differential device according to a deviation between a reference yaw rate and an actual yaw rate that increase with an increase in steering angle. The present invention relates to a differential device with a limiting mechanism.

  A differential device with a differential limiting mechanism in which a differential limiting mechanism that operates with an actuator to limit a differential function is provided in a differential device that distributes driving force to the left and right drive wheels is known, for example, from Patent Document 1 below It is.

JP 2007-56924 A

  By the way, in such a differential device with a differential limiting mechanism, the differential function of the differential device is limited by the differential limiting mechanism to generate a differential limiting torque corresponding to the deviation between the vehicle standard yaw rate and the actual yaw rate. When the control is performed so that the actual yaw rate matches the standard yaw rate, the deviation decreases rapidly when the steering wheel is returned to the neutral position, and the differential limiting torque generated by the differential limiting mechanism decreases rapidly. There is a case. In such a case, the steering reaction force that the driver receives from the steering wheel suddenly changes due to the torque steer phenomenon, which may cause the driver to feel uncomfortable.

  The present invention has been made in view of the above-described circumstances, and in a differential device with a differential limiting mechanism, the differential limiting torque generated by the differential limiting mechanism when the steering angle is reduced sharply reduces the driver's feeling of strangeness. The purpose is to prevent this.

  In order to achieve the above object, according to the first aspect of the present invention, the difference generated by the differential limiting mechanism of the differential device in accordance with the deviation between the standard yaw rate and the actual yaw rate that increases as the steering angle increases. In the differential device with a differential limiting mechanism that includes a differential limiting torque control unit that increases the dynamic limiting torque, the differential limiting torque control unit decreases a steering angle when the differential limiting torque exceeds a threshold value. Differential limiting torque gradual reduction control is performed to reduce the differential limiting torque more slowly than the differential limiting torque reduction rate determined according to the deviation. Is proposed.

  According to the second aspect of the present invention, in addition to the configuration of the first aspect, the differential limiting torque control means is configured to execute the differential limiting torque gradual reduction control so that the differential limiting torque is less than or equal to the threshold value. When this is the case, a differential device with a differential limiting mechanism is proposed in which the differential limiting torque gradual reduction control is stopped.

  According to a third aspect of the present invention, in addition to the configuration of the first or second aspect, the differential limiting torque control means has a predetermined steering angular velocity during execution of the differential limiting torque gradual reduction control. A differential device with a differential limiting mechanism is proposed in which the differential limiting torque gradual reduction control is stopped when the value exceeds the value.

  The actuator A of the embodiment corresponds to the differential limiting mechanism of the present invention, and the LSD control unit 91 of the embodiment corresponds to the differential limiting torque control means of the present invention.

  According to the configuration of the first aspect, the differential limiting torque generated by the differential limiting mechanism of the differential device is generated by the differential limiting torque control means in accordance with the deviation between the standard yaw rate and the actual yaw rate that increase as the steering angle increases. increase. When the steering angle is decreased while the differential limiting torque exceeds the threshold, the differential limiting torque control means decreases the differential limiting torque more slowly than the differential limiting torque reduction rate determined according to the deviation. Since the differential limiting torque gradually decreasing control is performed, the steering feeling can be prevented from deteriorating by preventing the driver from feeling uncomfortable by rapidly decreasing the differential limiting torque when the steering angle is decreased.

  According to the second aspect of the present invention, the driver does not feel uncomfortable in the first place even if the differential limiting torque rapidly decreases after the differential limiting torque becomes equal to or less than the threshold value by executing the differential limiting torque gradual reduction control. Therefore, it is possible to prevent unnecessary control from being performed by stopping the differential limiting torque gradual reduction control.

  According to the third aspect of the present invention, when the driver operates the steering wheel at a steering angular speed greater than or equal to a predetermined value during execution of the differential limiting torque gradual reduction control, the driver even if the differential limiting torque decreases rapidly. Since there is no sense of incongruity in the first place, unnecessary control can be prevented by stopping the differential limiting torque gradual reduction control.

The rear view of the internal combustion engine for motor vehicles. The expanded sectional view of a differential mechanism and an actuator. FIG. 3 is an enlarged view of a part 3 in FIG. 4 is an enlarged view of part 4 of FIG. 2 showing the structure of the actuator. FIG. 5 is an enlarged view of part 5 of FIG. 3 showing the structure of the friction multi-plate clutch. FIG. 6 is a sectional view taken along line 6-6 of FIG. FIG. 7 is a cross-sectional view taken along line 7-7 in FIG. 3. FIG. 8 is a cross-sectional view taken along line 8-8 in FIG. 4. The block diagram of the control system of an electric motor. The time chart which shows an example of the gradual reduction control of a differential limiting torque. The flowchart which shows the effect | action of the gradual reduction control of a differential limiting torque.

  Hereinafter, embodiments of the present invention will be described with reference to FIGS.

  As shown in FIG. 1, an internal combustion engine E mounted horizontally on the front body of a front engine / front drive automobile has a transmission T integrally coupled to a left side surface thereof, and a difference between the rear surface of the transmission T and the rear surface thereof. A moving mechanism D is provided. A half shaft 11 (intermediate shaft) extends rightward from a differential mechanism D arranged to be shifted leftward from the vehicle body center line, and a right axle that drives a right drive wheel (not shown) to the halfshaft 11. 12 is connected, and a left drive wheel (not shown) is driven via a left axle 13 extending in the left direction from the differential mechanism D. The right end of the half shaft 11 is supported by a stay 10 fixed to the engine block 22.

  As is clear from FIG. 2, the housing 14 that houses the differential mechanism D covers the housing body 15 that is formed integrally with the casing of the transmission T and the left end opening of the housing body 15. And a cover plate 17 fixed by a plurality of bolts 16. A plurality of actuators A, which are separately attached to the right side of the differential mechanism D, are an actuator case 18 that fits into the right end opening of the housing body 15 of the differential mechanism D, and a plurality of actuators A so as to cover the right end opening of the actuator case 18 The actuator cover 20 is fixed by a plurality of bolts 19... And is fixed to the engine block 22 by a plurality of bolts 21 penetrating the actuator case 18. The differential mechanism D and the actuator A constitute a differential device.

  The differential mechanism D housed in the housing 14 includes a first case 24 on the right side supported by the roller body 23 on the housing body 15 and a second case 26 on the left side supported by the roller bearing 25 on the cover plate 17. Are connected by a plurality of bolts 27, and an axle drive gear 29 driven by the transmission T is fixed to the outer periphery of the first case 24 by a plurality of bolts 30.

  Next, the structure of the differential mechanism D will be described with reference to FIGS. 3 and 5 to 7.

  The differential mechanism D housed in the housing 14 includes four pinion shafts 31 integrated so as to intersect in a cross shape. The pinion shafts 31 having a circular cross section are formed with chamfers 31a at their ends, and the chamfers 31a are fitted into four support grooves 24a formed on the inner peripheral surface of the first case 24. To do. Four pinions 32 are rotatably supported on the four pinion shafts 31. Spacers 33 are arranged between the pinions 32 and the inner peripheral surface of the first case 24, and the radial positions of the pinions 32 are regulated by these spacers 33.

  The outer periphery of the half shaft 11 inserted into the first case 24 is splined to the right side gear 34 </ b> R and is prevented from coming off by a snap ring 35. Further, the right end of the left axle 13 inserted through the second case 26 and inserted into the first case 24 is splined to the clutch inner 37 and is prevented from coming off by a snap ring 38. A left side gear 34 </ b> L is integrally formed on the right side surface of the clutch inner 37. The left and right side gears 34L and 34R mesh with the four pinions 32.

  A clutch outer 40 is integrally formed on the inner periphery of the first case 24 so as to face the outer periphery of the clutch inner 37, and a plurality of clutch plates (five in the embodiment) are provided on the inner peripheral surface of the clutch outer 40. 41 ... are spline-fitted to the outer peripheral portion of the clutch inner 37, and the inner peripheral portions of a plurality of (6 in the embodiment) clutch discs 42 are spline-fitted to the outer peripheral surface of the clutch inner 37. The clutch plates 41 and the clutch disks 42 are alternately arranged so that the friction materials 43 attached to both surfaces of the clutch disks 42 contact the clutch plates 41.

  The outer peripheral portion of the pressure plate 44 is spline-fitted to the inner peripheral surface of the clutch outer 40, and the left side surface of the pressure plate 44 is opposed to the right side surface of the clutch disk 42 located at the rightmost end. A plurality (four in the embodiment) of lever lever storage recesses 24b extending in the radial direction are formed on the inner surface of the first case 24 facing the right side surface of the pressure plate 44, and each lever lever storage recess 24b is formed. A fulcrum 45a at the radially outer end of the lever lever 45 is slidably engaged with the radially outer end.

  Inside the actuator case 18, the first hollow shaft 47 is fitted to the outer periphery of the half shaft 11 via a needle bearing 46 (see FIG. 1) so as to be relatively rotatable and axially movable. Inside the first case 24, the right end of the second hollow shaft 48 is engaged with the left end of the first hollow shaft 47 so that the right end of the second hollow shaft 48 is not rotatable relative to the left end, and the right end of the third hollow shaft 49 is connected to the left end of the second hollow shaft 48. Engages with concaves and convexes so that relative rotation is impossible. A diameter-expanded portion 48a having a diameter increased along the inner peripheral surface of the first case 24 is formed on the left end side of the second hollow shaft 48, and the diameter of the third hollow shaft 49 is set to the maximum diameter of the diameter-expanded portion 48a. Match.

  A plurality (six in the embodiment) of through holes 48b are formed in the enlarged diameter portion 48a of the second hollow shaft 48, and the four extended portions 24c projecting from the inner surface of the first case 24 are penetrated. It penetrates the hole 48b loosely and protrudes to the inside of the enlarged diameter portion 48a. The tip of each extending portion 24c comes into contact with the back surface of the right side gear 34R via the friction washer 50. The back surface of the left side gear 34 </ b> L, that is, the left side surface of the clutch inner 37 abuts against the inner surface of the second case 26 via the friction washer 51.

  The third hollow shaft 49 is formed with four U-shaped notches 49a that open to the left end side at 90 ° intervals. The third hollow shaft 49 can move in the axial direction while avoiding interference between the four pinion shafts 31 and the spacers 33 fitted to the outer periphery thereof by the notches 49a. And the press part 49b which presses the power point 45b provided in the radial direction inner end of the lever lever 45 is formed in the left end of the 3rd hollow shaft 49. As shown in FIG. An action point 45 c that abuts against the right side surface of the pressure plate 44 is provided at an intermediate portion of the lever lever 45.

  In this way, the friction multi-plate clutch 52 for fastening the left axle 13 to the differential case 28 by the clutch inner 37, the clutch outer 40, the clutch plate 41, the clutch disk 42, the pressure plate 44, and the lever lever 45. Is configured.

  Next, the structure of the actuator A that engages the friction multi-plate clutch 52 through the first to third hollow shafts 47, 48, and 49 will be described with reference to FIGS.

  A flange member 61 is slidably fitted to the right end of the first hollow shaft 47 extending inside the actuator case 18 and the actuator cover 20, and a spring seat 63 and a flange locked to the first hollow shaft 47 by a clip 62. A coil spring 64 is disposed in a compressed state between the back surface of the member 61.

  On the half shaft 11 between the flange member 61 and the inner wall surface 20a of the actuator cover 20, a first cam plate 67 and a second cam plate 68 are supported via needle bearings 69 and 70 so as to be rotatable and axially movable. Is done. The first cam plate 67 contacts the flange member 61 via the thrust bearing 85, and the second cam plate 68 contacts the inner wall surface 20 a of the actuator cover 20 via the thrust bearing 86. Inclined cam grooves 67a..., 68a... Are formed on the opposing surfaces of the first and second cam plates 67 and 68, and the balls 71 are accommodated in the cam grooves 67a. The first and second cam plates 67 and 68 and the balls 71 constitute a ball cam mechanism 72.

  A first shaft 73 is supported on the actuator case 18 via a ball bearing 74 and a needle bearing 75, and a second shaft 76 is supported via ball bearings 77 and 78. The first gear 80 provided on the first shaft 73 connected in series to the output shaft 79 a of the electric motor 79 supported on the actuator case 18 is the second and third gears 81 and 82 provided on the second shaft 76. Mesh with the second gear 81. In addition, fourth and fifth gears 83 and 84 are formed on the outer circumferences of the first and second cam plates 67 and 68, respectively. The fourth gear 83 meshes with the second gear 81 of the second shaft 76, and The fifth gear 84 meshes with the third gear 82 of the second shaft 76. The gear ratio between the second gear 81 and the fourth gear 83 and the gear ratio between the third gear 82 and the fifth gear 84 are slightly different.

  As shown in FIG. 9, the electronic control unit U that controls the operation of the electric motor 79 of the actuator A includes an LSD (differential limit) control unit 91 and a motor control unit 92. The LSD control unit 91 to which the vehicle speed detected by the vehicle speed sensor, the steering angle detected by the steering angle sensor, and the yaw rate (actual yaw rate) detected by the yaw rate sensor are input calculates the reference yaw rate from the vehicle speed and the steering angle, The yaw rate deviation is calculated from the reference yaw rate and the actual yaw rate, the target differential limit torque to be generated in the differential device is calculated from the yaw rate deviation, and the output differential limit torque is calculated by correcting the target differential limit torque from the steering angle. Then, the output differential limiting torque is converted into the target motor rotation angle of the electric motor 79. A motor to which a deviation between the target motor rotation angle of the electric motor 79 output by the LSD control unit 91 and the actual motor rotation angle of the electric motor 79 detected by the rotation angle sensor 65 (see FIG. 4) composed of an incremental encoder is input. The control unit 92 feedback-controls the actual motor rotation angle of the electric motor 79 via the motor driver 93 so that the deviation converges to zero.

  Next, the operation of the embodiment of the present invention having the above configuration will be described.

  The differential mechanism D exhibits a differential limiting function in addition to a normal differential function, and the differential limiting torque generated by the differential limiting function is controlled by the actuator A.

  First, the normal differential function of the differential mechanism D will be described.

  When the driving force of the internal combustion engine E is input to the axle drive gear 29 of the differential mechanism D via the transmission T, the differential case 28 coupled to the axle drive gear 29 with bolts 30. When the vehicle is in a straight traveling state, the four pinions 32 are not rotated with respect to the pinion shafts 31 and are not rotated with respect to the pinions 32, but the left side gear 34L meshed with the pinions 32 and the right axle meshed with the left axle 13 and the pinions 32. The side gear 34R and the integral half shaft 11 rotate at the same speed, and the driving force is evenly distributed to the left and right driving wheels.

  For example, when the vehicle is in a left turn state, the left axle 13 connected to the left drive wheel is decelerated and the half shaft 11 connected to the right drive wheel is accelerated, so that a differential rotation occurs between the left and right side gears 34L and 34R. Although generated, the differential rotation is absorbed by the rotation of the pinions 32 meshed with the left and right side gears 34L, 34R. Similarly, when the vehicle is in a right turn state, the left axle 13 connected to the left drive wheel is accelerated and the half shaft 11 connected to the right drive wheel is decelerated, so that the difference between the left and right side gears 34L and 34R. Although rotation occurs, the differential rotation is absorbed by the rotation of the pinions 32 meshed with the left and right side gears 34L, 34R.

  Next, the differential limiting function generated by the operation of the actuator A will be described.

  When the electric motor 79 of the actuator A is driven, the rotation of the first gear 80 of the first shaft 73 coupled to the output shaft 79a is transmitted to the second gear 81 and the second shaft 76 rotates. When the second shaft 76 rotates, the first cam plate 67 rotates through the second gear 81 and the fourth gear 83, and the second cam plate 68 rotates through the third gear 82 and the fifth gear 84. However, since the gear ratio between the second gear 81 and the fourth gear 83 and the gear ratio between the third gear 82 and the fifth gear 84 are slightly different, the first and second cam plates of the ball cam mechanism 72 are different. 67 and 68 rotate relative to each other. As a result, the relative positions of the cam grooves 67a of the first and second cam plates 67, 68 change from the state shown in FIG. 8A to the state shown in FIG. 1. The second cam plates 67 and 68 are driven in directions away from each other.

  The second cam plate 68 that has received a rightward load generated by the ball cam mechanism 72 is prevented from moving rightward by the actuator cover 20. Accordingly, the first cam plate 67 that has received the leftward load generated by the ball cam mechanism 72, that is, the pressing force for engaging the friction multi-plate clutch 52, moves to the left, and the first cam plate 67 passes through the thrust bearing 85 and the flange member 61. 1 Press the hollow shaft 47 in the left direction.

  When a leftward pressing force is applied to the first hollow shaft 47 by the actuator A, the second hollow shaft 48 and the third hollow shaft 49 coupled to the first hollow shaft 47 move to the left, and the third hollow shaft 49 The pressing portions 49b provided at the left end press the force points 45b of the four lever levers 45. As a result, the lever levers 45 swing around the fulcrum 45a, and the action point 45c presses the pressure plate 44 to the left, so that the clutch plates 41 and the clutch disks 42 are in close contact with each other, and the clutch The inner 37 and the clutch outer 40 are coupled together.

  Since the distance L1 between the fulcrum 45a and the force point 45b of the lever lever 45 is set larger than the distance L2 between the fulcrum 45a and the action point 45c, the pressing force F1 input to the lever lever 45 is increased by L1 / L2. The pressure plate 44 can be pressed with the boosted pressing force F2, so that a sufficient pressing force can be applied to the friction multi-plate clutch 52 even if the electric motor 79 of the actuator A is downsized.

  When the friction multi-plate clutch 52 is engaged in this way, the left axle 13 integrated with the clutch inner 37 is integrated with the differential case 28, whereby the left axle 13 and the half shaft 11, that is, the left axle 13. The right axle 12 is integrated so as not to rotate relative to each other, and the differential function of the differential mechanism D is limited so that it can be escaped from soft ground such as muddy, or the stability during high-speed straight running is increased. Can do. At this time, by controlling the current driving the electric motor 79 to change the pressing force generated by the actuator A and causing the friction multi-plate clutch 52 to generate a predetermined slip, the differential mechanism D has an arbitrary magnitude. Differential limiting torque can be exhibited.

  By the way, the LSD control unit 91 calculates a target differential limit torque to be generated in the differential device so that the actual yaw rate matches the standard yaw rate, and outputs the output differential limit torque obtained by correcting the target differential limit torque to the differential device. The differential limiting function is controlled so as to occur. The reason is as follows. That is, when the differential limiting function of the differential device is controlled to match the actual yaw rate with the reference yaw rate, if the steering wheel is returned to the neutral position, the deviation between the reference yaw rate and the actual yaw rate decreases rapidly. Therefore, the target differential limit torque rapidly decreases, and the steering reaction force that the driver receives from the steering wheel due to the torque steer phenomenon may suddenly change and give a sense of incongruity. In order to prevent this, the differential limiting function of the differential device is controlled using the output differential limiting torque obtained by correcting the target differential limiting torque.

  This will be specifically described based on the time chart of FIG.

  Until the time t1, the steering wheel is steered to a predetermined steering angle, and the target differential limit torque TOBJAorg is calculated according to the yaw rate deviation (reference yaw rate−actual yaw rate) generated thereby. When the steering angle starts to decrease toward the neutral position at time t1, the yaw rate deviation rapidly decreases accordingly, and the target according to the rapid decrease of the yaw rate deviation from time t2 when a predetermined time for saturating the change due to the yaw rate has elapsed. The differential limiting torque TOBJAorg suddenly decreases. Since the reduction rate of the target differential limit torque TOBJAorg is remarkable, when the differential limit control is executed based on the target differential limit torque TOBJAorg, the steering reaction force suddenly changes and gives the driver a sense of incongruity. The differential limiting control is executed based on the output differential limiting torque TOBJA in which the reduction rate of the limiting torque TOBJAorg is moderated. By executing the differential limiting control based on the gradually decreasing output differential limiting torque TOBJA, it is possible to prevent the driver from feeling uncomfortable by preventing a sudden change in the steering reaction force due to the torque steer phenomenon.

  The output differential limit torque TOBJA continues to decrease gradually after the target differential limit torque TOBJAorg reaches zero at time t3, and rapidly decreases to zero when the threshold T1 (for example, 500 Nm) is reached at time t4. To do. The reason is that if the output differential limiting torque TOBJA is less than or equal to the threshold value T1, the steering reaction force does not change greatly even if the value is rapidly reduced to zero, and there is no possibility of giving the driver a sense of incongruity.

  The above operation will be described in more detail based on the flowchart of FIG.

  First, at step S1, the target differential limit torque TOBJAorg is acquired, and when the difference obtained by subtracting the target differential limit torque previous value TOBJAorgold from the target differential limit torque TOBJAorg is negative in step S2, that is, the target differential limit torque previous value. If the current target differential torque limit TOBJAorg has decreased with respect to TOBJAorgold, the process proceeds to step S3. In step S3, the output differential limit torque TOBJA is compared with the differential limit torque threshold T1, and if the output differential limit torque TOBJA exceeds the differential limit torque threshold T1, the process proceeds to step S4. If the steering angle SWA is not 0 in step S4 and steering is in progress, and if the steering angle SWA> 0 in step S5 and right steering is being performed, the steering wheel steering is performed when the steering angular velocity threshold is set to ω in step S6. The steering angle SWA−the previous steering angle value SWAold corresponding to the angular velocity is calculated, and if the steering angle SWA−the previous steering angle value SWAold <−the steering angular velocity threshold value ω is established, it is determined that the steering wheel is being returned, The process proceeds to S8. Further, if the steering angle SWA ≦ 0 in the step S5 and the left steering is being performed, if the steering angle SWA−the previous steering angle SWAold> the steering angular velocity threshold value ω is established in the step S7, it is determined that the steering wheel is being returned. Then, the process proceeds to step S8.

As described above, when the target differential limit torque TOBJAorg is decreasing, the output differential limit torque TOBJA exceeds the differential limit torque threshold T1, and the steering wheel is in the returning operation, the step is performed. In S8, the absolute value of the difference obtained by subtracting the previous steering angle value SWAold from the steering angle SWA is calculated as the steering angular velocity ΔSWA of the steering wheel, and in the subsequent step S9, the differential limiting torque gradual decrease coefficient α * is calculated from the output differential limiting torque previous value TOBJAold. The difference obtained by subtracting the steering angular velocity ΔSWA is used as the current value of the output differential limiting torque TOBJA, and the differential limiting torque gradually decreasing flag F SWARTN is set to "1" (during execution of differential limiting torque gradual reduction control)

When the answer to step S2 is NO and the target differential limit torque TOBJAorg is not decreasing, that is, when the target differential limit torque TOBJAorg becomes zero in the region from time t3 to time t4 in FIG. The differential limiting torque gradually decreasing flag F already in S10 If SWARTN is “1” and the differential limiting torque gradual reduction control is being executed, the process proceeds to step S3. This is to prevent the differential limiting torque gradual reduction control from being interrupted in the region from the time t3 to the time t4, and the output differential limiting torque TOBJA is prevented from rapidly decreasing from a state exceeding the differential limiting torque threshold T1. .

When the differential limiting torque gradual reduction control is not being executed at step S10, when the output differential limiting torque TOBJA becomes equal to or less than the differential limiting torque threshold T1 at step S3, or at step S4, the steering angle SWA. When = 0 (during steering), the differential limiting torque gradual reduction control is stopped in step S11, the target differential limiting torque TOBJAorg is used as it is as the output differential limiting torque TOBJA, and the differential limiting torque gradual decreasing flag F SWARTN is reset to "0" (Differential limiting torque gradual reduction control is not being executed).

If the steering wheel is not being returned in step S6 or S7, that is, if the steering wheel is being held or increased, if differential limiting torque gradual reduction control is being executed in step S12, steering is performed in step S13. The absolute value of the difference (steering angular velocity) obtained by subtracting the previous steering angle value SWAold from the angle SWA is compared with the steering angular velocity threshold value ω, and the absolute value of the steering angular velocity is less than the steering angular velocity threshold value ω and the steering wheel is held. For example, the process proceeds to step S8 and step S9, and the differential limiting torque gradual reduction control is continued. On the other hand, when the differential limiting torque gradual reduction control is not being executed at step S12 and when the steering wheel is increased at step S13, the differential limiting torque gradual reduction control is stopped at step S14. The target differential limit torque TOBJAorg is directly used as the output differential limit torque TOBJA, and the differential limit torque gradually decreasing flag F SWARTN is reset to "0" (Differential limiting torque gradual reduction control is not being executed).

  The reason why the differential limiting torque gradual reduction control is stopped when the steering wheel is increased is that the driver cannot recognize even if the steering reaction force changes due to the torque steering phenomenon in such a case. It is possible to prevent the differential limiting torque gradual reduction control that is not required from being performed. In addition, when the steering wheel is temporarily held, the differential limiting torque gradual reduction control is continued without being canceled. Therefore, the differential limiting torque gradual reduction control is canceled due to slight fluctuation during the steering wheel return operation. Can be prevented.

  In step S15, in preparation for the next loop, the target differential limit torque TOBJAorg is updated to the target differential limit torque previous value TOBJAorgold, and the output differential limit torque TOBJA is updated to the output differential limit torque previous value TOBJAold. This routine is terminated.

  The embodiments of the present invention have been described above, but various design changes can be made without departing from the scope of the present invention.

  For example, the structure of the differential limiting mechanism is not limited to the embodiment, and the present invention can be applied to differential limiting mechanisms having various structures.

91 LSD control part (differential limit torque control means)
A Actuator (Differential limiting mechanism)
T1 threshold

Claims (3)

Differential limiting torque control means (91) for increasing the differential limiting torque generated by the differential limiting mechanism (A) of the differential device according to the deviation between the standard yaw rate and the actual yaw rate that increase as the steering angle increases is provided. In a differential device with a differential limiting mechanism,
The differential limiting torque control means (91)
When the steering angle decreases while the differential limiting torque exceeds the threshold value (T1), the difference that decreases the differential limiting torque more slowly than the differential limiting torque reduction rate determined according to the deviation. A differential device with a differential limiting mechanism, characterized by performing dynamic limiting torque gradual reduction control. The differential limiting torque control means (91)
The differential limiting torque gradual reduction control is stopped when the differential limiting torque becomes equal to or less than the threshold (T1) due to the execution of the differential limiting torque gradual reduction control. Differential device with differential limiting mechanism. The differential limiting torque control means (91)
3. The difference according to claim 1, wherein the differential limiting torque gradual reduction control is stopped when a steering angular velocity becomes a predetermined value or more during execution of the differential limiting torque gradual reduction control. Differential device with a movement limiting mechanism.

Images