JPH062449B2 - Vehicular limited clutch control device - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vehicular differential limiting clutch control device that controls a differential limiting amount of left and right wheels.

(Prior Art) As a conventional limited slip differential clutch control device, for example, a device described in JP-A-59-199331 is known.

In this conventional device, in a vehicle equipped with a differential lock device, a sensor that detects the ground load of each drive wheel and the output signals of the sensor are input and compared, and there is a predetermined difference in the ground load of each drive wheel. In the event of occurrence, the differential lock device is characterized by comprising a control circuit for activating the actuator or activating the alarm device in order to cancel the operating state when the differential locking device is in the operating state.

(Problems to be Solved by the Invention) However, in the above-mentioned conventional limited slip differential clutch control device, unless the ground load of the left and right drive wheels is significantly different, the diff lock state (the left and right wheel direct connection state). Therefore, when turning with the diff locked state, there is a problem that the understeer tendency is exhibited at the corner entry, and the lateral exit changes to the oversteer tendency due to the lateral acceleration, that is, the reverse steer characteristic is exhibited. .
Further, even if the diff lock state is suddenly switched to the diff lock release state during turning, there is a problem that the steer characteristic suddenly changes and the turning stability becomes extremely low.

(Means for Solving Problems) The present invention has been made for the purpose of solving the above-mentioned problems, and in order to achieve this object, the present invention provides the following solving means. did.

The solution means of the present invention will be described with reference to the conceptual diagram of claims shown in FIG. 1. A power split device 1 for distributing and transmitting an engine driving force to left and right drive wheels, a drive input unit 2 and a drive output of the power split device 1. The differential limiting clutch 4 provided between the portion 3 and the clutch limiting force capable of changing the differential limiting force according to the magnitude of the clutch engaging force, and the increase / decrease control of the clutch engaging force are performed based on the input signal from the input means 5. In the vehicle differential limiting clutch control device including the clutch control means 6, the vehicle speed sensor 501 and the steering angle sensor 5 are used as the input means 5.
02, wheel speed sensors 503 and 504 for the left and right drive wheels
And a yawing momentum detecting means 505, and the clutch control means 6 controls the outer speed of the turning wheel so that the actual yawing momentum from the yawing momentum detecting means 505 matches the target yawing momentum obtained from the vehicle speed V and the steering angle θ. When the actual yawing momentum becomes larger than the target yawing momentum in the initial stage of the turning, the clutch engagement force is increased, and the actual yawing momentum during the mid-to-late turning period when the turning outer wheel speed becomes equal to or lower than the turning inner wheel speed. Is a means for controlling the clutch engaging force by decreasing the clutch engaging force as the target yawing momentum increases.

Here, the yawing momentum means the momentum about the vehicle vertical axis which is the yaw axis of the vehicle. (Operation) First, in the initial stage of turning, since the lateral acceleration is small and the inner wheel spin does not occur, the turning outer wheel speed exceeds the turning inner wheel speed depending on the turning radius difference.

Therefore, when the differential limiting force is applied at this time, the inner wheel driving torque is large and the outer wheel driving torque is small, so that a yaw moment in the understeer direction to the outside of the turning radius is generated and the actual yawing momentum is reduced.

On the other hand, the control content is such that the clutch engagement force is increased as the actual yawing momentum becomes larger than the target yawing momentum at the initial stage of turning when the turning outer wheel speed exceeds the turning inner wheel speed.

As a result, control is performed to weaken the clutch engagement force and reduce the differential limiting force with respect to the actual reduction of the yawing momentum, and the yaw moment in the understeer direction is suppressed in the initial stage of turning, and the yaw moment of the vehicle in the initial stage of turning is suppressed. Turnability increases.

Next, from the middle of the turn to the latter half of the turn, the inner wheel spin is generated due to the high lateral acceleration, and the outer wheel speed of the turn becomes equal to or lower than the inner wheel speed of the turn.

Therefore, when the differential limiting force is applied at this time, the outer wheel drive torque is large and the inner wheel drive torque is small, so that a yaw moment in the oversteer direction to the inside of the turning radius is generated and the actual yawing momentum increases.

On the other hand, the control content is such that the clutch engagement force becomes smaller as the actual yawing momentum becomes larger than the target yawing momentum from the middle of turning to the latter half of turning when the turning outer wheel speed becomes equal to or lower than the turning inner wheel speed.

As a result, in response to an increase in the actual yawing momentum, control is performed to weaken the clutch engagement force and reduce the differential limiting force, and the yaw moment in the oversteer direction is suppressed from the mid-turn period to the late-turn period to suppress turning. The vehicle behavior at the limit running is improved, and the turning limit running stability is improved.

(Examples) Examples of the present invention will be described in detail below with reference to the drawings.

First, the configuration will be described.

An automobile to which the vehicle differential limiting clutch control device of the embodiment is applied has an engine 50, a transmission 51, a propeller shaft 52, a differential device (power split device) B, a left rear wheel drive shaft, as shown in FIG. 53, a right rear wheel drive shaft 54, a left rear wheel 55, a right rear wheel 56, a left front wheel 57, and a right front wheel 58, and is a so-called FR vehicle (front engine / rear drive vehicle).

As shown in FIG. 3, the differential device B includes a housing 6
0, drive pinion 61, ring gear 62, differential case 63, pinion mate shaft 64,
A differential pinion 65, side gears 66 and 67, and multi-plate friction clutches (differential limiting clutches) 68 and 69 are provided.

The multi-plate friction clutches 68 and 69 are clutches that can change the differential limiting force to the left and right rear wheels 55 and 56 by engaging the clutch with a control hydraulic pressure Pc from the outside, and rotate to a differential case (drive input unit) 63. A plurality of clutch plates 681 and 691 that are directionally engaged, and a plurality of clutch discs 682 and 692 that are disposed between the clutch plates 681 and 691 and that are rotationally engaged to the side gear (drive output portion) 66, 67 side. , The clutch plate 6
81, 691 and clutch disc 682, 692, a clutch piston 683 that applies a fastening force, and a control oil pressure P.
and a piston chamber 684 to which c is supplied.

The multi-plate friction clutch 69 on the side where the clutch piston 683 is not provided is given a fastening force by the reaction force from the housing 60 and the differential case 63.

Differential limited clutch control device (clutch control means) 70
Is a vehicle speed sensor 7 as an input means, as shown in FIG.
1, a steering angle sensor 72, a yaw rate sensor 73, a left rear wheel wheel speed sensor 74, a right rear wheel wheel speed sensor 75 are provided, a control unit 76 by a vehicle-mounted microcomputer is provided as a control circuit, and an electromagnetic proportional control is provided as a control actuator. A solenoid valve 77 is provided.

The vehicle speed sensor 71 is a sensor that detects the vehicle speed V and outputs a vehicle speed signal (v) corresponding to the vehicle speed V.

The steering angle sensor 72 detects the steering angle θ,
Is a sensor that outputs a steering angle signal (θ) according to the.

The vehicle speed sensor 71 and the steering angle sensor 72 are set to the target yaw rate. And a sensor for obtaining the target yaw angular acceleration ^* .

The calculation formula for these target values is R = KsXL / tan (θ / N) ... = dV / dt ... R; turning radius; vehicle acceleration Ks; gain L; wheel base length N; steering gear ratio, and the turning radius R and the vehicle speed sensor 41 obtained by the formula
By substituting the vehicle speed V by
^* Is obtained, and the turning radius R obtained by the formula and the vehicle acceleration obtained by the formula are given by the formula Be done.

Here, as the vehicle acceleration, a vehicle longitudinal sensor may be added and an acceleration signal from this sensor may be used.

Further, in the embodiment, these target values have a range, The area is set as.

The yaw rate sensor 73 is mounted on the vertical axis of the vehicle. It is a sensor.

This yaw rate sensor 73 is actually a yaw rate sensor. It is obtained by the arithmetic expression of.

The left and right rear wheel speed sensors 74, 75 are provided for the left and right rear wheels 5.
5,56 wheel speed _N L, to detect the _{N R,} wheel speed _N L, N
A sensor that outputs wheel speed signals (nl) and (nr) according to _R is used as a signal for determining which of the wheel speeds N _OUT and N _IN of the inner and outer wheels is higher during turning.

The control unit 76 includes a RAM or ROM that is a storage circuit as an internal circuit, a CPU that is a central processing circuit, and the like, and performs processing based on an input signal and information stored in advance. A control current signal (i) having a current value I is output to the electromagnetic proportional solenoid valve 45.

The control current from the control unit 44 And controlling the hydraulic pressure to 33, a signal for a predetermined control hydraulic pressure Pc, to determine the output current value I, N _OUT> control map when the N _IN M ₂ and _(Figure 4), N _OUT ≦ N _IN The time control map M ₃ (FIG. 5) is preset.

The electromagnetic proportional solenoid valve 77 is used in the oil pump 7.
8 is provided in the middle of the drain oil passage 80 branched from the pump oil pressure passage 79 from 8 to control the drain oil amount to the reserve tank 81 by the balance between the electromagnetic force and the oil pressure, and the magnitude of the current value I. Is a valve for adjusting the control oil pressure Pc according to

Next, the operation will be described.

First, referring to FIG. 7, the left wheel torques T _L1 , T _L2 and T _L2 and T _{L2 in} the case where the engaging force is applied to the multi-plate friction clutches 68, 69 which are the differential limiting clutches to generate the differential limiting forces T _C1 , T _C2. The right wheel torques T _R1 and T _R2 will be described.

When the differential limiting force is not applied, the left and right wheel torques are equally distributed, and when the differential limiting force T _C1 is applied when the right rear wheel 56 is slipping, idling, etc., the torque characteristic T _C1 is changed. The left and right wheel torques are selected to be T _L1 and T _R1 , respectively, and the driving torque T _L1 on the left rear wheel 55 side increases.

The same applies when the differential limiting force T _C2 is applied, and the same action is exhibited when the left rear wheel 55 is slipping or idling.

Next, the yaw moment when a high differential limiting force is applied during turning will be described.

First, in the initial stage of turning and in the case shown in FIG. 8, since the lateral acceleration is small, inner wheel spin does not occur, and N _OUT > N
It becomes the relation of _IN .

Therefore, if differential limiting is performed at this time, the inner-wheel drive torque is large and the outer-wheel drive torque is small. Next, in the middle of the turning period to the latter half of the turning, and in the case shown in FIG. 9, the inner wheel spin is generated by the high lateral acceleration, and N
_OUT ≤ N _IN .

Therefore, if differential limiting is performed at this time, the driving force difference between the inner and outer wheels becomes large, and the outer wheel driving torque becomes large. In this way, by controlling the differential limiting amount in the direction that suppresses the yaw moment in the understeer direction at the beginning of turning, it is possible to improve the turning ability of the vehicle at the beginning of turning, and in the oversteer direction from the middle of turning to the latter half of turning. It has been found that controlling the differential limiting amount in the direction of suppressing the yaw moment of the vehicle can improve the turning stability by improving the vehicle behavior at the limit running during turning acceleration, and thus controlling the differential limiting amount in this way. I am trying to do it.

Next, the flow of control operation in the control unit 76 of the embodiment apparatus will be described with reference to the flow chart shown in FIG.

(A) When N _OUT > N _IN At the initial _stage of turning, and when there is no inner wheel slip and there is a relationship of N _OUT > N _IN , step 200 → step 201 → step 202 → step 203 → step 204 → step 205 Flow, step 200 → step 2
01 → step 206 → step 203 → step 20
The flow is 4 → step 205, and in step 205, which is an output step, the control current signal (i) is output according to the control content searched in the control map M ₂ .

Control in the opposite direction, and in the opposite case, the differential limiting force is weakened. To converge.

(B) When N _OUT ≦ N _IN When the inner wheel slip occurs and the relationship of N _OUT ≦ N _IN is in the middle to the second half of the turning, step 200 →
Step 201 → step 202 → step 203 → step 207 → step 205, or step 200 → step 201 → step 206 → step 2
03 → will flow as step 207 → Step 205, the control current signal (i) is output in accordance with the control content retrieved at step 205 the control map M ₃ is an output step.

The control map M ₃ has the opposite relationship between the pressure increase and the pressure decrease with respect to the control map M ₂ .

(C) When traveling straight ahead When traveling straight ahead, the flow is as follows: step 200 → step 201 → step 208 → step 205. At step 205, which is an output step, a control current signal (i) for obtaining the maximum hydraulic pressure is output.

Incidentally, step 201 is a judgment step for judging whether to turn right, left or straight according to the steering angle θ, steps 202 and 206 are setting steps for setting the wheel speeds N _OUT and N _IN of the inner and outer wheels, and step 203 is This is a step of determining whether N _OUT > N _IN .

As described above, in the vehicle differential limiting clutch control device 70 of the embodiment, the vehicle speed sensor 71, the steering angle sensor 72, the yaw rate sensor 73, the left rear wheel wheel speed sensor 74, and the right rear wheel are used as the input means. A wheel / wheel speed sensor 75 is provided,
The control unit 76 reverses the control contents depending on the size of the turning inner and outer wheels and is obtained from the output signal of the yaw rate sensor 73. Target yaw rate obtained from vehicle speed V and steering angle θ Since the means for controlling the differential limiting force is used, the turning ability of the vehicle is improved in the early stage of turning, and the turning stability is enhanced in the middle to late stages of turning, resulting in sudden changes in spin and steer characteristics during high lateral acceleration turning. It is possible to realize high turning performance.

In addition, the target yawing momentum is defined by the yaw rate and the yaw angular acceleration, and the clutch engagement force control is performed by the proportional + derivative control operation. Therefore, the target steer characteristic is higher due to the higher control responsiveness than the control by only the yaw rate. Obtainable.

Although the embodiment of the present invention has been described in detail above with reference to the drawings, the specific configuration is not limited to this embodiment, and the present invention can be applied even if there is a design change or the like within a range not departing from the gist of the present invention. included.

For example, in the example, yawing momentum However, a combination of these may be used.

Further, in the embodiment, a clutch that differentially operates by hydraulic pressure is shown as the differential limiting clutch, but a clutch that operates by an external force other than hydraulic pressure, such as an electromagnetic clutch, may be used.

(Effect of the Invention) As described above, in the vehicular differential limiting clutch control device of the present invention, the actual yawing momentum from the yawing momentum detecting means is the target yawing momentum obtained from the vehicle speed and the steering angle. In order to correspond to the above, since the clutch engagement force control that reverses the control content depending on the size of the inner and outer wheels during turning is used, the turning ability of the vehicle is improved at the beginning of turning and the stability of turning is improved from the middle of turning to the latter half of turning. Therefore, it is possible to obtain an effect that it is possible to realize high turning performance without sudden changes in spin and steer characteristics during turning with high lateral acceleration.

[Brief description of drawings]

FIG. 1 is a conceptual diagram of claims of a limited slip differential clutch control device for a vehicle according to the present invention, FIG. 2 is a diagram showing a drive system of a rear wheel drive vehicle to which the limited slip differential clutch control device of an embodiment is applied, and FIG. Is a schematic diagram showing a differential device and a differential limiting clutch control device of the embodiment, FIGS. 4 and 5 are control map diagrams stored in advance in a control unit of the embodiment device, and FIG. 6 is the embodiment device. Fig. 7 is a flow chart showing the flow of control operation in the control unit of Fig. 7, Fig. 7 is a diagram showing the torque characteristics of the left and right wheels due to the differential limiting force, and Fig. 8 is a diagram showing the yaw moment when the differential limiting is performed at the initial stage of turning. FIG. 9 is an operation explanatory view showing the generation, and FIG. 9 is an operation explanatory view showing the generation of the yaw moment when the differential limitation is performed from the middle of turning to the latter half of turning. DESCRIPTION OF SYMBOLS 1 ... Power split device 2 ... Drive input part 3 ... Drive output part 4 ... Differential limiting clutch 5 ... Input means 501 ... Vehicle speed sensor 502 ... Steering angle sensor 503 ... Left drive wheel wheel speed sensor 504 ... Right drive wheel wheel speed sensor 505 ... yawing momentum detection means 6 ... clutch control means

Claims (1)

[Claims] Claim: What is claimed is: 1. A power split device for distributing and transmitting an engine drive force to left and right drive wheels, and a power split device provided between a drive input part and a drive output part of the power split device. A differential limiting clutch control device for a vehicle, comprising: a differential limiting clutch capable of changing a limiting force; and a clutch control means for performing an increase / decrease control of a clutch engaging force based on an input signal from an input means, The means includes a vehicle speed sensor, a steering angle sensor, a wheel speed sensor for the left and right driving wheels, and a yawing momentum detecting means, and the clutch control means controls the actual yawing momentum from the yawing momentum detecting means depending on the vehicle speed and the steering angle. In order to match the obtained target yawing momentum, the actual yawing momentum is equal to the target yaw moment at the beginning of turning when the turning outer wheel speed exceeds the turning inner wheel speed. The clutch engagement force is increased as the turning yaw momentum becomes larger, and the clutch engagement force becomes smaller as the actual yawing momentum becomes larger than the target yawing momentum during the middle to late turning periods when the turning outer wheel speed becomes lower than the turning inner wheel speed. As a means for controlling the clutch engaging force, a differential limiting clutch control device for a vehicle.