JPH0624254A - Integrated control device for traction and differential limit torque - Google Patents

Abstract

PURPOSE:To attain compatibility of preventing a steering characteristic from its rapid change in a normal turning region and ensuring stability and acceleratability in a turn limit region, in an integrated control device for traction and differential limit torque applied to a vehicle of mounting both a traction control system and a differential limit torque control system. CONSTITUTION:A differential limit torque control command setting means (d) for setting a differential limit torque control command in the point of time judging traction control action started is provided, and an integrated control means (e) for performing differential limit torque control with the set differential limit torque control command serving as the fixed value in lieu of normal differential limit torque control during the traction control action is provided.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a traction and differential limiting torque integrated control apparatus applied to a vehicle equipped with both a traction control system and a differential limiting torque control system.

[0002]

2. Description of the Related Art Conventionally, for example, Japanese Patent Application Laid-Open No. 4-6635 discloses a comprehensive control device for controlling traction and differential limiting torque.
The device described in Japanese Patent Publication No. 9-279427 (Japanese Patent Application No. 2-179427) is known.

In the above-mentioned conventional source, a technique for reducing the control amount in the understeer direction during operation of the traction reduction control for suppressing the acceleration slip to suppress an excessive understeer tendency accompanying the combined use of the traction control and the differential limiting torque control. It is shown.

[0004]

However, in the above-mentioned conventional integrated control device, the differential limiting torque control side is controlled so that the steer characteristic is oversteered during the operation of the traction reduction control. Therefore, although it is an effective means in the normal turning region due to the steady turning or the acceleration turning which does not reach the turning limit, it has the problems listed below in the turning limit region.

(1) During the operation of the traction reduction control in the turning limit region where idling of the inner wheel does not occur, control is performed to weaken the differential limiting torque so as to reduce the drive torque transmission to the inner turning wheel. In addition, the turning inner wheel slip increases, the vehicle stability is impaired, and the reduction control amount by the traction control increases as the turning inner wheel slip increases, resulting in poor acceleration of the vehicle.

(2) During the operation of the traction reduction control in the turning limit region where idling of the inner wheel occurs, the differential limiting torque is strengthened so as to increase the driving torque transmission to the grounding outer wheel. Therefore, in the case of a rear-wheel drive vehicle, in particular, the transmission drive torque to the turning outer wheel becomes high, so that the turning outer wheel slip is increased and the vehicle stability is deteriorated.

The present invention has been made in view of the above-mentioned problems, and is a combination of traction and differential limiting torque applied to a vehicle equipped with both a traction control system and a differential limiting torque control system. It is an object of the control device to prevent the steer characteristic from suddenly changing in the normal turning region and to ensure stability and acceleration in the turning limit region.

[0008]

In order to solve the above-mentioned problems, in the integrated traction and differential limiting torque control apparatus of the present invention, during traction control operation, instead of normal differential limiting torque control, traction control operation is performed. An integrated control means for performing the differential limiting torque control with the fixed value of the differential limiting torque control command at the time when the start is determined is provided.

That is, as shown in the claim correspondence diagram of FIG. 1, the traction control means a for controlling the traction to be reduced when an acceleration slip occurs and the left and right drive wheels based on predetermined input information such as an accelerator opening degree, a vehicle speed and a lateral acceleration. The differential limiting torque control means b for controlling the differential limiting torque, the traction control operating determination means c for determining whether the traction reduction control for suppressing the acceleration slip is operating, and the traction control operating determination means c. The differential limiting torque control command setting means d for setting the differential limiting torque control command output by the differential limiting torque control means b at the time when the start of the traction control operation is determined, and a predetermined limit during the traction control operation. Instead of the normal differential limiting torque control according to the input information, the set differential limiting torque control command is set to a fixed value. And a general control means e which is performing differential limiting torque control.

[0010]

When the acceleration slip occurs during turning or the like, the control operation determining means c determines whether the traction reduction control for suppressing the acceleration slip is operating, and the differential limiting torque control command setting means d. At this time, the differential limiting torque control command output from the differential limiting torque control means b is set at the time point when the traction control operating determination means c determines that the traction control operation is started.

During the operation of the traction control, the total control means e replaces the normal differential limiting torque control according to the predetermined input information with the set differential limiting torque control command as a fixed value. Control is performed.

Therefore, during the operation of the traction control in the normal turning region, the differential limiting torque control is performed while keeping the fixed value at the start of the control, so that the differential limiting torque before and after the traction control is started. It is possible to prevent a sudden change in the vehicle yaw moment (steer characteristic) due to a change in the driving torque to the inner and outer wheels of the turning due to a change in the torque and a control interference caused by the simultaneous control of the traction control and the differential limiting torque.

Further, even during the operation of the traction control in the turning limit region, the differential limiting torque control is performed while keeping the fixed value at the start of the control, so that the differential with respect to the occurrence of the acceleration slip of the drive wheels is generated. Limiting torque control interference is prevented, and vehicle stability and acceleration are ensured. That is, the vehicle acceleration is prevented from being deteriorated due to the decrease in vehicle stability due to the increase in the turning inner wheel slip and the increase in the traction reduction control amount, such as the case where the differential limiting torque is weakened when the inner wheel idling does not occur. Also, unlike the case where the differential limiting torque is intensified when the inner wheel slips, the transmission driving torque to the turning outer wheel is increased, the turning outer wheel slip is increased, and the vehicle stability is prevented from being impaired.

[0014]

Embodiments of the present invention will be described below with reference to the drawings.

The configuration will be described.

FIG. 2 is an overall view of a system to which an integrated traction and differential limiting torque control apparatus according to an embodiment of the present invention is applied.

The rear-wheel drive vehicle to which the embodiment apparatus is applied is an engine 1, a transmission 2, a propeller shaft 3, a differential 4, drive shafts 5, 6 ,.
The rear wheels 7 and 8 and the front wheels 9 and 10 are provided.

The traction control system corresponding to the traction control means is a system for controlling the engine output by the motor throttle opening so that the rear wheel slip ratio falls within the optimum allowable range when an acceleration slip occurs, and the intake passage 11 of the engine 1 is controlled. A mechanical throttle valve 13 that operates in conjunction with the accelerator pedal 12 and a motor throttle valve 15 that is opened and closed by a throttle motor 14.
And are arranged in series, and TC is connected to this throttle motor 14.
The motor throttle opening is controlled by drive control by the command current mi from the S motor drive circuit 16.

The differential limiting torque control system corresponding to the differential limiting torque control means varies the differential limiting torques of the left and right rear wheels 7 and 8 by controlling the engaging force with respect to the differential limiting clutch 17 built in the differential 4. A control oil passage 20 is connected to a clutch oil chamber of the differential limiting clutch 17 from an external hydraulic pressure source 18 via a hydraulic pressure control valve 19, and a CSD solenoid drive circuit 21 is connected to the hydraulic pressure control valve 19. The clutch hydraulic pressure serving as the clutch engaging force is controlled by the drive control by the command current si from the.

The TCS motor drive circuit 16 and CSD
The control command to the solenoid drive circuit 21 is output from an integrated control unit 22 that performs both throttle control and differential limiting torque control. The integrated control unit 22 includes a right front wheel speed sensor 23 and a right front wheel speed. VFR and left front wheel speed VFL from left front wheel speed sensor 24
, The right rear wheel speed VRR from the right rear wheel speed sensor 25, the left rear wheel speed VRL from the left rear wheel speed sensor 26, and the lateral acceleration sensor 2
The lateral acceleration YG from 7, the accelerator opening A from the accelerator opening sensor 28, the longitudinal acceleration XG from the longitudinal acceleration sensor 29, etc. are input as sensor information.

The operation will be described.

(A) Comprehensive Control Operation of Traction and Differential Limiting Torque FIG. 3 is a flow chart showing a flow of comprehensive control operation of traction and differential limiting torque performed by the differential limiting torque control section of the general control unit 22. Then, each step will be described below.

In step 50, it is judged from the traction control command information based on the traction control command information whether or not the traction control is in operation (corresponding to a traction control in-operation judging means).

In step 51, the flag FTCS indicating whether the traction control is in operation is set to FTCS = 0 indicating that the traction control is not in operation.

In step 52, the normal differential limiting torque control for controlling the differential limiting torque of the left and right rear wheels 7 and 8 is executed based on predetermined input information such as the accelerator opening A, the vehicle speed VFF and the lateral acceleration YG. .

In step 53, the flag FTCS indicating whether the traction control is in operation is set to FTCS = 1 indicating that the traction control is in operation.

In step 54, the control cycle is FTCS.
It is determined whether or not it is the first cycle since = 1.

In step 55, the differential limiting torque command TD output at the side of the differential limiting torque control system at that time is set as the traction control operating torque command TTCS (step 54 and this step 55).
Corresponds to the differential limiting torque control command setting means).

In step 56, the command current si for obtaining the torque command TTCS during traction control operation set in step 55 is set to a fixed value, and the control command based on this command current si is sent from the CSD solenoid drive circuit 21 to the hydraulic control valve 19. It is output (corresponding to the total control means).

(B) When the traction control is not in operation When the traction control is not in operation, such as during turning or straight traveling when the occurrence of acceleration slip of the drive wheels is small, the process proceeds from step 50 to step 51 to step 52 in FIG. Flow, accelerator opening A, vehicle speed VFF, lateral acceleration YG
The normal differential limiting torque control for controlling the differential limiting torque of the left and right rear wheels 7 and 8 is performed by predetermined input information such as.

Accordingly, this is similar to the case where the differential limiting torque control system is mounted alone. For example, at the time of steady turning, prevention of initial understeer of turning and improvement of stability of large radius turning are achieved, and acceleration turning is performed. At times, both turning acceleration and accelerator control are achieved, and
On low μ roads and split μ roads, both start / acceleration and stability are achieved, and by controlling the differential limiting torque of the left and right rear wheels 7 and 8, improvement in turning performance and straight running performance is achieved. .

(C) At the time of traction control operation When the operation of traction control is started at the time of turning or straight running when the occurrence of acceleration slip of the drive wheels is large, the first control cycle is step 50 in FIG. The flow proceeds from step 53 → step 54 → step 55 → step 56. At step 55, the differential limiting torque command TD output at the side of the differential limiting torque control system at that time is the torque command during traction control operation. TTC
S is set as S, and in step 56, a control command based on the command current si that outputs the traction control operating torque command TTCS set in step 55 is output. From the second control cycle, the flow proceeds from step 50 to step 53 to step 54 to step 56 in FIG. 3, and the traction control operating torque command T
A control command with a fixed value of the command current si for obtaining TCS is output.

Therefore, during the traction control operation in the normal turning region due to the low-to-middle lateral acceleration, the differential limiting torque control is performed while the traction control operation torque command TTCS at the start of the traction control is kept as a fixed value. Therefore, the vehicle yaw moment (steer characteristic) due to the fluctuation of the differential limiting torque before and after the start of traction control and the control torque due to the simultaneous control of the traction control and the differential limiting torque causes the driving torque to the turning inner and outer wheels to vary Sudden change is prevented.

That is, when the differential limiting torque is strengthened or weakened during the transmission drive torque reduction control to the left and right rear wheels 7 and 8 by the traction control, the turning inner and outer wheel drive torque difference may increase or decrease rapidly. In such cases,
When the yaw moment around the center of gravity of the vehicle suddenly changes and the yaw moment increases in the turning direction or decreases in the reverse direction, the steer characteristic suddenly changes to the over side, and when the yaw moment increases in the reverse direction or decreases in the turning direction. The steer characteristic suddenly changes to the under side.

Further, even during the traction control operation in the turning limit region due to the high lateral acceleration, the differential limiting torque control is performed while keeping the torque command TTCS during the traction control operation at the start of the traction control as a fixed value. Thus, the differential limiting torque control interference with the occurrence of the acceleration slip of the left and right rear wheels 7 and 8 is prevented, and the stability and acceleration of the vehicle are secured.

That is, the vehicle stability is deteriorated due to the increase of the turning inner wheel slip such as when the differential limiting torque is weakened when the inner wheel idling is not generated, and the traction reduction control amount is increased due to the increase of the turning inner wheel slip. Acceleration failure of the vehicle is prevented. Further, unlike the case where the differential limiting torque is intensified when the inner wheel slips, the transmission driving torque to the turning outer wheel is increased, the turning outer wheel slip is increased, and the vehicle stability is prevented from being impaired.

It should be noted that it is conceivable to set the differential limiting torque to a predetermined fixed value during the operation of the traction control or to make it a variable value according to the road surface friction coefficient, but in either case, when the operation of the traction control is started. Differential limiting torque The differential limiting torque given by the control system and the differential limiting torque that is about to be given during the operation of traction control do not always match. The differential limiting torque fluctuates, which is not preferable in terms of vehicle stability.

Further, in the case of performing the differential limiting torque control with the fixed value of the differential limiting torque control command at the time when the start of the traction control operation is determined instead of the normal differential limiting torque control during the traction control operation. Although there is a concern that vehicle stability will decrease due to the fact that differential limiting torque control is not performed, acceleration slip, which is indirect information on the road surface friction coefficient, is used in traction control in which normal control is given priority. Since the convergence control of the acceleration slip is performed based on the information, the stability can be sufficiently ensured.

The effect will be described.

In a comprehensive control device for traction and differential limiting torque applied to a vehicle equipped with both a traction control system and a differential limiting torque control system,
Instead of the normal differential limiting torque control during traction control operation, the differential limiting torque command TD output from the differential limiting torque control system side when the start of the traction control operation is determined is the traction control operating torque. The command current si for obtaining the torque command TTCS during the traction control operation is set as a fixed value to perform the differential limiting torque control, so that the steer characteristic sudden change in the normal turning region is prevented and the turning limit region is limited. It is possible to achieve both the stability and the ensuring of acceleration.

Although the embodiment has been described above with reference to the drawings, the specific structure is not limited to this embodiment.

For example, in the embodiment, an example of the traction control by the throttle control is shown, but in addition to the throttle control, one or a combination of brake control, ignition cut, cylinder cut, ignition timing retard, etc. is used. Is also good.

[0043]

As described above, according to the present invention, a comprehensive traction and differential limiting torque control device applied to a vehicle equipped with both a traction control system and a differential limiting torque control system. In the operation of the traction control, instead of the normal differential limiting torque control,
Since the integrated control means for performing the differential limiting torque control with the fixed value of the differential limiting torque control command at the time when the start of the traction control operation is determined is provided, the steer characteristic sudden change in the normal turning region is prevented and the turning limit region is provided. It is possible to obtain the effect that both stability and acceleration can be ensured at the same time.

[Brief description of drawings]

FIG. 1 is a claim correspondence diagram showing a comprehensive control device for traction and differential limiting torque according to the present invention.

FIG. 2 is an overall system diagram of a rear-wheel drive vehicle to which an integrated traction and differential limiting torque control device according to an embodiment is applied.

FIG. 3 is a flowchart showing a flow of a total control operation of a traction and a differential limiting torque, which is performed by a differential limiting torque control section of the overall control unit of the embodiment apparatus.

[Explanation of symbols]

 a Traction control means b Differential limiting torque control means c Traction control operating determination means d Differential limiting torque control command setting means e General control means

Claims (1)

[Claims] 1. A traction control means for reducing and controlling traction when an acceleration slip occurs, and a differential limiting torque for controlling a differential limiting torque of left and right driving wheels based on predetermined input information such as an accelerator opening, a vehicle speed and a lateral acceleration. The control means, the traction control operation judging means for judging whether or not the traction reduction control for suppressing the acceleration slip is in operation, and the differential limiting torque when the start of the traction control operation is judged by the traction control operation judging means. The differential limiting torque control command setting means for setting the differential limiting torque control command output in the control means, and the normal differential limiting torque control according to the predetermined input information during the operation of the traction control are set instead. Comprehensive control means for performing differential limiting torque control using the differential limiting torque control command as a fixed value, The general control unit of the traction and differential limiting torque, characterized in that it comprises.