JPH05248280A - Traction control device for vehicle - Google Patents

Abstract

PURPOSE:To compatibly provide accelerating performance at the time of high friction coefficient road running and stability at the time of large control frequency condition acceleration by performing control so as to enter against generation of an acceleration slip easier than the normal drive wheel torque control when the drive wheel torque control is performed in a large frequency. CONSTITUTION:An acceleration slip condition of a drive wheel is detected by an acceleration slip condition detecting means (a). Drive wheel torque is controlled to be decreased in accordance with the acceleration slip condition by a drive wheel torque control means (b). Further, a control frequency of the drive wheel torque is detected by a control frequency detecting means (d). When a large control frequency is detected, control is performed against generation of an acceleration slip to enter easier than the normal drive wheel torque control by an acceleration time corresponding control means (e). On the other hand when the control frequency is detected small, the drive wheel torque is controlled to be decreased in accordance with the acceleration slip condition. In this way, accelerating performance at the time of high friction coefficient road running and stability at the time of acceleration in a low friction coefficient road running condition and a large control frequency are compatibly obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vehicle traction control device for controlling drive wheel torque in accordance with an acceleration slip state.

[0002]

2. Description of the Related Art Conventionally, as a vehicle traction control device for controlling driving wheel torque in accordance with an acceleration slip state, for example, a device disclosed in Japanese Patent Laid-Open No. 61-85248 is known.

[0003]

However, in the conventional vehicle traction control device described above, the control is such that the reduction amount of the driving wheel torque is increased as the pre-control acceleration slip state increases. Therefore, when the driver suddenly accelerates the vehicle while traveling on a low friction coefficient road, the reduction response of the driving wheel torque is delayed and the vehicle stability is deteriorated.

That is, the normal drive wheel torque reduction response is
When the torque is excessively reduced, the acceleration performance on the high friction coefficient road is impaired, so that the response is set to follow the gradual growth of the acceleration slip. However, when the vehicle travels on a road surface having a low friction coefficient, even if the driver slowly depresses the accelerator pedal, the amount of reduction in the drive wheel torque against the occurrence of acceleration slip is insufficient, and the convergence of acceleration slip is poor. Also, if the driver frequently performs a sudden accelerator depressing operation, an acceleration slip will occur each time the accelerator depressing operation is performed, and the drive wheel torque reduction control will be performed frequently. The driving wheel torque reduction response is delayed with respect to this rapid acceleration slip growth.

The present invention has been made by paying attention to the above problems, and in a traction control device for a vehicle, which controls a driving wheel torque in accordance with an acceleration slip state, the acceleration performance during traveling on a high friction coefficient road and It is an object to achieve both low friction coefficient road stability and stability when accelerating in a state of frequent control.

[0006]

In order to solve the above problems, the traction control device for a vehicle according to the present invention uses a normal drive wheel when a low road surface friction coefficient equivalent value is detected or a large control frequency is detected. The torque control is used to make it easier to enter control when an acceleration slip occurs.

That is, as shown in the claim correspondence diagram of FIG. 1, an acceleration slip state detection means a for detecting the acceleration slip state of the drive wheel, and a drive wheel torque control for reducing the drive wheel torque according to the acceleration slip state. Means b, control frequency detection means d for detecting the drive wheel torque control frequency, and when the control frequency detection means d detects a large control frequency, control is performed with respect to the occurrence of acceleration slip as compared with normal drive wheel torque control. It is characterized in that it is provided with an acceleration response control means e for facilitating entry.

[0008]

When the control frequency is low, the drive wheel torque control means b controls the drive wheel torque to be reduced according to the acceleration slip state detected by the acceleration slip state detection means a.

When a large driving wheel torque control frequency is detected by the control frequency detecting means d, the acceleration-corresponding control means e is more likely to enter the control for the occurrence of acceleration slip than the normal driving wheel torque control.

[0010]

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 braking / driving system control system for a rear-wheel drive vehicle to which the vehicle traction control device according to the embodiment of the present invention is applied.

In this rear-wheel drive vehicle, the throttle control for controlling the motor throttle opening so that the rear-wheel slip ratio falls within the optimum allowable range when acceleration slip occurs, and the left and right rear wheels independently when acceleration slip occurs. A traction control system (corresponding to a traction control device for vehicles) that is used together with a brake control that applies braking force is also installed, and anti-skid brakes that perform front and rear wheel brake pressure control to prevent wheel lock during deceleration slip A control system is installed. And the centralized electronic control of these systems is the traction control system & anti-skid brake control system electronic control unit TCS / AB
It is performed by S-ECU (hereinafter, abbreviated as TCS / ABS-ECU).

The TCS / ABS-ECU includes a right front wheel speed sensor 1
Right front wheel speed sensor value VWFR, left front wheel speed sensor 2 left front wheel speed sensor value VWFL, right rear wheel speed sensor 3 right rear wheel speed sensor value VWRR, and left rear wheel speed sensor 4 Left rear wheel speed sensor value VWRL, lateral acceleration sensor value YG from lateral acceleration sensor 5, switch signal SWTC from TCS switch 6, switch signal SWST from brake lamp switch 7, throttle control module TCM (hereinafter, Throttle 1 actual opening DKV from TCM)
And the automatic transmission control unit A /
Gear position signal and shift-up signal from TC / U (hereinafter abbreviated as A / TC / U) and engine rotation from the engine centralized electronic control unit ECCS C / U (hereinafter abbreviated as ECCS C / U) The number signal and the second throttle signal TVO2 or the like from the second throttle sensor 17 are input.

Then, from the TCS / ABS-ECU, the acceleration slip is detected and the throttle 2 as a throttle opening / closing signal is detected.
The target opening DKR is output to TCM, and the solenoid signal as the brake pressure increase / decrease signal is output to each solenoid valve of the shared hydraulic unit TCS / ABS-HU (hereinafter abbreviated as TCS / ABS-HU). .. The throttle control side of this traction control is called TCS throttle control, and the brake control side is called TCS brake control.

Further, the TCS / ABS-ECU detects a deceleration slip and outputs a solenoid signal as a brake pressure increasing / decreasing signal to each solenoid valve of the TCS / ABS-HU. This anti-skid brake control is called ABS brake control.

In addition to the above output, the TCS / ABS-ECU outputs a lighting command to the TCS fail lamp 14 when the TCS fails, and outputs a lighting command to the TCS operation lamp 15 while the TCS is operating.

The TCM is a control circuit centered on a throttle motor drive circuit, which receives the first throttle signal TVO1 from the first throttle sensor 16 and outputs it to the TCS / ABS-ECU as the throttle 1 actual opening DKV. Or input the second throttle signal TVO2 from the second throttle sensor 17 as feedback information for the throttle 2 target opening DKR, or input the throttle 2 target opening DK from the TCS / ABS-ECU.
A motor drive current IM is applied to the throttle motor 18 based on R.

Here, the first throttle valve 19 provided with the first throttle sensor 16 is the accelerator pedal 2
The second throttle valve 21, which is a valve that operates in conjunction with 0, is provided in the engine intake passage 22 in series with the first throttle valve 19 and is opened and closed by the throttle motor 18. It is a valve that is used.

The traction control system includes an air flow meter AFM as a peripheral system as shown in the figure.
It has an ECCS C / U and an injector, and an engine centralized electronic control system that centrally controls fuel injection control, ignition timing control, idle speed correction, etc. is installed. When the ON signal is input, control for selecting a smaller valve opening of the first throttle signal TVO1 and the second throttle signal TVO2 (select low control) is performed to correct the transient characteristics, and the canister control and EGR control are performed. It will be canceled.

As a peripheral system, as shown in the figure, an automatic transmission control system having an A / TC / U and a shift solenoid for performing gear shift control, lockup control, etc. is installed. The gear position signal and shift-up signal are fetched from TCS / ABS-ECU.

Further, as a peripheral system, as shown in the figure, an ASCD actuator is provided, and a constant speed traveling control system for automatically controlling the vehicle speed so as to maintain the set vehicle speed is mounted, and in order to prevent control interference, When the ON signal of the traction switch signal TCS SW is input, the opening control of the first throttle valve 19 is stopped, and when the OFF signal of the TCS SW is input, the return speed of the first throttle valve 19 is made gentle.

FIG. 3 is a hydraulic circuit diagram showing a brake pressure control system commonly used for the TCS brake control for the left and right rear wheels and the ABS brake control for the four wheels.

This brake pressure control system includes a brake pedal 27, a hydraulic booster 28, a master cylinder 30 having a reservoir 29, wheel cylinders 31, 32, and
33, 34 and shared hydraulic unit TCS / ABS-HU
, Pump unit PU, and first accumulator unit
AU1, 2nd accumulator unit AU2, front wheel side damping unit FDPU, rear wheel side damping unit RD
It is equipped with PU.

The TCS / ABS-HU has a first switching valve TV1.
, Second switching valve TV2, left front wheel pressure increasing valve 36a
And right front wheel pressure increasing valve 36b and left rear wheel pressure increasing valve 36
c, right rear wheel pressure increasing valve 36d, left front wheel pressure reducing valve 3
7a, a right front wheel pressure reducing valve 37b, a left rear wheel pressure reducing valve 37c, a right rear wheel pressure reducing valve 37c, a front wheel side reservoir 38a, a rear wheel side reservoir 38b, and a front wheel side pump 39.
a, the rear wheel side pump 39b, and the front wheel side damper chamber 40a
And a rear wheel side damper chamber 40b and a pump motor 41.

During normal braking and ABS brake control, both switching valves TV1 and TV2 are turned off as shown in order to introduce the pressure from the master cylinder 30.
When the TCS brake is controlled, both switching valves TV1 and TV2 are turned to the ON position in order to introduce the pressure from the second accumulator unit AU2. Then, for example, in the pressure increasing mode of the TCS brake control, both control valves 36c, 36d, 37c, 37d are as shown in the drawing.
In the OFF position and in the holding mode, the booster valve 36
Only c and 36d are set to the ON position, and in the depressurization mode, both control valves 36c, 36d, 37c and 37d are set to the ON position, the brake fluid from the wheel cylinders 33 and 34 is stored in the rear wheel side reservoir 38b, and further, By the rotation of the rear wheel side pump 39b, it is returned to the rear wheel side damper chamber 40b.

The first accumulator unit AU1 is used as a hydraulic pressure source for the hydraulic booster 28, and the second accumulator unit AU2 is used as a hydraulic pressure source for TCS brake control. Predetermined accumulator pressure is maintained by the common pump unit PU that draws in.

The front wheel side damping unit FDPU and the rear wheel side damping unit RDPU are shared hydraulic units TCS / AB in order to improve pedal feeling.
The influence of the pressure change in the S-HU on the master cylinder 30 is suppressed.

The operation will be described.

(B) Outline of basic traction control FIG. 4 is a control block diagram showing an outline of basic traction control performed by the TCS / ABS-ECU. The traction control logic has the following four types of control. It can be roughly divided.

(1) Calculation of Actual Slip State The signals of the wheel speed sensors 1, 2, 3, 4 are filtered, and the actual slip state (for each of the left and right sides) is independently calculated based on the wheel speed value after the filtering. The slip amount based on the difference between the rear wheel speed and the front wheel speed average value, and the rear wheel speed difference value at 30 msec are calculated (corresponding to acceleration slip state detection means).

(2) Calculation of Target Slip State The signal of the lateral acceleration sensor 5 is filtered to calculate the target slip state corresponding to the running state based on the turning / straight ahead determination based on the lateral acceleration and the vehicle speed.

(3) TCS Brake Control Comparing the actual slip state and the target slip state, the required brake pressure increase / decrease speed (control duty ratio) is calculated and output to TCS / ABS-HU.

(4) TCS throttle control Comparing the actual slip state and the target slip state, the necessary throttle opening and opening / closing speed are calculated and output to TCM.

This control logic is characterized by low μ to high μ.
In order to secure the limit detectability (steering force, skill sound, etc.) based on the base chassis performance according to each road surface condition and to obtain active safety, the allowable slip state according to the magnitude of lateral acceleration, The allocation of throttle / brake control has been decided.

Further, in order to secure stability during shifting and improve controllability at each gear position, throttle / brake control is performed according to the gear position.

Further, in order to suppress slip hunting, to realize a smooth acceleration feeling and controllability, and to realize a responsive engine torque increase / decrease control, optimum throttle control according to the engine speed is performed.

(B) ABS brake control action When the deceleration slip of each wheel exceeds the deceleration slip threshold during braking, the solenoid signal as the brake pressure increasing / decreasing signal is independently applied to each wheel of each solenoid valve of TCS / ABS-HU. It is done by outputting to.

By this control, the wheel lock is suppressed when the braking force becomes excessive and the wheel lock is likely to occur, such as at the time of low friction coefficient road braking or sudden braking.
The braking stability of the vehicle and the braking distance can be shortened.

(C) Traction control action for acceleration time FIG. 5 is a flow chart showing the flow of the traction control process operation for acceleration time performed by the TCS / ABS-ECU.
Each step will be described.

In step 50, it is judged whether excessive acceleration slip over the control threshold value, at which both the TCS throttle control and the TCS brake control are constantly performed, is generated based on the detection of the acceleration slip state.
If NO is determined in this step 50, step 51
Proceed to transition.

In step 51, the slipperiness μ _T of the road surface is detected (corresponding to road surface friction coefficient equivalent value detecting means).

The slipperiness μ _T of the road surface is determined by estimating the driven wheel speed and the drive wheel speed using the following formula or the like.

(1) μ _T = {(drive wheel speed)-(driven wheel speed)} / (drive wheel speed) (2) μ _T = (drive wheel speed)-(driven wheel speed) The control frequency N _T during ΔTsec is detected (corresponding to control frequency detection means).

This control frequency N _T is in the past ΔT sec.
It is detected by (1) calculating the drive wheel torque control amount, or (2) counting the number of times of drive wheel torque control.

In step 53, it is judged whether the slipperiness μ _T of the road surface is small (low μ road surface) and the control frequency N _T is high.

If YES at step 53,
In step 54, the drive wheel torque control is facilitated.

As a method for facilitating this control, (1) decrease the control threshold value (2) improve the response of the control mechanism (increase the control current).

If YES is determined in step 50,
The routine proceeds to step 55, where the driving wheel torque control is performed by using both throttle control and brake control in accordance with the acceleration slip state.

(D) TCS control action during traveling When the control frequency N _T is low or the road surface has a large slipperiness μ _T (high μ road surface), step 5 in FIG.
From 0 → step 51 → step 52 → step 53, the process directly returns to step 50, and when it is detected that the acceleration slip state exceeds the throttle control threshold value or the brake control threshold value, excessive acceleration slip occurs, and the steps 50 to 55 are performed. Then, the drive wheel torque control is performed by using both throttle control and brake control.

Therefore, the drive wheel torque control is performed by the normal drive wheel torque reduction response that follows the gradual growth of the acceleration slip, and the accelerating property when traveling on a high friction coefficient road is ensured.

When the control frequency N _T is high and the road surface is less slippery μ _T (low μ road surface), the routine proceeds to step 50 → step 51 → step 52 → step 53 → step 54 in FIG. The driving wheel slip control is facilitated by a method such as setting the throttle control threshold value or the brake control threshold value to a small value, and then it is detected in step 50 that excessive acceleration slip exceeding the control threshold value has occurred. When step 50 to step 5
5, the driving wheel torque control is performed by using both throttle control and brake control.

Therefore, when the vehicle travels on a road surface having a low friction coefficient, the condition of step 53 is satisfied, and the control is facilitated in step 54, so that the drive wheel torque reduction amount is increased more than usual and an acceleration slip occurs. On the other hand, by sufficiently reducing the driving wheel torque, the acceleration slip is quickly settled, and the vehicle stability is ensured even if the driver depresses the accelerator pedal based on an unexpected intention of acceleration. Since this torque reduction amount is given in an amount proportional to the difference between the acceleration slip state and the control threshold value, for example, when the control threshold value is reduced to facilitate control, the acceleration slip state and the control value are reduced. The difference between the threshold values becomes large, and the torque reduction amount also becomes large.

Further, in the case of a driver who frequently performs a sudden accelerator depressing operation, an acceleration slip occurs every time the accelerator depressing operation is performed and the driving wheel torque reduction control is frequently performed. By satisfying the condition of 53 and making it easy to enter the control in step 54, the driving wheel torque is reduced with a good response to the rapid growth of the acceleration slip accompanying the accelerator depression operation.
The occurrence of excessive acceleration slip is suppressed and the stability of the vehicle is increased. For example, when the control threshold is reduced to facilitate the control, the timing at which the acceleration slip state exceeds the control threshold becomes early, and the earlier the drive wheel slip control is entered, the higher the response to the occurrence of the acceleration slip becomes.

It should be noted that the fact that the control frequency N _T is high serves as information that the driver knows that the road surface friction coefficient is low when the driver performs normal accelerator work. At this time, the slipperiness μ _T of the road surface is detected. By double detection of, the road friction coefficient will be monitored. Further, the control frequency N _T may be high even when traveling on a high friction coefficient road, and in this case, as described above, the driver's accelerator work is a driver who frequently depresses while performing sports driving. It will be information to know that.

The effect will be described.

In a vehicle traction control device that controls the driving wheel torque by using both throttle control and brake control in accordance with the acceleration slip state, the slipperiness μ of the road surface
_When it is detected that _T is small (low μ road surface) or the control frequency N _T is high, the device is designed to make it easier to enter the control for the occurrence of acceleration slip than the normal drive wheel torque control. It is possible to achieve both the acceleration performance when traveling on a road and the stability when accelerating in a low friction coefficient road traveling state or a state where the control frequency is high.

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 application to a traction control system using a combination of throttle and brake is shown, but it can also be applied to a system that performs traction control by only throttle control or brake control. Further, as the engine output reduction control system, ignition cut, cylinder cut, ignition timing retard, etc. may be used in addition to the throttle control.

[0060]

As described above, according to the present invention, a large control frequency of the drive wheel torque control is detected in the vehicle traction control device for controlling the drive wheel torque according to the acceleration slip state. At the time of driving, the control means for acceleration is provided to make it easier to enter control when an acceleration slip occurs compared to normal drive wheel torque control. In this state, it is possible to achieve the effect of achieving both stability when accelerating.

[Brief description of drawings]

FIG. 1 is a claim correspondence diagram showing a vehicle traction control device of the present invention.

FIG. 2 is an overall view of a braking / driving system control system of a rear-wheel drive vehicle to which the vehicle traction control device of the embodiment is applied.

FIG. 3 is a hydraulic circuit diagram showing a brake pressure control system of a braking / driving system control system to which the vehicle traction control device of the embodiment is applied.

FIG. 4 is a block diagram showing an outline of traction control in the embodiment.

FIG. 5 is a flow chart showing a flow of acceleration traction control operation performed by the TCS & ABS electronic control unit of the embodiment apparatus.

[Explanation of symbols]

 a Acceleration slip state detection means b Drive wheel torque control means c Road surface friction coefficient equivalent value detection means d Control frequency detection means e Acceleration time correspondence control means

Claims (1)

[Claims] 1. An acceleration slip state detection means for detecting an acceleration slip state of a drive wheel, a drive wheel torque control means for reducing a drive wheel torque according to the acceleration slip state, and a control for detecting a drive wheel torque control frequency. Frequency control means, and when the control frequency detection means detects a large control frequency, acceleration-time-corresponding control means that makes it easier to enter control in response to the occurrence of acceleration slip than normal drive wheel torque control, Vehicle traction control device characterized by