JP2882151B2 - Traction control device for vehicles - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a traction control device for a vehicle for controlling traction to suppress acceleration slip when a detected acceleration slip exceeds a control threshold value corresponding to a lateral acceleration.

[0002]

2. Description of the Related Art Conventionally, as a traction control device for a vehicle which detects a lateral acceleration state and changes a control threshold value in accordance with lateral acceleration information, for example, Japanese Patent Application Laid-Open No. 58-16948
An apparatus described in Japanese Unexamined Patent Publication (Kokai) No. H10-264 is known.

[0003]

However, in such a conventional traction control device for a vehicle, only one lateral acceleration judgment value branching between a low lateral acceleration region and a high lateral acceleration region is set, and the lateral acceleration is determined. Since the control threshold value is changed depending on whether the detected acceleration value is larger or smaller than the lateral acceleration judgment value, the acceleration slip during turning when the lateral acceleration detected value fluctuates near the lateral acceleration judgment value. Occurs, traction control hunting occurs due to a change in the control threshold value.

That is, when the detected value of the lateral acceleration is smaller than the judgment value of the lateral acceleration, for example, by setting a low control threshold value which facilitates the acceleration slip control, vehicle stability can be obtained.
When the lateral acceleration detection value is larger than the lateral acceleration judgment value, for example, setting a high control threshold value that is difficult to enter the acceleration slip control improves the acceleration performance, but when control hunting occurs, the stability and the acceleration performance are repeated. Not only the desired performance cannot be obtained, but also the vehicle behavior becomes unstable in the turning limit region.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problem, and is intended for a vehicle for controlling traction to suppress acceleration slip when a detected acceleration slip exceeds a control threshold value corresponding to lateral acceleration. In the traction control device, control hunting is prevented during turning when acceleration slip occurs, and when lateral acceleration increases, stability in the low lateral acceleration range and acceleration performance in the high lateral acceleration range are compatible, and lateral acceleration is reduced. At times, the goal is to shift to a stable side while balancing acceleration and stability.

[0006]

In order to solve the above-mentioned problems, a traction control device for a vehicle according to the present invention sets a first lateral acceleration judgment value and a second lateral acceleration judgment value as lateral acceleration judgment values and increases lateral acceleration. When the lateral acceleration decreases, the control threshold value is gradually changed from the low control threshold value to the high control threshold value after the second lateral acceleration determination value. When the lateral acceleration decreases, the control threshold value is gradually reduced to the first lateral acceleration determination value. Means.

That is, as shown in the claim correspondence diagram of FIG. 1, acceleration slip detecting means a for detecting an acceleration slip
A lateral acceleration detecting means b for detecting a lateral acceleration, a lateral acceleration determining value for setting a first lateral acceleration determining value existing in a low lateral acceleration region and a second lateral acceleration determining value existing in a high / low branch region of the lateral acceleration. a setting unit c, when the lateral acceleration increases the lateral acceleration detected value to the second lateral acceleration determination value maintaining low control threshold, the lateral acceleration detection value exceeds a second lateral acceleration determination value low
Threshold from control threshold to high control threshold at once
When the lateral acceleration decreases, the lateral acceleration detection value is used until the lateral acceleration detection value becomes the first lateral acceleration judgment value.
The threshold value is gradually reduced as
Control threshold value setting means d for maintaining a low control threshold value when the speed detection value becomes equal to or less than the first lateral acceleration judgment value, and a control threshold value for setting the acceleration slip detection value by the control threshold value setting means d. And a traction control means e for controlling traction so as to suppress the acceleration slip when the value exceeds the value.

[0008]

When the lateral acceleration rises, for example, when shifting from straight running to high-μ road turning, the control threshold value setting means d
Lateral acceleration detection value from the lateral acceleration detecting means b is up to second lateral acceleration determination value is maintained low control threshold, the lateral acceleration detection
If the output value exceeds the second lateral acceleration judgment value, is it a low control threshold?
Is set to a control threshold value at which the threshold value is immediately increased to a high control threshold value . In the traction control means e, when the acceleration slip detection value from the acceleration slip detection means a exceeds the control threshold value set by the control threshold value setting means d, the traction is controlled to suppress the acceleration slip. Note that the second lateral acceleration determination value is set by the lateral acceleration determination value setting means c as a value existing in a branch region between the low lateral acceleration region and the high lateral acceleration region. Therefore, when the lateral acceleration rises, the stability is maintained by maintaining the low control threshold value that is easy to enter the control in the low lateral acceleration range, and the high control threshold value is difficult to enter the control in the high lateral acceleration range. And the acceleration performance is achieved.

When the lateral acceleration decreases, for example, when the vehicle shifts from high-μ road turning to straight traveling, the control threshold setting means d determines the lateral acceleration detection value from the lateral acceleration detection means b as the first lateral acceleration judgment value. according to the decrease in lateral acceleration detection value until
The threshold value is gradually reduced, and when the lateral acceleration detection value becomes equal to or smaller than the first lateral acceleration determination value, the control threshold value is set to maintain the low control threshold value. In the traction control means e, when the acceleration slip detection value from the acceleration slip detection means a exceeds the control threshold value set by the control threshold value setting means d, the traction is controlled to suppress the acceleration slip. Note that the first lateral acceleration determination value is set by the lateral acceleration determination value setting means c as a value existing in the low lateral acceleration range. Therefore, when the lateral acceleration decreases, the control threshold value gradually decreases in proportion to the decrease in the lateral acceleration detection value, so that a shift to the stable side is achieved while balancing acceleration and stability.

At the time of turning in which the detected value of lateral acceleration fluctuates by a value near the lateral acceleration judgment value when an acceleration slip occurs,
Since the first lateral acceleration determination value and the second lateral acceleration determination value are set as the lateral acceleration determination values, and the control threshold value is provided with hysteresis, the occurrence of traction control hunting is prevented.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The configuration will be described.

FIG. 2 is an overall view of a braking / drive 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.

This rear-wheel drive vehicle has a throttle control for controlling a motor throttle opening degree so that a rear wheel slip ratio is within an optimum allowable range when an acceleration slip occurs, and is independent for right and left rear wheels when an acceleration slip occurs. Anti-skid brake control, which is equipped with a traction control system (corresponding to traction control means) that is used in combination with brake control that applies braking force to the front and rear wheels to prevent wheel lock during deceleration slip. The 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 / ABS-ECU
(Hereinafter abbreviated as TCS / ABS-ECU).

The TCS / ABS-ECU has a right front wheel speed sensor 1
From the right front wheel speed sensor value VFR from the left front wheel speed sensor 2, the right rear wheel speed sensor value VRR from the right rear wheel speed sensor 3, and the The left rear wheel speed sensor value VRL, the lateral acceleration sensor value YG from the lateral acceleration sensor 5 (corresponding to lateral acceleration detecting means), the switch signal SWTC from the TCS switch 6, and the switch signal SWST from the brake lamp switch 7 , Throttle actual opening DKV from throttle control module TCM (hereinafter abbreviated as TCM) and automatic transmission control unit A / TC / U (hereinafter abbreviated as A / TC / U)
, A gear position signal and an upshift signal, an engine speed signal from an engine centralized electronic control unit ECCS C / U (hereinafter abbreviated as ECCS C / U), and a second throttle signal from a second throttle sensor 17. TVO2 etc. are input.

From the TCS / ABS-ECU, an acceleration slip is detected and the throttle 2 as a throttle opening / closing signal is detected.
The target opening DKR is output to the TCM, and a solenoid signal as a brake pressure increase / decrease signal is output to each solenoid valve of the common hydraulic unit TCS / ABS-HU (hereinafter abbreviated as TCS / ABS-HU). (TCS throttle control and TCS brake control). Also, a deceleration slip is detected, and a solenoid signal as a brake pressure increase / decrease signal is output to TCS /
Output to each solenoid valve of ABS-HU (ABS control). In addition, the TCS / ABS-ECU outputs TCS
At the time of a failure, a lighting command is output to the TCS fail lamp 14, and a lighting command is output to the TCS operating lamp 15 during TCS operation.

The TCM is a control circuit mainly including a throttle motor drive circuit. The TCM receives a first throttle signal TVO1 from a first throttle sensor 16 and outputs it to a TCS / ABS-ECU as a throttle 1 actual opening degree DKV. Or input the second throttle signal TVO2 from the second throttle sensor 17 as feedback information to 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 connected to the accelerator pedal 2.
The second throttle valve 21 provided with the second throttle sensor 17 is provided in the engine intake passage 22 in series with the first throttle valve 19, and is opened / closed by the throttle motor 18. Valve.

The traction control system includes an air flow meter AFM as a peripheral system as shown in FIG.
And an ECCS C / U and an injector, and an engine centralized electronic control system that performs centralized control of fuel injection control, ignition timing control, idle speed correction, etc., is installed. When the ON signal is input, control (select low control) for selecting a smaller valve opening degree of the first throttle signal TVO1 and the second throttle signal TVO2 is performed for transient characteristic correction, and the canister control and the EGR control are performed. Aborted.

As shown in the figure, an automatic transmission control system which has an A / TC / U and a shift solenoid and performs shift control, lock-up control, etc. is mounted as a peripheral system. , The gear position signal and the shift-up signal are taken into the TCS / ABS-ECU.

Further, as a peripheral system, as shown, a constant speed traveling control system having an ASCD actuator and performing automatic vehicle speed control so as to maintain a set vehicle speed is mounted. 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 reduced.

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

The brake fluid pressure control system comprises a brake pedal 27, a hydraulic booster 28, a master cylinder 30 having a reservoir 29, wheel cylinders 31, 32,
33, 34, shared hydraulic unit TCS / ABS-HU
, Pump unit PU, and first accumulator unit
AU1, second accumulator unit AU2, front wheel side damping unit FDPU, rear wheel side damping unit RD
With PU.

The TCS / ABS-HU has a first switching valve 35a.
, A second switching valve 35b, and a left front wheel pressure increasing valve 36a.
, A right front wheel pressure increasing valve 36b and a 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, a rear wheel side pump 39b, and a front wheel side damper chamber 40a.
And a rear-wheel-side damper chamber 40b and a pump motor 41.

At the time of normal braking or ABS control, both switching valves 35a and 35b are set to the OFF position as shown in order to introduce the hydraulic pressure from the master cylinder 30, and at the time of TCS brake control, the second accumulator unit is set. Both switching valves 35 to introduce hydraulic pressure from AU2
a and 35b are set to the ON position. And, for example, TCS
In the pressure increasing mode in the brake control, both control valves 36
c, 36d, 37c, and 37d are set to the OFF position as shown in the figure. In the holding mode, only the pressure increasing valves 36c and 36d are set to the ON position.
The positions c, 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 returned to the rear wheel side damper chamber 40b by the rotation of the rear wheel side pump 39b. It is.

The first accumulator unit AU1 comprises:
The second accumulator unit AU2 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. Thus, a predetermined accumulator pressure is maintained.

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

The operation will be described.

(A) Normal Traction Control Operation FIG. 4 is a control block diagram showing an outline of the traction control performed by the TCS / ABS-ECU. The traction control logic can be roughly classified into the following four types of control.

(1) Calculation of Actual Slip State Filter processing is performed on the signals from the wheel speed sensors 1, 2, 3, and 4, and based on the wheel speed values after the filter processing, the actual slip state (slip amount, slip amount difference) is calculated. Value) (corresponding to acceleration slip detecting means).

(2) Calculation of Target Slip State A signal from the lateral acceleration sensor 5 is subjected to a filtering process, and a turning / straight traveling judgment based on the lateral acceleration and a target slip state suitable for the running state are calculated based on the vehicle speed.

(3) TCS brake control When the actual slip state exceeds a control threshold value corresponding to a lateral acceleration, which will be described later, the actual slip state is compared with the target slip state to determine the required brake increasing / decreasing speed (control duty). Ratio) and output to TCS / ABS-HU.

(4) TCS Throttle Control When the actual slip state exceeds a control threshold value corresponding to lateral acceleration, which will be described later, the actual slip state is compared with the target slip state to determine the necessary throttle opening and opening / closing speed. Calculate and output to TCM.

(B) Traction control action by lateral acceleration corresponding control threshold FIG. 5 is a flow chart showing the flow of traction control processing operation by the lateral acceleration corresponding control threshold performed in the TCS / ABS-ECU. The steps will be described.

In step 50, a lateral acceleration detection value YG obtained by filtering the sensor signal from the lateral acceleration sensor 5 is read, and a lateral acceleration differential value YG 'is calculated.

In step 51, a control threshold value correction coefficient β is set based on the lateral acceleration detection value YG, the lateral acceleration differential value YG ', and the correction coefficient characteristics described in the step frame.

The correction coefficient characteristic will be described. First, the first lateral acceleration determination value YG1 existing in the low lateral acceleration range is set.
(For example, 0.5G) and the second lateral acceleration determination value YG2 (for example, 0.6G to 0.5G) which exists in the branch region between the low lateral acceleration region and the high lateral acceleration region.
0.65G) (corresponding to the lateral acceleration judgment value setting means). The lateral acceleration rising characteristic determined by the positive lateral acceleration differential value YG ′ is such that the control threshold value correction coefficient β = 1 when the lateral acceleration detection value YG reaches the second lateral acceleration determination value YG2.
Is maintained and exceeds the second lateral acceleration determination value YG2, the control rises at once and the control threshold value correction coefficient β increases in proportion to the lateral acceleration detection value YG. Also, the lateral acceleration differential value
The lateral acceleration reduction characteristic determined by the fact that YG 'is negative is
The control threshold value correction coefficient β gradually decreases in proportion to the decrease in the lateral acceleration detection value YG until the lateral acceleration detection value YG becomes the first lateral acceleration judgment value YG1 along the proportional characteristic portion of the lateral acceleration increase characteristic. , The control threshold value correction coefficient β = 1 is maintained when the value becomes equal to or less than the first lateral acceleration determination value YG1.

In step 52, a throttle control threshold value SLPEN is calculated from the control threshold value correction coefficient β set in step 51 and the throttle control threshold value SLPENO during straight running, and the control threshold value set in step 51 is calculated. The brake control threshold value SLPBK is calculated from the correction coefficient β and the straight-travel-time brake control threshold value SLPBKO (corresponding to control threshold value setting means).

In step 53, the TCS throttle control described in (a) above is performed based on the throttle control threshold value SLPEN, and the brake control threshold value SLPBK
Based on the above, the TCS brake control described in the above (a) is performed.

(C) When the lateral acceleration rises When the lateral acceleration rises, for example, when shifting from straight running to high-μ road turning, in step 51, the lateral acceleration rise characteristic is selected and the control threshold correction coefficient β is increased. With this setting, in step 52, the same low control threshold value as in the straight traveling is maintained until the lateral acceleration detection value YG becomes the second lateral acceleration determination value YG2, and when the lateral acceleration detection value YG exceeds the second lateral acceleration determination value YG2. It is set to a high control threshold value that rises at a stretch and rises in proportion to the rise in the lateral acceleration detection value YG. In step 53, when the acceleration slip state exceeds the throttle control threshold value SLPEN, TCS throttle control is performed,
When the acceleration slip state exceeds the brake control threshold value SLPBK, TCS brake control is performed.

Therefore, when the lateral acceleration rises, the stability is maintained by maintaining the low control threshold value that facilitates the control in the low lateral acceleration range equal to or less than the second lateral acceleration determination value YG2, and the second lateral acceleration determination value YG2 By setting a high control threshold value that makes it difficult to enter control in the high lateral acceleration range described above, compatibility with acceleration can be achieved. In particular, when the control threshold value rises at once when the value exceeds the second lateral acceleration determination value YG2, T
In many cases, the CS control ends once, and it is easy to secure acceleration. Further, in a high lateral acceleration range equal to or higher than the second lateral acceleration determination value YG2, the turning controllability is improved by setting the proportional characteristic to increase the control threshold value in proportion to the lateral acceleration detection value YG.

(D) When the lateral acceleration decreases When the lateral acceleration decreases, for example, when the vehicle shifts from turning on a high-μ road to straight traveling, in step 52, the lateral acceleration detection value YG becomes equal to the first lateral acceleration judgment value YG1. Is set to a control threshold value that gradually decreases in proportion to the decrease in the lateral acceleration detection value YG along the proportional characteristic portion of the lateral acceleration increase characteristic. The control threshold is set to maintain the control threshold. Step 53
In the acceleration slip state, the throttle control threshold SLPE
N, TCS throttle control is performed, and when the acceleration slip condition exceeds the brake control threshold value SLPBK, TCS throttle control is performed.
CS brake control is performed.

Therefore, when the lateral acceleration decreases, the control threshold value gradually decreases in proportion to the decrease in the lateral acceleration detection value YG, so that the acceleration and controllability in the high lateral acceleration range are ensured. In the transition from the high lateral acceleration range to the low lateral acceleration range, the transition to the stable side is achieved while balancing acceleration and stability.

(E) At the time of lateral acceleration hunting When the vehicle is turning such that the lateral acceleration detection value YG fluctuates by a value near the second lateral acceleration determination value YG2 when an acceleration slip occurs, the first lateral acceleration determination value is used as the lateral acceleration determination value. The value YG1 and the second lateral acceleration determination value YG2 are set, and the control threshold value obtained in step 52 is given a hysteresis.
The occurrence of the traction control hunting in which the start and the end of the S control are repeated is prevented.

The effect will be described.

(1) When the acceleration slip state exceeds a control threshold value corresponding to the lateral acceleration, a traction control device for a vehicle that controls traction by using both throttle control and brake control in order to suppress acceleration slip is used to determine a lateral acceleration. The first lateral acceleration judgment value YG1 and the second lateral acceleration judgment value YG2 are set as values, and when the lateral acceleration rises, the threshold value is stepped from the low control threshold value to the high control threshold value starting from the second lateral acceleration judgment value YG2. When the lateral acceleration decreases, the control threshold value is gradually lowered to the first lateral acceleration determination value YG1. Therefore, control hunting can be prevented during turning while an acceleration slip occurs, and At the time of acceleration rise, stability at low lateral acceleration range and acceleration at high lateral acceleration range are compatible, and at the time of decrease of lateral acceleration, safety is maintained while balancing acceleration and stability. The shift to the fixed side can be achieved.

(2) In the high acceleration range equal to or higher than the second lateral acceleration judgment value YG2, both the ascending characteristic and the decreasing characteristic are set to the proportional characteristics proportional to the lateral acceleration detection value YG. The turning controllability can be improved as compared with the case where the control threshold is set.

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

For example, in the embodiment, an example of means for using both TCS throttle control and TCS brake control as traction control means has been described. However, means having only one of them may be used. Other control means that can control the engine output, such as timing retard control, may be used.

[0049]

As described above, according to the present invention, a traction control device for a vehicle for controlling traction to suppress an acceleration slip when an acceleration slip detection value exceeds a control threshold value corresponding to a lateral acceleration. In claim 1, a first lateral acceleration judgment value and a second lateral acceleration judgment value are set as lateral acceleration judgment values, and when the lateral acceleration increases, the lateral acceleration detection value is up to the second lateral acceleration judgment value. Is low
Control threshold value, and the lateral acceleration detection value is
Exceeding the threshold, from low control threshold to high control threshold
The threshold value is set to increase the threshold value at once, and when the lateral acceleration decreases, the lateral acceleration detection value becomes the first lateral acceleration judgment value.
Decreases the threshold value gradually as the lateral acceleration detection value decreases.
The lateral acceleration detection value is less than or equal to the first lateral acceleration judgment value
Means to maintain a low control threshold value when the vehicle is traveling, control hunting can be prevented during turning when acceleration slip occurs, and stability in the low lateral acceleration range and high lateral acceleration range when the lateral acceleration increases In this case, it is possible to achieve a balance between the acceleration performance and the stability when the lateral acceleration is reduced and to shift to the stable side.

[Brief description of the drawings]

FIG. 1 is a diagram corresponding to claims showing a traction control device for a vehicle according to the present invention.

FIG. 2 is an overall view of a braking / drive system control system for 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 fluid pressure control system of a braking / drive system control system to which the vehicle traction control device of the embodiment is applied.

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

FIG. 5 is a traction control system & AB of the embodiment device.
It is a flowchart which shows the flow of the traction control processing operation corresponding to a lateral acceleration performed by the S control system electronic control unit.

[Explanation of symbols]

 a acceleration slip detecting means b lateral acceleration detecting means c lateral acceleration judgment value setting means d control threshold setting means e traction control means

Claims (1)

(57) [Claims] 1. An acceleration slip detecting means for detecting an acceleration slip, a lateral acceleration detecting means for detecting a lateral acceleration, and a first lateral acceleration judgment value existing in a low lateral acceleration area and present in a high / low branch area of the lateral acceleration. A lateral acceleration determination value setting means for setting a second lateral acceleration determination value; when the lateral acceleration increases , the lateral acceleration detection value maintains a low control threshold value until the second lateral acceleration determination value; 2
If the lateral acceleration judgment value is exceeded, high control is started from the low control threshold.
Set the threshold value to increase the threshold value at once to the threshold value,
When the lateral acceleration decreases, it gradually increases according to the decrease in the lateral acceleration detection value until the lateral acceleration detection value becomes the first lateral acceleration judgment value.
Control threshold value setting means for maintaining a low control threshold value when the lateral acceleration detection value becomes equal to or less than the first lateral acceleration judgment value; And a traction control means for performing traction control to suppress an acceleration slip when a control threshold value set by the traction control threshold value is exceeded.