JP3271776B2 - Vehicle slip control device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vehicle slip control device provided with anti-skid control means for controlling a vehicle slip by controlling a brake pressure such as a brake fluid pressure of the vehicle.

[0002]

2. Description of the Related Art Conventionally, for example, Japanese Patent Application Laid-Open No. 61-266
As described in the official gazette, excessive braking
In order to prevent the wheels from being locked by braking force and impairing braking performance, etc., the slip ratio of the wheels is set separately to the target slip ratio (usually the slip ratio at which the maximum coefficient of friction between the wheels and the road surface is obtained) ) Of each wheel
2. Description of the Related Art A slip control device for a vehicle that performs anti-skid control for controlling a key pressure is known.

In the above-described anti-skid control, generally, a deceleration and a slip ratio of a wheel are calculated, and when the deceleration and a slip ratio exceed a predetermined threshold value (control start threshold value). Anti-skid control is started.

Further, as a vehicle slip control device,
In addition to performing only the above-described anti-skid control, there is known a type of performing traction control together with the above-described anti-skid control as described in, for example, Japanese Utility Model Laid-Open Publication No. 61-183249. In the traction control, a target slip ratio (typically, a wheel slip ratio) is set to separately set a slip ratio of the drive wheels in order to prevent the drive wheels from slipping due to excessive driving torque due to excessive driving torque and impairing the acceleration performance. The brake pressure and the like of the drive wheels are controlled so as to obtain the maximum friction coefficient between the vehicle and the road surface.

[0005]

However, during running of the vehicle, for example, the deceleration of the wheels may temporarily increase due to some reason, although the anti-skid control is not necessary. As a result, the anti-skid control start threshold may be exceeded, whereby the anti-skid control may be erroneously started. It is desirable to avoid such a malfunction of the anti-skid control.

For example, in a slip control device that performs both anti-skid control and traction control, when traction control is performed by brake control, the wheel speed vibrates due to an increase or decrease in brake fluid pressure during traction control. As a result, the deceleration of the wheel may exceed the threshold value for starting the anti-skid control, which may cause the anti-skid control to be erroneously started. Since it is not desirable, it is desirable that it can be avoided as much as possible.

An object of the present invention is to provide a vehicle slip control device capable of avoiding malfunction of anti-skid control as much as possible.

[0008]

Means for Solving the Problems In order to achieve the above object, the present invention has the following configuration. That is, as described in claim 1 of the claims,

In a vehicle slip control device provided with anti-skid control means and traction control means for controlling wheel slip by controlling the brake pressure on the wheels, it is preferable that the traction control means is in operation. Traction control state detection means for detecting, brake pressure detection means for detecting that the brake pressure applied to the drive wheels has become a predetermined value or more, and the traction control means is being operated by the traction control state detection means, When the brake pressure detection means detects that the brake pressure applied to the drive wheels is equal to or higher than a predetermined value, the anti-skid control is unnecessary and the anti-skid control is not required. Control that changes the starting threshold value in a direction that makes it difficult to enter anti-skid control A start threshold value changing means, a configuration equipped with.

The above-mentioned state in which anti-skid control is not required means a state in which anti-skid control is essentially not required or a state in which anti-skid control is hardly required. If
When the traction control is performed and the brake pressure on the drive wheels is equal to or higher than a predetermined value, the possibility of occurrence of re-slip requiring traction control is increased, and the anti-skid control is not required.

The anti-skid control unnecessary state may be, for example, an accelerator depressed state, a power drift state, a state in which the road surface friction coefficient is high, or the like. However, in the case of the above configuration, the degree of certainty that the anti-skid control is unnecessary is extremely strong. .

[0012]

According to the first aspect of the present invention, malfunction of the anti-skid control caused by brake control as traction control can be avoided as much as possible.

In particular, the fact that the brake pressure applied to the drive wheels during traction control is equal to or higher than a predetermined value means that:
The degree of certainty that the anti-skid control is unnecessary is extremely strong. In such a case, it is extremely preferable to prevent the anti-skid control from malfunctioning by making it difficult to start the anti-skid control.

[0014]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a diagram showing an automobile provided with a slip control device according to an embodiment of the present invention. In the illustrated embodiment, traction control is performed on the driving wheels by brake hydraulic pressure control, and anti-skid control is performed on the driven wheels and the drive wheels by brake hydraulic pressure control. In the traction control, the brake fluid pressure control is performed independently on the left and right drive wheels, and in the anti-skid control, the left and right driven wheels are separately independent, and the left and right drive wheels are commonly shaken. -The hydraulic pressure control is performed.

In FIG. 1, A is an automobile provided with a slip control device according to the present embodiment. In the automobile A, left and right front wheels 1FL and 1FR are driven wheels, and left and right rear wheels 1R.
L and 1RR are drive wheels. That is, the generated torque of the engine 2 mounted on the front of the vehicle body is transmitted to the left rear wheel 1RL via the left drive shaft 6L after passing through the automatic transmission 3, the propeller shaft 4, and the differential gear 5, while the right The power is transmitted to the right rear wheel 1RR via the drive shaft 6R.

Configuration of Automatic Transmission The automatic transmission 3 includes a torque converter 11 and a multi-stage transmission gear mechanism 12. Shifting is performed by a plurality of solenoids 13 incorporated in the hydraulic circuit of the transmission gear mechanism 12.
This is performed by changing the combination of the excitation and the demagnetization of a. The torque converter 11 has a hydraulically operated lock-up clutch 11A. By switching between excitation and demagnetization of a solenoid 13b incorporated in a hydraulic circuit of the clutch, the lock-up clutch 11A is turned on.
A is fastened and unfastened.

The solenoids 13a and 13b are controlled by a control unit UAT for an automatic transmission. The control unit UAT stores shift characteristics and lock-up characteristics in advance as is known, and performs shift control and lock-up control based on these characteristics. For this control, the control unit UAT detects a throttle opening signal from a throttle opening sensor 61 for detecting the opening of a throttle valve 43 connected to an accelerator pedal 42 disposed in the intake passage 41 and a vehicle speed. A vehicle speed signal from the vehicle speed sensor 62 (a rotation speed signal of the propeller shaft 4 in the embodiment) is input.

Configuration of brake fluid pressure adjusting mechanism Each of wheels 1FR to 1RR has brakes 21FR to 21R.
R is provided. Each of these brakes 21FR-21R
R caliper (brake cylinder) 22FR to 22RR
Is supplied with brake fluid pressure via pipes 23FR to 23RR. The structure for supplying the brake hydraulic pressure to each of the brakes 21FR to 21RR is as follows. First, the depressing force of the brake pedal 25 is boosted by a booster 26 using a hydraulic booster and transmitted to a tandem type master cylinder 27. The hydraulic pressure transmitted to the master cylinder 27 is transmitted to the left front wheel brake 21FL through a brake pipe 23FL connected to the first discharge port 27a of the master cylinder 27, and the second pressure of the master cylinder 27 is Right front wheel brake 21FR through brake pipe 23FR connected to discharge port 27b.
Respectively.

Hydraulic fluid pressure from a pump 29 is supplied to the booster 26 via a pipe 28, and excess hydraulic fluid is returned to a reservoir tank 31 via a return pipe 30. A branch pipe 28a branches from the pipe 28, and an electromagnetic on-off valve 32 is connected to the branch pipe 28a.
A pipe 33 is branched from the booster 26. The pipe 33 is connected to an electromagnetic on-off valve 34 and a one-way valve 35 arranged in parallel with the on-off valve 34.

The branch pipe 28a and the pipe 33 are joined at a junction a, and brakes for the left and right rear wheels are joined to the junction a.
Key pipes 23RL, 23RR are connected. Solenoid on-off valves 36A, 37A, 38A, 39A are connected to the pipes 23RL, 23RR, 23FL, 23FR, respectively, and relief passages 36C, 37C, 38C connected downstream of the valves 36A, 37A, 38A, 39A, respectively.
For 39C, the solenoid on-off valves 36B, 37B,
38B and 39B are connected.

Each of the above-described valves 32, 34, 36A, 37
A, 38A, 39A, 36B, 37B, 38B, 39B
Is controlled by a slip control unit USL which is a traction control means and an anti-skid control means.
That is, when neither traction control nor anti-skid control is performed, the valve 32 is closed, the valve 34 is opened, and the valves 36B, 37B, 38B, 39B are closed, and the valves 36A, 37A, 38A, 39A are closed, as shown in the figure. be opened. As a result, when the brake pedal 25 is depressed, brake fluid pressure is supplied to the front wheel brakes 21FR and 21FL via the master cylinder 27. The hydraulic pressure of the booster 26 is supplied to the rear wheel brakes 21RR and 21RL via a pipe 33 as brake hydraulic pressure.

When performing traction control on the rear wheels 1RR and 1RL as drive wheels, the valve 34 is closed and the valve 32 is opened. And valves 36A, 36B, 3
By the duty control of 7A and 37B, the brake fluid pressure is maintained, and the pressure is increased and reduced. More specifically,
Assuming that the valve 32 is closed, each of the valves 36A, 3A
When the valves 6B, 37A and 37B are closed, the brake fluid pressure is maintained, the valves 36A and 37A are opened, and the valves 36B and 3B are closed.
When 7B is closed, the pressure is increased, when the valves 36A, 37A are closed, and when the valves 36B, 37B are open, the pressure is reduced.
The brake fluid pressure passing through the branch pipe 28a is prevented from acting as a reaction force on the brake pedal 25 by the action of the one-way valve 35.

When the brake pedal 25 is depressed during such traction control, the hydraulic fluid pressure of the booster 26 corresponding to the depression is changed to the brake fluid pressure via the one-way valve 35. And rear wheel brake 21RR, 21
RL is supplied. When performing anti-skid control on the rear wheels 1RL and 1RR as drive wheels, the valve 32 is closed and the valve 34 is opened. The valves 36A, 36B, 37A, 37B are operated in the same manner as the traction control described above.
With the duty control described above, the brake hydraulic pressure is maintained, and the pressure is increased and reduced. The front wheel 1F as a driven wheel
When performing anti-skid control on L, 1FR, the valve 38A,
By the duty control of 38B, 39A and 39B, the brake fluid pressure is maintained, and the pressure is increased and reduced.

Configuration of Control Unit The slip control unit USL performs traction control by brake hydraulic pressure control on the drive wheels 1RL and 1RR as described above, and drives the driven wheels 1FL and 1FR and the drive wheel 1RL.
Anti-skid control by brake hydraulic pressure control is performed on RL and 1RR. The control unit USL receives signals from wheel speed sensors 64 to 67 for detecting wheel speeds, an accelerator signal from an accelerator switch 68 for detecting ON (depressed) and OFF (return) of an accelerator pedal, and the like. A road surface μ signal from a road surface μ sensor 69 that detects a road surface friction coefficient (road surface μ) is input.

Further, the control unit USL includes an input interface for receiving each signal from each of the sensors, a microcomputer including a CPU, a ROM, and a RAM, an output interface, and valves 32, 34, and 3,
6A, 37A, 38A, 39A, 36B, 37B, 38
B, 39B, and a drive circuit for driving
The control program necessary for traction control and anti-skid control, various maps, etc. are stored in
M is provided with various memories necessary for executing the control.

Next, the anti-skid control by the control unit USL will be described. This anti-skid control is performed in common for the left and right drive wheels 1RL and 1RR, and is separately and independently performed for the left and right drive wheels 1RL and 1RR, the left driven wheel 1FL, and the right driven wheel 1FR.

That is, for the left and right driving wheels 1RL and 1RR, the acceleration / deceleration and the slip rate of the left and right driving wheels 1RL and 1RR are calculated based on the wheel speeds of the wheels 1FL, 1FR, 1RL and 1RR and the like. The left and right driving wheels 1RL, 1
The valves 36A and 36A are used to set the slip rate of the wheel having the greater lock tendency to the target slip rate based on the acceleration / deceleration and the slip rate of the wheel having the greater lock tendency among the RRs.
B and 37A, 37B are opened and closed in exactly the same manner, and the brake hydraulic pressure of the left and right driving wheels 1RL, 1RR is controlled to increase or decrease and maintain. The control for the left driven wheel 1FL calculates the acceleration / deceleration and the slip rate of the left driven wheel 1FL in the same manner as described above, and based on the calculated values, calculates the right / left driven wheel 1FL.
The valves 38A, 3
8B is opened and closed to control the increase and decrease of the brake pressure of the left driven wheel 1FL. The same operation is performed for the right driven wheel 1FR as in the case of the left driven wheel 1FL.

Next, the contents of the traction control by the control unit USL will be described. This traction control is performed separately for the left and right drive wheels 1RL, 1RR. That is, the control for the left driving wheel 1RL is performed in the same manner as the traction control in Kochi, for each wheel 1FL, 1FR, 1RL, 1R.
The acceleration / deceleration and the slip rate of the left drive wheel 1RL are calculated based on the wheel speed of R, etc., and the valves 36A and 36A are used to set the slip rate of the left drive wheel 1RL to the target slip rate based on the calculated acceleration / deceleration and the slip rate.
B is opened and closed to control the increase and decrease of the brake hydraulic pressure of the left driving wheel 1RL. Also, the right driving wheel 1RR
Similarly, the acceleration / deceleration and the slip ratio of the right driving wheel 1RR are calculated, and based on the calculated values,
The valves 37A and 3
7B is opened and closed to control the brake fluid pressure of the right driving wheel 1RR to increase and decrease.

Change of Anti-Skid Control Start Threshold In the anti-skid control, the slip ratio and deceleration of the wheel are calculated, and either the slip ratio or the deceleration is equal to or greater than a preset control start threshold. Is determined, the wheel is determined to have a tendency to lock, and anti-skid control for the wheel is started. However, the anti-skid control start threshold is changed to a direction in which control is less likely to be performed when the anti-skid control is unnecessary, that is, the control is less likely to be started.

The control start threshold value is changed by detecting a state in which anti-skid control is not required by the anti-skid control unnecessary state detecting means, and changing the threshold value based on information indicating that the anti-skid control is not required. It is done by means. As described above, the change of the control start threshold value prevents the deceleration or the like from exceeding the control start threshold value for some reason when the anti-skid control is unnecessary, thereby preventing the anti-skid control from being erroneously started. It is done for the purpose. The state in which the anti-skid control is not required means a state in which the anti-skid control is not originally required or a state in which the anti-skid control is hardly required. For example, such a state as traction Control state,
Examples include a state in which the accelerator is operating or a state in which the road surface friction coefficient is high.

During the traction control, the wheel is slipping due to excessive driving torque, and since the accelerator is originally depressed and the brake is not depressed, the anti-skid control is not required. If the control enters the anti-skid control during traction control, at least the valve 32 is closed and the brake pressure is not increased, and the drive wheels may slip again. However, re-slip of the drive wheels can be considered when anti-skid control is started in a state where the brake pressure applied to the drive wheels is large, so at least even if the traction control is being performed, at least the brakes on the drive wheels will occur. If the key pressure is less than the predetermined value, the anti-skid control may be started at a normal start threshold value (the threshold value that is more likely to start).

In addition, even during the operation of the accelerator, the brake is not normally depressed, so that no anti-skid control is required. Also, when the road surface μ is high, the road surface μ
When the value is high, there is little possibility that a large slip of the wheel will occur, and therefore the probability that anti-skid control is required is sufficiently small, so it can be said that anti-skid control is not required.

Changing the control start threshold value in a direction that makes it difficult to enter the control means that the anti-skid control is not started unless the degree of wheel slip, that is, the degree of lock is further increased. When the control start threshold value is set for the slip rate and the deceleration, it means that the slip rate control start threshold value and the deceleration control start threshold value are changed to be larger.

Hereinafter, an example in which the anti-skid control unnecessary state is detected during the traction control, the accelerator operation and the high μ road as the anti-skid control unnecessary state, and the control start threshold value is changed in those cases will be described with reference to FIG. This will be specifically described. In the following description, P indicates a step.

First, at P1, it is determined whether or not the vehicle is stopped. In this determination, it is determined that the vehicle is stopped when the estimated vehicle speed is less than 5 km / h and each wheel speed is less than 2.5 km / h. If the determination in P1 is YES, the control is returned as it is.

If the determination in P1 is NO, it is determined in P2 whether traction control is currently underway. If the determination in P2 is YES, in P3, it is determined whether or not the brake pressure on the wheels, in particular, at least the brake pressure on the drive wheels is greater than or equal to a predetermined value. This blur
The brake pressure can be known by providing a brake pressure detecting sensor for each wheel brake, but a known theoretically estimated brake pressure can also be used. .

If the determination in P3 is YES, the anti-skid control is hardly started. For this reason, the slip ratio as a threshold for starting anti-skid control is 50%, and the wheel deceleration is 4 g.
(G is a gravitational acceleration). When the slip ratio is 50% or more (when the determination of P4 is YES) or when the wheel deceleration is 4 g or more (the determination of P5 is YES), the determination of P4 and P5 is made.
), The anti-skid control is started in P10. If the determinations of P4 and P5 are both NO, the control is returned as it is.

If NO in the determination of P2 or P3,
In P6, if the accelerator pedal is currently depressed, it is determined whether or not the state is substantially the same. If the determination in P6 is YES, the P4
And the anti-skid control is hardly performed.

When the determination in P6 is NO, in P7, it is determined whether or not the road surface is high μ, that is, whether or not the friction coefficient of the road surface is large. This determination of P7 is to determine whether or not the vehicle is in a high state when the road surface μ is set to, for example, three levels of high, medium, and low. In this determination of P7, YE
Also in the case of S, the process shifts to the aforementioned P4 in order to make the anti-skid control difficult to perform. Incidentally, the road surface μ detecting sensor 69 may be configured to irradiate a laser toward the road surface, receive its reflection, and determine the road surface μ based on the received reflection amount, for example. Alternatively, the road surface μ can be determined by a conventionally known appropriate method such as estimating the road surface μ based on the acceleration / deceleration of the wheels.

When the determination in P7 is YES, it is determined whether or not the anti-skid control should be started based on the normal control start threshold value. That is, the slip ratio as the control start threshold is set to a small value such as 30%, and the wheel deceleration is set to a small value such as 1.5 g. And
When the slip ratio is determined to be 30% or more in P8, or when the wheel deceleration is determined to be 1.5 g or more in the determination in P9, the process shifts to P10 and the anti-skid control is performed. Be started. P8 and P
If the determination in No. 9 is NO, the return is performed as it is.

Although the embodiment has been described above, it is also possible to change only one of the slip ratio and the deceleration as the control start threshold value of the anti-skid control. Also, the slip ratio, that is, the slip value can be set as appropriate, such as noting as a ratio but as a difference (for example, estimated vehicle speed-wheel speed). In the above embodiment, both the thresholds of the slip ratio and the deceleration are changed, but only one of the thresholds may be changed.

[0042]

[0043]

[Brief description of the drawings]

FIG. 1 is a diagram showing an automobile provided with one embodiment of the present invention.

FIG. 2 is a flowchart illustrating an example of changing a control start threshold value.

[Explanation of symbols]

1FL, 1FR, 1RL, 1RR: Wheel USL: Anti-skid control means USL: Traction control means USL: Control start threshold value changing means USL, 68, 69: Anti-skid control unnecessary state detecting means

──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Yoji Kurihara 3-1 Shinchi, Fuchu-cho, Aki-gun, Hiroshima Prefecture Inside Mazda Corporation (72) Inventor Toshiaki Tsuyama 3-1 Shinchi, Fuchu-cho, Aki-gun, Hiroshima Mazda Co., Ltd. (72) Inventor Toru Onaka 3-1, Shinchi, Fuchu-cho, Aki-gun, Hiroshima Prefecture Mazda Co., Ltd. (56) References JP-A-62-137557 (JP, A) JP-A-63-175464 ( JP, A) JP-A-3-246154 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) B60T 8/66 B60T 8/58

Claims (1)

(57) [Claims] An anti-skid control means for controlling wheel slip by controlling the brake pressure of the wheel .
In the slip control device for a vehicle with a Rakushon control unit, to detect that it is in operation of the traction control unit
Traction control state detection means, and that the brake pressure applied to the drive wheels has exceeded a predetermined value.
The traction control state detecting means detects the traction
The brake control detecting means is operating and the brake pressure detecting means is operating.
The brake pressure applied to the drive wheels by the gear is above a specified value
Anti-skid system when it is detected that
No anti-skid control required
As a slip control system for a vehicle which characterized in that it comprises a control start threshold value changing means for changing the anti-skid control start threshold difficult direction enters the anti-skid control, the.