JP2614627B2 - Anti-lock control method - Google Patents

Description

The present invention relates to an antilock control method for a four-wheeled vehicle.

[Conventional technology]

Conventionally, a three-channel type antilock control method or a four-wheel independent antilock control method has been known as an antilock control method for a four-wheeled vehicle.

The three-channel type antilock control type is one in which the left and right front wheels are independently subjected to antilock control, and the left and right rear wheels are subjected to antilock control in synchronization with each other.

In the four-wheel independent antilock control method, all four wheels are independently subjected to antilock control.

[Problems to be solved by the invention]

However, the road surface conditions on which the vehicle passes usually change constantly, and at times there are road surfaces with a low friction coefficient μ, or road surfaces with a high friction coefficient μ,
Further, the friction coefficient μ may be different between the left and right. In accordance with such a change in the road surface condition, the vehicle deceleration at the time of braking, the occurrence condition of the wheel lock, and the like also change in various ways. Therefore, brake control according to these changes is necessary.

Under these circumstances, when the conventional antilock control device is examined, the following problems are highlighted.

That is, when the vehicle body deceleration is low when the brake is applied, for example, when the vehicle passes on a road surface with a low friction coefficient μ, on such a road surface, since the cornering force of the tire is small, the braking force of the left and right rear wheels is reduced. If a slight difference occurs, a yawing moment easily occurs in the vehicle body.

Therefore, on such a road surface, and particularly on a road surface having a different friction coefficient μ between the left and right wheels, if there is a risk of wheel lock on one of the left and right rear wheels, the three channels for reducing the left and right rear wheel brake fluid pressure are reduced. The anti-lock control system of the type is suitable for preventing the occurrence of the yawing moment and ensuring the running stability, and the anti-lock control system of the four-wheel independent type is not suitable.

On the other hand, when the vehicle body deceleration is high, for example, when the vehicle passes on a road surface having a large friction coefficient μ, the yaw moment is small even if any of the wheels is used for the anti-lock control, but the three-channel type anti-lock control is performed. In the lock control method, the brake pressure of the rear wheels that are not likely to be locked is also reduced by following the reduction of the brake fluid pressure of the rear wheels to avoid locking, so that the braking force of the rear wheels is unnecessarily reduced. This would increase the braking distance. Therefore, on such a road surface, the four-wheel independent antilock control method is suitable, and the three-channel antilock control method is not suitable.

An object of the present invention is to solve such a conventional problem, and to provide an anti-lock control method capable of appropriately securing running stability and shortening a braking distance according to road surface conditions. It is an issue.

[Means for solving the problem]

The present invention employs the following technical means in order to solve the above technical problems.

That is, the present invention independently controls the brake fluid pressure of each of the front and rear wheels when the deceleration of the vehicle during braking is equal to or greater than a set value, and controls the left and right rear wheel speeds when the deceleration of the vehicle is equal to or less than the set value. Of these, the lower speed is selected as the speed to be controlled, so that the brake fluid pressures of the left and right rear wheels are controlled in synchronization with each other, thereby providing an antilock control method.

[Action]

According to the present invention, when the vehicle body deceleration is high (road surface with a high friction coefficient μ), it functions as a four-wheel independent antilock control system, all wheels are independently antilock controlled, and the vehicle body deceleration is low (friction When the coefficient μ is low, the vehicle functions as a three-channel anti-lock control system, and the left and right rear wheels are anti-lock controlled in synchronization with each other.

〔Example〕

Hereinafter, an embodiment of the present invention will be described with reference to FIG.

This device is an anti-lock control means for the front left wheel (FL
A), a right front wheel anti-lock control means (FRA), a left rear wheel anti-lock control means (RLA), and a right rear wheel anti-lock control means (RRA). The left and right front wheel anti-lock control means (FLA, LRA) operate independently, and the left and right rear wheel anti-lock control means (RLA, RR)
A) is independent in principle, but the first control means (C1)
The modulators (5c, 5d) of the left and right rear wheels can operate in synchronization with each other, and the first control means (C1) is controlled by the second control means (C2) according to the vehicle deceleration. Whether or not to mediate between the anti-lock control means for the left and right rear wheels (RLA, RRA) is selected.

Front, back, left and right antilock control means (FLA, FRA, RLA, RR
A) is a wheel speed sensor (1a, 1b, 1c, 1d) that outputs the rotation of a wheel as a pulse signal, and the wheel speed sensor (1a, 1
b, 1c, 1d) to convert the pulse signal from the signal (2a, 2b, 2c, 2d) to the wheel rotation speed.
b), a logic circuit (3a, 3b, 3c, 3d) for determining whether there is a possibility of wheel lock based on the rotation speed information from the logic circuit (3a, 3b, 3c, 3d) Command the amplifier (4a, 4b, 4
c, 4d), and has modulators (5a, 5b, 5c, 5d) for increasing and decreasing the brake fluid pressure of the wheels according to the command. Although the specific structure of the modulator (5a, 5b, 5c, 5d) is not shown here, for example, a gate valve, a pressure valve,
It has a pressure reducing valve, a reservoir, a pump, etc., closes the gate valve by a command from the logic circuit 3 that has detected the possibility of wheel lock, shuts off the brake fluid path between the master cylinder and the brake device, and opens the pressure reducing valve. As a result, the brake fluid is absorbed from the brake device into the reservoir to reduce the fluid pressure, and if necessary, the pressure reducing valve is closed to maintain the fluid pressure. It is returned to re-pressurize the brake fluid pressure.

Various known logic circuits and modulators can be used.

As shown in FIG. 1, the first control means (C1) is provided downstream of the converters (2c, 2d) for the left and right rear wheels, and rotates the left and right rear wheels by the operation of a second control means (C2) described later. Select the lower one of the speeds and send that speed to the logic circuits (3c, 3d) of the left and right rear wheels as a common control target speed so that each logic circuit (3c, 3d) issues a decompression command. Make up.

Although not shown, the second control means (C2) has a vehicle speed sensor, and calculates the vehicle body deceleration based on the vehicle speed signal from the vehicle speed sensor. If the vehicle speed at a certain point after braking is β ₁ and the vehicle speed after ΔT time is β ₂ , G =
The change amount of the vehicle speed represented by (β ₂ −β ₁ ) / ΔT, which is compared with a predetermined set value.

If the vehicle body deceleration G is lower than a predetermined set value, it means that braking is poor, that is, the road surface has a low friction coefficient μ. In this case, the second control device (C2) In order to operate the first control means (C1), the first control means (C1) is connected to the left and right rear wheel converters (2c, 2d) and the logic circuits (3c, 3d) by switches (SW). I have.

If the vehicle body deceleration G is higher than the set value, it means that the braking is good, that is, the road surface has a high friction coefficient μ, and in this case, the second control device (C2)
In order not to operate the control means (C1), the first control means (C1) is separated from the left and right rear wheel anti-lock control means (RLA, RRA) by a switch (SW), and each converter (2c, 2d) Each is configured to be directly connected to the associated logic circuit (3c, 3d) (the state shown).

When the first control means (C1) is not operated, the left rear wheel anti-lock control means (RLA) and the right rear wheel anti-lock control means (RRA) operate independently of each other, and the four-wheel independent anti-lock control is performed. Becomes

Although not shown, the second control means (C2) can control the switch (SW) by operating the switch means by moving the inertial body when the deceleration of the vehicle reaches a set value. .

 Next, the operation of this embodiment will be described.

When the vehicle deceleration during braking is lower than the set value (on a road surface having a low friction coefficient μ), the second control means (C
By selecting the first control means (C1) to operate according to 2), a three-channel antilock control device is obtained. In this state, for example, an operation in a case where the left front wheel and the left rear wheel head toward the preceding lock because the friction coefficient μ on the left side of the road surface is low and the friction coefficient μ on the right side is high is described.

First, for the front wheels, the left and right front wheel anti-lock control means (FLA, FRA) operate independently, so that the left front wheel anti-lock control means (FL
In A), only the front left wheel brake fluid pressure is reduced, and the right front wheel anti-lock control means (FRA) does not follow it. As for the rear wheels, the left rear wheel goes to the lock before the right rear wheel. In this case, the lower left rear wheel speed is selected as the control target speed by the first control means (C1). You. The control target speed is the logic circuit for the left and right rear wheels (3
c, 3d), the modulators (5c, 5d) of the left and right rear wheel anti-lock control means (RLA, RRA) operate in synchronization with each other, so that the brake fluid pressures of the left and right rear wheels are synchronized with each other. And the pressure is reduced. As a result, the locking of the left rear wheel is avoided, the braking force of the right rear wheel is reduced to be equal to that of the left rear wheel, and the generation of a clockwise yaw moment when the four wheels are independently controlled is suppressed, and the running stability is reduced. Is secured.

Next, when the vehicle deceleration during braking is higher than a set value (when the friction coefficient μ is high on a road surface), the first control means (C1) is not operated by the second control means (C2) and Of the anti-lock control means (FLA, FRA, RLA, RRA) are selected to operate independently, so that a four-wheel independent anti-lock control device is obtained.

In this state, each antilock control means (FLA, FRA, RL
A, RRA) operate independently, so when the left rear wheel goes to lock, only the brake fluid pressure of the left rear wheel is reduced, the brake fluid pressure of the right rear wheel is not reduced, and the braking force is secured Is done. Therefore, the braking distance becomes shorter.

〔The invention's effect〕

According to the present invention, it is possible to switch between the three-channel antilock control system and the four-wheel independent antilock control system in accordance with the vehicle deceleration, so that the braking distance can be made as short as possible in accordance with the road surface conditions. Good running stability at the time can be maintained.

[Brief description of the drawings]

 FIG. 1 is a block diagram showing one embodiment of the present invention. FLA: front left wheel anti-lock control means; FRA: right front wheel anti-lock control means; RLA: left rear wheel anti-lock control means; RRA: right rear wheel anti-lock control means; C1: first control means C2: second control means.

Claims (1)

(57) [Claims] When the deceleration of the vehicle at the time of braking is higher than a set value, the brake fluid pressure of each of the front and rear wheels is controlled independently. When the deceleration of the vehicle is lower than the set value, the left and right rear wheel speeds are controlled. An anti-lock control method, wherein the brake fluid pressures of the left and right rear wheels are controlled in synchronization with each other by selecting a lower speed as a control target speed.