JPH0211447A - Device for controlling anti-lock - Google Patents

Abstract

PURPOSE:To improve the directional stability of a vehicle at the time of braking by simultaneously reducing the brake fluid pressure of rear wheels when rear wheel locking occurred, while pressurizing the right/left rear wheel brake fluid pressures to be the same value by the action of a balance valve at the time of repressurizing. CONSTITUTION:In a dual-circuit crossing type brake hydraulic system, modulators M1, M2 consisting of normally-open hold valves 3a, 3b, normally- closed decay valves 4a, 4b, reservoirs 5a, 5b, and pumps 6a, 6b for controlling each front-wheel brake fluid pressure are provided in each brake hydraulic system 1, 2, respectively. In this case, check valves 7a, 7b are provided between rear wheel brakes and a master cylinder M/C with a direction from the rear wheel brake side to the M/C side as the normal direction, in each hydraulic system 1, 2. Also, a balance valve 8 composed of a pair of balance pistons 9a, 9b which are moved under rear-wheel brake fluid pressures to open/close each check valve 7a, 7b is provided between the hydraulic systems 1, 2.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a brake fluid pressure system that brakes one front wheel and another rear wheel, and a brake fluid system that brakes the other front wheel and the other rear wheel. The present invention relates to an anti-lock control device that is suitably applied to a two-system brake hydraulic system that is equipped with pressure systems independently of each other, particularly a two-system diagonal brake hydraulic system that has front and rear wheel brake systems diagonally connected. .

[Conventional technology]

This type of anti-lock control device firstly includes a modulator for anti-lock control in each brake hydraulic system, and monitors the wheel speed of each wheel. One that performs anti-lock control on whichever of the right rear wheels has a slower rotational speed (hereinafter referred to as select low), and the second one that performs anti-lock control on whichever one has a faster rotational speed. (below,
Third, select whichever of the rear wheels has the faster rotation speed, compare the selected rear wheel rotation speed with the left front wheel or right front wheel speed, and control the slower rotation speed. Anti-lock control devices are known as targets.

[Problem to be solved by the invention]

In the first means, priority is given to preventing locking, and if the rear wheels go to lock before the front wheels, the brake fluid pressure of the front wheels also decreases, resulting in insufficient braking force for the entire vehicle.

On the other hand, with the second method, the braking force is not insufficient, but there is a high risk of wheel locking.

Roughly speaking, since the third means has both select high and select low, each of the above drawbacks can be alleviated, but for example, on a split μ road where the left road surface is a low μ road and the right road surface is a high μ road, , the right rear wheel and right front wheel or left front wheel become select low, which causes the left rear wheel to lock and deteriorate the directional stability of the vehicle.

The technical object of the present invention is to solve such conventional problems.

[Means to solve the problem]

In the present invention, a first brake that brakes one front wheel and one rear wheel is provided.
In a two-system brake hydraulic system that independently includes a brake hydraulic system 1 and a second brake hydraulic system 2 that brakes the other front wheel and the other rear wheel, each brake hydraulic system ( 1,
2) Valve mechanisms (7a, 7b) are provided between the rear wheel brakes and the master cylinder (M/C), and each of the valve mechanisms (7a, 7b) moves by itself in response to the rear wheel brake fluid pressure. A pair of balance pistons (9a, 9b) that respectively control the opening and closing of the balance pistons (9a, 9b), and a hydraulic control chamber whose volume changes with the movement of each balance piston (9a, 9b), which is located between the pair of balance pistons (9a, 9b). 10 is provided between each brake hydraulic pressure system (1, 2), and the hydraulic pressure control chamber 10 is connected to the reservoir 5.
b, and when there is a risk of wheel locking in at least one of the rear wheels, the hydraulic pressure control chamber 10 is connected to the hydraulic pressure control chamber 10 so as to escape to the reservoir 5b, thereby forming an anti-lock control device.

Here, the brake hydraulic system to which the present invention is applied is as follows:
A first brake that brakes the left front wheel (FL) and the right rear wheel (RR)) sound pressure system 1, the right front wheel (FR), and the left rear wheel (RL)
or a two-system diagonal brake hydraulic system that is independently equipped with a second brake hydraulic system 2 that brakes the left front wheel (F
A first brake hydraulic system that brakes the front right wheel (FR) and the rear left wheel (RL), and a second brake hydraulic system that brakes the front right wheel (FR) and the rear right wheel (RR) are independently operated. This is a two-system brake hydraulic system.

Furthermore, when applying the device of the present invention to carry out anti-lock control of the rear wheels, it is preferable to use the selector type, which selects the slower one of the rotational speeds of each rear wheel as the control target. A select high method may be used in which the control target is the one that is controlled. In either case, anti-lock control is applied to both rear wheels.

In addition, each brake fluid pressure system (1, 2) has a normally open hold valve (3a, 3b) and a normally closed decay valve (4a) in order to control each front wheel brake fluid pressure.
, 4b), reservoir (5a, 5b), pump (6
It is preferable to provide a modulator (Ml, M2) for front wheel brake fluid pressure control consisting of components such as a, 6b), etc., and use it in conjunction with the device of the present invention.

In this case, if the reservoir or the like used in the present invention is also used for front wheel brake fluid pressure control, the device can be made smaller, lighter, and less expensive.

In addition, the hydraulic pressure control chamber 10 may be filled and supplied to actuate the balance pistons (9a, 9b). The chamber 10 may be connected to one brake hydraulic system 2 and the brake hydraulic system 2 may be used. In particular, when the reservoir etc. is also used as the front wheel brake fluid pressure control modulator, the brake fluid is activated)
Must be used at night. And the hydraulic control room 1o
is connected to one brake hydraulic system 2, and if that brake hydraulic system 2 loses power, the brake fluid in the hydraulic control chamber 10 will also leak out, and as a result, the balance pistons (9a, 9b) Since the brake fluid pressure in the brake fluid pressure system 1 of the other system drops due to the movement of It is preferable to insert a tinic valve 17 for blocking the outflow of liquid in the pressure control chamber 10.

[Effect]

Normally, brake braking is performed by each brake hydraulic system (1,
2) is performed independently. When there is a risk of locking of either the left or right rear wheels (RL, RR) due to braking, the hydraulic fluid in the hydraulic control chamber 10 is released to the reservoir 5b, so that the pair of balance pistons (9a, 9b) They approach each other and absorb the brake fluid from the left and right rear wheels (RL, RR), reducing the rear pressure of each rear wheel brake. For this reason,
The risk of locking is avoided for each rear wheel (RL, RR). Furthermore, since the brake fluid pressures of the rear wheels (RL, RR) are simultaneously reduced, the directional stability of the vehicle can be ensured. Once the fear of rear wheel lock is resolved, open the pressure recovery control room 1.
When hydraulic fluid is supplied into 0, a pair of balance pistons (
9a, 9b) separate from each other, the brake force absorbed in the balance valve 8 is pressurized to the balance piston (9a, 9b) and transmitted to each rear wheel brake. The above operations are then repeated as necessary.

〔Example〕

Hereinafter, one embodiment of the present invention will be described based on FIGS. 1 and 2.

The vehicle equipped with this device has a left front axle (FL) and a right rear axle (
A first brake hydraulic system 1 that brakes the front right wheel (FR) and a second brake hydraulic system 2 that brakes the front right wheel (FR) and the rear left wheel (RL) are provided independently of each other.

Each brake fluid pressure system (1, 2) has a tandem-type master cylinder (
Brake fluid pressure is supplied from the M/C.

In addition, each brake fluid pressure system (1, 2) is equipped with a normally open hold valve (3a) to control the brake fluid pressure of each front wheel.
, 3 b), normally closed decay valve (4a, 4b)
, reservoir (5a, 5b), pump (6a,
6b) formed by a modulator (Ml.

M2) is provided, and a hold valve (3a.

Brake fluid pressure is increased/decreased through the brake valve (3b), and during anti-lock control, the hold valve (3a, 3b) is closed, the decay valve (4a, 4b) is opened, and the reservoir (4a, 4b) is opened.
5a, 5b) absorbs the front wheel brake fluid, and the brake fluid in the reservoir (5a, 5b) is pumped up by the pump (6a, 6b) to the master cylinder (M/5b).
C) side.

In addition, in each brake hydraulic system (1, 2), a check valve is installed between the rear wheel brake and the master cylinder (M/C), the forward direction being from the rear wheel brake side to the master cylinder (M/C) side. (7a, 7b) are provided as valve mechanisms, a balance valve 8 is provided between each brake hydraulic system (1, 2), and each check valve (7a, 7b) is provided between each brake hydraulic system (1, 2).

Provisioning valves (PCVs) are interposed between the vehicle 7b) and each rear wheel brake.

The balance valve 8 includes each of the check valves (7a
, 7b) with a rod and each rear wheel brake).
A pair of balance pistons (9a, 9
b), and a hydraulic control chamber 10 which is located between the pair of balance pistons (9a, 9b) and whose volume changes with the movement of each balance piston (9a, 9b). The pair of balance pistons (9a, 9b) each have a spring 1 stretched between each balance piston (9a, 9b).
1 and is biased in the direction of separation. Further, the hydraulic pressure control chamber 10 is connected to a reservoir 5b provided in the second brake hydraulic system 2 via a normally closed decay valve 15, and is further connected to a pump 6b of the second brake hydraulic system 2 and a master cylinder. (M/C) is connected to the hydraulic pressure control chamber 10 via a normally open hold valve 16 and a check valve 17 whose forward direction is from the hold valve 16 side to the hydraulic pressure control chamber 10 side. There is.

On the other hand, each wheel (FL, FR, RL, RR) is provided with a wheel speed sensor (S), and a microcomputer-based control device receives signals from each sensor (S) and determines whether there is a risk of wheel locking. (ECtJ) is provided. This control device (ECU'') is equipped with the Decay valves (4a, 4b, 15), the hold valves (3a, 3b, 16), and the pumps (6a, 6b).
are connected, and their operations are controlled by commands from a control unit (ECU).

This control device (ECU) includes a first evaluation circuit 21 that determines whether there is a risk of wheel lock in the front left wheel (FL) based on the rotation speed of the front left wheel (FL), and a rotation speed of the front right wheel (FR). a second evaluation circuit 22 that determines whether there is a risk of wheel lock on the front right wheel (FR);
This select low circuit 23 compares the rotation speeds of the RR) and outputs the slower rotation speed.
A third evaluation circuit 24 is provided for determining whether or not there is a risk of wheel lock in the slower rear wheel based on the rear wheel rotation speed output from the Accordingly, an operation command is issued to each of the decay valves (4a, 4b, 15), etc.

Next, an example of the operation of the apparatus of this embodiment will be explained.

First, anti-lock control for each front wheel (FL, FR) will be explained. During braking, the first or second evaluation circuit (21
, 22), and if there is a risk of wheel lock, the hold valve (
3a, 3b) are closed and the decay valves (4a, 4
b) opens, and the brake fluid from the front brakes flows into the reservoir (
5a, 5b), and the front wheel brake fluid pressure is reduced. This causes the front wheel (FL) to change.

Since the wheel lock of FR) is avoided, the pump (
6a, 6b) to activate the reservoirs (5a, 5b).
Pump up the brake fluid from b) and transfer it to the master cylinder (M/
C), close the Decay valves (4a, 4b),
Open the hold valves (3a, 3b) and repressurize the front wheel brake fluid pressure. Then, the above operation is repeated while adding an operation to maintain the brake fluid pressure as necessary. As described above, the front wheel brake fluid pressure is controlled independently on the left and right sides.

Next, for each rear wheel (RL, RR), each rear wheel (R
L.

RR), the slower one is the select low circuit 23.
When the third evaluation circuit 24 determines that there is a risk of wheel locking, the hold valve 16 closes and the decay valve 15 opens in response to a command from the control unit (ECU) to close the brake in the hydraulic control chamber 10. The fluid (working fluid) is released into the reservoir 5b, and the pair of balance pistons (9a,
9b) approaches against the spring 11, and each check valve (7a) approaches.

7b) and then close the pair of balance pistons (9
Each rear wheel (RL) is located within both ends of the balance valve 8 whose volume has been expanded by regressing the rear wheels (RL).

RR) to absorb the brake fluid and reduce its fluid pressure.

In this way, the risk of locking of the rear wheels (RL, RR) is avoided. At the same time, the pumps (6a, 6b
) is activated to pump up brake fluid from the reservoir (5a, 5b) and return it to the master cylinder (M/C) side, but after that, if necessary, the brake fluid is maintained at the sound pressure and then re-pressurized.

That is, by closing the decay valve 15, opening the hold valve 16, and operating the pump 6b, the brake pressure is supplied into the hydraulic control chamber 10, and the pair of balance pistons (9a, 9b) are moved in the direction away from each other. Moving. As a result, the brake fluid absorbed in the balance valve 8 is pressurized and supplied to each rear wheel brake. In this repressurization control, a pair of balance pistons (9a
, 9b) and the hydraulic pressure control chamber 10, the left and right brake hydraulic pressures are balanced and become the same pressure. Therefore, the directional stability of the vehicle during control can be ensured.

Next, assume that a power failure occurs in the second brake hydraulic system 2 during braking. In this case, since the check valve 17 is present, the brake fluid in the hydraulic pressure control chamber 10 does not leak out, so that the braking force from the first brake hydraulic system 1 can be ensured.

Note that even if a power failure occurs in the first brake hydraulic system 1, it will not affect the second brake hydraulic system 2.

As described above, in the device of this embodiment, the left and right front axes (FL,
Since the brake fluid pressures of the FR) are controlled independently and the rear wheel brake fluid pressures are controlled synchronously, especially on so-called split μ roads where the left and right wheels have different coefficients of friction μ on the left and right road surfaces, The braking force of the front wheels is not lowered more than necessary, and the directional stability of the vehicle can be maintained well.

In addition, there is a reservoir and a pump for front wheel brake fluid pressure control (5b) necessary for controlling the rear pressure (rear wheel brake).
, 6b), it is possible to reduce the cost and downsize the entire device. However, in view of the spirit of the present invention, the pressure recovery control chamber 10 may be operated by being connected to a hydraulic pressure system separate from the brake sound pressure system (1, 2).

In addition, as a valve mechanism, a check valve (7) whose forward direction is from the rear wheel brake side to the master cylinder (M/C) side.
a, 7b), but the present invention is not limited to such check valves as a valve mechanism.
Other types of valve mechanisms may be provided between the respective rear wheel brakes and the master cylinder. In this case, it is preferable to provide a detour fluid path connecting the rear wheel brake and the master cylinder in a way that bypasses the valve mechanism, and to provide a check valve having the above-mentioned directionality in this detour path.

〔Effect of the invention〕

According to the present invention, when there is a risk of rear wheel locking in the independent two-system brake sound pressure system, the rear wheel brake fluid pressure can be simultaneously reduced, and when repressurizing, the left and right brake fluid pressures are operated by the action of the balance valve. Since the rear wheel brake fluid pressures are pressurized at the same value, the directional stability of the vehicle during braking is improved.

If the control of the front wheel brake fluid pressure is made independent of the control of the rear wheel brake fluid pressure as in the example, unnecessary pressure reduction of the front wheel brake force can be avoided, and the braking force of the entire vehicle can be reduced. We can secure enough.

[Brief explanation of the drawing]

FIG. 1 is a hydraulic system diagram showing one embodiment of the present invention, and FIG. 2 is a block diagram of a control device using a microcomputer. (FL)...Left front wheel, (RR)...Right rear wheel, (FR)...
・Front right wheel, (RL)...Rear left wheel, 1...1st brake) sound pressure system, 2...2nd brake fluid pressure system, 5b...Reservoir, 8...Balance valve, 7a, 7b ...Valve mechanism, 9a, 9b...Pair of balance pistons, 10...
Hydraulic control room. Diagram

Claims (1)

[Claims] (1) A first brake hydraulic system that brakes one front wheel and one rear wheel, and a second brake hydraulic system that brakes the other front wheel and the other rear wheel are independently provided. In a two-system brake hydraulic system, a valve mechanism is provided between the rear wheel brake and the master cylinder of each brake hydraulic system, and each valve mechanism operates by moving itself in response to the rear wheel brake hydraulic pressure. A balance valve is provided between each brake hydraulic system, and includes a pair of balance pistons that each control opening and closing, and a hydraulic pressure control chamber that is located between the pair of balance pistons and whose volume changes with the movement of each balance piston. An anti-lock control device, characterized in that a control chamber is connected to a reservoir, and the hydraulic fluid in the hydraulic pressure control chamber is configured to escape to the reservoir when there is a risk of wheel lock in at least one of the rear wheels.