JPH05305865A - Brake fluid pressure controller - Google Patents

Abstract

PURPOSE:To make it appliable to an antiskid braking system without requiring any special additional device and simplify a structure as well as to receive no effect of rigidity of a wheel cylinder and a fluid passage or the like and reduce an operating value of a brake pedal too. CONSTITUTION:This controller is provided with a master cylinder 3 outputting brake fluid pressure in response to a brake pedal 1, a fluid pressure source 6 outputting the boosted brake fluid pressure, a wheel cylinder 5 where the outputted brake fluid pressure is inputted, a spool 10 being installed in space between the master cylinder 3 and the wheel cylinder 5 and slidable in a housing, and a solenoid hydraulic control valve 2 with a solenoid 18. At the time of normal braking, the boosted brake fluid pressure of the fluid pressure source 6 is utilized, and the fluid pressure proportioned to the master cylinder fluid pressure is inputted into the wheel cylinder 5, and at the time of an antiskid braking system operating, the solenoid 18 is driven and a working fluid is controlled so as to make it escape to a reservoir 4.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention can be applied to an anti-lock brake system (hereinafter referred to as ABS) without the need for a brake fluid pressure control device, in particular, an additional device, and the structure can be simplified and the brake can be applied. The present invention relates to a brake fluid pressure control device that can reduce the amount of pedal depression.

[0002]

2. Description of the Related Art Conventionally, as a brake fluid pressure control device of this type, the one disclosed in Japanese Patent Laid-Open No. 1-119460 has been known. This directly uses the hydraulic pressure supplied from the hydraulic booster as the brake hydraulic pressure for the rear wheels, and the hydraulic pressure supplied from this hydraulic booster is generated by a lever that is rotated by depressing the brake pedal. The structure is controlled by a driven spool valve.

[0003]

However, since the hydraulic pressure controlled by the spool valve which constitutes the hydraulic booster is controlled by the position of the spool, a hydraulic pressure proportional to the depression amount of the brake pedal is generated. Not only is it difficult to operate, but also the structure is complicated in order to drive the master cylinder and the hydraulic booster by the brake pedal.

Further, the amount of depression of the brake pedal is easily affected by the rigidity of the wheel cylinders, the liquid passages, etc., and in order to realize accurate hydraulic pressure control, it is necessary to consider these rigidity as well. There are also problems.

Further, the wheel cylinder pressure characteristic (power boost ratio) due to the amount of depression of the brake pedal is not only constant in rising amount and inclination, but an ON-OFF control solenoid valve is used for ABS control. Therefore, there is a problem that the fluctuation of the hydraulic pressure is large and the surge pressure is generated to generate sound and vibration.

The present invention has been proposed in order to solve the above problems of the prior art, and can be applied to an ABS without the need for a special additional device, the structure can be simplified, and the brake An object of the present invention is to provide a brake fluid pressure control device with a reduced depression amount.

[0007]

To achieve the above object, the present invention provides a master cylinder that outputs a brake fluid pressure in response to a brake pedal, a hydraulic pressure source that outputs a boosted brake fluid pressure, and an output. A wheel cylinder to which the brake fluid pressure is input, an electromagnetic hydraulic pressure control valve that is provided between the master cylinder and the wheel cylinder, and has a spool and a solenoid slidable in the housing;
When a normal brake is operated, the brake hydraulic pressure boosted by the hydraulic pressure source is used, and a hydraulic pressure proportional to the brake hydraulic pressure output from the master cylinder is applied to the wheel cylinder by the electromagnetic hydraulic control valve. When the anti-lock brake system is operated, the solenoid of the electromagnetic hydraulic pressure control valve is driven to control the hydraulic pressure of the wheel cylinder to escape to the reservoir that supplies the hydraulic fluid to the master cylinder. Characterize.

[0008]

In the present invention, the electromagnetic hydraulic pressure control valve is provided between the master cylinder and the wheel cylinder, and the electromagnetic hydraulic pressure control valve has a spool and a solenoid that can slide in the housing. It is possible to smoothly increase the pressure to the target pressure instead of the stepwise hydraulic pressure fluctuation using the ON-OFF control valve without requiring an additional device for control.

Further, not only the structure is simplified, but also the stroke of the spool of the electromagnetic hydraulic pressure control valve can be shortened. As a result, the depression amount of the brake pedal interlocking with the master cylinder can be shortened and the brake pedal The wheel cylinder pressure characteristic (power boost ratio) due to the amount of depression can be made variable.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A brake fluid pressure control device according to the present invention will be described below with reference to the embodiments shown in the drawings.

FIG. 1 is a schematic configuration diagram showing a first embodiment of a brake fluid pressure control device according to the present invention. The present invention, however, responds to the depression of the brake pedal 1 so that the brake fluid of the brake fluid can be obtained. A master cylinder 3 that outputs pressure and a wheel cylinder 5 to which the output brake fluid pressure is input are provided. An electromagnetic hydraulic pressure control valve 2 is provided between the master cylinder 3 and the wheel cylinder 5 to form a booster portion, and a master hydraulic fluid pressure control valve 2 is provided in the master cylinder 3 with a reservoir 4 storing brake fluid. A hydraulic pressure source 6 for outputting a boosted brake hydraulic pressure is connected to each.

The hydraulic pressure source 6 is provided with a hydraulic pump 7 driven by an electric motor (not shown), the input side of which is connected to the reservoir 4 via a liquid path, and the output side of which is connected to an accumulator 8. The boosted brake fluid pressure is supplied to the electromagnetic fluid pressure control valve 2 via the accumulator 8. Reference numeral 19 is a relief valve, which is arranged between the fluid passages connecting the reservoir 4 and an annular fluid passage 14 to be described later. When the fluid pressure on the hydraulic pressure source 6 side becomes higher than a predetermined pressure, the relief valve 19 is provided. It has a function to return to the 4 side.

Further, the electromagnetic hydraulic control valve 2 is a spool valve in this embodiment, and has a large diameter portion 10a and a small diameter portion 10.
The spool 10 having b is fitted in the housing in a liquid-tight manner and slidably in the direction of the arrow, and a master cylinder pressure chamber 11 communicating with the master cylinder 3 is provided.
The back pressure chamber 12 that communicates with the reservoir 4 is held in the neutral position by the return springs 9a and 9b, respectively. A small diameter portion 10c is formed at a step portion between the large diameter portion 10a and the small diameter portion 10b of the spool 10, and a pressure feedback chamber 15 is formed between the large diameter portion and the small diameter portion of the housing. .. Since the pressure feedback chamber 15 communicates with the wheel cylinder 5 via the liquid passage, the hydraulic pressure output from the pressure feedback chamber 15 becomes the wheel cylinder pressure. Further, annular liquid passages 13 and 14 are provided in the large diameter portion and the small diameter portion of the housing, respectively. The annular liquid passage 13 provided in the large diameter portion communicates with the reservoir 4 and the annular liquid passages provided in the small diameter portion are provided. The line 14 is the hydraulic pressure source 6
Communicate with. The pressure feedback chamber 15 has a structure capable of opening (communicating with) both of the annular liquid passages 13 and 14 by sliding of the spool 10.

Further, a solenoid 18 is provided on the back pressure chamber 12 side of the electromagnetic hydraulic pressure control valve 2, and presses the spool 10 from the right side during ABS operation to slide the spool 10 to the left side so that the pressure feedback chamber 15 is formed. The annular liquid passage 13 is made to communicate. A piston 16 is arranged on the pressure receiving surface of the master cylinder pressure chamber 11 of the spool 10, and a seal 17 is attached to the sliding surface of the piston 16. This is a structure for preventing the hydraulic pressure supplied to the master cylinder pressure chamber 11 from leaking to the other pressure chambers, so that the dimensional accuracy in the clearance between the spool 10 and the housing, the coaxiality, etc. is not considered so much. It will be saved. This is because a pressure feedback type hydraulic pressure control device as in the present embodiment, in which the spool 10 has a stepped shape, requires high precision in the clearance between the spool 10 and the housing.

An accumulator 20 is provided in a fluid passage connecting the master cylinder 3 and the master cylinder pressure chamber 11 so that the stroke of the spool 10 can be adjusted by sucking and discharging the working fluid pressure.

FIG. 2 shows a second embodiment of the brake fluid pressure control apparatus according to the present invention, in which spool valves constituting the electromagnetic fluid pressure control valve 2 are provided for each of the left and right rear wheels. Is. In this embodiment, the same members are designated by the same reference numerals, and duplicate description will be omitted.

The operation procedure of the above embodiment will be described with reference to FIG. 3A. When the brake is normally operated, the master cylinder 3 produces a predetermined brake fluid pressure by depressing the brake pedal 1. This hydraulic pressure is
It is introduced into the master cylinder pressure chamber 11 of the electromagnetic hydraulic pressure control valve 2, and the introduced hydraulic pressure causes the spool 10 to slide to the right in the figure. Due to this sliding, the normally closed annular liquid passage 14 communicates with the pressure feedback chamber 15.
Since the brake fluid is accumulated in the accumulator 8 of the fluid pressure source 6 by the fluid pressure pump 7, the boost brake fluid pressure accumulated in the accumulator 8 by the communication between the annular fluid passage 14 and the pressure feedback chamber 15 is the pressure feedback chamber. 1
5, the pressure in the pressure feedback chamber 15 rises.

On the other hand, as described above, the spool 10 is formed with the large diameter portion 10a and the small diameter portion 10b, and the pressure feedback chamber 15 is provided so as to face the housing step portion. Therefore, the area of the cross section of the large diameter portion 10a orthogonal to the axial direction of the spool 10 is now A
₁ and A ₂ of the small diameter portion 10b, the force that overcomes the hydraulic pressure introduced into the master cylinder pressure chamber 11 and pushes the spool 10 back to the left side in the figure by the hydraulic pressure of the pressure feedback chamber 15 , The force P (A ₁ −A ₂ ) due to the difference (A ₁ −A ₂ ) between the two areas. As a result, the pressure feedback chamber 15 to the wheel cylinder 5
The control pressure (wheel cylinder pressure) output to the wheel cylinder 5 is determined by the balance of the forces of the pressure receiving surfaces of the master cylinder pressure chamber 11 and the pressure feedback chamber 15 of the spool 10, and the control pressure of the wheel cylinder 5 is input. A pressure proportional to the master cylinder pressure will be generated. When the solenoid 18 is energized to generate a certain suction force, the master cylinder pressure (brake pedal 1
Force) -the rising position of the wheel cylinder pressure characteristic changes (see FIG. 4).

The above is the case of increasing the pressure, but in the case of maintaining the pressure, the input of the brake pedal 1 may be held, whereby the master cylinder pressure is also held, the spool 10 is stopped in a balanced state, and the wheel cylinder pressure is held. Is also retained.

On the other hand, when the wheels are about to lock in the brake operating state, the ABS control is activated and the solenoid 18 of the electromagnetic hydraulic pressure control valve 2 is excited. As a result, the spool 10 slides to the left in the figure against the spring force of the return spring 9a, and the annular liquid passage 13 and the pressure feedback chamber 1
It communicates with 5. As a result, the wheel cylinder pressure is released to the reservoir 4, and the brake fluid pressure in the wheel cylinder 5 acts in the direction of decreasing (reducing pressure).

When the excitation of the solenoid 18 is maintained, the ABS operation is maintained as it is, and when the solenoid 18 is demagnetized, the spool 10 moves to the right and operates in the pressure increasing direction.

FIG. 3B shows a modified example of the spool valve constituting the electromagnetic hydraulic pressure control valve 2, and FIG.
1) The annular liquid passages 13 and 14 are both provided on the small diameter portion side of the spool valve. 2) The space formed by the stepped portion of the spool 10 and the stepped portion of the valve body is The pressure feedback chamber 15a becomes the wheel cylinder pressure chamber 15b, and the space provided between the annular liquid passages 13 and 14 in the small diameter portion 10b of the spool 10 constitutes the wheel cylinder pressure chamber 15b. 3) Both the spaces 15a and 15b are wheels. There are three points: communication with the cylinder 5. However,
Since the operation is the same as that in FIG. 3A, duplicate description will be omitted.

[0023]

As described above, according to the brake fluid pressure control device of the present invention, the electromagnetic fluid pressure control valve 2 is provided between the master cylinder 3 and the wheel cylinder 5, and the spool 1 is provided.
Since the brake fluid pressure can be controlled by driving 0, not only the structure can be simplified, but also the rigidity of the wheel cylinder 5, the fluid passage, etc. is not affected, and the depression amount of the brake pedal 1 is shortened. You can

Further, the wheel cylinder pressure characteristic (power boost ratio) caused by the amount of depression of the brake pedal 1 can be made variable, and the brake fluid pressure control corresponding to external factors such as the road surface and vehicle conditions can be performed. It will be possible.

Furthermore, an additional device for ABS control is unnecessary, the number of parts can be reduced, which contributes to downsizing of the device, and a solenoid valve is used to control the ABS. It is possible to smoothly increase the pressure up to the target hydraulic pressure.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram showing a first embodiment of a brake fluid pressure control device according to the present invention.

FIG. 2 is a schematic configuration diagram showing a second embodiment of the brake fluid pressure control device according to the present invention.

3A and 3B are explanatory views of the operation procedure of the brake fluid pressure control device according to the present invention, FIG. 3A showing the first embodiment, and FIG. 3B showing a modification of the spool valve.

FIG. 4 is a graph showing control characteristics of a master cylinder pressure and a wheel cylinder pressure in the brake fluid pressure control device according to the present invention.

[Explanation of symbols]

 1 Brake Pedal 2 Electromagnetic Hydraulic Control Valve 3 Master Cylinder 4 Reservoir 5 Wheel Cylinder 6 Hydraulic Pressure Source 18 Solenoid

Claims (1)

[Claims] 1. A master cylinder that outputs a brake fluid pressure in response to a brake pedal, a hydraulic pressure source that outputs a boosted brake fluid pressure, a wheel cylinder into which the output brake fluid pressure is input, and the master. A solenoid hydraulic pressure control valve provided between the cylinder and the wheel cylinder, the spool being slidable in the housing and having a solenoid, and the brake fluid pressure boosted by the hydraulic pressure source during normal brake operation. , The hydraulic pressure proportional to the brake hydraulic pressure output from the master cylinder is input to the wheel cylinder by the electromagnetic hydraulic control valve, and when the antilock brake system is activated, the electromagnetic hydraulic control valve Controls so that the hydraulic pressure of the wheel cylinder is released to a reservoir that supplies hydraulic fluid to the master cylinder by driving a solenoid. The brake fluid pressure control device is characterized by: