JP2574294Y2 - Brake fluid pressure control device - Google Patents

Description

[Detailed description of the invention]

[0001]

BACKGROUND OF THE INVENTION The present invention can secure a brake fluid pressure in the event of a failure of a brake fluid pressure control device, especially a fluid pressure source, as well as an antilock brake system (hereinafter referred to as ABS) and traction. The present invention relates to a brake fluid pressure control device applicable to a control system (hereinafter, referred to as TCS).

[0002]

2. Description of the Related Art Conventionally, as this type of brake fluid pressure control device, one disclosed in Japanese Patent Application Laid-Open No. 2-175361 is known. In this method, the hydraulic pressure supplied from the hydraulic pressure source is directly used for the wheel cylinder as the brake hydraulic pressure of the wheels. The hydraulic pressure supplied from the hydraulic pressure source is determined by the input generated by depressing the brake pedal. The structure is determined by the cross-sectional area of the load cell. Further, the ABS and the TCS are configured to be performed by another control actuator.

[0003]

However, in the above-mentioned conventional structure, when the hydraulic pressure source is defective, the pressure in the hydraulic pressure source hydraulic chamber in the master cylinder is reduced, and the spool is moved to the hydraulic pressure source hydraulic pressure. After moving to the chamber side, the pressure of the reaction chamber is applied to the output chamber of the hydraulic pressure control valve through the liquid passage. Therefore,
In order to secure the hydraulic pressure required for the brake, it is necessary to increase the input of the brake pedal and reduce the cross-sectional area of the load cell, and it is impossible to achieve this in terms of structure.

In order to perform ABS or TCS control, another control actuator must be provided, which complicates the structure and increases the manufacturing cost.

The present invention has been proposed in order to solve the problems of the prior art, and it is possible to secure the brake fluid pressure even when the pressure reducing source is defective, and to provide no special additional device. An object of the present invention is to provide a brake fluid pressure control device capable of performing ABS or TCS control.

[0006]

According to the present invention, there is provided a master cylinder for outputting a brake fluid pressure in response to a brake pedal, a fluid pressure source for outputting a boosted brake fluid pressure, and a brake fluid pressure corresponding to an input brake fluid pressure. A brake fluid pressure, which is connected between a wheel cylinder that generates a braking force and the master cylinder and the wheel cylinder and is increased by a predetermined rate to a brake fluid pressure output from the master cylinder, is applied to the hydraulic pressure. An electromagnetic hydraulic control valve that guides the hydraulic cylinder from a source to the wheel cylinder, and shuts off a hydraulic path between the hydraulic source and the wheel cylinder when the hydraulic source is defective;
A pressure booster connected between the master cylinder and the hole cylinder in parallel with the hydraulic pressure control valve, wherein the pressure booster is defined by a piston slidably provided therein. 1, having a second cylinder chamber, the first cylinder chamber is connected to the master cylinder, and the second cylinder chamber is connected to the wheel cylinder, the first cylinder chamber side and the The cross-sectional area of the piston on the side of the second cylinder chamber is different from that of the first cylinder chamber when the hydraulic pressure path between the hydraulic pressure source and the wheel cylinder is shut off by the electromagnetic hydraulic pressure control valve. The second cylinder chamber is set to have such a size as to increase the pressure with the same pressure increase ratio as the hydraulic pressure control valve.

[0007]

According to the present invention, a pressure intensifier is provided between a master cylinder and a wheel cylinder in parallel with an electromagnetic pressure control valve, and the area ratio of the cross section of a piston constituting the pressure intensifier during normal brake operation is determined. The structure is set so that the pressure increase rate and the pressure increase rate when the hydraulic pressure source is defective are the same, so even when the hydraulic pressure source is defective, the hydraulic pressure from the pressure booster is supplied to the wheel cylinder As a result, the necessary hydraulic pressure for the brake can be secured.

Further, the electromagnetic hydraulic pressure control valve and the hydraulic pressure
BS and TCS can be controlled.

[0009]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of a brake fluid pressure control device according to the present invention.

FIG. 1 is a schematic configuration diagram of a brake fluid pressure control device according to the present invention. The brake fluid pressure control device according to the present invention includes a master cylinder 3 that outputs braking fluid pressure of brake fluid in response to depression of a brake pedal 1, a wheel cylinder 5 that is connected to the master cylinder 3 via a fluid path, and It has. In the present embodiment, between the master cylinder 3 and the wheel cylinder 5, electromagnetic hydraulic pressure control valves 2a and 2b constituting the brake hydraulic pressure control device 2 are provided for each rear wheel to constitute a booster section. A reservoir 4 for storing brake fluid is connected to the master cylinder 3, and a hydraulic pressure source 6 for outputting boosted brake hydraulic pressure is connected to the electromagnetic hydraulic pressure control valves 2a and 2b. Further, between the master cylinder 3 and the wheel cylinder 5, a pressure booster 7 composed of a stepped piston 71 and a spring 72 is arranged in parallel with the electromagnetic hydraulic pressure control valves 2a and 2b. It is arranged for each. The pressure of the master cylinder 3 is guided to the large-diameter portion of the stepped piston 71, the pressure of the wheel cylinder 5 is guided to the small-diameter portion, and the spring 72 is provided at the small-diameter portion. The piston is biased toward the large diameter side.

The hydraulic pressure source 6 includes a hydraulic pump 61 driven by an electric motor (not shown). The input side is connected to the reservoir 4 via a liquid path, and the output side is connected to an accumulator 62. The boosted brake fluid pressure is supplied to the electromagnetic fluid pressure control valves 2a and 2b via the accumulator 62. Reference numeral 63 denotes a relief valve, which is disposed between a fluid path connecting the reservoir 4 and an annular fluid path 26b, which will be described later, and when the fluid pressure on the fluid pressure source 6 side becomes higher than a predetermined pressure, the relief valve 63 is turned on. It has the function of returning to the side. Reference numeral 8 denotes a TCS switching valve, which is disposed between the reservoir 4 and an annular fluid passage 26c, which will be described later, to supply the fluid pressure from the fluid pressure source 6 to the brake fluid pressure control device 2 during TCS control. Can be switched. Therefore, when a wheel spin occurs, the control circuit (not shown) sets T
The drive means (for example, an electromagnetic valve) of the CS switching valve 8 is energized,
The hydraulic pressure from the hydraulic pressure source 6 is applied to the electromagnetic pressure control valves 2a,
2b, and acts to move the spool 21 rightward in the figure.

In this embodiment, the electromagnetic hydraulic pressure control valves 2a and 2b are constituted by spool valves, and have a large diameter portion 21a and a small diameter portion 2a.
The spool 21 having 1b is
While being inserted in a liquid-tight and slidable manner in the direction of the arrow,
Master cylinder pressure chamber 22 communicating with master cylinder 3
And return springs 24a, 24b provided in the back pressure chamber 23 communicating with the reservoir 4, respectively, and are held at the neutral position. A small diameter portion 21c is formed between the large diameter portion 21a and the small diameter portion 21b of the spool 21, and a pressure feedback chamber (wheel cylinder chamber) 25 is formed between the large diameter portion and the small diameter portion of the housing. Has formed. Since the pressure feedback chamber 25 communicates with the wheel cylinder 5 through a liquid passage that opens to the large diameter portion of the housing,
The hydraulic pressure output from the pressure feedback chamber 25 becomes the wheel cylinder pressure. Annular liquid passages 26a and 26b are provided in the large diameter portion and the small diameter portion of the housing, respectively. The annular liquid passage 26a provided in the large diameter portion communicates with the reservoir 4 and the annular liquid passage 26a provided in the small diameter portion. Road 26b
Communicates with the hydraulic pressure source 6. Then, the sliding of the spool 21 causes the pressure feedback chamber 25 to move into the wheel cylinder 5.
Only, only the annular liquid passages 26a and 26b can be opened (communicated).

A solenoid 27 is provided on the back pressure chamber 23 side of the electromagnetic hydraulic pressure control valves 2a and 2b, and presses the spool 21 from the right side in the figure when the ABS is operated, and slides the spool 21 to the left side in the figure. Thus, the pressure feedback chamber 25 communicates with the annular liquid passage 26a. Further, a piston 28 is disposed on the pressure receiving surface of the master cylinder pressure chamber 22 of the spool 21, and the above-described TCS pressure chamber 29 is formed between the piston 28 and the large-diameter portion of the spool 21 to constitute a TCS control unit. . An annular liquid passage 26c for TCS is provided in the housing so as to be able to communicate with the TCS pressure chamber 29. The annular liquid passage 26c communicates with the hydraulic pressure source 6 via the TCS switching valve 8. Reference numeral 28a denotes a seal provided on the sliding surface of the piston 28 with the housing, so that the hydraulic pressure supplied from the master cylinder 3 to the master cylinder pressure chamber 22 does not leak to other pressure chambers. In particular, a pressure feedback type hydraulic pressure control device such as the present embodiment, in which the spool 21 has a stepped shape, generally requires high accuracy in the clearance between the spool 21 and the housing, As a result, it is not necessary to pay much attention to the dimensional accuracy in the clearance between the spool 21 and the housing, the coaxiality, and the like.

FIG. 3 shows a second embodiment of the electromagnetic hydraulic pressure control valves 2a and 2b constituting the brake hydraulic pressure control device 2 according to the present invention. The spool 21 is controlled by return springs 24a and 24b. When held at the neutral position, a space 26 a ′ having a T-shaped cross section that opens into an annular liquid passage 26 a communicating with the reservoir 4 forms the large-diameter portion 2 of the spool 21.
1a. FIG. 4 shows a third embodiment, which is different from the first embodiment in that it has a space 26a 'having a T-shaped cross section as in the second embodiment. 1) Both the annular liquid passages 26a and 26b are provided in the small diameter portion 21b of the spool 21. 2) The space formed by the step portion of the spool 21 and the step portion of the housing becomes a pressure feedback chamber 25a. A space provided between the annular liquid passages 26a and 26b in the small diameter portion 21c of the spool 21 constitutes a wheel cylinder pressure chamber 25b. 3) Both spaces 25a and 25b communicate with the wheel cylinder 5. There are three points. However, the operation is the same as that of the first embodiment. Therefore, in the following description of the first embodiment, the repeated explanation will be omitted.

The operation of the above embodiment will be described with reference to FIGS. 1 and 2.

That is, at the time of normal brake operation, when the brake pedal 1 is depressed, the master cylinder 3 is depressed.
More predetermined brake fluid pressure is generated. This hydraulic pressure is introduced into the master cylinder pressure chamber 22 of the electromagnetic hydraulic pressure control valves 2a and 2b via a liquid passage, and the spool 2 is driven by the introduced hydraulic pressure.
1 slides in the right arrow direction in the figure. Due to this sliding,
The normally closed annular liquid passage 26 b communicates with the pressure feedback chamber 25. Since the brake fluid is accumulated in the accumulator 62 of the fluid pressure source 6 by the fluid pressure pump 61, the annular fluid passage 26b and the pressure feedback chamber 2
5, the boosted brake fluid pressure stored in the accumulator 62 flows into the pressure feedback chamber 25,
The pressure in the pressure feedback chamber 25 increases.

As described above, the large diameter portion 2 is provided on the spool 21.
1a and a small-diameter portion 21b are formed, and a pressure feedback chamber 25 is provided to face a step portion of the housing. Therefore, if the area of the cross section of the large-diameter portion 21a orthogonal to the axial direction of the spool 21 is A ₁ and the area of the cross section of the small-diameter portion 21b is A ₂ , the hydraulic pressure introduced into the master cylinder pressure chamber 22 is overcome. The force for pushing the spool 21 back to the left side in the figure by the hydraulic pressure of the pressure feedback chamber 25 is the force P of the difference (A ₁ −A ₂ ) between the two areas.
(A ₁ -A ₂ ). As a result, the control pressure (wheel cylinder pressure) output from the pressure feedback chamber 25 to the wheel cylinder 5 is determined by the balance between the forces of the pressure receiving surfaces in the master cylinder pressure chamber 22 of the spool 21 and the pressure feedback chamber 25. ,
As the control pressure of the wheel cylinder 5, a pressure proportional to the master cylinder pressure is generated.

As described above, the master cylinder pressure acts on the large-diameter portion of the stepped piston 71 of the pressure intensifier 7 and the wheel cylinder pressure acts on the small-diameter portion. the pressure side P _M, the cross-sectional area of the X _1, if the pressure in the small diameter portion side P _W, an area of the cross section and X _2, during normal braking operation _{P M · X 1 = P W} · X 2 That is, the pressure increase rate during normal brake operation and the pressure increase rate when the hydraulic pressure source 6 is defective are the same (to be the same as the pressure increase rates of the electromagnetic hydraulic pressure control valves 2a and 2b). the area X ₂ of a cross section of the area X ₁ and the small-diameter portion of the cross section of the large diameter portion of the urging piston 71 is set. Therefore, during normal brake operation, the piston 71 of the pressure increasing device 7 does not operate, and operates only when the hydraulic pressure source 6 described below is defective.

That is, as shown in FIG. 2, when the hydraulic pressure of the master cylinder 3 increases in response to the depression of the brake pedal 1 when the hydraulic pressure source 6 is defective, the spools 21 of the electromagnetic hydraulic pressure control valves 2a, 2b Moves in the direction of the arrow shown in the figure, but since the fluid path connecting the electromagnetic hydraulic pressure control valves 2a and 2b and the wheel cylinder 5 is open to the large diameter side of the housing, the wheel cylinder 5 and the fluid pressure source 6 Will be shut off. Therefore, the electromagnetic hydraulic pressure control valves 2a, 2
The pressure increase by b does not occur, and the pressure increase device 7 is operated by the hydraulic pressure of the master cylinder 3, and the pressure increase device 7 supplies the brake fluid pressure of the same pressure as the normal brake to the wheel cylinder 5.

As described above, the pressure increasing device 7 increases the brake fluid pressure at the same pressure increasing rate as the normal pressure increasing rate by the electromagnetic hydraulic pressure control valves 2a and 2b when the defect of the hydraulic pressure source 6 occurs. As a result, even when a defect occurs in the hydraulic pressure source 6, it is possible to secure the same brake operability as in the normal state, while reducing the brake operation force by increasing the brake hydraulic pressure. As is apparent from FIG. 1, the pressure-intensifying device 7 has a first cylinder chamber on the upper side and a second cylinder chamber on the lower side in FIG. The first cylinder chamber is connected to the master cylinder 3, and the second cylinder chamber is connected to the wheel cylinder 5. The above is a case where the pressure is increased during normal brake operation. However, when the pressure is to be maintained, the input of the brake pedal 1 may be held, whereby the master cylinder pressure is also held, and the spool 21 stops in a balanced state. , The wheel cylinder pressure is also maintained.

On the other hand, when the wheels are about to be locked in the brake operating state, the ABS control is activated, and the solenoid 27 of the electromagnetic hydraulic pressure control valve is excited. This allows spool 2
Numeral 1 slides leftward in the drawing against the spring force of the return spring 24a, and the annular liquid passage 26a and the pressure feedback chamber 2
5 communicates. 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 a decreasing direction (decompression). If the excitation of the solenoid 27 is maintained, the operation of the ABS is maintained as it is, and if the solenoid 27 is demagnetized, the spool 21 slides to the right in the drawing and operates in the pressure increasing direction.

Also, when the vehicle starts or suddenly accelerates,
When occurrence of wheel spin is detected, TCS control is performed. That is, in this case, first, the TCS switching valve 8
Is switched by exciting the coil of the solenoid valve to cut off the connection between the reservoir 4 and the TCS annular hydraulic passage 26c of the electromagnetic hydraulic pressure control valve, and the hydraulic pressure from the accumulator 62 and the hydraulic pressure source 6 side is reduced to the annular hydraulic passage 26.
c. As a result, the spool 21 slides to the right in the drawing to communicate the pressure feedback chamber 25 and the annular fluid passage 26b to supply the fluid pressure from the fluid pressure source 6 to the wheel cylinder 5, and the brake fluid is increased by the pressure increase. The pressure is controlled.
In order to reduce the pressure of the wheel cylinder 5, the hydraulic pressure is released to the reservoir 4 through the annular hydraulic passage 26c by the excitation of the solenoid 27 of the electromagnetic hydraulic pressure control valve, as described above.

[0023]

As described above, according to the brake fluid pressure control device according to the present invention, the pressure increase device is provided in the fluid passage between the master cylinder and the wheel cylinder, so that the electric fluid pressure control valve operates normally. The pressure increase rate is set to be the same as the pressure increase rate when the fluid pressure source fails, so when the fluid pressure source defect occurs, the brake fluid pressure is increased with the same Even when a defect of the pressure source occurs, it is possible to ensure the same brake operability as in the normal state, while reducing the brake operation force by increasing the brake fluid pressure. In addition, when a hydraulic pressure source defect occurs, the electromagnetic hydraulic pressure control valve shuts off the hydraulic pressure path between the hydraulic pressure source and the wheel cylinder. Pressure can be accurately increased without being affected by the hydraulic pressure source.
The hydraulic pressure increased by the pressure intensifier does not flow back toward the hydraulic pressure source.

[Brief description of the drawings]

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

FIG. 2 is an explanatory diagram showing a state in which a pressure-intensifying device is operated when a hydraulic pressure source is defective in the brake hydraulic pressure control device of FIG. 1;

FIG. 3 is a schematic configuration diagram showing a second embodiment of the electromagnetic hydraulic pressure control valve constituting the present invention.

FIG. 4 is a schematic configuration diagram showing a third embodiment of the electromagnetic hydraulic pressure control valve constituting the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Brake pedal 2a, 2b Electromagnetic fluid pressure control valve 21 Spool 22 Master cylinder pressure chamber 24a, 24b Return spring 25 Pressure feedback chamber 26a, 26b, 26c Annular fluid path 27 Solenoid 29 TCS pressure chamber 3 Master cylinder 4 Reservoir 5 Wheel cylinder 6 Hydraulic pressure source 7 Pressure booster 71 Stepped piston 72 Spring 8 TCS switching valve

Claims (1)

(57) [Scope of request for utility model registration] 1. A master cylinder for outputting a brake fluid pressure in response to a brake pedal, a hydraulic pressure source for outputting a boosted brake fluid pressure, a wheel cylinder for generating a braking force according to the input brake fluid pressure, and A brake fluid pressure connected between the master cylinder and the wheel cylinder, the brake fluid pressure output from the master cylinder being increased by a predetermined rate, and guiding the brake fluid pressure from the fluid pressure source to the wheel cylinder; An electromagnetic hydraulic pressure control valve that shuts off a hydraulic pressure path between the hydraulic pressure source and the wheel cylinder when the hydraulic pressure source is defective; and a hydraulic pressure control valve between the master cylinder and the hole cylinder. And a pressure intensifier connected in parallel, the pressure intensifier having first and second cylinder chambers defined by slidable pistons provided therein. Te,
The first cylinder chamber is connected to the master cylinder, and the second cylinder chamber is connected to the wheel cylinder; and a cross-sectional area of the piston on the first cylinder chamber side and the second cylinder chamber side Controlling the second cylinder chamber relative to the first cylinder chamber when the hydraulic pressure path between the hydraulic pressure source and the wheel cylinder is shut off by the electromagnetic hydraulic pressure control valve. A brake fluid pressure control device characterized in that the pressure is set to be increased to have the same pressure increasing ratio as the valve.