JPH068097B2 - Relief valve device used for wheel antilock system - Google Patents

Description

Description: FIELD OF THE INVENTION The present invention relates to a wheel anti-lock system, and more particularly, to a sudden drop in wheel speed, that is, a wheel lock, which may occur during vehicle braking, by canceling the brake hydraulic pressure. The present invention relates to a relief valve device used in an antilock system.

[Background of the Invention]

Recently, various types of wheel anti-lock technologies have been proposed to improve safety when braking a vehicle. Typical examples of such technologies include a master cylinder (hydraulic pressure generator) and In the brake hydraulic pressure transmission path (hereinafter referred to as the main path) that connects between the brake devices, a normally open hold valve that is normally open and closed when the brake hydraulic pressure needs to be lowered is arranged. Is provided with a bypass-connected path (hereinafter referred to as a bypass path), and a pressure reducing valve that is normally closed separates this bypass path and the main path from the brake system-side output system. The brake pressure oil flowing into the bypass passage through the normally closed type pressure reducing valve that is sometimes opened is pumped up to, for example, a pressure accumulator, and the pressure oil in the pressure accumulator is returned to the main passage. The open / close switching operation of the pressure valve (normally open type) and pressure reducing valve (normally closed type) depends on the change state of the wheel speed during vehicle braking, depending on the antilock signal (pressure reduction, pressurization of brake hydraulic pressure, and necessary). Signal to hold according to)
Has been proposed which is performed by an electronic control circuit that outputs

By the way, in the pressure accumulator used in such an anti-lock system, it is desired that the residual pressure oil be as small as possible during non-operation, and if abnormal high pressure is pumped up, It is desired to release high pressure to the master cylinder side to prevent damage to the pressure accumulator, and from this viewpoint, a relief valve is often provided in the path connecting the accumulator to the master cylinder. However, conventionally, this type of relief valve is generally a method of determining the spring force of the valve body pressing spring of the check valve in correspondence with a predetermined relief valve, and therefore its design, especially the spring force of the valve body pressing spring is determined. There was a problem that it was difficult.

The reason is that the hydraulic port that acts on the relief valve is 1: 1 on the master cylinder side and the accumulator side, so the relief valve is only the differential pressure due to the spring force, and the residual pressure oil in the accumulator is In order to make it small, it is necessary to set the spring force to a small value. However, in this way, when the antilock system operates in a relatively low brake hydraulic pressure state, pressure oil recirculation from the pressure accumulator through the relief valve will occur. This will happen.

[Object of the Invention]

The present invention has been made from this point of view, and its object is to set a sufficiently large relief pressure when the antilock system is operating, and on the other hand, so small that residual pressure oil in the pressure accumulator is sufficiently small when the brake is released. An object of the present invention is to provide a relief valve device that sets the relief pressure.

[Outline of Invention]

Thus, the feature of the relief valve device according to the present invention made to realize such an object is that in the vehicle brake system, in particular, the pressure oil pumped up from the brake device to the pressure accumulator is connected to the master cylinder side so as to be recirculated. A first and second one-way valve that allows one-way pressure oil flow from the pressure accumulator side to the master cylinder side. The directional valve is provided in a structure in which an opening valve seat having a small seal cross-section that communicates with the pressure accumulator is closed by the seating of the valve element, and the second one-way valve opens the valve element by an urging spring force. It is composed of a cup seal having a large seal cross-sectional area which is assembled to a relief piston to be seated on a seat.

The wheel anti-lock system in which the relief valve device of the present invention is used may be of a type having a pressure accumulator that pumps pressure oil when the brake oil pressure is reduced, but in particular, the transmission path of the brake oil pressure from the master cylinder to the wheel cylinder is used. It is effectively used for an antilock system of a type in which a gate pulp device is provided to prevent a pedal kickback due to pressure oil fluctuations in the brake device, which is closed during antilock control.

Example of Invention

 The present invention will be described below based on embodiments shown in the drawings.

In the figure, a connection main path 1 from an oil chamber M / C of a master cylinder is connected via a gate valve device 10 and then a normally open type hold valve 2 which is electromagnetically closed by an antilock signal (brake pressure holding command). Wheel braking device Connected to wheel cylinder W / C. Further, a bypass path 4 is connected to the main path downstream of the hold valve 2 via a pressure reducing valve 3 which is electromagnetically opened by an antilock signal (brake pressure reducing command).
The gate valve device 10 is branched and connected via a pump 6 and a pressure accumulator 7.

Next, the structure of the gate valve device 10 will be described. This has a gate piston 13 that is slid over the stepped concentric opposed cylinders 11 and 12, and the gate piston 13 has a control oil at the large diameter end. It faces the chamber 14 and faces the main passage communicating chamber 15 downstream of the hold valve 2 at the small diameter end. Further, a taper valve body portion 17 is formed in an axial middle portion of the gate piston 13, and the taper valve body portion 17 cooperates with a pulp seat 18 formed as a cylinder stepped portion to open the gate valve portion 17 for opening and closing the main path 1. It is designed to be configured. Numerals 20 and 21 form an input oil chamber and an output oil chamber partitioned by the gate valve portion 17, and the input oil chamber 20 is communicated with the master cylinder M / C and the output oil chamber 21.
Are communicated with the hold valve 2 side.

The gate piston 13 is normally located at the position shown in the drawing, and the gate valve portion 17 is normally opened. When the gate piston 13 moves to the small diameter end side by δ ₁ in the drawing due to hydraulic pressure, the communication between the input and output oil chambers is established. The gate piston is closed so that the transfer hydraulic pressure from the pressure accumulator 7 is changed as described later.
It is performed when P _a and the hydraulic pressure P _{0 of} the main passage communicating oil chamber 15 have a constant differential pressure ΔP = (P _a −P ₀ ).

It should be noted that a hold spring having a light load may be provided to bias the initial position of the gate piston 13.

Next, the introduction control valve for introducing the pressure oil from the pressure accumulator 7 into the oil control chamber 20 will be described. The introduction control valve of this example is a connection opening of the branch passage 8 from the pressure accumulation device to the control oil chamber 14. The small diameter shaft portion 24 of the control piston 23 presses the pole valve body 22 that closes the valve to keep the valve closed. The control piston 23 is slidably fitted into the small diameter end side recessed cylinder 24 of the gate piston 13, and the small diameter shaft portion 24 axially penetrating the gate piston 13 is formed and extended from one end side thereof. A control spring 25 that exerts a spring force for maintaining the opening of the pawl valve body 22 is engaged with the other end side.

The spring force of the control spring 25 depends on the large diameter portion of the control piston, the cross-sectional area of the corresponding opening of the ball valve element 22, the hydraulic pressure value accumulated in the pressure accumulator 7 (normally determined by design), and the like. It is determined in relation to each other, but in short, the force acting on the control piston 23 in both axial directions changes the hydraulic pressure P ₁ of the main diameter communication chamber 20 and the hydraulic pressure P _{0 of} 15 to ΔP (= P ₁ -P ₀ ). The transmission oil pressure Pa from the excess pressure accumulator 7 is set to exceed _a certain value so that the ball valve body 22 is separated from the opening. Further, in the present example, the control piston 23 and the gate piston 13 are linked so as to be able to move together when the small gap of δ ₁ (<δ ₂ ) is filled. Therefore, once the control piston 23 and the gate piston 13 are separated from the opening of the ball valve body 22, When the pressure oil is introduced from the pressure accumulator 7 into the control oil chamber 14, the ball valve body 22 and the opening are separated from each other by the movement of closing the gate valve portion 17 of the gate piston 13 to restore the initial position of the gate piston 13. It is supposed to continue until the movement.

Reference numeral 26 is a check valve for connecting and communicating the pressure oil in the control oil chamber 14 to the first valve 2 side, and 27 is a relief valve for draining the pressure oil of the wheel cylinder W / C.

According to the above configuration, when the antilock control is started, pressure oil is introduced into the control oil chamber 14 by opening the introduction control valve of the gate valve device 10, and thus the gate valve portion 17 is closed. The oil pressure variation for antilock control is performed on the downstream side, which is separated from the upstream side of the gate valve device 10.

On the other hand, when the wheel antilock phenomenon does not occur, there is a Δ between the hydraulic pressures P ₁ of the main path communication chamber 20 and the hydraulic pressure P ₀ of 15.
Since the differential pressure exceeding P is not generated (the pressure is not reduced on the downstream side of the main path), the introduction control valve is kept in contact with the opening of the ball valve body 22, and therefore the hydraulic pressure from the pressure accumulator 7 is kept at this level. Without being transmitted to the system, the brake pressure control in the normal state is continued.

Next, the relief valve device 30 of the present example, which recirculates pressure oil from the pressure accumulator 7 to the master cylinder M / C side, will be described.
In the relief valve device 30 of this example, the relief pistons 32 and 33 are slidably engaged in the cylinder 31, and the urging springs 34 engaged with the relief pistons 32 and 33 press the relief pistons 32 and 33 in one direction. Thus, the first one-way valve that seats the ball valve element 35 on the opening valve seat 36 is configured. Also, this relief piston 32,
A piston cup 37 is attached to 33, and the piston cup 37 constitutes a second one-way valve.

The opening valve seat 36 is connected to the pressure accumulator 7 via the path 38, and the oil chamber 39 that the end of the relief piston 32 faces.
Is partitioned from the intermediate oil chamber 40 by the piston cup 37 and is connected to the master cylinder M / C side main path via a path 41.

According to the relief valve device having such a configuration, the first one-way valve having a small seal cross-sectional area provided by the small opening valve seat 36 and the second one-way valve having a large seal cross-sectional area provided by the piston cup 37. The relief pressure is determined by the one-way valve as follows.

During braking During braking, since the master cylinder M / C has hydraulic pressure, the relief pistons 32, 33 of the relief valve device 30 are
The force acting in the left-right direction in the figure is → P _m · A ₁ + F… (1) ← P _a・ A ₂ … (2) Since A ₁ > A ₂ , a sufficiently large relief pressure P _a ′ can be obtained by this area ratio.

When the brake is released In this case, the hydraulic pressure P _{m in the} equation (1) becomes zero, so the relief pressure P _a ″ is obtained only by the spring force F, and therefore the residual hydraulic pressure of the pressure accumulator 7 is sufficiently small. It becomes a value.

FIG. 2 shows the relationship between the relief pressure and the master cylinder pressure obtained in this example in comparison with the conventional example, and it can be seen that a large relief pressure can be obtained as the master cylinder pressure rises.

Note that the present invention is not limited to the above-described embodiment, and is similarly applied to any one of an antilock system of a type that does not use a gate valve, an antilock system having a proportioning valve together, and the like. Needless to say, in the case of the rear wheel antilock system, the relief pressure can be set relatively low by returning the relief pressure oil to the so-called downstream position of the proportioning valve. There is also.

〔The invention's effect〕

According to the present invention, it is possible to sufficiently reduce the residual pressure oil in the pressure accumulator of the antilock system, and to obtain a sufficiently large relief pressure when necessary, which makes it difficult to design a spring for determining the relief pressure. Its usefulness is extremely greater than the conventional one.

[Brief description of drawings]

FIG. 1 is a schematic diagram of an antilock system incorporating a relief valve device according to the present invention, and FIG. 2 is a characteristic diagram showing changes in relief pressure. 1 ... Main path 2 ... Hold valve 3 ... Pressure reducing valve 4, 8 ... Bypass path 5 ... Reservoir 6 ... Pump 7 ... Accumulator 10 ... Gate valve device 11, 12 ... Stepped cylinder 13 ... Gate piston 14 ... Control oil chamber 15 , 20, 21 ... Main path communication chamber 23 ... Control piston 24 ... Small axis 25 ... Control spring 26 ... Check valve 27 ... Relief valve 17 ... Taper valve body 18 ... Valve seat 22 ... Ball valve body 30 ... Relief valve Device 31 ... Cylinder 32, 33 ... Relief piston 34 ... Energizing spring 35 ... Pole valve element 36 ... Opening valve seat 37 ... Piston cup 38, 41 ... Path 39 ... Oil chamber 40 ... Intermediate oil chamber

Claims (1)

[Claims] 1. A relief valve device in a vehicle brake system, wherein the relief valve device is provided in a path connected to a master cylinder side so that pressure oil pumped from a brake device to a pressure accumulator during wheel antilock control can be returned to the master cylinder side. First and second one-way valves that allow one-way pressure oil flow from the pressure accumulator side to the master cylinder side are arranged. The first one-way valve has a small seal cross-sectional area that communicates with the pressure accumulator. The opening valve seat is provided so as to be closed by the seating of the valve body, and the second one-way valve is
A relief valve device for use in a wheel antilock system, comprising a cup seal having a large seal cross-sectional area, which is assembled to a relief piston that seats the valve element on an opening valve seat by an urging spring force.