JPS62110551A - Relief valve device used in antilock system for wheel - Google Patents

Abstract

PURPOSE:To make it easy to set relief pressure by constituting a relief valve device inside a passage through which a pressure oil inside and accumulator is returned to the master cylinder side so that a large relief pressure may be set in an anti-lock control and a small relief pressure may be set in the release of braking. CONSTITUTION:A main passage 1 for leading the hydraulic pressure inside a master cylinder M/C is connected to a wheel cylinder W/C through a gate valve device 10 and a normally open type hold valve 2 which is shut off by an anti-lock signal. A bypass passage 4 interposing therein reducing valve 3 whose passage is opened by the anti-lock signal branches from the main passage 1 on the downstream of the hold valve 2 and this is forked and connected to the gate valve device 10 through a reservoir 5, a pump 6 and an accumulator 7. In this case a relief valve device 30 is installed in a passage through which a pressure oil is returned from the accumulator 7 to the M/C side. Said device 30 consists of the first one-way valve including a ball valve body 35 and the second one-way valve including a piston cup 37.

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention relates to a wheel anti-lock system, and more specifically, to a wheel anti-lock system, which eliminates a sudden drop in wheel speed, that is, wheel lock, which may occur when braking a vehicle, by reducing the brake hydraulic pressure. The present invention relates to a relief valve device used in an anti-lock system.

[Background of the invention]

Recently, various types of wheel anti-lock technology have been proposed to improve safety during vehicle braking. The brake hydraulic pressure transmission path (hereinafter referred to as the main path) that connects the brake equipment and the
A normally open hold valve is installed that is normally open and closed when the brake oil pressure needs to drop, and a path connected to the main path (hereinafter referred to as the binoyasu path) is provided to this main path. The pi/gas path and the main path of the output system on the brake equipment side are separated by a normally closed pressure reducing valve, and the normally closed pressure reducing valve is opened when it is necessary to lower the brake oil pressure. Brake pressure oil flowing into the pipe-to-arm passage is pumped up, for example, into a pressure accumulator, and the pressure oil in this pressure accumulator is returned to the main passage. An electronic system that outputs an anti-lock signal (signal for reducing, increasing, and holding brake hydraulic pressure as necessary) to switch the opening/closing operation of the brake hydraulic pressure depending on the state of change in wheel speed during vehicle braking. It has been proposed that this is done by a control circuit.

By the way, in the pressure accumulator used in such an anti-lock system, it is desirable that the residual pressure oil is as small as possible when it is not in operation, and it is also desirable that abnormally high pressure can occur! In such cases, it is desirable to release such high pressure to the master cylinder to prevent damage to the pressure accumulator.From this perspective, a relief valve is provided in the path connecting the pressure accumulator to the master cylinder. Many things have been done. However, in conventional relief valves of this kind, the spring force of the valve body pressing spring of the check valve is generally determined in accordance with a predetermined relief pressure, so the design particularly determines the spring force of the valve body pressing spring. The problem was that it was difficult.

The reason is that the hydraulic pressure ports that act on the relief valve are 1:1 on the master cylinder side and the pressure accumulator side, so the relief pressure is only outside the differential pressure caused by the spring force, and the residual pressure oil in the pressure accumulator is In order to reduce the spring force, it is necessary to set the spring force to a small value, but in this way, when the anti-lock system is activated with a relatively low brake pressure, pressure oil will not flow back from the pressure accumulator through the relief valve. This is because it will occur.

[Purpose of the invention]

The present invention has been made from this point of view, and its purpose is to set a sufficiently large relief pressure when the anti-lock system is in operation, and on the other hand, to set the relief pressure so low that the 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 a relief pressure.

[Summary of the invention]

The relief valve device according to the present invention, which has been made to achieve such an object, is characterized in that, in a vehicle brake system, the pressure oil pumped from the brake device to the pressure accumulator is connected to the master cylinder so that it can be returned to the master cylinder side. A relief valve device is provided in a passageway, and includes first and second relief valve devices that allow pressure oil to flow in one direction from the pressure accumulator side to the master cylinder side.
A one-way valve is disposed, and the first one-way valve has a Sekiguchi valve seat with a small seal cross-sectional area that communicates with the pressure accumulator and is configured to close when the valve body is seated, and the second one-way valve The valve seal is constituted by a cup seal having a large seal cross-sectional area, which is assembled to a relief piston that seats the valve body on the open valve seat by the force of a biasing spring.

The wheel anti-lock system in which the relief valve device of the present invention is used may be of the type that has a pressure accumulator that pumps up pressure oil when the brake oil pressure is reduced; Effective for a type of anti-lock system in which an r-) pulp device is installed in the transmission path of the brake device, which is closed during anti-lock control to prevent pedal kickback due to fluctuations in pressure oil in the brake device. used for.

[Embodiments of the invention]

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

In the figure, the main connection path 1 from the oil chamber 1c of the master cylinder is e-) via a valve device 10, and then a normally open hold valve 2 that is electromagnetically closed by an anti-lock signal (brake pressure holding command). It is connected to the wheel brake device wheel cylinder W/C. In addition, a bypass path 4 is connected to the main path downstream of the hold valve 2 via a pressure reducing valve 3 that is electromagnetically opened in response to an anti-lock signal (brake pressure reduction command). 5
, a pump 6 , and a pressure accumulator 7 .

Next, the structure of the gate valve device 10 will be described. It has a Y-to-vis piston 13 slidably fitted over stepped concentric opposed cylinders 11 and 12, the dart piston 13 being controlled at the large diameter end. It faces the oil chamber 14 and, at the small diameter end, faces the main path communication chamber 15 downstream of the hold valve 2. Also, a cheek valve body part 17 is formed in the intermediate part of the axis of the r-) piston 13, and this cooperates with a valve seat 18 formed as a cylinder stepped part to open and close the main path 1. A valve portion 17 is configured. 20.21 forms an input oil chamber and an output oil chamber partitioned by the dart valve portion 17, and the input oil chamber 20 is communicated with the master cylinder M/C, and the output oil chamber 2
1 is connected to the hold valve 2 side.

The gate piston 13 normally leaves the r-toe valve part 17 open at the position shown in the figure, and when it moves by the amount δ1 shown in the figure toward the small diameter end under hydraulic action, the gate piston 13 communicates between the person and the output oil chamber. As will be described later, the movement of the r-toviston is such that the transmission hydraulic pressures P and L from the pressure accumulator 7 and the hydraulic pressure P0 of the main path communication oil chamber 15 are Δp = (
This is done when a constant pressure difference (pm - po) is generated.

Note that a lightly loaded hold spring may be provided to bias the piston 13 to its initial position.

Next, the introduction control valve that introduces pressure oil from the pressure accumulator 7 into the control oil chamber 20 will be explained. The introduction control valve of this example has a connection opening to the control oil chamber 14 of the branch path 8 from the pressure accumulator. The goal valve body 22 that closes the valve is pressed by the small-diameter shaft portion 24 of the control piston 23 to keep the valve closed. The control piston 23 is slidably fitted into a concave cylinder 24 on the small diameter end side of the r-toviston 13, and has a small diameter shaft portion 24 formed and extended from one end thereof to pass through the dart piston 13 in the axial direction. A control sedge ring 25 that applies a spring force to maintain the opening and closing of the goal valve body 22 is engaged with the other end.

The spring force of the control ring 25 is determined by the cross-sectional area of the large diameter part of the control piston 23 and the abutting opening of the goal valve body 22, the hydraulic pressure accumulated in the pressure accumulator 7 (usually determined by design), etc. In short, the force in both axial directions acting on the control piston 23 is determined in relation to the main reverse communication chamber 20.
hydraulic pressure P1 and hydraulic pressure P15. is Δp(=p1-Pa)
The goal valve body 22 is set so as to be separated from the opening when the pressure difference P1 exceeds a certain value. In addition, in this example, the control piston 2
3 and dart piston 13 are linked together so that they can move together when a small gap δ1 (delta 2) is filled.
Therefore, once pressure oil is introduced from the pressure accumulator 7 into the control oil chamber 14 by separating the mail valve body 22 from the opening, the peel valve body 22 and The separated state of the openings continues until the f-toviston 13 returns to its initial position.

Note that 26 is a check valve that connects and communicates the pressure oil in the control oil chamber 14 to the first valve 2 side, and 27 is a relief valve that drains the pressure oil from the foil cylinder W/C.

According to the above configuration, when the anti-lock control is started, pressure oil is introduced into the control oil chamber 14 by opening the introduction control valve of the r-to valve device 10, and therefore f-) the valve portion 17 is closed. Therefore, oil pressure fluctuations for anti-lock control are performed on the downstream side of the r-toad valve device 10, which is separated from the upstream side.

On the other hand, if wheel anti-lock does not occur, there is a difference Δ between the oil pressure P1 of the main path communication chamber 20 and the oil pressure 200 of the main passage communication chamber 20.
Since a pressure difference exceeding P is not generated (the downstream side of the main path is not depressurized), the inlet control valve remains in contact with the opening of the goal valve body 22, and therefore the hydraulic pressure from the pressure accumulator 7 is transferred to this system. is not transmitted, and the brake pressure control in the normal state continues.

Next, the IJ IJ-F valve device 30 of this example that recirculates pressure oil from the pressure accumulator 7 to the master cylinder V side will be described. The relief piston 32.33'Jt is pressed in one direction by the biasing spring 34 engaged with the relief piston 32.33, and the goal valve body 35 is seated on the opening valve seat 36.
It constitutes a one-way valve. Further, a piston cup 37 is attached to the relief pistons 32 and 33, and the piston cup 37 constitutes a second one-way valve.

The open valve seat 36 is connected to the pressure accumulator 7 via a path 38, and an oil chamber 39 facing the end of the relief piston 32.
is separated from the intermediate oil chamber 40 by the piston cup f37, and is connected to the main passage on the master cylinder Ic side via a passage 41.

According to the relief valve device having such a configuration, the first one-way valve with a small sealing cross-sectional area provided by the small opening valve seat 36 and the piston click! The second one-way valve with large seal cross-section provided at 37 will determine the relief pressure as follows.

During braking When braking, the master cylinder M/C has oil pressure, so the relief pistons 32 and 33 of the relief valve device 30
The force in the left-right direction in the figure that acts on is → Pm-A++F
-(1)-Pa" A2
(2) However, F: Spring force A2: Opening valve seat seal cross-sectional area, and since AI>Am, a sufficiently large relief pressure P1' can be obtained by this area ratio.

When the brake is released, in this case, the hydraulic pressure P in equation (1) becomes zero, so the relief pressure pH is obtained only by the Sguring force F, and therefore the residual hydraulic pressure in the pressure accumulator 7 becomes a sufficiently small value. .

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

Note that the present invention is not limited to the above-mentioned embodiments, and may be applied to any type, such as the type (7) 7-inch lock system that does not use an r-to-valve, or the anti-lock system that also uses Floposy pulp. Needless to say, the same applies to rear wheel anti-lock systems, and if the relief pressure oil is returned to the position downstream of the so-called proportion fourning valve,
There is also the advantage that the relief pressure can be set relatively low.

〔Effect of the invention〕

According to the present invention, it is possible to make the residual pressure oil in the pressure accumulator of the anti-lock system sufficiently small, and to obtain a sufficiently large relief pressure when necessary, thereby making it difficult to design a sedge ring for determining the relief pressure. Its usefulness is far greater than that of the conventional ones.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram of an anti-lock 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...Pinosu road 5...
・IJ *)” - Halo... I ring 7... Pressure accumulator
1o...r-t valve device 11.12...stepped cylinder 13...dart piston 14...control oil chamber 15.
20.21... Main path communication chamber 23... Control piston 24... Small diameter shaft portion 25.
...Control spring 26...Check valve 27...
Relief valve 17...Cheek valve body part 18...
Valve seat 22... Mail valve body 30... Relief valve device 31... Cylinder 32.33...
Relief piston 34...Biasing spring 35...Mail valve body 3
6...Opening valve seat 37...Piston cup 38.41...Route 39...Oil chamber 40...
intermediate oil chamber

Claims (1)

[Claims] In a vehicle brake system, a relief valve device is installed in a path connected to the master cylinder so that pressure oil pumped up from the brake device to the pressure accumulator can flow back to the master cylinder during wheel anti-lock control. First and second one-way valves are arranged to allow pressure oil to flow in one direction toward the cylinder side, and the first one-way valve has an open valve seat with a small seal cross-sectional area that communicates with the pressure accumulator. The second one-way valve is configured to close when the body is seated, and the second one-way valve is a cup seal with a large seal cross-sectional area assembled to a relief piston that seats the valve body on the open valve seat by a biasing spring force. A relief valve device used in a wheel anti-lock system, characterized by comprising: