JP2522237Y2 - Brake fluid pressure control valve - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial application field> The present invention relates to a brake fluid pressure control valve used for an automobile or the like.

<Conventional technology> As a conventional brake fluid pressure control valve, for example,
What is disclosed in -21563 is known.

Referring to FIG. 4, a conventional brake hydraulic pressure control valve will be described. An inflow chamber C communicating with a hydraulic pressure generation source and an outflow chamber D communicating with a brake cylinder are formed by a first piston B fitted in a housing A. It is partitioned.

A second piston E having a different-diameter pressure receiving portion is fitted into the first piston B.

Further, a poppet valve comprising a stopper F fixed to the first piston B, a valve seat G fixed to the second piston E, a washer H, a poppet valve J and a spring K is provided on the large-diameter pressure receiving portion side of the second piston E. A mechanism is formed.

The first spring P is contracted between the flange portion of the first piston B and the second piston E, and the second spring L is a washer M locked to the first piston B and a cap fixed to the housing A. N.

When the hydraulic pressure in the inflow chamber C rises and the acting force acting on the large-diameter and small-diameter pressure receiving portions of the second piston E reaches a first predetermined pressure that overcomes the spring force of the first spring P, the second piston E E moves to the left in the figure and the valve seat G becomes the poppet valve J
To temporarily close the flow path from the inflow chamber C to the outflow chamber D.

When the fluid pressure in the inflow chamber C further rises, the acting force is reversed, and the second piston E slightly moves rightward in the drawing, and the fluid pressure is fed to the outflow chamber D.

By repeating such an operation, the hydraulic pressure in the outflow chamber D is reduced at a fixed rate with respect to the increase in the hydraulic pressure in the inflow chamber C.

Further, when the hydraulic pressure in the inflow chamber C rises and the hydraulic pressure acting on the first piston B reaches a second predetermined pressure that overcomes the spring force of the second spring L, the first piston B moves to the right in FIG. Then, the poppet valve J continues to be closed, and the hydraulic pressure is increased again while compressing the outflow chamber D.

<Problems to be solved by the present invention> The conventional brake fluid pressure control valve has the following problems.

<A> Since both loads of the first and second springs P and L act on the first piston B, the variation of the second predetermined pressure increases.

<B> Since the chamber accommodating the first spring P is sealed, a compression resistance and a negative pressure resistance of the internal air are generated when the first and second pistons B and E operate, and the first and second predetermined pressures are reduced. Variation increases.

<C> First and second liquid pressure characteristics are determined as described above.
Is large, it is difficult to approximate to the ideal hydraulic pressure distribution of the vehicle.

<Object of the present invention> The present invention has been made in order to solve the above-mentioned problems, and an object of the present invention is to provide a brake hydraulic pressure which can approximate a brake cylinder hydraulic pressure to an ideal hydraulic pressure distribution as much as possible. It is to provide a control valve.

<Embodiment> The configuration of the present invention will be described with reference to FIG.

Reference numeral 1 denotes a housing having a bottomed stepped hole 1a. The housing 1 has a medium-diameter inflow chamber 1c communicating with a hydraulic pressure source (not shown) through a connection port 1b formed in a side portion, and is mounted on an opening. And a large-diameter outflow chamber 1d that communicates with a brake cylinder (not shown) through a connection port 2a of the cap 2 described above.

The stepped hole 1a is formed so as to gradually decrease in diameter toward the bottom side, and a ventilation path 1e communicating with the atmosphere is formed in the bottom surface.

Reference numeral 3 denotes a cylindrical first piston slidably fitted in the large-diameter portion of the stepped hole 1a. A valve seat 4 is provided on the inner periphery, and a seal member 5 is provided on a groove on the outer periphery. 1c and outflow chamber 1d are defined.

Reference numeral 6 denotes a rod-shaped second piston that penetrates the first piston 3, and includes a large-diameter valve head 6a located on the outflow chamber 1d side and a small-diameter pressure receiving shaft portion 6b located on the inflow chamber 1c side.

The terminal end of the small-diameter pressure receiving shaft portion 6b is inserted through the seal member 7 into the bottom of the small-diameter stepped hole 1a communicating with the air passage 1e.

Reference numeral 8 denotes a valve mechanism including the valve seat 4 and the valve head 6a, and opens and closes a flow path between the two chambers 1c and 1d by the relative movement of the first and second pistons 3 and 6.

Reference numeral 9 denotes a first spring for urging the first piston 3 toward the inflow chamber 1c, which is contracted between the first piston 3 and the cap 2 in the outflow chamber 1d.

The first piston 3 is locked in the stepped portion of the stepped hole 1a, and the retreat position is regulated to be constant.

Reference numeral 11 denotes a second spring which urges the second piston 6 toward the outflow chamber 1d in the inflow chamber 1c, and is contracted between the washer 10 contacting the inner wall of the stepped hole 1a and the second piston 6. .

The valve mechanism 8 is kept open by the spring force of the second spring 11 that urges the second piston 6 toward the outflow chamber 1d.

The configuration is not limited to this. For example, the valve seat 4 constituting the valve mechanism 8 may be mounted on the second piston 6 side, or the inflow chamber 1c
And the outflow chamber 1d are formed to have the same diameter and the retreat position of the first piston 3 is restricted by a retaining ring, or the small-diameter pressure receiving shaft portion 6d of the extended second piston 6 penetrates through the bottom of the housing 1. And may be projected outside.

<Operation> Next, the operation of the brake fluid pressure control valve will be described with reference to FIGS. FIG. 2 is a hydraulic pressure characteristic diagram, in which the horizontal axis indicates the inflow chamber hydraulic pressure and the vertical axis indicates the outflow chamber hydraulic pressure.

<A> Proportional rise in hydraulic pressure The valve mechanism 8 is in the valve-open state until it reaches the first predetermined pressure.

Therefore, the hydraulic pressure supplied from a hydraulic pressure generation source such as a master cylinder reaches the outflow chamber 1d from the inflow chamber 1c via the valve mechanism 8.

Therefore, the outflow chamber is maintained until the valve mechanism 8 reaches the first predetermined pressure.
The hydraulic pressure of 1d increases proportionally with the hydraulic pressure of the inflow chamber 1c.

 The hydraulic characteristics at this time are represented by straight lines O to X in FIG.

<B> Slow rise in hydraulic pressure When the hydraulic pressure in the inflow chamber 1c continues to rise and the hydraulic pressure acting on the small-diameter pressure receiving shaft portion 6b reaches a first predetermined pressure that overcomes the urging force of the second spring 11, The second piston 6 moves to the left in the figure, and the valve head 6a is seated on the valve seat 4 to temporarily close the valve mechanism 8.

Further, when the hydraulic pressure in the inflow chamber 1c rises, the valve head 6a is larger than the pressure receiving area of the small-diameter pressure receiving shaft portion 6b, so that there is a difference in the hydraulic pressure acting force between the two 6a and 6b.

As a result, the second piston 6 moves to the right in the drawing to open the valve mechanism 8, and the inflow chamber 1c and the outflow chamber 1d communicate.

By repeating the opening and closing operations of the valve mechanism 8, the fluid pressure in the outflow chamber 1d is reduced at a fixed rate with respect to the rise in the inflow chamber 1c.

This decompression phenomenon in the outflow chamber 1d continues until the hydraulic pressure in the inflow chamber 1c reaches the second predetermined pressure.

The hydraulic characteristics at this time are straight lines X to Y having a gentler gradient than the straight lines O to X in FIG.

The pressure reduction gradient can be appropriately set by changing the pressure receiving area ratio between the valve head 6a and the small diameter pressure receiving shaft 6b.

<C> Re-rise of hydraulic pressure When the hydraulic pressure of the inflow chamber 1c continuously increases and the hydraulic pressure acting on the first piston 3 reaches a second predetermined pressure that overcomes the urging force of the first spring 9, 1 piston 3 is valve seat 4
Then, the valve mechanism 8 is moved to the right side in the figure and the valve mechanism 8 is closed to obtain a turning point of Y in FIG.

When the first piston 3 further moves rightward with the valve mechanism 8 closed, the volume of the outflow chamber 1d is reduced, so that the outflow chamber 1d is reduced.
Hydraulic pressure rises again at a constant rate.

 The hydraulic characteristics at this time are represented by straight lines Y to Z in FIG.

<Modification> Next, a modification shown in FIG. 3 will be described.

Note that parts similar to those in the above-described embodiment are numbered in hundreds and their description is omitted.

In the modification shown in FIG. 3, instead of abolishing the first spring 9 of FIG. 1, the first piston 103 has a shape having a hydraulic pressure receiving portion having a different diameter. The first piston 103 is urged toward the inflow chamber 101c using pressure.

That is, the first piston 103 having the small diameter portion 103a formed on the inflow chamber 101c side and the large diameter portion 103b formed on the outflow chamber 101d side is connected to the housing 101.
Is inserted into the stepped hole 101a.

As for the hydraulic characteristics, the first piston 103 having a different diameter after the break point Y in FIG. 2 which is the second predetermined pressure reduces the volume of the outflow chamber 101d. The straight lines Y to W indicated by broken lines are obtained.

The first piston 103 has a small diameter portion 103a and a large diameter portion 103b.
By changing the different diameter ratio, the decompression gradient after the turning point Y can be appropriately set.

<Effect of the present invention><A> Since the spring load for applying the acting force to the second piston does not act on the first piston, the second predetermined pressure fluctuates little.

<B> Fluctuations in the predetermined pressure in FIGS. 1 and 2 are small because there is no closed air chamber. Fluctuations in the predetermined pressure in FIGS. 1 and 2 that determine the hydraulic characteristics according to <a> and <b> above. And it can be approximated to the ideal hydraulic pressure distribution.

Therefore, the effect of preventing early locking of the wheels is significantly improved, and the braking effect can be effectively exerted.

<C> When the first piston is urged by the first spring, the risk of liquid leakage is extremely low because the number of seal locations is small.

[Brief description of the drawings]

 FIG. 1 is a cross-sectional view of a brake hydraulic pressure control valve according to the present invention. FIG. 2 is a cross-sectional view of a hydraulic pressure characteristic valve. FIG. 3 is a cross-sectional view of a modified example.

Claims (2)

(57) [Scope of request for utility model registration] A first piston slidably housed in a housing and defined as an inflow chamber communicating with a hydraulic pressure generating source and an outflow chamber communicating with a brake cylinder, and the hydraulic pressure of both chambers acts thereon. A second pressure-receiving valve mechanism having a small-diameter pressure receiving portion penetrating the first piston on the inflow chamber side and having a large-diameter pressure receiving valve mechanism including a valve seat and a valve head on the outflow chamber side; A piston, a first spring contracted in the outflow chamber to bias the first piston toward the inflow chamber, and a first spring contracted between the housing bottom in the inflow chamber and the second piston to move the second piston toward the outflow chamber. When the fluid pressure in the inflow chamber reaches a first predetermined pressure, the valve mechanism repeats the opening and closing operations to reduce the fluid pressure in the outflow chamber at a fixed rate, and further inflows. When the fluid pressure in the chamber reaches the second predetermined pressure, the valve mechanism is maintained in a closed state. A brake fluid pressure control valve configured to increase the fluid pressure in the outflow chamber at a constant rate. 2. A housing which is slidably housed in a stepped hole of a housing,
A small-diameter inflow chamber communicating with the hydraulic pressure generation source and a large-diameter outflow chamber communicating with the brake cylinder, and a first piston having a different diameter on which the hydraulic pressure of both chambers acts; A second piston having a small-diameter pressure receiving portion penetrating therethrough on the inflow chamber side and forming a large-diameter pressure receiving valve mechanism including a valve seat and a valve head on the outflow chamber side between the first piston; and a housing in the inflow chamber. A second spring that is contracted between the bottom of the second piston and the second piston and urges the second piston toward the outflow chamber. When the hydraulic pressure in the inflow chamber reaches a first predetermined pressure, the valve The mechanism repeats the opening and closing operations to reduce the hydraulic pressure in the outflow chamber at a fixed rate, and further, when the hydraulic pressure in the inflow chamber reaches the second predetermined pressure, maintains the valve mechanism in a closed state to reduce the hydraulic pressure in the outflow chamber. A brake fluid pressure control valve configured to re-raise at a constant rate.