JPS59100041A - Controller for braking pressure - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a brake pressure control device inserted into a connection between a wheel cylinder and a master cylinder of a rear axle of an automobile. axially slidably guided in a stepped bore against a first pressure spring to serve a first valve passage, the first piston acting to decelerate the vehicle by an inert mass. The first valve passage is therefore controllable 4υ and relates to a brake pressure control device which opens at a predetermined deceleration value and communicates between the end faces of the first piston.

A brake pressure control device of the type mentioned above is disclosed in US Pat. No. 2,242,297. According to the brake pressure control device disclosed in the US patent specification, the stepped piston is provided in the stepped bore of the housing so as to be slidable along the axial direction against the biasing force of the spring. The small diameter end face of the piston is operated by the pressure of the master cylinder. The chamber defined by the large-diameter end face of the piston is also hydraulically connected to a wheel brake provided on the rear axle of the vehicle.

The stepped piston has an axially extending pressure fluid passage which can be closed by a ball as a closing member when the deceleration of the vehicle reaches a predetermined value.

For this purpose, the known brake pressure control device is mounted on the vehicle at an angle of inclination, the axis of the stepped piston being aligned according to the longitudinal axis of the vehicle.

In this way, the known brake pressure control device is arranged at an angle, so that the ball will not move between the master cylinder and the wheel brake unless an acceleration force acts on the ball, or as long as the acceleration force is positive. valve passages and/or
Alternatively, treat the valve passage between the two end faces of the stepped piston. When the vehicle deceleration reaches a predetermined value, the ball rolls towards the valve seat and abuts the valve seat, causing the stepped piston to break the connection between the two end faces, thereby creating a connection between the master cylinder and the wheel brake. Isolate the hydraulic connection. As the pressure in the master cylinder increases further, the stepped piston is moved within the bore of the housing against the biasing force of the pressure spring due to the pressure acting on its small diameter end face. As a result, a pressure is created in the chamber defined by the large diameter end face of the stepped piston, which pressure is reduced in proportion to the working surface of the piston.

The brake pressure control device described above has the following drawbacks. First, the brake pressure is mainly controlled according to deceleration, and the absolute brake pressure is not affected by the turning point. Additionally, when a vehicle is loaded, high wheel cylinder pressures can easily build up on the rear axle before wheel locking occurs.

The present invention has been made in view of the above points, and its object is to provide brake pressure control with a simple configuration that can be operated in response to deceleration and brake pressure of a valve passage between a wheel brake and a master cylinder of an automobile. The goal is to provide equipment.

To achieve the above object, the invention provides a second stepped piston having a second valve passage in its bore for controlling the connection between the master cylinder and the wheel cylinder. It is slidably guided in the axial direction against a second pressure spring, and the second valve passage is operable in a pressure sensitive manner. The opening and closing of the second valve passage can be adjusted by adjusting the axial position of the first stepped piston. The turning point of the brake pressure control device can therefore be determined on the one hand by the deceleration of the vehicle and on the other hand by the pressure of the wheel brakes. At a predetermined vehicle deceleration value, the first stepped piston displaces a second valve passage closure member that is primarily controlled by the second stepped piston. When the vehicle is not under load, the vehicle deceleration necessary to close the first valve passage may be achieved with low brake pressure.

As such, only the first stepped piston is moved within the first stepped bore a relatively short distance. On the contrary,
When the vehicle is under load, the restriction of wheel braking at the rear axle only occurs at high brake pressures;
The risk of wheel locking due to high axle loads is therefore significantly reduced.

Furthermore, the switching point of the brake pressure control device is advantageously influenced by the fact that the biasing force of the second pressure spring is adjustable.

According to a preferred embodiment of the invention, the first and second stepped pistons are arranged coaxially within the housing, and the working surface is disposed 2 times relative to the second stepped piston.
It has been found that it is preferable to arrange them at a ratio of :1.

The second stepped piston also supports a valve seat made of an elastic material, and the valve seat forms a second valve passage with a closure member mechanically abutting the first stepped piston. ing. The second valve passage closing member is biased by the third pressure spring in the direction of closing the second valve passage against the first stage piston, thereby:
The closure member is held in a predetermined initial position relative to the second valve seat.

Embodiments of the present invention will be described in more detail below with reference to the drawings.

In the figure, reference numeral 1 indicates a housing, in which stepped bores 2 and 3 are coaxially formed. The stepped bore 2 has a large diameter bore part 4 and a small diameter bore part 5.
have. Further, the stepped bore 3 has a large diameter bore 6 and a small diameter bore 7. A stepped piston 8 is guided in the stepped bore 2 and has a large working surface 9 and a small working surface 10 . The stepped piston 8 has annular grooves 11, 12 on its circumferential surface, in which a sealing ring 13, 14 is arranged. Furthermore, the stepped piston 8 is urged toward the left regulating surface of the stepped bore 2 by a pressure spring 15 .

The active surfaces 9, 10 of the piston 8 are hydraulically connected to each other via pressure fluid passages 16, 17 and a chamber 18 formed in the piston. A valve ball 19 is arranged in the chamber 18, which ball rests against a perforated disc 20 in the illustrated inactive position of the brake pressure control device. Furthermore, when the valve ball 19 receives a predetermined pressure, it can move to a position where it abuts the valve seat 21 of the stepped piston 8.

A second stepped piston 22 is disposed within the stepped bore 3 so as to be freely slidable along the axial direction. This piston 2
The right end of 2 projects into the small diameter bore 24 through a sealing ring 23 and is biased by a pressure spring 25. The other end of the pressure spring 25 rests on a spring case 26 , which is engagedly connected to the housing 1 . The second stepped piston 22 also has an annular groove 28 formed in the large diameter portion of the large diameter bore 6, and a sealing ring 29 is supported within this groove.

The second stepped piston 22 defines within the large diameter bore 6 two annular bores 30, 31 which communicate with each other via an axial bore 32, an axial passage 33 and a radial passage 34. (- hydraulically connected; also annular bore 3
0 is connected to a brake pressure generator (not shown) via a housing connection part 35. Also, a housing connection part 36 extends from the annular groove 31, and this connection part 3
6 is hydraulically connected to the wheel brake on the rear axle of the vehicle.

Further, a valve closing member 37 is disposed within the axial bore 32 of the second stepped piston 22 . This closing member 37 has a projection 38 and extends through a connecting bore 39 formed between the stepped bores 2, 3 and rests on the small-diameter working surface 10 of the stepped piston 8. Further, the closing member 37 is biased toward the first stepped piston 8 by a pressure spring 40 .

A valve seat 41 made of rubber elastic material is provided at the left end of the axial bore 32, and this valve seat is connected to the valve closing member 3.
Together with 7, it forms a valve passage. This valve passage can be closed when the second piston 22 moves to the right.

The operation of the brake pressure control device configured as above will be explained below.

First, it is assumed that the brake pressure generator connected to the housing connection portion 35 is in a non-pressurized state and that the brake pressure control device is in the state shown.

The position of the first stepped piston 8 is defined by a pressure spring 15. The second stepped piston 22 is held at the left end position by a pressure spring 25, as shown.

Further, the valve closing member 37 is held in contact with the first piston 8 together with the protrusion 38 by a pressure spring 40. In this position, the valve closing member 37 is spaced apart from the valve seat 41 so that the annular bores 30, 3
1 and/or between the brake pressure generator and the wheel brake.

The pressure applied to the bousing connection 35 causes the annular bore 3
0, radial passage 34, axial bore 32 and annular bore 3
1 to the housing connection 36. Therefore, the pressure from the brake pressure generator acts directly on the wheel brake. Moreover, the pressure in the annular bore 31 is transferred to the small-diameter working surface 10 of the first piston 2 via the connecting bore 39.
is transmitted to the chamber defined by. Furthermore, this pressure is transmitted from the chamber via the pressure fluid passage 17 and the disc 20 to the chamber 18 in the first piston 8 . The pressure fluid is then transferred from the chamber 18 to the pressure fluid passage 1
6 to the large-diameter working surface 9 of the first piston 8 . Since the working surfaces 9, 10 of the first piston 8 have different areas, the piston 8 moves to the right in the stepped bore 2. As a result, the movement of the piston 8 is transmitted to the valve closing member 37 via the protrusion 38, and the closing member is separated from the valve seat 41. Furthermore, when pressure is applied to the second stepped piston 22, the piston 22 moves to the right due to the difference in the acting surfaces. Note that the working surface within the small diameter bore portion 7 is not pressurized.

The brake pressure control device described above is installed in a vehicle so that a force acts on the valve ball 19 during deceleration. This force ultimately moves the valve ball 19 until it abuts the valve seat 21, thereby causing the working surface 9 of the first piston 8,
Shut off the hydraulic connection between 10 and 10. When the valve ball 19 comes into contact with the valve seat 21, movement of the first piston 8 becomes impossible, and the position of the valve closing member 37 is also maintained. Then, when the pressure in the housing connection part 35 further increases, only the second piston 22 moves to the right until the valve seat 41 comes into contact with the valve closing member 37 and the connection between the housing connection parts 35 and 36 is cut off. be done. Therefore, the pressure in the annular bore 31 and/or the housing connection 36
The pressure in the wheel brake connected to the wheel brake remains constant or increases slightly.

When the brake is released, the pressure in the housing connection 35 is reduced and the movement movement described above is reversed until the illustrated deactivation condition is reestablished.

[Brief explanation of the drawing]

The figure is a longitudinal sectional view of a brake pressure control device according to an embodiment of the present invention. 1... Housing, 2, 3... Stepped bore, 8...
・First stepped piston, 15...pressure spring, 16,
17... Pressure fluid passage, 22... Second stepped piston, 25, 40... Pressure cup, 37... Valve closing member, 41... Valve seat.

Claims (1)

[Claims] 1. ) A brake pressure control device inserted into a connection between a wheel cylinder and a master cylinder of a rear axle of a motor vehicle; a first stepped piston slidably disposed and having a first valve passage, said first valve passage being controllable by an inertial mass as the vehicle decelerates; In a brake pressure control device opening at a deceleration value and forming a connection between the end faces of the first stepped piston; controlling the connection between the second stepped bore (3) and the wheel cylinder and the master cylinder; Second valve passage (
37.41) and coaxially and slidably guided in a second stepped bore against a second pressure spring (25); 1. the second valve passage is operable in a pressure sensitive manner; The second valve passage is opened and closed by the first stepped piston (8
) is adjustable according to its axial position. 2.) The brake pressure control device according to claim 1, wherein the biasing force of the second pressure spring (25) is adjustable. 3.) The first and second stepped pistons (8, 22
2. Brake pressure control device according to claim 1, characterized in that the brake pressure control device (1) is arranged coaxially within the housing (1). 4. The brake pressure control device according to claim 1, wherein the ratio of the working surfaces formed on the second stepped piston (22) is 2:1. 5.) The second stepped piston (22) supports a valve seat (41) made of an elastic material, and this valve seat is connected to the first stepped piston (22).
a closure member (in mechanical contact with the stepped piston (8) of
The brake pressure control device according to claim 1, wherein the second valve passage is formed together with 37). 6.) The closing member (37) is the third pressure panel (40)
6. The brake pressure control device according to claim 5, wherein the first stepped piston (8) is biased in the direction of closing the second valve passage.