DE4201825A1 - Valve for vehicle antilock braking circuit - has throttle in front of inlet and uses slider subject to pump pressure - Google Patents

Abstract

The antilock vehicle braking circuit having a master cylinder connected by a brake pipe with a wheel brake with an inlet valve in the brake pipe and a pump whose pressure side is connected to the brake pipe between the master cylinder and the inlet valve. The system has a throttle (82) in front of the inlet valve (EV) which is bridgeable by a bypass channel (83) which is controllable by a slider (72) subject to pump pressure. ADVANTAGE - Braking system in which noise generations considerably reduced.

Description

The invention relates to a brake system and Pump with a pressure valve for this brake system with the Features of the preamble of claim 1.

Such a brake system is from DE-OS 38 42 699.4 be knows. The system described there sees a difference pressure limiter upstream of the inlet valve, which is a throttle has effect, so that the pressure drop at the inlet valve is reduced. This results in noise reduction.

A pump is known from DE-OS 29 12 935. The be there Written pump is for use in an anti-lock hydraulic brake system provided. To the noise to minimize the emission of the pump during operation proposed in the published patent application, the pressure valve a damping chamber, a check valve and a throttle to connect.

Pressure valve and check valve are in one valve carrier trained, which are inserted into the housing of the pump can. A holding pot is screwed into the housing and holds the valve carrier. Between one end of the valve carrier and the bottom of the pot is an expansion chamber trained by a hard elastic rubber element is bordered. This element has the task of pressure peaks in the Record pressure medium at the outlet of the pump, which is indicated in the closed brake system would cause noise.

There is the task of making noise even further to reduce.

This object is achieved with the means defined in claim 1 are mentioned.

Claim 2 describes a pump with a valve carrier, in which a switching valve is integrated, which is a bypass Lei lock to a throttle in the brake line as soon as the Pump delivers. The throttle causes a pressure drop, so that the differential pressure in the inlet valve is reduced.

The description of the invention is based on 5 figures.

Fig. 1 hydraulic circuit diagram of an anti-lock brake system,

Fig. 2 pump housing with a pressure relief valve cartridge and ei nem integrated memory,

Fig. 3 of the first variation of Fig. 2,

Fig. 4 second variation of Fig. 2,

Fig. 5 further variation of Fig. 2 with an additional union switching valve.

First, reference is made to FIG. 1.

The brake system consists of a master brake cylinder 1 to which a wheel brake 2 is connected via a brake line 3 . Inserted into the brake line 3 is an inlet valve 4 which keeps the brake line open in its basic position and blocks the brake line in its switching position. In parallel to the inlet valve, a check valve 5 is connected, which opens to the master cylinder. The check valve enables an immediate reduction in pressure in the wheel brakes when the actuating force is reduced to the master brake cylinder.

The wheel brake 2 is connected via a further line, the return line 6 , to the master brake cylinder. A pump 8 with a suction valve 9 and a pressure valve 10 is inserted into the line. An outlet valve 7 is inserted between the wheel brake 2 and the pump 8 , which blocks the return line 6 in its basic position and releases the return line 6 in its switching position. On the suction side of the pump, that is, between the suction valve 9 and the outlet valve 7 , a low-pressure accumulator (hereinafter called return accumulator 11 ) connects. It has the task of temporarily absorbing pressure medium that is not conveyed directly by the pump.

The master brake cylinder has a piston 12 which is connected to a pedal (shown symbolically). On the piston 12 , a sleeve 13 is attached, which is in the ge shown basic position of the piston immediately before an outlet bore 14 , which is connected to a (not shown) Re servoir. In the basic position of the piston 12 there is therefore a connection between the reservoir and the brake circuit. If the piston 12 is moved under the action of the pedal force (as shown to the left), the sleeve 13 passes over the outlet bore 14 so that the brake circuit is separated from the reservoir and a pressure can be built up in the brake circuit. The path between the basic position of the piston 12 and the position in which the sleeve has completely passed the outlet bore 14 is marked with s be.

The braking system described so far is now provided with a white low-pressure accumulator (hereinafter called transition accumulator 15 ). This includes according to the Fig. 1 to the printing region 6 '' (between the pump and the master brake cylinder) of the return line 6 on. It consists of a piston 18 with egg ner sleeve 20 , which separates the storage space from the atmosphere. The cuff 20 is supported on a leaf spring 19 . The leaf spring 19 can engage in a curvature on the bottom of the piston. This measure is intended to prevent noise emissions. The piston 18 is under the action of a spring which is only slightly preloaded. In the pressure range 6 '' of the return line 6 is in the area between the transition memory 15 and the confluence of the return line 6 in the brake line 3, a throttle 17 and a check valve 16th The two elements are connected one behind the other. The check valve 16 prevents pressure medium from entering the transition accumulator 15 during braking that is not regulated.

The brake system works according to the following scheme.

A pressure can be built up in the wheel brake 2 by actuating the pedal. Sensors monitor the turning behavior of the wheel so that a risk of locking can be determined. If this occurs, the system switches to ABS mode. The pump runs during ABS mode. To lower the pressure in the wheel brake, the inlet valve 4 is now closed and the outlet valve 7 is opened. As a result, pressure medium from the wheel brake arrives in the return accumulator 11 and is first conveyed from there into the transition accumulator 15 by means of the pump. As long as the memory is not yet completely filled 15 prevails upstream of the check valve 16, only a small pressure, because the spring of the transition memory 15 has only ei ne light preload. As soon as the transition store 15 is completely filled, the piston 18 bears against a rear stop, so that the pressure before the check valve 16 can rise. As soon as the pressure of the master cylinder is reached, pressure medium flows via the check valve 16 to the master brake cylinder. The memory 15 cannot be emptied, since this would have the consequence that the pressure upstream of the check valve 16 would drop and would therefore not be able to open the check valve 16 against the master cylinder pressure. As long as a regulation is running and a pressure is present in the master brake cylinder, the transition store 15 remains filled. Only when the pedal is released and the pressure in the master brake cylinder drops, is the spring of the transition accumulator 15 able to move the piston 18 and to spend the pressure medium in the transition accumulator 15 in the master brake cylinder 1 . The sleeve passes over the outlet bore 14 without pressure, so that no damage can occur.

In the following figures, an embodiment of the pump 8 with pressure valve 10 , throttle 17 , check valve 16 and accumulator 15 is shown.

For this purpose, Fig. 2 shows a section through a pump housing 30. Pump pistons 32 , which are driven via an eccentric 33 , are arranged in an axis 31 of the housing 30 . The pump has two circuits and supplies one brake circuit with one circuit each.

The pistons 32 limit the pump chambers 34 , each of which connects to the return line 6 (see FIG. 1) via a suction valve 9 . The suction valves 9 are arranged on the axis 31 of the Ge housing 30 . Two stepped blind bores 35 are provided in the housing 30 perpendicular to the axis 31 . Each Sackboh tion corresponds to a pump chamber 34 .

Each blind bore 35 receives a cylindrical Ventilträ 36 ger. This is held by a cup-shaped closure part 39 .

According to the upper part of FIG. 2, the Ventilträ 36 houses the pressure valve 10 and a throttle 17th According to the un lower part of the memory 15 and the check valve 16 is also integrated.

This form of presentation was chosen for the sake of simplicity, in principle, both circles can also use one or another embodiment.

Both types are largely identical, so that only the upper drawing is referred to below. Additional changes are described in the lower part of FIG. 2.

The stepped blind bore 35 has in its larger diameter area, which opens to the outside, an internal thread. In the lower part of the blind bore, which lies in the interior of the housing, the cylindrical valve carrier 36 is inserted in a sealing manner. For this purpose, the valve carrier 36 has a seal 37 at its lower end.

The lower end has approximately one third of the total length of the valve carrier 36 . A peripheral edge 38 adjoins the area of the valve carrier 36 which is inserted into the lower part of the blind bore 35 . This edge interacts with the cup-shaped closure part 39 .

The closure part 39 consists of a sleeve and a Bo the. The sleeve has an external thread and is screwed into the internal thread of the blind bore 35 . The edge of the sleeve is supported on the edge 38 and thus fixes the valve carrier 36 in the housing. The upper part of the valve carrier 36 , which extends approximately over 2/3 of the total length of the valve carrier, is located within the closure part 39 . A chamber 40 is formed between the end face of the valve carrier 36 and the bottom of the closure part 39 .

The upper part of the valve carrier has a cylindrical shape, where the cylinder has a diameter which is somewhat smaller than the inner diameter of the sleeve of the closure part 39 . This creates an annular gap 41 between the cylinder wall of the valve carrier and the inner wall of the sleeve.

The pressure valve is now arranged in the lower part of the valve carrier 36 , specifically in the axis of the valve carrier. In the end face of the valve carrier, an annular insert piece 42 is attached, which carries the valve seat and interacts with a valve body 43 .

On its outside, the insert 42 carries a umlau fende edge 44 , which is set to the bottom of the blind bore 35 . In this way, a central inlet space 46 is formed and an annular space 45 . The inlet chamber 46 is connected to the pump chamber 34 via a housing channel 47 .

On the other side of the insert 42 is the outlet space 48 , in which the valve ball 43 is also arranged. The outlet space 48 communicates with the chamber 40 via a channel 49 which runs obliquely to the axis of the valve carrier 36 .

Between the peripheral edge 38 and the cylindrical region of the valve carrier in the upper part, an annular groove 50 . Channel 49 opens into this. Pressure medium that flows in via the pressure valve 10 thus first reaches the outlet chamber 48 and from there via the channel 49 into the annular groove 50 . From the annular groove 50 , it continues to flow into the chamber 40 via the annular gap 41 .

The valve support 36 also has a blind bore 51 which opens towards the chamber 40 . A carrier 52 is inserted into the blind bore 51 and has a centrally arranged diaphragm 17 . The aperture 17 lies between the chamber 40 and the space which is separated from the carrier 52 in the blind bore 51 .

Between the aperture 17 and the space 40 , a flat Fil terteil 54 is arranged.

The space which is delimited in the blind bore 51 is connected via a channel 55 to the annular space 45 already described. This in turn is connected to the brake line 3 via a housing channel, not shown.

The connection of the pump 8 to the brake circuit is thus Herge.

In the lower part of FIG. 2, the valve carrier 36 is expanded by a memory 15 . The changes are minor.

The sleeve of the closure part 39 is extended so that the chamber 40 is expanded. This now receives a piston 18 , which is pressed by a weak spring 63 in the direction of the valve carrier 36 . If pressure medium gets into the chamber 40 , the piston 18 is displaced towards the bottom of the pot 39 , so that the chamber 40 is expanded and absorbs pressure medium. The space behind the piston 18 communicates with the atmosphere via a bore in the closure part 39 . A locking ring is placed over the bore.

The check valve 16 is arranged as follows.

The blind bore 51 in the valve support 36 is elongated, so that the space which is delimited by the support 52 in the blind bore is enlarged. This space now accommodates a valve body 65 . The valve body 65 consists of an elastic material which is designed as a hat 66 and is placed over a head 67 . An edge 68 on head 67 holds the hat.

The edge of the hat 66 protrudes beyond the head 67 and serves as a sealing lip which can be placed on the carrier 52 and in this way blocks the connection.

The head 67 is connected to a pin 68 , which is inserted into a bore in the carrier 52 and in this way guides the valve body 65 .

If a pressure builds up in the channel 55 from the brake line 3 , the valve 16 closes, so that no pressure medium gets into the memory 18 .

On the other hand, as soon as the reservoir is filled, pressure medium can flow from the chamber 40 into the brake line 3 via the check valve 16 .

In the Fig. 3 shows a first modification of the valve carrier 36 is shown. The channel 55 no longer opens into the annular space 45 but into an annular space 70 at the transition from the small ren to the larger step of the blind bore. The channel in the pump housing 30 must be laid accordingly.

This arrangement has the advantage that the edge 44 does not have to be absolutely tight.

In the channel 55 , an aperture insert 71 can now be screwed. The aperture cross section can be adapted to the respective brake system.

Another change is to not support the valve ball 43 directly on the valve carrier 36 , but on a sliding body 72 which slides in a bore 73 in the valve carrier 36 and is supported by a spring 74 on the carrier 52 .

The sliding body can now be used as a switching body for the channel 49 , which is shown in more detail in FIG. 5.

FIG. 4 shows another arrangement of the seal 37 (see also FIG. 2). The seal is now no longer below the edge 38 , but above and corresponds to the inner wall of the sleeve of the closure part 39 .

Fig. 5 shows a further modification of the upper part of Fig. 2, wherein in an axial bore of Ventilträ gers 36, a valve spool 72 (see Fig. 3) is provided. This slider serves two purposes. Firstly, it controls channel 49 . On the other hand, it controls the bypass to a throttle 82 in the brake line.

For this purpose, the valve carrier 36 is seen with a further groove 80 ver, which can also be formed by the annular space 70 .

The groove 80 is connected on the one hand to the channel 55 via a channel 81 , into which the diaphragm 82 is inserted. Another bore 83 connects the groove 80 to the space between the slide 72 and the carrier 52 .

In the housing (not shown) is a hen vorgese that connects the groove 80 to the inlet valve 4 (EV).

With a normal pressure build-up, in which no brake pressure regulation takes place, the connection between the master cylinder and the wheel brake takes place via the channel 55 , the space 84 , the channel 83 and from there via the open inlet valve to the wheel brake 2 .

If a brake slip control takes place, the pump uses its promotion, so that pressure medium gets into the outlet space 48 . The piston 72 is thereby, according to the Dar position shifted to the right, and blocks the mouth of the channel 83 in the room 84th The above-mentioned connection is interrupted. Pressure medium from the master cylinder therefore now flows via the throttle 82 into the annular space 80 and from there to the inlet valve (EV).

This throttling causes the pressure upstream of the intake valve is reduced compared to the pressure in the master cylinder. This how consequently, the pressure drop across the inlet valve is reduced and, as proven, the noise emission this valve is reduced.

With a further displacement of the piston 72 , the channel 49 is finally released, so that a connection of the pump via the channel 49 and the throttle 17 to the channel 55 and thus to the master cylinder or via the throttle 82 to the Radzy cylinder exists.

Claims (2)

1. Brake system with a master cylinder and at least one wheel brake, which is connected via a brake line to the master cylinder, an inlet valve being arranged in the brake line, and a pump, the pressure side of which is connected to the brake line between the master cylinder and the inlet valve, characterized in that a throttle ( 82 ) is arranged upstream of the inlet valve and has a lockable bypass line, the pump connecting the master line and throttle to the brake line. 2. Pump for a brake system according to claim 1, characterized in that the pressure valve ( 10 ) of the pump ( 8 ) is formed on a slide ( 72 ) which is arranged in a carrier ( 36 ) in which the bypass line as a bore ( 83 ) is formed, wherein the slide ( 72 ) is acted upon by the pump pressure, and is thereby shifted in a sense so that the bore ( 83 ) is closed.