DE3200930A1 - Hydraulic brake system with antilock device for vehicles - Google Patents

Description

PATENTANWÄLTE ' . »·· · · · · d» .-? No. «Franz Tuisthopf

WUESTHOFF-v.PECHMANN-BEHRENS-doET ^ "''" ⁰ ^ ** ³ * ^ «thoff {^ ₇

DIPL.-ING. GERHARD PULS (19J2-I97U EUROPEAN PATENT ATTORNEYS dipl.-chem. dr. e. Baron von Pechmann DR.-ING. DIETER BEHRENS DIPL.-ING .; DIPL.-VIRTSCH.-ING. RUPERT GOETZ

1A-55 563

D-8000 MUNICH SCHWEIGERSTRASSE

phone: (089) 662051 telegram: protectpatent

TELEX: $ 24070

January 14, 1982

Patent application

Applicant:

LUCAS INDUSTRIES LIMITED Great King Street Birmingham 19, England

Title:

Hydraulic braking system with anti-lock device for vehicles

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DR.-ING. DIETER BEHRENS DIPL.-1NG .; DIPL.-TFIRTSCH.-ING. KUPERT GOKT

LA-55 563 D-8000 MUNICH

SCHWEIGERSTRASSE 2

TKI.F.PON: (0R9) (1 (1 JO JI TKLBGKAM Ml PHOTEd'l'ATI'.NT TELEX: J 24 070

Hydraulic braking system with anti-lock device

for vehicles

The invention relates to a hydraulic brake system with an anti-lock device for vehicles, in which a modulator depending on a locking signal, which is sent by a device for determining the locking conditions of the wheel is generated when braking at a blocking point, by allowing brake fluid to flow back from the wheel brake a braked wheel is relieved of brake actuation pressure.

In a known anti-lock device of this type with a hydraulic pump and a main cylinder connected downstream Separating valve, the pump is designed as a suction pump and sucks at least when the blocked state is ended Brake fluid from a quick drain chamber, into which the brake fluid when the blocking signal occurs was diverted to relieve the brake, and pumps this brake fluid back to the master cylinder.

This known type of device has the advantage that the isolating valve can be replaced by a throttle device can having a permanent connection between the master cylinder and the brake enables. In such known burner systems

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however, the hydraulic pump is used exclusively for the braking system and is in addition to every other in a vehicle already existing power source is provided, for example, a separate power steering pump, an air compressor or negative pressure generated by the vehicle engine.

A hydraulic brake system with an anti-lock device of the type described at the beginning is characterized according to the invention characterized in that the modulator is a permanent connection between a master cylinder for actuating the wheel brake and produces a brake line to the wheel brake itself, a displacement piston that works in a bore in a housing, is movable in two opposite directions, whereby brake fluid is exerted by its movement in the first direction the brake line is sucked through a first check valve into a displacement chamber and a throttle device switched on between the master cylinder and the brake line is, and by its movement in the second direction brake fluid from the displacement chamber through a leading to the master cylinder second check valve is ejected through, and that a power source is provided which is capable of pressurizing a support chamber to thereby normally the displacer in a to hold the advanced position, which determines the path by which the displacement piston is adjusted in the second direction can be, and in which the effective volume of the displacement chamber is smallest, with a change in pressure in enables the support chamber to move the displacement piston in the first direction on the basis of the blocking signal, and the pressure in the support chamber decreases when the Blocking signal changes again and the displacement piston in moves the second direction.

The throttle device is preferably switched off when

- 3 "- 3 ^{55 563}

the brake pressure is approximately equal to the pressure supplied by the master cylinder.

The displacer separates the fluid used in such a power source from that used in and from the braking system him normally different fluid. The power source can be from a hydraulic pump and / or a hydraulic one Memory for, for example, the power steering or the suspension of the vehicle can be formed. As a source of power can also a source for pneumatic positive or negative pressure can be used, e.g. a negative pressure source, in particular in the form of the Suction force from the suction line of a vehicle engine, or a compressed air source.

The brake fluid is preferably drawn from the master cylinder the brake line through a first flow control valve, which has a first throttle device, supplied, and the fluid from the power source can be in the SUHzunga chamber fed through a second flow control valve having a second throttle device.

The modulator can have a wall that is movable in a housing, this into a first and a second chamber divided and cooperates with the displacement piston to the wheel brake supplied through a flow control valve To counteract pressure, the power source normally one of the chambers has a corresponding fluid pressure supplies, which holds the wall in a rest position, in which the displacement piston in the corresponding, advanced Position is held, and both chambers are connected to each other when a blocking signal occurs, whereby the wall can move into a working position and together with this movement the displacement piston retracts and thereby increases the effective volume of the displacement chamber, after which, when the blocking signal is extinguished, only said one chamber is connected to the power source.

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As used herein, the term "overpressure" means pressure greater than atmospheric pressure, and "Underpressure" means a pressure lower than atmospheric pressure, in particular a vacuum.

When the power source is compressed air, the compressed air acts in the first chamber, whereas the second chamber normally acts connected to the atmosphere. When a blockage condition occurs, the chambers are connected to one another, and at When the blocking signal is terminated, the compressed air is released from the second chamber to the atmosphere.

When the power source is a vacuum, the first chamber is connected to atmosphere during normal brake application. The second chamber is connected to vacuum before and after a blocking signal, but while one is in place Blocking signal connected to the first chamber.

In any case, the connection between the two chambers is controlled by an electromagnetically operated valve, whose electromagnet is excited depending on the blocking signal in order to establish the connection between the two chambers.

When the power source is pressurized hydraulic Is fluid, the second chamber is normally with normal brake application and after a blocking signal to a container connected for fluid and the first chamber is always connected to the pressure source.

In another embodiment, the fluid pressure from the power source can be supplied to that end face of the displacement piston which faces away from the displacement chamber and forms at least part of the support chamber, wherein a solenoid operated pressure relief valve a normally closed connection line between the support chamber and a low pressure tank controls.

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This arrangement is particularly advantageous when the power source is hydraulic fluid supplied under pressure; in In this case, the displacement piston can be a differential piston in order to generate higher pressures than in the brake system can be supplied by the power source.

Another advantageous feature of the invention is that means for periodically monitoring the delay of the braked wheel is provided and the locking signal is deleted after it has first been generated, if the deceleration of the wheel has decreased over two successive scans.

The blocking signal causes the solenoid of an electromagnetically operated quick release valve to be excited rapid discharge of the fluid from the support chamber to the displacement piston, the electromagnet being de-energized as soon as the braked wheel is accelerated. If the braked wheel is slow to pick up speed, it becomes electromagnetic activated valve alternately on and off until the wheel accelerates.

Several exemplary embodiments of the invention are explained in more detail below with reference to schematic drawings. It shows:
1 shows a system plan of a hydraulic brake system with an anti-lock device for a vehicle with a longitudinal section through a modulator, a graphic representation of the temporal relationship of modulated brake pressures,

a longitudinal section through a modulator according to another embodiment,

the section 4-4 in Fig. 3,

a section similar to FIG. 3 through a modulator according to a modified embodiment,

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6 shows a section similar to FIG. 3 through a modulator

according to a further embodiment and FIG. 7 shows a section similar to FIG. 3 through a modulator according to yet another embodiment.

The illustrated in Fig. 1 hydraulic brake system with anti-lock device has a pedal-operated hydraulic Master cylinder 1 for actuating a wheel brake 2, which transfers fluid under pressure from the master cylinder 1 a modulator 3 is supplied.

The modulator 3 has a housing 4 in which are arranged: an electromagnetically operated pressure relief valve 5, a first flow control valve 6, an expander piston 7, which works in a bore section 8, which is a quick release chamber 9 forms, and a pressure intensifier 10.

The pressure relief valve 5 has a valve body 11, which is normally by a spring in contact with a valve seat is biased to the connection between a port 12 connected to the pressure intensifier 10 and the quick release chamber 9 to lock.

The flow control valve 6 is in one end portion of a stepped, longitudinal bore 13 arranged in the housing 4, the opposite end of the smallest diameter the bore section 8 forming the tendon drainage chamber 9 forms. The flow control valve 6 has an externally stepped sleeve 14, the two sections of which are sealed in the bore sections of the largest and medium diameter of the bore 13 are arranged, a hollow flange piston 15, the works in a bore 16 of the sleeve 14, and an externally conical valve body 17, which is in a bore 18 of the collar piston 15 is slidably guided and attached to a valve seat 19 is able to apply, which is supported by a shoulder in the flange piston 15

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is formed. The valve body 17 has a longitudinal groove 20, and the valve seat 19 is diametrically opposed Groove or shallow recess provided when the valve body 17 rests on the valve seat 19 between these two forms a first throttle point of fixed cross-sectional area. The valve body 17 is supported by one end of a stem 21 of reduced diameter which carries an enlarged head 22 at its opposite end.

The expander piston 7 carries one end of a force transmission member 23 which is displaceably guided and a sealing member 24 penetrates in a partition wall 25 which is arranged in the bore section 8 of the smallest diameter of the bore 13 is. The opposite end of the force transmission link located on the opposite side of the partition wall 25 23 has a longitudinal bore 26 in which a spring 27 acting on the head 22 is arranged. Of the Head 22 is held in position by an externally cup-shaped holder 28, and spring 27 biases the valve body 17 in the direction of the valve seat 19 before. Between the collar piston 15 and a radial flange 33 on the power transmission member 23, a compression spring 32 is clamped for regulating purposes. The compression spring 32 presses the collar piston 15 on Stop piece 31 at the end of the bore 13 and the flange 33 on the partition wall 25, whereby the expander piston 7 a retracted position is set in which the volume of the rapid deflation chamber 9 is smallest. The length relation between the shaft 21 and the valve body 17 is chosen so that the valve body 17 in the illustrated retracted rest position has a distance from the valve seat 19.

The flow control valve 6 has a second throttle device 34 of variable cross-sectional area, which of a machined in the sleeve 14 diametrical opening 35, which is in constant communication with the master cylinder 1 via a channel 36 in the housing 4, and one in the collar piston 15 formed circular recess 37 ge

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forms which, according to the position of the collar piston 15 in the bore 16 of the sleeve 14, the flow through the opening and metered into a radial opening in the collar piston 15.

In the drawn retracted position, the throttle device takes 34 a largest open position, in which there is an unthrottled flow of fluid from the master cylinder 1 through the non-narrowed space between the valve body 17 and the valve seat 19, the groove 20, the central portion of the Bore 13 and a connecting channel 38 in the housing 4 to the wheel brake 2 allows. The stop piece 31 is with a diametrical or other slot 39 is provided, which makes it possible that in the bore 18 of the collar piston 15 prevailing Fluid pressure acts on the adjacent end of the collar piston 15.

The pressure booster 10 has an externally stepped displacement piston 40, which works in a second stepped bore 41 in the housing 4. In the bore 41 are close to The end of the smallest area of the displacement piston 40 is a displacement chamber 42 and between the opposite end A support chamber 43 is formed from the largest area of the displacement piston 40 and a second flow control valve 44.

The modulator 3 is with a conventional servo braking and Steering system 45 of a vehicle connected, which in the example shown has a pump 46, which is from the vehicle engine or can be driven by an electric motor and can suck fluid from a container 47 and to a flow divider 48 able to pump, which is designed so that it supplies fluid to a memory 49 and a steering valve 50, from which the Fluid is returned to the container 47. The reservoir 49 supplies pressurized fluid to the flow control valve 44 and an unillustrated brake servo mechanism. To monitor the pressure in the memory 49 is a

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$ 4

Low pressure warning switch 51 is provided. The container 47 is connected to an opening 53 in the housing 4 via a pipe 52, which with the rapid discharge chamber 9 via a throttle point 54 and a check valve preloaded by spring force 55 and via a separate channel 56 with a throttle point 57 is in connection.

The second flow control valve 44 has an externally stepped sleeve 60, both sections of which are in the bore sections of the largest and mean diameter of the bore 41 are arranged below the seal. In the bore of the sleeve 60 works a hollow collar piston 61 with a through axial bore 62, which at its inner end has a fixed Has throttle opening 63 which forms a first throttle point. The flow control valve 44 has a second throttle point or device 64 of variable cross-sectional area, which of a machined in the sleeve 60 radial Opening 65, which is in constant communication with the via a spring-loaded check valve 66 Memory 49 is, and an annular recess 67 formed in the collar piston 61 is formed, which accordingly the position of the collar piston 61 in the bore of the sleeve 60, the flow through the opening 65 and into a radial opening metered in the collar piston 61. In the depicted withdrawn The throttle device 64 assumes a largest open position with the support of a soft compression spring 68 a, in which it via the throttle opening 63 a fluid pressure connection between the reservoir 49 and the support chamber 43 manufactures.

For the outer end of the sleeve 60, a stop member 69 is provided which has a diametrical or other slot 70, which enables the fluid pressure prevailing in the bore of the sleeve 60 to act on the adjacent end of the collar piston 61 acts.

55 563

In the rest position shown, the electromagnet is de-energized, so that the valve body 11 is pressed by spring force against the valve seat formed by the opening 12 and in the support chamber 43 includes accumulator pressure. As a result, the displacement piston 40 is held in a rest position, in which the effective volume of the displacement chamber 42 is smallest.

The portion of the bore 13 located between the flow control valve 6 and the partition wall 25 is connected to the displacement chamber 42 via a spring-loaded check valve 71 in connection, and the displacement chamber 42 is connected to the radial opening 35 in the sleeve 14 via a check valve 72 preloaded by spring force.

The flow control valve 6 takes the one described above fully open position and establishes an open connection between the master cylinder 1 and the wheel brake 2.

When the brake is to be applied, by actuating the master cylinder 1 fluid is through the bore 13 through Wheel brake 2 and pressurizes the displacement chamber 42 via the check valve 71.

If the braked wheel slips or locks, one delivers Device for determining the deceleration of the wheel, a locking signal which generates an electrical current which the solenoid of the pressure relief valve 5 is energized. The electromagnet is excited in such a way that the pressure prevailing in the support chamber 43 passes through the check valve 55 is displaced through into the sehnellablaßkammer 9, and there the throttles 54 and 57 do not allow free flow to the container 47, there is sufficient back pressure, the urges the expander piston 7 relative to the flow control valve 6. As a result, the compression spring 32 is compressed and causes the valve body 17 to come into contact with the valve seat 19

55

creates, after which the spring 27 is compressed. At the same time, the one prevailing in the displacement chamber 42 urges Pressure the displacement piston 40 relative to the flow control valve 44, so that from the leading to the wheel brake 2 Line fluid is sucked through the check valve 71 into the displacement chamber 42 and that supplied to the wheel brake 2 Pressure is reduced. Fluid also begins from accumulator 49 through second flow control valve 44 to flow through to the support chamber 43, from which it over the throttles 54 and 57 are returned to the container 47 will. The opening widths of the throttle points are usually the same 54 and 57 selected so that the flow through the flow control valve 44, plus the flow caused by the initial speed of movement of the displacer 40, minus the current absorbed by the expander piston 7, a back pressure of approximately 1.3 bar is generated.

When the effective volume of the displacement chamber 42 is increased, fluid is removed from the brake line plus a residual flow to take up by the flow control valve 6, the brake line pressure supplied to the wheel brake 2 decreases with a Speed, which is determined by the force in the springs 32 and 27.

When the displacement piston 40 has covered a distance which is sufficient to generate the pressure supplied to the wheel brake 2 To reduce about 3.5 bar, it goes back to a movement speed that corresponds to the flow speed through the Flow control valve 6 corresponds. Thus the brake pressure remains constant. Since the main pressure in the support chamber 43 has now decreased, the expander piston 7 begins below the Effect of the springs 32 and 27 to expel fluid from the rapid discharge chamber 9 through the throttle point 57 through.

If the wheel accelerates slowly, the high-speed

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drain valve 5, whereby it stops the movement of the displacer 40 towards the flow control valve 44. The displacement piston 40 then begins under the action of fluid that flows from the reservoir 49 through the flow control valve 44 flows further into the support chamber 43 to move relatively away from the flow control valve 44. Through this movement is fluid from the displacement piston 40 out of the displacement chamber 42 and through the check valve 72 to the the side of the flow control valve corresponding to the master cylinder 1 6 pressed. The check valve 71 separates the brake line leading to the wheel brake 2 from the fluid contained in the displacement chamber 42 which is released during this movement of the displacement piston 40 away from the flow control valve 44 the master cylinder pressure overcomes. During this time, however, the brake pressure increases somewhat, usually to around 11 or 12 bar, since the displacement chamber 42 can not receive the flow from the flow control valve 6 during this phase, the thus begins to increase the brake pressure at a low speed, the exact amount of which differs from that at this point in time in the force generated by the springs 27 and 32 is dependent.

After the electromagnet has been de-energized for a fixed period of time, usually 16 ms, it becomes re-energized for a further variable period of time, provided that the stall condition is not yet proper has been corrected. Fluid from the support chamber is again released through the solenoid operated quick release valve 5 is displaced through when the displacement piston 40 is under the influence of the brake line pressure supplied to the wheel brake 2 and the flow through the flow control valve 6 begins to vary relative to the flow control valve 44 to move towards. However, such movement is now much in terms of both speed and distance smaller because the brake line pressure driving the displacer 40 is much lower than that above

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initial brake pressure relief described. Hence will this restoring movement of the expander piston 7 is not influenced to a large extent, but is only temporarily slowed down or maybe stopped for a short time.

The working steps described above are then repeated in the manner of a control loop until the blocking state is eliminated. The electromagnet then remains de-energized, so that the brake is actuated again with control the flow control valve 6 is continued and the displacer 40 returns to its original resting position.

In the embodiment described above, the master cylinder 1 is always connected to the wheel brake 2 If the accumulator 49 fails, however, the low-pressure warning switch 51 switches the solenoid-operated quick pressure relief valve 5, which thus remains closed and together with the check valve 66 in the support chamber 43 Fluid volume, causing movement, or further movement, of the displacer 40 to the flow control valve 44 is prevented. The wheel brake 2 can therefore be operated and released unhindered.

From the above it follows that the on the displacement piston 40 acting brake pressure causes a pressure increase in the support chamber 43, because this fluid from the check valve 66 and the Druckschneilablaßventil 5 is retained. If one of the valves 5 and 66 is leaking, the pedal travel increases when the displacement piston 40 moves. However, since the master cylinder 1 each time it is released of the pedal is refilled, at the moment in which the displacement piston 40 reaches an "end position", e.g. a stop piece 73 abuts, no further adjustment path is lost. After the system has been repaired, pressure escapes Memory 49 the displacer 40 in its rest position

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and pushes the "lost" fluid back to the reservoir of the master cylinder 1.

Figure 2 shows a common relationship between wheel speed- '*. speed, brake pressure and electromagnetic current on a common time basis for a roadway with a low coefficient of friction. When 'the example shown, the variable and fixed periods of time during which the electromagnet is energized, ι among each other and with the periods of de-energized solenoid j

shown the same way. As described above, this is not the normal case, and the variable or adaptive Time periods depend on the stored deceleration values of the braked wheel.

In a modified embodiment, the power source for reactivating the brake can be of a pneumatic nature and from a source of negative pressure such as a connecting line to the intake manifold of the vehicle engine, or be formed by a compressed air source. In both cases the pressure intensifier is 10 designed as a movable wall that is exposed to the pneumatic power source and directly on the expander piston 7 works.

The solenoid operated pressure relief valve 5 controls the operation of the power source for the movable Wall to regulate the position of the displacement piston 40 according to whether the blocking signal is active or not.

The modulation assembly shown in Figs. 3 and 4 has a housing 81 which contains a piston 82 which Housing 81 is divided into a first chamber 83 and a second chamber 84. The piston 82 acts as a support for a flexible membrane 85, which at its peripheral edge with the housing 81 is connected.

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The housing 81 carries at one end a valve block 86 which has a longitudinal bore 87 in which a from Piston 82 carried displacement piston 88 is displaceably guided. In the bore 87 is between the displacement piston 88 and a fixed partition wall 90, a displacement chamber 89 is formed. On the opposite side of the partition wall 90, a flow control valve 91 is arranged in the bore 87.

In the valve block 86 is an electromagnetically operated valve 92 for controlling the pressurization of the chambers 83 and 84 arranged. His electromagnet 93 is excited as a function of a blocking signal.

Normally, the electromagnet 93 is de-energized and there is a negative pressure in the chamber 83, which creates a suction port 'Vehicle engine is removed through a pipe 94. The chamber is always spaced apart from the atmosphere Inlet openings 95 in connection, which a filter 96 is connected upstream in the flow direction. In the drawn In position, a valve body 97 rests against a first valve seat 98 in order to supply the vacuum from one into the chamber 84 leading external pipe 99 to lock, and is spaced from a second valve seat 100 in order to have one between the Valve seats 98 and 100 arranged passage 101 to connect the vacuum supply to the chamber 83.

The flow control valve 91 is arranged in an enlarged stepped portion at the outer end of the bore 87 and has an externally stepped sleeve 102, the two sections of which in the sections of largest and medium diameter of the Bore 87 are arranged under a seal, a hollow collar piston 103 which works in a bore 104 of the sleeve 102, and an externally conical valve body 105 which can be placed against a valve seat 107 which is supported by a shoulder

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is formed at the outer end of the bore of the collar piston 103. The valve seat 107 is with a diametrical groove or Shallow recess 109 is provided, which when the valve body 105 rests on the valve seat 107 between these two a forms the first throttle point of fixed cross-sectional area. The valve body 105 is .from one end of a shaft 110 borne by a reduced diameter which penetrates the bore of the collar piston 103 and a bore in the partition wall 90 and rests with its free end on the displacement piston 88. The valve body 105 is supported by a soft spring biased towards the valve seat 107, and acts between the valve block 86 and a radial flange on the collar piston 103 a compression spring 112 which holds the flange of the collar piston 103 on the associated end of the sleeve 102 in contact. The length relation between the shaft 110 and the displacement piston is selected so that in the drawn retracted rest position, in which the volume of the displacement chamber 89 is smallest, the valve body 105 is spaced from the valve seat 107 has.

The flow control valve 91 has a second throttle point or device 114 of variable cross-sectional area on, which by a machined in the sleeve 102 radial opening 115, which via a channel 116 in the valve block 86 is in constant communication with a master cylinder, and one in the flange piston 103 formed in the form of a circular ring Depression 117 is formed, which the flow through the opening 115 and into a radial opening in the collar piston 103 accordingly the position of the collar piston 103 in the bore 104 of the sleeve 102. In the drawn withdrawn position the throttle device 114 assumes a largest open position in which it allows an unthrottled fluid flow from the Master cylinder through the non-narrowed space between the valve body 105 and the valve seat 107 and a radial Opening 119 in the collar piston 103 allows through to an outlet opening 118.

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The displacement chamber 89 is connected to the channel 116 via a first, spring biased check valve 120 in communication, and the outlet port 118 is to the displacement chamber 89 connected via a second check valve 121.

In the rest position shown, the displacement piston 88 takes its position because of the negative pressure prevailing in the chamber 83 Rest position, the displacement chamber 89 has its smallest volume and the flow control valve 91 is fully open.

When the brake is to be applied, it is usually hydraulic Fluid from the master cylinder on its way through the open radial opening 115 unimpeded to the outlet opening 118 funded.

If a device for determining the deceleration of the braked wheel generates a locking signal, the Solenoid 93 of the valve 92 energized and the valve body 97 pushed away from the valve seat 98 and attached to the Valve seat 100 applied. This blocks the supply of negative pressure to chamber 83 and connects the two chambers 83 and 84 with each other, so that the same pressure prevails in both. The one supplied to the brake and via the check valve 121 Pressure acting on the displacer piston 88 causes the displacer piston 88 to retreat and thereby the Valve body 105 enables the valve seat 107 to be applied, this constriction generating a back pressure which acts on the inner end of the collar piston 103, which moves against the force of the springs 111 and 112 and the Flow through the opening 115 regulates. This reduces the speed with the flow control valve 91, with the fluid is supplied to the brake, and the pressure applied to the brake is reduced by the displacement chamber 89.

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When the blocking signal is terminated, the electromagnet is de-energized and the valve body 97 is activated by a spring 122 the valve seat 98 applied. This re-establishes the vacuum supply to chamber 83 and piston 82 is drawn in its withdrawn starting position postponed, | wherein the effective volume of the displacement chamber 89 is determined by the air suction to the vacuum source with j th speed is reduced to its initial minimum value. A regulation for this can be made through the installation a flow restrictor in the pipe 94 so that the return flow to the master cylinder with that in the brake flowing current becomes the same. During this movement of the displacement piston 88, something is displaced from the displacement chamber 89 Fluid returned through check valve 120 to passage 116 and the master cylinder, and the brake is again actuated by fluid flowing through the flow control valve 91 at a predetermined rate. When the displacement piston 88 reaches its rest position, the valve body 105 is lifted from the valve site 107. /.

In the embodiment described above, a Device is provided which switches off the electromagnetically operated valve 92 if the vacuum source fails.

A modification of the embodiment described can be that the tube 94 to the atmosphere or to a vacuum is connected and the inlet ports 95 are connected to a source of compressed air. Thus, the piston 82 is nor sometimes held in its retracted position by positive pressure supply.

Another possibility is the inlet openings with a hydraulic pressure source, in particular with the Pump or the accumulator of a hydraulic power steering system

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to connect and to connect the pipe 94 to the container for hydraulic fluid.

In the modified embodiment shown in FIG the shaft 110 carries at its free end a head 131 which is displaced in a bore 132 in the displacement piston 88 is led. A spring 133 is clamped between the head 131 and a contact surface on the displacement piston ″ 88 Spring 111 is supported on an extension piece of collar piston 103.

In this training, the setting of the flow rate at the flow control valve 91 of the summarized Force of the springs 112 and 133 dependent. Because the force in the spring 133 increases with the adjustment of the displacement piston 88 changes, the flow rate through the flow control valve changes in the event of a blocking condition correction 91 corresponding to the fluid volume quickly derived from the brake.

Structure and mode of operation of the embodiment shown in FIG. 5 are otherwise the same as in the embodiment according to FIGS. 3 and 4. Corresponding to one another Components are denoted by the same reference numerals.

In the modified embodiment shown in FIG. 6, there is no interaction between the displacement piston and stem 110. In the example shown, these are flow control valves 91 and the shaft 110 are arranged in a bore at right angles to the bore 87, and that of the flow control valve 91 facing away from the free end of the shaft 110 is carried by a piston 140 of considerable diameter. Normally, the piston 140 is on either side of the negative pressure or atmospheric pressure prevailing in the chamber 83 Exposed to pressure. When the electromagnet of the

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Valve 92 is excited as a function of a blocking signal and the valve body 97 is pressed against the valve seat 98, communication between the opposite sides of the piston 140 is broken. Because the pressures in the two chambers 83 and 84 are balanced and on one side of the piston 140 act, on the opposite side of which the outlet pressure prevails, there is a pressure difference at piston 140, which moves the piston 140 relatively away from the flow control valve 91 against the force in a spring 141. The way of working the flow control valve 91 and the remainder of the modulation assembly corresponds to the description given in connection with FIGS. 3 and 4, and corresponds to one another Components are denoted by the same reference numerals.

In this embodiment it is ensured that if for any reason the support for the movable wall fails, a fault protection switch switches off the electromagnet of valve 92 and an unhindered I.

Flow to and from the brakes is possible even if

the displacement piston 88 moves away from its normal position.

In the modulation assembly shown in Fig. 7, the external tube 99 is large through an internal channel 145 Replaced diameter, and the connection between the valve seat 98 and the second chamber 84 is through another Inner channel 146 made of a similarly large diameter. The inner channel 146 is at an intermediate point in the longitudinal direction via an air inlet valve 147 to the filter 96 im Air inlet connected. The air inlet valve 147 has a valve body 148 carried by a stem 149, the free end of which rests freely releasably on the valve body 97, and a spring 150 which the valve body 148 in the direction a valve seat 151 which is located approximately half the length of a valve seat between the inner channel 146 and the filter 96

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extending channel 152 is formed. When the valve body 97 is in the rest position shown on the valve seat 98 is applied, the stem 149 keeps the valve body 148 away from the valve seat 151, so that the chamber 84 via the channel 152 in free communication with the inlet port 95 is.

When the solenoid of valve 92 is energized and valve body 97 is lifted from valve seat 98 and before the valve body 97 can come into contact with the valve seat 100 and the vacuum supply to the chamber interrupts and connects the two chambers 83 and 84 with one another, the valve body 148 first comes to rest on Valve seat 151 and blocks the communication between the atmosphere and the chamber 84. Then the valve body settles 97 to the valve seat 100, and the same pressures are supplied to both sides of the piston 82, which have different surfaces because of the rod-shaped displacement piston 88. The piston 82 pulls the displacer 88 back to relieve the brakes in the manner previously described, wherein the effective volume of the chamber 83 with the reduction of the Volume of the chamber 84 increases.

During this movement of the piston 82, the air inlet valve 147 has no effect because it is displacing air higher pressure from the chamber 84 into the lower pressure chamber 83 from the vacuum source no air is sucked out of the inner channels 145 and 146.

When the blocking signal is terminated, the solenoid of valve 92 is de-energized and the air inlet valve 147 opens before the valve body 97 is returned to the position shown. Chamber 83 becomes Air is sucked off, and additional air flows into the chamber 84 via the air inlet valve 147, which increases the volume of the Chamber 84 fills up.

When the piston 82 has moved to the extreme end of the bore with the blocking signal active, before the blocking signal goes out, and when the blocking signal ends, it is about half the way back to its starting position has, closes when a further blocking condition occurs j

ι the air inlet valve 147 again before the valve body j by 97 applies to the valve seat 100, and only the volume of air enclosed in the chamber 84 can be used to fill the Chamber 83 can be used, in which there was previously negative pressure.

By using the air inlet valve 147, the air supply is therefore obtained when the blocking signal is present, the for its part, limits the considerable amount of air that!

a blocking condition for reactivating the brakes by ί Vacuum must be extracted. The action of the air inlet valve 147 is particularly large when the volume of the chamber 83 is considerable.

Claims (17)

PATENTANWÄLTE WU ESTHOFF - ν. PECHMAN N - BEHRENS - GOETZ ** PH tL- D1PL.-ING. GERHARD PULS EUROPEAN PATENT TATTORNEYS DR.-ING. DIETER BEHRENS DIPL.-ING .; DIPL.-TTIRTSCH.-ING. RUTf RT GOtT; LA-55 563 D-8000 MUNICH SCHWEIGERSTRASSE 2 telephone: (089) 662051 telegram: protectpatent telex: 514070 patent claims: 1. j Hydraulic brake system with anti-lock device Vehicles in which a modulator is dependent on a blocking signal sent by a device for determining is generated by locking states of the wheel when braking at a locking point by allowing brake fluid to flow back relieves a braked wheel from the brake actuation pressure from the wheel brake, characterized in that the modulator (3) a permanent connection between a master cylinder (1) for actuating the wheel brake (2) and a Manufactures the brake line to the wheel brake (2) itself, a displacement piston (40; 88), which works in a bore (41; 87) in a housing (4; 81), in two opposite ones Direction is movable, whereby brake fluid from the brake line through its movement in the first direction a first check valve (71; 121) sucked through into a displacement chamber (42; 89) and a throttle device (34; valve body 105, recess 109) is switched on between the master cylinder (l) and the brake line, and by its movement in the second direction, brake fluid from the displacement chamber (42; 89) through a to the master cylinder (1) leading second check valve (72; 120) is ejected through, and that a power source (pump 46, accumulator 49) is provided which has a support chamber (43; Chambers 83,84) is able to put under pressure, thereby normally the displacement piston (40; 88) in an advanced / 2 - 2-- 55 • β · · To hold the position that determines the path around which the displacement piston (40; 88) can be adjusted in the second direction, and in which the effective volume of the displacement chamber (42; 89) is smallest, with a change in the Pressure in the support chamber (43; 83,84) due to the blocking signal allows the displacement piston (40; 88) to move in the first direction, and the pressure in the support chamber (43; 83, 84) increases when the blocking signal is terminated changes again and moves the displacement piston (40; 88) in the second direction. 2. Brake system according to claim 1, characterized in that the throttle device (-34; 105,109) is switched off when the brake pressure is approximately equal to the pressure supplied by the master cylinder (l). 3. Brake system according to claim 1 or 2, characterized in that the power source is a hydraulic Source of power is. 4. Brake system according to one of claims 1 to 3, characterized characterized in that the displacement piston (40) separates the fluid used in the power source from that in the brake system used fluid separates. 5. Brake system according to one of claims 1 to 4, characterized characterized in that the power source comes from a hydraulic pump (46) and / or a hydraulic accumulator (49) is formed for the power steering or the suspension of the vehicle. 6. Brake system according to one of claims 1 to 5, characterized in that the displacement piston (40) is formed by a differential piston that is able to generate pressures in the brake system that are higher than those in - 3 - 55 the pressures prevailing in the support chamber (43), and thereby acts as a pressure booster. 7. Brake system according to claim 1 or 2, characterized in that the power source is a pneumatic Source of power is. 8. A brake system according to claim 7, characterized geke η η- _~: characterized in that the power source is formed by suction force from the suction pipe of a vehicle engine. 9. Brake system according to claim 7, characterized in that it is characterized that the power source is compressed air. 10. Brake system according to one of claims 1 to 9, characterized in that the brake fluid from the master cylinder (1) of the brake line through a first flow control valve (6) which has a first throttle device (Valve body 17, groove 20), and the fluid from the power source (46,49) of the support chamber (43) through a second flow control valve (44) having a second throttle device (64) can be fed through. 11. Brake system according to one of claims 1 to 9, characterized in that the modulator (3) has a Wall (piston 82) which is movable in a housing (81), this into a first and a second chamber (84, 83) divided and cooperates with the displacement piston (88) to the wheel brake through a flow control valve (91) applied pressure counteract, the power source normally one of the chambers (84) a corresponding Fluid pressure supplies, which holds the wall (82) in a rest position, in which the displacement piston (88) in the corresponding, advanced position is held, and both chambers (84, 83) when a blocking signal occurs - 4 -. 55 563 • · «« te are connected to one another, -i / obei the wall (82) in can move a working position and the displacement piston (88) withdraws together with this movement and thereby the effective volume of the displacement chamber (89) is increased, after which only the above-mentioned when the blocking signal is extinguished a chamber (84) is connected to the power source. 12. Brake system according to claim ill, characterized in that g e k e η η that the power source is compressed air, which acts in the first chamber (84), and the second chamber (83) is normally connected to the atmosphere, the chambers (83, 84) with each other in the event of a blocking signal are connected and when the blocking signal ends, the compressed air from the second chamber (83) to the atmosphere is delivered. '-' 13. Brake system according to claim 11, characterized in that g e k e η η that the power source is a vacuum and the first chamber (84) normally with normal brake application is connected to the atmosphere, the second chamber (83) before and after airT'BvLockiersignal to negative pressure is connected, but is connected to the first chamber (84) ■ while a blocking signal is present. 14. Brake system according to one of claims 10 to 13, characterized in that the connection between the two chambers (83, 84) is controlled by an electromagnetically operated valve (92) whose electromagnet (93) is excited depending on the blocking signal in order to establish the connection between the two chambers (83,84). 15. Brake system according to claim 11, characterized in that the power source is under pressure is hydraulic fluid, the second chamber (83) normally during normal brake application and after a - 5 - 5Γ> 563 Blocking signal connected to a container for fluid is and the first chamber (84) is always connected to the pressure source. 16. Brake system according to one of claims 1 to 10, characterized in that the fluid pressure from the Power source (46,49) is supplied to that end face of the displacement piston (40) which is the displacement chamber (42) faces away and forms at least part of the support chamber (43), an electromagnetically actuated Pressure relief valve (5) a normally closed connecting line (53) between the support chamber (43) and a never pressure container (47) controls. 17. Brake system according to one of claims 1 to 16, characterized in that a direction to regular monitoring of the deceleration of the braked wheel is provided and the locking signal is generated after it is first generated is deleted when the deceleration of the wheel has decreased over two successive scans