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WO1997038884A1 - Servofrein hydraulique - Google Patents

Servofrein hydraulique Download PDF

Info

Publication number
WO1997038884A1
WO1997038884A1 PCT/EP1997/001634 EP9701634W WO9738884A1 WO 1997038884 A1 WO1997038884 A1 WO 1997038884A1 EP 9701634 W EP9701634 W EP 9701634W WO 9738884 A1 WO9738884 A1 WO 9738884A1
Authority
WO
WIPO (PCT)
Prior art keywords
piston
pressure
valve
valve body
booster
Prior art date
Application number
PCT/EP1997/001634
Other languages
German (de)
English (en)
Inventor
Rainer Seeger
Werner Volkmar
Bernd SCHÜTT
Original Assignee
Itt Manufacturing Enterprises, Inc.
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Itt Manufacturing Enterprises, Inc. filed Critical Itt Manufacturing Enterprises, Inc.
Publication of WO1997038884A1 publication Critical patent/WO1997038884A1/fr

Links

Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60T—VEHICLE BRAKE CONTROL SYSTEMS OR PARTS THEREOF; BRAKE CONTROL SYSTEMS OR PARTS THEREOF, IN GENERAL; ARRANGEMENT OF BRAKING ELEMENTS ON VEHICLES IN GENERAL; PORTABLE DEVICES FOR PREVENTING UNWANTED MOVEMENT OF VEHICLES; VEHICLE MODIFICATIONS TO FACILITATE COOLING OF BRAKES
    • B60T13/00—Transmitting braking action from initiating means to ultimate brake actuator with power assistance or drive; Brake systems incorporating such transmitting means, e.g. air-pressure brake systems
    • B60T13/10—Transmitting braking action from initiating means to ultimate brake actuator with power assistance or drive; Brake systems incorporating such transmitting means, e.g. air-pressure brake systems with fluid assistance, drive, or release
    • B60T13/12—Transmitting braking action from initiating means to ultimate brake actuator with power assistance or drive; Brake systems incorporating such transmitting means, e.g. air-pressure brake systems with fluid assistance, drive, or release the fluid being liquid
    • B60T13/16—Transmitting braking action from initiating means to ultimate brake actuator with power assistance or drive; Brake systems incorporating such transmitting means, e.g. air-pressure brake systems with fluid assistance, drive, or release the fluid being liquid using pumps directly, i.e. without interposition of accumulators or reservoirs
    • B60T13/161—Systems with master cylinder
    • B60T13/162—Master cylinder mechanically coupled with booster
    • B60T13/163—Pilot valve provided inside booster piston
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60T—VEHICLE BRAKE CONTROL SYSTEMS OR PARTS THEREOF; BRAKE CONTROL SYSTEMS OR PARTS THEREOF, IN GENERAL; ARRANGEMENT OF BRAKING ELEMENTS ON VEHICLES IN GENERAL; PORTABLE DEVICES FOR PREVENTING UNWANTED MOVEMENT OF VEHICLES; VEHICLE MODIFICATIONS TO FACILITATE COOLING OF BRAKES
    • B60T13/00—Transmitting braking action from initiating means to ultimate brake actuator with power assistance or drive; Brake systems incorporating such transmitting means, e.g. air-pressure brake systems
    • B60T13/10—Transmitting braking action from initiating means to ultimate brake actuator with power assistance or drive; Brake systems incorporating such transmitting means, e.g. air-pressure brake systems with fluid assistance, drive, or release
    • B60T13/12—Transmitting braking action from initiating means to ultimate brake actuator with power assistance or drive; Brake systems incorporating such transmitting means, e.g. air-pressure brake systems with fluid assistance, drive, or release the fluid being liquid
    • B60T13/14—Transmitting braking action from initiating means to ultimate brake actuator with power assistance or drive; Brake systems incorporating such transmitting means, e.g. air-pressure brake systems with fluid assistance, drive, or release the fluid being liquid using accumulators or reservoirs fed by pumps
    • B60T13/142—Systems with master cylinder
    • B60T13/143—Master cylinder mechanically coupled with booster
    • B60T13/144—Pilot valve provided inside booster piston

Definitions

  • the invention relates to a hydraulic amplifier, in particular for motor vehicle brake systems according to the preamble of patent claim 1.
  • a hydraulic power booster has already become known, which in its design as a so-called tube booster has a booster piston in the booster housing, which, via a valve body acting as a seat valve, introduces the pressure of an energy supply into a pressure chamber receiving the booster piston, provided that the actuating piston is under force.
  • the pressure chamber In the pedal release position, the pressure chamber is connected to an atmospheric container connection without pressure.
  • this amplifier which is provided with a ball valve, there is noise as a result of the axial play of the ball or even reactions on the pedal as a result of a pressure pulsation in the energy supply.
  • a hydraulic power booster which is also designed as a tube booster and carries out the pressure medium control in the direction of the surface to be acted upon on the booster piston by means of a slide valve.
  • the pressure of the energy supply is not sent directly to the slide valve, but is preset by means of a pressure reducing and pressure limiting valve.
  • the use of a slide valve requires tight fit play to be observed, which increases the cost of manufacturing the power amplifier. It is therefore the object of the invention to improve a hydraulic amplifier of the type mentioned at the outset such that an inexpensive, universally usable and comfortably operable power amplifier can be produced using simple, functionally reliable means.
  • FIG. 1 is an overall view of the power amplifier according to the invention in longitudinal section
  • FIG. 2 shows an enlarged partial section of essential features of the power amplifier according to FIG. 1.
  • Fig. 1 shows the structure of the hydraulic amplifier, consisting of an amplifier housing 1, with the adaptation of a master cylinder la, a mounting flange lb, a container connection lc, with a connection for a power supply ld and the adaptation of a step valve le. Furthermore, the illustration shows a pressure reducing valve 2, which is inserted obliquely to the longitudinal axis into the valve housing 1 and to which the energy supply ld (pump-storage unit) is connected.
  • An actuating unit 4 inserted as a cartridge insert into the amplifier housing 1 in the longitudinal direction consists of a hollow actuating piston 4a, which has a regulating piston 4b and a valve seat 4c attached to the actuating piston 4a.
  • booster piston 4d between the rear Housing receptacle 4e of the actuating unit 4 and the push rod 5 slipped over the actuating piston 4a. All of the above-mentioned parts of the actuation unit 4 are aligned coaxially with one another and, as it were, nested with one another.
  • the push rod 5 has a return spring 5a and a spring bearing 5b, which is held in the region of the master cylinder flange. These parts are also in a coaxial arrangement with respect to the actuation unit 4, which structurally fulfills the features of a so-called tube amplifier.
  • step valve 6 with a valve housing 6a, a step piston 6b located therein, a cover 6c, a screw 6d and a sealing plate 6e for flanging the step valve 6 onto the booster housing 1.
  • Two stage valves 6 are flanged to the booster housing 1 in a twin arrangement for a two-circuit brake system.
  • These step valves 6 are a significantly simplified and less expensive version of the changeover valve described in DE 40 32 206 AI, which has been expanded to include an essential function. This expansion of functions includes the division of the brake fluid volume per circuit into a so-called application volume and a so-called pressure increase volume, which is necessary for the legally required minimum braking in the event of an amplifier failure.
  • the accumulator pressure is applied via a connection for the energy supply ld on the input side (area difference of the surfaces 166-165) of the pressure reducing valve 2, which works as a pressure limiter in this functional position and the accumulator pressure on the Output side 52 of the pressure reducing valve 2 limited to a fixed value.
  • the accumulator pressure becomes the reduced accumulator pressure, which passes through the inclined housing bore 53 into the annular space 54 of the receptacle 4e and from there through the channel bores 55 into the annular space 56 of the actuating piston bore. This bore is smaller on the reinforcement side in the guide area of the actuating piston 4a than on the opposite side in the area of the pedal rod.
  • the diameter of the actuating piston 4a is up to its annular groove 9 smaller than at the outwardly sealed end section of the actuating piston 4a.
  • the reduced pressure passes from the annular space 56 into the annular groove 9 and from there into the bores 10, 11 of the actuating piston 4a into the control piston space 4f, through the piston bore 12 and past the valve body clamping into the pressure control space 112.
  • the valve body 13 has this Task to seal the reduced storage pressure at valve seat 4c. All other wet rooms in the amplifier housing 1, in the stepped valve 6 and in the master cylinder la are depressurized during this sealing effect and connected to an expansion tank (tank connection lc).
  • the end position of the actuating piston 4a in the release position is defined as follows: Due to the unevenly large diameter on the actuating piston 4a, there is an area difference (annular surface) which is acted upon by the reduced storage pressure and which results in a force component against the pedal input force direction. This force component is directly proportional to the hydraulic pressure applied.
  • the hydraulic pressure is constant (static) in the release position of the amplifier due to the pressure limitation value defined in the pressure reducing valve 2, in the braking position the hydraulic pressure on the actuating piston 4a increases (dynamic) due to the regulated hydraulic pressure.
  • the reduced accumulator pressure not only reaches the regulating piston 4b, but one is created Hydraulic restoring action on the actuating piston 4a opposite to the direction of the input force, which caused it to come to a stop via the collar 15 of the valve seat 4c axially secured in the actuating piston 4a via the end faces of the booster piston 4d on the end face of the receptacle 4e.
  • the receptacle 4e is fixed in position by a locking ring in the amplifier housing 1.
  • the actuation unit 4 has a valve seat 4c, a valve body 13 with a control piston 4b and a compression spring 33, which is supported on the actuation piston 4a. As already mentioned at the beginning, all parts are arranged coaxially in the actuating piston 4a.
  • the valve body 13 and the valve seat 4c form a ball-sealing-seat control element combination. To open such a hydraulically pressurized combination, an actuating force corresponding to the pressurized area times the feed pressure is necessary, that is, a high path-independent force increase with design of these control elements in accordance with the volume throughput.
  • the actuating unit 4 compensates for all static and dynamic influences by functional combination of the valve body 13 with a stepped control piston 4b. This is done in that the reduced storage pressure is present through a central bore 12 on both sides of the control piston 4b.
  • the surface difference of the piston surfaces 70 and 80 corresponds to a correction factor of the pressurized surface 90 of the Valve body 13 so that the forces are balanced in total.
  • the force required to lift the valve body 13 at the start of the actuation is determined only by the friction of the sealing elements on the control piston 4b and the design of the compression spring 33. In the dynamic range and thus during the hydraulic pressure control, this balance is not disturbed by a force resulting from the regulated accumulator pressure on the surface 90 and not by flow-related influences, since the annular surface 100 of the control piston 4b through bores 110 with the regulated hydraulic pressure in the pressure chamber 112 is connected. Since the annular surface 100 corresponds to the surface 90 and since the regulated pressure on the surface 90 and on the annular surface 100 is the same, the pressure-related influences and the flow-related influences neutralize. They become a constant variable, which is inversely proportional to the opening gap of the actuators.
  • the booster piston 4d which coaxially surrounds the actuating piston 4a.
  • the push rod 5 is a separate component which is guided centered on the amplifier side in the booster piston 4d without a fixed connection and seals the hydraulic pressure in the regulated pressure chamber 112 on the booster piston 4d with respect to the container connection 1c exposed to atmospheric pressure by means of sealing element 43.
  • On the master cylinder side the push rod 5 is mounted in the pressure piston by means of a spherical surface. This condition must be maintained if the amplifier is intact. This is particularly true in the start-up phase of the booster piston 4d, ie if the regulated hydraulic pressure has not yet reached the so-called start-up pressure and this also applies to a brake circuit failure of the upstream master cylinder la. To ensure this function, this module meets the following conditions: 1.
  • the sealed diameter on the push rod 5 is smaller than the master cylinder nominal diameter.
  • the spring force of the auxiliary spring 5a is greater than the force product of the push rod area and the starting pressure.
  • the frictional resistance of the seal 47 on the booster piston 4d is smaller than the product of the push rod ring surface 80 and the starting pressure.
  • Freewheel pressure is the pressure that must be built up to overcome all friction and spring forces in the booster piston / push rod functional unit.
  • the regulated storage pressure of the energy supply ld is missing or the reduced storage pressure or the regulated pressure become ineffective due to leakage.
  • actuating piston 4a pushes push rod 5 out of its bearing in booster piston 4d against auxiliary spring 5a.
  • the booster piston 4d remains in its current position, the seal between the regulated pressure chamber 112 and the container connection 1c for the atmospheric hydraulic supply is broken.
  • the push rod 5 slides on its centering ribs 110 in the housing bore.
  • the restoring force of the compression spring 5a is designed to a minimum for this emergency.
  • this also lacks the regulated accumulator pressure in the valve housing 6a, whereupon the brake pressure applied from the master cylinder la shifts the stepped piston 6b from a certain pressure level, and the hydraulic translation of the master cylinder pressure takes place in accordance with the specified parameter.
  • the input force acts on the actuation piston 4a via the pedal rod.
  • the entire actuating piston 4a is displaced by an empty travel, so that the ball of the valve body 13 tightly closes the valve bore 7 arranged in the push rod 5.
  • the collar 15 of the valve seat 4c lifts the same way from the end face of the booster piston 4a, the end face of the valve seat 4c is still a long way away from the opposite stop face in the push rod 5.
  • the actuating piston 4a moves further in the direction of the push rod 5, while the valve body 13 with the stepped piston is supported on the valve bore 7 via the ball and the Cannot follow the path of the actuating piston 4a.
  • the valve body sealing surface is thus lifted from the valve seat 4c free of free travel and reduced accumulator pressure can flow into the connected pressure chamber 112 along the annular gap between the actuating piston and the booster piston 4d.
  • a pressure builds up behind the booster piston 4d, which causes it to follow in the direction of movement of the actuating piston 4a.
  • the push rod 5 seated against the stop is also displaced with the valve bore 7 against the auxiliary spring 5a.
  • the valve body 13 supported on the valve bore 7 also follows and thus closes the gap between the valve body sealing surface and the valve seat again, thus ending the pressure build-up behind the booster piston 4d.
  • each increase in the regulated pressure via the piston surface 165 causes a brief displacement (opening) of the control elements 119, 120 of the pressure reducing valve 2 and thus an increase in the reduced storage pressure according to defined parameters.
  • the stepped piston 6b is pressed by the regulated pressure against a soft stop in the cover 6c and held there.
  • the pressure from the master cylinder la through the bore 123, 124 is passed unchanged through the bore 125 to the wheel cylinder.
  • the invention relates to a hydraulic amplifier (booster housing 1) arranged in series between the brake pedal and master brake cylinder la, which is actuated by the brake pedal by means of an actuating device 4 Foot strength proportionally increased according to the principle of hydraulic translation of surfaces.
  • the booster is preferably operated with brake fluid (monofluid), the container connection lc is provided in the connection area of the booster housing 1 to the master cylinder la and the booster piston 4d and the push rod 5 are separate components.
  • brake fluid monoofluid
  • a hydraulic return action on the actuating piston 4a is additionally used to return the actuating unit to the release position 4, which results from the area difference at the actuating piston 4a, acted upon by the reduced accumulator pressure, and which is approximately 60% of the total restoring force .
  • a further advantage with regard to the functional quality results from the arrangement of a hydraulically controlled pressure reducing valve 2, which reduces the storage pressure as required.
  • a functional expansion of the amplifier is ensured by a stepped valve 6 adapted to the amplifier housing 1 and controlled by the regulated accumulator pressure, as a result of which the main cylinder surface which is pressurized in effect is reduced in the event of an amplifier failure. Due to its design, the amplifier is therefore able to achieve a gain factor between 4.8 - 10.
  • valve housing 1 is suitable by a corresponding housing adaptation for the adaptation of master cylinders, which have previously been combined with vacuum boosters.
  • the design of the moving internal parts of the amplifier are geared towards the smallest possible diameter, friction, spring forces and number of moving parts To achieve the lowest possible input power losses in the event of amplifier failure.
  • the chosen design of the amplifier allows a fully automatic assembly. A relatively simple change in the amplification factor is achieved by replacing the booster piston 4d and adapting the receiving bore for the booster piston 4d. Because of the continuous bore of the housing and the short precision surfaces, the design is particularly easy to manufacture. Expensive precision control elements can be dispensed with using the selected 4-4e actuation unit.
  • the selected arrangement of the internal amplifier parts not only ensures a reduction in size, but also the permissible operating pressure can be increased.
  • the arrangement of the container connection 1c away from the booster piston 4d means that seals can be saved in the displacement path of the booster piston 4d, which reduces the friction.
  • the push rod 5 is a separate component, which is advantageously guided centered in the booster piston 4d without a fixed connection on the amplifier side and seals the hydraulic pressure in the regulated pressure chamber 112 against the booster piston 4d by means of a sealing element 43.

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  • Engineering & Computer Science (AREA)
  • Transportation (AREA)
  • Mechanical Engineering (AREA)
  • Braking Systems And Boosters (AREA)

Abstract

L'invention concerne un servofrein hydraulique, notamment pour systèmes de freinage d'automobiles, comportant au moins un piston de démultiplication (4d) monté dans un boîtier (1) de servofrein, qui est soumis à l'action d'un fluide provenant d'une alimentation en énergie (1d) par l'intermédiaire d'un corps de soupape (13) disposé dans le boîtier (1) de servofrein. En fonction de la position d'un piston d'actionnement (4a), le fluide provenant de l'alimentation en énergie (1d) parvient par l'intermédiaire du corps de soupape (13) dans une chambre de pression (112) contenant le piston de démultiplication (4d) ou bien la chambre de pression (112) communique sans pression avec un raccordement de récipient (1c). Le corps de soupape (13) est monté sur un piston de régulation (4b) étagé, guidé dans le piston d'actionnement (4a) de manière à se déplacer dans le sens axial. Un siège de soupape (4c) est fixé à l'extrémité du piston d'actionnement (4a) et son alésage est traversé par une partie saillante du corps de soupape (13), qui s'étend jusqu'à un alésage de soupape (7) pratiqué dans le piston de la tige de compression (5).
PCT/EP1997/001634 1996-04-16 1997-04-01 Servofrein hydraulique WO1997038884A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE19614909.6 1996-04-16
DE1996114909 DE19614909A1 (de) 1996-04-16 1996-04-16 Hydraulischer Verstärker

Publications (1)

Publication Number Publication Date
WO1997038884A1 true WO1997038884A1 (fr) 1997-10-23

Family

ID=7791370

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/EP1997/001634 WO1997038884A1 (fr) 1996-04-16 1997-04-01 Servofrein hydraulique

Country Status (2)

Country Link
DE (1) DE19614909A1 (fr)
WO (1) WO1997038884A1 (fr)

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2201213A1 (fr) * 1972-10-02 1974-04-26 Midland Ross Corp
US3889467A (en) * 1974-06-24 1975-06-17 Midland Ross Corp Accumulator arrangement for a booster brake mechanism
DE3737726A1 (de) * 1987-11-06 1989-05-18 Teves Gmbh Alfred Bremsdruckregelvorrichtung

Family Cites Families (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE3230791A1 (de) * 1982-04-15 1983-10-20 Alfred Teves Gmbh, 6000 Frankfurt Steuerventil fuer einen hydraulischen bremskraftverstaerker
DE3733863C2 (de) * 1987-10-07 1997-09-11 Teves Gmbh Alfred Hydraulischer Kraftverstärker, insbesondere zur Betätigung eines Hauptbremszylinders einer Fahrzeugbremsanlage
DE4015883C2 (de) * 1990-05-17 1998-10-15 Teves Gmbh Alfred Hydraulischer Kraftverstärker

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2201213A1 (fr) * 1972-10-02 1974-04-26 Midland Ross Corp
US3889467A (en) * 1974-06-24 1975-06-17 Midland Ross Corp Accumulator arrangement for a booster brake mechanism
DE3737726A1 (de) * 1987-11-06 1989-05-18 Teves Gmbh Alfred Bremsdruckregelvorrichtung

Also Published As

Publication number Publication date
DE19614909A1 (de) 1997-10-23

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