WO1999022977A1 - Servofrein pneumatique a actionnement mecanique et electromagnetique - Google Patents

Servofrein pneumatique a actionnement mecanique et electromagnetique Download PDF

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Publication number
WO1999022977A1
WO1999022977A1 PCT/EP1998/006944 EP9806944W WO9922977A1 WO 1999022977 A1 WO1999022977 A1 WO 1999022977A1 EP 9806944 W EP9806944 W EP 9806944W WO 9922977 A1 WO9922977 A1 WO 9922977A1
Authority
WO
WIPO (PCT)
Prior art keywords
housing
brake booster
control valve
armature
electromagnet arrangement
Prior art date
Application number
PCT/EP1998/006944
Other languages
German (de)
English (en)
Inventor
Heinrich Plewnia
Original Assignee
Lucas Industries Public Limited Company
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 Lucas Industries Public Limited Company filed Critical Lucas Industries Public Limited Company
Publication of WO1999022977A1 publication Critical patent/WO1999022977A1/fr

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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
    • B60T13/66—Electrical control in fluid-pressure brake systems
    • B60T13/72—Electrical control in fluid-pressure brake systems in vacuum systems or vacuum booster units

Definitions

  • the present invention relates to a pneumatic brake booster according to the preamble of claim 1.
  • a brake booster is known for example from DE 196 11 555 AI.
  • Brake boosters of the aforementioned type are on the one hand directly mechanically operable in a conventional manner, for example by stepping on a brake pedal coupled to the input element of the brake booster, and on the other hand they can be actuated by an integrated electromagnetic actuator which is usually operated outside of the Brake booster arranged electronic control unit can be controlled.
  • these brake boosters also allow automatic actuation that is independent of the driver's will as well as a combination of the two types of actuation, i.e. an automatic actuation of the brake booster (so-called brake assist function) overlaid on the driver's will.
  • the invention is therefore based on the object of providing a pneumatic brake booster with additional electromagnetic actuation, in which the servo force generated as part of an electromagnetic actuation is dependent on the current intensity with which the electromagnetic actuator is actuated.
  • the force is introduced into the electromagnet arrangement against the direction of the magnetic force.
  • the force required to actuate the electromagnet arrangement is thus essentially dependent on the pressure difference currently acting on the movable wall, so that a certain current value is associated with a certain pressure difference and thus with a certain servo force.
  • This has the advantage that e.g. in the case of automatic braking in accordance with the desired braking intensity, only a certain associated current value for controlling the
  • Electromagnet arrangement must be adjusted. Are advantageous the current values assigned to the specific braking intensities are stored in a characteristic diagram.
  • the electromagnet arrangement according to the invention is, due to its clamping between two pressure pads, a robust and yet sensitive actuator.
  • the housing of the electromagnet arrangement is the part which can be freely displaced in and relative to the control valve housing.
  • the coil is housed.
  • the coil concentrically surrounds the armature of the electromagnet arrangement.
  • the coil and the housing are fastened, for example, to an actuating piston and the armature, which in this embodiment represents the part which can be freely moved in and relative to the control valve housing, surrounds the coil concentrically.
  • the mechanical input member acts on an actuating piston on which a first valve seat for connecting the working chamber is formed with at least atmospheric pressure.
  • a second valve seat that connects the working chamber to the vacuum chamber.
  • a first and a second valve member, which cooperates with the first valve seat and with the second valve seat, are mechanically rigidly coupled in this embodiment, so that a displacement of the first valve member causes a corresponding, synchronous displacement of the second valve member and vice versa.
  • the housing of the electromagnet arrangement represents the part that is freely displaceable in and relative to the control valve housing
  • a second valve seat or the second valve seat for connecting the Working chamber formed with the vacuum chamber on the housing of the electromagnet assembly.
  • first and second valve members are preferably rigidly coupled to one another by an essentially hollow cylindrical connecting element.
  • a hollow cylindrical connecting element enables large valve cross sections and, as a result, a large air throughput, as a result of which the response behavior of the brake booster is improved.
  • the hollow cylindrical connecting element has at one end a radially inward flange which carries the first valve member and at its opposite other end a radially outward flange which carries the second valve member. If they consist of elastic material, the valve members can be vulcanized onto the flanges, for example.
  • a compression spring which is supported on the actuating piston and on the inside on the hollow cylindrical connecting element pretensions both the first valve seat in the direction of the first valve member and the second valve member in the direction of the second valve seat.
  • a metal bellows acting as a compression spring is hermetically sealed between the armature and an armature counterpart belonging to the housing of the electromagnet arrangement.
  • the metal bellows functions as a spring which pushes the housing of the electromagnet arrangement back into the unactuated state.
  • a metal bellows acting as a tension spring is arranged between the armature and a coil cover belonging to the housing of the electromagnet arrangement in a hermetically sealing manner.
  • the metal bellows functions as a spring which retracts the housing of the electromagnet arrangement into the unactuated state.
  • a metal bellows is hermetically sealed between the actuating piston and a coil cover belonging to the housing of the electromagnet arrangement.
  • the metal bellows can act either as a tension or as a compression spring.
  • a rubber-elastic bellows is arranged between an armature counterpart belonging to the housing of the electromagnet arrangement and an end section of the control valve housing located on the force output side of the control valve housing to seal the actuating piston from the vacuum chamber in a hermetically sealing manner.
  • hermetically sealing it is meant here that the sealing must above all be gas-tight. This can be achieved in many ways, for example the bellows ends can be pressed against corresponding sealing surfaces by means of suitable spring elements. However, it is also conceivable that the bellows ends are screwed in a sealing manner or even integrally, that is for example by soldering, welding or gluing. In addition to a gas-tight seal, it is particularly important that the stroke length of the bellows used is at least as long as the actuation stroke of the electromagnet arrangement.
  • the actuating piston is rigidly coupled to the armature of the electromagnet arrangement.
  • the armature is preferably screwed airtight to the actuating piston.
  • the armature is rigidly coupled to an end section of the control valve housing located on the force output side of the control valve.
  • Fig. 5 a slightly modified compared to Fig. 4, fifth embodiment in longitudinal section, and
  • Fig. 6 shows a sixth embodiment similar to the embodiment shown in Fig. 1.
  • FIG. 1 and in addition FIG. 6 show a vacuum brake booster with an amplifier housing 10, a small part of which is shown in FIG. 6.
  • the amplifier housing 10 which is usually formed from two sheet metal half-shells, delimits an interior space, which is divided into a vacuum chamber 14 and a working chamber 16 by at least one movable wall.
  • a control valve 18 projects into the amplifier housing 10 along a central longitudinal axis A for controlling a pneumatic pressure difference acting on the movable wall 12.
  • the control valve 18 has a control valve housing 20 and, as can be seen from FIG. 6, is displaceable and sealing in an axially outwardly projecting, cylindrical neck of the booster housing 10 added.
  • the movable wall 12 is fastened in a sealing and force-transmitting manner to a circumferential radial flange 22 of the control valve housing 20.
  • a return spring 23 biases the control valve housing 20 together with the movable wall 12 into the starting position shown.
  • the control valve 18 and thus the brake booster can be actuated with a mechanical input member 24 projecting axially into the control valve housing 20, which acts in the control valve 18 on an actuating piston 26 and whose other end is connected, for example, to a brake pedal, not shown here.
  • the actuating piston 26 passes through the entire control valve housing 20 and transmits the actuating force introduced by the input member 24 to a so-called
  • Sensing disk 28 which is received in an end section 30 of the control valve housing 20 on the force output side.
  • the sensing disk 28 in turn acts on a rubber-elastic reaction disk 32 of larger diameter, which is also accommodated in the end section 30 and which transmits the actuating force to an input piston 34 of a hydraulic master cylinder, not shown here, which is attached to the vacuum-side booster half.
  • a first valve seat 36 is formed on the actuating piston 26, which cooperates with a first valve member 38 and which, in the open state, connects the working chamber 16 to atmospheric pressure (or overpressure) via a radial channel 40, which pressure is brought into the control valve from the outside by an air filter element 42. can flow into the housing 20.
  • a transverse bolt 44 which is attached to the actuating piston 26 and which, when the control valve 18 is actuated, limits the axial relative movement of the actuating piston 26 with respect to the control valve housing 20 by coming into contact with the left side wall of the channel 40 in the figures and which a return movement of the actuating piston 26 at the end of a braking operation against one in the booster housing wall.
  • formed stop 46 which defines the so-called release position (unactuated position) of the brake booster.
  • the control valve 18 has an electromagnet arrangement 48 which is accommodated in a step-widened part of the control valve housing 20 and which has an armature 50, a housing formed from an armature counterpart 52 and a coil cover 54 and a housing accommodated therein. comprises a coil 58 carried by a coil holder 56, which surrounds the armature 50 in a ring.
  • the electromagnet arrangement 48 is arranged coaxially with the actuating piston 26 and is penetrated by the latter.
  • the actuating piston 26 is rigidly coupled to the armature 50 by means of a gas-tight screw connection 60.
  • a thin-walled separating sleeve 62 made of non-magnetic material, on the inner surface of which the armature 50 can slide axially supported by a slide ring 64.
  • a second annular valve seat 66 is formed on the outside, which cooperates with a second valve member 68 and, in the open state, connects the vacuum chamber 14 to the working chamber 16 via an annular channel 70.
  • the first valve member 38 and the second valve member 68 are carried by a substantially hollow cylindrical connecting element 72, which for this purpose has a radially inwardly extending flange 74 on which the rubber-elastic, first valve member 38 is vulcanized, and on its opposite, the other end has a radially outwardly extending flange 76 onto which the rubber-elastic, second valve member 68 is vulcanized.
  • the wall of the connecting element 72 has openings for the cross bar 44 and the air flowing to the working chamber 16.
  • the hollow cylindrical connecting element 72 rigidly couples the two valve members 38 and 68 with each other so that a movement of the second valve member 68 is synchronously transmitted to the first valve member 38 and vice versa.
  • the first valve member 38 is provided with an integrally molded rubber-elastic bellows 78, the free edge of which is thickened and is sealingly clamped between an inwardly projecting projection of the control valve housing 20 and an air guide insert 80.
  • the second valve member 68 is also provided with a one-piece, rubber-elastic bellows 82, the thickened free edge of which is tightly clamped between the control valve housing 20 and an insert 84.
  • this arrangement is chosen such that pressure balance is achieved with respect to each valve 36, 38 and 66, 68, i.e. there are no force components resulting from the different pressure in the vacuum chamber 14 or the working chamber 16 acting on the valve members 38, 68.
  • a compression spring 86 supported on the actuating piston 26 and on an inner projection of the connecting element 72 prestresses both the first valve seat 36 in the direction of the first valve member 38 and the second valve member 68 in the direction of the second valve seat 66.
  • Another compression spring 88 which is supported at one end on the air guide insert 80 and at the other end on the mechanical input member 24, biases the input member 24 against the direction of actuation.
  • Electromagnetic actuation of the control valve 18 proceeds as follows: starting from FIG. 1, in which the electromagnet arrangement 48 is biased by the compression spring 86 against the end section 30 of the control valve housing 20, the coil 58 is energized. A force field then arises between the armature 50 and the armature counterpart 52. Since the anchor 50 with the
  • Actuating piston 26 is rigidly connected, after overcoming the pretensioning force of the compression spring 86, the coil 58 together with the armature counterpart 52 and the coil cover 54 begins to move to the right, that is, counter to the pedal actuation direction.
  • the second valve seat 66 formed on the coil cover 54 displaces the second valve member 68 and, via the connecting element 72, also the first valve member 38 right, whereupon the latter lifts off the first valve seat 36.
  • the connection between the working chamber 16 and the atmospheric pressure is thus opened and air can flow into the working chamber 16 as described above. This state is shown in Fig. La. It should be noted here that this
  • Condition can be achieved both without a brake pedal actuation and superimposed on a brake pedal actuation.
  • Electromagnet arrangement 48 more precisely the armature counterpart 52, the pressure prevailing in the vacuum chamber 14, while on the opposite end face of the electromagnet arrangement 48, more precisely the coil cover 54, the pressure currently prevailing in the working chamber 16 acts.
  • the effective area on which the pressure of the vacuum chamber 14 acts is designated i, while the effective area on which the pressure of the working chamber 16 acts is designated W 2 .
  • Both effective surfaces W ⁇ _ and W 2 are limited radially on the outside by the diameter of the second valve seat 66 and radially on the inside essentially by the diameter of the actuating piston 26, more precisely by the effective diameter of a metal bellows 90 described below.
  • the axially displaceable actuating piston 26 must be hermetically sealed with respect to the working chamber 16. 1, this is achieved by a hollow cylindrical metal bellows 90 which coaxially surrounds the actuating piston 26 within the electromagnet arrangement 48 and one end of which is sealingly connected to the armature 50 and the other end of which is sealingly connected to the armature counterpart 52.
  • the metal bellows 90 acts as a compression spring which prestresses the housing of the electromagnet arrangement 48 consisting of armature counterpart 52 and coil cover 54 into the starting position shown in FIG. 1.
  • connection between the vacuum chamber 14 and the working chamber 16 is thus open and the pressure difference, which is also present on the movable wall 12, falls until it becomes clear a new force equilibrium is set, upon reaching which the second valve seat 66 again seals against the second valve member 68. In this way, the servo force generated by the brake booster can either be raised or lowered.
  • a hollow cylindrical metal bellows 90 ' is hermetically fastened at one end to the armature 50, while at the other end there is a radially outwardly extending, annular flange section 92, which has an axially directed collar the coil cover 54 is hermetically sealed.
  • the metal bellows 90 ′ acts like a tension spring that pulls the housing of the electromagnet arrangement 48 back into the starting position.
  • a metal bellows 90 "having a frustoconical cross-section is attached gas-tight at one end to the coil cover 54 and at its other end in a groove 94 of the actuating piston 26.
  • the third exemplary embodiment also acts analogously to the first exemplary embodiment the metal bellows 90 "as a compression spring which resets the housing of the electromagnet arrangement 48.
  • the exemplary embodiments according to FIGS. 2 and 3 have the advantage that the moving parts of the electromagnet arrangement 48 are hermetically sealed from the air flow between the working chamber 16 and the Atmosphere are separated. As a result, the sliding surfaces are reliably protected against any kind of contamination, which benefits the service life.
  • the sealing is performed by a rubber-elastic bellows 96, which is pressed by a compression spring 98 both in sealing contact with the end section 30 of the control valve housing 20 and with the armature counterpart 52.
  • a correspondingly stronger compression spring 100 is provided, which is supported in the control valve housing 20 between the insert 84 and the coil cover 54.
  • the fifth embodiment shown in FIG. 5 differs from the fourth embodiment only in the arrangement of the compression spring which counteracts the compression spring 98. 5, a compression spring 100 'is arranged at approximately the point at which the metal bellows 90 is located in the first exemplary embodiment.
  • the sixth exemplary embodiment shown in FIG. 6 essentially corresponds to the exemplary embodiment according to FIG. 1.
  • the armature 50 is, however, by means of a
  • Screw connection 102 rigidly coupled to the end section 30 of the control valve housing 20.
  • means are present which prevent the full-surface contact of the armature counterpart 52 on the end section 30 of the control valve housing 20.
  • This can be be ten-shaped elevations 104 (see FIGS. 1, 2, 3 and 6) or spacer pins 106 (see FIGS. 4 and 5), which at the same time prevent the bellows 96 from being destroyed by excessive compression thereof.
  • the above-mentioned spacing means primarily ensure that the pressure of the vacuum chamber 14 can act freely on the active surface W 2 . In addition, they prevent magnetic "sticking" of the armature counterpart 52 to the end section 30 of the control valve housing 20.

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

Abstract

L'invention concerne un servofrein pneumatique comportant un corps (10) dont l'espace intérieur est divisé, par au moins une paroi mobile (12), en une chambre à dépression (14) et en une chambre de travail (16). Une soupape de commande (18) fait saillie, le long d'un axe (A), dans le corps (10) et régule une pression différentielle pneumatique agissant sur la paroi mobile (12). Cette soupape de commande (18) possède une cage (20) avec laquelle la paroi mobile (12) est reliée de manière à transmettre une force. La soupape de commande (18) peut être actionnée d'une part par un organe d'entrée mécanique (24) et d'autre part par un système électromagnétique (48), indépendamment l'un de l'autre. Le corps (52, 54) du système électromagnétique (48) se déplace axialement dans la cage de soupape (20) et présente une première surface active (W1) située perpendiculairement par rapport à l'axe (A) et soumise, en service, à la pression régnant dans la chambre à dépression (14), ainsi qu'une deuxième surface active (W2) située également perpendiculairement par rapport à l'axe (A) et faisant face à la première surface active (W1), cette deuxième surface active étant soumise en service à la pression régnant dans la chambre de travail (16). On obtient ainsi une rétroaction, sur le système électromagnétique (48), de la pression différentielle existant au niveau de la paroi mobile (12), ce qui permet d'associer à chaque courant d'attaque une pression différentielle définie.
PCT/EP1998/006944 1997-11-04 1998-11-03 Servofrein pneumatique a actionnement mecanique et electromagnetique WO1999022977A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE1997148657 DE19748657A1 (de) 1997-11-04 1997-11-04 Pneumatischer Bremskraftverstärker mit mechanischer und elektromagnetischer Betätigung
DE19748657.6 1997-11-04

Publications (1)

Publication Number Publication Date
WO1999022977A1 true WO1999022977A1 (fr) 1999-05-14

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Application Number Title Priority Date Filing Date
PCT/EP1998/006944 WO1999022977A1 (fr) 1997-11-04 1998-11-03 Servofrein pneumatique a actionnement mecanique et electromagnetique

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DE (1) DE19748657A1 (fr)
WO (1) WO1999022977A1 (fr)

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP4529105B2 (ja) * 2000-03-31 2010-08-25 日立オートモティブシステムズ株式会社 ブレーキ倍力装置

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1994011226A1 (fr) * 1992-11-13 1994-05-26 Itt Automotive Europe Gmbh Systeme d'assistance de freinage a depression
DE19541535A1 (de) * 1995-11-08 1997-05-15 Teves Gmbh Alfred Verfahren zum Betrieb eines pneumatischen Bremskraftverstärkers
DE19612952A1 (de) * 1996-04-01 1997-10-02 Lucas Ind Plc Elektronisch gesteuerter Bremskraftverstärker
DE19624376A1 (de) * 1996-06-19 1998-01-02 Teves Gmbh Alfred Bremsanlage für Kraftfahrzeuge
DE19648597A1 (de) * 1996-11-23 1998-05-28 Teves Gmbh Alfred Unterdruckbremskraftverstärker

Family Cites Families (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE4337361A1 (de) * 1993-11-02 1995-05-04 Lucas Ind Plc Pneumatischer Bremskraftverstärker
JP3530987B2 (ja) * 1995-06-22 2004-05-24 アイシン精機株式会社 真空倍力装置
DE19611555A1 (de) * 1996-03-23 1997-09-25 Teves Gmbh Alfred Pneumatischer Bremskraftverstärker
DE19617277A1 (de) * 1996-04-30 1997-11-06 Teves Gmbh Alfred Pneumatischer Bremskraftverstärker

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1994011226A1 (fr) * 1992-11-13 1994-05-26 Itt Automotive Europe Gmbh Systeme d'assistance de freinage a depression
DE19541535A1 (de) * 1995-11-08 1997-05-15 Teves Gmbh Alfred Verfahren zum Betrieb eines pneumatischen Bremskraftverstärkers
DE19612952A1 (de) * 1996-04-01 1997-10-02 Lucas Ind Plc Elektronisch gesteuerter Bremskraftverstärker
DE19624376A1 (de) * 1996-06-19 1998-01-02 Teves Gmbh Alfred Bremsanlage für Kraftfahrzeuge
DE19648597A1 (de) * 1996-11-23 1998-05-28 Teves Gmbh Alfred Unterdruckbremskraftverstärker

Also Published As

Publication number Publication date
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