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WO1998014358A1 - Servofrein a depression - Google Patents

Servofrein a depression Download PDF

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Publication number
WO1998014358A1
WO1998014358A1 PCT/EP1997/005267 EP9705267W WO9814358A1 WO 1998014358 A1 WO1998014358 A1 WO 1998014358A1 EP 9705267 W EP9705267 W EP 9705267W WO 9814358 A1 WO9814358 A1 WO 9814358A1
Authority
WO
WIPO (PCT)
Prior art keywords
valve body
brake booster
valve
valve piston
booster according
Prior art date
Application number
PCT/EP1997/005267
Other languages
German (de)
English (en)
Inventor
Manfred Kahrs
Alfred Eckert
Thomas Berthold
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 WO1998014358A1 publication Critical patent/WO1998014358A1/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
    • B60T13/24—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 gaseous
    • B60T13/46—Vacuum systems
    • B60T13/52—Vacuum systems indirect, i.e. vacuum booster units
    • B60T13/573—Vacuum systems indirect, i.e. vacuum booster units characterised by reaction devices
    • 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
    • B60T13/24—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 gaseous
    • B60T13/46—Vacuum systems
    • B60T13/52—Vacuum systems indirect, i.e. vacuum booster units
    • B60T13/57—Vacuum systems indirect, i.e. vacuum booster units characterised by constructional features of control valves
    • 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 invention relates to a vacuum brake booster with electromagnetic auxiliary control, in particular for motor vehicle brake systems, with an amplifier housing, the interior of which is divided by a movable wall into a working chamber and a vacuum chamber, a control housing carrying the movable wall, which with the movable wall in the axial direction of the amplifier housing is movable and has a first sealing seat, a sealing body which is axially movably arranged in the control housing, a valve piston which is axially movably arranged in the control housing and can be actuated via an actuating rod, and a valve body which is axially movably arranged on the valve piston and which has a second sealing seat and is biased towards the sealing body, wherein the valve body can be moved away from the sealing body via the valve piston, an electromagnet provided in the control housing for displacing the valve body, the valve body also is movable independently of the valve piston via the electromagnet from the sealing body, and with a reaction disk made of elastic material, which is used to transmit the
  • Such a brake booster is known for example from DE 44 05 02 Cl.
  • the valve piston When moving the actuating rod connected to the brake pedal of a motor vehicle, the valve piston is moved forward and takes the valve body with it via a driver, so that its second valve seat detaches from the sealing body and ambient air flowing into the control housing can get into the working chamber from behind.
  • the vacuum chamber is separated from the working chamber because the sealing body is firmly attached to the first valve seat. This creates a pressure drop between the two chambers, which moves the movable wall together with the control housing and the push rod to the front.
  • the push rod transfers the force acting on it to the brake master cylinder of a brake system. Irrespective of the forward movement of the valve body mechanically caused by the piston, the latter can also be moved by the electromagnet.
  • the valve body acting as a magnet armature When the electromagnet is excited, the valve body acting as a magnet armature is pulled forward and opens or increases the flow cross section between the second sealing seat and the sealing body. In this way, a controlled pressure build-up can be achieved and, if necessary, the power output to the master brake cylinder can be accelerated and increased.
  • the reaction pressure which is made of elastic rubber material, is deformed by the control housing and flows into the valve piston as a result of the pressure force that arises. benraum. If the reaction disk touches the valve piston, the valve piston and with it the valve body with the second sealing seat are pushed back. At a certain pressure, this completely closes the flow cross section between the second sealing seat and the sealing body.
  • the main problem here is that the restoring force caused by the deformation of the reaction disk becomes so great that the electromagnet can no longer move the valve body from a certain pressure and thus can no longer open the second sealing seat.
  • a control valve can also be actuated by means of an electromagnet, independently of an actuating rod displacing a valve piston.
  • the electromagnet acts counter to the actuation direction of the actuation rod and actuates a third sealing seat, which enables ventilation of the working chamber.
  • the electromagnet is firmly connected to the valve piston and is displaceable in the control housing, so that the third sealing seat can be moved synchronously with the valve piston.
  • the object of the invention is to develop a generic brake booster in such a way that, even at high working pressure, targeted actuation of the second sealing seat by the electromagnet is made possible.
  • This object is essentially achieved with the invention in that devices are provided between the reaction disk and the valve body, by means of which a reaction force exerted on the valve body by the reaction disk in accordance with the pressure difference between the vacuum chamber and the working chamber compared with a restoring force when the valve piston is actuated the actuating rod acting restoring force is reduced and is transferred past the valve piston directly to the valve body.
  • the second sealing seat can be opened or kept open by the electromagnet even at a high working pressure without having to use an excessive external actuating force for this. Since the restoring force for closing the valve is directed past the valve piston directly onto the valve body, the force level for closing the valve is independent of the booster ratio set on the reaction disc for normal actuation via the actuating rod and is therefore freely adjustable.
  • At least one force transmission element acts on the reaction disk, the area of the force bearing on the reaction disk being smaller than the area of the valve piston engaging on the reaction disk and which is connected to the valve body.
  • the force transmission member is a plunger which is guided in a longitudinally displaceable manner in the valve piston.
  • the valve piston takes over the tasks of holding and guiding the tappet, so that the invention can be incorporated into existing brake boosters without additional measures on the control housing. Nevertheless, the movement of the valve piston during normal operation is not influenced by the tappet.
  • connection of the tappet to the valve body is carried out according to the invention via projections formed on the tappet, which are inserted into corresponding recesses in the valve body.
  • the tappet is preferably connected to the section of the valve body that forms the armature of the electromagnet.
  • At least one recess is formed in the side of the control housing facing the reaction disk, in which the force transmission element is arranged, the force transmission element being connected to the valve body via at least one connecting element which extends through a through opening in the control housing.
  • the plunger during normal actuation, engage with the full contact surface on the reaction disc via the actuating rod and transmit the actuating force, while the restoring force for closing the valve is transmitted to the valve body via the smaller contact surface of the force transmission element provided in the recess.
  • the recess is preferably circular and arranged concentrically with the valve piston.
  • the force transmission member is designed as a continuous ring which is connected to the valve body via a plurality of connecting elements which are distributed uniformly around its circumference.
  • At least one spiral spring is provided on the control housing, on which the pressure rod and the valve body are supported.
  • the compressive force acting on the push rod or the reaction disk is passed on to the valve body via the spiral spring, the restoring force being able to be influenced via the spring stiffness of the spiral spring. Since the restoring force does not act on the valve piston, but rather directly on the valve body in this embodiment, it can be set independently of the ratio set on the reaction disk for the normal actuation of the brake booster.
  • a plurality of spiral springs arranged in a star shape around the longitudinal axis of the control housing are provided. This ensures a uniform pressure transmission to the valve body and further reduces the restoring force by increasing the overall bending stiffness accordingly.
  • the spiral springs In order to enable trouble-free actuation of the brake booster in normal operation, the spiral springs have a free space in the region of the longitudinal axis of the control housing for the valve piston to pass through.
  • a uniform effect of the spiral spring arrangement and thus the reduction in the restoring force can be further enhanced by the fact that the spiral springs are connected to one another via at least one ring element.
  • the connecting elements between the spiral springs and the valve body preferably engage the section of the valve body which forms the armature of the electromagnet.
  • FIG. 1 is a partially broken longitudinal section through a vacuum brake booster according to a first embodiment of the invention
  • FIG. 2 is a partially broken longitudinal section through a vacuum brake booster according to a second embodiment of the invention
  • Fig. 3 is a partially broken longitudinal section through a vacuum brake booster according to a third embodiment of the invention.
  • the brake booster shown in FIGS. 1 to 3 is essentially rotationally symmetrical about its axis M, which when installed in a motor vehicle normally corresponds to the longitudinal direction of the vehicle.
  • the only schematically indicated booster housing 1 of the vacuum brake booster is divided by an axially movable wall 2 into a working chamber 3 and a vacuum chamber 4.
  • the movable wall 2 is carried by a control housing 5, which is axially displaceably mounted in the booster housing 1.
  • a control valve 6 is arranged in the control housing 5 so as to be longitudinally displaceable and can be actuated via an actuating rod 7 connected to the brake pedal of a motor vehicle.
  • the control valve 6 consists of a first sealing seat 8 formed in the control housing 5, which separates a first channel 9 opening into the working chamber 3 from a second channel 10 connected to the vacuum chamber 4.
  • valve piston 11 connected to the actuating rod 7, on which a sleeve-shaped valve body 12 is arranged to be longitudinally displaceable.
  • a second sealing seat 13 is formed on the valve body 12 and separates the first channel 9 from a space in communication with the surroundings.
  • the valve body 12 is constantly pushed backwards via a valve spring 14, to the right in the drawing.
  • the actuating rod 7 is normally held in its illustrated rest position by a rear return spring 15, in which an annular sealing body 17 arranged within the control housing 5 and biased forwardly by a spring 16 bears sealingly against the second sealing seat 13, but not completely against the first sealing seat 8 seals.
  • the vacuum chamber 4 is constantly connected to a vacuum source, so that in the rest position of the valve body 12 there is a vacuum in both chambers 3, 4.
  • the movable wall 2 and the control housing 5 connected to it for a common axial movement are pushed into the rear end position shown by a front return spring 18.
  • the braking force is transmitted via a rubber-elastic reaction disk 19, which rests on the end face to the control housing 5, and a reaction disk receptacle 20 to an actuating piston of a master cylinder of the brake system, not shown, which is attached to the vacuum-side booster half, not shown.
  • the electromagnet 21 is assigned to the left in the drawing section 22 of the valve body 12 as a magnet armature such that the valve body 12 is pulled forward against the resistance of the valve spring 14 when the electromagnet 21 is energized.
  • an axial bore 23 is formed, in which a tappet 24 is arranged to be longitudinally displaceable.
  • the tappet 24 is fixedly connected to the latter via projections 25 which engage in corresponding recesses 26 in the armature section 22 of the valve body 12.
  • the projections 25 of the tappet 24 extend through slots 27 in the valve piston 11.
  • valve piston 11 In a valve piston chamber 28 facing the reaction disk 19, the valve piston 11 has a flange-like extension 29 in order to enlarge the contact surface on the reaction disk 19.
  • the function of the vacuum brake booster constructed as described above is described below.
  • the valve body 12 connected to the valve piston 1 is carried along and releases the second sealing seat 13 from the sealing body 17
  • the connection between the first channel 9 and the second channel 10 is closed here since the spring 16 presses the sealing body 17 firmly against the first sealing seat 8.
  • the movable wall 2 is pressed forward with the control valve 5 and transmits the acting force to the master brake cylinder of the brake system (not shown here) via the reaction disc 19 and the push rod 20.
  • the electromagnet 21 is excited so that it pulls the valve body 12 forward and thereby the free flow cross section between the second sealing seat 13 and the sealing body 17 enlarged.
  • the actuation of the valve body 12 via the electromagnet 21 can also take place completely independently of the actuation of the actuation rod 7.
  • the tappet 24 is displaceable within the valve piston 11, that is to say it is moved independently of the latter, the restoring force is independent of the booster ratio on the reaction disc set for normal actuation, in which the valve piston 11 lies directly against the reaction disc 19 and moves it 19 and thus freely adjustable.
  • FIG. 2 corresponds essentially to the first embodiment, so that only the differences are shown here.
  • the same parts are provided with the same reference symbols and their detailed description is omitted.
  • annular recess 50 is formed in the end face of the control housing 5. forms, which is arranged concentrically with the longitudinal axis M of the vacuum brake booster. Arranged in the recess 50 is a ring 51 which is connected to the portion 22 of the valve body 12 forming the armature of the electromagnet 21 via a plurality of connecting elements 51 which are distributed uniformly around its circumference and which extend through through openings 53 in the control housing 5.
  • the ring 51 absorbs the restoring force exerted by the reaction disk 19 and shifts the valve body 12 to the right in the drawing. Since the surface of the ring 51 resting against the reaction disk 19 is relatively small, the restoring force is reduced. As in the first embodiment, the valve body 12 is reset independently of the valve piston 11.
  • the basic structure of the vacuum brake booster corresponds to that of the first and second embodiment, so that it is not described again in detail.
  • a plurality of spiral springs 60 which are evenly distributed over the circumference of the control housing 5 and extend radially inward, are provided, on which the push rod 20 is supported via connecting elements 61.
  • the bending springs 60 leave a free space for the passage of the valve piston 11 in the region of the longitudinal axis M of the control housing 5 and are at their inner free ends connected to the armature section 22 of the valve body 12 via connecting elements 62.
  • the radially extending spiral springs 60 are also connected to one another via a ring 63 with which they are riveted, for example.
  • the reaction disk holder 20 is supported on the spiral springs 60 and generates a bending moment which the valve body 12 transfers pushes the connecting elements 62 back.
  • the restoring force can in this case be set via the bending strength of the bending springs 60.
  • the restoring force can be set independently of the booster ratio set on the reaction disk 19 for normal actuation.

Landscapes

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

Abstract

Un servofrein à dépression comprenant une commande auxiliaire électromagnétique, en particulier pour systèmes de freinage de véhicules, présente un boîtier de servofrein (1) dont le volume intérieur est subdivisé, par une paroi intérieure mobile (1), en une chambre de travail (3) et une chambre à dépression (4), un boîtier de commande (5) déplaçable, avec la paroi mobile, dans le sens axiale du boîtier du servofrein et présentant un premier siège d'étanchéité (8), un corps d'étanchéité (17) monté mobile axialement dans le boîtier de commande et un piston de soupape (11) pouvant être actionné par l'intermédiaire d'une tige de commande (7), un corps de soupape (12) monté mobile axialement sur le piston de soupape, présentant un deuxième siège d'étanchéité (13) et qui est soumis à une précontrainte en direction du corps d'étanchéité (17), un électroaimant (21) prévu dans le boîtier de commande, et un disque de réaction (19) en un matériau élastique, le corps de soupape pouvant être déplacé, via le piston de soupape et/ou l'électroaimant, à distance du corps d'étanchéité. Une ouverture sûre du deuxième siège d'étanchéité par l'électroaimant est garantie, indépendamment du rapport d'amplification sur le disque de réaction, même pour une pression élevée de freinage, grâce au fait qu'il est prévu, entre le disque à réaction et le corps de soupape, des moyens (24), par l'intermédiaire desquels une force de rappel exercée par le disque de réaction est réduite par rapport à une force de rappel exercée lors de l'actionnement du piston de soupape (11) au moyen de la tige de commande (7) et est transmise directement en contournant le piston de soupape.
PCT/EP1997/005267 1996-10-02 1997-09-25 Servofrein a depression WO1998014358A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE1996140683 DE19640683A1 (de) 1996-10-02 1996-10-02 Unterdruckbremskraftverstärker
DE19640683.8 1996-10-02

Publications (1)

Publication Number Publication Date
WO1998014358A1 true WO1998014358A1 (fr) 1998-04-09

Family

ID=7807697

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/EP1997/005267 WO1998014358A1 (fr) 1996-10-02 1997-09-25 Servofrein a depression

Country Status (2)

Country Link
DE (1) DE19640683A1 (fr)
WO (1) WO1998014358A1 (fr)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6311606B1 (en) * 1998-09-30 2001-11-06 Aisin Seiki Kabushiki Kaisha Vacuum servo unit for vehicle brake systems

Citations (3)

* 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
EP0668200A2 (fr) * 1994-02-17 1995-08-23 Lucas Industries Public Limited Company Servo-moteur pneumatique à commande électromagnétique auxiliaire, notamment pour circuits de freinage de véhicules automobiles
DE19523020A1 (de) * 1995-05-03 1996-11-07 Teves Gmbh Alfred Bremskraftverstärker

Family Cites Families (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3279327A (en) * 1964-06-03 1966-10-18 Bendix Corp Reaction mechanism
DE3318065A1 (de) * 1983-05-18 1984-11-22 Alfred Teves Gmbh, 6000 Frankfurt Vakuumbremskraftverstaerker
JPS6237261A (ja) * 1985-08-13 1987-02-18 Jidosha Kiki Co Ltd 倍力装置の入力検出装置
DE4441913C2 (de) * 1994-11-24 1998-11-12 Lucas Ind Plc Elektronisch gesteuerter Bremskraftverstärker
JPH08239029A (ja) * 1995-03-07 1996-09-17 Aisin Seiki Co Ltd 負圧式倍力装置

Patent Citations (3)

* 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
EP0668200A2 (fr) * 1994-02-17 1995-08-23 Lucas Industries Public Limited Company Servo-moteur pneumatique à commande électromagnétique auxiliaire, notamment pour circuits de freinage de véhicules automobiles
DE19523020A1 (de) * 1995-05-03 1996-11-07 Teves Gmbh Alfred Bremskraftverstärker

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6311606B1 (en) * 1998-09-30 2001-11-06 Aisin Seiki Kabushiki Kaisha Vacuum servo unit for vehicle brake systems

Also Published As

Publication number Publication date
DE19640683A1 (de) 1998-04-09

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