EP1037784A1 - Unite servofrein/maitre cylindre a aptitude au freinage amelioree en cas de defaillance du servofrein - Google Patents

Unite servofrein/maitre cylindre a aptitude au freinage amelioree en cas de defaillance du servofrein

Info

Publication number
EP1037784A1
EP1037784A1 EP98961250A EP98961250A EP1037784A1 EP 1037784 A1 EP1037784 A1 EP 1037784A1 EP 98961250 A EP98961250 A EP 98961250A EP 98961250 A EP98961250 A EP 98961250A EP 1037784 A1 EP1037784 A1 EP 1037784A1
Authority
EP
European Patent Office
Prior art keywords
chamber
brake booster
pressure
master cylinder
piston
Prior art date
Legal status (The legal status 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 status listed.)
Ceased
Application number
EP98961250A
Other languages
German (de)
English (en)
Inventor
Leo Gilles
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
ZF International UK Ltd
Original Assignee
Lucas Industries Ltd
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 Ltd filed Critical Lucas Industries Ltd
Publication of EP1037784A1 publication Critical patent/EP1037784A1/fr
Ceased legal-status Critical Current

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
    • B60T8/00—Arrangements for adjusting wheel-braking force to meet varying vehicular or ground-surface conditions, e.g. limiting or varying distribution of braking force
    • B60T8/32—Arrangements for adjusting wheel-braking force to meet varying vehicular or ground-surface conditions, e.g. limiting or varying distribution of braking force responsive to a speed condition, e.g. acceleration or deceleration
    • B60T8/34—Arrangements for adjusting wheel-braking force to meet varying vehicular or ground-surface conditions, e.g. limiting or varying distribution of braking force responsive to a speed condition, e.g. acceleration or deceleration having a fluid pressure regulator responsive to a speed condition
    • B60T8/44—Arrangements for adjusting wheel-braking force to meet varying vehicular or ground-surface conditions, e.g. limiting or varying distribution of braking force responsive to a speed condition, e.g. acceleration or deceleration having a fluid pressure regulator responsive to a speed condition co-operating with a power-assist booster means associated with a master cylinder for controlling the release and reapplication of brake pressure through an interaction with the power assist device, i.e. open systems
    • B60T8/444—Arrangements for adjusting wheel-braking force to meet varying vehicular or ground-surface conditions, e.g. limiting or varying distribution of braking force responsive to a speed condition, e.g. acceleration or deceleration having a fluid pressure regulator responsive to a speed condition co-operating with a power-assist booster means associated with a master cylinder for controlling the release and reapplication of brake pressure through an interaction with the power assist device, i.e. open systems using vacuum
    • 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
    • B60T13/565—Vacuum systems indirect, i.e. vacuum booster units characterised by being associated with master cylinders, e.g. integrally formed
    • 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
    • B60T13/68—Electrical control in fluid-pressure brake systems by electrically-controlled valves
    • B60T13/686—Electrical control in fluid-pressure brake systems by electrically-controlled valves in hydraulic systems or parts thereof
    • 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
    • B60T17/00—Component parts, details, or accessories of power brake systems not covered by groups B60T8/00, B60T13/00 or B60T15/00, or presenting other characteristic features
    • B60T17/18—Safety devices; Monitoring
    • 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
    • B60T8/00—Arrangements for adjusting wheel-braking force to meet varying vehicular or ground-surface conditions, e.g. limiting or varying distribution of braking force
    • B60T8/32—Arrangements for adjusting wheel-braking force to meet varying vehicular or ground-surface conditions, e.g. limiting or varying distribution of braking force responsive to a speed condition, e.g. acceleration or deceleration
    • B60T8/34—Arrangements for adjusting wheel-braking force to meet varying vehicular or ground-surface conditions, e.g. limiting or varying distribution of braking force responsive to a speed condition, e.g. acceleration or deceleration having a fluid pressure regulator responsive to a speed condition
    • B60T8/42—Arrangements for adjusting wheel-braking force to meet varying vehicular or ground-surface conditions, e.g. limiting or varying distribution of braking force responsive to a speed condition, e.g. acceleration or deceleration having a fluid pressure regulator responsive to a speed condition having expanding chambers for controlling pressure, i.e. closed systems
    • B60T8/4275—Pump-back systems

Definitions

  • the invention relates to a brake booster / master cylinder unit for a hydraulic vehicle brake system.
  • the brake booster increases the actuating force initiated by a driver and thus ensures that high braking forces can be applied with a relatively low actuating force.
  • the force acting on the master cylinder during an actuation is therefore composed of a foot power component that is applied by the driver and a component that is applied by the brake booster.
  • the bre power booster is usually a vacuum brake booster.
  • the legislator prescribes a certain minimum deceleration value, for example 0.3 g in Germany, which must be achievable with a defined actuation force.
  • This legal requirement largely determines the basic design of the hydraulic effective diameter of the piston or pistons arranged in the master cylinder. With a given effective diameter of its piston, the master cylinder must on the one hand be able to move enough fluid volume to enable the desired pressure build-up on the wheel brakes, on the other hand, with this given effective diameter, the legally prescribed minimum deceleration must also occur if the brake booster fails can be achieved.
  • a master cylinder in which a trailing chamber separated by a piston from a pressure chamber is fluidly connected to the pressure chamber when the braking force only has to be applied by the brake booster itself.
  • Such operating states occur, for example, when a traction control system prevents one or more drive wheels from spinning by slowing down or slippery or slippery road surface, or when a vehicle dynamics control system selectively brakes individual vehicle wheels in order to counteract a breakaway or skidding of the vehicle.
  • the most important prerequisite for the arrangement described in DE 196 20 228 AI is that the brake booster functions properly.
  • the invention is based on the object of providing a brake booster / master cylinder unit which allows the displacement of sufficiently large fluid volumes and which enables the legally prescribed minimum deceleration to be achieved with the defined foot force in the event of a brake booster failure.
  • this object is achieved in a brake booster / master cylinder unit in which the piston of the master cylinder, to which the input force is transmitted from the brake booster by means of a rod-shaped actuator, has a larger hydraulically effective area than the actuator, in that the device for fluid-conducting connection of the pressure chamber and the trailing chamber then said two chambers connects with each other if the brake booster does not work or no longer works properly.
  • the smaller hydraulically effective area of the actuating member comes into play, so that the actuating force introduced by a driver is reduced more hydraulically and thus the build-up of a sufficiently high braking force despite the lack of force amplification by the brake booster enables.
  • the required actuation stroke which is larger than that of a properly functioning brake booster / master cylinder unit, clearly shows the driver that something is wrong with his brake system.
  • the device for the liquid-conducting connection of the pressure chamber and the trailing chamber advantageously comprises a valve which connects the trailing chamber with a reservoir for hydraulic fluid in a first position and the pressure chamber with the trailing chamber in a second position.
  • a valve which connects the trailing chamber with a reservoir for hydraulic fluid in a first position and the pressure chamber with the trailing chamber in a second position.
  • In the first position of the valve which it assumes when the brake booster / master cylinder unit is functioning properly, is the first position of the valve, which it assumes when the brake booster / master cylinder unit is functioning properly, is the
  • the trailing chamber is thus inoperative, because hydraulic fluid is only sucked into the trailing chamber when the piston is moved or pressed out of it back into the hydraulic fluid reservoir.
  • the hydraulic fluid displaced by it is built up partly under pressure and into the trailing chamber other part pressed through the pressure outlet connected to a brake circuit.
  • the above object is achieved in that the trailing chamber is in constant liquid-conducting connection with a reservoir for hydraulic fluid, that the piston on its side facing away from the actuator is mechanically connected to an intermediate piston, which has a smaller diameter than the piston and which extends into an intermediate pressure chamber which is separate from the pressure chamber and which has a second pressure outlet provided for connection to the brake circuit mentioned, and that the device for fluid-conducting connection of the pressure chamber and the trailing chamber connects these two chambers to one another and the one present in the pressure chamber, shuts off the first pressure outlet from said brake circuit if the brake booster is not working or is not working properly.
  • this second variant has the advantage that the degree of change in reduction that occurs when the pressure-conducting chamber and the trailing chamber are connected in a liquid-conducting manner is independent of the hydraulic active surface of the actuating member.
  • the actuator can be dimensioned regardless of a specific hydraulic reduction
  • the intermediate piston can be designed so that a desired hydraulic reduction is achieved.
  • the intermediate piston can be made in one piece with the piston separating the trailing chamber from the pressure chamber, but it can also form a separate component which only bears against the aforementioned piston or is connected to it in some other way, for example by screwing.
  • both the pressure chamber through the first pressure outlet and the intermediate pressure chamber through the second pressure outlet contribute to the pressure build-up in the brake circuit connected to the aforementioned pressure outlets.
  • this brake circuit if the brake booster is functioning properly, the hydraulically effective surfaces of the intermediate piston and of the piston separating the trailing chamber from the pressure chamber add up.
  • the trailing chamber is inoperative in this operating state; when the master cylinder is actuated, hydraulic fluid is sucked in without pressure from the hydraulic fluid reservoir into the trailing chamber, and is pushed back into the hydraulic fluid reservoir when the piston separating the trailing chamber from the pressure chamber returns.
  • the pressure chamber is fluidly connected to the trailing chamber and the first pressure outlet present in the pressure chamber is closed.
  • pressure build-up in the brake circuit mentioned only takes place via the intermediate pressure chamber and the hydraulically active surface of the intermediate piston arranged therein.
  • the hydraulically effective surface of the piston separating the trailing chamber from the pressure chamber then only displaces a certain volume of fluid from the pressure chamber into the trailing chamber and from there into the hydraulic fluid reservoir.
  • the trailing chamber thus creates a connection between the pressure chamber and the hydraulic fluid reservoir in this operating state.
  • the trailing chamber is completely eliminated and instead the pressure chamber is connected directly to the hydraulic fluid reservoir in the event of a defect or failure of the brake booster.
  • the device for the liquid-conducting connection of pressure chamber and trailing chamber preferably comprises a valve which connects the first pressure outlet to the second pressure outlet in a first position and the first pressure outlet to the trailing chamber in a second position. If, according to the modified embodiment of the second alternative, there is no trailing chamber, the valve connects the first pressure outlet to the second pressure outlet in its first position and the first pressure outlet to the hydraulic fluid reservoir in its second position.
  • the valve belonging to the device mentioned preferably has an actuating tappet which interacts with the membrane of a vacuum socket which is arranged in a vacuum chamber of the brake booster.
  • the vacuum can be determined in this embodiment, whether the brake booster works properly. If it works properly, there must be a certain negative pressure in relation to the atmosphere in the negative pressure chamber. If the pressure in the vacuum chamber rises, this means that the brake booster is no longer working properly.
  • the membrane of the vacuum box interacts with the actuating plunger of the valve in such a way that the valve is moved into its second position in the vacuum chamber when a predetermined pressure threshold is exceeded, in which only the smaller hydraulic effective area of the actuating element or the intermediate piston is left causes the pressure to build up in the brake circuit mentioned.
  • the valve is resiliently biased into its second position, for example by a spring acting on the membrane of the vacuum box. If the vacuum corresponding to its proper function is present in the vacuum chamber of the brake booster, a force opposing the aforementioned spring acts on the membrane of the vacuum can, so that the valve assumes its first position. If the vacuum in the
  • Vacuum chamber the force of the spring biasing the valve into its second position prevails, so that the valve assumes this second position.
  • the valve is an electromagnetic valve which is connected to a pressure sensor arranged in a vacuum chamber of the brake booster.
  • a pressure sensor arranged in a vacuum chamber of the brake booster.
  • this pressure sensor emits an electrical signal which causes the electromagnetic valve to assume its second position.
  • the pressure sensor is connected directly to the electromagnetic valve.
  • the pressure sensor is connected to the solenoid valve via an electronic control unit, which also controls other functions of the brake system, for example a brake slip and / or traction control system and the like.
  • a piston which is sealingly and displaceably guided in the bore of the master cylinder and is designed as a floating piston and which has another pressure chamber with a in the bore limited third pressure outlet, which is provided for connection to the second brake circuit.
  • Fig. 1 shows a first embodiment of a brake booster / master cylinder unit according to the invention in longitudinal section
  • Fig. 2 is a similar to the first embodiment, somewhat modified second embodiment also in longitudinal section.
  • Fig. 1 shows a brake booster / master cylinder unit 10 consisting of a brake booster 12 and an associated, downstream master cylinder 14.
  • a brake booster / master cylinder unit 10 consisting of a brake booster 12 and an associated, downstream master cylinder 14.
  • Today, units of this type are installed millions of times in cars and smaller commercial vehicles.
  • the brake booster 12 is here a vacuum brake booster in a so-called tandem design, ie it has a housing 16, the interior of which is formed by a fixed partition 18 and two movable partitions 20, 20 'in two vacuum chambers 22, 22' and two working chambers 24, 24 'is divided.
  • each vacuum chamber 22, 22 ' is constantly in operation of the brake booster. dig connected to a vacuum source, such as the intake tract of an internal combustion engine that drives the vehicle in which the brake booster / master cylinder unit 10 is installed.
  • the working chambers 24, 24 ' are also connected to the vacuum source, so that initially the same pressure level as in the vacuum chambers 22, 22' prevails in them.
  • a control valve generally designated 28 and not described in more detail here, ensures that the working chambers 24, 24 'be disconnected from the vacuum source and connected to atmospheric pressure (or overpressure). A pressure difference then builds up on the two movable partitions 20, 20 ', which leads to the displacement of the partitions 20, 20' to the left in the figures.
  • the resulting force in the actuating direction is transmitted from the movable partitions 20, 20 'to the housing of the control valve 28 and from there, together with the actuating force introduced via the input member 26, is delivered to a rod-shaped actuating member 30 of the master cylinder 14.
  • the force with which the master cylinder 14 is actuated thus arises from the addition of the actuating force introduced by a driver via the input member 26 of the brake booster 12 and the additional actuating force then generated by the brake booster 12 through the displacement of the movable partition walls 20, 20 '.
  • This function and the structure of a vacuum brake booster 12 are well known to those skilled in the art, which is why a further explanation can be dispensed with here.
  • the master cylinder 14 has a housing 32 with a bore 34 formed therein, in which a rod-shaped actuator supply member 30 coupled piston 36 is sealingly and slidably guided.
  • the piston 36 delimits a pressure chamber 38 in the bore 34 on its one side facing away from the brake booster 12 and a follow-up chamber 40 on its opposite side facing the brake booster 12.
  • the piston 36 On its side facing away from the actuator 30, the piston 36 is in mechanical connection with an intermediate piston
  • the pressure chamber 38 has a first pressure outlet 48 and the intermediate pressure chamber 46 has a second pressure outlet 50. Both pressure outlets 48 and 50 are intended to be connected to one and the same brake circuit. In the figures, this brake circuit is the one that is responsible for building up brake pressure on wheel brakes 52 and 54, which are only shown schematically here.
  • a further piston 56 is sealingly and displaceably guided in the bore 34 of the master cylinder housing 32 and is designed here as a floating piston.
  • the further piston 56 whose end face on the right in the figures forms a boundary wall of the intermediate pressure chamber 46, delimits, with its opposite end face, together with the bore 34, a further pressure chamber 58 with a third pressure outlet 60, which is provided for connection to a second brake circuit, which in wheel brakes 62 and 64 are assigned to the figures.
  • Both the trailing chamber 40 and the pressure chamber 38 and 58 are, as shown in the figures, connected in a liquid-conducting manner to a reservoir 66 for hydraulic fluid.
  • the openings which make the connection to the storage container 66 are arranged such that these openings differ from those which are actuated when the Master cylinder 14 displacing pistons 36 and 56 are closed practically immediately after the start of actuation, so that pressure can build up in the pressure chambers 38 and 58.
  • the trailing chamber 40 is constantly connected to the reservoir 66 for hydraulic fluid.
  • a device which essentially consists of a valve 68 which, in a first position, connects the first pressure outlet 48 of the pressure chamber 38 to the second pressure outlet 50 of the intermediate pressure chamber 46 connects, and which connects the first pressure outlet 48 to the trailing chamber 40 in a second position.
  • the valve 68 has an actuating plunger 70 which interacts with the membrane 72 of a vacuum socket 74 which is arranged in the vacuum chamber 22 of the brake booster 12.
  • the membrane 72 is biased against the actuating plunger 70 by a spring 76 located in the vacuum can 74, whereby the valve 68 is resiliently biased into its second position.
  • the function of the brake booster / master cylinder unit 10 is explained in more detail below. It is initially assumed that the brake booster 12 is functioning properly, i.e. in its vacuum chambers 22, 22 'the constructively provided vacuum level is reached. At the
  • Membrane 72 of vacuum box 74 is then subjected to a pressure difference that is large enough to move membrane 72 against the force of spring 76 and thereby, via actuating plunger 70, to move valve 68 into its first position, in which the two Pressure outlets 48 and 50 are interconnected.
  • An actuation of the master cylinder 14 leads to a displacement of the piston 36, the intermediate piston 42 coupled to it and the floating piston 56.
  • the valve 68 in its first position is in the pressure chambers 38 and 58 and in the intermediate pressure chamber 46 Hydraulic pressure built up. Since the two pressure outlets 48 and 50 are connected to each other, are With regard to the brake circuit to which the wheel brakes 52 and 54 are assigned, the hydraulically effective surfaces of the piston 36 and the intermediate piston 42 participate in the pressure build-up.
  • valve 68 If the valve 68 is in its second position, then when the master cylinder 14 is actuated, hydraulic fluid from the pressure chamber 38 is only displaced without pressure into the follow-up chamber 40 and from there into the reservoir 66 for hydraulic fluid.
  • the total effective area of the piston 36 and the intermediate piston 42 can be set independently of the diameter of the rod-shaped actuating member 30, the degree of the hydraulic reduction change of the master cylinder 14 which occurs in the event of a failure of the brake booster 12.
  • the second exemplary embodiment of the brake booster / master cylinder unit 10 shown in FIG. 2 differs from the first exemplary embodiment explained above in that it cooperates with the vacuum socket 74
  • Valve 68 is replaced by an electromagnetic valve 68 •, which is connected to an electronic control unit 73, which in turn is connected to a pressure sensor 80, which measures the prevailing pressure in the vacuum chamber 22 of the brake booster 12. If the pressure in the vacuum chamber 22 rises above a predetermined value, the pressure sensor 80 emits a signal to the control unit 78, which then causes the solenoid valve 68 'to assume its second position, in which the first pressure outlet 48 of the pressure chamber 38 with the Follow-up chamber 40 is connected.
  • the function of the second embodiment thus corresponds to that of the first embodiment.
  • valve 68, 68 'in its second position connects the first pressure outlet 48 directly to the reservoir 66 for hydraulic fluid.
  • the trailing chamber 40 is completely eliminated in this third exemplary embodiment.
  • the intermediate piston 42, the intermediate wall 44 and the intermediate pressure chamber 46 are omitted.
  • a valve corresponding to the valve 68, 68 ' connects the wake in its first position, which is assumed when the brake booster 12 is functioning properly barm 40 with the reservoir 66 for hydraulic fluid, and in its second position, which is assumed in the event of a defect in the brake booster 12, the Pressure chamber 38 with the trailing chamber 40.
  • part of the hydraulic fluid is therefore shifted from the pressure chamber 38 into the trailing chamber 40; thus only the hydraulically effective area of the rod-shaped actuating member 30, which is smaller than the hydraulically effective area of the piston 36, contributes to the build-up of pressure.
  • a sufficiently high brake pressure can be built up in the event of a failure of the brake booster 12, but the actuation path, however, is extended.

Landscapes

  • Engineering & Computer Science (AREA)
  • Transportation (AREA)
  • Mechanical Engineering (AREA)
  • Physics & Mathematics (AREA)
  • Fluid Mechanics (AREA)
  • Braking Systems And Boosters (AREA)
  • Transmission Of Braking Force In Braking Systems (AREA)

Abstract

L'invention concerne une unité servofrein/maître cylindre (10) destinée à une installation hydraulique de freinage de véhicule. Ladite unité comporte un maître cylindre (14) pourvu d'un corps (32) dans lequel est ménagé un alésage (34). Dans ledit alésage (34) est guidé, de façon étanche et mobile, un piston (36) qui est relié mécaniquement à un organe d'actionnement (30) sous forme de tige, cet organe servant au transfert audit piston (36) d'une force d'entrée provenant du servofrein (12). Sur un de ses côtés, le piston (36) délimite une chambre de pression (38) pourvue d'un orifice de libération de pression (48) servant à la liaison avec un circuit de freinage, et sur son autre côté, côté opposé faisant face à l'organe d'actionnement (30), ledit piston délimite une chambre d'appoint (40). Le piston (36) présente une surface hydrauliquement active plus grande que celle de l'organe d'actionnement (30). Un dispositif, qui peut mettre, de façon sélective, la chambre de pression (38) et la chambre d'appoint (40) en communication fluidique, établit ladite communication lorsque le servofrein (12) ne fonctionne pas du tout ou ne fonctionne pas correctement.
EP98961250A 1997-12-17 1998-12-03 Unite servofrein/maitre cylindre a aptitude au freinage amelioree en cas de defaillance du servofrein Ceased EP1037784A1 (fr)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
DE1997156248 DE19756248A1 (de) 1997-12-17 1997-12-17 Bremskraftverstärker/Hauptzylinder-Einheit mit verbesserter Bremsfähigkeit bei einem Bremskraftverstärkerausfall
DE19756248 1997-12-17
PCT/EP1998/007878 WO1999030948A1 (fr) 1997-12-17 1998-12-03 Unite servofrein/maitre cylindre a aptitude au freinage amelioree en cas de defaillance du servofrein

Publications (1)

Publication Number Publication Date
EP1037784A1 true EP1037784A1 (fr) 2000-09-27

Family

ID=7852338

Family Applications (1)

Application Number Title Priority Date Filing Date
EP98961250A Ceased EP1037784A1 (fr) 1997-12-17 1998-12-03 Unite servofrein/maitre cylindre a aptitude au freinage amelioree en cas de defaillance du servofrein

Country Status (3)

Country Link
EP (1) EP1037784A1 (fr)
DE (1) DE19756248A1 (fr)
WO (1) WO1999030948A1 (fr)

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE10234366B3 (de) * 2002-07-27 2004-03-04 Daimlerchrysler Ag Bremsdrucksteuervorrichtung
DE102006015850A1 (de) * 2005-04-15 2006-11-02 Continental Teves Ag & Co. Ohg Vorrichtung zur Bremsbestätigung eines Kraftfahrzeuges

Family Cites Families (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE2451467A1 (de) * 1974-10-30 1976-05-06 Daimler Benz Ag Vorrichtung zur automatischen veraenderung der bremspedaluebersetzung beim ausfall der hilfsenergie des bremskraftverstaerkers
DE2521368A1 (de) * 1975-05-14 1976-11-25 Teves Gmbh Alfred Fuer kraftfahrzeuge bestimmtes bremsgeraet
DE3504562A1 (de) * 1985-02-11 1986-08-14 Alfred Teves Gmbh, 6000 Frankfurt Hydraulische bremsanlage
DE19620228C2 (de) * 1996-05-20 1999-06-10 Lucas Ind Plc Hauptzylinder für eine hydraulische Fahrzeugbremsanlage

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
See references of WO9930948A1 *

Also Published As

Publication number Publication date
DE19756248A1 (de) 1999-07-01
WO1999030948A1 (fr) 1999-06-24

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