EP0874749A1 - Hydraulic brake system with device for active braking - Google Patents

Hydraulic brake system with device for active braking

Info

Publication number
EP0874749A1
EP0874749A1 EP97902176A EP97902176A EP0874749A1 EP 0874749 A1 EP0874749 A1 EP 0874749A1 EP 97902176 A EP97902176 A EP 97902176A EP 97902176 A EP97902176 A EP 97902176A EP 0874749 A1 EP0874749 A1 EP 0874749A1
Authority
EP
European Patent Office
Prior art keywords
pressure
brake
line
return pump
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
EP97902176A
Other languages
German (de)
French (fr)
Inventor
Thomas Bartsch
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.)
Continental Teves AG and Co OHG
Original Assignee
ITT Manufacturing Enterprises LLC
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 LLC filed Critical ITT Manufacturing Enterprises LLC
Publication of EP0874749A1 publication Critical patent/EP0874749A1/en
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
    • B60T15/00—Construction arrangement, or operation of valves incorporated in power brake systems and not covered by groups B60T11/00 or B60T13/00
    • B60T15/02—Application and release valves
    • B60T15/36—Other control devices or valves characterised by definite functions
    • B60T15/38—Other control devices or valves characterised by definite functions for quick take-up and heavy braking, e.g. with auxiliary reservoir for taking-up slack
    • B60T15/40—Other control devices or valves characterised by definite functions for quick take-up and heavy braking, e.g. with auxiliary reservoir for taking-up slack with separate take-up and applying cylinders
    • 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
    • B60T8/40—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 comprising an additional fluid circuit including fluid pressurising means for modifying the pressure of the braking fluid, e.g. including wheel driven pumps for detecting a speed condition, or pumps which are controlled by means independent of the braking system
    • B60T8/404—Control of the pump unit
    • B60T8/405—Control of the pump unit involving the start-up phase
    • 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
    • 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
    • B60T8/441—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 hydraulic boosters
    • 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
    • B60T8/48—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 connecting the brake actuator to an alternative or additional source of fluid pressure, e.g. traction control systems
    • B60T8/4809—Traction control, stability control, using both the wheel brakes and other automatic braking systems
    • B60T8/4827—Traction control, stability control, using both the wheel brakes and other automatic braking systems in hydraulic brake systems
    • B60T8/4863—Traction control, stability control, using both the wheel brakes and other automatic braking systems in hydraulic brake systems closed systems
    • B60T8/4872—Traction control, stability control, using both the wheel brakes and other automatic braking systems in hydraulic brake systems closed systems pump-back systems

Definitions

  • Hydraulic brake system with a device for active braking
  • the present invention relates to a hydraulic brake system according to the preamble of claim 1.
  • Such a brake system is known for example from WO 91/18776.
  • the known brake system is suitable for anti-lock control and traction control.
  • the traction control system as a type of active braking does not require the brake pedal to be operated. Therefore, the filling of the wheel brakes of the driven wheels must be carried out by a pump.
  • the known brake system uses the return pump of the anti-lock control device.
  • a pressure accumulator is installed in a suction line from the suction side of the pump to the master brake cylinder, which is intended to provide the suction side of the return pump with a pre-pressure in the case of traction control.
  • a switching valve is arranged between the pressure accumulator and the suction side of the return pump, which only connects the pressure accumulator to the suction side of the return pump when a traction control is to be carried out.
  • the object of the present invention is to equip a braking system of the type mentioned at the outset with simple means such that a rapid braking effect can be achieved by using the return pump for active braking.
  • the principle of the present invention is therefore that the return pump acts on a small effective area of a stepped piston and displaces this stepped piston by its high delivery pressure, so that the larger effective area of the stepped piston displaces a larger volume of pressure medium than is conveyed by the return pump. Since a high pressure is not required to overcome the air play of the wheel brakes, the larger area of the stepped piston can be dimensioned considerably larger than the smaller area. If a higher pressure is required in the wheel brakes after this priming process, the return pump can then feed directly into the wheel brakes through the pressure line and also generate a high pressure with a low volume flow. So that the stepped piston is initially displaced, means are provided in the pressure line parallel to this pressure-volume translator, which initially accumulate the pump pressure.
  • a pre-pressure valve is suitable for this, which has the advantage that it is permanently at a constant pressure difference. renz opens. Its opening pressure is then designed so that the dynamic pressure developed is just sufficient to fill the wheel brake cylinders of the wheels to be actively braked.
  • a spring action of the stepped piston towards the pressure side of the pump causes this volume accumulator to charge automatically when the return pump is switched off.
  • a seat valve which blocks the connection between the brake line and the stepped piston as soon as the stepped piston has overcome its stroke for filling the wheel brakes, prevents the stepped piston from retracting during active braking. Since the valve is dimensioned such that it has a much smaller effective area in the opening direction than the smaller stepped piston area, it cannot happen that the brake pressure built up in the brake line by the return pump pushes the stepped piston back to the return pump and the total delivery volume of the return ⁇ feed pump flows into the volume storage.
  • FIG. Shows a hydraulic brake system according to the invention in a symbolic representation.
  • the master cylinder 1 is connected to a storage container 2 and can be actuated via a brake pedal 3.
  • a brake line 4 runs from the master cylinder 1 to a wheel brake 5.
  • Another wheel brake is also supplied by the brake line 4, but is not shown.
  • a separating valve 6 Arranged in the brake line 4 is a separating valve 6, which, like the inlet valve 7 inserted closer to the wheel brake 5, is an electromagnetically actuated, normally open 2/2-way valve.
  • a non-return valve 8 is arranged parallel to the isolating valve 6 and allows a pressure medium flow from the master cylinder 1 to the wheel brake 5.
  • a pressure relief valve 9 opens, which releases an excessively high pressure in the brake line 4 below the separating valve 6 during active braking, that is to say when the separating valve 6 is closed.
  • active braking can be any type of brake intervention, which can also take place without actuation of the brake pedal 3.
  • a non-return valve 10 is located parallel to the inlet valve 7, which allows a rapid pressure reduction from the wheel brake 5, even if the inlet valve 7 should still be closed when braking is ended.
  • a return line 11 runs from the wheel brake 5 via an outlet valve 12 to a low-pressure accumulator 13 and from there to the suction side of a self-priming return pump 14.
  • a non-return valve is inserted into the return line 11 between the low-pressure accumulator 13 and the suction side of the return pump 14.
  • til 15 inserted, which only allows a pressure medium flow to the suction side of the return pump 14.
  • a suction line 16 branches off from the brake line 4 between the master cylinder 1 and the isolation valve 6 and also leads via a changeover valve 17 to the suction side of the return pump 14.
  • the pressure side of the latter is connected to the brake line 4 via a pressure line 18 which has a pre-pressure check valve 19 connected between isolation valve 6 and inlet valve 7.
  • the pre-pressure check valve 19 is only permeable for a volume flow from the return pump 14 to the brake line 4.
  • a pressure-volume translator 20 is located parallel to the pressure line 18. It has a stepped bore
  • stepped piston 22 a stepped piston 22.
  • the smaller end face of the stepped piston 22 is connected to the pressure side of the return pump 14.
  • the step of the step piston 22 points to the brake line 4.
  • This larger end face of the stepped piston 22 is acted upon by a compression spring 23 towards the return pump 14.
  • the step of the step piston 22 is connected to the atmosphere.
  • a sealing seat 24 which has a smaller diameter than the smaller end face of the stepped piston 22.
  • This sealing seat 24 interacts with the larger end face of the stepped piston 22 as a seat valve. Since this is a purely schematic representation, the seat valve between the stepped bore 21 and the brake line 4 can also be designed differently. All that matters is the opening cross section, which must be smaller than the smaller end face of the stepped piston 22.
  • a throttle 25 is provided parallel to the pressure line 18 and to the pressure-volume translator 20, which allows a pressure medium outflow from the pressure side of the return pump 14 to the brake line 4, when the return spring 14 is at a standstill, the compression spring 23 the step piston 22 to the return pump 14 moves and thus feels the volume storage spanned by the compression spring 23 again.
  • the brake system works on the known return conveyor principle. Since a brake pressure is already present in the brake line 4 from the master cylinder 1, the delivery pressure of the return pump 14 is also unable to displace the stepped piston 22. The pressure in the brake line 4 has a much larger effective area on the stepped piston 22 than the pressure side of the return pump 14.
  • the brake pedal 3 In the case of active braking, be it for traction control or for another control intervention such as yaw moment control, the brake pedal 3 is not actuated.
  • the master cylinder 1 is therefore depressurized and with it the brake line 4 to the isolating valve 6.
  • the latter is closed for active braking.
  • the return pump 14 starts to run, whereby the normally closed changeover valve 17 is energized to open the suction line 16, so that the suction line 16 establishes a connection to the master cylinder 1 and thus to the reservoir 2.
  • the return pump 14 therefore sucks in pressure medium and conveys it into the pressure line 18 and into the pressure-volume translator 20 before the pumped pressure medium can propagate to the brake line 4.
  • the pressure built up on the pressure side of the return pump 14 has an effect even with a small delivery volume Moving the stepped piston 22 towards the brake line 4.
  • a considerably larger volume is displaced towards the brake line 4 than is required for the displacement of the step piston 22 from the pressure side of the return pump 14.
  • the pressure level built up in the brake line 4 is considerably lower than on the pressure side of the return pump 14.
  • this is of no further importance since it is not a high pressure, but only a large volume that is required to overcome the air play of the wheel brake 5.
  • the isolating valve 6 When active braking has ended, the isolating valve 6 is opened so that the brake pressure can be reduced via the brake line 4 and the master cylinder 1 into the reservoir 2.
  • the pump 14 is switched off so that no further pressure medium is delivered.
  • the residual pressure remaining on the pressure side of the return pump 14 slowly dissipates via the throttle 25.
  • the compression spring 23 is able to move the piston 22 back to the return pump 14 into the stop position shown.
  • the of the compression spring 23 spanned volume storage is thus refilled and ready for another active braking.
  • the throttle 25 shown here schematically parallel to the stepped piston 22 can also pass through the stepped piston 22. It then connects the two end faces of the stepped piston, that is to say the pressure side of the return pump 14 with the brake line 4.
  • the throttle 25 can have a very narrow cross section, so that it does not build up a dynamic pressure on the pressure side of the return pump 14 during active braking with special needs. This is because the pressure medium volume to be displaced in order to reset the step piston 22 is comparatively small in relation to the quantity of pressure medium contained in the volume accumulator.

Abstract

In order to enable a hydraulic brake system equipped with a self-priming return pump (14) to rapidly fill wheel brakes (5) during active braking, the invention proposes providing a pressure-volume intensifier (20) on the pressure side of the return pump (14). This has the effect that at low displaced volumes of the return pump (14) a high volume of the pressure medium is delivered to the brake line (4) of the wheel brake concerned (5). This is possible because a return pump (14) can produce high pressure and thus a sufficient force to displace a differential piston which then can displace a large volume of pressure medium. So that sufficient back pressure can be built up on the pressure side of the return pump (14), a supply pressure check valve is built into the pressure line (18) running parallel to the pressure-volume intensifier (20). This valve lets the necessary pressure medium pass through into the brake line (4) only once a given supply pressure is reached.

Description

Hydraulische Bremsanlage mit einer Einrichtung zur AktivbremsungHydraulic brake system with a device for active braking
Die vorliegende Erfindung betrifft eine hydraulische Brems¬ anlage gemäß dem Oberbegriff des Anspruchs 1.The present invention relates to a hydraulic brake system according to the preamble of claim 1.
Eine derartige Bremsanlage ist beispielsweise aus der WO 91/18776 bekannt. Die bekannte Bremsanlage ist zur Blockier¬ schutzregelung sowie zur Antriebsschlupfregelung geeignet. Die Antriebsschlupfregelung als eine Art der Aktivbremsung erfordert keine Betätigung des Bremspedals. Daher muß die Befüllung der Radbremsen der angetriebenen Räder von einer Pumpe vorgenommen werden. Die bekannte Bremsanlage nutzt hierzu die Rückförderpumpe der Blockierschutzregeleinrich¬ tung aus. Um für diese Zwecke auch eine Rückförderpumpe ver¬ wenden zu können, die nicht selbstansaugend ausgelegt ist, ist in einer Saugleitung von der Saugseite der Pumpe zum Hauptbremszylinder ein Druckspeicher angelegt, welcher bei einer Antriebsschlupfregelung die Saugseite der Rückförder¬ pumpe mit einem Vordruck versehen soll. Die Anordnung ist aber ebenso zur Vorladung einer selbstansaugenden Rückför¬ derpumpe vorgesehen. Zwischen dem Druckspeicher und der Saugseite der Rückförderpumpe ist ein Schaltventil angeord¬ net, welches den Druckspeicher nur dann mit der Saugseite der Rückförderpumpe verbindet, wenn eine Antriebsschlupf- regelung vorgenommen werden soll.Such a brake system is known for example from WO 91/18776. The known brake system is suitable for anti-lock control and traction control. The traction control system as a type of active braking does not require the brake pedal to be operated. Therefore, the filling of the wheel brakes of the driven wheels must be carried out by a pump. For this purpose, the known brake system uses the return pump of the anti-lock control device. In order to be able to use a return pump for this purpose, which is not designed to be self-priming, a pressure accumulator is installed in a suction line from the suction side of the pump to the master brake cylinder, which is intended to provide the suction side of the return pump with a pre-pressure in the case of traction control. However, the arrangement is also intended for pre-charging a self-priming return pump. A switching valve is arranged between the pressure accumulator and the suction side of the return pump, which only connects the pressure accumulator to the suction side of the return pump when a traction control is to be carried out.
Für die vorliegende Erfindung ist es unerheblich, ob die Rückförderpumpe selbstansaugend ausgelegt ist oder vorgela¬ den werden muß. Das prinzipielle Problem bei Hochdruckpumpen in Bremsanlagen ist folgendes: Bevor überhaupt eine Brems¬ wirkung an den Radbremsen erzielt werden kann, muß schnell ein bestimmtes Volumen zur Überwindung des Lüftspiels der Radbremsen in die Bremsleitung befördert werden. Rückförder¬ pumpen sind zwar in der Lage, einen hohen Druck aufzubauen, jedoch ist der geförderte Druckmittelstrom so klein, daß bei niedrigem Druckniveau es einer längeren Zeit bedarf, bis eine Bremswirkung auftritt. Zur Überwindung des Luftspiels von Radbremszylindern ist daher eine Rückförderpumpe - selbstansaugend oder nicht selbstansaugend - nur bedingt geeignet. Erforderlich ist nämlich hierzu nicht hoher Druck, sondern ein großer Volumenstrom.For the present invention, it is irrelevant whether the return pump is designed to be self-priming or must be preloaded. The basic problem with high-pressure pumps in brake systems is as follows: Before a braking effect can be achieved on the wheel brakes at all, a certain volume has to be overcome quickly to overcome the clearance of the Wheel brakes are conveyed into the brake line. Rückförder¬ pumps are able to build up a high pressure, but the pressure medium flow is so small that it takes a long time for a braking effect at low pressure level. A return pump - self-priming or not self-priming - is therefore only suitable to a limited extent to overcome the air play in wheel brake cylinders. This does not require a high pressure, but a large volume flow.
Die Aufgabe der vorliegenden Erfindung besteht darin, mit einfachen Mitteln eine Bremsanlage der eingangs genannten Art dahingehend auszustatten, daß unter Ausnutzung der Rück¬ förderpumpe bei einer Aktivbremsung eine schnelle Bremswir¬ kung erzielt werden kann.The object of the present invention is to equip a braking system of the type mentioned at the outset with simple means such that a rapid braking effect can be achieved by using the return pump for active braking.
Diese Aufgabe wird gelöst in Verbindung mit den kennzeich¬ nenden Merkmalen des Anspruchs 1. Das Prinzip der vorliegen¬ den Erfindung besteht also darin, daß die Rückförderpumpe auf eine kleine Wirkfläche eines Stufenkolbens einwirkt und durch ihren hohen Förderdruck diesen Stufenkolben ver¬ schiebt, so daß die größere Wirkfläche des Stufenkolbens ein größeres Druckmittelvolumen verdrängt, als es von der Rück¬ förderpumpe gefördert wird. Da ein hoher Druck zur Überwin¬ dung des Luftspiels der Radbremsen nicht erforderlich ist, kann die größere Fläche des Stufenkolbens erheblich größer bemessen sein als die kleinere Fläche. Wenn nach diesem Vor- füllvorgang ein größerer Druck in den Radbremsen erforder¬ lich wird, so kann dann die Rückförderpumpe durch die Druck¬ leitung direkt in die Radbremsen fördern und auch mit gerin¬ gem Volumenstrom einen hohen Druck erzeugen. Damit zunächst aber der Stufenkolben verschoben wird, sind in der Druck¬ leitung parallel zu diesem Druck-Volumen-Übersetzer Mittel vorgesehen, die zunächst den Pumpendruck stauen.This object is achieved in connection with the characterizing features of claim 1. The principle of the present invention is therefore that the return pump acts on a small effective area of a stepped piston and displaces this stepped piston by its high delivery pressure, so that the larger effective area of the stepped piston displaces a larger volume of pressure medium than is conveyed by the return pump. Since a high pressure is not required to overcome the air play of the wheel brakes, the larger area of the stepped piston can be dimensioned considerably larger than the smaller area. If a higher pressure is required in the wheel brakes after this priming process, the return pump can then feed directly into the wheel brakes through the pressure line and also generate a high pressure with a low volume flow. So that the stepped piston is initially displaced, means are provided in the pressure line parallel to this pressure-volume translator, which initially accumulate the pump pressure.
Hierzu eignet sich ein Vordruckventil, welches den Vorteil hat, daß es sich permanent bei einer konstanten Druckdiffe- renz öffnet. Sein Öffnungsdruck wird dann so ausgelegt, daß der entwickelte Staudruck gerade ausreicht, um die Radbrems¬ zylinder der aktiv zu bremsenden Räder zu füllen.A pre-pressure valve is suitable for this, which has the advantage that it is permanently at a constant pressure difference. renz opens. Its opening pressure is then designed so that the dynamic pressure developed is just sufficient to fill the wheel brake cylinders of the wheels to be actively braked.
Eine Federbeaufschlagung des Stufenkolbens zur Druckseite der Pumpe hin bewirkt eine selbsttätige Aufladung dieses Volumenspeichers, wenn die Rückförderpumpe ausgeschaltet ist.A spring action of the stepped piston towards the pressure side of the pump causes this volume accumulator to charge automatically when the return pump is switched off.
Damit das zwischen der Druckseite der Pumpe und dem Stufen¬ kolben befindliche Volumen bei einer Aufladung des Volumen¬ speichers verdrängt werden kann, empfiehlt es sich, parallel zum Stufenkolben eine Drosselvorrichtung vorzusehen, über welche das eingeschlossene Volumen zur Bremsleitung hin ab¬ fließen kann.So that the volume between the pressure side of the pump and the stepped piston can be displaced when the volume accumulator is charged, it is advisable to provide a throttle device parallel to the stepped piston, via which the enclosed volume can flow off to the brake line.
Ein Sitzventil, welches die Verbindung zwischen der Brems¬ leitung und dem Stufenkolben sperrt, sobald der Stufenkolben seinen Hub zur Befüllung der Radbremsen überwunden hat, ver¬ hindert ein Zurückfahren des Stufenkolbens während einer Aktivbremsung. Da das Ventil so bemessen wird, daß es eine wesentlich kleinere Wirkfläche in Öffnungsrichtung aufweist als die kleinere Stufenkolbenflache, kann es nicht passie¬ ren, daß der durch die Rückförderpumpe in der Bremsleitung aufgebaute Bremsdruck den Stufenkolben zur Rückförderpumpe hin zurückschiebt und das gesamte Fördervolumen der Rück¬ förderpumpe in den Volumenspeicher abfließt.A seat valve, which blocks the connection between the brake line and the stepped piston as soon as the stepped piston has overcome its stroke for filling the wheel brakes, prevents the stepped piston from retracting during active braking. Since the valve is dimensioned such that it has a much smaller effective area in the opening direction than the smaller stepped piston area, it cannot happen that the brake pressure built up in the brake line by the return pump pushes the stepped piston back to the return pump and the total delivery volume of the return ¬ feed pump flows into the volume storage.
Wenn die Drossel parallel zum Stufenkolben zur Entlastung der Druckleitung zwischen Rückförderpumpe und Stufenkolben durch den Stufenkolben hindurchgeführt ist, so ergibt sich eine besonders platzsparende Lösung. Zudem ist eine derarti¬ ge Bohrung durch einen Kolben hindurch leichter zu führen als durch einen Ventilblock. Eine nähere Erläuterung des Erfindungsgedankens erfolgt nun anhand der Beschreibung eines Ausführungsbeispiels in einer Zeichnung.If the throttle is passed through the stepped piston parallel to the stepped piston to relieve the pressure line between the return pump and the stepped piston, a particularly space-saving solution is obtained. In addition, such a bore is easier to guide through a piston than through a valve block. A more detailed explanation of the concept of the invention will now be given on the basis of the description of an exemplary embodiment in a drawing.
Die einzige Fig. zeigt in symbolischer Darstellung eine er¬ findungsgemäße hydraulische Bremsanlage.The sole FIG. Shows a hydraulic brake system according to the invention in a symbolic representation.
Der Hauptzylinder 1 ist an einem Vorratsbehälter 2 an¬ geschlossen und über ein Bremspedal 3 betätigbar. Vom Haupt¬ zylinder 1 verläuft eine Bremsleitung 4 zu einer Radbremse 5. Eine weitere Radbremse wird ebenfalls von der Bremslei¬ tung 4 versorgt, ist jedoch nicht dargestellt. Dasselbe gilt für einen weiteren Bremskreis II, welcher identisch zu dem dargestellten Bremskreis I aufgebaut sein kann.The master cylinder 1 is connected to a storage container 2 and can be actuated via a brake pedal 3. A brake line 4 runs from the master cylinder 1 to a wheel brake 5. Another wheel brake is also supplied by the brake line 4, but is not shown. The same applies to a further brake circuit II, which can be constructed identically to the brake circuit I shown.
In der Bremsleitung 4 ist ein Trennventil 6 angeordnet, wel¬ ches ebenso wie das näher an der Radbremse 5 eingefügte Ein¬ laßventil 7 ein elektromagnetisch betätigtes, stromlos offe¬ nes 2/2-Wegeventil ist. Parallel zum Trennventil 6 ist ein Rückschlagventil 8 angeordnet, welches einen Druckmittel¬ strom vom Hauptzylinder 1 zur Radbremse 5 erlaubt. In Gegen¬ richtung öffnet ein Überdruckventil 9, welches bei einer Aktivbremsung, also bei geschlossenem Trennventil 6 einen zu hohen Druck in der Bremsleitung 4 unterhalb des Trennventils 6 abbaut. Eine solche Aktivbremsung kann jede Art von Brem¬ seneingriff sein, welche auch ohne Betätigung des Bremspe¬ dals 3 erfolgen kann.Arranged in the brake line 4 is a separating valve 6, which, like the inlet valve 7 inserted closer to the wheel brake 5, is an electromagnetically actuated, normally open 2/2-way valve. A non-return valve 8 is arranged parallel to the isolating valve 6 and allows a pressure medium flow from the master cylinder 1 to the wheel brake 5. In the opposite direction, a pressure relief valve 9 opens, which releases an excessively high pressure in the brake line 4 below the separating valve 6 during active braking, that is to say when the separating valve 6 is closed. Such active braking can be any type of brake intervention, which can also take place without actuation of the brake pedal 3.
Parallel zum Einlaßventil 7 befindet sich ein Rückschlagven¬ til 10, welches einen schnellen Druckabbau aus der Radbremse 5 erlaubt, auch wenn bei Beendigung einer Bremsung das Ein¬ laßventil 7 noch geschlossen sein sollte. Von der Radbremse 5 verläuft eine Rücklaufleitung 11 über ein Auslaßventil 12 zu einem Niederdruckspeicher 13 und von dort aus weiter zur Saugseite einer selbstansaugenden RückfOrderpumpe 14. In die Rücklaufleitung 11 ist zwischen dem Niederdruckspeicher 13 und der Saugseite der Rückförderpumpe 14 ein Rückschlagven- til 15 eingefügt, welches einen Druckmittelstrom nur zur Saugseite der RückfOrderpumpe 14 hin erlaubt. Eine Sauglei¬ tung 16 zweigt von der Bremsleitung 4 zwischen Hauptzylinder 1 und Trennventil 6 ab und führt über ein Umschaltventil 17 ebenfalls zur Saugseite der Rückförderpumpe 14. Diese ist mit ihrer Druckseite über eine Druckleitung 18, welche ein Vordruckrückschlagventil 19 aufweist, an die Bremsleitung 4 zwischen Trennventil 6 und Einlaßventil 7 angeschlossen. Das Vordruckrückschlagventil 19 ist nur für einen Volumenstrom von der Rückförderpumpe 14 zur Bremsleitung 4 hin durchläs¬ sig. Parallel zur Druckleitung 18 befindet sich ein Druck- Volumen-Übersetzer 20. Dieser weist in einer StufenbohrungA non-return valve 10 is located parallel to the inlet valve 7, which allows a rapid pressure reduction from the wheel brake 5, even if the inlet valve 7 should still be closed when braking is ended. A return line 11 runs from the wheel brake 5 via an outlet valve 12 to a low-pressure accumulator 13 and from there to the suction side of a self-priming return pump 14. A non-return valve is inserted into the return line 11 between the low-pressure accumulator 13 and the suction side of the return pump 14. til 15 inserted, which only allows a pressure medium flow to the suction side of the return pump 14. A suction line 16 branches off from the brake line 4 between the master cylinder 1 and the isolation valve 6 and also leads via a changeover valve 17 to the suction side of the return pump 14. The pressure side of the latter is connected to the brake line 4 via a pressure line 18 which has a pre-pressure check valve 19 connected between isolation valve 6 and inlet valve 7. The pre-pressure check valve 19 is only permeable for a volume flow from the return pump 14 to the brake line 4. A pressure-volume translator 20 is located parallel to the pressure line 18. It has a stepped bore
21 einen Stufenkolben 22 auf. Die kleinere Stirnfläche des Stufenkolbens 22 ist an die Druckseite der Rückförderpumpe 14 angeschlossen. Die größere Stirnfläche des Stufenkolbens21 a stepped piston 22. The smaller end face of the stepped piston 22 is connected to the pressure side of the return pump 14. The larger face of the stepped piston
22 weist zur Bremsleitung 4 hin. Diese größere Stirnfläche des Stufenkolbens 22 ist von einer Druckfeder 23 zur Rück¬ förderpumpe 14 hin beaufschlagt. Die Stufe des Stufenkolbens 22 ist an die Atmosphäre angeschlossen. Am bremsleitungs- seitigen Ausgang der Stufenbohrung 21 befindet sich ein Dichtsitz 24, welcher einen kleineren Durchmesser aufweist als die kleinere Stirnfläche des Stufenkolbens 22. Dieser Dichtsitz 24 wirkt mit der größeren Stirnfläche des Stufen¬ kolbens 22 zusammen als Sitzventil. Da es sich um eine rein schematische Darstellung handelt, kann das Sitzventil zwi¬ schen Stufenbohrung 21 und Bremsleitung 4 auch anders ge¬ staltet sein. Es kommt lediglich auf den Öffnungsquerschnitt an, der kleiner sein muß als die kleinere Stirnfläche des Stufenkolbens 22.22 points to the brake line 4. This larger end face of the stepped piston 22 is acted upon by a compression spring 23 towards the return pump 14. The step of the step piston 22 is connected to the atmosphere. At the brake line-side exit of the stepped bore 21 there is a sealing seat 24, which has a smaller diameter than the smaller end face of the stepped piston 22. This sealing seat 24 interacts with the larger end face of the stepped piston 22 as a seat valve. Since this is a purely schematic representation, the seat valve between the stepped bore 21 and the brake line 4 can also be designed differently. All that matters is the opening cross section, which must be smaller than the smaller end face of the stepped piston 22.
Des weiteren ist parallel zur Druckleitung 18 und zum Druck- Volumen-Übersetzer 20 eine Drossel 25 angelegt, welche einen Druckmittelabfluß von der Druckseite der Rückförderpumpe 14 zur Bremsleitung 4 hin erlaubt, wenn bei Stillstand der Rückförderpumpe 14 die Druckfeder 23 den Stufenkolben 22 zur Rückförderpumpe 14 hin verschiebt und damit den von der Druckfeder 23 aufgespannten Volumenspeicher wieder fühlt. Es folgt eine Beschreibung der Funktionsweise der Bremsanla¬ ge.Furthermore, a throttle 25 is provided parallel to the pressure line 18 and to the pressure-volume translator 20, which allows a pressure medium outflow from the pressure side of the return pump 14 to the brake line 4, when the return spring 14 is at a standstill, the compression spring 23 the step piston 22 to the return pump 14 moves and thus feels the volume storage spanned by the compression spring 23 again. A description of the operation of the brake system follows.
Bei einer pedalbetätigten Normalbremsung ohne kritische Schlupfwerte verbleiben alle Ventile in ihrer dargestellten Position. Der Druckaufbau in der Radbremse 5 sowie der Druckabbau erfolgen ausschließlich über die Bremsleitung 4.In the case of pedal-operated normal braking without critical slip values, all valves remain in their position shown. The pressure build-up in the wheel brake 5 and the pressure reduction take place exclusively via the brake line 4.
Wenn während einer pedalbetätigten Bremsung überhöhte Brems¬ schlupfwerte auftreten, so ist eine Blockierschutzregelung notwendig. Die Bremsanlage arbeitet nach dem bekannten Rück¬ förderprinzip. Da in der Bremsleitung 4 vom Hauptzylinder 1 her schon ein Bremsdruck ansteht, vermag auch der Förder¬ druck der Rückförderpumpe 14 den Stufenkolben 22 nicht zu verschieben. Der Druck in der Bremsleitung 4 besitzt eine wesentlich größere Wirkfläche am Stufenkolben 22 als die Druckseite der Rückförderpumpe 14.If excessive brake slip values occur during pedal-operated braking, an anti-lock control system is necessary. The brake system works on the known return conveyor principle. Since a brake pressure is already present in the brake line 4 from the master cylinder 1, the delivery pressure of the return pump 14 is also unable to displace the stepped piston 22. The pressure in the brake line 4 has a much larger effective area on the stepped piston 22 than the pressure side of the return pump 14.
Im Falle einer Aktivbremsung, sei es zur Antriebsschlupf- regelung oder zu einem anderen Regeleingriff wie z.B. zur Giermomentenregelung, ist das Bremspedal 3 nicht betätigt. Der Hauptzylinder 1 ist also drucklos und mit ihm die Brems¬ leitung 4 bis zum Trennventil 6. Letzteres wird zu einer Aktivbremsung geschlossen. Die Rückförderpumpe 14 beginnt zu laufen, wobei zur Öffnung der Saugleitung 16 das stromlos geschlossene Umschaltventil 17 bestromt wird, so daß die Saugleitung 16 eine Verbindung zum Hauptzylinder 1 und somit zum Vorratsbehälter 2 herstellt. Die Rückförderpumpe 14 saugt also Druckmittel an und fördert es in die Druckleitung 18 sowie in den Druck-Volumen-Übersetzerübersetzer 20. Das Vordruckrückschlagventil 19 bewirkt, daß sich zunächst in der Druckleitung 18 und entsprechend an der kleineren Stirn¬ fläche des Stufenkolbens 22 ein Druck aufbaut, bevor sich das geförderte Druckmittel zur Bremsleitung 4 hin fortpflan¬ zen kann. Der an der Druckseite der Rückförderpumpe 14 auf¬ gebaute Druck bewirkt schon bei kleinem Fördervolumen ein Verschieben des Stufenkolbens 22 zur Bremsleitung 4 hin. Da der Bremsleitung 4 jedoch die größere Stirnfläche des Stu¬ fenkolbens 22 zugewandt ist, wird zur Bremsleitung 4 hin ein erheblich größeres Volumen verdrängt, als es zur Verschie¬ bung des Stufenkolbens 22 von der Druckseite der Rückförder¬ pumpe 14 her benötigt wird. Dafür ist das in der Bremslei¬ tung 4 aufgebaute Druckniveau erheblich niedriger als an der Druckseite der Rückförderpumpe 14. Dies ist aber nicht weiter von Bedeutung, da zur Überwindung des Luftspiels der Radbremse 5 kein hoher Druck, sondern nur großes Volumen erforderlich ist. Erst wenn der Stufenkolben 22 sich an sei¬ nen Dichtsitz 24 angelegt hat, ist die Rückförderpumpe 14 in der Lage, einen hohen Druck aufzubauen, welcher das Vor¬ druckrückschlagventil 19 zu überwinden vermag, so daß sich dieser hohe Druck sodann in die Bremsleitung 4 unterhalb des Trennventils 6 fortpflanzt. An der Radbremse 5 angekommen erzielt der Druck in der Bremsleitung 4 eine sofortige Bremswirkung, da ja die Radbremse 5 zuvor schon vorgeladen wurde. Dieser Druck kann nicht dazu führen, daß der Stufen¬ kolben 22 wieder zur Druckseite der Rückförderpumpe zurück¬ geschoben wird, da der Dichtsitz 24 einen wesentlich kleine¬ ren Durchmesser hat als der Kolbenabschnitt kleineren Durch¬ messers. Der Druck an der Druckseite der Rückförderpumpe 14 verhindert also ein Zurückschieben des Stufenkolbens 22. Eine Druckregelung während einer Aktivbremsung erfolgt durch Betätigung des Einlaßventils 7 und des Auslaßventils 12 auf bekannte Weise.In the case of active braking, be it for traction control or for another control intervention such as yaw moment control, the brake pedal 3 is not actuated. The master cylinder 1 is therefore depressurized and with it the brake line 4 to the isolating valve 6. The latter is closed for active braking. The return pump 14 starts to run, whereby the normally closed changeover valve 17 is energized to open the suction line 16, so that the suction line 16 establishes a connection to the master cylinder 1 and thus to the reservoir 2. The return pump 14 therefore sucks in pressure medium and conveys it into the pressure line 18 and into the pressure-volume translator 20 before the pumped pressure medium can propagate to the brake line 4. The pressure built up on the pressure side of the return pump 14 has an effect even with a small delivery volume Moving the stepped piston 22 towards the brake line 4. However, since the larger end face of the step piston 22 faces the brake line 4, a considerably larger volume is displaced towards the brake line 4 than is required for the displacement of the step piston 22 from the pressure side of the return pump 14. For this purpose, the pressure level built up in the brake line 4 is considerably lower than on the pressure side of the return pump 14. However, this is of no further importance since it is not a high pressure, but only a large volume that is required to overcome the air play of the wheel brake 5. Only when the stepped piston 22 has applied to its sealing seat 24 is the return pump 14 able to build up a high pressure which can overcome the pre-pressure check valve 19, so that this high pressure then passes into the brake line 4 below of the isolation valve 6 reproduces. Arrived at the wheel brake 5, the pressure in the brake line 4 has an immediate braking effect, since the wheel brake 5 has already been preloaded. This pressure cannot lead to the stepped piston 22 being pushed back to the pressure side of the return pump, since the sealing seat 24 has a much smaller diameter than the piston section of smaller diameter. The pressure on the pressure side of the return pump 14 thus prevents the stepped piston 22 from being pushed back. Pressure control during active braking is carried out by actuating the inlet valve 7 and the outlet valve 12 in a known manner.
Bei Beendigung einer Aktivbremsung wird das Trennventil 6 geöffnet, so daß sich der Bremsdruck über die Bremsleitung 4 und den Hauptzylinder 1 in den Vorratsbehälter 2 abbauen kann. Die Pumpe 14 wird abgeschaltet, so daß kein weiteres Druckmittel gefördert wird. Der an der Druckseite der Rück¬ förderpumpe 14 verbleibende Restdruck baut sich langsam über die Drossel 25 ab. Hierdurch ist die Druckfeder 23 in der Lage, den Kolben 22 wieder zur Rückförderpumpe 14 hin bis in seine dargestellte Anschlagposition zu verschieben. Der von der Druckfeder 23 aufgespannte Volumenspeicher ist somit wieder gefüllt und bereit zu einer erneuten Aktivbremsung.When active braking has ended, the isolating valve 6 is opened so that the brake pressure can be reduced via the brake line 4 and the master cylinder 1 into the reservoir 2. The pump 14 is switched off so that no further pressure medium is delivered. The residual pressure remaining on the pressure side of the return pump 14 slowly dissipates via the throttle 25. As a result, the compression spring 23 is able to move the piston 22 back to the return pump 14 into the stop position shown. The of the compression spring 23 spanned volume storage is thus refilled and ready for another active braking.
Um eine platzsparende Anordnung des Druck-Volumen-Überset¬ zers 20 mit der parallel geschalteten Drossel 25 zu errei¬ chen, kann die hier schematisch parallel zum Stufenkolben 22 dargestellte Drossel 25 auch durch den Stufenkolben 22 hin¬ durchverlaufen. Sie verbindet dann die beiden Stirnflächen des Stufenkolbens, also die Druckseite der Rückförderpumpe 14 mit der Bremsleitung 4. Die Drossel 25 kann dabei einen sehr engen Querschnitt aufweisen, so daß sie den Aufbau ei¬ nes Staudrucks an der Druckseite der Rückförderpumpe 14 bei einer Aktivbremsung nicht behindert. Denn das zur Rückstel¬ lung des Stufenkolbens 22 zu verdrängende Druckmittelvolumen ist vergleichsweise gering im Verhältnis zu der im Volumen¬ speicher enthaltenen Druckmittelmenge. In order to achieve a space-saving arrangement of the pressure-volume converter 20 with the throttle 25 connected in parallel, the throttle 25 shown here schematically parallel to the stepped piston 22 can also pass through the stepped piston 22. It then connects the two end faces of the stepped piston, that is to say the pressure side of the return pump 14 with the brake line 4. The throttle 25 can have a very narrow cross section, so that it does not build up a dynamic pressure on the pressure side of the return pump 14 during active braking with special needs. This is because the pressure medium volume to be displaced in order to reset the step piston 22 is comparatively small in relation to the quantity of pressure medium contained in the volume accumulator.

Claims

Patentansprüche claims
1. Hydraulische Bremsanlage mit einer Einrichtung zur Ak¬ tivbremsung, mit einem pedalbetätigten Hauptzylinder (1), der an einen Vorratsbehälter (2) angeschlossen ist, mit einer Bremsleitung (4) vom Hauptzylinder (1) zu min¬ destens einer Radbremse (5), mit einem Trennventil (6) in der Bremsleitung, mit einer Rücklaufleitung (11) von der Radbremse (5) zur Saugseite einer Rückförderpumpe (14), die selbstansaugend ist, mit einer Saugleitung (16) von der Bremsleitung (4) zwischen Hauptzylinder (1) und Trennventil (6) zur Saugseite der Rückförderpumpe (14) sowie mit einer Druckleitung (18) von der Drucksei¬ te der Rückförderpumpe (14) zur Bremsleitung (4) zwi¬ schen Trennventil (6) und Radbremse (5) und mit einem Volumenspeicher zur schnellen Füllung der Radbremse (5) bei einer Aktivbremsung, dadurch gekennzeichnet, daß der Volumenspeicher von einem Druck-Volumen-Übersetzer (20) gebildet ist, der parallel zur Druckleitung (18) ange¬ legt ist und welcher einen axial verschiebbaren Stufen¬ kolben (22) aufweist, dessen kleinere Stirnfläche an der Druckseite der Rückförderpumpe (14) und dessen größere Stirnfläche an die Bremsleitung (4) angeschlossen ist, wobei in der parallel verlaufenden Druckleitung (18) Mittel zur Erzeugung eines Druckgefälles zwischen Rück¬ förderpumpe (14) und Bremsleitung (4) angeordnet sind.1. Hydraulic brake system with a device for active braking, with a pedal-operated master cylinder (1) which is connected to a reservoir (2), with a brake line (4) from the master cylinder (1) to at least one wheel brake (5) , with a isolating valve (6) in the brake line, with a return line (11) from the wheel brake (5) to the suction side of a return pump (14) that is self-priming, with a suction line (16) from the brake line (4) between the master cylinder ( 1) and isolation valve (6) to the suction side of the return pump (14) and with a pressure line (18) from the pressure side of the return pump (14) to the brake line (4) between the isolation valve (6) and wheel brake (5) and with a volume accumulator for rapid filling of the wheel brake (5) during active braking, characterized in that the volume accumulator is formed by a pressure-volume translator (20) which is parallel to the pressure line (18) and which axially displaces one another Levelable piston (22), the smaller end face of which is connected to the pressure side of the return pump (14) and the larger end face of which is connected to the brake line (4), means in the parallel pressure line (18) being used to generate a pressure gradient between the return line Delivery pump (14) and brake line (4) are arranged.
2. Bremsanlage nach Anspruch 1, dadurch gekennzeichnet, daß die Mittel ein Vordruckventil (19) umfassen, welches von der Bremsleitung (4) zur Druckseite der Rückförderpumpe (14) sperrt.2. Brake system according to claim 1, characterized in that the means comprise a pre-pressure valve (19) which blocks from the brake line (4) to the pressure side of the return pump (14).
3. Bremsanlage nach Anspruch 1 oder 2, dadurch gekennzeich¬ net, daß der Stufenkolben (22) zur Druckseite der Rück¬ förderpumpe (14) hin federbelastet ist. 3. Brake system according to claim 1 or 2, characterized gekennzeich¬ net that the stepped piston (22) to the pressure side of the return pump (14) is spring-loaded.
4. Bremsanlage nach Anspruch 1, 2 oder 3, dadurch gekenn¬ zeichnet, daß dem Druck-Volumen-Übersetzer (20) und der Druckleitung (18) eine Drossel (25) parallelgeschaltet ist.4. Brake system according to claim 1, 2 or 3, characterized gekenn¬ characterized in that the pressure-volume translator (20) and the pressure line (18), a throttle (25) is connected in parallel.
5. Bremsanlage nach einem der Ansprüche 1 bis 4, dadurch gekennzeichnet, daß nach Überwindung eines bestimmten Kolbenhubs des Stufenkolbens (22) ein Sitzventil (24) schließt, welches die Verbindung zwischen Bremsleitung (4) und der größeren Kolbenstirnfläche unterbricht und welches bremsleitungsseitig in Öffnungsrichtung eine Wirkfläche aufweist, die kleiner ist als die kleinere Kolbenstirnfläche.5. Brake system according to one of claims 1 to 4, characterized in that after overcoming a certain piston stroke of the stepped piston (22) closes a seat valve (24) which interrupts the connection between the brake line (4) and the larger piston end face and which side of the brake line in the opening direction has an effective area that is smaller than the smaller piston end face.
6. Bremsanlage nach Anspruch 4 oder 5, dadurch gekennzeich¬ net, daß die Drossel (25) innerhalb des Stufenkolbens (22) angelegt ist und die beiden Stirnseiten des Stufen¬ kolbens (22) miteinander verbindet. 6. Brake system according to claim 4 or 5, characterized gekennzeich¬ net that the throttle (25) is applied within the step piston (22) and connects the two end faces of the step piston (22) with each other.
EP97902176A 1996-01-20 1997-01-17 Hydraulic brake system with device for active braking Ceased EP0874749A1 (en)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
DE19602057 1996-01-20
DE19602057A DE19602057A1 (en) 1996-01-20 1996-01-20 Hydraulic braking system with a device for active braking
PCT/EP1997/000190 WO1997026168A1 (en) 1996-01-20 1997-01-17 Hydraulic brake system with device for active braking

Publications (1)

Publication Number Publication Date
EP0874749A1 true EP0874749A1 (en) 1998-11-04

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US (1) US6195995B1 (en)
EP (1) EP0874749A1 (en)
JP (1) JP2000503272A (en)
DE (1) DE19602057A1 (en)
WO (1) WO1997026168A1 (en)

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DE19602057A1 (en) 1997-07-24
JP2000503272A (en) 2000-03-21
US6195995B1 (en) 2001-03-06
WO1997026168A1 (en) 1997-07-24

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