EP2459422A1 - Hydraulic vehicle brake system, vehicle equipped with such a brake system, and method for operating a hydraulic vehicle brake system - Google Patents

Hydraulic vehicle brake system, vehicle equipped with such a brake system, and method for operating a hydraulic vehicle brake system

Info

Publication number
EP2459422A1
EP2459422A1 EP10728145A EP10728145A EP2459422A1 EP 2459422 A1 EP2459422 A1 EP 2459422A1 EP 10728145 A EP10728145 A EP 10728145A EP 10728145 A EP10728145 A EP 10728145A EP 2459422 A1 EP2459422 A1 EP 2459422A1
Authority
EP
European Patent Office
Prior art keywords
brake
vehicle
hydraulic
brake system
chamber
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.)
Withdrawn
Application number
EP10728145A
Other languages
German (de)
French (fr)
Inventor
Stefan Strengert
Michael Kunz
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.)
Robert Bosch GmbH
Original Assignee
Robert Bosch GmbH
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 Robert Bosch GmbH filed Critical Robert Bosch GmbH
Publication of EP2459422A1 publication Critical patent/EP2459422A1/en
Withdrawn legal-status Critical Current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
    • B60T8/48—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
    • 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
    • B60T1/00—Arrangements of braking elements, i.e. of those parts where braking effect occurs specially for vehicles
    • B60T1/02—Arrangements of braking elements, i.e. of those parts where braking effect occurs specially for vehicles acting by retarding wheels
    • B60T1/10—Arrangements of braking elements, i.e. of those parts where braking effect occurs specially for vehicles acting by retarding wheels by utilising wheel movement for accumulating energy, e.g. driving air compressors
    • 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
    • B60T13/58—Combined or convertible systems
    • B60T13/585—Combined or convertible systems comprising friction brakes and retarders
    • B60T13/586—Combined or convertible systems comprising friction brakes and retarders the retarders being of the electric type
    • 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
    • B60T8/26—Arrangements for adjusting wheel-braking force to meet varying vehicular or ground-surface conditions, e.g. limiting or varying distribution of braking force characterised by producing differential braking between front and rear wheels
    • B60T8/266—Arrangements for adjusting wheel-braking force to meet varying vehicular or ground-surface conditions, e.g. limiting or varying distribution of braking force characterised by producing differential braking between front and rear wheels using valves or actuators with external control means
    • B60T8/268—Arrangements for adjusting wheel-braking force to meet varying vehicular or ground-surface conditions, e.g. limiting or varying distribution of braking force characterised by producing differential braking between front and rear wheels using valves or actuators with external control means using the valves of an ABS, ASR or ESP system
    • 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
    • B60T8/4072—Systems in which a driver input signal is used as a control signal for the additional fluid circuit which is normally used for braking
    • B60T8/4081—Systems with stroke simulating devices for driver input
    • 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
    • B60T8/442—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 the booster being a fluid return pump, e.g. in combination with a brake pedal force booster
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60T—VEHICLE BRAKE CONTROL SYSTEMS OR PARTS THEREOF; BRAKE CONTROL SYSTEMS OR PARTS THEREOF, IN GENERAL; ARRANGEMENT OF BRAKING ELEMENTS ON VEHICLES IN GENERAL; PORTABLE DEVICES FOR PREVENTING UNWANTED MOVEMENT OF VEHICLES; VEHICLE MODIFICATIONS TO FACILITATE COOLING OF BRAKES
    • B60T13/00—Transmitting braking action from initiating means to ultimate brake actuator with power assistance or drive; Brake systems incorporating such transmitting means, e.g. air-pressure brake systems
    • B60T13/10—Transmitting braking action from initiating means to ultimate brake actuator with power assistance or drive; Brake systems incorporating such transmitting means, e.g. air-pressure brake systems with fluid assistance, drive, or release
    • B60T13/12—Transmitting braking action from initiating means to ultimate brake actuator with power assistance or drive; Brake systems incorporating such transmitting means, e.g. air-pressure brake systems with fluid assistance, drive, or release the fluid being liquid
    • B60T13/14—Transmitting braking action from initiating means to ultimate brake actuator with power assistance or drive; Brake systems incorporating such transmitting means, e.g. air-pressure brake systems with fluid assistance, drive, or release the fluid being liquid using accumulators or reservoirs fed by pumps
    • B60T13/142—Systems with master cylinder

Definitions

  • the invention relates to a hydraulic vehicle brake system and to a method for operating a hydraulic vehicle brake system according to the preamble of claim 1 or 13.
  • State of the art
  • a hydraulic vehicle brake system which comprises two brake circuits which are to be actuated by a brake pedal of the vehicle via a common master cylinder. Each brake circuit acts on two wheel brake units on the vehicle wheels.
  • Vehicle brake system comprises a hydraulic pump unit with a hydraulic pump per brake circuit and a common, both hydraulic pumps actuating electric motor.
  • driver assistance systems can be supported, for example an electronic stability program ESP.
  • the invention has for its object to design the braking operation in a vehicle that is equipped with a hydraulic vehicle brake system, in such a way that acts on the vehicle 1925bremsmo- ment unnoticed by the driver.
  • the inventive hydraulic vehicle brake system is provided in a conventional manner with a master cylinder, which is actuated by a brake pedal in the vehicle, further comprising at least one storage chamber for receiving the hydraulic brake fluid, a hydraulic pump and at least one wheel brake in a brake circuit of the vehicle brake system are provided. Furthermore, the vehicle brake system has a pedal travel simulator which is equipped with a primary chamber and a secondary chamber and a displaceable piston separating the two chambers. The primary chamber is connected to the master cylinder or a
  • the hydraulic pump is connected to the storage chamber and that the hydraulic pump via control signals of a control or control unit for generating a Radbremsmoments in the wheel brake is controllable.
  • the pedal travel of the brake Pedals and / or the pedal pressure generated by the driver is used for determining a desired braking torque, wherein the pedal movement over the displacement of hydraulic fluid from the master cylinder is not directly in the Radbremsaku effective, but rather a shift of hydraulic fluid via the pedal travel simulator in the downstream storage unit takes place.
  • the hydraulic pump draws hydraulic fluid from the storage chamber and pressurizes the fluid with a brake pressure which is effective in the wheel brake unit.
  • the control of the hydraulic pump via the control signals of the control or
  • Control unit allows a variable adaptation to the current braking situation in the vehicle.
  • the actuation of the hydraulic pump is thus not necessarily coupled to the actuation of the brake pedal, so that other influences in the control of the hydraulic pump can be taken into account.
  • additional braking torques which originate from additional brake devices, in particular electric motors which operate in recuperative operation and which are arranged in the drive train of the vehicle.
  • the additional braking torques of such auxiliary brake devices and the mechanical braking torques which are generated in the wheel brake units of the vehicle brake systems by actuation of the hydraulic pump determine this
  • Total braking torque which corresponds to the predetermined braking torque given by the driver via the pedal actuation.
  • the hydraulic pump With the control of the hydraulic pump sucks this from the storage chamber hydraulic fluid and acts on this with the in the control unit or control unit determined brake pressure.
  • the hydraulic pump is advantageously connected via a valve with no current to the master cylinder or the reservoir associated with this and promotes hydraulic fluid from the reservoir into the brake circuit.
  • the primary chamber of the pedal travel simulator is expediently connected via an adjustable hydraulic valve to the brake circuit containing the at least one wheel brake unit.
  • the secondary chamber is expediently connected to the storage chamber via a closable setting device.
  • the hydraulic valve which is connected downstream of the primary chamber, is preferably configured as a normally open valve, which is in the open position in the event of a failure of the electrical power supply, so that the primary chamber of the pedal travel simulator is hydraulically connected to the wheel brake units.
  • the adjusting device which is associated with the secondary chamber is designed to be normally closed, so that in case of failure of the power supply, the connection between the secondary chamber of the pedal travel and the storage chamber is interrupted.
  • the closable adjusting device which is located in the flow path between the secondary chamber of the pedal travel simulator and the storage chamber, is designed according to a first preferred embodiment as an adjustable, the secondary chamber downstream hydraulic valve which is normally closed.
  • the adjusting device is integrated in the pedal travel simulator, wherein the piston is part of the adjusting device and is released at a displacement of the piston between the starting position and the displaced in the direction of the secondary chamber, the flow path to the storage chamber. This is realized, for example, in that in the starting position in which no hydraulic fluid has yet been conveyed from the master brake cylinder into the primary chamber of the pedal travel simulator, a part of the piston closes an outflow opening in the direction of the downstream storage chamber.
  • the pedal travel simulator including the associated structural units, to be integrated only in a single brake circuit of the vehicle brake system, whereas a conventionally provided second brake circuit is implemented in the conventional manner without such a pedal travel simulator.
  • a first brake circuit acts on the wheel brake units on the front axle and the second brake circuit on the wheel brake units on the rear axle
  • a torque distribution between the brake circuits can be realized by closing a hydraulic valve between the reservoir of the master brake cylinder and the brake circuit without a pedal travel simulator.
  • each hydraulic pump is assigned its own electric motor drive.
  • a brake force distribution between the wheel brake units of this brake circuit can also be carried out within the brake circuit equipped with the pedal travel simulator by controlling the intake and exhaust valves of each wheel brake unit in different ways.
  • the hydraulic vehicle brake system is preferably used in hybrid vehicles, the drive source as an electric motor and an internal combustion engine exhibit. To charge the electrical energy storage, the electric motor is to be operated in recuperation or generator operation, in which electric braking torques in the electric motor take effect, which have a braking effect on the drive train. The electrical braking torques add up to the mechanical wheel braking torques that are generated by the hydraulic vehicle brake system.
  • the hydraulic vehicle brake system according to the invention can also be used in vehicles which have exclusively an electric motor as drive source.
  • the hydraulic vehicle brake system preferably has only in a brake circuit on a pedal travel simulator with the associated units.
  • both brake circuits are each equipped with a pedal travel simulator and the associated structural units.
  • the method according to the invention requires a hydraulic vehicle brake system which has a pedal travel simulator with primary chamber and secondary chamber and intermediate displaceable piston at least in one brake circuit, wherein the secondary chamber is fluidically connected to a storage chamber and hydraulic fluid is conveyed from the storage chamber into the brake circuit via a hydraulic pump can.
  • the method is carried out in such a way that initially in a first method step from the brake pedal position, a desired braking torque is determined, which corresponds to the driver's request. Thereafter, it is determined in a next method step, whether and at what level in an additional brake device, an additional braking torque is currently generated. Finally, in a further method step, the hydraulic pump is actuated in such a way that the pressure generated by the wheel brake unit
  • Radbremsmoment from the difference between the predetermined by the driver Target braking torque and the additional braking torque is calculated. This procedure ensures that regardless of a currently applied additional braking torque always desired by the driver target braking torque is effective.
  • a decoupling between the brake pedal pressure and the brake pressure of the hydraulic fluid in the brake circuit is achieved by the special design of the one brake circuit with the pedal travel simulator.
  • Fig. 1 is a hydraulic circuit diagram of a vehicle brake system with a front-axle brake circuit and a rear brake circuit, wherein in the rear axle brake circuit a pedal travel simulator is integrated with a primary chamber and a secondary chamber separated by a piston and both the primary chamber and the secondary chamber each have a hydraulic valve is downstream,
  • Fig. 2 is a vehicle brake system which is designed similar to that of FIG. 1, but with an integrated into the pedal travel control device for opening and closing an outflow opening in the
  • FIG. 3 shows a flow chart with individual method steps for carrying out the method for operating the vehicle brake system.
  • the hydraulic vehicle brake system 1 in a motor vehicle has a front-axle brake circuit 2 and a rear-axle brake circuit 3 which are connected to a common brake system
  • Master cylinder 4 are connected, which is operated by a brake pedal 6 by the driver.
  • the master cylinder 4 is a brake fluid reservoir 5 assigned.
  • the pedal travel of the brake pedal 6 is determined by means of a pedal travel sensor 7.
  • Wheel brake units 8 and 9 are actuated on the left and right front wheels via the front axle brake circuit 2, and wheel brake units 10 and 11 on the left and right rear wheels via the rear axle brake circuit 3.
  • Each brake circuit 2, 3 is associated with a controllable changeover valve 12 which is connected to the Hauptbremszy- cylinder 4, wherein the changeover valves are open in their normally-off normal position.
  • Each switching valve 12 has a check valve arranged in parallel, which can be flowed through by the master cylinder to the respective wheel brake units. Between the switching valves 12 and the respective wheel brake units 8 to
  • the wheel brake units 8 to 11 are each associated with a normally closed exhaust valve 14, which are connected to the suction side of a pump unit 15, the pump unit 15, which is in particular part of an ESP system (electronic stability program), a first hydraulic pump 16 in the front-axle brake circuit 2 and a second hydraulic pump 17 in the rear axle brake circuit 3 and a two hydraulic pumps 16, 17 jointly actuated electric drive motor 18 includes.
  • the pressure side of the hydraulic pumps 16 and 17 is at a line section between the switching valve
  • the suction sides of the hydraulic pumps 16 and 17 are each connected to a main switching valve 19, which is hydraulically connected to the master cylinder 4.
  • the main switching valves 19, which are closed in the de-energized state, can be opened, whereupon the hydraulic pumps 16 and 17 draw in hydraulic fluid directly from the master brake cylinder 4 or the associated brake fluid reservoir 5.
  • Brake pressure build-up here is independent of an operation of the brake pedal by the driver.
  • the suction side of the hydraulic pumps 16 and 17 also communicates with each of a hydraulic accumulator and a storage chamber 20 for receiving
  • the storage chambers 20 are also with the exhaust valves 14 containing line sections flow-connected.
  • the storage chambers 20 are used for temporary storage of brake fluid, which was discharged from the wheel brake units 8 to 11 during a dynamic driving engagement via the exhaust valves 14.
  • Each brake circuit 2, 3 also has a pressure sensor 21 or 22 for measuring the brake pressure in the respective brake circuit.
  • the pressure sensor 21 in the front-axle brake circuit 2 is located between the master cylinder 4 and the main switching valve 19.
  • the pressure sensor 22 in the rear-axle brake circuit 3 is disposed between the switching valve 12 and the intake valves 13.
  • the vehicle brake system 1 is also associated with a control or control unit 23, which generates control signals in response to input signals, in particular for acting upon the hydraulic pumps 16 and 17 or the electric drive motor 18 assigned to the pumps.
  • a control or control unit 23 As input signals of the control unit 23, the sensor signals of the sensors of the vehicle brake system are supplied.
  • signals of further units or actuating devices in the vehicle can be processed in the control unit or control unit 23, for example additional braking torques of auxiliary brake devices outside the hydraulic vehicle brake system, such as in the
  • the rear axle brake circuit 3 has an additional unit 24, which is connected downstream of the master brake cylinder 4 in the brake circuit 3.
  • the auxiliary unit 24 comprises a pedal travel simulator 25, which is flow-connected to the master cylinder 4, and two hydraulic valves 26 and 27 downstream of the pedal travel simulator 25, of which the first hydraulic valve 26 is connected between a primary chamber 28 of the pedal travel simulator 25 and the changeover valve 12 and the second hydraulic valve 27 is disposed between a secondary chamber 29 of the pedal travel simulator 25 and the storage chamber 20.
  • the primary chamber 28 of the pedal travel simulator 25 is fluidly connected to the master cylinder 4. Between primary chamber 28 and secondary chamber 29, a piston 30 is slidably disposed. As soon as brake fluid flows from the master brake cylinder 4 into the primary chamber 28, the piston 30 is shifted from the starting position shown in FIG.
  • the hydraulic valve 26 is designed as a normally open valve
  • the hydraulic valve 27 is designed as a normally closed valve, whereby a Fallebene is realized because with de-energized valves direct hydraulic penetration between the master cylinder 4 via the primary chamber 28 and the open hydraulic valve 26 to the wheel brake 10th and 11 is given.
  • the second hydraulic valve 27 is normally closed in the fallback mode, so that no hydraulic fluid can flow out of the secondary chamber 29 of the pedal travel simulator 25 in the direction of the storage chamber 20.
  • the hydraulic valves 26 and 27 are energized, so that the hydraulic valve 26 connected downstream of the primary chamber 28 is closed and the hydraulic valve 27 connected downstream of the secondary chamber 29 is opened.
  • hydraulic fluid flows from the master cylinder 4 into the primary chamber 28 of the pedal travel simulator 25, whereupon the piston 30 is displaced in the direction of the secondary chamber 29 and the brake fluid therein is displaced into the storage chamber 20 via the open hydraulic valve 27.
  • brake fluid is sucked from the storage chamber 20 and fed to the wheel brake units 10 and 11 at a desired brake pressure.
  • the brake pressure here depends on the operation of the hydraulic pump 17, which is set via control signals of the control unit 23.
  • the pressure reduction can be carried out either via the switching valve 12 or the exhaust valve 14 depending on the driving situation.
  • the pressure is reduced by opening the changeover valve 12, so that brake fluid from the wheel brake units 10 and 11 flows into the storage chamber 20 via the open changeover valve 12 and the likewise open hydraulic valve 27.
  • the exhaust valves 14 are opened so that brake fluid from the wheel brake units 10 and 11 flows directly into the storage chamber 20 via the opened exhaust valves 14.
  • Fig. 2 shows a variant is shown, in which the auxiliary unit 24 is executed with the pedal travel simulator 25 in comparison to the embodiment of FIG. 1 in a modified manner.
  • the pedal travel simulator 25 has a primary chamber 28 and a secondary chamber 29, between which the displaceable piston 30 is arranged.
  • Primary chamber 28 is the normally open hydraulic valve 26 downstream.
  • the secondary chamber 29 is but in contrast to the first embodiment, no hydraulic valve connected downstream. Rather, the secondary chamber 29 is opened and closed by means of a special embodiment of the piston 30, which is shown in its initial position in FIG. 2, in which no brake fluid has yet flowed from the master brake cylinder into the primary chamber 28. A portion 30a of the piston 30 closes in the starting position an outflow opening in the secondary chamber 29 in the direction of storage chamber 20. As soon as brake fluid from the master cylinder 4 flows into the primary chamber 28 and the piston 30 is moved from the starting position in the direction of the secondary chamber 29 passes a second portion 30 b of the piston 30 in the region of the discharge opening of the secondary chamber 29, whereupon the discharge opening is released, so that the hydraulic fluid located in the secondary chamber 29 can flow into the storage chamber 20.
  • the special embodiment of the pedal travel simulator 25 can also be used for a pressure reduction in the rear axle brake circuit 3 in the normal case.
  • a first method step 40 the pedal travel s traveled on actuation of the brake pedal is measured with the aid of the pedal travel sensor and a desired braking torque M Br determined therefrom.
  • a desired braking torque M Br determined therefrom.
  • additional braking torques are currently active in the vehicle, for example electric braking torques of an electric drive motor of the vehicle operating in recuperation mode. such Braking torques M e ⁇ be detected in the control or control unit and further processed.
  • a wheel braking M w for the Hinterachsbrems- circle is determined in step 42.
  • the mechanical wheel braking torque M w generated in the wheel brake units of the rear wheels is generated by acting on the hydraulic pump for the Schuachsbremsnik, wherein the wheel braking is set in such a manner that in the vehicle taking into account the additional braking torque M e ⁇ the desired braking torque M Br takes effect.
  • the setting of the wheel brake torque M w takes place in method step 43 by acting on the hydraulic pump for the rear axle brake circuit by means of the electric motor drive assigned to the hydraulic pump.

Landscapes

  • Engineering & Computer Science (AREA)
  • Transportation (AREA)
  • Mechanical Engineering (AREA)
  • Physics & Mathematics (AREA)
  • Fluid Mechanics (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Regulating Braking Force (AREA)

Abstract

The invention relates to a hydraulic vehicle brake system, comprising a pedal travel simulator (25) having a primary chamber (28) and a secondary chamber (29), between which a piston (30) is slidably arranged, wherein the secondary chamber (29) is flow-connected to a storage chamber (20). Brake fluid from the storage chamber (20) can be conveyed by way of a hydraulic pump (17).

Description

Beschreibung  description
Titel title
HYDRAULISCHE FAHRZEUGBREMSANLAGE, FAHRZEUG MIT EINER DERARTIGEN  HYDRAULIC VEHICLE BRAKING SYSTEM, VEHICLE WITH SUCH A
BREMSANLAGE UND VERFAHREN ZUM BETRIEB EINER BRAKING SYSTEM AND METHOD FOR OPERATING ONE
HYDRAULISCHEN FAHRZEUGBREMSANLAGE HYDRAULIC VEHICLE BRAKING SYSTEM
Die Erfindung bezieht sich auf eine hydraulische Fahrzeugbremsanlage und auf ein Verfahren zum Betrieb einer hydraulischen Fahrzeugbremsanlage nach dem Oberbegriff des Anspruches 1 bzw. 13. Stand der Technik The invention relates to a hydraulic vehicle brake system and to a method for operating a hydraulic vehicle brake system according to the preamble of claim 1 or 13. State of the art
Aus der DE 10 2007 020 503 A1 ist eine hydraulische Fahrzeugbremsanlage bekannt, welche zwei Bremskreise umfasst, die über einen gemeinsamen Hauptbremszylinder von einem Bremspedal des Fahrzeugs zu betätigen sind. Jeder Bremskreis beaufschlagt zwei Radbremseinheiten an den Fahrzeugrädern. DieFrom DE 10 2007 020 503 A1 a hydraulic vehicle brake system is known which comprises two brake circuits which are to be actuated by a brake pedal of the vehicle via a common master cylinder. Each brake circuit acts on two wheel brake units on the vehicle wheels. The
Fahrzeugbremsanlage weist eine Hydropumpeneinheit mit einer Hydropumpe pro Bremskreis und einem gemeinsamen, beide Hydropumpen betätigenden E- lektromotor auf. Über die Ansteuerung der Pumpeneinheit können Fahrerassistenzssysteme unterstützt werden, beispielsweise ein elektronisches Stabili- tätsprogramm ESP. Vehicle brake system comprises a hydraulic pump unit with a hydraulic pump per brake circuit and a common, both hydraulic pumps actuating electric motor. By controlling the pump unit, driver assistance systems can be supported, for example an electronic stability program ESP.
Bei hydraulischen Bremsanlagen, die in Hybridfahrzeugen mit einem Elektromotor und einem Verbrennungsmotor als Antriebsquelle eingesetzt werden, entsteht das Problem, dass im Rekuperations- bzw. Generatorbetrieb des Elektromotors ein auf das Fahrzeug wirkendes elektrisches Bremsmoment erzeugt wird, welches beim Bremsvorgang beim Betätigen der mechanisch wirkenden Radbremse berücksichtigt werden muss. Da die rekuperative Bremse nur zur Verfügung steht, falls der elektrische Energiespeicher nicht vollständig aufgeladen ist, können je nach Ladungszustand des elektrischen Energiespeichers Bremssituatio- nen mit und ohne elektrischem Bremsmoment entstehen. Da die von den verschiedenen Bremseinrichtungen herrührenden Bremsmomente kumulativ auf das Fahrzeug wirken, muss der Wegfall bzw. das Zuschalten eines elektrischen Bremsmoments vom Fahrer mit einem geänderten mechanischen Bremsmoment kompensiert werden, was eine Änderung der Bremspedalstellung erfordert. Offenbarung der Erfindung In hydraulic brake systems, which are used in hybrid vehicles with an electric motor and an internal combustion engine as the drive source, the problem arises that in the recuperation or generator operation of the electric motor acting on the vehicle electrical braking torque is generated, which during braking operation when operating the mechanically acting wheel brake must be taken into account. Since the recuperative brake is available only if the electrical energy storage is not fully charged, depending on the state of charge of the electrical energy storage brake situations with and without electrical braking torque can arise. Since the braking torques resulting from the various braking devices accumulate on the Act vehicle, the elimination or the connection of an electric braking torque must be compensated by the driver with a modified mechanical braking torque, which requires a change in the brake pedal position. Disclosure of the invention
Der Erfindung liegt die Aufgabe zugrunde, den Bremsvorgang in einem Fahrzeug, das mit einer hydraulischen Fahrzeugbremsanlage ausgestattet ist, in der Weise auszugestalten, dass ein auf das Fahrzeug wirkendes Zusatzbremsmo- ment vom Fahrer unbemerkt bleibt. The invention has for its object to design the braking operation in a vehicle that is equipped with a hydraulic vehicle brake system, in such a way that acts on the vehicle Zusatzbremsmo- ment unnoticed by the driver.
Diese Aufgabe wird erfindungsgemäß bei einer hydraulischen Fahrzeugbremsanlage mit den Merkmalen des Anspruches 1 und bei einem Verfahren zum Betrieb einer hydraulischen Fahrzeugbremsanlage mit den Merkmalen des Anspruches 13 gelöst. Die Unteransprüche geben zweckmäßige Weiterbildungen an. This object is achieved in a hydraulic vehicle brake system with the features of claim 1 and in a method for operating a hydraulic vehicle brake system with the features of claim 13. The dependent claims indicate expedient developments.
Die erfindungsgemäße, hydraulische Fahrzeugbremsanlage ist in an sich bekannter Weise mit einem Hauptbremszylinder versehen, der von einem Bremspedal im Fahrzeug betätigbar ist, wobei des Weiteren mindestens eine Speicher- kammer zur Aufnahme des hydraulischen Bremsfluids, eine Hydraulikpumpe und mindestens eine Radbremseinheit in einem Bremskreis der Fahrzeugbremsanlage vorgesehen sind. Des Weiteren weist die Fahrzeugbremsanlage einen Pedalwegsimulator auf, der mit einer Primärkammer und einer Sekundärkammer und einem die beiden Kammern separierenden, verschieblichen Kolben ausge- stattet ist. Die Primärkammer ist mit dem Hauptbremszylinder bzw. einem demThe inventive hydraulic vehicle brake system is provided in a conventional manner with a master cylinder, which is actuated by a brake pedal in the vehicle, further comprising at least one storage chamber for receiving the hydraulic brake fluid, a hydraulic pump and at least one wheel brake in a brake circuit of the vehicle brake system are provided. Furthermore, the vehicle brake system has a pedal travel simulator which is equipped with a primary chamber and a secondary chamber and a displaceable piston separating the two chambers. The primary chamber is connected to the master cylinder or a
Hauptbremszylinder zugeordneten Reservoir strömungsverbunden, die Sekundärkammer mit der Speicherkammer zur Aufnahme des hydraulischen Bremsfluids. Des Weiteren ist vorgesehen, dass die Hydraulikpumpe mit der Speicherkammer verbunden ist und dass die Hydraulikpumpe über Stellsignale einer Re- gel- bzw. Steuereinheit zur Erzeugung eines Radbremsmoments in der Radbremseinheit ansteuerbar ist. Master cylinder associated reservoir fluidly connected, the secondary chamber with the storage chamber for receiving the hydraulic brake fluid. Furthermore, it is provided that the hydraulic pump is connected to the storage chamber and that the hydraulic pump via control signals of a control or control unit for generating a Radbremsmoments in the wheel brake is controllable.
Über den Pedalwegsimulator und die Speicherkammer im Strömungsweg zwischen Sekundärkammer des Simulators und Hydraulikpumpe wird eine Entkopp- lung zwischen der Betätigung des Bremspedals durch den Fahrer und derVia the pedal travel simulator and the storage chamber in the flow path between the secondary chamber of the simulator and hydraulic pump, a decoupling between the actuation of the brake pedal by the driver and the driver
Druckbeaufschlagung der Radbremseinheiten erzielt. Der Pedalweg des Brems- pedals und/oder der vom Fahrer erzeugte Pedaldruck wird für die Ermittlung eines Sollbremsmoments herangezogen, wobei die über die Pedalbewegung erfolgte Verdrängung von Hydraulikfluid aus dem Hauptbremszylinder nicht unmittelbar in der Radbremseinheit wirksam wird, sondern vielmehr eine Verschiebung von Hydraulikfluid über den Pedalwegsimulator in die nachgeschaltete Speichereinheit stattfindet. Die Hydraulikpumpe saugt bei Betätigung Hydraulikfluid aus der Speicherkammer an und beaufschlagt das Fluid mit einem Bremsdruck, welcher in der Radbremseinheit wirksam wird. Die Ansteuerung der Hydraulikpumpe über die Stellsignale der Regel- bzw. Achieved pressurization of Radbremseinheiten. The pedal travel of the brake Pedals and / or the pedal pressure generated by the driver is used for determining a desired braking torque, wherein the pedal movement over the displacement of hydraulic fluid from the master cylinder is not directly in the Radbremseinheit effective, but rather a shift of hydraulic fluid via the pedal travel simulator in the downstream storage unit takes place. Upon actuation, the hydraulic pump draws hydraulic fluid from the storage chamber and pressurizes the fluid with a brake pressure which is effective in the wheel brake unit. The control of the hydraulic pump via the control signals of the control or
Steuereinheit erlaubt eine variable Anpassung an die jeweilige, aktuelle Bremssituation im Fahrzeug. Die Betätigung der Hydraulikpumpe ist somit nicht zwingend an die Betätigung des Bremspedals gekoppelt, so dass sonstige Einflüsse bei der Ansteuerung der Hydraulikpumpe berücksichtigt werden können. Es ist ins- besondere möglich, Zusatzbremsmomente zu berücksichtigen, welche von Zusatzbremseinrichtungen herstammen, insbesondere von im rekuperativen Betrieb laufenden Elektromotoren, die im Antriebsstrang des Fahrzeugs angeordnet sind. Die Zusatzbremsmomente derartiger Zusatzbremseinrichtungen und die mechanischen Bremsmomente, welche in den Radbremseinheiten der Fahrzeugbrems- anläge durch Betätigung der Hydraulikpumpe erzeugt werden, bestimmen das Control unit allows a variable adaptation to the current braking situation in the vehicle. The actuation of the hydraulic pump is thus not necessarily coupled to the actuation of the brake pedal, so that other influences in the control of the hydraulic pump can be taken into account. In particular, it is possible to take account of additional braking torques which originate from additional brake devices, in particular electric motors which operate in recuperative operation and which are arranged in the drive train of the vehicle. The additional braking torques of such auxiliary brake devices and the mechanical braking torques which are generated in the wheel brake units of the vehicle brake systems by actuation of the hydraulic pump determine this
Gesamt-Bremsmoment, welches dem vom Fahrer über die Pedalbetätigung vorgegebenen Sollbremsmoment entspricht. Durch eine entsprechende Ansteuerung der Hydraulikpumpe können Änderungen der Zusatzbremsmomente kompensiert werden, ohne dass dies vom Fahrer bemerkt wird. Dies betrifft bei- spielsweise den Fall, dass ein rekuperatives, elektrisches Bremsmoment zunimmt oder abnimmt, zugeschaltet oder abgeschaltet wird. Für den Fahrer ist dies weder in der Pedalbetätigung noch in der Fahrzeugverzögerung zu spüren. Total braking torque, which corresponds to the predetermined braking torque given by the driver via the pedal actuation. By a corresponding control of the hydraulic pump changes of the additional braking torques can be compensated without this being noticed by the driver. This applies, for example, to the case where a recuperative electric braking torque increases or decreases, is switched on or off. For the driver, this is felt neither in the pedal operation nor in the vehicle deceleration.
Während eines regulären Bremsvorgangs - mit oder ohne Zusatzbremsmoment einer Zusatzbremseinrichtung - wird durch die Betätigung des BremspedalsDuring a regular braking operation - with or without additional braking torque of an additional braking device - is by pressing the brake pedal
Hydraulikfluid aus dem Hauptbremszylinder in die Primärkammer des Pedalwegsimulators geleitet, woraufhin der Kolben in dem Pedalwegsimulator in Richtung der Sekundärkammer verschoben und aufgrund der Volumenverkleinerung der Sekundärkammer darin befindliches Hydraulikfluid in die nachgeschaltete Spei- cherkammer verdrängt wird. Mit der Ansteuerung der Hydraulikpumpe saugt diese aus der Speicherkammer Hydraulikfluid an und beaufschlagt dieses mit dem in der Regel- bzw. Steuereinheit ermittelten Bremsdruck. Für einen voll aktiven Druckaufbau ohne Pedalbetätigung durch den Fahrer, beispielsweise zur Unterstützung eines Fahrerassistenzsystems wie zum Beispiel ESP (Elektronisches Stabilitäts-Programm), ist die Hydraulikpumpe vorteilhafterweise über ein strom- los geschlossenes Ventil mit dem Hauptbremszylinder bzw. dem diesem Zylinder zugeordneten Reservoir verbunden und fördert aus dem Reservoir Hydraulikfluid in den Bremskreis. Hydraulic fluid from the master cylinder passed into the primary chamber of the pedal travel simulator, whereupon the piston is displaced in the pedal travel simulator in the direction of the secondary chamber and due to the reduction in volume of the secondary chamber therein hydraulic fluid is displaced into the downstream storage chamber. With the control of the hydraulic pump sucks this from the storage chamber hydraulic fluid and acts on this with the in the control unit or control unit determined brake pressure. For a fully active pressure build-up without pedal actuation by the driver, for example, to support a driver assistance system such as ESP (Electronic Stability Program), the hydraulic pump is advantageously connected via a valve with no current to the master cylinder or the reservoir associated with this and promotes hydraulic fluid from the reservoir into the brake circuit.
Um für Notfälle einen direkten, hydraulischen Durchgriff zwischen dem Haupt- bremszylinder und den Radbremseinheiten zu erhalten, ist die Primärkammer des Pedalwegsimulators zweckmäßigerweise über ein einstellbares Hydraulikventil mit dem die mindestens eine Radbremseinheit enthaltenden Bremskreis verbunden. Die Sekundärkammer ist zweckmäßigerweise über eine verschließbare Stelleinrichtung mit der Speicherkammer verbunden. Das Hydraulikventil, welches der Primärkammer nachgeschaltet ist, ist vorzugsweise als stromlos offenes Ventil ausgestaltet, das bei einem Ausfall der elektrischen Stromversorgung in Öffnungsposition steht, so dass die Primärkammer des Pedalwegsimulators hydraulisch mit den Radbremseinheiten verbunden ist. Die Stelleinrichtung, welche der Sekundärkammer zugeordnet ist, ist dagegen stromlos geschlossen ausgeführt, so dass bei einem Ausfall der Stromversorgung die Verbindung zwischen der Sekundärkammer des Pedalwegsimulators und der Speicherkammer unterbrochen ist. In order to obtain a direct hydraulic penetration between the main brake cylinder and the wheel brake units for emergencies, the primary chamber of the pedal travel simulator is expediently connected via an adjustable hydraulic valve to the brake circuit containing the at least one wheel brake unit. The secondary chamber is expediently connected to the storage chamber via a closable setting device. The hydraulic valve, which is connected downstream of the primary chamber, is preferably configured as a normally open valve, which is in the open position in the event of a failure of the electrical power supply, so that the primary chamber of the pedal travel simulator is hydraulically connected to the wheel brake units. The adjusting device which is associated with the secondary chamber, however, is designed to be normally closed, so that in case of failure of the power supply, the connection between the secondary chamber of the pedal travel and the storage chamber is interrupted.
Die verschließbare Stelleinrichtung, die im Strömungsweg zwischen der Sekun- därkammer des Pedalwegsimulators und der Speicherkammer liegt, ist gemäß einer ersten bevorzugten Ausführung als ein einstellbares, der Sekundärkammer nachgeordnetes Hydraulikventil ausgeführt, das stromlos geschlossen ist. Gemäß einer zweiten, alternativen Ausführung ist die Stelleinrichtung in den Pedalwegsimulator integriert, wobei der Kolben Teil der Stelleinrichtung ist und bei ei- ner Verschiebung des Kolbens zwischen der Ausgangsposition und der in Richtung der Sekundärkammer verschobenen Position der Strömungsweg zur Speicherkammer freigegeben wird. Dies wird beispielsweise dadurch realisiert, dass in der Ausgangsposition, in der noch kein Hydraulikfluid aus dem Hauptbremszylinder in die Primärkammer des Pedalwegsimulators gefördert wurde, ein Teil des Kolbens eine Abströmöffnung in Richtung der nachgeschalteten Speicherkammer verschließt. Mit dem Verschieben des Kolbens in Richtung der Sekundär- kammer wird die Abströmöffnung geöffnet, so dass eine Strömungsverbindung zwischen der Sekundärkammer und der Speicherkammer besteht und mit dem weiteren Verschieben des Kolbens das in der Sekundärkammer befindliche Hydraulikfluid in die Speicherkammer verdrängt wird. Diese Ausführung zeichnet sich durch eine kompakte Bauform und eine geringe Teileanzahl aus; außerdem ist für das Öffnen und Schließen der Abströmöffnung in der Sekundärkammer des Pedalwegsimulators kein elektrisches Bauteil erforderlich. The closable adjusting device, which is located in the flow path between the secondary chamber of the pedal travel simulator and the storage chamber, is designed according to a first preferred embodiment as an adjustable, the secondary chamber downstream hydraulic valve which is normally closed. According to a second, alternative embodiment, the adjusting device is integrated in the pedal travel simulator, wherein the piston is part of the adjusting device and is released at a displacement of the piston between the starting position and the displaced in the direction of the secondary chamber, the flow path to the storage chamber. This is realized, for example, in that in the starting position in which no hydraulic fluid has yet been conveyed from the master brake cylinder into the primary chamber of the pedal travel simulator, a part of the piston closes an outflow opening in the direction of the downstream storage chamber. With the displacement of the piston in the direction of the secondary Chamber, the discharge opening is opened, so that a flow connection between the secondary chamber and the storage chamber and with the further displacement of the piston which is located in the secondary chamber hydraulic fluid is displaced into the storage chamber. This design is characterized by a compact design and a low number of parts; In addition, no electrical component is required for the opening and closing of the discharge opening in the secondary chamber of the pedal travel simulator.
Grundsätzlich genügt es, dass der Pedalwegsimulator einschließlich der zuge- ordneten Baueinheiten lediglich in einen einzigen Bremskreis der Fahrzeugbremsanlage integriert ist, wohingegen ein üblicherweise vorgesehener zweiter Bremskreis in konventioneller Weise ohne derartigen Pedalwegsimulator ausgeführt ist. Bei einer achsbezogenen Aufteilung der Bremskreise, bei der ein erster Bremskreis die Radbremseinheiten an der Vorderachse und der zweite Brems- kreis die Radbremseinheiten an der Hinterachse beaufschlagt, ist auf diese Weise eine Aufteilung unterschiedlicher hoher Radbremsmomente pro Fahrzeugachse möglich. Erreicht wird dies durch eine entsprechende Ansteuerung der Hydraulikpumpe bzw. des die Hydraulikpumpe beaufschlagenden elektromotorischen Antriebs. In principle, it suffices for the pedal travel simulator, including the associated structural units, to be integrated only in a single brake circuit of the vehicle brake system, whereas a conventionally provided second brake circuit is implemented in the conventional manner without such a pedal travel simulator. In the case of an axle-related division of the brake circuits, in which a first brake circuit acts on the wheel brake units on the front axle and the second brake circuit on the wheel brake units on the rear axle, it is possible in this way to split different high wheel brake torques per vehicle axle. This is achieved by a corresponding control of the hydraulic pump or of the hydraulic pump acting on the electromotive drive.
Es reicht aus, einen gemeinsamen elektromotorischen Antrieb für jeweils eine Hydraulikpumpe pro Bremskreis vorzusehen. Eine Momentenaufteilung zwischen den Bremskreisen kann dadurch realisiert werden, dass ein Hydraulikventil zwischen dem Reservoir des Hauptbremszylinders und dem Bremskreis ohne Pe- dalwegsimulator geschlossen wird. Daneben sind aber auch Ausführungen möglich, in denen jeder Hydraulikpumpe ein eigener elektromotorischer Antrieb zugeordnet ist. It is sufficient to provide a common electric motor drive for one hydraulic pump per brake circuit. A torque distribution between the brake circuits can be realized by closing a hydraulic valve between the reservoir of the master brake cylinder and the brake circuit without a pedal travel simulator. In addition, however, embodiments are possible in which each hydraulic pump is assigned its own electric motor drive.
Gemäß einer weiteren zweckmäßigen Ausführung kann auch innerhalb des mit dem Pedalwegsimulator ausgestatteten Bremskreises eine Bremskraftverteilung zwischen den Radbremseinheiten dieses Bremskreises durchgeführt werden, indem die Einlass- bzw. Auslassventile jeder Radbremseinheit in unterschiedlicher Weise angesteuert werden. Die hydraulische Fahrzeugbremsanlage wird bevorzugt in Hybridfahrzeugen eingesetzt, die als Antriebsquelle einen Elektromotor und einen Verbrennungsmotor aufweisen. Zum Aufladen des elektrischen Energiespeichers ist der Elektromotor im Rekuperations- bzw. Generatorbetrieb zu betreiben, in welchem elektrische Bremsmomente im Elektromotor wirksam werden, die sich auf den Antriebsstrang bremsend auswirken. Die elektrischen Bremsmomente addieren sich zu den mechanischen Radbremsmomenten, die über die hydraulische Fahrzeugbremsanlage generiert werden. Aufgrund der Ausstattung der hydraulischen Fahrzeugbremsanlage mit dem Pedalwegsimulator, dessen Sekundärseite mit der Speicherkammer kommuniziert, wobei die Hydraulikpumpe aus der Speicherkammer Hydraulikfluid in Richtung der Radbremseinheiten fördert, ist je nach Beaufschlagung der Hydraulikpumpe ein entsprechender hydraulischer Bremsdruck erzeugbar, der sich in einem entsprechenden mechanischen Radbremsmoment niederschlägt. According to a further expedient embodiment, a brake force distribution between the wheel brake units of this brake circuit can also be carried out within the brake circuit equipped with the pedal travel simulator by controlling the intake and exhaust valves of each wheel brake unit in different ways. The hydraulic vehicle brake system is preferably used in hybrid vehicles, the drive source as an electric motor and an internal combustion engine exhibit. To charge the electrical energy storage, the electric motor is to be operated in recuperation or generator operation, in which electric braking torques in the electric motor take effect, which have a braking effect on the drive train. The electrical braking torques add up to the mechanical wheel braking torques that are generated by the hydraulic vehicle brake system. Due to the equipment of the hydraulic vehicle brake system with the pedal travel simulator whose secondary side communicates with the storage chamber, wherein the hydraulic pump from the storage chamber promotes hydraulic fluid in the direction of Radbremseinheiten, depending on the application of the hydraulic pump, a corresponding hydraulic brake pressure can be generated, which is reflected in a corresponding mechanical Radbremsmoment ,
Grundsätzlich ist die erfindungsgemäße hydraulische Fahrzeugbremsanlage auch in Fahrzeugen einsetzbar, die ausschließlich einen Elektromotor als Antriebsquelle aufweisen. In principle, the hydraulic vehicle brake system according to the invention can also be used in vehicles which have exclusively an electric motor as drive source.
Die hydraulische Fahrzeugbremsanlage weist vorzugsweise nur in einem Bremskreis einen Pedalwegsimulator mit den zugeordneten Baueinheiten auf. Grund- sätzlich möglich ist aber auch eine Ausführung, bei der beide Bremskreise mit jeweils einem Pedalwegsimulator und den zugeordneten Baueinheiten ausgestattet sind. The hydraulic vehicle brake system preferably has only in a brake circuit on a pedal travel simulator with the associated units. In principle, however, an embodiment is also possible in which both brake circuits are each equipped with a pedal travel simulator and the associated structural units.
Das erfindungsgemäße Verfahren setzt eine hydraulische Fahrzeugbremsanlage voraus, die zumindest in einem Bremskreis einen Pedalwegsimulator mit Primärkammer und Sekundärkammer und zwischenliegendem, verschieblichen Kolben aufweist, wobei die Sekundärkammer mit einer Speicherkammer strömungsver- bunden ist und aus der Speicherkammer über eine Hydraulikpumpe Hydraulikfluid in den Bremskreis gefördert werden kann. Das Verfahren wird in der Weise durchgeführt, dass zunächst in einem ersten Verfahrensschritt aus der Bremspedalstellung ein Sollbremsmoment festgestellt wird, das dem Fahrerwunsch entspricht. Danach wird in einem nächsten Verfahrensschritt festgestellt, ob und in welcher Höhe in einer Zusatzbremseinrichtung ein Zusatzbremsmoment aktuell generiert wird. Schließlich wird in einem weiteren Verfahrensschritt die Hydrau- likpumpe in der Weise betätigt, dass das über die Radbremseinheit erzeugteThe method according to the invention requires a hydraulic vehicle brake system which has a pedal travel simulator with primary chamber and secondary chamber and intermediate displaceable piston at least in one brake circuit, wherein the secondary chamber is fluidically connected to a storage chamber and hydraulic fluid is conveyed from the storage chamber into the brake circuit via a hydraulic pump can. The method is carried out in such a way that initially in a first method step from the brake pedal position, a desired braking torque is determined, which corresponds to the driver's request. Thereafter, it is determined in a next method step, whether and at what level in an additional brake device, an additional braking torque is currently generated. Finally, in a further method step, the hydraulic pump is actuated in such a way that the pressure generated by the wheel brake unit
Radbremsmoment aus der Differenz zwischen dem vom Fahrer vorgegebenen Sollbremsmoment und dem Zusatzbremsmoment berechnet wird. Durch diese Vorgehensweise ist sichergestellt, dass unabhängig von einem aktuell anliegenden Zusatzbremsmoment immer das vom Fahrer gewünschte Sollbremsmoment wirksam ist. Außerdem wird durch die spezielle Ausgestaltung des einen Brems- kreises mit dem Pedalwegsimulator eine Entkopplung zwischen dem Bremspedaldruck und dem Bremsdruck des Hydraulikfluids im Bremskreis erzielt. Radbremsmoment from the difference between the predetermined by the driver Target braking torque and the additional braking torque is calculated. This procedure ensures that regardless of a currently applied additional braking torque always desired by the driver target braking torque is effective. In addition, a decoupling between the brake pedal pressure and the brake pressure of the hydraulic fluid in the brake circuit is achieved by the special design of the one brake circuit with the pedal travel simulator.
Weitere Vorteile und zweckmäßige Ausführungen sind den weiteren Ansprüchen, der Figurenbeschreibung und den Zeichnungen zu entnehmen. Es zeigen: Further advantages and expedient embodiments can be taken from the further claims, the description of the figures and the drawings. Show it:
Fig. 1 einen hydraulischen Schaltplan einer Fahrzeugbremsanlage mit einem Vorderachs-Bremskreis und einem Hinterachs-Bremskreis, wobei in den Hinterachs-Bremskreis ein Pedalwegsimulator mit einer Primärkammer und einer über einen Kolben separierten Sekundärkammer integriert ist und sowohl der Primärkammer als auch der Sekundärkammer jeweils ein Hydraulikventil nachgeschaltet ist, Fig. 1 is a hydraulic circuit diagram of a vehicle brake system with a front-axle brake circuit and a rear brake circuit, wherein in the rear axle brake circuit a pedal travel simulator is integrated with a primary chamber and a secondary chamber separated by a piston and both the primary chamber and the secondary chamber each have a hydraulic valve is downstream,
Fig. 2 eine Fahrzeugbremsanlage, die ähnlich ausgestaltet ist wie diejenige nach Fig. 1 , jedoch mit einer in den Pedalwegsimulator integrierten Stelleinrichtung zum Öffnen und Schließen einer Abströmöffnung in derFig. 2 is a vehicle brake system which is designed similar to that of FIG. 1, but with an integrated into the pedal travel control device for opening and closing an outflow opening in the
Sekundärkammer, Secondary chamber
Fig. 3 ein Ablaufdiagramm mit einzelnen Verfahrensschritten zur Durchführung des Verfahrens zum Betrieb der Fahrzeugbremsanlage. 3 shows a flow chart with individual method steps for carrying out the method for operating the vehicle brake system.
In den Figuren sind gleiche Bauteile mit gleichen Bezugszeichen versehen. In the figures, the same components are provided with the same reference numerals.
Wie dem hydraulischen Schaltplan nach Fig. 1 zu entnehmen, weist die hydraulische Fahrzeugbremsanlage 1 in einem Kraftfahrzeug einen Vorderachs- Bremskreis 2 und einen Hinterachs-Bremskreis 3 auf, die an einen gemeinsamenAs can be seen from the hydraulic circuit diagram according to FIG. 1, the hydraulic vehicle brake system 1 in a motor vehicle has a front-axle brake circuit 2 and a rear-axle brake circuit 3 which are connected to a common brake system
Hauptbremszylinder 4 angeschlossen sind, der von einem Bremspedal 6 vom Fahrer zu betätigen ist. Dem Hauptbremszylinder 4 ist ein Bremsflüssigkeitsreservoir 5 zugeordnet. Der Pedalweg des Bremspedals 6 wird mithilfe eines Pedalwegsensors 7 ermittelt. Über den Vorderachs-Bremskreis 2 werden Radbremseinheiten 8 und 9 am linken bzw. rechten Vorderrad betätigt, über den Hinterachs-Bremskreis 3 Radbremseinheiten 10 und 1 1 am linken bzw. rechten Hinterrad. Jedem Bremskreis 2, 3 ist ein regelbares Umschaltventil 12 zugeordnet, das an den Hauptbremszy- linder 4 angeschlossen ist, wobei die Umschaltventile in ihrer stromlosen Grundstellung geöffnet sind. Jedes Umschaltventil 12 weist ein parallel angeordnetes Rückschlagventil auf, das vom Hauptbremszylinder zu den jeweiligen Radbremseinheiten durchströmbar ist. Zwischen den Umschaltventilen 12 und den jeweiligen Radbremseinheiten 8 bisMaster cylinder 4 are connected, which is operated by a brake pedal 6 by the driver. The master cylinder 4 is a brake fluid reservoir 5 assigned. The pedal travel of the brake pedal 6 is determined by means of a pedal travel sensor 7. Wheel brake units 8 and 9 are actuated on the left and right front wheels via the front axle brake circuit 2, and wheel brake units 10 and 11 on the left and right rear wheels via the rear axle brake circuit 3. Each brake circuit 2, 3 is associated with a controllable changeover valve 12 which is connected to the Hauptbremszy- cylinder 4, wherein the changeover valves are open in their normally-off normal position. Each switching valve 12 has a check valve arranged in parallel, which can be flowed through by the master cylinder to the respective wheel brake units. Between the switching valves 12 and the respective wheel brake units 8 to
1 1 befinden sich jeweils Einlassventile 13, die ebenfalls im stromlosen Zustand geöffnet sind. Jedem Einlassventil 13 ist je ein Rückschlagventil zugeordnet, das in Richtung zum Hauptbremszylinder durchströmbar ist. Den Radbremseinheiten 8 bis 11 ist jeweils ein stromlos geschlossenes Auslassventil 14 zugeordnet, die mit der Saugseite einer Pumpeneinheit 15 verbunden sind, wobei die Pumpeneinheit 15, die insbesondere Bestandteil eines ESP- Systems (elektronisches Stabilitätsprogramm) ist, eine erste Hydraulikpumpe 16 im Vorderachs-Bremskreis 2 und eine zweite Hydraulikpumpe 17 im Hinterachs- Bremskreis 3 sowie einen die beiden Hydraulikpumpen 16, 17 gemeinsam betätigenden elektrischen Antriebsmotor 18 umfasst. Die Druckseite der Hydraulikpumpen 16 und 17 ist an einen Leitungsabschnitt zwischen dem Umschaltventil1 1 are each intake valves 13, which are also open when de-energized. Each inlet valve 13 is associated with a respective check valve, which can be flowed through in the direction of the master cylinder. The wheel brake units 8 to 11 are each associated with a normally closed exhaust valve 14, which are connected to the suction side of a pump unit 15, the pump unit 15, which is in particular part of an ESP system (electronic stability program), a first hydraulic pump 16 in the front-axle brake circuit 2 and a second hydraulic pump 17 in the rear axle brake circuit 3 and a two hydraulic pumps 16, 17 jointly actuated electric drive motor 18 includes. The pressure side of the hydraulic pumps 16 and 17 is at a line section between the switching valve
12 und den beiden Einlassventilen 13 pro Bremskreis angeschlossen. Die Saugseiten der Hydraulikpumpen 16 und 17 sind jeweils mit einem Hauptschaltventil 19 verbunden, welches mit dem Hauptbremszylinder 4 hydraulisch verbunden ist. 12 and the two inlet valves 13 per brake circuit connected. The suction sides of the hydraulic pumps 16 and 17 are each connected to a main switching valve 19, which is hydraulically connected to the master cylinder 4.
Zur Durchführung eines fahrdynamischen Regeleingriffes können die im stromlosen Zustand geschlossenen Hauptschaltventile 19 geöffnet werden, woraufhin die Hydraulikpumpen 16 und 17 Hydraulikfluid unmittelbar aus dem Hauptbrems- zylinder 4 bzw. dem zugeordneten Bremsflüssigkeitsreservoir 5 ansaugen. DerTo carry out a dynamic control intervention, the main switching valves 19, which are closed in the de-energized state, can be opened, whereupon the hydraulic pumps 16 and 17 draw in hydraulic fluid directly from the master brake cylinder 4 or the associated brake fluid reservoir 5. Of the
Bremsdruckaufbau ist hierbei unabhängig von einer Betätigung des Bremspedals durch den Fahrer. Brake pressure build-up here is independent of an operation of the brake pedal by the driver.
Die Saugseite der Hydraulikpumpen 16 und 17 kommuniziert außerdem mit je- weils einem Hydraulikspeicher bzw. einer Speicherkammer 20 zur Aufnahme vonThe suction side of the hydraulic pumps 16 and 17 also communicates with each of a hydraulic accumulator and a storage chamber 20 for receiving
Bremsfluid. Die Speicherkammern 20 sind außerdem mit dem die Auslassventile 14 enthaltenden Leitungsabschnitten strömungsverbunden. Die Speicherkammern 20 dienen zur Zwischenspeicherung von Bremsfluid, das während eines fahrdynamischen Eingriffs über die Auslassventile 14 aus den Radbremseinheiten 8 bis 11 ausgelassen wurde. Brake fluid. The storage chambers 20 are also with the exhaust valves 14 containing line sections flow-connected. The storage chambers 20 are used for temporary storage of brake fluid, which was discharged from the wheel brake units 8 to 11 during a dynamic driving engagement via the exhaust valves 14.
Jeder Bremskreis 2, 3 weist außerdem einen Drucksensor 21 bzw. 22 zur Messung des Bremsdrucks im jeweiligen Bremskreis auf. Der Drucksensor 21 im Vorderachs-Bremskreis 2 befindet sich zwischen dem Hauptbremszylinder 4 und dem Hauptschaltventil 19. Der Drucksensor 22 im Hinterachs-Bremskreis 3 ist zwischen dem Umschaltventil 12 und den Einlassventilen 13 angeordnet. Each brake circuit 2, 3 also has a pressure sensor 21 or 22 for measuring the brake pressure in the respective brake circuit. The pressure sensor 21 in the front-axle brake circuit 2 is located between the master cylinder 4 and the main switching valve 19. The pressure sensor 22 in the rear-axle brake circuit 3 is disposed between the switching valve 12 and the intake valves 13.
Der Fahrzeugbremsanlage 1 ist außerdem eine Regel- bzw. Steuereinheit 23 zugeordnet, die in Abhängigkeit von Eingangssignalen Stellsignale insbesondere zur Beaufschlagung der Hydraulikpumpen 16 und 17 bzw. des den Pumpen zu- geordneten elektrischen Antriebsmotors 18 generiert. Als Eingangssignale werden der Regel- bzw. Steuereinheit 23 die Sensorsignale der Sensoren der Fahrzeugbremsanlage zugeführt. Darüber hinaus können in der Regel- bzw. Steuereinheit 23 Signale weiterer Aggregate bzw. Stelleinrichtungen im Fahrzeug verarbeitet werden, beispielsweise Zusatzbremsmomente von Zusatzbremseinrich- tungen außerhalb der hydraulischen Fahrzeugbremsanlage wie zum Beispiel imThe vehicle brake system 1 is also associated with a control or control unit 23, which generates control signals in response to input signals, in particular for acting upon the hydraulic pumps 16 and 17 or the electric drive motor 18 assigned to the pumps. As input signals of the control unit 23, the sensor signals of the sensors of the vehicle brake system are supplied. In addition, signals of further units or actuating devices in the vehicle can be processed in the control unit or control unit 23, for example additional braking torques of auxiliary brake devices outside the hydraulic vehicle brake system, such as in the
Generatormodus betriebene elektrische Antriebsmotoren im Antriebsstrang des Fahrzeugs. Generator mode operated electric drive motors in the drive train of the vehicle.
Der Hinterachs-Bremskreis 3 weist ein Zusatzaggregat 24 auf, das dem Haupt- bremszylinder 4 im Bremskreis 3 nachgeschaltet ist. Das Zusatzaggregat 24 um- fasst einen Pedalwegsimulator 25, der mit dem Hauptbremszylinder 4 strömungsverbunden ist, sowie zwei dem Pedalwegsimulator 25 nachgeordnete Hydraulikventile 26 und 27, von denen das erste Hydraulikventil 26 zwischen einer Primärkammer 28 des Pedalwegsimulators 25 und dem Umschaltventil 12 und das zweite Hydraulikventil 27 zwischen einer Sekundärkammer 29 des Pedalwegsimulators 25 und der Speicherkammer 20 angeordnet ist. Die Primärkammer 28 des Pedalwegsimulators 25 ist mit dem Hauptzylinder 4 strömungsverbunden. Zwischen Primärkammer 28 und Sekundärkammer 29 ist ein Kolben 30 verschieblich angeordnet. Sobald Bremsflüssigkeit aus dem Hauptbremszy- linder 4 in die Primärkammer 28 einströmt, wird der Kolben 30 aus der in Fig. 1 dargestellten Ausgangsposition in Richtung der Sekundärkammer 29 verscho- ben, woraufhin das in der Sekundärkammer 29 befindliche Bremsfluid über eine Abströmöffnung in der Sekundärkammer über das geöffnete Hydraulikventil 27 abströmt und der Speicherkammer 20 zugeführt wird. Das Hydraulikventil 26 ist als stromlos offenes Ventil, das Hydraulikventil 27 als stromlos geschlossenes Ventil ausgeführt, wodurch eine Fallebene realisiert ist, da bei stromlosen Ventilen ein unmittelbarer hydraulischer Durchgriff zwischen von dem Hauptbremszylinder 4 über die Primärkammer 28 und das geöffnete Hydraulikventil 26 zu den Radbremseinheiten 10 und 11 gegeben ist. Zugleich ist in der Rückfallebene das zweite Hydraulikventil 27 stromlos geschlossen, so dass kein Hydraulikfluid aus der Sekundärkammer 29 des Pedalwegesimulators 25 in Richtung Speicherkammer 20 abströmen kann. The rear axle brake circuit 3 has an additional unit 24, which is connected downstream of the master brake cylinder 4 in the brake circuit 3. The auxiliary unit 24 comprises a pedal travel simulator 25, which is flow-connected to the master cylinder 4, and two hydraulic valves 26 and 27 downstream of the pedal travel simulator 25, of which the first hydraulic valve 26 is connected between a primary chamber 28 of the pedal travel simulator 25 and the changeover valve 12 and the second hydraulic valve 27 is disposed between a secondary chamber 29 of the pedal travel simulator 25 and the storage chamber 20. The primary chamber 28 of the pedal travel simulator 25 is fluidly connected to the master cylinder 4. Between primary chamber 28 and secondary chamber 29, a piston 30 is slidably disposed. As soon as brake fluid flows from the master brake cylinder 4 into the primary chamber 28, the piston 30 is shifted from the starting position shown in FIG. 1 in the direction of the secondary chamber 29. ben, whereupon the brake fluid located in the secondary chamber 29 flows through an outflow opening in the secondary chamber via the open hydraulic valve 27 and the storage chamber 20 is supplied. The hydraulic valve 26 is designed as a normally open valve, the hydraulic valve 27 is designed as a normally closed valve, whereby a Fallebene is realized because with de-energized valves direct hydraulic penetration between the master cylinder 4 via the primary chamber 28 and the open hydraulic valve 26 to the wheel brake 10th and 11 is given. At the same time, the second hydraulic valve 27 is normally closed in the fallback mode, so that no hydraulic fluid can flow out of the secondary chamber 29 of the pedal travel simulator 25 in the direction of the storage chamber 20.
Im regulären Betriebsmodus sind die Hydraulikventile 26 und 27 bestromt, so dass das der Primärkammer 28 nachgeschaltete Hydraulikventil 26 geschlossen und das der Sekundärkammer 29 nachgeschaltete Hydraulikventil 27 geöffnet ist. Bei einer Betätigung des Bremspedals 6 strömt Hydraulikfluid aus dem Hauptbremszylinder 4 in die Primärkammer 28 des Pedalwegsimulators 25, woraufhin der Kolben 30 in Richtung der Sekundärkammer 29 verschoben und das darin befindliche Bremsfluid über das geöffnete Hydraulikventil 27 in die Speicherkammer 20 verschoben wird. Bei einer Betätigung der Hydraulikpumpe 17 wird Bremsfluid aus der Speicherkammer 20 angesaugt und mit einem gewünschten Bremsdruck den Radbremseinheiten 10 und 1 1 zugeführt. Der Bremsdruck hängt hierbei von der Betätigung der Hydraulikpumpe 17 ab, die über Stellsignale der Regel- bzw. Steuereinheit 23 eingestellt wird. In the regular operating mode, the hydraulic valves 26 and 27 are energized, so that the hydraulic valve 26 connected downstream of the primary chamber 28 is closed and the hydraulic valve 27 connected downstream of the secondary chamber 29 is opened. Upon actuation of the brake pedal 6, hydraulic fluid flows from the master cylinder 4 into the primary chamber 28 of the pedal travel simulator 25, whereupon the piston 30 is displaced in the direction of the secondary chamber 29 and the brake fluid therein is displaced into the storage chamber 20 via the open hydraulic valve 27. Upon actuation of the hydraulic pump 17, brake fluid is sucked from the storage chamber 20 and fed to the wheel brake units 10 and 11 at a desired brake pressure. The brake pressure here depends on the operation of the hydraulic pump 17, which is set via control signals of the control unit 23.
Der Druckabbau kann je nach Fahrsituation entweder über das Umschaltventil 12 oder das Auslassventil 14 durchgeführt werden. Im Regelfall erfolgt der Druckabbau über ein Öffnen des Umschaltventils 12, so dass Bremsfluid aus den Rad- bremseinheiten 10 und 1 1 über das geöffnete Umschaltventil 12 und das ebenfalls geöffnete Hydraulikventil 27 in die Speicherkammer 20 einströmt. Im Falle eines möglichst schnell durchzuführenden Druckabbaus werden dagegen die Auslassventile 14 geöffnet, so dass Bremsfluid aus den Radbremseinheiten 10 und 1 1 über die geöffneten Auslassventile 14 direkt in die Speicherkammer 20 strömt. In Fig. 2 ist eine Ausführungsvariante dargestellt, bei der das Zusatzaggregat 24 mit dem Pedalwegsimulator 25 im Vergleich zum Ausführungsbeispiel nach Fig. 1 in modifizierter Weise ausgeführt ist. Der Pedalwegsimulator 25 weist analog zum ersten Ausführungsbeispiel eine Primärkammer 28 und eine Sekundärkam- mer 29 auf, zwischen denen der verschiebliche Kolben 30 angeordnet ist. DerThe pressure reduction can be carried out either via the switching valve 12 or the exhaust valve 14 depending on the driving situation. As a rule, the pressure is reduced by opening the changeover valve 12, so that brake fluid from the wheel brake units 10 and 11 flows into the storage chamber 20 via the open changeover valve 12 and the likewise open hydraulic valve 27. In the case of pressure reduction to be carried out as quickly as possible, on the other hand, the exhaust valves 14 are opened so that brake fluid from the wheel brake units 10 and 11 flows directly into the storage chamber 20 via the opened exhaust valves 14. In Fig. 2 shows a variant is shown, in which the auxiliary unit 24 is executed with the pedal travel simulator 25 in comparison to the embodiment of FIG. 1 in a modified manner. Analogous to the first exemplary embodiment, the pedal travel simulator 25 has a primary chamber 28 and a secondary chamber 29, between which the displaceable piston 30 is arranged. Of the
Primärkammer 28 ist das stromlos offene Hydraulikventil 26 nachgeordnet. Primary chamber 28 is the normally open hydraulic valve 26 downstream.
Der Sekundärkammer 29 ist aber im Unterschied zum ersten Ausführungsbeispiel kein Hydraulikventil nachgeschaltet. Das Öffnen und Schließen der Sekun- därkammer 29 erfolgt vielmehr mithilfe einer speziellen Ausgestaltung des Kolbens 30, der in Fig. 2 in seiner Ausgangsstellung dargestellt ist, in der noch kein Bremsfluid aus dem Hauptbremszylinder in die Primärkammer 28 eingeströmt ist. Ein Abschnitt 30a des Kolbens 30 verschließt in der Ausgangsstellung eine Abströmöffnung in der Sekundärkammer 29 in Richtung Speicherkammer 20. So- bald Bremsfluid aus dem Hauptbremszylinder 4 in die Primärkammer 28 einströmt und der Kolben 30 aus der Ausgangsstellung in Richtung der Sekundärkammer 29 verschoben wird, gelangt ein zweiter Abschnitt 30b des Kolbens 30 in den Bereich der Abströmöffnung der Sekundärkammer 29, woraufhin die Abströmöffnung freigegeben wird, so dass das in der Sekundärkammer 29 befindli- che Hydraulikfluid in die Speicherkammer 20 abströmen kann. The secondary chamber 29 is but in contrast to the first embodiment, no hydraulic valve connected downstream. Rather, the secondary chamber 29 is opened and closed by means of a special embodiment of the piston 30, which is shown in its initial position in FIG. 2, in which no brake fluid has yet flowed from the master brake cylinder into the primary chamber 28. A portion 30a of the piston 30 closes in the starting position an outflow opening in the secondary chamber 29 in the direction of storage chamber 20. As soon as brake fluid from the master cylinder 4 flows into the primary chamber 28 and the piston 30 is moved from the starting position in the direction of the secondary chamber 29 passes a second portion 30 b of the piston 30 in the region of the discharge opening of the secondary chamber 29, whereupon the discharge opening is released, so that the hydraulic fluid located in the secondary chamber 29 can flow into the storage chamber 20.
Die spezielle Ausgestaltung des Pedalwegsimulators 25 kann auch für einen Druckabbau im Hinterachs-Bremskreis 3 im Normalfall genutzt werden. Mit Beendigung des Bremsvorgangs wird Bremsfluid aus den Radbremseinheiten 10 und 1 1 über das geöffnete Umschaltventil 12 in die Sekundärkammer 29 des Pedalwegsimulators 25 geleitet, wobei die Zuströmöffnung in die Sekundärkammer 29 von dem in Öffnungsstellung stehenden Kolben 30 freigegeben ist. The special embodiment of the pedal travel simulator 25 can also be used for a pressure reduction in the rear axle brake circuit 3 in the normal case. With the completion of the braking process brake fluid from the wheel brake 10 and 1 1 is passed through the open switching valve 12 in the secondary chamber 29 of the pedal travel 25, wherein the inflow opening is released into the secondary chamber 29 of the open-ended piston 30.
Im Ablaufdiagramm gemäß Fig. 3 ist der Ablauf zur Durchführung des Verfahrens illustriert. Zunächst wird in einem ersten Verfahrensschritt 40 der bei einer Betätigung des Bremspedals zurückgelegte Pedalweg s mithilfe des Pedalwegsensors gemessen und daraus ein Sollbremsmoment MBr bestimmt. Im nächsten Verfahrensschritt 41 wird festgestellt, ob aktuell im Fahrzeug Zusatzbremsmomente wirken, beispielsweise elektrische Bremsmomente eines im Rekuperati- onsbetrieb arbeitenden elektrischen Antriebsmotors des Fahrzeugs. Derartige Bremsmomente Meι werden im Regel- bzw. Steuergerät erfasst und weiter verarbeitet. In the flowchart of FIG. 3, the procedure for carrying out the method is illustrated. First, in a first method step 40, the pedal travel s traveled on actuation of the brake pedal is measured with the aid of the pedal travel sensor and a desired braking torque M Br determined therefrom. In the next method step 41, it is determined whether additional braking torques are currently active in the vehicle, for example electric braking torques of an electric drive motor of the vehicle operating in recuperation mode. such Braking torques M e ι be detected in the control or control unit and further processed.
Ausgehend von dem Sollbremsmoment MBr und dem Zusatzbremsmoment Meι wird im Verfahrensschritt 42 ein Radbremsmoment Mw für den Hinterachsbrems- kreis bestimmt. Das mechanische Radbremsmoment Mw, das in den Radbremseinheiten der Hinterräder erzeugt wird, wird durch Beaufschlagung der Hydraulikpumpe für den Hinterachsbremskreis generiert, wobei das Radbremsmoment Mw in der Weise eingestellt wird, dass im Fahrzeug unter Berücksichtigung des Zusatzbremsmomentes Meι das gewünschte Sollbremsmoment MBr wirksam wird.Based on the desired braking torque M Br and the additional braking torque M e ι a wheel braking M w for the Hinterachsbrems- circle is determined in step 42. The mechanical wheel braking torque M w generated in the wheel brake units of the rear wheels is generated by acting on the hydraulic pump for the Hinterachsbremskreis, wherein the wheel braking is set in such a manner that in the vehicle taking into account the additional braking torque M e ι the desired braking torque M Br takes effect.
Die Einstellung des Radbremsmomentes Mw erfolgt im Verfahrensschritt 43 durch Beaufschlagung der Hydraulikpumpe für den Hinterachsbremskreis mittels des der Hydraulikpumpe zugeordneten elektromotorischen Antriebs. The setting of the wheel brake torque M w takes place in method step 43 by acting on the hydraulic pump for the rear axle brake circuit by means of the electric motor drive assigned to the hydraulic pump.

Claims

Ansprüche claims
1. Hydraulische Fahrzeugbremsanlage (1 ), mit einem Hauptbremszylinder (4), der von einem Bremspedal (6) betätigbar ist, mit mindestens einer Speicherkammer (20), einer Hydraulikpumpe (17) und einer Radbremseinheit (10, 1 1 ), dadurch gekennzeichnet, dass ein Pedalwegsimulator (25) mit einer1. Hydraulic vehicle brake system (1), with a master cylinder (4), which is actuated by a brake pedal (6), with at least one storage chamber (20), a hydraulic pump (17) and a wheel brake (10, 1 1), characterized in that a pedal travel simulator (25) is provided with a
Primärkammer (28), welche mit dem Hauptbremszylinder (4) strömungsver- bunden ist, und einer Sekundärkammer (29), welche mit der Speicherkammer (20) strömungsverbunden ist, in einem Bremskreis (3) der Fahrzeugbremsanlage (1 ) angeordnet ist, wobei Primär- und Sekundärkammer (28, 29) über einen verschieblichen Kolben (30) separiert sind, dass die Hydraulikpumpe (17) mit der Speicherkammer (20) verbunden ist, und mit einer Regel- bzw. Steuereinheit (23) zur Ansteuerung der Hydraulikpumpe (17) zur Erzeugung eines Radbremsmoments (Mw) in der Radbremseinheit. Primary chamber (28), which is fluidly connected to the master cylinder (4), and a secondary chamber (29), which is fluidly connected to the storage chamber (20) arranged in a brake circuit (3) of the vehicle brake system (1), wherein primary and secondary chamber (28, 29) via a displaceable piston (30) are separated, that the hydraulic pump (17) with the storage chamber (20) is connected, and with a control unit (23) for controlling the hydraulic pump (17 ) for generating a wheel braking torque (M w ) in the wheel brake unit.
2. Fahrzeugbremsanlage nach Anspruch 1 , dadurch gekennzeichnet, dass die2. Vehicle brake system according to claim 1, characterized in that the
Primärkammer (28) des Pedalwegsimulators (25) über ein einstellbares Hydraulikventil (26) mit den Radbremseinheiten (10, 1 1 ) des Bremskreises (3) verbunden ist. Primary chamber (28) of the pedal travel simulator (25) via an adjustable hydraulic valve (26) with the Radbremseinheiten (10, 1 1) of the brake circuit (3) is connected.
3. Fahrzeugbremsanlage nach Anspruch 2 dadurch gekennzeichnet, dass das3. Vehicle brake system according to claim 2, characterized in that the
Hydraulikventil (26) als stromlos offenes Ventil ausgeführt ist. Hydraulic valve (26) is designed as a normally open valve.
4. Fahrzeugbremsanlage nach einem der Ansprüche 1 bis 3, dadurch gekennzeichnet, dass die Sekundärkammer (29) des Pedalwegsimulators (25) über eine verschließbare Stelleinrichtung mit der Speicherkammer (20) verbunden ist. 4. Vehicle brake system according to one of claims 1 to 3, characterized in that the secondary chamber (29) of the pedal travel simulator (25) via a closable adjusting device with the storage chamber (20) is connected.
5. Fahrzeugbremsanlage nach Anspruch 4, dadurch gekennzeichnet, dass die verschließbare Stelleinrichtung als ein dem Pedalwegsimulator (25) nachge- schaltetes Hydraulikventil (27) ausgebildet ist. 5. A vehicle brake system according to claim 4, characterized in that the closable adjusting device as a the pedal travel simulator (25) downstream switched hydraulic valve (27) is formed.
6. Fahrzeugbremsanlage nach Anspruch 4, dadurch gekennzeichnet, dass die verschließbare Stelleinrichtung den zwischen Primär- und Sekundärkammer (28, 29) des Pedalwegsimulators (25) verschieblich angeordneten Kolben (30) umfasst, der zwischen einer den Strömungsweg zur Speicherkammer (20) verschließenden Ausgangsposition und einer den Strömungsweg freigebenden Öffnungsposition verstellbar ist, wobei die Öffnungsposition der in Richtung der Sekundärkammer (29) verschobenen Position des Kolbens (30) entspricht. 6. Vehicle brake system according to claim 4, characterized in that the closable adjusting device comprises between the primary and secondary chambers (28, 29) of the pedal travel simulator (25) displaceably arranged pistons (30) between a flow path to the storage chamber (20) occluding starting position and an opening position releasing the flow path is adjustable, wherein the opening position corresponds to the displaced in the direction of the secondary chamber (29) position of the piston (30).
7. Fahrzeugbremsanlage nach einem der Ansprüche 1 bis 6, dadurch gekennzeichnet, dass der Pedalwegsimulator (25) nur in den Bremskreis(3) einer der beiden Fahrzeugachsen integriert ist. 7. Vehicle brake system according to one of claims 1 to 6, characterized in that the pedal travel simulator (25) is integrated only in the brake circuit (3) of one of the two vehicle axles.
8. Fahrzeugbremsanlage nach einem der Ansprüche 1 bis 7, dadurch gekenn- zeichnet, dass die Hydraulikpumpe (17) über ein einstellbares Hydraulikventil (19) mit einem Hydraulikreservoir (5) des Hauptbremszylinders (4) verbunden ist. 8. Vehicle brake system according to one of claims 1 to 7, characterized in that the hydraulic pump (17) via an adjustable hydraulic valve (19) with a hydraulic reservoir (5) of the master cylinder (4) is connected.
9. Fahrzeugbremsanlage nach Anspruch 8, dadurch gekennzeichnet, dass das Hydraulikventil (19) als stromlos geschlossenes Ventil ausgeführt ist. 9. Vehicle brake system according to claim 8, characterized in that the hydraulic valve (19) is designed as a normally closed valve.
10. Fahrzeug mit einer hydraulischen Fahrzeugbremsanlage nach einem der Ansprüche 1 bis 9. 10. Vehicle with a hydraulic vehicle brake system according to one of claims 1 to 9.
1 1. Fahrzeug nach Anspruch 10, dadurch gekennzeichnet, dass das Fahrzeug mit einem elektrischen Antriebsmotor ausgestattet ist, der im Rekuperations- bzw. Generatorbetrieb ein Bremsmoment (Meι) erzeugt. 1 1. A vehicle according to claim 10, characterized in that the vehicle is equipped with an electric drive motor which generates a braking torque (M e ι) in recuperation or generator operation.
12. Fahrzeug nach Anspruch 1 1 , dadurch gekennzeichnet, dass das Fahrzeug als Hybridfahrzeug ausgelegt ist und zusätzlich zu dem elektrischen Antriebsmotor einen Verbrennungsmotor aufweist. 12. Vehicle according to claim 1 1, characterized in that the vehicle is designed as a hybrid vehicle and in addition to the electric drive motor comprises an internal combustion engine.
13. Verfahren zum Betrieb einer hydraulischen Fahrzeugbremsanlage (1 ) nach einem der Ansprüche 1 bis 9, bei dem 13. A method for operating a hydraulic vehicle brake system (1) according to one of claims 1 to 9, wherein
- aus der Bremspedalstellung ein Sollbremsmoment (MBr) festgestellt wird, ein von einer Zusatzbremseinrichtung generiertes Zusatzbremsmoment (Mei) festgestellt wird, a desired braking torque (M Br ) is determined from the brake pedal position, a supplementary braking torque (Mei) generated by an additional braking device is determined,
die Hydraulikpumpe (17) in der Weise betätigt wird, dass das über die Radbremseinheit (10, 11 ) erzeugte Radbremsmoment (Mw) aus der Differenz zwischen Sollbremsmoment (MBr) und Zusatzbremsmoment (Mei) berechnet wird. the hydraulic pump (17) is actuated in such a way that the wheel brake torque (M w ) generated via the wheel brake unit (10, 11) is calculated from the difference between the setpoint brake torque (M Br ) and additional brake torque (Mei).
14. Verfahren nach Anspruch 13, dadurch gekennzeichnet, dass die Zusatzbremseinrichtung ein als Generator betriebener Elektromotor ist. 14. The method according to claim 13, characterized in that the additional brake device is a generator operated as an electric motor.
15. Verfahren nach Anspruch 13 oder 14, dadurch gekennzeichnet, dass im 15. The method according to claim 13 or 14, characterized in that in
Vorderachs-Bremskreis (2) und im Hinterachs-Bremskreis (3) unterschiedlich hohe Radbremsmomente (Mw) erzeugt werden.  Front axle brake circuit (2) and in the rear axle brake circuit (3) different levels of wheel braking torque (Mw) are generated.
16. Verfahren nach einem der Ansprüche 13 bis 16, dadurch gekennzeichnet, dass in dem Bremskreis (3), welcher den Pedalwegsimulator (25) enthält, bei Betätigung der Hydraulikpumpe (17) durch Ansteuerung von Einlass- bzw. Auslassventilen (13, 14) der dem Bremskreis (3) zugeordneten Radbremseinheiten (10, 11 ) unterschiedlich hohe Bremsmomente (Mw) an den Fahr- zeugrädern erzeugt werden. 16. The method according to any one of claims 13 to 16, characterized in that in the brake circuit (3), which contains the pedal travel simulator (25) upon actuation of the hydraulic pump (17) by controlling inlet or outlet valves (13, 14) the braking brake units (10, 11) assigned to the brake circuit (3) generate braking torques (M w ) of different levels on the vehicle wheels.
EP10728145A 2009-07-27 2010-05-31 Hydraulic vehicle brake system, vehicle equipped with such a brake system, and method for operating a hydraulic vehicle brake system Withdrawn EP2459422A1 (en)

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DE200910028028 DE102009028028A1 (en) 2009-07-27 2009-07-27 Hydraulic vehicle brake system and method for operating a hydraulic vehicle brake system
PCT/EP2010/057509 WO2011012346A1 (en) 2009-07-27 2010-05-31 Hydraulic vehicle brake system, vehicle equipped with such a brake system, and method for operating a hydraulic vehicle brake system

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US9050955B2 (en) 2015-06-09
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DE102009028028A1 (en) 2011-02-03
CN102470841B (en) 2015-11-25

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