WO2020025187A1 - Method for operating a hydraulic power-assisted brake system and/or hydraulic power brake system of a vehicle - Google Patents

Method for operating a hydraulic power-assisted brake system and/or hydraulic power brake system of a vehicle Download PDF

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Publication number
WO2020025187A1
WO2020025187A1 PCT/EP2019/063554 EP2019063554W WO2020025187A1 WO 2020025187 A1 WO2020025187 A1 WO 2020025187A1 EP 2019063554 W EP2019063554 W EP 2019063554W WO 2020025187 A1 WO2020025187 A1 WO 2020025187A1
Authority
WO
WIPO (PCT)
Prior art keywords
brake
master
vehicle
cylinder
brake system
Prior art date
Application number
PCT/EP2019/063554
Other languages
German (de)
French (fr)
Inventor
Andreas SWACZINNA
Tim-Philipp Jesse
Peter Ziegler
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 WO2020025187A1 publication Critical patent/WO2020025187A1/en

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Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60T—VEHICLE BRAKE CONTROL SYSTEMS OR PARTS THEREOF; BRAKE CONTROL SYSTEMS OR PARTS THEREOF, IN GENERAL; ARRANGEMENT OF BRAKING ELEMENTS ON VEHICLES IN GENERAL; PORTABLE DEVICES FOR PREVENTING UNWANTED MOVEMENT OF VEHICLES; VEHICLE MODIFICATIONS TO FACILITATE COOLING OF BRAKES
    • B60T7/00—Brake-action initiating means
    • B60T7/02—Brake-action initiating means for personal initiation
    • B60T7/04—Brake-action initiating means for personal initiation foot actuated
    • B60T7/042—Brake-action initiating means for personal initiation foot actuated by electrical means, e.g. using travel or force sensors
    • 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
    • B60T13/16—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 pumps directly, i.e. without interposition of accumulators or reservoirs
    • B60T13/18—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 pumps directly, i.e. without interposition of accumulators or reservoirs with control of pump output delivery, e.g. by distributor valves
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60T—VEHICLE BRAKE CONTROL SYSTEMS OR PARTS THEREOF; BRAKE CONTROL SYSTEMS OR PARTS THEREOF, IN GENERAL; ARRANGEMENT OF BRAKING ELEMENTS ON VEHICLES IN GENERAL; PORTABLE DEVICES FOR PREVENTING UNWANTED MOVEMENT OF VEHICLES; VEHICLE MODIFICATIONS TO FACILITATE COOLING OF BRAKES
    • B60T13/00—Transmitting braking action from initiating means to ultimate brake actuator with power assistance or drive; Brake systems incorporating such transmitting means, e.g. air-pressure brake systems
    • B60T13/10—Transmitting braking action from initiating means to ultimate brake actuator with power assistance or drive; Brake systems incorporating such transmitting means, e.g. air-pressure brake systems with fluid assistance, drive, or release
    • B60T13/66—Electrical control in fluid-pressure brake systems
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60T—VEHICLE BRAKE CONTROL SYSTEMS OR PARTS THEREOF; BRAKE CONTROL SYSTEMS OR PARTS THEREOF, IN GENERAL; ARRANGEMENT OF BRAKING ELEMENTS ON VEHICLES IN GENERAL; PORTABLE DEVICES FOR PREVENTING UNWANTED MOVEMENT OF VEHICLES; VEHICLE MODIFICATIONS TO FACILITATE COOLING OF BRAKES
    • B60T13/00—Transmitting braking action from initiating means to ultimate brake actuator with power assistance or drive; Brake systems incorporating such transmitting means, e.g. air-pressure brake systems
    • B60T13/10—Transmitting braking action from initiating means to ultimate brake actuator with power assistance or drive; Brake systems incorporating such transmitting means, e.g. air-pressure brake systems with fluid assistance, drive, or release
    • B60T13/66—Electrical control in fluid-pressure brake systems
    • B60T13/662—Electrical control in fluid-pressure brake systems characterised by specified functions of the control system components
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60T—VEHICLE BRAKE CONTROL SYSTEMS OR PARTS THEREOF; BRAKE CONTROL SYSTEMS OR PARTS THEREOF, IN GENERAL; ARRANGEMENT OF BRAKING ELEMENTS ON VEHICLES IN GENERAL; PORTABLE DEVICES FOR PREVENTING UNWANTED MOVEMENT OF VEHICLES; VEHICLE MODIFICATIONS TO FACILITATE COOLING OF BRAKES
    • B60T13/00—Transmitting braking action from initiating means to ultimate brake actuator with power assistance or drive; Brake systems incorporating such transmitting means, e.g. air-pressure brake systems
    • B60T13/10—Transmitting braking action from initiating means to ultimate brake actuator with power assistance or drive; Brake systems incorporating such transmitting means, e.g. air-pressure brake systems with fluid assistance, drive, or release
    • B60T13/66—Electrical control in fluid-pressure brake systems
    • B60T13/68—Electrical control in fluid-pressure brake systems by electrically-controlled valves
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60T—VEHICLE BRAKE CONTROL SYSTEMS OR PARTS THEREOF; BRAKE CONTROL SYSTEMS OR PARTS THEREOF, IN GENERAL; ARRANGEMENT OF BRAKING ELEMENTS ON VEHICLES IN GENERAL; PORTABLE DEVICES FOR PREVENTING UNWANTED MOVEMENT OF VEHICLES; VEHICLE MODIFICATIONS TO FACILITATE COOLING OF BRAKES
    • B60T13/00—Transmitting braking action from initiating means to ultimate brake actuator with power assistance or drive; Brake systems incorporating such transmitting means, e.g. air-pressure brake systems
    • B60T13/10—Transmitting braking action from initiating means to ultimate brake actuator with power assistance or drive; Brake systems incorporating such transmitting means, e.g. air-pressure brake systems with fluid assistance, drive, or release
    • B60T13/66—Electrical control in fluid-pressure brake systems
    • B60T13/68—Electrical control in fluid-pressure brake systems by electrically-controlled valves
    • B60T13/686—Electrical control in fluid-pressure brake systems by electrically-controlled valves in hydraulic systems or parts thereof
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60T—VEHICLE BRAKE CONTROL SYSTEMS OR PARTS THEREOF; BRAKE CONTROL SYSTEMS OR PARTS THEREOF, IN GENERAL; ARRANGEMENT OF BRAKING ELEMENTS ON VEHICLES IN GENERAL; PORTABLE DEVICES FOR PREVENTING UNWANTED MOVEMENT OF VEHICLES; VEHICLE MODIFICATIONS TO FACILITATE COOLING OF BRAKES
    • 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
    • B60T13/74—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 electrical assistance or drive
    • 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
    • B60T13/74—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 electrical assistance or drive
    • B60T13/745—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 electrical assistance or drive acting on a hydraulic system, e.g. a master cylinder
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60T—VEHICLE BRAKE CONTROL SYSTEMS OR PARTS THEREOF; BRAKE CONTROL SYSTEMS OR PARTS THEREOF, IN GENERAL; ARRANGEMENT OF BRAKING ELEMENTS ON VEHICLES IN GENERAL; PORTABLE DEVICES FOR PREVENTING UNWANTED MOVEMENT OF VEHICLES; VEHICLE MODIFICATIONS TO FACILITATE COOLING OF BRAKES
    • B60T17/00—Component parts, details, or accessories of power brake systems not covered by groups B60T8/00, B60T13/00 or B60T15/00, or presenting other characteristic features
    • B60T17/18—Safety devices; Monitoring
    • B60T17/22—Devices for monitoring or checking brake systems; Signal devices
    • B60T17/221—Procedure or apparatus for checking or keeping in a correct functioning condition of brake 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
    • B60T17/00—Component parts, details, or accessories of power brake systems not covered by groups B60T8/00, B60T13/00 or B60T15/00, or presenting other characteristic features
    • B60T17/18—Safety devices; Monitoring
    • B60T17/22—Devices for monitoring or checking brake systems; Signal devices
    • B60T17/226—Devices for monitoring or checking brake systems; Signal devices using devices being responsive to the difference between the fluid pressions in conduits of multiple braking systems
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60T—VEHICLE BRAKE CONTROL SYSTEMS OR PARTS THEREOF; BRAKE CONTROL SYSTEMS OR PARTS THEREOF, IN GENERAL; ARRANGEMENT OF BRAKING ELEMENTS ON VEHICLES IN GENERAL; PORTABLE DEVICES FOR PREVENTING UNWANTED MOVEMENT OF VEHICLES; VEHICLE MODIFICATIONS TO FACILITATE COOLING OF BRAKES
    • B60T8/00—Arrangements for adjusting wheel-braking force to meet varying vehicular or ground-surface conditions, e.g. limiting or varying distribution of braking force
    • B60T8/32—Arrangements for adjusting wheel-braking force to meet varying vehicular or ground-surface conditions, e.g. limiting or varying distribution of braking force responsive to a speed condition, e.g. acceleration or deceleration
    • B60T8/34—Arrangements for adjusting wheel-braking force to meet varying vehicular or ground-surface conditions, e.g. limiting or varying distribution of braking force responsive to a speed condition, e.g. acceleration or deceleration having a fluid pressure regulator responsive to a speed condition
    • B60T8/40—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
    • 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
    • B60T8/88—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 with failure responsive means, i.e. means for detecting and indicating faulty operation of the speed responsive control means
    • B60T8/92—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 with failure responsive means, i.e. means for detecting and indicating faulty operation of the speed responsive control means automatically taking corrective action
    • 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
    • B60T2220/00—Monitoring, detecting driver behaviour; Signalling thereof; Counteracting thereof
    • B60T2220/04—Pedal travel sensor, stroke sensor; Sensing brake request
    • 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
    • B60T2270/00—Further aspects of brake control systems not otherwise provided for
    • B60T2270/40—Failsafe aspects of brake control systems
    • B60T2270/402—Back-up
    • 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
    • B60T2270/00—Further aspects of brake control systems not otherwise provided for
    • B60T2270/40—Failsafe aspects of brake control systems
    • B60T2270/403—Brake circuit failure

Definitions

  • the invention relates to a method for operating a hydraulic auxiliary and / or external vehicle brake system with the features of the preamble of claim 1.
  • International patent application WO 2012/150 120 A1 discloses a hydraulic auxiliary and external power vehicle brake system with a master brake cylinder which can be actuated by muscle power by means of a brake pedal.
  • the known vehicle brake system has a power brake pressure generator with a piston-cylinder unit, the piston of which can be displaced with an electric motor via a screw drive in the cylinder in order to generate a brake pressure.
  • Service braking is carried out as external power braking, in which brake pressure is generated with the external power brake pressure generator.
  • the master brake cylinder is hydraulically separated from the vehicle brake system by closing a separating valve.
  • the master brake cylinder serves as a setpoint generator for the brake pressure to be generated with the power brake pressure generator.
  • the brake pressure is generated as usual by muscle power with the master brake cylinder.
  • the known vehicle brake system has an electrohydraulic brake booster with a hydraulic pump which can be driven by an electric motor and which increases a master brake cylinder pressure. Disclosure of the invention
  • the method according to the invention with the features of claim 1 provides a relationship between a wheel brake pressure in at least one wheel brake and an actuating force of a master brake cylinder and / or to change an actuation path of the master brake cylinder and / or a master brake cylinder pressure in the master brake cylinder, in particular to reduce the wheel brake pressure in the at least one wheel brake in relation to the actuation force and / or the actuation path of the master brake cylinder and / or the master brake cylinder pressure.
  • a vehicle driver receives haptic feedback that something has changed in the vehicle brake system. In particular, the vehicle driver gets the feeling that the vehicle brake system brakes worse.
  • a fault in a vehicle brake system is, for example, a failure of a wheel brake or a brake circuit.
  • a functional restriction is, for example, air in the vehicle brake system, which is compensated for in the case of external power braking and is therefore not noticed by the vehicle driver. If the power brake pressure generator fails, the air becomes noticeable through an extended actuation path of the master brake cylinder due to the compressibility of brake fluid containing air.
  • the invention is intended in particular for so-called “hidden errors”, which means errors that the vehicle driver would not perceive without the method according to the invention, for example because it is compensated for by a brake booster or the external power brake pressure generator or has an effect on a further error Have braking behavior of the vehicle brake system.
  • FIG. 1 shows a diagram of a hydraulic auxiliary and external vehicle brake system to explain the method according to the invention.
  • Figure 2 shows a pedal characteristic curve
  • the hydraulic vehicle brake system shown in simplified form in FIG. 1 is an auxiliary and external vehicle brake system. It has a master brake cylinder 1 to which one or preferably several brake circuits, each with one or more hydraulic wheel brakes 2, are connected. A single-circuit master brake cylinder 1 is drawn, to which a brake circuit is connected.
  • the vehicle brake system preferably has a two-circuit master brake cylinder 1, to which two brake circuits, each with one or more wheel brakes 2, are connected. For example, the vehicle brake system has two wheel brakes 2 in each brake circuit.
  • the master brake cylinder 1 can be actuated with muscle power by means of a brake pedal 3 or a hand brake lever (not shown) and has a controllable, electromechanical brake booster 4.
  • the brake booster 4 amplifies the actuating force exerted by muscle force on the master brake cylinder 1, strictly speaking on a piston of the master brake cylinder 1.
  • the master brake cylinder 1 can be a controllable vacuum brake booster, for example, or the vehicle brake system can use an electro-hydraulic brake have power booster.
  • Auxiliary vehicle brake system means that the master brake cylinder 1 and thus the vehicle brake system can be actuated with muscular strength by an amplifying force of the brake booster.
  • An electrohydraulic brake booster instead increases a brake pressure generated with the master cylinder 1.
  • the brake booster 4 is controllable, which means that its gain can be adjusted or changed.
  • the vehicle brake system has an electronic control unit 5 which receives signals from a pedal travel sensor 6, a pedal force sensor (not shown) and / or from a pressure sensor 7 which is connected to the master brake cylinder 1.
  • the signals of the pedal travel sensor 6, the pedal force sensor and the pressure sensor 7 are dependent on one another, in principle one of the measured variables is sufficient as the input signal of the control device 5. For redundancy, another of the three variables or all three variables can be measured.
  • the vehicle brake system has an external brake pressure generator 8 with a piston-cylinder unit 9, the piston 10 of which can be displaced in a cylinder 12 by means of a screw drive (not shown) in order to generate a brake pressure in the vehicle brake system with an electric motor 11.
  • the cylinder 12 of the piston-cylinder unit 9 of the external brake pressure generator 8 can be hydraulically connected to the vehicle brake system by an external power valve 13.
  • a brake pressure is generated with the external power brake pressure generator 8 and the brake pressure (s) are applied to the wheel brake (s) 2 by opening the external power valve 13.
  • the main brake cylinder 1 is hydraulically separated from the vehicle brake system by closing a separating valve 14.
  • the master brake cylinder 1 serves as a setpoint generator for the brake pressure to be generated by the external power brake pressure generator 8, which is regulated by the control unit 5 as a function of the pedal force, the pedal travel and / or the master brake cylinder pressure.
  • a pressure sensor 15 is connected to the cylinder 12 of the external brake pressure generator 8.
  • one or more brake circuits and / or one or more re or all wheel brakes 2 have a pressure sensor for pressure control (not shown).
  • the wheel brake 2 or the wheel brakes 2 are actuated only in the event of a fault or a failure of the power brake pressure generator 8.
  • Each wheel brake 2 is assigned an inlet valve 16 and an outlet valve 17, with which slip control systems such as anti-lock protection, traction control systems, and driving dynamics or anti-skid control systems are possible in a manner known per se.
  • slip control systems such as anti-lock protection, traction control systems, and driving dynamics or anti-skid control systems are possible in a manner known per se.
  • ABS, ASR and FDR or ESP are used for these slip rules.
  • the brake pressure control takes place with the external force brake pressure generator 8 and / or the intake valves 16 and exhaust valves 17
  • valves 13, 14, 16, 17 are 2/2-way solenoid valves, but this is not essential for the invention.
  • a linear, a degressive or a progressive dependency between the wheel brake pressure in the / n wheel brake / n 2 and the pedal travel and / or the pedal force of the master brake cylinder 1 and / or the master brake cylinder pressure is possible.
  • the dependency is referred to here as the pedal characteristic and in the described embodiment is progressive as shown in curve 18 in FIG. 2, which shows the pedal travel s on the abscissa and the wheel brake pressure p on the ordinate.
  • different wheel brake pressures are possible in the wheel brakes 2, provided the vehicle brake system has a plurality of wheel brakes 2 with inlet and outlet valves 16, 17.
  • the pedal characteristic is progressive, that is, the wheel brake pressure increases disproportionately with increasing pedal travel and pedal force.
  • a linear, degressive, progressive and basically any dependency between the wheel brake pressure and the pedal travel, the pedal force and / or the master cylinder pressure is possible with the external brake pressure generator 8 and / or the controllable brake booster 4.
  • the dependency between the wheel brake pressure is on the one hand and the pedal travel, the pedal force and / or the master brake cylinder pressure on the other hand changed, in particular reduced, so that a vehicle driver has the feeling that the vehicle brake system is braking less well.
  • the vehicle driver is made aware of the fault or the functional limitation of the vehicle brake system.
  • a possible fault is air in the vehicle brake system, which makes the brake fluid compressible. If the vehicle brake system was actuated by external power with the external brake pressure generator 8, the fault would not be noticed without the inventive method, because the master brake cylinder 1 is hydraulically separated from the vehicle brake system by closing the isolating valve 14 and with the external brake pressure generator 8 despite the compressibility of the brake fluid by the Setpoint-dependent brake pressure or wheel brake pressure is generated. It is a so-called “hidden fault”, which is not perceptible to the vehicle driver or is only perceived if the vehicle brake system is actuated with the master brake cylinder 1 in the event of a malfunction or failure of the power brake pressure generator 8.
  • Such faults or functional restrictions can be detected using test methods that are carried out automatically by the electronic control unit 5 and in which one Pressure generated by the external brake pressure generator 8, the valves 13, 14, 16, 17 switched differently and pressures with the pressure sensors 7, 15 and movements of the external brake pressure generator 8 are measured. If the values deviate from the values with a fully functional vehicle brake system, this indicates a functional restriction or an error. If no deviations are measured, the vehicle brake system is considered to be fully functional and has the pedal characteristic provided for it, in the embodiment described the progressive pedal characteristic represented by curve 18 in the diagram in FIG. 2.
  • the pedal characteristic is changed as written, in the described embodiment of the invention the ratio between the wheel brake pressure and the actuation path and / or the actuation force of the master cylinder 1 and / or the master cylinder pressure is reduced.
  • a variant of the method according to the invention provides that at the same time the progression of the pedal characteristic is increased as shown in curve 19 in FIG. 2. This means that when the master brake cylinder 1 is actuated, the wheel brake pressure initially increases less and later than in the case of a fully functional vehicle brake system.
  • the curves 18, 19 intersect at a point 20 at which the wheel brake pressure, the actuation force, the actuation travel and the master cylinder pressure are the same in the event of a fault or a functional restriction of the vehicle brake system as in the case of a fully functional vehicle brake system. If the pressure increases further, the curve 19 of the pedal characteristic can continue to rise more, the same or less strongly than in the case of a fully functional vehicle brake system when the vehicle brake system is impaired or defective.
  • point 20 can be specified as required by law, for example for a vehicle deceleration of 6.43 m / s 2 with a pedal force of 500 N. At point 20, a higher full deceleration than the legally prescribed deceleration is also possible.
  • the full deceleration is a vehicle deceleration for the respective vehicle brake system and a vehicle equipped with it with the pedal force of 500 N. As written, it is higher than the legally prescribed vehicle deceleration and typically corresponds to the acceleration due to gravity of 9.81 m / s 2 ,
  • a variant of the method according to the invention provides, for example, an optical, acoustic and / or haptic warning of the vehicle driver in the event of an error or a functional restriction of the vehicle brake system, the optical warning 21 being shown in FIG. 1 with the symbol of a light source 21.
  • the pedal characteristic can be changed as shown by curve 22 in FIG. 2 in such a way that in point 23 a lower deceleration, for example a statutory deceleration, occurs for example with the pedal force of 500 N.
  • an optical and / or other warning prescribed deceleration of 2.44 m / s 2 with the pedal force of 500 N is reached.
  • a haptic warning of one or a functional restriction of the vehicle brake system in addition to the changed pedal characteristics, it is possible, for example, to reduce the power of a drive motor and / or to limit the speed of a motor vehicle.
  • comfort functions and / or automated driving functions such as cruise control and / or adaptive cruise control (preferably speed-dependent distance control to a vehicle in front, abbreviation: ACC, English: Adaptive Cruise Control). All of these warnings alert a driver that something is wrong.

Abstract

In order to alert a driver of an error or a limitation in functionality of a hydraulic power-assisted brake system and/or hydraulic power brake system of a vehicle, a wheel brake pressure is reduced depending on a pedal force or a pedal travel.

Description

Verfahren zum Betrieb einer hydraulischen Hilfskraft- und/oder Fremdkraft- Method for operating a hydraulic auxiliary and / or external power
Fahrzeuqbremsanlaqe Fahrzeuqbremsanlaqe
Beschreibung description
Die Erfindung betrifft ein Verfahren zum Betrieb einer hydraulischen Hilfskraft- und/oder Fremdkraft-Fahrzeugbremsanlage mit den Merkmalen des Oberbegriffs des Anspruchs 1. The invention relates to a method for operating a hydraulic auxiliary and / or external vehicle brake system with the features of the preamble of claim 1.
Stand der Technik State of the art
Die internationale Patentanmeldung WO 2012/150 120 A1 offenbart eine hydrau- lische Hilfskraft- und Fremdkraft-Fahrzeugbremsanlage mit einem Hauptbrems- zylinder, der mittels eines Bremspedals durch Muskelkraft betätigbar ist. Außer- dem weist die bekannte Fahrzeugbremsanlage einen Fremdkraft- Bremsdruckerzeuger mit einer Kolben-Zylinder-Einheit auf, deren Kolben zur Er- zeugung eines Bremsdrucks mit einem Elektromotor über einen Gewindetrieb im Zylinder verschiebbar ist. Eine Betriebsbremsung wird als Fremdkraftbremsung durchgeführt, bei der ein Bremsdruck mit dem Fremdkraft-Bremsdruckerzeuger erzeugt wird. Der Hauptbremszylinder wird bei einer Betriebsbremsung durch Schließen eines Trennventils hydraulisch von der Fahrzeugbremsanlage ge- trennt. Der Hauptbremszylinder dient bei einer Betriebsbremsung als Sollwertge- ber für den mit dem Fremdkraft-Bremsdruckerzeuger zu erzeugenden Brems- druck. Bei einem Ausfall oder einer Störung des Fremdkraft- Bremsdruckerzeugers wird der Bremsdruck wie üblich durch Muskelkraft mit dem Hauptbremszylinder erzeugt. Dafür weist die bekannte Fahrzeugbremsanlage ei- nen elektrohydraulischen Bremskraftverstärker mit einer Hydropumpe auf, die mit einem Elektromotor antreibbar ist und die einen Hauptbremszylinderdruck ver- stärkt. Offenbarung der Erfindung International patent application WO 2012/150 120 A1 discloses a hydraulic auxiliary and external power vehicle brake system with a master brake cylinder which can be actuated by muscle power by means of a brake pedal. In addition, the known vehicle brake system has a power brake pressure generator with a piston-cylinder unit, the piston of which can be displaced with an electric motor via a screw drive in the cylinder in order to generate a brake pressure. Service braking is carried out as external power braking, in which brake pressure is generated with the external power brake pressure generator. In the case of service braking, the master brake cylinder is hydraulically separated from the vehicle brake system by closing a separating valve. In the case of service braking, the master brake cylinder serves as a setpoint generator for the brake pressure to be generated with the power brake pressure generator. In the event of failure or malfunction of the external brake pressure generator, the brake pressure is generated as usual by muscle power with the master brake cylinder. For this purpose, the known vehicle brake system has an electrohydraulic brake booster with a hydraulic pump which can be driven by an electric motor and which increases a master brake cylinder pressure. Disclosure of the invention
Für den Fall eines Fehlers oder einer Funktionseinschränkung einer hydrauli- schen Hilfskraft- und/oder Fremdkraft-Fahrzeugbremsanlage sieht das erfin- dungsgemäße Verfahren mit den Merkmalen des Anspruchs 1 vor, ein Verhältnis zwischen einem Radbremsdruck in mindestens einer Radbremse und einer Betä- tigungskraft eines Hauptbremszylinders und/oder einem Betätigungsweg des Hauptbremszylinders und/oder einem Hauptbremszylinderdruck im Hauptbrems- zylinder zu ändern, insbesondere den Radbremsdruck in der mindestens einen Radbremse im Verhältnis zur Betätigungskraft und/oder dem Betätigungsweg des Hauptbremszylinders und/oder dem Hauptbremszylinderdruck zu reduzieren. Ein Fahrzeugführer erhält dadurch bei einer Betätigung des Hauptbremszylinders eine haptisches Rückmeldung, dass sich etwas an der Fahrzeugbremsanlage geändert hat. Insbesondere erhält der Fahrzeugführer das Gefühl, die Fahrzeug- bremsanlage bremse schlechter. In the event of a fault or a functional restriction of a hydraulic auxiliary power and / or external vehicle brake system, the method according to the invention with the features of claim 1 provides a relationship between a wheel brake pressure in at least one wheel brake and an actuating force of a master brake cylinder and / or to change an actuation path of the master brake cylinder and / or a master brake cylinder pressure in the master brake cylinder, in particular to reduce the wheel brake pressure in the at least one wheel brake in relation to the actuation force and / or the actuation path of the master brake cylinder and / or the master brake cylinder pressure. As a result, when the master brake cylinder is actuated, a vehicle driver receives haptic feedback that something has changed in the vehicle brake system. In particular, the vehicle driver gets the feeling that the vehicle brake system brakes worse.
Ein Fehler einer Fahrzeugbremsanlage ist beispielsweise ein Ausfall einer Rad- bremse oder eines Bremskreises. Eine Funktionseinschränkung ist beispielswei- se Luft in der Fahrzeugbremsanlage, die bei einer Fremdkraftbremsung ausge- glichen und deswegen vom Fahrzeugführer nicht bemerkt wird. Wenn der Fremdkraft-Bremsdruckerzeuger ausfällt, macht sich die Luft durch einen verlän- gerten Betätigungsweg des Hauptbremszylinders infolge von Kompressibilität von Luft enthaltender Bremsflüssigkeit bemerkbar. A fault in a vehicle brake system is, for example, a failure of a wheel brake or a brake circuit. A functional restriction is, for example, air in the vehicle brake system, which is compensated for in the case of external power braking and is therefore not noticed by the vehicle driver. If the power brake pressure generator fails, the air becomes noticeable through an extended actuation path of the master brake cylinder due to the compressibility of brake fluid containing air.
Die Erfindung ist insbesondere für sogenannte„versteckte Fehler“ vorgesehen, womit Fehler gemeint sind, die ohne das erfindungsgemäße Verfahren vom Fahrzeugführer nicht wahrgenommen werden, weil sie beispielsweise von einem Bremskraftverstärker oder dem Fremdkraft-Bremsdruckerzeuger kompensiert oder erst bei einem weiteren Fehler eine Auswirkung auf ein Bremsverhalten der Fahrzeugbremsanlage haben. The invention is intended in particular for so-called “hidden errors”, which means errors that the vehicle driver would not perceive without the method according to the invention, for example because it is compensated for by a brake booster or the external power brake pressure generator or has an effect on a further error Have braking behavior of the vehicle brake system.
Die abhängigen Ansprüche haben Weiterbildungen und vorteilhafte Ausgestal- tungen der im unabhängigen Anspruch angegebenen Erfindung zum Gegen- stand. Sämtliche in der Beschreibung und der Zeichnung offenbarten Merkmale können einzeln für sich oder in grundsätzlich beliebiger Kombination bei Ausführungs- formen der Erfindung verwirklicht sein. Ausführungen der Erfindung, die nicht al- le, sondern nur ein oder mehrere Merkmale eines Anspruchs aufweisen, sind grundsätzlich möglich. The dependent claims relate to developments and advantageous refinements of the invention specified in the independent claim. All of the features disclosed in the description and the drawing can be implemented individually or in any combination in principle in embodiments of the invention. In principle, embodiments of the invention that do not have all but only one or more features of a claim are possible.
Kurze Beschreibung der Zeichnung Brief description of the drawing
Die Erfindung wird nachfolgend anhand einer in der Zeichnung dargestellten Ausführungsform näher erläutert. Es zeigen: The invention is explained below with reference to an embodiment shown in the drawing. Show it:
Figur 1 eine Schemadarstellung einer hydraulischen Hilfskraft- und Fremdkraft- Fahrzeugbremsanlage zur Erläuterung des erfindungsgemäßen Verfah- rens; und FIG. 1 shows a diagram of a hydraulic auxiliary and external vehicle brake system to explain the method according to the invention; and
Figur 2 eine Pedalcharakteristik Kennlinie.  Figure 2 shows a pedal characteristic curve.
Ausführungsform der Erfindung Embodiment of the invention
Die in Figur 1 vereinfacht dargestellte hydraulische Fahrzeugbremsanlage ist ei- ne Hilfskraft- und Fremdkraft-Fahrzeugbremsanlage. Sie weist einen Haupt- bremszylinder 1 auf, an den ein oder vorzugsweise mehrere Bremskreise mit je- weils einer oder mehreren hydraulischen Radbremsen 2 angeschlossen sind. Gezeichnet ist ein Einkreis-Hauptbremszylinder 1 , an den ein Bremskreis ange- schlossen ist. Vorzugsweise weist die Fahrzeugbremsanlage einen Zweikreis- Hauptbremszylinder 1 auf, an den zwei Bremskreise mit jeweils einer oder meh- reren Radbremsen 2 angeschlossen sind. Beispielsweise weist die Fahrzeug- bremsanlage in jedem Bremskreis zwei Radbremsen 2 auf. The hydraulic vehicle brake system shown in simplified form in FIG. 1 is an auxiliary and external vehicle brake system. It has a master brake cylinder 1 to which one or preferably several brake circuits, each with one or more hydraulic wheel brakes 2, are connected. A single-circuit master brake cylinder 1 is drawn, to which a brake circuit is connected. The vehicle brake system preferably has a two-circuit master brake cylinder 1, to which two brake circuits, each with one or more wheel brakes 2, are connected. For example, the vehicle brake system has two wheel brakes 2 in each brake circuit.
Der Hauptbremszylinder 1 ist mittels eines Bremspedals 3 oder eines nicht ge- zeichneten Handbremshebels mit Muskelkraft betätigbar und weist einen steuer- baren, elektromechanischen Bremskraftverstärker 4 auf. Der Bremskraftverstär- ker 4 verstärkt die durch Muskelkraft auf den Hauptbremszylinder 1 , genau ge- nommen auf einen Kolben des Hauptbremszylinders 1 ausgeübte Betätigungs- kraft. Anstelle des elektromechanischen Bremskraftverstärkers 4 kann beispiels- weise der Hauptbremszylinder 1 einen steuerbaren Unterdruckbremskraft- verstärker oder die Fahrzeugbremsanlage einen elektrohydraulischen Brems- kraftverstärker aufweisen. Hilfskraft-Fahrzeugbremsanlage bedeutet, dass der Hauptbremszylinder 1 und damit die Fahrzeugbremsanlage mit Muskelkraft ver- stärkt durch eine Verstärkerkraft des Bremskraftverstärkers betätigbar ist. Ein elektrohydraulischer Bremskraftverstärker erhöht stattdessen einen mit dem Hauptbremszylinder 1 erzeugten Bremsdruck. The master brake cylinder 1 can be actuated with muscle power by means of a brake pedal 3 or a hand brake lever (not shown) and has a controllable, electromechanical brake booster 4. The brake booster 4 amplifies the actuating force exerted by muscle force on the master brake cylinder 1, strictly speaking on a piston of the master brake cylinder 1. Instead of the electromechanical brake booster 4, the master brake cylinder 1 can be a controllable vacuum brake booster, for example, or the vehicle brake system can use an electro-hydraulic brake have power booster. Auxiliary vehicle brake system means that the master brake cylinder 1 and thus the vehicle brake system can be actuated with muscular strength by an amplifying force of the brake booster. An electrohydraulic brake booster instead increases a brake pressure generated with the master cylinder 1.
Der Bremskraftverstärker 4 ist steuerbar, was bedeutet, dass seine Verstärkung einstellbar bzw. veränderbar ist. Dazu weist die Fahrzeugbremsanlage ein elekt- ronisches Steuergerät 5 auf, das Signale von einem Pedalwegsensor 6, einem nicht gezeichneten Pedalkraftsensor und/oder von einem Drucksensor 7, der an den Hauptbremszylinder 1 angeschlossen ist, bekommt. Die Signale des Pedal- wegsensors 6, des Pedalkraftsensors und des Drucksensors 7 sind voneinander abhängig, es genügt grundsätzlich eine der gemessenen Größen als Eingangs- signal des Steuergeräts 5. Zwecks Redundanz können eine weitere der drei Größe oder alle drei Größen gemessen werden. The brake booster 4 is controllable, which means that its gain can be adjusted or changed. For this purpose, the vehicle brake system has an electronic control unit 5 which receives signals from a pedal travel sensor 6, a pedal force sensor (not shown) and / or from a pressure sensor 7 which is connected to the master brake cylinder 1. The signals of the pedal travel sensor 6, the pedal force sensor and the pressure sensor 7 are dependent on one another, in principle one of the measured variables is sufficient as the input signal of the control device 5. For redundancy, another of the three variables or all three variables can be measured.
Die Fahrzeugbremsanlage weist einen Fremdkraft-Bremsdruckerzeuger 8 mit ei- ner Kolben-Zylinder-Einheit 9 auf, deren Kolben 10 zur Erzeugung eines Brems- drucks in der Fahrzeugbremsanlage mit einem Elektromotor 1 1 über einen nicht dargestellten Gewindetrieb in einem Zylinder 12 verschiebbar ist. Der Zylinder 12 der Kolben-Zylinder-Einheit 9 des Fremdkraft-Bremsdruckerzeugers 8 ist durch ein Fremdkraftventil 13 hydraulisch mit der Fahrzeugbremsanlage verbindbar. The vehicle brake system has an external brake pressure generator 8 with a piston-cylinder unit 9, the piston 10 of which can be displaced in a cylinder 12 by means of a screw drive (not shown) in order to generate a brake pressure in the vehicle brake system with an electric motor 11. The cylinder 12 of the piston-cylinder unit 9 of the external brake pressure generator 8 can be hydraulically connected to the vehicle brake system by an external power valve 13.
Zu einer Betätigung der Fahrzeugbremsanlage wird ein Bremsdruck mit dem Fremdkraft-Bremsdruckerzeuger 8 erzeugt und durch Öffnen des Fremdkraftven- tils 13 die Radbremse/n 2 mit dem Bremsdruck beaufschlagt. Der Hauptbremszy- linder 1 wird dabei durch Schließen eines Trennventils 14 hydraulisch von der Fahrzeugbremsanlage getrennt. To actuate the vehicle brake system, a brake pressure is generated with the external power brake pressure generator 8 and the brake pressure (s) are applied to the wheel brake (s) 2 by opening the external power valve 13. The main brake cylinder 1 is hydraulically separated from the vehicle brake system by closing a separating valve 14.
Bei der Fremdkraftbetätigung dient der Hauptbremszylinder 1 als Sollwertgeber für den von dem Fremdkraft-Bremsdruckerzeuger 8 zu erzeugenden Brems- druck, der von dem Steuergerät 5 in Abhängigkeit von der Pedalkraft, dem Pe- dalweg und/oder dem Hauptbremszylinderdruck geregelt wird. Dazu ist an den Zylinder 12 des Fremdkraft-Bremsdruckerzeugers 8 ein Drucksensor 15 ange- schlossen. Zusätzlich oder statt des Drucksensors 15 des Fremdkraft- Bremsdruckerzeugers 8 können ein oder die Bremskreise und/oder eine, mehre- re oder alle Radbremsen 2 einen Drucksensor für die Druckregelung aufweisen (nicht dargestellt). When the external power is actuated, the master brake cylinder 1 serves as a setpoint generator for the brake pressure to be generated by the external power brake pressure generator 8, which is regulated by the control unit 5 as a function of the pedal force, the pedal travel and / or the master brake cylinder pressure. For this purpose, a pressure sensor 15 is connected to the cylinder 12 of the external brake pressure generator 8. In addition or instead of the pressure sensor 15 of the power brake pressure generator 8, one or more brake circuits and / or one or more re or all wheel brakes 2 have a pressure sensor for pressure control (not shown).
Mit dem Hauptbremszylinder 1 wird die Radbremse 2 bzw. werden die Radbrem- sen 2 nur bei einer Störung oder einem Ausfall des Fremdkraft- Bremsdruckerzeugers 8 betätigt. With the master brake cylinder 1, the wheel brake 2 or the wheel brakes 2 are actuated only in the event of a fault or a failure of the power brake pressure generator 8.
Jeder Radbremse 2 ist ein Einlassventil 16 und ein Auslassventil 17 zugeordnet, mit denen Schlupfregelungen wie Blockierschutz-, Antriebsschlupf-, und Fahrdy- namik- bzw. Schleuderschutzregelungen in an sich bekannter Weise möglich sind. Für diese Schlupfregelungen sind die Abkürzungen ABS, ASR und FDR bzw. ESP gebräuchlich. Die Bremsdruckregelung erfolgt mit dem Fremdkraft- Bremsdruckerzeuger 8 und/oder den Einlassventilen 16 und Auslassventilen 17 Each wheel brake 2 is assigned an inlet valve 16 and an outlet valve 17, with which slip control systems such as anti-lock protection, traction control systems, and driving dynamics or anti-skid control systems are possible in a manner known per se. The abbreviations ABS, ASR and FDR or ESP are used for these slip rules. The brake pressure control takes place with the external force brake pressure generator 8 and / or the intake valves 16 and exhaust valves 17
Die Ventile 13, 14, 16, 17 sind 2/2-Wege-Magnetventile, was allerdings nicht zwingend für die Erfindung ist. The valves 13, 14, 16, 17 are 2/2-way solenoid valves, but this is not essential for the invention.
Möglich ist beispielsweise eine lineare, eine degressive oder eine progressive Abhängigkeit zwischen dem Radbremsdruck in der/n Radbremse/n 2 und dem Pedalweg und/oder der Pedalkraft des Hauptbremszylinders 1 und/oder dem Hauptbremszylinderdruck. Die Abhängigkeit wird hier als Pedalcharakteristik be- zeichnet und ist in der beschriebenen Ausführungsform progressiv wie in Kurve 18 in Figur 2 dargestellt, die an der Abszisse den Pedalweg s und an der Ordina- te den Radbremsdruck p zeigt. Grundsätzlich sind unterschiedliche Radbrems- drücke in den Radbremsen 2 möglich, sofern die Fahrzeugbremsanlage mehrere Radbremsen 2 mit Ein- und Auslassventilen 16, 17 aufweist. In der beschriebe- nen Ausführungsform ist die Pedalcharakteristik progressiv, das heißt der Rad- bremsdruck steigt mit zunehmendem Pedalweg und zunehmender Pedalkraft überproportional an. Eine lineare, degressive, progressive und grundsätzlich be- liebige Abhängigkeit zwischen dem Radbremsdruck und dem Pedalweg, der Pe- dalkraft und/oder dem Hauptbremszylinderdruck ist mit dem Fremdkraft- Bremsdruckerzeuger 8 und/oder dem steuerbaren Bremskraftverstärker 4 mög- lich. For example, a linear, a degressive or a progressive dependency between the wheel brake pressure in the / n wheel brake / n 2 and the pedal travel and / or the pedal force of the master brake cylinder 1 and / or the master brake cylinder pressure is possible. The dependency is referred to here as the pedal characteristic and in the described embodiment is progressive as shown in curve 18 in FIG. 2, which shows the pedal travel s on the abscissa and the wheel brake pressure p on the ordinate. In principle, different wheel brake pressures are possible in the wheel brakes 2, provided the vehicle brake system has a plurality of wheel brakes 2 with inlet and outlet valves 16, 17. In the described embodiment, the pedal characteristic is progressive, that is, the wheel brake pressure increases disproportionately with increasing pedal travel and pedal force. A linear, degressive, progressive and basically any dependency between the wheel brake pressure and the pedal travel, the pedal force and / or the master cylinder pressure is possible with the external brake pressure generator 8 and / or the controllable brake booster 4.
Im Falle eines Fehlers oder einer Funktionsbeschränkung der Fahrzeugbremsan- lage wird erfindungsgemäß die Abhängigkeit zwischen dem Radbremsdruck ei- nerseits und dem Pedalweg, der Pedalkraft und/oder dem Hauptbremszylinder- druck andererseits geändert, insbesondere reduziert, so dass ein Fahrzeugführer das Gefühl hat, die Fahrzeugbremsanlage bremse schlechter. Dadurch wird der Fahrzeugführer haptisch auf den Fehler oder die Funktionsbeschränkung der Fahrzeugbremsanlage aufmerksam gemacht. In the event of a fault or a functional restriction of the vehicle brake system, the dependency between the wheel brake pressure is on the one hand and the pedal travel, the pedal force and / or the master brake cylinder pressure on the other hand changed, in particular reduced, so that a vehicle driver has the feeling that the vehicle brake system is braking less well. As a result, the vehicle driver is made aware of the fault or the functional limitation of the vehicle brake system.
Ein möglicher Fehler ist Luft in der Fahrzeugbremsanlage, wodurch die Brems- flüssigkeit kompressibel wird. Bei einer Fremdkraftbetätigung der Fahrzeug- bremsanlage mit dem Fremdkraft-Bremsdruckerzeuger 8 würde der Fehler ohne das erfindungsgemäße Verfahren nicht bemerkt, weil der Hauptbremszylinder 1 durch Schließen des Trennventils 14 hydraulisch von der Fahrzeugbremsanlage getrennt und mit dem Fremdkraft-Bremsdruckerzeuger 8 trotz Kompressibilität der Bremsflüssigkeit der vom Sollwert abhängige Bremsdruck bzw. Radbrems- druck erzeugt wird. Es handelt sich um einen sogenannten„versteckten Fehler“, der für den Fahrzeugführer nicht wahrnehmbar ist bzw. nur wahrgenommen wird, wenn die Fahrzeugbremsanlage bei einer Störung oder einem Ausfall des Fremdkraft-Bremsdruckerzeugers 8 mit dem Hauptbremszylinder 1 betätigt wird. A possible fault is air in the vehicle brake system, which makes the brake fluid compressible. If the vehicle brake system was actuated by external power with the external brake pressure generator 8, the fault would not be noticed without the inventive method, because the master brake cylinder 1 is hydraulically separated from the vehicle brake system by closing the isolating valve 14 and with the external brake pressure generator 8 despite the compressibility of the brake fluid by the Setpoint-dependent brake pressure or wheel brake pressure is generated. It is a so-called “hidden fault”, which is not perceptible to the vehicle driver or is only perceived if the vehicle brake system is actuated with the master brake cylinder 1 in the event of a malfunction or failure of the power brake pressure generator 8.
Andere versteckte Fehler sind beispielsweise ein nicht öffnendes Trennventil 14 ein nicht schließendes Fremdkraftventil 13 oder ein nicht schaltendes Einlass- ventil 16 oder Auslassventil 17. Solche Fehler oder Funktionsbeschränkungen lassen sich mit Prüfverfahren aufspüren, die vom elektronischen Steuergerät 5 von selbst durchgeführt werden und bei denen ein Druck mit dem Fremdkraft- Bremsdruckerzeuger 8 erzeugt, die Ventile 13, 14, 16, 17 verschieden geschaltet und Drücke mit den Drucksensoren 7, 15 und Bewegungen des Fremdkraft- Bremsdruckerzeugers 8 gemessen werden. Weichen die Werte von den Werten bei voll funktionsfähiger Fahrzeugbremsanlage ab, lässt das auf eine Funktions- beschränkung oder einen Fehler schließen. Werden keine Abweichungen ge- messen, wird die Fahrzeugbremsanlage als voll funktionsfähig angesehen und weist die dafür vorgesehene Pedalcharakteristik, in der beschriebenen Ausfüh- rungsform die progressive, mit der Kurve 18 im Diagramm der Figur 2 dargestell- te Pedalcharakteristik auf. Other hidden faults are, for example, a non-opening isolating valve 14, a non-closing power valve 13 or a non-switching inlet valve 16 or outlet valve 17. Such faults or functional restrictions can be detected using test methods that are carried out automatically by the electronic control unit 5 and in which one Pressure generated by the external brake pressure generator 8, the valves 13, 14, 16, 17 switched differently and pressures with the pressure sensors 7, 15 and movements of the external brake pressure generator 8 are measured. If the values deviate from the values with a fully functional vehicle brake system, this indicates a functional restriction or an error. If no deviations are measured, the vehicle brake system is considered to be fully functional and has the pedal characteristic provided for it, in the embodiment described the progressive pedal characteristic represented by curve 18 in the diagram in FIG. 2.
Als verstecke Fehler, die sich bei einer Muskel- oder Hilfskraftbetätigung, nicht jedoch bei einer Fremdkraftbetätigung der Fahrzeugbremsanlage bemerkbar machen, kommen auch vergrößertes Lüftspiel, Schrägverschleiß von Bremsbe- lägen, Scheibenschlag (unebene Bremsscheibe/n), Fading, kleine Leckagen mit geringem Bremsflüssigkeitsverlust insbesondere nur durch Druckaufbau beim Bremsen in Betracht. Hidden faults that are noticeable when a muscle or auxiliary power is actuated, but not when the vehicle brake system is actuated by external power, are also increased air play, oblique wear of brake , disc runout (uneven brake disc (s)), fading, small leaks with little loss of brake fluid, especially only due to pressure build-up when braking.
Im Falle eines Fehlers oder einer Funktionsbeschränkung wird wie geschrieben die Pedalcharakteristik geändert, in der beschriebenen Ausführungsform der Er- findung wird das Verhältnis zwischen dem Radbremsdruck und dem Betäti- gungsweg und/oder der Betätigungskraft des Hauptbremszylinders 1 und/oder dem Hauptbremszylinderdruck reduziert. Eine Variante des erfindungsgemäßen Verfahrens sieht vor, dass zugleich die Progression der Pedalcharakteristik wie in Kurve 19 in Figur 2 gezeigt vergrößert wird. Das heißt, dass bei einer Betäti gung des Hauptbremszylinders 1 der Radbremsdruck zunächst weniger und spä- ter stärker steigt als bei voll funktionsfähiger Fahrzeugbremsanlage. Die Kurven 18, 19 schneiden einander in einem Punkt 20, an dem der Radbremsdruck, die Betätigungskraft, der Betätigungsweg und der Hauptbremszylinderdruck bei ei- nem Fehler oder einer Funktionsbeschränkung der Fahrzeugbremsanlage gleich wie bei voll funktionsfähiger Fahrzeugbremsanlage sind. Bei weiterer Druckerhö- hung kann die Kurve 19 der Pedalcharakteristik bei beeinträchtigter oder fehler- hafter Fahrzeugbremsanlage weiterhin stärker, gleich oder weniger stark steigen wie bei voll funktionsfähiger Fahrzeugbremsanlage. Der Punkt 20 kann bei- spielsweise wie gesetzlich vorgeschrieben festgelegt werden für beispielsweise eine Fahrzeugverzögerung von 6,43 m/s2 bei einer Pedalkraft von 500 N. Am Punkt 20 ist auch eine höhere Vollverzögerung als die gesetzlich vorgeschriebe- ne Verzögerung möglich. Die Vollverzögerung ist eine für die jeweilige Fahr- zeugbremsanlage und ein mit ihr ausgerüstetes Fahrzeug festgelegte Fahrzeug- verzögerung bei der Pedalkraft von 500 N. Sie ist wie geschrieben höher als die gesetzlich vorgeschriebene Fahrzeugverzögerung und entspricht typischerweise der Erdbeschleunigung von 9,81 m/s2. In the event of an error or a functional restriction, the pedal characteristic is changed as written, in the described embodiment of the invention the ratio between the wheel brake pressure and the actuation path and / or the actuation force of the master cylinder 1 and / or the master cylinder pressure is reduced. A variant of the method according to the invention provides that at the same time the progression of the pedal characteristic is increased as shown in curve 19 in FIG. 2. This means that when the master brake cylinder 1 is actuated, the wheel brake pressure initially increases less and later than in the case of a fully functional vehicle brake system. The curves 18, 19 intersect at a point 20 at which the wheel brake pressure, the actuation force, the actuation travel and the master cylinder pressure are the same in the event of a fault or a functional restriction of the vehicle brake system as in the case of a fully functional vehicle brake system. If the pressure increases further, the curve 19 of the pedal characteristic can continue to rise more, the same or less strongly than in the case of a fully functional vehicle brake system when the vehicle brake system is impaired or defective. For example, point 20 can be specified as required by law, for example for a vehicle deceleration of 6.43 m / s 2 with a pedal force of 500 N. At point 20, a higher full deceleration than the legally prescribed deceleration is also possible. The full deceleration is a vehicle deceleration for the respective vehicle brake system and a vehicle equipped with it with the pedal force of 500 N. As written, it is higher than the legally prescribed vehicle deceleration and typically corresponds to the acceleration due to gravity of 9.81 m / s 2 ,
Eine Variante des erfindungsgemäßen Verfahrens sieht eine beispielsweise opti sche, akustische und/oder haptische Warnung des Fahrzeugführers im Falle ei- nes Fehlers oder einer Funktionseinschränkung der Fahrzeugbremsanlage vor, wobei die optische Warnung 21 in Figur 1 mit dem Symbol einer Lichtquelle 21 dargestellt ist. Im Falle beispielsweise einer optischen und/oder sonstigen Warnung 21 kann die Pedalcharakteristik wie mit der Kurve 22 in Figur 2 dargestellt so geändert wer- den, dass in Punkt 23 bei der Pedalkraft von beispielsweise 500 N eine niedrige- re Verzögerung, beispielsweise eine gesetzlich bei einer optischen und/oder sonstigen Warnung vorgeschriebene Verzögerung von 2,44 m/s2 bei der Pedal- kraft von 500 N erreicht wird. A variant of the method according to the invention provides, for example, an optical, acoustic and / or haptic warning of the vehicle driver in the event of an error or a functional restriction of the vehicle brake system, the optical warning 21 being shown in FIG. 1 with the symbol of a light source 21. In the case of, for example, an optical and / or other warning 21, the pedal characteristic can be changed as shown by curve 22 in FIG. 2 in such a way that in point 23 a lower deceleration, for example a statutory deceleration, occurs for example with the pedal force of 500 N. an optical and / or other warning prescribed deceleration of 2.44 m / s 2 with the pedal force of 500 N is reached.
Als haptische Warnung eines oder einer Funktionsbeschränkung der Fahrzeug- bremsanlage ist außer der geänderten Pedalcharakteristik beispielsweise eine Leistungsreduktion eines Antriebsmotors und/oder eine Geschwindigkeitsbe- grenzung eines Kraftwagens möglich. Ebenso ist die Abschaltung von Komfort- funktionen und/oder automatisierten Fahrfunktionen wie Tempomat und/oder Ab- standsregeltempomat (vorzugsweise geschwindigkeitsabhängige Abstandsrege- lung zu einem vorausfahrenden Fahrzeug, Abkürzung: ACC, englisch: Adaptive Cruise Control). Alle diese Warnungen machen einen Fahrzeugführer darauf aufmerksam, dass etwas nicht stimmt. As a haptic warning of one or a functional restriction of the vehicle brake system, in addition to the changed pedal characteristics, it is possible, for example, to reduce the power of a drive motor and / or to limit the speed of a motor vehicle. Likewise, the deactivation of comfort functions and / or automated driving functions such as cruise control and / or adaptive cruise control (preferably speed-dependent distance control to a vehicle in front, abbreviation: ACC, English: Adaptive Cruise Control). All of these warnings alert a driver that something is wrong.

Claims

Ansprüche Expectations
1. Verfahren zum Betrieb einer hydraulischen Hilfskraft- und/oder Fremdkraft- Fahrzeugbremsanlage mit einem muskelkraftbetätigbaren Hauptbremszylin- der (1 ), einem steuerbaren Bremskraftverstärker (4) und/oder einem Fremd- kraft-Bremsdruckerzeuger (8) und mit mindestens einer hydraulischen Rad- bremse (2), dadurch gekennzeichnet, dass im Falle eines Fehlers oder ei- ner Funktionseinschränkung der Fahrzeugbremsanlage ein Verhältnis zwi- schen einem Radbremsdruck in der mindestens einen Radbremse (2) und einer Betätigungskraft des Hauptbremszylinders (1 ) und/oder einem Betäti gungsweg des Hauptbremszylinders (1 ) und/oder einem Hauptbremszylin- derdruck im Hauptbremszylinder (1 ) geändert, insbesondere der Radbrems- druck in der mindestens einen Radbremse (2) im Verhältnis zur Betätigungs- kraft des Hauptbremszylinders (1 ) und/oder dem Betätigungsweg des Hauptbremszylinders (1 ) und/oder dem Hauptbremszylinderdruck im Haupt- bremszylinder (1 ) reduziert wird. 1. Method for operating a hydraulic auxiliary and / or external vehicle brake system with a main brake cylinder (1) that can be operated by muscle power, a controllable brake booster (4) and / or an external brake pressure generator (8) and with at least one hydraulic wheel brake generator. Brake (2), characterized in that in the event of a fault or a functional restriction of the vehicle brake system, a relationship between a wheel brake pressure in the at least one wheel brake (2) and an actuating force of the master brake cylinder (1) and / or an actuation path of the Brake master cylinder (1) and / or a master brake cylinder pressure in the master brake cylinder (1) changed, in particular the wheel brake pressure in the at least one wheel brake (2) in relation to the actuating force of the master brake cylinder (1) and / or the actuation path of the master brake cylinder ( 1) and / or the master cylinder pressure in the master cylinder (1) is reduced.
2. Verfahren nach Anspruch 1 , dadurch gekennzeichnet, dass die Fahrzeug- bremsanlage das Verhältnis zwischen dem Radbremsdruck in der mindes- tens einen Radbremse (2) und der Betätigungskraft des Hauptbremszylin- ders (1 ) und/oder dem Betätigungsweg des Hauptbremszylinders (1 ) und/oder dem Hauptbremszylinderdruck im Hauptbremszylinder (1 ) bei ei- nem versteckten Fehler ändert. 2. The method according to claim 1, characterized in that the vehicle brake system, the ratio between the wheel brake pressure in the at least one wheel brake (2) and the actuating force of the master brake cylinder (1) and / or the actuation path of the master brake cylinder (1) and / or the master cylinder pressure in the master cylinder (1) changes in the event of a hidden fault.
3. Verfahren nach Anspruch 1 oder 2, dadurch gekennzeichnet, dass die Fahrzeugbremsanlage bei einem Fehler oder einer Funktionseinschränkung eine progressive Pedalcharakteristik oder eine stärkere Progression der Pe- dalcharakteristik als bei voll funktionsfähiger Fahrzeugbremsanlage aufweist. 3. The method according to claim 1 or 2, characterized in that the vehicle brake system has a progressive pedal characteristic or a stronger progression of the pedal characteristic in the event of a fault or a functional restriction than in the case of a fully functional vehicle brake system.
4. Verfahren nach Anspruch 3, dadurch gekennzeichnet, dass die Fahrzeug- bremsanlage bei einer festgelegten Betätigungskraft des Hauptbremszylin- ders (1 ) und/oder einem festgelegten Betätigungsweg des Hauptbremszylin- ders (1 ) und/oder einem festgelegten Hauptbremszylinderdruck im Haupt- - io - bremszylinder (1 ) bei einem Fehler oder einer Funktionseinschränkung der Fahrzeugbremsanlage denselben Radbremsdruck aufweist wie bei voll funk- tionsfähiger Fahrzeugbremsanlage. 4. The method according to claim 3, characterized in that the vehicle brake system with a fixed actuating force of the master brake cylinder (1) and / or a fixed actuation path of the master brake cylinder (1) and / or a fixed master cylinder pressure in the master - io - brake cylinder (1) has the same wheel brake pressure in the event of a fault or a functional restriction of the vehicle brake system as in the case of a fully functional vehicle brake system.
5. Verfahren nach einem oder mehreren der vorhergehenden Ansprüche, dadurch gekennzeichnet, dass die Fahrzeugbremsanlage im Falle eines Fehlers oder einer Funktionseinschränkung eine Warnung ausgibt. 5. The method according to one or more of the preceding claims, characterized in that the vehicle brake system issues a warning in the event of an error or a functional restriction.
6. Verfahren nach Anspruch 5, dadurch gekennzeichnet, dass als Warnung eines Fahrzeugführerers im Falle eines Fehlers oder einer Funktionsein- schränkung der Fahrzeugbremsanlage eine Motorleistung eines mit der Fahrzeugbremsanlage ausgestatteten Kraftfahrzeugs reduziert oder be- grenzt und/oder eine Höchstgeschwindigkeit des Kraftfahrzeugs begrenzt wird und/oder automatische Fahrfunktionen des Kraftfahrzeugs abgeschaltet werden. 6. The method according to claim 5, characterized in that as a warning to a vehicle driver in the event of a fault or a functional restriction of the vehicle brake system, an engine output of a motor vehicle equipped with the vehicle brake system is reduced or limited and / or a maximum speed of the motor vehicle is limited and / or automatic driving functions of the motor vehicle are switched off.
PCT/EP2019/063554 2018-08-01 2019-05-25 Method for operating a hydraulic power-assisted brake system and/or hydraulic power brake system of a vehicle WO2020025187A1 (en)

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