DE102010003081A1 - Brake assembly for motor vehicle, has electronic controlling-and regulating unit and pressure sources that are connected with intermediate chamber and/or pressure supplying unit by electrically controlled valve arrangement - Google Patents

Abstract

The assembly has a regulating unit electrically regulating pressure in an intermediate chamber (21). A pressure medium is retained in a pressure supplying unit (2) under atmospheric pressure, and the pressure from the pressure medium is controlled for electrically regulating the pressure in the intermediate chamber. An electronic controlling-and regulating unit (10) and pressure sources (3) that are connected with the intermediate chamber and/or pressure supplying unit by an electrically controlled valve arrangement (38). An independent claim is also included for a method for operating a brake assembly.

Description

• • einem Hauptbremszylinder, der mindestens einen Hauptzylinderkolben aufweist und an den Radbremskreise angeschlossen sind,
• • einem ersten Kolben, der über eine Betätigungskräfte übertragende Druckstange mit einem Bremspedal gekoppelt ist,
• • einem zweiten Kolben, der vom ersten Kolben betätigbar ist und der in eine kraftübertragende Verbindung mit dem Hauptzylinderkolben bringbar ist,
• • einer Simulationseinrichtung mit mindestens einem elastischen Element, die in der Betriebsart „Brake-by-wire” dem Fahrzeugführer ein angenehmes Pedalgefühl vermittelt,
• • einem mit hydraulischem Druck beaufschlagbaren Zwischenraum zwischen dem zweiten Kolben und dem Hauptzylinderkolben, wobei eine Druckbeaufschlagung des Zwischenraumes den zweiten und den Hauptzylinderkolben in entgegen gesetzten Richtungen belastet,
• • mit einer Druckbereitstellungseinrichtung, die den Druck im Zwischenraum steuert,
• • mit einem unter Atmosphärendruck stehenden Druckmittelvorratsbehälter, der mit dem Zwischenraum hydraulisch verbindbar ist, sowie
• • mit Mitteln zur elektrischen Regelung des Druckes im Zwischenraum, wobei
• • das zur elektrischen Regelung des im Zwischenraum eingesteuerten Druckes benötigte Druckmittel in der Druckbereitstellungseinrichtung unter Atmosphärendruck bereit gehalten und bei Bedarf unter einen höheren Druck gesetzt wird, sowie
• • einer elektronischen Steuer- und Regeleinheit.

The present invention relates to a brake system for motor vehicles, which can be controlled in a "brake-by-wire" mode both by the driver and independently of the driver, is preferably operated in the "brake-by-wire" mode and in a fallback mode without brake booster can be operated in the only operation by the driver is possible, with

• A master cylinder having at least one master cylinder piston and connected to the wheel brake circuits,
• A first piston, which is coupled to a brake pedal via an actuating force transmitting push rod,
• A second piston, which is actuatable by the first piston and which can be brought into a force-transmitting connection with the master cylinder piston,
• A simulation device with at least one elastic element, which gives the driver a pleasant pedal feel in the "brake-by-wire" operating mode,
• A hydraulic pressure-loadable gap between the second piston and the master cylinder piston, pressurizing the clearance loading the second and master cylinder pistons in opposite directions,
• With a pressure supply device that controls the pressure in the intermediate space,
• • with a pressurized medium storage container under atmospheric pressure, which is hydraulically connectable with the intermediate space, as well as
• • with means for electrical control of the pressure in the intermediate space, wherein
• • The pressure required for the electrical control of the pressure introduced in the intermediate space pressure in the pressure supply device is kept ready under atmospheric pressure and set if necessary under a higher pressure, and
• • an electronic control unit.

A brake system of the type mentioned is from the international patent application of the applicant WO 2008/025797 A1 known. A hydraulic pressure for actuating the master cylinder is provided in the prior art brake system by an electro-hydraulic actuator forming the pressure supply device, which is driven by an electric motor. A disadvantage is felt in such brake systems, the fact that to overcome the rotational inertia of electric motor drives in high-dynamic operation electrical services are needed with reasonable means neither provided (electrical system load), still controlled (electronic effort), still implemented (special motors required) can be ,

It is therefore an object of the present invention to provide a brake system of the type mentioned, in which at a reasonable cost highly dynamic braking operations can be performed by an as needed increase the pressure build-up dynamics is brought about in the space.

This object is achieved with a brake system in which a second pressure source is provided which can be connected via an electrically controllable valve arrangement with the intermediate space or the pressure supply device.

With the brake system according to the invention, all the brakes can be handled without any special requirements on the dynamics with the electro-hydraulic actuator, while additional means according to the invention are used for braking with higher pressure build-up dynamics. Therefore, a smaller sized high-pressure accumulator is sufficient.

Further advantageous embodiments of the brake system according to the invention are listed in the subclaims.

The present invention will be explained in more detail below with reference to two exemplary embodiments with reference to the attached schematic drawings, in which: 1 and 2 each show an embodiment of the brake system according to the invention.

The brake system according to the invention shown in the drawing consists essentially of an actuator 1 , a pressure supply device 2 , a high-pressure accumulator 3 , wherein the actuator unit 1 , the pressure delivery device 2 and the high-pressure accumulator 3 form a brake booster, as well as a brake booster operatively downstream master cylinder or tandem master cylinder 4 , whose pressure chambers with the under atmospheric pressure chambers of a pressure medium reservoir 11 are connectable. On the other hand, wheel brake circuits are connected to the pressure chambers I . II connected, with the interposition of a hydraulic unit or a controllable Radbremsdruckmodulationsmodul 9 the wheel brakes 5 - 8th supply a motor vehicle with hydraulic pressure medium. The wheel brake pressure modulation module 9 can be formed by a known ABS wheel brake pressure modulation module with eight or a twelve-valve ESP wheel brake pressure modulation module. The from the master cylinder 4 provided, the wheel brake pressure modulation module 9 acting pressure is from a pressure sensor 49 detected. Of course, as an alternative to the illustrated Radbremsdruckmodulationsmodul 9 the wheel brakes 5 - 8th upstream, unspecified pressure modulation valves may be provided which allow a Radbremsdruckmodulation according to the so-called. Multiplex principle, which is known in the art. In addition, the brake system shown has an only schematically indicated electronic control unit 10 on. The actuating device 1 in a housing 20 is arranged, on or in the tandem master cylinder 4 connected or integrated, is via a brake pedal 12 controllable, that via an actuating rod 13 with a first piston 14 the actuator 1 is operatively connected. The actuating travel of the brake pedal 12 is by means of a displacement sensor 28 captures the path of the first piston 14 sensed. However, for the same purpose, a rotation angle sensor can be used which determines the angle of rotation of the brake pedal 12 detected. The first piston 14 limited with a second piston 15 a pressure chamber 16 that is a compression spring 17 the brake pedal is de-energized 12 the first piston 14 for attachment to a housing 20 trained stop 22 brings. Alternatively or additionally, in the area of the push rod 13 or the brake pedal 12 a pedal return spring may be provided. The pressure chamber 16 is in the unactuated state of the actuator 1 via a connection indicated only schematically 50 with the pressure medium reservoir 11 connected. The second piston 15 acts with a primary piston 18 of the tandem master cylinder 4 together, whereby between the second ( 15 ) and the primary piston 18 an unillustrated pressure booster piston can be arranged. Between the second piston 15 and the master cylinder piston 18 is a gap 21 limited, by the application of a hydraulic pressure of the second piston 15 acted upon against the direction of actuation and so on a housing-fixed stop 19 is held while the master cylinder piston 18 in the sense of a pressure build-up in the tandem master cylinder 4 is acted upon in the direction of actuation. A resulting from this load movement of the master cylinder piston 18 is by means of a second displacement sensor 29 detected. In addition, the second piston limits 15 in the case 20 a hydraulic room 23 , by means of a parallel connection of an electromagnetically operable 2/2-way switching valve 44 as well as one to the room 23 opening check valve 51 with the pressure medium reservoir under atmospheric pressure 11 is connectable. The function of the room 23 will be explained in more detail in the following text.

Furthermore, it can be seen from the drawing that the previously mentioned pressure chamber 16 via a lockable connection line 24 with a simulator chamber 25 communicating from a simulator piston 26 is limited. The simulator piston acts 26 with a simulator pen 27 together. The simulator chamber 25 , the simulator piston 26 , as well as the simulator pen 27 Form a pedal travel simulator, which gives the driver the usual pedal feel when operating the brake system, which corresponds to a common brake pedal characteristic. This means that with low brake pedal travel, the resistance increases slowly and increases disproportionately with a larger brake pedal travel. To dampen the movement of the simulator piston 26 can not be provided, for example, hydraulic or pneumatic damping means may be provided. The hydraulic connection line 24 between the pressure chamber 16 and the simulator chamber 25 is by means of an electromagnetically actuated, preferably analog controllable shut-off valve 30 locked, whereby the pedal travel simulator is effectively switched off. When switching the shut-off valve 30 in its second switching position, preferably by the high-pressure accumulator 3 provided pressure is applied, the connecting line 24 Approved. Parallel connected to the shut-off valve 30 is a simulator chamber 25 closing check valve 31 , Detecting the in the pressure chamber 16 applied pressure is a second pressure sensor, the reference numeral 32 is provided and in the aforementioned electronic control unit 10 can be integrated.

The aforementioned electrohydraulic pressure supply device 2 consists essentially of a hydraulic cylinder-piston arrangement 34 as well as an electromechanical drive unit 35 , which is formed for example by an electric motor with a downstream mechanical transmission, the rotational movement of the electric motor in a translational movement of a hydraulic piston 36 so that in a pressure room 37 the hydraulic cylinder-piston arrangement 34 a hydraulic pressure is built up. The electromechanical drive unit 35 is powered by an electrical energy storage, not shown, with energy. The movement of the piston 36 is detected by means of a displacement sensor indicated by the reference numeral 33 is provided. The pressure room 37 is via an electromagnetically controllable, preferably analog controllable 2/2-way valve 38 over a line section 40 with the high-pressure accumulator 3 connected so that the high-pressure accumulator 3 by means of the electromechanical drive unit 35 is loadable. The detection of the high-pressure accumulator 3 prevailing hydraulic pressure is a pressure sensor with the reference numeral 39 is provided. The mentioned hydraulic line section 40 is also by means of a normally open (SO-) 2/2-way valve 41 With one of the two under atmospheric pressure chamber of the pressure medium reservoir 11 connectable, so that in a resting state of the brake system by a temperature expansion of the pressure medium in the pressure chamber 37 no unintentional pressure build-up occurs. In addition, another line section connects 42 the pressure room 37 with the aforementioned gap 21 , A third pressure sensor 43 serves to capture the from the pressure supply device 2 delivered or in the interspace 21 prevailing pressure.

The previously mentioned electronic control unit 10 serves on the one hand the acquisition of sensor data, the processing of these data, u. U. the exchange of data with other control units, and on the other hand, the control not shown, in the Radbremsdruckmodulationsmodul 9 contained, electromagnetically actuated pressure modulation valves, the previously described 2/2-way valves 38 . 41 . 53 . 63 , the electro-mechanical actuator 35 the pressure supply device 2 and the brake lights of the vehicle.

In the following text, the operation of the brake system according to the invention will be explained in more detail.

A first operating mode corresponds to a purely electrical, the so-called. "Brake-by-wire" mode in which all components of the brake system are intact and working properly. In this mode is used to build up a hydraulic pressure in the space 21 with simultaneous shut-off of the hydraulic line 40 the electrohydraulic actuator 34 - 37 controlled, so that of the pressure-providing device 2 provided or in their cylinder-piston arrangement 34 generated pressure in the gap 21 is supplied. By the pressure effect of the second piston 15 at the stop 19 held and the master cylinder piston 18 shifted to the left, creating a pressure build-up in the master cylinder 4 takes place. The hydraulic pressure is thereby in the electronic control unit 10 contained means via a control of the electric motor 35 supplied stream regulated. For the purpose of keeping pressure, the piston 36 the piston-cylinder arrangement 34 held firmly in the activated position. That in the connection between the pressure chamber 37 and the pressure fluid reservoir 11 inserted, normally open 2/2-way valve 41 is switched to its closed switching position both during pressure build-up and when holding pressure. In contrast, when braking, which make high demands on the dynamics, the analog controllable 2/2-way valve 38 regulated open, leaving the gap 21 in addition to the high-pressure accumulator 3 provided hydraulic pressure is applied.

For a pressure reduction, the piston 36 the cylinder-piston arrangement 34 driven back. In this case, pressure medium flows from the intermediate space 21 back to the pressure room 37 , For complete reduction of the pressure to atmospheric pressure level is finally the aforementioned 2/2-way valve 41 opened, creating a hydraulic connection to the pressure medium reservoir 11 will be produced. To a vacuum in the space 21 or in the pressure room 36 to avoid is the 2/2-way valve 41 preferably designed so that it in the energized state, a pressure medium flow from the pressure fluid reservoir 11 in the pressure chambers 21 . 37 allowed.

The process of controlling the electro-hydraulic actuator 34 . 35 is from the electronic control unit 10 performed so that the pressure in the space 21 a target pressure value is approximated. This desired pressure value results on the one hand from a detected actuation component of the brake pedal 12 and, on the other hand, a foreign operation component. The operating component of the brake pedal 12 is from the actuation of the brake pedal 12 or the first piston 14 and from the hydraulic pressure in the pressure chamber 16 determined by means of the pressure sensor 32 is detected and the operating force of the brake pedal 12 is proportional.

In a second mode of operation caused by a fault in the electronics or by the absence of any of the hydraulic pressure supply means 2 generated pressure is equivalent and corresponds to a fallback level, is not an electronically controlled pressure build-up in the intermediate space 21 possible. Since the 2/2-way valve 41 as well as the 2/2-way valve 44 remain open in the de-energized state, on the one hand both the gap 21 , as well as the pressure room 37 the cylinder-piston arrangement 34 and the high-pressure accumulator 3 and on the other hand, the hydraulic (barrier) space 23 with the pressure medium reservoir 11 or connected to the atmospheric pressure. In this operating mode, the brake system can be actuated purely mechanically. The over the brake pedal 12 in the pressure chamber 16 built-up pressure shifts the second piston 15 from his stop 19 away and thus the master cylinder piston 18 by mechanical contact. The operation of the master cylinder 4 is done exclusively with the muscle power of the driver.

A significant increase in the reliability of the brake system constructed according to the invention is achieved by a method in the implementation of commissioning of the vehicle equipped with the brake system after switching on the ignition, the brake pedal is first operated by the driver to check the operation of the brake system.

To concretize the idea of the invention, it is provided in a further method step that signals of the movement of the first piston 14 detecting displacement sensor 28 , the movement of the master cylinder piston 18 detecting displacement sensor 29 , the one in the pressure chamber 16 controlled pressure sensing pressure sensor 32 and one in the master cylinder 4 controlled pressure sensing pressure sensor 49 be evaluated in the sense of detecting a malfunction, such as a leak.

It makes sense to initialize the "brake-by-wire" mode after completion of the check with a positive result.

The addressed initialization is carried out according to a further advantageous feature of the invention by controlling the pressure supply device 2 in the sense of an increase in pressure in the intermediate space 21 or a movement of the second piston 15 contrary to the direction of actuation, which from the pressure chamber 16 displaced pressure medium volume in the simulation device 25 - 27 is directed. The transfer of pressure medium is using the analog controllable 2/2-way valve 30 controlled so that a brake pedal irritation is avoided by the initialization.

The construction of in 2 shown second embodiment of the present invention largely corresponds to the first embodiment, in connection with 1 was explained in detail. The above described, to the individual brake circuits I . II connected pressure modulation module 9 ' contains however the wheel brakes 5 - 8th upstream, electromagnetically actuated, preferably normally open (SO) 2/2-way valves 45 . 46 . 47 . 48 that, by the electronic control unit 10 controlled, the implementation of a brake pressure control according to the so-called. Multiplex principle allow. However, this type of brake pressure control is known to a person skilled in the art and need not be explained in the present application.

The present invention achieves a simply constructed, highly efficient braking system in which in a "brake-by-wire" mode, the brake pedal characteristic does not depend on the operating state of the rest of the brake system, whereby the pedal feel in a driver's braking neither by the simultaneous presence of a Third-party braking can be disturbed by other control activities of the braking system such as anti-lock braking, traction control or driving stability control.

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• WO 2008/025797 A1 [0002]

Claims (15)

Brake system for motor vehicles, which can be controlled in a "brake-by-wire" mode both by the driver and independently of the driver, is preferably operated in the "brake-by-wire" mode and can be operated in a fallback mode without brake boost, in only operation by the vehicle driver is possible, with a master cylinder ( 4 ), the at least one master cylinder piston ( 18 ) and at the wheel brake circuits ( I . II ), a first piston ( 14 ), which via an actuating forces transmitting push rod ( 13 ) with a brake pedal ( 12 ), a second piston ( 15 ) from the first piston ( 14 ) is operable and in a force-transmitting connection with the master cylinder piston ( 18 ) can be brought, • a simulation device with at least one elastic element ( 27 ), which gives the driver a pleasant pedal feel in the "brake-by-wire" mode of operation, • a space which can be subjected to hydraulic pressure ( 21 ) between the second piston ( 15 ) and the master cylinder piston ( 18 ), wherein a pressurization of the intermediate space ( 21 ) the second ( 15 ) and the master cylinder piston ( 18 ) in opposite directions, • with a pressure delivery device ( 2 ), the pressure in the space ( 21 ), with a pressurized medium storage tank (under atmospheric pressure) ( 11 ), with the space ( 21 ) is hydraulically connectable, and • with means for electrical control of the pressure in the intermediate space ( 21 ), wherein • the electrical regulation of the in the space ( 21 ) controlled pressure required pressure medium in the pressure supply device ( 2 ) is kept at atmospheric pressure and pressurized if necessary, and an electronic control unit ( 10 ), characterized in that a second pressure source ( 3 ) is provided, which via an electrically controllable valve arrangement ( 38 ) with the space ( 21 ) or the pressure supply device ( 2 ) is connectable. Brake system according to claim 1, characterized in that the means for producing the compound as an electromagnetically operable 2/2-way valve, in particular an analog controllable 2/2-way valve ( 38 ) are formed, so that when needed an increased pressure build-up dynamics in the space ( 21 ) the required pressure medium as the sum of the volume flow of the pressure supply device ( 2 ) and of the analog controllable 2/2-way valve ( 38 ) controlled volume flow of the second pressure source ( 3 ) is made available. Brake system according to claim 1 or 2, characterized in that the second pressure source as a high-pressure accumulator ( 3 ), wherein a charging of the high-pressure accumulator ( 34 ) by the pressure delivery device ( 2 ) via the analog controllable 2/2-way valve ( 38 ), and that a pressure sensor ( 39 ) for monitoring the high-pressure accumulator ( 3 ) is provided ready held pressure. Brake system according to at least one of claims 1 to 3, characterized in that the pressure supply device ( 2 ) by an electrohydraulic actuator ( 34 - 37 ) is formed, wherein a pressure sensor ( 43 ) for monitoring the pressure supply device ( 2 ) generated pressure is provided. Brake system according to at least one of claims 1 to 4, characterized in that between the pressure supply device ( 2 ) and the pressure fluid reservoir ( 11 ) one by means of a shut-off valve ( 41 ) lockable hydraulic connection is provided. Brake system according to at least one of claims 1 to 5, characterized in that the second piston ( 15 ) a hydraulic space ( 23 ), the pressurization of which causes movement of the second piston ( 15 ) inhibits or prevents in the direction of actuation. Brake system according to at least one of claims 1 to 6, characterized in that the first piston ( 14 ) as well as the second piston ( 15 ) a pressure chamber ( 16 ) to which the simulation facility ( 25 . 26 . 27 ) connected. Brake system according to at least one of claims 1 to 7, characterized in that the second piston ( 15 ) is designed as a stepped piston and that of the pressure in the pressure chamber ( 16 ) acted upon cross-sectional area of the second piston ( 15 ) is greater than its pressure generating cross-sectional area. Brake system according to claim 7 or 8, characterized in that in the connection between the pressure chamber ( 16 ) and the simulation device ( 25 . 26 . 27 ) a parallel connection of an electromagnetically operable, analog controllable 2/2-way valve ( 30 ) and one to the simulation facility ( 25 - 27 ) closing check valve ( 31 ) is inserted. Brake system according to one of claims 7 to 9, characterized in that a pressure sensor ( 32 ) for detecting the in the pressure chamber ( 16 ) is provided. Brake system according to one of claims 1 to 10, characterized in that to the brake circuits ( I . II ) Raddruckmodulationseinrichtungen ( 9 . 9 ' ), which operate according to the return principle or the multiplex principle. Method for operating the brake system according to one or more of the preceding claims, characterized in that for starting up the motor vehicle equipped with the brake system after switching on the ignition, first the brake pedal ( 12 ) is operated by the driver to check the functionality of the brake system. A method according to claim 12, characterized in that signals of a movement of the first piston ( 14 ) detecting displacement sensor ( 28 ), the movement of the master cylinder piston ( 18 ) detecting displacement sensor ( 29 ), in the pressure chamber ( 16 ) controlled pressure sensing pressure sensor ( 32 ) and one in the master cylinder ( 4 ) controlled pressure sensing pressure sensor ( 49 ) in the sense of detecting a malfunction, such as leakage, are evaluated. A method according to claim 13, characterized in that after completion of the check with a positive result, the operating mode "brake-by-wire" is initialized. A method according to claim 14, characterized in that the initialization by a control of the pressure-providing device ( 2 ) in the sense of an increase in pressure in the intermediate space ( 21 ) or a movement of the second piston ( 15 ) takes place counter to the direction of actuation, wherein the from the pressure chamber ( 16 ) displaced pressure medium volume into the simulation device ( 25 - 27 ).

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