Brake system and method for controlling the brake system

Abstract

The present invention relates to a braking system and a method for controlling the braking system. The braking system (2) includes a first module having a first pressure supply unit (6) with an electric drive (8), an optional second pressure supply unit (14), and a first control device (9) for controlling the first pressure supply unit (6); a second module having a third pressure supply unit (90), in particular a motor-pump unit (91), shut-off valves (USV1, USV2, HSV1, HSV2) and brake pressure regulating valves (AV1-AV4, EV1-EV4), as well as a second control device (95) for controlling the brake pressure regulating valves (AV1-AV4, EV1-EV4); and a detection unit for detecting a first case of an error, in particular an at least partial failure of the third pressure supply unit (90). The brake system (2) is designed to perform (wheel-specific and / or selective) regulation of the pressure in the wheel brakes in the first case of an error by actuating at least one of the brake pressure regulating valves (AV1-AV4, EV1-EV4) of the second module and / or the shut-off valves (USV1, USV2, HSV1, HSV2) of the second module and the first pressure supply unit (6) in order to provide ABS functionality and / or yaw torque mediation.

Description

[Technical Field]

[0001] This invention relates to a brake system and a method for controlling the brake system. [Background technology]

[0002] Trends surrounding vehicles configured for autonomous driving present, from the perspective of braking systems, on the one hand, a high demand for fail-safe design, and on the other hand, redundant functions for, for example, brake pressure generation, power supply, and computer functions.

[0003] So-called one-box and two-box systems are generally preferred. These consist of an electric brake booster (BKV) (so-called e-booster) and an electronic stability control system (ESP / ESC).

[0004] Known solutions have relatively long installation lengths and / or high weight.

[0005] Described in German Patent Application Publication No. 10 2014 205 645A1 and International Publication No. 2011 / 098178 is a solution having a coaxial drive in which an electric motor via a gear mechanism and piston acts on a master cylinder piston (HZ piston) (hereinafter referred to as Modification A, follower booster, or e-booster). BKV control is performed by an electric element and reaction disk as a so-called follower booster, and the pedal travel is a function of the brake pressure and volume absorption of the brake system, which requires a long pedal travel in the event of fading or brake circuit failure.

[0006] International Publication No. 2009 / 065709 describes an e-booster (hereinafter referred to as Modification B, or follower booster, or e-booster) that also has follower booster functionality. Here, BKV control is performed via pedal stroke and / or pedal pressure, i.e., the pressure used to activate the pedal. Another pressure supply having an electric motor and plunger acts on the HZ piston via the booster piston.

[0007] International Publication No. 2012 / 019802 presents an assembly similar to International Publication No. 2011 / 098178 (hereinafter referred to as Modification C), having a coaxial drive in which an electric motor acts on an HZ piston via a gear mechanism and piston. An additional piston / cylinder unit acting on a travel simulator piston is used here. In this way, the pedal stroke is independent of, for example, fading and brake circuit failure. However, it is highly complex and has a long installation length.

[0008] German Patent Application Publication No. 10 2009 033 499 describes a brake booster (hereinafter also referred to as variant D) having an additional ESP unit and an external pressure supply unit activated by hydraulic activation of a booster piston. This assembly, having four or five pistons and six solenoid valves (MVs), is complex and undesirable in terms of installation length. A non-hydraulic stroke simulator (WS) is located in a piston / cylinder unit upstream of the master cylinder and cannot be damped or switched by the solenoid valves (MVs).

[0009] All of the above solutions have a redundant brake booster function, as the braking function in the event of a BKV motor failure is ensured by an ESP unit with a pump similar to the vacuum BKV support function in autonomous drive mode.

[0010] In the event of an ESP motor failure, the ABS may continue to function due to the possibility of pressure modulation by the brake booster motor, and as described in International Publication No. 2010 / 088920, the piston of the master brake cylinder moves in a reciprocating manner to increase and dissipate pressure. If the brake booster is used in combination with an ESP unit having a typical valve circuit of an ESP unit, the pressure can be increased and dissipated by inlet valves that open when deactivated (reference numerals 32a, 32, b, 34b, 34a in Figure 1 of German Patent Application Publication No. 10 2014 205 645A1) and switching valves (USV) (reference numerals 30a, 30b in Figure 1 of German Patent Application Publication No. 10 2014 205 645A1), as outlined in detail in Figure 1: that is, common pressure control for all four wheels can be implemented, but not to the extent that the optimal stopping distance is achieved.

[0011] All known one-box systems have a so-called travel simulator (especially brake-by-wire systems) to implement a progressive pedal travel characteristic.

[0012] A well-known system with an e-booster and ESP has the only redundancy within the pressure supply unit, namely a redundant pressure supply unit with redundant outputs to enhance braking by the ESP in the event of an e-booster failure. Higher safety requirements are not considered.

[0013] Packaging the individual components of the braking system so as to form a ready-to-install unit, and thus the arrangement and the installation volume of this unit are of great importance. In particular, in the case of a braking system used in a motor vehicle configured for semi-automatic or fully automatic driving, many deformation forms, such as a tandem master (brake) cylinder or a single master (brake) cylinder, need to be considered. Examples of known packaging deformation forms are the arrangement of a pressure supply unit perpendicular to the axis of the master (brake) cylinder (e.g., as described in European Patent No. 2 744 691) or the arrangement of a pressure supply unit parallel to the axis of the master (brake) cylinder (e.g., as described in German Patent Application Publication No. 10 2016 105 232). The latter is distinguished in particular by a smaller installation width compared to the first-mentioned packaging deformation form.

Summary of the Invention

Problems to be Solved by the Invention

[0014] Proceeding from the prior art, the object of the present invention is to define an improved braking system.

Means for Solving the Problems

[0015] In particular, the present invention is based on the object of realizing a braking system for use in autonomous driving (hereinafter also referred to as AD) and / or for electric vehicles / hybrid vehicles having an increasingly high recuperation output (in the generator operation, energy is recuperated by brakes via the generator / or drive motor respectively). Preferably, the weight is minimized and / or the dimensions of the system are reduced and / or the reliability is increased.

[0016] A cost-effective braking system for autonomous driving, preferably realizing a braking system that satisfies all the required redundancies and very high requirements from the perspective of safety.

[0017] Furthermore, in the event of an ESP failure, the braking system provides sufficient ABS functionality in terms of braking distance and stability, as well as sufficient recovery capabilities.

[0018] In particular, an object of the present invention is to specify an improved braking system, along with a method for controlling a braking system that has redundant pressure supplyers, a very wide range of functions and availability, and at the same time, a very short installation length and low cost, especially in the event of brake circuit failure. Furthermore, a method is provided that enables a very high degree of availability even in the event of partial failure / leakage.

[0019] From the perspective of the braking system, the objective is achieved according to the present invention by a braking system having the features described in claim 1. From the perspective of the method, the objective is achieved according to the present invention by a method having the features described in claim 18.

[0020] The objective of focusing on the braking system is achieved in accordance with the present invention by a braking system having, in particular, the following: ● A first module comprising a first pressure supply unit having an electric drive, an optional second pressure supply unit, and a first control device for controlling the first pressure supply unit, wherein the first module is configured to cause at least one first brake circuit via a first connection point and at least one second brake circuit via a second connection point to collide with a pressurized medium, and wheel brakes are assigned to the first and second brake circuits, ● A second module including a third pressure supply unit, in particular a motor / pump unit, a brake pressure regulating valve and a shut-off valve, in particular an outlet valve and an input valve for regulating the pressure in the wheel brake, and a second control device for controlling the brake pressure regulating valve. ● A detection unit for detecting a first error event, in particular a partial failure of a third pressure supply unit, wherein the brake system in the first error event for providing ABS function and / or yaw-torque mediation is configured to perform (individual and / or selective) adjustment of pressure in the wheel brakes while activating at least one of the brake pressure regulating valve of the second module and / or the shut-off valve of the second module and the first pressure supply unit.

[0021] In this specification, a pressure supply unit can generally be understood to mean a unit (particularly a construction unit) of a brake system that provides brake pressure. Thus, the pressure supply unit works to bring at least one brake circuit into contact with a pressurized medium. A third pressure supply unit is preferably an ESP unit of the type described first. The shut-off valve in this specification may be configured to be bidirectional: that is, it may be hydraulically permeable in two flow directions. Depending on the design embodiment of the brake system and / or the application field of the brake system, an optional second pressure supply unit may be configured as an electronic pedal or a central computer.

[0022] A failure of at least a partial third pressure supply unit here can be understood to mean that the motor / pump unit fails while the other components of the third pressure supply unit are still functioning.

[0023] Not only brake pressure regulating valves, but also shut-off valves, particularly pressure boosting valves and pressure dissipation valves (hereinafter also called inlet valve EV and outlet valve AV), are specifically configured as solenoid valves. Solenoid valves have been found to be advantageous, especially due to their simple operating capability.

[0024] In one embodiment, the first pressure supply unit in a first error event is controlled in such a way that it generates a pressure drop having a pressure lower than the pressure in the wheel brake when the first pressure supply unit dissipates pressure to provide ABS braking operation.

[0025] In another embodiment, at least some of the shut-off valves of the first module are positioned and configured to establish a hydraulic connection between a brake pressure regulating valve, particularly an outlet valve, and a connection point. In a first error event, the brake system is preferably configured to open the assigned outlet valve to dissipate pressure in one of the wheel brakes.

[0026] In one embodiment, at least some of the shut-off valves of the first module are arranged and configured to establish a hydraulic connection between a brake pressure regulating valve, particularly an outlet valve, and a connection point, and the brake system in a first error event to dissipate pressure in one of the wheel brakes is preferably configured to open the assigned outlet valve.

[0027] Conveniently, a communication link, particularly a bus link, is configured between the first and second control units, and the first control unit is preferably configured to receive pressure measurements and / or wheel rotation speed signals from the second module via the communication link. The communication link may alternatively be an Ethernet or Flexray link.

[0028] Alternatively, the communication link may also be configured to be, for example, a wireless or analog connection for determining the measured values.

[0029] Alternatively, a communication link, particularly a bus link, may be configured between the first and second control units, and the first and second control units are preferably configured to receive pressure measurements and / or wheel rotation speed signals from a third pressure supply unit via the communication link. In the event of a communication link failure, ABS control can be performed using the data thus imported by the two control units. In this specification, receiving may also be understood to mean importing this type of sensor value and signal from one of the control units via the communication link.

[0030] In one embodiment, in a first error event, the first control unit and / or the second and / or third control unit are configured to control the first pressure supply unit and the brake pressure regulating valve to perform pressure feedback control of individual wheels and / or individual brake circuits within the wheel brake or brake circuit. According to the present invention, indirect control of actuators (e.g., valves) may also occur via the respective other control units. The third control unit may be understood to mean, for example, a central control unit.

[0031] In another embodiment, the first shut-off valve of the first module is located in the first hydraulic line between the first pressure supply unit and the first connection point. Furthermore, according to this embodiment, the second shut-off valve is located in the second hydraulic line between the first pressure supply unit and the second connection point. The brake system here is configured to detect a second error event (particularly a total failure of the third pressure supply unit). A total failure here can be understood to mean that all components of the third pressure supply unit have failed and are no longer functional. Furthermore, in the second error event, the brake system is configured to control the first pressure supply unit and the first and second shut-off valves to implement pressure feedback control for at least one individual brake circuit within at least two brake circuits. This control here preferably occurs via the first control device.

[0032] According to one embodiment, the brake system and in particular the first control device are configured to detect heterogeneous road conditions, in particular a μ-segmentation condition, and to control the first pressure supply unit in a second error event and in the detected heterogeneous road condition. This control works to adjust the target brake pressure in at least one selected brake circuit of the brake circuits, the target brake pressure being determined as a function of the wheel stopping pressure of the selected brake circuit's wheel brake having a higher coefficient of friction compared to the other wheel brakes of the selected brake circuit. Hereinherent road conditions are detected in such a way that a pressure difference between two wheel stopping pressures is detected. Heterogeneous road conditions exist when this pressure difference has a percentage value greater than 30% or 40%.

[0033] In a third error event, particularly in the additional failure event of the wheel sensor described above, or in the communication of the wheel rotation speed signal from the second module to the first module, the brake system in one embodiment in the third error event by the first pressure supply unit (particularly in the first control unit) is specified to control pressure enhancement and pressure dissipation to perform single-channel ABS using the wheel rotation speed sensor, and / or in a fourth error event, the brake system is specified to perform intermittent braking by modulating pressure between two fixedly adjusted pressure levels in both brake circuits. Thus, improved vehicle handling and braking performance compared to brake systems known in the prior art is also achieved in other error events and in additional failure events of other components of the brake system associated therewith.

[0034] Conveniently, at least one pressure sensor is provided for detecting brake pressure in at least one brake circuit.

[0035] In one embodiment, the first hydraulic line between the first pressure supply unit and the first connection point is configured without valves. Furthermore, the second hydraulic line between the first pressure supply unit and the second connection point is configured without valves. Herein, "without valves" can be understood to mean that no valves are located in the first hydraulic line or the second hydraulic line between the first pressure supply unit and the first or second connection point, respectively.

[0036] According to another embodiment, the first module has a rotary pump, in particular a single-circuit single-piston pump or a multi-piston pump for increasing and dissipating pressure. Furthermore, the first module according to this embodiment includes a solenoid valve hydraulically connected to a reservoir and at least one optional pressure transducer. The optional pressure transducer for feedback control of pressure increasing and pressure dissipation is preferably communicably connected to the first control device.

[0037] According to an alternative embodiment, the first pressure supply unit is configured as a gear pump for increasing and dissipating pressure. The gear pump is cleverly controlled using a pressure transducer or in accordance with current measurements (particularly the phase current i of the electric drive of the gear pump and the rotor angle α of the electric drive). In the case of this pressure transducer, the measurements may be used to provide redundancy (hot or cold).

[0038] Considering the various variations in the design configuration of the first pressure supply unit, the first pressure supply unit thus takes into account various configuration variations.

[0039] In another embodiment, at least one third shut-off valve is provided, which is arranged and configured such that when the third shut-off valve is closed, the first brake circuit is hydraulically disconnected from the first and second pressure supply units.

[0040] Furthermore, the first hydraulic line and / or the second hydraulic line are preferably (in either case) connected to the reservoir via a suction valve. The suction valve is used so that the third pressure supply unit can rapidly transport the volume directly from the reservoir with minimal hydraulic resistance, and so that the first and second pressure supply units are disconnected as a result of the operation of the third pressure supply unit during transport and are not damaged by this operation.

[0041] According to another design embodiment, the activation element, in particular the brake pedal, is located on a second pressure supply unit. Herein, the second pressure supply unit includes a master brake cylinder having a single piston that can be activated by the activation element and also having a pressurized chamber as well as a stroke simulator connected to the pressurized chamber. Furthermore, the pressurized chamber is connected to at least one brake circuit via a switchable solenoid feed valve FV.

[0042] As a result of the embodiment of the brake system according to the present invention described above, it becomes possible to perform operations that take safety into consideration, particularly in the error events listed below (in all of these error events, or in selected ones). Error event 1: Motor failure of the third pressure supply unit (ESP unit); 4-channel ABS with feedback control by the valve and the first pressure supply unit; Error event 2: Complete failure of the third pressure supply unit (ESP unit); 2-channel ABS with atypical "select low" / "select high" feedback control under normal operation; Error event 3: Complete failure of the third pressure supply unit (ESP unit), wheel rotation speed sensor available in a redundant manner and directly imported from the wheel brake into the first module; 1-channel ABS established; Error event 4: Complete failure of the third pressure supply unit (ESP unit) and failure of the wheel rotation speed sensor; establishment of automatic intermittent brakes.

[0043] Alternatively or additionally to the ABS control in error event 1, yaw torque control may be further implemented in this error event so that brake pressure is generated within a selectively selected wheel.

[0044] In terms of this method, the objective is achieved in particular by a braking system, and more particularly by a method for controlling the aforementioned braking system, the method comprising the following steps: ● A process of controlling the first pressure supply unit of the first module by the first control device during normal operation. ● A process of controlling multiple brake pressure regulating valves in the second module during normal operation. ● A process for detecting the first error event, particularly a partial failure of the second module. A step of controlling the brake system in a first error event such that adjustment of pressure (individually and / or selectively) within the wheel brakes occurs while using at least one (in particular, bidirectional) shut-off valve of the second module and the first pressure supply unit, in order to provide ABS braking operation and / or yaw torque mediation.

[0045] In one embodiment, the method further includes the following steps: ● A process for detecting a second error event, particularly a complete failure of the third pressure supply unit. ● A step of controlling the first pressure supply unit and at least two shut-off valves of the first module in such a way that pressure feedback control of individual brake circuits is performed in at least two brake circuits during a second error event.

[0046] According to another embodiment, the method includes the following steps: ● A process for detecting non-homogeneous road conditions, particularly the μ-segmentation status. ● A step of controlling the first pressure supply unit in a second error event in a manner in which the wheel brake of a selected brake circuit having a higher coefficient of friction compared to other wheel brakes is used to determine the target brake pressure in non-homogeneous road conditions.

[0047] In another embodiment, the method further includes the following steps: ● A process for detecting a third error event, particularly a complete failure of the third pressure supply unit and a failure of the wheel sensor. ● A step of controlling the first pressure supply unit in a manner in which 1-channel ABS is performed in a third error event, or in a manner in which intermittent braking is performed in a fourth error event by modulating the pressure between two predetermined pressure levels in at least one of the brake circuits (BK1, BK2).

[0048] According to an alternative embodiment, the method further includes the following steps: ● A step of determining the first wheel braking pressure on the first wheel brake to be assigned to one of the two brake circuits; ● A step of determining the second wheel braking pressure on a wheel brake assigned to the same brake circuit, wherein a non-uniform road condition is detected or determined when the first wheel braking pressure and the second wheel braking pressure differ by more than 30%.

[0049] Similar advantages to those described in relation to the braking system can be derived with respect to this method. [Brief explanation of the drawing]

[0050] Exemplary embodiments of the present invention are described in more detail below with reference to the accompanying drawings. In some cases in the accompanying drawings, which are greatly simplified in illustration:

[0051] [Figure 1a] A circuit diagram of a first exemplary embodiment of a brake system having a first pressure supply unit according to the first embodiment is shown. [Figure 1b] A circuit diagram of a second exemplary embodiment of a brake system having a first pressure supply unit according to the first embodiment is shown. [Figure 2] A circuit diagram of a first exemplary embodiment of a brake system having a first pressure supply unit according to a second embodiment is shown. [Figure 3]A circuit diagram of a first exemplary embodiment of a brake system having a first pressure supply unit according to a third embodiment is shown. [Figure 4] The circuit diagram for the third pressure supply unit (ESP unit) is shown. [Figure 5] The circuit diagram shows the third pressure supply unit (ESP unit) during pressure dissipation in the first error event in 4-channel ABS control. [Figure 6] The circuit diagram shows the third pressure supply unit (ESP unit) during pressure enhancement in the first error event in 4-channel ABS control. [Figure 7a] This shows the schematic temporal profile of "select-high" control in a brake circuit with two wheel brakes. [Figure 7b] This shows the schematic temporal profile of "select-low" control in a brake circuit with two wheel brakes. [Figure 8] A circuit diagram of a first exemplary embodiment of a brake system according to the present invention, having two shut-off valves and one feed valve, is shown. [Figure 9] A circuit diagram of a second exemplary embodiment of a brake system according to the present invention, having four shut-off valves and one feed valve, is shown. [Figure 10] The circuit diagram shows the third pressure supply unit (ESP unit) during pressure amplification in the first error event in yaw torque control. [Figure 11] The circuit diagram shows the third pressure supply unit (ESP unit) during pressure dissipation in the first error event in yaw torque control.

[0052] In the attached drawings, in some cases, parts with equivalent functions are given the same reference numeral. [Modes for carrying out the invention]

[0053] The brake system 2 according to the first exemplary embodiment shown in Figure 1a has a first pressure supply unit 6 in the first embodiment. In this embodiment, the first pressure supply unit 6 has an electric drive 8 that acts on the piston of a piston / cylinder unit. Furthermore, the brake system 2 (in particular the first pressure supply unit 6) has a first control device 9 that supplies control signals in particular to the electric drive 8.

[0054] The first pressure supply unit 6 here works to cause the first brake circuit BK1 and the second brake circuit BK2 to collide with the pressurized medium. To achieve this purpose, the cylinder of the first pressure supply unit 6 is hydraulically connected to the first brake circuit BK1 (see connection point A1) and the second brake circuit BK2 (see connection point A2) via a hydraulic line.

[0055] In the exemplary embodiment shown in Figure 1a, a shut-off valve PD1 is additionally placed in the hydraulic line, which can hydraulically and reversibly isolate the first pressure supply unit 6 from the first brake circuit BK1 and the second brake circuit BK2. The shut-off valve PD1 here is configured as a solenoid valve.

[0056] In addition, the first pressure supply unit 6, and in particular the cylinder of the first pressure supply unit 6, has a hydraulic connection line to a reservoir 40 in which a check valve is located. The hydraulic connection to the reservoir 40 is used to draw the pressurized medium from the reservoir 40.

[0057] Furthermore, the brake system 2 has a third pressure supply unit 90, which is only schematically shown in Figure 1a. The third pressure supply unit 90 is also called an ESP unit; that is, each ESP unit includes a third supply unit 90. Furthermore, a second control device 95 is provided for controlling the third pressure supply unit 90.

[0058] A communication link 100 (specifically, a CAN bus link) is established between the first control unit 9 and the second control unit 95. The communication link 100 is used to exchange data and / or signals between the two control units 9 and 95.

[0059] In particular, no valves are located within the hydraulic lines of the first brake circuit BK1 and the second brake circuit BK2 in the exemplary embodiment shown in Figure 1a.

[0060] Furthermore, pressure transducers p / U are provided in the hydraulic line, respectively, positioned between the shut-off valve PD1 and the first or second brake circuits BK1 and BK2. These pressure transducers p / U are useful in providing pressure information related to the brake circuits BK1 and BK2 so that the pressure is adjusted within the brake circuits BK1 and BK2, especially in the event of an error (see the embodiments below).

[0061] As an alternative to the pressure transducer p / u, in this embodiment, information items related to the pressure adjusted by the first pressure supply unit 6 are generated by estimating the pressure via the motor rotary encoder α / U and / or motor current i / u.

[0062] Figure 1b shows a circuit diagram of a second exemplary embodiment of the brake system 2 having a first pressure supply unit 6 according to the first embodiment.

[0063] This exemplary embodiment largely corresponds to the aforementioned exemplary embodiment of the brake system 2 shown in Figure 1a. The difference here is the shut-off valve BP1, TV BK2 In either case, the two shut-off valves BP1 and TV are located within the hydraulic line up to the brake circuits BK1 and BK2. BK2 Adjusting the brake pressure of individual brake circuits is possible, especially in error situations.

[0064] Figure 2 shows a circuit diagram of a first exemplary embodiment of the brake system 2 having a first pressure supply unit 6 according to a second embodiment. This exemplary embodiment of the brake system 2 similarly corresponds substantially to the design embodiment of the brake system 2 shown in Figure 1a. However, the first pressure supply unit 6 in the exemplary embodiment of Figure 2 is configured as a rotary pump, in particular as a single-circuit piston pump, in particular as a pump having one or more, in particular three, pistons. The piston pump is embodied in a manner equivalent to an ESP pump drive, in which one or more pistons via an eccentric are driven by the shaft of an electric motor. In this design embodiment, a valve PD2 is additionally provided to enable pressure enhancement or pressure dissipation, respectively. When enhancing pressure, the PD2 valve can also be advantageously used to compensate for pressure pulses of the pump driven by the eccentric. Pressure pulses are very high, in particular in the case of a single-piston pump.

[0065] As shown in Figure 3, the brake system 2 according to the first exemplary embodiment, which has a first pressure supply unit 6 according to the third embodiment, corresponds similarly to the brake system 2 according to Figure 1a, except for the embodiment of the first pressure supply unit 6. In the exemplary embodiment according to Figure 3, the first pressure supply unit 6 is configured as a gear pump. As an alternative to a pressure transducer p / u, the items of pressure-related information provided by the pressure supply unit 6 in this exemplary embodiment are generated by estimating the pressure by a motor rotary encoder α / U and / or motor current i / u. Thanks to the mechanical and functional design embodiment of the gear pump, no valve PD2 is required in this exemplary embodiment, as the pressure can also be dissipated by the gear pump by reversing the direction of rotation (for example, by embodying the drive motor of the gear pump as a brushless electric motor operated via a B6 bridge circuit and operating the electric motor in four-quadrant operation). Furthermore, for reasons related to the operating principle, the pressure pulse is significantly weaker than in the case of an eccentric piston pump.

[0066] Figure 4 shows a circuit diagram of a third pressure supply unit 90 (also called an ESP unit) having a motor / pump unit 91 for use in a brake system 2 according to the present invention. The ESP unit is well known and has a motor M, valves HSV1, HSV2, USV1, USV2, and inlet valves EV1-EV4 and outlet valves AV1-AV4 assigned to wheel brakes RB1, RB2, RB3, RB4, and a main component pump P having one storage chamber (SpK) for each brake circuit. This system has been described in many publications and patent applications. The system is already commercially available as a two-box brake system "e-booster + ESP" and is used in electric vehicles and hybrid vehicles in particular. In this application, only the outlet valves of the ESP unit are actuated by the e-booster via a CAN interface that interacts with the shaft torque of the generator (i.e., recovery to avoid increased brake pressure in the wheel brakes), and the storage chamber SpK is used to contain the pressurized medium.

[0067] One aspect of the present invention is that the first control device 9 is communicably connected to the second control device 95 ("ECU-ESP") of the ESP unit via a communication link 100, and in order to ensure safety, at least the inlet valves EV1 to EV4 can be controlled by the first control device 9.

[0068] Another aspect of the present invention lies in the dissipation of individual wheel pressures between the outlet valves AV1-AV4 and the HSV valve of the ESP unit.

[0069] A circuit diagram of the third pressure supply unit 90 (ESP unit) during pressure dissipation in the first error event is shown as an example within the brake circuit in Figure 5. The first error event here can be understood to mean that the motor M of the third pressure supply unit 90 has failed. In this case, pressure dissipation for the purpose of feedback control occurs via the first pressure supply unit 6. Specifically, this occurs in the sense that the piston of the first pressure supply unit 6 is returned (to the right in the plane of the page, identified by the arrow) and the outlet valves AV4, AV3 and shut-off valve HSV2 are opened, while the outlet valves AV4, AV3 are normally closed if not activated. Valves that are open for flow in this state are marked with an asterisk ("*") in Figure 5 in all cases to highlight the open state (left half of Figure 5). The states of other solenoid valves are not explicitly described. In this way, at least the inlet valves EV1-EV4 are closed by active activation, for example, when dissipating pressure. Pressure dissipation from wheel brakes RB3 and RB4 is illustrated in particular in Figure 5 (the flow direction of the pressurized medium from the wheel brakes to the first pressure supply unit 6 is identified by arrows). For this purpose, the pressure supply unit 90 according to the present invention may be equipped with shut-off valves HSV1 and HSV2, which are operated bidirectionally according to the invention, in contrast to their typical use in the ESP unit. Shut-off valves HSV1 and HSV2 are also used to resupply fluid from the reservoir 40 during normal ESP operation by the active pump. Thanks to the given configuration, pressure from wheel brakes RB1, RB2 or RB3, RB4 (not shown) can be selectively dissipated by opening and closing shut-off valves HSV1 and HSV2 when shut-off valves USV1 and USV2 are closed. Individual wheel pressure adjustment can be achieved by switching outlet valves AV1 to AV4 accordingly.

[0070] In the first error event, the operation of the valves, particularly the shut-off valves USV1, USV2, HSV1, HSV2 and outlet valves AV1-AV4, may also be caused by the first control unit 9 rather than by the second control unit 95, as in the normal case. When controlled by the first control unit 9, the control signals required for this purpose are transmitted to the third pressure supply unit 90 via the communication link 100. However, in normal operation without an error event, the second control unit 95 is responsible for activating the valves. Normal operation here can be understood as meaning the pressure increase required to brake the vehicle, for example, compared to the pressure increase for feedback control purposes (to prevent wheel slippage or obstruction).

[0071] Inlet valves EV1-EV4 are closed (by activation) when the pressure is released. The hydraulic connection to the first pressure supply unit 6 is established by opening the shut-off valve HSV2; the outflow of the pressurized medium here is then facilitated by the first pressure supply unit 6 rather than by the pump P, as is customary.

[0072] The pressure dissipation shown and explained by the example of the two wheel brakes RB3 and RB4 in Figure 5 can alternatively and similarly occur in individual brake circuits or individual wheel brakes. Individual wheel brake circuit feedback control (also called yaw-torque feedback control) is used for 4-channel ABS operation and yaw-torque arbitration.

[0073] Preferably, the pressure is detected by a pressure transducer p / U within the ESP unit during this feedback control so that pressure-related information is available at all times for feedback control of pressure dissipation.

[0074] The pressure increase in the first error event is shown, as an example, by the circuit diagram of the third pressure supply unit 90 according to FIG. 6. In this case, the second control device 95 controls the inlet valves EV1 to EV4 of the third pressure supply unit 90 as in the normal operation of the third pressure supply unit 90. The outlet valves AV1 to AV4 are closed (deactivated) when the pressure is increased. In addition, the valve USV2 or USV1 is opened during the pressure increase while the valves HSV1, HSV2 remain closed (deactivated). Since the pressure increase in the two wheel brakes RB3, RB4 is shown by the example in FIG. 6, the shut-off valves HSV2, USV2 located in this brake circuit BK1 are referred to in any case. Alternatively, the pressure increase shown and described by the example of the two wheel brakes RB3, RB4 in FIG. 6 can also occur in a similar manner individually in the brake circuits or individually in the wheel brakes, as a result of which individual wheel pressure increase and yaw torque mediation can occur.

[0075] The shut-off valve PD1 (if provided) for insulating the first pressure supply unit 6 from the brake circuits BK1, BK2 is operated to open during the pressure increase. The first pressure supply unit 6 conveys the pressurized medium into the wheel brakes RB3, RB4 via the hydraulic lines. Also, in this exemplary embodiment, the pressure transducer p / U (arranged in the second brake circuit BK2 according to FIG. 6) is preferably utilized to detect pressure-related information. Alternatively, the control of the valves of the third pressure supply unit 90 in this exemplary embodiment can also be taken over by the first control device 9 via the communication link 100.

[0076] Vehicle speed V F , wheel circumferential speed V R , reference speed V RFE , brake circuit pressure P of the "high wheel" h , brake circuit pressure P of the "low wheel" L The time profiles of are all shown in FIGS. 7a and 7b. The slip coefficient λ is the wheel speed at which the wheel becomes unstable and is approximately equal to the reference speed V RFE . In this way, typical key indicators such as the λ limit or (reference speed V RFE ), pressure dissipation Pab Sub-points 1, 1', 2, 4 (exceeding the coefficient of slip λ), pressure enhancement P auf Points 3 and 5 (when the coefficient of slip λ is below the limit) are shown in Figures 7a and 7b.

[0077] In homogeneous conditions (for example, when all wheels are on asphalt), the switching occurs for "select-low" feedback control (Figure 7b), meaning that the corresponding pressure is adjusted to be so low that no wheel is blocked. In this way, approximately 20% of all braking actions are eliminated.

[0078] In heterogeneous conditions, such as μ-splitting, where one vehicle's wheels are on ice and the other vehicle's wheels are on a wet or dry road, the "Select High" feedback control (Figure 7a) is activated, meaning that the wheels that are not blocked are feedback-controlled while the wheels with a low coefficient of friction remain blocked. Here again, approximately 20% of the optimal braking action is eliminated.

[0079] As already explained, Figure 7a shows the "Select High" feedback control. The explanation of ABS feedback control is based on general principles known from several patent applications, brake manuals, and brake brochures. As a result of the tire slip characteristics, the vehicle speed V F and wheel circumferential speed V R Slip between the two = wheel slip is thus formed as a result of increased brake pressure. In the case of the slip coefficient λ, which is a function of many factors, the tire circumferential force exceeds the maximum value, and without feedback control, the tire circumferential force leads to wheel obstruction. A feedback controller that evaluates wheel acceleration (positive and negative) and slip λ reduces pressure P ab and pressure increase P auf Pressure feedback control is effective in terms of achieving the desired optimal braking and cornering forces. Similarly, the reference speed = λ limit (corresponding to the optimal slip λ) is formed by the feedback controller using a complex algorithm.

[0080] Thus, Figure 7a specifically shows an exemplary time profile of "select-high" feedback control in a brake circuit with two wheel brakes. At time point 1, pressure augmentation P by the first pressure supply unit 6. auf As a result, wheel V R1 The stopping limit (at low friction coefficient μ) is reached when pressure p1 is reached, and this wheel will not be subjected to further pressure increase P auf As a result in this case, the wheel circumferential speed V R = 0, therefore the wheel is stopped. Consequently, the pressure continues to increase. Further pressure increase P auf At time point 2, wheel V was shortly after the λ limit was exceeded at pressure level p2. R2 Similarly, the wheel circumferential speed V becomes unstable. R2 This has the effect of causing a rapid decrease. Consequently, the pressure is reduced by the pressure supply, for example, by recovering the piston. The pressure difference ΔP between the previously defined pressures p1 and p2 is evaluated. If the pressure difference ΔP = P2 - P1 is large, that is, if pressure p2 exceeds pressure p1 by more than 30%, "select high" feedback control (also called selective "high μ" control) is initiated. Next, the pressure is ΔP in both brake circuits. ab = It is moderately reduced by 20%, that is, the circuit break valve (BP1 / BP2, TV BK2 (See Figure 9) is not used for selective pressure dissipation and is in an open state.

[0081] As a result, wheel V R2 It is not blocked at time 3 and undershoots the λ slip limit again at time 3. A gradual pressure increase follows from time 3. In the first stage, the pressure is increased, for example, from the previous ΔP, so that pressure p2 is reached again and subsequently exceeded. ab The value is increased by 70%, and then further increased by another 30% in the second step. In this phase, the pressure transducer p / U is preferably used for pressure measurement. The slip limit is again exceeded at time 4. Subsequently, the pressure is reduced again as at time 2, and then gradually increased again so that the wheel undershoots the slip limit again at time 5. This feedback control method is continued during feedback control.

[0082] Figure 7b shows an exemplary time profile of "select-low" feedback control, particularly in a brake circuit with two wheel brakes. Here, the pressure difference ΔP = P2 - P1 is relatively small, within the range of 10% to 20%. As a result, the wheels with small pressure differences become unstable. This is an indicator of operation on a homogeneous road surface. As previously explained in the context of "select-high" feedback control, the pressure is ΔP ab It is reduced and then gradually increased again. However, in contrast to "select high" feedback control, the pressure in the case of "select low" feedback control is dissipated more strongly (e.g., ΔP) so that the low wheel is released from the stopped state at time 6, i.e., in contrast to "select high" feedback control, no wheel is operated in the stopped state. ab =40%). The pressure is initially applied to the wheel V. R2 And then wheel V R1 It is kept low until it undershoots the λ limit at time 3; then it is simply increased again in stages. Wheel V R1 The slip limit is exceeded again at time 4, and the pressure is reduced again, and then gradually increased thereafter.

[0083] Figures 7a and 7b show only general embodiments of the "select-low" / "select-high" feedback control. Many enhancements are possible, such as another test in the "select-high" feedback control when the pressure level is reduced in the "high" wheel. Alternatively, the "select-low" wheel may also exit the blocked state again and exceed the λ limit without feedback control. This potential wheel speed profile is identified by X in Figure 7a. Another "select-low" / "select-high" test may then occur by selectively switching from "select-high" feedback control to "select-low" feedback control.

[0084] As already explained, in one exemplary embodiment, in a second error event, the switch from "select low" feedback control to "select high" feedback control occurs via the first control device 9 when the first control device 9 detects that the vehicle is located on a non-homogeneous hard surface (e.g., a partially icy road). For this purpose, it is necessary that the brake system 2 according to the present invention, provided by the first pressure supply unit 6, can adjust various pressures in the individual brake circuits BK1 and BK2. The design embodiment already schematically shown in Figures 1b, 8, and 9 is particularly suitable for this purpose. In order for this control strategy to be implemented, the control device 9 monitors the pressures in the individual wheel brakes RB1, RB2, RB3, and RB4 that would lead to wheel braking. If these pressures between two wheels (particularly within brake circuits BK1 and BK2) deviate from each other by more than 30%, the switch by the first control device 9 occurs from "select low" feedback control to "select high" feedback control so as to still achieve a very positive braking result even in the aforementioned error event.

[0085] Figure 8 shows a circuit diagram of the brake system 2, which includes a first module (referred to as X-Boost) and a second module. The first module (X-Boost) includes a first pressure supply unit 6 having an electric drive 8, a second pressure supply unit 14 having a master brake cylinder 22, and an activation element 26 having a brake pedal. Further provided is a valve mounting section having various solenoid valves and check valves.

[0086] The second module (in particular, the third pressure supply unit 90) includes an electrically driven motor / pump unit 91 having a pump with an electric drive. The third pressure supply unit 90 may be any ESP unit. A suitable ESP unit is described in detail in German Patent Application Publication No. 10 2014 205 645A1. Alternatively, a standard ABS unit without ESP functionality may be used as the second module.

[0087] Two modules (X-Boost and ESP unit) are defined to collide two brake circuits BK1 and BK2 with a pressurized medium, where the modules are preferably fluidly connected in series. In one exemplary embodiment, the X-Boost is fixed to the vehicle's scuttle, and the second module (ESP unit) at two hydraulic interfaces or connection points A1 and A2 (see bold black dots in Figure 8 relating to BK1 and BK2) is each connected to the vehicle's scuttle by hydraulic lines.

[0088] The first pressure supply unit 6 is connected to the first brake circuit BK1 or a corresponding interface via the first hydraulic line HL1. Also provided is a second hydraulic line HL2 for connecting the first pressure supply unit to the second brake circuit or a corresponding interface.

[0089] According to the present invention, the second pressure supply unit 14 of the X-Boost has only one master brake cylinder 22 having a piston 24 and a piston chamber. In exemplary embodiments, the second pressure supply unit 14 is embodied by a single circuit and via a third hydraulic line HL3, and a feed valve 69 is connected to the brake circuit BK1 or the corresponding hydraulic interface, respectively. Fluid connection to the second hydraulic line HL2 is performed via an optional first shut-off valve BP1 (highlighted by a dotted boundary). The second pressure supply unit 14 can be isolated from the brake circuits BK1, BK2 by closing the feed valve 69 in such a way that the activation element 26 acts only on the stroke simulator 28 during normal brake-by-wire operation without errors (e.g., without brake circuit failure).

[0090] In the exemplary embodiment shown in Figure 8, the brake circuits BK1 and BK2 can be isolated by an optional first shut-off valve BP1 (preferably open when not activated), if present. According to the present invention, in the event of a failure of the first pressure supply unit 6, the master brake cylinder 22 of the second pressure supply unit 14 can be connected to either only the first brake circuit BK1, or to both the first and second brake circuits BK1 and BK2, by opening the first shut-off valve BP1. For this emergency operation, a feed valve 69 is configured to open when not activated. As long as current is still applied, the feed valve 69 opens so that the second pressure supply unit 14 is no longer hydraulically disconnected from the brake circuits BK1 and BK2.

[0091] The first pressure supply unit 6 similarly acts selectively on the second brake circuit BK2 (the first shut-off valve BP1 is closed) or both brake circuits BK1 and BK2 (the first shut-off valve BP1 is open when not activated). The first shut-off valve BP1 is normally open so that "the first pressure supply unit 6 supplies pressure to both brake circuits BK1 and BK2, and the second pressure supply unit 14 is disconnected from the first brake circuit BK1 by the closed feed valve 69." If it is established that volume is being lost from the brake circuits BK1 and BK2, the brake circuit BK1 may be disconnected from the first pressure supply unit 6 by the first shut-off valve BP1 so that the second brake circuit BK2 can continue to operate without hydraulic fluid loss in the event of leakage in the first brake circuit BK1.

[0092] In the exemplary embodiment, the shut-off valve BP1 is embodied as a solenoid valve, and the spherical seat of the shut-off valve BP1 by a connector (valve seat connector) is connected to a portion of the hydraulic line leading to the first pressure supply unit 6. In this way, the shut-off valve BP1 can also be reliably closed by being activated in the event of a failure of the first brake circuit BK1, and cannot be forcibly opened by high pressure when the first pressure supply unit 6 is operating.

[0093] The second pressure supply unit 14 supplies stroke simulator 28 through exhaust holes in the wall of the master brake cylinder 22 so that when the activation element 26 is activated, a progressive tactile resistance in the form of a restoring force can be felt as a function of the activation variable of the activation element 26. The activation variable here can be understood as how "firmly and / or how far" the driver activates the activation element 26, which is configured as a brake pedal, and thus pushes the piston 24 into the master brake cylinder 22. The progressive tactile resistance is also called pedal characteristic.

[0094] A stroke simulator valve 29 may be provided to prevent connection to the stroke simulator 28.

[0095] The second pressure supply unit 14 has at least one exhaust port 38 which is connected to the reservoir 40 via a hydraulic line. The reservoir 40 is also part of the brake system 2.

[0096] In the exemplary embodiment, not only the throttle DR but also the check valve RVHZ may be located in the hydraulic line between the exhaust port 38 and the reservoir 40. This check valve RVHZ and the first pressure supply unit 6 make it possible to perform diagnostics related to the storage status of the sealing elements located not only in the first pressure supply unit 6 but also in the stroke simulator 28. The stroke simulator valve 29 (if present) may be closed when checking the sealing of the master brake cylinder 22.

[0097] As shown in the figure, the master brake cylinder 22 has two sealing elements 42a and 42b configured as an annular seal. The exhaust hole 38 is located between the two sealing elements 42a and 42b. The throttle DR is located in the connection between the two sealing elements 42a and 42b and the exhaust hole 38 located between the reservoir 40.

[0098] The throttle DR is sized in terms of its flow rate such that the pedal characteristics remain virtually unchanged in the event of a failure of the sealing element 42a (3 mm pedal stroke within 10 seconds). Furthermore, temperature-related volume compensation for the pressurized medium may occur via the throttle DR.

[0099] High-pressure peaks in the brake circuits BK1 and BK2 (which can place significant stress on the first pressure supply unit 6) may be generated during the ABS operation of the third pressure supply unit 90. In a modified form of the design embodiment shown in Figure 8, the pressure limiting valve UV is connected to the piston chamber of the first pressure supply unit 6 via a hole so that the high-pressure peaks are dissipated and damage to the system is avoided.

[0100] The suction valve NV is similarly fluid-connected to the piston chamber of the first pressure supply unit 6, and allows the pressurizing medium to be resupplied from the reservoir 40. In this way, the first pressure supply unit 6 can independently introduce additional pressurizing medium into the brake circuits BK1 and BK2. An additional exhaust hole provided in the cylinder of the first pressure supply unit 6 allows for volume compensation at the initial position of the piston of the first pressure supply unit 6.

[0101] The third pressure supply unit 90 is only schematically shown in Figure 8. The pressure supply unit 90 ultimately supplies pressure to the four wheel brakes RB1, RB2, RB3, and RB4. In the schematic diagram, wheel brakes RB1 and RB2 actuate the vehicle's front axle VA, and wheel brakes RB3 and RB4 actuate the vehicle's rear axle HA. An electric drive motor for driving the vehicle is located on the vehicle's rear axle HA. The vehicle may be a pure electric vehicle or a hybrid vehicle.

[0102] The first brake circuit BK1 is connected to wheel brakes RB1 and RB2, and the second brake circuit BK2 is connected to wheel brakes RB3 and RB4. This correspondence is advantageous for the hydraulic assembly shown in Figure 8.

[0103] The third pressure supply unit 90 further includes a control unit 95 ("ECU-ESP").

[0104] The second pressure supply unit 14 similarly has a printed circuit board having a level detector NST that detects the position of a magnetic float gauge NS in the reservoir 40. The PCB further has sensors 30a, 30b for detecting the pedal stroke as well as the difference in stroke distance between the piston 24 and the pedal stroke.

[0105] A suction valve 70b connecting the pump of the third pressure supply unit 90 to the storage unit 40 is provided in the first brake circuit BK1 to provide additional pressurizing medium for the third pressure supply unit 90.

[0106] If the pump of the third pressure supply unit 90 requires a pressurizing medium for the second brake circuit BK2, the pressurizing medium can thus be supplied from the reservoir 40 via the suction valve 70c.

[0107] In this manner, to draw in the pressurized medium, the two brake circuits BK1 and BK2 are connected to the reservoir 40 via their respective hydraulic lines HL1 and HL2, each through a single suction valve 70b or 70c. To achieve optimal suction of the pressurized medium, the suction valve 70c preferably has a diameter in the range of 30 mm to 50 mm (particularly 40 mm in diameter).

[0108] The exemplary embodiments optionally include a controller for the clearance between the brake pads and the disc brake. The wheel brakes RB1, RB2, RB3, RB4 (see Figure 8) can be configured as frictionless wheel brakes RB1, RB2, RB3, RB4. In the brake-by-wire system, a disc brake having brake pads separated by clearance without pressure within the brake system allows for reduced frictional resistance. This can be achieved by actively retracting the brake pads by using a brake pad rollback seal, a return spring, or by generating a vacuum with a pressure supply 6, as described by the applicant in European Patent No. 2,225,133.

[0109] The clearances within the wheel brakes RB1, RB2, RB3, and RB4, which are variable during operation, can be measured individually for each wheel or brake circuit by evaluating the pressure profile using the first pressure supply unit 6. According to the present invention, the corresponding measurements may occur during service or otherwise while the vehicle is in operation. The measurements are preferably performed in a stationary vehicle or after braking.

[0110] By using the known clearance values ​​of the wheel brakes RB1, RB2, RB3, and RB4, the clearance when activating the wheel brakes RB1, RB2, RB3, and RB4 is quickly overcome first by the piston stroke control of the first pressure supply unit 6. In this regard, the use of a brushless motor as the electric drive 8 of the first pressure supply unit 6, which has a small time constant, is preferred because the act of overcoming the clearance can be performed without the driver perceiving the clearance when activating the brakes.

[0111] Furthermore, the brake system 2 can be controlled so that the vehicle's electric motor is active in the clearance phase. In this way, the braking action is generated immediately upon activation of the brakes.

[0112] In one exemplary embodiment of the present invention, the clearance differences between the wheel brakes RB1, RB2, RB3, and RB4 are compensated in that the inlet valves EV1-EV4 of the second module (ESP unit) are activated and / or that the electric motors of one or more vehicle axles are utilized to generate braking action at the beginning of braking. The clearances can generally reduce or avoid the stick-slip effect of the new braking system at low speeds.

[0113] In one exemplary embodiment, in the event of an ESP unit failure (error event 4), the braking system 2 according to the present invention implements a very simple variant of intermittent braking. Wheel lock is avoided, and maneuverability is maintained by moving the piston of the first pressure supply unit 6 in a reciprocating manner between upper and lower pressure ranges. In contrast to single-channel ABS operation, no measurements (e.g., pressure, wheel speed) are required in this deceleration form.

[0114] Automatic intermittent braking achieves a sufficient stopping distance (approximately 200% of the stopping distance in ABS mode) compared to full-fledged individual wheel ABS, and maintains acceptable stability while preserving maneuverability.

[0115] The brake system according to the present invention offers the decisive advantage that the brake pedal acts only on the piston 24 and is isolated from the brake circuits BK1 and BK2 by the feed valve 69. In this way, the function of the automatic intermittent brake having X-boost or X-booster, respectively, cannot be interfered with by the driver, in contrast to the prior art (International Publication No. 2011 / 098178).

[0116] Instead of intermittent braking, a single-channel ABS operation with "select-low" feedback control (in error event 3) may be implemented. This results in further degradation of stopping distance (approximately 400% less stopping distance compared to full wheel-by-wheel ABS), but achieves unlimited vehicle stability and is superior to intermittent braking in terms of this feature. This form of single-channel ABS operation requires measurements such as pressure and wheel speed, which can be imported from the ESP unit via a communication link / interface (e.g., CAN interface).

[0117] To further increase the availability of the brake system 2 according to the present invention as shown in Figure 8, the electric drive 8 of the first pressure supply unit 6 is connected to the X-boost control unit 9 (ECU-DV) via two redundant three-phase strands, and the electric system is implemented to be (partially) redundant. For example, two B6 bridges may be provided for each strand. Furthermore, in at least one exemplary embodiment, the electronic system is connected to two redundant power supplies. In this way, the failure probability of the electric drive 8 can be reduced by a coefficient of 4-10, and the error event (failure of the first pressure supply unit 6) can be further significantly reduced.

[0118] The control unit 95 of the ESP unit 90 and the control unit 9 (ECU-DV) of the X-Boost are connected to each other via a communication link 100 (e.g., a CAN bus). In this respect, control commands that cause the activation of the drive 91 and / or the provided valves can be released to the third pressure supply unit 90 (see also Figure 8).

[0119] The following safety-related redundancy can be implemented by using brake system 2 as shown in Figure 8: - Ensure sufficient braking action to meet legal requirements in the following brake circuit failures: a) failure of the second pressure supply unit 14, b) failure of the first pressure supply unit 6, or c) failure of the first pressure supply unit 6 and the third pressure supply unit 90 (simultaneously), i.e., also meet legal requirements in the case of double error: ○ Error event 1 - Failure of the third pressure supply unit 90: Deceleration due to increased braking force via the first pressure supply unit 6 in both brake circuits BK1 and BK2; ○ Error event 2 - Failure of the third pressure supply unit 90 and brake circuit BK1: for example, deceleration by increasing the braking force via the first pressure supply unit 6 on the rear axle; ○ Error event 3 - Failure of the third pressure supply unit 90 and the second brake circuit BK2: For example, deceleration by the second pressure supply unit 14 on the front axle (the first shut-off valve BP1 is closed) ○ Error event 4 - Failure of the first pressure supply unit 6: Deceleration by increasing braking force via the third pressure supply unit 90; ○ Error event 5 - Failure of the first pressure supply unit 6 and the first brake circuit BK1 or the second brake circuit BK2: Deceleration by increasing the braking force via the third pressure supply unit 90 in one of the brake circuits BK1 or BK2 (optionally amplified by the vehicle's electric motor on one axle); ○ Error event 6 - Failure of the first pressure supply unit 6 and the third pressure supply unit 90: Braking by the master brake cylinder on the front axle VA and optionally by the electric drive motor on the rear axle HA; ○ Error event 7 - Onboard network failure: Selective braking by the second pressure supply unit 14 on the front axle VA and rear axle HA; - Electronic brake force distribution (EBV) in the event of an ESP unit failure by generating pressure in the first brake circuit BK1 via the third pressure supply unit 90, generating pressure in the second brake circuit BK2 via the first pressure supply unit 6 with the first shut-off valve BP1 closed, and controlling the first pressure supply unit 6 via the sensor assembly of the second pressure supply unit 14. To achieve this objective, a switch brake circuit division is required, namely, the wheels of the front axle VA are connected to the first brake circuit BK1, and the wheels of the rear axle HA are connected to the second brake circuit BK2; - Controlling the clearance between the brake pads and the disc brake; - 4-channel ABS operation and / or yaw-torque feedback control when activating the valves of the ESP unit; - One-channel ABS operation or implementation of automatic intermittent braking.

[0120] Figure 9 shows an alternative design embodiment of the X-boost according to Figure 8. In contrast to the exemplary embodiment according to Figure 8, the second shut-off valve TV BK2 This is located within the second hydraulic line HL2 in Figure 9. This second shut-off valve TVBK2 This allows the second brake circuit BK2 to be hydraulically disconnected from the first pressure supply unit 6. In this way, the first pressure supply unit 6 can selectively supply pressurizing medium to the first brake circuit BK1, the second brake circuit BK2, or both brake circuits. If a volume loss is detected in the second brake circuit BK2, the second brake circuit BK2 can be disconnected.

[0121] Furthermore, the exemplary embodiment shown in Figure 9 differs in that a third shut-off valve BP2 is provided in the first hydraulic line HL1 between the first shut-off valve BP1 and the first connection point A1 of the first brake circuit BK1. Preferably, the third shut-off valve BP2 is positioned such that the third hydraulic line in the hydraulic connection between the first shut-off valve BP1 and the third shut-off valve BP2 opens into the first hydraulic line HL1. The third shut-off valve BP2 allows the first brake circuit BK1 to be hydraulically disconnected not only from the first pressure supply unit 6 but also from the second pressure supply unit 14. Thus, in the event of a failure of the first pressure supply unit 6, the pressurized medium starting from the second pressure supply unit 14 is supplied to the feed valve 69, the first shut-off valve BP1 and the second shut-off valve TV BK2 It can be introduced into the second brake circuit BK2 via this. No pressurizing medium is administered into the first brake circuit BK1 when the third shut-off valve BP2 is closed.

[0122] The following safety-related redundancy can be implemented by using brake system 2 as shown in Figure 9: - To ensure sufficient braking action in the event of failure of one or more pressure supply units. ○ Error events 1-7: Refer to Embodiment 1; ○ Error event 8 - Failure of feed valve 69 (e.g., leakage) or electrical failure: Close the third hydraulic line HL3 by shut-off valves BP1 and BP2 so that the stroke simulator 28 is fully effective; the first pressure supply unit 6 adjusts the wheel pressure in brake circuit BK2; and / or the ESP unit adjusts the wheel pressure in both brake circuits BK1 and BK2. ○ Further flexibility: Selectively supplying pressure from the master brake cylinder to brake circuit BK1 or BK2 in the event of a brake circuit failure; - To ensure 4-channel ABS feedback control and / or yaw torque feedback control when activating the valves of the ESP unit. - Two-channel ABS operation using select-low and select-high methods, or one-channel ABS using a select-low method via a wheel rotation speed sensor; - Electronic brake force distribution (EBV) in the event of an ESP unit failure by generating pressure in the brake circuit BK1 via the second pressure supply unit 14, generating pressure in the brake circuit BK2 via the first pressure supply unit 6 through the closed first shut-off valve BP1, and controlling the pressure supply via the sensor assembly of the second pressure supply unit 14. To achieve this objective, S / W brake circuit distribution is required, and the distribution of brake force within the brake circuit is performed by shut-off valves BP1, BP2 and TV BK2 It is controlled via [a specific mechanism]. According to the present invention, the piston of the first pressure supply unit 6 for applying a suitable pressure can be controlled by a reciprocating stroke motion. Optionally, pressure adjustment can be achieved via PWM control of a valve, particularly a shut-off valve; - Clearance control is already embodied in the exemplary embodiment shown in Figure 8. An exemplary embodiment, such as that shown in Figure 9, involves shut-off valves BP1 and TV. BK2The corresponding pilot control preceding the braking force enhancement operation by sequentially opening the valves presents an additional possibility for compensating for unequal clearances in the wheel brakes RB1, RB2, RB3, and RB4 of the brake circuits BK1 and BK2. Alternatively, PWM operation can also be used so that different flow cross-sections are established to the brake circuits BK1 and BK2 and unequal clearances can be compensated simultaneously. Here, S / W brake circuit splitting is preferred. This method is readily possible since the brake circuit shutoff valve is a component of the X-Boost module and can be implemented without any time delay or vulnerability to failure (e.g., by utilizing the interface between the X-Boost and ESP units). In this way, the brake system can be designed such that, for example, clearance is not provided on the brake pads on the front axle but is provided on the rear axle. In this way, failure of the first pressure supply unit 6 does not result in a time delay in braking when pressure is generated by the activation unit and acts on the wheel brakes RB1, RB2, RB3, and RB4 of the front axle VA according to the present invention. Furthermore, greater braking force can be generated by the front axle VA.

[0123] The circuit diagrams of the third pressure supply unit (ESP unit) during the first error event in yaw-torque feedback control, specifically when dissipating pressure (see Figure 11) or increasing pressure (see Figure 11), are shown in Figures 10 and 11, respectively. In principle, the feedback control here is performed in a similar manner to that of a 4-channel ABS, which is similarly possible in the first error event. However, in the case of yaw-torque feedback control, pressure dissipation as well as pressure increase (in contrast to 4-channel ABS feedback control) occurs not only through the USV valve but also through the inlet valves EV1-EV4. Valves that are appropriately opened for the flow are marked with an asterisk (*) in both Figure 11 and Figure 10, respectively. The states of other solenoid valves are not explicitly described. For example, at least the inlet valves EV2, EV3, and EV4 are thus closed by active activation during pressure dissipation. In the context of this application, "open" can also be understood to mean that these valves are operated by a PWM signal so that a predetermined opening cross-section is established, as long as the valves are PWM-operable valves. In this way, the flow rate through each valve can be controlled by activating the valve with a PWM signal. Specifically, the inlet valves EV1-EV4 and valves USV1 and USV2 in Figures 10 and 11 are operable with a PWM signal. In this way, the flow rates through these valves can be feedback controlled or controlled in the situations described below.

[0124] Wheel-selective yaw-torque feedback control during pressure buildup in wheel brake RB4 is illustrated in an exemplary manner in Figure 10. To achieve this objective, inlet valves EV1 assigned to each wheel brake (here, wheel brake RB4) and shut-off valves USV2 assigned to each brake circuit (here, first brake circuit BK1) are passed through by the flow of pressurizing medium. In this embodiment, the valves do not need to be actively activated as they are passively opened in a deactivated open state and allow bidirectional flow of pressurizing medium. For selective pressure generation in wheel brake RB4, the other inlet valves EV1-EV3 (of RB1-RB3) whose pressure is not built up are actuated in such a way that the solenoid valves move from an open state to an activated closed state. In this context, the actuated valves that open when deactivated can be understood as meaning that the inlet valves EV1-EV3 are closed (i.e., switched off from allowing pressurizing medium to flow). Similarly, the HSV valve for selective pressure generation in wheel brake RB4 is closed (i.e., switched off from allowing pressurizing medium to flow).

[0125] In this way, the pressure from the first pressure supply unit 6 via the shut-off valve USV2 and the inlet valve EV4 is exclusively applied to the wheel brake RB4 (circumstantially indicated by the arrow). In addition to the wheel brakes RB1, RB2, RB3, and RB4, yaw torque can be generated in multiple wheel brakes RB1, RB2, RB3, and RB4. To achieve this objective, the inlet valves EV1-EV4 in the wheel brakes RB1, RB2, RB3, and RB4 are closed in all cases, and the pressure is not increased. This increase allows yaw torque to be generated simultaneously in, for example, two wheel brakes RB1, RB2, RB3, and RB4 on one vehicle side. Since brake circuits are usually embodied in black and white or diagonally, in this case, consequently, one wheel brake RB1, RB2, RB3, and RB4 of one brake circuit is affected by the pressure in all cases. Circuit shut-off valves BP1 / BP2 and TV of the first module BK2As a result of sequential or simultaneous multiple operations, further potential enhancement of yaw-torque feedback control is possible (embodiment shown in Figure 9). In this way, the pressure in the wheel brakes RB1, RB2, RB3, RB4 (e.g., RB4 of the right rear wheel) is controlled by the circuit break valve TV BK2 Once the pressure reaches the pressure valve, it can be set to a pressure level that will cause it to close in order to maintain this pressure.

[0126] Furthermore, another pressure level may be regulated within the wheel brakes RB1, RB2, RB3, RB4 of other brake circuits (e.g., RB2 of the right front wheel), and the second brake circuit shut-off valve BP1 or alternatively BP2 is closed to maintain the pressure. Brake circuit shut-off valves BP1 / BP2 and TV BK2 Therefore, the inlet valves of the wheel brakes RB1, RB2, RB3, and RB4 have check valves connected in parallel, which is necessary to maintain pressure. In this way, maintaining pressure within the second module (ESP unit) is impossible if the pressure dissipates or if a lower pressure level is regulated within the second brake circuit. Thus, the following conditions are the result of the relevant valves of the third pressure supply unit 90 for pressure enhancement as shown in Figure 10: HSV1: Closed (not activated) HSV2: Closed (inactive) EV4: Open (Open if not activated by the PWM method or if activated: i.e., partially open) EV1-EV3: Closed (Activated) All other valves are in their initial hydraulic (especially deactivated) state.

[0127] In the case of pressure dissipation shown in Figure 11, for example, the return of the pressurized medium occurs from the wheel brake RB4 through the inlet valve EV4 and the shut-off valve USV2 to the first pressure supply unit 6 in a similar but reversed manner. Similarly, pressure dissipation also occurs during yaw-torque mediation in multiple wheel brakes. Here again, a multiplexing method is preferably used.

[0128] In one embodiment, multiple wheel brakes RB1, RB2, RB3, RB4 (in particular, all four) may be additionally actuated individually and wheel-selectively in a similar manner, thereby enabling wheel-selective yaw-torque feedback control. Alternatively or additionally, the yaw-torque feedback control in one embodiment may occur in a brake-circuit-selective manner such that two wheel brakes of a single brake circuit are actuated together in either case.

[0129] Specifically, the following conditions are derived with respect to the associated valve of the third pressure supply unit 90 for pressure dissipation as shown in Figure 11: HSV1: Closed (not activated) HSV2: Closed (inactive) EV4: Open (Open if not activated by the PWM method or if activated: i.e., partially open) USV1: Closed (closed when activated) EV1-EV3: Closed (Activated) All other valves are in their initial hydraulic (especially deactivated) state.

[0130] At this point, it is noted that all of the above-mentioned components should be considered individually in each case, even without the additionally described features in each context, and even without the features being individually and explicitly identified as optional features in each context, by using, for example, “particularly,” “preferably,” “for example” (e.g., “optionally,” in parentheses, etc.), and in particular as independent design embodiments of the invention or in combination or any subcombination as refinements, as defined in the introduction of this specification and the claims, respectively. Deviance from these is possible. Specifically, it is noted that the terms “particularly” or in parentheses do not identify features that are essential in each context. [Explanation of Symbols]

[0131] 2 Brake System 6. First pressure supply unit 8 Electric drive 9. Control Unit (ECU-DV) 14. Second pressure supply unit 22 Master brake cylinder 24 pistons 26 Activation elements 28. WS Itinerary Simulator 28a, 28b Sealed elements of the stroke simulator 29 Stroke simulator valve 30a, 30b Pedal stroke sensor 38 Exhaust hole of the second pressure supply unit 40 Storage containers 42a, 42b Sealing elements of auxiliary pistons 69 Feed valve 70b, 70c, 80d Suction valve (check valve) RV1, RV2, NV Intake Valve (Check Valve) RVHZ Check Valve (Master Cylinder) 74, PD1, PD2 shut-off valves 80. UV pressure limiting valve 90 Third pressure supply unit 91 Motor / Pump Unit 95 ESP Unit Control Device 100 Communication Link (CAN Bus) A1, A2 connection point B1, B2 Electrical Connection (Three-phase) P Pump M Motor BP1, TV1 First shut-off valve TV BK2 TV2 Second shut-off valve BP2 Third shut-off valve RB1, RB2, RB3, RB4 Wheel Brakes DR Throttle BK1 First Brake Circuit BK2 Second Brake Circuit HL1 Hydraulic Line 1 HL2 Second hydraulic line HL3 Third hydraulic line HL4 4th hydraulic line VA front axle HA rear axle NS Float Gauge NST Level Detector HSV1, HSV2 ESP unit shut-off valve USV1, USV2 ESP unit shut-off valve AV1, AV2, AV3, AV4 ESP unit outlet valves Inlet valve for EV1, EV2, EV3, and EV4 ESP units

Claims

1. Brake system (2), ● A first module comprising a first pressure supply unit (6) having an electric drive (8), and a first control device (9) for controlling the first pressure supply unit (6), wherein the first module is configured to supply a pressurizing medium to at least one first brake circuit (BK1) via a first connection point (A1) and at least one second brake circuit (BK2) via a second connection point (A2), and wheel brakes (RB1, RB2, RB3, RB4) are assigned to the brake circuits (BK1, BK2), ● A third pressure supply unit (90), i.e., a motor / pump unit (91), brake pressure regulating valves and shut-off valves (USV1, USV2, HSV1, HSV2) for regulating the pressure in the wheel brakes (RB1, RB2, RB3, RB4), the brake pressure regulating valves and shut-off valves (USV1, USV2, HSV1, HSV2) comprising outlet valves (AV1, AV2, AV3, AV4) and input valves (EV1, EV2, EV3, EV4), and a second module including a second control device (95) for controlling the brake pressure regulating valves (AV1-AV4, EV1-EV4). ● A detection unit for detecting a first error event, namely at least a partial failure of the third pressure supply unit (90), wherein, in order to provide ABS function and / or yaw-torque mediation, the brake system (2) in the first error event is configured to perform individual and / or selective adjustment of the pressure in the wheel brakes while operating at least one of the brake pressure regulating valves (AV1-AV4, EV1-EV4) of the second module and / or the shut-off valves (USV1, USV2, HSV1, HSV2) of the second module, and the first pressure supply unit (6), the detection unit It has, In the first error event, the first pressure supply unit (6) is controlled in such a manner that when the first pressure supply unit (6) releases pressure from the wheel brakes (RB1, RB2, RB3, RB4) through the respective outlet valves (AV1, AV2, AV3, AV4) to provide the ABS braking operation, it produces a pressure drop having a pressure lower than the pressure inside the wheel brakes (RB1, RB2, RB3, RB4). At least some of the shut-off valves (USV1, USV2, HSV1, HSV2) of the second module are positioned between the outlet valves (AV1, AV2, AV3, AV4) and the connection points (A1, A2) and are configured to establish a hydraulic connection between the outlet valves (AV1, AV2, AV3, AV4) and the connection points (A1, A2), and in the first error event, the brake system (2) is configured to open the assigned outlet valve (AV1, AV2, AV3, AV4) to dissipate the pressure in one of the wheel brakes. Brake system (2).

2. The brake system (2) according to claim 1, wherein a communication link (100) in the form of a bus link is configured between the first control device (9) and the second control device (95), and the first control device (9) is configured to receive pressure measurement values ​​and / or wheel rotation speed signals of the third pressure supply unit (90) via the communication link (100).

3. A communication link (100) in the form of a bus link is configured between the first control device (9) and the second control device (95), and the first control device (9) and the second control device (95) are configured to receive pressure measurement values ​​and / or wheel rotation speed signals of the third pressure supply unit (90) via the communication link (100), the brake system (2) according to claim 1.

4. The brake system (2) according to any one of claims 1 to 3, wherein the third control device, meaning the first control device (9), the second control device (95), or the central control unit, is configured to control the first pressure supply unit (6) and the brake pressure regulating valves (AV1-AV4, EV1-EV4) in the event of the first error event, so as to perform pressure feedback control on individual wheels and / or individual brake circuits within the wheel brakes (RB1, RB2, RB3, RB4) or the brake circuits (BK1, BK2).

5. - The first shut-off valve (BP1) of the first module is located in the first hydraulic line (HL1) between the first pressure supply unit (6) and the first connection point (A1), and the second shut-off valve (TV BK2 The brake system (2) according to any one of claims 1 to 4, wherein the brake system (2) is located in the second hydraulic line (HL2) between the first pressure supply unit (6) and the second connection point (A2), - To detect a second error event corresponding to a complete failure of the second module, and - In the second error event described above, the first pressure supply unit (6) and the first and second shut-off valves (BP1, TV) are configured to perform pressure feedback control on at least one individual brake circuit within the at least two brake circuits (BK1, BK2). BK2 A brake system (2) configured to control ).

6. The first control device (9) is - To detect non-homogeneous road conditions, particularly μ-segmentation conditions, and - The brake system (2) according to claim 5, configured to control the first pressure supply unit (6) to adjust a target brake pressure determined as a function of the wheel cutoff pressure of the wheel brake (RB1, RB2, RB3, RB4) of the selected brake circuit (BK1, BK2) having a higher coefficient of friction compared to the other wheel brakes (RB1, RB2, RB3, RB4) of the selected brake circuit (BK1, BK2) in the second error event and in the non-uniform road conditions.

7. The brake system (2) according to any one of claims 1 to 6, wherein at least the second module has a wheel sensor for detecting wheel speed, and the wheel sensor is configured to transmit a wheel rotation speed signal generated from the detected wheel speed or the detected wheel speed to the first control device (9) via a communication link (100).

8. The brake system (2) according to any one of claims 1 to 7, wherein the first control device (9) is configured to control pressure rise and pressure dissipation in the third error event by the first pressure supply unit (6) to perform one-channel ABS using a sensor, and / or in the fourth event to perform intermittent braking by modulating pressure between two fixedly adjusted pressure levels in two brake circuits (BK1, BK2).

9. The brake system (2) according to any one of claims 1 to 8, wherein at least one pressure sensor is provided for detecting the brake pressure in the at least one brake circuit (BK1, BK2).

10. The first module is: - Rotary pumps for increasing and dissipating pressure, in the form of a single-piston pump or a three-piston pump; - Solenoid valve (PD2) hydraulically connected to the storage container (40); - The brake system (2) according to any one of claims 1 to 9, comprising at least one pressure transducer communicably connected to the first control device (9) for feedback control of the pressure increase and dissipation by the rotary pump.

11. The brake system (2) according to any one of claims 1 to 9, wherein the first pressure supply unit (6) is configured as a gear pump for increasing and dissipating pressure.

12. The gear pump is controlled using a pressure transducer, or according to the measured value of the phase current i of the electric drive of the gear pump and the rotor angle α of the electric drive. Brake system (2) as described in item 11.

13. A brake system (2) according to any one of claims 1 to 12, wherein at least one third shut-off valve (BP2) is provided, and the third shut-off valve (BP2) is arranged and configured such that, when the third shut-off valve (BP2) is closed, the first brake circuit (BK1) is hydraulically disconnected from the first and second pressure supply units (6, 14).

14. The brake system (2) according to any one of claims 1 to 13, wherein a first hydraulic line (HL1) and / or a second hydraulic line (HL2) are connected to a reservoir (40) via suction valves (70b, 70c), respectively.

15. A brake system (2) according to any one of claims 1 to 14, wherein an activation element (26) in the form of a brake pedal is disposed on a second pressure supply unit (14), and the second pressure supply unit (14) includes a master brake cylinder (22) having a single piston (24) that can be activated by the activation element (26).

16. ● A step of controlling the first pressure supply unit (6) of the first module with the first control device (9) during normal operation, ● A process of controlling multiple brake pressure regulating valves (AV1-AV4, EV1-EV4) in the second module during normal operation. - A step of detecting a first error event corresponding to a partial failure of the second module; - A step of controlling the brake system (2) in the first error event such that adjustment of the pressure in the wheel brakes (individually and / or selectively) occurs while activating the brake pressure regulating valves (AV1-AV4, EV1-EV4) of the second module and / or the shut-off valves (USV1, USV2, HSV1, HSV2) of the second module and the first pressure supply unit (6) in order to provide ABS braking operation and / or yaw torque mediation. A method for controlling the brake system (2) according to any one of claims 1 to 15, including the following:

17. ● A step of detecting a second error event corresponding to a complete failure of the third pressure supply unit (90), and ● In the second error event described above, pressure feedback control of individual brake circuits is performed in at least two brake circuits (BK1, BK2), in such a manner that the pressure supply unit (6) and at least two shut-off valves (BP1, TV) of the first module are controlled. BK2 The process of controlling ) The method according to claim 16, including the method described in claim 16.

18. ● A process for detecting non-homogeneous road conditions corresponding to the μ division status. ● A process of controlling the first pressure supply unit (6) in the second error event, in which the wheel brakes (RB1, RB2, RB3, RB4) of selected brake circuits (BK1, BK2) having a higher coefficient of friction compared to other wheel brakes (RB1, RB2, RB3, RB4) in the second error event are used to determine the target brake pressure. The method according to claim 17, including the method described in claim 17.

19. ● A step of detecting a third error event corresponding to a complete failure of the third pressure supply unit (90) and / or a failure of the wheel sensor, ● A step of controlling the first pressure supply unit (6) in a manner in which one-channel ABS is implemented in the third error event, or in a manner in which intermittent braking is implemented in the fourth error event by modulating the pressure between two predetermined pressure levels in at least one of the brake circuits (BK1, BK2). The method according to any one of claims 16 to 18, including the method described in any one of claims 16 to 18.

20. ● A step of determining the first wheel braking pressure on the first wheel brake (RB1, RB2, RB3, RB4) assigned to one of the two brake circuits (BK1, BK2); ● A step of determining the second wheel braking pressure on the wheel brakes (RB1, RB2, RB3, RB4) assigned to the same brake circuit (BK1, BK2), wherein a non-uniform road condition is detected and determined when the first and second wheel braking pressures differ by 30% or more. The method according to any one of claims 16 to 19, including the method described in any one of claims 16 to 19.

Images