Brake system and method for controlling the brake system

Abstract

To provide an improved brake system.SOLUTION: Provided is a brake system including: a first pressure supply unit including an electric driving device configured to supply a pressure medium to at least a first brake circuit and a second brake circuit; a motor pump unit configured to supply a pressure medium to one of the brake circuits; a second pressure supply unit configured to supply a pressure medium to the brake circuit, the second pressure supply unit being connected to the motor pump unit via a first hydraulic line and a second hydraulic line; and a valve unit. At least one of the brake circuits is connected to the second pressure supply unit via a third hydraulic line. The valve unit includes at least one supply valve capable of reversibly partially blocking the third hydraulic line. An isolation valve is arranged in one of the hydraulic lines. As a result, each hydraulic line can be reversibly partially blocked.SELECTED DRAWING: Figure 1

Description

Background Art

[0001] With the trend towards the automation of automobiles, in addition to fault tolerance, the braking system is strongly required to have redundancy with respect to, for example, the generation of braking pressure, the supply of power, and computer functions.

[0002] So-called one-box and two-box systems are generally preferred. The latter consists of an electric brake booster (BKV), a so-called e-booster, and an ESP system (electronic stability control system).

[0003] Known solutions have a relatively long length and / or high weight.

[0004] WO 2011 / 098178 (hereinafter referred to as Variant A or follow-up booster or e-booster) describes such a solution with coaxial drive, in which an electric motor acts on the main cylinder piston (HZ piston) via a transmission and a piston. BKV control is performed via an electric element as a so-called follow-up booster and a reaction disk, and the pedal stroke is a function of the braking pressure and the volume absorption of the braking system, which requires a long pedal stroke in case of fading or failure of the braking circuit.

[0005] ​​​​​International Publication No. 2012 / 019802 presents a similar configuration to International Publication No. 2011 / 098178 with coaxial drive, where an electric motor acts on the HZ piston via a transmission and piston (hereinafter referred to as Modification C). Here, an additional piston cylinder unit is used, which acts on the stroke simulator piston (WS). Thus, the pedal stroke is not affected, for example, by fading and brake circuit failures. However, this increases complexity and structural length.

[0007] German Patent No. 10 2009 033 499 describes a brake booster with an additional ESP unit capable of hydraulically operating the amplifier piston and supplying external pressure (hereinafter also referred to as Modification D). This arrangement, having four or five pistons and six solenoid valves (MVs), is complex and undesirable in terms of length. A non-hydraulic stroke simulator (WS) is located in the piston-cylinder unit upstream of the main cylinder, and this cannot be damped or switched via the solenoid valves (MVs).

[0008] In the event of a BKV motor failure, the above solutions all have redundant brake booster functions, as the pump-equipped ESP unit ensures braking functionality in automatic driving mode, similar to the assist function provided by the vacuum BKV.

[0009] If the ESP motor fails, the ABS can maintain its function through pressure modulation by the BKV motor, as described in International Publication No. 2010 / 088920. However, this only allows for common pressure control across all four wheels and cannot achieve optimal braking distance.

[0010] All known one-box systems incorporate a so-called stroke simulator to achieve advanced pedal stroke characteristics (especially in the case of brake-by-wire systems).

[0011] Known systems with e-boosters and ESPs have only one redundancy in the pressure supply; that is, if the e-booster fails, there is a redundant pressure supply with redundant power supply to the brake booster via the ESP. Higher safety requirements are not considered.

[0012] The assembly of the individual components of a brake system, i.e., the placement of them to form a ready-to-install unit, and the overall volume of that unit, are of great importance. In particular, brake systems used in automobiles designed for semi-autonomous or even fully autonomous driving require consideration of many variations, such as tandem main (brake) cylinders or single main (brake) cylinders. Examples of known assembly variations include arranging the pressure supply unit perpendicular to the axis of the main (brake) cylinder (e.g., described in European Patent No. 2 744 691), or arranging the pressure supply unit parallel to the axis of the main (brake) cylinder (e.g., described in German Patent No. 10 2016 105 232). The latter is characterized in particular by a smaller overall width compared to the assembly variations described first. [Overview of the project] [Problems that the invention aims to solve]

[0013] Purpose of the invention Based on prior art, the object of the present invention is to provide an improved braking system.

[0014] In particular, the present invention relates to a braking system for use in autonomous driving operations (hereinafter also referred to as AD) and / or electric vehicles / hybrid vehicles, and is based on the problem of creating a braking system that has increasingly powerful regenerative power (energy recovery through braking via a generator / or drive motor during generator operation). Weight is preferably reduced, and / or system dimensions are reduced, and / or reliability is improved.

[0015] Preferably, an economical braking system for autonomous driving operations should also be created, which should meet all the necessary redundancy and very high safety requirements.

[0016] Furthermore, in the event of an ESP failure, this braking system achieves both the appropriate function of ABS in terms of braking distance and stability, as well as the appropriate function of regeneration.

[0017] In particular, the object of the present invention is to provide an improved brake system that offers redundant pressure supply, a very wide range of operation, and very high availability, especially in the event of brake circuit failure, while also being very short in length and low in cost. Furthermore, a method is provided that enables very high availability even in the case of partial failure / leakage. [Means for solving the problem]

[0018] Solution by invention This objective is achieved according to the present invention by a brake system having the features of claim 1 and a method having the features of claim 17. Advantageous embodiments, improvements, and modifications are the subject of the dependent claims.

[0019] This objective is achieved, in particular, by a braking system having the following: - A first pressure supply unit having an electric drive device, configured to supply a pressure medium to at least one brake circuit and at least one second brake circuit. - A motor-pump unit configured to supply a pressure medium to at least one of the brake circuits, - A second pressure supply unit configured to supply a pressure medium to at least one of the brake circuits, the second pressure supply unit being connected to a motor-pump unit via at least one first hydraulic line and at least one second hydraulic line, - Valve unit.

[0020] At least one of the brake circuits is connected to a second pressure supply unit via at least one third hydraulic line. The valve unit comprises at least one supply valve capable of at least partially reversibly shutting off the third hydraulic line, and an isolation valve is located on at least one of the hydraulic lines capable of at least partially reversibly shutting off that hydraulic line.

[0021] A pressure supply unit can generally be understood as a unit of a brake system, particularly a structural unit, that supplies brake pressure. Therefore, a pressure supply unit is used to supply a pressure medium to at least one brake circuit.

[0022] Furthermore, the braking system includes a valve unit. In this case, the valve unit is formed as a hydraulic valve unit. Specifically, the valve unit has at least one supply valve formed as a solenoid valve. Solenoid valves have been found to be particularly advantageous due to their simple operation.

[0023] The supply valve can be implemented as a valve in a normally open state. Under normal operation, the supply valve can be closed so that the pressure medium does not reach one of the two brake circuits from the second pressure supply unit. In the event of a system failure, pressure can be applied to the first and / or second brake circuits to enable emergency braking as needed.

[0024] It should be noted at this point that, as with all drive-by-wire systems, the supply valve is critically important for safety. In the event of failure, the pressure generated in the cylinder of the first pressure supply unit, or thereby in the cylinder of the second pressure supply unit, acts to directly counteract the pedal force. By moving the piston of the second pressure supply unit, the first pressure supply unit is deactivated. The driver must then apply the required braking force with the pedal. In a system that merely complies with legal requirements, this corresponds to 500N (equivalent to 40-50 bar). This can frustrate the driver and potentially lead to an accident.

[0025] The solenoid valve in the normally open state used as an isolation valve and a supply valve has a return spring with two connectors. One of the connectors leads to the armature chamber and is referred to herein as the armature chamber connector. The other connector is located behind the valve seat and is hereinafter referred to as the valve seat connector. In the closed state, the pressure of the valve seat connector acts against the magnetic force applied by the valve. However, the valve is designed to withstand the required pressure.

[0026] Preferably, the supply valve is designed and arranged to be reliably closed against the high pressure of the brake system, particularly the first and second brake circuits, in the closed state.

[0027] For this purpose, in one embodiment, the supply valve is indirectly connected to the first hydraulic line via the valve seat connector.

[0028] Here, the expression "at least partially blockable" can be understood to mean that the valve only restricts the volumetric flow (of the pressure medium) through the hydraulic supply line, such as a throttle. Instead of this, or in addition to this, the valve can completely stop the volumetric flow. In this context, the term "reversible" can be understood to mean that the valve can be closed and opened in a controllable manner. For this purpose, at least one valve is preferably designed as a solenoid valve. In a further embodiment, the valve unit has a plurality of valves designed as solenoid valves.

[0029] According to the present invention, at least one isolation valve is provided in the first and / or second hydraulic lines, and through this isolation valve, each hydraulic line can be at least partially reversibly shut off. At least one isolation valve can have the function of hydraulically separating the first and second brake circuits from each other. Therefore, in a failure scenario, it is possible to selectively introduce the pressure medium from the first pressure supply unit to one brake circuit or to both brake circuits. Furthermore, if the first pressure supply unit fails, it is possible to select whether to introduce the pressure medium from the second pressure supply unit exclusively to one brake circuit or to both brake circuits.

[0030] The advantages of the brake system according to the present invention can be seen in its more compact design and shape compared to brake systems of the prior art. In particular, this advantage is achieved by the fact that an additional pressure supply unit and tandem brake cylinder can be eliminated compared to brake systems of the prior art. Furthermore, not only the functional range but also the safety against failure (e.g., as defined by standards) is guaranteed. By making the brake system more compact, the application area of ​​the brake system is advantageously optimized. Application area is understood here to mean, for example, the localized placement of the brake system (e.g., inside an automobile), and also the modular design of the brake system to meet different performance requirements of the brake system.

[0031] In one embodiment, the brake system consists of two hydraulic modules. Preferably, these modules are spatially separated and distinct units connected by two hydraulic lines. These two hydraulic lines form a hydraulic interface. However, it is also possible to integrate both modules into a single structural unit.

[0032] The first module (hereinafter also referred to as "X-Boost") may include a first pressure supply unit having an electric drive, a second pressure supply unit, and a valve device. The second pressure supply unit may be embodied as an operating unit, in particular as a main brake cylinder with a brake pedal.

[0033] In one embodiment, the second module may include an electrically driven motor-pump unit (hereinafter also referred to as the "ESP unit"). The motor-pump unit functions as a pressure source and supplies a pressure medium to at least one brake circuit, preferably both brake circuits.

[0034] The brake system module according to the present invention can be designed to perform the following functions: Module 1 (X-Boost): - Brake boost with variable braking force amplification via evaluation of sensor technology of the operating unit; - Blending during the regeneration of braking energy by the generator or electric drive motor in generator mode; optionally, axle-specific blending if multiple drive motors are used on the front and rear axles; - Emergency braking function (AEB) with highly dynamic pressure increase by the first pressure supply unit; - Control of variable spatial distance for frictionless brakes; - Driver assistance functions such as automatic distance control (DAS); - A secondary or alternative primary system for locking and unlocking an electric parking brake (EPB); - Secondary or primary systems for yaw moment control (ESP, torque vectoring, steering intervention) via target brake circuit intrinsic brake pressure generation; and / or - A secondary or primary system for electric brake force distribution (EBV). Second module (ESP unit): - Anti-lock braking system (ABS); - Anti-slip regulation (ASR); - Electrical braking force distribution (EBV); - Yaw moment control via target wheel specific brake pressure generation (ESP function, torque vectoring, steering intervention); - For example, during fading, amplification of the braking force as a primary system at a pressure higher than the lock pressure; - Brake force amplification as a secondary system through variable brake force amplification based on driver request recognition via evaluation of sensor technology of the operating unit; - A primary system or an alternative secondary system for locking and unlocking an electric parking brake (EPB); - Other features implemented in the ESP unit.

[0035] The braking system is designed specifically for passenger cars. The pressure medium is preferably brake fluid.

[0036] It is known that one component of an electric drive system is a motor sensor for electronically rectifying and controlling the position of the piston of a first pressure supply unit. The electric drive system can be combined with different types of drive systems, for example, via a transmission, particularly via a trapezoidal spindle, or via the spindle of a ball screw drive system.

[0037] According to the present invention, various types of sensors can be used, such as segment sensors equipped with inductive or magnetic field-sensitive sensors, or sensors arranged on a motor or transmission shaft. These have a particularly simple design and typically consist of a target (two-pole or multi-pole magnet) and a magnetic field-sensitive sensor element (Hall sensor, GMR, etc.). These sensors are preferably electrically connected to a motor control unit located in an electric drive unit, sometimes via an intermediate housing. The sensors are preferably housed in a sensor housing on a sensor circuit board.

[0038] In one embodiment, the first isolation valve is embodied as an isolation valve that is normally in an open state.

[0039] At least one second isolation valve can be placed in the second hydraulic line. The second isolation valve can reversibly interrupt the second hydraulic line so that the pressure medium from the first pressure supply unit can enter only the first brake circuit. From the viewpoint of the first pressure supply unit, the first and second isolation valves can select whether the pressure medium from the first pressure supply unit reaches a) exclusively the first brake circuit, b) exclusively the second brake circuit, or c) both brake circuits.

[0040] The arrangement of the second isolation valve is particularly advantageous when combined with the third isolation valve. This third isolation valve can be positioned and designed in the first hydraulic line such that, when the third isolation valve is closed, the pressure medium from the second pressure supply unit flows exclusively into the second brake circuit. According to the present invention, the third isolation valve can be designed and positioned to completely close off the supply to the first brake circuit so that the second brake circuit can be supplied with pressure via the first and / or second pressure supply unit. It should be noted at this point that the terms “first brake circuit” and “second brake circuit” are arbitrarily chosen. The second brake circuit can replace the first brake circuit, and the first brake circuit can replace the second brake circuit.

[0041] In one embodiment, the second isolation valve is positioned such that the valve seat connection portion of the second isolation valve is hydraulically connected to the second brake circuit, and / or The third isolation valve (BP2) is positioned such that its valve seat connection is hydraulically connected to the first brake circuit, and / or The first isolation valve is positioned such that its valve seat connection is hydraulically connected to the second isolation valve and, via the fourth isolation valve, to the first pressure supply unit.

[0042] The first isolation valve and / or the second isolation valve may be a normally open valve according to one aspect of the present invention.

[0043] The second pressure supply unit may include a main cylinder and a piston located within the main cylinder.

[0044] The solution according to the present invention provides a brake system optimized in terms of its overall volume and installation space. At the same time, the flexibility of the modular design of the brake system is advantageously optimized. In one embodiment, the modular design of the brake system is understood to mean a modular design of the brake system using components of different performance and / or variations in the arrangement of components within the brake system in order to meet the different performance and installation space requirements of different automobiles.

[0045] In one embodiment, a stroke simulator is provided that is hydraulically connected to a second pressure supply unit.

[0046] This embodiment is based on the idea that when the driver presses the brake pedal, haptic feedback is output to the driver using a journey simulator.

[0047] In its simplest embodiment, the stroke simulator can be understood as a stroke simulator cylinder containing a stroke simulator piston that is spring-loaded by a spring element positioned between the inner wall and the stroke simulator piston. The stroke simulator cylinder is preferably connected to a second pressure supply unit by a hydraulic line. As the brake pedal is actuated, the stroke simulator cylinder is also supplied with pressure, so that the stroke simulator piston moves against the direction of the spring force of the spring element. Due to the progressive spring force, in one embodiment, the spring force of the spring element indirectly counteracts the force with which the driver actsuates the brake pedal, so the driver feels an increase in pedal pressure.

[0048] Furthermore, in a further development, the stroke simulator can be turned off by a switching valve and is not active when the brake pedal operates along a first range and the force of the brake pedal is determined solely by the return spring. In this context, the first range is understood to mean, for example, the first half of the pedal stroke after the start of operation during braking. In other words, the first range corresponds to, for example, the (stroke) range between the unpressed brake pedal and the half-pressed brake pedal. In the second range, the force of the brake pedal is determined by the return spring and the stroke simulator piston. The second range is understood to be, for example, the second half of the pedal stroke, i.e., the (stroke) range between the half-pressed brake pedal and the fully pressed brake pedal. In particular, the return spring in this case is not a spring element located within the stroke simulator cylinder. Rather, the return spring is an additional spring element, preferably fixed, with one end located in the stroke simulator cylinder and the other end in the stroke simulator piston.

[0049] To further reduce the overall volume of the brake system, as shown in the applicant's International Publication No. 2013 / 072198, which is referenced herein, the volume within the stroke simulator can be reduced, and the return spring can be used instead to correspond only to the flat portion of the pedal stroke characteristic curve, i.e., the portion where a low return force acts on the brake pedal, so as to correspond only to the progressive portion of the characteristic curve.

[0050] For further protection, the stroke simulator may preferably be equipped with redundant seals. According to the present invention, a stroke simulator shut-off valve may be provided. However, the stroke simulator shut-off valve may be omitted.

[0051] In one embodiment, the brake system includes a fourth isolation valve that can reversibly disconnect the first and second hydraulic lines from the first pressure supply unit (simultaneously). The fourth isolation valve can be used to hydraulically isolate the brake circuit, in particular the first and second hydraulic lines, from the first pressure supply unit in the event of failure. This prevents pressure medium that cannot be used to brake the brake circuit from being drawn into the first pressure supply unit. The fourth isolation valve can be designed to be normally closed.

[0052] In one embodiment, the first pressure supply unit has a self-locking transmission to avoid volume loss in the scenario.

[0053] Furthermore, a fourth isolation valve can be used, if necessary, to selectively supply volume from the storage container to one of the brake circuits. For this purpose, the first pressure supply unit draws in volume when the fourth isolation valve is closed.

[0054] The braking system may include at least one pressure relief valve for component protection. In one embodiment, the pressure relief valve may be fluidly connected to a first pressure supply unit, particularly its working chamber. For this overpressure protection, the first pressure supply unit may be designed for 80–100 bar. A more powerful design would require a significantly larger dimension of the first pressure supply unit. At least one pressure relief valve prevents, for example, damage to the first pressure supply unit during ABS operation.

[0055] The isolation valve may be a solenoid valve and / or a two-way valve.

[0056] The first and / or second hydraulic lines may be connected to the storage vessel via their own suction valves. These suction valves are used to quickly replenish the pressure medium, for example, when the motor-pump unit requires more volume. This is particularly advantageous when the motor-pump unit is operating standalone, i.e., when the first pressure supply unit is not available to replenish the volume.

[0057] For redundancy, the second pressure supply unit may also be electrically actuated. In a preferred embodiment, the actuating element is located on the second pressure supply unit. The actuating element is, for example, the brake pedal already described above in the description of the stroke simulator, which can be actuated by the driver of the vehicle. In particular, the actuating element is located on an auxiliary piston of the second pressure supply unit. Thus, the auxiliary piston can be actuated by the actuating element. In other words, when the actuating element, designed as a brake pedal, is actuated, the auxiliary piston is displaced deeper into the main brake cylinder so that the pressure medium is pushed out of the main brake cylinder and therefore out of the second pressure supply unit.

[0058] In one embodiment, the second pressure supply unit includes a (single) main brake cylinder or cylinder having a single piston that can be actuated by an actuating element. Thus, the second pressure supply unit preferably includes a "single-piston cylinder" having only a single operating chamber in which a single piston is held.

[0059] In one embodiment, the second pressure supply unit and / or stroke simulator each have two redundantly designed seal elements. "Redundancy" in this context is understood to mean that each of the two seal elements ensures the liquid-tightness of its corresponding component and, as a result, maintains its function in the event of failure of the other seal element. The seal elements are preferably designed as ring seals.

[0060] According to the present invention, all functionally important seals can be designed redundantly. For example, leaks can be detected during the braking process as part of a diagnostic process. This achieves a high level of safety against "faulty driving."

[0061] In one embodiment, a storage container or reservoir is provided for holding a pressure medium. The storage container is hydraulically connected to a first pressure supply unit and a second pressure supply unit by hydraulic lines. In one embodiment, the storage container is connected to the first hydraulic line and the second hydraulic line via one additional hydraulic line. All or part of the hydraulic lines to the storage container may include suction valves.

[0062] In one embodiment, the storage container further includes a sensor element, in particular a level sensor, designed to detect the filling level of a pressure medium within the storage container. The level sensor may have a float that is positioned in the pressure medium within the storage container, i.e., "floats" in the pressure medium, and generates a sensor signal in response to the filling level of the pressure medium, or causes a (permanent) change in the sensor signal when the filling level of the pressure medium changes.

[0063] In one embodiment, the position of the float can be detected wirelessly. For example, the float may include a magnet, and its position can be detected based on its magnetic field. The associated sensor means includes, for example, one or more magnetic field sensors located on or immediately adjacent to the storage container on a circuit board. In one embodiment, the circuit board is a PCB.

[0064] According to one embodiment, the electric drive unit has redundant three-phase electrical connections. The electric drive unit is controlled through these connections. The drive unit can be controlled according to one of the methods known from the prior art.

[0065] The 2x3 phase connection of the motor in the first pressure supply unit allows for a 50% increase in torque and pressure even in the event of a partial motor failure. This enables the generation of brake pressures up to 40-50 bar, ensuring safe braking of the vehicle even in the event of this partial failure.

[0066] In one embodiment, an elastic element, particularly a spring element, is provided in the wheel brake to return the wheel brake pads. Preferably, the spring element or elastic element acts to cause the brake pads to lift off the brake disc as soon as the pressure in the brake circuit no longer increases (space distance). The spring element can also serve as a (strong) rollback seal for the wheel brake. This has the advantage of eliminating brake pedal backlash.

[0067] The typical friction loss due to brake pads contacting disc brakes is 100-300 watts in a standard braking system, which significantly impacts the range or battery capacity of electric vehicles. Since battery costs are a very significant cost factor in all-electric vehicles, frictionless braking has a very large impact on the overall cost of the vehicle. Frictionless or low-friction braking can be achieved, for example, by a strong rollback seal of the brake pads. This clearance changes with brake pad wear and increases with longer operating times.

[0068] As described, the present invention achieves a compact design for a brake system, particularly a brake booster with a small overall volume, resulting in a very short and slender brake system with redundancy in case of failure of, for example, pressure generation, power supply, and the pump motor of the ABS / ESP unit. Furthermore, even if the ESP unit fails, the ABS function can be activated, albeit with reduced performance. Thus, in emergency situations without ESP, the ABS function exhibits individual control at least per axle to improve braking distance ("select low" pressure control).

[0069] In one embodiment, a first pressure supply unit is arranged with a first piston cylinder unit, and a second pressure supply unit is arranged with the second piston cylinder unit within the housing such that the longitudinal axis of the first piston cylinder unit is substantially perpendicular to the longitudinal axis of the second piston cylinder unit. The longitudinal axes can be located on two adjacent planes. This arrangement allows for the manufacture of a very compact first module. According to the present invention, the substantially perpendicular arrangement may be one in which the axes are offset by up to ±15° compared to a 90° angle. Preferably, the arrangement of the piston cylinder units is such that they are hydraulically separated from one another.

[0070] The above objective can also be achieved by a method of controlling the braking system. The braking system may be one of the braking systems already described above. This method may include the following steps: a) A step of providing a first pressure to a first connection point in order to connect to a first brake circuit; b) The step of providing a second pressure to a second connection point in order to connect to a second brake circuit; c) Steps to detect a fault condition, in particular loss of pressure medium and / or failure of pressure supply; d) In response to the detection of a fault condition, the step of closing at least a first isolation valve to hydraulically disconnect the first pressure supply unit from the first connection point.

[0071] The same advantages as those described above can be obtained in relation to this device.

[0072] The method may include the step of opening a supply valve so that a first connection point is fluidly connected to a second pressure supply unit. The opening of the supply valve may also be in response to the detection of a fault condition.

[0073] Some exemplary embodiments of the present invention are described below in more detail with reference to the figures, which are presented in a partially highly simplified manner. [Brief explanation of the drawing]

[0074] [Figure 1] A schematic circuit diagram of a first exemplary embodiment of a brake system according to the present invention, comprising two isolation valves and one supply valve. [Figure 2] A schematic circuit diagram of a second exemplary embodiment of a brake system according to the present invention, comprising four isolation valves and one supply valve. [Figure 3] A schematic circuit diagram of a modified example of the first exemplary embodiment. [Figure 4] A schematic circuit diagram of a further exemplary embodiment of the brake system according to the present invention. [Figure 5a] A schematic side view of the structural unit of the brake system. [Figure 5b] A schematic side view of the structural unit of the brake system. [Figure 6] Schematic circuit diagram of the ESP unit. [Modes for carrying out the invention]

[0075] Figure 1 shows a schematic circuit diagram of the brake system 2, which includes a first module (called X-Boost) and a second module. The first module, X-Boost, includes a first pressure supply unit 6 equipped with an electric drive unit 8, as well as a second pressure supply unit 14 equipped with an operating element 26 that includes a main brake cylinder 22 and a brake pedal. Furthermore, a valve device equipped with various solenoid valves and check valves is provided.

[0076] The second module comprises an electrically driven motor-pump unit 90 (also called an ESP unit) having a pump with an electric drive device 91, also called a third pressure supply unit. The motor-pump unit 90 may be any ESP unit. A suitable ESP unit is described in detail in German Patent Application Publication No. 10 2014 205 645 A1. Alternatively, a standard ABS unit without ESP functionality may be used as the second module.

[0077] The two modules (X-Boost and ESP unit) are configured to supply pressure medium to two brake circuits BK1 and BK2, where the modules are preferably connected in series hydraulically. In one exemplary embodiment, the X-Boost is mounted on the vehicle's bulkhead, to which the second module (ESP unit) is connected via hydraulic lines at two hydraulic interfaces or connection points (see the thick black dots in Figure 1 in relation to BK1 and BK2).

[0078] The first pressure supply unit 6 is connected to the first brake circuit BK1 or a corresponding interface via the first hydraulic line HL1. Furthermore, a second hydraulic line HL2 is provided for connecting the first pressure supply unit to the second brake circuit or a corresponding interface.

[0079] According to the present invention, the second pressure supply unit 14 of the X-Boost has only one main brake cylinder 22 having a piston 24 and a piston chamber 23. In an exemplary embodiment, the second pressure supply unit 14 is a single-circuit design and is connected to the brake circuit BK1 or the corresponding hydraulic interface via a third hydraulic line HL3 and a supply valve 69. The fluid connection to the second hydraulic line HL2 is connected via a first isolation valve BP1. In normal brake-by-wire operation without defects (e.g., no brake circuit failures), the second pressure supply unit 14 can be isolated from the brake circuits BK1, BK2 by closing the supply valve 69 so that the actuation unit 26 acts only on the stroke simulator 28.

[0080] In the exemplary embodiment shown in Figure 1, brake circuits BK1 and BK2 can be isolated via a first isolation valve BP1 (preferably normally open). According to the present invention, in the event of a failure of the first pressure supply unit 6, the main brake cylinder 22 of the second pressure supply unit 14 can thus be connected to the first brake circuit BK1 only, or to the first and second brake circuits BK1 and BK2 by opening the first isolation valve BP1. For this emergency operation, the supply valve 69 is designed as a normally open valve. If current is still applied, the valve is opened so that the second pressure supply unit 14 is no longer hydraulically disconnected from the brake circuits BK1 and BK2.

[0081] Furthermore, the first pressure supply unit 6 can optionally act on the second brake circuit BK2 (the first isolation valve BP1 is closed), or act on both brake circuits BK1 and BK2 (the first isolation valve BP1 is open or always open). In normal operation, the first isolation valve BP1 is open, so 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 supply valve 69. If it is determined that volume is being lost from the brake circuits BK1 and BK2, the first isolation valve BP1 can disconnect the brake circuit BK1 from the first pressure supply unit 6, so that if a leak occurs in the first brake circuit BK1, the second brake circuit BK2 can be kept operating to prevent loss of hydraulic fluid.

[0082] In an exemplary embodiment, the first isolation valve BP1 is embodied as a solenoid valve, and the ball seat of the isolation valve BP1 is connected via a connector (valve seat connector) to the portion of the hydraulic line that connects to the first pressure supply unit 6. This means that the first isolation valve BP1 can be reliably closed by energization even if the first brake circuit BK1 fails, and will not be forcibly opened by higher pressure during the operation of the first pressure supply unit 6.

[0083] The second pressure supply unit 14 supplies pressure to the stroke simulator 28 through an expansion hole in the wall of the main cylinder 22 when the actuating element 26 is actuated, so that a progressive tactile resistance in the form of a restoring force can be felt as a function of the magnitude of the actuation of the actuating element 26. In this context, the magnitude of the actuation is understood to be how "firmly and / or how far" the driver acts the actuating element 26, which is configured as a brake pedal, and as a result pushes the piston 24 into the main brake cylinder 22. The progressive tactile resistance is also called pedal characteristics.

[0084] A process simulator valve 29 may be provided to block the connection to the process simulator 28 (shown in Figure 1).

[0085] The second pressure supply unit 14 has at least one expansion bore 38, which is connected to the storage container 40 via a hydraulic line. The storage container 40 is also part of the brake system 2.

[0086] In an exemplary embodiment, a check valve RVHZ can be positioned in the hydraulic line between the expansion bore and the storage container 40, similar to the throttle DR. This check valve RVHZ, similar to the first pressure supply unit 6, allows for the diagnosis of the storage condition of the seal elements located in the first pressure supply unit 6, similar to the stroke simulator 28. When testing the seal of the main brake cylinder 22, the stroke simulator valve 29 (if present) can be closed.

[0087] As shown, the main brake cylinder 22 has two sealing elements 42a and 42b, which are ring seals. The expansion bore 38 is located between the two sealing elements 42a and 42b. The throttle DR is located at the connection between the expansion bore 38, located between the two sealing elements 42a and 42b, and the reservoir 40.

[0088] The throttle DR flow rate is sized so that the pedal characteristics do not change significantly even if the seal element 42a fails (3 mm pedal stroke in 10 seconds). In addition, volume compensation related to the temperature of the pressure medium can be performed via the throttle DR.

[0089] During ABS operation of the motor-pump unit 90, high-pressure peaks occur in the brake circuits BK1 and BK2, which can place a considerable load on the first pressure supply unit 6. In the modified example shown in Figure 1, the pressure relief valve UeV is connected to the piston chamber of the first pressure supply unit 6 via a bore, thereby reducing the high-pressure peaks and preventing damage to the system.

[0090] The suction valve NV is also fluidly connected to the piston chamber of the first pressure supply unit 6, allowing for replenishment of the pressure medium from the storage container 40. Thus, the first pressure supply unit 6 can independently introduce additional pressure medium into the brake circuits BK1 and BK2. In addition, an additional expansion 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.

[0091] The motor-pump unit 90 is shown schematicly in Figure 1 only. It ultimately supplies four wheel brakes RB1, RB2, RB3, and RB4. In the schematic diagram, wheel brakes RB1 and RB2 work for the vehicle's front axle VA, and wheel brakes RB3 and RB4 work for the vehicle's rear axle HA. The rear axle HA houses the electric motor for driving the vehicle. The vehicle may be an all-electric vehicle or a hybrid vehicle.

[0092] 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. In the hydraulic configuration shown in Figure 1, the corresponding assignments are advantageous.

[0093] Furthermore, the motor-pump unit 90 includes a control unit 95 ("ECU-ESP").

[0094] Similarly, the second pressure supply unit 14 has a circuit board (PCB) that includes a level sensor NST for sensing the position of a magnetic float NS in the storage container 40. The PCB further includes sensors 30a, 30b for sensing the pedal stroke and the stroke difference between the piston 24 and the pedal stroke.

[0095] To supply additional pressure medium to the motor-pump unit, a suction valve 70b is provided in the first brake circuit BK1, and the pump of the motor-pump unit 90 is connected to the storage container 40.

[0096] If the pump of the motor-pump unit 90 requires a pressure medium for the second brake circuit BK2, this can be supplied from the storage container 40 via the suction valve 70c.

[0097] Therefore, the two brake circuits BK1 and BK2 are connected to the storage container 40 via suction valves 70b or 70c, respectively, for drawing in the pressure medium, by their respective hydraulic lines HL1 and HL2. To achieve optimal suction of the pressure medium, the suction valve 70c preferably has a diameter in the range of 30 mm to 50 mm, and particularly a diameter of 40 mm.

[0098] Optionally, in this exemplary embodiment, the spatial distance between the brake pads and the disc brake is controlled. The wheel brakes RB1, RB2, RB3, RB4 (see Figure 1) can be designed as frictionless wheel brakes RB1, RB2, RB3, RB4. In a brake-by-wire system, frictional resistance can be reduced by a disc brake with brake pads spaced apart by a spatial distance without pressure within the brake system. This can be achieved by using a rollback seal, a return spring, or by generating negative pressure to actively retract the brake pads. European Patent Application Publication 2225133 A2 describes the possibility of generating the corresponding negative pressure by a first pressure supply unit 6, which is expressly incorporated with respect to this disclosure.

[0099] By using the first pressure supply unit 6 to evaluate the pressure curve, the spatial distances of the wheel brakes RB1, RB2, RB3, and RB4, which change during operation, can be measured individually for each wheel or brake circuit. According to the present invention, the corresponding measurements can be performed not only during maintenance but also while the vehicle is in operation. Preferably, the measurements are performed when the vehicle is stationary or after braking.

[0100] Using the known spatial distance values ​​of the wheel brakes RB1, RB2, RB3, and RB4, when the wheel brakes RB1, RB2, RB3, and RB4 are activated, the spatial distance is quickly overcome by the piston stroke control of the first pressure supply unit 6. In this respect, it is preferable to use a brushless motor with a small time constant as the electric drive device 8 of the first pressure supply unit 6, as this allows the spatial distance to be overcome without the driver noticing when braking.

[0101] Furthermore, the brake system 2 can be controlled so that the vehicle's electric motor TM1 acts in phase with respect to spatial distance. Therefore, the braking effect occurs immediately when the brakes are applied.

[0102] In one exemplary embodiment of the present invention, differences in the spatial distances of the wheel brakes RB1, RB2, RB3, and RB4 are compensated by controlling the inlet valves of a second module (ESP unit) and / or by using electric motors on one or more axles to generate a braking effect to initiate braking. This spatial distance can generally be used to reduce or avoid the stick-slip effect of the new braking system at low speeds.

[0103] In one exemplary embodiment, the brake system 2 according to the present invention performs stutter braking in the event of a failure of the ESP unit. By moving the piston of the first pressure supply unit 6 back and forth between an upper pressure range and a lower pressure range, wheel lock-up is avoided and steering performance is maintained.

[0104] In one exemplary embodiment, one-channel ABS operation is performed additionally or alternatively. For this purpose, measurement signals such as pressure and wheel speed can be read via the interface of the ESP unit to the control unit 95.

[0105] Automated stutter braking provides sufficient braking distance (approximately 200% of the braking distance with ABS compared to full wheel-specific ABS) and acceptable stability by maintaining steering control. In conventional braking systems that provide this emergency function (International Publication No. 2011 / 098178), the actuation via the brake pedal acts directly on the piston of the main brake cylinder, which moves back and forth during the stutter braking function, so the actuation of the pedal can cause the wheel to lock.

[0106] In the brake system according to the present invention, the brake pedal, according to one aspect of the present invention, acts only on the piston 24 and is isolated from the brake circuits BK1 and BK2 via the supply valve 69, thus eliminating the shortcomings of conventional systems and providing this emergency function. Therefore, in the brake system according to the present invention, the function of the automated stutter brake is not interrupted by the driver.

[0107] Instead of, or in addition to, stutter braking, single-channel ABS operation can be implemented with select-low control. This further worsens the braking distance (approximately 400% of the braking distance with full wheel-specific ABS), but does not limit vehicle stability. According to the present invention, measurements for 1-channel ABS operation, such as pressure and wheel speed, can be read by the ESP unit 95 via an interface, such as a CAN interface.

[0108] As shown in Figure 1, to further enhance the availability of the brake system 2 according to the present invention, the electric drive unit 8 of the first pressure supply unit 6 is connected to the X-Boost control unit 9 (ECU DV) via two redundant three-phase strings, and the electronics are (partially) redundant. For example, two B6 bridges can be provided for each string. Furthermore, in at least one exemplary embodiment, the electronics are connected to two redundant power supplies. In this way, the failure probability of the electric drive unit 8 can be reduced to 1 / 4 to 1 / 10, and the failure condition (failure of the first pressure supply unit 6) can be further significantly reduced.

[0109] The control unit of the ESP unit 95 and the control unit 9 (ECU DV) of the X-booster are communicated via a CAN bus. This allows control commands to be sent to the motor-pump unit 90 to trigger the operation of the drive unit 91 and / or the valves provided (see also Figure 6).

[0110] The braking system 2 shown in Figure 1 can achieve the following safety-related redundancy: - In the event of a brake circuit failure, 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 (simultaneously), sufficient braking effect to meet legal requirements must be ensured; that is, legal requirements must be met even in the case of a double failure: o Failure Situation 1 - Failure of the third pressure supply unit (motor-pump unit 90): Deceleration due to brake boost via the first pressure supply unit 6 in both brake circuits BK1 and BK2; o Failure Situation 2 - Failure of the third pressure supply unit and brake circuit BK1: For example, deceleration due to brake boost via the first pressure supply unit 6 on the rear axle; o Failure Situation 3 - Failure of the third pressure supply unit and the second brake circuit BK2: For example, deceleration by the second pressure supply unit 14 on the front axle (the first isolation valve BP1 is closed) o Failure Situation 4 - Failure of the first pressure supply unit 6: Deceleration due to brake boost via the third pressure supply unit; o Failure Situation 5 - Failure of the first pressure supply unit 6 and the first brake circuit BK1 or the second brake circuit BK2: Deceleration by brake boost in one of the brake circuits BK1 or BK2 via the third pressure supply unit (if applicable, assisted by the vehicle electric motor TM1 on one axle); o Failure Condition 6 - Failure of the first pressure supply unit 6 and the third pressure supply unit: Braking by the main brake cylinder of the front axle VA, and optionally braking by the drive electric motor of the rear axle HA; o Failure Situation 7 - Vehicle electrical system failure: Braking by the second pressure supply unit 14 on the front axle VA and rear axle HA as needed; - Electronic brake force distribution (EBV) in case of ESP unit failure. This is achieved by closing the first isolation valve BP1, generating pressure in the first brake circuit BK1 via the third pressure supply unit, generating pressure in the second brake circuit BK2 via the first pressure supply unit 6, and controlling the first pressure supply unit 6 via the sensor of the second pressure supply unit 14. This requires the division of the S / W brake circuit, namely, the wheel of the front axle VA is connected to the first brake circuit BK1, and the wheel of the rear axle HA is connected to the second brake circuit BK2; - Controlling the spatial distance between the brake pads and the disc brake; - Activation of 1-channel ABS or implementation of automatic stutter braking.

[0111] Figure 2 shows an alternative embodiment of the X-booster according to Figure 1. In contrast to the exemplary embodiment in Figure 1, Figure 2 includes a second isolation valve TVBK2 in the second hydraulic line HL2. This second isolation valve TVBK2 allows the second brake circuit BK2 to be hydraulically disconnected from the first pressure supply unit 6. Therefore, the first pressure supply unit 6 can selectively supply pressure medium to the first brake circuit BK1, to the second brake circuit BK2, or to both brake circuits. If volume loss is detected in the second brake circuit BK2, it can be disconnected.

[0112] Furthermore, the exemplary embodiment shown in Figure 2 differs in that a third isolation valve BP2 is provided in the first hydraulic line between the connection point of the first isolation valve BP1 and the first brake circuit BK1. Preferably, the third isolation valve BP2 is positioned such that the third hydraulic line opens into the first hydraulic line HL1 at the hydraulic connection between the first isolation valve BP1 and the third isolation valve BP2. The third isolation valve BP2 makes it possible to hydraulically isolate the first brake circuit BK1 from both the first pressure supply unit 6 and the second pressure supply unit 14. Therefore, when the first pressure supply unit 6 fails, it is possible to supply pressure medium from the second pressure supply unit 14 to the second brake circuit via the supply valve 69, the first isolation valve BP1, and the second isolation valve TVBK2. When the third isolation valve BP2 is closed, no pressure medium is supplied to the first brake circuit.

[0113] The brake system 2 shown in Figure 2 can achieve the following safety-related redundancy: - To ensure sufficient braking effect in the event of failure of one or more pressure supply units. o Failure conditions 1-7: Refer to Embodiment 1; o Failure Situation 8 - Failure of supply valve 69 (e.g., leak) or electrical control failure: The isolation valves BP1 and BP2 close the third hydraulic line HL3, allowing the stroke simulator to be fully activated; the first pressure supply unit 6 and ESP unit set the wheel brake pressure; o Further degree of freedom: In the event of a brake circuit failure, pressure from the main brake cylinder can be optionally supplied to either brake circuit BK1 or BK2. - Electronic brake boost (EBV) in case of ESP unit failure. This is achieved by generating pressure in the brake circuit BK1 via the second pressure supply unit 14, by generating pressure in the brake circuit BK2 via the first pressure supply unit 6 when the first isolation valve BP1 is closed, and by controlling the pressure supply via the sensor system of the second pressure supply unit 14. This requires the division of the S / W brake circuit, and the distribution of braking force to the brake circuit is controlled via the isolation valves BP1, BP2, and TVBK2. According to the present invention, the piston of the first pressure supply unit 6 can control the movement of its forward and return strokes to apply appropriate pressure. Optionally, pressure adjustment can be performed via PWM control of the valves, particularly the isolation valves; - The 2-channel ABS system switches between "Select Low" control (where the wheel lock pressure of the wheel with the worse grip for each brake circuit determines the set pressure) and "Select High" control (where the wheel lock pressure of the wheel with the better grip for each brake circuit determines the set pressure) depending on the road surface conditions. - Spatial distance control has already been implemented in the exemplary embodiment shown in Figure 1. The exemplary embodiment shown in Figure 2 provides an additional possibility for compensating for the uneven spatial distances of the wheel brakes RB1, RB2, RB3, and RB4 in the brake circuits BK1 and BK2 by performing appropriate pre-control before the brake booster operation by sequentially opening the isolation valves BP1 and TVBK2. Alternatively, it is also possible to use PWM operation to set different flow cross-sections to the brake circuits BK1 and BK2 so that the uneven spatial distances can be compensated for simultaneously. Here, splitting the S / W brake circuit is suitable. This method is easily implementable because the brake circuit isolation valves are part of the X-Boost module and can be implemented without being affected by time delays or errors (e.g., using an interface between the X-Boost and the ESP unit). For example, the brake system can be designed so that there is no spatial distance for the brake pads on the front axle and there is a spatial distance for the rear axle. Thus, even if the first pressure supply unit 6 fails, the operating unit generates pressure according to the present invention and acts on the wheel brakes RB1, RB2, RB3, and RB4 of the front axle VA, without causing a delay in braking. Furthermore, a greater braking effect can be generated at the front axle VA.

[0114] Figure 3 shows a modified example of the exemplary embodiment shown in Figure 1, where the brake circuit has been replaced. It will be apparent to those skilled in the art that the same advantages already described in relation to the exemplary embodiments of Figures 1 and 2 can be achieved in the corresponding modifications of the present invention.

[0115] Figure 4 shows a schematic circuit diagram of a further exemplary embodiment of the brake system 2 of the present invention, which comprises a first pressure supply unit 6 having an electric drive unit 8 and a transmission, and a motor-pump unit 90, which is schematically shown only by a rectangle in Figure 4.

[0116] The brake system 2 further comprises a second pressure supply unit 14. The second pressure supply unit 14 is described in detail in the present applicant's application no. PCT / EP2018 / 072363, which is referenced hereto.

[0117] Similar to the exemplary embodiment shown in Figure 1, the second pressure supply unit 14 includes a main brake cylinder 22 and a piston 24. An actuation element 26 is positioned on the piston 24, which is only partially shown in Figure 4 and is designed, for example, as a brake pedal.

[0118] Furthermore, the brake system 2 shown in Figure 4 has a stroke simulator 28 that is hydraulically connected to the second pressure supply unit 14.

[0119] Sensors 30a and 30b detect the stroke of the brake pedal and the difference in stroke between the actuating element 26 and the piston 24. The actuating element 26 acts on the piston 24 via a spring element. Sensors 30a and 30b are preferably integrated into a second pressure supply unit 14, which is part of the pedal interface there, and is not described in more detail here.

[0120] The signals generated by sensors 30a and 30b include information about the differential stroke and therefore include a control signal for the first pressure supply unit 6, the latter of which applies pressure medium to the first brake circuit BK1 and the second brake circuit BK2 as a function of the signals generated by sensors 30a and 30b. Alternatively or additionally, the two brake circuits BK1 and BK2 are supplied with pressure medium located inside the main brake cylinder 22. Thus, in this exemplary embodiment, the second pressure supply unit 14 is configured such that the two brake circuits BK1 and BK2 are supplied with pressure medium at least indirectly.

[0121] Furthermore, when the actuating element 26 is actuated, the second pressure supply unit 14 supplies pressure to the stroke simulator 28 through an expansion hole in the wall of the main brake cylinder 22, allowing the driver to feel a progressive tactile resistance in the form of a restoring force as a function of the magnitude of the actuating element 26. In this context, the magnitude of the actuating element is understood to be how "firmly and / or how far" the driver actsuating the actuating element 26 in the form of a brake pedal, thereby pushing the piston 24 into the main brake cylinder 22. The progressive tactile resistance is also called the pedal characteristic.

[0122] Furthermore, the second pressure supply unit 14 includes a spring 36, one end of which is positioned on the piston 24 and the other end of which is positioned on the main brake cylinder 22. The spring 36 may also be part of the spring characteristics of the stroke simulator 28, and therefore may be part of the pedal characteristics.

[0123] The second pressure supply unit 14 has at least one, in this exemplary embodiment, two, expansion bores 38, which are connected to the storage vessel 40 via a hydraulic line. The storage vessel 40 is also part of the brake system 2 in the exemplary embodiment shown in Figure 4.

[0124] In one embodiment, a check valve RV (not shown) may be placed in the hydraulic line between the expanded bore 38 and the storage container 40. Furthermore, such a check valve RV (not shown) may also be placed in the hydraulic line between the first pressure supply unit 6 and the storage container 40. The check valve RV and the first pressure supply unit 6 make it possible to diagnose the storage condition of the seal elements placed in the first pressure supply unit 6 and the stroke simulator 28.

[0125] Furthermore, the main brake cylinder 22 has two sealing elements 42a and 42b that are redundant to each other and designed as a ring seal. One of the two expansion bores 38 is located between the two sealing elements 42a and 42b. A throttle DR is located at the connection between the expansion bore 38 located between the two sealing elements 42a and 42b and the reservoir 40.

[0126] The throttle DR is dimensionally designed with respect to its flow rate so that the pedal characteristics do not change significantly if one of the two sealing elements 42a and 42b fails (3 mm pedal stroke in 10 seconds). Furthermore, volume compensation related to the temperature of the pressure medium can be performed via the throttle DR.

[0127] In the exemplary embodiment shown in Figure 4, as in Figures 1 and 2, the brake system 2 is designed redundantly in the event of a failure of the first pressure supply unit 6. Therefore, in the event of a failure of the first pressure supply unit 6 related to the braking process, the ABS / ESP unit 90 takes over, drawing pressure medium from the storage container 40 using the pump P and supplying it to the brake circuits BK1 and BK2. In other words, the pump P of the ABS / ESP unit 90 takes over the function of the brake booster, at least as an alternative, in the event of a failure of the first pressure supply unit 6. For this reason, hydraulic lines HL1 and HL2 are hydraulically connected to the storage container 40 via hydraulic lines.

[0128] The first pressure supply unit 6 has a piston 44, which has an expansion hole 46. The pressure medium is drawn in through a hydraulic line (partially shown in Figure 4) to which the first pressure supply unit 6 is connected to the storage container 40.

[0129] The dimensions of the first pressure supply unit 6 can be alternating so that one full stroke of the piston 44 corresponds to the volume acquired by one of the two brake circuits BK1 and BK2.

[0130] Furthermore, the first pressure supply unit 6 can be manufactured to correspond to or reduced in volume (piston and stroke).

[0131] Pressure increases and / or decreases in the first brake circuit BK1 and the second brake circuit BK2 are performed via a control unit 9, to which signals from pedal stroke sensors 30a and 30b are transmitted. The electric drive unit 8 is then controlled by the control unit 9 in accordance with the transmitted signals. The control unit also has a signal input section (not shown) for receiving signals from pedal stroke sensors 30a and 30b. Furthermore, the control unit has two connection sections (also not shown) for supplying electricity to the vehicle's electrical system.

[0132] Typically, the first pressure supply unit 6 delivers a volume with a pressure in the range of 80 to 120 bar to the brake circuits BK1 and BK2. This pressure range substantially corresponds to the wheel lock limit; that is, higher pressures will lock the wheels. Nevertheless, if higher pressure is required, the pump P of the ABS / ESP unit 90 is turned on, generating a pressure increased to approximately 200 bar. However, this increased pressure is carried out with correspondingly lower power and therefore more slowly than the pressure increase by the first pressure supply unit 6. This is acceptable because the pressure increase up to 200 bar is only relevant to fading cases and does not need to be carried out as quickly as the pressure increase up to the lock limit (for example, to perform emergency braking functions). Therefore, the pump P of the ABS / ESP unit 90 is preferably designed for 200 bar, and the first pressure supply unit 6 is preferably designed for 80 to 120 bar.

[0133] If the first pressure supply unit 6 fails during the braking process, the piston 44 is pushed back under pressure, thereby completely reducing the braking pressure. Such a pressure reduction is not possible if a self-locking transmission is used for the piston 44 (for example, in the form of a trapezoidal spindle with a plastic nut). In this case, the first brake circuit BK1 is provided with a normally closed solenoid valve (not shown) connected to a reservoir.

[0134] Furthermore, the brake system 2 has a valve unit 50, which is positioned between the second pressure supply unit 14 and the ABS / ESP unit to the motor-pump unit 90, and is connected in particular by a hydraulic line. In addition, the first pressure supply unit 6 is connected to the valve unit 50. Thus, the valve unit 50 acts as a distributor, enabling the flow of the pressure medium as already described above. The valve unit 50 also has a check valve (not shown here for simplicity) and a pressure sensor.

[0135] The auxiliary piston chamber 23 of the second pressure supply unit 14 is connected to the motor-pump unit 90 via a valve 69 and a hydraulic supply line HL3. Specifically, downstream of the valve 69, there are two hydraulic lines, HL1 and HL2, connected in parallel to each other, and these are connected to the motor-pump unit 12. In other words, the hydraulic supply line HL3 downstream of the valve 69 branches into the first hydraulic line HL1 (which constitutes part of the first brake circuit BK1) and the second hydraulic line HL2 (which constitutes part of the second brake circuit BK2). Furthermore, valves TV1 and TV2 are provided in the first hydraulic line HL1 and the second hydraulic line HL2, respectively, and these valves can at least partially reversibly shut off the first hydraulic line HL1 and the second hydraulic line HL2.

[0136] To increase the suction force of the pump P of the brake circuit BK1 of the motor-pump unit 90, a suction valve 70b is provided that connects the pump P of the brake circuit BK1 of the motor-pump unit 90 to the storage container 40. The motor-pump unit 90 can also draw pressure medium from the storage container 40 via the first hydraulic line HL1, valve 69, hydraulic supply line HL3, auxiliary piston chamber 23, and expansion bore 38. The suction force of the pump P of the brake circuit BK1 of the motor-pump unit 90 is also not reduced by the hydraulic flow resistance of valve TV1 or valve combination TV1 / TV11.

[0137] The suction force when the pump P of the motor-pump unit 90's brake circuit BK2 draws pressure medium from the storage container 40 via valve TV2, hydraulic line HL2, valve 69, and auxiliary piston chamber 23 is mainly determined by the hydraulic flow resistance of valve TV2. To increase the suction force of the pump P of the motor-pump unit 90's brake circuit BK2, a suction valve 70c is provided that connects the second hydraulic line HL2 to the storage container 40. The pump P of the motor-pump unit 90's brake circuit BK1 can also draw pressure medium from the storage container 40 via the second hydraulic line HL2 and the suction valve 70c.

[0138] Furthermore, a fourth hydraulic line HL4 branches off from the first hydraulic line HL1. The fourth hydraulic line HL4 hydraulically connects the first brake circuit BK1 and the first pressure supply unit 6. A fourth isolation valve 74 is located within the fourth hydraulic line HL4, which allows the hydraulic connection between the first brake circuit BK1 and the first pressure supply unit 6 to be disconnected at least partially in a reversible manner. If leakage occurs in the pressure relief valve 80, the fourth isolation valve 74 can be closed to prevent the brake circuit BK1 from failing.

[0139] The essential feature of the brake system 2 shown in Figure 4 is that it eliminates the need for additional pressure supply units. Therefore, the brake system 2 has only a first pressure supply unit 6 and a second pressure supply unit 14 that supply pressure medium to the two brake circuits BK1 and BK2.

[0140] In the fallback option, when the first pressure supply unit 6 fails, the second pressure supply unit 14 can be switched to one or both brake circuits BK1 and BK2 via valves TV1 and TV2, thereby supplying pressure medium to one or both brake circuits BK1 and BK2 by the second pressure supply unit 14. When the control unit 9 fails, both brake circuits BK1 and BK2 become active.

[0141] Figures 5a and 5b show one way in which the individual components of the X-booster, in particular the first and second pressure supply units 6 and 14, and the associated valves, in particular the isolation valves 74, PD1, BP1, TV1, BP2, TVBK2, and TV2, can be arranged within the housing.

[0142] Figures 5a and 5b show a simplified representation of the basic elements of an assembly comprising an electric drive unit 8, a second pressure supply unit 14, an HCU block 114 with a main brake cylinder 22 in particular, a first pressure supply unit (ECU), a storage container 40, and other components (SH2, motor sensor, and motor sensor housing).

[0143] The first pressure supply unit 6, as shown in Figure 1, includes an electric drive unit 8, for example, a spindle drive unit, and a piston housing 108. The piston housing 108 is attached to the HCU block 114 via a screw connection 101.

[0144] The spindle drive unit, equipped with piston 24, is located within the HCU block 114. According to the present invention, the piston stroke of the first pressure supply unit 6 can be very small. This is because the dimensions of the electric drive unit 8 are designed for both low pressure levels, e.g., 120 bar, and correspondingly small volumes. Higher pressure levels and additional volumes can be provided by the ESP unit. The valves necessary for the above functions are also integrated into the HCU block 114.

[0145] Furthermore, the HCU block 114 has an SH2 connected to the actuation element 26 integrated into it. The HCU block 114 is connected to a mounting flange 102, which is bolted to the end wall 104 of the brake booster with mounting bolts 103.

[0146] The HCU block 114 is fitted with a control unit 9 (ECU) equipped with a housing 113.

[0147] The plug connector ST of the control unit 9 (ECU) is connected to the PCB. The PCB also has a level sensor NS mounted on it. The level sensor NS is designed to measure linearly to detect even minute leak flow rates. This sensor detects the magnetic float NS or its position within the storage vessel 40. If the highest level of safety is required, the level sensor NS can also be designed to be redundant. A prerequisite for the described exemplary embodiment (without the plug connector) is the corresponding arrangement of the storage vessel 40 behind the PCB (with respect to the image plane of Figure 5b). This arrangement allows for a very short overall length, which is advantageous in the event of a head-on collision.

[0148] The hydraulic connection line 105 to the ESP unit for the brake circuits BK1 and BK2 can be mounted on the motor side or the front side, preferably at an angle of about 45°. This facilitates assembly.

[0149] The plug connector ST is located above the HCU block 114. In the illustrated exemplary embodiment, the stroke simulator housing 117 is formed separately and is not integrated with the HCU block 114. Instead, a screw connection is provided to allow adjustment of the position of the stroke simulator 28. This saves volume in the HCU block 114.

[0150] In one aspect of the present invention, first and second pressure supply units 6 and 14 are arranged substantially perpendicular to each other within the described housing. Due to the orientation of the pistons of the pressure supply units 6 and 14, they have directions of extension designated in Figures 5a and 5b as L6 (the longitudinal axis of the first pressure supply unit 6) and L14 (the longitudinal axis of the second pressure supply unit 14). These two axes L6 and L14 are orthogonal to each other in the illustrated exemplary embodiment, thereby enabling a very compact arrangement of the pistons. As can be seen from Figures 5a and 5b, the longitudinal axes L6 and L14 are not coplanar but are located on two parallel, offset planes. Mapping the longitudinal axes L6 and L14 to a common plane results in a perpendicular course. The offset can range from 1 to 15 cm.

[0151] Figure 6 is a schematic circuit diagram of an ESP unit with a motor-pump unit 90 for use in the brake system 2 according to the present invention. The ABS / ESP unit is known to include a main component pump P with a motor 91, valves HSV1 and HSV2, USV1 and USV2, inlet valves EV and outlet valves AV associated with wheel brakes RB1, RB2, RB3, and RB4, and a reservoir chamber (SpK). This system has been described in numerous publications and patent applications. This system is already on the market as an e-booster and is mainly used in electric and hybrid vehicles. This is because, in this system, the control of the brake system is performed in cooperation with the braking torque of the generator, i.e., regenerative.

[0152] In one exemplary embodiment of the present invention, the ESP unit may have a bidirectional valve HSV1 that, in the event of failure, bypasses the pump P and releases pressure from the wheel brakes RB3, RB4 through this valve HSV1. This design is particularly advantageous when used in combination with selective pressure control in the brake circuits BK1, BK2.

[0153] In particular, in one aspect of the present invention in this embodiment, the control unit 9 is connected to the control unit 95 of the ESP unit ("ECU-ESP") in a communicative manner, and in order to realize the safety aspects already described, at least the acquisition valve and the outlet valve AV may be controllable by the control unit 9.

[0154] By saving on the pressure supply unit, for example, further cost reductions can be achieved compared to the embodiment of brake system 2 described in the prior art.

[0155] At this point, it should be noted that all the components described above, individually—even if their features are not additionally described in a particular context—are considered independent embodiments or further developments of the invention as defined in the introduction, description, and claims, particularly in the description and in the claims, even if they are not individually explicitly identified as optional features in a particular context, for example, by the use of words such as: particularly, preferably, for example, e.g., and possibly, by the use of parentheses, etc. Deviating from this is possible. Specifically, it should be noted that the word “particular” or parentheses does not indicate features that are essential in a particular context. [Explanation of symbols]

[0156] List of reference codes 2 Brake System 6. DV1 First pressure supply unit 8 Electric drive unit 9. Control Unit (ECU) 10 Transmission 14. BE Second Pressure Supply Unit 22 Main brake cylinder 23 Piston Chamber 24 pistons 26 Actuating elements 28. WS Itinerary Simulator 28a, 28b Seal elements of the process simulator 29 Stroke simulator valve 30a, 30b Pedal stroke sensor 32-stroke simulator piston 34. Spring elements of the stroke simulator 36 springs 38 Expansion hole of the second pressure supply unit 40. VB Storage Container 42a, 42b Auxiliary piston seal elements 44 Piston of the first pressure supply unit 46 Expansion hole of the piston of the first pressure supply unit 48 Control Unit 50 valve unit 62 Sensor Elements 69. FV supply valve 70b, 70c, 80d, RV1, RV2, NV Suction valve 74. PD1 Fourth isolation valve 80. UeV pressure relief valve 90. DV2 Motor-Pump Unit 91 Drive unit 95 ESP Unit Control Unit 101 Screw connection part 102 Mounting flange 103 Mounting bolts 104 End wall 105 connection lines 108 Piston Housing 110 Sensor Elements 113 Control Unit Housing 114 HCU Blocks 117 Process Simulator Housing B1, B2 Electrical connection (3 phase) P Pump M Motor BP1, TV1 First isolation valve TVBK2, TV2 Second Isolation Valve BP2 Third isolation 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 L6 Longitudinal axis of the first pressure supply unit L14 Longitudinal axis of the second pressure supply unit VA front axle HA rear axle TM1 Vehicle Electric Motor RVHZ Check Valve CAN CAN bus ST Plug Connector NS Float NST Level Sensor HSV1, HSV2, USV1, USV2 ESP Unit Valves AV exit valve EV Inlet Valve SpK Storage Room

Claims

1. Brake system (2), - A first pressure supply unit (6) comprising an electric drive device (8) configured to supply a pressure medium to at least one first brake circuit (BK1) via a first hydraulic line (HL1) and to supply a pressure medium to at least one second brake circuit (BK2) via a second hydraulic line (HL2), - A motor pump unit (90) configured to supply the pressure medium to at least one of the first and second brake circuits (BK1, BK2), - comprising a valve unit (50), A first isolation valve (BP1, TV1) is positioned in the first hydraulic line (HL1), thereby enabling the first hydraulic line (HL1) to be at least partially reversibly shut off. A second isolation valve (TV2, TVBK2) is positioned in the second hydraulic line (HL2), thereby enabling the second hydraulic line (HL2) to be at least partially reversibly shut off. The brake system (2) is adapted to control the first isolation valve (BP1, TV1) and the second isolation valve (TV2, TVBK2) such that pressure from the first pressure supply unit (6) is selectively supplied to the first brake circuit (BK1), the second brake circuit (BK2), or both brake circuits. The system further comprises a second pressure supply unit (14) configured to supply the pressure medium to at least one of the first and second brake circuits (BK1, BK2), the second pressure supply unit (14) being connected to the motor-pump unit (90) via at least one first hydraulic line (HL1) and at least one second hydraulic line (HL2), at least one of the first and second brake circuits (BK1, BK2) being connected to the second pressure supply unit (14) via at least one third hydraulic line (HL3), and the valve unit (50) comprising at least one supply valve (FV, 69) capable of at least partially reversibly shutting off the third hydraulic line (HL3), The first hydraulic line (HL1) and / or the second hydraulic line (HL2) are connected in each case to a reservoir (40) via suction valves (70b, RV1, 70c, RV2), The reservoir (40) includes a sensor element (62), which is configured to detect the filling level of the pressure medium in the reservoir (40). Brake system (2).

2. The third hydraulic line (HL3) and the first isolation valve (TV1, BP1) are arranged such that the pressure medium from the second pressure supply unit (14) enters the second brake circuit (BK2) through the first isolation valve (TV1, BP1). The brake system (2) according to claim 1, characterized in that

3. At least one third isolation valve (BP2), wherein, when the third isolation valve (BP2) is closed, the first brake circuit (BK1) is hydraulically disconnected from the first and second pressure supply units (6, 14), A brake system (2) according to claim 1 or 2, characterized by the above.

4. The second isolation valve (TVBK2) is positioned such that the valve seat connection portion of the second isolation valve (TVBK2) is hydraulically connected to the second brake circuit (BK2), and / or The third isolation valve (BP2) is positioned such that the valve seat connection portion of the third isolation valve (BP2) is hydraulically connected to the first brake circuit (BK1), and / or The first isolation valve (BP1) is arranged such that its valve seat connection is hydraulically connected to the second isolation valve (TVBK2) and to the first pressure supply unit (6) via the fourth isolation valve (74). The brake system (2) according to claim 3, characterized in that

5. A stroke simulator (28) is provided connected to the second pressure supply unit (14). The brake system (2) according to any one of claims 1 to 4.

6. The third hydraulic line (HL3) is connected to the first hydraulic line (HL1) and the second hydraulic line (HL2). The brake system (2) according to any one of claims 1 to 5.

7. The fourth isolation valve (74, PD1), This allows the first and second hydraulic lines (HL1, HL2) to be reversibly separated from the first pressure supply unit (6), and / or The first and second hydraulic lines (HL1, HL2) are arranged and designed so that when the fourth isolation valve (74) is closed, they are disconnected from the first pressure supply unit (6). Characterized by the fourth isolation valve (74, PD1), The brake system (2) according to claim 4.

8. The brake system (2) according to claim 4, characterized in that the fourth isolation valve (74, PD1) is a valve that is normally closed, and / or the first isolation valve (BP1) and / or the second isolation valve (TVBK2) and / or the third isolation valve (BP2) and / or the supply valve (69) are valves that are normally open.

9. Characterized by at least one pressure relief valve (80, UeV) for component protection, which is fluidly connected to the working chamber of the first pressure supply unit (6), The brake system (2) according to any one of claims 1 to 8.

10. The at least one isolation valve (TV1, TV2, BP1, BP2) is a solenoid valve and / or a 2 / 2 directional valve, A brake system (2) according to any one of claims 1 to 9.

11. The brake pedal, which is an operating element (26), is located in the second pressure supply unit (14), and the second pressure supply unit (14) comprises a main brake cylinder (22) having a single piston (24) that can be operated by the operating element (26). The brake system (2) according to any one of claims 1 to 10.

12. A stroke simulator (28) is provided connected to the second pressure supply unit (14). The second pressure supply unit (14) and / or the stroke simulator (28) each comprises two sealing elements (42a, 42b and 28a, 28b), The brake system (2) according to any one of claims 1 to 11.

13. The control unit of the brake system (2) is configured to perform a diagnosis to determine the liquid tightness of the seal and / or to determine leakage based on the signal from the sensor element (62), The brake system (2) according to claim 1.

14. The electric drive device (8) of the first pressure supply unit (6) has redundant three-phase electrical connections (B1, B2) for operation by the control unit (48), The brake system (2) according to claim 13.

15. The first pressure supply unit (6) comprising a first piston-cylinder unit and the second pressure supply unit (14) comprising a second piston-cylinder unit are arranged within a housing such that the longitudinal axis (L6) of the first piston-cylinder unit is substantially perpendicular to the longitudinal axis (L14) of the second piston-cylinder unit. The brake system (2) according to any one of claims 1 to 14.

16. The second pressure supply unit (14) comprises a main brake cylinder (22) having only one piston (24) and only one piston chamber (23). The brake system (2) according to any one of claims 1 to 15.

17. The main brake cylinder (22) comprises at least one expansion bore (38) connected to a reservoir (40) via a hydraulic line, The main brake cylinder (22) comprises two ring seals (42a, 42b), with at least one expansion bore (38) positioned between the ring seals (42a, 42b), and a throttle (DR) and a parallel-connected check valve (RVHZ) are positioned in the hydraulic line between the expansion bore (38) positioned between the ring seals (42a, 42b) and the reservoir (40). The brake system (2) according to claim 16.

18. a. Providing a first pressure to a first connection point on a first hydraulic line (HL1) connected to the first brake circuit (BK1), b. A step of supplying a second pressure to a second connection point on a second hydraulic line (HL2) connected to the second brake circuit (BK2), c. A step of detecting a loss of pressure medium in the first brake circuit (BK1) and / or the second brake circuit (BK2) which is in a first failure state, d. In response to the detection of the first fault condition, the first isolation valve (TV1, BP1) or the second isolation valve (TV2, TVBK2) is closed to hydraulically disconnect the first pressure supply unit (6) from the first connection point or the second connection point, thereby allowing the pressure from the first pressure supply unit (6) to be selectively supplied to the first brake circuit (BK1) or the second brake circuit (BK2). A method for controlling the brake system (2) according to any one of claims 1 to 17, including the following:

19. - Closing the first isolation valve (BP1) and the second isolation valve (TVBK2), - Increasing the pressure using the first pressure supply unit (6), and - Measure the pressure at least at predetermined time intervals. Characterized by the diagnosis of the liquid-tightness of the first isolation valve (BP1) by, The method according to claim 18.

20. In response to detection of a second failure condition which is at least a partial failure of the third pressure supply unit, - A step of reading a measurement signal from the ESP unit via at least one bus, - A step of executing a control strategy for the valve of the ESP unit, taking into consideration the measurement signal. This is characterized by the detection of a second failure state, The method according to claim 18 or 19.

21. - In response to the detection of a third fault condition which is a fault in the first pressure supply unit (6) and / or a fault in the second brake circuit (BK2), - A step of controlling a valve so that a pressure medium can be supplied from a second pressure supply unit (14) to the first brake circuit (BK1) in order to brake the front axle (VA), which is the first axle of the vehicle, and - A step of operating the vehicle electric motor (TM1) on the second axle in order to brake the second axle, This is characterized by the detection of a third failure state, in which the following is performed. The method according to any one of claims 18 to 20.

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