BRAKE SYSTEM FOR A MOTOR VEHICLE

Description

[0001] The invention relates to a braking system for a motor vehicle according to the preamble of claim 1.

[0002] WO 2019158242 A1 describes an electro-hydraulic externally powered vehicle braking system. Two independent externally powered brake pressure generators each have brake fluid reservoirs divided into chambers, both of which are connected to a further brake fluid reservoir with a single chamber.

[0003] From DE 10 2018 214 564 A1, a braking system for a motor vehicle is known, comprising a master brake cylinder, a total of three pumps, and a reservoir for brake fluid. One of the pumps can draw brake fluid both from the master brake cylinder and directly from the reservoir.

[0004] From WO 2018 / 130483 A1, a brake system without a master brake cylinder and with two electrically controlled pressure sources for a motor vehicle with four hydraulically actuated wheel brakes is known. In addition to wheel-specific inlet and outlet valves, the brake system comprises a circuit separator valve and three further separator valves. The aforementioned components are arranged together in a single unit. Furthermore, two electronic control units are provided, with one of the electronic control units controlling the second pressure source and the inlet and outlet valves, while the first pressure source and all other valves are controlled by the other electronic control unit.The brake system comprises a pressure medium reservoir with two reservoir chambers, wherein the first pressure source for drawing in pressure medium is hydraulically connected to the first reservoir chamber and the second pressure source for drawing in pressure medium is hydraulically connected to the second reservoir chamber.

[0005] It is an object of the present invention to provide an improved braking system suitable for highly automated driving, which offers the highest possible availability necessary for highly automated driving. In particular, the braking system should offer improved operating time / availability in the event of a leak when the vehicle is parked.

[0006] A further object of the present invention is to provide an improved braking system suitable for highly automated driving, which also offers such high availability in the event of a leak that it does without a driver-operated hydraulic fallback level, in particular without a mechanical-hydraulic connection from a driver-operated actuating unit (e.g. a driver-operated master brake cylinder) to the wheel brakes.

[0007] This problem is solved according to the invention by a braking system according to claim 1.

[0008] The invention is based on the concept that the brake system comprises an electrically actuated inlet valve for each wheel brake, a first electrically actuated pressure source, and a second electrically actuated pressure source, wherein the first and second pressure sources are connected to a brake supply line to which the at least four inlet valves are connected, and a pressure medium reservoir with a first reservoir chamber and a second reservoir chamber, wherein the first pressure source is hydraulically connected to the first reservoir chamber and wherein the second pressure source is hydraulically connected to the second reservoir chamber. The pressure medium reservoir comprises a third reservoir chamber, and the first pressure source is connected to the third reservoir chamber of the pressure medium reservoir via an electrically actuated first isolation valve.

[0009] The braking system offers the advantage that the first pressure source, and thus the brake supply line or the wheel brakes, can be depressurized via the connection to the first isolating valve, but in the event of a leak via this connection only the third reservoir chamber empties and pressure medium can remain in the first and second reservoir chambers to ensure sufficient braking of the vehicle for at least a predetermined duration or distance.

[0010] Preferably, the first isolating valve is designed to be normally open, so that in a de-energized state of the brake system the wheel brakes are connected to the third reservoir chamber via the first isolating valve, so that the wheel brakes are depressurized.

[0011] The first pressure source is advantageously hydraulically connected to the first container chamber for the purpose of drawing in pressure medium.

[0012] Preferably, the first pressure source is hydraulically connected to the first reservoir chamber via a check valve opening towards the first pressure source. Advantageously, this is a spring-loaded check valve, as is known, for example, from WO 2018 / 130483 A1. This allows hydraulic fluid to be drawn from the first reservoir chamber into the first pressure source as needed, while preventing the first reservoir chamber from emptying via the first pressure source. Particularly preferred is this connection of the first reservoir chamber to the first pressure source as the sole hydraulic connection of the first reservoir chamber to the brake system or to the wheel brakes.

[0013] The second pressure source is advantageously hydraulically connected to the second reservoir chamber for the purpose of drawing in pressure medium. Particularly preferably, a suction side of the second pressure source is hydraulically connected to the second reservoir chamber. Particularly preferably, the second pressure source is hydraulically connected to the second reservoir chamber on the suction side and to the brake supply line on the pressure side. Most preferably, the second pressure source comprises one or more spring-loaded check valves arranged in the hydraulic connection between the second reservoir chamber and the brake supply line.

[0014] Preferably, the pressure medium reservoir is a pressure medium reservoir at atmospheric pressure.

[0015] Preferably, no electrically actuated valve is arranged in the hydraulic connection between the second pressure source (or the suction side of the second pressure source) and the second reservoir chamber. This ensures suction of the pressure medium with low hydraulic resistance.

[0016] Preferably, no further electrically actuated valve is arranged in the hydraulic connection between the first pressure source and the third reservoir chamber besides the first isolation valve. This allows for rapid pressure equalization between the wheel brakes and the hydraulic fluid reservoir when the first isolation valve is opened.

[0017] Preferably, the three chambers of the pressure medium reservoir are separated from each other by bulkheads. Pressure medium reservoirs with separate chambers are generally known, with the separation of the chambers usually achieved by means of bulkheads. Thus, if pressure medium leaks from one of the chambers via the corresponding connection, a reserve of pressure medium remains in the other two chambers.

[0018] Preferably, the three reservoir chambers and at least one overflow are arranged and designed such that any overflow of hydraulic fluid from the third reservoir chamber (directly) is only possible into the first reservoir chamber (and not into the second reservoir chamber). With the circuit isolating valve closed, when the first and second brake circuits are separated, hydraulic fluid can flow into the third reservoir chamber via the opening first isolating valve when pressure is reduced by the first pressure source. Excess hydraulic fluid is then not lost into the second reservoir chamber or the brake circuit of the second pressure source. It is also possible to draw hydraulic fluid from the first reservoir chamber using the first pressure source, in which case the excess hydraulic fluid flows into the "correct" brake circuit of the first pressure source via the first isolating valve.

[0019] Preferably, the third reservoir chamber is smaller than the first and smaller than the second. This allows the pressure medium reservoir to remain compact despite the addition of a third chamber. By slightly reducing the size of the first and second reservoir chambers, the overall volume of the pressure medium reservoir can be maintained. A smaller third reservoir chamber is also advantageous for other reasons. In the event of a leak located significantly lower than the pressure medium reservoir, for example, at one of the wheel brakes, the pressure differential could open the check valve to the first reservoir chamber, causing it to empty as well. The draining of the first reservoir chamber stops as soon as air (from the emptied third reservoir chamber) enters the system pressure line section through the first isolation valve, and the vacuum collapses.

[0020] Preferably, the brake system includes an electrically actuated outlet valve for each wheel brake, wherein the outlet valves are normally closed (closed). Particularly preferably, the outlet valves are connected to the second reservoir chamber, as is the second pressure source. Particularly preferably, all outlet valves are connected to the second reservoir chamber of the pressure medium reservoir via a common hydraulic connection.

[0021] Preferably, a check valve opening in the direction of the first pressure source is connected in parallel to the first separating valve.

[0022] Preferably, an electrically actuated circuit isolating valve is arranged in the brake supply line such that, when the circuit isolating valve is closed, the brake supply line is hydraulically separated into a first line section and a second line section, wherein the first line section is hydraulically connected to the second pressure source and at least two of the at least four inlet valves, and the second line section is hydraulically connected to the first pressure source and the other two of the at least four inlet valves. Particularly preferably, the second line section is hydraulically connected to the first pressure source and the other two of the at least four inlet valves.

[0023] Preferably, the circuit separator valve is designed to be normally open, so that the circuit separator valve does not need to be actuated to operate the / all wheel brakes using one of the pressure sources.

[0024] Preferably, the first pressure source is connected to the brake supply line via an electrically actuated second isolating valve. By closing the second isolating valve, the first pressure source (or the first component) can be hydraulically disconnected from the brake supply line, for example, if the brake system is to be or must be operated in a mode (e.g., in the event of an electrical failure of the first component) in which the at least four wheel brakes are pressurized by means of the second pressure source. It is particularly preferred that the second isolating valve be normally open. Thus, in a de-energized state of the brake system, the wheel brakes are connected to the third reservoir chamber via the second and first isolating valves and are depressurized.

[0025] Preferably, the first pressure source is connected to the second isolation valve via a system pressure line section, wherein the system pressure line section is connected to the third reservoir chamber of the pressure medium reservoir via the first isolation valve.

[0026] Preferably, the brake system comprises at least four wheel connections for the at least four wheel brakes, and in a de-energized state of the brake system, the first reservoir chamber and the second reservoir chamber are hydraulically isolated from the wheel connections. This prevents the first and second reservoir chambers from emptying when the brake system is switched off (e.g., when the vehicle is parked) and there is a leak in one of the wheel brake lines (e.g., between the wheel connection and the wheel brake).

[0027] Preferably, the first reservoir chamber is hydraulically connected to the at least four wheel connections exclusively via the first pressure source, wherein the first reservoir chamber is hydraulically connected to the first pressure source via a spring-loaded check valve opening towards the first pressure source. This allows hydraulic fluid to be drawn from the first reservoir chamber into the first pressure source as needed, in order to then deliver the hydraulic fluid to the wheel connections (or into the wheel brakes) via the first pressure source, while preventing the first reservoir chamber from draining via the first pressure source.

[0028] Preferably, the second reservoir chamber is hydraulically connected to the at least four wheel connections via the normally closed outlet valves. Particularly preferably, the second reservoir chamber is further hydraulically connected to the at least four wheel connections via the second pressure source, wherein the second pressure source comprises at least one spring-loaded check valve opening towards the wheel connections, so that the second reservoir chamber is hydraulically connected to the at least four wheel connections via the spring-loaded check valve(s) of the second pressure source. A further (third) hydraulic connection between the second reservoir chamber and the at least four wheel connections is particularly preferably omitted. This allows hydraulic fluid to be drawn from the second reservoir chamber via the second pressure source and delivered to the wheel connections (or into the wheel brakes) as needed.And if necessary, pressure fluid can be released into the second reservoir chamber via the outlet valves. However, the second reservoir chamber is prevented from emptying when the brake system is de-energized.

[0029] Preferably, the first pressure source and its connection to the first reservoir chamber are designed such that, in a de-energized state of the brake system, there is no hydraulic connection between the first reservoir chamber and the wheel connections of the brake system or the wheel brakes, through which pressure medium can flow from the first reservoir chamber into one of the wheel brakes.

[0030] Preferably, the brake system is designed such that, in a de-energized state of the brake system, there is no hydraulic connection between the first reservoir chamber and the wheel connections of the brake system or the wheel brakes, through which pressure medium can flow from the first reservoir chamber into one of the wheel brakes.

[0031] Preferably, the second pressure source and its connection to the second reservoir chamber are designed such that, in a de-energized state of the brake system, there is no hydraulic connection between the second reservoir chamber and the wheel connections of the brake system or the wheel brakes, through which pressure medium can flow from the second reservoir chamber into one of the wheel brakes.

[0032] Preferably, the brake system is designed such that, in a de-energized state of the brake system, there is no hydraulic connection between the second reservoir chamber and the wheel connections of the brake system or the wheel brakes, through which pressure medium can flow from the second reservoir chamber into one of the wheel brakes.

[0033] According to a preferred embodiment of the invention, the second pressure source is designed as a two-circuit or multi-circuit pump. Particularly preferably, the second pressure source is designed as a two-piston pump or a multi-piston pump.

[0034] Particularly preferred are the pressure sides of the two- or multi-circuit pressure source connected together (e.g. to a common pressure port) and the suction sides of the two- or multi-circuit pressure source connected together (to a common suction port).

[0035] The suction side (or suction port) of the second pressure source is particularly preferably connected together with the outlet valves to the second reservoir chamber of the pressure medium storage tank.

[0036] The pressure side (or pressure connection) of the second pressure source is preferably connected to the first section of the brake supply line.

[0037] Preferably, the first pressure source is formed by a cylinder-piston arrangement with a hydraulic pressure chamber, the piston of which is moved forward by an electromechanical actuator to build up brake pressure and back to reduce brake pressure.

[0038] The first pressure source is preferably formed by a cylinder-piston arrangement with a hydraulic pressure chamber, a suction port, and a pressure port, the piston of which is moved back and forth by an electromechanical actuator. The suction port is advantageously connected to the first reservoir chamber of the hydraulic fluid storage tank via a check valve opening towards the first pressure source. The pressure port is advantageously connected to the brake supply line, particularly the second section of the line. Most preferably, the pressure port is additionally connected to the third reservoir chamber of the hydraulic fluid storage tank via the first isolation valve.

[0039] Preferably, the braking system comprises a first electronic control device that controls the first pressure source, and a second electronic control device that controls the second pressure source and the inlet valves, and in particular the exhaust valves.

[0040] According to a further development of the invention, the brake system comprises a first assembly in which the first electrically actuated pressure source is arranged, and a second assembly in which the second electrically actuated pressure source and the electrically actuated inlet valves are arranged, wherein the pressure medium reservoir is arranged on the first assembly. The outlet valves are particularly preferably arranged in the second assembly.

[0041] Preferably, the first and second components are connected to each other by at most one pressure-resistant hydraulic connecting element.

[0042] Other non-pressure-resistant connecting elements between the first and second building units are possible.

[0043] A pressure-resistant connecting element or connection is preferably understood to be one that is designed for a maximum operating pressure of one of the pressure sources, in particular the first pressure source, and / or the wheel brakes. Particularly preferably, the pressure-resistant connecting element or connection is designed for a pressure of approximately 180-220 bar. Most preferably, the pressure-resistant connecting element or connection is designed for a pressure of approximately 200 bar.

[0044] Preferably, a non-pressure-resistant connecting element or connection is understood to mean that the connecting element or connection is not designed for the maximum operating pressure of the wheel brakes. Particularly preferably, a non-pressure-resistant connecting element or connection is designed for a maximum pressure of approximately 10 bar.

[0045] The first and second components are preferably designed such that they are connected to each other by at most one pressure-resistant hydraulic connection element. The first and second components may be connected to each other by several hydraulic connection elements, but at most one – meaning only one – of these hydraulic connection elements is pressure-resistant. Any other hydraulic connection elements are not pressure-resistant.

[0046] Preferably, the first and second components are connected by only one hydraulic connecting element, which is pressure-resistant. Additional, non-pressure-resistant connecting elements, advantageously between the second component and the pressure medium reservoir, are possible.

[0047] Preferably, the first isolation valve is arranged in the first assembly unit.

[0048] Preferably, the exhaust valves are arranged in the second assembly unit.

[0049] Preferably, the circular separation valve is arranged in the second assembly unit.

[0050] Preferably, the second isolation valve is arranged in the second assembly unit.

[0051] Dividing the system into two units offers the advantage over a single-unit design that both units are smaller, lighter, and therefore easier to handle. They can also be manufactured more easily on existing production lines. On the other hand, with a two-unit design, each hydraulic connection between these units results in considerable complexity and expense. It is therefore particularly advantageous to minimize the number of hydraulic connections. Experience has shown that it is beneficial to clearly separate the different functions of hydraulic connections. For example, connections through which hydraulic fluid is drawn in can be designed with the largest possible diameter to minimize hydraulic resistance. It is advantageous if such connections do not need to be pressure-resistant.Conversely, pressure-bearing connections should not have a suction function.

[0052] Preferably, the first assembly comprises a first electronic control device that controls the first pressure source, and the second assembly comprises a second electronic control device that controls the second pressure source and the inlet valves (and optionally the outlet valves).

[0053] Preferably, the first assembly comprises a first hydraulic connection for connecting to the first reservoir chamber, a third hydraulic connection for connecting to the third reservoir chamber, and a second hydraulic connection for connecting to the second assembly, wherein the second hydraulic connection is connected to the hydraulic connecting element. Particularly preferably, the first assembly does not include any further hydraulic connection besides the first hydraulic connection, the second hydraulic connection, and the third hydraulic connection.

[0054] The first pressure source is preferably connected to the second hydraulic connection in order to be able to actuate at least four wheel brakes.

[0055] The second assembly preferably comprises at least four hydraulic wheel connections for connecting to the wheel brakes, a first hydraulic connection for connecting to the second reservoir chamber, and a second hydraulic connection for connecting to the first assembly, wherein the second hydraulic connection is connected to the hydraulic connecting element. Particularly preferably, the second assembly does not include any further hydraulic connections besides the first hydraulic connection, the second hydraulic connection, and the at least four hydraulic wheel connections.

[0056] Preferably, the first isolation valve is controlled by the first electronic control device.

[0057] Preferably, the circular separation valve is controlled by the second electronic control device.

[0058] Preferably, the second isolation valve is controlled by the second electronic control device.

[0059] Preferably, the brake system comprises a first electrical partition and a second electrical partition, which are electrically independent of each other. The first pressure source and the first electronic control device are assigned to the first electrical partition, and the second pressure source, the second electronic control device, and the inlet valves are assigned to the second electrical partition. Particularly preferably, the outlet valves and the circuit isolator valve are assigned to the second electrical partition. Particularly preferably, the first isolator valve is assigned to the first electrical partition. Particularly preferably, the second isolator valve is assigned to the second electrical partition.

[0060] Preferably, the first electronic control device or the first electrical partition is supplied by a first electrical energy source, and the second electronic control device or the second electrical partition is supplied by a second electrical energy source, which is independent of the first electrical energy source. The first energy source is thus part of the first electrical partition, and the second energy source is part of the second electrical partition.

[0061] Preferably, the first pressure source is controlled exclusively by the first electronic control device, and the second pressure source, the inlet and outlet valves, and the circuit separator valve are controlled exclusively by the second electronic control device. Particularly preferably, the first separator valve is controlled exclusively by the first electronic control device, and the second separator valve is controlled exclusively by the second electronic control device.

[0062] The invention offers the advantage that, through the selection and arrangement of the electrically actuated valves, in particular the electronic partitioning and especially the assignment between electrically actuated valves and electronic control devices, a clear separation of the properties of the hydraulic connections is made possible.

[0063] Preferably, the braking system includes at least four hydraulically actuated wheel brakes.

[0064] Preferably, the brake system comprises an inlet valve and an outlet valve for each wheel brake for adjusting wheel-specific brake pressures, which are derived from the brake supply pressure in the brake supply line, wherein in the uncontrolled state the inlet valves forward the brake supply pressure to the wheel brakes and the outlet valves block the outflow of pressure medium from the wheel brakes.

[0065] Preferably, the braking system, besides the first and second pressure sources, does not include any further pressure source for building up brake pressure to actuate the wheel brakes. Preferably, the braking system does not include any further electrically actuated pressure source or a driver-operated pressure source, such as a master brake cylinder, which is operatively connected to at least one of the wheel brakes for their actuation, e.g., hydraulically or mechanically.

[0066] Preferably, the braking system comprises an actuating unit for a driver, wherein the actuating unit is connected to at least one electronic control device for transmitting a driver request signal and wherein there is no mechanical-hydraulic connection from the actuating unit to the wheel brakes.

[0067] The braking system according to the invention offers the advantage that the braking system can maintain the most important residual braking functions for a required time and / or distance even if one of the two redundant electrical pressure sources fails, e.g. due to a failure of the electrical power source or the electronic control device associated with it, or a mechanical fault or a leak in one of the two brake circuits.

[0068] The braking system according to the invention is therefore particularly suitable for the realization of highly automated driving functions and for use with an electric brake pedal which has no mechanical-hydraulic connection to the wheel brakes.

[0069] Further preferred embodiments of the invention will become apparent from the dependent claims and the following description with reference to figures.

[0070] They show schematically Fig. 1 a first embodiment of a braking system according to the invention, and Fig. 2 a second embodiment of a braking system according to the invention.

[0071] In Fig. 1 Figure 1 is a first embodiment of a braking system according to the invention for a motor vehicle, shown in a highly schematic manner. By way of example, the braking system is designed to actuate four hydraulically actuated wheel brakes 8a-8d; expansion to include more wheel brakes is easily possible. By way of example, wheel brakes 8a, 8b are assigned to the rear axle (rear) and wheel brakes 8c, 8d to the front axle (front) of the vehicle.

[0072] The braking system comprises a first electrically actuated pressure source 5 and a second electrically actuated pressure source 2. To actuate the wheel brakes 8a-8d, the first pressure source 5 and the second pressure source 2 (on the pressure side) are connected to a brake supply line 13, to which the four wheel brakes 8a-8d are each connected via an inlet valve 6a-6d. Thus, all four wheel brakes 8a-8d can be actuated by means of the first pressure source 5 or by means of the second pressure source 2.

[0073] The brake system comprises a hydraulic fluid reservoir 4 with three reservoir chambers 401, 402, and 403. The first reservoir chamber 401 is assigned to the first pressure source 5, and the second reservoir chamber 402 to the second pressure source 2. For drawing in hydraulic fluid, the first pressure source 5 (suction side) is hydraulically connected to the first reservoir chamber 401 via a check valve 53 that closes towards the first reservoir chamber 401. For drawing in hydraulic fluid, the second pressure source 2 (suction side) is directly hydraulically connected to the second reservoir chamber 402. The third, separate reservoir chamber 403 is provided to allow pressure equalization of the wheel brakes 8a-8d when necessary, i.e., in particular, to depressurize the wheel brakes 8a-8d.For this purpose, the first pressure source 5, and thus also the brake supply line 13 to the wheel brakes 8a-8d, is separably connected to the third reservoir chamber 403 via an electrically actuated isolating valve 23.

[0074] Advantageously, the first electrically controllable pressure source 5 is designed as a hydraulic cylinder-piston arrangement (or an electrohydraulic actuator (linear actuator)).

[0075] Advantageously, the second electrically controlled pressure source 2 is designed as a piston pump, for example as a two-piston pump, whose two pressure sides are connected together and whose two suction sides are connected together.

[0076] An electrically actuated circuit isolator valve 40 is advantageously arranged in the brake supply line 13, so that when the circuit isolator valve 40 is closed, the brake supply line 13 is divided into a first line section 13a, to which the inlet valves 6a, 6b and the wheel brakes 8a, 8b are connected, and a second line section 13b, to which the inlet valves 6c, 6d and the wheel brakes 8c, 8d are connected. The second pressure source 2 is hydraulically connected to the first line section 13a, and the first pressure source 5 is hydraulically connected to the second line section 13b. When the circuit isolator valve 40 is closed, the brake system is thus separated or divided into two hydraulic brake circuits, I and II.In the first brake circuit I, pressure source 2 (via the first line section 13a) is connected only to wheel brakes 8a and 8b, and in the second brake circuit II, the first pressure source 5 (via the second line section 13b) is connected only to wheel brakes 8c and 8d. The circuit isolating valve 40 is advantageously designed to be normally open (de-energized).

[0077] Each wheel brake 8a-8d is provided with an electrically actuated inlet valve 6a-6d, which is advantageously designed to be normally open, and an electrically actuated outlet valve 7a-7d, which is advantageously designed to be normally closed.

[0078] As already mentioned, the brake system comprises the pressure medium reservoir 4, which is advantageously at atmospheric pressure, and has three reservoir chambers 401, 402, and 403. The first chamber 401 is assigned a first reservoir connection 411, the second chamber 402 a second reservoir connection 412, and the third chamber 403 a third reservoir connection 413. The first reservoir chamber 401 is assigned to the first pressure source 5, and the second reservoir chamber 402 to the second pressure source 2. For the purpose of drawing in pressure medium, the first pressure source 5 (on the suction side, for example via a suction connection 520 and a (re-suction) line 42) is hydraulically connected to the first reservoir chamber 401. In A check valve 53, closing towards the first reservoir chamber 401 of the pressure medium reservoir 4, is arranged in the (suction) line 42. For the purpose of drawing in pressure medium, the second pressure source 2 (suction side, for example via a suction port 220, a line 14 and a hose 90) is hydraulically connected directly to the second reservoir chamber 402.

[0079] The third, separate reservoir chamber 403 is provided to allow pressure equalization of the wheel brakes 8a-8d when necessary, i.e., in particular to depressurize the wheel brakes 8a-8d. For this purpose, the first pressure source 5, and thus also the brake supply line 13 to the wheel brakes 8a-8d, is disconnectably connected to the third reservoir chamber 403 via an electrically actuated, preferably normally open, isolating valve 23.

[0080] Thus, the first pressure source 5 can be depressurized by means of the isolating valve 23, or the wheel brakes 8a-8d are depressurized when the brake system is de-energized.

[0081] For example, a pressure medium storage tank 4 is divided into three chambers 401, 402, and 403 by two bulkheads. For instance, the pressure medium storage tank 4 comprises a first bulkhead 421 and a second bulkhead 422, with the first chamber 401 being separated from the third chamber 403 by the first bulkhead 421, and the third chamber 403 being separated from the second chamber 402 by the second bulkhead 422. A different order of the chambers or a different relative arrangement of the three chambers is possible. In principle, the pressure medium storage tank 4 can also have more than three chambers; however, this entails higher manufacturing costs.

[0082] The third chamber 403 of the pressure medium reservoir 4 can be dimensioned very small (the third chamber 403 is smaller than the first chamber 401 and smaller than the second chamber 402). The installation space for the pressure medium reservoir 4 can be chosen to be the same size as for a known pressure medium reservoir 4 with two chambers, i.e., the pressure medium reservoir 4 does not increase in size.

[0083] The three container chambers 401, 402, 403 and at least one overflow between them are arranged and designed in such a way that a (direct) overflow of pressure medium from the third container chamber 403 is only possible into the first container chamber 401, and not into the second container chamber 402.

[0084] Advantageously, the brake system for leakage monitoring includes a level measuring device 50 for detecting or determining the pressure medium level in the pressure medium reservoir 4. The level measuring device 50 is designed to also detect pressure medium levels in the pressure medium reservoir 4 that are located above the bulkhead walls 421, 422. For example, the level measuring device 50 detects a pressure medium level that is too low and, in particular, closes the circuit separating valve 40 when the pressure medium level falls below the limit level 501. The limit level 501 is located above the bulkhead walls 421, 422.

[0085] For example, the level measuring device 50 is arranged in the first reservoir chamber 401. Positioning the level measuring device 50 in the reservoir chamber (401) associated with the pressure source, which is designed as a hydraulic cylinder-piston arrangement (linear actuator) (first pressure source 5), offers the advantage of faster detection of a pressure medium loss. In the event of an external leak, pressure medium would be pumped out very quickly via the linear actuator during braking, and the pressure medium would flow back into the pressure medium reservoir 4 at a limited rate (especially in cold conditions). To be able to report the pressure medium loss quickly, it is therefore advantageous to place the level measuring device 50 close to the point where a large outflow is expected, i.e., in the reservoir chamber 401 associated with the first pressure source 5 (linear actuator).

[0086] The brake system comprises, for example, a first assembly 100, which is designed, for example, as a first electro-hydraulic brake control unit (HECU1) with a valve block HCU1 and a first electronic control device 101 (ECU1), and a second assembly 200, which is designed, for example, as a second electro-hydraulic brake control unit (HECU2) with a valve block HCU2 and a second electronic control device 201 (ECU2).

[0087] The first electrically actuated pressure source 5 is arranged in the first assembly unit 100.

[0088] The second assembly unit 200 contains the second electrically actuated pressure source 2 and the wheel-individual brake pressure modulation valves (inlet valves 6a-6d and outlet valves 7a-7d).

[0089] The pressure medium reservoir 4 is, for example, arranged on the first assembly unit 100.

[0090] As already mentioned, the brake system comprises, for each hydraulically actuated wheel brake 8a-8d, an inlet valve 6a-6d and an outlet valve 7a-7d, which are hydraulically connected in pairs via center connections and each pair is connected to a hydraulic wheel connection 9a-9d of the second assembly 200, to which the corresponding wheel brake 8a-8d is connected. A check valve 70a-70d, opening towards the brake supply line 13, is connected in parallel to each inlet valve 6a-6d. The outlet connections of the outlet valves 7a-7d are connected via a common line 14 to a hydraulic connection 62 of the second assembly 200, which is connected to the pressure medium reservoir 4 or its reservoir chamber 402. The inlet ports of all inlet valves 6a-6d can be supplied with pressure via the brake supply line 13 (with the circuit separator valve 40 open) from the first pressure source 5 or, e.g.In the event of failure of the first pressure source 5, pressure is supplied by the second pressure source 2.

[0091] The first electrically controlled pressure source 5 of the valve block HCU1 is designed as a hydraulic cylinder-piston arrangement (or a single-circuit electrohydraulic actuator (linear actuator)), whose piston 36 can be actuated by a schematically indicated electric motor 35 via an interposed rotary-translational transmission 39, in particular by moving it back and forth to build up and release pressure in a pressure chamber 37. The piston 36 defines the pressure chamber 37 of the pressure source 5. A rotor position sensor 44, also only schematically indicated, is provided for controlling the electric motor 35.

[0092] A system pressure line section 38 is connected to the pressure chamber 37 of the first electrically controlled pressure source 5. Pressure source 5, or pressure chamber 37, is connected via line section 38 to a hydraulic connection 60 of the first assembly 100, which is connected via a hydraulic connecting element 80 to a hydraulic connection 61 of the second assembly 200. Connection 80 represents the only hydraulic pressure connection, in particular the only hydraulic connection, between the first and the second assembly. This hydraulic connection is for transmitting brake pressure to actuate the wheel brakes 8a-8d. Connecting element 80 must therefore be pressure-resistant.

[0093] Pressure chamber 37 is connected, regardless of the actuation state of the piston 36, via the (suction) line 42 to the first reservoir connection 411 of the pressure medium reservoir 4, and thus to the reservoir chamber 401. The check valve 53, which closes towards the pressure medium reservoir 4, is located in the line 42. The cylinder-piston assembly 5, for example, has no vent holes.

[0094] Furthermore, the pressure chamber 37 of the first pressure source 5 is connected, for example via the line section 38, the isolation valve 23 and a line 43, to the third container connection 413 of the pressure medium reservoir 4, and thus to the reservoir chamber 403. For example, a check valve 72 opening towards the pressure chamber 37 is connected in parallel to the isolation valve 23. However, such a check valve 72 is not functionally necessary (see also the second embodiment of the Fig. 2 ).

[0095] In addition to the two (unpressurized) connections to the tank chambers 401, 403 and the (pressurized) connection 60, the first assembly unit 100 does not include any further hydraulic connections.

[0096] The second electrically controlled pressure source 2 is, for example, designed as a two-piston pump whose two pressure sides are connected together (pressure port 221) and whose two suction sides are connected together (suction port 220). The suction sides (suction port 220) are connected to line 14 and thus to port 62 or 412, and therefore to the second reservoir chamber 402. The pressure sides (pressure port 221) are connected to the first line section 13a of the brake supply line 13.

[0097] In addition to the pressure source 2 and the brake pressure modulation valves 6a-6d, 7a-7d, the second assembly 200 includes, for example, an electrically actuated isolating valve 26, advantageously designed to be normally open. The isolating valve 26 is hydraulically connected between the first pressure source 5, specifically the connection 61, and the second line section 13b of the brake supply line 13. Thus, the first pressure source 5 is disconnected from the second line section 13b, or the brake supply line 13, via the isolating valve 26.

[0098] The brake system includes, for example, a pressure sensor 19 in brake circuit II (line section 13b), which is thus assigned to pressure source 5. However, pressure sensor 19 can also be located in brake circuit I (see embodiment of the Fig. 2 ) or a second pressure sensor can be provided so that each of the two brake circuits I and II can be directly monitored by means of a pressure sensor.

[0099] For example, components 5, 53, 23, 72 and line sections 38, 42, 43 are arranged in the first valve block HCU1 and components 2, 40, 6a-6d, 7a-7d, 26, 19 and line sections 13a, 13b (and the line sections between the inlet and outlet valves on the one hand and the wheel connections on the other) are arranged in the second valve block HCU2.

[0100] Each valve block HCU1, HCU2 is associated with an electronic control unit 101, 201 (ECU1, ECU2). Each electronic control unit 101, 201 comprises electrical and / or electronic elements (e.g., microcontrollers, power components, valve drivers, other electronic components, etc.) for controlling the electrically actuated components of the associated valve block and, if applicable, the associated sensors. Advantageously, the valve block and electronic control unit are designed in a known manner as an electrohydraulic unit (HECU).

[0101] For the electrical connection, linking and supply of the individual electrical or electrically actuated, controllable, evaluable or similar components of the brake system, a first electrical partition A and a second electrical partition B are provided, which are electrically independent of each other.

[0102] In the figure, those electrical components which are assigned to or belong to the first electrical partition A are marked by an arrow with A, while those electrical components which are assigned to or belong to the second electrical partition B are marked by an arrow with B.

[0103] The electronic control device 101 is assigned to, or belongs to, the first electrical partition A, while the second electronic control device 201 is assigned to, or belongs to, the second electrical partition B. Accordingly, the electronic control device 101 and the second electronic control device 201 are electrically independent.

[0104] To supply the braking system with electrical energy, a first electrical energy source 103, e.g. an on-board electrical system, and a second electrical energy source 203, e.g. an on-board electrical system, independent of the first energy source, are provided.

[0105] The first electrical energy source 103 supplies the first electrical partition A with energy and the second electrical energy source 203 supplies the second electrical partition B.

[0106] The first electronic control device 101 controls the first pressure source 5. Accordingly, the first pressure source 5 is assigned to or belongs to the first electrical partition A. For example, the first pressure source 5 is supplied with energy (from the first electrical energy source 103) via the first electronic control device 101.

[0107] The second electronic control device 201 controls the second pressure source 2. Accordingly, the second pressure source 2 is assigned to or belongs to the second electrical partition B. For example, the second pressure source 2 is supplied with energy (from the second electrical energy source 203) via the second electronic control device 201.

[0108] For example, the first pressure source 5 can be controlled exclusively by the first electronic control device 101, and the second pressure source 2 exclusively by the second electronic control device 201. In principle, it would be conceivable to equip the electric motor of a pressure source with, for example, two electrically independent motor windings, so that the pressure source could be controlled by the two independent electrical devices. However, this would involve further redundancies, such as duplicate connecting lines, etc., and would therefore be more expensive.

[0109] The remaining components of the brake system are advantageously assigned to either the first electronic control unit 101 (partition A) or the second electronic control unit 201 (partition B). That is, they are controlled or actuated by this control unit and / or supplied with electrical energy and / or are connected to this control unit via signals and / or are evaluated by this control unit. To avoid further redundancies, a component is advantageously controllable or actuated, supplied with electrical energy, connected to, or evaluated by only or exclusively by one of the two electronic control units 101 or 201, but not by the other electronic control unit.

[0110] The inlet and outlet valves 6a-6d, 7a-7d are assigned to the second electrical partition B and are controlled by the second electronic control device 201. Likewise, the circuit separator valve 40 is assigned to the second electrical partition B and is controlled by the second electronic control device 201.

[0111] The isolating valve 26 for separating the first pressure source 5 and brake supply line 13 is also assigned to the second electrical partition B and is controlled by the second electronic control device 201.

[0112] Pressure sensor 19 is also assigned to the second electrical partition B. Its signals are fed to the second electronic control device 201, which evaluates and processes them.

[0113] The separating valve 23, on the other hand, is assigned to the first electrical partition A and is controlled by the first electronic control device 101.

[0114] Furthermore, the signals from the level measuring device 50 are fed to the first electronic control device 101 and evaluated and processed by it.

[0115] The suction side 220 of the pressure source 2 is connected directly to the second reservoir chamber 402 of the pressure medium reservoir 4 via connection 62 and a line or hose 90, without the interposition of an electrically actuated valve. The connection 90 does not carry pressure and can therefore have a large diameter.

[0116] The pressure side 221 of the pressure source 2 is directly connected to the first line section 13a without the interposition of a valve.

[0117] The pressure port 521 of the pressure source 5 is connected via the separating valve 23, also called pressure relief valve, to the pressure medium reservoir 4, specifically the third reservoir chamber 403.

[0118] Preferably, the isolating valve 26, the circular isolating valve 40 and the isolating valve 23 are designed to be normally open.

[0119] Under normal operating conditions, pressure in the wheel brakes is built up by pressure source 5 with the isolation valve 23 closed. Pressure is released back into pressure source 5 or via the isolation valve 23. The pressure is modulated individually for each wheel as needed by the inlet and outlet valves 6a-6d and 7a-7d. If necessary, the isolation valve 26 is closed to allow pressure source 5 to draw in additional volume, e.g., from the first reservoir chamber 401.

[0120] When a particularly high flow rate is required, both pressure sources 5 and 2 operate simultaneously in parallel. In this case, the pressure reduction occurs at least partially via the isolating valve 23, which is preferably designed as an analog valve, meaning it can control its flow rate. The pressure reduction that cannot occur via the first pressure source 5 (so-called excess pressure medium volume) can be carried out either via the isolating valve 23 or via the outlet valves, preferably via the outlet valves 7a and 7b at the rear axle. When a particularly high pressure is required, the isolating valve 26 is closed, and pressure source 2 increases the pressure above the pressure of pressure source 5. Outside of braking, atmospheric pressure equalization is permanently ensured via the isolating valves 23 and 26.

[0121] In the event of a leak in the brake system, the circuit separating valve 40 is advantageously closed, thereby dividing the system into two independent brake circuits I and II.

[0122] Preferably, the isolation valve 23 is controlled by the primary ECU 101. Preferably, the isolation valve 26 is controlled by the secondary ECU 201. The following description of operation in the event of a fault refers to this valve assignment.

[0123] If the primary system fails electrically, in particular the primary ECU 101 or its power supply 103 (failure of partition A), the secondary ECU 201 closes the isolation valve 26 to build up pressure via the secondary pressure source 2. Pressure is released via the isolation valve 26 or via the outlet valves 7a-7d. Preferably, the inlet and outlet valves are controlled by the secondary ECU 201 (partition B) so that the pressure can be modulated individually for each wheel.

[0124] If the secondary system fails electrically, in particular the secondary ECU 201 or its power supply 203 (failure of partition B), the pressure is built up and released as in normal operation via the primary pressure source 5 and, if necessary, the isolation valve 23. Individual wheel pressure control is not possible, but collective modulation of the wheel pressures remains possible to prevent the vehicle from being destabilized by wheel lock-up.

[0125] Preferably, the valves are assigned to the two ECUs as described above, the circuit separator valve 40 is controlled by the secondary ECU 201, and the system is divided into two units 100, 4 and 200 with two hydraulic connecting lines 80 (pressure-resistant) and 90 (pressureless). These two units preferably each comprise one of the two ECUs, the associated pressure source, and the associated valves.

[0126] Dividing the exemplary brake system into two units offers the advantage over a single-unit design that both units are smaller, lighter, and therefore easier to handle. They can also be manufactured more easily on existing production lines. However, with a two-unit design, each hydraulic connection between these units introduces additional complexity and costs. Therefore, it is advantageous to minimize the number of hydraulic connections. Furthermore, it is beneficial to clearly separate the different functions of hydraulic connections. Connections through which hydraulic fluid is drawn in should have the lowest possible hydraulic resistance and therefore the largest possible diameter. To achieve this, it is advantageous if such connections do not need to be pressure-resistant.Conversely, pressure-bearing connections should not have a suction function.

[0127] The selection and arrangement of the electrically actuated valves, the electronic partitioning, and in particular the allocation between electrically actuated valves and electronic control devices enable these advantageous properties of the hydraulic connections between the two units. This allows the two units to require only one pressure-resistant connection, apart from the pressureless connections to the hydraulic fluid reservoir.

[0128] A particular advantage of the exemplary brake system with a pressure medium reservoir 4 with at least three reservoir chambers 401, 402, 403 is explained below.

[0129] In principle, a braking system is conceivable which is similar to the braking system of Fig. 1 This corresponds to the previous system with the difference that the pressure medium reservoir 4 comprises (only) the two reservoir chambers 401 and 402, and the isolating valve 23 is connected to the line 42 or the first reservoir chamber 401 on the pressure medium reservoir side. This means that the pressure chamber 37 of the first pressure source 5 is connected to the same reservoir chamber 401 via a parallel connection of check valve 53 and isolating valve 23 (possibly with check valve 72). This brake system has the disadvantage that in the event of a leak at the rear axle (rear) when the brake system is switched off (de-energized), reservoir chamber 401 of the pressure medium reservoir 4 would empty. When the brake system is started, the low pressure medium level in the pressure medium reservoir could then be detected via the level measuring device 50, and the circuit isolating valve 40 could be closed to separate the circuits. The rear axle circuit I (including...Reservoir chamber 402 would be empty and fail after just a few braking maneuvers due to the leak at the rear axle. At the front axle, only the hydraulic fluid volume in pressure chamber 37 of the first pressure source 5 is then available; reservoir chamber 401 is already empty. With each braking maneuver, a small volume of hydraulic fluid is lost through the usually unavoidable leakage of the circuit separator valve 40 and the two outlet valves 7c and 7d in the defective rear axle circuit I. After a number of braking maneuvers, the achievable braking effect of the front axle circuit II thus decreases continuously until it fails. Depending on the leakage conductance of the outlet valves and the circuit separator valve, the required operating time (or driving distance) of the braking system after a leak in the parked state is therefore not achieved.

[0130] The described disadvantage is eliminated by the braking system according to the invention.

[0131] In this case, the pressure medium reservoir 4 includes an additional third reservoir chamber 403, which is separated from the first and second reservoir chambers 401, 402 by at least one bulkhead, wherein the first pressure source 5 or the brake supply line 13 or the second line section 13b is connected to the third reservoir chamber 403 via the electrically actuated isolating valve 23.

[0132] The pressure equalization of the wheel brakes to the atmosphere is thus realized via the separating valve 23 and a separate (third) reservoir chamber 403 in the pressure medium reservoir 4.

[0133] In the event of a leak at the rear axle (rear) while the vehicle is switched off (parked), only the third reservoir chamber 403 empties in the exemplary brake system. The two main chambers (first and second reservoir chambers 401, 402) are separated from the wheel brake lines (wheel connections 9a-9d) by (spring-loaded) check valves or normally closed switching valves and therefore cannot empty. When the brake system is started, the level measuring device 50 detects the low pressure fluid level in the pressure fluid reservoir 4 and closes the circuit isolation valve 40. After a few braking maneuvers, the rear axle circuit I will be empty due to the leak at the rear axle (rear) and will fail.At the front axle, the hydraulic fluid volume in pressure chamber 37 of the first pressure source 5 is available, and to compensate for leakage into the defective rear axle brake circuit I via circuit isolating valve 40 and outlet valves, the hydraulic fluid volume of the first reservoir chamber 401 is available. With appropriate dimensioning of the hydraulic fluid reservoir 4, continued operation over the required time and distance can thus be ensured.

[0134] The third compartment 403 of container 4 can be very small. The installation space for container 4 does not increase, or only increases slightly.

[0135] In the event of a leak, a fully functional dual-circuit operation with reserve volume in tank 4 is immediately possible after closing the circuit separation valve 40. No leak detection or conditioning routines are required.

[0136] The duration of dual-circuit operation is limited only by leakage from the circuit isolating and outlet valves, as well as the chamber volume of the corresponding reservoir chamber 401 or 402. Depending on the location of the leak (e.g., 8a, 8b, 8c, 8d), the reservoir chamber (401 or 402) connected to the leak point after the circuit isolating valve 40 closes is quickly emptied. The other reservoir chamber (402 or 401) remains full. However, a small volume of hydraulic fluid is lost with each braking action due to minimal leakage from the circuit isolating valve 40 (and the outlet valves 7c, 7d if the front axle circuit I is intact). This limits the duration of dual-circuit operation.

[0137] In Fig. 2 Figure 1 schematically shows a second embodiment of a braking system according to the invention for a motor vehicle. The second embodiment largely corresponds to the first embodiment. Therefore, the differences between the embodiments will be discussed below.

[0138] For example, a pressure medium storage tank 4 is divided into three tank chambers 401, 402, and 403 by two bulkheads. The pressure medium storage tank 4 comprises, for example, a first bulkhead 421 and a second bulkhead 422, wherein the first tank chamber 401 is separated from the third tank chamber 403 by the first bulkhead 421, and the first tank chamber 401 is separated from the second tank chamber 402 by the second bulkhead 422. The third tank chamber 403 is smaller than the first tank chamber 401 and smaller than the second tank chamber 402 with respect to its capacity.

[0139] For example, the first pressure source 5 comprises only one hydraulic connection, which is connected to the system pressure line section 38. The system pressure line section 38 (and thus the pressure chamber 37) is connected on the one hand via the separating valve 23 and the line section 43 to the third reservoir connection 413 of the pressure medium reservoir 4, and thus to the third reservoir chamber 403, and on the other hand via the check valve 53 and the (suction) line section 42 to the first reservoir connection 411 of the pressure medium reservoir 4, and thus to the first reservoir chamber 401. For example, no check valve is connected in parallel to the separating valve 23.

[0140] The three container chambers 401, 402, 403 and at least one overflow are arranged and designed in such a way that a (direct) overflow of pressure medium from the third container chamber 403 is only possible into the first container chamber 401 (and not into the second container chamber 402).

[0141] By means of line section 38, pressure source 5 or pressure chamber 37 is further connected to the hydraulic connection 60 of the first assembly 100, which is connected via the pressure-resistant hydraulic connecting element 80 to the hydraulic connection 61 of the second assembly 200. Connection 80 is also, according to this embodiment, the only hydraulic pressure connection, in particular the only hydraulic connection, between the first and the second assembly.

[0142] In In the second assembly unit 200, the pressure sensor 19 is arranged, for example, in brake circuit I.

[0143] Advantageously, the second assembly unit includes an internal pressure medium reservoir 75, to which the second pressure source 2 is hydraulically connected on the suction side and which, in turn, is hydraulically connected to the second reservoir chamber 402 for the supply of pressure medium. The internal pressure medium reservoir 75 allows pressure medium to be stored for suction by the second pressure source 2, thus enabling suction with lower resistance, especially at low temperatures.

Claims

1. A brake system for a motor vehicle for at least four hydraulically actuatable wheel brakes (8a-8d), comprising one electrically actuatable inlet valve (6a-6d) per wheel brake, a first electrically actuatable pressure source (5), and a second electrically actuatable pressure source (2), wherein the first pressure source (5) and the second pressure source (2) are connected to a brake supply line (13) to which the at least four inlet valves (6a-6d) are attached, a pressure medium storage reservoir (4) with a first reservoir chamber (401) and a second reservoir chamber (402), wherein the first pressure source (5) is hydraulically connected to the first reservoir chamber (401), and wherein the second pressure source (2) is hydraulically connected to the second reservoir chamber (402), characterised in that the pressure medium storage reservoir (4) comprises a third reservoir chamber (403) and the first pressure source (5) is connected to the third reservoir chamber (403) of the pressure medium storage reservoir (4) via an electrically actuatable first separation valve (23).

2. The brake system of claim 1, characterised in that the three reservoir chambers (401, 402, 403) are separated from each other by bulkheads (421, 422).

3. The brake system of claim 1 or 2, characterised in that the third reservoir chamber (403) is designed so as to be smaller than the first reservoir chamber (401) and smaller than the second reservoir chamber (402).

4. The brake system of any one of the preceding claims, characterised in comprising one electrically actuatable outlet valve (7a-7d) per wheel brake, wherein the outlet valves (7a-7d) are designed so as to be closed when de-energised and are connected to the second reservoir chamber (402).

5. The brake system of any one of the preceding claims, characterised in that an electrically actuatable circuit separation valve (40), which is in particular open when de-energised, is arranged in the brake supply line (13) such that, when the circuit separation valve (40) is closed, the brake supply line (13) is hydraulically separated into a first line section (13a) and a second line section (13b), wherein the first line section (13a) is hydraulically connected to the second pressure source (2) and to at least two of the at least four inlet valves (6a, 6b), and the second line section (13b) is hydraulically connected to the first pressure source (5) and to the others, in particular at least two, of the at least four inlet valves (6c, 6d).

6. The brake system of any one of the preceding claims, characterised in that the first pressure source (5) is connected to the brake supply line (13) via an electrically actuatable second separation valve (26), which is in particular open when de-energised.

7. The brake system of any one of the preceding claims, characterised by a first structural unit (100), in which the first electrically actuatable pressure source (5) is arranged, and a second structural unit (200), in which the second electrically actuatable pressure source (2) and the electrically actuatable inlet valves are arranged, wherein the pressure medium storage reservoir (4) is arranged on the first structural unit (100).

8. The brake system of claim 7, characterised in that the first structural unit (100) and the second structural unit (200) are connected to each other by at most one pressure-resistant hydraulic connecting element (80).

9. The brake system of claim 7 or 8, characterised in that the first structural unit (100) comprises a first hydraulic port for connection to the pressure medium storage reservoir (4), in particular to the first reservoir chamber (401), a third hydraulic port for connection to the pressure medium storage reservoir (4), in particular to the third reservoir chamber (403), and a second hydraulic port (60) for connection to the second structural unit (200), wherein the second hydraulic port (60) is connected to the hydraulic connecting element (80).

10. The brake system of claim 9, characterised in that the first structural unit (100) does not comprise any further hydraulic port.

11. The brake system of any one of claims 9 or 10, characterised in that the first pressure source (5), in particular for actuating the at least four wheel brakes (8a-8d), is connected to the second hydraulic port (60).

12. The brake system of any one of claims 7 to 11, characterised in that the first separation valve (23) is arranged in the first structural unit (100).

13. The brake system of any one of claims 7 to 12, characterised in that the second structural unit (200) comprises at least four hydraulic wheel ports (9a-9d) for connection to the wheel brakes (8a-8d), a first hydraulic port (62) for connection to the pressure medium storage reservoir (4), in particular the second reservoir chamber (402), and a second hydraulic port (61) for connection to the first structural unit (100), wherein the second hydraulic port (61) is connected to the hydraulic connecting element (80).

14. The brake system of any one of claims 7 to 13, when dependent on claim 5, characterised in that the circuit separation valve (40) is arranged in the second structural unit (200).

15. The brake system of any one of claims 7 to 14, when dependent on claim 6, characterised in that the second separation valve (26) is arranged in the second structural unit (200).

16. The brake system of any one of the preceding claims with at least four wheel ports (9a-9d) for the at least four wheel brakes (8a-8d), characterised in that, in a de-energised state of the brake system, both the first reservoir chamber (401) is hydraulically separated from the wheel ports (9a-9d) and the second reservoir chamber (402) is hydraulically separated from the wheel ports (9a-9d).

17. The brake system of any one of the preceding claims, characterised in that the first pressure source (5) is connected to the first reservoir chamber (401) via a non-return valve (53) opening towards the first pressure source (5).

18. The brake system of any one of the preceding claims, characterised in that the three reservoir chambers (401, 402, 403) and at least one overflow are arranged and designed such that overflow of pressure medium from the third reservoir chamber (403) is possible only into the first reservoir chamber (401).