CN105292093B

CN105292093B - Brake system for a vehicle and method for operating a brake system for a vehicle

Info

Publication number: CN105292093B
Application number: CN201510396613.6A
Authority: CN
Inventors: S.施特伦格特
Original assignee: Robert Bosch GmbH
Current assignee: Robert Bosch GmbH
Priority date: 2014-07-09
Filing date: 2015-07-08
Publication date: 2020-06-05
Anticipated expiration: 2035-07-08
Also published as: CN105292093A; DE102014213354A1

Abstract

The invention relates to a brake system for a vehicle, comprising a master brake cylinder (10), a brake fluid reservoir (12), a first brake circuit (16) and a second brake circuit (18), wherein a first wheel brake cylinder (20) associated with the first brake circuit (16) is connected to the master brake cylinder (10) by means of at least one first separating valve (28) and a second wheel brake cylinder (22) associated with the second brake circuit (18) is connected to the master brake cylinder (10) by means of at least one second separating valve (30), wherein the first wheel brake cylinder (20) is connected to the brake fluid reservoir (12) by means of at least one continuously adjustable first valve (32) and the second wheel brake cylinder (22) is connected to the brake fluid reservoir (12) by means of at least one continuously adjustable second valve (34), and wherein a third wheel brake cylinder (24) associated with the first brake circuit (16) is connected to the brake fluid reservoir (12) by means of at least one first reversing valve (36) and a first high-pressure switch (18) A valve (38) is connected to the master brake cylinder (10) and a fourth wheel brake cylinder (26) associated with the second brake circuit (18) is connected to the master brake cylinder (10) via at least one second switching valve (40) and a second high-pressure switching valve (42). The invention also relates to a method for operating a brake system of a vehicle.

Description

Brake system for a vehicle and method for operating a brake system for a vehicle

Technical Field

The present invention relates to a brake system for a vehicle. The invention further relates to a method for operating a brake system of a vehicle.

Background

DE 102009001401 a1 describes a brake system for a vehicle, a method for operating a brake system for a vehicle and a method for producing a brake system for a vehicle. Each brake system comprises a first brake circuit connected to the master brake cylinder and a second brake circuit connected to the master brake cylinder and the brake fluid reservoir. The first brake circuit and the second brake circuit each have two wheel brake cylinders. In addition, the first brake circuit comprises a directional control valve and a high-pressure switching valve, while the second brake system is connected to the master brake cylinder via a separating valve and to the brake fluid reservoir via a continuously variable valve.

Disclosure of Invention

The invention provides a brake system for a vehicle and a method for operating a brake system of a vehicle.

The invention proposes a possibility for implementing a brake system in which a driver can brake directly into a third wheel brake cylinder and into a fourth wheel brake cylinder by actuating a brake actuating element connected to a master brake cylinder of the respective brake system. The driver thus feels a reaction force that meets the criteria during his operation of the brake operating element. At the same time, due to the achieved separability of the first and second wheel brake cylinders (by closing the first and second separating valves), the brake fluid can be prevented from moving from the master brake cylinder into the first and second wheel brake cylinders themselves when the brake actuating element is strongly actuated. As explained in detail below, at least one brake pressure prevailing in the first wheel brake cylinder and/or the second wheel brake cylinder can thus be regulated independently of the internal pressure in the master brake cylinder or independently of the actuation of the brake actuating element.

The invention also provides a brake system which can be advantageously used for vehicles with an X brake circuit distribution (X-Bremskreisuefteilung). The advantages described in the preceding paragraph can also be used for this vehicle type/motor vehicle type.

In an advantageous embodiment of the brake system, a first supply line of the brake system extends from the first pressure chamber of the master brake cylinder to the first separating valve, and the first switchover valve and the first high-pressure switching valve are connected parallel to one another at a first branch point in the first supply line. Alternatively or additionally, a second supply line of the brake system may also extend from the second pressure chamber of the master brake cylinder to the second separating valve, and the second switchover valve and the second high-pressure switching valve may be connected parallel to one another at a second branch point in the second supply line. In both cases, at least one brake pressure in the first wheel brake cylinder and/or in the second wheel brake cylinder can be increased by operating the first pump and/or the second pump.

In particular, in such a design of the brake system, a brake force buildup can be brought about by the operation of the first pump and/or the second pump and without a (typical) brake booster (Bremsskrafvertst ä rker). The necessity of equipping the respective brake system with a brake booster, for example a vacuum brake booster, is thus eliminated.

In a further advantageous embodiment of the brake system, a first suction line of the brake system extends from the brake fluid reservoir to the continuously adjustable first valve, and the suction side of the first pump of the brake system is connected to a third branch point located in the first suction line. Likewise, a second suction line of the brake system can also extend from the brake fluid reservoir to a continuously adjustable second valve, and the suction side of a second pump of the brake system can be connected to a fourth branch point located in the second suction line.

Advantageously, a first line can extend from the first separating valve to the first wheel brake cylinder, and the delivery side of the first pump and the continuously adjustable first valve can be connected to the first line. Accordingly, it is also advantageous if a second line extends from the second separating valve to the second wheel brake cylinder, and the delivery side of the second pump and the continuously adjustable second valve are connected to the second line.

The first wheel inlet valve and the first wheel outlet valve are preferably connected to the third wheel brake cylinder. Accordingly, the second wheel inlet valve and the second wheel outlet valve can also be connected to the fourth wheel brake cylinder.

In an advantageous development, the first storage chamber of the brake system is connected to the third wheel brake cylinder via a first wheel outlet valve and to the first high-pressure switching valve via a first pressure relief valve (Ü berdruckventil). accordingly, it is also advantageous if the second storage chamber of the brake system is connected to the fourth wheel brake cylinder via a second wheel outlet valve and to the second high-pressure switching valve via a second pressure relief valve.

Furthermore, the suction side of a third pump of the brake system can be connected to the first pressure relief valve and to the first high-pressure switching valve, and the delivery side of the third pump can be connected to the first directional control valve and to the first wheel inlet valve. In a further advantageous development, the suction side of a fourth pump of the brake system is connected to the second pressure relief valve and to the second high-pressure switching valve, and the delivery side of the fourth pump is connected to the second directional control valve and to the second wheel inlet valve.

A corresponding method for operating a brake system of a vehicle also provides the aforementioned advantages. The method for operating a brake system of a vehicle can be extended according to the above-described embodiments of the brake system.

Drawings

Further features and advantages of the invention are explained below with the aid of the figures. In the drawings:

FIG. 1 shows a schematic view of an embodiment of a braking system; and is

Fig. 2 shows a flow chart for explaining an embodiment of a method for operating a brake system of a vehicle.

Detailed Description

Fig. 1 shows a schematic representation of an embodiment of a brake system.

The brake system schematically illustrated in fig. 1 can be used in a vehicle/motor vehicle, for example in an electric or hybrid vehicle. It should be noted that the usability of the brake system is not limited to a certain vehicle type/motor vehicle type. Although the brake system described below can be used particularly advantageously in vehicles with an X brake circuit distribution, the advantages described below are also achieved in vehicles with a parallel brake circuit distribution.

The brake system illustrated schematically in fig. 1 comprises a master cylinder 10 and a brake fluid reservoir 12, the brake fluid reservoir 12 being understood as the volume of the brake system in which (usually) atmospheric pressure prevails, the brake fluid reservoir 12 can be connected to the master cylinder 10, for example, by means of at least one vent hole (Schn ü ffelbohrung), a brake actuating element 14, for example a brake pedal, can also be connected to the master cylinder 10 (directly or indirectly), the constructability of the brake system is not limited to a specific type of brake actuating element.

The brake system has two

brake circuits

16 and 18 and four wheel brake cylinders 20 to 26. First wheel brake cylinder 20 of the brake system associated with first brake circuit 16 is connected to master brake cylinder 10 via at least one first isolating valve 28. Second wheel brake cylinder 22 of the brake system associated with second brake circuit 18 is also connected to master brake cylinder 10 via at least one second isolating valve 30. Furthermore, the first wheel brake cylinder 20 associated with the first brake circuit 16 is connected to the brake fluid accumulator 12 via at least one continuously adjustable first valve 32, and the second wheel brake cylinder 22 associated with the second brake circuit 18 is connected to the brake fluid accumulator 12 via at least one continuously adjustable second valve 34. In contrast, third wheel brake cylinder 24 of the brake system associated with first brake circuit 16 is connected to master brake cylinder 10 via at least one first switchover valve 36 and a first high-pressure switching valve 38. Correspondingly, fourth wheel brake cylinder 26 associated with second brake circuit 18 is also connected to master brake cylinder 10 via at least one second switchover valve 40 and a second high-pressure switching valve 42.

Advantageously, the brake system illustrated in fig. 1 has a mutually parallel arrangement of first brake circuit 16 and second brake circuit 18. This simplifies the use of the brake system for vehicles with an X brake circuit profile. For this purpose, both first wheel brake cylinder 20 associated with first brake circuit 16 and second wheel brake cylinder 22 associated with second brake circuit 18 may be arranged on a common axle of the vehicle. Preferably, the common axis of the first wheel brake cylinder 20 and the second wheel brake cylinder 22 is the front axis of the vehicle. As an alternative thereto, the first wheel brake cylinder 20 and the second wheel brake cylinder 22 can also be situated jointly on the rear axle of the vehicle.

By closing first separating valve 28 and/or closing second separating valve 30, when brake actuating element 14 is actuated by the driver, a displacement of brake fluid from master brake cylinder 10 into first wheel brake cylinder 20 itself associated with first brake circuit 16 and/or into second wheel brake cylinder 22 itself associated with second brake circuit 18 can be reliably prevented. This case can also be expressed as: by closing first separating valve 28 and/or closing second separating valve 30, first wheel brake cylinder 20 and/or second wheel brake cylinder 22 can be disengaged from master brake cylinder 10. This ensures that at least one brake pressure prevailing in first wheel brake cylinder 20 and/or second wheel brake cylinder 22 can be determined independently of the operation of at least one master brake cylinder internal pressure and/or brake actuating element in master brake cylinder 10. In particular, at least one brake pressure in first wheel brake cylinder 20 and/or in second wheel brake cylinder 22 can be reduced by an at least temporary opening of continuously controllable first valve 32 (while first separating valve 28 is simultaneously closed) and/or by an at least temporary opening of continuously controllable second valve 34 (while second separating valve 30 is simultaneously closed). The degradability of at least one brake pressure in first wheel brake cylinder 20 and/or in second wheel brake cylinder 22 can be used in particular to blank (verbleden) a generator braking torque of a generator (not shown). The brake system shown in fig. 1 can therefore be used particularly advantageously in a vehicle for regenerative braking. In particular, it can be ensured by the brake system that the driver braking request predefined by the actuation of the brake actuating element 14 is not exceeded despite the at least temporary use of the generator for regenerative braking. The braking system thus improves the driving comfort of its users during regenerative braking and thus promotes the sale of energy-efficient and low-emission vehicles.

At the same time, it is ensured in the brake system that the user, by actuating brake actuating element 14, can brake into third wheel brake cylinder 24 associated with first brake circuit 16 and into fourth wheel brake cylinder 26 associated with second brake circuit 18 via at least

valves

36, 38, 40 and 42. Therefore, the driver has a brake operating feel (pedal feel) that meets the criteria during the operation of brake actuating element 14 even after first wheel brake cylinder 20 and/or second wheel brake cylinder 22 is disengaged. It is therefore not necessary to equip the brake system with a simulator (pedal simulator). Instead, the third wheel brake cylinder 24 and the fourth wheel brake cylinder 26 fulfill both a brake function and a "simulator function". By eliminating the need for equipping the brake system with a simulator due to the versatility of the third wheel brake cylinder 24 and the fourth wheel brake cylinder 26, the weight of the brake system can be reduced and the space structure on a vehicle equipped with the brake system can be saved. Additionally, the cost of the simulator is eliminated in the manufacture of the brake system shown in fig. 1.

In the embodiment of fig. 1, a first supply line 44 of the brake system extends from a first pressure chamber of master brake cylinder 10 to first separating valve 28. The first direction switching valve 36 and the first high-pressure switching valve 38 are connected in parallel to each other at a first branch point 46 in the first supply line 44. For example, a branched intermediate conduit 48 may extend from the first branch point 46 to the first direction valve 36 and the first high pressure switch valve 38. A second supply line 50 of the brake system leads from a second pressure chamber of master brake cylinder 10 to second separating valve 30. The second direction switching valve 40 and the second high-pressure switching valve 42 are connected in parallel to each other at a second branch point 52 in the second supply line 50. A branched intermediate line 54 may also extend from the second branch point 52 to the second direction valve 40 and to the second high pressure switching valve 42. Thus, it is reliably ensured that: neither the movement of brake fluid from master cylinder 10 to first switchover valve 36 or first high-pressure switching valve 38 is prevented by the closing of first separating valve 28, nor the movement of brake fluid from master cylinder 10 to second switchover valve 40 or second high-pressure switching valve 42 is prevented by the closing of second separating valve 30.

Preferably, the brake system also has a first suction line 56 which extends from the brake fluid reservoir 12 to the continuously adjustable first valve 32. Furthermore, the brake system can have a first pump 58, the suction side of which first pump 58 is connected to a third branching point 60 in first suction line 56. It is also advantageous if a second suction line 62 of the brake system extends from the brake fluid reservoir 12 to the continuously adjustable second valve 34, and the suction side of a second pump 64 of the brake system is connected to a fourth branch 66 in the second suction line 62. First pump 58 and/or second pump 64 in this case effect an increase in at least one brake pressure in first wheel brake cylinder 20 and/or second wheel brake cylinder 22. The brake pressure increase in first wheel brake cylinder 20 and/or second wheel brake cylinder 22, which can be brought about by operating first pump 58 and/or second pump 64, can be used, for example, to suppress a generator braking torque that decreases over time.

Likewise, the brake pressure increase that can be brought about can also be used for brake force boosting. When the driver brakes into the third wheel brake cylinder 24 and into the fourth wheel brake cylinder 26 by actuating the brake actuating element 14 without applying any force, at least one brake pressure in the first wheel brake cylinder 20 and/or in the second wheel brake cylinder 22 can be built up (after the first and/or second separating

valve

28, 30 has been closed) by operating the first and/or

second pump

58, 64, which is significantly higher than the build-up pressure that arises in the third wheel brake cylinder 24 and/or in the fourth wheel brake cylinder 26. It is therefore not necessary to equip the brake system with a brake booster, for example a vacuum brake booster. Alternatively, first pump 58 and/or second pump 64 may fully satisfy the reduced brake booster function. In particular, the driver only needs to apply a relatively low driver braking force to brake actuating element 14, despite the relatively large brake pressure increase in first wheel brake cylinder 20 and/or in second wheel brake cylinder 22.

By simplifying the brake booster, such as in particular a vacuum brake booster, on the brake system, the space requirement of the brake system is reduced, but also its weight and production costs. In particular, when a vehicle equipped with the brake system does not have an internal combustion engine or does not use the internal combustion engine for a long period of time, the brake system without a brake booster ensures that the driver also has a comfortable brake operation feeling (pedal feeling). The necessity of vacuum supply is also eliminated because the brake system does not require a vacuum brake booster for ensuring good brake operation feeling. It should furthermore be noted that the advantageous design of the brake system enables a vacuum pump of a compact design, which is often still required on the vehicle and disadvantageously increases the emissions of the vehicle.

In the brake system of fig. 1, a first line 68 extends from first separating valve 28 to first wheel brake cylinder 20. The delivery side of the first pump 58 and the continuously adjustable first valve 32 are connected to a first line 68. For example, the intermediate line 70 branches off to the delivery side of the first pump 58 and to the continuously adjustable first valve 32, wherein the intermediate line 70 opens into the first line 68. Correspondingly, the brake system also has a second line 72, which second line 72 extends from the second separating valve 30 to the second wheel brake cylinder 22. The delivery side of the second pump 64 and the continuously adjustable second valve 34 are connected to a second line 72. This is also achieved by an intermediate line 74 branching off into the second pump 64 and the continuously adjustable second valve 34, said intermediate line 74 leading into the second line 72.

The brake system may also have a first wheel inlet valve 76 and a first wheel outlet valve 78, which are connected to the third wheel brake cylinder 24 (for example via a branched intermediate line 80). Accordingly, second wheel inlet valve 82 and second wheel outlet valve 84 may also be connected to fourth wheel brake cylinder 26 (e.g., via a branched intermediate line 86). For a vehicle axle equipped with the third wheel brake cylinder 24 and the fourth wheel brake cylinder 26, a typical brake pressure regulation is thus possible via the

wheel inlet valves

76 and 82 and the

wheel outlet valves

78 and 84. In particular, ABS control can be performed simply on each axis. (conventional ESP function can also be achieved since each vehicle axle is equipped with a reversing

valve

36 and 40 and a high pressure switching valve 38 and 42)

In the embodiment of fig. 1, the first storage chamber 88 of the brake system is also connected to the third wheel brake cylinder 24 via the first wheel outlet valve 78 and to the first high-pressure switching valve 38 via a first pressure relief valve 90. For example, an intermediate line 92 extends from the first high pressure switching valve 38 to the first wheel outlet valve 78, wherein the first pressure relief valve 90 is housed within the intermediate line 92. The first storage chamber 88 may be connected to a branch point 94 in the intermediate pipe 92. Accordingly, the brake system of fig. 1 also has a second storage chamber 96, which second storage chamber 96 is connected to the fourth wheel brake cylinder 26 via the second wheel outlet valve 84 and to the second high-pressure switching valve 42 via a second pressure relief valve 98. An intermediate line 100, in which a second pressure relief valve 98 is arranged, can also extend from the second high-pressure switching valve 42 to the second wheel outlet valve 84, wherein the second storage chamber 96 is connected to a branching point 101 in the intermediate line 100.

In the brake system of fig. 1, the suction side of the third pump 102 of the brake system is connected to the first relief valve 90 and to the first high-pressure switching valve 38. The delivery side of the third pump 102 is connected to the first diverter valve 36 and to the first wheel inlet valve 76. Third pump 102 may be placed in an intermediate line 104, intermediate line 104 leading on a first side into intermediate line 92, and a second side of intermediate line 104 connected to a branch point 106 in an intermediate line 108 from first directional valve 36 to first wheel inlet valve 76. The suction side of the fourth pump 110 of the brake system is connected in the brake system of fig. 1 to the second pressure relief valve 98 and to the second high-pressure switching valve 42. The delivery side of the fourth pump 110 is hydraulically connected to the second directional valve 40 and the second wheel inlet valve 82, or to an intermediate line 112 extending from the second directional valve 40 to the second wheel inlet valve 82. For example, the fourth pump 110 is placed in an intermediate line 114, which intermediate line 114 opens on a first side into the intermediate line 100 and on a second side into the intermediate line 112.

In the embodiment of fig. 1, the four pumps 58, 64, 102 and 110 of the brake system are connected to a common shaft 116 of a pump motor 118. It is not necessary to equip the brake system with a plurality of pump motors. The four pumps 58, 64, 102 and 110 are each designed, for example, as a single-piston pump. The braking system of fig. 1 may therefore be referred to as a four-piston ESP system. It should be noted, however, that the constructability of the brake system is not limited to a certain pump type. For the

pumps

58, 64, 108 and 110, it is therefore also possible to use at least one pump with a different number of pistons, at least one asymmetrical pump and/or at least one gear pump.

For example, the brake system of fig. 1 has a preload sensor 120 connected to first brake circuit 16 and a pressure sensor 122 connected to first wheel brake cylinder 20 and second wheel brake cylinder 22, respectively. But the constructability of the brake system is not limited to certain configurations with pre-pressure sensors 120 or pressure sensors 122. In order to detect a driver braking request or the intensity of the actuation of the brake actuating element 14 by the driver, at least one further brake actuating element sensor 124 can additionally also be used on the brake system. The at least one brake operating element sensor 124 may be, for example, a pedal stroke sensor, a stroke difference sensor, and/or a lever stroke sensor. Driver braking desire may also be detected by other types of sensing devices.

During operation of the brake system, the setpoint braking torque can be determined by the brake actuating element sensor 124 as a function of the actuation strength of the actuation of the brake actuating element 14. In order to achieve the setpoint braking torque desired by the driver, first separating valve 28 and/or second separating valve 30 can be closed, so that the build-up of braking pressure in first wheel brake cylinder 20 and/or in second wheel brake cylinder 22 can be continuously brought about by the operation of first pump 58 and/or second pump 64 until a predefined setpoint braking torque is applied as a sum via the four

wheel brake cylinders

20, 22, 24 and 26 to the respective wheel. Since the driver moves the brake fluid into the third wheel brake cylinder 24 and the fourth wheel brake cylinder 26 by actuating the brake actuating element 14 during the process described here, the driver also has a brake actuating feel (pedal feel) that meets the criteria. At the same time, the brake pressure built up in the first wheel brake cylinder 20 and/or the second wheel brake cylinder 22 is significantly higher than the pressure caused by the driver braking force in the third wheel brake cylinder 24 and in the fourth wheel brake cylinder 26, as a result of which an increase in the braking force can be caused.

When the brake is released, the driver can displace the brake fluid volume from third wheel brake cylinder 24 and fourth wheel brake cylinder 26 back into master brake cylinder 10 again. Accordingly, a reduction in the brake pressure can also be brought about in the first wheel brake cylinder 20 and/or in the second wheel brake cylinder 22 by means of the continuously adjustable first valve 28 and/or the continuously adjustable second valve 30. The driver therefore does not feel: in addition to the brake fluid which is directly caused by the driver braking force moving between the master cylinder 10, the third wheel cylinder 24 and the fourth wheel cylinder 26, the brake fluid is additionally moved in the brake system.

In the event of an emergency braking situation, for example in the event of an emergency braking situation and in the event of a rapid actuation of the brake actuating element 14 by the driver associated therewith, the separating

valves

28 and 30 can remain open. Thus, the driver can also quickly brake in first wheel brake cylinder 20 and second wheel brake cylinder 22 by displacing the volume of master brake cylinder 10. It is not necessary to provide the first and

second pumps

58, 64 for rapid volume delivery in an emergency braking situation. Alternatively, an inexpensive model (Modelle) may be used for

pumps

58 and 64.

For example, it may be checked by at least one brake operating element sensor 124 whether the operation of the brake operating element 14 shows an indication of an emergency/sudden braking situation. In particular, the depression gradient (einrittsgradient) applied during the operation of the brake actuating element 14 can be checked. At least one environmental sensor may also be considered for determining an emergency braking situation. In the event of a defined emergency braking situation, the separating

valves

28 and 30 can be brought into their open state. In this way, the brake system allows optimum utilization of the driver dynamics at high rapid braking demands. Although there is a limited pump dynamics due to the inexpensive pump model, high brake dynamics can also be achieved in this way. After a certain time or when a predefined braking torque is reached, the separating

valves

28 and 30 can be closed, so that a further pressure increase can be brought about by the first pump 58 and the second pump 64.

ABS adjustments may be conventionally made through

wheel inlet valves

76 and 82 and through

wheel outlet valves

78 and 84. For the axles of the first wheel brake cylinder 20 and the second wheel brake cylinder 22, ABS control can also be effected via continuously

controllable valves

32 and 34 and via the brake fluid being discharged into the brake fluid reservoir 12. Advantageous ABS regulation performance (comparable to conventional brake systems) is thus also obtained in the brake system of fig. 1.

The vehicle can be stabilized by means of a standard ESP control system at the

wheel brake cylinders

24 and 26 by means of brake intervention (bremseinengriffe) of the individual wheels. A stabilizing intervention (stabisieregustingriffe) on the

wheel brake cylinders

20 and 22 can be carried out with the separating

valves

28 and 30 closed by the continuously

adjustable valves

32 and 34 and the pumps 58 and 64 (as in conventional brake systems).

Effective pressure build-up capability is achieved by the

directional valves

36 and 40 and the high

pressure switching valves

38 and 42. Continuously

adjustable valves

32 and 34 may also be used for traction slip adjustment (for both axles). The brake system of fig. 1 is therefore suitable without functional disadvantages for front-wheel-drive, rear-wheel-drive and all-wheel-drive vehicles. Due to the typical valve arrangement, partial effectiveness as a function of a combination of driver operation and assistance by the regulating unit can also be achieved. All known partially effective functions can thus be carried out without functional restrictions.

Regenerative braking can be carried out by the generator, so that (when the separating

valves

28 and 30 are closed) brake fluid can be discharged into the brake fluid reservoir 12 via the continuously

controllable valves

32 and 34 and a corresponding braking torque of the generator is required. During regenerative braking, the driver also has a brake actuation feel (pedal feel) that is in accordance with the standard, due to its connection to the third wheel brake cylinder 24 and the fourth wheel brake cylinder 26. Due to the pronounced over-braking of the

wheel brake cylinders

20 and 22, a relatively large, reducible hydraulic braking torque is available for regenerative braking. Thus ensuring high regeneration efficiency.

The

valves

28, 30, 36, 40, 76 and/or 82 are preferably normally open valves, a normally closed configuration is preferred for the

valves

38, 42, 78 and/or 84, the driver can thus brake into all the wheel brake cylinders 20 to 26 in a mechanical backup solution (R ü ckfallebene) (in the case of no flow through the valves) without any augmentation, and a sufficient minimum retardation is achieved in this way.

The braking system of fig. 1 thus integrates the following advantages: comfortable brake operating feel (pedal feel), low manufacturing costs, light weight, low space construction requirements, high safety and suitability for X brake circuit distribution. Furthermore, the brake system can also be constructed as a compact component.

The method, which will be further described, may be performed, for example, by the aforementioned brake system. The method is not limited to just this type of brake system.

In method step S1, during the actuation of the brake actuating element connected to the master brake cylinder, the brake fluid is prevented from being displaced from the master brake cylinder of the brake system into a first wheel brake cylinder of the brake system assigned to a first brake circuit of the brake system and into a second wheel brake cylinder of the brake system assigned to a second brake circuit of the brake system. This is achieved by closing the first separating valve and closing the second separating valve, wherein the first wheel brake cylinder is connected to the master brake cylinder via the first separating valve and the second wheel brake cylinder is connected to the master brake cylinder via the second separating valve. At least one brake pressure in the first wheel brake cylinder and/or in the second wheel brake cylinder can thus be set independently of the master brake cylinder internal pressure in the master brake cylinder and independently of the actuation of the brake actuating element by the driver. The method steps for adjusting the brake pressure in the first wheel brake cylinder and/or in the second wheel brake cylinder are also described below.

Method step S2 is performed simultaneously with method step S1. In method step S2, the first directional control valve and the first high-pressure switching valve and the second directional control valve and the second high-pressure switching valve are controlled in such a way that the brake fluid volume pressed out of the master brake cylinder by actuating the brake actuating element is displaced at least partially into the third wheel brake cylinder and into the fourth wheel brake cylinder, wherein the third wheel brake cylinder of the brake system assigned to the first brake circuit is connected to the master brake cylinder by the first directional control valve and the first high-pressure switching valve, and the fourth wheel brake cylinder of the brake system assigned to the second brake circuit is connected to the master brake cylinder by the second directional control valve and the second high-pressure switching valve. Thus, despite the disengagement of the first wheel brake cylinder and the second wheel brake cylinder from the master brake cylinder (caused by method step S1), the driver still has a brake actuating feel (pedal feel) that is in accordance with the standard during the actuation of the brake actuating element. In particular, the driver is therefore unaware of the regulation of at least one brake pressure in the first wheel brake cylinder and/or in the second wheel brake cylinder independently of the master brake cylinder internal pressure and the actuation of the brake actuating element. For example, in method step S3, which is executed during method steps S1 and S2, the brake pressure in the first wheel brake cylinder and/or in the second wheel brake cylinder can be reduced during the actuation of the brake actuating element. This can be achieved by at least temporarily opening a continuously adjustable first valve, by means of which the first wheel brake cylinder is connected to a brake fluid reservoir of the brake system (while the first separating valve remains closed), and/or by at least temporarily opening a continuously adjustable second valve, by means of which the second wheel brake cylinder is connected to the brake fluid reservoir (while the second separating valve remains closed). By reducing the brake pressure in the first wheel brake cylinder and/or in the second wheel brake cylinder, the generator brake torque of the generator, which increases over time, can be blanked for regenerative braking of a vehicle equipped with the brake system, for example.

As an alternative or in addition to method step S3, method step S4 may also be executed during method steps S1 and S2. In method step S4, during the actuation of the brake actuating element, the brake pressure in the first wheel brake cylinder and/or in the second wheel brake cylinder is increased. This takes place by operating a first pump of the brake system, the suction side of which is connected to the brake fluid reservoir (while the first separating valve remains closed), and/or by operating a second pump of the brake system, the suction side of which is connected to the brake fluid reservoir (while the second separating valve remains closed). By increasing the brake pressure in the first wheel brake cylinder and/or in the second wheel brake cylinder, a time-reduced generator braking torque of the generator can be blanked, for example. Furthermore, method step S4 may also be used for brake force boosting. During the non-intensified braking of the driver (due to method step S2) into the third wheel brake cylinder and into the fourth wheel brake cylinder, a significantly increased brake pressure is built up in the first wheel brake cylinder and/or the second wheel brake cylinder in this case by method step S4. By method step S4, a brake force boost can thus be achieved on a brake system without a brake booster.

Method step S0 may also be performed before method steps S1 and S2 in an alternative manner. In method step S0, it may be determined whether an emergency braking situation is present (during operation of the brake actuating element by the driver). If it is determined that an emergency braking situation is present, the first and second separating valves can be set to their open state in method step S5. The rapid braking dynamics of the driver in the event of an emergency braking can therefore also be used to build up brake pressure in the first wheel brake cylinder and in the second wheel brake cylinder. This means that, by method step S1, the brake fluid is prevented from being displaced from the master brake cylinder into the first wheel brake cylinder and into the second wheel brake cylinder during the actuation of the brake actuating element only if it is determined that there is no emergency braking situation.

Claims

1. Brake system for a vehicle, having:

a master brake cylinder (10),

a brake fluid reservoir (12);

a first brake circuit (16) which is hydraulically connected at least to the master brake cylinder (10); and

a second brake circuit (18) hydraulically connected to the master brake cylinder (10) and to the brake fluid reservoir (12);

it is characterized in that the preparation method is characterized in that,

a first wheel brake cylinder (20) of the brake system associated with the first brake circuit (16) is connected to the master brake cylinder (10) via at least one first separating valve (28), and a second wheel brake cylinder (22) of the brake system associated with the second brake circuit (18) is connected to the master brake cylinder (10) via at least one second separating valve (30);

a first wheel brake cylinder (20) associated with the first brake circuit (16) is connected to the brake fluid reservoir (12) via at least one continuously adjustable first valve (32), and a second wheel brake cylinder (22) associated with the second brake circuit (18) is connected to the brake fluid reservoir (12) via at least one continuously adjustable second valve (34); and is

A third wheel brake cylinder (24) of the brake system associated with the first brake circuit (16) is connected to the master brake cylinder (10) via at least a first switching valve (36) and a first high-pressure switching valve (38), and a fourth wheel brake cylinder (26) of the brake system associated with the second brake circuit (18) is connected to the master brake cylinder (10) via at least a second switching valve (40) and a second high-pressure switching valve (42).

2. A brake system according to claim 1, wherein a first supply line (44) of the brake system extends from a first pressure chamber of the master brake cylinder (10) to a first separating valve (28) and the first direction valve (36) and the first high-pressure switching valve (38) are connected in parallel to one another at a first separating point (46) in the first supply line (44), and/or a second supply line (50) of the brake system extends from a second pressure chamber of the master brake cylinder (10) to a second separating valve (30) and the second direction valve (40) and the second high-pressure switching valve (42) are connected in parallel to one another at a second separating point (52) in the second supply line (50).

3. Braking system according to claim 1 or 2, wherein a first suction line (56) of the braking system extends from the brake fluid reservoir (12) to the continuously adjustable first valve (32) and the suction side of a first pump (58) of the braking system is connected at a third branch point (60) within the first suction line (56), and/or a second suction line (62) of the braking system extends from the brake fluid reservoir (12) to the continuously adjustable second valve (34) and the suction side of a second pump (62) of the braking system is connected at a fourth branch point (66) within the second suction line (62).

4. A brake system according to claim 3, wherein a first line (68) extends from the first separating valve (28) to the first wheel brake cylinder (20) and a delivery side of the first pump (58) and the continuously adjustable first valve (32) are connected to the first line (68), and/or a second line (72) extends from the second separating valve (30) to the second wheel brake cylinder (22) and a delivery side of the second pump (64) and the continuously adjustable second valve (34) are connected to the second line (72).

5. A brake system according to claim 1 or 2, wherein a first wheel inlet valve (76) and a first wheel outlet valve (78) are connected to the third wheel brake cylinder (24) and/or a second wheel inlet valve (82) and a second wheel outlet valve (84) are connected to the fourth wheel brake cylinder (26).

6. Brake system according to claim 5, wherein a first storage chamber (88) of the brake system is connected to the third wheel brake cylinder (24) via the first wheel outlet valve (78) and to the first high-pressure switching valve (38) via a first pressure relief valve (90), and/or a second storage chamber (96) of the brake system is connected to the fourth wheel brake cylinder (26) via the second wheel outlet valve (84) and to the second high-pressure switching valve (42) via a second pressure relief valve (98).

7. A braking system according to claim 6, wherein a suction side of a third pump (102) of the braking system is connected to the first pressure relief valve (90) and to the first high pressure switching valve (38) and a delivery side of the third pump (102) is connected to the first reversing valve (36) and to the first wheel inlet valve (76), and/or a suction side of a fourth pump (110) of the braking system is connected to the second pressure relief valve (98) and to the second high pressure switching valve (42) and a delivery side of the fourth pump (110) is connected to the second reversing valve (40) and to the second wheel inlet valve (82).

8. Method for operating a brake system of a vehicle, having the following steps:

during the actuation of a brake actuating element (14) connected to a master brake cylinder (10) by closing a first separating valve (28) and closing a second separating valve (30), the movement of brake fluid from the master brake cylinder (10) into a first wheel brake cylinder (20) and into a second wheel brake cylinder (22) of the brake system is prevented, wherein the first wheel brake cylinder (20) is connected to the master brake cylinder (10) via the first separating valve (28), and the second wheel brake cylinder (22) is connected to the master brake cylinder (10) via the second separating valve (30), wherein the first wheel brake cylinder (20) is associated with a first brake circuit (16) of the brake system, and the second wheel brake cylinder (22) is associated with a second brake circuit (18) of the brake system (S1); and is

The first direction switching valve (36) and the first high-pressure switching valve (38) and the second direction switching valve (40) and the second high-pressure switching valve (42) are controlled in this way, such that the brake fluid volume pressed out of the master brake cylinder (10) by actuating the brake actuating element (14) is at least partially displaced into a third wheel brake cylinder (24) and into a fourth wheel brake cylinder (26), wherein a third wheel brake cylinder (24) of the brake system associated with the first brake circuit (16) is connected to the master brake cylinder (10) via the first switching valve (36) and the first high-pressure switching valve (38), and a fourth wheel brake cylinder (26) of the brake system associated with the second brake circuit (18) is connected to the master brake cylinder (10) via the second directional control valve (40) and the second high-pressure switching valve (42) (S2).

9. Method according to claim 8, wherein during the actuation of the brake actuating element (14) the brake pressure in the first wheel brake cylinder (20) and/or in the second wheel brake cylinder (22) is reduced by:

at least temporarily opening a continuously adjustable first valve (32) while keeping the first separating valve (28) closed, wherein the first wheel brake cylinder (20) is connected to a brake fluid reservoir (12) of the brake system via the first valve (32); and/or

At least temporarily opening a continuously adjustable second valve (34) while keeping the second separating valve (30) closed, wherein the second wheel brake cylinder (22) is connected to the brake fluid reservoir (12) via the second valve (34) (S3).

10. Method according to claim 8 or 9, wherein during the actuation of the brake actuating element (14) the brake pressure in the first wheel brake cylinder (20) and/or in the second wheel brake cylinder (22) is increased by:

operating a first pump (58) of the brake system while keeping the first separating valve (28) closed, wherein a suction side of the first pump (58) is connected to the brake fluid reservoir (12); and/or

Operating a second pump (64) of the brake system while keeping the second separating valve (30) closed, wherein a suction side of the second pump (64) is connected to the brake fluid reservoir (12) (S4).

11. Method according to claim 8 or 9, wherein it is determined whether an emergency braking situation exists (S0), and if it is determined that an emergency braking situation exists, the first separating valve (28) and the second separating valve (30) are adjusted into their open state (S5), and only when an emergency braking situation does not exist, the movement of brake fluid from the master brake cylinder (10) into the first wheel brake cylinder (20) and into the second wheel brake cylinder (22) is inhibited during the operation of the brake operating element (14).