DE102010040854A1 - Hydraulic brake system and method of operation - Google Patents

Abstract

Hydraulic brake system and method for operating a hydraulic brake system which has at least one first brake circuit (2a, 2b) which is in hydraulic connection with a master brake cylinder (3) and at least one second brake circuit (4) which is not in hydraulic connection with the master brake cylinder ( 3) stands. The hydraulic brake system also has a booster unit (5) for actuating the master brake cylinder (3), which is in hydraulic connection with the at least one second brake circuit (4). The at least one second brake circuit (4) also has a pressure source (6). A pressure in the at least one first brake circuit (2a, 2b) is set by means of the pressure source (6) and / or by the driver via the booster unit (5) and a pressure in the second brake circuit (4) is set by means of the pressure source (6) .

Description

State of the art

The publication DE 19826346 deals with a device for brake pressure control. The brake pressure regulation device is used in hydraulic brake systems of vehicles and comprises at least one respective sensor for the relative movement between the actuating device and the abutment and / or for the pendulum force introduced into the simulator spring, for the position of a brake piston and for the pressure in the brake circuit or between the control valve and housing. The hydraulic pressure fluid flowing from the pressure supply device via the control valve is fed exclusively into a space of the housing, where on the one hand it pushes the abutment against the stop and on the other hand pressurizes at least one brake piston.

A special feature of hybrid vehicles is the recovery of braking energy by recuperative braking. In this case, an electric motor, usually the electric drive motor of the vehicle, operated as a generator. The electrical energy generated thereby is fed back into a memory. Recuperation reduces the power loss of the vehicle during braking. Recuperation is therefore a measure to reduce consumption and emissions.

The recuperative braking makes high demands on the conventional, based on friction braking system of the vehicle, since the braking effect of recuperation depends on several factors: First, with full (electric) energy storage, the recuperative brake is not available, the entire braking torque must over the Friction brakes are applied to the wheels. Furthermore, recuperative brake systems do not allow braking torques to a standstill via the generator-driven electric motor. During stopping operations, the conventional braking system in the low speed range must compensate for the lost braking effect of the recuperative brake by a higher braking torque. There are also operating conditions in which the hydraulic braking force must be withdrawn in order to achieve a high degree of recuperation. For example, after switching operations, the decoupled generator is displayed again as a recuperative brake, in order to shift the braking action again in the direction of the recuperative brake. In order to keep the total braking torque constant, therefore, the proportion of conventional friction brake must be reduced.

Both operations described above are referred to as "blending". Furthermore, the recuperative braking system must not affect the braking distance. For single systems, points 1 and 2 are left to the driver. The driver takes over the task of the deceleration controller here. If there is no or additional recuperative braking torque, the driver must adjust the conventional braking torque via the pedal so that the desired deceleration is achieved. The required pedal modulations are reasonable, but are not optimal for comfort. From a cost point of view for the brake system, these solutions are optimal because almost no additional effort is required. For higher demands today brake-by-wire brake systems are used. By decoupling the pedal blending the braking torque can be done almost anywhere, the veneering can be done completely unnoticed by the driver. These solutions are an optimal solution in terms of comfort, but are also very expensive.

Disclosure of the invention

The present invention relates to a hydraulic brake system which has at least one first brake circuit and at least one second brake circuit. The at least one first brake circuit is in hydraulic communication with a master brake cylinder, the at least one second brake circuit is not in hydraulic communication with the master brake cylinder. Furthermore, the hydraulic brake system comprises an amplification unit for actuating the master brake cylinder, which is in hydraulic communication with the at least one second brake circuit. Advantageously, by means of the amplification unit, a brake pressure in the at least one second brake circuit can be set via the master brake cylinder. The at least one first brake circuit is always available as emergency brake circuit, since it is advantageously connected to the master cylinder and thus can be operated, even in the presence of a defect, such as the electrical system; This is an important requirement for brake systems in general. Due to the fact that the at least one second brake circuit is not connected to the master brake cylinder, a brake pressure in the at least one second brake circuit can be modulated and / or adjusted, without changes in the pressure conditions in the second brake circuit via the master brake cylinder reacting on the amplification unit, in particular counteracting this can.

According to the invention, the reinforcement unit of the hydraulic brake system has an actuation chamber. The at least one second brake circuit has a pressure source which is in hydraulic communication with said actuation chamber. By means of the pressure source is the Pressure setting in the actuation chamber of the amplification unit. The pressure source is for example a pump. It is advantageous that the pump is both part of the at least one second brake circuit, as well as that with the pump of the second brake circuit, a pressure adjustment in the amplification unit can be done. As a result, a separate pressure supply of the hydraulic actuation unit, that is to say the amplification unit, can be dispensed with. The pump in the second brake circuit thus assumes at least one double function, which is both space-saving and cost-effective.

According to the invention, the at least one second brake circuit of the hydraulic brake system has a first, normally open, hydraulic interrupting means, by means of which the pressure build-up in the actuating chamber is performed. According to the invention, the pressure source is connected to the actuating chamber via the first interruption means hydraulically interruptible. By providing said interrupting means, that is, a pressure build-up valve in the form of a normally open control valve, the pressure build-up by the pump in the actuation chamber of the amplification unit can be effected by controlled and / or controlled connection of the pressure source to the actuation chamber.

Furthermore, the hydraulic brake system in the at least one second brake circuit comprises a second, normally open, hydraulic interrupting means by means of which the pressure reduction takes place in the actuating chamber. The actuation chamber is connected to a hydraulic fluid reservoir via the second interruption means hydraulically interruptible. A pressure reduction in the actuation chamber can be advantageously controlled and / or regulated. The hydraulic fluid reservoir is advantageously the reservoir of the master cylinder, which again keeps the number of components used in the brake system low.

The pump and the master cylinder thus do not require a separate supply of hydraulic fluid.

According to the invention, the suction side of the pressure source is hydraulically connected to the hydraulic fluid reservoir, wherein the suction side is connected via at least a fifth, normally open, interruption means with at least one wheel brake cylinder of the second brake circuit. Due to the fact that at least one wheel brake cylinder and the hydraulic reservoir are connected to the suction side of the pump, there are the advantages that an additional hydraulic accumulator, which otherwise, for example in the context of an ABS control, must absorb volume from the wheel brake cylinder, does not have to be provided , Likewise, the pump does not have to draw volume from the master cylinder, which could affect further brake circuits connected to the master cylinder, but is supplied with hydraulic fluid directly from the hydraulic reservoir. Not least, this makes possible the autarkic design of the at least one second brake circuit, independent in the sense of being decoupled from the master brake cylinder.

Advantageously, the delivery side of the pressure source via the first interrupting means to the actuating chamber is hydraulically connected. Likewise, the delivery side via a third interrupting means, shown here as a pressure relief valve, hydraulically connected to a reservoir. The reservoir is advantageously the hydraulic fluid reservoir of the master cylinder. The delivery side is connected via at least a fourth interrupting means with at least one wheel brake cylinder of the second brake circuit. Through the connection of the pump via the third interrupting means to the reservoir, an overload protection of the second brake circuit can advantageously be represented, with which it can be prevented that damage will occur to the hydraulic unit in an operating situation with an increased pressure on the delivery side of the pump special to the pressure build-up valve and the intake valves of the second brake circuit; an unwanted opening of the same can also be prevented. By connecting the delivery side with the actuation chamber of the amplification unit and with the wheel brakes of the second brake circuit, pressure buildup in the wheel brakes and / or the actuation chamber is possible. This is particularly advantageous with one and the same pressure source possible.

In an advantageous embodiment, the amplification unit has a transmission element which transmits an actuating force produced by the driver and / or the actuating force produced by the pressure source to the master brake cylinder. The provision of such a transmission element allows the common but also separate coupling and or applying the master cylinder by a driver and / or by the pressure source and thus on the amplification unit. By the transmission element is also given a mechanical fallback, in which the driver if necessary alone actuates the master cylinder via the transmission element and brakes in the at least one first brake circuit. Thus, a safe deceleration of the vehicle, for example in case of failure of the brake assist, by the gain unit is possible.

According to the invention, the transmission element ( 15 ) on a reaction disc. A relationship between an actuation path of an input element, for example a Input rod of a brake booster and a force to be applied by a driver for this actuation path depends on the reaction disc, in particular on the deformation of the reaction disc. Said connection has three operating areas jump-in, gain range and / or run-out.

Likewise, a chamber for receiving a reaction disc can be provided in a part of the actuating element. By means of the reaction disc is a pedal feel, so a relationship between a brake pedal operation by the driver and to be applied by him force representable, wherein the displayable areas for generating the pedal feel during brake operation jump-in, gain range and / or run-out include. Advantageously, such a driver in a brake operation, an operating feeling can be taught, as he knows it from conventional pneumatic brake booster ago.

According to the invention, the at least one first brake circuit has at least one wheel brake cylinder, wherein the pressure on the at least one wheel brake cylinder is set based on the pressure produced by the pressure source and / or by the driver via the amplification unit. The pressure setting is carried out by means of a normally open control valve, a normally closed switching valve ( 18 ), a hydraulic accumulator ( 19 ) and / or by means of a pump ( 20 ). By virtue of said components, the at least one first brake circuit is operable as known from conventional return conveyor systems. The pressure, which is applied by the amplifying means for pressure adjustment in the wheel brake cylinder of the at least one first brake circuit - optionally by the actuating chamber alone without the driver - is produced by the pressure source, so the pump of the second brake circuit. This has the advantage that a brake booster can be generated with pumps that are present anyway in the vehicle, for example pumps of the second brake circuit. Likewise, an active pressure build-up in the first and / or second brake circuit can be generated by the pressure source, for example for ACC, ESP control, Lüftspieleinstellung or comfort functions such as brake wiper or Vorbefüllen the brakes in the event of a collision.

The brake system shown, a cost-effective brake system is realized, which can actively build brake pressure, which is independent of vacuum sources, for example from an intake system of an engine or from a vacuum pump and which is thus well suited for electric and / or hybrid vehicles. In addition, a regenerative braking can be carried out in an advantageous manner with the present brake system, wherein the wheel brake pressure in the wheels of the second brake circuit can be adapted to the braking effect of the regenerative braking system. This is particularly advantageous because the driver feels no change in his brake pedal whether the changing hydraulic braking torque component of the second brake circuit, since the second brake circuit is decoupled from the master cylinder and thus from a hydraulic and / or mechanical reaction to the brake pedal.

According to the invention, the first second, fourth and fifth interrupting means of the two brake circuit are normally open control valves and the third interrupting means is a check valve, more precisely a pressure relief valve.

Furthermore, the invention relates to a method for operating a hydraulic brake system. The hydraulic brake system comprises at least a first brake circuit, which is in hydraulic communication with a master cylinder, and at least one second brake circuit which is not in hydraulic communication with the master cylinder. Likewise, the hydraulic brake system comprises an amplifying unit for actuating the master cylinder, which is in hydraulic communication with the at least one second brake circuit. The at least one second brake circuit has a pressure source. By means of the pressure source and / or by the driver, a pressure in the at least one first brake circuit is set via the amplification unit. The pressure in the second brake circuit is adjusted by means of the pressure source. An advantage of this method is that both the pressure in the decoupled from the master cylinder second brake circuit, and the pressure in the coupled first brake circuit via the amplifying unit by means of the same pressure source is set. In the method according to the invention, therefore, the pressure adjustment in the second brake circuit assigned to the pressure source takes place, as well as the adjustment of the gain in the amplification unit with only one pressure source.

In the method according to the invention, the pressure in the actuation chamber is adjusted by means of the pressure source. In this way, a brake booster is advantageously adjustable and thus also variable, since the pressure can be set differently in the actuation chamber when the driver desires to brake request by the driver. As a result, the applied by the actuating chamber support force is variable.

According to the invention, the pressure build-up in the actuating chamber via a first, normally open, hydraulic interrupting means. Thus, the pressure adjustment can be controlled advantageously respectively. Likewise, the pressure reduction takes place in the actuating chamber via a second normally open hydraulic interrupting means.

According to the invention, the master cylinder is actuated by the reinforcing unit, wherein an actuating force acting on the master cylinder, is better applied, more precisely to an input piston of the master cylinder, by the driver and / or by the pressure source ( 6 ) is produced. This makes it clear again, where the actuation force acting on the master cylinder comes from. A separate adjustment of driver power and boost force is possible by means of the pressure source. Because the pressure source (of the second brake circuit) actuates the master brake cylinder, the at least one first brake circuit can also be advantageously supplied with pressure via the master brake cylinder. The functionality of the pressure source in the method according to the invention thus extends - not limited - from a brake booster, a pressure setting / pressure adjustment in the second brake circuit, up to a pressure setting in the first brake circuit. By being able to act independently of the driver, the pump can thus be used for active pressure structures in the existing brake circuits, both in the coupled from the master cylinder, as well as in the decoupled from this.

In an advantageous embodiment, the hydraulic brake system is part of an overall brake system, which has a regenerative braking system in addition to the hydraulic brake system. The braking effect of the hydraulic brake system is adapted in the method according to the invention to the braking effect of the regenerative braking system by adjusting the braking effect, starting from the second brake circuit. In this case, a predetermined total braking torque is set. The default can come from the driver, but also from a system in the vehicle, which controls, regulates and / or coordinates active braking interventions. For this purpose, a control device may be provided. The determination of the braking effect to be set takes place taking into account the braking effect of the at least one first brake circuit, the driver brake command input and the present regenerative braking effect. At least depending on these variables, possibly taking into account the idle travel of the pedal input rod, the hydraulic braking action to be set in the second brake circuit is determined. Thus, a regenerative braking system can be realized in an advantageous manner, in which a predetermined total braking effect without affecting the driver can be kept constant, even if the proportion of the regenerative braking system to the total braking effect should change, for example due to a state of charge of an energy storage or a worse regenerative Braking effect at low or low vehicle speed.

According to the invention, the driver presets the braking request via an input element. Between the input member and a power transmission element for actuating the master cylinder, a distance is provided. If the distance is available, the braking effect may originate from the regenerative braking system alone or from the regenerative braking system together with the second brake circuit. In this case, a particularly high recuperation efficiency is ensured, since the at least one first brake circuit does not contribute to the braking and thus the largest possible proportion of regenerative braking effect can be used. Likewise, a braking is possible in which the at least one first brake circuit is also involved in the regenerative braking.

In a further embodiment, the regenerative braking system acts on that axis of the vehicle to which the wheel brake cylinders of the second brake circuit are to be assigned. Thus, by way of example, the intended braking effect can be kept constant by operating the second brake circuit according to the invention when, for example, the regenerative braking torque changes. A shift of the braking effect from one axis to the other, does not arise.

However, it may also be provided that the regenerative braking system acts on the axle of the vehicle to which the wheel brake cylinders of the at least one first brake circuit are to be assigned or to those axles which belong to the wheels of the at least one first brake circuit and the at least one second brake circuit are working. Keeping constant a predetermined braking effect by operating the second brake circuit according to the invention in these configurations of the brake system can be accompanied by a shift of the braking effect from one axle to the other axle. An associated 'pitching' of the vehicle may occur, but is not necessarily felt to be detrimental.

Further advantageous embodiments of the invention can be found in the dependent claims.

1 shows a schematic representation of the hydraulic brake system according to the invention, which optionally together with a regenerative braking system forms a total braking system. By means of this braking system, the inventive method for operating a hydraulic brake system can be used.

The present invention is concerned with a hydraulic brake system 1 , The hydraulic brake system 1 essentially comprises a brake input element 22 , an amplification unit 5 , by means of which a master cylinder 3 is actuated, a hydraulic unit 21 , as well as connected wheel brake cylinder 13 . 16 , As a reservoir for hydraulic fluid is in the hydraulic brake system 1 a reservoir 10 to disposal. The hydraulic unit 21 can be divided into several brake circuits. A first brake circuit 2a a wheel 16a is assigned, more precisely, a wheel brake cylinder 16a lies, as in 1 shown, in duplicate 2a . 2 B in front.

Furthermore, the hydraulic unit includes 21 a second brake circuit 4 , as well as at least one second brake circuit 4 associated wheel with a wheel brake cylinder 13a , b. In the case of a four-wheeled vehicle, and hence four wheel-brake cylinders, two wheel-brake cylinders, and thus two wheels, may each be the double-executed first brake circuit 2a . 2 B be assigned, as well as two more wheel brakes the second brake circuit 4 be assigned. The wheel brake cylinders 16a , b are therefore the first brake circuits 2a assigned to b, the wheel brake cylinder 13a , b are the second brake circuit 4 assigned.

The first brake circuits 2a and 2 B differ from the second brake circuit 4 in that the first brake circuits 2a and 2 B with the master cylinder 3 to be in hydraulic connection. The second brake circuit 4 is with the master cylinder 3 not connected.

The following is the first brake circuit 2a described, the brake circuit 2 B is identical to the brake circuit 2a is constructed and will not be described separately. The first brake circuit 2a is via a hydraulic line to the master cylinder 3 connected. To the master cylinder 3 is via a normally open control valve 17 a wheel brake cylinder 16a connected. The control valve 17 a check valve is connected in parallel, which is a volume transport from the wheel brake cylinder 16 in the direction of the master cylinder 3 allows. Such a check valve can also be understood as a bypass valve.

Starting from a branch point 23 between control valve 17 and wheel brake cylinders 16 performs a hydraulic connection to a switching valve 18 , The control valve 17 can be understood as an inlet valve, the switching valve 18 as an outlet valve for the wheel brake cylinder 16a ,

Starting from the exhaust valve 18 performs a hydraulic connection to a branching point 24 to the a hydraulic accumulator 25 connected. Next to the hydraulic accumulator 25 and the exhaust valve 18 is at the branch point 24 a pump 20 connected. More specifically, the suction side of the pump 20 with the branch point 24 hydraulically connected. The delivery side of the pump 20 flows into a branching point 26 located in the connection, more precisely in the hydraulic line, between the master cylinder 3 and the already mentioned control valve 17 located.

In addition, one or both of the brake circuits 2a , b a pressure sensor 36 have, inter alia, for monitoring and or control or regulation of the brake system, in particular the first brake circuits 2a and or 2 B , In 1 is the pressure sensor in the brake circuit 2 B located. As I said, the brake circuit 2a have such a pressure sensor, which then between the master cylinder 3 and the control valve 17 is connected.

The following is the second brake circuit 4 described. The second brake circuit 4 is not in hydraulic communication with the master cylinder 3 , Strictly speaking, a hydraulic connection of the second brake circuit 4 with the master cylinder 3 about the reservoir, in open Schnüffelbohrungen possible, meant here, however, that by a pressure build-up on the chambers of the master cylinder 3 no pressure buildup in the second brake circuit 4 he follows. More specifically, the second brake circuit is not with the exhaust ports of the master cylinder 3 connected to the two first brake circuits 2a and 2 B are connected and in no other way directly to the pressure build-up chambers of the master cylinder 3 ,

Central component of the second brake circuit 4 is a hydraulic pump 6 , in 1 shown as a three-piston pump. The pump 6 however, is not limited to this embodiment. Likewise, instead of a pump a differently designed volume delivery unit may be provided, such as multi-piston pumps, asymmetric pumps, gear pumps and more. The hydraulic layout must then be adapted accordingly.

The hydraulic pump 6 has an intake side and a delivery side. Starting from the delivery side of the pump 6 performs a hydraulic connection to a normally open control valve 12a which is a wheel brake cylinder 13a can be assigned. Such a normally open control valve 12a assumes the functionality of an intake valve for the wheel brake cylinder 13a , The inlet valve 12a is a check valve 27a connected in parallel, which supplies a flow of hydraulic fluid from the pump 6 in the direction wheel brake cylinder 13a in derogation. Between the inlet valve 12a and the wheel brake cylinder 13a there is a branch point 28a on which a normally open control valve 14a connected. This normally open control valve 14a assumes the functionality of an exhaust valve for the wheel brake cylinder 13a ,

In the second brake circuit 4 can another wheel with another wheel brake cylinder 13b to be available. Associated with this wheel brake cylinder, the second brake circuit has a second normally open control valve 12b , another normally open control valve 14b , as well as the valve 12b parallel check valve 27b on.

The exhaust valves 14a and 14b are common to the suction side of the hydraulic pump 6 connected. The exhaust valves 14a and 14b both lead to a branching point 29b , which in addition to the valves 14a and 14b also with the suction side of the hydraulic pump 6 in hydraulic connection.

Between the suction side of the hydraulic pump 6 and the branch point 29b is another branch point 30 intended. About the branch point 30 stand the exhaust valves 14a and or 14b via a hydraulic line 32 in hydraulic communication with the reservoir 10 , Thus, the wheel brake cylinders 13a , b on the respective exhaust valves 14a , b with the reservoir 10 hydraulically connectable.

The reservoir 10 takes over the function of the storage chambers in the second brake circuit 25 in the first brake circuit 2a , b. About the said hydraulic connection of the reservoir 10 with the branch point 30 and thus with the suction side of the hydraulic pump 6 , becomes the hydraulic pump 6 the volume of hydraulic fluid provided, which is the hydraulic pump 6 when it is in operation, via the intake valves 12a and or 12b the wheel brake cylinder 13a and or 13b supplies. In this way, with closed exhaust valves 14a and or 14b a pressure in the wheel brake cylinders 13a and or 13b being constructed. Thus, the hydraulic pump can have a braking action on the wheels, which are the wheel brake cylinders 13 and or 13b are assigned generate.

A pressure reduction in the wheel brake cylinders 13a and / or b can be via the exhaust valves 14a and / or b by establishing the hydraulic connection between the wheel brake cylinders 13a and / or b with the reservoir 10 respectively.

The delivery side of the hydraulic pump 6 is next to the valves 12a and 12b additionally with a normally open control valve 8th connected. The normally open control valve 8th can also be used as a pressure build-up valve 8th be understood, by means of which the hydraulic pump 6 a pressure in an actuating chamber 7 the amplification unit 5 , which to the pressure build-up valve 8th connected, can build. The reinforcement unit 5 will be described in more detail below.

It should be mentioned at this point that the amplification unit 5 a hydraulic amplification unit. This is also based on the hydraulic connection of the second brake circuit 4 with the amplification unit, in particular with its actuation chamber 7 already recognizable.

In the hydraulic line between the actuation chamber 7 and the pressure build-up valve 8th there is a branch point 31 , Between the branch point 31 and the hydraulic connection 32 between reservoir 10 and hydraulic pump 6 There is a hydraulic connection in which a pressure reduction valve 9 is integrated. The pressure reduction valve 9 is a normally open control valve, which is a check valve 33 connected in parallel, which is a flow of hydraulic fluid in the direction of the line 32 in derogation. As already mentioned, the delivery side of the pump 6 both with the inlet valve 12a respectively. 12b connected, as well as with the pressure build-up valve 8th ,

In addition, the second brake circuit 4 a check valve 11 on, which is in the hydraulic connection between the pump delivery side 6 and the hydraulic line 32 located. The check valve 11 is provided as a spring-loaded check valve, which is a flow of hydraulic fluid from the pump delivery side in the direction of the reservoir 10 over the line 32 allows. Between the check valve 11 and the delivery side of the pump 6 is a pressure sensor 34 built-in.

As mentioned, the hydraulic pumps 6 such as 20 from a drive motor 35 driven. The pump 20 can be provided in duplicate, due to the double existing first brake circuits 2a and 2 B ,

This can lead to operating situations in which the pump 6 and the pump 20 operated together. To avoid this, the pump can 6 separately from the pumps in the brake circuits 2a and 2 B be provided operable.

Not shown here, but it is still conceivable that the said pumps are provided, for example, each with a motor, as well as it is possible to provide a freewheel, with the individual of said pumps, for example, can be operated separately. Likewise, by means of hydraulic switching elements idling at least One of the mentioned pumps can be realized, which is not in 1 is shown.

With the hydraulic layout according to the invention, however, it is also possible to supply the volume to the suction side of the second pump 20 to limit / shut down. The suction side of the second pump 20 is only after an ABS pressure reduction through the exhaust valve 18 Volume available. The ABS control is conventionally via the inlet valve 17 and exhaust valve 18 , After completion of the ABS control is the exhaust valve 18 closed again and the storage chamber 25 is completely emptied again, leaving the pump 20 again no volume is available.

Thus stands the pump 20 in the case described no volume available for promotion. The storage chamber 25 is empty and the exhaust valve 18 closed. Ie. pump 20 runs, but has no influence on the volume and the pressure in the brake circuit 2a , The description also applies to the pump in the brake circuit 2 B ,

The following is the operation of a first brake circuit 2a and the second brake circuit 4 described. The operation of the brake circuit 2 B is analogous to that of the brake circuit 2a ,

As already mentioned, the first brake circuit 2a to the master cylinder 3 connected while the second brake circuit 4 not to the master cylinder 3 connected. Thus, the at the second brake circuit 4 connected wheel brakes 13a and 13b not by the master cylinder 3 be supplied with pressure. The brake circuit 2a as well as the brake circuit 2 B can, however, from the master cylinder 3 from being pressurized. Should one of the wheel brake cylinder 13a or 13b be supplied with pressure, so that a braking effect on one of the wheel brake cylinders 13a or 13b assigned wheels, the pump can 6 Volume of brake fluid from the reservoir 10 over the intake valves 12a and or 12b the wheel brake cylinders 13a and or 13b respectively. To build up pressure, the exhaust valves 14a respectively. 14b kept closed. Should a pressure in the wheel brake cylinders 13a and or 13b can be set or regulated, it can be provided, one of the exhaust valves 14a or 14b close and the pressure on the wheel brake cylinders 13a and or 13b only over the other outlet valve 14a or 14b regulate. Suppose the exhaust valve 14b is kept closed, so the pump can 6 over the intake valves 12a or 12b Hydraulic fluid to the brake cylinders 13a and 13b respectively. Considering the connection of the outlet side of the pump 6 via the inlet valve 12a , the exhaust valve 14a as well as the exhaust valve 14b and the inlet valve 12b This is how you can see a hydraulic circuit. Will the valve 14b For example, kept closed at a pressure build-up by means of the hydraulic pump 6 kept closed, so can by regulating and / or adjusting the hydraulic valve 14a the total pressure in said hydraulic circuit can be adjusted. Thus, lies on the wheel brake cylinders 13a and 13b in each case the same pressure.

For pressure reduction, the exhaust valves 14a such as 14b opened and hydraulic fluid flows, starting from the wheel brake cylinders, via the branch points 29b and 30 as well as via the hydraulic line 32 in the reservoir 10 , In this way, the pressure in the wheel brake cylinders is reduced, the braking effect decreases.

In addition to pressure build-up and. Pressure reduction can be used to hold the inlet valves 13a and 13b and the exhaust valves 14a and 14b getting closed. The pressure build-up and the pressure reduction in the first two brake circuits 2a and 2 B , and thus on the wheel brake cylinders 16a respectively. 16b takes place as known from known recirculation systems and is therefore not described in detail. It should be noted here that the master cylinder 3 in 1 is shown as a tandem master cylinder, each one connected to the respective chamber wheel 16a or 16b having. In conventional brake systems, two wheels are often connected to the chambers of the tandem master cylinder.

Up to here, only the functionality of the second brake circuit 4 represented by means of the wheel brake cylinder 13a respectively. 13b can be supplied with pressure. The hydraulic pump 6 of the second brake circuit 4 but has a further functionality, apart from the pressurization of the wheel brake cylinder 13a , b.

This additional functionality is that via the pressure build-up valve 8th the delivery side of the pump to the amplification unit 5 More specifically to the actuation chamber 7 connected. Thus, the hydraulic pump 6 the actuation chamber 7 apply pressure. The one in the actuation chamber 7 built-up pressure can be used to actuate the master cylinder 3 be used. This will be discussed in more detail later.

As mentioned, the hydraulic pump 6 over the pressure build-up valve 8th with the actuation chamber 7 connected. There is a branching point in this hydraulic connection 31 which is the actuation chamber 7 with the pressure reduction valve 9 combines. The pressure reduction valve 9 also has a hydraulic connection to the line 32 on which into the reservoir 10 empties. The Pressure reduction valve 9 serves to reduce the pressure in the actuation chamber 7 to reduce again. With the valve open 9 and an existing pressure in the actuation chamber 7 the volume flows out of actuation chamber 7 if the pressure levels involved permit it, above the branching point 31 and the pressure reduction valve 9 in the reservoir 10 ,

By operating the hydraulic pump with involvement of the pressure build-up valve 8th and / or the pressure reduction valve 9 can be a pressure in the actuation chamber 7 be set. By adjusting the pressure in the actuation chamber 7 so can the master cylinder 3 be operated. Thus, a controllable and controllable brake booster, so acting on the master cylinder 3 Representable with a support force.

The adjustment of the pressure on both the wheel brake cylinders 13a respectively. 13b of the second brake circuit 4 , as well as in the actuation chamber 7 takes place by means of ΔP control of the respective pressure control valve. A ΔP control is understood to mean that, taking into account, more specifically, the valve spring forces as well as the magnetic actuation forces of the valve, a pressure gradient in front of and behind the valve to be controlled can be achieved. For this purpose, for example, the drive current for the solenoid valve can be limited.

By the possibility of the actuation chamber 7 the amplification unit 5 to apply pressure and thus the master cylinder 3 can be operated by means of the hydraulic pump 6 , in addition to the wheel brake cylinders 13a and 13b the brake circuit 4 , also the wheel brake cylinder 16a and 16b the brake circuits 2a and 2 B be pressurized.

The hydraulic pump 6 thus acts as a self-sufficient pressure supply to the wheel brake cylinder 13a respectively. 13b , Wherein self-sufficient in the sense of driver-independent to understand, on the other hand as a brake booster for actuating those wheel brake cylinders, which in hydraulic communication with the master cylinder 3 stand.

In addition to the described brake circuits 2a , b as well 4 For example, the hydraulic brake system includes said amplification unit 5 , by means of which the master cylinder 3 can be operated. The reinforcement unit 5 consists essentially of a mounted amplifier body, which is a reaction disc 43 includes a hydraulically actuated booster piston 15 and a pedal input bar 37 that with the brake pedal 22 connected is. The hydraulic actuation takes place in that in the manner described above, a pressure in the actuation chamber 7 the amplification unit 5 is set. The actuation chamber 7 is in interruptible hydraulic connection with the second brake circuit 4 , The pressure setting in the actuation chamber 7 takes place via the pressure build-up valve 8th as well as the pressure reduction valve 9 , The one in the actuation chamber 7 set pressure causes an actuating piston 38 in the actuation chamber 7 is offset and so an operating force on the booster piston 15 applies. The actuating piston 38 shares the actuation chamber 7 in two areas, the area facing the booster piston containing air and the one with the branch 31 hydraulically connected part contains or absorbs hydraulic fluid. Air and hydraulic fluid are on the piston 38 separated.

To increase the pressure in the actuation chamber 7 becomes the pressure build-up valve 8th open. As a result, the boosting force decreases from the boosting unit 5 to. To reduce the pressure, the pressure reduction valve 9 opened, which is a direct connection of the actuating chamber 7 with the hydraulic line 32 manufactures. As a result, the boosting force decreases from the boosting unit 5 from.

In addition to that of the actuation chamber 7 applied force, a force can be applied to the booster piston also by the driver .. For this purpose, the driver moves the input rod 37 and transmits an actuating force at least partially to the booster piston 15 , A part of the actuating force leads to the deformation of the return spring 40 for the input element 37 and or the reaction disc 43 , The joint coupling of the at least proportional actuating force of the driver and the boosting force starting from the actuating chamber can be achieved in a known manner by means of the reaction disc 43 being represented.

• 1. Jump-In: Bereich unendlicher Verstärkung bei geringen Pedaleingangsstangenwegen. Der Fahrer spürt nahe zu keine Pedalkraft.
• 2. Verstärkungsbereich: Die von der Verstärkungseinheit ausgehende Ausgangskraft stellt die verstärkte Eingangskraft dar. Der Fahrer spürt eine zunehmende Kraft am Pedal.
• 3. Run-Out: Hier liegt keine weitere Verstärkung vor. Dieser bereich befindet sich bei großen Pedaleingangsstangenwegen. Der Fahrer spürt eine erhöhte Pedalkraft.

The amplifier piston 15 has a chamber 44 on, before the known from conventional vacuum brake booster reaction disc 43 sitting. The chamber 44 offers the possibility of the reaction disc 43 in the event of brake application by the driver with the pedal input rod 37 to deform. With conventional vacuum brake boosters, 3 work areas can be identified:

• 1. Jump-In: range of infinite gain with low pedal input rod paths. The driver feels close to no pedal force.
• 2. Amplification Range: The output force from the amplification unit represents the amplified input force. The driver senses an increasing force on the pedal.
• 3. Run-Out: There is no further reinforcement here. This area is located at large pedestrian entrance bar paths. The driver feels an increased pedal force.

• 1. Die Eingangsstange 37 hat die Reaktionsscheibe 43 noch nicht berührt. Die Bremsbetätigung kommt alleine aus der Verstärkerkammer 37.
• 2. Eingangsstange und Reaktionsscheibe haben Kontakt. Die Reaktionsscheibe 43 kann in die Kammer 44 verformt werden.
• 3. Eingangsstange hat Reaktionsscheibe 43 bis zum Anschlag in Kammer 44 verformt und der Fahrer drückt direkt auf Kolben 15

These three areas can be covered with the arrangement as follows, or represented.

• 1. The entrance bar 37 has the reaction disk 43 not touched yet. The brake control comes alone from the booster chamber 37th
• 2. Input rod and reaction disc are in contact. The reaction disk 43 can in the chamber 44 be deformed.
• 3. Input rod has reaction disc 43 until it stops in the chamber 44 deformed and the driver presses directly on piston 15

To detect the braking request of the driver, a displacement sensor 41 be provided, which determines an actuation path of the brake pedal. Likewise, a displacement sensor can control the actuating travel of the input element 37 to capture. On the basis of the braking request, then the brake system 1 be controlled or regulated.

For driver brake request detection additional sensors can be provided or even needed. Here, for example, a pedal travel sensor, a differential travel sensor between Pedaleingangsstange 37 and intensifier pistons 15 and / or a rod path sensor are used. Likewise, other sensors are conceivable.

Between the amplifier piston 15 and the booster piston 15 facing side of the input element 37 is a free path 42 maintained. By providing this empty way 42 is it possible to apply a brake pressure in the brake system 1 by means of the actuation chamber 7 without the driver contributing to the brake application. In such a driver-independent braking, the brake pedal is not offset because of the idle travel.

It is also possible with still existing Leerweg 42 a braking effect by means of the brake system 1 in the manner described above, optionally with the participation of other non-hydraulic brake systems present in the vehicle such as a regenerative braking system, wherein the driver while the braking request on the sensor 41 pretends, but is not involved by means of the actuating force on the pressure build-up. This may be the case, for example, at the beginning of a braking or during a weak braking in which the free travel has not yet transgressed. In such weak braking regenerative braking is often performed, sometimes with additional hydraulic assistance.

Regenerative braking can be realized with still existing free travel, but is not limited to this area. Because the brake circuit 4 not connected to the master cylinder and thus decoupled from the driver can be decided independently of the driver, whether the braking request, especially in the brake circuit 4 hydraulic or regenerative to be realized. By decoupling the driver he feels in a regenerative braking no reaction to a changing hydraulic braking effect.

The amplifier piston 15 transfers the force exerted on it from the driver over the input rod 37 and / or from the actuation chamber 7 over the actuating piston 38 on a first piston 39 of the master cylinder 3 which in a known manner to a pressure build-up in the master cylinder 3 leads.

The following is the operation of the hydraulic brake system 1 described on the basis of several braking situations.

A possible braking situation corresponds to a partial braking. Partial braking is a braking that is not full braking. The partial braking range is the range of medium delays. Mean delays may be, for example, between 0 to 4 m / s ² . In such partial braking, the driver brakes in the brake circuits 2a and 2 B one. This is done via the brake pedal 22 , the reaction disk 43 , the amplifier piston 15 and the master cylinder 3 , in a known manner, such a pressure build-up takes place in the brake circuits 2a and 2 B connected wheels 16a and 16b ,

The braking request of the driver upon actuation of the brake is detected by a suitable sensor, for example by the displacement sensor 41 , According to the detected braking request, the pressure in the second brake circuit 4 by operating the pump 6 set. For this purpose, the exhaust valves are controlled as described above. The control over only one exhaust valve is possible as I said. This results in the driver's desired pressure in the brake circuit 4 ,

Furthermore, by operating the pump 6 the pressure in the actuation chamber 7 set. These are the pressure build-up valve 8th as well as the pressure reduction valve 9 driven accordingly. Thus, the desired amplification of the driver braking force by the amplification unit can be 5 to adjust.

Reduces the driver's braking request, in whole or in part, then at least one of the two exhaust valves 14a , b and the pressure reduction valve 9 open. Volume of brake fluid flows from the wheel brake cylinders 14a , b and the booster chamber back into the reservoir. So will the Braking effect in all brake circuits 4 . 2a . 2 B reduced.

By reducing the pedal position and concomitantly by reducing the pressure in the actuation chamber 7 , which is set depending on the pedal position, is at the wheel brakes 16a . 16b also the pressure is reduced.

The adjustment of the pressure in the amplification chamber 7 as well as the pressure in the brake circuit 4 is done by ΔP control of the involved valves. It can also be a pressure control of the brake circuit 4 be provided as well as the boost pressure, what then appropriate pressure sensors must be provided.

sensor 34 is such a pressure sensor. By means of this pressure sensor 34 the pump control is set to the currently highest required pressure, either in the booster chamber 7 and / or in the wheels 13a , b should be present. By means of the valves in ΔP operation, the correspondingly lower pressures could then be set.

Another operating situation corresponds to a braking in the context of an anti-lock control (ABS), where it may be necessary, an intake valve 12a . 12b close.

Suppose the pressure setting on both wheel brake cylinders 13a . 13b was before the ABS control alone by means of the exhaust valve 14b completed in the manner described above.

Now blocks the wheel, which is the wheel brake cylinder 13b is assigned, so must the inlet valve 12b getting closed. For this reason, the pressure setting in the entire brake circuit 4 no longer about the previously used for regulation exhaust valve 14b respectively. In this case, the pressure setting in the brake circuit 4 through the valve 14a accepted. The functionality of the pressure setting is thus of valve 14b on valve 14a above. Thus, a complete braking of the blocking wheel via the valve 14b respectively.

This process occurs when the second wheel of the brake circuit is blocked 4 carried out with the participation of the corresponding inlet and outlet valves. The ABS control on the wheels of the first brake circuit 2a , b takes place in a known manner.

A brake system described herein may also be used as part of a regenerative overall braking system. In such a regenerative braking system, the overall braking effect is composed of a hydraulic braking effect, starting from the hydraulic braking system just described, as well as a regenerative braking effect. The regenerative braking effect is caused by a generator which applies a braking torque, for example to the rear axle, of a vehicle. Both the hydraulic and the regenerative braking system can be operated individually or together and thus contribute to the braking.

The generator applies to its associated at least one axis of the vehicle to a non-constant, but known regenerative braking torque.

Suppose that the generator is associated with that axis, which also the second brake circuit 4 assigned.

The driver specifies a braking request in the form of a total braking torque to be set. The regenerative braking torque is known, as well as the brake circuits 2a , b caused braking torque on the other axis. By means of a control device of the overall brake system, a hydraulic braking torque to be set can be determined. This set braking torque is calculated as the difference between the total braking torque and the currently existing generator braking torque and by the brake circuits 2a , b the other axis caused braking torques. The braking torque of the second brake circuit to be set 4 is then, as already described, by operating the pump 6 and adjusting the respective valves. The driver does not notice any reaction from this pressure setting in the brake circuit 4 on the pedal, because the brake circuit 4 not on the master cylinder 3 connected.

The pump 6 acts as a pressure supply for both the brake boost through the gain unit 5 as well as for the braking effect in the brake circuit 4 ,

Should be braked purely hydraulic, so must the pump 6 both pressure for the gain in the booster chamber 7 , as well as the braking torque in the wheels 13 provide. The target pressure in the wheels 13 is usually larger than the one in the chamber 7 , If you set the pressure build-up valve 8th on ΔP control, opens the intake valves 12 and closes the exhaust valves 14a , b, for the exact adjustment of the pressure, if necessary only for a short time, so the pressure in the wheels 13a , b are set independently of the gain. Should be braked purely regenerative, the pump must 6 only the boost pressure in the boost chamber 7 provide. Under purely regenerative is to be understood that no hydraulic pressure build-up in brake circuit 4 is necessary because the necessary braking torque is provided by the generator, possibly with the involvement of the brake circuits 2a , b. This is the pressure build-up valve 8th opened and the intake valves 12a , b are closed. The braking torque at the wheels 13a , b is applied by means of the generator.

However, the driver still feels the same power on the pedal as with purely hydraulic braking, because he gets the same gain and is still only on the wheels 16a , b docked.

In order to use the largest possible proportion of regenerative braking torque during braking, the free travel is 42 between the pedal input rod 37 and the reaction disc 43 maintained. By keeping this idle travel, the driver can make the braking request by pressing the brake pedal 22 and associated displacement of the pedal input rod 37 pretend without being in the brake circuits 2a , b by the driver directly a pressure is built up. The actuation chamber 7 is also not supplied with pressure. This causes the brake circuits 2a , b not involved in hydraulic braking. This has the advantage that the total braking torque to be set by the generator and the second brake circuit 4 must be applied. The non-constant, caused by the generator braking torque is due to the hydraulic braking torque from the second brake circuit 4 added to the total braking torque. The adjusted hydraulic braking torque can be determined by a control unit again. As the braking effect of the brake circuits 2a , b do not contribute to the braking, a larger proportion of the total braking torque provided by the generator can be produced. Thus, the recuperation efficiency increases.

Previously, it was assumed that the generator is associated with that axle of the vehicle operatively connected, which also the second brake circuit 4 with the wheels 13a , b is assigned. However, the generator does not necessarily have to be arranged on this axis. Is the generator in operative connection with the axle, which can not be decoupled from the master cylinder (wheels 16a , b), so changes in maintaining the total braking torque by inventive Beerteiben the pump in the brake circuit 4 the distribution of the braking effect on the vehicle (front / rear) in purely hydraulic or purely regenerative braking, as well as in intermediate situations between regenerative and hydraulic braking. The resulting vehicle pitch can be classified as imperceptible on some vehicles. It is also conceivable that a four-wheel-generator is used.

As already described, the second brake circuit points 4 a check valve 11 on. The check valve 11 acts as a pressure relief valve and is used in another, more specific braking situation. The motor 35 drives both the pump 6 as well as the pump 20 at. For example, on a wheel brake cylinder 16a of the first brake circuit 2a pressure is built up and at the same time the pressure on the wheel brake cylinders 13a and 13b be kept, so when operating the pump, the valves 12a and 12b closed. Because when operating the pump 20 to build up pressure and the pump 6 operated, promotes the pump 6 Volume of brake fluid in the second brake circuit 4 and builds a pressure on the delivery side of the pump so fast 6 on. Should also the pressure in the actuating chamber 7 kept constant, so is the pressure build-up valve 8th closed. To damage the hydraulic unit 4 , in particular in the second brake circuit 4 To avoid, so to prevent excessive pressure, is the pressure relief valve 11 intended. As already mentioned, the pressure relief valve 11 spring-loaded. Is the pressure generated by operating the pump 6 has been built on the delivery side of the pump was high enough, so opens the pressure relief valve and hydraulic fluid is supplied to the reservoir and the pressure is reduced.

Brake requirements without pedal operation, so-called active pressure structures are in the present brake system by the amplifier device 5 carried out. In doing so, the hydraulic pump becomes 6 drives and delivers volume of brake fluid via the suction line 32 in the wheel brake cylinder of the second brake circuit 4 , as well as in the reinforcement unit 5 , In this way, a brake pressure in the wheel brake cylinders 13a , b directly through the pump 6 , as well as in the wheel brake cylinders 16a , b indirectly through the pump 6 about the amplification unit 5 built up. The respective intake valves and the pressure increase valve are opened. Such an active pressure build-up may, for example, be necessary in the course of a distance sequence control, an automatic emergency braking or a function of a brake disk wiper.

If there is a circuit failure at one of the brake circuits 2a , b before, the brake circuit remains 4 still active and allows braking on three wheels, as the brake circuit 4 like the intact brake circuit 2a respectively 2 B still have full function. In the presence of an electrical fault in a control, transmission, and / or power supply device or due to a fault in the hydraulic circuit, the brake circuit 4 fail. The possibility purely with the brake circuits 2a and or 2 B to brake, possibly alone by driver power, remains as a mechanical fallback level.

QUOTES INCLUDE IN THE DESCRIPTION

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

Cited patent literature

• DE 19826346 A [0001]

Claims (22)

Hydraulic brake system ( 1 ) with: - at least one first brake circuit ( 2a . 2 B ) in hydraulic communication with a master cylinder ( 3 ), - at least one second brake circuit ( 4 ), which is not in hydraulic communication with the master cylinder ( 3 ), - an amplification unit ( 5 ) for actuating the master cylinder ( 3 ) in hydraulic communication with the at least one second brake circuit ( 4 ). Hydraulic brake system according to claim 1, characterized in that the reinforcing unit ( 5 ) an actuation chamber ( 7 ) and that the at least one second brake circuit ( 4 ) a pressure source ( 6 ) in hydraulic communication with the actuating chamber ( 7 ) for pressure adjustment in the actuation chamber ( 7 ) having. Hydraulic brake system according to claim 2, characterized in that the at least one second brake circuit ( 4 ) a first, normally open, hydraulic interruption means ( 8th ) for pressure build-up in the actuation chamber ( 7 ) having. Hydraulic brake system according to claim 2, characterized in that the at least one second brake circuit ( 4 ) a second, normally open, hydraulic interrupting means ( 9 ) for depressurization in the actuation chamber ( 7 ) having. Hydraulic brake system according to claim 3, characterized in that the pressure source ( 6 ) with the actuating chamber ( 7 ) via the first interruption means ( 8th ) Is connected hydraulically interruptible. Hydraulic brake system according to claim 4, characterized in that the actuating chamber ( 7 ) with a hydraulic fluid reservoir ( 10 ) via the second interruption means ( 9 ) is hydraulically interruptible connected, in particular with the hydraulic fluid reservoir ( 10 ) of the master cylinder ( 3 ). Hydraulic brake system according to claim 6, characterized in that the pressure source ( 6 ) has a suction side, wherein the suction side of the pressure source ( 6 ) hydraulically to the hydraulic fluid reservoir ( 10 ) and wherein the suction side via at least a fifth normally open interruption means ( 14a , b) with at least one wheel brake cylinder ( 13a , b) is connected. Hydraulic brake system according to claim 3, characterized in that the pressure source ( 6 ) has a delivery side, wherein the delivery side of the pressure source ( 6 ) via the first interruption means ( 8th ) with the actuating chamber ( 7 ) is hydraulically connected via a third interrupting means ( 11 ) with a reservoir ( 10 ) is hydraulically connected and via at least a fourth interruption means ( 12a , b) with at least one wheel brake cylinder ( 13a , b) the second brake circuit ( 4 ) connected is. Hydraulic brake system according to claim 8, characterized in that the reinforcing unit ( 5 ) a transmission element ( 15 ) which has an operating force produced by the driver and / or by the pressure source ( 6 ) produced actuating force on the master cylinder ( 3 ) transmits. Hydraulic brake system according to claim 1, characterized in that the at least one first brake circuit ( 2a . 2 B ) at least one wheel brake cylinder ( 16 ) and wherein the pressure on the wheel brake cylinder ( 15 ) of the first brake circuit ( 2a , b) based on the pressure source ( 6 ) and / or by the driver via the amplification unit ( 5 ) produced pressure by means of - a normally open control valve, - a normally closed switching valve ( 18 ), - a hydraulic accumulator ( 19 ) and / or - a pump ( 20 ) is set. Hydraulic brake system according to at least one of the preceding claims, characterized in that the first, second, fourth and fifth interrupting means of the second brake circuit are normally open control valves and the third interrupting means is a check valve. Hydraulic brake system according to claim 9, characterized in that the transmission element ( 15 ) a reaction disk ( 43 ), wherein a relationship between an actuating path of an input element ( 37 ) and a force to be applied by the driver for this actuation path from the reaction disc ( 43 ), in particular of the deformation of the reaction disc ( 43 ), wherein the context has three operating areas - jump-in, gain area and / or - run-out. Method for operating a hydraulic brake system, wherein the hydraulic brake system ( 1 ) with: - at least one first brake circuit ( 2a . 2 B ) in hydraulic communication with a master cylinder ( 3 ) stands, At least one second brake circuit ( 4 ), which is not in hydraulic communication with the master cylinder ( 3 ), - an amplification unit ( 5 ) for actuating the master cylinder ( 3 ) in hydraulic communication with the at least one second brake circuit ( 4 ), wherein the at least one second brake circuit ( 4 ) a pressure source ( 6 ), - wherein a pressure in the at least one first brake circuit ( 2a . 2 B ) by means of the pressure source ( 6 ) and / or by the driver via the amplification unit ( 5 ) and a pressure in the second brake circuit ( 4 ) by means of the pressure source ( 6 ) is set. Method according to claim 13, characterized in that the amplification unit ( 5 ) an actuation chamber ( 7 ), wherein the pressure in the actuation chamber ( 7 ) by means of the pressure source ( 6 ) is set. A method according to claim 14, characterized in that the at least one second brake circuit ( 4 ) a first, normally open, hydraulic interruption means ( 8th ), wherein the pressure in the actuation chamber ( 7 ) via the first interruption means ( 8th ) is constructed. A method according to claim 14, characterized in that the at least one second brake circuit ( 4 ) a second normally open hydraulic interrupting means ( 9 ), wherein the pressure in the actuation chamber ( 7 ) via the second interruption means ( 9 ) is degraded. A method according to claim 13, characterized in that the pressure build-up in at least one wheel brake cylinder ( 13a , b) the second brake circuit ( 4 ) by means of at least one fourth interruption means ( 12a , b) and the pressure reduction in the at least one wheel brake cylinder ( 13a , b) by means of at least one fifth interrupting means ( 14 ) he follows. A method according to claim 13, characterized in that the master cylinder ( 3 ) by the amplification unit ( 5 ) is actuated, wherein an actuating force acting on the master cylinder ( 3 ), by the driver and / or by the pressure source ( 6 ) is produced. Method according to claim 13, characterized in that the hydraulic brake system ( 1 ) Is part of an overall brake system having a regenerative braking system in addition to the hydraulic brake system, wherein the braking effect of the hydraulic brake system to the braking effect of the regenerative braking system by adjusting the braking effect from the second brake circuit ( 4 ) is adjusted and wherein a predetermined by the driver total braking torque is set. A method according to claim 19, characterized in that the driver the braking request via an input element ( 22 . 37 ), wherein between the input element and a power transmission element ( 15 ) for actuating the master cylinder ( 3 ) a distance ( 42 ) is provided, wherein at existing distance ( 42 ) the braking action of the regenerative braking system alone or together with the second brake circuit ( 4 ). A method according to claim 20, characterized in that the regenerative braking system acts on the axle of the vehicle, the wheel brake cylinder ( 13a , b) of the second brake circuit are assigned. A method according to claim 20, characterized in that the regenerative braking system acts on - that axle of the vehicle, the wheel brake cylinder ( 16a , b) the at least one first brake circuit ( 2a . 2 B ) are assigned or, on those axes, the wheels of the first brake circuit and the at least one second brake circuit ( 2a , b) are assigned.

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