Control apparatus and method for operating an externally powered brake system of a vehicle

Abstract

The invention relates to a control apparatus (10) for an externally powered brake system of a vehicle, by means of which a motor (M) of a motorised piston cylinder apparatus (20) can be controlled and at least one first valve (22a) and at least one second valve (22b) can be switched, wherein first wheel brake cylinders (12a, 12b) are connected at least via the at least one first valve (22a) and second wheel brake cylinders (14a, 14b) are connected at least via the at least one second valve (22b) hydraulically to at least one fluid receiving volume (20c, 20d) of the motorised piston cylinder apparatus (20), wherein a brake pressure maintaining function or a brake pressure increasing function for the first wheel brake cylinders (12a, 12b) and a brake pressure reducing function for the second wheel brake cylinders (14a, 14b) can be executed simultaneously in that, while a transfer of brake fluid from the first wheel brake cylinders (12a, 12b) into the at least one larger fluid receiving volume (20c, 20d) is suppressed by means of the at least one closed switched first valve (22a), brake fluid from the second wheel brake cylinders (14a, 14b) can be sucked into the at least one larger fluid receiving volume (20c, 20d) by means of the at least one partially open switched second valve (22b).

Description

[0001] Description

[0002] title

[0003] Control device and method for operating a power braking system of a vehicle

[0004] The invention relates to a control device for a power braking system of a vehicle. The invention also relates to a power braking system for a vehicle. Furthermore, the invention relates to a method for operating a power braking system of a vehicle.

[0005] State of the art

[0006] From the prior art, such as DE 10 2018 212 269 A1 , a conventional procedure for blending a generator braking torque applied to a vehicle by means of at least one electric motor operated in a recuperative mode is known, by means of which a brake pressure build-up in at least one wheel brake cylinder of a hydraulic braking system of the vehicle is to be preventable or at least limited by at least one wheel outlet valve arranged downstream of the respective wheel brake cylinder being switched at least temporarily to its open state.

[0007] Disclosure of the invention

[0008] The present invention provides a control device for a power brake system of a vehicle having the features of claim 1, a power brake system for a vehicle having the features of claim 4 and a method for operating a power brake system of a vehicle having the features of claim 8.

[0009] Advantages of the invention The present invention creates quieter options for blending a generator braking torque that is exerted on the respective vehicle by means of at least one electric motor of a vehicle used as a generator. Advantageously, the present invention uses a motorized piston-cylinder device that is often already used in a power braking system to blend the generator braking torque, so that implementation of the present invention does not require any hardware expansion on the respective power braking system. Instead, it is generally sufficient to implement the present invention if only a control device of the respective power braking system is reprogrammed. This facilitates use of the present invention on a variety of different vehicle types.

[0010] A further advantage of the present invention is that, in a power-braking system equipped with the motorized piston-cylinder device, a driver of the vehicle equipped with the power-braking system (usually) does not brake into the power-braking system. The driver, who instead brakes into a simulator by actuating a brake actuation element / brake pedal, is therefore not irritated by simultaneously using the motorized piston-cylinder device of the power-braking system to effect the brake pressure reduction function. The present invention therefore not only enables a quieter blending of the generator braking torque, but also continues to offer the driver a standard brake actuation / pedal feel.

[0011] In an advantageous embodiment of the control device, the electronic device is additionally designed and / or programmed such that a brake pressure increase function for the first wheel brake cylinders and a brake pressure reduction function for the second wheel brake cylinders can be carried out simultaneously by means of the electronic device, in that, while a brake fluid transfer from the first wheel brake cylinders into the at least one fluid intake volume increased by means of the controlled motor is prevented by means of the at least one closed first valve, and brake fluid from the second wheel brake cylinders can be sucked into the at least one enlarged fluid intake volume via the at least one at least partially open second valve, a pump motor of at least one pump of the power brake system can be activated by means of the electronic device in such a way thatthat brake fluid can be pumped into the first wheel brake cylinders by means of the at least one activated pump. The embodiment of the control device described here therefore takes advantage of the fact that when the power brake system is equipped with the motorized piston-cylinder device and the at least one pump as its two actuators, operation of the at least one pump is not / hardly affected by the closing of the at least one first valve. Therefore, the motorized piston-cylinder device can be used to reduce the brake pressure in the second wheel brake cylinders, and simultaneously the at least one pump can be used to increase the brake pressure in the first wheel brake cylinders.

[0012] In a further advantageous embodiment of the control device, the electronic device is additionally designed and / or programmed in such a way that a first brake pressure reduction function with a first target gradient for the first wheel brake cylinders and a second brake pressure reduction function with a second target gradient above the first target gradient for the second wheel brake cylinders can be carried out simultaneously by means of the electronic device, in that during a brake fluid transfer from the second wheel brake cylinders via the at least one at least partially open second valve into the at least one fluid holding volume increased by means of the controlled motor, a brake fluid transfer from the first wheel brake cylinders into the at least one increased fluid holding volume is interrupted several times by means of the at least one briefly closed first valve.This also enables a relatively quiet blending of the generator braking torque of at least one electric motor of the vehicle used as a generator.

[0013] The advantages described above are also ensured in a power brake system for a vehicle which is equipped with a corresponding control device, the motorised piston-cylinder device, the motor of which can be controlled by means of the electronic device of the control device such that the at least one fluid intake volume of the motorised piston-cylinder device can be varied by means of the controlled motor, the two first wheel brake cylinders which can be arranged or are arranged on a first axle of the vehicle and the two second wheel brake cylinders which can be arranged or are arranged on a second axle of the vehicle, and the first and second valves which can be switched by means of the electronic device, wherein the first wheel brake cylinders are hydraulically connected to the at least one fluid intake volume at least via the at least one first valve and the second wheel brake cylinders are hydraulically connected to the at least one fluid intake volume at least via the at least one second valve.

[0014] In a first advantageous embodiment of the power-assisted braking system, the first wheel brake cylinders are hydraulically connected to a first brake circuit of the power-assisted braking system, and the second wheel brake cylinders are hydraulically connected to a second brake circuit of the power-assisted braking system. The only first valve is a switchover valve for the first brake circuit, and the only second valve is a switchover valve for the second brake circuit. The switchover valves can be switched more quietly than the wheel outlet valves of such a power-assisted braking system. The power-assisted braking system described here therefore enables particularly quiet blending of a generator braking torque exerted on the vehicle by at least one electric motor used as a generator.

[0015] In a second advantageous embodiment of the power brake system, one of the first wheel brake cylinders and one of the second wheel brake cylinders are hydraulically connected to a first brake circuit of the power brake system, and another of the first wheel brake cylinders and another of the second wheel brake cylinders are hydraulically connected to a second brake circuit of the power brake system, wherein the two first valves are a wheel inlet valve upstream of the first wheel brake cylinder of the first brake circuit and a wheel inlet valve upstream of the first wheel brake cylinder of the second brake circuit, and the two second valves are a wheel inlet valve upstream of the second wheel brake cylinder of the first brake circuit and a wheel inlet valve upstream of the second wheel brake cylinder of the second brake circuit. The advantages described above can therefore also be used for a power brake system with an X-brake circuit division.

[0016] Preferably, the motorized piston-cylinder device is a DPB device. The DPB device is understood to be a "Decoupled Power Brake." As will become clear from the following description, a driver operating the brake actuation element / brake pedal will not feel any repercussions from the current use of the DPB device to blend the generator braking torque on each axle, which is simultaneously generated to decelerate the respective vehicle by means of at least one of the vehicle's electric motors.

[0017] The advantages described above are also achieved by implementing a corresponding method for operating a power braking system of a vehicle. It is expressly noted that the method can be further developed according to the above-explained embodiments of the control device and / or the power braking system.

[0018] Short description of the drawings

[0019] Further features and advantages of the present invention are explained below with reference to the figures. They show:

[0020] Fig. 1 is a schematic representation of a first embodiment of the power braking system and the control device interacting therewith;

[0021] Fig. 2 is a schematic representation of a second embodiment of the power brake system, or the control device interacting therewith; and

[0022] Fig. 3 is a flow chart for explaining an embodiment of the

[0023] Method for operating a power braking system of a vehicle. Embodiments of the invention

[0024] Fig. 1 shows a schematic representation of a first embodiment of the power braking system, or the control device interacting therewith.

[0025] It should be noted that the usability of the control device 10 and the cooperating power braking system of Fig. 1 is not limited to any specific vehicle type / motor vehicle. Instead, the control device 10 and the power braking system can be mounted on (almost) any vehicle / motor vehicle that has two first wheels mounted on a first axle of the vehicle / motor vehicle and two second wheels arranged on a second axle of the vehicle / motor vehicle. The vehicle equipped with the power braking system can be, for example, a passenger car, a truck, or an off-highway vehicle.

[0026] The power brake system of Fig. 1 has two first wheel brake cylinders 12a and 12b and two second wheel brake cylinders 14a and 14b, wherein the first wheels of the vehicle can be braked / are braked by means of the first wheel brake cylinders 12a and 12b and the second wheels of the vehicle by means of the second wheel brake cylinders 14a and 14b. For the equal or unequal brake pressures present in the first wheel brake cylinders 12a and 12b, a maximum can be defined as the first maximum brake pressure and a minimum as the first minimum brake pressure. Accordingly, for the equal or unequal brake pressures present in the second wheel brake cylinders 14a and 14b, their maximum is referred to as the second maximum brake pressure and their minimum as the second minimum brake pressure. The power brake system of Fig. 1 has a II brake circuit division (parallel brake circuit division), i.e.that the first wheel brake cylinders 12a and 12b are hydraulically connected to a first brake circuit 16 of the power brake system, and the second wheel brake cylinders 14a and 14b are hydraulically connected to a second brake circuit 18 of the power brake system. The control device 10 interacting with the power brake system can be at least a part of the power brake system or at least a unit that can be mounted / mounted separately from the power brake system. Although the control device 10 is depicted in Fig. 1 as a one-piece control, the design of the control device 10 is not limited to this. Therefore, the functions performed by the control device 10 / its electronic device 10a can also be performed by several separate units.

[0027] The electronic device 10a of the control device 10 is designed and / or programmed such that a motor M of a motorized piston-cylinder device 20 of the power brake system and at least one first valve 22a and at least one second valve 22b can be controlled / activated by means of the electronic device 10a. The motor M of the motorized piston-cylinder device 20 can be controlled / activated by means of at least one motor control signal 10b output by the electronic device 10a such that at least one linearly adjustable piston 20a and 20b of the motorized piston-cylinder device 20 can be adjusted / adjusted by means of the controlled motor M such that at least one fluid receiving volume 20c and 20d of the motorized piston-cylinder device 20, delimited by the at least one piston 20a and 20b, can be varied / varied (in its size). The motorized piston-cylinder device 20 can, for example,a DPB (Decoupled Power Brake) device. In particular, the first brake circuit 16 of the power brake system can be hydraulically connected to a first fluid intake volume 20c, and the second brake circuit 18 of the power brake system can be hydraulically connected to a second fluid intake volume 20d of the motorized piston-cylinder device 20.

[0028] The first and second valves 22a and 22b, which can be switched by means of the electronic device 10a, are arranged on the power brake system in such a way that the first wheel brake cylinders 12a and 12b are hydraulically connected to the at least one fluid receiving volume 20c and 20d at least via the at least one first valve 22a, and the second wheel brake cylinders 14a and 14b are hydraulically connected to the at least one fluid receiving volume 20c and 20d at least via the at least one second valve 22b. The at least one first valve 22a can be switched by means of at least one first valve switching signal 10c output by the electronic device 10a. Accordingly, the at least one second valve 22b is switched by means of at least one second valve switching signal 10d output by the electronic device 10a. Advantageous exemplary embodiments for the first and second valves 22a and 22b will be discussed below.

[0029] Furthermore, the electronic device 10a is designed and / or programmed such that, by means of the electronic device 10a, a brake pressure holding or brake pressure increasing function for the first wheel brake cylinders 12a and 12b and a brake pressure reducing function for the second wheel brake cylinders 14a and 14b can be executed simultaneously. To simultaneously execute the brake pressure holding or brake pressure increasing function for the first wheel brake cylinders 12a and 12b and the brake pressure reducing function for the second wheel brake cylinders 14a and 14b, the motor M of the motorized piston-cylinder device 20 can be controlled by means of the electronic device 10a such that the at least one fluid receiving volume 20c and 20d of the motorized piston-cylinder device 20 is / is increased by adjusting its at least one piston 20a and 20b by means of the controlled motor M.At the same time, by means of the electronic device 10a, while a brake fluid transfer from the first wheel brake cylinders 12a and 12b into the at least one enlarged fluid receiving volume 20c and 20d is prevented by means of the at least one closed first valve 22a, brake fluid from the second wheel brake cylinders 14a and 14b can be sucked into the at least one enlarged fluid receiving volume 20c and 20d via the at least one at least partially open second valve 22b.This can also be paraphrased as follows: while the equal or unequal brake pressures in the first wheel brake cylinders 12a and 12b are locked in by closing the at least one first valve 22a, the equal or unequal brake pressures in the second wheel brake cylinders 14a and 14b can be reduced by injecting brake fluid into the at least one fluid receiving volume 20c and 20d by means of the electronic device 10a. A braking effect of the second wheel brake cylinders 14a and 14b eliminated by the resulting brake pressure reduction can be used to blend a generator braking torque exerted by at least one electric motor of the vehicle (not shown) operating in a recuperative mode.By means of the at least one electric motor used as a generator, kinetic energy can be converted into electrically storable energy when braking / slowing down the vehicle, without exceeding a target vehicle deceleration requested by the driver or an automatic system of the vehicle. The advantageous design / programming of the electronic device 10a thus enables axle-by-axle blending, which can be implemented without shifting the brake fluid via at least one wheel outlet valve 24a and 24b of the power brake system. This allows the advantage that the first and second valves 22a and 22b can be switched (generally) more quietly than the wheel outlet valves 24a and 24b of the power brake system.In particular, at least one first wheel outlet valve 24a downstream of the first wheel brake cylinders 12a and 12b and at least one second wheel outlet valve 24b downstream of the second wheel brake cylinders 14a and 14b can be controlled / maintained in their closed state during the simultaneous execution of the brake pressure holding or brake pressure increasing function for the first wheel brake cylinders 12a and 12b and the brake pressure reducing function for the second wheel brake cylinders 14a and 14b. The axle-by-axle blending effected by the design / programming of the electronic device 10a is therefore comparatively quiet.

[0030] A further advantage of the design / programming of the electronic device 10a of the control device 10 lies in the use of the motorized piston-cylinder device 20 to effect the brake pressure reduction in the second wheel brake cylinders 14a and 14b. In the power braking system, particularly in its "full-function mode," the driver of the vehicle is decoupled from the power braking system in such a way that the driver actuating a brake actuating element / brake pedal (not shown) has no direct access to the hydraulics of the power braking system. Instead, during the "full-function mode" of the power braking system, the driver brakes into a simulator (not shown). The driver actuating the brake actuating element / brake pedal therefore does not feel any reaction from the use of the motorized piston-cylinder device 20 to reduce the brake pressure in the second wheel brake cylinders 14a and 14b.The power braking system can be understood in particular as a driver-decoupled braking system or a by-wire braking system.

[0031] In the braking system of Fig. 1, a first switching valve 22a is used as the only first valve 22a, and a second switching valve 22b is used as the only second valve 22b. The advantageous design / programming of the electronic device 10a therefore makes it possible to exploit the fact that the switching valves 22a and 22b can be switched comparatively quietly, in particular more quietly than the wheel outlet valves 24a and 24b.

[0032] Therefore, the electronic device 10a is designed and / or programmed such that, precisely when the second maximum brake pressure in the second wheel brake cylinders 14a and 14b is less than or equal to the first minimum brake pressure in the first wheel brake cylinders 12a and 12b, the brake pressure maintaining or brake pressure increasing function for the first wheel brake cylinders 12a and 12b and the brake pressure reducing function for the second wheel brake cylinders 14a and 14b can be / are executed simultaneously by means of the electronic device 10a in the manner described above. The electronic device 10a utilizes the fact that a check valve 22c of the closed-circuit first switching valve 22a opens only when the second maximum brake pressure is / becomes greater than the first minimum brake pressure.(The check valve 22c of the first switching valve 22a is oriented such that a transfer of brake fluid from the first wheel brake cylinders 12a and 12b via the check valve 22c of the first switching valve 22a to the motorized piston-cylinder device 20 is prevented.) The design / programming of the electronic device 10a described here thus allows the use of the first switching valve 22a as a separating valve despite its being equipped with the check valve 22c. As an advantageous further development, the control device 10 / its electronic device 10a can additionally be designed and / or programmed such that a brake pressure increase function for the first wheel brake cylinders 12a and 12b and a brake pressure reduction function for the second wheel brake cylinders 14a and 14b can be / are executed simultaneously by means of the electronic device 10a.This is possible in that, at the same time as a transfer of brake fluid from the first wheel brake cylinders 12a and 12b into the at least one fluid holding volume 20c and 20d increased by means of the controlled motor M is prevented by means of the at least one closed first valve 22a, and brake fluid from the second wheel brake cylinders 14a and 14b can be sucked in / is sucked in via the at least one at least partially open second valve 22b into the at least one increased fluid holding volume 20c and 20d, a pump motor MP of at least one pump 26a and 26b of the power brake system can be activated / is activated by means of the electronic device 10a in such a way that brake fluid can be pumped / is pumped into the first wheel brake cylinders 12a and 12b by means of the at least one activated pump 26a.In particular, the electronic device 10a can be designed / programmed such that the brake pressure increase function for the first wheel brake cylinders 12a and 12b and the brake pressure reduction function for the second wheel brake cylinders 14a and 14b can be executed / are executed together precisely when the second maximum brake pressure in the second wheel brake cylinders 14a and 14b is less than or equal to the first minimum brake pressure in the first wheel brake cylinders 12a and 12b.

[0033] By means of the advantageous design / programming of the electronic device 10a described in the previous paragraph, it is possible to utilize the fact that, to ensure good redundancy, a power brake system often has not only the motorized piston-cylinder device 20 as its first actuator, but also the at least one pump 26a and 26b as its second actuator. In addition, by means of the design / programming of the electronic device 10a, it is possible to utilize the fact that the first wheel brake cylinders 12a and 12b, together with the respectively associated pump 26a, are decoupled from the motorized piston-cylinder device 20 and the second wheel brake cylinders 14a and 14b by means of the at least one closed-circuited first valve 22a.The brake fluid pumped into the first wheel brake cylinders 12a and 12b by the at least one activated pump 26a during the closing / keeping closed of the at least one first valve 22a can be drawn in via an at least partially open first high-pressure switching valve 28a of the first brake circuit 16. By closing / keeping closed a second high-pressure switching valve 28b of the second brake circuit 18, an undesirable pressure increase in the second wheel brake cylinders 14a and 14b due to co-driving of a pump 26b of the second brake circuit 18 by the pump motor MP can be (essentially) prevented.

[0034] Instead of the above-described simultaneous execution of the brake pressure increase function for the first wheel brake cylinders 12a and 12b and the brake pressure reduction function for the second wheel brake cylinders 14a and 14b, a brake force distribution between the four wheel brake cylinders 12a, 12b, 14a and 14b can also be changed by combining a slow brake pressure reduction in the second wheel brake cylinders 14a and 14b with a brake pressure maintenance in the first wheel brake cylinders 12a and 12b.

[0035] As a further optional development, the electronic device 10a of the control device 10 can also be designed and / or programmed such that a first brake pressure reduction function with a first target gradient for the first wheel brake cylinders 12a and 12b and a second brake pressure reduction function with a second target gradient for the second wheel brake cylinders 14a and 14b can be / are carried out simultaneously by means of the electronic device 10a, wherein the second target gradient lies above the first target gradient.This can also be realized by interrupting a brake fluid transfer from the first wheel brake cylinders 12a and 12b into the at least one enlarged fluid receiving volume 20c and 20d via the at least one at least partially open second valve 22b several times by means of the at least one briefly closed first valve 22a during a brake fluid transfer from the second wheel brake cylinders 14a and 14b into the at least one enlarged fluid receiving volume 20c and 20d.Preferably, the electronic device 10a is designed / programmed such that the first brake pressure reduction function with the first target gradient for the first wheel brake cylinders 12a and 12b and the second brake pressure reduction function with the second target gradient for the second wheel brake cylinders 14a and 14b can be executed / are executed together precisely when the second maximum brake pressure in the second wheel brake cylinders 14a and 14b is less than or equal to the first minimum brake pressure in the first wheel brake cylinders 12a and 12b.

[0036] Alternatively or additionally, the electronic device 10a can also be used to control simultaneous execution of the first brake pressure reduction function with the first target gradient for the second wheel brake cylinders 14a and 14b and the second brake pressure reduction function with the second target gradient for the first wheel brake cylinders 12a and 12b, in that during a brake fluid transfer from the first wheel brake cylinders 12a and 12b via the at least one at least partially open first valve 22a into the at least one fluid holding volume 20c and 20d enlarged by means of the controlled motor M, a brake fluid transfer from the second wheel brake cylinders 14a and 14b into the at least one enlarged fluid holding volume 20c and 20d is / is interrupted several times by means of the at least one briefly closed second valve 22b.In this way, a generator braking torque other than zero can also be advantageously blended on an axle-by-axle basis.

[0037] By means of the electronic device 10a, a first brake pressure increase function with a first target gradient for the first wheel brake cylinders 12a and 12b and a second brake pressure increase function with a second target gradient for the second wheel brake cylinders 14a and 14b can optionally be effected, wherein the first target gradient lies above the second target gradient. For this purpose, during a brake fluid transfer from the at least one fluid holding volume 20c and 20d reduced by means of the controlled motor M via the at least one at least partially open first valve 22a into the first wheel brake cylinders 12a and 12b, a brake fluid transfer from the at least one reduced fluid holding volume 20c and 20d into the second wheel brake cylinders 14a and 14b can be interrupted several times by means of the at least one briefly closed second valve 22b.Alternatively, during the brake fluid transfer from the at least one reduced fluid holding volume 20c and 20d via the at least one at least partially open first valve 22a and at least one first wheel inlet valve 30a arranged upstream of the first wheel brake cylinders 14a and 14b and switched at least partially open into the first wheel brake cylinders 12a and 12b, the brake fluid transfer from the at least one reduced fluid holding volume 20c and 20d into the second wheel brake cylinders 14a and 14b can be interrupted several times by means of at least one second wheel inlet valve 30b arranged upstream of the second wheel brake cylinders 14a and 14b and switched closed for a short time.Accordingly, by means of the electronic device 10a, the first brake pressure increase function with the first target gradient for the second wheel brake cylinders 14a and 14b and the second brake pressure increase function with the second target gradient for the first wheel brake cylinders 12a and 12b can be effected / brought about simultaneously.

[0038] In all the processes described above, the brake pressures in the wheel brake cylinders 12a, 12b, 14a and 14b can be adjusted by means of the electronic device 10a in such a way that the target vehicle deceleration requested by the driver or the vehicle's automatic system corresponds to a total braking torque M exerted on the vehicle. totai, wherein the total braking torque Mtotai is the sum of a first hydraulic partial braking torque MM applied to the first axle of the vehicle by means of the first wheel brake cylinders 12a and 12b, a second hydraulic partial braking torque Mh2 applied to the second axle of the vehicle by means of the second wheel brake cylinders 14a and 14b, a first generator partial braking torque M applied to the first axle of the vehicle by means of the at least one electric motor operated in its recuperative mode mi and a second generator partial braking torque M applied to the second axle of the vehicle by means of the at least one electric motor operated in its recuperative mode m2. After reaching a target pressure of (almost) 0 bar, or the atmospheric pressure in the first wheel brake cylinders 12a and 12b and / or in the second wheel brake cylinders 14a and 14b, the at least one downstream wheel outlet valve 24a and 24b can be at least partially opened in order to compensate for any leakage via the at least one upstream wheel inlet valve 30a and 30b.

[0039] For example only, the power brake system of Fig. 1 is constructed as a 2-box system. A first box 32a of the 2-box system comprises the motorized piston-cylinder device 20 and a brake fluid reservoir 34 hydraulically connected thereto. A second box 32b of the 2-box system has the valves 22a, 22b, 24a, 24b, 28a, 28b, 30a and 30b, at least one pump 26a and 26b, one storage chamber 36 per brake circuit 16 and 18 arranged downstream of the wheel outlet valves 24a or 24b, one check valve 38 arranged between the storage chamber 36 and the respective pump 26a or 26b, and a pre-pressure sensor 40 connected to the second brake circuit 18. However, the components of the power brake system shown in Fig. 1 are only to be interpreted as examples.

[0040] The equal or unequal brake pressures present in the first wheel brake cylinders 12a and 12b and the equal or unequal brake pressures present in the second wheel brake cylinders 14a and 14b, or the first maximum brake pressure, the first minimum brake pressure, the second maximum brake pressure and / or the second minimum brake pressure, can be physical variables estimated by the electronic device 10a. Alternatively or additionally, the electronic device 10a can also be designed / programmed to estimate the equal or unequal brake pressures present in the first wheel brake cylinders 12a and 12b and the equal or unequal brake pressures present in the second wheel brake cylinders 14a and 14b.to read the first maximum brake pressure, the first minimum brake pressure, the second maximum brake pressure, and / or the second minimum brake pressure from at least one sensor signal from at least one sensor, such as specifically the pre-pressure sensor 40 connected to the second brake circuit 18. Fig. 2 shows a schematic representation of a second embodiment of the power brake system, or the control device interacting therewith.

[0041] The power brake system schematically illustrated in Fig. 2 differs from the previously described embodiment of Fig. 1 in that one of the first wheel brake cylinders 12a and one of the second wheel brake cylinders 14a are connected to its first brake circuit 16, while another of the first wheel brake cylinders 12b and another of the second wheel brake cylinders 14b are assigned to its second brake circuit 18. The power brake system of Fig. 2 is therefore designed with an X-brake circuit division.

[0042] The electronic device 10a of the control device 10 illustrated in Fig. 2 is also designed and / or programmed such that, by means of the electronic device 10a, a brake pressure maintenance or brake pressure increase function for the first wheel brake cylinders 12a and 12b and a brake pressure reduction function for the second wheel brake cylinders 14a and 14b can be executed simultaneously. This can be achieved by means of the electronic device 10a, while a brake fluid transfer from the first wheel brake cylinders 12a and 12b into the at least one enlarged fluid receiving volume 20c and 20d is prevented by means of the at least one closed first valve 30a, brake fluid can be sucked in from the second wheel brake cylinders 14a and 14b via the at least one at least partially open second valve 30b into the at least one enlarged fluid receiving volume 20c and 20d. In the power braking system shown in Fig.2, the two first valves 30a are a wheel inlet valve 30a upstream of the first wheel brake cylinder 12a of the first brake circuit 16 and a wheel inlet valve 30a upstream of the first wheel brake cylinder 12b of the second brake circuit 18. Correspondingly, the two second valves 30b are a wheel inlet valve 30b upstream of the second wheel brake cylinder 14a of the first brake circuit 16 and a wheel inlet valve 30b upstream of the second wheel brake cylinder 14b of the second brake circuit 18. The electronic device 10a utilizes the fact that a respective check valve 30c of the wheel inlet valves 30a used as first valves 30a only opens when the second minimum brake pressure is less than the first maximum brake pressure isl / . (The respective check valve 30c is oriented such that a transfer of brake fluid from the motorized piston-cylinder device 20 via the check valve 30c into the downstream first wheel brake cylinder 12a or 12b is prevented.).

[0043] Preferably, the electronic device 10a is therefore designed and / or programmed such that, precisely when the second minimum brake pressure in the second wheel brake cylinders 14a and 14b is greater than or equal to the first maximum brake pressure in the first wheel brake cylinders 12a and 12b, the brake pressure maintaining or brake pressure increasing function for the first wheel brake cylinders 12a and 12b and the brake pressure reducing function for the second wheel brake cylinders 14a and 14b can be / are executed simultaneously by means of the electronic device 10a in the manner described above. The design / programming of the electronic device 10a described here thus allows the wheel inlet valves 30a arranged upstream of the first wheel brake cylinders 12a and 12b to be used as isolating valves, despite their being equipped with a check valve 30c each.

[0044] Likewise, the electronic device 10a can also be used to control the simultaneous execution of a first brake pressure reduction function with a first target gradient for the first wheel brake cylinders 12a and 12b and a second brake pressure reduction function with a second target gradient for the second wheel brake cylinders 14a and 14b, wherein the second target gradient lies above the first target gradient. For this purpose, during a brake fluid transfer from the second wheel brake cylinders 14a and 14b via the at least one at least partially open second valve 30b into the at least one enlarged fluid holding volume 20c and 20d, a brake fluid transfer from the first wheel brake cylinders 12a and 12b into the at least one enlarged fluid holding volume 20c and 20d can be interrupted several times by means of the at least one briefly closed first valve 30a.

[0045] The other processes described in the preceding embodiment can also be carried out by appropriately designing / programming the electronic device 10a. The advantageous interaction of the control device 10 with the power braking system of Fig. 2 thus enables numerous low-noise options for blending a generator braking torque exerted by at least one electric motor of the vehicle (not shown) operating in a recuperative mode.

[0046] With regard to further properties and features of the power brake system of Fig. 2 and its advantages, reference is made to the previously described embodiment of Fig. 1.

[0047] Fig. 3 shows a flow chart for explaining an embodiment of the method for operating a power braking system of a vehicle.

[0048] The procedure described below can be carried out, for example, using one of the power braking systems explained above. However, the method's implementation is not limited to such a power braking system. Likewise, the method's implementation is not limited to any specific vehicle type / motor vehicle.

[0049] The method comprises at least method steps S1 to S3, the simultaneous execution of which jointly effects a brake pressure maintaining or brake pressure increasing function for two first wheel brake cylinders of the power brake system arranged on a first axle of the vehicle, and a brake pressure reducing function for two second wheel brake cylinders of the power brake system arranged on a second axle of the vehicle. In method step S1, a motor of a motorized piston-cylinder device of the power brake system is controlled such that at least one fluid intake volume of the motorized piston-cylinder device is increased by means of the controlled motor.At the same time, in method step S2, at least one first valve of the power brake system is switched such that, while the first wheel brake cylinders are hydraulically connected to the at least one fluid intake volume at least via the at least one first valve, a brake fluid transfer from the first wheel brake cylinders into the at least one fluid intake volume increased by means of the controlled motor is prevented by means of the at least one closed first valve.Likewise, in the simultaneously executed method step S3, at least one second valve of the power brake system is switched such that, while the second wheel brake cylinders are hydraulically connected to the at least one fluid intake volume at least via the at least one second valve, brake fluid is drawn from the second wheel brake cylinders into the at least one enlarged fluid intake volume via the at least one at least partially open second valve. Examples of the at least one first valve and the at least one second valve, as well as advantageous prerequisites for executing method steps S1 to S3, have already been explained above.

[0050] Optionally, when carrying out the method described here, a brake pressure increase function for the first wheel brake cylinders and a brake pressure reduction function for the second wheel brake cylinders can also be effected simultaneously by carrying out a method step S4 in addition to the method steps S1 to S3.As method step S4, while a brake fluid transfer from the first wheel brake cylinders into the at least one fluid intake volume increased by means of the controlled motor is prevented by means of the at least one closed first valve and brake fluid is sucked from the second wheel brake cylinders into the at least one enlarged fluid intake volume via the at least one at least partially open second valve (method steps S1 to S3), a pump motor of at least one pump of the power brake system is additionally activated such that brake fluid is pumped into the first wheel brake cylinders by means of the at least one activated pump.

[0051] Likewise, when executing the method described here, a first brake pressure reduction function with a first target gradient for the first wheel brake cylinders and a second brake pressure reduction function with a second target gradient above the first target gradient for the second wheel brake cylinders can be effected simultaneously. In a method step S5, the motor of the motorized piston-cylinder device is controlled such that the at least one fluid intake volume of the motorized piston-cylinder device is reduced by means of the controlled motor. At the same time, the at least one second valve is

[0052] Method step S6 is switched to an at least partially open state. However, in method step S7, which is carried out during a brake fluid transfer effected by method step S6 from the at least one fluid holding volume reduced by the controlled motor via the at least one second valve switched to an at least partially open state into the second wheel brake cylinders, a brake fluid transfer from the at least one reduced fluid holding volume is interrupted several times by means of the at least one briefly closed first valve.

[0053] Thus, carrying out the procedure described here also creates the advantages already explained above.

Claims

Claims 1. A control device (10) for a power brake system of a vehicle, comprising: an electronic device (10a) which is designed and / or programmed such that, by means of the electronic device (10a), a motor (M) of a motorized piston-cylinder device (20) of the power brake system can be controlled such that, by means of the controlled motor (M), at least one fluid intake volume (20c, 20d) of the motorized piston-cylinder device (20) can be varied, and by means of the electronic device (10a), at least one first valve (22a, 30a) and at least one second valve (22b, 30b) of the power brake system can be switched, wherein two first wheel brake cylinders (12a, 12b) of the power brake system can be controlled at least via the at least one first valve (22a, 30a) and two second wheel brake cylinders (14a, 14b) of the power brake system can be controlled at least via the at least one second valve (22b, 30b). hydraulically connected to the at least one liquid receiving volume (20c,20d) are connected; characterized in that the electronic device (10a) is additionally designed and / or programmed in such a way that by means of the electronic device (10a) a brake pressure holding or brake pressure increasing function for the first wheel brake cylinders (12a, 12b) and a brake pressure reducing function for the second wheel brake cylinders (14a, 14b) can be carried out simultaneously, in that at least, during a brake fluid transfer from the first wheel brake cylinders, (12a, 12b) into which at least one fluid intake volume (20c, 20d) enlarged by means of the controlled motor (M) is prevented by means of the at least one closed-switched first valve (22a, 30a), brake fluid from the second wheel brake cylinders (14a, 14b) can be sucked into the at least one enlarged fluid intake volume (20c, 20d) via the at least one at least partially open-switched second valve (22b, 30b).

2. Control device (10) according to claim 1, wherein the electronic device (10a) is additionally designed and / or programmed such that a brake pressure increase function for the first wheel brake cylinders (12a, 12b) and a brake pressure reduction function for the second wheel brake cylinders (14a, 14b) can be carried out simultaneously by means of the electronic device (10a), in that, while a brake fluid transfer from the first wheel brake cylinders (12a, 12b) into the at least one fluid receiving volume (20c, 20d) enlarged by means of the controlled motor (M) is prevented by means of the at least one closed first valve (22a), and brake fluid from the second wheel brake cylinders (14a, 14b) can be sucked into the at least one enlarged fluid receiving volume (20c, 20d) via the at least one at least partially open second valve (22b), a pump motor (MP) of at least one pump (26a,26b) of the power brake system can be activated by means of the electronic device (10a) such that brake fluid can be pumped into the first wheel brake cylinders (12a, 12b) by means of the at least one activated pump (26a).

3. Control device (10) according to claim 1 or 2, wherein the electronic device (10a) is additionally designed and / or programmed such that by means of the electronic device (10a) a first brake pressure reduction function with a first target gradient for the first wheel brake cylinders (12a, 12b) and a second brake pressure reduction function with a second target gradient over the first target gradients for the second wheel brake cylinders (14a, 14b) can be carried out in that during a brake fluid transfer from the second wheel brake cylinders (14a, 14b) via the at least one at least partially open second valve (22b, 30b) into the at least one fluid receiving volume (20c, 20d) enlarged by means of the controlled motor (M), a brake fluid transfer from the first wheel brake cylinders (12a, 12b) into the at least one enlarged fluid receiving volume (20c, 20d) is interrupted several times by means of the at least one briefly closed first valve (22a, 30a).

4. Power brake system for a vehicle comprising: a control device (10) according to one of the preceding claims; the motorized piston-cylinder device (20), the motor (M) of which can be controlled by the electronic device (10a) of the control device (10) such that the at least one fluid intake volume (20c, 20d) of the motorized piston-cylinder device (20) can be varied by means of the controlled motor (M); the two first wheel brake cylinders (12a, 12b) that can be arranged or are arranged on a first axle of the vehicle and the two second wheel brake cylinders (14a, 14b) that can be arranged or are arranged on a second axle of the vehicle;and the first and second valves (22a, 22b, 30a, 30b) which can be switched by means of the electronic device (10a), wherein the first wheel brake cylinders (12a, 12b) are hydraulically connected to the at least one fluid receiving volume (20c, 20d) at least via the at least one first valve (22a, 30a) and the second wheel brake cylinders (14a, 14b) are hydraulically connected to the at least one fluid receiving volume (20c, 20d) at least via the at least one second valve (22b, 30b); 5. Power brake system according to claim 4, wherein the first wheel brake cylinders (12a, 12b) are hydraulically connected to a first brake circuit (16) of the power brake system and the second wheel brake cylinders (14a, 14b) are hydraulically connected to a second brake circuit (18) of the power brake system, and wherein the only first valve (22a) is a changeover valve (22a) of the first brake circuit (16) and the only second valve (22b) is a changeover valve (22b) of the second brake circuit (18).

6. Power brake system according to claim 4, wherein one of the first wheel brake cylinders (12a) and one of the second wheel brake cylinders (14a) are hydraulically connected to a first brake circuit (16) of the power brake system and another of the first wheel brake cylinders (12b) and another of the second wheel brake cylinders (14b) are hydraulically connected to a second brake circuit (18) of the power brake system, and wherein the two first valves (30a) are a wheel inlet valve (30a) upstream of the first wheel brake cylinder (12a) of the first brake circuit (16) and a wheel inlet valve (30a) upstream of the first wheel brake cylinder (12b) of the second brake circuit (18), and the two second valves (30b) are a wheel inlet valve (30b) upstream of the second wheel brake cylinder (14a) of the first brake circuit (16) and a wheel inlet valve (30b) upstream of the second wheel brake cylinder (14b) of the second brake circuit (18). Wheel inlet valve (30b).

7. Power brake system according to one of claims 4 to 6, wherein the motorized piston-cylinder device (20) is a DPB device (20).

8. A method for operating a power braking system of a vehicle, characterized by: Simultaneous execution of a brake pressure holding or brake pressure increasing function for two first wheel brake cylinders (12a, 12b) of the power brake system arranged on a first axle of the vehicle and a brake pressure reducing function for two second wheel brake cylinders (14a, 14b) of the power brake system arranged on a second axle of the vehicle at least by the steps: Controlling a motor (M) of a motorised piston-cylinder device (20) of the power brake system in such a way that at least one fluid intake volume (20c, 20d) of the motorised piston-cylinder device (20) is increased (S1) by means of the controlled motor (M); Switching at least one first valve (22a, 30a) of the power brake system such that, while the first wheel brake cylinders (12a, 12b) are hydraulically connected to the at least one fluid receiving volume (20c, 20d) at least via the at least one first valve (22a, 30a), a brake fluid transfer from the first wheel brake cylinders (12a, 12b) into the at least one fluid receiving volume (20c, 20d) increased by means of the controlled motor (M) is prevented by means of the at least one closed first valve (22a, 30a) (S2); and Switching at least one second valve (22b, 30b) of the power brake system in such a way that, while the second wheel brake cylinders (14a, 14b) are hydraulically connected to the at least one fluid receiving volume (20c, 20d) at least via the at least one second valve (22b, 30b), brake fluid is sucked from the second wheel brake cylinders (14a, 14b) into the at least one enlarged fluid receiving volume (20c, 20d) via the at least one at least partially open second valve (22b, 30b) (S3).

9. Method according to claim 8, wherein simultaneously a brake pressure increasing function for the first wheel brake cylinders (12a, 12b) and a brake pressure reducing function for the second wheel brake cylinders (14a, 14b) are carried out by simultaneously, while a brake fluid transfer from the first wheel brake cylinders (12a, 12b) into the at least one fluid receiving volume (20c, 20d) enlarged by means of the controlled motor (M) is prevented by means of the at least one closed first valve (22a), and brake fluid from the second wheel brake cylinders (14a, 14b) is sucked into the at least one enlarged fluid receiving volume (20c, 20d) via the at least one at least partially open second valve (22b), a pump motor (MP) of at least one pump (26a, 26b) of the power brake system is additionally activated such that brake fluid is pumped into the first wheel brake cylinders (12a, 12b) by means of the at least one activated pump (26a) (S4).

10. The method according to claim 8 or 9, wherein a first brake pressure reduction function with a first target gradient for the first wheel brake cylinders (12a, 12b) and a second brake pressure reduction function with a second target gradient above the first target gradient for the second wheel brake cylinders (14a, 14b) are carried out simultaneously, in that during a brake fluid transfer from the at least one fluid holding volume (20c, 20d) reduced by means of the controlled motor (M) via the at least one at least partially open second valve (22b, 30b) into the second wheel brake cylinders (14a, 14b), a brake fluid transfer from the at least one reduced fluid holding volume (20c, 20d) is interrupted several times by means of the at least one briefly closed first valve (22a, 30a) (S5-S7).

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