DE102014225587A1 - Hydraulic power unit for a brake system of a vehicle, brake system for a vehicle and method for operating a brake system of a vehicle - Google Patents

Abstract

The invention relates to a brake system for a vehicle having a first brake circuit (14a) connected to a master brake cylinder (10) to which at least one first wheel brake cylinder (16a) is connected to a second brake circuit (14b) connected to the master brake cylinder (10) which at least one second wheel brake cylinder (16b) is connected, and a first piston-cylinder device (18a) with an adjustable first piston (20a) which limits a first volume (22a) which can be filled with brake fluid, which hydraulically at least with the first brake circuit (14a), wherein a second volume (22b) which can be filled with brake fluid and which is hydraulically connected at least to the second brake circuit (14b) is delimited by an adjustable second piston (20b), and wherein the second volume (22b) in a second piston-cylinder E formed separately from the first piston-cylinder device (18a) and equipped with the second piston (20b) device (18b). The invention also relates to a hydraulic power unit for realizing such a brake system and to a method for operating a brake system of a vehicle.

Description

The invention relates to a hydraulic unit for a brake system of a vehicle. Likewise, the invention relates to a braking system for a vehicle. Furthermore, the invention relates to a method for operating a brake system of a vehicle.

State of the art

In the DE 10 2011 004 983 A1 For example, a brake system for a vehicle and a method for controlling the brake system are described. The brake system comprises a master cylinder with two pressure chambers, wherein each one brake circuit is hydraulically connected to each of the two pressure chambers of the master cylinder. In addition, the brake system has a motorized piston-cylinder device, which also has two pressure chambers. Each of the two pressure chambers of the motorized piston-cylinder device is hydraulically connected via a respective isolation valve to another of the two brake circuits of the brake system.

Disclosure of the invention

The invention provides a hydraulic unit for a brake system of a vehicle having the features of claim 1, a brake system for a vehicle having the features of claim 4 and a method for operating a brake system of a vehicle having the features of claim 10.

Advantages of the invention

The articles of the present invention allow a relatively large volume of brake fluid to be transferred between all the wheel brake cylinders of a brake system and the first volume and the second volume without the need for a single large volume pressure unit on the brake system. A use of such a large-volume pressure unit of the prior art has conventionally the disadvantage that it must muster high supporting and driving forces due to its single piston with a comparatively large piston diameter at high counter pressures. This places high demands on the conventionally often required large-volume printing unit, such as expensive starting materials in producing the large-volume printing unit. The conventionally sometimes used large-volume pressure unit is therefore relatively expensive. In contrast, the objects of the present invention can be realized inexpensively and by means of easily executable process steps.

By means of the articles of the present invention, not only a comparatively large volume of brake fluid can be easily transferred between all the wheel brake cylinders of the respective brake system, the first volume and the second volume, but by means of the articles of the present invention also a relatively fast brake fluid volume transfer in the respective brake system can be carried out , Also, by means of the present invention, occurrence of a conventional emergency situation which is sometimes present in a brake system having a single pressure adjusting unit with only one adjustable piston component, if the single piston component is in block, is prevented. As will be explained in more detail below, the present invention also overcomes the problem of snooping that frequently occurs in the prior art within a short time. The present invention thus also contributes to increasing a safety standard of the respective brake system.

In an advantageous embodiment of the hydraulic unit / brake system, the first piston may have a first piston diameter aligned perpendicular to its first braking direction, which is greater or smaller than a second piston diameter of the second piston aligned perpendicular to its second braking direction. Especially with a hydraulic connection of the first volume only to the first partial brake circuit or brake circuit and a hydraulic connection of the second volume only to the second partial brake circuit or brake circuit can thus, even if the first piston and the second piston are connected to the same engine, different brake fluid volume between the first volume and the first partial brake circuit / brake circuit and the second volume and the second partial brake circuit / brake circuit are transferred. A first brake fluid volume fed to or withdrawn from the first partial brake circuit / brake circuit and a second brake fluid volume supplied to or taken from the second partial brake circuit / brake circuit can thus be maintained as required and specific to the brake circuit. In this way, e.g. a stronger brake pressure gradient can be effected in one of the two brake circuits of the respective brake system, as a result of which vehicle stability can be improved, in particular during rapid braking of a vehicle equipped with the respective brake system.

In another advantageous embodiment of the hydraulic unit / brake system, the first volume via a first check valve is hydraulically connected both to the first partial brake circuit or brake circuit and to the second partial brake circuit or brake circuit and / or the second volume is hydraulically connected via a second check valve both to the first partial brake circuit or brake circuit and to the second partial brake circuit or brake circuit. Thus, both the first volume and the second volume can be shared for at least one of the brake circuits of the respective brake system. In addition, as will be explained in more detail below, in this case by means of adjusting the first piston in opposition to the second piston, brake fluid can also be snooped simultaneously during filling of the first brake circuit and / or the second brake circuit.

In an advantageous embodiment of the brake system, the brake system has a control device, by means of which the first motor and the second motor can be controlled.

In an advantageous embodiment, the control device is designed to control the first motor for executing a first setpoint speed and the second motor for executing a deviating from the first setpoint speed second setpoint speed. This is advantageous in particular with the hydraulic connection of the first volume only to the first brake circuit and the hydraulic connection of the second volume only to the second brake circuit, since in this way the first brake fluid volume shifted between the first volume and the first brake circuit and that between the second Volume and the second brake circuit displaced second brake fluid volume as needed and brake circuit specific about the different target speeds are fixed. Thus, even in this advantageous embodiment of the control device, the stability of the vehicle equipped with the respective braking system can be optimized by different increases in brake pressure in the brake circuits (even during a rapid braking process).

In a further advantageous embodiment, the control device is designed to control the first motor and the second motor such that the first piston is adjustable in opposite directions to the second piston. This is particularly advantageous in the case of a joint connection of the first brake circuit and the second brake circuit to at least one of the volumes for carrying out the refilling operation described below.

The advantages described above are also ensured when executing a corresponding method for operating a brake system of a vehicle. It should be noted that the method can also be developed according to the previously described embodiments of the hydraulic unit / brake system.

For example, during execution of the method, the first motor may be actuated to execute a first setpoint rotational speed, while the second motor is actuated to execute a second setpoint rotational speed deviating from the first setpoint rotational speed. The advantageous needs-based and brake circuit-specific determination of the first brake fluid volume displaced between the first volume and the first brake circuit and the second brake fluid volume displaced between the second volume and the second brake circuit can therefore also be realized when the method is carried out.

Furthermore, in carrying out the method, the first motor and the second motor can also be controlled in such a way that the first piston is displaced in the opposite direction to the second piston. This provides refilling of the first volume and / or the second volume without interrupting brake pressure increase in at least one of the brake circuits.

Brief description of the drawings

Further features and advantages of the present invention will be explained below with reference to the figures. Show it:

1 a schematic representation of a first embodiment of the brake system;

2 a schematic representation of a second embodiment of the brake system; and

3 a flowchart for explaining an embodiment of the method for operating a braking system of a vehicle.

Embodiments of the invention

1 shows a schematic representation of a first embodiment of the brake system.

This in 1 schematically illustrated brake system is used in a vehicle / motor vehicle. It should be noted that the usability of the brake system is not limited to a particular vehicle type / vehicle type.

The braking system of 1 has a master cylinder 10 , one on the master cylinder 10 connected first brake circuit 14a and one on the master cylinder 10 also connected second brake circuit 14b , At least one first wheel brake cylinder 16a is at the first one brake circuit 14a tethered. Accordingly, at least one second wheel brake cylinder 16b on the second brake circuit 14b tethered. Preferably, a brake fluid reservoir is also 12 at least one sniffer bore of the master cylinder 10 tethered. It should be noted that the in 1 illustrated equipment of the brake circuits 14a and 14b with two wheel brake cylinders each 16a or 16b merely to be interpreted as an example. In addition, the brake system is the 1 suitable for both an X-Bremskreisausteilung as well as for a parallel brake circuit distribution.

The brake system also includes a first piston-cylinder device 18a with an adjustable first piston 20a , which is a first volume to be filled with brake fluid 22a the first piston-cylinder device 18a limited to. The first volume 22a the first piston-cylinder device 18a is by means of an adjustment of the first piston 20a in a first braking direction 24a reducible while the first volume 22a by means of an adjustment of the first piston 20a against the first braking direction 24a is enlargeable. The first volume 22a the first piston-cylinder device 18a is hydraulic at least with the first brake circuit 14a connected.

In addition, the brake system still includes a separate from the first piston-cylinder device 18a trained second piston-cylinder device 18b , The second piston-cylinder device 18b is with a second piston 20b fitted. A second volume that can be filled with brake fluid 22b lies in the second piston-cylinder device 18b and is from the adjustable second piston 20b limited. While the second volume 22b by means of an adjustment of the second piston 20b in a second braking direction 24b is reducible, causes an adjustment of the second piston 20b against the second braking direction 24b an increase in the second volume 22b , The second volume 22b is hydraulic at least with the second brake circuit 14b connected.

By means of the first piston-cylinder device 18a and the second piston-cylinder device 18b is a total brake fluid volume optionally from the first brake circuit 14a and the second brake circuit 14b sucked out or into the first brake circuit 14a and the second brake circuit 14b depressible, which is at least equal to a sum of a first maximum volume of the first volume 22a and a second maximum volume of the second volume 22b is. (In a particularly advantageous possibility for interaction of the first piston-cylinder device 18a and the second piston-cylinder device 18b for effecting a total brake fluid volume greater than the sum of the first maximum volume and the second maximum volume, in particular as a continuous volume flow, will be discussed below.) Even with a comparatively small design of the first piston-cylinder device 18a and the second piston-cylinder device 18b Therefore, the total brake fluid volume is still comparatively large. This means significant brake pressure increases and brake pressure reductions in both brake circuits 14a and 14b even with a comparatively small design of the piston-cylinder devices 18a and 18b through their joint interaction feasible. At the same time is the use of two piston-cylinder devices 18a and 18b with respect to a single (conventional) pressure point unit designed for such a total brake fluid volume, with the advantage that each of the two piston-cylinder devices 18a and 18b compared to the single pressure unit only reduced drive and support forces must apply. In contrast to the single pressure point unit can therefore cost-effective components for the two piston-cylinder devices 18a and 18b be used. This reduces the to realize a possibility for optional brake pressure increase or brake pressure reduction in both brake circuits 14a and 14b the cost of the brake system.

Under a separate configuration of the first piston-cylinder device 18a from the second piston-cylinder device 18b can be understood that neither the first piston 20a still the first volume 22a to the second piston-cylinder device 18b adjacent and neither the second piston 20b still the second volume 22b to the first piston-cylinder device 18b adjoin. In particular, it can be understood that no power transmission path between the first piston 20a and the second piston 20b (bypassing at least one connected thereto piston engine) is present. Above all, under the separate training of the first piston-cylinder device 18a from the second piston-cylinder device 18b an exclusion of a support of the second piston 20b on the first piston 20a and / or the first piston 20a on the second piston 20b be understood by at least one spring.

The first piston-cylinder device 18a and the second piston-cylinder device 18b can on or in a (common) hydraulic power unit 26 be formed of the brake system. For example, the first piston-cylinder device 18a on or in one of the hydraulic power unit 26 formed present first bore / receiving opening, which can be filled with brake fluid part volume as the first volume 22a from the first bore adjustably arranged in the first bore 20a is limited. Accordingly, the second piston-cylinder device 18b on or in one of the hydraulic power unit 26 formed second bore / receiving opening, which can be filled with brake fluid part volume as a second volume 22b from the second bore adjustably arranged second piston 20b is limited, be formed. In this case, the first bore is formed separately from the second bore. By this it can be understood that the first bore does not intersect with the second bore and that neither bore joins the other bore. In particular, the first bore may have a first outer edge on at least one outer surface of the hydraulic unit 26 while the second bore also has one on the at least one outer surface of the hydraulic power unit 26 lying second outer edge, wherein the first outer edge does not overlap with the second outer edge. It is noted, however, that the braking system of 1 instead of the hydraulic unit 26 may also have corresponding individual components.

In the embodiment of the 1 is the first piston 20a such on a first engine 28 connected to a (not sketched) first axis of rotation that the first piston 20a by means of an operation of the first motor 28a within the first piston-cylinder device 18a (in the first braking direction 24a or against the first Einbremsrichtung 24a ) is adjustable. The first braking direction 24a is along or parallel to the first axis of rotation (of the first motor 28a ). In addition, the second piston 20b such on a second engine 28b connected to a (not shown) second axis of rotation that the second piston 20b by means of an operation of the second motor 28b within the second piston-cylinder device 18b (in the second braking direction 24b or against the second braking direction 24b ) is adjustable. Also the second braking direction 24b is along or parallel to the second axis of rotation (of the second motor 28b ).

Because the piston-cylinder facilities 18a and 18b In comparison to the prior art, only reduced drive and support forces have to be able to afford, cost-effective and little space-consuming engine models for the first engine 28a and for the second engine 28b be used. It is also noted that instead of the two engines 28a and 28b even a single / common engine (possibly together with a single spindle) for common / simultaneous operation of the two piston-cylinder devices 18a and 18b can be used. In this case, the Einbremsrichtungen 24a and 24b aligned along or parallel to an axis of rotation of the single / common motor.

The braking system of 1 has a Kreistrennung / Bremskreistrennung its brake circuits 14a and 14b on. By this it can be understood that the first volume 22a only on the first brake circuit 14a hydraulically tethered while the second volume 22b only on the second brake circuit 14b hydraulically connected. This is feasible over a from the first volume 22a up to the first brake circuit 14a extending line section 30a and another from the second volume 22b to the second brake circuit 14b extending line section 30b , Optionally, a first isolation valve 32a in the line section 30a and / or a second isolation valve 32b in the line section 30b be used. If desired, each of the piston-cylinder device 18a or and 18b from the associated brake circuit 14a or 14b be decoupled.

In addition, the first volume 22a via a first hydraulic path 34a at the brake fluid reservoir 12 tethered. Also the second volume 22b is via a second hydraulic path 34b hydraulically with the brake fluid reservoir 12 connected. The hydraulic paths 34a and 34b may have a common line section. Preferably, a first check valve 36a in the first hydraulic path 34a and / or a second check valve 36b in the second hydraulic path 34b arranged. By means of an orientation of the at least one check valve 36a and 36b is to ensure that brake fluid from the brake fluid reservoir 12 in the first volume 22a or in the second volume 20b refillable while a brake fluid shift from the first volume 22a into the brake fluid reservoir 12 or from the second volume 22b into the brake fluid reservoir 12 is prevented.

Advantageously, the brake system also has a control device 38 on, by means of which the first engine 28a and the second engine 28b are controllable. The control device 38 may in particular be designed to be the first motor 28a (by means of a first control signal 40a ) for executing a first target speed (nonzero) and the second motor 28b (by means of a second control signal 40b ) to execute a deviating from the first target speed second target speed (not equal to zero) to control. Thus, despite being perpendicular to its first Einbremsrichtung 24a aligned first piston diameter d1 of the first piston 20a equal to one perpendicular to its second Einbremsrichtung 24b aligned second piston diameter d2 of the second piston 20b (or at a direction perpendicular to the first Einbremsrichtung 24a aligned first volume diameter of the first volume 22a equal to one perpendicular to the second braking direction 24b aligned second volume diameter of the second volume 22b ) different levels of brake pressure increases or brake pressure reductions in the brake circuits 14a and 14b effected. This can contribute to the improvement of stability of the vehicle equipped with the braking system (even with rapid deceleration).

Likewise, the control device 38 however, in at least one mode of operation, the first motor 28a and the second engine 28b (eg by means of only a single control signal) to drive to execute a same target speed. For example, the control device 38 in the at least one operating mode adapted to the first motor 28a and the second engine 28b to operate in synchronism. By this it can be understood that the first engine 28a and the second engine 28b be controlled such that the first piston 20a the same (without a phase difference) to the second piston 20b is adjusted. This means that during an adjustment of the first piston 20a in its first braking direction 24a also the second piston 20b in its second braking direction 24b is adjusted, and during an adjustment of the first piston 20a against its first Einbremsrichtung 24a the second piston 20b against its second Einbremsrichtung 24b is adjusted. In this case, one can also from a co-incident, in-phase or phase-difference operation of the piston-cylinder devices 18a and 18b speak.

As an alternative or as a supplement, the control device 38 in the at least one operating mode for operating the first motor 28a and the second motor 28b be designed in the opposite direction. In this case, the first engine 28a and the second engine 28b controlled such that the first piston 20a opposite (with a phase difference of 180 °) to the second piston 20b is adjusted. By this it can be understood that during an adjustment of the first piston 20a in its first braking direction 24a the second piston 20b against its second Einbremsrichtung 24b is adjusted, and during an adjustment of the first piston 20a against its first Einbremsrichtung 24a the second piston 20b in its second braking direction 24b is adjusted. This is also considered to be an inverse or 180 degree out of phase operation of the piston-cylinder devices 18a and 18b rewritable, which by means of arrows 41a and 41b in 1 is reproduced.

By means of the counter-rotating or 180 ° phase-shifted operation of the piston-cylinder devices 18a and 18b is a continuous flow can be generated, which a fast and / or strong brake pressure increase in both brake circuits 14a and 14b simultaneously. During an adjustment of the first piston 20a in its first braking direction 24a for pressing brake fluid (via the open-controlled first isolation valve 32a ) in the first brake circuit 14a is by means of a simultaneous adjustment of the second piston 20b against its second Einbremsrichtung 24b Brake fluid via the second check valve 36b from the brake fluid reservoir 12 nachsaugbar. (Pressing brake fluid from the first volume 22a into the brake fluid reservoir 12 is by means of the first check valve 36a prevented while sucking brake fluid from the second brake circuit 14b in the second volume 22b by means of the closed-controlled second separating valve 32b is preventable.) Accordingly, during an adjustment of the first piston 20a against its first Einbremsrichtung 24a for sucking in brake fluid via the second check valve 36b from the brake fluid reservoir 12 by means of a simultaneous adjustment of the second piston 20b in its second braking direction 24b Brake fluid (via the open-controlled second isolation valve 32b ) in the second brake circuit 14b pressed. (Pressing brake fluid from the second volume 22b into the brake fluid reservoir 12 is by means of the second check valve 36b prevented while sucking brake fluid from the first brake circuit 14a in the first volume 22a by means of the closed-controlled first separating valve 32a is preventable.) The control device 38 can also be used to control the isolation valves 32a and 32b be designed. In addition, by means of a (in addition to a rod piston 10a ) in the master cylinder 10 existing floating piston 10b which is adjustable between one on the first brake circuit 14a connected first pressure chamber 10c (eg a rod piston chamber) and one on the second brake circuit 14b connected second pressure chamber 10d (For example, a floating piston chamber) is arranged for an equal pressure increase in both brake circuits 14a and 14b be taken care of.

The synchronous operation of the piston-cylinder devices 18a and 18b or the opposite operation of the piston-cylinder devices 18a and 18b can also be carried out provided the pistons 20a and 20b connected to a single / common engine. For example, the pistons 20a and 20b on a common spindle, which is displaceable by means of the single / common motor in a rotational movement lie. By means of the connection of the pistons 20a and 20b to the single / common engine can be determined whether the piston-cylinder devices 18a and 18b be operated in synchronism or in reverse. The piston-cylinder devices 18a and 18b can be either as a parallel arrangement or as a serial Arrangement to be connected to the single / common engine.

In the embodiment of the 1 is every brake circuit 14a and 14b of the brake system via a respective additional isolation valve 42a and 42b on the master cylinder 10 tethered. Thus, after closing the isolation valve 42a at least one first brake pressure in the at least one first wheel brake cylinder 16a of the first brake circuit 14a and / or after closing the isolation valve 42b at least one second brake pressure in the at least one second wheel brake cylinder 16b of the second brake circuit 14b be varied without a driver pressing one on the master cylinder 10 Tethered brake actuator (brake pedals) 44 a repercussion of it feels. At the same time, the driver's brake request by means of the piston-cylinder devices 28a and 28b are performed, including the control device 38 at least one (not sketched) sensor signal of at least one brake actuation element sensor 46 , such as a pedal travel sensor, rod travel sensor and / or driver brake force sensor, can be taken into account. Likewise, the piston-cylinder facilities 18a and 18b However, also be used to vary the at least one first brake pressure and / or the at least one second brake pressure so that despite an additional use of a regenerative electric motor for recuperative braking the driver's braking request is not exceeded. It is noted, however, that the equipment of the brake system with the isolation valves 42a and 42b is optional.

In the embodiment of the 1 has the brake system for every wheel brake cylinder 16a and 16b also ever a Radeinlassventil 48a and 48b and one wheel outlet valve each 50a and 50b , On the wheel inlet valves 48a and 48b and / or the wheel outlet valves 50a and 50b but can also be dispensed with.

As an optional further training, the braking system is the 1 still with a simulator 52 equipped with a simulator separator valve 54 and a check valve arranged in parallel thereto 56 on the master cylinder 10 is connected. (Complementing is the simulator 52 still with the hydraulic reservoir 12 Also optional is an in 1 shown connection of a Schnüffelbohrung the master cylinder 10 via an electrically controllable valve 58 and a check valve arranged in parallel thereto 60 to the brake fluid reservoir 12 ,

The brake system can have at least one admission pressure sensor 62 and / or pressure sensor 64 to have. Likewise, at least one rotation rate sensor 66 on the at least one engine 28a and 28b be connected.

In a Krerehennung / brake circuit separation of the brake system, it is often advantageous if the first piston 20a one perpendicular to its first Einbremsrichtung 24a aligned first piston diameter d1, which is greater or smaller than a perpendicular to its second Einbremsrichtung aligned second piston diameter d2 of the second piston 20b is. In this case, even at the same speed of the motors 28a and 28b a first volume of brake fluid between the first volume 22a and the first brake circuit 14a and a second volume of brake fluid not equal to the first volume of brake fluid between the second volume 22b and the second brake circuit 14b be transferred. Thus, different degrees of brake pressure increases or brake pressure reductions in the two brake circuits 14a and 14b in a simple way effected simultaneously. Also in this way, stability of the vehicle equipped with the braking system can be improved (even with rapid deceleration).

2 shows a schematic representation of a second embodiment of the brake system.

At the in 2 Brake system shown is not formed Kreereich identification / brake circuit separation. Instead, that's the first volume 22a via a third check valve 70a hydraulically with both the first brake circuit 14a as well as with the second brake circuit 14b connected. Corresponding is also the second volume 22b via a fourth check valve 70b hydraulically with both the first brake circuit 14a as well as with the second brake circuit 14b connected. By means of an alignment of the third check valve 70a , or the fourth check valve 70b , is a brake fluid displacement from the first brake circuit 14a and the second brake circuit 14b in the first volume 22a , or in the second volume 20b , can not be stopped. For example, the first volume 22a over the third check valve 70a and the second volume 22b over the fourth check valve 70b at a common line section 72 be connected, of which a line section 74a (preferably with the first isolation valve 32a ) to the first brake circuit 14a and a line section 74b (Preferably with the second isolation valve 32b ) to the first brake circuit 14b extend.

Preferably, the control device 38 in the brake system of 2 designed the piston-cylinder devices 18a and 18b in the opposite or 180 ° phase-shifted operation to control. While the first piston-cylinder device 18a eg in a working stroke, is the second piston-cylinder device 18b in a suction phase. (When adjusting the first piston 20a in its first braking direction 24a for pressing brake fluid (via the third check valve 70a ) in the first brake circuit 14a is by means of a simultaneous adjustment of the second piston 20b against its second Einbremsrichtung 24b Brake fluid via the second check valve 36b from the brake fluid reservoir 12 nachsaugbar. Pressing brake fluid from the first volume 22a into the brake fluid reservoir 12 is by means of the first check valve 36a prevented while sucking brake fluid from the second brake circuit 14b in the second volume 22b by means of the fourth check valve 70b can be prevented.) Accordingly, it is ensured that during a power stroke of the second piston-cylinder device 18b the first piston-cylinder device 18a present in their intake phase. Thus, there is always pressure / brake fluid available. A snooping is not necessary. This means strong and fast brake pressure increases in both brake circuits 14a and 14b for highly dynamic processes.

As an alternative or in addition to this, the control device 38 also be designed to the piston-cylinder devices 18a and 18b to control the synchronous operation or simultaneous operation with different target speeds. It is also noted that the braking system of the 2 even with only a single / common engine for operating the piston-cylinder devices 18a and 18b can be equipped. Also in this case, by means of the connection of the piston 20a and 20b be set to the single / common engine, whether the piston-cylinder devices 18a and 18b be operated in synchronism or in reverse.

This in 2 Brake system shown realizes a high reliability. Due to the continuous volume flow, no reset times are lost. In addition, inexpensive components can be used for its realization. Regarding the further characteristics of the braking system of 2 Reference is made to the description of the previous embodiment.

3 FIG. 12 is a flowchart for explaining an embodiment of the method of operating a brake system of a vehicle.

The method described below may e.g. be executed on one of the previously discussed brake systems. It should be understood, however, that a practicability of the method is not limited to use of any of the brake systems described above.

The method has the method steps S1 and S2. By means of the method steps S1 and S2, both a first brake fluid quantity in a first brake circuit connected to a master brake cylinder of the brake system can be increased or reduced by at least one connected first wheel brake cylinder, and a second brake fluid quantity in a second brake circuit connected to the master brake cylinder with at least one connected second Wheel brake cylinders increased or reduced. This is done by operating in the method step S1 a first piston-cylinder device whose first volume which can be filled with brake fluid is hydraulically connected at least to the first brake circuit. The first piston-cylinder device is understood to mean a device in which the first volume is delimited by an (adjustable) first piston, which is adjusted by means of a first motor with a first axis of rotation in or against a first braking direction of the first piston, which is aligned along or parallel to the first axis of rotation.

In addition, in the method step S2, a second piston-cylinder device formed separately from the first piston-cylinder device, whose second volume which can be filled with brake fluid is hydraulically connected at least to the second brake circuit, is additionally operated. The second piston-cylinder device is understood to mean a device in which the second volume is delimited by a second piston, which is adjusted by means of the first motor or a second motor with a second axis of rotation in or against a second braking direction of the second piston which is aligned along or parallel to the respective axis of rotation.

The method steps S1 and S2 can be carried out in particular simultaneously. In an advantageous embodiment of the method, the first motor is driven to execute a first setpoint speed (not equal to zero), while at the same time the second motor is driven to execute a second setpoint speed (not equal to zero) deviating from the first setpoint speed. In a further advantageous embodiment of the method, the first motor and the second motor are controlled such that the first piston is moved in opposite directions to the second piston. Alternatively, the first motor and the second motor may also be controlled so that the first piston is adjusted in the same direction to the second piston. Thus, those described above can also be realized by means of the method described here.

QUOTES INCLUDE IN THE DESCRIPTION

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Cited patent literature

• DE 102011004983 A1 [0002]

Claims (12)

Hydraulic unit ( 26 ) for a brake system of a vehicle comprising: a first partial brake circuit or brake circuit ( 14a ), which on a hydraulic unit-own master cylinder ( 10 ) or attachable to a non-hydraulic master cylinder master cylinder, and to which at least one first wheel brake cylinder ( 16a ) is connectable or connected; a second partial brake circuit or brake circuit ( 14b ), which on the respective master cylinder ( 10 ) is attached or attachable, and to which at least one second wheel brake cylinder ( 16b ) is connectable or connected; and one in the hydraulic power unit ( 26 ) formed first bore, which can be filled with brake fluid first volume ( 22a ) of a first piston adjustably arranged in the first bore ( 20a ) to which a first motor ( 28a ) is connected or connectable with a first axis of rotation in such a way that the first piston ( 20a ) by means of an operation of the first motor ( 28a ) at least in a along or parallel to the first axis of rotation aligned first Einbremsrichtung ( 24a ) is adjustable, wherein the first volume ( 22a ) hydraulically at least with the first partial brake circuit or brake circuit ( 14a ) connected is; and wherein a second volume which can be filled with brake fluid ( 22b ), which hydraulically at least with the second partial brake circuit or brake circuit ( 14b ) is connected by an adjustably arranged second piston ( 20b ) to which the first motor ( 28a ) or a second motor ( 28b ) is connected or connectable with a second axis of rotation such that the second piston ( 20b ) by means of an operation of the respective engine ( 28b ) at least in a along or parallel to the respective axis of rotation aligned second Einbremsrichtung ( 24b ) is adjustable; characterized in that the second volume ( 20b ) in a separate from the first bore in the hydraulic power unit ( 26 ) formed second bore is located. Hydraulic unit ( 26 ) according to claim 1, wherein the first piston ( 20a ) one perpendicular to its first Einbremsrichtung ( 24a ) aligned first piston diameter (d1), which is greater or smaller than a perpendicular to its second Einbremsrichtung ( 24b ) aligned second piston diameter (d2) of the second piston ( 20b ). Hydraulic unit ( 26 ) according to claim 1 or 2, wherein the first volume ( 22a ) via a first check valve ( 32a ) hydraulically with both the first partial brake circuit or brake circuit ( 14a ) as well as with the second partial brake circuit or brake circuit ( 14b ) and / or the second volume ( 22b ) via a second check valve ( 32b ) hydraulically with both the first partial brake circuit or brake circuit ( 14a ) as well as with the second partial brake circuit or brake circuit ( 14b ) connected is. Braking system for a vehicle comprising: a master cylinder ( 10 ); one on the master cylinder ( 10 ) connected first brake circuit ( 14a ), on which at least one first wheel brake cylinder ( 16a ) is connected; one on the master cylinder ( 10 ) connected second brake circuit ( 14b ), on which at least one second wheel brake cylinder ( 16b ) is connected; and a first piston-cylinder device ( 18a ) with an adjustable first piston ( 20a ), which can be filled with brake fluid first volume ( 22a ) of the first piston-cylinder device ( 18a ) and to which a first motor ( 28a ) is connected to a first axis of rotation such that the first piston ( 20a ) by means of an operation of the first motor ( 28a ) at least in a first braking direction ( 24a ), which is aligned along or parallel to the first axis of rotation, wherein the first volume ( 22a ) hydraulically at least with the first brake circuit ( 14a ) connected is; and wherein a second volume which can be filled with brake fluid ( 22b ), which hydraulically at least with the second brake circuit ( 14b ) is connected by an adjustable second piston ( 20b ) to which the first motor ( 28a ) or a second motor ( 28b ) is connected to a second axis of rotation such that the second piston ( 20b ) by means of an operation of the respective engine ( 28b ) at least in a second braking direction ( 24b ) is adjustable, which is aligned along or parallel to the respective axis of rotation; characterized in that the second volume ( 22b ) in a separate from the first piston-cylinder device ( 18a ) and with the second piston ( 20b ) equipped second piston-cylinder device ( 18b ) lies. Brake system according to claim 4, wherein the first piston ( 20a ) one perpendicular to its first Einbremsrichtung ( 24a ) aligned first piston diameter (d1), which is greater or smaller than a perpendicular to its second Einbremsrichtung ( 24b ) aligned second piston diameter (d2) of the second piston ( 20b ). Braking system according to claim 4 or 5, wherein the first volume ( 20a ) via a first check valve ( 32a ) hydraulically with both the first brake circuit ( 14a ) as well as with the second brake circuit ( 14b ) and / or the second volume ( 22b ) via a second check valve ( 32b ) hydraulically with both the first brake circuit ( 14a ) as well as with the second brake circuit ( 14b ) connected is. Brake system according to one of claims 4 to 6, wherein the brake system comprises a control device ( 38 ), by means of which the first motor ( 28a ) and the second motor ( 28b ) are controllable. Brake system according to claim 7, wherein the control device ( 38 ) is adapted to the first motor ( 28a ) for executing a first target speed and the second motor ( 28b ) to execute a deviating from the first target speed second target speed to control. Braking system according to claim 7 or 8, wherein the control device ( 38 ) is adapted to the first motor ( 28a ) and the second motor ( 28b ) in such a way that the first piston ( 20a ) in opposite directions to the second piston ( 20b ) is adjustable. Method for operating a braking system of a vehicle, comprising the steps of: increasing or reducing a first quantity of brake fluid in a master cylinder ( 10 ) of the brake system connected first brake circuit ( 14a ) with at least one connected first wheel brake cylinder ( 16a ) and / or increasing or reducing a second quantity of brake fluid in one of the master cylinder ( 10 ) connected second brake circuit ( 14b ) with at least one connected second wheel brake cylinder ( 16b ) by - operating a first piston-cylinder device ( 18a ), which can be filled with brake fluid first volume ( 22a ) hydraulically at least with the first brake circuit ( 14a ) and which of a first piston ( 20a ), which by means of a first motor ( 28a ) with a first axis of rotation in or against a first Einbremsrichtung ( 24a ) of the first piston ( 20a ) which is aligned along or parallel to the first axis of rotation (S1); characterized by additionally operating a separate from the first piston-cylinder device ( 18a ) formed second piston-cylinder device ( 18b ), which can be filled with brake fluid second volume ( 22b ) hydraulically at least with the second brake circuit ( 14b ), and which of a second piston ( 20b ), which by means of the first motor ( 28a ) or a second motor ( 28b ) with a second axis of rotation in or against a second braking direction ( 24b ) of the second piston ( 20b ), which is aligned along or parallel to the respective axis of rotation (S2). The method of claim 10, wherein the first motor ( 28a ) is driven to execute a first target speed and the second motor ( 28b ) is driven to execute a deviating from the first target speed second target speed. Method according to claim 10 or 11, wherein the first motor ( 28a ) and the second motor ( 28b ) are controlled such that the first piston ( 20a ) in opposite directions to the second piston ( 20b ) is adjusted.

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