WO2020043652A1

WO2020043652A1 - Control device and method for determining an actual variable relating to a flow factor of at least one wheel outlet valve of a dual-circuit brake system of a vehicle

Info

Publication number: WO2020043652A1
Application number: PCT/EP2019/072683
Authority: WO
Inventors: Yasutaka NAGAKURA
Original assignee: Robert Bosch Gmbh
Priority date: 2018-08-28
Filing date: 2019-08-26
Publication date: 2020-03-05
Also published as: DE102018214548A1

Abstract

The invention relates to a control device (24) and to a method for determining an actual variable relating to a flow factor of at least one wheel outlet valve (20a, 20b) of a dual-circuit brake system of a vehicle by determining whether a target storage volume is to be transferred into a first storage chamber (16a) of a first brake circuit (10a) having a first maximum storage volume and/or into a second storage chamber (16b) of a second brake circuit (10b) having a second maximum storage volume; if a target storage volume less than at least the first maximum storage volume is to be transferred, switching only one of the first wheel outlet valves (20a) of the first brake circuit (10a) arranged upstream of the first storage chamber (16a) to an opening degree greater than zero, while all other wheel outlet valves (20b, 22a, 22b) of the brake system, including a second wheel outlet valve (20b) of the second brake circuit (10b) arranged upstream of the second storage chamber (16b), are kept closed, and determining a first actual variable with respect to a first flow factor of the first wheel outlet valve (20a) when the degree of opening thereof is greater than zero on the basis of sensor signals (54) of a pressure sensor (56) of the brake system.

Description

description

title

Control device and method for determining an actual variable with regard to a flow factor of at least one wheel outlet valve of a two-circuit

Brake system of a vehicle

The invention relates to a control device for a dual-circuit braking system of a vehicle. The invention also relates to a dual-circuit brake system for a vehicle. Furthermore, the invention relates to a method for

Determining an actual variable with regard to a flow factor of at least one wheel outlet valve of a dual-circuit brake system of a vehicle and a method for operating a dual-circuit brake system.

State of the art

DE 10 2016 208 529 A1 describes a brake system and a method for operating such a brake system, the brake system comprising two brake circuits, each with two wheel brake cylinders and one storage chamber each. Each of the wheel brake cylinders is connected to the associated storage chamber via a wheel outlet valve. To blend one

Brake fluid volume is at least one wheel outlet valve per

Brake circuit at least partially opened, so that to be veneered

Brake fluid volume is transferred to both storage chambers of the two brake circuits of the brake system via the opened wheel outlet valves.

Disclosure of the invention

The invention provides a control device for a dual-circuit brake system of a vehicle with the features of claim 1, a dual-circuit brake system for a vehicle with the features of claim 6, a method for determining an actual variable with regard to a flow factor of at least one wheel outlet valve of a dual-circuit brake system of a vehicle with the features of claim 7 and a method for

Operating a dual-circuit braking system of a vehicle with the

Features of claim 9. Advantages of the invention

The present invention creates possibilities for individual valve

Determining an actual variable with regard to a specific flow factor of at least one wheel outlet valve of a dual-circuit brake system of a vehicle, despite the formation of such a brake system, as a rule with at least one wheel outlet valve per brake circuit. Under the

Flow factor of the respective wheel outlet valve can also be a

Flow coefficient of the respective wheel outlet valve, more effective

Cross section / opening cross section of the respective wheel outlet valve or a Kv value of the respective wheel outlet valve can be understood. The flow factor is usually given with the unit m ³ / h (cubic meters per hour). The flow factor of the respective wheel outlet valve is generally dependent on an opening degree of the respective wheel outlet valve. With a nominal stroke of a wheel outlet valve, ie with an opening degree of the respective one

Wheel outlet valve of 100%, the flow factor is often also referred to as the Kvs value, which indicates the maximum possible throughput through the respective wheel outlet valve.

The at least one actual variable determined individually for the valve by means of the present invention can advantageously also be taken into account when the dual-circuit brake system is operated later. By means of the

Taking into account the at least one actual variable determined individually for the valve when actuating the wheel outlet valves of the dual-circuit brake system, in particular the target storage volume to be transferred can be maintained more reliably. This can ensure that that too

transferring target storage volume is reliably transferred into the first storage chamber of the first brake circuit and / or into the second storage chamber of the second brake circuit, and at the same time transferring too much brake fluid, which can either be removed from the respective storage chamber by means of at least one pump or an undesirable one Pre-filling of the incompletely emptied storage chamber causes is prevented. Taking into account the at least one actual variable determined individually for the valve when actuating the wheel outlet valves of the dual-circuit brake system also allows a more precise pressure setting / pressure control in the

dual circuit braking system. The present invention thus contributes to Improve the operation and safety standards of dual-circuit brake systems.

The present invention in particular creates possibilities for

valve-specific determination of the flow factor of at least one continuously switchable wheel outlet valve of a two-circuit brake system. A continuously switchable wheel outlet valve is to be understood as a valve type which, in addition to its closed state (with an opening degree of 0%) and its fully open state (with an opening degree of 100%), also in at least one at least partially open state (with a

Degree of opening greater than 0% and less than 100%) is controllable / switchable. However, it is pointed out that a usability of the present invention is not limited to continuously switchable valves. For example, the respective flow factor can also be designed for a switching valve

Wheel outlet valve of a two-circuit brake system can be determined individually for the wheel by means of the present invention. The switching valve is understood to mean a valve type which can only be controlled / switched in its closed state or in its fully open state. A

The usability of the present invention is also not limited to the design of the respective wheel outlet valve as a de-energized closed wheel outlet valve. The respective wheel outlet valve can alternatively also be a de-energized open wheel outlet valve.

The present invention is also advantageously suitable for the detection of

Deviations in the flow factor of a wheel outlet valve from a target flow factor due to production deviations or aging effects. For example, production deviations and / or aging effects in a solenoid valve used as a wheel outlet valve can influence one

Have adjustability of an adjustable valve element of the solenoid valve by means of a magnetic field caused by energizing at least one solenoid coil of the solenoid valve. For example, a magnetic force triggered on the adjustable valve element of the normally closed magnetic valve by the magnetic field caused can be increased compared to a standard situation in such a way that the normally closed magnetic valve is opened further than desired by means of the magnetic force. By means of the present invention, however, such a deviation of the flow factor of the respective solenoid valve from the target flow factor can be reliably detected, and by a Responding appropriately can transfer too much

Brake fluid can be prevented in the storage chamber downstream of the solenoid valve.

In an advantageous embodiment of the control device

Electronic device additionally designed to only transfer the second wheel outlet valve into one in the case of a further target storage volume to be transferred smaller than at least the second maximum storage volume

To switch opening degree greater than zero and to keep all other wheel outlet valves of the brake system closed, and based on the degree of opening greater than zero during the presence of the second wheel outlet valve

provided sensor signals of the pressure sensor to determine a second actual variable with respect to a second flow factor of the second wheel outlet valve with its degree of opening greater than zero. The one described here

Embodiment of the control device can thus be used to determine both the first actual variable with respect to the first flow factor of the first

Evaluate the wheel outlet valve of the first brake circuit and the second actual variable with regard to the second flow factor of the second wheel outlet valve of the second brake circuit, the sensor signals of the same pressure sensor. The embodiment of the control device described here therefore only requires the one pressure sensor, optionally connected to the first brake circuit or to the second brake circuit, to carry out its advantageous function. It is therefore not necessary to equip the two brake circuits of the brake system with their own pressure sensor.

In a further advantageous embodiment of the control device, the electronic device is additionally designed to compare the first actual variable and the second actual variable with one another and / or with a predetermined target variable, and the first wheel outlet valve and / or the second one on the basis of the comparison Specify the wheel outlet valve as the valve to be used for blending. The control device can thus control the operation of the two-circuit brake system actuated thereby with regard to advantageous suitability of only the first wheel outlet valve, only the second

Wheel outlet valve or the first wheel outlet valve and the second

Optimize the wheel outlet valve. In particular, if both the first wheel outlet valve and the second wheel outlet valve are defined as valves to be used for blending, the electronic device can be designed to alternately define the first wheel outlet valve or the second wheel outlet valve as the valve currently to be used for blending and for the next desired target to be transferred. Storage volume less than a minimum of the first maximum

Storage volume and the second maximum storage volume or less than a predetermined limit volume below the minimum to switch only the valve currently to be used for blending to an opening degree greater than zero and to keep all other wheel outlet valves of the brake system closed. The intermediate storage of target storage volumes alternately only in the first storage chamber or only in the second storage chamber protects components of both storage chambers, such as their seals. The embodiment of the control device described here thus contributes to extending the life of both storage chambers compared to the prior art described above.

If only the first wheel outlet valve or only the second wheel outlet valve is defined as the valve to be used for blending, the electronic device is preferably designed to be smaller than the minimum or the predetermined for each desired storage volume to be transferred

Limit volume only the valve to be used for blending into one

Switch opening degree greater than zero and keep all other wheel outlet valves of the brake system closed. Thus, the embodiment of the control device described here for transferring desired storage volumes only uses the wheel outlet valve that is reliably suitable for this purpose and does not share the other wheel outlet valve, which is only suitable to a limited extent. This contributes to more reliable compliance with the

transferring target storage volume.

A dual-circuit brake system with such a control device also brings about the advantages already explained above.

Likewise, executing a corresponding method for determining an actual variable with regard to a flow factor of at least one wheel outlet valve of a dual-circuit brake system of a vehicle also brings about the advantages described above. The procedure for determining an actual size With regard to a flow factor of at least one wheel outlet valve of a dual-circuit brake system of a vehicle, the control device can be further developed in accordance with the above-explained embodiments.

Furthermore, executing a corresponding method for operating a dual-circuit brake system of a vehicle also creates the advantages explained above. The method for operating a dual-circuit brake system of a vehicle can also be carried out in accordance with those explained above

Embodiments of the control device are developed.

Brief description of the drawings

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

Fig. 1 is a schematic representation of an embodiment of the

Control device, or a two-circuit braking system equipped therewith;

Fig. 2 is a flowchart for explaining an embodiment of the

Method for determining an actual variable with regard to a flow factor of at least one wheel outlet valve of a dual-circuit brake system of a vehicle; and

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

Method for operating a dual-circuit braking system of a vehicle.

Embodiments of the invention

Fig. 1 shows a schematic representation of an embodiment of the

Control device, or a two-circuit equipped with it

Braking system.

The dual-circuit brake system shown schematically in FIG. 1 has a first brake circuit 10a with two wheel brake cylinders 12a and 14a and a first storage chamber 16a and a second brake circuit 10b with two Wheel brake cylinders 12b and 14b and a second storage chamber 16b.

The first brake circuit 10a and the second brake circuit 10b are on one

Master brake cylinder 18 of the dual-circuit brake system connected.

In addition, the braking system has at least one of the first

Storage chamber 16a upstream of the first wheel outlet valve 20a of the first brake circuit 10a and a second wheel outlet valve 20b upstream of the second storage chamber 16b. Optionally, each brake circuit 10a and 10b can also be designed with a further wheel outlet valve 22a or 22b in such a way that each wheel brake cylinder 12a, 12b, 14a and 14b of the brake system via “its own wheel outlet valve” 20a, 20b, 22a or 22b with the associated storage chamber 16a or 16b is connected. In the

1, the first wheel outlet valve 20a and the second wheel outlet valve 20b are each a continuously switchable valve, while the further wheel outlet valves 22a and 22b are each a switching valve. However, the ability of the brake system to be configured is not limited to the valve types of the wheel outlet valves 20a, 20b, 22a and 22b shown in FIG. 1.

The brake system of FIG. 1 can have, for example, an X brake circuit division, so that each brake circuit 10a and 10b each has a first one

Has wheel brake cylinders 12a or 12b assigned to the vehicle axle and one wheel brake cylinder 14a or 14b each assigned to a second vehicle axis. Alternatively, the braking system can also be used for a parallel one

Brake circuit division are used. It is expressly pointed out here that the usability described below can be used

Control device 24 is neither restricted to the braking system shown in FIG. 1 nor to a special vehicle type / motor vehicle type of the vehicle / motor vehicle equipped with the braking system.

The control device 24 has an electronic device 26 which is designed to control at least the wheel outlet valves 20a, 20b, 22a and 22b of both brake circuits 10a and 10b of the brake system. As an advantageous further development, the electronic device 26 can also be designed to have at least one high-pressure switching valve 28a and 28b, at least one

Changeover valve 30a and 30b, at least one wheel inlet valve 32a, 32b, 34a and 34b, at least one pump motor 36 at least one pump 38a and 38b and / or at least one upstream of the master brake cylinder 18

To control brake booster 40. When controlling the Electronics device 26 at least one provided or determined

Information regarding a target storage volume

Brake fluid volume to be transferred from the master brake cylinder 18 into the first storage chamber 16a and / or into the second storage chamber 16b. For example, when a brake actuation element 42 is actuated by a driver, the electronic device recognizes the driver's brake request on the basis of at least one signal 44 from a brake actuation element sensor 46, and then uses information 48 provided to determine the current executability of the

Driver braking request by means of a recuperative operation of at least one electric motor of the vehicle that can be used as a generator, whether the brake fluid volume in the wheel brake cylinders 12a, 12b, 14a and 14b that is pushed out of the master brake cylinder 18 by the driver by actuating the brake actuation element 42 is required completely, or at least partially to be transferred as a target storage volume into at least one of the storage chambers 16a and 16b.

The electronic device 26 is additionally designed to switch only the first wheel outlet valve 20a to an opening degree greater than zero by means of at least one first control signal 50a in the case of a desired storage volume to be transferred, which is smaller than at least a first maximum storage volume of the first storage chamber 16a, and, during the presence of the first wheel outlet valve 20a in its degree of opening greater than zero, to keep all other wheel outlet valves 20b, 22a and 22b of the braking system closed by means of at least one second control signal 50b. The first maximum storage volume of the first storage chamber 16a is to be understood as a volume that can be maximally displaced into the first storage chamber 16a at the current time. In addition, the electronic device 26 is designed to use a sensor signal 54 of a pressure sensor 56 of the brake system of a pressure sensor 56 of the brake system, which is provided during the presence of the first wheel outlet valve 20a in its degree of opening greater than zero (and the keeping of all other wheel outlet valves 20b, 22a and 22b), to provide a first actual value with respect to one to determine the first flow factor of the first wheel outlet valve 20a with its degree of opening greater than zero. The control device 24 is thus suitable for the valve-specific determination of the first actual variable with respect to the first flow factor of the first wheel outlet valve 20a, despite the design of the braking system with two brake circuit 10a and 10 equipped with wheel outlet valve 10b. The first actual variable determined individually for the valve can be, for example, the first

Flow factor of the first wheel outlet valve 20a, a first effective one

Cross section / opening cross section of the first wheel outlet valve 20a and / or a first Kv value of the first wheel outlet valve 20a, in particular a first Kvs value of the first wheel outlet valve 20a.

Preferably, the electronic device 26 is additionally designed, in the case of a further target storage volume to be transferred, which is smaller than at least a second maximum storage volume of the second

Storage chamber 16b is to switch only the second wheel outlet valve 20b (for example by means of the at least one first control signal 50a) to an opening degree greater than zero, and, when the second wheel outlet valve 20b is present in its opening degree greater than zero, all other wheel outlet valves 20a, 22a and 22b of the brake system (for example by means of the at least one second control signal 50b), and on the basis of sensor signals 54 of the pressure sensor 56 provided during the presence of the second wheel outlet valve 20b in its degree of opening greater than zero (and the keeping of all other wheel outlet valves 20a, 22a and 22b) to determine a second actual variable with respect to a second flow factor of the second wheel outlet valve 20b with its degree of opening greater than zero. In this case, the control device 24 is also suitable for the valve-specific determination of the second actual variable with respect to the second flow factor of the second wheel outlet valve 20b. The second actual variable determined individually for the valve can, for example, be the second flow factor of the second wheel outlet valve 20b, a second effective cross section / opening cross section of the second wheel outlet valve 20b and / or a second Kv value of the second wheel outlet valve 20b, in particular a second Kvs value of the second wheel outlet valve 20b , his. The second maximum storage volume of the second storage chamber 16b is to be understood as a volume that can be displaced to a maximum in the second storage chamber 16b at the current time.

As is clear from the preceding description, the control device 24 / its electronic device 26 only requires the single pressure sensor 56 to determine the first actual variable with regard to the first flow factor of the first wheel outlet valve 20a and the second actual variable with regard to the second flow factor of the second wheel outlet valve 20b , wherein the only pressure sensor 56 optionally on the first brake circuit 10a or on the second Brake circuit 10b can be connected. A further pressure sensor is not necessary for the function of the control device 24 / its electronic device 26 described here, so that a space requirement of the further pressure sensor that is not required and its manufacturing costs can be saved.

The at least one actual variable determined individually for the valve can also be taken into account by the electronic device 26 during subsequent operation of the brake system, in particular during the next desired storage volume to be shifted into the first storage chamber 16a and / or into the second storage chamber 16b. In this way, the target storage volume to be shifted can be maintained more reliably.

As an advantageous further development, the electronic device 26 can additionally be designed to determine the valve-specific first actual variable and the

to compare the valve-specific second actual variable with one another and / or with a predetermined target variable, and on the basis of the comparison the first wheel outlet valve 20a and / or the second wheel outlet valve 20b as

Define the valve to be inserted. In this case, preference is given to the first storage chamber 16a and / or the second

Storage chamber 16b to be shifted target storage volume, provided that it is smaller than a minimum of the first maximum storage volume and the second maximum storage volume or smaller than a predetermined

Limit volume is below the minimum, only that is at least one as of

The valve to be inserted is inserted so that the

corresponding target storage volume corresponding

Brake fluid volume is only displaced into the at least one downstream storage chamber 16a or 16b via the at least one valve to be used for blending.

For example, if both the first wheel outlet valve 20a and the second wheel outlet valve 20b are defined as valves to be used for blending, the electronic device 26 is designed to alternately define the first wheel outlet valve 20a or the second wheel outlet valve 20b as the valve currently to be used for blending, and in next to

transferring target storage volume smaller than the minimum or smaller than the predetermined limit volume only to switch the valve currently to be used for blending to an opening degree greater than zero, and, during the Existence of the valve to be used for blending in its

Degree of opening greater than zero to keep all other wheel outlet valves of the brake system closed. If only the first wheel outlet valve 20a or only the second wheel outlet valve 20b is defined as the valve to be used for blending, the electronic device 26 is advantageously designed to only use the valve to be blended in for each desired storage volume to be transferred smaller than the minimum or the predetermined limit volume to switch an opening degree greater than zero, and, during the

If the valve to be used for blending is greater than zero in its opening degree, all other wheel outlet valves of the brake system must be kept closed.

In the conventional procedure described above, a target storage volume to be transferred is shifted via one wheel brake cylinder per brake circuit into both storage chambers of both brake circuits. This is done without taking into account the respective flow factor of the wheel outlet valves or an appropriate size. Compared to the conventional procedure described above, the in the

Operation of the brake system described in the preceding paragraph by means of the control device 24 in the case of a brake master cylinder 18

extracted brake fluid volume a more precise compliance with the target storage volume to be transferred by using only the at least one valve to be used for blending, for which its suitability as a "blending valve" is verified on the basis of its respective valve-specific target size. In comparison to the conventional procedure, therefore, during operation of the brake system by means of the control device 24 there is no need to fear that either too much volume or too little volume will be buffered. The shifting of the desired storage volume into only one of the storage chambers 16a and 16b, which is carried out during operation of the brake system by means of the control device 24, also has the advantage over the conventional procedure described above that it is always known which current first volume in the first storage chamber 16a and which current second volume is present in the second storage chamber 16b. The at least one pump 38a and 38b can thus be easily controlled so that the at least one storage chamber 16a and 16b is reliably pumped empty. In contrast, in the conventional procedure described above, the two storage chambers are due to Deviations in the flow factors of the wheel outlet valves used for blending are often filled unequally, which is why, to empty the two storage chambers, either all pumps have to be operated longer or a remaining volume in one of the storage chambers has to be accepted.

FIG. 2 shows a flow chart for explaining an embodiment of the method for determining an actual variable with regard to a flow factor of at least one wheel outlet valve of a dual-circuit brake system of a vehicle.

In a method step S1, it is determined whether a target storage volume from a master brake cylinder of the brake system into a first storage chamber of a first brake circuit of the brake system with a first maximum storage volume and / or into a second storage chamber of a second brake circuit of the brake system with a second maximum

Storage volume is to be transferred. Method step S1 can be carried out as often as desired while the vehicle / motor vehicle is traveling.

If it is determined in method step S1 that a target storage volume smaller than at least the first maximum storage volume is to be transferred, method steps S2 and S3 are carried out. As method step S2, only a first wheel outlet valve of the first brake circuit upstream of the first storage chamber is switched to an opening degree greater than zero, while all other wheel outlet valves of the brake system, including a second wheel outlet valve of the second brake circuit upstream of the second storage chamber, are kept closed. In a method step S3, a first actual variable with respect to a first flow factor of the first wheel outlet valve with its opening degree greater than zero is determined on the basis of sensor signals of a pressure sensor of the brake system provided during the presence of the first wheel outlet valve with an opening degree greater than zero.

As an optional further development, method step S1 can be repeated at least once after method steps S2 and S3. If it is determined in method step S1 that a further target storage volume smaller than at least the second maximum storage volume is to be transferred, the optional method steps S4 and S5 can be carried out. In In this case, as method step S4, only the second wheel outlet valve is switched to an opening degree greater than zero, while all the others

Brake system wheel outlet valves are kept closed. In a method step S5, a second actual variable with respect to a second flow factor of the second wheel outlet valve with its degree of opening greater than zero is then determined on the basis of sensor signals of the pressure sensor provided during the presence of the second wheel outlet valve with an opening degree greater than zero.

The method described here is therefore also suitable for determining the respective actual size individually for the valve. The method cannot be carried out either on a specific brake system type or on a special one

Vehicle type / vehicle type limited.

3 shows a flowchart for explaining an embodiment of the method for operating a dual-circuit brake system of a vehicle.

When the method described here is carried out, first of all, using method steps S1 to S5 explained above, a first actual variable with respect to a first flow factor of the first wheel outlet valve

Degree of opening greater than zero and a second actual variable is determined with respect to a second flow factor of the second wheel outlet valve with an opening degree greater than zero. In a subsequent method step S10, the first actual variable and the second actual variable are compared with one another and / or with a predetermined target variable. Based on the comparison, the first

Wheel outlet valve and / or the second wheel outlet valve is defined as the valve to be used for blending.

In the embodiment described here, when the first actual variable is compared with the second actual variable, a difference between the actual variables is established. If the difference is below a predetermined difference threshold value, the first wheel outlet valve and the second wheel outlet valve are defined as valves to be used for blending. Otherwise, only that

Wheel outlet valve with the smaller actual size specified as the (only) valve to be used for blending. However, the first actual size and the second actual size can also (alternatively or additionally) be compared with the predetermined target size. In this case, preferably only the at least one wheel outlet valve, the actual size of which deviates by at most a predetermined maximum deviation from the predetermined target size, is defined as the at least one valve to be used for blending.

Method step S1 is then repeated at least once. If it is determined in method step S1 that a further target storage volume is to be transferred, the target storage volume is compared as method step Sil with a minimum of the first maximum storage volume and the second maximum storage volume or with a predetermined limit volume below the minimum. If the target storage volume is smaller than the minimum or smaller than the predetermined limit volume, the method is continued with a method step S12. Otherwise, the target storage volume is shifted into both storage chambers by means of a method step S13 via at least the openly controlled first wheel outlet valve and the simultaneously openly controlled second wheel outlet valve.

However, if the target storage volume to be transferred is smaller than the minimum or smaller than the specified limit volume, then in the

Method step S12 polls the at least one valve to be used for blending. If both the first in method step S10

If the wheel outlet valve and the second wheel outlet valve are defined as valves to be used for blending, the method is continued with a method step S14. In step S14

alternately the first wheel outlet valve or the second wheel outlet valve is defined as the valve to be used for blending before the method is continued with a step S15. Each time step S15 is carried out, only the valve currently to be used for blending is switched to an opening degree greater than zero, while all the other wheel outlet valves of the brake system are kept closed. Executing method step S15 alternately by means of the first wheel outlet valve or second wheel outlet valve, which is defined as the valve currently to be used for blending, ensures that alternately only the first storage chamber or only the second storage chamber is used for intermediate storage of the target storage volume. That way they can Lifetimes of the first storage chamber and the second storage chamber can be extended.

If only the first wheel outlet valve or only the second wheel outlet valve is defined as the valve to be used for blending in method step S10, the method continues with method step S16, wherein in method step S16 only the valve to be used for blending is switched to an opening degree greater than zero, while everyone else

Brake system wheel outlet valves are kept closed. By executing method step S16 instead of method steps S14 and S15, it can be ensured that only the valve to be used for blending for shifting brake fluid into the downstream one

Storage chamber is used, with a shared use of the as

Blending only conditionally suitable valve is dispensed with. Inaccuracies in the blending of the target storage volume to be transferred due to deviations in the functioning of the valve, which is only suitable to a limited extent, can thus be avoided.

The method described here also enables a valve-specific control of the target storage volume shifted into the respective storage chamber by taking into account the actual size determined for the valve currently to be used for blending when it is activated. An executability of the method is neither restricted to a specific brake system type nor to a special vehicle type / motor vehicle type. During execution of method step S15 or S16, the actual size of the wheel outlet valve used in each case can also be redetermined using the procedure described above. It may also be possible to react to aging effects suddenly occurring on one of the two wheel outlet valves.

Claims

Expectations

1. Control device (24) for a two-circuit braking system

Vehicle with: an electronic device (26), which is designed to

Consideration of a provided or ascertained information regarding a target storage volume, which from a master brake cylinder (18) of the brake system into a first storage chamber (16a) of a first brake circuit (10a) of the brake system with a first maximum storage volume and / or into a second storage chamber (16b ) of a second brake circuit (10b) of the brake system with a second maximum storage volume, at least one first wheel outlet valve (20a) upstream of the first storage chamber (16a) of the first brake circuit (10a) and / or at least one upstream of the second storage chamber (16b) to control the second wheel outlet valve (20b) of the second brake circuit (10b); characterized in that the electronic device (26) is additionally designed to switch only the first wheel outlet valve (20a) to an opening degree greater than zero and all other wheel outlet valves (20a, 22a) if the target storage volume to be transferred is smaller than at least the first maximum storage volume , 22b) of the brake system, and by means of sensor signals (54) of a pressure sensor (56) of the brake system provided during the presence of the first wheel outlet valve (20a) with an opening degree greater than zero, a first actual value with respect to a first flow factor of the first

To determine the wheel outlet valve (20a) with its degree of opening greater than zero.

2. Control device (24) according to claim 1, wherein the electronic device (26) is additionally designed to switch only the second wheel outlet valve (20b) to an opening degree greater than zero at a further target storage volume to be transferred smaller than at least the second maximum storage volume and to keep all other wheel outlet valves (20a, 22a, 22b) of the brake system closed, and based on sensor signals (54) of the pressure sensor (56) provided in the degree of opening greater than zero during the presence of the second wheel outlet valve (20b) relating to a second actual variable to determine a second flow factor of the second wheel outlet valve (20b) with its degree of opening greater than zero.

3. Control device (24) according to claim 2, wherein the electronic device (26) is additionally designed to compare the first actual variable and the second actual variable with one another and / or with a predetermined target variable, and based on the comparison that to define the first wheel outlet valve (20a) and / or the second wheel outlet valve (20b) as the valve to be used for blending.

4. Control device (24) according to claim 3, wherein, if both the first wheel outlet valve (20a) and the second wheel outlet valve (20b) are defined as valves to be used for blending, the electronic device (26) is designed to alternate the first wheel outlet valve ( 20a) or the second wheel outlet valve (20b) to be used as the valve currently to be blended, and for the next desired storage volume to be transferred less than a minimum of the first maximum storage volume and the second maximum storage volume or less than a predetermined limit volume below the minimum, only the current one for blending

switch the valve to be used into an opening degree greater than zero and keep all other wheel outlet valves of the brake system closed.

5. Control device (24) according to claim 3 or 4, wherein, if only the first wheel outlet valve (20a) or only the second wheel outlet valve (20b) is defined as a valve to be used for blending, the electronic device (26) is designed for each transferring target storage volume smaller than the minimum or the specified limit volume only that

Switching the valve to be used for opening to a degree of opening greater than zero and keeping all other wheel outlet valves of the brake system closed.

6. Dual circuit braking system for a vehicle comprising: a control device (24) according to any one of the preceding claims; the master brake cylinder (18); the first brake circuit (10a) connected to the master brake cylinder (18) with two wheel brake cylinders (12a, 14a), the first storage chamber (16a) and at least the first one upstream of the first storage chamber (16a)

Wheel outlet valve (20a); and the second brake circuit (10b) connected to the master brake cylinder (18) with two wheel brake cylinders (12b, 14b), the second storage chamber (16b) and at least the second wheel outlet valve (20b) upstream of the second storage chamber (16b).

7. Method for determining an actual size with respect to one

Flow factor of at least one wheel outlet valve (20a, 20b) of a dual-circuit brake system of a vehicle, with the steps:

Determine whether a target storage volume from a master brake cylinder (18) of the braking system into a first storage chamber (16a) of a first braking circuit (10a) of the braking system with a first maximum storage volume and / or into a second storage chamber (16b) of a second braking circuit (10b ) the braking system is to be transferred with a second maximum storage volume (Sl);

If a target storage volume smaller than at least the first maximum storage volume is to be transferred, only one of the first switches

Storage chamber (16a) upstream of the first wheel outlet valve (20a) of the first brake circuit (10a) into an opening degree greater than zero, while all other wheel outlet valves (20b, 22a, 22b) of the brake system including one of the second storage chamber (16b) upstream of the second wheel outlet valve (20b) second brake circuit (10b) are kept closed (S2); and

Determining a first actual variable with respect to a first flow factor of the first wheel outlet valve (20a) with its degree of opening greater than zero on the basis of during the presence of the first wheel outlet valve (20a) in it

Degree of opening greater than zero provided sensor signals (54) of a

Pressure sensor (56) of the brake system (S3).

8. The method according to claim 7, with the additional steps:

If a further target storage volume smaller than at least the second maximum storage volume is to be transferred, switching only the second one Wheel outlet valve (20b) into an opening degree greater than zero, while all other wheel outlet valves (20a, 22a, 22b) of the brake system are kept closed (S4); and

Determining a second actual variable with regard to a second flow factor of the second wheel outlet valve (20b) with its degree of opening greater than zero on the basis of sensor signals (54) of the pressure sensor (56) (S5) provided during the presence of the second wheel outlet valve (20b) with its degree of opening greater than zero .

9. A method for operating a dual-circuit braking system of a vehicle, comprising the steps:

Determining a first actual variable with respect to a first flow factor of the first wheel outlet valve (20a) with an opening degree greater than zero and a second actual variable with regard to a second flow factor of the second wheel outlet valve (20b) with an opening degree greater than zero according to the method of claim 8;

Comparing the first actual variable and the second actual variable with one another and / or with a predetermined target variable; and

Determining the first wheel outlet valve (20a) and / or the second

Wheel outlet valve (20b) as a valve to be used for blending based on the comparison (S10).

10. The method according to claim 9, wherein, if both the first

The wheel outlet valve (20a) and the second wheel outlet valve (20b) are defined as valves to be used for blending, the first wheel outlet valve (20a) or the second wheel outlet valve (20b) is alternately defined as the valve currently to be used for blending (S14), and the next one transferring target storage volume smaller than a minimum of the first maximum storage volume and the second maximum storage volume or smaller than a predetermined limit volume below the minimum, only the valve to be used for blending is switched to an opening degree greater than zero, while all other wheel outlet valves of the brake system are kept closed (S15).

11. The method according to claim 9 or 10, wherein, provided that only the first wheel outlet valve (20a) or only the second wheel outlet valve (20b) is defined as the valve to be used for blending, is smaller than the minimum or the predetermined for each target storage volume to be transferred

Limit volume only the valve to be used for blending into one

Degree of opening greater than zero is switched while all others

Brake system wheel outlet valves must be kept closed (S16).