Method for operating a brake system for a motor vehicle and brake system

1. A method in which a brake system for a motor vehicle is at least one of controlled and regulated, said motor vehicle having at least one electrically regenerative brake and a hydraulic pressure-medium-operated brake system with friction brakes, wherein wheel brakes assigned to the individual wheels are arranged in at least two brake circuits which can be charged with pressure medium by a first brake pressure generating means, and wherein each brake circuit comprises at least one pressure accumulator and at least two electronically activatable hydraulic valves, such that during a braking process with the one or more electrically regenerative brakes, by activation of at least one hydraulic valve, at a point in time, the pressure medium is discharged only into one predetermined pressure accumulator,

wherein inlet and outlet hydraulic valves of the wheel brakes, in the two brake circuits are activated such that firstly the pressure accumulator of a first one of the brake circuits and subsequently the pressure accumulator of a second one of the brake circuits is filled.

2. The method as claimed in claim 1 , wherein the first brake pressure generating means is a tandem master brake cylinder.

3. The method as claimed in claim 1 , wherein a filling of a pressure accumulator is carried out via the outlet valve of only one of the wheel brakes of the first brake circuit.

4. The method as claimed in claim 1 , wherein one of the two wheel brakes of at least one brake circuit is charged with a predefined pressure medium volume, and said wheel brake is subsequently hydraulically isolated, through the closure of the associated inlet valve, from the first brake pressure generating means and from the associated pressure accumulator.

5. The method as claimed in claim 4 , wherein the wheel brake is hydraulically isolated when a first predefined measure of an actuation of a brake actuation pedal is attained, the first predefined measure being detected by at least one of a pedal angle sensor and a switch.

6. The method as claimed in claim 5 , wherein firstly a filling of a pressure accumulator is commenced via the outlet valve of one of the two wheel brakes, and a wheel brake of a first brake circuit is hydraulically isolated when the first predefined measure of the brake actuation is attained.

7. The method as claimed in claim 4 , wherein the filling of the pressure accumulators is ended and the hydraulically isolated wheel brake is connected to the first brake pressure generating means again when a third predefined measure of an actuation of a brake actuation pedal is attained, wherein the third predefined measure is detected by a pedal angle sensor and corresponds to a predefined value of the braking torque provided by the electrically regenerative brake or brakes.

8. The method as claimed in claim 7 , wherein the predefined value of the braking torque provided by the electrically regenerative brake or brakes is a predefined fraction of a maximum delivered braking torque of the electrically regenerative brake or brakes.

9. The method as claimed in claim 4 , wherein the filling of the pressure accumulators is ended and the hydraulically isolated wheel brake is connected to the first brake pressure generating means again when the difference between the pressure measured at a position of the first brake circuit and the pressure measured at a position of the second brake circuit exceeds a predefined threshold value.

10. The method as claimed in claim 1 , wherein if the braking torque delivered by the electrically regenerative brake or brakes is lower than the braking torque demanded by the driver, the first brake pressure generating means is hydraulically isolated from the wheel brakes through the closure of a hydraulic valve, and a brake medium is delivered from both pressure accumulators into the wheel brakes by a second brake pressure generating means.

11. The method as claimed in claim 10 , wherein the second brake pressure generating means is a hydraulic pump.

12. A method in which a brake system for a motor vehicle is at least one of controlled and regulated, said motor vehicle having at least one electrically regenerative brake and a hydraulic pressure-medium-operated brake system with friction brakes, wherein wheel brakes assigned to the individual wheels are arranged in at least two brake circuits which can be charged with pressure medium by a first brake pressure generating means and wherein each brake circuit comprises at least one pressure accumulator and at least two electronically activatable hydraulic valves, such that during a braking process with the one or more electrically regenerative brakes, by activation of at least one hydraulic valve, at a point in time, the pressure medium is discharged only into one predetermined pressure accumulator,

wherein one of the two wheel brakes of at least one brake circuit is charged with a predefined pressure medium volume, and said wheel brake is subsequently hydraulically isolated, through the closure of the associated inlet valve, from the first brake pressure generating means and from the associated pressure accumulator, and

wherein the filling of one pressure accumulator is ended and the filling of the other pressure accumulator is commenced when a second predefined measure of an actuation of a brake actuation pedal is attained, wherein the second predefined measure is detected by a pedal angle sensor and corresponds to a predefined value of the braking torque provided by the electrically regenerative brake or brakes.

13. The method as claimed in claim 12 , wherein the predefined value of the braking torque provided by the electrically regenerative brake or brakes is a predefined fraction of a maximum delivered braking torque of the electrically regenerative brake or brakes.

14. A method in which a brake system for a motor vehicle is at least one of controlled and regulated, said motor vehicle having at least one electrically regenerative brake and a hydraulic pressure-medium-operated brake system with friction brakes, wherein wheel brakes assigned to the individual wheels are arranged in at least two brake circuits which can be charged with pressure medium by a first brake pressure generating means, and wherein each brake circuit comprises at least one pressure accumulator and at least two electronically activatable hydraulic valves, such that during a braking process with the one or more electrically regenerative brakes, by activation of at least one hydraulic valve, at a point in time, the pressure medium is discharged only into one predetermined pressure accumulator, wherein the actuation of the hydraulic valves of a brake circuit takes place in an alternating fashion, such that during one braking process, a first inlet valve is closed and a first outlet valve is opened while a second inlet valve remains open and a second outlet valve remains closed, and in the subsequent braking process, the second inlet valve is closed and the second outlet valve is opened, while the first inlet valve and outlet valve are not actuated.