Pressure supply device with double stroke piston for a brake system
A brake system for a vehicle has at least one pressure supply device which is connected to a brake circuit via a hydraulic line. Furthermore, the brake system has a hydraulic connection between at least one of the brake circuits and an accumulator container, said connection being switchable via at least one outlet switch valve, and the pressure supply device has a double stroke piston with a working stroke and a return stroke. The double stroke piston can be at least partly emptied via the outlet switch valve.
1. A brake system for a vehicle, comprising the following components:
at least two hydraulic brake circuits, each with at least one hydraulically acting wheel brake;
at least one pressure supply device, which is connected via a hydraulic line to a brake circuit;
an associated switching valve for each hydraulically acting wheel brake, which switching valve switchably connects in each case one hydraulically acting wheel brake to one of the two brake circuits;
wherein the at least one pressure supply device includes a motor, which has a redundant winding and/or a connection with 2×3 phase control;
at least one hydraulic connection, which is switchable by means of several outlet valves, between at least one of the brake circuits and a reservoir; and
a piston, of which a hydraulic output is coupled, in a manner switchable by means of an infeed switching valve, to at least one brake circuit;
wherein the at least one pressure supply device has a double-action piston with forward stroke and return stroke, and wherein an at least partial evacuation of the double-action piston into the reservoir is enabled to be performed via solenoid valves located at a pressure chamber of the double-action piston.
2. The brake system as claimed in claim 1 , wherein pressure reduction in the at least one hydraulically acting wheel brake is performed by opening of the outlet switching valve and of the associated switching valve.
3. The brake system as claimed in claim 1 , wherein each hydraulically acting wheel brake is assigned an outlet switching valve which is connected to the reservoir.
4. The brake system as claimed in claim 1 , wherein the double-action piston is, in the forward stroke, connected via a first valve to at least one of the brake circuits, wherein the first valve is a check valve that closes in a direction of the at least one pressure supply device, or wherein the first valve is a first solenoid valve.
5. The brake system as claimed in claim 1 , wherein an effective piston area in a return stroke of the double-action piston is at least 10% smaller than an effective piston area in the forward stroke.
6. The brake system as claimed in claim 1 , wherein the motor is a brushless DC motor.
7. The brake system as claimed in claim 1 , wherein the associated switching valves are designed and connected such that a residual pressure in a wheel brake opens the associated switching valve in an electrically deenergized state.
8. The brake system as claimed in claim 1 , wherein closed-loop anti-lock braking system (ABS) and/or electronic stability (ESP) control is enabled to be performed by means of at least one of the associated switching valves and the outlet switching valve.
9. The brake system as claimed in claim 1 , wherein only the outlet switching valve connects the brake circuits switchably to the reservoir.
10. The brake system as claimed in claim 1 , wherein each wheel brake has only the associated switching valve.
11. The brake system as claimed in claim 1 , further comprising a hydraulic brake pedal system having a single master cylinder.
12. The brake system as claimed in claim 11 , wherein the hydraulic brake pedal system has a ventilation opening which is connected to the reservoir via a parallel circuit of a throttle and a check valve which closes toward the reservoir.
13. The brake system as claimed in claim 1 , wherein a pressure increase is performed in at least one of the brake circuits in the return stroke via an opened or opening second solenoid valve.
14. The brake system as claimed in claim 1 , wherein the double-action piston, in the forward stroke, is connected to the reservoir via a check valve, which opens toward the pressure supply device, and a solenoid valve.
15. The brake system as claimed in claim 1 , wherein the double-action piston, in the return stroke, is connected to the reservoir via a check valve, which opens toward the pressure supply device, and a solenoid valve.
16. The brake system as claimed in claim 1 , wherein an effective piston area in a return stroke of the double-action piston is at least 60% smaller than an effective piston area in the forward stroke.