| 摘要 |
A brake system and method of controlling the system are disclosed. The system provides secondary hydraulic braking in a de-energized mode. The system includes a wheel brake associated with wheels of a vehicle typically at each corner of the vehicle. The wheel brake typically includes a caliper or drum for deceleration of the vehicle. The system includes a master cylinder in fluid communication with the wheel brake. In the de-energized mode, the master cylinder operates the wheel brake. A solenoid isolation valve decouples the master cylinder from the wheel brake when the system is in a normal, i.e., an energized, mode. As such, the master cylinder is isolated from the wheel brake and is prevented from operating the wheel brake. Alternatively, in the de-energized mode, the isolation valve couples the master cylinder with the wheel brake to provide the secondary hydraulic braking. The system includes an actuator assembly for operation of the wheel brake independent of the master cylinder when the system is in the energized operational mode. A second, normally-closed, solenoid valve opens in the energized mode to couple the actuator assembly with the wheel brake. The second solenoid valve closes in the de-energized mode to isolate the actuator assembly from the wheel brake such that the secondary hydraulic braking is provided through the master cylinder.
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