Method for shutdown of vehicle brakes

A method for controlling vehicle brakes comprising:

• providing a pedal driven primary piston that pressurizes hydraulic fluid for no-boost manual actuation of the vehicle brakes in proportion to pedal travel so that the driver feels pedal resistance in proportion to pedal travel;
• providing a source of pressure boosted hydraulic fluid;
• selectively closing off communication of the hydraulic fluid between the vehicle brakes and the primary piston and opening communication of the pressure boosted hydraulic fluid to the vehicle brakes to provide pressure boosted actuation of the vehicle brakes;
• providing a spring loaded simulator in hydraulic fluid communication with the primary piston to provide spring induced resistance to the pedal driven primary piston in proportion to the force exerted on the pedal while the communication of hydraulic fluid between the vehicle brakes and the primary piston is closed off so that the driver feels resistance in proportion to pedal travel even though the primary piston is isolated from the pressure at the wheel brakes;
• and upon a shutdown of pressure boosted actuation of the vehicle brakes, comparing the boosted pressure at the vehicle brakes with the simulator provided pressure provided on the pedal, and
• reopening communication of the hydraulic fluid between the vehicle brakes and the primary piston and closing communication of the pressure boosted hydraulic fluid to the wheel brakes when the boosted pressure and simulator pressure are sufficiently equal that the driver will not experience a pedal disturbance;
• when the boosted pressure exceeds the simulator pressure to a magnitude that would create a pedal disturbance, reducing the boosted pressure over time until the boosted pressure and simulator pressure are substantially equal and then reopening communication of the hydraulic fluid between the vehicle brakes and the primary piston and closing communication of the pressure boosted hydraulic fluid to the wheel brakes,
• when upon a shutdown of pressure boosted actuation of the vehicle brakes by a shutdown of the vehicle, the driver is not depressing the pedal or releases the pedal, reopening communication of hydraulic fluid between the primary piston and the vehicle brakes without delay as the driver cannot be disturbed by any pedal disturbance when the driver is not depressing the brake pedal;
• and
• when there is a fault in the vehicle brakes, reopening communication of hydraulic fluid between the primary piston and the vehicle brakes without delay irrespective of the possibility of a pedal disturbance.

A method for controlling a vehicle brakes comprising:

• providing no boost manual braking at vehicle start up and vehicle shutdown via a master cylinder having a pedal driven primary piston that pressurizes hydraulic fluid in a primary piston chamber and furnishes the pressurized hydraulic fluid to the wheel brakes, with the driver feeling the hydraulic pressure as pedal resistance;
• providing pressure boosted braking during normal running operation of the vehicle by closing an isolation valve to cut off the communication of primary piston chamber from the wheel brakes and then modulating boosted hydraulic pressure from an accumulator to the vehicle brakes, with the driver feeling hydraulic pressure provided to the primary piston chamber by a pedal simulator spring to simulate a pedal resistance in proportion to the boosted pressure at the wheel brakes;
• and, upon vehicle shutdown or brake system fault during pressure boosted braking, comparing the pressure at the primary piston chamber with the boosted pressure at the vehicle brakes, and operating the boost valve to ramp down the boosted pressure to the primary piston chamber pressure over a period over a period of time, and then when the primary chamber pressure and the boosted pressure are substantially equal, reopening the isolation valve to restore the direct communication between the primary piston chamber and the wheels brakes without disturbing the pedal;
• when upon vehicle shutdown during pressure boosted braking, the driver is not depressing the pedal or releases the pedal, reopening communication of hydraulic fluid between the primary piston chamber and the vehicle brakes during the ramp down as the driver cannot be disturbed by any pedal disturbance when the driver is not depressing the brake pedal;
• and,
• when there is a fault in the vehicle brakes, reopening communication of hydraulic fluid between the primary chamber and the vehicle brakes during the ramp down irrespective of the possibility of a pedal disturbance.