Claims
- 1. A brake system for providing secondary hydraulic braking in a de-energized operational mode, said system comprising:
a wheel brake assembly including a brake application device; a master cylinder in fluid communication with said wheel brake assembly for operation of said brake application device when said brake system is in the de-energized operational mode; a first valve disposed between said master cylinder and said wheel brake assembly to decouple said master cylinder from said wheel brake assembly in an energized operational mode such that said master cylinder is prevented from operating said brake application device in the energized operational mode, and to couple said master cylinder with said wheel brake assembly in the de-energized operational mode such that said master cylinder can operate said brake application device in the de-energized operational mode to provide the secondary hydraulic braking through said master cylinder; an actuator assembly in fluid communication with said wheel brake assembly for operation of said brake application device independent of said master cylinder when said brake system is in the energized operational mode; and a second valve disposed between said actuator assembly and said wheel brake assembly, said second valve being normally-closed such that said second valve is open in the energized operational mode to couple said actuator assembly with said wheel brake assembly in the energized operation mode to allow said actuator assembly to operate said brake application device, and is closed in the de-energized operational mode to isolate said actuator assembly from said wheel brake assembly in the de-energized operational mode such that the secondary hydraulic braking is provided through said master cylinder.
- 2. A brake system as set forth in claim 1 further comprising a controller operatively connected to said actuator assembly for activating said actuator assembly to operate said brake application device independent of said master cylinder when said brake system is in the energized operational mode.
- 3. A brake system as set forth in claim 2 further comprising a motor disposed in said actuator assembly, said controller activating said motor to operate said brake application device.
- 4. A brake system as set forth in claim 3 further comprising a screw device and a piston disposed in said actuator assembly wherein, said motor, upon activation, rotates said screw device to advance said piston and increase hydraulic pressure to said brake application device.
- 5. A brake system as set forth in claim 4 wherein said second valve is disposed in said actuator assembly between said piston and said wheel brake assembly.
- 6. A brake system as set forth in claim 2 further comprising a brake pedal assembly operatively connected to said master cylinder for operation of said brake application device.
- 7. A brake system as set forth in claim 6 wherein said controller is operatively connected to said brake pedal assembly, said controller activating said actuator assembly in response to an input to said brake pedal assembly thereby operating said brake application device independent of said master cylinder when said brake system is in the energized operational mode.
- 8. A brake system as set forth in claim 7 further comprising a first pressure sensor monitoring said input to said brake pedal assembly and providing said controller with command signals relating to said input for activating said actuator assembly in the energized operational mode.
- 9. A brake system as set forth in claim 1 further comprising a first hydraulic line extending between said master cylinder and said wheel brake assembly, said first hydraulic line enabling the fluid communication for operation of said brake application device by said master cylinder during the de-energized operational mode.
- 10. A brake system as set forth in claim 9 further comprising a second hydraulic line extending between said actuator assembly and said wheel brake assembly, said second hydraulic line enabling the fluid communication for operation of said brake application device by said actuator assembly.
- 11. A brake system as set forth in claim 10 further comprising a second pressure sensor disposed between said actuator assembly and said wheel brake assembly for monitoring hydraulic pressure in said second hydraulic line.
- 12. A brake system as set forth in claim 10 wherein said second valve, upon closing in the de-energized operational mode, isolates at least a portion of said second hydraulic line such that the secondary hydraulic braking is provided from said master cylinder through said first hydraulic line.
- 13. A brake system as set forth in claim 1 further comprising an emulator device in fluid communication with said master cylinder for receiving hydraulic fluid from said master cylinder when said wheel brake assembly is decoupled from said master cylinder in the energized operational mode.
- 14. A brake system as set forth in claim 1 in combination with a vehicle having a plurality of wheels.
- 15. A brake system as set forth in claim 14 further comprising a plurality of wheel brake assemblies wherein one wheel brake assembly is associated with each of said wheels.
- 16. A brake system as set forth in claim 15 wherein said master cylinder is in fluid communication with each of said wheel brake assemblies.
- 17. A brake system as set forth in claim 16 further comprising a plurality of actuator assemblies, each actuator assembly including a second valve wherein one actuator assembly is disposed at each of said wheels and is in fluid communication with each wheel brake assembly associated with said wheel.
- 18. A brake system as set forth in claim 17 further comprising four first valves disposed between said master cylinder and each of said wheel brake assemblies.
- 19. A brake system as set forth in claim 18 further comprising an emulator assembly wherein said four first valves are all disposed within the emulator assembly.
- 20. A brake system as set forth in claim 1 wherein said brake application device is a brake caliper.
- 21. A brake system as set forth in claim 1 wherein said brake application device is a brake drum.
- 22. A method of controlling a brake system having secondary hydraulic braking in a de-energized operational mode wherein the brake system includes a wheel brake assembly having a brake application device, a master cylinder in fluid communication with the wheel brake assembly for operation of the brake application device in the de-energized operational mode, a first valve disposed between the master cylinder and the wheel brake assembly, an actuator assembly in fluid communication with the wheel brake assembly for operation of the brake application device independent of the master cylinder in an energized operational mode, a normally-closed second valve disposed between the actuator assembly and the wheel brake assembly, and a pressure sensor disposed between the actuator assembly and the wheel brake assembly, said method comprising the steps of:
energizing the first valve to decouple the master cylinder from the wheel brake assembly such that the master cylinder is prevented from operating the brake application device in the energized operational mode; energizing the normally-closed second valve to couple the actuator assembly with the wheel brake assembly to allow the actuator assembly to operate the brake application device; activating the actuator assembly in response to a first input to produce an operational pressure that operates the brake application device independent of the master cylinder in the energized operational mode; de-energizing the first valve to couple the master cylinder with the wheel brake assembly such that the master cylinder can operate the brake application device in the de-energized operational mode to provide the secondary hydraulic braking through the master cylinder; and de-energizing the normally-closed second valve while the first valve is de-energized to isolate the actuator assembly from the wheel brake assembly in the de-energized operational mode such that the secondary hydraulic braking is provided through said master cylinder.
- 23. A method as set forth in claim 22 further comprising the step of sensing the operational pressure produced by the actuator assembly to determine if the operational pressure remains constant for greater than a predetermined time interval.
- 24. A method as set forth in claim 23 further comprising the step of de-energizing the normally-closed second valve while the first valve is energized to isolate the actuator assembly from the wheel brake assembly thereby maintaining constant operational pressure.
- 25. A method as set forth in claim 24 further comprising the step of deactivating the actuator assembly.
- 26. A method as set forth in claim 25 further comprising the step of reactivating the actuator assembly in response to a second input that is different than said first input.
- 27. A method as set forth in claim 26 further comprising the step of re-energizing the normally-closed second valve while the first valve is energized to couple the actuator assembly with the wheel brake assembly thereby modifying the operational pressure in response to the second input.
- 28. A method of controlling a brake system having primary hydraulic braking through an actuator assembly of the brake system in an energized operational mode and secondary hydraulic braking through a master cylinder of the brake system in a de-energized operational mode, said method comprising the steps of:
energizing a first valve to decouple the master cylinder from a wheel brake assembly having a brake application device such that the master cylinder is prevented from operating the brake application device in the energized operational mode; energizing a normally-closed second valve to couple the actuator assembly with the wheel brake assembly to allow the actuator assembly to operate the brake application device; providing a first input to the actuator assembly through a brake input device; activating the actuator assembly in response to the first input to produce an operational pressure that operates the brake application device independent of the master cylinder in the energized operational mode thereby providing the primary hydraulic braking through the actuator assembly; de-energizing the first valve to couple the master cylinder with the wheel brake assembly such that the master cylinder can operate the brake application device in the de-energized operational mode to provide the secondary hydraulic braking through the master cylinder; and de-energizing the normally-closed second valve while the first valve is de-energized to isolate the actuator assembly from the wheel brake assembly in the de-energized operational mode such that the secondary hydraulic braking is provided through the master cylinder.
RELATED APPLICATIONS
[0001] This patent application claims priority to and all advantages of U.S. Provisional Patent Application No. 60/241,715 which was filed on Oct. 19, 2000.
Provisional Applications (1)
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Number |
Date |
Country |
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60241715 |
Oct 2000 |
US |