davoodtayyebi
عضو جدید
ترمزهای ABS
ترمزهایABS
- شروع کننده موضوع davoodtayyebi
- تاریخ شروع
mohan
عضو جدید
Vehicle anti-lock brake system
Vehicle anti-lock brake system
Vehicle anti-lock brake system
Abstract
The present invention concerns a vehicle anti-lock brake control system which does not require the use of an auxiliary hydraulic pump and, in the preferred embodiment, is adapted to control only the rear brakes of a four-wheel vehicle. The control system includes a normally open solenoid actuated isolation valve connected between the master cylinder and the rear wheel brakes, and a normally closed solenoid actuated dump valve connected between the rear wheel brakes and a fluid accumulator. A computer control is connected to monitor the rear wheel speed and deceleration and, during breaking of the vehicle, functions to control the application of hydraulic pressure to the rear brakes via the isolation and dump valves in order to prevent lock-up of the brakes. In the event excessive rear wheel deceleration is detected during a vehicle stop, the computer control closes the isolation valve to hold pressure to the rear brakes at a relatively constant level. If, after the isolation...
The present invention concerns a vehicle anti-lock brake control system which does not require the use of an auxiliary hydraulic pump and, in the preferred embodiment, is adapted to control only the rear brakes of a four-wheel vehicle. The control system includes a normally open solenoid actuated isolation valve connected between the master cylinder and the rear wheel brakes, and a normally closed solenoid actuated dump valve connected between the rear wheel brakes and a fluid accumulator. A computer control is connected to monitor the rear wheel speed and deceleration and, during breaking of the vehicle, functions to control the application of hydraulic pressure to the rear brakes via the isolation and dump valves in order to prevent lock-up of the brakes. In the event excessive rear wheel deceleration is detected during a vehicle stop, the computer control closes the isolation valve to hold pressure to the rear brakes at a relatively constant level. If, after the isolation...
mohan
عضو جدید
ABS
ABS
1. In a wheeled vehicle having means for supplying pressurized brake fluid to actuate the associated wheel brakes of the vehicle, a brake control system for controlling the application of pressurized brake fluid to at least one selected wheel brake to control the braking of the associated wheel, said control system comprising:
2. The control system according to claim 1 wherein said control means includes means for sensing deceleration of the vehicle, said control means being operable to selectively open said isolation valve means to selectively increase pressure to the wheel brake to cause a third wheel speed departure after said second wheel speed departure has been corrected and the increase in deceleration of the vehicle has exceeded a predetermined amount, said control means operable to selectively open said dump valve means after said third wheel speed departure has been detected to selectively reduce pressure to the selected wheel brake to a third predetermined pressure.
3. The control system according to claim 2 wherein said third predetermined pressure is greater than said second predetermined pressure.
4. The control system according to claim 1 wherein said control means includes means for determining when the vehicle has approached an end-of-stop condition and for automatically operating said isolation valve means to apply and maintain additional pressure to the selected wheel brake when the vehicle is in said end-of-stop condition.
5. The control system according to claim 1 wherein said control means includes means for sensing the acceleration of the associated wheel during spin-up portions of said wheel speed departures, said control means being operable to selectively open said isolation valve means to selectively increase pressure to the selected wheel brake to cause a further wheel speed departure after a previous wheel speed departure has been corrected and the acceleration of the associated wheel during a spin-up portion of said previous wheel speed departure exceeds a predetermined rate.
6. The control system according to claim 5 wherein said previous wheel speed departure is said second wheel speed departure and said further wheel speed departure is a third wheel speed departure.
7. The control system according to claim 5 wherein said control means is operable to selectively open said dump valve means after said further wheel departure has been detected to selectively reduce pressure to the selected wheel brake to a third predetermined pressure.
8. The control system according to claim 7 wherein said third predetermined pressure is greater than said second predetermined pressure.
ABS
What is claimed is:
1. In a wheeled vehicle having means for supplying pressurized brake fluid to actuate the associated wheel brakes of the vehicle, a brake control system for controlling the application of pressurized brake fluid to at least one selected wheel brake to control the braking of the associated wheel, said control system comprising:
a normally open isolation valve means connected between the supply means and the selected wheel brake;
a normally closed dump valve means connected between the selected wheel brake and a fluid reservoir; and
control means connected to operate said isolation valve means and said dump valve means, said control means including means for detecting wheel speed departures of the associated wheel relative to the actual speed of the vehicle, said control means operable to close said isolation valve means to hold the fluid pressure to the selected wheel brake at a relatively constant level after a first wheel speed departure of the associated wheel is detected, said control means operable to selectively open said dump valve means after said isolation valve means has been closed to enable fluid to flow into said fluid reservoir to selectively reduce fluid pressure to the selected wheel brake to a first predetermined pressure and correct said first wheel speed departure, said control means further operable to selectively open said isolation valve to selectively increase pressure to the wheel brake to cause a second wheel speed departure after said first wheel speed departure has been corrected, said control means operable to selectively open said dump valve means after said second wheel speed departure has been detected to selectively reduced pressure to the selected wheel brake to a second predetermined pressure greater than said first predetermined pressure.
a normally closed dump valve means connected between the selected wheel brake and a fluid reservoir; and
control means connected to operate said isolation valve means and said dump valve means, said control means including means for detecting wheel speed departures of the associated wheel relative to the actual speed of the vehicle, said control means operable to close said isolation valve means to hold the fluid pressure to the selected wheel brake at a relatively constant level after a first wheel speed departure of the associated wheel is detected, said control means operable to selectively open said dump valve means after said isolation valve means has been closed to enable fluid to flow into said fluid reservoir to selectively reduce fluid pressure to the selected wheel brake to a first predetermined pressure and correct said first wheel speed departure, said control means further operable to selectively open said isolation valve to selectively increase pressure to the wheel brake to cause a second wheel speed departure after said first wheel speed departure has been corrected, said control means operable to selectively open said dump valve means after said second wheel speed departure has been detected to selectively reduced pressure to the selected wheel brake to a second predetermined pressure greater than said first predetermined pressure.
2. The control system according to claim 1 wherein said control means includes means for sensing deceleration of the vehicle, said control means being operable to selectively open said isolation valve means to selectively increase pressure to the wheel brake to cause a third wheel speed departure after said second wheel speed departure has been corrected and the increase in deceleration of the vehicle has exceeded a predetermined amount, said control means operable to selectively open said dump valve means after said third wheel speed departure has been detected to selectively reduce pressure to the selected wheel brake to a third predetermined pressure.
3. The control system according to claim 2 wherein said third predetermined pressure is greater than said second predetermined pressure.
4. The control system according to claim 1 wherein said control means includes means for determining when the vehicle has approached an end-of-stop condition and for automatically operating said isolation valve means to apply and maintain additional pressure to the selected wheel brake when the vehicle is in said end-of-stop condition.
5. The control system according to claim 1 wherein said control means includes means for sensing the acceleration of the associated wheel during spin-up portions of said wheel speed departures, said control means being operable to selectively open said isolation valve means to selectively increase pressure to the selected wheel brake to cause a further wheel speed departure after a previous wheel speed departure has been corrected and the acceleration of the associated wheel during a spin-up portion of said previous wheel speed departure exceeds a predetermined rate.
6. The control system according to claim 5 wherein said previous wheel speed departure is said second wheel speed departure and said further wheel speed departure is a third wheel speed departure.
7. The control system according to claim 5 wherein said control means is operable to selectively open said dump valve means after said further wheel departure has been detected to selectively reduce pressure to the selected wheel brake to a third predetermined pressure.
8. The control system according to claim 7 wherein said third predetermined pressure is greater than said second predetermined pressure.
9. The control system according to claim 1 wherein said control means includes means for monitoring the time said dump valve means has been open after said first wheel speed departure has been detected and prior to correction of said first wheel speed departure, said control means operable to selectively open said isolation valve means to increase pressure to the selected wheel brake after said dump valve means has been open during said first wheel speed departure for a predetermined time period.
mohan
عضو جدید
ABS
ABS
10. The control system according to claim 9 wherein, when said first wheel speed departure is detected, the speed of the associated wheel is greater than the speed of the vehicle.
11. The control means according to claim 1 wherein said control means includes means for sensing the deceleration of the associated wheel and is operable to initially open said dump valve during one of said wheel departures for a first dumping cycle until the deceleration of the associated wheel is less than a first predetermined amount to reduce pressure, said control means further operable to reopen said dump valve means for a second renewed dumping cycle to further reduce pressure when the deceleration of the associated wheel is greater than a second predetermined amount which is less than said first predetermined amount and an impending lock-up condition of the associated wheel has continued for a predetermined time period after said first dumping cycle is terminated.
12. The control system according to claim 1 wherein said vehicle includes front and rear wheel brakes and said control system controls the application of pressurized brake fluid only to said rear wheel brakes.
13. The control system according to claim 1 wherein said normally open isolation valve means includes first solenoid means for selectively closing said isolation valve, and said normally closed dump valve means includes second solenoid means for selectively opening said dump valve.
14. The control system according to claim 1 wherein said control means includes means coupled to monitor the speed of the associated wheel for generating a wheel speed signal, means responsive to said wheel speed signal for generating a speed ramp signal representing the speed the vehicle would travel if decelerated at a predetermined rate, and means for generating a slip signal when the difference between said speed ramp signal and said wheel speed signal exceeds a predetermined slip threshold.
15. The control system according to claim 14 wherein said control means includes means responsive to said slip signal for generating a dump signal to open said dump valve means to selectively reduce pressure to the selected wheel brake.
16. The control system according to claim 15 wherein said dump signal includes a series of dump pulses each having a width representing the time the dump valve means remains open.
ABS
10. The control system according to claim 9 wherein, when said first wheel speed departure is detected, the speed of the associated wheel is greater than the speed of the vehicle.
11. The control means according to claim 1 wherein said control means includes means for sensing the deceleration of the associated wheel and is operable to initially open said dump valve during one of said wheel departures for a first dumping cycle until the deceleration of the associated wheel is less than a first predetermined amount to reduce pressure, said control means further operable to reopen said dump valve means for a second renewed dumping cycle to further reduce pressure when the deceleration of the associated wheel is greater than a second predetermined amount which is less than said first predetermined amount and an impending lock-up condition of the associated wheel has continued for a predetermined time period after said first dumping cycle is terminated.
12. The control system according to claim 1 wherein said vehicle includes front and rear wheel brakes and said control system controls the application of pressurized brake fluid only to said rear wheel brakes.
13. The control system according to claim 1 wherein said normally open isolation valve means includes first solenoid means for selectively closing said isolation valve, and said normally closed dump valve means includes second solenoid means for selectively opening said dump valve.
14. The control system according to claim 1 wherein said control means includes means coupled to monitor the speed of the associated wheel for generating a wheel speed signal, means responsive to said wheel speed signal for generating a speed ramp signal representing the speed the vehicle would travel if decelerated at a predetermined rate, and means for generating a slip signal when the difference between said speed ramp signal and said wheel speed signal exceeds a predetermined slip threshold.
15. The control system according to claim 14 wherein said control means includes means responsive to said slip signal for generating a dump signal to open said dump valve means to selectively reduce pressure to the selected wheel brake.
16. The control system according to claim 15 wherein said dump signal includes a series of dump pulses each having a width representing the time the dump valve means remains open.
17. The control system according to claim 16 including means for varying the width of said dump pulses
mohan
عضو جدید
ABS
ABS
18. The control system according to claim 17 including means for varying the spacing between successive dump pulses.
19. The control system according to claim 14 wherein said control means includes means for generating a no slip signal when the difference between said speed ramp signal and said wheel speed signal is less than said predetermined slip threshold.
20. The control system according to claim 19 wherein said control means includes means responsive to said no slip signal for generating an apply signal to selectively open said isolation valve to increase pressure to the selected wheel brake.
21. The control system according to claim 20 wherein said apply signal includes a series of apply pulses each having a width representing the time the isolation valve means remains open.
22. The control system according to claim 21 including means for varying the width of said apply pulses.
23. The control system according to claim 22 including means for varying the spacing between successive apply pulses.
24. The control system according to claim 14 wherein said control means includes means for increasing said slip threshold for a predetermined time period when wheel speed oscillations are detected.
ABS
18. The control system according to claim 17 including means for varying the spacing between successive dump pulses.
19. The control system according to claim 14 wherein said control means includes means for generating a no slip signal when the difference between said speed ramp signal and said wheel speed signal is less than said predetermined slip threshold.
20. The control system according to claim 19 wherein said control means includes means responsive to said no slip signal for generating an apply signal to selectively open said isolation valve to increase pressure to the selected wheel brake.
21. The control system according to claim 20 wherein said apply signal includes a series of apply pulses each having a width representing the time the isolation valve means remains open.
22. The control system according to claim 21 including means for varying the width of said apply pulses.
23. The control system according to claim 22 including means for varying the spacing between successive apply pulses.
24. The control system according to claim 14 wherein said control means includes means for increasing said slip threshold for a predetermined time period when wheel speed oscillations are detected.
25. The control system according to claim 1 wherein said isolation valve means includes an inlet coupled to the supply means and an outlet coupled to the selected wheel brake, said control means including means for monitoring the differential pressure across said isolation valve means and for generating a pressure differential signal when said isolation valve means is closed and the pressure at said outlet is greater than the pressure at said inlet, said control means responsive to said pressure differential signal for opening said isolation valve means.
mohan
عضو جدید
ABS
ABS
26. In a wheeled vehicle having means for supplying pressurized brake fluid to actuate the associated wheel brakes of the vehicle, a brake control system for controlling the application of pressurized brake fluid to at least one selected wheel brake to control the braking of the associated wheel, said control system comprising:
27. The control system according to claim 26 wherein said vehicle includes front and rear wheel brakes and said control system controls the application of pressurized brake fluid only to said rear wheel brakes.
28. The control system according to claim 26 wherein said associated wheel is a driven wheel of the vehicle and said additional pressure is supplied at a level which prevents any rotation of said associated wheel after the vehicle has come to a complete stop.
29. In a wheeled vehicle having means for supplying pressurized brake fluid to actuate the associated wheel brakes of the vehicle, a brake control system for controlling the application of pressurized brake fluid to at least one selected wheel brake to control the braking of the associated wheel, said control system comprising:
ABS
26. In a wheeled vehicle having means for supplying pressurized brake fluid to actuate the associated wheel brakes of the vehicle, a brake control system for controlling the application of pressurized brake fluid to at least one selected wheel brake to control the braking of the associated wheel, said control system comprising:
valve means connected between the supply means and the selected wheel brake;
control means connected to operate said valve means for selectively controlling the application of pressure to the associated wheel brake to prevent lock-up of the associated wheel;
said control means including means for generating an end-of-stop speed ramp representing the speed of the vehicle as the vehicle is decelerated at a predetermined deceleration rate and for automatically operating said valve means to apply and maintain additional pressure to the associated wheel brake when the level of said end-of-stop speed ramp falls below a predetermined speed.
control means connected to operate said valve means for selectively controlling the application of pressure to the associated wheel brake to prevent lock-up of the associated wheel;
said control means including means for generating an end-of-stop speed ramp representing the speed of the vehicle as the vehicle is decelerated at a predetermined deceleration rate and for automatically operating said valve means to apply and maintain additional pressure to the associated wheel brake when the level of said end-of-stop speed ramp falls below a predetermined speed.
27. The control system according to claim 26 wherein said vehicle includes front and rear wheel brakes and said control system controls the application of pressurized brake fluid only to said rear wheel brakes.
28. The control system according to claim 26 wherein said associated wheel is a driven wheel of the vehicle and said additional pressure is supplied at a level which prevents any rotation of said associated wheel after the vehicle has come to a complete stop.
29. In a wheeled vehicle having means for supplying pressurized brake fluid to actuate the associated wheel brakes of the vehicle, a brake control system for controlling the application of pressurized brake fluid to at least one selected wheel brake to control the braking of the associated wheel, said control system comprising:
a normally open isolation valve means connected between the supply means and the selected wheel brake;
a normally closed dump valve means connected between the selected wheel brake and a fluid reservoir; and
control means connected to operate said isolation valve means and said dump valve means, said control means including means for detecting an impending wheel lock-up condition of the associated wheel and means for sensing the deceleration of the associated wheel, said control means operable to close said isolation valve means to hold the fluid pressure to the selected wheel brake at a relatively constant first predetermined pressure after said impending wheel lock-up condition of the associated wheel is detected, said control means operable to selectively open said dump valve means for a first dumping cycle after said isolation valve means is closed and the deceleration of the selected wheel exceeds a first predetermined amount of enable fluid to flow into said fluid reservoir to selectively reduce fluid pressure to the selected wheel brake until the deceleration of the associated wheel is less than said first predetermined amount, said control means further operable to selectively reopen said dump valve means for a second renewed dumping cycle to further reduce fluid pressure to the selected wheel brake when the deceleration of the associated wheel is greater than a second predetermined amount less than said first predetermined amount and said impending lock-up condition of the associated wheel has continued for a predetermined time period after said first dumping cycle is terminated.
30. The control system according to claim 29 wherein said vehicle includes front and rear wheel brakes and said control system controls the application of pressurized brake fluid only to said rear wheel brakes.
a normally closed dump valve means connected between the selected wheel brake and a fluid reservoir; and
control means connected to operate said isolation valve means and said dump valve means, said control means including means for detecting an impending wheel lock-up condition of the associated wheel and means for sensing the deceleration of the associated wheel, said control means operable to close said isolation valve means to hold the fluid pressure to the selected wheel brake at a relatively constant first predetermined pressure after said impending wheel lock-up condition of the associated wheel is detected, said control means operable to selectively open said dump valve means for a first dumping cycle after said isolation valve means is closed and the deceleration of the selected wheel exceeds a first predetermined amount of enable fluid to flow into said fluid reservoir to selectively reduce fluid pressure to the selected wheel brake until the deceleration of the associated wheel is less than said first predetermined amount, said control means further operable to selectively reopen said dump valve means for a second renewed dumping cycle to further reduce fluid pressure to the selected wheel brake when the deceleration of the associated wheel is greater than a second predetermined amount less than said first predetermined amount and said impending lock-up condition of the associated wheel has continued for a predetermined time period after said first dumping cycle is terminated.
30. The control system according to claim 29 wherein said vehicle includes front and rear wheel brakes and said control system controls the application of pressurized brake fluid only to said rear wheel brakes.
mohan
عضو جدید
ABS
ABS
31. The control system according to claim 29 wherein said control means includes means for generating a wheel speed signal representing the speed of the associated wheel and means for generating a speed ramp signal representing the speed of the vehicle if decelerated at a predetermined rate, said control means operable to generate a slip signal when the difference between said speed ramp signal and said wheel speed signal exceeds a predetermined slip threshold.
32. The control means according to claim 31 wherein said second renewed dumping cycle is performed only when said slip signal has been generated during said predetermined time period.
33. The control system according to claim 29 wherein said second predetermined amount is 0.0 g.
34. The control system according to claim 33 wherein said first predetermined amount is greater than or equal to 1.0 g.
35. In a wheeled vehicle having means for supplying pressurized brake fluid to actuate the associated wheel brakes of the vehicle, a brake control system for controlling the application of pressurized brake fluid to at least one selected wheel brake to control the braking of the associated wheel, said control system comprising:
36. The control system according to claim 35 wherein said vehicle includes front and rear wheel brakes and said control system controls the application of pressurized brake fluid only to said rear wheel brakes.
37. The control system according to claim 35 wherein said control means includes means for generating a wheel speed signal representing the speed of the associated wheel and means for generating a speed ramp signal representing the speed of the vehicle if decelerated at a predetermined rate, said control means operable to generate a no slip signal when the difference between said speed ramp signal and said wheel speed signal exceeds a predetermined slip threshold.
ABS
31. The control system according to claim 29 wherein said control means includes means for generating a wheel speed signal representing the speed of the associated wheel and means for generating a speed ramp signal representing the speed of the vehicle if decelerated at a predetermined rate, said control means operable to generate a slip signal when the difference between said speed ramp signal and said wheel speed signal exceeds a predetermined slip threshold.
32. The control means according to claim 31 wherein said second renewed dumping cycle is performed only when said slip signal has been generated during said predetermined time period.
33. The control system according to claim 29 wherein said second predetermined amount is 0.0 g.
34. The control system according to claim 33 wherein said first predetermined amount is greater than or equal to 1.0 g.
35. In a wheeled vehicle having means for supplying pressurized brake fluid to actuate the associated wheel brakes of the vehicle, a brake control system for controlling the application of pressurized brake fluid to at least one selected wheel brake to control the braking of the associated wheel, said control system comprising:
a normally open isolation valve means connected between the supply means and the selected wheel brake;
a normally closed dump valve means connected between the selected wheel brake and a fluid reservoir; and
control means connected to operate said isolation valve means and said dump valve means, said control means including means for detecting wheel speed departures of the associated wheel and means for sensing the acceleration of the associated wheel during spin-up portions of said wheel speed departures, said control means operable to close said isolation valve means to hold the fluid pressure to the selected wheel brake at a relatively constant level after a first wheel speed departure of the associated wheel is detected, said control means operable to selectively open said dump valve means after said isolation valve means has been closed to enable fluid to flow into said fluid reservoir to selectively reduce pressure to the selected wheel brake and correct said first wheel speed departure of the associated wheel, said control means further operable to selectively open said isolation valve means to selectively increase pressure to the selected wheel brake to cause a second wheel speed departure after said wheel first wheel speed departure has been corrected and the acceleration of the associated wheel during a spin-up portion of said first wheel speed departure exceeds a predetermined rate.
a normally closed dump valve means connected between the selected wheel brake and a fluid reservoir; and
control means connected to operate said isolation valve means and said dump valve means, said control means including means for detecting wheel speed departures of the associated wheel and means for sensing the acceleration of the associated wheel during spin-up portions of said wheel speed departures, said control means operable to close said isolation valve means to hold the fluid pressure to the selected wheel brake at a relatively constant level after a first wheel speed departure of the associated wheel is detected, said control means operable to selectively open said dump valve means after said isolation valve means has been closed to enable fluid to flow into said fluid reservoir to selectively reduce pressure to the selected wheel brake and correct said first wheel speed departure of the associated wheel, said control means further operable to selectively open said isolation valve means to selectively increase pressure to the selected wheel brake to cause a second wheel speed departure after said wheel first wheel speed departure has been corrected and the acceleration of the associated wheel during a spin-up portion of said first wheel speed departure exceeds a predetermined rate.
36. The control system according to claim 35 wherein said vehicle includes front and rear wheel brakes and said control system controls the application of pressurized brake fluid only to said rear wheel brakes.
37. The control system according to claim 35 wherein said control means includes means for generating a wheel speed signal representing the speed of the associated wheel and means for generating a speed ramp signal representing the speed of the vehicle if decelerated at a predetermined rate, said control means operable to generate a no slip signal when the difference between said speed ramp signal and said wheel speed signal exceeds a predetermined slip threshold.
38. The control system according to claim 37 wherein said control means is operable to cause said second wheel speed departure only if the acceleration of the associated wheel exceeds said predetermined rate for a certain time period when said no slip signal is being generated.
mohan
عضو جدید
ABS
ABS
39. In a wheeled vehicle having means for supplying pressurized brake fluid to actuate the associated wheel brakes of the vehicle, a brake control system for controlling the application of pressurized brake fluid to at least one selected wheel brake to control the braking of the associated wheel, said control system comprising:
40. The control system according to claim 39 wherein said vehicle includes front and rear wheel brakes and said control system controls the application of pressurized brake fluid only to said rear wheel brakes.
41. In a wheeled vehicle having means for supplying pressurized brake fluid to actuate the associated wheel brakes of the vehicle, a brake control system for controlling the application of pressurized brake fluid to at least one selected wheel brake to control the braking of the associated wheel, said control system comprising:
ABS
39. In a wheeled vehicle having means for supplying pressurized brake fluid to actuate the associated wheel brakes of the vehicle, a brake control system for controlling the application of pressurized brake fluid to at least one selected wheel brake to control the braking of the associated wheel, said control system comprising:
a normally open isolation valve means connected between the supply means and the selected wheel brake;
a normally closed dump valve means connected between the selected wheel brake and a fluid reservoir; and
control means connected to operate said isolation valve means and said dump valve means, said control means including means for detecting a wheel lock-up condition of the associated wheel, said control means including means for detecting a wheel lock-up condition of the associated wheel, said control means operable to close said isolation valve means to hold the fluid pressure to the selected wheel brake at a relatively constant level after said wheel lock-up condition of the associated wheel is detected, said control means operable to selectively open said dump valve means during a dump cycle after said wheel lock-up condition has been detected to enable fluid to flow into said fluid reservoir to selectively reduce pressure to the selected wheel brake and correct the lock-up condition of the associated wheel, said control means including means for monitoring the time said dump valve means has been open during said dump cycle, said control means further operable to selectively open said isolation valve means to increase pressure to the selected wheel brake to cause a wheel speed departure of the associated wheel after said dump cycle when the total time said dump valve has been open during said dump cycle exceeds a predetermined amount, said control means further operable to selectively open said dump valve means after said increase in pressure to enable fluid to flow into said fluid reservoir to selectively reduce pressure to the selected wheel brake and correct said wheel speed departure.
a normally closed dump valve means connected between the selected wheel brake and a fluid reservoir; and
control means connected to operate said isolation valve means and said dump valve means, said control means including means for detecting a wheel lock-up condition of the associated wheel, said control means including means for detecting a wheel lock-up condition of the associated wheel, said control means operable to close said isolation valve means to hold the fluid pressure to the selected wheel brake at a relatively constant level after said wheel lock-up condition of the associated wheel is detected, said control means operable to selectively open said dump valve means during a dump cycle after said wheel lock-up condition has been detected to enable fluid to flow into said fluid reservoir to selectively reduce pressure to the selected wheel brake and correct the lock-up condition of the associated wheel, said control means including means for monitoring the time said dump valve means has been open during said dump cycle, said control means further operable to selectively open said isolation valve means to increase pressure to the selected wheel brake to cause a wheel speed departure of the associated wheel after said dump cycle when the total time said dump valve has been open during said dump cycle exceeds a predetermined amount, said control means further operable to selectively open said dump valve means after said increase in pressure to enable fluid to flow into said fluid reservoir to selectively reduce pressure to the selected wheel brake and correct said wheel speed departure.
40. The control system according to claim 39 wherein said vehicle includes front and rear wheel brakes and said control system controls the application of pressurized brake fluid only to said rear wheel brakes.
41. In a wheeled vehicle having means for supplying pressurized brake fluid to actuate the associated wheel brakes of the vehicle, a brake control system for controlling the application of pressurized brake fluid to at least one selected wheel brake to control the braking of the associated wheel, said control system comprising:
a normally open isolation valve means connected between the supply means and the selected wheel brake;
a normally closed dump valve means connected between the selected wheel brake and a fluid reservoir; and
control means connected to operate said isolation valve means and said dump valve means, said control means including means for detecting wheel speed departures of the associated wheel and means for sensing the deceleration of the associated wheel, said control means operable to close said isolation valve means to hold the fluid pressure to the selected wheel brake at a relatively constant level after a first wheel speed departure of the associated wheel is detected, said control means operable to selectively open said dump valve means after said isolation valve means has been closed to enable fluid to flow into said fluid reservoir to selectively reduce pressure to the selected wheel brake to a first predetermined pressure and correct said first wheel speed departure, said control means further operable to selectively open said isolation valve means to increase pressure to the selected wheel brake when the deceleration of the vehicle increases by a predetermined amount to cause a second wheel speed departure after said first wheel speed departure has been corrected, said control means operable to selectively open said dump valve means after said second wheel speed departure has been detected to selectively reduce pressure to the selected wheel brake to a second predetermined pressure greater than said first predetermined pressure.
a normally closed dump valve means connected between the selected wheel brake and a fluid reservoir; and
control means connected to operate said isolation valve means and said dump valve means, said control means including means for detecting wheel speed departures of the associated wheel and means for sensing the deceleration of the associated wheel, said control means operable to close said isolation valve means to hold the fluid pressure to the selected wheel brake at a relatively constant level after a first wheel speed departure of the associated wheel is detected, said control means operable to selectively open said dump valve means after said isolation valve means has been closed to enable fluid to flow into said fluid reservoir to selectively reduce pressure to the selected wheel brake to a first predetermined pressure and correct said first wheel speed departure, said control means further operable to selectively open said isolation valve means to increase pressure to the selected wheel brake when the deceleration of the vehicle increases by a predetermined amount to cause a second wheel speed departure after said first wheel speed departure has been corrected, said control means operable to selectively open said dump valve means after said second wheel speed departure has been detected to selectively reduce pressure to the selected wheel brake to a second predetermined pressure greater than said first predetermined pressure.
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