Detection and identification of pressure-sensor faults in electro-hydraulic (EHB) braking systems

• US 6,634,221 B2
• Filed: 03/26/2002
• Issued: 10/21/2003
• Est. Priority Date: 11/27/1998
• Status: Expired due to Fees

• Current Assignee: Lucas Industries Limited (Zeppelin - Stiftung der Stadt Friedrichshafen)
• Original Assignee: Lucas Industries Limited (Zeppelin - Stiftung der Stadt Friedrichshafen)
• Inventors: Phillips, Mark Ian, Howell, Mark Leighton, Harris, Alan Leslie
• Primary Examiner(s): Oen, William
• Application Number:
  US10/106,874
• Publication Number:
  US 20020166369A1
• Time in Patent Office: 574 Days
• Field of Search: 731/21, 737/14, 188/1.11, 188/72.1, 188/158, 303/111, 303/118, 303/119, 303/122.12, 303/122.14, 303/113.4, 303/115.4, 303/84.2
• US Class Current: 73/121
• CPC Class Codes: B60T 13/686 in hydraulic systems or parts thereof
• CPC Class Codes: B60T 17/221 Procedure or apparatus for checking or keeping in a correct functioning condition of brake systems hydraulic pressure systems in general F15B19/00, F15B21/04; testing structures or apparatus G01M
• CPC Class Codes: B60T 8/4072 Systems in which a driver input signal is used as a control signal for the additional fluid circuit which is normally used for braking
• CPC Class Codes: B60T 8/4086 the stroke simulating device being connected to, or integrated in the driver input device
• CPC Class Codes: B60T 8/88 with failure responsive means, i.e. means for detecting and indicating faulty operation of the speed responsive control means

Abstract

A method of detection and identification of pressure sensor faults in an electro-hydraulic braking system of the type comprising a brake pedal, respective braking devices connected to the vehicle wheels and which communicate with electronically controlled proportional control valves in order to apply hydraulic fluid under pressure to the braking devices, respective pressure sensors for measuring the hydraulic pressures at the individual braking devices, a hydraulic pump driven by an electric motor, a high pressure hydraulic pressure accumulator fed by the pump for the provision of hydraulic fluid under pressure which can be passed to the braking devices via the proportional control valves in order to apply hydraulic fluid under pressure to the braking devices in proportion to the driver'"'"'s braking demand as sensed at the brake pedal, and a supply pressure sensor for monitoring the hydraulic pressure supplied to the electronically controlled proportional control valves. In accordance with the method, three or more of the pressure sensors are arranged to be subjected to the same pressure and their readings measured and compared whereby to identify a sensor whose reading does not correspond to that of the others.

Claims

1. A method of detection and identification of pressure sensor faults in a braking system of the type comprising a brake pedal, respective braking devices connected to the vehicle wheels and which communicate with electronically controlled valves in order to apply hydraulic fluid under pressure to the braking devices, respective pressure sensors for measuring the hydraulic pressures at the individual braking devices, a hydraulic pump driven by an electric motor, a high pressure hydraulic pressure accumulator fed by said pump for the provision of hydraulic fluid under pressure which can be passed to the braking devices via the electronically controlled valves in order to apply hydraulic fluid under pressure to the braking devices as a function of the driver'"'"'s braking demand as sensed at the brake pedal, and a supply pressure sensor for monitoring the hydraulic pressure supplied to the electronically controlled proportional control valves, in which method at least three of said pressure sensors are subjected to the same pressure and their readings are measured and compared to identify a sensor whose reading does not correspond to that of the others.

2. A method according to claim 1, wherein in the case of a vehicle having at least four or more wheels, all pressure sensors associated with the braked wheels, and the supply pressure sensor, are connected together, with all of the proportional control valves either one of opened fully and substantially fully.

3. A method according to claim 1, wherein with the vehicle stationary and an accumulator isolating valve open, a comparison of the readings from all sensors is made under pressure.

4. A method according to claim 2, wherein with the vehicle stationary and an accumulator isolating valve open, a comparison of the readings from all sensors is made under pressure.

5. A method according to claim 1, wherein the comparison of the sensor readings is made with the vehicle stationary and an accumulator isolating valve closed.

6. A method according to claim 2, wherein the comparison of the readings from all sensors is made under pressure.

7. A method according to claim 1, wherein a comparison is made of the brake pressures as measured by the pressure sensors, both across the axles and between front and rear axles.

17. A method according to claim 1, wherein in the case of a vehicle having at least four or more wheels, all pressure sensors associated with the braked wheels, and the supply pressure sensor, are connected together, with all of the proportional control valves either one of opened fully and substantially fully.

18. A method according to claim 1, wherein a comparison is made of the brake pressures as measured by the pressure sensors, both across the axles and between front and rear axles.

8. A braking system comprising a brake pedal, respective braking devices connected to the vehicle wheels and which communicate with electronically controlled valves in order to apply hydraulic fluid under pressure to the braking devices, respective pressure sensors for measuring the hydraulic pressures at the individual braking devices, a hydraulic pump driven by an electric motor, a high pressure hydraulic pressure accumulator fed by said pump for the provision of hydraulic fluid under pressure which can be passed to the braking devices via the electronically controlled valves in order to apply hydraulic fluid under pressure to the braking devices as a function of the driver'"'"'s braking demand as sensed at the brake pedal, a supply pressure sensor for monitoring the hydraulic pressure supplied to the electronically controlled valves, and sensor control and comparison means for subjecting at least three of said pressure sensors to the same pressure and measuring and comparing their readings so as to identify a sensor whose reading does not correspond to that of the others.

9. A system according to claim 8, wherein in the case of a vehicle having at least four wheels, the control means can connect together all pressure sensors associated with the brake wheels, and the supply pressure sensor, with all of the proportional control valves either one of opened fully and opened substantially fully.

10. A system according to claim 8, wherein, with the vehicle stationary and an accumulator isolating valve open, the control means is arranged to effect a comparison of the readings from all sensors under pressure.

11. A system according to claim 9, wherein with the vehicle stationary and an accumulator isolating valve open, the control means is arranged to effect a comparison of the readings from all sensors under pressure.

12. A system according to claim 8, wherein said control means is arranged to effect the comparison of the sensor readings with the vehicle stationary and an accumulator isolating valve closed.

13. A system according to claim 9, wherein said control means is arranged to effect the comparison of the sensor readings with the vehicle stationary and an accumulator isolating valve closed.

14. A system according to claim 8, wherein the control means is arranged to effect a comparison of the brake pressures as measured by the pressure sensors, both across the axles and between front and rear axles.

15. A system according to claim 8, wherein said control means comprises a system ECU.

16. A method of detection and identification of pressure sensor faults in an electro-hydraulic braking system of the type comprising a brake pedal, respective braking devices connected to the vehicle wheels and which communicate with electronically controlled proportional control valves in order to apply hydraulic fluid under pressure to the braking devices, respective pressure sensors for measuring the hydraulic pressures at the individual braking devices, a hydraulic pump driven by an electric motor, a high pressure hydraulic pressure accumulator fed by said pump via an isolating valve for the provision of hydraulic fluid under pressure which can be passed to the braking devices via the proportional control valves in order to apply hydraulic fluid under pressure to the braking devices in proportion to the driver'"'"'s braking demand as sensed at the brake pedal, and a supply pressure sensor for monitoring the hydraulic pressure supplied to the electronically controlled proportional control valves, in which method, with the accumulator isolating valve closed and with the vehicle having been brought to a stationary condition by operating the brake pedal and before the brake pedal is released, at least three of said pressure sensors are arranged to be subjected commonly to the pressure then existing within the braking system downstream of the accumulator isolating valve and their readings measured and compared whereby to identify a sensor whose reading does not correspond to that of the others.

19. An electro-hydraulic braking system comprising a brake pedal, respective braking devices connected to the vehicle wheels and which communicate with electronically controlled proportional control valves in order to apply hydraulic fluid under pressure to the braking devices, respective pressure sensors for measuring the hydraulic pressures at the individual braking devices, a hydraulic pump driven by an electric motor, a high pressure hydraulic pressure accumulator fed by said pump for the provision of hydraulic fluid under pressure which can be passed to the braking devices via the proportional control valves in order to apply hydraulic fluid under pressure to the braking devices in proportion to the driver'"'"'s braking demand as sensed at the brake pedal, a supply pressure sensor for monitoring the hydraulic pressure supplied to the electronically controlled proportional control valves, and control means for identifying a sensor whose reading does not correspond to that of the others, which control means closes the accumulator isolating valve and, when the vehicle has been brought to a stationary condition by operating the brake pedal and before the brake pedal has been released, is arranged to measure the readings from at least three of said pressure sensors subjected to the common pressure then existing within the braking system downstream of the accumulator isolating valve.

20. A system according to claim 19, wherein in the case of a vehicle having at least four or more wheels, the control means can connect together all pressure sensors associated with the brake wheels, and the supply pressure sensor, with all of the proportional control valves either one of opened fully and opened substantially fully.