METHOD AND DEVICE FOR THE CALIBRATION OR DIAGNOSIS OF A MOTOR VEHICLE BRAKE SYSTEM HAVING A CYCLICALLY OPERATED PUMP

• US 20110184606A1
• Filed: 10/22/2008
• Published: 07/28/2011
• Est. Priority Date: 10/24/2007
• Status: Active Grant

• Current Assignee: Continental Teves AG & Company HG (Continental AG)
• Original Assignee: Continental Teves AG & Co. OHG (Continental AG)
• Inventors: Scheller, Tobias, Robert, Tom, Attallah, Faouzi
• Granted Patent: US 8,301,331 B2
• Time in Patent Office: Days
• US Class Current: 701/29
• CPC Class Codes: B60T 8/404 Control of the pump unit
• CPC Class Codes: B60T 8/4059 involving the rate of delivery

Abstract

A method for the calibration or diagnosis of a motor vehicle brake system having a cyclically operated pump. At least one parameter (U_RP^Off), representing the electromotor force of the reference pump, is repeatedly ascertained during operation of a reference pump under defined guidelines. A statistical characteristic variable (<U_RP^Off>) is derived from the values of parameter (U_RP^Off) ascertained for the reference pump. Parameter (U_BP^Off) is ascertained under a corresponding guideline during operation of an operating pump. Corresponding statistical characteristic variable (<U_BP^Off>) is derived from the values of parameter (U_BP^Off) ascertained for the operating pump. At least one ratio number is calculated as a measure of the deviation of the operating behavior of the operating pump from the operating behavior of the reference pump from the characteristic variable (<U_RP^Off>) calculated for the reference pump and the characteristic variable (<U_BP^Off>) calculated for the operating pump.

Claims

1-14. -14. (canceled)

15. A method for the calibration or diagnosis of a motor vehicle brake system having a pump operating in a pulsed fashion, comprising:

repeatedly determining, during operation of a reference pump under defined stipulations, at least one parameter (U_RP^Off) representing the electromotive force of the reference pump;

deriving a statistical characteristic variable (U_RP^Off) from the values of the parameter (U_RP^Off) that are determined for the reference pump;

determining, during operation of an operating pump, a parameter (U_BP^Off) representing the electromotive force of the operating pump under corresponding stipulations;

deriving a corresponding statistical characteristic variable (U_BP^Off) from the values of the parameter (U_BP^Off) that are determined for the operating pump; and

calculating at least one ratio as a measure of the deviation of the operating behavior of the operating pump from the operating behavior of the reference pump from the characteristic variable (U_RP^Off) calculated for the reference pump and the characteristic variable (U_BP^Off) calculated for the operating pump.

16. The method of claim 15, wherein with the aid of said at least one ratio, a characteristic curve (p_v(U_BP^Off)) of the operating pump is adapted to a characteristic curve (p_v(U_RP^Off)) correspondingly prescribed for the reference pump.

17. The method as claimed in claim 16, wherein the characteristic curves (p_v(U_RP^Off), p_v(U_BP^Off)) represent a functional relationship between the at least one parameter (U^Off) and a brake line pressure (p_v) of the motor vehicle brake system, a pumping rate of the pump and/or the temperature of the pump.

18. The method as claimed in claim 15, wherein if said at least one ratio lies outside a prescribed tolerance range, the operating pump is identified as defective.

19. The method as claimed in claim 15, wherein the statistical characteristic variables (U_RP^Off,U_BP^Off) are determined from a histogram (HU_RP^Off,HU_BP^Off) of a parameter (U^Off) created for the reference pump and for the operating pump, respectively.

20. The method as claimed in claim 19, wherein the statistical characteristic variables (U_RP^Off,U_BP^Off) are determined from one or more of the following parameters:

a last voltage value (U^OnL) of a pulse of an operating clock of the respective pump,

a first voltage value (U^OnF) of the pulse,

a first voltage value (U^Off) of an interpulse period following the pulse,

a differential value (U^Fall) between the last voltage value (U^OnL) of the pulse and the first voltage value (U^Off) of the interpulse period,

a lowest voltage value (U^min) within the interpulse period,

a sum (U^Sum) of the voltage values within the interpulse period,

a mean voltage value (U_Aver) of the voltage values within the interpulse period,

a slope (U^Slope) of the voltage fall within the interpulse period,

a difference (U^Rise) between the lowest voltage value (U^Min) of the interpulse period and the first voltage value (U^OnF) of the following pulse, and

a time (t^Fall) up to the fall of the voltage to zero.

21. The method as claimed in claim 15, wherein within the scope of the stipulations, an operating clock of the respective pump is prescribed during the measurement.

22. The method as claimed in claim 15, wherein the at least one parameter (U^Off) is normalized to a further parameter.

23. The method as claimed in claim 15, wherein use is made, as a statistical characteristic variable, of the mean value (U_RP^Off,U_BP^Off) of the values of the parameter (U^Off) that are acquired for the reference pump and for the operating pump, respectively.

24. The method as claimed in claim 15, wherein a mathematical distribution function (G) is adapted to each histogram (HU_RP^Off,HU_BP^Off).

25. The method as claimed in claim 24, wherein the mathematical distribution function (G) is a Gaussian distribution function.

26. The method as claimed in claim 15, wherein a plurality of ratios are calculated in order to form a total ratio.

27. The method as claimed in claim 26, wherein the total ratio is a weighted sum of the ratios.

28. A device for the calibration of a motor vehicle brake system having a pump operated in a pulsed fashion and further having a control unit configured to carry out the method as claimed in claim 15.