Method of operating an electrically controllable brake system and brake system which is operated according to the method
A method for operating an electrically controllable brake system for a motor vehicle having at least one electrically actuated valve arrangement for setting a pressure difference between a second brake pressure and a first brake pressure, wherein in a first time interval a predetermined first pressure difference is set and an associated first power consumption value of the pump is identified; in a second time interval a predetermined second pressure difference is set and an associated second power consumption value of the pump is identified; a correction value is obtained from the first power consumption value and the second power consumption value; the correction value is taken into account for setting a set-point value for the pressure difference.
1. A method for operating an electrically controllable brake system for a motor vehicle with a master cylinder for generating a first brake pressure, with an electrically driven pump for generating a second brake pressure, and with at least one electrically driven valve arrangement for setting a pressure difference between the second brake pressure and the first brake pressure, wherein:
in a first time-interval a predetermined first pressure difference is set and an associated first power consumption of the pump is ascertained,
in a second time-interval a predetermined second pressure difference is set and an associated second power consumption of the pump is ascertained,
a correction value is ascertained from the first power consumption and the second power consumption, and
the correction value taken into consideration for the purpose of setting a set-point value for the pressure difference.
2. A method for operating an electrically controllable brake system for a motor vehicle with wheel cylinders in which a first brake pressure is generated, with an electrically driven pump for generating a second brake pressure, and with at least one electrically driven valve arrangement for setting a pressure difference between the second brake pressure and the first brake pressure, wherein:
in a first time-interval a predetermined first pressure difference is set and an associated first power consumption of the pump is ascertained,
in a second time-interval a predetermined second pressure difference is set and an associated second power consumption of the pump is ascertained,
a correction value is ascertained from the first power consumption and the second power consumption, and
the correction value is taken into consideration for the purpose of setting a set-point value for the pressure difference.
3. The method according to claim 1 , wherein a termination of the method occurs if a braking operation initiated by a driver of the vehicle and/or an automatic braking operation occurs.
4. The method according to claim 1 , wherein a termination of the method occurs if a braking operation is imminent.
5. The method according to claim 1 , wherein for the purpose of ascertaining the correction value a ratio is derived from the first power consumption and the second power consumption.
6. The method according to claim 1 , wherein for the purpose of ascertaining the correction value a difference is derived from the first power consumption and the second power consumption.
7. The method according to claim 5 , wherein an existence of a system error is inferred if a value of the correction value is ascertained that does not lie within a predetermined range.
8. The method according to claim 1 , wherein the first pressure difference or the second pressure difference is set to a value of an order of magnitude zero.
9. The method according to claim 1 , wherein the first time-interval and the second time-interval are of a same duration.
10. The method according to claim 1 , wherein the first time-interval and the second time-interval are of different duration.
11. The method according to claim 1 , wherein the pump is driven in such a way that in the first time-interval and in the second time-interval a rate of delivery of a same magnitude is achieved.
12. The method according to claim 1 , wherein the pump is driven in such a way that in the first time-interval and in the second time-interval rates of delivery of differing magnitude are achieved.
13. The method according to claim 1 , wherein the first and second power consumptions are ascertained if in the respective first and second time-intervals the rate of delivery of the pump is constant.
14. The method according to claim 1 , wherein the correction value is compared with a reference value, and the set-point value for the pressure difference is set in such a way that the correction value approximates to the reference value.
15. The method according to claim 14 , wherein the comparison of the correction value with the reference value and the setting of the set-point value for the pressure difference are repeated until such time as the correction value has approximated to the reference value within a predetermined deviation.
16. The method according to claim 14 , wherein the existence of a system error is inferred if the approximation of the correction value to the reference value has not occurred within a predetermined period of time and/or after a predetermined number of repetitions.
17. The method according to claim 14 , wherein the reference value is predetermined in a manner depending on the first and/or second pressure difference.
18. An electrically controllable brake system that is operated in accordance with a method according to claim 1 .
19. The method according to claim 6 , wherein an existence of a system error is inferred if a value of the correction value is ascertained that does not lie within a predetermined range.
20. The method according to claim 2 , wherein a termination of the method occurs if a braking operation initiated by a driver of the vehicle and/or an automatic braking operation occurs.
21. The method according to claim 2 , wherein a termination of the method occurs if a braking operation is imminent.
22. The method according to claim 2 , wherein for the purpose of ascertaining the correction value a ratio is derived from the first power consumption and the second power consumption.
23. The method according to claim 2 , wherein for the purpose of ascertaining the correction value a difference is derived from the first power consumption and the second power consumption.
24. The method according to claim 22 , wherein an existence of a system error is inferred if a value of the correction value is ascertained that does not lie within a predetermined range.
25. The method according to claim 2 , wherein the first pressure difference or the second pressure difference is set to a value of an order of magnitude zero.
26. The method according to claim 2 , wherein the first time-interval and the second time-interval are of a same duration.
27. The method according to claim 2 , wherein the first time-interval and the second time-interval are of different duration.
28. The method according to claim 2 , wherein the pump is driven in such a way that in the first time-interval and in the second time-interval a rate of delivery of a same magnitude is achieved.
29. The method according to claim 2 , wherein the pump is driven in such a way that in the first time-interval and in the second time-interval rates of delivery of differing magnitude are achieved.
30. The method according to claim 2 , wherein the first and second power consumptions are ascertained if in the respective first and second time-intervals the rate of delivery of the pump is constant.
31. The method according to claim 2 , wherein the correction value is compared with a reference value, and the set-point value for the pressure difference is set in such a way that the correction value approximates to the reference value.
32. The method according to claim 31 , wherein the comparison of the correction value with the reference value and the setting of the set-point value for the pressure difference are repeated until such time as the correction value has approximated to the reference value within a predetermined deviation.
33. The method according to claim 31 , wherein the existence of a system error is inferred if the approximation of the correction value to the reference value has not occurred within a predetermined period of time and/or after a predetermined number of repetitions.
34. The method according to claim 31 , wherein the reference value is predetermined in a manner depending on the first and/or second pressure difference.
35. An electrically controllable brake system that is operated in accordance with a method according to claim 2 .
36. The method according to claim 23 , wherein an existence of a system error is inferred if a value of the correction value is ascertained that does not lie within a predetermined range.