METHOD AND DEVICE FOR DETERMINING AND BALANCING THE WORKING POINT OF VALVES IN A HYDRAULIC SYSTEM

• US 20110153177A1
• Filed: 06/30/2009
• Published: 06/23/2011
• Est. Priority Date: 07/18/2008
• Status: Abandoned Application

• Current Assignee: Robert Bosch GmbH
• Original Assignee: Robert Bosch GmbH
• Inventors: Mahlenbrey, Ulrich
• Application Number:
  US13/054,365
• Publication Number:
  US 20110153177A1
• Time in Patent Office: Days
• US Class Current: 701/70
• CPC Class Codes: B60T 8/36 including a pilot valve responding to an electromagnetic force
• CPC Class Codes: B60T 8/3655 Continuously controlled electromagnetic valves
• CPC Class Codes: B60T 8/4872 pump-back systems
• CPC Class Codes: Y10T 137/0379 By fluid pressure
• CPC Class Codes: Y10T 137/7758 Pilot or servo controlled

Abstract

A method and an apparatus for ascertaining the working point of switchover valves of a hydraulic system of a vehicle, in particular of a hydraulic brake circuit, are described in which the hydraulic system contains at least a pressure generating arrangement, a high-pressure switching valve, a switchover valve, and an admission pressure sensor, an admission pressure that is higher than the target pressure of the switchover valve being established, the switchover valve being energized with a target current corresponding to the target pressure, admission pressure being reduced until the switchover valve closes, with the switchover valve closed, a nominal admission pressure being established as an admission pressure, after the switchover valve opens, a pressure difference Δp between admission pressure and a circuit pressure being sensed, and on the basis of the pressure difference Δp, the working point being ascertained.

Claims

1-10. -10. (canceled)

11. A method for determining a working point of a switchover valve of a hydraulic system, which includes a brake circuit, of a vehicle, the method comprising:

establishing an admission pressure that is higher than a target pressure of the switchover valve of the hydraulic system, which includes at least a pressure generating arrangement, a high-pressure switching valve, the switchover valve, and an admission pressure sensor;

energizing the switchover valve with a target current I corresponding to the target pressure;

reducing the admission pressure until the switchover valve closes;

establishing, with the switchover valve closed, a nominal admission pressure;

after the switchover valve opens, sensing a pressure difference Δ

p between the nominal admission pressure and a circuit pressure; and

determining, based on the pressure difference Δ

p, the working point.

12. The method of claim 11, wherein the admission pressure to be established instead of the nominal admission pressure is determined on the basis of the pressure difference Δ

p.

13. The method of claim 12, wherein when the pressure difference Δ

p exceeds a previously set threshold value, the admission pressure is increased.

14. The method of claim 12, wherein when the pressure difference Δ

p falls below a previously set threshold value, the admission pressure is decreased.

15. The method of claim 11, wherein the target pressure is determined in accordance with an I-dp-q characteristics diagram.

16. The method of claim 11, wherein the reduction in the admission pressure occurs with a constant gradient.

17. The method of claim 11, wherein a nominal characteristics diagram is adapted by the determined admission pressure.

19. The apparatus of claim 11, wherein the admission pressure to be established instead of the nominal admission pressure is determined on the basis of the pressure difference Δ

p.

18. An apparatus for determining the working point of a switchover valve of a hydraulic system, including a brake circuit, of a vehicle, comprising:

a pressure generating unit that establishes an admission pressure;

an energizing unit that energizes the switchover valve of the hydraulic system, which includes at least a pressure generating arrangement, a high-pressure switching valve, the switchover valve, and an admission pressure sensor;

a pressure reduction unit that reduces the admission pressure;

a measuring unit that senses a pressure difference Δ

p between a nominal admission pressure1 and a circuit pressure; and

a calculation unit that determines the working point based on the pressure difference Δ

p.

20. A computer readable medium having a computer program, which is executable by a processor, comprising:

a program code arrangement having program code for determining a working point of a switchover valve of a hydraulic system, which includes a brake circuit, of a vehicle, by performing the following;

establishing an admission pressure that is higher than a target pressure of the switchover valve of the hydraulic system, which includes at least a pressure generating arrangement, a high-pressure switching valve, the switchover valve, and an admission pressure sensor;

energizing the switchover valve with a target current I corresponding to the target pressure;

reducing the admission pressure until the switchover valve closes;

establishing, with the switchover valve closed, a nominal admission pressure;

after the switchover valve opens, sensing a pressure difference Δ

p between the nominal admission pressure and a circuit pressure; and

determining, based on the pressure difference Δ

p, the working point.