Power steering system with hydraulic power assistance

• US 20050051378A1
• Filed: 08/26/2004
• Published: 03/10/2005
• Est. Priority Date: 03/15/2002
• Status: Active Grant

• Current Assignee: Robert Bosch Automotive Steering GmbH (Robert Bosch GmbH)
• Original Assignee: ZF Lenksysteme GmbH (Robert Bosch GmbH)
• Inventors: Merz, Johann
• Granted Patent: US 7,055,644 B2
• Time in Patent Office: Days
• US Class Current: 180/441
• CPC Class Codes: B62D 5/062 Details, component parts
• CPC Class Codes: B62D 5/065 characterised by specially adapted means for varying pressurised fluid supply based on need, e.g. on-demand, variable assist

Abstract

A hydraulic power-assisted steering system, in particular for motor vehicles, has a hydraulic pump for generating hydraulic pressure for assisting the steering and an electromagnetic valve, in addition to a motor for driving the hydraulic pump. The hydraulic pump can be decoupled from the motor by means of a coupling.

Claims

1. A power steering system with hydraulic power assistance, comprising a pressure medium pump for producing a hydraulic pressure for power assistance, a solenoid valve for controlling the pressure medium flow to working spaces, the solenoid valve being arranged in the pressure medium pump, a power source for driving the pressure medium pump, and a clutch to separate the pressure medium pump from the power source.

2. The power steering system as claimed in claim 1, wherein the clutch is an electromagnetic clutch.

3. The power steering system as claimed in claim 1, wherein the clutch is integrated in the pressure medium pump.

4. The power steering system as claimed in claim 1, wherein the clutch is arranged on the pressure medium pump.

5. The power steering system as claimed in claim 1, wherein the power source is an internal combustion engine.

6. The power steering system as claimed in claim 1, wherein the solenoid valve is a valve with a closed hydraulic center.

7. The power steering system as claimed in claim 1, wherein the solenoid valve is a proportional solenoid valve.

8. The power steering system as claimed in claim 1, comprising a computing unit and at least one steering moment sensor, the computing unit controlling the solenoid valve, the computing unit processing signals from said at least one steering moment sensor.

9. The power steering system as claimed in claim 8, wherein the computing unit monitors booster oil pressure to working spaces.

10. The power steering system as claimed in claim 8, wherein the computing unit processes additional parameters selected from the group consisting of driving speed, steering speed, acceleration, yaw velocity, loading state, engine speed, ESP signals, ABS signals, steering angle and driver-specific settings.

11. The power steering system as claimed in claim 9, wherein the additional parameters can be transmitted by a CAN bus.

12. The power steering system as claimed in claim 1, wherein a hydraulic accumulator is integrated into the pressure medium pump.

13. The power steering system as claimed in claim 1, wherein the power of the pressure medium pump is regulated as a function of the power necessary for hydraulic assistance.

14. The power steering system as claimed in claim 12, wherein the clutch is controlled using the pressure values in the hydraulic accumulator.

15. The power steering system as claimed in claim 14, wherein the clutch is controlled using upper and a lower pressure values in the hydraulic accumulator.

16. The power steering system as claimed in claim 14, wherein the clutch regulates the pressure in the hydraulic accumulator.

17. The power steering system as claimed in claim 14, wherein the clutch regulates the pressure in the pressure medium pump.

18. A power steering system as in claim 1, wherein the power steering system is utilized with motor vehicles.