Power steering with hydraulic power assistance

US6230839A · kind A · utility

Assignee

• ZF FRIEDRICHSHAFEN AG · DE

Inventors

• Dieter Elser · Oberkochen, DE
• Andreas Braun · San Diego, US
• Wolfgang Zeitz · Deggendorf, DE

Key dates

• Filing date: Oct 25, 1999
• Grant date: May 15, 2001
• Expiry date: Oct 25, 2019

Classification

• Technology area (CPC B): Performing Operations; Transporting
• CPC primary: B62D5/06
• WIPO field: Transport
• WIPO sector: Mechanical engineering

Abstract

In connection with a servo-assisted steering system with hydraulic servo-assistance for motor vehicles, a steering shaft (15), which is provided with a steering wheel (16), is connected via a torsion spring (14) with an input member of a steering gear (2). An output member of the steering gear (2) is connected with the wheels (11) of the vehicle which are to be steered. In case of a relative rotation of the steering shaft (15) in respect to the input member, two work chambers (12, 13) of a servo motor of a force amplification device can be pressurized by a servo pump via a steering valve with a pressure medium. Two sensors (23, 24) for detecting a rotation angle and/or a torque are arranged on the steering shaft (15), or respectively on the output member of the steering gear (2). After the steering wheel (16) is released following a steering process, the wheels to be steered (11) and the steering gear (2) can be returned with hydraulic assistance. The amount and the direction of the hydraulic servo-assistance, as well as the return of the wheels (11) to be steered, are controlled by means of a common electronically-controlled electromagnetic (18) valve.