Zahnradfabrik Friedrichshafen, Ag.

Zf Lenksysteme Gmbh

Winfried De Maight

Jens-Uwe Hafermalz

Peter Ertle

Karl-Heinz Urban

Erich Eichele

Ronald Schutze

Rotary disk valve for power steering systems of motor vehicles

A surge chamber hydraulically connected between the outlet of a radial piston pump and the internal chambers of the piston plungers, cooperates with a second fluid storing surge chamber in the pump housing through connecting passages to dampen vibrations produced by pump flow fluctuations to reduce non-uniform flow and the noise level during pump operation under a wide range of pressures and speeds.

Radial piston pump

A pressure reducing valve between a high pressure source and a steering control valve lowers the operating pressure of fluid conducted to a piston servomotor from the source by the steering control valve. A constant pressure differential across the steering control valve is maintained by the pressure reducing valve through a feedback pressure balancing arrangement to appropriately vary regulation of the feed pressure to the steering control valve.

Auxiliary power steering

A throttle valve biased to open position by a spring is interposed in the return line of a steering control valve in a booster steering system. The essential feature of the invention is that one face of the valve is exposed to feed pressure acting against a valve opening bias spring to produce the throttling effect in accordance with construction and design of the valve and the system in which it may be used. The invention is particularly intended for use with booster steering control valves in neutral or steering position and ensures throttling of return flow to the system sump only during a steering operation. The invention is usable in steering mechanisms such as shown in the patent to Wagner et al., U.S. Pat. No. 3,964,371.

Auxiliary power steering for motor vehicles

A pump having a limited maximum output pressure is alternately connected to a steering control valve and a pressure storage reservoir charged by the pump under control of a signal pressure operated valve to supply fluid under the maximum pump pressure to a steering servomotor only under high loading conditions. The storage pressure is limited to a value less than the maximum pump pressure to influence operation of the signal pressure operated valve and operate the servomotor under low load conditions.

Growing community of inventors

Mutlangen, Germany

Winfried De Maight