Zf Lenksysteme Gmbh

Zf Friedrichshafen Ag

Wolfgang Zeitz

Dieter Elser

Andreas Braun

Manfred Heintschel

A hydropneumatic suspension system for motor vehicles, having at least one hydropneumatic support aggregate and one automatic level control system cooperating with the aggregate, the automatic level control system, as a function of the lift position of the wheels, sending hydraulic fluid from the hydropneumatic pressure reservoir into the hydropneumatic suspension cylinders, or drawing hydraulic fluid from the hydropneumatic suspension cylinders into the pressure reservoirs, and the functions of suspension, roll stabilization, and automatic level control being able to be performed using the hydropneumatic suspension cylinders.

Hydropneumatic suspension system

In a power steering system having hydraulic power support for motor vehicles, a steering gear shaft having a steering wheel is connected to an input element of a steering gear. An output element of the steering gear is connected to wheels of the vehicle to be steered. Two working chambers of a servo motor of a power boosting system can be supplied with a hydraulic medium from a servo pump through a steering valve in accordance with a torque applied in the area of the steering gear shaft input element. Two sensors for detecting an angle of rotation and a torque are provided on the steering gear shaft and on the output element of the steering gear accordingly. After the steering wheel has been released after a steering operation, the wheels to be steered and the steering gear can be returned with hydraulic support. Both the intensity and direction of the hydraulic power support as well as the returning of the wheels to be steered are controlled by a common, electronically controlled electromagnetic valve. In addition, only one steering force sensor and/or torque sensor is provided for detecting the steering force. With this sensor, the control distances can be reduced greatly, thus yielding a high steering accuracy.

Power-assisted steering with hydraulic power assistance

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

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Sandweg, Germany

Wolfgang Zeitz