Rotary slide valve for assisted steering systems

Rotary slide valve for use with hydraulic power steering units, comprising:

• a housing,
• a valve bushing located in the housing,
• a rotatable slide located within the valve bushing to form a rotary slide valve,
• a drive shaft connected with the valve bushing of the rotary slide valve,
• a steering shaft connected with the rotary slide of the rotary slide valve and to a manual steering wheel,
• a rotating rod positioned between the valve bushing and the rotary slide of the rotary slide valve,
• a reaction chamber defined by a reaction piston and a lid, said reaction chamber including feed grooves for feeding a pressurized fluid to the reaction chamber and return grooves for removing fluid from the reaction chamber,
• a centering device positioned between the valve bushing and the rotary slide of the rotary slide valve, said centering device including a plurality of inclined surfaces at least two of which are associated with the reaction piston, a plurality of roller bodies located between said inclined surfaces, and a spring located in the reaction chamber and supported against the reaction piston by a needle bearing, said spring being used for the precise positioning of the rotary slide valve in a central position by exertion of a pressure force on the roller bodies via the reaction piston, and
• means for applying a speed-dependent variable pressure in the reaction chamber to the same side of the reaction piston as is acted upon by the spring whereby a speed-dependent steering resistance is generated in the manual steering wheel.