Fluid handling – Systems – Multi-way valve unit
Patent
1997-03-21
1998-06-23
Michalsky, Gerald A.
Fluid handling
Systems
Multi-way valve unit
29890128, 91375A, 180423, F15B 910
Patent
active
057691215
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to a rotary slide valve for the power steering of motor vehicles in accordance with the present invention. The rotary slide valve contains two valve parts which are arranged to be coaxially movable inside each other and are maximally rotatable in respect to each other about the rotational travel path of a backlash coupling. In this case the first valve element, which is connected with a valve inlet member, is externally embodied as a radial rotary distributor. The second valve element is fixedly connected to prevent relative rotation, with a valve outlet member and is located inside as a radial control bushing, which is guided in an axial bore of the rotary distributor. Both valve elements have longitudinal control ports which are at least partly limited in their axial length and cooperate with each other for the control of a pressure medium into and out of two work chambers of a servo motor. A torsion bar is used to reset the two valve elements from a deflected position into their neutral position.
2. Description of the Prior Art
A rotary slide valve of this type is the subject of DE-A1-43 10 396. This rotary slide valve has the advantage that it is possible to keep the exterior size of the entire valve very small by means of the special arrangement of the control bushing in the interior of the rotary distributor. Centering of this rotary slide valve is performed exclusively via the torsion bar. A torsion bar is known to have the property that the reset in the central area of the rotary slide valve by the torsion bar is very small.
In connection with other rotary slide valves it has therefore been proposed to provide a centering device in addition to the torsion bar, which allows very exact centering, particularly in the direct central area of the rotary slide valve. Such an additional centering device is known, for example, from DE-C1 42 01 311. In this embodiment the additional centering device requires additional structural space in the axial direction. However, the essential disadvantage is that this middle centering device can no longer be adjusted after the individual parts have been manufactured. Because of this, large differences in the middle of the central area and in the torque are possible. Since the centering spring is supported on the one end on a rotating element and on the other end on a stationary one, additional friction is created which influences the sensitivity of the rotary slide valve.
The object of the invention is therefore based on equipping the known rotary slide valve with an additional adjustable middle centering device which does not cause any additional friction between the two valve elements.
SUMMARY OF THE INVENTION
This object is attained by means of the rotary slide valve of the present invention. Advantageous embodiments of the invention are recited in the dependent claims. A method for mounting the rotary slide valve in accordance with the invention is described herein.
The solution is that a spring-loaded centering device is located between the rotary distributor and the valve outlet member of the rotary slide valve of the type, which contains two elements which can be rotated with respect to each other, and with at least one ball situated between the two elements. As a result, one part is fixedly connected with a reaction piston, and is fixedly connected with the rotary distributor to prevent relative rotation, but is axially displaceable. The other part is fixed to the outlet element in a predetermined position to prevent relative rotation and prevent axial displacement. The ball is maintained in the recesses of the two elements.
Because of the placement of the centering device between the rotary distributor and the valve outlet member, a part of the centering device can be fixed in a predetermined position to the valve outlet member. Because of this the centering device can be easily adjusted with respect to the centering position and centering force even after manufacturing of the indi
REFERENCES:
patent: 5135068 (1992-08-01), Emori et al.
patent: 5575193 (1996-11-01), Bareis et al.
Michalsky Gerald A.
ZF Friedrichshafen AG.
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