Fluid-pressure and analogous brake systems – Speed-controlled – Having a valve system responsive to a wheel lock signal
Patent
1992-05-08
1994-03-01
Butler, Douglas C.
Fluid-pressure and analogous brake systems
Speed-controlled
Having a valve system responsive to a wheel lock signal
303 841, 137514, 267204, B60T 832, F16K 1706
Patent
active
052900967
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The present invention relates to a pressure control valve, in particular for the pressure fluid control in slip-controlled hydraulic brake systems.
Conventional pressure control valves for the flow control of fluids in slip-controlled hydraulic brake systems are in wide use.
Pressure control valves are known, such as described in patent application P 39 30 757.3 for example, which have a valve tappet guided in a valve housing acted upon by a compression spring. The valve tappet end remote from the compression spring is formed as a spherical closure cooperating with a valve seat in order to interrupt the pressure fluid connection between the fluid supply and return in a leak-free manner when the valve is in its closed position.
In order to diminish the occurrence of noise and particularly the solid-borne sound during the stroke movement of the valve tappet, axially extending recesses are arranged unsymmetrically around the periphery of the valve tappet which bring about a radial pressure force resultant depending on the rate of flow and thereby an attenuation of the vibration. To manufacture such a shaped valve tappet, however, additional sophisticated machining steps are required.
It is therefore an object of this invention to improve upon a pressure control valve of the type referred to in such a manner as to achieve a major reduction in noise during the valve control phase with simple cost-efficient means, while the operational reliability is safeguarded at the same time.
SUMMARY OF THE INVENTION
According to the present invention, the object set forth is achieved by the arrangement of a friction element whose radial friction surfaces are effective during the movement of the valve tappet in order to attenuate the mechanical vibrations of the valve tappet in such a manner that, on the one hand, the audible operating noises of the valve tappet are avoided and, on the other hand, possibly occurring compressional vibrations can be reduced.
The friction element can advantageously take the form of a friction ring clamped in between the inner end wall of the valve housing and the compression spring on the side of the valve tappet which ring having a bore which receives and frictionally engages the outside of the valve tappet. Upon initiation of the valve stroke movement, the engagement of the bore of the friction ring diminishes the vibrations. Likewise, as an alternative of the frictional engagement of the bore, the outside diameter of the friction ring can be in frictional engagement with the inside wall of the valve housing, a considerably larger peripheral effective surface thereby being in frictional contact as a result so that good static friction properties can be realized on start-up of the stroke movement on the tappet side.
Both design variants permit a relatively simple attachment of the friction ring in that the friction ring, preferably constructed as an elastomeric friction element, is held in proper position by the compression spring.
In order to maximize use of available space, it is particularly expedient to use a compression spring which itself generates friction forces acting in an axial direction. The compression spring may be clamped in between the internal end surface of the valve housing and an axial stop of the valve tappet, with its spring coils in frictional contact with the radial inside wall of the valve housing. It is hence possible by selecting a suitable compression spring to control the friction forces generated.
The frictional contact between the compression spring and the valve housing may be brought about by a slope of a spring abutting surface, effective transversely to the spring's longitudinal axis, on which slope one end of the compression spring is abutting. Buckling of the compression spring may thus be initiated, dependent on the spring preloading force. Hence, the frictional contact on the valve housing permits an attenuation of the vibrations which depend on the valve stroke.
Major reduction in the manufacturing costs while maintaining
REFERENCES:
patent: 2564815 (1951-08-01), Raymond
patent: 2948529 (1960-08-01), Maier
patent: 3107906 (1963-10-01), Maier
patent: 3782412 (1974-01-01), Darash
patent: 3796228 (1974-03-01), Bedo et al.
patent: 3848632 (1974-11-01), Powell
patent: 5199769 (1993-04-01), Beck et al.
Beck Erhard
David Anton
Kornemann Horst
Weisbrod Helmut
Alfred Teves GmbH
Butler Douglas C.
Lewis J. Gordon
Seitter Robert P.
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