Fluid-pressure and analogous brake systems – Speed-controlled – Having a valve system responsive to a wheel lock signal
Patent
1991-05-14
1993-04-06
Graham, Matthew C.
Fluid-pressure and analogous brake systems
Speed-controlled
Having a valve system responsive to a wheel lock signal
137514, 303 841, F16K 1706
Patent
active
051997690
DESCRIPTION:
BRIEF SUMMARY
INTRODUCTION
The present invention is related to flow control valves, and more particularly, noise reduction in the operation of valves of the type in which a valve tappet is mounted in a bore in a valve housing, the valve tappet moving towards and away from a valve seat during operation.
BACKGROUND OF THE INVENTION
Such valves are commonly used in slip-controlled hydraulic brake systems.
Valves for a slip-controlled hydraulic brake system are disclosed in German patent application P 37 01 019.0, each comprising a valve seat receiving a valve tappet, the valve tappet being moved by an electromagnet and being axially movably guided in a valve housing. An annular flow cross-section opens between the valve tappet and the valve seat when the valve tappet is shifted in a controllable manner, the flow cross-section communicating with pressure-fluid channels within the valve housing. To control all brake circuits, several valves are often included in a common valve block housing so that there is accomplished a space-saving positioning of each valve in an economical and cost-efficient manner.
What is to be considered less favorable in the known valve design is the noise behavior of the valve during the valve's shift periods, which behavior is due to the marginal layer separation of on the valve closure member circulated by hydraulic fluid as well as due to the resultant radial vibrations and/or the radial contact of the valve tappet on the valve seat in consequence of unstable flow.
In order to diminish the occurrence of noise and thus the transmission of sound conducted through the housing major passive and also active measures for noise attenuation are taken at present which, however, all entail considerable cost and offer more or less satisfying results.
SUMMARY OF THE INVENTION
It is, therefore, an object of the present invention to improve a valve of the type referred to to achieve a significant noise reduction during the valve's shift periods to overcome the drawbacks of prior design, while the operational reliability is ensured at the same time.
This object is achieved by causing a force to be generated which acts on the tappet causing one side of a tappet head to be urged into contact an adjacent surface housing, with asymmetric flow opening defined at the other side of the tappet head receiving flow through the valve.
A valve is obtained thereby which considerably diminishes the cause of noise without increasing manufacturing costs excessively and without significantly impairing the control function of the valve.
In a preferred embodiment of the subject matter of this invention, a transverse force resultant is exerted on the valve tappet by virtue of the available pneumatic or hydraulic flow media, caused by an asymmetric pressure distribution in the flow cross-section. A radial shift of the valve closure member thereafter results in a concentric configuration of the penetration surface.
An alternative embodiment of this invention for generating the transverse force resultant is obtained by a mechanical transverse spring action in that the radial abutment of the valve tappet on the valve seat is rendered possible by inserting an inclined washer in the area of the valve tappet guidance, for instance.
Low cost manufacture of the valve tappet in the area of the tappet head results from the asymmetric arrangement of the axially extending recesses which determine the penetration surface, since for example instead of the symmetric distribution of four groove-shaped recesses over the circumference, only two recesses of greater width are provided on a portion of the tappet head. This facilitates the manufacturing process.
Owing to a fluted shape of the grooves in the tappet head, a valve tappet minimized in respect of inherent stress as well as optimized in respect to flow is attained which adopts an eccentric position under the action of radial pressure forces.
In order to insure leak free sealing of the valve closure member of the valve seat, one embodiment of the invention provides that the valve closur
REFERENCES:
patent: 2345379 (1944-03-01), Campbell
patent: 3003423 (1961-10-01), Drutchas
patent: 3354898 (1967-11-01), Barnes
patent: 3782412 (1974-01-01), Darash
patent: 4030520 (1977-06-01), Sands
patent: 4440454 (1984-04-01), Belart et al.
Beck Erhard
Kornemann Horst
Schweighofer Bernd
Alfred Teves GmbH
Graham Matthew C.
Lewis J. Gordon
Seitter Robert P.
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