Fluid handling – Line condition change responsive valves – Bi-directional flow valves
Patent
1997-12-03
1999-10-05
Bennett, Henry
Fluid handling
Line condition change responsive valves
Bi-directional flow valves
137539, 137540, 1375157, F16K 1726, F16K 1500
Patent
active
059608226
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The invention relates to a valve arrangement of a hydraulic system, constructed as a step valve, including a housing which is provided with two pressure connections and has at least one valve seat to which a closing element is allocated which, in a closed position, has a first valve surface which is smaller than a second valve surface, which it has in a position where the closing element is displaced from the valve seat.
The use of one way valve, also called a non-return value or relief valve, is known in hydraulic systems to make a pressure medium flow possible and to block a return flow. Known valves of this type have a spring actuated closing element which lies sealingly against the sealing seat of the one way valve in its closed position. The construction of the valve requires that the opening pressure substantially depends upon the initial stressing force of the spring and the valve surface acted upon by pressure fluid. In this way, an increasing pressure flow resistance appears with the rise in the flow volume. This property is disadvantageous for a number of applications.
From DE-A 27 28 486 a type of valve arrangement is known in which a closing element lies sealing on a housing-side valve seat in the closed position. The pressurized fluid flows toward the closing element via an entrance in the housing and acts upon a valve surface which is smaller than a second valve surface which appears after the pressurized fluid displaces the closing element from the valve seat. The second valve surface at the same time corresponds to the diameter of the spherical closing element, whereby immediately after lifting the closing element from the valve seat, the flow-through cross section is not yet set up, because the closing element must be guided through a stepped section of a step boring having a diameter which is only slightly larger than the diameter of the closing element. After a further displacement of the closing element in a next larger section of the step boring, a new flow-through cross section is set up. The familiar one way valve makes possible an uncontrolled shifting of the closing element in the open position, whereby this can knock against the housing, which leads to a disadvantageous development of noise.
SUMMARY OF THE INVENTION
The object of the present invention is to minimize the flow-through resistance for a valve arrangement which is acted upon by pressure fluid in two flow directions, whereby its construction makes an effective reduction of noise possible.
The object is accomplished by the features mentioned in the characterization part of the first claim.
The accomplishment of the objective consists of arranging two step valves in a valve element at a distance from each other, each associated with one direction of flow, which are correspondingly provided with a valve seat and a spring actuated closing element. The inventive valve element used in a valve arrangement (which, for example, can be used in connection with a hydraulic circulation having changing flow directions), possesses an advantageous degressive opening characteristic of the closing element. This is achieved, since after opening the closing element, the flow resistance diminishes in comparison to a closed closing element owing to a larger surface acted upon on the closing element. In addition to the different surfaces of the closing element which are acted upon by pressure fluid between the closed and the open state, a relatively weak spring which displaces the closing element in the direction of the valve seat brings about a desired reduction of the flow resistance of the valve element.
Based on this configuration, a higher pressure is necessary for opening the step valve in comparison with the opened step valve. This mode of operation is useful for compensating for pressure pulsations in hydraulic systems through which, for example, pressure fluctuations occurring very frequently do not lead to a disadvantageous unwanted opening of the valve. The invention brings it about that the change i
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Search Report from International Application No. PCT/EP96/02855.
Search Report from Priority Application DE 195 25 948.3 dated May 9, 1996.
Adler Dieter
Matuschka Joachim
Weber Jorg
Bennett Henry
INA Wazlager Schaeffler OHG
Kim Joanne Y.
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