Valves and valve actuation – Fluid actuated or retarded – Pilot or servo type motor
Reexamination Certificate
2000-01-18
2001-09-18
Lee, Kevin (Department: 3753)
Valves and valve actuation
Fluid actuated or retarded
Pilot or servo type motor
C251S030020, C251S045000
Reexamination Certificate
active
06290203
ABSTRACT:
FIELD OF THE INVENTION
This invention relates generally to valves for controlling the flow of fluids and relates specifically to valve assemblies where a pilot valve controls the opening and closing of a main valve.
BACKGROUND OF THE INVENTION
Valve assemblies having a pressure responsive main valve member operated by a low force, short travel pilot valve actuator are relatively well known in the art. A low force short travel actuator permits a valve of this type to be operated by a low wattage solenoid or by a magnetic latch type device. These are important aspects for a valve used in conjunction with the ever growing electronic control field where low wattage devices are always an advantage, or where a valve assembly may be adaptable to a magnetic latch type actuator for battery operation. Valves of the type described are commercially available in a number of configurations, but due to their more complicated structure, bulk, and high cost, have not gained a wide acceptance in the market place. It is therefore the primary object of this invention to provide a pilot operated valve assembly of simple construction, compactness, economical manufacturing cost and one that can operate with a low force, short travel pilot actuator and that by the foregoing stated criteria, would gain a greater acceptability over present types now available.
To meet the simplicity object, in one aspect the present invention was developed as an improvement over the construction of the valve described in U.S. Pat. No. 3,672,627 to W. R. McCarty, Jr. et al. Although the McCarty patent is of simple construction and operates with small actuation forces, it also needs a pilot actuator that requires a large actuator travel that limits its capability for achieving low operational power and for adaptability to magnetic latch operation. An attempt to reduce the power consumption of a long actuator travel pilot valve is described in U.S. Pat. No. 4,502,661 to Wesley S. Swanson. Although this valve operates at lower continuous power levels than that shown by McCarty, the long actuation stroke required at its initial energization requires a high power spike which in some applications could be undesirable. The added pole piece also adds a little more complexity over the McCarty valve, but still requires a similar lengthy stroke and thereby limits its adaptability to be an efficient magnetic latch type actuator. The valves shown by McCarty and Swanson are simple, compact, and economical to manufacture, but due to their large actuator travel requirements, do not meet the desired objects of the invention.
U.S. Pat. No. 4,283,040 to L. Kolze, describes a valve where the pilot valve actuator does provide the low force and short actuator travel requisite, is relatively compact, but is more complicated and costly to manufacture and thereby does not fully meet the present invention objectives. Other valves meeting the performance criteria of low force and short pilot actuator travel are those similar to that shown in
FIG. 3
of this application, where the pilot actuator is offset from the pressure responsive main valve member. These valve designs are bulky, complex, and costly to manufacture. As shown in
FIG. 3
which illustrates the prior art, location of the pilot valve spaced apart from the main valve creates a structure where pilot and bleed passages are difficult to economically fabricate and the need for special orientation to assemble asymmetrical parts adds to the cost. Also, these valves use seal gasketing that is not symmetrical and can cause some difficulty to obtain uniformity of gasket sealing pressure that could lead to seal leakage. The
FIG. 3
valve utilizes the eccentric pilot location with respect to the pressure responsive main valve member to obtain a short pilot actuator travel over that required by the McCarty and Swanson valves, but at the expense of complexity, size, and cost. Thus, all the above valve assemblies described are deficient in some aspect of the objectives achieved by the present invention which will be more fully understood from the Summary of the Invention below and Detailed Description that follows.
SUMMARY OF THE INVENTION
A surprisingly unique and useful combination has been discovered and is provided by the present invention which is an improved structural arrangement of the elements of a valve assembly where a pressure responsive main valve member can be operated by a pilot actuator having a small actuation force and a small actuator travel. The valve assembly comprises an insert structure within a valve housing which incorporates therein the pressure responsive main valve member, the pilot actuator, and its associated pilot passages. This arrangement allows the valve to be made of component parts that can be economically fabricated and assembled into a very compact assembly. The valve structure utilizes symmetry of individual parts for assembly ease and allows the use of simple O-ring seals. The valve construction also offers flexibility to use either metal or plastic materials as any machining or molding of component parts can be accomplished at simple axially and right angle oriented production processes. Since the housing, insert, and pilot actuation components can be made circular, the valve construction permits a plastic spin weld assembly for added economy in manufacture.
In one aspect, the invention is a pilot operated pressure actuated valve assembly which comprises a housing having a main fluid passage with inlet and outlet passages. A main valve seating surface within said housing located between said inlet and outlet passages; a pressure responsive main valve member movable with respect to the housing from a closed position contacting said seating surface to an open position spaced apart from said seating surface to permit flow from the inlet to the outlet passage; an insert disposed within said housing, the space between the pressure responsive main valve member and said insert defining a pilot chamber in said insert, said insert having pilot passages therein communicating said inlet, said pilot chamber, and said outlet; means for biasing said pressure responsive main valve member to the closed position; means defining a pilot flow passage for communicating said inlet passage and said outlet passage; a pilot valve member movable between a closed position preventing fluid flow through said pilot flow passage and an open position permitting flow therethrough; means for biasing said pilot valve member to a closed position; and, means for moving said pilot valve member from the closed to the open position to permit fluid to flow through said pilot flow passage thereby causing a pressure differential across said pressure responsive main valve member whereby said pressure responsive main valve member is opened to permit flow from said inlet passage to said outlet passage.
In another aspect, the valve assembly of the invention is arranged so that the distance said pressure responsive main valve member moves from a closed position to an open position is greater than the distance said pilot valve member moves from its closed to open position. The distance the main valve moves is limited only by its designed stroke capability while the pilot actuator is designed to provide minimal operational travel and force requirements.
In still another aspect, the present invention provides that said pilot valve member, said pressure responsive main valve member, and said main valve seating surface are co-axial.
REFERENCES:
patent: 3439895 (1969-04-01), Marandi
patent: 3672627 (1972-06-01), McCarty, Jr. et al.
patent: 4283040 (1981-08-01), Kolze
patent: 4502661 (1985-03-01), Swanson
patent: 4531547 (1985-07-01), Hadden
patent: 4981280 (1991-01-01), Brandenberg
Flint & Kim, P.A.
Kolze, Inc.
Lee Kevin
LandOfFree
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