This invention generally relates to fluid flow regulating valves and, more particularly, to flow valves that provide a constant liquid flow rate under conditions of varying inlet pressures.
Flow valves that provide a constant fluid flow under conditions of varying inlet pressure are useful for a wide variety of applications such as, for example, in water lines for plumbing installations, coolant lines for refrigeration systems and hydraulic fluid lines for brake systems, as well as components of sprayer apparatus.
Dillman, U.S. Pat. No. 3,073,350, the disclosure of which is incorporated herein by reference, describes a constant fluid flow valve that includes an inwardly radiating abutment flange at its downstream end and an outwardly radiating flange at its upstream end that includes a series of openings for permitting a desired fluid flow.
May, US Patent Application No. 2003/0079782, the disclosure of which is incorporated herein by reference, describes a flow control valve that includes an annular throttling orifice defined by the relative positions of a flow port and a tapered probe element.
Newton, US Patent Application No. 2006/0267403, the disclosure of which is incorporated herein by reference, describes a constant flow valve having a base section that is divided into a fluid chamber and a spring chamber by a modulating assembly that is supported by a flexible diaphragm within the valve housing.
McCann et al., U.S. Pat. No. 5,097,863, the disclosure of which is incorporated herein by reference, describes a flow control valve for maintaining a constant flow rate that includes a sleeve and a piston, a membrane positioned between the sleeve and the piston, and a spring adjustment member that includes a set screw.
Oyama, U.S. Pat. No. 5,904,335, the disclosure of which is incorporated herein by reference, describes a flow control valve that includes a first fluid chamber, a piston, and a variable-area orifice within the valve housing, and a second fluid chamber connected to the first fluid chamber by a fixed-area orifice.
Okuda et al., U.S. Pat. No. 4,437,493, the disclosure of which is incorporated herein by reference, describes a constant flow control valve that contains a main flow passage whose area is variable with pressure fluctuation, and a by-pass passage mounted along an external periphery of the main flow passage.
The present invention is directed to a valve for maintaining constant fluid flow under conditions of a specified operating inlet pressure and varying inlet pressures in excess of the specified pressure. The valve comprises: a tubular valve body comprising an inlet end, an outlet end, and a fluid flow channel extending between the inlet and outlet ends; a cylindrical flow control member axially aligned within the valve body and slidably engageable with an annular flange extending inwardly within the valve body proximate the inlet end; and a compression spring axially aligned within the valve body and acting to cause the flow control member to move within the valve body in response to variations in the inlet pressure.
The flow control member comprises an annular band having a first surface congruent with a surface of the annular flange and a second surface congruent with an interior surface of the valve body; wherein the first band surface and flange surface define a first flow path having a first variable volume and a first variable cross-sectional area. The second band surface and valve body interior surface define a second flow path having a second variable volume and a second variable cross-sectional area.
The valve further comprises an outlet orifice for discharge of fluid from the valve, the outlet orifice having a cross-sectional area less than the minimum of the first or second variable cross-sectional areas.
The first and second variable volumes are substantially equal at the specified operating inlet pressure. If the inlet pressure exceeds the specified pressure, action of the compression spring on the flow control member causes the first variable volume to increase and the second variable volume to decrease, thereby maintaining a substantially constant fluid flow from the valve. A decrease in the inlet pressure below the specified pressure causes the first variable volume to decrease and the second variable volume to increase, thereby maintaining a substantially constant fluid flow from the valve.
As shown in
Valve 100 further comprises a compression spring 111 axially aligned within valve body 101 and acting to cause flow control member 104 to move within valve body 101 in response to variations in inlet pressure.
Valve 100 also includes an outlet orifice 112 that has a cross-sectional area less than the minimum of the first or second variable cross-sectional area. Outlet orifice 112 may be included in a nozzle 113, which may be connected to valve body 101 by first threading 114. Valve body 101 may further include second threading 115 at inlet end 102 to facilitate attachment of valve 100 to a fluid source (not shown).
When the inlet pressure exceeds the specified operating pressure, the first variable volume is caused to increase and the second variable volume to decrease, thereby maintaining a substantially constant fluid flow from valve 100. Conversely, when the inlet pressure falls below the specified operating pressure, the first variable volume is caused to decrease and the second variable volume to increase, thereby again maintaining a substantially constant fluid flow from valve 100.
As depicted in
As shown in
The valve of the present invention is particularly suitable for applications requiring the precise spraying of liquid chemical formulations, including those produced by mixing two or more liquids, overcoming a wide range of inlet pressures to maintain a constant outlet pressure determined by a selected spring rate.
While the invention has been described by reference to various specific embodiments, it should be understood that numerous changes may be made within the spirit and scope of the inventive concepts described. Accordingly, it should be recognized that the invention is not limited to the described embodiments but has full scope defined by the language of the following claims.