Fluid handling – Processes – With control of flow by a condition or characteristic of a...
Reexamination Certificate
1997-09-19
2001-09-11
Walton, George L. (Department: 3753)
Fluid handling
Processes
With control of flow by a condition or characteristic of a...
C251S036000, C251S046000, C251S047000, C251S051000, C251S052000
Reexamination Certificate
active
06286533
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a metering valve for use in sanitary installations. More particularly, the present invention relates to a self-closing valve assembly with reduced operating effort and improved ability to maintain a timed flow of water despite variations in water supply pressure and temperature.
Metering valves for lavatory applications are generally used in commercial or public buildings. Metering valves are intended to provide a flow of water for a predetermined period of time when they are actuated. Typically, a metering valve is mounted on, for example, a faucet in a public restroom and actuated by pressing down on a handle. When the handle is released, water is supposed to flow for a preset time to allow the user to wash up. After the preset time, the metering valve completely shuts off the water.
Several existing metering valves use a washer compression valve as the main water flow control valve. Washer compression valves use the inlet water pressure to assist in sealing. The force of the inlet water pressure must then be overcome to open the valve. Because of this direct dependence on inlet water pressure, these types of metering valves are often very sensitive to changes in water pressure and are thus prone to large swings in operating effort necessary to begin water flow as well as swings in cycle time once the valve is actuated. The operating effort necessary to actuate a metering valve used in public buildings is preferably five pounds or less under the Americans with Disabilities Act (ADA).
In order to control the cycle time of the metering valve, various valve configurations have been attempted in the industry. U.S. Pat. No. 4,899,778 discloses a metering valve that uses handle stroke and a very small diameter pilot hole to control cycle time. This design can lead to cycle times that are very dependent upon inlet water supply pressure. Also, the small pilot hole can be easily clogged. The metering valve disclosed in U.S. Pat. No. 3,933,337 discloses another approach to maintaining a desired cycle time through the use of a sealed damping chamber containing a special timing fluid. This design can be disadvantageous because small amounts of the timing fluid may be lost with each cycle. Also, any type of timing fluid with a higher viscosity than water will increase operating effort and be sensitive to water temperature changes.
Accordingly, there is a need for a metering valve with an operating effort that is less sensitive to water supply pressure and temperature, a cycle time that is not significantly affected by water supply pressure and temperature, and improved resistance to mineral or particulate contamination in the water supply.
SUMMARY OF THE INVENTION
According to a first aspect of the present invention, a metering valve for use in a lavatory is provided having a relief valve assembly operatively connected to a handle. The relief valve assembly includes a damping mechanism for controllably closing the relief valve assembly after the handle receives an actuating force opening the relief valve. A pilot valve assembly is mounted over a water supply inlet independently of the relief valve assembly and the handle. The pilot valve assembly is hydraulically controllable by the relief valve to open or close off a flow of water from the water supply inlet. Preferably, the damping assembly of the metering valve consists of a damping member and biasing member positioned in a damping chamber adjacent to the relief valve wherein the spring constant of the biasing member and a water channel in the damping chamber control the cycle time of the metering valve substantially independently of the water pressure or temperature of the water supply.
According to another aspect of the present invention, a method of actuating a metering valve includes the step of providing a metering valve having a relief valve operatively connected to a handle and a pilot valve assembly covering a water supply inlet. The pilot valve assembly is movably mounted inside the metering valve independently of the handle and relief valve. The pilot valve has a first side covering the water supply inlet and a second side opposite the first side, the water supply inlet providing water at a predetermined water pressure. A downforce is provided on the handle that is transmitted from the handle to the relief valve. The relief valve opens when the downforce reaches a predetermined threshold. Water pressure on the second side of the pilot valve is then reduced by channeling water through the opened relief valve. The pilot valve is automatically opened with the force of the water supply pressure when the force of the reduced water pressure against the second side of the pilot valve becomes less than the force of the water supply pressure against the first side of the pilot valve. The relief valve is closed at a rate substantially independent of the water supply pressure and causes an increased water pressure on the second side of the pilot valve. The pilot valve then quickly closes in response to the increased water pressure that builds up on the second side of the pilot valve.
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Brinks Hofer Gilson & Lione
Mark Controls Corporation
Walton George L.
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