Fluid handling – Processes
Reexamination Certificate
1999-03-16
2001-05-29
Michalsky, Gerald A. (Department: 3753)
Fluid handling
Processes
C060S432000, C060S477000, C137S625660, C251S025000
Reexamination Certificate
active
06237617
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a proportional fluid control valve.
2. Description of Related Art
The flow of fluids is typically controlled by a fluid control valve(s). A conventional fluid control valve has a spool or other similar element that is movable between two positions. The spool is typically moved into one position by a solenoid and pushed back to the original position by a spring or another solenoid. The spool is in either one of two positions. Consequently, the flowrate through the valve is limited to the two positions of the spool. By way of example, a two-way valve is either open or closed, so that the flowrate through the valve is either at a maximum value or zero.
It is sometimes desirable to vary the flowrate in a fluid system. For example, insecticides are sometimes sprayed from a moving vehicle. As the vehicle is driven about a field, it may be desirable to limit the range of the spray so that insecticide does not fall onto a certain area. As another example, it may be desirable to vary the range of a water stream emitted by a sprinkler system so that the water more completely covers an area adjacent to the sprinkler heads.
To change the fluid flowrate, some fluid systems have a variable speed pump motor that is controlled by an electronic controller. The controller can be programmed, or receive manual inputs, to change the speed of the motor and the pressure of the pump. The change in pump pressure varies the fluid flowrate within the system. Variable speed pumps are relatively expensive and provide relatively inaccurate and unproportional control of the fluid flowrate, particularly if multiple valves and nozzles are used in the system.
Another method for controlling fluid flowrate is to incorporate a flow restrictor within the system. The flow restrictor may contain a valve that varies and restricts the flow of fluid in the system. By way of example, a sprinkler system may contain a cam driven flow restrictor valve that is attached to a moving sprinkler head. The restrictor valve incrementally closes and reduces the range of the water stream after each revolution of the sprinkler head. The control of a mechanical flow restrictor is limited to the particular assembly installed. Any variation in the flowrate typically requires the adjustment of a spring or other mechanical element. This requires the operator to be available and in a position to adjust the restrictor valve. This may be undesirable, particularly if the operator must also perform another function such as driving a vehicle that sprays insecticides. It would be desirable to have an electronically controlled fluid valve that provides proportional control of a fluid.
SUMMARY OF THE INVENTION
The present invention comprises a proportional fluid control valve. The proportional valve includes a fluid valve that controls the flowrate of an output fluid. The fluid valve is coupled to a pressure chamber of the control valve. The position of the fluid valve, and the corresponding flowrate of the output fluid, can be varied by changing the pressure of a working fluid within the pressure chamber. The pressure within the pressure chamber can be increased by a piston that pumps working fluid from a reservoir to the chamber. The piston is coupled to a first solenoid and a spring that move the piston in a reciprocating pumping motion. The pressure of the working fluid within the pressure chamber can be decreased by opening a bleeder valve that allows working fluid to flow from the pressure chamber back to the reservoir. The bleeder valve is coupled to a second solenoid and a spring that open and close the valve. The first and second solenoids are connected to a controller that generates digital signals which energize the solenoids and move the piston and bleeder valve, accordingly. The controller can move the fluid valve and vary the output fluid flowrate by energizing the solenoids and either increasing or decreasing the pressure within the pressure chamber.
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Grill Benjamin
Sturman Oded E.
Blakely , Sokoloff, Taylor & Zafman LLP
Michalsky Gerald A.
Sturman BG, LLC
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