Valves and valve actuation – Fluid actuated or retarded – Pilot or servo type motor
Reexamination Certificate
2000-10-19
2001-10-02
Shaver, Kevin (Department: 3754)
Valves and valve actuation
Fluid actuated or retarded
Pilot or servo type motor
C251S030010, C251S118000
Reexamination Certificate
active
06296226
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates generally to systems for metering fluids. More particularly, it relates to an apparatus for the controlled delivery of fluids at low flow rates.
BACKGROUND OF THE INVENTION
Delivery devices for the delivery of fluids at predetermined flow rates are well known in the art. The delivery of fluids at rates of below approximately 30 milliliters per minute typically involve the use of devices such as syringe pumps. While such devices are suitable for regulating very low rates of flow, they generally are not adequate for flow rates above 30 milliliters per minute. The delivery of fluids at rates above approximately 200 milliliters per minute typically includes the use of flow meters. However, such devices are generally unsuitable for flow rates below 200 milliliters per minute. Thus, it is difficult to use conventional devices to produce flow rates in the range of approximately 30-200 milliliters per minute.
Conventional flow meters and pumps provide the additional disadvantage that such devices include moving elements involving chemicals that may interfere with the purity and chemical characteristic parameters required in certain industries, such as the semiconductor fabrication or medical industries. Noninvasive flow meters that do not interfere with the required purity and chemical characteristics parameters, such as vortex meters, Corioles meters, ultrasonic meters, magnetic flow meters and the like, are typically large, closed-loop units that take up valuable space.
Thus, there is a need for a compact, open-loop fluid metering device that is suitable for delivering fluid at constant rates in the range of approximately 30-200 milliliters per minute. There is a further need for a fluid metering device that will not interfere with the purity and chemical characteristic parameters of the fluid during flow.
SUMMARY OF THE INVENTION
These and other aspects of the present invention will become more apparent to those skilled in the art from the following non-limiting detailed description of preferred embodiments of the invention taken with reference to the accompanying figures.
In accordance with an exemplary embodiment of the present invention, a fluid metering apparatus for the delivery of a fluid at a desired flow rate uses air pressure to regulate the pressure of the fluid thereby regulating the fluid flow rate. The fluid metering apparatus includes a gas inlet and a first regulator in fluid communication with the gas inlet and configured to receive a gas from the gas inlet and emit the gas at a first gas pressure. A second regulator is in fluid communication with the gas inlet and configured to receive the gas from the gas inlet and emit the gas at a second gas pressure. A first valve is in fluid communication with the first regulator and a second valve is in fluid communication with the second regulator. A switch mechanism is connected to the first valve and the second valve and has a first actuator and a second actuator, wherein said switch mechanism causes the first valve to be open and the second valve to be closed when the first actuator is actuated and causes the second valve to be open and the first valve to be closed when the second actuator is actuated.
The apparatus also includes a fluid pressure regulating device which has a fluid inlet port configured to receive a fluid to be metered, wherein the fluid has a fluid inlet pressure. The fluid pressure regulating device also has a gas inlet port, in fluid communication with the first valve and the second valve, and a fluid outlet port. When the first actuator of the switch mechanism is actuated, the fluid pressure regulating device is configured to deliver the fluid to the fluid outlet port at a first device outlet flow rate which is proportional to a predetermined ratio of the fluid inlet pressure and the first gas pressure. When the second actuator of the switch mechanism is actuated, the fluid pressure regulating device is configured to deliver the fluid to the outlet port at a second device outlet flow rate which is proportional to a predetermined ratio of the fluid inlet pressure and the second gas pressure.
The apparatus further includes a fluid outlet and an orifice fitting which is in fluid communication with the fluid outlet port of the fluid pressure regulating device and is configured to effect a pressure drop between the fluid outlet port and the fluid outlet.
In accordance with another embodiment of the present invention, the fluid metering apparatus further has a fluid flow activation device which is configured to permit the fluid to flow from the fluid inlet port to the fluid outlet port when either the first actuator or second actuator is actuated.
In accordance with a further embodiment of the present invention, the fluid flow activation device has an activation valve, which is in fluid communication with the gas inlet and the fluid pressure regulating device and which is opened when either the first or second actuator is actuated.
In accordance with yet another embodiment of the present invention the switch mechanism has an electronic assembly which is configured to transmit a first electronic signal to the first valve when the first actuator is actuated and to transmit a second electronic signal to the second valve when the second actuator is actuated.
In accordance with yet a further embodiment of the present invention, the electronic assembly transmits the first electronic signal to the activation valve when the first actuator is actuated and the second electronic signal to the activation valve when the second actuator is actuated.
In accordance with another embodiment of the present invention, the second regulator may be in fluid communication with said first regulator gas-outlet and may be configured to receive the gas from the first regulator gas outlet and emit the gas at a second gas pressure, wherein the first gas pressure is higher than the second gas pressure.
In accordance with a further embodiment of the present invention, a fluid metering apparatus for the delivery of a fluid at one of N delivery pressures, wherein N is any integer greater than 1 and i is any number from 1 to N, includes a gas inlet for receiving a gas and N regulators. Each N
i
regulator is in fluid communication with the gas inlet and is configured to emit said gas at a corresponding N
i
gas pressure. The apparatus further includes N valves. Each N
i
valve is in fluid communication with a corresponding N
i
regulator. A switch mechanism is connected to each N
i
valve and has N actuators. The switch mechanism causes an N
i
valve to be opened and the remaining valves to be closed when an N
i
actuator is actuated. The apparatus further includes a fluid pressure regulating device. The fluid pressure regulating device has a fluid inlet port which is configured to receive a fluid to be metered, wherein the fluid has a fluid inlet pressure. The fluid pressure regulating device also has a gas inlet port in fluid communication with each N
i
valve and a fluid outlet port. When an N
i
actuator of the switch mechanism is actuated, the fluid pressure regulating device is configured to deliver the fluid to the fluid outlet port at a device outlet pressure which is proportional to a predetermined ratio of the fluid inlet pressure and the N
i
gas pressure which corresponds to the N
i
actuator that was actuated.
The apparatus further includes a fluid outlet which is configured to emit the fluid at an N
i
delivery flow rate and an orifice fitting which is in fluid communication with the fluid outlet port and configured to effect a pressure drop between the fluid outlet port and the fluid outlet.
REFERENCES:
patent: 3880178 (1975-04-01), Panissidi
patent: 4065094 (1977-12-01), Adams
patent: 5181538 (1993-01-01), Manganaro
patent: 5520206 (1996-05-01), Deville
Bonderer D. Austin
Shaver Kevin
Snell & Wilmer LLP
SpeedFam-IPEC Corporation
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