Fluid handling – Line condition change responsive valves – Pilot or servo controlled
Reexamination Certificate
1999-12-28
2001-01-30
Huson, Gregory L. (Department: 3753)
Fluid handling
Line condition change responsive valves
Pilot or servo controlled
C137S486000, C137S488000, C137S334000, C251S057000
Reexamination Certificate
active
06178996
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a fluid flow control apparatus for use in, for example, supplying a process gas for manufacturing semiconductors.
In a process for manufacturing semiconductors, there has been an increasing demand for a flow rate control apparatus for gasifying a liquid or solid material at a high temperature and feeding the resultant gas in a stable manner.
The above-mentioned flow rate control apparatus is used in a high-temperature environment of 100° C. or more. Therefore, as a control valve for the above-mentioned flow rate control apparatus, an electromagnetic valve adapted for use at a high temperature has been conventionally used. However, even in the electromagnetic valve adapted for use at a high-temperature, the heat-resistance of a coil is limited, so that a usable maximum temperature for the electromagnetic valve is about 200° C. Further, many materials used for manufacturing semiconductors are chemically reactive. Therefore, a diaphragm-operated control valve has been strongly desired.
However, in a diaphragm-operated control valve, the actuator for the valve is required to generate a force as large as 10 kg/cm
2
or more. Such a large force cannot be obtained when the actuator is an electromagnetic valve. Therefore, it is difficult to enable the use of a diaphragm-operated control valve by using an electromagnetic valve.
SUMMARY OF THE INVENTION
In view of the above situation regarding conventional flow rate control, the present invention has been made. It is an object of the present invention to provide a flow rate control apparatus which is usable at a temperature of 200° C. or more and which is capable of conducting flow rate control appropriately by movement of a diaphragm.
The present invention provides a flow rate control apparatus for controlling a fluid flow rate by controlling a degree of opening of an orifice through which a fluid flows. The flow rate control apparatus comprises: a control valve for controlling the degree of opening of the orifice by movement of a diaphragm which is operated by a pressure-operated valve actuator, tube feeds a pressure to the valve actuator from a position remote from the valve actuator, and a pressure control means arbitrarily controls the pressure to be fed to the valve actuator.
By this arrangement, when the control valve is placed in high temperature condition, the diaphragm is moved by means of the pressure-operated valve actuator so as to control the degree of opening of the orifice through which the fluid flows. Therefore, the desired flow rate control can be effected.
The present invention also provides a flow rate control apparatus for controlling a fluid flow rate by controlling a degree of opening of an orifice through which a fluid flows, the flow rate control apparatus comprising a control valve for controlling the degree of opening of the orifice by movement of a diaphragm which is operated by a pressure-operated valve actuator, a tube feeds a pressure to the valve actuator from a position remote from the valve actuator, a flow rate sensor detects an actual flow rate of the fluid under operation of the control valve, and a controlling part controls the pressure to be fed to the valve actuator so that an actual flow rate signal representative of the actual flow rate detected by the flow rate sensor coincides with a flow rate command signal externally applied to the controlling part.
In the flow rate control apparatus of the present invention, a heat exchanger may be provided at a portion of the tube for feeding the pressure to the valve actuator and the heat exchanger and the control valve may be placed in an atmosphere having the same temperature.
In the flow rate control apparatus of the present invention, the valve actuator may be operated by the application of the pressure of a gas and the flow rate control apparatus may include pressure control means having at least one control valve for feeding the gas to the valve actuator and discharging the gas therefrom.
In the flow rate control apparatus of the present invention, the valve actuator may be operated by the application of liquid pressure and the flow rate control apparatus may include pressure control means having a liquid pump for generating the liquid pressure.
The foregoing and other objects, features and advantages of the present invention will be apparent from the following detailed description and appended claims taken in connection with the accompanying drawings.
REFERENCES:
patent: 5549137 (1996-08-01), Lenz et al.
patent: 5678601 (1997-10-01), Engel
patent: 5678803 (1997-10-01), Shinohara et al.
patent: 5931186 (1999-08-01), Skoglund
Huson Gregory L.
Krishnamurthy Ramesh
MKS Japan Inc.
Wenderoth , Lind & Ponack, L.L.P.
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