Automatic pressure controller

Claim 2

In a pressure control device: A chamber; a pump communicating with said chamber for evacuating the atmosphere therein; a valve forming a fluid coupling between the inside and outside of the chamber to regulate the chamber pressure; means responsive to deviation of the actual chamber pressure from the desired chamber pressure to generate an error signal, said chamber having a sufficiently large volume that a small volume of fluid introduced into or removed from the chamber will not appreciably change pressure in the chamber creating a time lag between movement of the valve and achievement of a desired chamber pressure; a feedback loop adapted to deliver a signal representative of the flow rate through the valve; means in the feedback loop to vary the magnitude of the signal representative of the flow rate through the valve relative to the magnitude of the error signal; means to combine the error signal and the signal representative of the flow rate through the valve to generate a modified error signal; and an actuator driven by the modified error signal acting to open and close said valve.

Claim 3

The combination called for in claim 1 wherein the feedback loop includes a potentiometer variable proportional to the movement of the valve adapted to deliver a voltage through the loop which varies with the flow rate through the valve.

Claim 4

The combination called for in claim 1 wherein the valve comprises a hollow body portion; inlet and outlet ports communicating with the hollow portion of the valve body; an elongated tubular seat portion disposed adjacent one of said ports; an elongated closure member having a slight taper; and means for moving said closure member through said tubular seat to regulate flow rate whereby the flow rate is determined by the relative length and diameter of the flow passage.

Claim 5

In a device for controlling pressure in a vacuum chamber: A chamber; evacuating means communicating with said chamber for continuously removing gas therefrom; valve means forming a fluid coupling between the inside and outside of the chamber to regulate the flow rate of gas into the chamber; a transducer coupled to the inside of the chamber for generating a signal representing the chamber pressure; an actuator connected to the valve means for opening and closing the valve means; a first servo loop between the transducer and the actuator to deliver an error signal to the actuator representing the difference between the actual and the desired chamber pressure to change the valve position; means to deliver a signal representative of the desired chamber pressure to the first servo loop; a second servo loop connected between the first servo loop and the valve means for delivering a valve position feedback signal to the first servo loop to prevent excessive valve movement; an attenuator in the second servo loop to vary the magnitude of the valve position feedback signal; and a variable decay circuit connected to the second servo loop to prevent permanent discrepancy between actual and desired chamber pressures.

Claim 6

In a device for controlling pressure in a vacuum chamber: A chamber; evacuating means communicating with said chamber for continuously removing gas therefrom; valve means forming a fluid coupling between the inside and outside of the chamber to regulate the flow rate of gas into the chamber; a transducer coupled to the inside of the chamber for generating a signal representing the chamber pressure; an actuator connected to the valve means for opening and closing the valve means; a first servo loop between the transducer and the actuator to deliver an error signal to the actuator representing the difference between the actual and the desired chamber pressure to change the valve position; means to deliver a signal representative of the desired chamber pressure to the first servo loop; a second servo loop connected between the first servo loop and the valve means for delivering a valve position feedback signal to the first servo loop to prevent excessive valve movement; an attenuator in the second servo loop to vary the magnitude of the valve position feedback signal; and a variable decay circuit connected to the second servo loop to prevent permanent discrepancy between actual and desired chamber pressures.

Claim 7

In a pressure control device: A vacuum chamber; a pump communicating with the chamber for evacuating same; a source of gas; a pressure control valve forming a fluid coupling between the inside of the chamber and the source of gaS; actuating means connected to the valve for regulating the flow rate of gas therethrough; a first servo loop including a gauge coupled to the inside of the chamber for generating an electrical signal related to the actual chamber pressure, means for generating a setpoint signal related to the desired chamber pressure; a junction for combining the said signals producing an error signal output representing the difference between the actual and the desired chamber pressure; and a second servo loop connected between the actuating means and the first servo loop for delivering a feedback signal into the first servo loop to compensate for movement of the valve and to prevent excessive movement wherein the actuating means is driven by the error signal and the feedback signal combined; means to vary the magnitude of the feedback signal relative to the magnitude of the error signal.

Claim 8

In a pressure control device: A vacuum chamber; a pump communicating with the chamber for evacuating same; a source of gas; a pressure control valve forming a fluid coupling between the inside of the chamber and the source of gaS; actuating means connected to the valve for regulating the flow rate of gas therethrough; a first servo loop including a gauge coupled to the inside of the chamber for generating an electrical signal related to the actual chamber pressure, means for generating a setpoint signal related to the desired chamber pressure; a junction for combining the said signals producing an error signal output representing the difference between the actual and the desired chamber pressure; and a second servo loop connected between the actuating means and the first servo loop for delivering a feedback signal into the first servo loop to compensate for movement of the valve and to prevent excessive movement wherein the actuating means is driven by the error signal and the feedback signal combined; means to vary the magnitude of the feedback signal relative to the magnitude of the error signal.

Claim 9

The combination called for in claim 5 wherein the first servo loop includes a variable lead circuit to cause a larger error signal to be generated for rapid changes in chamber pressures than for slow changes in chamber pressure.

Claim 10

The combination called for in claim 5 wherein the second servo loop includes a potentiometer having an output varying in relation to the valve position.

Claim 11

The combination called for in claim 7 wherein the potentiometer has opposite ends connected to opposite terminals of a source of electricity and a wiper connected to the second servo loop; and with the addition of a variable decay circuit connected between the second servo loop and the source of electricity to prevent permanent discrepancies between the signal related to the actual chamber pressure and the setpoint signal.

Claim 12

The combination called for in claim 8 wherein the second servo loop contains an attenuator for regulating the magnitude of the feedback signal.

Claim 13

The combination called for in claim 5 wherein the actuating means is a reversible variable torque motor, the output of which varies with the magnitude of the error signal and the feedback signal combined.

Claim 14

In a control device for regulating pressure in a chamber, means for evacuating fluid from the chamber; a valve having an elongated tubular port forming a flow passage, and a tapered closure member movable through the port to vary the length and diameter of the flow passage through the port; a reversible variable torque motor; means to connect the motor to the closure member to move the closure member through said port; means in fluid communication with the inside of the chamber to generate a first signal related to the actual chamber pressure; a first servo loop to transfer the first signal to the motor; a setpoint signal generator for generating a setpoint signal which bears the same relation to the desired chamber pressure as the first signal bears to the actual chamber pressure; means operably connected to the motor to generate a feedback signal related to the flow rate of fluid through the flow passage of the valve; a second servo loop for delivering the feedback signal to the first servo loop; means connected to the second servo loop to cause the feedback signal to decay; and means to combine the first signal, the feedback signal, and the setpoint signal to produce a combined signal in the first servo loop to energize the motor.

Claim 15

In a control device for regulating pressure in a chamber, means for evacuating fluid from the chamber; a valve having an elongated tubular port forming a flow passage, and a tapered closure member movable through the port to vary the length and diameter of the flow passage through the port; a reversible variable torque motor; means to connect the motor to the closure member to move the closure member through said port; means in fluid communication with the inside of the chamber to generate a first signal related to the actual chamber pressure; a first servo loop to transfer the first signal to the motor; a setpoint signal generator for generating a setpoint signal which bears the same relation to the desired chamber pressure as the first signal bears to the actual chamber pressure; means operably connected to the motor to generate a feedback signal related to the flow rate of fluid through the flow passage of the valve; a second servo loop for delivering the feedback signal to the first servo loop; means connected to the second servo loop to cause the feedback signal to decay; and means to combine the first signal, the feedback signal, and the setpoint signal to produce a combined signal in the first servo loop to energize the motor.