Control valve positioners having improved operating characteristics
AssigneeFisher Controls International LLC
InventorHans D. Baumann
Life of this patent
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Abstract
A control assembly includes a positioner/actuator and a control valve. The positioner/actuator includes a valve actuator and a positioner for controlling actuator position and speed in response to a control signal. The control valve has a characteristic flow rate as a function of time. The positioner may include an electronic control circuit for modifying the travel speed of the actuator to produce a desired flow rate as a function of time. The positioner may determine an error between a desired actuator position and an actual actuator position and apply a correction signal to reduce the error. The correction signal is asymmetric with respect to error polarity.
Claims17
A control valve assembly comprising:
- a positioner/actuator comprising a valve actuator having an actuator position and a positioner for controlling said actuator position;
- and
- a control valve having a characteristic fluid flow rate passing through it as a function of time in response to a travel speed of said actuator, said positioner including an electronic control circuit for modifying the travel speed of said actuator as a function of time to produce a desired rate of change in fluid flow through the valve as a function of time in response to a specified control signal.
A control valve assembly comprising:
- a positioner/actuator comprising a valve actuator having an actuator position and a positioner for controlling said actuator position in response to a control signal;
- and
- a control valve having a characteristic fluid flow rate as a function of said actuator position, said positioner comprising means for determining an error between a desired actuator position and an actual actuator position and means responsive to said error for applying a correction signal to said actuator to reduce said error, said correction signal having a first characteristic determining an actuator speed when said error is positive and a second characteristic determining the actuator speed when said error is negative, wherein the first and second characteristics of said correction signal are different.
A control valve assembly comprising:
- a positioner/actuator comprising a valve actuator and a positioner for controlling actuator position and speed in response to a control signal;
- and
- a control valve having a characteristic fluid flow rate passing through it as a function of said control signal, said positioner including an electronic control circuit for modifying the travel speed of said actuator as a function of said control signal to produce a desired rate of change in fluid flow through the valve as a function of time.
A control valve assembly comprising:
- a positioner/actuator comprising a valve actuator and a positioner for controlling actuator position in response to a control signal;
- and
- a control valve having a characteristic flow rate as a function of said actuator position, said positioner comprising means for determining an error between a desired actuator position and an actual actuator position and means responsive to said error for applying a correction signal determining an actuator speed to said actuator to reduce said error, said correction signal being asymmetric with respect to polarity of said error.
In a control valve assembly comprising a positioner/actuator including a valve actuator and a positioner for controlling actuator position and actuator speed in response to a control signal, and a control valve, a method for positioning said control valve comprising the step of:
- modifying the travel speed of said actuator as a function of said control signal to produce a desired rate of change in fluid flow through the valve as a function of time.
In a control valve assembly comprising a positioner/actuator including a valve actuator and a positioner for controlling actuator position in response to a control signal, and a control valve, a method for positioning said control valve comprising the steps of:
- determining an error between a desired actuator position and an actual actuator position;
- generating a correction signal to reduce said error, said correction signal determining an actuator speed and being an asymmetric function of error polarity;
- and
- applying said correction signal to said actuator.
Dependencies are inferred from the claim text.