System and method for a mass flow controller
AssigneeCelerity, Inc.
InventorsJohn M. Lull, Chiun Wang, William S. Valentine, Joseph A. Saggio, Jr.
Life of this patent
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Abstract
A system and method for controlling a mass flow controller to have a constant control loop gain under a variety of different types of fluids and operating conditions, and for configuring the mass flow controller for operation with a fluid and/or operating conditions different from that used during a production of the mass flow controller. Further, the system and method includes providing control by reducing the effects of hysteresis in solenoid actuated devices by providing a non-operational signal to the solenoid actuated device.
Claims36
A mass flow controller having a control loop, the mass flow controller comprising:
- a flow meter adapted to sense fluid flow in a fluid flow path and provide a flow signal indicative of the mass flow rate in the flow path;
- a controller coupled to the flow meter and adapted to provide a drive signal based at least in part on the flow signal;
- a valve actuator adapted to receive the drive signal from the controller;
- and
- a valve adapted to be controlled by the valve actuator and coupled to the fluid flow path;
- wherein the control loop of the mass flow controller includes the flow meter, the controller, the valve actuator, and the valve each having a respective gain term;
- wherein the control loop has an overall gain term that includes each of the respective gain terms, and
- wherein the mass flow controller is adapted to maintain the overall gain term at a substantially constant value independent of changes in one or more of the respective gain terms.
A method of controlling a gain of a control loop of a mass flow controller, the mass flow controller including a flow meter adapted to sense fluid flow in a fluid flow path and provide a flow signal indicative of the mass flow rate in the flow path, a controller coupled to the flow meter and adapted to provide a drive signal based at least in part on the flow signal, a valve actuator adapted to receive the drive signal from the controller, and a valve adapted to be controlled by the valve actuator and coupled to the fluid flow path, the method comprising an act of:
- maintaining an overall gain term of the control loop at a substantially constant value independent of changes in one or more of a plurality of gain terms,
- wherein the plurality of gain terms includes a flow meter gain term, a controller gain term, a valve actuator gain term, and a valve gain term.
Dependencies are inferred from the claim text.