Liquid flow controller and precision dispense apparatus and system

A fluid flow control apparatus, comprising:

• a proportional flow valve having a fluid inlet and a fluid outlet;
• a pneumatic proportional control valve in communication with said proportional flow valve for modulating said proportional flow valve;
• a frictional flow element having a frictional flow element fluid inlet in fluid communication with said fluid outlet of said proportional flow valve and having a frictional flow element fluid outlet spaced from said frictional flow element fluid inlet, said frictional flow element creating a pressure drop between said frictional flow element fluid inlet and frictional flow element fluid outlet;
• an upstream pressure sensor;
• a downstream pressure sensor;
• a controller in communication with said upstream pressure sensor, said downstream pressure sensor and said pneumatic proportional control valve, said controller further comprising:
• one or more processors;
• a computer readable memory;
• and a set of computer readable instructions stored on said computer readable memory and executable by the one or more processors, the set of computer readable instructions comprising instructions executable to:
• receive an upstream pressure signal receive a downstream pressure signal;
• calculate an error signal;
• calculate a valve control signal based on the upstream pressure signal, downstream pressure signal and error signal, wherein the computer readable instructions further comprise instructions that are executable to:
• maintain one or more valve gain curves in memory;
• determine a valve gain for a particular valve based on the valve gain curve associated with that valve;
• and account for the valve gain when calculating the valve control signal.

A fluid flow control apparatus, comprising:

• a proportional flow valve having a fluid inlet and a fluid outlet;
• a pneumatic proportional control valve in communication with said proportional flow valve for modulating said proportional flow valve;
• a frictional flow element having a frictional flow element fluid inlet in fluid communication with said fluid outlet of said proportional flow valve and having a frictional flow element fluid outlet spaced from said frictional flow element fluid inlet, said frictional flow element creating a pressure drop between said frictional flow element fluid inlet and frictional flow element fluid outlet;
• an upstream pressure sensor;
• a downstream pressure sensor;
• a controller in communication with said upstream pressure sensor, said downstream pressure sensor and said pneumatic proportional control valve, said controller further comprising:
• one or more processors;
• a computer readable memory;
• and a set of computer readable instructions stored on said computer readable memory and executable by the one or more processors, the set of computer readable instructions comprising instructions executable to:
• receive an upstream pressure signal receive a downstream pressure signal;
• calculate an error signal;
• calculate a valve control signal based on the upstream pressure signal, downstream pressure signal and error signal, wherein the computer readable instructions further comprise instructions executable to adaptively adjust the valve control signal based on a set of past position values.

A device comprising a set of computer readable instructions stored on a computer readable memory and executable by one or more processors, the set of computer readable instructions comprising instructions executable to:

• receive an upstream pressure signal, receive a downstream pressure signal;
• calculate an error signal;
• determine a valve gain for a particular valve based on a valve gain curve associated with that valve, wherein the valve gain varies according to the position of the particular valve;
• calculate a valve control signal based on the upstream pressure signal, downstream pressure signal, error signal and valve gain.

A device comprising a set of computer readable instructions stored on a computer readable memory and executable by one or more processors, the set of computer readable instructions comprising instructions executable to:

• receive an upstream pressure signal receive a downstream pressure signal;
• calculate an error signal based on proportional, integral and derivative values for the upstream pressure signal and downstream pressure signal;
• add an error gain to the error signal;
• determine a valve gain for a particular valve based on a valve gain curve associated with that valve, wherein the valve gain varies according to the position of the particular valve;
• calculate a valve control signal based on the upstream pressure signal, downstream pressure signal, error signal and valve gain;
• adaptively adjust the valve control signal based on a set of past position values.