Pulse Flow Valve Control Using Integral Flow Feedback
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Solution Overview
Problem
Conventional flow rate control devices, particularly those using piezoelectric element-driven valves, struggle with high-speed pulsed flow rate control due to limitations in valve response speed and variability in responsivity, leading to deviations between set and actual flow rates during pulse-shaped signal control.
Innovation Solution
A flow rate control device with a control valve, a flow rate measurement unit, and a controller that calculates and compares measurement integral flow rates to target integral flow rates, using a valve operation control unit to adjust the control valve's opening/closing based on the comparison, ensuring accurate pulsed flow rate control by matching the measurement integral flow rate to the target integral flow rate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a piezoelectric element driven valve is used for flow rate control, then the valve can be opened/closed by controlling the applied voltage, but the response speed of opening/closing is limited and cannot meet high-speed pulsed flow rate control requirements
Solution Approach 1:
The controller calculates the measurement integral flow rate in advance and compares it with the target integral flow rate before the pulse signal ends. Based on this preliminary comparison, the controller determines whether to extend the valve opening time beyond the original pulse duration, ensuring the total integral flow rate matches the target value even when valve response speed is limited
Solution Approach 2:
The system continuously measures the actual integral flow rate using the flow rate measurement unit and feeds this information back to the controller. The controller compares the feedback measurement integral flow rate with the target integral flow rate and adjusts the valve opening time accordingly, creating a closed-loop control system that compensates for slow valve response
2Speed
If the valve is opened/closed quickly to meet pulsed flow rate control, then the response speed improves, but deviation between set flow rate and actual flow rate increases
Solution Approach 1:
The flow rate measurement unit continuously monitors the actual flow rate and feeds this information back to the controller. The controller compares the measurement integral flow rate with the target integral flow rate and adjusts the valve operation to eliminate deviations, ensuring accurate flow rate control even during rapid opening/closing operations
Solution Approach 2:
The controller performs preliminary calculation of the measurement integral flow rate and compares it with the target value before the pulse signal concludes. This allows the controller to predict and compensate for potential deviations between set and actual flow rates by adjusting the valve opening time accordingly
3Device complexity
If conventional flow rate control is used, then the device structure is simple, but the control accuracy during pulsed flow rate varies from device to device
Solution Approach 1:
The system incorporates a flow rate measurement unit that continuously measures the actual flow rate and feeds this information back to the controller. This feedback mechanism compensates for device-to-device variations in responsivity, allowing each device to achieve stable and accurate pulse flow rate control without requiring complex hardware modifications
Solution Approach 2:
Each flow rate control device uses its own measured flow rate data to automatically adjust its valve operation timing. The controller calculates the measurement integral flow rate based on actual measurements and autonomously determines the optimal valve opening time, enabling each device to self-correct for its specific responsivity characteristics
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enables appropriate gas supply during pulsed flow rate control by stabilizing the pulse flow rate and ensuring the desired gas volume is delivered, even with varying device responsivity, by precisely controlling the valve's opening and closing operations.
Implementation Method 1
a piezoelectric element-driven valve for opening/closing a diaphragm valve element by a piezo actuator
Data Source
AI summary
A flow rate control device 100 includes a control valve 6 provided in a flow path 1, a flow rate measurement unit 2, 3 for measuring fluid flow rate controlled by the control valve 6, and a controller 7. The controller 7 is configured so as to control the opening/closing operation of the control valve 6 to match the measurement integral flow rate based on the signal outputted from the flow rate measurement unit (Vn+Vd) to the target integral flow rate Vs.