Piezoelectric Flow Control Valve with Preliminary Voltage Spike
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Solution Overview
Problem
Piezo actuators in flow control systems for semiconductor manufacturing and other applications exhibit slow displacement responses due to high capacitance, leading to delayed flow changes and overshoot when trying to quicken the response, which deteriorates product quality.
Innovation Solution
A flow control apparatus and program that utilize a piezoelectric element coupled with a valve, a driving circuit, and an output means to apply a voltage signal with a spike-like or step-like change when the flow regulating valve is closed, compensating for the response delay by generating a signal based on the deviation from the target flow and electrical characteristics of the piezoelectric element, allowing for quick response control without overshoot.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the initial voltage is increased to quicken the response, then the response speed is improved, but overshoot occurs and product quality deteriorates
Solution Approach 1:
The system applies a preliminary voltage (higher than the steady-state voltage) to the piezoelectric element before the actual flow change is needed. This preliminary action pre-charges the capacitor and positions the valve closer to the desired state, enabling faster response when the target flow changes without causing overshoot during normal operation.
Solution Approach 2:
The system dynamically changes the voltage parameter applied to the piezoelectric element based on the operational state. When the valve is closed, a higher preliminary voltage is applied to prepare for quick opening. When the valve is already open, normal voltage control is maintained to prevent overshoot. This parameter change strategy allows fast response when needed while maintaining precision during steady operation.
2Device complexity
If conventional PI control or digital arithmetic compensation is used, then the control system is simple, but the flow response remains delayed due to piezoelectric element capacitance
Solution Approach 1:
The control system performs preliminary voltage application to the piezoelectric element when the valve is in the closed state, preparing the actuator for rapid response. This preliminary charging of the capacitor reduces the time constant effect, enabling faster flow response without requiring complex control algorithms or additional hardware components.
Solution Approach 2:
The control system dynamically adjusts the voltage applied to the piezoelectric element based on the valve's operational state. When closed, a higher preliminary voltage is applied to accelerate the opening response. This dynamic parameter adjustment compensates for the capacitive delay without increasing device complexity or requiring sophisticated control algorithms.
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
The solution enables rapid and precise control of fluid flow without overshoot, improving manufacturing efficiency by reducing response delays and maintaining product quality.
Implementation Method 1
a piezoelectric element that is coupled to a valve element configuring a flow regulating valve and that works the valve element to regulate a flow
Data Source
AI summary
A flow control apparatus and a program are disclosed herein. A flow control apparatus includes a piezoelectric element coupled to a valve element configuring a flow regulating valve and that works the valve element to regulate a flow, a driving circuit that applies a voltage to the piezoelectric element to drive the piezoelectric element, an accepting means for accepting a target flow, and an output means for outputting a signal corresponding to the voltage applied to the piezoelectric element to the driving circuit, to change the flow so as to coincide with the target flow. When the target flow is changed, the output means transiently outputs a signal corresponding to a voltage value different from a target voltage value corresponding to the target flow after the change, and then the output means outputs a signal corresponding to a voltage change converging at the target voltage value.