Fluid Control Valve Calibration Using Thermal Valve Opening Adjustment
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Solution Overview
Problem
Existing fluid control devices in semiconductor manufacturing face challenges in accurately controlling fluid flow rates due to temperature-induced deviations in position sensor output values, requiring reassembly and stepwise adjustments, which limits detailed calibration data acquisition.
Innovation Solution
A calibration data generation apparatus that includes a flow rate sensor, differential pressure control mechanism, temperature control mechanism, and control unit to maintain fluid flow at sound velocity, allowing for temperature changes and non-stepwise valve opening adjustments to generate detailed calibration data without reassembling the fluid control valve.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a shim is interposed between the valve seat and the valve closure member to keep the valve opening constant, then the valve opening can be maintained, but reassembly of the fluid control valve is required every time the shim is replaced
Solution Approach 1:
The invention extracts the calibration function from the mechanical assembly process. By using a temperature control mechanism to heat the valve body and allowing the valve closure member to expand thermally, the valve opening is adjusted without requiring physical shims or reassembly. The calibration data is generated by measuring sensor outputs at different temperatures, separating the calibration process from the mechanical structure.
Solution Approach 2:
The invention changes the physical state of the valve components by controlling temperature. By heating the valve body to a predetermined temperature, the valve closure member expands thermally, changing the valve opening. This allows continuous adjustment of the valve opening parameter without mechanical intervention, enabling detailed calibration data acquisition.
2Measurement precision
If the valve opening is adjusted using the shim, then the valve opening can be maintained constant, but the valve opening can be adjusted only stepwise
Solution Approach 1:
The invention uses temperature as a continuous control parameter to adjust the valve opening. By controlling the temperature of the valve body, the valve closure member expands or contracts continuously, providing fine-grained adjustment of the valve opening. This eliminates the stepwise limitation of shim-based adjustment and enables detailed calibration data to be acquired across a continuous range of valve openings.
Solution Approach 2:
The invention replaces the mechanical shim-based adjustment system with a thermal expansion mechanism. Instead of physically inserting shims of different thicknesses, the system uses controlled heating to induce thermal expansion of the valve closure member, achieving continuous valve opening adjustment without mechanical intervention.
3Temperature
If the temperature of the fluid flowing through the fluid control valve becomes high, then the position sensor output value deviates from the actual valve opening, but the deviation becomes significant
Solution Approach 1:
The invention performs preliminary calibration at elevated temperatures before actual operation. By heating the valve body to the predetermined temperature and acquiring sensor output values at this state, the system pre-compensates for thermal expansion effects. This preliminary calibration ensures that subsequent position sensor readings remain accurate even when the valve operates at high temperatures.
Solution Approach 2:
The invention changes the calibration temperature parameter to match the operating temperature. Instead of calibrating at room temperature and expecting accurate readings at high temperatures, the system performs calibration at the actual operating temperature, ensuring that the relationship between sensor output and valve opening is accurate under real operating conditions.
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 accurate calibration data generation for position sensors, accounting for thermal effects on both the sensor and valve components, allowing for precise flow rate control and valve opening adjustments, thus improving the accuracy and detail of calibration data without the need for reassembly.
Implementation Method 1
when the temperature of the fluid flowing through the fluid control valve becomes high, respective members constituting the fluid control valve are deformed due to the effect of heat
Implementation Method 2
using an eddy current sensor adapted to detect the relative position of the valve closure member to the valve seat of the fluid control valve
Implementation Method 3
controls the differential pressure between the upstream and downstream sides of the fluid control valve; in a state where the differential pressure control mechanism controls the differential pressure so that the fluid passing through the fluid control valve has sound velocity
Data Source
AI summary
A calibration data generation apparatus includes a flow rate sensor that measures the flow rate of a fluid flowing through a fluid control valve; a differential pressure control mechanism; a temperature control mechanism; and a control unit that when the fluid passing has sound velocity, uses the temperature control mechanism to change the temperature from a reference temperature to comparative temperature. In addition, the control unit includes a valve opening control part that controls the fluid control valve so that at the comparative temperature, an output value outputted from one of the position sensor and the flow rate sensor becomes equal to the reference output value of the one; and a calibration data generation part that generates the calibration data on the basis of a calibration data generation output value outputted from the other one of the position sensor and the flow rate sensor.