Flow Rate Control Apparatus Using Parallel Orifices for Wide Range Accuracy
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Solution Overview
Problem
Conventional flow rate control apparatuses face challenges in maintaining high accuracy over a wide range, leading to increased manufacturing costs and complexity due to the need for multiple apparatuses with different flow rate ranges, and the pressure type flow rate control apparatus experiences a narrowing of its control range with rising orifice secondary side pressure, causing unevenness in semiconductor product quality.
Innovation Solution
A flow rate range variable type control apparatus that switches fluid passages and detection levels for small and large flow quantities, using multiple orifices in parallel with switching valves to achieve accurate control across a wide range, and incorporates thermal type mass flow rate control for temperature-based detection and adjustment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple flow rate control apparatuses with different flow rate ranges are provided in parallel, then high flow rate control accuracy can be maintained over a wide flow rate control range, but installation costs go up and switching operations become time-consuming
Solution Approach 1:
The flow rate control apparatus is segmented into multiple flow rate areas (large, medium, small) with dedicated control circuits for each area. Each control circuit is responsible for a specific flow rate range, allowing high precision control within each segment while maintaining a wide overall control range through the segmented architecture.
Solution Approach 2:
A single flow rate control apparatus is designed to perform multiple functions by incorporating control circuits for different flow rate areas within one device. The apparatus can automatically switch between different control ranges, eliminating the need for multiple separate apparatuses while maintaining high accuracy across the entire flow rate spectrum.
2Measurement precision
If three sets of flow rate control apparatuses are provided in parallel for different flow rate areas, then high flow rate control accuracy can be maintained, but installation costs unavoidably go up
Solution Approach 1:
Multiple control circuits for different flow rate areas (large, medium, small) are merged into a single integrated flow rate control apparatus. This consolidation reduces the total number of devices needed from three separate apparatuses to one, thereby reducing installation costs while maintaining high accuracy through the combined functionality of all control circuits.
Solution Approach 2:
The flow rate control apparatus is designed as a universal device that can handle all flow rate areas (large, medium, and small) within a single system. By making the apparatus multi-functional, it eliminates the need for multiple specialized devices, reducing installation costs while maintaining high precision control across the entire flow rate range.
3Device complexity
If a pressure type flow rate control apparatus is used, then structure is simple and responsiveness is excellent, but control range becomes narrower as orifice secondary side pressure rises
Solution Approach 1:
The flow rate control apparatus dynamically adapts its control characteristics by switching between different control circuits based on the required flow rate area. This dynamic capability allows the simple pressure-type structure to maintain its responsiveness while expanding its effective control range to cover large, medium, and small flow rate areas through automatic circuit selection.
Solution Approach 2:
The control apparatus changes its operational parameters by switching between different control circuits designed for different flow rate areas. This parameter change capability allows the pressure-type apparatus to maintain its structural simplicity and responsiveness while achieving a wider control range by adjusting which control circuit is active based on the desired flow rate.
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 highly accurate flow rate control with less than 1% error across a wide range, simplifies operations, and reduces manufacturing costs by using a single apparatus setup, while maintaining responsiveness and control stability.
Implementation Method 1
incorporates thermal type mass flow rate control for temperature-based detection and adjustment
Implementation Method 2
pressure type flow rate control apparatus experiences a narrowing of its control range with rising orifice secondary side pressure
Data Source
AI summary
A pressure type flow rate control apparatus is provided wherein flow rate of fluid passing through an orifice is computed as Qc=KP1 (where K is a proportionality constant) or as Qc=KP2m (P1−P2)n (where K is a proportionality constant, m and n constants) by using orifice upstream side pressure P1 and/or orifice downstream side pressure P2. A fluid passage between the downstream side of a control valve and a fluid supply pipe of the pressure type flow rate control apparatus comprises at least 2 fluid passages in parallel, and orifices having different flow rate characteristics are provided for each of these fluid passages, wherein fluid in a small flow quantity area flows to one orifice for flow control of fluid in the small flow quantity area, while fluid in a large flow quantity area flows to the other orifice for flow control of fluid in the large flow quantity area.