Flow Rate Control Apparatus with 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, especially with pressure type flow rate control systems where control range narrows with rising orifice secondary side pressure, affecting semiconductor product quality.
Innovation Solution
A flow rate range variable type control apparatus that uses multiple orifices with different flow rate characteristics arranged in parallel and switching valves to control fluid passages, allowing for accurate flow rate control across a wide range by switching between small, medium, and large flow quantity ranges, and employing thermal type mass flow rate control for temperature-based detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a single pressure type flow rate control apparatus is used, then the structure is simple and manufacturing costs are low, but the control range narrows when orifice secondary side pressure rises
Solution Approach 1:
The flow rate control apparatus is segmented into multiple control regions by dividing the orifice secondary side pressure range into first, second, and third regions. Different control methods are applied to each region: critical flow rate control for the first region, differential pressure control for the second region, and direct flow rate control for the third region. This segmentation allows the single apparatus to maintain accurate control across a wide overall range despite the limitations of individual control methods.
Solution Approach 2:
The apparatus dynamically switches between different control methods based on the current orifice secondary side pressure. The control mode is automatically adjusted as pressure transitions between regions, enabling the system to adapt its control strategy to maintain accuracy across varying operating conditions rather than being fixed in a single control mode.
2Manufacturing precision
If multiple flow rate control apparatuses with different ranges are provided in parallel, then high control accuracy is maintained over wide range, but installation costs go up and switching operations become time-consuming
Solution Approach 1:
The flow rate control apparatus is designed with multi-functionality to perform multiple control tasks within a single device. It can operate in critical flow rate control mode, differential pressure control mode, and direct flow rate control mode, effectively replacing what would traditionally require multiple specialized apparatuses. This universal design maintains control accuracy across the entire range while eliminating the need for multiple separate devices and their associated switching operations.
Solution Approach 2:
The patent merges multiple control functions and methods into a single integrated apparatus. By combining critical flow rate control, differential pressure control, and direct flow rate control capabilities in one device with unified control logic, it eliminates the need for parallel installation of multiple apparatuses and manual switching operations, thereby reducing installation costs and operational complexity while maintaining accuracy.
3Reliability
If pressure type flow rate control is used, then responsiveness and control stability are excellent, but control accuracy degrades in low flow rate situations when control range is expanded
Solution Approach 1:
The control approach changes parameters based on operating conditions. When orifice secondary side pressure is low (first region), critical flow rate control is used which maintains good stability. When pressure rises (second and third regions), the system transitions to differential pressure control and then direct flow rate control, which are better suited for maintaining accuracy at higher pressures and lower flow rates. This parameter adaptation allows the system to maintain both stability and accuracy across the full range.
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 by automatic range selection, and reduces manufacturing costs by using a single apparatus for various fluid supply facilities.
Implementation Method 1
thermal type mass flow rate control apparatus
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.