Branch Flow Ratio Control for Smooth Valve Switching
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional flow rate ratio control devices experience abrupt changes and unequal flow rates when switching between branch flow paths, leading to defects in semiconductor manufacturing processes due to differences in conductance and valve performance.
Innovation Solution
A flow rate ratio control device with position sensors on fluid control valves and a storage unit to store reference positions for equal flow rate division, allowing smooth switching by normalizing valve positions and flow rates between branch paths, minimizing differential pressure and system variations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If fluid control valves are placed in fully open state and flow rate control is performed on other valves, then valve control can be performed easily, but abrupt changes (spikes) are generated in flow rates when switching branch flow paths
Solution Approach 1:
The patent applies preliminary action by pre-storing reference positions for each fluid control valve that correspond to equal flow rate conditions in a storage unit. Before switching between branch flow paths, the system retrieves these pre-calculated reference positions and uses them to gradually adjust valve openings, ensuring smooth transitions without abrupt flow rate changes. This eliminates the need for complex real-time calculations while maintaining flow rate stability during switching operations.
2Ease of operation
If fluid control valves are placed in fully open state, then valve control is simple, but flow rates in branch flow paths are not evenly divided due to different conductance
Solution Approach 1:
The patent applies parameter changes by storing reference positions for each fluid control valve that correspond to specific flow rate ratios. These reference positions are determined based on the individual conductance characteristics of each branch flow path. When control is needed, the system retrieves the appropriate reference position parameters and adjusts valve openings accordingly, achieving precise flow rate ratio control while maintaining ease of operation through simple position retrieval and adjustment.
3Device complexity
If position control is performed on fluid control valve A and flow rate control on fluid control valves B, then control is simplified, but switching point does not occur when flow rates are equal
Solution Approach 1:
The patent applies feedback by continuously monitoring the actual flow rates in each branch flow path and comparing them with target flow rate ratios. The flow rate ratio control unit receives feedback signals from flow rate detectors and adjusts the positions of fluid control valves accordingly. This closed-loop feedback mechanism ensures that switching between branch flow paths occurs precisely when flow rates are equal, improving measurement precision while maintaining relatively simple control structure through automated feedback adjustment.
Data Source
AI summary
A flow rate ratio control device smoothly switches branches without generating abrupt changes in the flow rates of a fluid flowing therethrough. The device includes at least two branches from a main flow path, first and second fluid control valves each including a position sensor for a valve body, a storage unit that stores reference positions of the valve bodies in order to divide the fluid flowing into the branches at predetermined ratios, and a control unit that controls the ratios of the branches by performing position control to place the valve body of the first valve in the reference position, and by performing flow rate control to set the flow rate of the second valve to a target flow rate. When the valve body of the second valve reaches the reference position, the control unit switches the position control and flow rate control between the valves.