Mass Flow Control Pressure Mapping for Leak-Safe Flow Convergence
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Solution Overview
Problem
In semiconductor manufacturing, maintaining the pressure on the upstream side of a mass flow controller at a limit pressure or less to prevent leakage while ensuring the flow rate converges to a reference flow rate within a predetermined time is challenging due to the limitations of conventional pressure regulation methods.
Innovation Solution
A fluid control apparatus that includes a valve, pressure sensor, flow rate sensor, reference pressure determination part, reference flow rate calculation part, and valve control part, which dynamically adjusts the pressure and flow rate to keep the upstream pressure at or below the limit pressure, using a flow rate-pressure map and PID gains to optimize convergence time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If pressure on the upstream side is kept constant at a predetermined low pressure by a pressure regulator, then safety specifications are satisfied, but the flow rate convergence time becomes longer
Solution Approach 1:
The patent applies dynamics by transitioning from static pressure regulation (constant low pressure) to dynamic pressure control (varying pressure up to limit pressure). The control unit dynamically adjusts the upstream pressure based on real-time flow rate measurements and the flow rate-pressure map, allowing pressure to vary within safe limits rather than remaining fixed, thereby reducing convergence time while maintaining safety.
Solution Approach 2:
The patent changes the pressure parameter from a fixed constant value to a variable value that can reach up to the limit pressure. By using the flow rate-pressure map to determine optimal pressure values dynamically, the system adjusts pressure parameters based on operating conditions, enabling faster flow rate convergence while ensuring pressure never exceeds the safety limit.
2Adaptability or versatility
If reference flow rate is set excessively high in the state where fluid supply is limited, then flow rate control range is improved, but convergence time becomes longer
Solution Approach 1:
The system dynamically adjusts the upstream pressure in response to the reference flow rate setting. When a high reference flow rate is set, the control unit increases the upstream pressure toward the limit pressure to provide sufficient fluid supply, enabling the system to handle excessive reference flow rates while maintaining fast convergence through active pressure regulation rather than passive limitation.
Solution Approach 2:
The patent implements feedback control by continuously measuring the actual flow rate with a flow rate sensor and comparing it to the reference flow rate. The control unit uses this feedback information along with the flow rate-pressure map to dynamically adjust pressure settings, ensuring that the system responds appropriately to high reference flow rate demands while maintaining safety and achieving convergence within the specified time.
Data Source
AI summary
In order to prevent leakage, a fluid control apparatus is adapted to include: a valve provided in the flow path through which the fluid flows; a pressure sensor provided upstream of the valve; a flow rate sensor provided downstream of the pressure sensor; a reference pressure determination part that is inputted with a measured flow rate from the flow rate sensor and on the basis of a flow rate-pressure map, determines a reference pressure corresponding to the measured flow rate; a reference flow rate calculation part that calculates a reference flow rate so that the deviation between the reference pressure and a measured pressure measured by the pressure sensor decreases; and a valve control part that controls the opening of the valve so that the deviation between the reference flow rate and the measured flow rate decreases.