Pressure-Type Flow Control Device Preventing Overshoot
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Solution Overview
Problem
Conventional pressure-type flow control devices experience overshoot during flow control startup due to increased internal fluid channel pressure from minute gas leakage, which affects the accuracy of pulse flow control.
Innovation Solution
Incorporating a vent line on the orifice upstream side to evacuate gas before flow control initiation, reducing downstream pressure and preventing overshoot by using a pressure control valve and an exhaust valve to forcibly exhaust gas from the fluid channel.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If an on/off valve is provided on the orifice downstream side to enable pulse flow control, then flow control flexibility is improved, but internal pressure increases due to minute gas leakage causing overshoot at flow control startup
Solution Approach 1:
The exhaust valve performs preliminary evacuation of the fluid channel before the on/off valve initiates pulse flow control. This preliminary action removes accumulated gas that would otherwise cause pressure buildup and overshoot, enabling accurate flow control while maintaining pulse capability
Solution Approach 2:
The exhaust valve acts as an intermediary component between the pressure control valve and the on/off valve. It mediates the pressure buildup issue by providing a dedicated exhaust path, allowing the on/off valve to perform pulse control without suffering from gas leakage accumulation
2Manufacturing precision
If the fluid channel internal pressure is reduced by evacuating gas before flow control, then overshoot is prevented, but device complexity increases due to additional exhaust channel and valve
Solution Approach 1:
The exhaust valve shares the same valve body and actuation mechanism as other control valves in the system. It utilizes the existing valve infrastructure and control system, adding minimal complexity while providing the essential exhaust function to prevent overshoot
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
This solution enhances control responsiveness and reduces step-up and step-down times, improving flow regulation and gas replaceability, while allowing for downsized devices with improved pulse flow control accuracy.
Implementation Method 1
gas is previously evacuated through an exhaust channel before the start of flow control to reduce the pressure on the orifice downstream side
Implementation Method 2
a pressure control valve fixed to the fluid inlet side of the main body for opening or closing the upstream side of the fluid channel
Implementation Method 3
an on/off valve for opening or closing the fluid channel on the downstream side of the first pressure sensor
Data Source
AI summary
The pressure-type flow control device includes: a main body provided with a fluid channel communicating between a fluid inlet and a fluid outlet and an exhaust channel communicating between the fluid channel and an exhaust outlet; a pressure control valve fixed to a fluid inlet side of the main body for opening or closing the upstream side of the fluid channel; a first pressure sensor for detecting the internal pressure of the fluid channel on the downstream side of the control valve; an orifice provided in the fluid channel on the downstream side of the point of branching of the exhaust channel; an on/off valve for opening or closing the fluid channel on the downstream side of the first pressure sensor; and an exhaust valve for opening or closing the exhaust channel.