Flow Rate Valve Control for Overshoot and Hunching Suppression
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Solution Overview
Problem
Conventional flow rate adjusting devices experience overshoot and hunching phenomena when the back pressure is excessively lower or higher relative to the supply pressure, leading to inconsistent measured flow rates that fail to converge to the set value.
Innovation Solution
A flow rate adjusting device with a flow metering portion, adjusting portion, and control unit that detects flow rate fluctuations and adjusts the valve body motion based on the difference between measured and set flow rates, using different motion amounts to stabilize the flow rate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the valve body is moved by a large motion amount to quickly adjust the flow rate, then the response speed is improved, but the flow rate fluctuation and overshoot increase
Solution Approach 1:
The patent applies dynamics by making the motion amount of the valve body variable rather than fixed. The control unit dynamically adjusts the motion amount based on the detected flow rate fluctuation state, using larger motion amounts when flow rate is stable and smaller motion amounts when fluctuation is detected, thereby achieving both fast response and flow rate stability
Solution Approach 2:
The patent implements feedback control by detecting the flow rate fluctuation state and using this information to adjust subsequent valve body motion. The control unit continuously monitors whether flow rate fluctuation is present and modifies the motion amount accordingly, creating a closed-loop control system that prevents overshoot while maintaining response speed
2Stability of the object's composition
If the valve body is moved by a small motion amount to reduce flow rate fluctuation, then the flow rate stability is improved, but the response speed decreases
Solution Approach 1:
The patent makes the motion amount dynamic by adjusting it based on the flow rate fluctuation state. When no fluctuation is detected, larger motion amounts are used for faster response. When fluctuation is detected, smaller motion amounts are used to stabilize flow rate, thus optimizing both response speed and stability at different control stages
3Stress or pressure
If the back pressure is excessively lower or higher relative to the supply pressure, then the pressure difference is increased, but the flow rate convergence to set value is deteriorated
Solution Approach 1:
The patent uses feedback control to detect when flow rate fluctuation occurs due to excessive pressure difference and adjusts the valve body motion amount accordingly. By monitoring the flow rate and comparing it to the set value, the system identifies fluctuation states and modifies control parameters to achieve convergence even under large pressure differences
Solution Approach 2:
The patent changes the control parameter (motion amount of valve body) based on the detected flow rate fluctuation state. When fluctuation is detected, the motion amount parameter is reduced to prevent overshoot and hunching, allowing the system to maintain flow rate precision despite large pressure differences between supply and back pressure
Data Source
AI summary
Provided is a flow rate adjusting device including: an ultrasonic flow metering portion; a flow rate adjusting portion; a flow rate setting unit; a flow rate fluctuation state detecting unit configured to detect a flow rate fluctuation state where a first flow rate state where a measured flow rate value is higher by at least a first threshold than the set flow rate value and a second flow rate state where the measured flow rate value is lower by at least a second threshold than the set flow rate value occur; and a control device. The control device controls the flow rate adjusting portion to move the valve body by a first motion amount when no flow rate fluctuation state is detected and controls flow rate adjusting portion to move the valve body by a second motion amount less than first motion amount when flow rate fluctuation state is detected.