Fluid Control Valve Stabilization During State Transitions
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Solution Overview
Problem
Existing fluid control units experience peak generation in measured flow rates due to noise fluctuations when transitioning from a stable to a transitional state, caused by inappropriate setting of control coefficients that result in unexpected changes in valve aperture.
Innovation Solution
A fluid control unit with a flow rate measurement part, a fluid control valve, and a valve aperture operation amount output part, where the control coefficients for the transitional state are set to moderate valve aperture fluctuations more than in the stable state, and a valve aperture operation amount for switching time is calculated based on stable state outputs to stabilize the valve aperture during transitions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the control coefficient gain is set to be small in the transitional state to restrain overshoot or undershoot, then the valve aperture fluctuation is moderated, but the applied voltage does not quickly return after noise fluctuation occurs at state switching
Solution Approach 1:
The patent applies dynamics by making the control coefficient adaptive rather than fixed. The control coefficient is dynamically adjusted based on the system state (stable or transitional) and noise detection. In the transitional state, if noise is detected, the control coefficient is further reduced to prioritize stability over response speed, whereas without noise the normal transitional coefficient is used for faster response.
Solution Approach 2:
The patent changes the parameter of control coefficient gain based on operating conditions. Different control coefficients are set for stable state and transitional state, and within the transitional state, the coefficient is further adjusted based on noise detection. This parameter adaptation resolves the contradiction by optimizing the gain for each specific condition.
2Speed
If the control coefficient gain is set to be big in the stable state to quickly return after noise fluctuation, then the applied voltage response is fast, but the valve aperture operation amount fluctuates excessively in the transitional state
Solution Approach 1:
The control system dynamically switches between different control coefficients based on the detected state (stable or transitional). In the stable state, a bigger control coefficient is used for fast response to noise fluctuations. In the transitional state, a smaller control coefficient is used to prevent excessive valve aperture changes, thus resolving the contradiction through state-dependent parameter adjustment.
Solution Approach 2:
The patent implements parameter changes by setting different control coefficient values for different operating states. The control coefficient is changed from a larger value in stable state to a smaller value in transitional state, allowing the system to optimize between response speed and stability according to the current operational phase.
3Reliability
If the control coefficient is set to moderate the valve aperture operation amount in the transitional state, then overshoot or undershoot is restrained, but peak generation occurs in the measured flow rate due to unexpected valve aperture changes
Solution Approach 1:
The patent uses feedback by detecting noise in the applied voltage and adjusting the control coefficient accordingly. When noise is detected during state transition, the system provides feedback to further reduce the control coefficient, preventing the valve aperture from changing unexpectedly and thus avoiding peak generation in the measured flow rate while still restraining overshoot or undershoot.
Solution Approach 2:
The patent applies beforehand cushioning by detecting noise before it causes significant valve aperture changes. When noise is detected in the applied voltage during state transition, the control coefficient is proactively reduced to cushion against potential excessive valve aperture changes, preventing peak generation before it occurs.
Data Source
AI summary
In order to restrain generation of a peak in the measured flow rate, a fluid control unit measures a flow rate of a fluid in a channel and outputs a signal indicating a valve operation amount of a fluid control valve obtained based on a deviation between a preset flow rate and a measured flow rate and a control coefficient, and the control coefficient for a stable state and the control coefficient for a transitional state are so set to moderate fluctuation of the valve operation amount to the deviation more in the transitional state than in the stable state. At or shortly after a timing when the stable state is switched to the transitional state, a signal is output that indicates an operation amount for a switching time calculated based on each of the operation amounts output at a plurality of timings in the stable state.