Fluid Flow Rate Output Switching for Faster Valve Stabilization
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Solution Overview
Problem
Conventional fluid control devices experience unintended flow rate outputs due to pressure differences when valves are closed, leading to instability and the need for time delays to suppress these outputs, which prolong stabilization times.
Innovation Solution
A fluid control device with an actual flow rate calculation unit, a delayed flow rate calculation unit, and a flow rate output unit that compares absolute differences between calculated and delayed flow rates to output the rate closer to a reference value, enabling quick stabilization and suppressing accidental flow rates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a low-pass filter is used to suppress the unexpected flow rate output, then the flow rate stability is improved, but the response time increases and the flow rate stabilization time is extended
Solution Approach 1:
The patent applies dynamics by making the filter characteristics variable rather than fixed. The filter dynamically adjusts its time constant based on the operating state of the fluid control valve. When the valve is closing or closed, the filter time constant is increased to suppress unexpected flow rate outputs. When the valve is opening or fully open, the filter time constant is decreased to enable rapid response and quick stabilization of the flow rate output.
Solution Approach 2:
The patent changes the parameter of the filter time constant based on different operational conditions. By detecting the valve state (opening/closing) and adjusting the filter time constant accordingly, the system achieves both suppression of unexpected outputs and rapid stabilization when needed, resolving the contradiction between stability and response time.
2Ease of operation
If the fluid control valve is closed to stop flow, then the flow rate control is achieved, but pressure differences occur due to fluid resistance elements causing unexpected flow rate outputs
Solution Approach 1:
The patent introduces a filter as an intermediary between the pressure sensor measurements and the flow rate output. This filter mediates the relationship by smoothing out the pressure differences that occur when the valve is closed, preventing these transient pressure variations from being interpreted as actual flow rate changes. The filter acts as a buffer that distinguishes between real flow changes and artifacts caused by valve closure.
Solution Approach 2:
The patent applies preliminary anti-action by detecting when the valve is closing or closed and proactively adjusting the filter time constant to suppress unexpected outputs before they occur. This preemptive adjustment prevents the pressure difference artifacts from affecting the flow rate measurement accuracy.
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
The device quickly stabilizes the output flow rate by initially outputting a delayed flow rate closer to the reference value, allowing the calculated flow rate to rapidly approach and surpass it, thereby reducing unintended flow rate outputs and stabilizing the system efficiently.
Implementation Method 1
the pressure measured by the upstream pressure sensor increases by a time difference caused by the fluid resistance element
Data Source
AI summary
A fluid control device in which a fluid control valve, an upstream pressure sensor, a fluid resistance element, and a downstream pressure sensor are arranged in this order from an upstream side, includes: an actual flow rate calculation unit that calculates a flow rate on basis of pressures measured by the upstream pressure sensor and the downstream pressure sensor; a delayed flow rate calculation unit that calculates a delayed flow rate by generating a response delay in the calculated flow rate calculated by the actual flow rate calculation unit; and a flow rate output unit that compares an absolute difference between a predetermined reference value and the calculated flow rate and an absolute difference between the reference value and the delayed flow rate, and outputs the calculated flow rate or the delayed flow rate having a smaller absolute difference.