Liquid Supply Valve Timing to Prevent Flowmeter Pressure Errors
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Solution Overview
Problem
Downsizing liquid supply apparatuses leads to increased internal pressure in piping, causing measurement value upper limit errors in sensors such as flowmeters and pressure gauges due to the reduced distance and volume between components.
Innovation Solution
Incorporating a control device that introduces a delay time between the open/closed switchover times of valves connected to a flow controller, thereby controlling the supply of liquids to prevent abrupt pressure and flow rate increases in the piping, which helps in suppressing measurement value upper limit errors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the liquid supply apparatus is downsized by shortening the distance between components (valve, pressure gauge, flow control valve), then the apparatus size is reduced, but the internal pressure in the piping increases causing measurement value upper limit errors in sensors
Solution Approach 1:
The control device switches the first valve before switching the second valve, creating a time sequence that prevents simultaneous opening of both valves. This preliminary action on the first valve avoids the pressure surge that would occur if both valves opened simultaneously in a downsized apparatus with limited piping volume.
Solution Approach 2:
The valve switching operations are performed in a periodic sequence rather than simultaneously. The control device implements a time-based control strategy where the first valve switches at time t1 and the second valve switches at time t2, creating a periodic switching pattern that manages pressure fluctuations in the downsized apparatus.
2Length of stationary object
If the distance between components is shortened to downsize the apparatus, then the apparatus becomes more compact, but abrupt pressure and flow rate increases occur in the piping
Solution Approach 1:
The first valve is switched before the second valve, creating a preliminary action that allows the system to adjust to the first change before the second change occurs. This sequential approach prevents abrupt pressure increases that would result from simultaneous valve switching in a compact apparatus with short piping distances.
Solution Approach 2:
The control device acts as an intermediary that mediates between the two valve switching operations. It introduces a time delay between the switching of the first and second valves, effectively managing the pressure transition in the piping system and preventing abrupt pressure spikes.
3Productivity
If simultaneous valve switching is performed, then the control process is simple and fast, but measurement value upper limit errors occur due to pressure increases
Solution Approach 1:
The valve switching is performed in a periodic sequence with defined time intervals. The control device switches the first valve at time t1 and the second valve at time t2, creating a periodic switching pattern that maintains reliability by preventing pressure surges while still achieving efficient control.
Solution Approach 2:
The control device monitors the switching state of both valves and adjusts the timing accordingly. By implementing feedback control on the valve switching timing, the system ensures that the first valve is switched before the second valve, preventing measurement errors while maintaining efficient operation.
Data Source
AI summary
There is provided an apparatus for supplying liquid, comprising a flow controller configured to measure a flow rate of a liquid and control the flow rate based on a measurement value; a first valve connected with the flow controller to control supply of a first liquid to the flow controller; a second valve connected with the flow controller to control supply of a second liquid to the flow controller; and a control device configured to control the first valve and the second valve, wherein the control device switches over the first valve and the second valve with providing a delay time between an open/closed switchover time of the first valve and an open/closed switchover time of the second valve.