Method of improved control for variable volume ratio valve
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Solution Overview
Problem
Variable volume ratio compressors experience excessive wear due to high-frequency switching of volume ratios, which can lead to inconsistent operation and reduced efficiency, especially under partial load conditions.
Innovation Solution
Implementing a controller that determines a switching parameter based on suction density and compressor speed, with incorporated delay periods to manage changes in volume ratio, reducing frequent switching and optimizing compressor operation by adjusting valve positions between suction and intermediate pressures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If automated switching of volume ratios is implemented to improve compressor efficiency under partial load conditions, then compressor efficiency is improved, but component wear increases due to high-frequency switching
Solution Approach 1:
The patent implements periodic action by introducing delay periods between volume ratio switching operations. The controller is configured to wait for a specified delay period before allowing another volume ratio change, thereby converting continuous high-frequency switching into controlled periodic action. This reduces mechanical wear on valves and pistons while maintaining efficiency benefits during stable operating conditions.
Solution Approach 2:
The patent applies preliminary action by implementing a delay period before executing volume ratio switching. The controller determines when a volume ratio change is needed based on operating conditions, then waits for a delay period to elapse before actually implementing the change. This preliminary waiting period prevents premature or excessive switching, reducing component wear while still achieving efficiency improvements.
2Productivity
If volume ratio switching is implemented to match discharge conditions to condenser pressure, then system efficiency increases, but operational consistency deteriorates due to excessive switching frequency
Solution Approach 1:
The patent implements periodic action by establishing regular delay intervals between volume ratio switching operations. This converts potentially chaotic high-frequency switching into controlled periodic action, ensuring that volume ratio changes occur only when operating conditions have been stable long enough to justify the transition. This maintains system efficiency while improving operational consistency.
Solution Approach 2:
The patent applies preliminary action by requiring a delay period to elapse before executing volume ratio changes. This preliminary action ensures that switching decisions are based on sustained operating conditions rather than transient fluctuations, thereby improving operational consistency while still achieving the efficiency benefits of volume ratio matching.
Data Source
AI summary
Variable volume ratio compressors may be controlled using a switching parameter based on compressor speed and suction density to improve the matching of compressor volume ratio to desired discharge conditions. Delay periods may be implemented in the determination of when to change volume ratio to control the frequency of changes to the volume ratio. The switching parameter may be a product of the compressor speed and suction density. The volume ratio of the compressor may be controlled by switching valves directing pressure to a piston of a variable volume ratio system of the compressor.