Method and apparatus for pressure equalization in rotary compressors
Solution Overview
Problem
High-side compressors, such as rotary compressors, face difficulties in starting when there is a significant pressure differential between the discharge and suction sides, often failing to initiate operation when the discharge side pressure is approximately 7 psi greater than the suction side pressure.
Innovation Solution
A rotary compressor system that includes a solenoid valve fluidly coupled between the compression chamber and the suction side, electrically coupled in series with an overload-protection switch, allowing pressure equalization by opening the solenoid valve when the compressor motor experiences an overload, ensuring the system can restart without pressure imbalances.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a solenoid valve is electrically coupled in parallel with the compressor motor (maintaining continuous power to solenoid), then the solenoid valve remains closed during normal operation to maintain pressure differential, but the compressor cannot restart after overload because the solenoid valve stays closed blocking pressure equalization
Solution Approach 1:
The solenoid valve is electrically coupled in series with the overload-protection switch and compressor motor, merging their control circuits. This ensures that when the overload-protection switch opens to stop the motor, the solenoid valve simultaneously opens to equalize pressure, enabling automatic restart capability without additional complexity.
Solution Approach 2:
The system uses the overload-protection switch's own operation to automatically control the solenoid valve. When the overload-protection switch trips, it automatically opens the solenoid valve through the series connection, allowing the system to self-correct the pressure differential issue without external intervention or complex control logic.
2Productivity
If the solenoid valve is kept closed to maintain pressure differential for compression, then compression efficiency is improved, but the compressor cannot start when pressure differential exceeds 7 psi
Solution Approach 1:
The solenoid valve's position is made dynamic through the series electrical connection with the overload-protection switch. During normal operation, the valve remains closed to maintain pressure differential for efficient compression. When the motor stops due to overload, the valve automatically opens to equalize pressure, allowing the compressor to restart when conditions improve, thus adapting to different operational states.
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
Enables the compressor to equalize pressure between the discharge and suction sides, facilitating successful restarts by allowing trapped refrigerant to escape through the solenoid valve, thus overcoming the challenge of high pressure differentials and ensuring reliable operation.
Implementation Method 1
A solenoid valve is fluidly coupled between the compression chamber and a location upstream of the suction side
Data Source
AI summary
A rotary compressor system includes a compressor housing that includes a compressor motor that draws in fluid from a suction side. The fluid is compressed within a compression chamber and discharged through a discharge side. The compression chamber is disposed between the suction side and the discharge side. An overload-protection switch is electrically coupled in series with the compressor motor and is adapted to cut power to the compressor motor responsive to an overload event. A solenoid valve is fluidly coupled between the compression chamber and a location upstream of the suction side and is electrically coupled in series with the overload-protection switch. An interruption of electrical current to the compressor motor also interrupts electrical current to the solenoid valve, which opens the solenoid valve to equalize pressure between the suction side and the discharge side.