Screw Compressor Slide Valve Gap Sealing
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Solution Overview
Problem
Conventional screw compressors experience refrigerant leakage from the gap between the back surface of the slide valve and the inner circumferential surface of the high-low pressure partition wall due to pressure differences, particularly with high-pressure refrigerants like R410A, which degrades compressor performance.
Innovation Solution
A screw compressor design that includes a partition wall and an injection mechanism to supply oil to the gap between the inner circumferential surface of the partition wall and the back surface of the slide valve, sealing the gap and reducing refrigerant leakage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a gap is provided between the back surface of the slide valve and the inner circumferential surface of the high-low pressure partition wall to prevent mutual contact, then the reliability of the components is improved, but refrigerant leakage increases degrading compressor performance
Solution Approach 1:
The patent introduces oil as an intermediary substance to seal the gap between the slide valve back surface and the partition wall inner circumferential surface. The oil forms a sealing film that prevents refrigerant leakage while allowing the gap to remain open for component reliability, thus resolving the contradiction between preventing mutual contact and eliminating refrigerant leakage
Solution Approach 2:
The patent changes the physical state and properties of the gap by introducing oil, transforming it from a direct gas-phase refrigerant leakage path to a liquid-mediated sealing interface. This parameter change in the gap's sealing mechanism allows simultaneous maintenance of gap openness for reliability and refrigerant leakage prevention
2Loss of energy
If the gap between the slide valve and partition wall is reduced to eliminate refrigerant leakage, then refrigerant leakage is reduced, but the risk of mutual contact between components increases
Solution Approach 1:
Oil serves as a mediator that enables the gap to remain sufficiently large for component reliability while still preventing refrigerant leakage. The oil film fills the gap space and creates an effective seal without requiring the gap dimensions to be reduced to near-zero values
3Loss of energy
If a covering member is provided to the inner circumferential surface of the slide valve to fill the gap between the slide valve and screw rotor, then refrigerant leakage from the inner circumferential surface is reduced, but refrigerant leakage from the back surface side of the slide valve remains
Solution Approach 1:
The patent extracts the sealing function from the mechanical covering member approach and relocates it to the back surface side of the slide valve where oil injection sealing is implemented. This separates the sealing responsibilities: the inner circumferential surface uses traditional covering members while the back surface uses oil injection, addressing the specific leakage path without adding overall complexity
Solution Approach 2:
By applying oil injection sealing to the back surface gap, the patent uses oil as an intermediary to prevent refrigerant leakage from this specific location, complementing the covering member solution on the inner circumferential surface and providing comprehensive sealing without significant additional complexity
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 solution effectively eliminates or reduces refrigerant leakage from the gap, enhancing the performance and efficiency of the screw compressor, contributing to energy savings.
Implementation Method 1
an injection mechanism configured to supply oil to a gap between an inner circumferential surface of the partition wall and the back surface side of the slide valve to seal the gap
Data Source
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AI summary
A screw compressor 1 includes a casing body 8, a screw rotor 9 disposed to rotate inside the casing body 8, a slide valve 14 movably provided between the casing body 8 and the screw rotor 9, a high-low pressure partition wall 17 provided to face a back surface side 14f of the slide valve 14 and configured to divide an interior of the casing body 8 into a discharge pressure space and a suction pressure space, and an injection mechanism 20 configured to supply oil to a gap between the high-low pressure partition wall 17 and the back surface side of the slide valve 14 to seal the gap.