Scroll Compressor Non-Return Valve Axial Backflow Prevention
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Solution Overview
Problem
High-pressure scroll compressors with the compression unit located below the motor unit face challenges in preventing oil and refrigerant from flowing back to the suction pipe, leading to increased suction loss and friction loss due to oil leakage, especially in bottom-compression types where the compression unit is adjacent to an oil storage space.
Innovation Solution
A non-return valve is installed between the compression unit and the refrigerant suction pipe, operating orthogonally to the suction pipe's direction, to block fluid flow back into the suction pipe, and a suction passage is defined using the lower space of the compression unit, allowing for a valve installation without extending the compressor's length, enhancing the valve's responsiveness and simplifying its structure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a check valve is installed in the suction passage to prevent oil and refrigerant from flowing back to the suction pipe, then oil leakage and suction loss are reduced, but the device complexity increases due to additional components
Solution Approach 1:
The check valve is integrated into the suction passage structure itself, merging the valve function with the existing passage components. This eliminates the need for separate, additional check valve assemblies while still providing the necessary backflow prevention function, thus reducing device complexity while maintaining reliability
Solution Approach 2:
The suction passage structure is designed to serve multiple functions: it acts as both the fluid transport pathway and the check valve mechanism. By making the suction passage multi-functional, the design avoids adding dedicated check valve components, thereby preventing increase in device complexity while achieving reliable oil backflow prevention
2Device complexity
If the check valve is disposed outside the casing, then the structure is simplified, but oil leakage and refrigerant backflow increase due to gap generation between the valve and compression unit
Solution Approach 1:
The check valve is nested within the compression unit structure, specifically positioned inside the casing where it can utilize the existing spatial arrangement. This nesting approach allows the valve to remain structurally simple while eliminating gaps that would cause leakage, as the valve operates within the confined space of the compression unit rather than externally
3Device complexity
If the check valve operates in the radial direction inside the casing, then the structure is simplified, but the responsiveness of the valve is reduced
Solution Approach 1:
The check valve operation is transitioned from radial direction to axial direction, utilizing a different spatial dimension. This dimensional change allows the valve to respond more quickly to pressure differential changes while maintaining structural simplicity, as axial movement provides a more direct response path for the valve disc or plug
4Length of stationary object
If the suction passage is defined using the lower space of the compression unit, then the compressor length is not extended, but the space for valve installation is limited
Solution Approach 1:
Instead of extending the compressor length axially to accommodate the suction passage and valve, the design utilizes the radial space within the existing compression unit. By developing the suction passage in the radial direction and positioning the check valve within the available radial clearance, the compressor maintains its compact axial length while providing sufficient space for valve installation and operation
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
This configuration effectively prevents oil and refrigerant from flowing back to the suction side, reducing suction loss and friction loss, and ensures reliable operation by maintaining oil supply to the compression unit while minimizing leakage.
Implementation Method 1
a non-return valve provided between the compression unit and the refrigerant suction pipe to block a fluid flowing backward from the compression unit to the refrigerant suction pipe
Data Source
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AI summary
A scroll compressor according to the present disclosure may include a refrigerant suction pipe coupled to a discharge cover or a fixed scroll through a casing in a radial direction, a suction passage communicating the refrigerant suction pipe with a compression chamber, and a suction passage opening and closing valve disposed inside the suction passage to be slidable in an axial direction so as to selectively open or close the suction passage. Accordingly, when the compressor is stopped, oil or refrigerant in the casing can be blocked quickly so as not to flow back to the refrigerant suction pipe through a compression unit.