Scroll Compressor Dual Flow Paths for Lubricating Oil Retention
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Solution Overview
Problem
Existing scroll compressors suffer from unintentional lubricating oil exhaustion due to its compatibility with refrigerant, leading to oil loss.
Innovation Solution
A dedicated second flow path with a narrow portion having a hydraulic diameter to length ratio of 0.01 to 0.07 is introduced to separate lubricating oil from refrigerant, reducing mixing opportunities and suppressing oil loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of substance
If a single flow path is used for both refrigerant and lubricating oil, then the structure is simple, but lubricating oil is unintentionally exhausted due to mixing with refrigerant
Solution Approach 1:
The flow path is segmented into two separate paths: a first flow path for refrigerant and a second flow path for lubricating oil. This segmentation prevents mixing between the two fluids, thereby preventing unintentional oil exhaustion while maintaining clear functional separation.
Solution Approach 2:
A partitioning member acts as an intermediary structure that physically separates the refrigerant flow path from the lubricating oil flow path. This intermediary component enables both fluids to coexist in the compressor without mixing, solving the oil loss problem.
2Reliability
If a dedicated second flow path for lubricating oil is provided, then oil loss is suppressed, but the device complexity increases
Solution Approach 1:
The partitioning member serves multiple functions: it separates the flow paths to prevent oil loss, provides structural support for the compression element, and defines the internal geometry of the compressor. This multi-functionality reduces the need for additional separate components.
Solution Approach 2:
The narrow portion of the second flow path has specific dimensional parameters (hydraulic diameter to length ratio between 0.01 and 0.07) that optimize fluid flow characteristics. These parameter optimizations ensure reliable oil retention while keeping the flow path design practical.
3Loss of substance
If the narrow portion has a small hydraulic diameter to length ratio, then refrigerant resistance increases, but lubricating oil flow is maintained
Solution Approach 1:
The flow path has different local qualities: the second flow path has a narrow portion with specific D/L ratio to control oil flow, while the first flow path has different dimensions optimized for refrigerant flow. This local differentiation allows each fluid to flow efficiently through its designated path.
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 reduces oil loss to 90% or less, maintaining efficient operation by ensuring lubricating oil remains within the compressor.
Implementation Method 1
The second flow path includes a narrow portion. The narrow portion has a smallest flow path area. A ratio of a hydraulic diameter of the narrow portion to a length of the narrow portion in an axial direction of the casing is 0.01 or more and 0.07 or less.
Data Source
AI summary
A scroll compressor includes a casing, a partition member, a compression element, and first and second flow paths provided in the partition member. The casing has a cylindrical shape with an internal space for lubricating oil. The partitioning member is fixed to the casing to divide the internal space into first and second spaces. The compression element includes fixed and movable scrolls to discharge refrigerant to the first space. The first flow path allows refrigerant to pass from the first space to the second space. The second flow path is apart from the first flow path. The second flow path guides the lubricating oil to the second space, and includes a narrow portion having a smallest flow path area. A ratio of a hydraulic diameter of the narrow portion to a length of the narrow portion in an axial direction of the casing is 0.01 to 0.07.