Compressor Oil Return Flow Path Design to Reduce Lubricant Splashing
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Solution Overview
Problem
In hermetic compressors, a portion of the lubricant flows out with the refrigerant gas due to splashing in the oil return passage, leading to inefficiencies and potential contamination.
Innovation Solution
The compressor features an oil return flow path with a varying cross-sectional shape that gradually increases in width and decreases in thickness, forming a film along the casing's inner surface, reducing splashing and allowing most lubricant to flow down with the refrigerant, thereby minimizing lubricant loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of substance
If lubricant flows through the oil return passage, then lubricant is transported from the compression mechanism to the bottom of the casing, but lubricant splashes in the oil return passage and flows out with refrigerant gas
Solution Approach 1:
The patent changes the geometric parameters of the oil return passage by introducing a varying cross-sectional shape with specific width-to-thickness ratio. The passage has a wider opening at the top and tapers to a thinner section at the bottom, creating a controlled flow geometry that reduces lubricant splashing and prevents lubricant from being carried out with the refrigerant gas.
2Reliability
If lubricant flows down by gravitation in the oil return passage, then lubricant returns to the bottom of the casing, but a portion of lubricant splashes and is discharged with refrigerant gas
Solution Approach 1:
The patent modifies the geometric parameters of the oil return passage by creating a varying cross-sectional shape. The passage width decreases and thickness reduces from top to bottom, forming a tapered structure that guides lubricant flow smoothly along the inner wall surface of the casing, preventing splashing and ensuring reliable lubricant return while avoiding discharge with refrigerant gas.
3Ease of manufacture
If the oil return passage has a uniform cross section, then the structure is simple, but lubricant splashes and is discharged with refrigerant gas
Solution Approach 1:
The patent introduces a varying cross-sectional geometry to the oil return passage, where the width and thickness change along the flow direction. This design modification, while slightly increasing manufacturing complexity, effectively reduces lubricant splashing and discharge, providing a practical balance between ease of manufacture and lubricant retention.
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 design significantly reduces the amount of lubricant that splashes out of the compressor, enhancing efficiency and reducing contamination by ensuring most lubricant flows down with the refrigerant, thus improving the compressor's operational performance.
Implementation Method 1
The lubricant flowing through the oil return passage of Patent Document 1 described above flows down by gravitation.
Data Source
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AI summary
A compressor (10) includes a casing (20), a compression mechanism (30), and an oil return member (100) forming an oil return flow path (130). The oil return flow path (130) includes a uniform-cross-section flow path (133) having a uniform cross-sectional shape, and a varying-cross-section flow path (134) being continuous with a lower end of the uniform-cross-section flow path (133) and having a cross-sectional shape that varies. A lower end of the varying-cross-section flow path (134) forms an outlet of the oil return flow path (130), and lies along an inner surface of the casing (20). A cross section of the lower end of the varying-cross-section flow path (134) has a greater width and a smaller thickness than a cross section of an upper end of the varying-cross-section flow path (134).