Hermetic Compressor Oil Guide for Refrigerant Oil Separation

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Solution Overview

Problem

Existing hermetic compressors suffer from oil leakage due to insufficient separation of oil from refrigerant, leading to friction loss and increased manufacturing costs from additional oil separators, and simple discharge passages facilitate direct oil flow with refrigerant, increasing leakage.

Innovation Solution

The hermetic compressor design includes an oil cap between the driving motor and main frame, with an oil block surrounding the main bearing surface and a curved or bent refrigerant discharge pipe to complicate the discharge passage, incorporating narrow holes or slits to enhance oil separation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a separate oil separator is installed outside the casing, then oil separation effect is improved, but the number of parts increases and manufacturing cost increases

Engineering Contradiction:
Improveoil separation effectVSAvoidnumber of parts
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent combines the oil separation function with the existing main frame structure by forming the oil separation chamber as an integrated part of the main frame. The discharge passage is configured to extend into the oil separation chamber, allowing oil-gas mixture to be separated without requiring a separate external oil separator component.

Inventive Principle:
Principle #5Merging (Combining)

2Productivity

If the discharge passage is made simple and straight, then refrigerant discharge efficiency is improved, but oil flows out directly with refrigerant increasing oil leakage

Engineering Contradiction:
Improverefrigerant discharge efficiencyVSAvoidoil leakage prevention
Core Design Contradiction:
ProductivityVSReliability

Solution Approach 1:

The discharge passage is configured with a curved or bent shape instead of a straight line. The passage extends from the compression chamber, curves downward below the main bearing surface level, then rises to connect with the oil separation chamber. This curved path increases flow resistance and prevents oil from flowing directly out with the refrigerant.

Inventive Principle:
Principle #14Spheroidality (Curvature)

Solution Approach 2:

The discharge passage is divided into multiple sections with different orientations: a downward section, a horizontal section at the lowest point, and an upward section. This segmentation creates flow resistance at each transition point, preventing direct oil flow while maintaining refrigerant discharge capability.

Inventive Principle:
Principle #1Segmentation

3Speed

If the discharge passage flow resistance is reduced, then refrigerant discharge speed is improved, but oil separation effect deteriorates

Engineering Contradiction:
Improverefrigerant discharge speedVSAvoidoil separation effect
Core Design Contradiction:
SpeedVSReliability

Solution Approach 1:

The discharge passage has different flow resistance characteristics at different locations. The passage cross-sectional area and curvature radius are optimized at each section: larger area at the inlet for high speed, curved sections with controlled radius for flow resistance, and appropriate area at the outlet. This local optimization allows high refrigerant discharge speed while maintaining effective oil separation.

Inventive Principle:
Principle #3Local quality

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 effectively prevents oil leakage by guiding oil back to storage while complicating the refrigerant discharge path, improving oil separation efficiency and reducing friction loss.

Implementation Method 1

complicating the discharge passage... incorporating narrow holes or slits to enhance oil separation

Methodology Applied
Scientific EffectFlow resistance: Drag

Implementation Method 2

an oil block surrounding the main bearing surface... guiding oil back to storage

Methodology Applied
Scientific EffectGravity: Gravitation

Data Source

PatentEP4060193B1Hermetic compressor
Publication Date: 2026.02.18 LG ELECTRONICS INC
  • EP4060193B1 patent drawingFigure 1
  • EP4060193B1 patent drawingFigure 2
  • EP4060193B1 patent drawingFigure 3

AI summary

A hermetic compressor according to the present disclosure may include an oil guide disposed on a rotating shaft between a driving motor and a main frame, the oil guide may include an oil block surrounding a main bearing surface between the main frame and the rotating shaft, and one end of the oil block may radially overlap a shaft support protrusion of the main frame. This can suppress oil returned after lubricating a compression unit from being scattered, thereby reducing a leakage of the oil to outside of a casing through a refrigerant discharge pipe.