Oil Separator Float Pressure Equalization for Reliable Oil Return

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Solution Overview

Problem

Conventional oil separators in refrigerating cycle apparatuses face issues with float breakage due to extreme pressure changes, leading to inefficient oil return and increased manufacturing costs, as well as potential compressor burning and cooling errors.

Innovation Solution

An oil separator design featuring a float with equalizing means that allows communication between the interior and exterior spaces, eliminating pressure differences and incorporating an equalizing path or tube to prevent float breakage, thus enabling effective oil return without high-strength materials.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a conventional float is used in the oil separator, then the float can detect oil level changes, but the float breaks due to extreme pressure changes between compressor operation and stop

Engineering Contradiction:
Improvefloat durabilityVSAvoidfloat pressure resistance
Core Design Contradiction:
ReliabilityVSStrength

Solution Approach 1:

An equalizing tube is introduced as an intermediary element that connects the interior of the float to the exterior environment. This tube allows pressure equalization between the inside and outside of the float, preventing pressure differential buildup that causes float breakage. The equalizing tube acts as a mediator that transfers pressure information from the external environment to the float interior, eliminating the harmful pressure difference without compromising the float's oil level detection function.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Strength

If high-strength materials and welding are used to make the float withstand pressure changes, then the float can resist pressure, but manufacturing cost increases

Engineering Contradiction:
Improvefloat pressure resistanceVSAvoidmanufacturing cost
Core Design Contradiction:
StrengthVSEase of manufacture

Solution Approach 1:

Instead of using expensive high-strength materials and complex welding processes to make the float pressure-resistant, the invention introduces an equalizing tube as a simple intermediary component. This tube allows the float to withstand pressure changes without requiring special materials or complex manufacturing, thereby significantly reducing manufacturing costs while maintaining float durability.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The invention changes the pressure parameter inside the float by providing a pressure equalization path through the equalizing tube. This allows the internal pressure to match the external pressure, eliminating the need for high-strength materials and complex welding, thus simplifying manufacturing and reducing costs.

Inventive Principle:
Principle #35Parameter changes

3Strength

If metal float is used to withstand pressure, then the float has strength, but metal fatigue causes float breakage over time

Engineering Contradiction:
Improvefloat strengthVSAvoidfloat service life
Core Design Contradiction:
StrengthVSDuration of action of stationary object

Solution Approach 1:

The equalizing tube serves as a mediator that prevents pressure differential stress from acting on the float structure. By allowing pressure equalization, the tube eliminates the cyclic stress that causes metal fatigue, thereby extending the float's service life without requiring changes to the float material or structure.

Inventive Principle:
Principle #24Intermediary (Mediator)

4Ease of manufacture

If a simple float configuration is used, then manufacturing is easy, but the float breaks due to pressure changes

Engineering Contradiction:
Improvefloat manufacturing simplicityVSAvoidfloat reliability
Core Design Contradiction:
Ease of manufactureVSReliability

Solution Approach 1:

The equalizing tube is a simple component that can be easily manufactured and integrated into the float structure. Despite its simplicity, it effectively prevents float breakage by enabling pressure equalization, thus maintaining manufacturing ease while significantly improving float reliability.

Inventive Principle:
Principle #24Intermediary (Mediator)

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 prevents float breakage, ensures reliable oil return, reduces manufacturing costs, and maintains refrigerant circulation efficiency, effectively preventing compressor burning and cooling errors.

Implementation Method 1

equalizing means having one end that opens at a bottom part in the float and the other end that opens outside of the float downward and above the oil level in the tank

Methodology Applied
Scientific EffectPressure equalization: Pascal's Law

Implementation Method 2

a float having a hollow therein that is held vertically movably in the tank, the float moving up and down with a change of an oil level in the tank

Methodology Applied
Scientific EffectBuoyancy: Archimedes' Principle (Buoyancy)

Data Source

PatentEP2500677B1Oil separator and refrigerating cycle apparatus using the same
Publication Date: 2014.11.05 PANASONIC HEALTHCARE HLDG CO LTD
  • EP2500677B1 patent drawingFigure 1
  • EP2500677B1 patent drawingFigure 2
  • EP2500677B1 patent drawingFigure 3

AI summary

An oil separator capable of preventing breakage in a float with an extremely simple configuration is provided. An oil separator is to separate oil in a refrigerant that is discharged from a compressor and return the oil to the compressor. The oil separator includes: a tank, into which a refrigerant discharged from the compressor flows; a float having a hollow therein that is held vertically movably in the tank, the float moving up and down with a change of an oil level in the tank; and a needle valve to return oil in the tank to the compressor in accordance with up/down movement of the float. The float includes an equalizing tube having a lower end that opens at a bottom part in the float and an upper end that opens outside of the float and above the oil level in the tank.