Oil separator, filter element, and compressor for cryocooler

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Solution Overview

Problem

The existing oil separators in cryocooler compressors allow a significant amount of oil to escape with the refrigerant gas, leading to premature adsorbent replacement, increased operating costs, and potential deterioration of the expander and reduced cooling capacity due to oil solidification at low temperatures.

Innovation Solution

An oil separator design incorporating a filter element with a tubular inner filter member and an outer filter layer, where the refrigerant gas outlet surface occupies at least 80% of the outer filter layer's surface area, is used to effectively separate oil from refrigerant gas, reducing oil outflow and preventing re-mixing with the refrigerant.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a conventional oil separator is used, then the structure is simple, but a significant amount of oil escapes with the refrigerant gas

Engineering Contradiction:

Improveoil separation effectivenessVSAvoidseparator structure complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The filter element is divided into multiple functional layers: an inner filter member with first porous layers for initial oil separation, and an outer filter layer with second porous layers for final filtration. This segmentation allows each layer to perform a specific separation function, improving overall oil removal effectiveness while maintaining a manageable structural complexity through modular design.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The inner filter member is nested within the outer filter layer, creating a concentric filtration system. The inner filter member surrounds the inner cavity while the outer filter layer is disposed outside it, with both layers working together in a nested configuration to progressively separate oil from refrigerant gas, achieving high separation effectiveness without excessive structural complexity.

Inventive Principle:

Principle #7Nested doll (Nesting)

2Reliability

If the refrigerant gas outlet surface area is small, then the filter structure is compact, but oil re-mixing with refrigerant gas occurs

Engineering Contradiction:

Improveoil separation effectivenessVSAvoidoutlet surface area

Core Design Contradiction:

ReliabilityVSArea of stationary object

Solution Approach 1:

The outer filter layer is designed with differentiated local properties: the second porous layers provide high filtration quality for oil separation, while the refrigerant gas outlet surface is optimized to occupy at least 80% of the outer filter layer's surface area. This local quality differentiation ensures effective oil separation at the filtration surfaces while maintaining large outlet area to prevent re-mixing, resolving the contradiction between separation effectiveness and outlet area.

Inventive Principle:

Principle #3Local quality

3Productivity

If oil flows into the expander, then the compressor operates continuously, but cooling capacity is reduced due to oil solidification

Engineering Contradiction:

Improvecompressor operation continuityVSAvoidcooling capacity

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The dual-layer filter element performs preliminary oil removal action before refrigerant gas enters the expander. The inner and outer filter layers work together to separate oil from refrigerant gas in advance, preventing oil from reaching the expander. This preliminary separation action ensures continuous compressor operation while maintaining cooling capacity by eliminating the cause of oil solidification in the expander.

Inventive Principle:

Principle #10Preliminary action

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 significantly reduces oil outflow from the separator, extending adsorbent life, lowering replacement frequencies, reducing compressor size, and maintaining cooling capacity by minimizing oil flow into the expander.

Implementation Method 1

a filter element that is disposed in the oil separator container, defines an outer cavity between the oil separator container and itself, includes an inner cavity into which refrigerant gas is introduced, and separates oil from the refrigerant gas flowing to the outer cavity from the inner cavity

Methodology Applied

Scientific EffectFiltration: Filter (physical)

Data Source

PatentUS11408655B2Oil separator, filter element, and compressor for cryocooler

Publication Date: 2022.08.09 SUMITOMO HEAVY IND LTD

AI summary

An oil separator includes: an oil separator container; and a filter element that is disposed in the oil separator container, defines an outer cavity between the oil separator container and itself, includes an inner cavity into which refrigerant gas is introduced, and separates oil from the refrigerant gas flowing to the outer cavity from the inner cavity. The filter element includes a tubular inner filter member that surrounds the inner cavity, and an outer filter layer that includes a refrigerant gas outlet surface exposed to the outer cavity and is disposed outside the inner filter member. A wire-like or band-like filter retaining member that is in contact with the outer filter layer from the outside may be provided. The refrigerant gas outlet surface may occupy at least 80% of the surface area of the outer filter layer.