Linear Compressor Gas Bearing Structure for Piston Misalignment

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Solution Overview

Problem

Conventional linear compressors face issues with piston misalignment leading to abrasion and reduced durability due to friction, and oil lubrication systems suffer from oil shortages and reliability concerns, while gas lubrication systems require complex thread wound designs to prevent dirt ingress.

Innovation Solution

The compressor features fine irregularities on the piston and cylinder surfaces, including circular band-shaped patterns and gas inflow passages to enhance floating force and prevent oil ingress, using a gas bearing system for lubrication and reducing friction, and employing ultra-fine steel balls for surface treatment to improve durability.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Temperature

If oil lubrication is used in linear compressors, then cooling effect and lubrication are improved, but oil shortage occurs and reliability deteriorates

Engineering Contradiction:
Improvecooling effectVSAvoidreliability
Core Design Contradiction:
TemperatureVSReliability

Solution Approach 1:

The patent replaces the oil lubrication system with a gas bearing system that uses gas (typically air or refrigerant gas) to provide both lubrication and cooling. The gas bearing eliminates mechanical contact between the piston and cylinder wall, substituting the oil-based lubrication mechanism with a gas-based non-contact lubrication system, thereby preventing oil shortage while maintaining cooling effectiveness

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent employs pneumatic principles by introducing gas into the clearance space between the piston and cylinder to form a gas bearing. This pneumatic system uses gas pressure to maintain separation between moving parts, providing both lubrication and cooling functions without requiring oil circulation systems, thus improving reliability while maintaining thermal management

Inventive Principle:
Principle #29Pneumatics and hydraulics

2Reliability

If gas lubrication is used in linear compressors, then miniaturization is achieved and reliability is improved, but complex thread wound designs are required to prevent dirt ingress

Engineering Contradiction:
ImprovereliabilityVSAvoiddevice complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent extracts and eliminates the complex thread wound filter design from the gas lubrication system. Instead of using threads to prevent dirt ingress, the invention employs a simplified gas bearing configuration where the gas supply system inherently prevents contaminant entry, removing the need for additional protective structures and reducing overall device complexity

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The gas supply system in the patent serves multiple functions simultaneously: it provides lubrication through the gas bearing, cooling through gas flow, and contamination prevention through pressurized gas sealing. This multi-functionality eliminates the need for separate thread wound filters or protective structures, simplifying the overall design while maintaining reliability

Inventive Principle:
Principle #6Universality (Multi-functionality)

3Force

If piston misalignment occurs in linear compressors, then friction and abrasion increase, but durability is reduced

Engineering Contradiction:
ImprovefrictionVSAvoiddurability
Core Design Contradiction:
ForceVSDuration of action of stationary object

Solution Approach 1:

The patent introduces gas as an intermediary substance between the piston and cylinder wall to prevent direct mechanical contact. This gas bearing acts as a mediator that separates the moving parts, eliminating friction and abrasion that would otherwise occur during piston misalignment, thereby significantly improving the durability of both the piston and cylinder

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent replaces the mechanical contact-based lubrication system with a non-contact gas bearing system. By substituting the traditional friction-based mechanical interaction with a gas-based separation mechanism, the system eliminates wear and tear caused by piston misalignment, extending the service life of critical components

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

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 friction and abrasion, enhances the floating force of the piston, prevents oil from entering the sliding parts, and improves the reliability and durability of the compressor by maintaining consistent floating force and preventing oil accumulation, thus addressing misalignment and lubrication challenges.

Implementation Method 1

using a gas bearing system for lubrication and reducing friction

Methodology Applied
Scientific EffectGas lubrication: Air Lubrication

Implementation Method 2

fine irregularities on the piston and cylinder surfaces, including circular band-shaped patterns and gas inflow passages to enhance floating force

Methodology Applied
Scientific EffectGas pressure distribution: Pressure Gradient

Data Source

PatentEP3819501B1Compressor and manufacturing method thereof
Publication Date: 2022.01.26 LG ELECTRONICS INC
  • EP3819501B1 patent drawingFigure 1
  • EP3819501B1 patent drawingFigure 2
  • EP3819501B1 patent drawingFigure 3

AI summary

A compressor and a method of manufacturing the same are disclosed. The compressor includes a piston (260-1, 260-2, 260-3) having a cylindrical shape and having formed therein a suction space (102), in which refrigerant gas is sucked, and a cylinder (140, 240, 240-1, 240-2) having, as a space formed therein, formed therein a compression space (103), in which refrigerant gas is compressed, by reciprocation of the piston in an axial direction. A gas inflow passage having one side communicating with a gas pocket outside the cylinder and the other side communicating with a space formed in the cylinder is formed in the cylinder, and the piston includes a plurality of fine irregularities (265, 266, 267) formed in an outer circumferential surface of a guide (262) facing the cylinder and provided at a position corresponding to the gas inflow passage.