Linear Compressor Piston-Rod Structure for Lateral Force Relief

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Solution Overview

Problem

Linear compressors face issues with lateral force damage to the piston and oil shortages, which affect reliability and efficiency, particularly in oil-lubricated models, while gas-lubricated models are prone to mechanical stress due to the absence of oil.

Innovation Solution

The design incorporates a piston with a rod and plate configuration, where the rod distributes lateral forces and increases refrigerant intake through flow holes, and an elastic member to mitigate mechanical stress, enhancing the compressor's structural integrity and refrigerant flow.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Temperature

If oil lubrication is used in the linear compressor, then the cylinder and piston can be suppressed from overheating and suction loss can be prevented, but oil shortage inside the casing may occur leading to reduced reliability

Engineering Contradiction:
Improvecylinder and piston temperatureVSAvoidcompressor reliability
Core Design Contradiction:
TemperatureVSReliability

Solution Approach 1:

The patent extracts the lubrication function from oil and implements it through gas pressure instead. The piston is designed with a lubrication groove and lubrication holes that utilize the pressure of refrigerant gas to maintain separation between the piston and cylinder wall, eliminating the need for oil storage and circulation systems while preventing overheating and suction loss.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The patent applies pneumatic principles by using refrigerant gas pressure instead of liquid oil for lubrication. The lubrication groove and holes are designed to utilize the dynamic pressure of the refrigerant gas flowing through the compression chamber, creating a gas film that reduces friction and heat between the piston and cylinder while avoiding oil-related reliability issues.

Inventive Principle:
Principle #29Pneumatics and hydraulics

2Volume of moving object

If gas lubrication is used in the linear compressor, then the compressor size can be reduced and reliability is improved by eliminating oil shortage, but lateral force applied to the piston may cause product damage

Engineering Contradiction:
Improvecompressor sizeVSAvoidpiston structural integrity
Core Design Contradiction:
Volume of moving objectVSStrength

Solution Approach 1:

The patent segments the piston structure into multiple functional zones: a head portion with a lubrication groove, a connection portion with reinforcement ribs, and a rod connection portion. The lubrication groove is divided into multiple lubrication holes distributed around the circumference, creating localized support points that collectively manage lateral forces while maintaining overall structural integrity.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent employs composite structural design by combining the piston head made of durable material resistant to lateral forces with integrated lubrication features. The reinforcement ribs create a composite structure that distributes stress more effectively, allowing the piston to withstand lateral forces from gas lubrication while maintaining a compact design.

Inventive Principle:
Principle #40Composite materials

3Strength

If a rod is added to the piston to distribute lateral force, then mechanical stress is reduced, but the device complexity increases

Engineering Contradiction:
Improvepiston stress distributionVSAvoidpiston structure complexity
Core Design Contradiction:
StrengthVSDevice complexity

Solution Approach 1:

The patent merges the rod function into the piston structure itself by creating an integrated piston assembly where the rod is seamlessly connected to the piston head through a reinforcement structure. The lubrication groove and holes are integrated into the piston body, and the rod connection portion is formed as part of the same component, eliminating separate parts while maintaining stress distribution capabilities.

Inventive Principle:
Principle #5Merging (Combining)

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 effectively distributes lateral forces, reduces mechanical stress, and increases refrigerant intake, improving the compressor's reliability and efficiency by integrating an elastic member to support the piston and plate assembly.

Implementation Method 1

an elastic member to mitigate mechanical stress

Methodology Applied
Scientific EffectElasticity: Elasticity

Implementation Method 2

The plate defines a flow hole configured to receive the refrigerant

Methodology Applied
Scientific EffectFluid flow:

Data Source

PatentEP3851671B1compressor
Publication Date: 2022.07.06 LG ELECTRONICS INC
  • EP3851671B1 patent drawingFigure 1
  • EP3851671B1 patent drawingFigure 2
  • EP3851671B1 patent drawingFigure 3

AI summary

A compressor for compressing and discharging a refrigerant sucked into a cylinder includes a cylinder (140) forming a compression space (103) of the refrigerant and having a cylindrical shape; a piston (150) configured to reciprocate in the cylinder (140) along an axial direction and having a cylindrical shape; a suction valve (155) disposed at a front of the piston (150); a plate (220) disposed in a rear of the piston (150), the plate (220) comprising a flow groove (222) into which the refrigerant is sucked; and a rod (210) extending along the axial direction, one end of the rod (210) being disposed on the suction valve (155), and other end of the rod (210) being disposed on the plate (220).