Linear Compressor Piston Clearance Profile for Leakage and Friction

Solution Overview

Problem

Conventional linear compressors face issues with refrigerant leakage and friction loss due to clearance between the piston and cylinder, leading to efficiency deterioration.

Innovation Solution

The design incorporates a piston with varying diameters and lengths of outer circumferential surfaces, creating a small clearance with the cylinder to minimize refrigerant leakage and maintain a uniform distance, thereby reducing friction loss and improving floating force.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of substance

If the clearance between the piston and cylinder is reduced to minimize refrigerant leakage, then refrigerant leakage loss decreases, but friction loss increases due to increased friction between the piston and cylinder

Engineering Contradiction:

Improverefrigerant leakageVSAvoidfriction loss

Core Design Contradiction:

Loss of substanceVSLoss of energy

Solution Approach 1:

The piston is designed with different diameter sections (first diameter section, second diameter section, third diameter section) where each section has a different diameter. This creates different clearance distances between the piston and cylinder at different axial positions. The first diameter section has a smaller clearance to reduce refrigerant leakage, while the second and third diameter sections have larger clearances to reduce friction loss, allowing each region to optimize for its specific function.

Inventive Principle:

Principle #3Local quality

2Force

If the clearance between the piston and cylinder is reduced to improve floating force, then floating force increases, but friction loss increases due to increased contact between the piston and cylinder

Engineering Contradiction:

Improvefloating forceVSAvoidfriction loss

Core Design Contradiction:

ForceVSLoss of energy

Solution Approach 1:

The piston is designed with different diameter sections (first diameter section, second diameter section, third diameter section) where each section has a different diameter. This creates different clearance distances between the piston and cylinder at different axial positions. The first diameter section has a smaller clearance to reduce refrigerant leakage, while the second and third diameter sections have larger clearances to reduce friction loss, allowing each region to optimize for its specific function.

Inventive Principle:

Principle #3Local quality

3Ease of manufacture

If the piston structure is simplified to reduce manufacturing complexity, then manufacturing ease improves, but the ability to maintain uniform clearance and minimize leakage deteriorates

Engineering Contradiction:

Improvepiston machiningVSAvoidrefrigerant leakage

Core Design Contradiction:

Ease of manufactureVSLoss of substance

Solution Approach 1:

The piston is designed with different diameter sections (first diameter section, second diameter section, third diameter section) where each section has a different diameter. This creates different clearance distances between the piston and cylinder at different axial positions. The first diameter section has a smaller clearance to reduce refrigerant leakage, while the second and third diameter sections have larger clearances to reduce friction loss, allowing each region to optimize for its specific function.

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 configuration effectively minimizes refrigerant leakage and friction loss, enhancing the efficiency and floating force of the piston, thus improving the overall performance of the linear compressor.

Implementation Method 1

since a sawtooth-shaped uneven portion may be formed in the outer circumferential surface of the piston and oil is concentrated (compressed) in the uneven portion to increase pressure, floating force of the piston in the cylinder may be increased

Methodology Applied

Scientific EffectCentrifugal force: Centrifugal Force

Data Source

PatentUS11346338B2Linear compressor

Publication Date: 2022.05.31 LG ELECTRONICS INC

AI summary

A linear compressor includes a cylinder, a piston, and a discharge valve, wherein the piston includes a first part extending in the axial direction, a second part having a diameter greater than that of the first part and formed at one end of the first part facing the discharge valve, and a third part having a diameter greater than that of the first part and formed at the other end of the first part. The second part includes a first outer circumferential surface extending backward from a front surface of the piston, and a second outer circumferential surface spaced apart from the first outer circumferential surface in a direction away from the discharge valve, and a distance between the first outer circumferential surface and an inner circumferential surface of the cylinder is less than a distance between the second outer circumferential surface and the inner circumferential surface of the cylinder.