Linear Compressor Piston Grooves for Gas Bearing Optimization

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Solution Overview

Problem

The existing linear compressor designs have a large volume, which occupies significant space in the machine room of refrigerators, and reducing its size to increase storage space compromises performance due to increased friction and inefficiencies in gas bearing technology.

Innovation Solution

The design incorporates a piston with first and second grooves on its outer surface, positioned between the cylinder nozzles, to optimize refrigerant flow and reduce pressure loss, along with an expansion part in the cylinder nozzle to enhance lifting force and prevent refrigerant reintroduction into the compression space.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Volume of stationary object

If the linear compressor size is reduced to increase refrigerator storage space, then the volume of the machine room is reduced, but the compression performance deteriorates due to increased friction and inefficiencies

Engineering Contradiction:
Improvemachine room volumeVSAvoidcompression performance
Core Design Contradiction:
Volume of stationary objectVSProductivity

Solution Approach 1:

The piston is divided into multiple sections with different groove configurations (first groove, second groove, third groove) at different positions. This segmentation allows optimized refrigerant flow control in each section, improving gas bearing efficiency and reducing friction without increasing overall compressor size.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

Different grooves are positioned at specific locations on the piston (first groove at front, second groove at middle, third groove at rear) with different dimensions and orientations. This local differentiation optimizes refrigerant distribution and pressure control at each position, enhancing overall compression performance in a compact design.

Inventive Principle:
Principle #3Local quality

2Productivity

If the drive frequency is increased to compensate for deteriorated compressor performance, then the compression efficiency is improved, but the friction force due to oil circulation increases

Engineering Contradiction:
Improvecompression efficiencyVSAvoidfriction force
Core Design Contradiction:
ProductivityVSObject-generated harmful factors

Solution Approach 1:

The patent utilizes gas bearing technology where refrigerant gas is supplied through multiple nozzles to create a gas film between the piston and cylinder wall. This pneumatic bearing system replaces traditional oil lubrication, eliminating oil circulation friction and allowing high-speed operation without increased friction losses.

Inventive Principle:
Principle #29Pneumatics and hydraulics

Solution Approach 2:

Refrigerant gas acts as an intermediary substance, forming a gas bearing film that separates the piston from the cylinder wall. This intermediary gas layer reduces direct metal-to-metal contact and eliminates the need for oil circulation, thereby reducing friction force while enabling high drive frequencies.

Inventive Principle:
Principle #24Intermediary (Mediator)

3Force

If gas bearing technology is used to reduce friction, then the lifting force is improved, but the small bear space limits refrigerant inflow and reduces pressure

Engineering Contradiction:
Improvelifting forceVSAvoidrefrigerant pressure
Core Design Contradiction:
ForceVSStress or pressure

Solution Approach 1:

The gas bearing system is segmented into multiple nozzle groups (first, second, third nozzles) positioned at different locations. This segmentation allows distributed refrigerant supply, maintaining adequate pressure in each local region while collectively providing sufficient lifting force, overcoming the limitation of small bear space.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent extends the gas bearing system in the axial dimension by positioning nozzles and grooves at multiple positions along the piston length (front, middle, rear). This multi-dimensional arrangement increases the effective bearing area and improves refrigerant inflow without increasing the radial bear space, maintaining both lifting force and pressure.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

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 reduces the compressor's size, improves gas bearing performance, increases lifting force, and enhances compression efficiency, thereby increasing storage space and reducing power consumption.

Implementation Method 1

a gas bearing technology in which a refrigerant gas is supplied in a space between a cylinder and a piston to perform a bearing function

Methodology Applied
Scientific EffectGas bearing: Air Lubrication

Implementation Method 2

the refrigerant supplied through the cylinder nozzle lifts the piston

Methodology Applied
Scientific EffectPressure differential: Pressure Gradient

Implementation Method 3

The permanent magnet may linearly reciprocate by an electromagnetic force between the permanent magnet and the inner (or outer) stator

Methodology Applied
Scientific EffectElectromagnetic force: Lorentz Force

Implementation Method 4

compressing, condensing, expanding, and evaporating the refrigerant are repeatedly performed

Methodology Applied
Scientific EffectCompression: Compression

Data Source

PatentEP3239521B1Linear compressor
Publication Date: 2023.02.22 LG ELECTRONICS INC
  • EP3239521B1 patent drawingFigure 1
  • EP3239521B1 patent drawingFigure 2
  • EP3239521B1 patent drawingFigure 3

AI summary

A linear compressor is provided. The linear compressor may include a piston having a first piston groove and a second piston groove.