Linear Compressor Discharge Cover Layout for Cooler Gas Lubrication

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Solution Overview

Problem

Gas-lubricated linear compressors experience suction and compression losses due to overheating of the cylinder and piston, heat transfer from discharge covers to the frame, and inefficient heat dissipation, leading to reduced compressor efficiency.

Innovation Solution

The design includes a linear compressor with a gas bearing system where refrigerant from discharge covers is guided to lubricate the cylinder and piston at a lower temperature, and a heat insulating member is used to prevent direct contact and heat transfer between discharge covers and the frame, enhancing heat radiation and convective heat transfer coefficients.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If gas-lubricated linear compressor uses high-temperature refrigerant gas to lubricate between cylinder and piston, then lubrication effect is improved, but cylinder and piston are overheated causing suction loss or compression loss

Engineering Contradiction:
Improvelubrication effectVSAvoidsuction loss or compression loss
Core Design Contradiction:
ReliabilityVSLoss of energy

Solution Approach 1:

The discharge cover is divided into multiple segments (first discharge cover, second discharge cover, etc.) that are disposed in sequence along the refrigerant flow direction. This segmentation allows different portions of the discharge cover to serve different functions: earlier segments can dissipate heat while later segments provide lubrication, thereby resolving the contradiction between lubrication effectiveness and overheating prevention

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

Multiple discharge covers act as intermediaries between the compression space and the external environment. These intermediate structures progressively cool the high-temperature refrigerant gas through heat dissipation surfaces before it reaches the cylinder and piston, enabling effective lubrication without overheating the compression components

Inventive Principle:
Principle #24Intermediary (Mediator)

2Stability of the object's composition

If discharge cover is directly communicated with compression space to reduce pulsation, then pulsation reduction is improved, but discharge cover temperature increases reducing heat radiation effect

Engineering Contradiction:
Improverefrigerant flow stabilityVSAvoiddischarge cover temperature
Core Design Contradiction:
Stability of the object's compositionVSTemperature

Solution Approach 1:

The patent introduces a spatial dimension by arranging multiple discharge covers in sequence along the refrigerant flow path rather than using a single cover. This dimensional arrangement allows the system to simultaneously achieve pulsation reduction (through the communicated structure) and heat dissipation (through the extended surface area distributed along the flow direction)

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

3Temperature

If distance between discharge cover and casing is increased, then heat transfer to casing is reduced, but convection heat transfer coefficient decreases reducing heat radiation effect

Engineering Contradiction:
Improveheat transfer to casingVSAvoidheat radiation effect
Core Design Contradiction:
TemperatureVSLoss of energy

Solution Approach 1:

The discharge cover system is segmented into multiple covers with different positions and functions. Earlier segments can be positioned closer to the casing for better heat dissipation, while later segments are positioned to optimize lubrication delivery. This segmentation allows optimization of heat transfer distance for each segment's specific function, resolving the contradiction between heat transfer efficiency and convection coefficient

Inventive Principle:
Principle #1Segmentation

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 suction and compression losses by maintaining lower temperatures within the compressor, improving efficiency through effective heat dissipation and reduced heat transfer, thereby enhancing the overall performance of the linear compressor.

Implementation Method 1

a gas bearing configured to guide part of refrigerant accommodated in a discharge space of any one of the plurality of discharge covers between the cylinder and the piston to lubricate between the cylinder and the piston with the refrigerant

Methodology Applied
Scientific EffectGas lubrication: Gas Lift

Implementation Method 2

a heat insulating member provided between the discharge cover and the frame

Methodology Applied
Scientific EffectThermal insulation: Thermal Insulation

Implementation Method 3

enhancing heat radiation and convective heat transfer coefficients

Methodology Applied
Scientific EffectConvection heat transfer: Convection

Data Source

PatentEP3470673B1Linear compressor
Publication Date: 2021.12.01 LG ELECTRONICS INC
  • EP3470673B1 patent drawingFigure 1
  • EP3470673B1 patent drawingFigure 2
  • EP3470673B1 patent drawingFigure 3

AI summary

A linear compressor according to the present disclosure may include a linear motor in which a mover reciprocates with respect to a stator; a compression unit configured to form a compression space in a cylinder while a piston connected to the mover of the linear motor reciprocates in the cylinder; a plurality of discharge covers in which each discharge space is provided to accommodate refrigerant discharged from the compression space, and the each discharge space is sequentially communicated therewith; and a gas bearing configured to guide part of refrigerant accommodated in a discharge space of any one of the plurality of discharge covers between the cylinder and the piston to lubricate between the cylinder and the piston with the refrigerant, wherein at least part of a discharge cover in contact with the compression unit is formed to be exposed to an outside of a discharge space of another discharge cover.