Reciprocating compressor

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Solution Overview

Problem

Linear compressors face issues with increased temperature of refrigerant causing overheating, reduced compression efficiency, and heat transfer to the piston and cylinder, leading to operational inefficiencies and limited operating frequencies due to high-temperature refrigerant flow and discharge cover heat conduction.

Innovation Solution

The implementation of a discharge plenum in close contact with the discharge cover and a structure for decreasing the temperature of bearing refrigerant supplied to the gap between the cylinder and piston, utilizing multiple flow paths for refrigerant as a bearing, and minimizing the surface area of the discharge cover to enhance heat dissipation through convection.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If high-temperature refrigerant is supplied through the gas hole to the piston and cylinder, then the refrigerant can reach the compression space, but heat is transferred to the piston and cylinder causing overheating and reduced compression efficiency

Engineering Contradiction:
Improvecompression efficiencyVSAvoidpiston and cylinder temperature
Core Design Contradiction:
ProductivityVSTemperature

Solution Approach 1:

The gas hole is divided into multiple segments (first gas hole and second gas hole) that are spatially separated and directed toward different targets. The first gas hole supplies refrigerant to the piston while the second gas hole supplies refrigerant to the cylinder, allowing independent temperature control and heat management for each component.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

A gas guide groove is introduced as an intermediary structure that directs the flow of refrigerant from the gas hole to specific locations on the piston and cylinder. This intermediary pathway allows precise control over where the refrigerant flows and how heat is distributed, preventing direct overheating of components.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Productivity

If the discharge cover has a large surface area to accommodate refrigerant discharge, then refrigerant can be discharged effectively, but heat is conducted from the discharge cover to the frame and then to the piston and cylinder

Engineering Contradiction:
Improverefrigerant discharge efficiencyVSAvoidpiston and cylinder temperature via heat conduction
Core Design Contradiction:
ProductivityVSTemperature

Solution Approach 1:

The function of discharging refrigerant is extracted from the discharge cover and relocated to a dedicated discharge plenum. The discharge plenum is positioned away from the frame and piston-cylinder assembly, allowing the discharge cover to maintain its discharge function while eliminating its role as a heat conduction pathway to the frame.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

A discharge plenum is introduced as an intermediary chamber between the discharge cover and the frame. This plenum serves as a buffer that receives discharged refrigerant while preventing direct thermal contact between the discharge cover and the frame, thereby blocking the heat conduction pathway.

Inventive Principle:
Principle #24Intermediary (Mediator)

3Ease of manufacture

If a supporter and magnet frame are added to support the permanent magnet, then the linear motor can be assembled, but the weight of the driving part increases

Engineering Contradiction:
Improveassembly feasibilityVSAvoiddriving part weight
Core Design Contradiction:
Ease of manufactureVSWeight of moving object

Solution Approach 1:

The supporter and magnet frame are merged into a single integrated component. This consolidation eliminates the need for separate support structures and the magnet frame, reducing the total number of parts and the overall weight of the driving assembly while maintaining structural integrity and assembly feasibility.

Inventive Principle:
Principle #5Merging (Combining)

4Productivity

If refrigerant flows directly from the compression space to the discharge cover, then discharge is efficient, but the discharge cover becomes overheated

Engineering Contradiction:
Improvedischarge efficiencyVSAvoiddischarge cover temperature
Core Design Contradiction:
ProductivityVSTemperature

Solution Approach 1:

The discharge plenum is extracted from the discharge cover structure and positioned as a separate component. This allows the discharge function to be separated from the discharge cover, enabling the plenum to handle hot refrigerant while the discharge cover remains cooler and structurally stable.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The discharge plenum is positioned in a different spatial dimension away from the frame and piston-cylinder assembly. By relocating the discharge function to a different spatial location, the patent eliminates the thermal coupling between the discharge cover and the frame, preventing heat conduction to the moving parts.

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 effectively reduces the temperature of the piston and cylinder, prevents overheating, maintains compression efficiency, and allows for higher operating frequencies by minimizing heat transfer and material costs through improved heat dissipation.

Implementation Method 1

The refrigerant gas may function as a gas bearing between the cylinder and the piston to reduce frictional force

Methodology Applied
Scientific EffectGas bearing: Air Lubrication

Implementation Method 2

the permanent magnet is driven to reciprocate linearly by mutual electromagnetic force between the permanent magnet and the inner (or outer) stator

Methodology Applied
Scientific EffectElectromagnetic force: Lorentz Force

Implementation Method 3

heat is transferred to the piston and the cylinder. Then, suction refrigerant flowing into the piston is overheated

Methodology Applied
Scientific EffectHeat conduction: Conduction (thermal)

Implementation Method 4

the heat of the discharge cover is conducted to the frame, and then the heat is transferred from the frame to the piston and the cylinder

Methodology Applied
Scientific EffectHeat conduction: Conduction (thermal)

Data Source

PatentEP3587813B1Reciprocating compressor
Publication Date: 2021.01.27 LG ELECTRONICS INC
  • EP3587813B1 patent drawingFigure 1
  • EP3587813B1 patent drawingFigure 2
  • EP3587813B1 patent drawingFigure 3

AI summary

Disclosed is a linear compressor. The linear compressor according to the spirit of the present invention includes a cylinder forming a compression space for refrigerant and a discharge unit forming a discharge space for refrigerant into which refrigerant discharged from the compression space flows. The discharge unit includes a discharge cover having an inner space formed therein and a discharge plenum placed in the inner space. In this case, the discharge plenum includes a plenum flange extending radially, a plenum seating part, a plenum body, and a plenum extension part which extend from a radially inner side end of the plenum flange, and a plenum guide part extending from a radially outer side end of the plenum flange toward the inner space.