Piston for compressor

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Solution Overview

Problem

Existing linear compressors face issues with unnecessary space occupation, labor costs, and potential refrigerant leakage due to the need for separate surface treatments and press-fitting processes, which can lead to assembly tolerances and reduced compression efficiency.

Innovation Solution

A piston design where only the bearing portion is surface-treated and coupled to the head and flange portions through a bonding process, eliminating the need for separate jigs and reducing the risk of plasma interference, and using adhesives like anaerobic or epoxy to prevent gaps and enhance abrasion resistance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If the piston is made as an integral structure with flange and bearing portions, then structural strength is improved, but unnecessary space is occupied in coating equipment and labor costs increase

Engineering Contradiction:
Improvestructural strengthVSAvoidlabor costs and time
Core Design Contradiction:
StrengthVSLoss of time

Solution Approach 1:

The piston is divided into separate components: a piston body and a bearing portion. The bearing portion is detached from the piston body and processed separately, allowing the piston body to be coated without the flange portion interfering with the coating equipment. This segmentation reduces unnecessary space occupation in coating equipment and decreases labor costs.

Inventive Principle:
Principle #1Segmentation

2Reliability

If the flange portion is included in the coating process, then complete surface treatment is achieved, but plasma interference occurs at the boundary between bearing and flange portions

Engineering Contradiction:
ImproveDLC coating propertiesVSAvoidplasma interference
Core Design Contradiction:
ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The flange portion is extracted or separated from the piston body before the coating process. Only the piston body undergoes the DLC coating treatment, which eliminates the plasma interference problem that would occur at the boundary between the bearing portion and flange portion during coating.

Inventive Principle:
Principle #2Taking out (Extraction)

3Ease of manufacture

If press-fitting is used to couple the bearing portion to the piston body, then assembly is achieved, but the bearing portion may be damaged and fine gaps occur leading to refrigerant leakage

Engineering Contradiction:
Improveassembly processVSAvoidcompression efficiency
Core Design Contradiction:
Ease of manufactureVSReliability

Solution Approach 1:

The mechanical press-fitting process is replaced with a bonding process. The bearing portion is bonded to the piston body using adhesive material, which eliminates the damage risk to the bearing portion and prevents fine gaps that would cause refrigerant leakage, thereby maintaining compression efficiency.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

4Strength

If separate surface treatment is performed on the bearing portion, then abrasion resistance is improved, but manufacturing complexity and costs increase

Engineering Contradiction:
Improveabrasion resistanceVSAvoidmanufacturing process complexity
Core Design Contradiction:
StrengthVSDevice complexity

Solution Approach 1:

The surface treatment (DLC coating) is applied locally only to the bearing portion where abrasion resistance is needed, rather than treating the entire piston assembly. This localized approach improves abrasion resistance at the critical interface with the cylinder while avoiding the complexity of treating the entire integral structure.

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 design simplifies the manufacturing process, reduces costs, and maintains high compression efficiency by preventing refrigerant leakage and improving abrasion resistance, while avoiding the complexities of press-fitting and plasma interference.

Implementation Method 1

the bearing surface is subjected to a surface treatment to improve abrasion resistance

Methodology Applied
Scientific EffectSurface treatment: Deposition (physical)

Implementation Method 2

The bearing portion is coupled to the head portion and the flange portion through bonding

Methodology Applied
Scientific EffectAdhesive bonding: Adhesive

Data Source

PatentEP3835580B1Piston for compressor
Publication Date: 2022.03.30 LG ELECTRONICS INC
  • EP3835580B1 patent drawingFigure 1
  • EP3835580B1 patent drawingFigure 2
  • EP3835580B1 patent drawingFigure 3~4

AI summary

A piston (200) for a refrigerant compressor includes: a bearing portion (220) having a cylindrical shape to define a suction space (222) into which the suctioned refrigerant is accommodated therein, the bearing portion being provided with a bearing surface (221) facing an inner circumferential surface of the cylinder; a head portion (210) coupled to a front opening of the bearing portion (220) and provided with a plurality of suction ports (211a) which communicate with the suction space (222), the head portion (210) having a compression surface (211) configured to face a compression space to compress the refrigerant in the compression space; and a flange portion (230) coupled to a rear opening of the bearing portion (220) and provided with a through-passage (234) through which the refrigerant is introduced from a muffler unit to the suction space (222), the flange portion (230) being coupled to a driving portion to transmit driving force to the piston (200). The bearing surface (221) is subjected to a surface treatment to improve abrasion resistance.