Thermal Expansion Sleeve for Reciprocating Compressor Assembly

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Solution Overview

Problem

In reciprocating compressors, the process of press-fitting a sleeve between the connecting rod and crankshaft is challenging due to deformation issues, leading to increased frictional losses and abrasion of the crankshaft, as the sleeve is often made from the same material as the connecting rod, resulting in a difficult assembly and higher motor input loads.

Innovation Solution

A sleeve with a thermal expansion coefficient higher than the connecting rod, having an outer diameter smaller than the inner diameter of the connecting rod, is used to facilitate assembly and prevent deformation, thereby reducing frictional losses and abrasion by allowing non-press-fitting and thermal expansion alignment.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the sleeve is made from the same material as the connecting rod and press-fitted, then the assembly is secure, but the assembly process is difficult and deformation occurs

Engineering Contradiction:

Improveassembly securityVSAvoidassembly difficulty

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The patent changes the material parameter (thermal expansion coefficient) of the sleeve from being the same as the connecting rod to being different (higher). This parameter change enables thermal expansion-based assembly, where the sleeve is heated to expand, inserted into the connecting rod, and then contracts upon cooling to secure the assembly without press-fitting deformation

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent directly applies thermal expansion by selecting a sleeve material with a higher thermal expansion coefficient than the connecting rod. The sleeve is heated during assembly to expand its dimensions for easy insertion, and upon cooling, it contracts to firmly secure itself in the connecting rod without requiring forceful press-fitting that causes deformation

Inventive Principle:

Principle #37Thermal expansion

2Strength

If the sleeve is press-fitted into the connecting rod, then the connection is firm, but frictional loss increases and motor input load increases

Engineering Contradiction:

Improveconnection firmnessVSAvoidmotor input load

Core Design Contradiction:

StrengthVSUse of energy by moving object

Solution Approach 1:

The patent uses thermal expansion to achieve firm connection without press-fitting. The sleeve is heated to expand, inserted into the connecting rod, and upon cooling contracts to create a secure interference fit. This thermal-based assembly eliminates the need for forceful press-fitting, reducing frictional losses and motor input load while maintaining connection firmness

Inventive Principle:

Principle #37Thermal expansion

3Stability of the object's composition

If the sleeve material has the same thermal expansion coefficient as the connecting rod, then thermal compatibility is achieved, but assembly deformation occurs

Engineering Contradiction:

Improvethermal compatibilityVSAvoidsleeve roundness

Core Design Contradiction:

Stability of the object's compositionVSManufacturing precision

Solution Approach 1:

The patent intentionally changes the thermal expansion coefficient parameter of the sleeve material to be different (higher) from the connecting rod. This parameter change enables thermal expansion-based assembly, where the sleeve is heated to expand for easy insertion without deformation, and upon cooling contracts to secure the assembly while maintaining manufacturing precision

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent applies thermal expansion by heating the sleeve during assembly to expand its dimensions, allowing easy insertion into the connecting rod without deformation. Upon cooling, the sleeve contracts to firmly secure itself while maintaining its roundness and manufacturing precision, avoiding the deformation issues associated with press-fitting

Inventive Principle:

Principle #37Thermal expansion

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 solution simplifies the assembly process, prevents sleeve deformation, reduces motor input loads, and minimizes crankshaft abrasion by ensuring a stable interface between the sleeve and connecting rod, even under varying temperatures.

Implementation Method 1

the sleeve is formed of a material different from the connecting rod, the material having a thermal expansion coefficient higher than that of the connecting rod

Methodology Applied

Scientific EffectThermal expansion: Thermal Expansion

Data Source

PatentUS8776669B2Anti-abrasion device and reciprocating compressor having the same

Publication Date: 2014.07.15 LG ELECTRONICS INC

AI summary

Disclosed are an anti-abrasion device and a reciprocating compressor having the same, whereby a sleeve is fabricated with an outer diameter smaller than an inner diameter of a connecting rod to be non-press-fitted, thereby facilitating an assembly of the sleeve, and also the deformation of an inner diameter of the sleeve is prevented during the assembly of the sleeve, thereby preventing beforehand an increase in an input load of a motor unit due to the deformation of the sleeve and an abrasion of a pin of a crankshaft.