Compressor Shoe Recess Radius for Oil Film Stability

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Solution Overview

Problem

Conventional compressor shoes with acute-angled edges or recesses can break the oil film, reducing seizure resistance between the shoe and swash plate.

Innovation Solution

A compressor shoe design featuring a second sliding face with a recess and rounded connecting portions with radii greater than 5 mm, facilitating oil film formation and preventing film obstruction.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a recess is formed in the sliding face of the shoe to retain lubricant, then seizure resistance is improved, but the oil film may break due to acute-angled edges at the connecting portions

Engineering Contradiction:
Improveseizure resistanceVSAvoidoil film breaking
Core Design Contradiction:
ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The connecting portions between the recess and the sliding face, and between the sliding faces, are formed with rounded shapes having radii larger than 5 mm. This curvature eliminates acute-angled edges that would otherwise break the oil film, while the recess continues to retain lubricant for improved seizure resistance.

Inventive Principle:
Principle #14Spheroidality (Curvature)

Solution Approach 2:

The radius of the connecting portions is specifically designed to be larger than 5 mm, creating a favorable curvature radius that prevents oil film breaking. This parameter change transforms the geometric characteristics of the connecting portions from acute-angled to smoothly rounded, resolving the contradiction between lubricant retention and oil film integrity.

Inventive Principle:
Principle #35Parameter changes

2Reliability

If the connecting portion is formed with a small radius to reduce material, then manufacturing cost is reduced, but the oil film formation is obstructed and seizure resistance decreases

Engineering Contradiction:
Improveseizure resistanceVSAvoidmaterial usage
Core Design Contradiction:
ReliabilityVSEase of manufacture

Solution Approach 1:

The radius of the connecting portions is set to a specific range (greater than 5 mm) to optimize both seizure resistance and manufacturing efficiency. This parameter specification ensures adequate oil film formation while maintaining reasonable material usage and manufacturability.

Inventive Principle:
Principle #35Parameter changes

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

The design enhances seizure resistance by maintaining a stable oil film between the shoe and swash plate, as evidenced by increased seizure load measurements when radii exceed 5 mm.

Implementation Method 1

a shoe for a compressor with improved seizure resistance... oil film formation between the shoe and the swash plate... the edge may break an oil film

Methodology Applied
Scientific EffectLubrication: Lubrication

Implementation Method 2

a recess is formed in the sliding face of the shoe. These shoes can retain lubricant in the hole or recess

Methodology Applied
Scientific EffectCapillary action: Capillary Action

Data Source

PatentEP3521615B1Compressor shoe
Publication Date: 2022.11.02 TAIHO KOGYO CO LTD
  • EP3521615B1 patent drawingFigure 1
  • EP3521615B1 patent drawingFigure 2(a)~2(b)
  • EP3521615B1 patent drawingFigure 3

AI summary

There is provided a shoe for a compressor with improved seizure resistance. The shoe for the compressor includes: a first sliding face 51 that slides on a piston 4; a second sliding face 52 that slides on a swash plate 3; and a recess 53 formed in the second sliding face 52. In a section along a height direction and scaled up 1000 times in the height direction and 10 times in a radial direction, a connecting portion 55 between the second sliding face 52 and the recess 53 is formed in a rounded shape with a radius R2 larger than 5 mm.