Oldham Coupling Groove Geometry for Scroll Compressor Stress Reduction

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Solution Overview

Problem

The existing Oldham coupling configuration in scroll compressors limits the displacement of compression units, reduces efficiency due to twisting and tipping moments, and is prone to mechanical stress-induced failures due to its low-weight material and projection design.

Innovation Solution

The Oldham coupling features an annular ring with diametrically opposed engaging grooves instead of projections, optimized in depth, width, and angular sectors to reduce mechanical stress and increase space for spiral wraps, made from a more robust material to prevent breaking.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the first, second, third and fourth engaging projections are located diametrically opposed and angularly offset by 90°, then the Oldham coupling can prevent rotation of the orbiting scroll, but this configuration decreases space for the fixed and orbiting spiral wraps and limits the displacement of the compression unit

Engineering Contradiction:

Improverotation preventionVSAvoidspace for spiral wraps

Core Design Contradiction:

ReliabilityVSVolume of moving object

Solution Approach 1:

The patent inverts the conventional design by placing engaging grooves on the Oldham coupling instead of engaging projections. This inversion allows the grooves to be positioned in angular sectors less than 90° apart, optimizing space for spiral wraps while still preventing rotation through the groove-projection engagement mechanism

Inventive Principle:

Principle #13The other way round (Inversion)

Solution Approach 2:

The patent transitions from a two-dimensional radial arrangement (90° offset projections) to a three-dimensional configuration where grooves are positioned in specific angular sectors with varying depths, creating more efficient use of available space while maintaining the rotation prevention function

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

2Reliability

If the first, second, third and fourth engaging projections are located diametrically opposed and angularly offset by 90°, then the Oldham coupling can prevent rotation of the orbiting scroll, but this configuration results in a significant tipping moment that may lead to twisting of the Oldham coupling

Engineering Contradiction:

Improverotation preventionVSAvoidtwisting deformation

Core Design Contradiction:

ReliabilityVSStability of the object's composition

Solution Approach 1:

By inverting the design from projections to grooves, the patent changes the load distribution pattern, reducing the tipping moment and twisting deformation while maintaining the rotation prevention function through groove-projection engagement

Inventive Principle:

Principle #13The other way round (Inversion)

Solution Approach 2:

The patent changes the geometric parameters of the engagement features, specifically positioning grooves in angular sectors less than 90° apart and varying groove depths, which optimizes the load distribution and reduces twisting moments on the Oldham coupling

Inventive Principle:

Principle #35Parameter changes

3Weight of moving object

If the Oldham coupling is made of low weight material such as aluminium, then the Oldham coupling reduces overall weight, but the engaging projections may break under mechanical stresses

Engineering Contradiction:

ImproveOldham coupling weightVSAvoidprojection strength

Core Design Contradiction:

Weight of moving objectVSStrength

Solution Approach 1:

The patent inverts the design from projections to grooves, which fundamentally changes the stress distribution. The groove design eliminates stress concentration at projection tips, preventing breakage while maintaining the lightweight material advantage

Inventive Principle:

Principle #13The other way round (Inversion)

Solution Approach 2:

Inventive Principle:

Principle #35Parameter changes

Data Source

PatentUS10472967B2Oldham coupling for a scroll compressor

Publication Date: 2019.11.12 DANFOSS COMML COMPRESSORS SA

AI summary

An Oldham coupling includes an annular ring having a first side and a second side opposite to the first side, a first and a second engaging groove that are diametrically opposed and located on the first side, and a third and a fourth engaging groove that are diametrically opposed and located on the second side. The first and second engaging grooves are configured to be engaged with a first and a second engaging projection provided on a fixed element. The third and fourth engaging grooves are configured to be engaged with a third and a fourth engaging projection provided on an orbiting scroll. The first and third engaging grooves are located in a first angular sector, and the second and fourth engaging grooves are located in a second diametrically opposed angular sector of the annular ring, the first and second angular sectors have an opening angle less than 40°.