Tolerance Ring Engagement Structure for Weld-Free Interference Fits

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Solution Overview

Problem

Existing tolerance rings for compressor motors face challenges in achieving precise interference fits and secure assembly without the need for welding, especially in applications where close tolerances and thermal expansion compensation are critical.

Innovation Solution

The proposed tolerance ring design incorporates a plurality of wave structures and component engagement structures that engage both the inner and outer components, allowing for secure locking without welding. The ring is installed around an inner component, and as the outer component cools and shrinks, the compressive force engages the component engagement structures, ensuring a stable interference fit.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If very close tolerances are required for press fits and splines to transmit torque, then torque transmission reliability is improved, but manufacturing costs increase

Engineering Contradiction:
Improvetorque transmission reliabilityVSAvoidmanufacturing cost
Core Design Contradiction:
ReliabilityVSEase of manufacture

Solution Approach 1:

The tolerance ring is segmented into multiple protrusions that can be independently formed, allowing the interference fit function to be distributed across multiple contact points rather than requiring a single precision-machined surface. This segmentation enables the use of less precise machining while maintaining reliable torque transmission.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The tolerance ring acts as an intermediary component between the shaft and the housing bore. Instead of requiring direct precision fit between shaft and housing, the tolerance ring mediates the connection, absorbing dimensional variations and providing reliable torque transmission through its resilient protrusions.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Manufacturing precision

If tolerance rings are used to provide interference fit between parts, then manufacturing precision requirements are reduced, but the complexity of the assembly increases

Engineering Contradiction:
Improvedimensional toleranceVSAvoidassembly complexity
Core Design Contradiction:
Manufacturing precisionVSDevice complexity

Solution Approach 1:

The tolerance ring is formed from a resilient material strip that is curved into a ring shape, creating a flexible structure that can elastically deform during assembly. This flexibility allows the ring to be installed on the shaft and then compressed by the housing bore, creating the interference fit without requiring complex assembly mechanisms.

Inventive Principle:
Principle #30Flexible shells and thin films

Solution Approach 2:

The tolerance ring is formed by curving a strip into an annular shape with overlapping ends. This curvature provides the necessary elastic compliance for the ring to deform during assembly and maintain continuous contact with both the shaft and housing bore, simplifying the assembly process while maintaining precision.

Inventive Principle:
Principle #14Spheroidality (Curvature)

3Ease of operation

If a tolerance ring is installed around an inner component and the outer component is heated and expanded, then assembly ease is improved, but the need for thermal processing increases

Engineering Contradiction:
Improveassembly easeVSAvoidthermal processing requirement
Core Design Contradiction:
Ease of operationVSDevice complexity

Solution Approach 1:

The assembly process utilizes thermal expansion and contraction phase transitions of the outer component. By heating the outer component to expand it, the tolerance ring can be installed around the inner component without excessive force. Upon cooling, the outer component contracts, creating the interference fit and securing the assembly.

Inventive Principle:
Principle #36Phase transitions

4Reliability

If welding operations are eliminated to secure components, then manufacturing precision and durability are improved, but alternative securement mechanisms are required

Engineering Contradiction:
Improveassembly durabilityVSAvoidsecurement mechanism complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The tolerance ring provides self-service securement through its resilient protrusions that automatically engage with both the shaft and housing bore upon assembly. The elastic deformation of the ring during installation creates the interference fit without requiring external welding or additional fastening mechanisms, maintaining durability while simplifying the overall assembly process.

Inventive Principle:
Principle #25Self-service

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 effectively secures compressor components within the housing without welding, providing a stable and precise interference fit that compensates for thermal expansion, thus enhancing the durability and assembly efficiency of compressor motors.

Implementation Method 1

the wave structures of the tolerance ring can be caused to expand radially outward by compressing the tolerance ring in an axial direction

Methodology Applied
Scientific EffectPoisson's Effect: Poisson's Effect

Implementation Method 2

As the compressor housing cools and shrinks, the inner wall of the contracting compressor housing can apply a compressive force on the wave structures of the tolerance ring

Methodology Applied
Scientific EffectThermal Contraction: Thermal Contraction

Data Source

PatentEP2867552B1Tolerance ring with component engagement structures
Publication Date: 2025.04.23 SAINT GOBAIN PERFORMANCE PLASTICS RENCOL LIMITED
  • EP2867552B1 patent drawingFigure 1
  • EP2867552B1 patent drawingFigure 2
  • EP2867552B1 patent drawingFigure 3~5

AI summary

A tolerance ring (200) is disclosed and can include a generally cylindrical body (202) having a side wall (204) that defines a top (206), and a bottom (208). The side wall includes a plurality of wave structures (220) that extend from the sidewall in a first direction and a first plurality of component engagement structures (230) that extend from the sidewall in a second direction opposite the first direction. Each of the first plurality of component engagement structures can be configured to at least partially extend into and engage a first component to which the tolerance ring is assembled.