Tolerance Ring Structure for Precise Torque and Overload Protection

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Solution Overview

Problem

Existing tolerance rings struggle to provide precise torque transmission and overload protection within tight torque ranges between inner and outer members, necessitating improved designs for applications requiring precise torque control.

Innovation Solution

The tolerance ring features a design with a cylindrical sidewall that includes wave structures, buckled regions, and a low friction layer, allowing for precise engagement and deformation to accommodate torque variations while preventing relative movement between components.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If a tolerance ring uses a simple band design with projections, then it can transmit torque between inner and outer members, but it cannot provide precise torque control within tight torque ranges

Engineering Contradiction:
Improvetorque precisionVSAvoidring structure complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The tolerance ring is segmented into multiple functional zones along its axial length: a first region with projections for torque transmission, a second region with wave structures for elastic deformation, and a third region with buckled regions for additional compliance. This segmentation allows each zone to perform its specific function, enabling precise torque control while maintaining a relatively simple overall structure.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The tolerance ring incorporates dynamic elements including wave structures that can elastically deform under load and buckled regions that can change configuration. These dynamic features allow the ring to adapt its stiffness and torque transmission characteristics based on the applied load, providing precise torque control within tight ranges while protecting against overloads.

Inventive Principle:
Principle #15Dynamics

2Reliability

If a tolerance ring is designed to provide overload protection within precise torque values, then it can protect assemblies from damage, but it requires complex structures to achieve the precise torque ranges

Engineering Contradiction:
Improveoverload protection reliabilityVSAvoidring structure complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The tolerance ring incorporates wave structures and buckled regions that act as pre-designed compliance elements. These features are built into the ring structure beforehand to absorb excess torque and prevent damage to connected components. The wave structures can elastically deform to cushion sudden torque spikes, while the buckled regions provide additional compliance for overload protection.

Inventive Principle:
Principle #11Beforehand cushioning (Prior cushioning)

Solution Approach 2:

The tolerance ring utilizes changes in material and structural parameters along its length to achieve different torque characteristics. The transition from a rigid first region with projections to a more compliant second region with wave structures and third region with buckled regions creates a gradient of stiffness parameters. This allows the ring to transmit precise torque values in the first region while providing progressive compliance in subsequent regions for overload protection.

Inventive Principle:
Principle #35Parameter changes

3Strength

If a tolerance ring uses projections to span the radial gap and transmit forces, then it can connect inner and outer members, but it generates high friction that affects operational stability

Engineering Contradiction:
Improveforce transmission capabilityVSAvoidfriction
Core Design Contradiction:
StrengthVSObject-generated harmful factors

Solution Approach 1:

The tolerance ring separates the force transmission function from the low-friction interface function by dividing the ring into distinct regions. The first region with projections handles force transmission between inner and outer members, while the second and third regions with wave structures and buckled regions provide compliance and reduce friction through elastic deformation rather than sliding contact.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The wave structures in the second region and buckled regions in the third region act as flexible elements that can elastically deform to accommodate radial gaps and misalignments. This flexibility allows the ring to transmit forces while reducing friction compared to rigid projections that would require sliding contact, thereby improving operational stability.

Inventive Principle:
Principle #30Flexible shells and thin films

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 torque transmission precision and overload protection by allowing elastic deformation and interference fits, providing stable interconnection and reducing friction, thus improving the assembly's operational stability and durability.

Implementation Method 1

a low friction layer, allowing for precise engagement and deformation

Methodology Applied
Scientific EffectFriction reduction: Lubrication

Implementation Method 2

allowing elastic deformation and interference fits, providing stable interconnection

Methodology Applied
Scientific EffectElastic deformation: Elasticity

Data Source

PatentEP3688330B1Tolerance ring
Publication Date: 2025.12.10 SAINT GOBAIN PERFORMANCE PLASTICS RENCOL LIMITED
  • EP3688330B1 patent drawingFigure 1A~1B
  • EP3688330B1 patent drawingFigure 2
  • EP3688330B1 patent drawingFigure 3

AI summary

An assembly including an outer member; an inner member; and a tolerance ring disposed between the inner member and the outer member, wherein the tolerance ring is a split ring comprising opposing edges, where the edges engaged with at one of the inner member or the outer member so as to prevent or restrict movement between the tolerance ring and at least one of the inner member or the outer member, or where the tolerance ring is deformed as installed between the inner member and the outer member and forms at least one buckled region in the tolerance ring due to an interference fit between the inner member and the outer member, where in an uninstalled state, the buckled region is absent.