Tapered Joint Assembly With Adjustable Friction Torque

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Solution Overview

Problem

Rotary joint assemblies in applications like bicycle frames face issues with looseness, weight, packaging, and torque variability due to wear and temperature sensitivity, especially when using ball bearings or plain bearing rotary joints, leading to performance degradation and complexity.

Innovation Solution

A joint assembly design featuring a shaft and housing with tapered surfaces and a polymer layer to adjust torque and frictional fit, allowing for customizable torque transmission and improved stability through a connecting component and spring element, which enhances axial positioning and biasing force.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Speed

If ball bearings are used in rotary joint assemblies, then rotational smoothness is improved, but packaging space and weight increase

Engineering Contradiction:

Improverotational smoothnessVSAvoidpackaging space

Core Design Contradiction:

SpeedVSVolume of moving object

Solution Approach 1:

The patent extracts and eliminates the ball bearing component from the rotary joint assembly, replacing it with a plain bearing design that achieves rotational smoothness through a different mechanism (tapered surface geometry) without requiring the additional space and complexity of ball bearings

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent substitutes the ball bearing mechanical system with a plain bearing system that uses tapered surfaces to achieve the same rotational function, replacing a complex mechanical component with a simpler geometric solution

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Volume of moving object

If plain bearing rotary joints are used, then packaging space is reduced, but looseness and radial/axial free-play increase

Engineering Contradiction:

Improvepackaging spaceVSAvoidtolerance performance

Core Design Contradiction:

Volume of moving objectVSReliability

Solution Approach 1:

The patent employs tapered (curved) surfaces instead of flat or cylindrical surfaces, using the geometric curvature to naturally guide and constrain the rotational movement, eliminating free-play while maintaining compact dimensions

Inventive Principle:

Principle #14Spheroidality (Curvature)

Solution Approach 2:

The patent changes the geometric parameters of the bearing surfaces by introducing taper angles, which fundamentally alters the contact mechanics and eliminates the looseness and free-play problems associated with conventional plain bearings

Inventive Principle:

Principle #35Parameter changes

3Device complexity

If conventional joint assembly components are used, then assembly is simple, but torque variability due to wear and abrasion increases

Engineering Contradiction:

Improveassembly simplicityVSAvoidtorque consistency

Core Design Contradiction:

Device complexityVSReliability

Solution Approach 1:

The patent applies a polymer coating layer on the bearing surfaces, creating a composite structure that combines the structural integrity of the base material with the low-friction, wear-resistant properties of the polymer, thereby maintaining torque consistency over time

Inventive Principle:

Principle #40Composite materials

Solution Approach 2:

The patent substitutes conventional metal-to-metal contact with polymer-coated surfaces, replacing the wear-prone mechanical interface with a low-friction, self-lubricating surface that resists wear and abrasion

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

4Adaptability or versatility

If adjustable torque mechanisms are added, then torque control is improved, but device complexity increases

Engineering Contradiction:

Improvetorque adjustabilityVSAvoidassembly complexity

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent introduces a spring element that provides dynamic, adjustable axial positioning of the shaft, allowing torque control through the elastic deformation of the spring without requiring complex mechanical adjustment mechanisms

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The spring element automatically adjusts the axial position and torque characteristics based on operating conditions, providing self-regulating torque control without requiring external adjustment mechanisms or complex control systems

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

The solution provides a compact, durable, and low-friction joint assembly with adjustable torque, reducing wear and temperature sensitivity, resulting in improved stiffness, noise reduction, and extended lifespan while offering space and weight savings.

Implementation Method 1

Methodology Applied

Scientific EffectSpring force: Spring

Implementation Method 2

A joint assembly design featuring a shaft and housing with tapered surfaces and a polymer layer to adjust torque and frictional fit

Methodology Applied

Scientific EffectFriction: Friction

Data Source

PatentEP3612440B1Adjustable joint assembly

Publication Date: 2023.08.23 SAINT GOBAIN PERFORMANCE PLASTICS RENCOL LIMITED

AI summary

A joint assembly including a housing including an inner diameter portion having a tapered surface; and at least one shaft having an outer diameter portion having a tapered surface that is complementary in shape to the inner diameter portion of the housing, where the shaft is adapted to rotate relative to the housing, and where the frictional fit is adjustable by modifying the axial position of the shaft relative to the housing.