Toothed Belt Drive Compression Span Design

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Solution Overview

Problem

Conventional synchronous belt drives face challenges in achieving optimal initial installation tension, leading to poor drive efficiency and noise issues, especially in high-torque applications like dry transfer cases, where the belt may jump teeth or experience noise due to the lack of bending stiffness in flexible chain links.

Innovation Solution

A toothed belt drive design where the drive length is less than the belt length, forming a free-standing arcuate span between sprockets, utilizing stationary linear guides made of low-friction materials to achieve stable backward buckling and reduce initial tension, with the difference in belt and drive length determining the concave arc formation and stability.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If high initial tension is used to prevent belt jump under high torque, then reliability is improved, but drive efficiency deteriorates and noise increases

Engineering Contradiction:
Improvebelt tooth engagement stabilityVSAvoiddrive efficiency
Core Design Contradiction:
ReliabilityVSLoss of energy

Solution Approach 1:

The invention changes the physical state of the belt span from tensioned to compressed, allowing the belt to buckle backward and form an arc shape. This parameter change enables the system to accommodate torque variations without requiring high initial tension, thereby maintaining reliability while improving drive efficiency and reducing noise

Inventive Principle:
Principle #35Parameter changes

2Reliability

If high initial tension is used to prevent belt jump under high torque, then reliability is improved, but noise increases

Engineering Contradiction:
Improvebelt tooth engagement stabilityVSAvoidbelt noise
Core Design Contradiction:
ReliabilityVSObject-generated harmful factors

Solution Approach 1:

The invention changes the physical state of the belt span from tensioned to compressed, allowing the belt to buckle backward and form an arc shape. This parameter change enables the system to accommodate torque variations without requiring high initial tension, thereby maintaining reliability while improving drive efficiency and reducing noise

Inventive Principle:
Principle #35Parameter changes

3Loss of energy

If belt length is made longer than drive length to enable backward buckling, then drive efficiency is improved, but device complexity increases

Engineering Contradiction:
Improvedrive efficiencyVSAvoidbelt span configuration
Core Design Contradiction:
Loss of energyVSDevice complexity

Solution Approach 1:

The invention employs stationary linear guides that require no actuation or control. The guides passively enable the belt to buckle backward and form a stable arc shape under compression, allowing the system to self-regulate torque variations without complex control mechanisms, thereby improving drive efficiency while maintaining simplicity

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 enhances drive efficiency and reduces noise by allowing a stable concave arc formation without continuous mechanical contact, improving belt life and operational stability under varying torque conditions.

Implementation Method 1

The concept of using belt backward buckling to achieve the zero tension drive has been explored in the prior art. The idea is to use a belt pitch length longer than the drive length, and let the belt buckle backward on the slack side span.

Methodology Applied
Scientific EffectBuckling:

Implementation Method 2

A toothed belt drive with a compression span, and more particularly, to a toothed belt drive having a drive length which is less than a toothed belt length such that the toothed belt forms a free-standing arcuate span between the first sprocket and the second sprocket on a toothed belt compression span

Methodology Applied
Scientific EffectCompression: Compression

Data Source

PatentEP3194806B1Belt drive with compression span
Publication Date: 2018.10.03 THE GATES CORP
  • EP3194806B1 patent drawingFigure 1
  • EP3194806B1 patent drawingFigure 2
  • EP3194806B1 patent drawingFigure 3

AI summary

A toothed belt drive with compression span comprising a first sprocket, a second sprocket, a toothed belt having a toothed belt length and trained between the first sprocket and the second sprocket, a first linear guide member in cooperative relation to and disposed a predetermined distance (B) from the toothed belt, a second linear guide member in cooperative relation to and disposed a predetermined distance (B) from the toothed belt, and the toothed belt length greater than a drive length such that the toothed belt forms a free-standing arcuate span between the first sprocket and the second sprocket on a toothed belt compression span.