Series Spring Blade Tensioner for Uniform Chain Load

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Conventional blade spring tensioners face issues with maintaining sufficient tensioning load as chains wear, leading to rapid load decrease due to high system spring rate sensitivity to deflection, resulting in increased frictional losses and noise.

Innovation Solution

A blade shoe assembly with parallel stacked blade springs that pivots at one end and is supported in series by a spring-loaded ramp, reducing overall stiffness and providing a more uniform tensioning load as the tensioner takes up chain slack.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Force

If a high system spring rate is used to develop sufficient tensioning load in a compact package, then the tensioning load is adequate for new chains, but the tensioning load decreases too rapidly as the blade assembly deflects to take up chain slack

Engineering Contradiction:

Improvetensioning loadVSAvoidtensioning load maintenance

Core Design Contradiction:

ForceVSDuration of action of moving object

Solution Approach 1:

The tensioner system is segmented into two separate spring elements: a blade spring for initial tensioning and a ramp spring for maintaining tension during deflection. This segmentation allows each spring to be optimized for its specific function, resolving the contradiction between achieving high initial tension and maintaining tension over displacement.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The system transitions from a static high spring rate to a dynamic two-spring system where the ramp spring progressively engages as the blade deflects. This dynamic configuration allows the effective spring rate to change during operation, maintaining adequate tension throughout the chain's wear cycle.

Inventive Principle:

Principle #15Dynamics

2Force

If the tensioning load is increased for new chains to achieve minimum acceptable load, then adequate tension is maintained, but frictional losses, chain engagement noise and blade shoe and chain wear increase

Engineering Contradiction:

Improvetensioning loadVSAvoidfrictional losses

Core Design Contradiction:

ForceVSLoss of energy

Solution Approach 1:

The system changes the effective spring rate parameter during operation. The blade spring provides high initial tension with controlled deflection, while the ramp spring provides progressive tension as needed. This parameter change allows adequate tension maintenance without the continuously high loads that cause frictional losses and wear.

Inventive Principle:

Principle #35Parameter changes

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 ensures a more consistent tensioning load across the lifespan of the chain, reducing wear and noise while maintaining adequate tension without excessive initial tensioning loads.

Implementation Method 1

A blade shoe assembly with parallel stacked blade springs that pivots at one end

Methodology Applied

Scientific EffectElasticity: Elasticity

Implementation Method 2

supported in series by a spring loaded ramp at the opposite end

Methodology Applied

Scientific EffectElasticity: Elasticity

Data Source

PatentUS8057333B2Series spring blade tensioner

Publication Date: 2011.11.15 BORGWARNER INC

AI summary

A blade tensioner includes a blade shoe assembly with parallel stacked flat springs that pivots at one end and is supported in series by a spring loaded ramp at the opposite end. Providing a spring loaded ramp in series reduces the overall stiffness of the tensioner which enables a more uniform tensioning load as the tensioner takes up chain slack due to elongation from wear.