Asymmetric Elastomeric Damping Ring for Oil-Resistant Belt Tensioner
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Solution Overview
Problem
Existing tensioners face challenges in maintaining proper belt tension and synchronization between the camshaft and crankshaft in an oil environment, as oil presence complicates friction damping, leading to issues like 'tooth jump' or 'ratcheting' and reduced component lifespan due to excessive vibration.
Innovation Solution
A tensioner design incorporating an elastomeric damping ring with a friction force and a retaining member connected to an adjuster and sleeve, providing asymmetric damping to resist motion away from the belt while allowing motion towards it, utilizing a torsion spring and pulley system for precise tensioning and vibration reduction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If friction damping is used to prevent excessive tensioner arm motion, then vibration is reduced and synchronization is maintained, but the presence of oil reduces friction effectiveness allowing excessive motion to occur
Solution Approach 1:
The patent changes the physical state of the friction interface by introducing an elastomeric material that maintains high friction coefficients in the presence of oil. The elastomeric material's viscoelastic properties allow it to generate friction damping forces that are not significantly degraded by oil contamination, thereby maintaining reliable synchronization despite the harmful presence of oil.
Solution Approach 2:
The patent employs composite material construction by combining metal components with an elastomeric friction element. This composite approach allows the system to leverage the structural strength of metal while utilizing the oil-resistant friction characteristics of the elastomeric material, resolving the contradiction between reliability and oil interference.
2Reliability
If symmetric friction damping is applied to resist all arm motion, then vibration is minimized, but the tensioner cannot properly tension the belt during installation and adjustment
Solution Approach 1:
The patent implements asymmetric friction damping where the elastomeric friction element is positioned and dimensioned to provide friction resistance only during the outward motion of the tensioner arm (when moving away from the belt). During inward motion (when moving toward the belt for tensioning), the friction element allows free movement. This asymmetric design resolves the contradiction by providing vibration reduction in one direction while maintaining ease of operation in the opposite direction.
Solution Approach 2:
The friction damping system is designed to be dynamic rather than static, with the elastomeric element engaging friction only under specific motion conditions. The system automatically adapts its friction characteristics based on the direction and nature of arm motion, providing damping when needed and freedom of movement when needed for installation and adjustment.
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 effectively maintains belt tension and synchronization, reducing 'tooth jump' and vibration-induced wear, while operating efficiently in an oil environment by generating asymmetric damping that adapts to changing belt loads, thus enhancing the lifespan of the tensioner and belt.
Implementation Method 1
an elastomeric damping ring friction element having a friction force and a retaining member connected to an adjuster and cooperatively engaged with the sleeve whereby the adjuster and sleeve are kept in a predetermined relation
Data Source
AI summary
A tensioner comprising a sleeve, an adjuster cooperatively engaged with an inner surface of the sleeve, a pivot arm pivotally engaged with the sleeve, a pulley journalled to the pivot arm, a torsion spring engaged with the sleeve for urging the pivot arm, an elastomeric damping ring connected to the arm and in compressive frictional contact between the sleeve and the arm whereby a tangential friction force damps a pivot arm movement, the elastomeric damping ring exerting a radial force on the sleeve, and a retaining member connected to the adjuster and cooperatively engaged with the sleeve whereby the adjuster and sleeve are kept in a predetermined relation.