Tensioner Arm Vibration Control via Dual Damping

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Solution Overview

Problem

Timing belts require precise tensioning to maintain synchronization between camshafts and crankshafts, and existing solutions face challenges in achieving effective friction damping in an oil environment, which can lead to tooth jump or ratcheting and reduced component lifespan due to excessive arm vibration.

Innovation Solution

A tensioner design featuring a first and second damping member with relative axial movement capability, utilizing a compressible member to separate and apply a normal force between them, along with a torsion spring and wave spring configuration to minimize arm oscillation and maintain belt tension.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Stability of the object's composition

If friction damping is applied to minimize arm vibration, then arm oscillation is reduced, but the presence of oil reduces friction effectiveness causing excessive arm motion

Engineering Contradiction:

Improvearm vibration controlVSAvoidfriction damping effectiveness

Core Design Contradiction:

Stability of the object's compositionVSReliability

Solution Approach 1:

The patent employs composite damping members comprising friction materials with specific properties that maintain effective friction coefficients in the presence of oil. The damping members are constructed with materials that resist oil degradation, ensuring reliable friction damping performance in the oil environment where conventional friction materials would fail.

Inventive Principle:

Principle #40Composite materials

Solution Approach 2:

The invention changes the physical and chemical parameters of the friction surfaces by selecting materials with specific friction characteristics that remain effective when exposed to oil. The damping members are designed with controlled friction coefficients that maintain adequate damping force despite the lubricating effect of oil, resolving the contradiction between friction effectiveness and oil presence.

Inventive Principle:

Principle #35Parameter changes

2Reliability

If belt tension is increased to prevent tooth jump, then synchronization is maintained, but excessive tension increases arm vibration and reduces component lifespan

Engineering Contradiction:

Improvesynchronization maintenanceVSAvoidarm vibration

Core Design Contradiction:

ReliabilityVSStability of the object's composition

Solution Approach 1:

The damping members act as intermediaries between the belt tensioning system and the arm pivot point. They absorb and dissipate the vibrational energy generated by belt tension fluctuations, allowing the system to maintain adequate belt tension for synchronization while reducing the transmission of excessive vibrational forces to the arm and surrounding components.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Stability of the object's composition

If damping force is increased to control arm motion, then arm oscillation is reduced, but excessive damping force increases friction and heat generation

Engineering Contradiction:

Improvearm oscillation controlVSAvoidfriction energy loss

Core Design Contradiction:

Stability of the object's compositionVSLoss of energy

Solution Approach 1:

The damping members are designed to provide partial damping action rather than excessive damping. The friction surfaces are configured to generate just enough damping force to control arm oscillation within acceptable limits without over-damping the system. This partial action approach prevents excessive energy loss while maintaining adequate vibration control.

Inventive Principle:

Principle #16Partial or excessive action

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 reduces arm vibration and maintains belt tension, preventing tooth jump and ratcheting, while ensuring the tensioner and belt longevity by using frictional damping in an oil environment.

Implementation Method 1

a compressible member disposed therebetween urging apart the first damping member and the second damping member

Methodology Applied

Scientific EffectElasticity: Elasticity

Implementation Method 2

The first damping member frictionally engaged with the base and engaged with first receiving portion

Methodology Applied

Scientific EffectFriction: Friction

Data Source

PatentUS9618098B2Tensioner

Publication Date: 2017.04.11 THE GATES CORP

AI summary

A tensioner comprising a base, a shaft connected to the base, an eccentric adjuster coaxially engaged with the shaft, an arm pivotally engaged with the shaft, a pulley journalled to the arm, a torsion spring engaged between the arm and the base, the arm comprising a first receiving portion and a second receiving portion disposed axially opposite from the first receiving portion, a first damping member disposed between the arm and the base, the first damping member frictionally engaged with the base and engaged with first receiving portion, a second damping member disposed between the arm and the eccentric adjuster having a member engaged with the second receiving portion, and a biasing member disposed between the first damping member and the arm for applying a normal force to the first damping member and to the second damping member.