Segmented Spring Tensioner With Polymeric Damping
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Solution Overview
Problem
Existing tensioners lack sufficient damping to prevent sudden increases in belt tension from causing catastrophic failure, particularly in demanding applications where the tensioner arm is thrown off the belt, leading to potential engine failure due to insufficient frictional torque.
Innovation Solution
A tensioner design incorporating a spring support with multiple axially spaced segments that engage a damping element, providing increased frictional torque and damping through a polymeric bushing plate and additional friction sources, allowing for longer tensioner arms and improved stability in belt tension control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a typical prior art tensioner is used, then the device complexity is low, but the damping is insufficient to prevent sudden increases in belt tension from causing catastrophic failure
Solution Approach 1:
The spring support is divided into multiple axially spaced segments (first segment, second segment, third segment) that can independently engage with the damping element. This segmentation allows each segment to contribute to frictional torque generation, increasing overall damping capability while maintaining a modular structure that does not significantly increase device complexity
Solution Approach 2:
A damping element (polymeric bushing plate) is introduced as an intermediary component between the spring support segments and the tensioner arm. This damping element provides a controlled friction interface that generates the necessary frictional torque to dampen sudden belt tension increases, thereby improving reliability without requiring fundamental changes to the tensioner architecture
2Stability of the object's composition
If the tensioner arm length is increased to improve stability, then the belt tension control stability is improved, but the damping is insufficient and the tensioner arm is thrown off the belt
Solution Approach 1:
The multiple spring support segments are pre-configured to engage the damping element before any sudden belt tension increase occurs. This preliminary engagement ensures that the frictional torque mechanism is already in place and active, providing immediate resistance to sudden tension increases and preventing the tensioner arm from being thrown off the belt
Solution Approach 2:
The damping element is made from polymeric material (bushing plate) that combines damping properties with structural integrity. This composite approach allows the tensioner to achieve both improved stability from the longer arm and enhanced reliability from the polymeric damping element's ability to absorb and dissipate sudden tension loads
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 enhanced damping system effectively stabilizes belt tension, enabling the use of longer tensioner arms and preventing sudden belt tension increases, thus reducing the risk of engine failure and improving installation ease while maintaining cost-effectiveness.
Implementation Method 1
The damping element (224) is engaged by a spring (222) and provides frictional torque
Implementation Method 2
a polymeric bushing plate and additional friction sources
Data Source
Figure 1
Figure 2a
Figure 2b
AI summary
In an aspect, a tensioner(100) for an endless drive member, comprising a shaft (14) and base (15) that are mountable to be stationary relative to an engine, a tensioner arm (118) that is pivotable relative to the shaft about a tensioner arm axis, a pulley on the tensioner arm (118) rotatable about a pulley axis that is offset from the tensioner arm axis, and that is engageable with an endless drive member, a bushing (116) that is positioned radially between the pulley (120) and the tensioner arm (118) to support the pulley radially during relative rotation between the pulley and the tensioner arm, a tensioner spring (22) that is positioned to urge the tensioner arm towards a free arm position, a damping element (124) that engages the tensioner arm and that is engaged by a plurality of axially spaced segments (127a,127b) of the tensioner spring.