Power Spring Chain Tensioner for Vibration Damping
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Solution Overview
Problem
Hydraulic tensioners face issues with load synchronization and chain vibration due to oil pressure fluctuations, leading to excessive chain looseness and tap tones, while mechanical tensioners have low load absorbability and generate high tension as an impact load, making them unsuitable for engines with high loads.
Innovation Solution
A tensioner utilizing a power spring with a backup member that supports the spring to resist radial shifts, utilizing inter-plate frictional forces to absorb and damp vibrations by expanding and contracting the spring's diameter, thereby adjusting chain tension effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a hydraulic tensioner is used, then load absorbing ability is improved, but chain vibration and tap tones occur due to delayed plunger projection and excessive chain looseness
Solution Approach 1:
The patent replaces the hydraulic tensioner system with a mechanical tensioner using a power spring. This substitution eliminates the need for hydraulic fluid and plunger mechanisms, directly addressing the chain vibration and tap tone issues caused by delayed plunger projection while maintaining load absorbing ability through the power spring mechanism
Solution Approach 2:
The patent changes the fundamental operating parameter from hydraulic pressure to mechanical spring force. By using a power spring with controlled urging force, the system achieves immediate response to chain tension variations without the lag inherent in hydraulic systems, thereby eliminating chain vibration and tap tones
2Device complexity
If a mechanical tensioner with reverse rotation preventing claw is used, then structure is simplified, but load absorbability is low causing high tension impact loads
Solution Approach 1:
The patent employs a power spring mechanism that transforms the mechanical properties of the tensioner. The power spring provides progressive resistance to chain tension variations, enabling high load absorbability while maintaining structural simplicity. The spring's elastic properties allow it to absorb impact loads without requiring complex reverse rotation preventing mechanisms
Solution Approach 2:
The patent utilizes the composite action of the power spring and tensioner arm to achieve both structural simplicity and high load absorbability. The power spring serves multiple functions: maintaining chain tension, absorbing load variations, and preventing reverse rotation through its inherent elastic resistance, thereby eliminating the need for separate reverse rotation preventing claws
3Reliability
If a lock mechanism is added to hydraulic tensioner, then excessive plunger push-in is prevented, but high tension impact loads and tap tones occur
Solution Approach 1:
The patent replaces the hydraulic tensioner with lock mechanism with a purely mechanical power spring tensioner. The power spring inherently maintains constant urging force on the tensioner arm without requiring lock mechanisms, thereby eliminating the high tension impact loads and tap tones generated by sudden locking actions while still preventing excessive plunger push-in through continuous spring pressure
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 tensioner smoothly absorbs chain vibrations, prevents excessive tension, and reduces stress concentrations, offering high durability and stress resistance, making it suitable for a wide range of applications including high-load engines.
Implementation Method 1
utilizing a difference of inter-plate frictional forces in winding and unwinding a power spring
Implementation Method 2
absorb and damp vibrations by expanding and contracting the spring's diameter
Implementation Method 3
a backup member (25)(25 2 ) being in contact with the power spring (21) and supporting the power spring by acting an urging force in a direction opposite to a radial shift of the power spring
Implementation Method 4
causing an urging force of a power spring to act so as to resist against a load acting from a wrap-around transmission body
Data Source
Figure 1
Figure 2
Figure 3A~3B
AI summary
A use range of a conventional mechanical tensioner using a power spring is limited because a function of damping and buffering chain vibration is insufficient or its durability is not enough. In a tensioner 17 of the present disclosure, an urging force of a power spring 21 acts on a plunger 20 and resists against a load from a tensioner arm 16. In a case where the plunger 20 projects out, while the power spring expands its diameter and is unwound, an inter-plate frictional force at this time is small. In a case where the plunger 20 is pushed in, the power spring 21 is wound up and an inter-plate frictional force acts significantly due to the reduction of the diameter. Due to the difference of the frictional force, the chain vibration is damped and is buffered.