Elastic Chain Tensioner with Variable Pitch Rim
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Solution Overview
Problem
Existing tensioning and damping elements for endless chain drives experience precision deficiencies, increased wear, and noise due to unstable point contact and varying pitch deviations during the operating period, especially as the chain wears and elongates, leading to imprecise chain engagement and reduced stability at higher speeds.
Innovation Solution
The tensioning and damping element features radially curved segments with bulges on opposite sides and depressions between them, providing stable positioning surfaces and preventing pressure deformation, with an extended pitch that remains larger than the chain pitch throughout the deformation range, ensuring consistent engagement and reduced heat transfer, and a semielliptical profile shape for improved correspondence with the chain.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the tensioning and damping element is pre-tensioned in an elliptical shape to achieve tensioning function, then the tensioning effectiveness is improved, but the pitch correspondence between the toothed rim and chain deteriorates due to compression in the contact region
Solution Approach 1:
The toothed rim is designed with radially curved segments that can dynamically adjust their pitch during operation. The pitch varies between a first pitch value when the element is in its stress-free concentric shape and a second pitch value when pre-tensioned in an elliptical shape, allowing the structure to adapt to different operational states and maintain optimal engagement with the chain throughout the tensioning cycle.
Solution Approach 2:
The patent implements variable pitch parameters in the toothed rim design. The pitch is not constant but changes based on the operational state (concentric vs. elliptical shape), enabling the structure to compensate for deformations and maintain precise chain engagement across different tensioning conditions.
2Duration of action of moving object
If the chain operates for an extended period causing wear and elongation, then the chain pitch increases, but the pitch deviation between chain and toothed rim worsens leading to imprecise engagement
Solution Approach 1:
The radially curved segments enable the toothed rim to dynamically respond to chain wear and elongation over time. As the chain pitch increases due to wear, the variable pitch mechanism adjusts accordingly, maintaining optimal engagement geometry throughout the extended operating period and preventing precision degradation.
Solution Approach 2:
The pitch parameter of the toothed rim is designed to vary not only with operational state but also to accommodate long-term chain wear. This allows the system to maintain precise engagement even as the chain elongates over extended operating periods.
3Strength
If the roller-seatings are located outside the neutral bending fiber to provide structural configuration, then the structural integrity is maintained, but the roller-seatings experience compression during elliptical deformation causing camber and point contact
Solution Approach 1:
The roller-seatings are designed with a curved profile shape that corresponds to the secondary vortexes of the elliptical deformation. This curvature compensation ensures that during elliptical pre-tensioning, the roller-seatings maintain proper contact geometry with the chain rollers, preventing camber-induced point contact while preserving structural integrity.
4Manufacturing precision
If the pitch of the toothed rim is compressed during elliptical deformation to match chain pitch initially, then initial engagement is improved, but the engagement precision deteriorates as chain wears and pitch increases
Solution Approach 1:
The variable pitch design allows the toothed rim to transition between different pitch values based on operational state and wear level. This dynamic adjustment ensures optimal engagement precision both initially and throughout the service life, accommodating chain elongation without sacrificing long-term engagement stability.
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
This configuration enhances running precision, reduces noise, slows down wear, and improves load-carrying capability by maintaining stable engagement and pitch correspondence across the operating period, even as the chain wears and elongates, allowing for longer tensioning paths and higher chain speeds.
Implementation Method 1
Such tensioning and damping elements are elastic elements, which can be deformed between the shape of a concentric ring and the shape of a Cassinian curve
Data Source
AI summary
A tensioning and damping element for endless chain drives, especially for roller chain drives, can be used for endless chain drives, which are to be tensioned diametrically. The material is an elastic plastic. All told, the known tensioning and damping elements, in conjunction with the wear of the chain, the load changing phases, as well as the reversing according to the degree of deformation, have the disadvantage of a phased running irregularity, an increased running noise and of wear-intensive areas in the toothed rim. An element with a ring part and a toothed rim of arc-shaped teeth with, in each case, axially opposite bulges in the roller-seating and, between these, roller-seating depressions, grooves, which are disposed peripherally between the ring part and the bulges, an extended pitch and extended roller-seatings with the advantageous profile shape similar to a semielliptical curve lying on the root circle.