Silent Chain Link Plate Curved Inner Flank Noise Reduction
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Solution Overview
Problem
Conventional silent chains experience high contact pressure and noise during engagement with sprockets due to small initial contact area and forward inclination of link plates, leading to excessive friction and noise generation.
Innovation Solution
The silent chain features arc-shaped engagement starting regions and straight engagement guiding regions on its link plates, allowing continuous and smooth engagement with sprockets, reducing contact pressure and noise by ensuring inner flanks engage first, followed by outer flanks, and varying curvature and length along the chain to prevent clashing and periodic vibrations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional silent chains use straight inner flanks for engagement, then manufacturing is simpler, but chordal action causes direct clashing of tooth tips with high friction and noise
Solution Approach 1:
The inner flank of the link plate tooth is designed with a curved profile instead of a straight line. The curvature radius varies along the engagement direction, being smaller at the tip and larger toward the root. This curved geometry allows the tooth to engage the sprocket more gradually, reducing the impact of chordal action and preventing direct clashing of tooth tips, thereby reducing frictional noise and engagement noise.
2Device complexity
If conventional silent chains have small initial contact area, then the structure is simpler, but contact pressure is high causing engagement noise
Solution Approach 1:
The curved inner flank with varying curvature radius creates a progressively increasing contact area during engagement. At the beginning of engagement, the contact area is small, but as the link plate engages the sprocket, the curved geometry naturally increases the contact area, distributing the load and reducing contact pressure throughout the engagement process, thereby reducing engagement noise.
3Ease of operation
If conventional silent chains use circular arc inner flanks, then sliding contact is achieved, but contact area remains small leading to high contact pressure
Solution Approach 1:
The inner flank uses a curved profile with varying curvature radius rather than a constant radius circular arc. The curvature radius increases from the tip toward the root of the tooth, which maintains smooth sliding contact at the beginning of engagement while progressively increasing the contact area, thereby reducing contact pressure as engagement progresses.
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 design reduces frictional noise and engagement noise by minimizing contact pressure and preventing clashing, resulting in smoother operation and reduced overall noise levels in chain transmission.
Implementation Method 1
the link teeth slidably contact the sprocket tooth surfaces without excessive friction when starting to engage with, and when separating from, the sprocket
Data Source
AI summary
In a silent chain of the inner flank engagement and outer flank seating type, the link plate teeth are arranged so that their rearwardly facing inner flanks protrude slightly beyond the outer flank overlapping link plate teeth in a preceding row when the chain is straight and in tension. The rearwardly facing inner flank is composed of an arc-shaped engagement starting region adjacent the tip and a straight engagement guiding region extending toward the root.