Silent Chain Link Geometry for Tooth Jump Resistance
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Solution Overview
Problem
Conventional silent chains face limitations in strength, stiffness, and noise levels due to design features like crotch height, included angle, and effective flank angle, leading to issues with tooth jump resistance and increased noise during operation, especially in wider transmission ratio vehicles.
Innovation Solution
The development of a silent chain link design with specific geometric ratios and curvature features, including effective outer and inner flank angles of less than or equal to 29 degrees, and specific ratios of K, H, and T, which enhance resistance to tooth jump while maintaining low noise levels by optimizing the contact areas and curvature of the links.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If the crotch height is increased to reduce operating noise, then noise level is reduced, but fatigue strength decreases due to high bending stress in the link crotch
Solution Approach 1:
The patent changes the geometric parameters of the link, specifically reducing the crotch height to a specific ratio (H/P ≤ 0.239) and adjusting the effective flank angles, which simultaneously reduces noise and maintains strength by optimizing the stress distribution in the link structure
Solution Approach 2:
The patent employs a composite link structure combining different geometric features (optimized crotch height, specific flank angles, and tooth profiles) to achieve both low noise operation and high fatigue strength, balancing two previously conflicting requirements
2Reliability
If the included angle of outer flanks is reduced to improve tooth jump resistance, then tooth jump resistance improves, but operating noise increases due to reduced active flank length
Solution Approach 1:
The patent optimizes the effective flank angles (α and φ) to specific ranges (≤29 degrees) and adjusts the crotch height ratio (H/P ≤ 0.239), creating a balanced geometric configuration that provides both tooth jump resistance and acceptable noise levels through precise parameter control
Solution Approach 2:
The patent introduces multiple geometric parameters (effective outer flank angle, effective inner flank angle, crotch height ratio, tooth height ratio) that work together in a multi-dimensional optimization, allowing simultaneous improvement of tooth jump resistance and noise control through coordinated parameter adjustment
3Productivity
If wider transmission ratio is used to improve vehicle performance and fuel economy, then performance and fuel economy improve, but chain tension increases making tooth jump more likely
Solution Approach 1:
The patent changes the link geometry parameters (effective flank angles, crotch height ratio) to create a more robust engagement configuration that increases tooth jump resistance, allowing the chain to handle the higher tensions generated by wider transmission ratios without failing
Data Source
AI summary
An improved link for a chain for use with a sprocket, the link comprising a body having a pair of apertures for receiving connecting pins and a pair of teeth having outside flanks, and inside flanks between the teeth defining a crotch. The improvement includes an effective outer flank angle between a line tangent to the outer flank of the link at 1.5 P and a vertical line intersecting the tangent line of less than or equal to 29 degrees, an effective inner flank angle between a line tangent to the inner flank of the link at 0.5 P and a vertical line intersecting the tangent line of less than or equal to 29 degrees, and a plurality ratios. The links may be assembled into a chain and connected by a plurality of pins.