Silent Chain Rocker Pin Bend-Blocking Surface Design
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Solution Overview
Problem
Existing silent chains experience noise and abrasion due to string vibration, which occurs when links bend relative to each other, and existing solutions either allow significant vibration or concentrate stress, impairing durability.
Innovation Solution
The silent chain features flat bend-blocking surfaces in pin holes and contact portions that prevent links from bending outward, reducing string vibration by ensuring continuous contact and dispersing loads, thus enhancing durability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If gaps are provided between the rocker pins and the bend blocking surfaces, then ease of assembly is improved, but string vibration is reduced only to a limited extent and noise is still generated
Solution Approach 1:
The patent changes the dimensional parameter of the gap between the rocker pin and bend-blocking surface from a larger value (in prior art) to a substantially closed or minimal gap. This parameter change eliminates the harmful string vibration and noise while maintaining ease of assembly, as the minimal gap does not significantly impede the assembly process.
Solution Approach 2:
The patent applies preliminary anti-action by pre-positioning the rocker pin such that it is substantially closed against the bend-blocking surface in the straight condition of the chain. This preliminary contact prevents the development of string vibration before it can occur during operation, thereby eliminating noise generation while still allowing for relatively easy assembly.
2Stability of the object's composition
If a bend-blocking surface is provided with a projection that contacts the rocker pin, then backward bending is prevented, but stress concentration occurs which impairs durability
Solution Approach 1:
The patent replaces the projection (sharp or concentrated feature) with a substantially flat bend-blocking surface. This geometric change from a concentrated contact point to a distributed flat surface prevents stress concentration while effectively preventing backward bending of the chain links, thereby improving durability without sacrificing stability.
Solution Approach 2:
The patent modifies the local geometry of the bend-blocking surface by making it substantially flat rather than projecting. This local quality change distributes the contact stress over a larger area where the rocker pin contacts the bend-blocking surface, preventing stress concentration and improving the durability of the link plates while maintaining the function of preventing backward bending.
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 effectively suppresses string vibration, reduces noise and abrasion, and improves the overall durability of the chain by eliminating stress concentration and minimizing contact noise.
Implementation Method 1
each connecting pin comprising two rocker pins arranged to roll on each other
Implementation Method 2
The engagement of the rocker pins with the bend-blocking surfaces of the pin holes prevents the links from bending backward beyond their straight condition
Implementation Method 3
reducing string vibration by ensuring continuous contact and dispersing loads, thus enhancing durability
Data Source
AI summary
In a transmission chain, interleaved links are articulably connected by connecting pins, each connecting pin comprising two rocker pins arranged to roll on each other. Pin holes in each of at least two overlapping link plates in each interleaved pair of link plates are shaped so that each rocker pin moves with one of the overlapping link plates and is engageable with a bend-blocking surface in the pin hole in the other of the two overlapping link plates when the two overlapping link plates are in a straight part of the chain. The engagement of the rocker pins with the bend-blocking surfaces of the pin holes prevents the links from bending backward beyond their straight condition, i.e., in an outward direction, opposite to the inward direction in which the links bend relative to each other when engaging a sprocket.