Roller Chain Rocker Joints for Wear Reduction
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Solution Overview
Problem
Existing roller chains with rocker joints and bolts suffer from rapid wear and complex structures, leading to inefficient power transmission and short service life under dynamic loads, particularly in timing chain drives of internal combustion engines.
Innovation Solution
A roller chain design featuring convexly curved contact areas and transition radii between 0.03 to 0.1 times the chain pitch, providing a four-area support for rollers, optimized lubrication, and angled rocker bolts to distribute forces and reduce friction, resulting in improved centric guidance and longer service life.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional rocker pins are used with flat or simple curved surfaces, then the structure is simple, but the roller guidance is poor causing rapid wear and short service life
Solution Approach 1:
The rocker pin contact surfaces are designed with convex curvature having a radius of 0.9 to 1.1 times the roller radius, creating a four-area contact pattern that ensures concentric roller guidance. This curved geometry eliminates the wear problems associated with flat or simple rocker pin designs while maintaining manufacturing feasibility.
Solution Approach 2:
Different sections of the rocker pin are given different geometries: the contact areas have convex curvature for optimal roller guidance, while the intermediate section has a reduced width (maximum 0.27 times chain pitch) to minimize non-load-bearing material. This localized optimization improves both performance and weight efficiency.
2Strength
If the rocker pin contact areas are made small to reduce material, then manufacturing is simpler, but the contact area with the roller is insufficient leading to high stress and deformation
Solution Approach 1:
The contact area radius is optimized to be 0.9 to 1.1 times the roller radius, and the contact areas are positioned at specific angles (≥60° apart) to create four distinct contact zones. These parameter optimizations ensure adequate contact area for load bearing while maintaining manufacturability through standard machining processes.
3Reliability
If the transition radius between contact areas and weighing surface is made large, then stress concentrations are reduced, but the support distance increases causing larger sprocket requirements and reduced performance
Solution Approach 1:
The transition radius is precisely optimized to be between 0.03 and 0.1 times the chain pitch. This narrow parameter range achieves the optimal balance: it is large enough to avoid significant stress concentrations but small enough to minimize the support distance, enabling effective operation on smaller sprockets while maintaining chain reliability.
4Power
If conventional roller chain designs are used, then the structure is straightforward, but friction is high and power transmission efficiency is poor
Solution Approach 1:
The convex curved contact surfaces of the rocker pins create point or line contact rather than face contact with the roller, significantly reducing the friction area. The four-area contact pattern distributes loads efficiently while minimizing energy loss to friction, thereby improving power transmission efficiency in the chain drive system.
Data Source
Figure 1
Figure 2~4
Figure 5
AI summary
The present invention relates to a roller chain (4) with inner and outer chain links (12, 13) alternately connected to one another by means of a rocker joint (11) and with at least one roller (16) rotatably mounted on rocker pins (15, 18) of the rocker joint, wherein the roller has a substantially cylindrical roller opening (23). The rocker pins are characterized in that at least two contact areas (25.1, 25.2) arranged at an angle to each other at a distance about the joint axis (G) are provided on a back (21, 22) facing away from their rocker surface (19, 20), which can be brought into contact with the roller opening, and an intermediate section (24) having a distance (A) from the roller opening.