Motorcycle Chain Guide with Variable Wall Thickness
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Solution Overview
Problem
Existing chain guides for motorcycles, whether made of metal or plastic, face challenges in balancing weight reduction with the need to withstand repeated impacts, leading to potential deformation and excessive wear, especially when the distance between the front and rear sprockets is substantial.
Innovation Solution
A U-shaped plastic chain guide with a trapezoidal configuration and a removable insert that transitions from a thicker top edge to a thinner bottom edge, providing structural integrity while minimizing weight, and featuring a beveled design to reduce material thickness and enhance support around mounting holes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If plastic chain guides are designed to be strong enough to withstand repeated impacts, then strength is improved, but weight increases and becomes bulky
Solution Approach 1:
The chain guide features non-uniform wall thickness with thicker sections (first thickness) at the top edge and mounting hole areas, and thinner sections (second thickness) at the bottom edge. This local variation in material distribution provides enhanced strength where impacts and mounting stresses occur while reducing overall weight and bulk of the chain guide.
Solution Approach 2:
The beveled configuration and thicker top edge design prepare the chain guide structure in advance to withstand repeated impacts from chain tension and loading. The pre-engineered thickness distribution and bevels create inherent structural reinforcement that proactively resists deformation before impacts occur.
2Strength
If metal chain guides are used, then strength is improved, but deformation under impact occurs leading to chain contact with internal channel sides
Solution Approach 1:
The patent changes the material parameter from metal to plastic, and modifies the geometric parameter of wall thickness distribution. The plastic material with its specific elasticity and the non-uniform thickness profile work together to absorb impact energy without permanent deformation, preventing chain contact with internal channel sides and maintaining reliable operation.
Solution Approach 2:
The chain guide utilizes plastic material properties combined with a specific geometric configuration (non-uniform thickness, beveled edges) to create a composite solution that achieves both strength and deformation resistance. The plastic material's inherent elasticity complements the structural design to prevent the deformation issues associated with metal chain guides.
3Ease of manufacture
If uniform thickness is used throughout the chain guide, then manufacturing is simplified, but weight reduction is limited
Solution Approach 1:
The chain guide employs varying wall thickness (first thickness at top, second thickness at bottom) tailored to local structural requirements. This local quality approach optimizes weight reduction in areas requiring less strength while maintaining adequate thickness where structural support is needed, achieving better overall weight reduction than uniform thickness designs.
Data Source
AI summary
A chain guide for guiding a chain traveling around a sprocket supported on a frame of a motorcycle is disclosed. Typically, the chain guide includes a U-shaped, plastic body with a channel formed along an inner surface to of the body and a plastic removable chain guide oriented such that a surface of the removable chain guide insert is facing the chain running through the channel. The inner and outer walls of the body configured with a first thickness along the top edge and downward to a bevel to a second, smaller thickness downward to a bottom edge along an outer surface.