Cycle Suspension Assembly Increasing Mechanical Trail
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Solution Overview
Problem
Telescopic front suspension forks in two-wheeled vehicles face issues with high stiction, reduced mechanical trail during compression, lack of leverage ratio, and undesirable braking reactions, leading to instability and reduced traction.
Innovation Solution
A suspension assembly with a steering fork, shock link, shock absorber, wheel carrier, and control link configured in a trailing orientation, which increases mechanical trail distance as the suspension compresses, providing a greater than 1:1 leverage ratio and varying motion ratio, reducing stiction and enhancing stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If telescopic fork stantions are made larger to support fore/aft loads, then load-bearing capacity is improved, but stiction increases and compliance decreases
Solution Approach 1:
The suspension system is divided into multiple independent linkage components (upper arm, lower arm, shock link, control link) that work together through articulated connections. This segmentation allows each component to be optimized for its specific function while reducing overall stiction compared to a single large telescopic stantion.
Solution Approach 2:
Bushings and bearings are introduced as intermediary elements at the articulation points of the linkage system. These intermediaries reduce friction and stiction between moving parts, allowing compliant motion while supporting fore/aft loads effectively.
2Strength
If telescopic fork compression increases to absorb bumps, then shock absorption is improved, but mechanical trail reduces and stability decreases
Solution Approach 1:
The linkage configuration is designed so that mechanical trail varies dynamically with suspension compression. As the suspension compresses to absorb bumps, the geometry of the linkage system maintains or increases mechanical trail, preserving stability throughout the compression stroke rather than losing it as in traditional telescopic forks.
Solution Approach 2:
The system changes the geometric parameters of the linkage configuration during compression. By altering the angles and positions of the linkage components, the mechanical trail parameter is maintained or increased during compression, allowing shock absorption without stability loss.
3Stability of the object's composition
If fork stantion angle is made slacker to improve angle of attack stability, then angle of attack stability is improved, but bushing load increases and stiction increases
Solution Approach 1:
The fork assembly is segmented into multiple linkage components with separate articulation points. This allows the effective fork angle to be optimized for angle of attack stability while the bushing loads are distributed across multiple smaller articulation points rather than concentrated in a single large stantion, reducing stiction.
4Strength
If telescopic fork compresses during braking to support load transfer, then load support is improved, but suspension stiffens and traction reduces
Solution Approach 1:
The linkage system provides dynamic response to braking loads through its articulated geometry. As load transfer compresses the suspension during braking, the changing geometry of the linkage maintains compliance and prevents stiffening, allowing the suspension to continue absorbing bumps while supporting braking loads, thereby maintaining traction.
Data Source
AI summary
A trailing link, multi-link, suspension assembly for a cycle having improved stability includes a first arm having a first arm fixed pivot and a first arm shock pivot. A shock link has a shock link fixed pivot and a shock link floating pivot. A shock absorber has a first shock mount and a second shock mount. A wheel carrier has a wheel carrier first pivot and a wheel carrier second pivot spaced apart from one another, and a wheel mount that is adapted to be connected to a wheel. A control link has a control link floating pivot and a control link fixed pivot, the control link floating pivot being pivotably connected to the wheel carrier second pivot, and the control link fixed pivot being pivotably connected to the first arm control pivot. A mechanical trail distance increases as the suspension assembly compresses relative to a fully extended state.