Trailing Link Cycle Suspension With Unequal Gas Piston Areas
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Solution Overview
Problem
Telescopic front suspension forks for cycles face issues such as high stiction, reduced stability during suspension compression, and inadequate leverage ratio, leading to instability and compromised traction, especially during braking and cornering.
Innovation Solution
A suspension assembly with a steering fork featuring a shock absorber and a spring unit on each arm, where the gas pistons have unequal areas, allowing for balanced force distribution and improved mechanical trail, thereby reducing stiction and enhancing stability and traction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If telescopic fork stanchions are made larger to support fore/aft loads, then load-bearing capacity is improved, but stiction increases and stability deteriorates
Solution Approach 1:
The suspension system is divided into separate functional components: a telescopic fork for lateral support and a trailing link suspension with shock absorber for fore/aft load management. This segmentation allows each component to be optimized for its specific function, reducing the need for oversized stanchions that generate high stiction.
Solution Approach 2:
The shock absorption function is extracted from the telescopic fork stanchions and placed into a dedicated shock absorber within the trailing link suspension. This extraction allows the stanchions to be smaller and generate less stiction while the shock absorber handles fore/aft load management.
2Loss of energy
If telescopic fork suspension is compressed to absorb bumps, then shock absorption is improved, but mechanical trail reduces and stability deteriorates
Solution Approach 1:
The trailing link suspension employs a dynamic geometry design where the linkage angles and mechanical trail change dynamically with suspension compression. As the suspension compresses, the trailing link geometry maintains or increases mechanical trail, preserving stability during shock absorption events.
Solution Approach 2:
The system changes geometric parameters (linkage angles, mechanical trail) as a function of suspension compression. The trailing link mechanism transforms vertical wheel movement into controlled changes in linkage geometry that maintain stable handling characteristics throughout the compression range.
3Stability of the object's composition
If fork stanchions are angled 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 suspension system segments the functions of angle management and shock absorption. The trailing link geometry handles angle of attack stability independently of the stanchion angle, allowing the stanchions to be optimized for minimal stiction rather than slackness.
Solution Approach 2:
The trailing link mechanism acts as an intermediary that decouples the relationship between stanchion angle and angle of attack stability. It provides a mechanical means to achieve stable geometry without requiring the stanchions themselves to be angled slacker, thus avoiding increased bushing load and stiction.
Data Source
AI summary
A suspension assembly for a cycle having improved stability includes a steering fork having a first arm and a second arm, each of the first arm and the second arm having a fixed pivot and a shock pivot, the space between the first arm and the second arm defining a wheel opening. A shock link has a shock link fixed pivot and a shock link floating pivot. A shock absorber has a shock gas spring comprising a shock spring body a shock gas piston having a first gas piston area, a spring unit has a spring gas spring comprising a spring body and a spring gas piston having a second gas piston area. The first gas piston area is not equal to the second gas piston area.