Trailing Link Cycle Suspension With Rising Mechanical Trail
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Solution Overview
Problem
Telescopic front suspension forks in two-wheeled vehicles suffer from high stiction, reduced stability due to mechanical trail reduction during compression, lack of leverage ratio, and increased stiction and angle of attack stability, leading to instability and poor handling.
Innovation Solution
A suspension assembly for a cycle with a steering fork having unequal gas piston areas in the shock absorber and spring unit, which increases mechanical trail distance as the suspension compresses, improving stability and handling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If telescopic fork stanchions are sized to support greatest loads in fore/aft direction, then load bearing capacity is improved, but stiction increases
Solution Approach 1:
The suspension system is divided into separate functional components: a telescopic fork assembly for load bearing and a linkage suspension assembly for shock absorption. This segmentation allows each component to be optimized for its specific function, with the telescopic fork focusing on fore/aft load support while the linkage handles vertical shock absorption, thereby reducing unnecessary stiction in the steering system.
2Object-generated harmful factors
If telescopic fork compression increases, then shock absorption is improved, but mechanical trail reduces causing instability
Solution Approach 1:
The linkage suspension assembly incorporates dynamic geometric relationships where the mechanical trail increases as the suspension compresses. This is achieved through the specific arrangement of linkage members that create a varying leverage ratio, allowing the system to adapt its stability characteristics in real-time based on the compression state, thereby maintaining stability during shock absorption events.
3Ease of operation
If fork stanchion angle is made slacker for better angle of attack, then bump response is improved, but bushing load and stiction increase
Solution Approach 1:
The system separates the functions of angle of attack optimization and load bearing. The linkage suspension assembly can be designed with optimal fork angles for bump response without compromising steering stability, as the telescopic fork assembly independently handles the load bearing function. This segmentation allows each subsystem to be optimized for its primary function.
4Device complexity
If telescopic fork is used for simple linear compression, then device complexity is reduced, but leverage ratio is lost
Solution Approach 1:
The invention merges a telescopic fork assembly with a linkage suspension assembly into a hybrid system. This combination allows the system to achieve both the simplicity of linear compression from the telescopic fork and the leverage ratio benefits of the linkage suspension, creating a composite system that exhibits properties of both parent designs.
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
The suspension assembly reduces stiction, increases stability during braking and cornering, and provides improved handling by maintaining a greater mechanical trail distance as the suspension compresses.
Implementation Method 1
a shock absorber including a first gas spring on a first arm of a steering fork, and a spring unit including a second gas spring on a second arm of the steering fork
Implementation Method 2
The damper has a first damping coefficient when the wheel suspension is in the first configuration and a second damping coefficient when the wheel suspension is in the second configuration
Data Source
AI summary
A suspension assembly for a cycle having improved stability includes a steering fork having a steering axis, 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. A mechanical trail distance increases as the suspension assembly compresses relative to a fully extended state.