Bicycle Suspension Fork Air Volume Tuning for Stable Spring Rate
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Solution Overview
Problem
Existing bicycle suspension forks experience pressure spikes and speed-sensitive return forces due to the casting ramp spring effect, which affects spring rate and consistency, leading to inconsistent riding feel.
Innovation Solution
Incorporating an increased internal air volume within the lower tube of the suspension fork, utilizing a housing to expand the casting volume capacity and reduce pressure spikes during compression, thereby minimizing the influence of the casting ramp spring effect.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the casting volume capacity is increased to reduce pressure spikes, then the spring rate consistency is improved, but the device complexity increases due to additional housing and volume control elements
Solution Approach 1:
The volume control element is nested within the lower tube assembly, with the seal element positioned between the first and second tubes to define the increased casting volume. This nested configuration allows the volume control element to be integrated into the existing fork structure without requiring separate external components, thereby reducing overall device complexity while still achieving the goal of increased casting volume capacity for more consistent spring rate
Solution Approach 2:
The invention changes the volume parameter of the casting chamber by positioning the seal element to increase the casting volume capacity. This parameter change directly addresses the pressure spike issue during compression while maintaining structural simplicity through the integrated seal element design that modifies the existing volume rather than adding separate expansion chambers
2Reliability
If the casting volume capacity is increased to reduce speed sensitivity, then the damping performance consistency is improved, but the manufacturing complexity increases due to precise sealing requirements
Solution Approach 1:
The seal element is configured to work in conjunction with the volume control element to create a homogeneous sealing interface between the first and second tubes. This homogeneous sealing approach ensures consistent sealing performance across the increased casting volume while simplifying manufacturing by using a single integrated seal element rather than multiple separate sealing components that would require complex assembly
Solution Approach 2:
The seal element is nested within the telescoping tube assembly, positioned to seal between the first tube and second tube. This nested positioning allows the seal to be integrated into the existing manufacturing process of the telescoping tubes without requiring separate sealing assembly steps, thereby improving ease of manufacture while achieving the required sealing for increased casting volume capacity
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 increased air volume reduces pressure spikes and speed sensitivity, providing a more consistent riding experience by stabilizing the spring rate and damping performance.
Implementation Method 1
utilizing a housing to expand the casting volume capacity and reduce pressure spikes during compression
Data Source
Figure 1
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Figure 3A
AI summary
Suspension forks for bicycles are described herein. An example suspension fork (200) includes a first tube (222) and a second tube (226) slidably received within the first tube. The first tube includes an outer mounting portion. A first volume (326) is disposed between the first tube and the second tube. A sealing element (380) is provided for sealing the first volume between the first tube and the second tube. A volume control element is removably attachable to the outer mounting portion of the first tube, wherein the volume control element is operable to change a magnitude of the first volume disposed between the first tube and the second tube.