Suspension Fork Air Spring With Floating Piston Rebound Control
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Solution Overview
Problem
Current suspension forks experience a hard stop due to sudden pressure spikes during the retraction stroke, which is undesirable, as the negative air chamber volume decreases, causing the air spring to act like an air spring itself.
Innovation Solution
Incorporation of a floating piston inside the negative air spring chamber that moves to facilitate air flow through communication ports, controlling pressure and allowing a gradual stop by adjusting the air flow between chambers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of stationary object
If the seal head is moved lower in the stanchion tube to increase negative air chamber volume, then the negative air chamber volume is improved, but the air inside the lower acts like an air spring itself when the fork is compressed, causing a sudden spike in pressure
Solution Approach 1:
The air chambers are segmented and isolated from each other using a piston with seals. This segmentation allows the negative air chamber to be positioned lower in the stanchion tube without causing the air inside the lower to act like an air spring, because the piston prevents direct communication between the chambers and controls air flow through regulated pathways.
Solution Approach 2:
The piston acts as an intermediary between the positive and negative air spring chambers. It controls the interaction between the two chambers, allowing the seal head to be positioned lower while preventing uncontrolled air compression that would cause pressure spikes. The piston regulates air flow through communication ports, mediating the pressure dynamics.
2Force
If the air spring chamber volume decreases during compression, then the air spring effect is improved, but it causes a hard stop for the stanchion inside the lower
Solution Approach 1:
The air spring system is divided into positive and negative chambers that operate semi-independently. During compression, the negative chamber volume decreases providing air spring effect, while the positive chamber can compensate by allowing controlled air flow between chambers through the piston, preventing the hard stop that would occur in a single-chamber system.
Solution Approach 2:
The piston with communication ports serves as an intermediary that regulates air flow between the positive and negative chambers. During compression, it allows controlled air transfer that moderates the pressure increase in the negative chamber, transforming the harmful hard stop into a controlled gradual deceleration while maintaining the beneficial air spring effect.
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 solution prevents sudden stops by managing pressure spikes, providing a smoother and more controlled retraction stroke through the use of a floating piston and adjustable air flow mechanisms.
Implementation Method 1
The floating piston is adapted to move towards the piston head in response to a pressure created inside the lower during a translation of the stanchion towards the closed end of the lower
Implementation Method 2
a positive air spring chamber and a negative air spring chamber defined inside the stanchion
Data Source
AI summary
A suspension fork includes a steerer tube, a crown attached to the steerer tube, and a pair of fork legs extending from the crown. Each fork leg has a hollow stanchion telescopically inserted into a hollow lower. A piston having a piston head separates the stanchion into a positive and a negative air spring chamber. A base is disposed inside the stanchion and is secured to the stanchion such that the base is arranged between a closed end of the lower and the piston head. A floating piston is slidably disposed inside the negative air spring chamber and divides the negative air spring chamber into a first chamber and a second chamber. The floating piston moves towards the piston head in response to a pressure created inside the lower to facilitate a passage of air from the lower to the second chamber through a communication port defined by the base.