Dual-Chamber Bicycle Air Spring for Bump Absorption and Bottom-Out Resistance
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Solution Overview
Problem
Conventional bicycle air springs have an ideal load displacement curve that is not suitable for mountain bike suspension systems, experiencing spikes due to the adiabatic effect at high velocities, which compromises performance in bump absorption.
Innovation Solution
An improved air spring design with a first and second pressurized chamber and a flow passage, featuring a seal that restricts flow between the chambers at specific compression positions, allowing independent tuning of spring curves to manage resistance force and slope variation, ensuring effective bump absorption and bottom-out resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of moving object
If a conventional air spring is used in a mountain bike suspension system, then the weight is reduced compared to metal coil springs, but the load-displacement curve exhibits spikes due to the adiabatic effect at high velocities, compromising bump absorption performance
Solution Approach 1:
The air spring is divided into two separate pressurized chambers (first chamber and second chamber) that can operate independently. This segmentation allows each chamber to be optimized for different parts of the compression stroke, eliminating the adiabatic spikes that occur in conventional single-chamber designs while maintaining weight advantages.
Solution Approach 2:
A seal is implemented that dynamically transitions between allowing flow between chambers and restricting flow based on compression position. The seal permits flow during most of the compression stroke but restricts flow when the air spring is adjacent to the fully compressed position, creating a progressive spring curve that eliminates velocity-dependent spikes.
2Ease of operation
If the air spring allows free flow between chambers during compression, then the spring curve is softer for improved comfort, but the resistance force at full compression is insufficient to prevent bottoming out
Solution Approach 1:
The seal is positioned and configured to restrict flow between chambers in advance, specifically when the air spring reaches the fully compressed position. This preliminary restriction of flow ensures that sufficient resistance force is generated before bottoming out can occur, preventing the suspension from bottoming out while maintaining comfort during normal operation.
Solution Approach 2:
The system changes the flow parameter between chambers based on compression position. During most of the compression stroke, flow is permitted for softer operation, but at full compression, the seal restricts flow to increase resistance force. This dynamic parameter change allows the spring curve to be tuned independently for both comfort and bottom-out resistance.
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 improved air spring provides enhanced pedaling efficiency and ride comfort by maintaining a consistent spring rate in the bump zone and increasing resistance at full compression, effectively addressing the limitations of conventional designs.
Implementation Method 1
a first piston and a first body cooperating to define a pressurized first chamber including a gas... a pressurized second chamber... the pressurized first chamber and pressurized second chamber exert expansion force on the air spring
Implementation Method 2
The air spring has a seal to selectively permit, prevent, and/or restrict flow between the first chamber and the second chamber
Implementation Method 3
a conventional air spring may experience spikes in the load v. displacement curve when the air spring experiences high velocities due to the adiabatic effect
Data Source
Figure 1
Figure 2
Figure 3A
AI summary
An air spring includes a first body; a first piston cooperating with the first body to define a pressurized first chamber including a gas, the first piston configured to slideably move relative to the first body; a pressurized second chamber; a flow passage between the first chamber and the second chamber; and a seal to selectively permit or restrict flow between the first chamber and the second chamber depending on a position of the first piston with respect to the first body.