Dual-Chamber Bicycle Air Spring for Progressive Compression
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Solution Overview
Problem
Conventional bicycle air springs have an ideal load displacement curve for mountain bike suspension systems, and they experience spikes in load due to the adiabatic effect at high velocities.
Innovation Solution
An improved air spring design featuring a first body with a first piston that slides within it, a second piston in a fixed position, and a cup that allows gas to flow between different areas, increasing the spring rate at a higher rate as the pistons move from an intermediate to a compressed position.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of moving object
If a conventional air spring is used in mountain bike suspension, then the suspension system is lightweight, but the load-displacement curve is not ideal and experiences spikes at high velocities due to the adiabatic effect
Solution Approach 1:
The air spring is divided into two separate chambers: a first chamber and a second chamber. The first chamber contains a first piston that moves with suspension compression, while the second chamber contains a second piston that remains fixed during compression. This segmentation allows each chamber to serve a different function in the load-displacement curve, eliminating the spikes caused by adiabatic heating in a single-chamber design.
Solution Approach 2:
A flow restrictor is introduced as an intermediary component between the first and second chambers. This flow restrictor controls the rate at which air can transfer between chambers, allowing the system to maintain ideal performance characteristics by regulating gas flow during compression and extension cycles.
2Force
If the spring rate increases too quickly in compression, then bump absorption is improved, but the likelihood of bottoming out increases
Solution Approach 1:
The system dynamically adjusts the effective spring rate during compression by allowing air to flow between chambers at a restricted rate. As compression increases, the pressure differential drives more air into the second chamber, progressively increasing the spring rate in a controlled manner that provides bump absorption while preventing bottoming out.
Solution Approach 2:
The system changes the physical parameters of the gas chambers by transferring air between them during compression. This changes the pressure and volume parameters dynamically, creating a progressive spring rate that adapts to the compression level without causing bottoming out.
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 design enhances the performance of mountain bike suspension systems by providing better control over the spring rate, improving bump absorption, and reducing the likelihood of bottoming out.
Implementation Method 1
a first piston that is slideably coupled to the first body, wherein the first piston comprises a seal that seals against the first wall, the first body and the first piston at least partially forming a first chamber having a volume containing an amount of gas, such that sliding of the first piston with respect to the first wall will change the volume of the first chamber
Implementation Method 2
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 (1700; 1800) includes a first body (1701; 1801); a first piston (1721; 1821) sealed against a first wall (1791; 1891) of the first body (1701; 1801); a cup (1702; 1802) having a second wall (1792; 1892); and a second piston (1722; 1822), wherein the cup (1702; 1802) and the second piston (1722; 1822) are configured such that: in an extended position, the second piston (1722; 1822) does not seal against the second wall (1792; 1892), in an intermediate position, the second piston (1722; 1822) seals against the second wall (1792; 1892), and as the first piston (1721; 1821) moves from the intermediate position to a compressed position, a spring rate of the air spring will increase at a higher rate than if the second piston (1722; 1822) were not sealed against the second wall.