Methods and apparatus for vehicle suspension having multiple gas volumes
A method and apparatus for a vehicle suspension system gas spring. In one embodiment, a vehicle suspension system gas spring includes a compressible main gas chamber and an additional volume combinable with the main chamber to change a gas spring rate of the system. In one embodiment, a low friction piston seal is created by a flexible seal member.
1 . A gas spring system for use in a suspension system, comprising:
a first chamber having a mechanical spring member therein, said mechanical spring member compressible in a compression stroke of said suspension system, said first chamber configured to contain a gas therein, wherein, in said compression stroke, both said gas and said mechanical spring together to determine a spring rate of said first chamber, and wherein said mechanical spring member primarily forms said spring rate of said first chamber over a first portion of said compression stroke;
a second chamber isolated from the first chamber, the second chamber having gas therein, the gas in said second chamber compressible in the compression stroke, said second chamber isolated from said first chamber;
wherein said spring rate of said first chamber and the gas in said second chamber jointly form a spring rate of said gas spring system in the compression stroke;
a shaft extending along a center of said suspension system, wherein said shaft extends through said second chamber;
a piston coupled with said shaft, wherein said piston does not sealingly engage an inner surface of said second chamber; and
wherein said first chamber is fillable through a first fill valve located at a lower end of said suspension system.
2 . The gas spring system of claim 1 , further comprising:
a spring guide integrated into said suspension system.
3 . The gas spring system of claim 2 , wherein said spring guide is configured to ensure said mechanical spring member remains centered in said first chamber.
4 . The gas spring system of claim 1 , wherein said gas in said second chamber is pressurized.
5 . The gas spring system of claim 1 , wherein said second chamber is isolated from said first chamber such that said gas in said second chamber is not permitted to flow into said first chamber during operation of said gas spring system.
6 . The gas spring system of claim 1 , wherein said gas in said second chamber primarily forms said spring rate over a second portion of said compression stroke.
7 . The gas spring system of claim 1 , wherein said shaft terminates in a top out ring disposed in a piston.
8 . The gas spring system of claim 7 , wherein said shaft and said top out ring are configured to retain said piston in an initial position prior to said compression stroke.
9 . The gas spring system of claim 1 , wherein said gas spring system is disposed in a front fork of a bicycle.
10 . The vehicle suspension system gas spring of claim 9 , wherein the front fork also includes a fluid damper.