Variable friction tuning for shock absorption

Abstract

An exemplary shock absorber includes a damper tube, a damper piston, a piston shaft, and at least two different surface treatments. The damper tube includes an interior surface. The damper piston includes a piston surface that engages the interior surface. The piston shaft couples with the damper piston and includes a shaft surface that engages a fourth surface. The at least two different surface treatments are disposed on at least one of the interior surface and the shaft surface and create a corresponding plurality of coefficients of friction with at least one of the piston surface and the fourth surface respectively.

The invention claimed is: 
     
         1 . A fluid damper shock absorber, comprising:
 a damper tube including an interior surface;   a damper piston including a piston surface that engages said interior surface;   a piston shaft coupled with said damper piston and including a shaft surface that engages a fourth surface; and   at least two different surface treatments on at least one of said interior surface and said shaft surface that create a corresponding plurality of coefficients of friction with at least one of said piston surface and said fourth surface respectively, wherein said surface treatments include a first surface treatment at a first end of said interior surface of said damper tube having a first coefficient of friction with said piston surface, wherein said surface treatments include a second surface treatment adjacent said first surface treatment having a second coefficient of friction with said piston surface that is less than said first coefficient of friction, and wherein said surface treatments include a third surface treatment adjacent said second surface treatment having a third coefficient of friction with said piston surface that is greater than said second coefficient of friction.