Methods and apparatus for combined variable damping and variable spring rate suspension

Abstract

Pressure-sensitive vales are incorporated within a dampening system to permit user-adjustable tuning of a shock absorber. In one embodiment, a pressure-sensitive valve includes an isolated gas chamber having a pressure therein that is settable by a user.

1 . A vehicle suspension damper comprising:
 a cylinder and a piston assembly comprising a piston and piston rod;   working fluid within said damper, the damper comprising a compression chamber and a receiving chamber;   a pressure-sensitive valve disposed in the damper between the compression chamber and the receiving chamber, the valve including:
 a first valve surface in communication with a pressurized gas; 
 an opposing valve surface in communication with the working fluid. 
   
     
     
         2 . The damper of  claim 1 , whereby;
 in a compression stroke of the piston, the valve opens permitting fluid to move from one side of the piston to the other side when a force exerted by the gas on the first valve surface is overcome by an opposing force exerted on the opposing valve surface by the working fluid.   
     
     
         3 . The damper of  claim 1 , whereby:
 the valve closes, impeding movement of the fluid from one side of the piston to the other side when a force exerted by the gas on the first valve surface is overcome by an opposing force exerted on the opposing valve surface by working fluid.   
     
     
         4 . The damper of  claim 1 , further including a gas spring, the gas spring having a gas filled chamber that is compressible as the rod moves in the compression stroke. 
     
     
         5 . The damper of  claim 4 , whereby the gas in the gas spring is in fluid communication with the pressurized gas. 
     
     
         6 . The suspension damper of  claim 1 , wherein the first valve surface has a smaller piston area than the opposing valve surface. 
     
     
         7 . The suspension damper of  claim 1 , wherein the pressurized gas is user-adjustable. 
     
     
         8 . The suspension damper of  claim 7 , wherein the pressurized gas is user-adjustable via a path formed in the piston rod between the first valve surface and a user-adjustable fill valve. 
     
     
         9 . The suspension damper of  claim 1 , further including a gas-filled reservoir formed in a portion of the cylinder, the reservoir separated from the working fluid by a floating piston. 
     
     
         10 . The suspension damper of  claim 1 , wherein the valve is normally closed impeding the flow of working fluid from moving between the sides of the piston in a compression stroke. 
     
     
         11 . A vehicle suspension damper comprising:
 a cylinder and piston assembly comprising a piston and piston rod;   working fluid within said cylinder;   a valve disposed in the piston, the valve including:
 a first piston surface in communication with a first source of pressurized gas; 
 a second piston surface in communication with a second source of pressurized gas; and 
 a piston surface in communication with the working fluid, whereby the first and second piston surfaces are opposed. 
   
     
     
         12 . The damper of  claim 11 , whereby the first source of pressurized gas is a user-adjustable source and the second, opposing source is a preset source. 
     
     
         13 . The damper of  claim 12 , wherein the first source is of a higher pressure than the second source. 
     
     
         14 . The damper of  claim 11 , whereby;
 in a compression stroke of the piston, the valve opens permitting fluid to move from one side of the piston to the other side when a force exerted by the gas on the first piston surface is overcome by an opposing force exerted on the opposing piston surface and an opposing force exerted on the second piston surface.   
     
     
         15 . A vehicle suspension damper, comprising:
 a housing with working fluid, a piston and a rod designed to move into the housing in a compression stroke of the piston;   a remotely located reservoir for housing excess fluid during the compression stroke;   a fluid path connecting the housing and the remotely located reservoir;   a pressure-sensitive valve located in the fluid path, the valve having at least one movable surface acted upon by a gas, the gas housed in a chamber and the chamber in fluid communication with ambient air pressure.   
     
     
         16 . A damper for a vehicle comprising:
 a chamber with a piston and rod constructed and arranged to extend into the chamber in a compression stroke of the damper;   a valve operable with the damper, the valve permitting and restricting operation of the damper and having a first surface formed on a movable valve member, the surface operable with a working fluid of the damper and a second surface formed on the member, the second surface operable with gas pressure whereby;   in the compression stroke, the fluid pressure exerted on the first surface increases while the gas pressure exerted on the second surface remains constant.   
     
     
         17 . The damper of  claim 1 , whereby the second surface is an opposing surface to the first surface. 
     
     
         18 . The damper of  claim 16 , whereby the valve is integral to the piston. 
     
     
         19 . A shock absorber comprising:
 a damper having a compression chamber and a piston and rod for moving into the chamber during a compression stroke;   a valve for permitting and impeding working fluid from passing from the compression chamber of the damper to a receiving chamber of the damper, the valve having a first surface acted upon by working fluid and a second surface acted upon by a user-settable pressurized gas;   a spring, the spring working in conjunction with the damper to affect the movement of the shock absorber during the compression stroke.   
     
     
         20 . The shock absorber of  claim 19 , wherein the spring comprises a gas spring having a compressible gas chamber in fluid communication with the pressurized gas.