Methods and apparatus for position sensitive suspension damping

Abstract

Methods and apparatus for position sensitive dampening. In one aspect a fluid damper is provided comprising a damper chamber divided by a piston into a primary compression and a primary rebound chamber; a secondary compression chamber in fluid communication with the damper chamber; and an adjustable fluid meter controlling fluid flow out of the secondary compression chamber.

1 . A damper for a shock absorber comprising:
 a damper chamber divided by a piston and shaft into a compression portion and a rebound portion;   a dampening fluid within said damper chamber, said piston comprising a fluid path therethrough to permit said dampening fluid to be metered from said compression portion through said piston and into said rebound portion when said shaft moves into said damper chamber;   a bottom out cup at an end of said chamber;   a bottom out piston disposed at an end of said shaft for sealing engagement with said bottom out cup;   a first fluid flow path fluidically coupling said bottom out cup with said compression portion of said chamber, wherein a capacity of said first fluid flow path is adjustable;   a second fluid flow path fluidically coupling said bottom out cup and said rebound portion of said damper chamber, said second fluid flow path formed in said shaft.   
     
     
         2 . The damper of  claim 1 , wherein said capacity of said first fluid flow path is determined by a user-adjustable valve positioned in and partially obstructing said first fluid flow path. 
     
     
         3 . The damper of  claim 2 , wherein said user-adjustable valve is manually adjustable and accessible externally of said damper. 
     
     
         4 . The damper of  claim 2 , wherein said user-adjustable valve can be adjusted between a closed position and a plurality of open positions. 
     
     
         5 . The damper of  claim 1  further comprising:
 a third fluid flow path fluidically coupling said bottom out cup and said compression portion. 
 
     
     
         6 . The damper of  claim 5  further comprising:
 a blow off valve disposed in said third fluid flow path, said blow off valve having a predetermined blow off threshold pressure. 
 
     
     
         7 . The damper of  claim 1 , wherein said second fluid flow path is adjustable with a check valve to permit flow of said dampening fluid in a single direction between said bottom out cup and said rebound portion. 
     
     
         8 . The damper of  claim 7 , wherein said check valve is arranged in said second fluid flow path to permit fluid communication between said rebound portion and said bottom out cup during a rebound stroke of said shaft. 
     
     
         9 . The damper of  claim 7 , wherein a volume of said dampening fluid traveling through said second fluid flow path is user-adjustable. 
     
     
         10 . A vehicle comprising:
 a damper for a shock absorber coupled to said vehicle, said damper comprising:
 a damper chamber divided by a piston and shaft into a compression portion and a rebound portion; 
 a dampening fluid within said damper chamber, said piston comprising a fluid path therethrough to permit said dampening fluid to be metered from said compression portion through said piston and into said rebound portion when said shaft moves into said damper chamber; 
 a bottom out cup at an end of said chamber; 
 a bottom out piston disposed at an end of said shaft for sealing engagement with said bottom out cup; 
 a first fluid flow path fluidically coupling said bottom out cup with said compression portion of said chamber, wherein a capacity of said first fluid flow path is adjustable; 
 a second fluid flow path fluidically coupling said bottom out cup and said rebound portion of said damper chamber, said second fluid flow path formed in said shaft. 
   
     
     
         11 . The vehicle of  claim 10 , wherein said vehicle is selected from the group consisting of: an off-road vehicle, a car, a motorcycle, a bicycle, an off-road truck, an all-terrain vehicle and a snow-mobile. 
     
     
         12 . A method of operating a shock absorber comprising a damper, said method comprising:
 compressing said shock absorber to a location where a bottom out piston on a shaft moves in engagement with a bottom out chamber disposed within a dampening chamber containing a dampening fluid;   creating a substantially sealed relationship between said bottom out piston and said bottom out chamber; and   metering a passage of said dampening fluid from within said bottom out chamber through a user-adjustable metering valve.   
     
     
         13 . The method of  claim 12 , further comprising:
 flowing, during extension of said shock absorber, said dampening fluid through a first fluid flow path fluidically coupling said bottom out chamber and a rebound portion of said dampening chamber, said first fluid flow path closed during compression of said shock absorber.   
     
     
         14 . The method of  claim 12 , further comprising:
 adjusting said user-adjustable metering valve.   
     
     
         15 . The method of  claim 14 , further comprising:
 adjusting said user-adjustable metering valve by further closing said user-adjustable metering valve when a temperature of said shock absorber increases.