Patent ID: 6988599

Claim:
A suspension strut for a vehicle having a wheel contacting a surface under the vehicle and a suspension link suspending the wheel from the vehicle and allowing compression movement of the wheel toward the vehicle and rebound movement of the wheel toward the surface, said suspension strut comprising: a compressible fluid; a hydraulic tube and displacement rod adapted to couple the suspension link and the vehicle, said hydraulic tube defining an inner cavity adapted to contain a portion of said compressible fluid and to cooperate with said compressible fluid to supply a suspending spring force that biases the wheel toward the surface, said displacement rod adapted to move into said inner cavity upon the compression movement of the wheel and to move out of said inner cavity upon the rebound movement of the wheel; a cavity piston coupled to said displacement rod and extending to said hydraulic tube thereby separating said inner cavity into a first section and a second section, said cavity piston defining a first orifice adapted to allow flow of said compressible fluid between said first section and said second section of said inner cavity; a first variable restrictor coupled to said cavity piston and adapted to variably restrict the passage of said compressible fluid through said first orifice based on the velocity of said cavity piston relative to said hydraulic tube; wherein said cavity piston, said first orifice, and said first variable restrictor cooperate to supply a rebound damping force during the rebound movement of the wheel; a pressure vessel defining an outer cavity located between said pressure vessel and said hydraulic tube and adapted to contain a portion of said compressible fluid; wherein said hydraulic tube has a sidewall defining a tube opening adapted to fluidly connect said first section of said inner cavity and said outer cavity; and wherein said hydraulic fluid in said first section of said inner cavity and said outer cavity cooperate to simultaneously supply the suspending spring force; and a controllable valve adapted to selectively restrict passage of said compressible fluid between said first section of said inner cavity and said outer cavity, the controllable valve being normally open and actuated to restrict the passage of the compressible fluid between said first section of said inner cavity and said outer cavity.