Suspension system for a vehicle including an accumulator

A suspension system for a vehicle having a wheel contacting a surface under the vehicle and a suspension link suspending the wheel from the vehicle and allowing relative movement of the wheel and the vehicle, said suspension system comprising:

• a suspension strut adapted to couple the suspension link and the vehicle;
• a hydraulic cavity at least partially defined by said suspension strut and adapted to contain a portion of a fluid and to supply a suspending spring force that biases the wheel toward the surface;
• an accumulator adapted to contain a portion of the fluid at a predetermined pressure above atmospheric pressure;
• a volume modulator in fluidic communication with said hydraulic cavity and said accumulator and adapted to selectively push the fluid into said hydraulic cavity and vent the fluid from said hydraulic cavity, thereby actively modulating said suspending spring force, wherein said volume modulator includes a modulator housing defining a modulator cavity, a crankshaft, a modulator piston coupled to said crankshaft and adapted to cycle through a compression stroke and ar expansion stroke within said modulator cavity, a cavity-side valve coupled between said hydraulic cavity and said volume modulator and adapted to selectively restrict the passage of the fluid between said hydraulic cavity and said modulator cavity, and an accumulator-side valve coupled between said accumulator end said volume modulator and adapted to selectively restrict the passage of the fluid between said reservoir and said modulator cavity;
• a compressible fluid;
• wherein said hydraulic cavity is further adapted to cooperate with said compressible fluid to supply the suspending spring force.