Semi-active suspension system with energy saving

Abstract

A semi-active suspension system having a linear actuator operatively connected between a sprung mass and an unsprung mass of the vehicle for each corner of the vehicle. An accumulator connected to the actuator through an electrically controlled valve. An actuatable fluid RAM is in fluid communication with the accumulator for controlling fluid pressure in the accumulator. A hydraulic ram driver is operatively connected to the RAM. A sensor senses force inputs to the vehicle. A controller controls (i) the ram driver for pressurizing the accumulator to a desired fluid pressure, and (ii) the electrically controlled valve in response to sensed force input so as to effect a fluid pressure change in the actuator. Each fluid RAM includes a hydraulic motor having a housing and a piston slidably mounted in the housing. The piston divides the housing into two variable volume fluid chambers, one fluid chamber in fluid communication with the accumulator and a second fluid chamber in communication with the second fluid chambers of each RAM of the other corners of the vehicle. This arrangement permits movement of the piston of the fluid RAM with reduced energy.