Suspension system for an automotive vehicle

A method of controlling a relative movement of a wheel assembly and a body of an automotive vehicle using a suspension system comprising:

• a hydraulic actuator connecting the wheel assembly and the body;
• and
• a hydraulic system configured to provide a supply of fluid to the hydraulic actuator,
• wherein the hydraulic system comprises:
• a plurality of gas accumulators,
• a common flow path connecting the hydraulic system to the hydraulic actuator,
• and one or more valves;
• wherein each gas accumulator of said plurality of gas accumulators is connected to the common flow path via an associated valve, each associated valve being associated with one or more gas accumulators and independently actuatable to place one or more of said associated gas accumulators in fluid communication with said common flow path, such that, when said associated valve is in an open position corresponding to a selected gas accumulator, pressure changes in said common flow path are transmitted to gas in the selected gas accumulator, and when said associated valve is in a closed position corresponding to said selected gas accumulator, pressure changes in said common flow path are not transmitted to gas in said selected gas accumulator;
• wherein the hydraulic actuator comprises:
• a piston comprising a rod and a piston head mounted on the rod, and
• a piston housing,
• wherein:
• the piston is mounted for movement within a cavity formed within the piston housing, and
• a first side and a second side of the piston head divides the cavity into a first chamber and a second chamber, wherein an effective surface area of the first side of the piston head is larger than an effective surface area of the second side of the piston head,
• the first chamber is connected to the common flow path via at least one first piston flow path, and
• the second chamber is connected to the common flow path via at least one second piston flow path;
• wherein controlling the relative movement of the wheel assembly and the body is performed by:
• providing fluid via the hydraulic system to the hydraulic actuator via the common flow path at a total pressure equal to or greater than 7 MPa (70 Bar) for a first time period, and
• during the first time period:
• (1) causing one or more changes in the total pressure in the common flow path, and
• (2) transmitting each of the one or more changes in the total pressure in the common flow path to (i) the first chamber via the at least one first piston flow path and (ii) the second chamber via the at least one second piston flow path;
• and
• the method further comprising, during the first time period, changing a stiffness of the hydraulic actuator by actuating the associated valve to switch the hydraulic system between a first configuration in which the associated valve of a first gas accumulator of said plurality of gas accumulators is in an open position and the associated valve of a second gas accumulator of said plurality of gas accumulators is in a closed position, and a second configuration in which the associated valve of the first gas accumulator is in a closed position and/or the associated valve of the second gas accumulator is in an open position.