Hydraulic suspension for vehicle and multi-functional proportional control valve for the same

A hydraulic suspension system comprising:

• a controller;
• a pump adapted to provide a source of pressurized fluid and a tank adapted to hold a reservoir of fluid, the tank in fluid communication with the pump;
• a suspension cylinder in selective fluid communication with the pump, the suspension cylinder defining a chamber therein adapted to receive pressurized fluid;
• a proportional control valve interposed between the pump and the suspension cylinder and between the suspension cylinder and the tank, the proportional control valve in electrical communication with the controller and in selective fluid communication with the pump, the tank, and the suspension cylinder, the proportional control valve including:
• a control valve portion, the control valve portion including a control valve cage and a hollow spool, the control valve cage defining a longitudinal interior passageway, a tank port, and a pump port, the tank and pump ports in communication with the interior passageway, the spool defining a longitudinal spool passageway and a plurality of cross holes radially arranged about the spool, the cross holes in communication with the spool passageway and the interior passageway of the control valve cage, the spool disposed within the interior passageway of the control valve cage and reciprocally movable over a range of travel between at least a pump flow position in which the pump port of the control valve cage is open and the tank port of the control valve cage is closed and the pump and the pump port of the proportional control valve are in fluid communication with each other and a tank flow position in which the tank port of the control valve cage is open and the pump port of the control valve cage is closed and the tank and the tank port of the control valve are in fluid communication with each other, the spool being biased to the pump flow position, and the control valve portion being adapted such that the spool moves in response to a control signal received from the controller, and
• a logic element portion in communication with the control valve portion, the logic element portion being interposed between the control valve and the suspension cylinder, the logic element in fluid communication with the control valve and in selective fluid communication with the suspension cylinder, the logic element portion including a logic element cage and a logic element poppet, the logic element cage defining a longitudinal interior logic element passageway and a logic element port in communication with the logic element passageway, the logic element passageway in communication with the spool passageway, the logic element poppet disposed within the logic element passageway of the logic element cage and reciprocally movable over a range of travel between a blocking position in which the logic element port of the logic element cage is closed and in which fluid is prevented from flowing out of the chamber of the suspension cylinder and a logic element through-flow position in which the logic element port of the logic element cage is open and in which fluid can flow in either direction between the chamber of the suspension cylinder and the proportional control valve, the logic element poppet being biased to the blocking position such that the logic element poppet remains in the blocking position until a pressure at a fluid region upstream of the logic element poppet at least equal to a crack pressure is applied to the logic element poppet against the biasing force, thereby unseating the logic element poppet from the blocking position and moving the logic element poppet toward the through-flow position, the fluid region upstream of the logic element poppet being in fluid communication with the control valve portion.