Seat suspension

Abstract

Disclosed is a shock absorbing suspension system supporting a seat on a floor of a vehicle. The suspension system includes a hydraulic bag filled with a liquid and coupled to support the seat on the floor, the hydraulic bag having a valve orifice. The suspension system also includes a reservoir partially filled with liquid, having a lower orifice, an upper orifice, and a baffle positioned adjacent the lower orifice to impede the liquid from escaping through the upper orifice. An adjustable valve has an internal passageway communicating with the hydraulic bag via its valve orifice and the reservoir via its lower orifice to allow the liquid from the hydraulic bag to pass into the reservoir. The passageway can be made sufficiently small to dampen motion of the seat toward and away from the floor. The reservoir includes a supply of gas in direct communication with the liquid, the gas being compressed when the liquid enters the reservoir through the valve, thereby providing a spring. Gravity keeps the gas above the liquid in the reservoir and out of the valve without requiring a diaphragm to maintain gas/liquid separation. In one embodiment, a vent line connects a vent orifice of the hydraulic bag with a vent orifice of the reservoir to allow gas to escape from the hydraulic bag to the reservoir.