Articulated lumbar support for a seat

Abstract

A user adjustable lumbar support apparatus for inclusion in a seat back, comprising an essentially rigid back plate having front and rear surfaces and adapted to extend vertically within a seat back, a front plate having a front and back surface and having an orthotic lumbar support contour at its said front surface, the contour preferrably being generally concave side-to-side and convex top-to-bottom, and a multi-chambered fluid actuator including at least a pair of independently inflatable chambers arranged vertically one chamber above the other, together with elastic means supporting the actuator and the front plate in assembled relationship to the back plate with the chambers between said plates to accommodate relative motion between the plates as the chambers are inflated and deflated. The fluid actuator preferrably is a distendable chamber member containing separated enclosed fluid receiving chambers. Fluid under pressure is admitted and vented separately to and from each chamber to alter the positional relationship of the front plate to the back plate so the lumbar support contour can be adjusted to a position giving optimum support at a desired elevation along the seat back. An elastic strap confines the fluid chamber member between the plates, such strap being attached at its ends to one of the plates and engaged with the other plate to urge the plates together with the fluid chamber member between the plates. There is a resilient support for the back plate about a generally vertical axis of the seat back to allow compliant rotational motion of the support assembly within the seat back in response to like motion of the torso of a person seated against the seat back.