Elastic supporting structure for seats

An elastic supporting structure of plastics material for seats in general, comprising a plate (1) of plastics material provided with a plurality of rectilinear hollow ribs (2) having a substantially V-shaped transverse cross-section and converging from the peripheral zone (3) of the plate towards its central zone where the plate is provided with an aperture (4), the peripheral zones of the plate, from which the ribs extend, being provided with chamfers (3) with respect to the contour of the plate itself, and the depth of the ribs varying in the sense that it decreases linearly along the ribs from the central zone of the plate towards the peripheral zone of the plate. The plate may be attached to or integrally moulded with, a seat frame.