GB1398524A - Energy absorbing device - Google Patents

Abstract

1398524 Collapsible steering columns; bumpers WALTON & CO (WOLVERHAMPTON) Ltd 26 Oct 1972 [28 July 1971] 35467/71 Headings B7H and B7J [Also in Division F2] A collapsible steering column or bumper mounting incorporates an energy-absorbing, shock-absorbing or load-limiting device comprising a tube and a plunger, the cross-sectional shape of the interior of the tube being different from the cross-sectional shape of the exterior of the plunger, the plunger having portions which contact the inner surface of the tube and which, when the the plunger is forced relatively into and along the tube, force the tube walls outwards at the places of contact, the actual periphery of the plunger in cross-section or, where the plunger has one or more recesses, the notional shortest periphery around the outermost surfaces of the plunger, being less than the internal periphery of the tube so that when the plunger is forced relatively along the tube the development of tensile stresses in the tube walls is inhibited and the internal periphery of the tube remains constant, or substantially so, in length. A circular-section steel plunger 1 inch in diameter has one end tapered and engaged in a mild steel tube of square cross-section, the wall being # inch thick and the length of the side of the internal square being # inch. Instead of square the tube may have a hexagonal, or other polygonal, section. A square-section plunger may be used with a circular-section tube whose internal diameter is less than the diagonal of the square. A tube with longitudinally-extending corrugations, e.g. twelve, is associated with a circularsection plunger sufficiently large in diameter to engage and deform the inwardly-directed portions of the corrugations. The plunger may be tubular and subject to deformation. The degree of initial interengagement is sufficient to ensure transmission of torque when the device forms part of an axially collapsible steering column.