Patent GB-1426265-A (GB)
Title: Energy absorber components
IPC: B62D21/15
Filed: 1973-05-04
Abstract: 1426265 Vehicle bodies; vehicular safety devices; vehicle bumpers GENERAL MOTORS CORP 4 May 1973 [8 May 1972 17 May 1972 11 Aug 1972] 21303/73 Headings B7B B7H and B7J [Also in Division F2] An energy-absorber component of a vehicle comprises a hollow member which is filled with a foam substance and which; in the event of an impact stress taking place in the direction of its longitudinal axis, is deformable substantially over its entire cross-section lying at right angles to the direction of impact, the walls of the hollow member being formed of a foldable sheetmetal material, and the specific weight and hardness of the foam substance being in such relation to the thickness of the walls of the hollow member that, under the impact stress; the foam substance reinforces the walls so that deformation of the component occurs by substantially uniform folding of the walls of the hollow member, proceeding from one end of the component. As shown in Fig. 1, the rear portion 10 of an automobile side girder 28 is in the form of a U- section with out-turned flanges 22 covered by the sheet metal vehicle floor 24, the cavity thusformed being filled with polyurethane foam 26 introduced at 32. A planned point of buckling 34, ensuring that the first fold occurs without an undesirable deceleration peak, is provided just behind a sheet metal closure and support plate 14 and may take the form of one or more filler apertures (whereby aperture 32 may be dispensed with). A partition 30 closes the other end of the cavity. Upon impact, when girder portion 10 begins to collapse, Fig. 3, the foam 26 exerts outward pressure upon the side walls so that steady and uniform folding is established, to the right of which the girder portion is not deformed. In Figs. 6 and 8, besides the end portions 10 of the lower side girders 28, similar energyabsorbing members 50, 51, are provided above the portions 10 and in the planes of the wheels. Preferably member 50 is formed partly by the wheel arch 64, Fig. 8, and an angle plate 65; alternatively a triangular-section cavity is formed by the (straight) wheel arch, the adjoining wing 68 and a lower closing plate (69, Fig. 9, not shown). Further energy-absorbing components 56 may be provided under the bonnet 54, Figs. 6, 8, a component 59 may be interposed between an over-roll bar 58 in the roof and a door lock pillar 57, and a cross member 60 may have spaced foam-filled sections (62, Figs. 7, 16, not shown). End portions 10 and members 50 are joined at the front by a body work portion 44, Fig. 6, and two impact dampers 43 each consisting of a foam-filled hollow member are interposed between this portion 44 and the forward bumper 42. Similar provision is made at the rear. The impact dampers 43 are intended to collapse at an impact speed lower than that appropriate to members 10, 50. In Figs. 10 to 12b (not shown) the forward bumper is connected via four impact dampers and bodywork portion 44 is omitted. In Fig. 13 the steering column 75 and propeller shaft 79 are hollow foam-filled members according to the invention. In Fig. 14 (not shown), a foam-filled buffer ring is additionally interposed between the steering wheel and the instrument panel. In Fig. 17 (not shown), foam-filled structural components are interposed between the instrument panel and the underlying body portion. In Fig. 18 a damping member 121 is interposed between an extension 120 of a back-rest frame 125 and a roof frame 112. In each example the foam may be provided with a cavity so that it forms a hollow body 120, Fig. 25. The inner surface of the hollow body may be formed by the foam itself, in which case a bounding wall must be provided during foam production and filling, and thereafter removed. Alternatively a supporting member 126 of thin sheet metal or plastics, and, optionally, spacing stays 128, may be provided. The outer casing may be formed from two matching angle plates 26, 28, each with a single flange 32 or 30; alternatively it may be formed from two U- section parts with out-turned flanges, welded together (Fig. 24, not shown); these parts may be tapered so as to form a casing of uniformlyvarying cross-section (Figs. 32, 33, not shown), the complete member being located in a vehicle so that the smaller end will receive the impact first. The casing may be seamless hollow member, or formed as a cylinder from a single sheet spotwelded along the meeting edges; such a cylinder may have perforations in its wall which are covered until the foam has hardened (Figs. 30, 31, not shown). Two concentric hollow casings may enclose an annular filling of foam; the inner casing may resemble the outer casing, or consist of expansible material which merely bulges inwards on impact compression of the member endwise (Figs. 19 to 19b, not shown). Members 50, Fig. 6, may be joined by a transverse stay, and each member 50 may be connected by a vertical support inside the door pillar to the lower girder 28 (Figs. 36 to 40, not shown). The filling material is preferably a hard polyurethane foam of specified density, though the easing may contain foams of progressivelydifferent hardness arranged longitudinally. Alternatively the foam may be based on polystyrol or polyvinylchloride. The foam should be compressible and may be introduced alternatively as particles or balls.