Field of the invention

This invention relates to a bumper arrangement for vehicles including an open bumper beam in which the central part of the bumper beam between two attachment portions has a central flange and two webs forming a U-section open towards the vehicle, wherein the central flange has a central groove gradually deepening from the centre of the beam to the attachment portions at the ends of the bumper beam so that the beam has an inverted U-section open away from the vehicle, the central groove forming the central flange of the U-section and two webs, the height of which is greatest at the attachment portions, and the original central flange forming side flanges on either side of the U-section.

Prior art

A bumper beam of the aforementioned type is known from WO 2008/057025. It is designed to be fastened by means of a flat portion.

WO 2007/136320 describes the attachment of a bumper beam to two crash boxes in which the bumper beam is welded to recesses in the crash boxes.

Aim of the invention and brief description of the invention

The aim of the invention is to provide improved deformation properties over the entire width of the vehicle in the event of collisions of various types. This is achieved by means of two crash boxes having a closed profile with an upper surface, a lower surface and two vertical sides and having recesses at the ends of the vertical sides adapted to the inverted U-section of the bumper beam and welded to the inverted U-section at the attachment portions, wherein the inverted U-section continues beyond the attachment portions with the web height decreasing towards the ends.

The invention is defined by the claims. Brief description of the drawings

Figure 1 is a perspective view of a bumper arrangement according to this invention, the bumper beam being viewed from the outside towards the vehicle. Figure 2 shows the same arrangement viewed from the vehicle and outwards.

Figure 3 shows the same arrangement viewed directly from above.

Figure 4 is a section along the line 4-4 in Figure 3.

Figures 5 and 6 show a section along the line 5-5 in Figure 3, but with the elements separated.

Detailed description of illustrated embodiment of the invention

The figures show a bumper beam 11 attached to two crash boxes 12, 13. The crash boxes are designed to be attached to load-bearing parts of the vehicle. The crash boxes are usually attached to the ends of the side beams of the vehicle by means of bolts so that the bumper, i.e. the bumper beam and the crash boxes, can be mounted and removed as one unit.

As shown in Figure 4, the bumper beam is provided in its central section with a central flange 14 and two webs 15, 16. The webs end in side flanges 17, 18. The central flange has a relatively shallow central groove 19. The bumper beam thus has an open U-section with the opening directed towards the vehicle. The central groove 19 gradually deepens from the central section outwards and the U-section is inverted at the two attachment portions 20, 21 of the bumper beam, i.e. the central groove 19 forms the central flange 22 and two webs 23, 24 of the inverted U-section, and the outer portions of the central flange 14 in Figure 4 form side flanges 32, 33 together with the original side flanges 17, 18, as will be seen most clearly from Figure 6. Beyond the attachment portions, the depth of the central groove 19 gradually decreases again as shown, but the beam provides good crash protection even beyond the attachment portions. The central portion of the bumper beam is strong by virtue of the fact that it has both the central groove 19 and high webs 15, 16. As the central groove 19 deepens, the height of the webs 15, 16 simultaneously decreases.

The two crash boxes 12, 13 are identical, but of reversed design and only the crash box 12 and the attachment thereof are therefore described. The crash box 12 has an upper surface 25, a lower surface 26 and two sides 27, 28, which are vertical. The crash box thus has a closed profile and is shown with completely straight and vertical sides, although the sides do not have to be completely straight and vertical. The two vertical sides 27, 28 of the crash box have recesses 30 at the ends of the crash box. In the crash box 12 shown in Figure 2, the recess is on the inside of the crash box and in the crash box 13, the recess is shown on the outside of the crash box.

Figures 5 and 6 show the crash box 12 and the bumper beam 11 before they are welded together and it will be clear that the recess 30 at the end of the side 27 of the crash box 12 is adapted to the cross section of the bumper beam. A corresponding recess in the other side 28 of the crash box matches the bumper beam in the same manner. The bumper beam 11 does not have exactly the same cross section with respect to the side 28 and the side 27 and the recesses 30 at the ends of both sides are not exactly the same. The recesses 30 in both sides 27, 28 are to be welded to the bumper beam 11 along the contact lines. The upper and lower surfaces 25, 26 of the crash box do not bear against the bumper beam as the recesses in the sides do not extend over the entire height of the sides.

The attachment of the bumper beam to the crash boxes shown is extremely stiff against torsion and, overall, this design of the bumper beam and the attachment thereof result in very favourable deformation characteristics in the event of collisions of various types.