The invention relates to a door beam for vehicles with attachment ends to the vehicle and a double hat profile between the attachment ends, comprising two outer side walls with lateral flanges, two inner side walls, two apexes defined between the outer and inner side walls and directed outwards from the vehicle, and an apex defined between the inner side walls and directed inwards towards the vehicle.

Prior art

Door beams with a double hat profile are known, for example from US 8,061 ,762 B2.

Object of the invention

The object of the invention is to give the door beam a favourable deformation progression in the event of a lateral collision and thereby increase its energy take-up in relation to its weight and to the maximum profile height.

Brief description of the invention

The object of the invention is achieved when the height of the outer side walls decreases from a central part of the beam towards the attachment ends, so that the ratio in height between the outer and the inner side walls decreases towards the attachment ends. The invention is defined by the claims.

Brief description of the drawings

Figure 1 is a view of a door beam according to the invention.

Figure 2 shows six cross sections of the door beam taken as indicated by the lines 1-6 in figure 1.

Description of the illustrated example of the invention

The door beam shown in the figures consists of thin, high-strength steel plate. It can be formed and hardened using press hardening technology, i.e. thermoformed and hardened in the same operation in cooled forming dies. It has two attachment ends 12, 13 and between the attachment ends it has the double hat profile with two outer side walls 14, 15 with lateral flanges 16, 17 and two inner side walls 18, 19. Between the outer and inner side walls two apexes 20, 21 are formed, directed outwards from the vehicle. Between the inner side walls an apex 22 is formed that is directed inwards towards the vehicle.

On a central part 25 of the beam, the profile is constant, and from this central part the height of the outer side walls 14, 15 decreases at least in one direction over a length of at least ¼ of the length of the beam, or as shown in both directions. In the example it is shown that the height of the side walls decreases symmetrically in both directions in continuous curves, but symmetry is not necessary. The height of the outer side walls 14, 15 decreases towards the attachment ends 12, 13 so that the ratio in height between the outer and inner side walls diminishes towards each attachment end over a length of at least ¼ of the length of the beam. The height of the inner side walls 18, 19 can remain constant as shown. A central part with a constant profile is not necessary.

The attachment ends 12, 13 can have a different appearance. In the example, the attachment end 12 is shown completely flat, while the attachment end 13 has a profile. It can have a low single hat profile or a low double hat profile, for example.