Door beam assembly with roll formed beam

A door beam assembly for a passenger vehicle comprises a roll formed longitudinally-swept tubular beam having a constant cross section defining a generally-orthogonal shape, with the outside wall having an integral channel rib formed into the wall to stiffen the wall. C-shaped mounting brackets are attached to beam ends, with opposing walls welded to and supporting walls of the beam, and with a transverse wall spaced from the adjacent wall of the beam. In one aspect, right and left door beam assemblies includes identical beams, front and rear mounting brackets attached to each end, and identical center brackets.

BACKGROUND

The present invention relates to door beam assemblies used in modern passenger vehicles to provide side impact resistance during a vehicle crash.

Many door beam assemblies exist for providing side impact strength in passenger vehicles. However, improvements are desired to reduce cost, reduce weight, increase impact strength, maintain consistency and repeatability of energy absorption during an impact (i.e. the beam's force-deflection curve), improve manufacturability including reducing secondary manufacturing operations, and improve assemble-ability. This is not easily accomplished given many conflicting requirements, including the need to stay within a desired package space and to provide mounting brackets on ends of the beam and along sides the beam for both right-side and left-side vehicle components.

SUMMARY OF THE PRESENT INVENTION

In one aspect of the present invention, a door beam assembly for a passenger vehicle comprises a tubular beam having a constant cross section, the constant cross section having top, inside, outside, and bottom walls generally defining a non-circulate tubular shape, at least one of the inside and outside walls having an integral rib formed therein that adds stiffness to the one wall, and including mounting brackets on ends of the tubular beam for attaching the tubular beam to a door assembly.

In another aspect of the present invention, a door beam assembly for a passenger vehicle comprises a tubular beam having a constant cross section, the constant cross section having top, inside, outside, and bottom walls; and mounting brackets attached to ends of the tubular beam, the mounting brackets having opposing walls welded to the top and bottom walls and having a transverse wall connecting the opposing walls that is spaced from the inside wall.

In another aspect of the present invention, a door beam assembly for a passenger vehicle comprises a tubular beam having a constant cross section and longitudinal curve, the constant cross section having top, inside, outside, and bottom walls; and mounting brackets on ends of the tubular beam, the mounting brackets having opposing walls welded to and supporting the top and bottom walls.

In another aspect of the present invention, a set of door beam assemblies for a passenger vehicle comprises right and left door beam assemblies, each including a beam having a continuous cross section, front and rear mounting brackets attached to each end, and a center bracket; at least one of the beam, the front and rear mounting brackets and the center bracket being identical on each of the right and left door beam assemblies.

Methods related to the above also form a part of the present invention.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

A door beam assembly20(FIG. 1) is provided for mounting inside the door of a passenger vehicle. The assembly20comprises a roll formed longitudinally-swept tubular beam21having walls26-27,31-33forming a constant cross section defining a generally orthogonal rectangular shape, with the outside/exterior wall25-27having an integral channel rib26formed to stiffen the wall. C-shaped mounting brackets22,23are attached to beam ends with opposing walls28,29on bracket22being welded to and supporting top and bottom walls31,32of the beam21, and with a transverse wall30being spaced from the adjacent inside wall33of the beam21, and with opposing walls35,36on bracket23being welded to and supporting top and bottom walls31,32of the beam21, and with a transverse wall37being spaced from the adjacent inside wall33of the beam21. A center bracket(s)24is welded to one of the walls, such as the bottom wall32. In one aspect, right and left door beam assemblies (20) include identical beams21and an identical center bracket24, and different front and rear mounting brackets22,23attached to beam ends.

The illustrated beam21is roll formed of a high strength steel material, such as a tensile strength of about 450-550 MPa (80-100 ksi) and a thickness of 1.6-3 mm thickness. However, it is contemplated that other materials of higher or lower strength and/or higher or lower thicknesses can be used, depending on functional requirements. For example, an ultra high strength steel material could be used having a tensile strength of 1500 MPa (270+ksi) and thickness of less than 1 mm (such as 0.8 mm) for an extra high strength and low weight. A rectangular cross sectional shape defined by the walls22-25of the beam21allows it to be roll formed using a process not unlike that shown in Sturrus U.S. Pat. Nos. 5,092,512 and 5,454,504, the entire contents of which are incorporated herein for their teachings. The longitudinal curvature (i.e. “sweep”) in the illustrated beam21is relatively small, but it is contemplated that beams can be made less curved or more curved, depending on a vehicle's design.

A shape of the beam21as used in a door beam is believed to be novel, unobvious, and patentable. Specifically, the rectangular cross sectional shape of the beam21is believed to be unusual for door beams, in that it is about 45 mm deep (in a cross car direction) and about 31 mm high (in a vertical direction), and it includes an inboard/inside wall25-27formed by three curves. The three curves include the channel rib25in a center location and two protruding radiused sections26,27on each side of the channel rib25. The illustrated protruding sections26,27define a radius of about 5-7 mm, and the illustrated channel rib25has a radius of slightly less than 5 mm and slightly less than 180 degrees. However, it is contemplated that the protruding sections and channel rib may have alternative shapes and sizes, depending on functional requirements of a particular door beam assembly. Testing has shown that the channel rib25stiffens and stabilizes the inside wall26,27and generally stabilizes the beam21, resulting in improved impact strength and energy-absorbing characteristics, particularly with the ultra-high strength materials and thin materials used in the illustrated beam21.

The illustrated beam assembly20is for a left driver-side vehicle door, but persons skilled in the art will recognize that a right passenger-side vehicle door can be constructed using parts to form a mirror image. Artisans will also recognize that the right vehicle door can use an identical beam21and an identical center bracket24if desired.

The brackets22-24are formed from a stampable steel material, such as a steel sheet having tensile strengths much lower than that used for beam21. The illustrated brackets22,23each have a U-shaped portion that engages the beam21, and a Z-shaped attachment flange extending from the U-shaped portion with bolt-receiving apertures for attachment to a door frame on the vehicle door. The U-shaped portion includes opposing walls28,29and transverse wall30. The walls28and29lie adjacent the top and bottom walls23,24of the beam21and are welded to them. The transverse wall30is spaced from the adjacent inside wall22of the beam21, such as to define a gap of about 4 mm. This facilitates secondary assembly, and adds to the overall impact strength and consistency of impact strength and energy-absorbing capability of the present door beam assembly20. The attachment flange is configured to matingly engage mating material on the door frame and can include weld pad areas or apertures for fastener attachment as required.

A modified door beam assembly20A (FIGS. 9-12) is provided for mounting inside the door of a passenger vehicle. The assembly20A comprises a roll formed longitudinally-swept tubular beam21A having walls26A-27A,31A,31AA,32A,32AA, and33A forming a constant cross section defining a generally horseshoe-like shape, with the outside/exterior wall26A-27A having an integral channel rib25A formed to stiffen the wall. The top wall31A,31AA includes a horizontal wall section31AA and an angled wall section31A. Similarly, the bottom wall32A,32AA includes a horizontal wall section32AA and an angled wall section32AA. The channel25A is relatively deep, such as about ½ of the total dimension of its cross sectional shape. The horizontal wall portions31AA and32AA extend generally parallel each other on opposing sides of the deep channel rib25A. The angled wall sections31A and32A extend toward each other slightly from horizontal wall sections31AA and32AA and connect to the wall section33A with relatively small radius (as compared to the radius of the channel rib25A and the radii of walls25A,27A. A cross sectional shape of the beam21A along with the deep channel rib25A and with angled wall portions31A,32A provides a door beam21A having optimal impact and energy-absorbing characteristics, including quick initial resistance to bending during an impact, a continued high level of resistance to bending during continued impact stroke (during which time a substantial amount of energy is absorbed into the beam), and a more predictable collapse and predictable energy-absorption during failure (when the beam begins permanent deformation with its walls bending and crushing along multiple deformation lines).

C-shaped mounting brackets22A,23A are attached to beam ends, with opposing walls28A,29A on bracket22A being welded to and supporting top and bottom walls31A,31AA,32A,32AA of the beam21A, and with a transverse wall30A being spaced from the adjacent inside wall33A of the beam21A, and with opposing walls35A,36A on bracket23A being welded to and supporting top and bottom walls31A,31AA,32A,32AA of the beam21A, and with a transverse wall37A being spaced from the adjacent inside wall33A of the beam21A. A center bracket(s)24A is welded to one of the walls, such as the bottom wall32A. In one aspect, right and left door beam assemblies (20A) include identical beams21A and an identical center bracket24A, and different front and rear mounting brackets22A,23A attached to beam ends.