Fastening arrangement of a door sill on the floor panel of a motor vehicle

A fastening arrangement of a door sill on the floor panel of a motor vehicle provides a welded connection between a welding flange on a longitudinal side of the door sill and an edge zone of the floor panel extending laterally next thereto. The welded connection, being distributed along the length of the door sill, has at least one run of spot welds. The butt joint between the welding flange of the door sill and the opposite edge zone of the floor panel is bridged in the rearward length area by a tension member or lug extending transversely thereto. The tension member is fastened by one end on the door sill and by of the other end on the adjacent area of the floor panel.

This application claims priority of DE 199 01 070.6-21, filed Jan. 14,
 1999, the disclosure of which is expressly incorporated by reference
 herein.
 BACKGROUND OF THE INVENTION
 The present invention relates to a fastening arrangement of a door sill on
 the floor panel of a motor vehicle, and more particularly, to an
 arrangement with a welded connection provided between a welding flange on
 a longitudinal side of the door sill and an edge zone of the floor panel
 extending laterally next to it, which welded connection being distributed
 along the length of the door sill, comprises at least one run of spot
 welds.
 In such a fastening arrangement which is used in series produced motor
 vehicles, the door sill is conventionally fixedly connected by a welded
 connection along its longitudinal direction with an edge zone adjoining
 the door sill. For this purpose, the door sill has a welding flange on its
 longitudinal side. The welding flange is welded to the edge zone of the
 floor panel by at least one run of spot welds distributed over the entire
 length of the door sill. This results in a relatively low-cost welded
 connection between the door sill and the floor panel which can easily be
 made by automatic welding machines.
 Particularly in the case of an offset frontal crash with a small width
 overlap of the motor vehicle with another vehicle or other obstacle,
 however, in fastening arrangements of this type, the spot-welded
 connection can fail because of occurring forces. The problem generally
 exists in such an offset frontal crash that, as the result of the accident
 forces acting in the front in the area of a forward wheel house, the motor
 vehicle is acted upon by a torsional force about a vertical axis of the
 vehicle. As a result, very high superimposed forces act between the door
 sill arranged on the side of the impact and the floor panel connected
 therewith, because the door sill arranged on the side of the impact is
 very decelerated in its movement within a short time, while, in contrast,
 the floor panel is acted upon by a torsional force about the
 above-described vertical axis of the vehicle. The spot-welded connection,
 which connects the door sill with the floor panel, is therefore stressed
 excessively particularly by tension forces, whereby the run of spot welds
 rips open, starting from the rearward end of the welded connection, in the
 direction toward the front, and the floor panel detaches from the door
 sill.
 A bearing structure for a motor vehicle is shown in DE 40 08 703 A1 which
 has a relatively stiff supporting member and an adjoining thin-walled
 metal sheet. There, the supporting member has a so-called welding flange
 by way of which it is connected with the metal sheet. In order to prevent
 a destruction of the connection between the supporting member and the
 metal sheet in the event of impact-caused tension peaks, for example, in
 the event of a side impact, and in order to permit a uniform and
 large-surface introduction of force into the metal sheet, one or several
 projections are molded to the welding flange. The projections are
 connected with the metal sheet by welding. These measures are, however,
 not provided and suitable for avoiding particularly a tearing-off of the
 floor panel from the door sill. In addition, the construction of the
 welding flange with projections requires very high manufacturing
 expenditures.
 SUMMARY OF THE INVENTION
 An object of the present invention is to provide a fastening arrangement
 which has a better crash behavior in the event of an offset frontal crash
 with a small width overlap of the motor vehicle with another vehicle or
 another obstacle, which, in addition can be manufactured in a simple
 manner and at reasonable cost.
 According to the invention, this object has been achieved by a fastening
 arrangement in which the butt joint between the welding flange of the door
 sill and the opposite edge zone of the floor panel is bridged in the
 rearward length area by a tension member (lug) extending transversely
 thereto, the tension member being fastened by means of one end on the door
 sill and, by means of the other end, on the adjacent area of the floor
 panel.
 In the fastening arrangement according to the present invention, the butt
 joint between the welding flange of the door sill and the opposite edge
 zone of the floor panel is bridged in its rearward length area such by a
 tension member extending transversely thereto that the forces which occur
 particularly in the event of an offset frontal impact with a small width
 overlap of the involved motor vehicles can be absorbed particularly
 effectively between the door sill arranged on the side of the impact and
 the floor panel connected with the door sill. The spot-welded connection,
 which connects the door sill with the floor panel, is therefore relieved.
 An unbuttoning of the run of weld spots starting from the rearward end of
 the welded connection in the area of the rearward weld house in the
 direction toward the front and a tearing-off of the floor panel from the
 door sill is effectively avoided. Because the tension member must only be
 arranged in the rearward length area of the butt joint in order to avoid
 the unbuttoning, the fastening arrangement can be produced in a relatively
 simple manner and at correspondingly reasonable cost.
 Thus, a run of weld spots along a butt joint extending essentially in the
 vertical direction of the vehicle is particularly easily accessible and
 producible for an automatic welding machine.
 It was also found to be advantageous to fix both ends of the tension member
 by spot-welded connections which can be made particularly rapidly and
 easily when manufacturing the motor vehicle.
 A tension member, can be is constructed as a separate angle piece with a
 first leg and another leg and can be manufactured in a simple manner and
 at reasonable cost. The two legs can, for example, be formed to rest on
 the door sill and the floor panel without high expenditures and can be
 connected therewith by a welded connection. The legs preferably enclose an
 obtuse angle of approximately 100-150.degree., whereby the transmission of
 high tension forces can be ensured in a crash.
 If the two legs each rest by a broad side on a side of the welded flange
 facing away from the butt joint or in the area of a rearward wheel house
 on the adjacent area of the floor panel, a particularly tension-proof
 connection can also be established between the tension member and the
 welded flange or the floor panel.
 In particular, an approximately horizontally extending first leg has been
 found to be advantageous because it can be fixed in a simple manner on the
 welding flange by way of a spot-welded connection existing anyhow. In
 order to permit a particularly good fastening of the tension member within
 the wheel house, the additional leg extends, starting from the first leg,
 preferably diagonally upwards.
 If the tension member is fastened in the area of the rearward wheel house
 on a wheel house panel connected with the floor panel, the additional leg
 can be arranged in a simple manner at a variable height on the wheel house
 panel.
 The tension member is particularly well protected from environmental
 influences between a wheel house panel situated on the inside and a wheel
 house panel situated on the outside, the fastening of the tension member
 is, in addition, suitable for absorbing particularly high tension forces.
 Finally, the tension member is fixed on the welded flange and on the edge
 zone of the floor panel by one rivet per leg respectively. In this case,
 particularly the rivet arranged between the first leg and the door sill or
 the floor panel counteracts an unbuttoning of the run of weld spots.
 The tension member can be formed as a separate angle piece having a first
 leg and a second leg, which legs enclose an obtuse angle (.alpha.) of
 between approximately 100 to 150 degrees.

DETAILED DESCRIPTION OF THE DRAWINGS
 FIG. 1 is a side view of a motor vehicle with a right door sill 10 which
 extends in the longitudinal direction of the vehicle between a forward and
 a rearward wheel house 11, 12 and is covered here by a door sill cover 13.
 The door sill 11 is connected by a fastening arrangement along its
 approximately entire length with a floor panel 14 by a welded connection.
 The fastening arrangement of the door sill 10 on the floor panel 14 is, of
 course, mirror-symmetrically provided with respect to a longitudinal
 center plane on both sides on the motor vehicle.
 In FIG. 1, FH indicates a vertical axis of the vehicle about which, in a
 frontal crash with a small width overlap of the involved motor vehicles,
 the motor vehicle is torqued by a force which occurs, for example, in the
 forward right frontal area.
 FIG. 2 shows a side wall 15 between approximately the forward and the
 rearward wheel house 11, 12 of the motor vehicle illustrated in FIG. 1, at
 whose lower end the door sill 10 is fixedly arranged and is fixedly
 connected with the floor panel 14 by way of the fastening arrangement. In
 an enlargement, FIG. 3 shows the fastening arrangement according to the
 detail III in FIG. 2. For reasons of clarity, the door sill covering 13 is
 not shown in FIGS. 2 and 3.
 The door sill 10 has an approximately box-shaped profile formed of several
 partial shells, which profile will be explained in detail particularly
 with reference to FIG. 4. At its rearward end, the door sill 10 is bounded
 by a wheel house panel 17 which extends in the circumferential direction
 of the wheel house 12 and is situated in the interior. The
 interior-situated wheel house panel 17 is welded to an adjoining front
 panel 18 which extends in the longitudinal direction of the vehicle and
 vertically, and forms the front side of the wheel house 12.
 The interior-situated wheel house panel 17 ends in the front at the bottom,
 while extending approximately vertically in the transverse direction of
 the vehicle, at the level of the floor panel 14 welded to it or at the
 level of the underside of the door sill 10. In addition, the wheel house
 panel 17, is covered by a wheel house panel 19 which is situated on the
 exterior and extends in the circumferential direction of the wheel house
 12, and which, while being adapted to the wheel house panel 17 situated in
 the interior, is connected with the wheel house panel 17.
 The exterior-situated wheel house panel 19 is shown only in a cutaway
 manner in the upper area of the wheel house 12. It ends in the front on
 the bottom, while extending approximately vertically in the transverse
 direction of the vehicle, at the level of the wheel house panel 17
 situated in the interior. The exterior wheel house panel 19 is connected
 with the floor panel 14 or the door sill 10 by the interior wheel house
 panel 17. A lower longitudinal side 21 of the door sill 10, which extends
 approximately horizontally in the longitudinal direction of the vehicle,
 has a downwardly bent welding flange 22 which extends approximately in the
 vertical direction of the vehicle and which is connected with an edge zone
 23 of the floor panel 14 adapted to it and extending laterally in the
 interior, along a butt joint 24 (FIG. 4), which extends approximately in
 the vertical direction of the vehicle, by way of a spot-welded connection
 with a run of spot welds 25.
 In the corner area between the door sill 10 and the interior wheel house
 panel 17 with the floor panel 14, a lug-type tension member 26 is assigned
 to the fastening arrangement. The tension member 26 is constructed here as
 a separate angle piece whose shape is more fully illustrated in FIGS. 5a
 and 5b. It would also be within the scope of the present invention for the
 tension member 26 to be constructed in one piece with the door sill 10 or
 with the floor panel 14. The first end of the tension member 26 is
 fastened by a first leg 27 which, by way of its broad side 28, rests on
 the outside on a side 29 of the welding flange 22 facing away from the
 butt joint 24. On its other end, the tension member 26 is fastened in the
 area of the rearward wheel house 12 by a broad side 31 of its other leg
 30, to an adjacent area 32 of the floor panel 14. In the illustrated
 embodiment, the additional leg 30 extending transversely to the butt joint
 24 is connected by its broad side 31 by way of the interior wheel house
 panel 17 arranged between the tension member 26 and the floor panel 14
 with the adjacent area 32 of the floor panel 14.
 The first and the additional leg 27, 30, as illustrated particularly in
 FIGS. 5a and 5b, enclose an angle .alpha. of approximately 110.degree. as
 seen in FIG. 5b. The first leg 27 of the tension member 26 extends
 approximately horizontally in the longitudinal direction of the vehicle
 and is arranged on the welded flange 22 by means of a spot-welded
 connection. The additional leg 30, starting from the first leg 27, extends
 at an angle .beta. (FIG. 5a) of approximately 25.degree. diagonally upward
 and is fastened, preferably also by a spot-welded connection, to the
 interior wheel house panel 17 and to the floor panel 14.
 The exterior wheel house panel 19 is pulled downward approximately to the
 level of the floor panel 14, and the tension member 26 is fixedly arranged
 between the interior and the exterior wheel house panel 17, 19. The two
 wheel house panels 17, 19 with the tension member 26 arranged therebetween
 can then also be connected with the floor panel 14 by way of a single
 spot-welded connection.
 In another contemplated embodiment, the exterior wheel house panel 19 which
 is connected to the interior wheel house panel 17 by a welded connection,
 ends above the tension member 26, so that the tension member 26 is welded
 only to the interior wheel house panel 17. The first leg 17 fastened to
 the welding flange 22 of the door sill 10 is preferably fastened to the
 welding flange 22 by way of the spot-welded connection which connects the
 welding flange 22 with the adjoining edge zone 23 of the floor panel 14.
 The first leg and the additional leg 27, 30 are fastened on the welding
 flange 22 or on the edge zone 23 of the floor panel 14, additionally to
 the welded connection, by at least one rivet (e.g., punch-type rivet 33)
 respectively which penetrates the welding flange 22 and the edge zone 23.
 The punch-type rivet 33, which fixes the first leg 27 on the welding
 flange 22, is preferably arranged instead of the rearmost weld spot, which
 connects the tension member 26 with the welding flange 22 and the edge
 zone 23, at the rearward end of the door sill 10, to ensure a particularly
 good connection between the tension member 26 and the welding flange 22 in
 the event of a crash. By way of the door sill covering 13 as well as by
 way of an interior wheel housing covering (not shown) and by way of which
 the wheel house 12 is covered on the interior side with respect to the
 rear wheel (not shown), the tension member 26 is covered and therefore
 protected from environmental influences.
 FIG. 4 is a sectional view of the fastening arrangement along line IV--IV
 in FIG. 3. The door sill 10 can be covered on the outside and on the
 bottom by the door sill covering 13 which is fastened on the door sill 10
 by receiving devices. The door sill 10 consists of an inner partial shell
 35 and an outer partial shell 36, which bound the side wall 15 in the
 downward direction. Only the downwardly bent edge zone 23, which extends
 approximately in the vertical direction of the vehicle, is visible of the
 floor panel 13 and rests against the interior partial shell 35 and is
 connected therewith, for example, by a spot-welded connection extending
 along the entire length of the door sill 10.
 As illustrated in FIG. 4, the downwardly bent welding flange 22 is
 constructed in one piece with the exterior partial shell 36 of the door
 sill 10. The outer partial shell 36 of the door sill 10 is fixedly
 connected by the downwardly bent edge zone 23 of the floor panel 14 with
 the inner partial shell 35 of the door sill 10. The first leg 27 of the
 tension member 26 is fastened on the outside resting on the side 29 of the
 welding flange 22 facing away from the butt joint 24. The first leg 27,
 the welding flange 22 and the edge zone 23 are connected with one another
 by the spot-welded connection along the butt joint 24 and additionally by
 the punch-type rivet 33. For achieving even better stability
 characteristics, as illustrated in FIG. 4, the first leg 27 can be bent at
 the top. The additional leg 30 can also be bent at the top.
 The lug 26 shown in FIGS. 5a and 5b has several projections in the area of
 the first leg 27. These projections adapt the first leg 27 to the welding
 flange 22. In order to obtain, in the event of a crash, a particularly
 stable connection of the door sill 10 and the floor panel 14, a last
 section 37 of the first leg 27 extends at an angle of approximately
 15.degree., and the additional leg 30 extends at an angle .beta. of
 approximately 25.degree. with respect to the horizontal line in the upward
 direction.
 In order to achieve a flat contact of the additional leg 30 on the interior
 wheel house panel 17, this leg 30, as illustrated in FIG. 5b, is bent in a
 flat manner. The tension member 26 is formed of a steel band. It is also
 contemplated to use other steel profiles, such as tubes or the like, which
 are suitable for transmitting larger tension forces. Further, it would
 also be within the scope of the present invention to use, instead of a
 steel profile, a plastic profile made of the fiber composite or the like,
 or an aluminum profile, which the tension member 26 would then have to be
 arranged on the floor panel 14 and the welding flange 22 by a different
 connection, e.g., a riveted or screwed connection.
 The foregoing disclosure has been set forth merely to illustrate the
 invention and is not intended to be limiting. Since modifications of the
 disclosed embodiments incorporating the spirit and substance of the
 invention may occur to persons skilled in the art, the invention should be
 construed to include everything within the scope of the appended claims
 and equivalents thereof.