BUMPER FOR A VEHICLE

Abstract

A bumper for a vehicle, including at least one profile, in particular an open profile, from a first material, having at least one ribbed structure formed from ribs from a second material, the ribbed structure being disposed along the profile at least in portions and at least in portions being connected to the profile in a force-fitting, form-fitting and/or materially integral manner in order for the profile to be reinforced. The bumper meets the requirements set in the event of collision loads and can be optimized in terms of load is achieved in that the ribbed structure is formed from fiber-reinforced plastic and has at least one first region and one second region, which differ from one another in terms of at least one property.

Claims

1.-14. (canceled)

15. A bumper for a vehicle, comprising: at least one profile from a first material, and a ribbed structure including ribs formed from a second material, said ribbed structure being disposed along at least portions of the profile and at least in portions being connected to the profile in a force-fitting, form-fitting and/or materially integral manner to reinforce the profile, wherein the ribbed structure is formed from a fiber-reinforced plastics material and comprising a first region and a second region that differ from one another in terms of at least one property.

16. The bumper of claim 15, wherein the at least one property relates to one or more of the proportion of the fibers in the plastics material, the occupancy rate, the orientation, and the width and/or the height of the ribs that form the ribbed structure in relation to one region.

17. The bumper of claim 15, wherein the ribbed structure extends substantially completely along the profile, wherein the ribbed structure in a first region which is disposed in the central portion of the profile has a higher rigidity than in a second region that is directly adjacent to the first region.

18. The bumper of claim 15, wherein the regions of the ribbed structure are distributed symmetrically along the profile and includes at least three regions, having in each case dissimilar properties.

19. The bumper of claim 15, wherein the ribbed structure is formed from one or more of glass fibers, carbon fibers, aramid fibers, polyester fibers, natural fibers, recycled fibers and boron fibers embedded in a thermoplastic or thermosetting matrix, wherein the proportion of fiber in the matrix is between 10 and 50% by volume.

20. The bumper of claim 15, wherein the profile is an open deep-drawn profile, an open extruded profile, or an open rolled profile and formed from a metallic material, wherein a cross section of the profile at least in regions is configured so as to be one of U-shaped, hat-shaped and W-shaped.

21. The bumper of claim 15, wherein the ribbed structure is molded in an integral manner or as multiple pieces, said ribbed structure within the open profile being bonded in a materially integral manner.

22. The bumper of claim 15, wherein the profile is formed from a metallic material.

23. The bumper of claim 22, wherein the metallic material is a steel material, having a moderate ductility with an elongation at break of A.sub.80>8%.

24. The bumper of claim 15, wherein at least one region in the ribbed structure is foamed.

25. A method for producing the bumper of claim 15, for a vehicle, comprising: providing a profile from a first material; laying up the profile in an opened injection-molding tool; closing the injection-molding tool and injection-molding a second material to generate at least one said ribbed structure formed from ribs, said ribbed structure at least in portions along the profile being molded thereto and at least in portions being connected in a force-fitting, form-fitting and/or materially integral manner to the profile to reinforce the profile; curing the molded material; and opening the injection-molding tool and retrieving the reinforced profile; wherein the second material is the fiber-reinforced plastics material and a ribbed structure having at least one first region and one second region which differ from one another in terms of at least one property is generated.

26. The method of claim 25, wherein a bonding agent is used, said bonding agent being applied to the first material prior to or after the production of the profile, wherein the bonding agent is provided on an internal side of the profile.

27. A method for producing the bumper of claim 15, for a vehicle, comprising: providing a profile from a first material; providing at least one said ribbed structure formed from ribs from a second material, wherein the ribbed structure is molded from a fiber-reinforced plastics material and has at least one first region and one second region which differ from one another in terms of at least one property; and disposing the ribbed structure along the profile at least in portions, and at least in portions connecting the latter in a force-fitting, form-fitting and/or materially integral manner to the profile in order for the profile to be reinforced.

28. The method of claim 27, wherein a bonding agent is used, said bonding agent being applied to the first material prior to or after the production of the profile, wherein the bonding agent is provided on an internal side of the profile.

29. A motor vehicle comprising the bumper of claim 15.

30. The motor vehicle of claim 29, wherein the profile in the installed state is open in the travel direction.

Description

[0032] The invention will be explained in more detail hereunder by means of a drawing illustrating exemplary embodiments. The same parts are provided with the same reference signs. In the drawing:

[0033] FIG. 1: shows a first exemplary embodiment of a bumper according to the invention for a vehicle in a perspective view;

[0034] FIG. 2: shows a fragment from FIG. 1 of a region in plan view;

[0035] FIG. 3: shows an exemplary embodiment of a method according to the invention for producing a bumper according to a first variant, in a schematic sequence; and

[0036] FIG. 4: shows an exemplary embodiment of a first method according to the invention for producing a bumper according to a second variant, in a schematic sequence.

[0037] A first exemplary embodiment of a bumper (1) according to the invention is illustrated in a perspective view in FIG. 1. Said bumper (1) comprises a profile (2) from a first material, said profile (2) being an open deep-drawn profile, an open extruded profile, or preferably an open rolled profile from a metallic material. The cross section of the profile (2) at least in regions, preferably continuously, is configured so as to be W-shaped and in particular of consistent length. Other cross-sectional shapes are likewise conceivable. The metal material having a substantially consistent material thickness is preferably formed to a rolled profile by means of roll forming. The rolled profiles can be embodied straight or preferably bent, depending on requirements, wherein the bending can be performed inline in the roll forming station or in a separate device. The profile (2) is preferably composed of a steel material, in particular of a cold-formed steel having a moderate ductility, preferably having an elongation at break of A.sub.80>8%, particularly preferably A.sub.80>10%, so as to be able to absorb the impact energy that arises in particular in the event of a frontal collision by way of a sufficient plastic deformation. For example, the steel material, besides a moderate elongation at break, also has a moderate tensile strength of, for example, R.sub.m>700 MPa, in particular R.sub.m>800 MPa, preferably R.sub.m>900 MPa, wherein in the event of a collision the intrusion depth can be reduced as the tensile strength increases. The material thickness of the profile is, for example, between 0.5 and 3.0 mm, in particular between 0.7 and 2.5 mm, preferably between 0.8 and 2.0 mm, particularly preferably between 1.0 and 1.6 mm.

[0038] The open, bent rolled profile illustrated is composed of a steel of comparatively high strength, for example of a multi-phase steel having an elongation at break of A.sub.80>8% and a tensile strength of R.sub.m>800 MPa at a material thickness between 1.1 mm and 1.4 mm, preferably of a dual-phase steel having a material thickness of 1.2 mm.

[0039] Deformation elements (not illustrated) are linked in the linking regions (11, 11) on the left and right side of the profile (2), said deformation elements by way of a preferably releasable screw connection being capable of being linked to longitudinal beams (not illustrated) of a vehicle body. The openings (12, 12) in the profile (2) serve for plugging in screws (not illustrated) for releasably connecting the deformation elements to the profile (2). On account of the releasable connection the profile (2) can be replaced in an advantageously simple manner in the case of damage. Locally integrated reinforcements (13, 13) can be provided for reinforcing the linking regions (11, 11). In order for in particular the global rigidity of the profile (2) to be further increased, the edges/flanges (14) of the profile (2) can be canted or bent, respectively.

[0040] The bumper (1) according to the invention has at least one ribbed structure (3) formed from ribs (R) from a second material, said ribbed structure (3) being disposed along the profile (2) at least in regions and at least in regions being connected to the profile (2) in a force-fitting, form-fitting and/or materially integral manner, preferably being integrated in the profile (2), in order for the profile (2) to be reinforced. The ribbed structure (3) is formed from a fiber-reinforced plastics material and has at least one first region (4) and one second region (5, 5) which differ from one another in terms of at least one property. The ribbed structure (3) extends substantially completely along the profile (2), wherein the ribbed structure (3) in a first region (4) which is disposed in the central portion of the profile (2) has a higher strength than in a second region (5, 5) that is directly adjacent to the first region (4). On account thereof, a high resistance in relation to flexing and buckling can be advantageously achieved in the impact point in the center of the vehicle, in particular in combination with a profile (2) that is preferably open in the vehicle direction and is configured so as to be bent and symmetrical. The substantially complete extent along the profile (2) comprises at least in part the regions (7, 7) in which in each case at least one deformation element (crash box) is capable of being linked. The ribbed structure preferably extends even further and is completely present in the region (11, 11) for linking to the body. The ribbed structure (3) does not terminate flush with the ends of the profile (2), for example, but terminates at a predetermined spacing (a, a) from the ends of the profile (2) such that the end portions of the profile (2) remain free of the ribbed structure (3). The property profile of the ribbed structure (3) is distributed symmetrically along the profile (2) and per symmetry plane has at least three regions, preferably at least four regions (4, 5, 5, 6, 6, 7, 7) having in each case dissimilar properties. The provision of at least three regions having dissimilar properties takes into account the fact that in the event of a collision the forces acting thereon can have dissimilar effects in regions, and this can be counteracted in a targeted and flexible manner on account thereof, the bumper on account thereof being able to be conceived so as to be adjusted to the load. The fiber-reinforced plastics material is, for example, a thermoplastic plastics material, in particular a PA6 having a fiber proportion of, for example, 30% by volume, wherein glass fibers are used in particular. By virtue of the W-shaped cross section of the profile/rolled profile (2), the height of the ribs (R) that form the ribbed structure (3) varies in the transverse direction of the profile (2), wherein the height of the ribs (R) preferably corresponds to at most the depth (T) of the open profile (2). The dissimilar properties in terms of the occupancy rate, the orientation, and the thickness of the ribs (2) that form the ribbed structure (3) for the four regions (4, 5, 5, 6, 6, 7, 7) are listed.

TABLE-US-00001 Region Density Orientation Width (t) 4 50% diamond-shaped and 3.0 mm checkerboard-shaped 5, 5 25% diamond-shaped 3.5 mm 6, 6 10% star-shaped 1.5 mm 7, 7 25% diamond-shaped and 4.0 mm local thickening for a screw connection

[0041] The mechanical properties, in particular the rigidity and the strength and associated therewith the resilience of the bumper, can be influenced by way of the aforementioned properties, in each case individually or in combination, in a targeted manner in regions, in particular the intrusion depth in the event of a frontal collision by way of initiating/introducing in a targeted manner a plastic deformation in predefined regions of the profile (2) in order for the impact energy to be absorbed. A local increase of the rigidity on the bumper (1) can be additionally achieved in that if at least one region (9) in the ribbed structure (3) is foamed.

[0042] The chain dotted region (10) from FIG. 1 is illustrated in plan view in FIG. 2. The third region (6) which has a star-shaped orientation, a density of 10%, and a width (t) of the ribs (2) that form the ribbed structure (3) of 1.5 mm is shown. In order for the adhesion between the ribbed structure (3) and the profile (2) to be increased, a bonding agent is preferably provided on the internal side (8) of the profile (2).

[0043] A flow diagram of a first variant of a method according to the invention for producing a bumper (1) for a vehicle is illustrated in FIG. 3. Providing a profile (2) from a first material, in particular a deep-drawn profile or preferably a rolled profile from a metallic material which is open is performed according to step (A). Laying up the preferably open, metallic rolled profile (2) in an opened injection-molding tool is performed according to step (B). Closing the injection-molding tool and injection-molding a second material for generating at least one ribbed structure (3) formed from ribs (R) is performed in step (C), said ribbed structure being molded along the profile (2) at least in portions and at least in portions being connected to the profile (2) in a force-fitting, form-fitting and/or materially integral manner in order for the profile (2) to be reinforced. Curing the molded material is performed in step (D); subsequently opening the injection-molding tool and retrieving the reinforced profile (2) being performed in step (E). A fiber-reinforced plastics material, for example a thermoplastic injection-molding compound, preferably having loose short fibers and being provided with a fiber proportion between 10 and 50% by volume is used as a second material, and a ribbed structure (3) having at least one first region (4) and one second region (5, 5) which differ from one another in terms of at least one property is generated. Back-molded profiles (2) which are used as bumpers (1) and are conceived in a load-optimized manner can be economically produced at sufficiently high cycle rates in conventional injection-molding tools.

[0044] A flow diagram of a second variant of a method according to the invention for producing a bumper (1) for a vehicle is illustrated in FIG. 4. Providing a profile (2) from a first material, in particular a deep-drawn profile or preferably a rolled profile from a metallic material which is open is performed in step (A). Providing at least one ribbed structure (3) formed from ribs (R) from a second material, wherein the ribbed structure (3) is molded integrally or in multiple pieces from a fiber-reinforced plastics material and has at least one first region (4) and one second region (5, 5) which differ from one another in terms of at least one property, is performed in step (B). Disposing the ribbed structure along the profile (2) at least in regions and at least in regions connecting the latter to the profile (2) in a force-fitting, form-fitting and/or materially integral manner in order for the profile (2) to be reinforced is carried out in step (C). The prefabricated integral or multi-piece ribbed structure (3) is provided, for example, as a module, or as modules, respectively, which as a volume product can be economically produced, and the profile (2) can be conceived in a load-optimized manner.

[0045] The bumper (1) as a hybrid component having preferably a rolled profile from a high-strength, ductile steel material and having a ribbed structure formed from a fiber-reinforced plastics material, in particular from a PA6 reinforced with glass fibers imparts to the bumper (1) a high strength initially at the time of impact, said high strength in particular in the center of the vehicle (impact point) initially providing a high resistance in relation to flexing and buckling. The impact energy acting thereon leads to the maximum strength of the fiber-reinforced plastics material being exceeded, said fiber-reinforced plastics material by virtue of the relatively low elongation at break thereof failing, and the further energy as a result of the plastic deformation being able to be absorbed by the high-strength, ductile steel material in a targeted manner, in particular at low intrusion depths.

[0046] The invention is not limited to the exemplary embodiments described in conjunction with the drawing. Rather, mutual combinations are also possible within the scope of the invention. Additionally or alternatively, the bumper according to the invention can also be disposed or provided, respectively, in the rear-end structure of a vehicle so as to be able to set in a targeted manner an optimum in terms of the intrusion behavior in the direction of the passenger cabin also in the event of a rear impact.

LIST OF REFERENCE SIGNS

[0047] 1 Bumper [0048] 2 Profile [0049] 3 Ribbed structure [0050] 4 First region [0051] 5, 5 Second region [0052] 6, 6 Third region [0053] 7, 7 Fourth region [0054] 8 Internal side of the profile [0055] 9 Foamed region [0056] 10 Partial view [0057] 11, 11 Linking region [0058] 12, 12 Opening [0059] 13, 13 Locally integrated reinforcement [0060] 14 Edges/flanges [0061] A, B, C, D, E Process steps, process sequence [0062] A, B, C Process steps, process sequence [0063] R Rib(s) [0064] T Depth [0065] a, a Region without a ribbed structure, free region [0066] t Width of the rib