Bumper crossmember assembly for a motor vehicle and method for manufacturing such a bumper crossmember assembly

Abstract

The invention relates to a bumper crossmember arrangement for a motor vehicle, comprising a bumper crossmember (10) which is composed of a plurality of shell elements (12, 14) and with respective brackets (22) via which the bumper crossmember (10) can be attached to respective associated longitudinal members (52), wherein the respective bracket is formed as part of the rear shell element (12, 14).

Description

[0001] The invention relates to a bumper cross member arrangement for a motor vehicle according to the preamble of claim 1 and to a method for producing such a bumper cross member arrangement according to the preamble of claim 9.

[0002] DE 10 2005 017 956 A1 discloses a device for absorbing impact energy, comprising a front part as the outer shell element and an inner shell. Plate elements are arranged between the inner shell and the longitudinal member, which are arranged as brackets that connect the inner part to a longitudinal member by screw connections.

[0003] DE 10 2017 127 610 A1 and DE 10 2017 123 325 A1 already disclose respective bumper cross member assemblies in which a bumper cross member is composed of a plurality of shell elements. Furthermore, the bumper cross member assembly comprises respective, separately formed lateral brackets, via which the bumper cross member can be attached to respective laterally assigned longitudinal members. This bumper cross member assembly is therefore composed of a large number of components and is therefore complex to manufacture.

[0004] Finally, DE 10 2014 011 790 A1, US 40 736 E and DE 10 2013 107 179 A1 disclose further noteworthy designs for shock absorbers in the state of the art.

[0005] Connecting the body via the brackets reduces the existing crash path and requires additional bolts for connecting the bumper cross member. This increases both the weight and cost of the overall system.

[0006] DE 10 2008 017 055 A1 discloses a bumper cross member comprising a bumper cross member made from an extruded profile. This bumper cross member can be attached to the respective side longitudinal members via separately formed lateral brackets.

[0007] Due to the extruded construction, the bumper cross member has the same cross-section across its entire width and therefore the same rigidity / crash performance. If the cross-section, rigidity, and crash performance are to be varied across the vehicle width, this can only be achieved via a downstream machining process. Here, too, the connection to the body via the brackets reduces the existing crash path, and additional bolts are required to create a connection between the brackets and the bumper cross member, which increases the weight and cost of the overall system. Adaptation to the outer skin in the vehicle's transverse direction can only be achieved via a bending process, whereby a correspondingly high clearance to the outer skin must be maintained due to the high tolerances in the bending process.

[0008] The object of the present invention is therefore to provide a bumper cross member arrangement and a method of the type mentioned at the outset, by means of which the usable crash path can be increased and by means of which the weight and the manufacturing and assembly costs can be reduced.

[0009] This object is achieved according to the invention by a bumper cross member arrangement and a method having the features of claims 1 and 9, respectively. Advantageous embodiments with expedient further developments of the invention are specified in the dependent claims.

[0010] The bumper cross member assembly according to the invention comprises a bumper cross member with at least two shell elements, namely a front and a rear shell element, which extend, for example, across at least approximately the entire vehicle width in the vehicle transverse direction and are assembled together. The two shell elements can be connected, for example, by joining, in particular welding or gluing, or alternatively or additionally by mechanical fasteners. Furthermore, the bumper cross member assembly comprises respective brackets formed as part of the rear shell element, via which the bumper cross member can be fastened to respective laterally assigned longitudinal members.

[0011] In order to create a bumper cross member arrangement that allows the usable crash path to be increased and the weight and manufacturing and assembly costs to be reduced, the invention provides for the front shell element and the rear shell element to be connected to one another via a joining process. Furthermore, the respective brackets are designed as crash boxes and comprise respective contact areas with outer sides through which the respective brackets are supported on the associated longitudinal member, and with inner sides on which a respective plate element is supported, which can be screwed to the associated longitudinal member.

[0012] Accordingly, the brackets of the rear shell element are provided with respective support areas, on the inside of which a respective plate element is supported, which can be screwed to the associated side member. This results in a simple, lightweight, and easily installed attachment of the bumper cross member assembly to the vehicle structure.

[0013] Accordingly, a bumper cross member with a multi-shell design is envisaged, with the shell elements being manufactured using suitable processes, such as deep drawing, roll forming (particularly of the front shell element), pressing, or injection molding. The brackets, which can also be designed as crash boxes, are integrated into the rear shell element according to the invention and thus also provide the connection and support of the bumper cross member assembly to the vehicle body shell or to the corresponding longitudinal members. The front and rear shell elements are connected to each other using a suitable joining process (adhesive bonding, riveting, spot welding, laser welding, or a suitable combination).The above-mentioned design of the consoles as respective crash boxes means that they are designed in such a way that in the event of a collision they can deform in a defined way to absorb crash energy, thereby reducing the forces acting on the vehicle's occupants.

[0014] In this case, the bumper cross member can be optimally adapted to the outer skin in all spatial directions. Due to the high dimensional accuracy during deep drawing / pressing / injection molding, less clearance is required for the outer skin compared to, for example, the bending process for a bumper cross member manufactured from an extruded profile, thus increasing the usable crash path.

[0015] Integrating the connection bracket into the rear shell element saves screws, weight, and assembly time (eliminating the need to mount the cross member to the brackets, which is required with the current technology). Eliminating the need for separate brackets also reduces costs (e.g., tooling costs). The multi-part design allows the best material to be used for each shell element. A pure aluminum support (weight) is just as conceivable as a pure steel support (cost). Mixed constructions of aluminum / steel or steel / aluminum are also conceivable. A mixed construction of plastic (e.g., organic sheet, injection molding) and metal is also conceivable. This design now allows the cross-section to be varied in the vehicle's transverse direction. Finally, the more direct connection of the bumper cross member to the vehicle structure also has a positive effect on body rigidity.

[0016] In a further embodiment of the invention, the respective console is created by primary forming or reshaping the rear shell element. As already explained above, the respective components, in particular the shell elements of the bumper cross member, are conceivable in all common metal and plastic materials, as well as in all mixed constructions.

[0017] It is also advantageous if the rear and front shell elements form a sheet metal shell profile, at least over a length of the bumper cross member, through which a hollow space is defined. This creates a particularly stable bumper cross member with high energy absorption capacity.

[0018] A further advantageous embodiment of the invention provides for an absorber element to be arranged in the cavity of the sheet metal shell profile formed by the rear and front shell elements. The crash absorber thus integrated between the two shell elements can be made of a foam material, but multi-shell sheet metal and extruded constructions (as a chamber profile, particularly with chambers running in the vehicle's longitudinal direction) are also conceivable. Such an absorber element allows the crash performance to be adapted to the requirements, particularly in the vehicle's longitudinal but also transverse direction. This design allows the use of a crash absorber made of PP (polypropylene) or PA (polyamide) foam.

[0019] In this context, it has proven further advantageous if one of the plate elements has a towing sleeve, which is accessible via an opening located in the front shell element. Attaching the towing sleeve to the vehicle body via the plate element provides a particularly convenient mounting position.

[0020] The advantages mentioned above in connection with the bumper cross member arrangement according to the invention apply equally to the method according to the invention.

[0021] Showing: Fig. 1 is an exploded perspective view and a perspective view of the bumper cross member assembly according to the invention according to a first embodiment; Fig. 2 shows a plan view, a side view and a rear view of, as well as two sectional views through, the bumper cross member arrangement according to the invention in accordance with the first embodiment; Fig. 3 is an exploded perspective view and a perspective view of the bumper cross member assembly according to the invention according to a second embodiment; Fig. 4 shows a plan view, a side view and a rear view of, as well as two sectional views through, the bumper cross member arrangement according to the invention according to the second embodiment; Fig. 5 is an exploded perspective view and a perspective view of the bumper cross member assembly according to the invention according to a third embodiment; Fig. 6 shows a plan view, a side view and a rear view of, as well as two sectional views through, the bumper cross member arrangement according to the invention according to the third embodiment; Fig. 7 a comparison of a bumper cross member arrangement according to the prior art above and a bumper cross member arrangement according to the invention below, each in a partial perspective view and a sectional view.

[0022] Fig. 1 shows in the upper figure in a perspective exploded view and the lower figure in a perspective view a first embodiment of the bumper cross member arrangement according to the invention.

[0023] The bumper cross member assembly comprises a bumper cross member 10, which is composed of a plurality of shell elements 12, 14, 16. According to the first exemplary embodiment, these shell elements 12, 14, 16 are a front shell element 12 and a rear shell element 14, each of which is formed as a sheet metal component and together forms a shell profile, by which, in the present case, a cavity 24 is delimited over the entire length in the transverse direction of the vehicle or in the direction of extension of the bumper cross member 10.The two shell elements 12, 14 are connected to one another by respective upper flanges 18 and lower flanges 20, which in this case extend over the entire length of the shell elements 12, 14, for example by a joining connection, in particular by welding, and more particularly by spot welding, or by gluing, or alternatively or additionally by mechanical connections. Of course, the shell elements 12, 14 can also be connected to one another in other ways.

[0024] Respective brackets 22, via which the bumper cross member 10 or the entire bumper cross member arrangement can be fastened at the end to respectively assigned longitudinal members of a bodyshell structure of the motor vehicle, are each formed as part of the rear shell element 14, in the present case introduced in particular by corresponding forming.

[0025] In the present case, it is a bumper cross member assembly at the rear end of a passenger car. The bumper cross member 10 is typically supported on the two longitudinal members via brackets 22. Typically, at least the bumper fascia of the vehicle at the front of the vehicle is held to the bumper cross member assembly. Components and other parts can also be held to the bumper cross member assembly. Likewise, it can also be attached to the front end of the motor vehicle, for example, as part of a front-end module, to which other components at the front of the vehicle, such as headlights or lighting units, vehicle radiators, or the like, can also be attached. In this case, the bumper cross member assembly is typically attached to the respective front longitudinal members of a main longitudinal member plane.

[0026] This bumper cross member assembly can also be used at the rear of the vehicle. Furthermore, the bumper cross member assembly can also be used in other vehicle shells, such as vans or trucks, for example, with a frame construction.

[0027] The shell element 16 is arranged as an absorber element in the cavity 24 of the sheet metal shell profile formed by the rear and front shell elements 12, 14. This absorber element 16 is also designed as a formed sheet metal part and comprises an upper and a lower flange 26, 28, which extends over the entire length of the absorber element 16. The absorber element 16 is designed to be at least substantially the same length as the shell elements 12, 14 and extends over the entire length of the bumper cross member 10 in the transverse direction of the vehicle. The absorber element 16 is fastened to the rear shell element 14 by means of the upper flange 26, which runs below the upper flanges 18, and the lower flange 28, which runs below the lower flanges 20, for example by joining, in particular by welding or gluing.

[0028] The brackets 22 of the rear shell element 14 have respective contact areas 30, with the outer sides of which the brackets 22 or the rear shell element are supported on respective flanges or the like of the respective laterally corresponding longitudinal member of the vehicle structure. A respective plate element 34 is supported on the inner sides 32 of the contact areas 30 of the brackets 22, which is screwed to the laterally associated longitudinal member—with the contact area 30 of the corresponding bracket 22 interposed. The corresponding screws 36, which here penetrate the plate element 34, the contact areas 30 of the brackets 22, and the flanges of the longitudinal members, are screwed in from the front.

[0029] Furthermore, it can be seen that one of the plate elements 34, in the present case the left plate element 34 viewed in the forward direction of travel, has a towing sleeve 38 which is accessible via an opening 40 cut out in the front shell element 12.

[0030] Fig. 2 shows the bumper cross member arrangement according to Fig. 1.

[0031] The top view particularly clearly shows the front shell element 12 of the bumper cross member 10, which can be easily adapted to the contours of the front end of the vehicle or the bumper fascia. Also clearly visible are the brackets 22 with their flat contact areas 30, by means of which the rear shell element 14 or the entire bumper cross member 10 can be supported and secured to the respective longitudinal members toward the center of the vehicle. The integral, one-piece design of the brackets 22 with the rear shell element 14 is also particularly evident.

[0032] From the rear view, in particular, respective through holes 42 in the flat contact areas 30 of the brackets 22 of the rear shell element 14 for the screws 36 for fastening the bumper cross member arrangement to the vehicle body shell are visible.

[0033] The two sectional views AA and BB show, according to the section lines shown in the rear view, respective sections along section planes in the vehicle vertical direction and in the vehicle longitudinal direction through the bumper cross member arrangement in the central area of ​​the towing sleeve 38 or the two inner screws 36 in the area of ​​one bracket 22.

[0034] In particular, it can be seen from the sectional views that the absorber element 16 is substantially U-shaped in cross-section and has respective legs 44 extending slightly obliquely outwards, which are integrally connected to one another via a front belt 46. In the present case, the belt rests, for example, on the inside of a front wall 48 of the front shell element 12, which is also substantially U-shaped in cross-section, and can optionally be connected to it, for example, joined. However, this is not absolutely necessary. The front belt 46 can also run at a distance from the front wall 48.

[0035] The sectional views also clearly show that the rear shell element 14, like the front shell element 12, is essentially U-shaped in cross-section. The flanges 18, 20 for connecting the two shell elements 12, 14 extend approximately halfway up the bumper cross member 10, relative to the vehicle's longitudinal direction.

[0036] Fig. 3 shows analogous to Fig. 1 shows a perspective exploded view and a perspective view of the bumper cross member assembly according to a second embodiment. Since this is essentially identical to the bumper cross member assembly according to the first embodiment, only the differences between the embodiments will be discussed below, and it will otherwise be assumed that the unmentioned features of the present embodiment are identical to the first embodiment. In this respect, identical reference numerals are used for the corresponding features.

[0037] In contrast to the first embodiment, the second embodiment provides an absorber element 16 which is designed as a chamber profile, in particular with chambers 49 running in the vehicle's longitudinal direction. In the present case, this chamber profile is designed, for example, as an extruded profile made of a metal or plastic alloy and is supported on the front wall 48 of the front shell element 12 and on a rear wall 50 of the rear shell element 14. In this case, it can be connected, in particular joined, to the shell elements 12, 14. Likewise, the absorber element 16 can also be shorter than the distance between the walls 48, 50. In the vehicle's transverse direction, the absorber element 16 extends over the entire length of the bumper cross member 10 in the vehicle's transverse direction.

[0038] Fig. Figure 4 shows a top view, a side view, and a rear view, as well as two sectional views through the bumper cross member assembly according to the second embodiment of the invention. It can be seen, in particular, from the two sectional views AA and BB that, in this case, one of the plate elements 34 also has the towing sleeve 38, which is accessible via an opening 40 recessed in the front shell element 12.

[0039] Fig. 5 shows analogous to the Fig. 1 and Fig. 3 shows a perspective exploded view and a perspective view of the bumper cross member assembly according to a third embodiment. Since this third embodiment is also essentially identical to the bumper cross member assembly according to the two previously described embodiments, only the differences between these embodiments will be discussed below, and it will otherwise be assumed that the unmentioned features of the present embodiment are identical to the first two embodiments. In this respect, identical reference numerals are used for the corresponding features.

[0040] In the present exemplary embodiment, an absorber element 16 is provided, which is formed as a plastic element, in particular from a plastic foam. The absorber element 16 is essentially trapezoidal in cross-section, tapering from the inside to the outside. In this case, the absorber element 16 is formed, for example, from a PP or PA foam and, for example, is prefabricated. During assembly, it is then inserted between the shell elements 12, 14 and, if necessary, connected to them, for example by gluing. Likewise, the absorber element 16 could also be formed by foaming into the cavity 24 of a foam material.

[0041] Fig. Figure 6 shows a top view, a side view, and a rear view, as well as two sectional views through the bumper cross member assembly according to the third embodiment of the invention. It can be seen, in particular, from the two sectional views AA and BB that, in this case, one of the plate elements 34 also has the towing sleeve 38, which is accessible via an opening 40 recessed in the front shell element 12.

[0042] Finally, Fig.7 shows a comparison of a bumper cross member assembly according to the prior art (above) and a bumper cross member assembly according to the invention (below), each in a partial perspective view and a sectional view. The sectional views show the respective attachment of the bumper cross member assembly according to the prior art (above) and the bumper cross member assembly according to the invention (below) to a respective rear longitudinal member 52 of a rear structure 54 of the motor vehicle arranged in front of it.

[0043] It is particularly evident here that the usable crash length I in the vehicle's longitudinal direction in the bumper according to the prior art is limited to the length of the cross-section of the bumper I due to the separately formed brackets of length k, whereas in the bumper cross member arrangement according to the invention, the usable crash length L in the vehicle's longitudinal direction comprises the length of the cross-section of the bumper 10 and the brackets 22. Thus, in the present example, the prior art assumes a length of the cross-section of the bumper I of, for example, approximately 109.5 mm and a length k of the brackets of approximately 37.5 mm, compared to a usable crash length L in the vehicle's longitudinal direction, which corresponds to the length of the cross-section of the bumper 10 and the brackets 22 - of approximately 147 mm. It is evident that in the present case, approximately 25% of additional usable crash length L in the vehicle's longitudinal direction can be gained.It is clear that these values ​​are only examples and, of course, the length of the cross-section of the bumper 10 and the brackets 22 can be chosen differently, both absolutely and in their relationship to each other.

Claims

[1] Bumper cross member arrangement for a motor vehicle, with a bumper cross member (10) which is composed of a front shell element (12) and a rear shell element (14), and with respective brackets (22) formed as part of the rear shell element (14), via which the bumper cross member (10) can be fastened to respectively associated longitudinal members (52), characterized by in that the front shell element (12) and the rear shell element (14) are connected to one another via a joining process and the respective consoles (22) are designed as crash boxes and comprise respective contact areas (30), with outer sides through which the respective consoles (22) are supported on the associated longitudinal member (52) and with inner sides (32) on which a respective plate element (34) is supported, which can be screwed to the associated longitudinal member (52). [2] Bumper cross member arrangement according to claim 1, characterized bythat the respective console (22) is produced by primary shaping or reshaping of the rear shell element (12, 14). [3] Bumper cross member arrangement according to claim 1 or 2, characterized by that the rear and the front shell element (12, 14) form a shell profile by which a cavity (24) is delimited at least over a length region of the bumper cross member (10). [4] Bumper cross member arrangement according to claim 3, characterized by that an absorber element (16) is arranged in the cavity (24) of the shell profile formed by the rear and front shell elements (12, 14). [5] Bumper cross member arrangement according to claim 4, characterized by that the absorber element (16) is designed as a chamber profile, in particular with chambers (49) running in the longitudinal direction of the vehicle. [6] Bumper cross member arrangement according to claim 4, characterized by that the absorber element (16) is designed as a shell element (12, 14). [7] Bumper cross member arrangement according to claim 4, characterized by that the absorber element (16) is designed as a plastic element, in particular from a plastic foam. [8] Bumper cross member arrangement according to one of the preceding claims, characterized by that one of the plate elements (34) has a towing sleeve (38) which is accessible via an opening (40) arranged in the front shell element (12, 14). [9] Method for producing a bumper cross member arrangement for a motor vehicle, which comprises a bumper cross member (10) which is composed of a front shell element (12) and a rear shell element (14), and wherein the rear shell element (14) comprises respective brackets (22) formed as part of the rear shell element (14), via which the bumper cross member (10) can be fastened to respectively associated longitudinal members (52), characterized bythat the front shell element (12) and the rear shell element (14) are connected to one another via a joining process and the respective consoles (22) are designed as crash boxes and are manufactured with respective contact areas (30) which comprise outer sides by means of which the consoles (22) are supported on the associated longitudinal member (52) and inner sides (32) on which a respective plate element (34) is supported, which is screwed to the associated longitudinal member (52).

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