Bumper for motor vehicle

Abstract

The invention relates to a bumper for a motor vehicle, comprising a cross-member (2) and two crash boxes (3). The cross-member has an upper leg (11) and a lower leg (12) which are connected by means of a web (10). The crash box has a coupling section (24, 25) on the cross-member side, which coupling section overlaps the upper leg or the lower leg and is integrally bonded thereto. According to the invention, the coupling section has a recess (27) which is open on the end face (26) thereof. At least one wall section (30, 31, 32) defining the gap is welded to the upper leg or the lower leg. An upper front connecting plate (14) pointing outwards is connected to the upper leg. An outwardly directed lower front web (15) is connected to the lower leg (12). A pressure groove (35), which is oriented in the vertical axis of the vehicle, is provided on the at least one front panel in a region in front of the crash box.

Description

Technical Field

[0001] The invention relates to a bumper for a motor vehicle according to the features of the preamble of claim 1 . Background Art

[0002] Bumpers are mounted on the front and rear sides of motor vehicles in order to intercept the collision energy of a collision process so that the load-bearing structure of the motor vehicle is not damaged as much as possible. In addition, the bumper should help to minimize personal injuries. The bumper has a crossbeam that can be fixed transversely to the longitudinal beams of the motor vehicle frame when deformation elements in the form of crash boxes are added. The crossbeam is used to introduce the energy caused by the collision into the crash boxes, where the collision energy is converted into deformation work. The arrangement of the bumpers is adapted to each other so that the crash boxes are mounted as centrally as possible on the longitudinal beams of the motor vehicle and the collision energy is introduced into the crash boxes and thus also into the longitudinal guides via the crossbeam with the smallest possible bending moment.

[0003] Bumpers must meet legal requirements and the requirements for pedestrian protection. Good crash performance and space-optimized and weight-optimized designs are requirements that must be consistent with the high demands on the safety structure of motor vehicles. Stringent safety requirements must be met, which are tested by crash tests, such as the so-called pole test (pole test) or the RCAR bumper test.

[0004] EP1928704B1 belongs to the prior art bumper, which has a cross member and two crash boxes. The cross member is shaped like a hat in cross section and includes a connecting plate and two legs. Each crash box has an upper coupling section and a lower coupling section on the cross member side. They overlap with the upper leg or the lower leg and are respectively connected thereto.

[0005] US2006 / 125354A1 discloses a bumper for a motor vehicle, which includes a crossbeam and a plurality of crash boxes, wherein the crossbeam has an upper leg and a lower leg, which are connected via a connecting plate. The crash box has a coupling section on the crossbeam side, which overlaps with the upper leg and the lower leg and is joined thereto. The coupling section has an open gap on its end side. At least one wall section defining the gap is welded to the upper leg or the lower leg.

[0006] A similar suggestion is made by US 2022 / 0001818 A1.

[0007] In the area of ​​the connection between the crash box and the cross member, a relatively deformable area is advantageous. Otherwise, cracks may develop, even to the point of breaking. The known solutions do not provide optimal preconditions here. Summary of the invention

[0008] Starting from this prior art, the invention is based on the object of providing a functionally improved bumper for a motor vehicle, which has advantageous load-bearing and deformation properties and is improved in particular with regard to the joint connection between the cross member and the crash box.

[0009] This object is achieved by a bumper according to claim 1 .

[0010] Advantageous embodiments and developments of the bumper according to the invention are the subject matter of the dependent claims.

[0011] Features of a motor vehicle bumper, whose embodiments and variants also emerge from the description and the drawings, constitute a functionally and technically advantageous bumper individually or in combination.

[0012] The directional information relates to the installation position of the bumper in the motor vehicle and to the vehicle coordinate system. The vehicle coordinate system is a three-dimensional Cartesian coordinate system in order to represent axes within the motor vehicle and axes of components of the motor vehicle. The x-axis and the y-axis are in a horizontal plane, i.e. the vehicle plane. The x-axis corresponds to the longitudinal axis of the vehicle, the y-axis to the transverse axis of the vehicle and the z-axis to the vertical axis of the vehicle.

[0013] A bumper for a motor vehicle has a cross member and a plurality of crash boxes. The cross member has an upper leg and a lower leg, which are connected via a web. The crash box has at least one coupling section on the cross member side, i.e., on its end facing the cross member. The coupling section overlaps with the upper leg or the lower leg and is joined to the upper leg or the lower leg in a material-locking manner.

[0014] The coupling section has a recess which is open at its end side. At least a wall section which defines the recess is welded to the upper leg or the lower leg.

[0015] This concept allows a joining that is advantageous in terms of production technology and a connection between the crash box and the cross member that is advantageous in terms of load-bearing and deformation properties. In the region of the connection of the crash box to the cross member, the crash box and the cross member deform during a crash. The cross member stretches ahead of the crash box without cracks developing.

[0016] The coupling section is preferably designed in a fork-shaped manner and has two teeth that laterally delimit the recess. The two teeth extend on the left and right side of the recess on the longitudinal axis of the vehicle (x axis). The teeth are welded to the legs of the cross member and stabilize and support the legs in the event of a crash.

[0017] The bumper according to the invention provides that the cross member has an outwardly directed upper front web connected to the upper leg and / or an outwardly directed lower front web connected to the lower leg, the coupling section being joined to the upper front web or the lower front web.

[0018] In particular, the crossbeam has an upper front connecting plate and a lower front connecting plate. In addition, the crash box has an upper coupling section and a lower coupling section. The upper coupling section overlaps with the upper leg of the crossbeam. The lower coupling section overlaps with the lower leg of the crossbeam. On the end side, the coupling sections or the teeth of a coupling section support the legs and optionally the upper front connecting plate or the lower front connecting plate.

[0019] In a practically advantageous embodiment, the upper coupling section and the lower coupling section can each be designed in a fork-shaped manner, comprising a recess and two teeth laterally delimiting the recess. The teeth extend in a straight line and on the upper leg or lower leg, respectively, to the upper front web or lower front web of the cross member.

[0020] Another embodiment provides that the upper coupling section has a recess which is open at the end. The lower coupling section has a shaped part which has lateral bevels and a bottom area in which a hole is arranged. The hole has a circumferentially closed edge. The hole in the lower coupling section is not open at the end. The lower coupling section is joined to the lower leg of the cross member by hole welding.

[0021] The cross member is designed as a closed hollow profile at least over the main part of its length. In particular, the cross member has a middle length section, which is followed on both sides by a connecting section for a crash box. At least in the middle length section and the connecting sections for the crash boxes, the cross member is designed as a hollow profile and has a closed interior.

[0022] The crossbeam may be an extruded profile comprising at least one cavity extending in its longitudinal direction.

[0023] A practically advantageous embodiment provides that the cross member has a sheet metal housing which is designed to be U-shaped or cap-shaped in cross section and has a terminating plate which is arranged on the front side of the sheet metal housing.

[0024] The cross-sectional profile of the hollow profile of the cross member is designed in a load-adapted manner over the component length due to the sheet-shell construction and advantageously has a greater depth in the middle length section than in the connecting sections and / or end sections. The cross member height, i.e. the width of the web and / or front web, can be varied and adapted to compatibility requirements and / or crash test requirements.

[0025] The sheet metal shell and the closing plate are made of steel. In particular with regard to crash performance, the sheet metal shell can be made of ultra-high-strength steel (UHSS) or can be a press-hardened steel component made of manganese-boron steel. The closing plate is preferably made of medium-strength or high-strength steel. The sheet metal shell has a tensile strength of more than 1250 MPa. The closing plate has a tensile strength of between 400 MPa and 1200 MPa. In the case of a hot-formed and press-hardened sheet metal shell, the tensile strength is greater than 1450 MPa.

[0026] A variant for improving the bumper according to the invention, in particular in terms of deformation behavior, provides that the upper front web and / or the lower front web have a groove oriented in the region in front of the crash box in the vertical axis (z axis) of the vehicle. The cross member is grooved in at least one front web, which can be integrated in a reasonable manner in production and imparts deformability to the cross member without making the inside of the crash box softer.

[0027] According to the invention, the embossing groove is arranged in front of the crash box in the region of the cross member. In particular, the embossing groove is arranged in front of the recess in the coupling section.

[0028] The embossed grooves in one or both front webs contribute effectively to improving the deformability of the bumper system. In particular for the load case "pile center impact", the deformation behavior of the bumper during an impact is improved. The crash boxes are stretched in the connection area in front of the crash boxes. The crash boxes are tilted inwards. Crack initiation and crack propagation are counteracted, in particular in or from the strongly deformed joint connection between the cross member and the crash box.

[0029] Preferably, the embossing groove is formed in the direction of the crash box. It is also advantageous if the embossing groove is offset laterally on the vehicle transverse axis (y-axis) relative to the central longitudinal axis of the crash box. In particular, the embossing groove is offset inwardly in the direction of the inner teeth of the coupling section.

[0030] Preferably, the embossing groove extends over the entire height of the front connecting plate. Here, the height of the front connecting plate is measured on the vehicle vertical axis (z axis). The embossing groove extends over the height of the front connecting plate and preferably transitions into the transition between the front connecting plate and the upper leg or the lower leg.

[0031] The embossed groove has a width, measured on the vehicle transverse axis (y-axis), which is less than 30 mm, in particular less than 20 mm.

[0032] The front closing plate extends in the longitudinal direction of the crossbeam. Here, the closing plate covers the embossed groove. The closing plate can extend linearly over the embossed groove. It is also possible that the closing plate has a shaped portion in the region of the embossed groove, which engages in the embossed groove in the front connecting plate.

[0033] The closing plate may have one or more embossed grooves. The embossed grooves may extend in the longitudinal direction of the closing plate or in the transverse direction of the closing plate.

[0034] It is also possible to provide, instead of or in addition to the embossed groove, locally fully cured or soft zones in the closing plate or in the cross member, in particular in the legs of the cross member or in a front connecting plate or in each front connecting plate, with the aim of setting the deformation and load-bearing properties of the bumper and in particular adapting them to compatibility requirements and / or crash test requirements. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] The present invention will be described in more detail below with the aid of the accompanying drawings. The accompanying drawings are as follows:

[0036] Figure 1 The bumper according to the invention is shown in a top view;

[0037] Figure 2 A detail of the bumper is shown in a perspective view of the connecting section of the crash box and the cross member;

[0038] Figure 3 Display in top view with Figure 2 The local part corresponding to the view;

[0039] Figure 4 a technically simplified vertical cross section through a crash box in the region of a recess in an upper coupling section of the crash box; and

[0040] Figure 5 A technically simplified vertical cross section through the crash box is also shown in the region of the depression in the upper front web. DETAILED DESCRIPTION

[0041] Figure 1 A bumper 1 according to the invention is shown. The bumper 1 is used in the front region or in the rear region of a body of a motor vehicle.

[0042] The bumper 1 has a cross member 2 which extends on the vehicle transverse axis (y axis) and can be fastened transversely to longitudinal members (not shown here) of the motor vehicle. The bumper 1 is supported on the longitudinal members by crash boxes 3 with the addition of a flange plate 4 on each side of the longitudinal members. The connection between the bumper 1 and the motor vehicle is established by the flange plates 4. The crash boxes 3 are intended to absorb the energy caused by a collision, especially at low speeds, as a supplement to the cross member 2, wherein the energy is converted into deformation work.

[0043] The cross member 2 has a central length section 5 , which is followed on both sides by a connecting section 6 for the crash box 3 and an end section 7 .

[0044] The cross member 2 has a plate housing 8 which is open at the front and is closed by a closing plate 9 which extends over the length of the plate housing 8. The plate housing 8 is designed in a U-shaped or cap-shaped manner in cross section and has a connecting plate 10 and an upper leg 11 and a lower leg 12 (see also Figures 2~5 ). The connecting plate 10 is arranged on the side of the bumper 1 facing the motor vehicle and connects the upper leg 11 and the lower leg 12. The upper leg 11 and the lower leg 12 each start from the connecting plate 10 and point forward in the longitudinal direction of the vehicle.

[0045] Due to the closing plate 9 , the cross member 2 is designed over its length L as a closed hollow profile 13 .

[0046] Adjacent to the upper leg 11 is an outwardly directed upper front web 14. Adjacent to the lower leg 12 is an outwardly directed lower front web 15. The upper front web 14 and the lower front web 15 are oriented on the vehicle vertical axis (z axis), the upper front web 14 pointing upwards from the upper leg 11 and the lower front web 15 pointing downwards from the lower leg 12. The closing plate 9 rests on the upper front web 14 and the lower front web 15 and is joined to them in a materially bonded manner.

[0047] The crash box 3 is composed of two sheet metal shell parts 16, 17 in a sheet metal shell construction. The sheet metal shell parts 16, 17 are adapted to each other in structure and preferably overlap each other at the end sides of their side walls 18. Here, the sheet metal shell parts 16, 17 are joined to each other in a material-locking manner. A vertical embossing groove 19 oriented in the vertical axis (z axis) of the vehicle is provided in each side wall 18 of the crash box 3. In addition, the crash box 3 has an upper wall 20 and a lower wall 21. In the upper wall 20 and also in the lower wall 21, an embossing groove 22 extending in the transverse direction of the vehicle (y axis) is embossed. The embossing groove 19 in each side wall 18 is formed outward from the interior of the crash box 3. The embossing groove 22 in the upper wall 20 and in the lower wall 21 is formed inwardly toward the interior of the crash box 3.

[0048] In the connecting section 6, the crash box 3 is connected to the cross member 2. On the cross member side, at the end 23 of the crash box pointing toward the cross member 2, the crash box 3 has coupling sections 24, 25 in the extension of the upper wall 20 or the lower wall 21, respectively. The upper coupling section 24 overlaps the upper leg 11 of the cross member 2. The lower coupling section 24 overlaps the lower leg 12 of the cross member 2. In each coupling section 24, 25, the crash box 3 is joined to the cross member 2 in a materially bonded manner. This is achieved using welding technology.

[0049] In the embodiment described, the upper coupling section 24 has a recess 27 which is open on its end face 26. The coupling section 24 is designed in a fork-shaped manner and has two teeth 28, 29 which laterally delimit the recess 27. The teeth 28, 29 extend in the extension of the upper wall 20 up to the upper front web 14 and support the upper leg 11 and the upper front web 14 in the event of a frontal impact. Thus, in the event of a frontal impact against an obstacle offset in height, even with a small vertical overlap, a good load introduction and a good force level are achieved for a targeted deformation of the crash box 3. The teeth 28, 29 are welded to the leg 11.

[0050] In one embodiment, the lower coupling section 25 is also fork-shaped and comprises a recess and two teeth which laterally delimit the recess and which, in this embodiment, support the lower leg 12 and the lower front web 15 .

[0051] The recess 27 is bounded by a wall section 29 oriented on the vehicle transverse axis (y-axis) and two wall sections 31, 32 oriented on the vehicle longitudinal axis (x-axis) to the left and right of the recess 27. The coupling section 24 is welded to the upper leg 11 at least on one wall section 30, 31, 32, in particular on all three wall sections 30, 31, 32. In addition, the coupling section 24 can be welded to the upper front web 14 on the end faces of the teeth 29, 29.

[0052] As especially Figure 4 and Figure 5 As shown, the upper wall 20 of the crash box 3 transitions into the upper coupling section 24 via a transition section 33 extending obliquely and converging in the direction of the central longitudinal axis ML of the crash box 3. The lower wall 21 of the crash box 3 also transitions into the lower coupling section 25 via a transition section 34 extending obliquely and converging in the direction of the central longitudinal axis ML of the crash box 3. The transition section 33 transitions into two rectilinear teeth 28, 29, as shown in FIG. Figure 2 and Figure 3 Visible in.

[0053] In the area in front of the crash box 3, the upper front slat 14 has a embossed groove 35. The embossed groove 35 is oriented on the vehicle vertical axis (z axis) and is arranged in the area in front of the recess 27. The embossed groove 35 is formed in the direction of the crash box 3. In particular, by means of Figure 3 It can be seen from the view that the embossing groove 35 is laterally offset relative to the central longitudinal axis ML of the crash box 3 on the vehicle transverse axis (y axis). The embossing groove 35 is laterally offset relative to the vehicle center in the direction of the teeth 28 facing inward.

[0054] The groove 35 extends over a height h of the upper front web 14, measured on the vehicle vertical axis (z axis), to a transition 36 between the upper front web 14 and the upper leg 11. The groove 35 has a width b measured on the vehicle transverse axis (y axis) that is less than 30 mm, in particular less than 20 mm.

[0055] The closing plate 9 extends on the front side along the plate housing 8 and in the process covers the embossing groove 35. The closing plate 9 can extend in a straight line on the front side. Figure 5 The view of shows this. However, the closing plate 9 can also have one or more embossed grooves, in particular the closing plate 9 can have an embossed groove-shaped shaped portion 37 which is arranged in the region of the embossed groove 35 in the upper front web 14 . Reference numerals list

[0056] 1 Bumper

[0057] 2 beams

[0058] 3. Collision energy absorption box

[0059] 4 Flange plate

[0060] 5 Intermediate length sections

[0061] 6 Connection section

[0062] 7 End section

[0063] 8-plate housing

[0064] 9 closed plate

[0065] 10 Connector board

[0066] 11 Legs

[0067] 12 legs

[0068] 13Hollow Profile

[0069] 14 Upper front connecting plate

[0070] 15 Lower front connecting plate

[0071] 16 Plate and shell parts

[0072] 17 Plate and shell parts

[0073] 18 side walls of plate shell members 16, 17

[0074] 19 groove

[0075] 20 Upper wall of collision energy absorption box 3

[0076] 21 The lower wall of the collision energy absorption box 3

[0077] 22 Press groove

[0078] 23 End of the collision energy absorption box 3

[0079] 24 coupling sections

[0080] 25 coupling section

[0081] 26 End side of coupling section 24

[0082] 27 Gap

[0083] 28 teeth

[0084] 29 teeth

[0085] 30 wall section of gap 27

[0086] 31 Wall section of gap 27

[0087] 32 wall section of gap 27

[0088] 33 Transition section

[0089] 34 Transition section

[0090] 35 groove

[0091] 36 Transition

[0092] 37 Forming Department

[0093] bWidth

[0094] hHeight

[0095] L length

[0096] ML center longitudinal axis

Claims

1. A bumper for a motor vehicle, comprising a cross member (2) and a plurality of crash boxes (3), the cross member (2) having an upper leg (11) and a lower leg (12), the upper leg and the lower leg being connected via a web (10), and the crash box (3) having a coupling section (24, 25) on the cross member side, the coupling section overlapping the upper leg (11) or the lower leg (12) and being joined to the upper leg or the lower leg in a materially bonded manner, the coupling section (24, 25) having a recess (27) open on its end side (26), and at least one wall section (30, 31, 32) defining the recess (27) being welded to the upper leg (11) or the lower leg (12), and the cross member (2) having an outwardly directed upper front web (14) connected to the upper leg (11) and / or an outwardly directed lower front web (15) connected to the lower leg (12), characterized in that The upper front connecting plate (14) and / or the lower front connecting plate (15) have a embossed groove (35) in the area in front of the crash box (3).

2. The bumper according to claim 1, characterized in that: The coupling section (24, 25) is fork-shaped and has two teeth (28, 29) which laterally delimit the recess (27).

3. The bumper according to claim 2, characterized in that: The coupling sections (24, 25) are joined to the upper front web (14) or the lower front web (15).

4. The bumper according to any one of claims 1 to 3, characterized in that: The cross member (2) is designed as a closed hollow profile (13) at least over a major part of its length (L).

5. The bumper according to any one of claims 1 to 4, characterized in that: The cross member (2) has a sheet metal housing (8) which is designed to be U-shaped or cap-shaped in cross section and has a closing plate (9) which is arranged on the front side of the sheet metal housing (8).

6. The bumper according to any one of claims 1 to 5, characterized in that: The depression (35) is oriented on the vehicle vertical axis (z-axis).

7. The bumper according to any one of claims 1 to 6, characterized in that: The pressing groove (35) is arranged in front of the gap (27).

8. The bumper according to any one of claims 1 to 7, characterized in that: The embossed groove (35) is formed in a direction toward the collision energy absorption box (3).

9. The bumper according to any one of claims 1 to 8, characterized in that: The embossed groove (35) is laterally offset relative to the central longitudinal axis (ML) of the crash box (3) on the vehicle transverse axis (y-axis).

10. The bumper according to any one of claims 1 to 9, characterized in that: The front connecting plate (14, 15) has a height (h) measured on the vertical axis (z axis) of the vehicle, and the depression (35) extends over the height (h).

11. The bumper according to any one of claims 1 to 10, characterized in that: The embossed groove (35) has a width (b) measured on the vehicle transverse axis (y-axis) which is smaller than 30 mm, in particular smaller than 20 mm.

12. The bumper according to any one of claims 5 to 11, characterized in that: The closing plate (9) covers the pressing groove (35).

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