DE102015105625A1 - Bumper arrangement for a motor vehicle - Google Patents

Abstract

The present invention relates to a bumper assembly 1 for a motor vehicle comprising a cross member 2 and in the region of the ends of the cross member 2 arranged crash boxes 3 for coupling the bumper assembly 1 with the motor vehicle, wherein the cross member 2 is formed of a light metal alloy as a multi-chamber hollow profile, which is characterized in that the front cross-member 4 has a height in motor vehicle vertical direction Z which is greater than the height H14 of the rear side 14 and the multichamber hollow profile has at least two chambers, wherein a main chamber 21 has a larger cross-sectional area, compared to at least one front chamber 12, 17, preferably two front chambers 12, 17, and the front chambers 12, 17 with at least one wall 19, 20 forms part of the front side 4, preferably form the two front chambers 12, 17 each with at least one wall 19, 20, the front 4 with.

Description

The present invention relates to a bumper assembly for a motor vehicle according to the features in the preamble of claim 1.

From the prior art bumper assemblies are known, which are mounted on the front or rear side of a motor vehicle. The bumper assemblies have for this purpose a cross member, which extends substantially over at least part of the width of the motor vehicle body. The cross member should be as rigid as possible, so that the various impact scenarios, such as the impact of a pile, a Bumper to Bumper Crash or the impact on an obstacle and here in particular with coverage, which is also known as offset crash, are covered and a uncontrolled intrusion into the motor vehicle is prevented.

In order for the kinetic energy occurring in such a crash to be dissipated, such a known cross member is also coupled via crash boxes to the motor vehicle body and in particular to the longitudinal members. The crash boxes are designed in such a way that they are deformed by the impact and thus transform the kinetic energy by cold deformation in forming work. The crash boxes are usually coupled to the front side members of the vehicle body to initiate in this the further Crashenergie. The load path thus takes place from the cross member via the crash box into the longitudinal members of the motor vehicle.

A good crash performance is accompanied by a high stiffness of the cross member and a high energy absorption capacity of the crash box and the cross member, which is realized by a large dimensioning of the components. However, this large dimensioning of the components requires a high weight and a large amount of space.

The known bumper assemblies are thus in a conflict of interests of the lowest possible weight at the same time good crash performance and low space requirement.

From the EP 2 024 201 B1 a bumper assembly is known, which has a cross member having a high rigidity and small dimensions by different stiffening beads and steel component by using the hot forming and press-hardening technology. So that now also in the case of a bumper to bumper crash with another motor vehicle sufficient coverage is made possible, the cross member further comprises an asymmetric middle section to cover a center line of the cross member of an impacting motor vehicle sufficiently vertical. Here, however, the problem arises that in the event of an impact, a rotation takes place about the longitudinal axis of the cross member.

Furthermore, from the prior art cross member of light metal extrusions are known. For example, from the US 2015/0084355 A1 is a bumper assembly with a cross member known as a light metal extruded profile. Here, the overlap in the case of a Bumper to Bumper crash and the rigidity of the cross member is realized by a corresponding total height of the cross member relative to the motor vehicle vertical direction.

Object of the present invention is to show starting from the prior art, a bumper assembly which has a low space requirement with high crash performance and low weight.

The aforementioned object is achieved with a bumper assembly for a motor vehicle according to the features in claim 1.

Advantageous embodiments of the present invention are the subject of the dependent claims.

The bumper arrangement for a motor vehicle has a cross member and arranged in the region of the ends of the cross member crash boxes for coupling the bumper assembly with the motor vehicle, wherein the cross member is formed of a light metal alloy of an extruded multi-chamber hollow profile. The bumper assembly according to the invention is characterized in that the cross member has a front facing in the direction of travel and a rear facing away from the direction of travel, wherein the front in motor vehicle vertical direction has a height which is greater than the height of the back and the multi-chamber hollow profile at least two chambers, said a main chamber has a larger cross-sectional area with respect to the at least one front chamber and the front chamber with at least one of its walls forms the front with. Preferably, two front chambers are arranged, wherein both front chambers with at least one of its walls form the front with.

The bumper arrangement is suitable both for arrangement on the front side of the motor vehicle and on the rear side of the motor vehicle. The direction of travel is at the front then the forward direction of travel. When mounting the bumper assembly on the rear side, the direction of travel is the reverse direction.

According to the invention, it is possible by forming the cross member as a multi-chamber hollow profile of a light metal alloy, in particular of an aluminum alloy with a particularly low weight at the same time form high rigidity. For this purpose, different wall thicknesses are realized in particular in cross section. A good fulfillment of the requirements of various crash scenarios is achieved by the motor vehicle vertical direction relative to the height of the front of the cross member relative to the height of the rear side of the cross member. Preferably, the height of the back is 40% to 90% of the height of the front. In the region of the rear side of the cross member, motor vehicle peripheral components, for example a motor vehicle radiator, hoses, connecting hoses, lines or other components are often arranged, so that the smaller height leads to an installation space and at the same time during a deformation of the cross member, in particular as a result of a rotation about the longitudinal axis in vertically offset colliding cross beams due to the lower height of the back of the cross member, damage to adjacent components is avoided. Likewise, the penetration and associated damage of components in the engine compartment of the motor vehicle is avoided or reduced.

The increased crash performance with simultaneously lower dead weight is further achieved in that the cross member is designed as a multi-chamber hollow profile with at least one, preferably two directed in the direction of travel front chambers and one of these related to the direction downstream or downstream main chamber. The above-mentioned data relate in each case to the cross section of the cross member. The impacting obstacle thus initially hits the front chamber or front chambers. In the case of two front chambers, these may be arranged directly adjacent to one another in the motor vehicle vertical direction one above the other. However, the front chambers can also be arranged at a distance from one another, in which case the front chambers are connected to one another via a web. The related to the direction of travel front walls or wall surfaces of the front chambers then form at the same time at least a part of the front of the cross member. The remaining part is formed by the bridge. With only one front chamber, the rest of the front forms the bridge. In directly adjacent front chambers, these form the entire front of the cross member.

The cross-sectional area of the main chamber is greater than the cross-sectional area of the front chamber. With two front chambers, the cross-sectional area of the main chamber is larger than the respective cross-sectional area of a front chamber. The cross-sectional areas of the front chambers can be different or the same size from each other. However, the cross-sectional area of the main chamber is particularly preferably also greater than the cross-sectional area of the two front chambers together.

The web can be set back in cross-section relative to the vehicle longitudinal direction, so that the front of the cross member is not flat. Preferably, the web is arranged such that the front walls of the front chambers together with the web form the front and the front in cross-section is substantially flat is oriented to us in particular in automotive vertical direction.

To achieve the greater height of the front of the cross member relative to the rear, each with respect to the motor vehicle vertical direction, the front chambers above the main chamber are arranged above and below protruding, in particular with a stepped shoulder or step offset. This means that the upper side of the upper front chamber and the lower side of the lower front chamber are at a distance from one another which corresponds to the height of the front side and which is greater than the height of the rear side. Bends or rounding are excluded from this. The height of the back is also the height of the main chamber, as long as the main chamber has a rectangular cross-section. Thus, the main chamber is in each case with a step offset at the top over in the upper front chamber and at the bottom over in the lower front chamber.

For this purpose, the main chamber is formed in cross-section in particular by the back of an overhead upper chord and a lower chord underlying the corresponding parts of the front chambers and the optionally arranged on the front web. The back of the main chamber, which is also the back of the cross member and the web are oriented oriented in automotive vertical direction. The upper chord and the lower chord are oriented in the vehicle longitudinal direction, preferably oriented at an angle between -20 ° to + 20 ° to the vehicle longitudinal direction oriented. The parts of the front chambers, which form the main chambers are arranged correspondingly extending in motor vehicle vertical direction and in the vehicle longitudinal direction. The front chambers are further preferably formed in cross-section substantially rectangular. The main chamber preferably also has a rectangular, in particular square cross section, wherein due to the part of the main chamber, which is formed in cross section through the front chambers, the rectangular cross section is at least partially interrupted.

A particularly good force curve or load path results from the fact that the upper and lower chords of the main chamber merge into the rear side of the front chambers in each case in a median height range, also referred to below as the middle region. In particular, the upper flange and the lower flange are substantially orthogonal to the respective rear side of the front chambers, thus arranged in abutment with these. In this case, a high-intensity impact would lead to additional energy dissipation, in that the upper belt leads to a deformation of the rear side of the upper front chamber and the lower belt leads to the impressions of the rear side of the lower front chamber. This also converts kinetic energy into forming work and increases the crash performance. At the same time, the deformation increases the bending stiffness of the cross member itself, in which at least locally a longitudinal bead is formed in the rear wall of the front chamber.

Another essential aspect of the invention is that the cross member has a longitudinal course which is oriented in the vehicle transverse direction. Consequently, the longitudinal axis of the cross member is arranged oriented in the vehicle transverse direction. For this purpose, the cross member further preferably has a curvature over its longitudinal course, wherein the curvature is directed in the vehicle longitudinal direction. Thus, the cross member is formed slightly bent in the vehicle longitudinal direction towards the front.

Alternatively or additionally, the cross member has, relative to its longitudinal direction, a middle section which is bent or deformed asymmetrically in the motor vehicle vertical direction. In particular, the asymmetrical middle section is designed to be shaped upward in the vehicle vertical direction. The central portion may also be arranged offset parallel to the longitudinal axis of the cross member with respect to the motor vehicle vertical direction. This then results in a respective transition section. As a result, for the crash scenario Bumper to Bumper Crash, a good overlap is achieved for an impacting bumper, especially in the case of passenger cars, in particular in the middle class or in the case of small or micro cars. Their motor vehicle body and in particular the longitudinal members are often arranged lower in relation to the motor vehicle vertical direction than the centerline of luxury-class vehicles, SUVs or even commercial vehicles. By asymmetrically upwardly shaped middle section, in turn, a high coverage is realized with the aforementioned vehicles. Due to the design, in particular as a multi-chamber hollow profile, it is still possible to realize a sufficient bending stiffness of the cross member.

For this purpose, further preferably, the cross member is designed such that it has different wall thicknesses in cross section, wherein preferably the upper front chamber has a greater wall thickness relative to the lower front chamber. If a reverse arrangement is made, for example, of the bumper arrangement according to the invention on an SUV, the middle section would preferably be oriented downwards. In this case, the lower front chamber would have a higher wall thickness compared to the upper front chamber. Furthermore, particularly preferably, the wall thickness of the main chamber is greater than or equal to the wall thickness of the lower front chamber. In particular, the wall thickness of the main chamber is less than and particularly preferably smaller than the wall thickness of the upper front chamber. This makes it possible to achieve optimum crash performance with low material usage and thus possible low dead weight of the cross member, without reducing the crash performance of the bumper assembly, as a high bending stiffness of the cross member is realized.

Furthermore, particularly preferably, a respective front chamber has a height which corresponds to 20% to 60%, preferably 25% to 50%, in particular 30% to 40% and substantially 1/3 of the height of the main chamber. The height in turn refers to the automotive vertical direction. The front chambers can each have the same height. In the context of the invention, however, it is also possible that the front chambers have a different height from each other. Preferably, the upper front chamber has a greater height than the lower front chamber, in particular in an upwardly disposed central portion of the cross member.

Further particularly preferably, the rear side of the cross member merges into the upper flange and the lower flange in each case rounded. This makes it possible for a penetration of the cross member in the engine compartment or passenger compartment to keep the associated damage low. In the case of a slight torsion and / or rotation of the cross member about its longitudinal axis is damaged by the rounded transition region from back to top or back to bottom chord damage that could be caused for example by a 90 ° edge on a connecting hose or the like.

Furthermore, particularly preferably, the cross member is formed from an aluminum alloy, in particular from a 6000 or 7000 aluminum alloy. The cross member particularly preferably has a yield strength Rp 0.2 between 200 MPa and 500 MPa, more preferably between 300 MPa and 450 MPa. Particularly preferably, the material of the cross member is further increased by hot and / or cold aging.

The bumper assembly according to the invention further comprises a crash box. The crash box described below can be regarded independently within the scope of the invention with their respective features and associated properties without the cross member described above.

The crash box according to the invention itself is designed as a hollow profile, wherein the hollow profile has a rectangular configuration in cross section. The hollow profile may be formed in one piece and of the same material, but also in two parts or in several parts. The central longitudinal axis of the crash box extends oriented in the vehicle-mounted state in the vehicle longitudinal direction. A Crashboxoberseite and a Crashboxunterseite each have two curvatures, wherein the buckles are formed based on an interior of the hollow profile of the crash box outwardly oriented. The curves of the vaults are oriented in automotive vertical direction. Thus, the bulges of Crashboxoberseite are directed directed upward in automotive vertical direction and aligned the curvatures of the underside in automotive vertical direction oriented downwards. The curvature itself is formed over a longer course, in the manner of an outwardly oriented bead. This course itself is oriented in the vehicle longitudinal direction running. This course of the bulges thus increases the stiffness of the crash box and the energy absorption capacity in the vehicle longitudinal direction and even with a displaced as a result in motor vehicle vertical direction Bumper to Bumper crash constellations occurring rotational movement remains a connection of cross member to Crashbox guaranteed. Overall, more crash energy is reduced per way traveled the forming over the course of the crash box in the vehicle longitudinal direction.

Furthermore, particularly preferably, the crash box is fork-shaped towards the front and takes in the fork opening, the cross member at least partially in the vehicle longitudinal direction. For this purpose, the upper flange of the cross member of the Crashboxoberseite is at least partially, in particular completely overlapped and the lower flange of the Crashboxunterseite partially completely overlapped in particular. The cross member is further particularly preferred not only positively coupled in this area with the crash box. The coupling takes place in particular additionally by a riveting method or particularly preferably by a screw connection. This allows a simple and easy assembly and disassembly of the cross member and in particular pre-assembly of the entire bumper assembly, so that it can be completely assembled to the vehicle. Furthermore, particularly preferably, a spacer sleeve is arranged in the interior of the cross member, in particular in the main chamber, so that a screw connection of the crash box upper side of the cross member is formed by cross-Crashboxunterseite. Alternatively, a welding of the crash box on the top and bottom of the cross member, in particular on the upper flange and / or lower flange is possible.

The particularly good crash performance of the bumper assembly is further achieved in that the crash box is formed such that the Crashboxoberseite rests in particular with the front ends of the bulges on a rear wall of the upper front chamber of the cross member and the Crashboxunterseite in particular with the front ends of the bulges on a rear wall the lower front chamber is applied. An introduced to the front of the cross member crash is thus passed through the front chamber directly to the crash box or the vaults of the crash box. In the case of only a front chamber is formed on the cross member on the front chamber in the motor vehicle vertical direction opposite side of the web extended with a flange. The front end of the curvature of the crash box is then directly on the flange.

Furthermore, particularly preferably, the crash box has a laterally oriented in the vehicle transverse direction transverse flange, which rests against the rear wall of the cross member and in particular is coupled to the rear wall of the cross member. The coupling can in turn be produced by a riveting method and more preferably by a screw connection. Together with the coupling of Crashboxoberseite and Crashboxunterseite with the cross member thus takes place a three-sided coupling, which in particular prevents twisting or torsion of the cross member in the event of a crash.

Furthermore, in particular the crash box is in one piece and of uniform material, in particular made of a light metal alloy, preferably formed from an aluminum alloy. Thus, it is possible to produce the crash box in the extrusion process. To the crash box, a back plate or flange plate can be coupled, with which the crash box or the entire bumper assembly is then coupled to the vehicle body and in particular in the region of the front ends of the side members of the vehicle body.

In the case of the production of a one-piece and material-uniform crash box, it is possible to produce this as an extruded profile and then editing cutting technology and forming technology so that the Crashboxoberseite and the Crashboxunterseite and the laterally projecting flange are formed.

In particular, the crash box also has different wall thicknesses in cross-section in this case. Strips oriented in the vehicle longitudinal direction are preferably formed with greater wall thickness than the remaining regions of the crash box. The strips are very particularly preferably designed such that they extend from the flange plate of the crash box at least partially in the region of the bulges over the entire longitudinal course of the crash box, so that the area with greater wall thickness and thus higher rigidity of the flange of the crash box to the rear wall the front chamber of the cross member is formed, in particular in the region of the curvature.

As a result, it is again possible that the crash or impact introduced via the front chambers has an optimal load path through the crash box due to the strip with a higher wall thickness up to the flange plate and, as it were, a targeted deformation remains possible even in the case of an automotive vertical offset Bumper to Bumper crash constellations ,

Further advantages, features, characteristics and aspects of the present invention are the subject of the following description. Preferred embodiments are shown in the schematic figures. These serve for easier understanding of the invention. Show it:

1 the bumper assembly according to the invention in a perspective view,

2 the bumper assembly according to the invention in a plan view,

3 the bumper assembly according to the invention in a view from behind,

4 the cross member in a view from behind,

5 the bumper assembly in a side view,

6 the crash box according to the invention in perspective view,

7 the cross member according to the invention in a cross-sectional view,

8a to c the load path through a bumper assembly according to the invention and a known from the prior art bumper assembly,

9a to e cross-sectional views of different variants of the cross member and

10a to f a bumper assembly according to the invention before and after a crash with force level profile in contrast to a known from the prior art bumper assembly.

In the figures, the same reference numerals are used for the same or similar components, even if a repeated description is omitted for reasons of simplicity.

1 shows the bumper assembly according to the invention 1 in a perspective view. The bumper arrangement 1 has a cross member 2 on and in a respective end region of the cross member 2 arranged crash boxes 3 , The crossbeam 2 even has a flat front 4 and is designed as a multi-chamber hollow profile. The multi-chamber hollow profile is shown in detail and described in 7 , In the front are mounting holes 5 designed to a towing not shown the cross member 2 to arrange thoroughly. At the crash boxes 3 are flange plates 6 via which they can be coupled to the motor vehicle body, not shown, or to the longitudinal member of the motor vehicle body.

The crossbeam 2 is first produced as an extruded component and then further processed by forming technology and / or cutting technology. For this purpose is shown in particular according to 2 in the vehicle longitudinal direction X a curvature is formed. The curvature takes place in such a way that in the longitudinal direction 8th of the crossbeam 2 , where the longitudinal direction 8th in the vehicle transverse direction Y is oriented arcuately, so that the curvature arc is formed pointing in the vehicle longitudinal direction X. Thus, the cross member points 2 an arcuate course along its central longitudinal axis 7 on. Also clearly visible is that a respective Crashboxoberseite 9 a top strap 10 of the crossbeam 2 overlaps and thereby on a back wall 11 the upper front chamber 12 represented in 7 , comes to rest. Furthermore, the cross member 2 with the crash boxes 3 via a respective screw connection 13 between crash box top 9 and upper girth 10 coupled. Furthermore, screw connections 13 designed such that the back 14 of the crossbeam 2 with laterally projecting flanges 15 the crashbox 3 also coupled by screw technology.

Instead of the screw connections, it is also possible to weld the crash boxes and the cross member. For this purpose, preferably the Crashboxoberseite 9 and crashbox base 26 by welded joints with the upper flange 10 and the lower chord 22 coupled, in particular, alternatively or additionally, the front walls 28 the vaults 27 on the back walls 11 . 24 of the front chambers 12 . 17 of the crossbeam 2 be coupled.

3 shows a rear view of the bumper assembly according to the invention 1 and 4 a rear view only of the cross member 2 , Well recognizable is that a middle section 16 of the crossbeam 2 relative to the motor vehicle vertical direction Z directed upward parallel offset to the central longitudinal axis 7 is. Due to this upwardly offset middle section 16 In the case of a bumper to bumper crash, the highest possible overlap with respect to the motor vehicle vertical direction Z is achieved.

As 7 shows, in particular, the upper front chamber 12 a larger wall thickness W12, compared to a lower front chamber 17 with a smaller wall thickness W17 compared to the other. Between the upper and the lower front chamber 12 . 17 is one of these connecting footbridge 18 arranged. The front wall 19 the upper front chamber 12 as well as the front wall 20 the lower front chamber 17 and the jetty 18 together form the front side 4 of the crossbeam 2 out, which in plan, is flat. The jetty 18 itself has a wall thickness W18, the smaller equal to the wall thickness W12 of the upper front chamber 12 and greater than or equal to the wall thickness W17 of the lower front chamber 17 is trained.

The main chamber 21 itself forms the third chamber of the multi-chamber hollow profile, wherein all chambers have a substantially rectangular cross-sectional profile. The main chamber 21 itself is formed by the upper belt 10 , a bottom strap 22 as well as the back 14 , The backside 14 it always goes with a rounding 23 in the upper girth 10 or the lower chord 22 above. The upper strap 10 and the lower chord 22 as well as the back 14 each preferably have a wall thickness W10, W22, W14, which is less than or equal to the wall thickness W12 of the upper front chamber 12 and greater than or equal to the wall thickness W17 of the lower front chamber 17 is.

Also clearly visible is the height H14 of the back 14 smaller than the height H4 of the front 4 of the crossbeam 2 , This will be on the front 4 the largest possible impact surface provided for impact on a bumper, stake or other obstacle. Through the front chambers 12 . 17 a correspondingly high rigidity is ensured. The height H14 of the back 14 however, requires only a smaller space requirement and only a small risk of damage when penetrating the cross member 2 in the engine compartment.

Also clearly visible in 7 is that the upper strap 10 and the lower chord 22 each in the rear wall of the upper front chamber 12 as well as the back wall 24 the lower front chamber 17 go over, especially at a right angle. Preferably, the upper belt goes 10 or the lower chord 22 each in a central area 25 the back wall 11 in this over, so that there is an ideal load path, with simultaneous possibility of deformation of the multi-chamber hollow profile in itself. The height H12 of the upper front chamber 12 as well as the height H17 of the lower front chamber 17 can be the same but also different from each other. In the event that the middle section according to 3 is offset parallel to the motor vehicle vertical direction oriented upwards, preferably the height H12 of the upper front chamber 12 greater than the height H17 of the lower front chamber 17 , Preferably, the height corresponds to H12, H17 of the respective front chamber 12 . 17 20% to 60% of the height H21 of the main chamber 21 ,

Furthermore, the crash box according to the invention 3 clearly visible in the perspective view of 6 shown. Well visible here is the flange plate 6 , which at the back 14 the crashbox 3 is set and that the crashbox 3 itself is designed as a hollow component. According to their cross-sectional profile according to 6 is the crashbox 3 itself designed as a two-part component, the crash box 3 However, it can also be formed as a one-piece and material-uniform component, in particular as a single extruded component.

In particular, at the crash box top 9 as well as at the crash box bottom 26 buckles 27 formed, with the bulges 27 the crash box top 9 are formed oriented upwards in the motor vehicle vertical direction Z and the curvatures 27 at the crash box bottom 26 are oriented oriented towards the motor vehicle vertical direction Z pointing down. The respective vaults 27 extend over the respective length of the crash box 3 such that a leading edge or a forward end of each buckle 27 , by way of example only shown at the top right on the respective rear wall 24 the front chamber 17 of the crossbeam 2 comes form-fitting to the plant.

Furthermore, particularly preferred, the crash box 3 Wall thicknesses W27 differing from one another in cross-section, in particular in the end regions of the curvatures 27 strip 29 are formed, wherein the wall thickness W29 of the strips 29 larger than the remaining wall thickness W27, for example, the curvature 27 and / or at the Crashboxoberseite or Crashboxunterseite 26 , These stripes 29 then also extend over the entire length of the crash box 3 so these stripes 29 with increased wall thickness W29 and at the same time higher rigidity, from the flange plate 6 down to the back wall 24 the front chamber 17 extend. The Stripes 29 then each lie at right angles on the upper flange 10 or lower chord 22 of the main chamber 21 of the crossbeam 2 positive locking. Well shown this is in 5 ,

Also well recognizable is that the crash box top 9 and the crashbox base 26 are formed fork-shaped, that is a receiving area for the positive and in particular fork-shaped recording of the cross member 2 and here significantly the main chamber 21 yields, so that the upper chord 10 and the lower chord 22 the main chamber 21 be attacked as well as the crashbox 3 at the back 14 of the crossbeam 2 are formed coming to the plant.

In 8th are shown Bumper to Bumper crash scenarios, with an offset in motor vehicle vertical direction Z.

8a shows a load path 30 , In case of impact on an obstacle 31 is over the front 4 introduced the crash energy and in this case passes through the upper front chamber 12 over the upper belt 10 and the crashbox top 9 , the crashbox 3 and is in a the downstream side member 32 directed. In contrast, shows 8c a modified embodiment variant, wherein between the front wall 28 the crash box top 9 and the back wall 11 the upper front chamber 12 A gap 38 is trained. When hitting an obstacle 31 Thus, first the top chord 10 deformed before the front wall 28 on the back wall 11 the upper front chamber 12 incident. Only when the gap 38 has gone to zero, is also the back wall 11 the upper front chamber 12 due to the additional impact of Crashboxoberseite 9 noticeably deformed. In contrast, according to 8b represented a load path 30 according to the prior art, wherein here when hitting an obstacle 31 a known from the prior art cross member 33 the load path 30 also via a top strap shown there 10 is led, but then abruptly on a back wall 35 breaks off again in a side member 32 or this upstream crash box 37 to be guided.

9a to e each reveal cross-sectional views through various design variants of the cross member 2 , 9a shows the previously described embodiment variant with upper and lower front chamber 12 . 17 as well as the main chamber 21 and the connecting bridge 18 , According to 9b is the jetty 18 formed offset back from the front and connects the upper and lower front chamber 12 . 17 ,

In the embodiment variant according to 9c is on the lower front chamber 17 omitted, with an overhanging flange 34 is formed, which then the front 4 of the crossbeam 2 with trains. The flange 34 as well as the upper front chamber 12 will turn off the jetty 18 connected.

According to 9d an embodiment variant is shown in which the upper and the lower front chamber 12 . 17 immediately adjacent to each other are therefore immediately adjacent. These thus form without the bridge 18 the front 4 out. The main chamber 21 will then also from the upper belt 10 , the bottom flange 22 and the back 14 and parts of the respective backs of the front chambers 12 . 17 limited.

The 9e shows a modification to the representation 9a , In contrast to the embodiment variant according to 9a Here is the cross member 2 formed in cross-section such that the front 4 has a curved course. The arc of curvature shows it in the vehicle longitudinal direction X. Therefore, in the upper front chamber 12 , Based on the motor vehicle vertical direction Z, the upper wall in the vehicle longitudinal direction X formed shorter than the lower wall. At the lower front chamber 17 is based on the motor vehicle vertical direction Z, the upper wall formed longer than the lower wall, each in the vehicle longitudinal direction X.

10a to f show a comparison of a bumper assembly according to the invention 1 according to 10a to c, in contrast to a known from the prior art bumper assembly 1 represented in 10d to f, in each case simplified without crash box. For this purpose, the bumper assembly according to the invention is located 1 according to 10a in the initial state. According to 10b a force F hits the front 4 of the crossbeam 2 , As a result, the upper belt bulge 10 and the lower chord 22 referred to the motor vehicle vertical direction Z to the outside and thus reduce force F on the associated deformation path in the vehicle longitudinal direction X from. This corresponds to the force path diagram ➀ according to 10c , In particular, in a low intensity impact, this deformation occurs. At the same time upper belt are pressed 10 and bottom strap 22 the main chamber 21 in the backs 11 . 24 the two front chambers 12 . 17 and deform both the backsides 11 . 24 as well as the respective top and bottom of each front chamber 12 . 17 , In this case, there is a conversion of force F in forming work. In particular, this degrades the crash energy to be degraded in the event of a high-intensity impact. This corresponds to the force level ➁ in the force path diagram according to 10c , In 10c Then the acting force F and the associated deformation path in the vehicle longitudinal direction X is shown.

In contrast, the known from the prior art variant according to 10d to f only one known from the prior art Zweikammerhohlprofilquerträger 36 , Good to see here according to 10e and f, that only a force level ➀ of an impacting force F in the vehicle longitudinal direction X is realized. Overall, therefore, the force level ➀ according to 10f less than that in 10c , is therefore known in the prior art cross members 2 ensures a lower displacement.

LIST OF REFERENCE NUMBERS

1

bumper assembly

2

crossbeam

3

crash box

4

front

5

mounting hole

6

flange

7

Center longitudinal axis too 2

8th

Longitudinal direction too 2

9

Crashboxoberseite

10

 upper chord

11

Back wall too 12

12

 upper front chamber

13

 screw

14

Back to 2

15

Flange too 3

16

Middle section too 2

17

 lower front chamber

18

 web

19

front wall too 12

20

front wall too 17

21

 main chamber

22

 lower chord

23

 curve

24

Back wall too 17

25

Middle area too 11 respectively. 24

26

 Crashboxunterseite

27

 bulge

28

front wall too 27

29

 strip

30

 load path

31

 obstacle

32

 longitudinal beams

33

 crossbeam

34

 flange

35

 rear wall

36

 Two-chamber hollow profile cross member

37

 crash box

38

 gap

F

 force

H4

Height too 4

H12

Height too 10

H14

Height too 14

H17

Height too 17

H21

Height too 21

W10

Wall thickness too 10

W12

Wall thickness too 12

W14

Wall thickness too 14

W17

Wall thickness too 17

W18

Wall thickness too 18

W22

Wall thickness too 22

W26

Wall thickness too 26

W27

Wall thickness too 27

W29

Wall thickness too 29

X

 Motor vehicle longitudinal direction

Y

 Motor vehicle transverse direction

Z

 Automotive vertical direction

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• EP 2024201 B1 [0006]
• US 2015/0084355 A1 [0007]

Claims (17)

Bumper assembly ( 1 ) for a motor vehicle having a cross member ( 2 ) and in the area of the ends of the cross member ( 2 ) arranged crash boxes ( 3 ) for coupling the bumper assembly ( 1 ) with the motor vehicle, wherein the cross member ( 2 ) is formed from a light metal alloy as a multi-chamber hollow profile, characterized in that the cross member ( 2 ) a front facing in the direction of travel ( 4 ) and a rear facing away from the direction of travel ( 14 ), wherein the front side ( 4 ) in the automotive vertical direction (Z) has a height (H4) which is greater than the height (H14) of the rear side (Z) 14 ) and the multi-chamber hollow profile has at least two chambers, wherein a main chamber ( 21 ) has a larger cross-sectional area, compared to at least one front chamber ( 12 . 17 ), preferably two front chambers ( 12 . 17 ), and the front chamber ( 12 . 17 ) with at least one wall ( 19 . 20 ) a part of the front ( 4 ), preferably the two front chambers ( 12 . 17 ) each with at least one wall ( 19 . 20 ) the front ( 4 ) with. Bumper arrangement according to claim 1, characterized in that the front chambers ( 12 . 17 ) lie directly adjacent to each other or that the front chambers ( 12 . 17 ) are arranged at a distance to each other, wherein the front chambers via a web ( 18 ) are interconnected. Bumper arrangement according to claim 2, characterized in that the two front chambers ( 12 . 17 ) together with the bridge ( 18 ) the front ( 4 ), in particular a flat or a curved front side ( 4 ). Bumper arrangement according to one of the preceding claims, characterized in that the front chambers ( 12 . 17 ) in the automotive vertical direction (Z) based on the main chamber ( 21 ) protrude above and below, in particular with a stepped shoulder. Bumper arrangement according to one of the preceding claims, characterized in that the main chamber ( 21 ) in cross section through the back, a top chord ( 10 ) and a lower flange ( 22 ), Parts of the front chambers ( 12 . 17 ) and a footbridge ( 18 ) which extends to the front chamber is formed, wherein the back ( 14 ) and the jetty ( 18 ) oriented in the vertical direction of the motor vehicle (Z) and the upper belt ( 10 ) and the lower flange ( 22 ) in the vehicle longitudinal direction (X) oriented, in particular at an angle between -20 ° and + 20 ° to the vehicle longitudinal direction (X) are oriented. Bumper arrangement according to one of the preceding claims, characterized in that in cross-section the upper flange ( 10 ) and the lower flange ( 22 ) into a central area ( 25 ) on the respective back ( 24 ) of the front chambers ( 12 . 17 ) pass over. Bumper arrangement according to one of the preceding claims, characterized in that the cross member ( 2 ) has a longitudinal course which is oriented in the vehicle transverse direction (Y) and in that the transverse beam ( 2 ) has over its longitudinal course a curvature in the vehicle longitudinal direction (X) and / or that the cross member ( 2 ) is bent asymmetrically in a vertical section in the vehicle vertical direction (Z), in particular in the motor vehicle vertical direction (Z) upward. Bumper arrangement according to one of the preceding claims, characterized in that the cross member ( 2 ) have different wall thicknesses in cross-section, wherein preferably the upper front chamber ( 12 ) has a greater wall thickness (W12), compared to the lower front chamber ( 17 ). Bumper arrangement according to one of the preceding claims, characterized in that each front chamber ( 12 . 17 ) has a height (H12, H17) which is 20 to 60%, preferably 25 to 50% and in particular 30 to 40% of the height of the main chamber ( 21 ) corresponds. Bumper arrangement according to one of claims 5 to 9, characterized in that the rear side in the upper flange ( 10 ) and the lower chord ( 22 ) each rounded off. Bumper arrangement according to one of claims 5 to 10, characterized in that the cross member ( 2 ) is formed of an aluminum alloy, in particular of a 6000 or 7000 aluminum alloy, wherein the cross member ( 2 ) preferably has a yield strength RP 0.2 between 200 and 500 MPa, more preferably between 300 and 450 MPa. Bumper arrangement according to one of claims 5 to 11, characterized in that the crash box ( 3 ) is formed as a hollow profile, wherein a Crashboxoberseite ( 9 ) and a crashbox underside ( 26 ) each two vaults ( 27 ), wherein the vaults ( 27 ) in motor vehicle vertical direction (Z) extend and oriented in the vehicle longitudinal direction (Y). Bumper arrangement according to one of claims 5 to 12, characterized in that the upper flange ( 10 ) from the crash box top ( 9 ) and / or the lower chord ( 22 ) from the crash box bottom ( 26 ) is overlapped and in particular with the cross member ( 2 ), preferably preferably by means of rivets or a screw connection. Bumper arrangement according to the preceding claim, characterized in that the crash box upper side ( 9 ) on a rear wall of the upper front chamber ( 12 ) and the crashbox underside ( 26 ) on a rear wall of the lower front chamber ( 17 ) issue. Bumper arrangement according to one of claims 11 to 14, characterized in that the crash box ( 3 ) a laterally in the vehicle transverse direction (Y) oriented flange ( 15 ), wherein the flange ( 15 ) on the back wall ( 11 ) of the cross member ( 2 ) and in particular with the rear wall ( 11 ) of the cross member ( 2 ) is coupled, in particular by rivets or a screw connection. Bumper arrangement according to one of claims 11 to 15, characterized in that the crash box ( 3 ) in one piece and of the same material from a light metal alloy, in particular aluminum alloy is formed and in particular has different wall thicknesses in cross-section. Bumper arrangement according to claim 16, characterized in that the crash box ( 3 ) in the vehicle longitudinal direction (X) oriented running strips ( 29 ) with respect to the remaining areas of the crash box ( 3 ) of greater wall thickness (W29), the strips ( 29 ), in particular in the area of vaults ( 27 ) are arranged.

Images