DE102020209190A1 - Crash energy absorber for a motor vehicle - Google Patents

Abstract

In order to create a crash energy absorber (100) for a motor vehicle (200), it is proposed that only a single tubular element (10) be included, which has: a tubular axis (11), a tubular diameter (12) and a tubular wall (13 ), as well as a front end face (14) and a rear end face (15), the tube wall (13) having an axially running corrugation (20) with axially alternating elevations (21) and depressions (22), the corrugation (20 ) is formed correspondingly radially inside and outside of the pipe wall (13), and wherein the elevations (21) and depressions (22) are formed circumferentially like a thread with an axial pitch (23). Furthermore, a manufacturing method for such a crash energy absorber (100) by means of flow-forming or embossing is proposed.

Description

The invention relates to a crash energy absorber for a motor vehicle according to claim 1 and a manufacturing method for such a crash energy absorber according to claim 9.

The invention relates to a crash energy absorber for a motor vehicle, the crash energy absorber comprising only a single tubular element, and a manufacturing method for such a crash energy absorber.

The front impact beam and/or rear impact beam is designed differently for all vehicle manufacturers and offers many possibilities for optimization. There are many discussions and a wide variety of solutions for the design of these components. A so-called crash box used for this purpose is often made of two shells with beads to trigger wrinkles. An extruded profile is often used as a crash box in aluminium. In many cases, the energy absorption or the force level is uneven and fluctuates due to manufacturing tolerances. The weight of the front impact beams and/or rear impact beams has to be reduced further and further under the requirement of decreasing body weight, for example the desired lightweight construction from the point of view of consumption.

For example, from the DE 100 39 594 A1 a movable structure for a vehicle is known, in which the movable element 4 is formed entirely as a tube on which the thread 3 is presently provided as an external thread over its entire length or only a part of the tube. At the same time, the displacement element 4 also serves, at least in part, as a crash element. Furthermore, for example, from the U.S. 2004/0060790 A1 discloses a crush tube assembly 10 for absorbing impact energy in vehicle structures. According to paragraph [0029] therein, the crush tube assembly 10 comprises an outer tube 12, an inner tube 14, a core tube 16, a first coiled tube 18, a second coiled tube 20 and a sealing cap 22, the coiled tubes 18, 19 according to claim 1 9 are formed like a thread.

Compared to previously known crash energy absorbers, the invention is based on the object of achieving reliable energy absorption at a force level that does not decrease as far as possible with a low weight.

According to claim 1, only a single tube element is provided, which has: a tube axis, a tube diameter and a tube wall, as well as a front face and a rear face,
wherein the tube wall has a peripheral, axially running corrugation with axially alternating elevations and depressions, the corrugation being formed correspondingly radially on the inside and outside of the tube wall, and
the elevations and depressions being formed circumferentially in the manner of threads with an axial pitch.

1. i. Bereitstellen des Rohrelements;
2. ii. Drückwalzen oder Prägen der Wellung in die Rohrwandung des Rohrelements.

Furthermore, according to claim 7, a manufacturing method for such a crash energy absorber is proposed, which comprises at least the following steps:

1. i. providing the tubular member;
2. ii. Flow-forming or embossing of the corrugation into the tube wall of the tube element.

Advantageous developments of the invention are characterized in the dependent claims.

• eine Rohrachse, einen Rohrdurchmesser und eine Rohrwandung, sowie eine vordere Stirnseite und eine hintere Stirnseite,
• wobei die Rohrwandung umlaufend eine axial verlaufende Wellung mit axial abwechselnden Erhebungen und Vertiefungen aufweist, wobei die Wellung radial innen und außen der Rohrwandung korrespondierend gebildet ist, und
• wobei die Erhebungen und Vertiefungen umlaufend mit einer axialen Steigung gewindeartig gebildet sind.

According to a first embodiment of the invention, a crash energy absorber for a motor vehicle comprises only a single tubular element, which has:

• a tube axis, a tube diameter and a tube wall, as well as a front face and a rear face,
• wherein the tube wall has a peripheral, axially running corrugation with axially alternating elevations and depressions, the corrugation being formed correspondingly radially on the inside and outside of the tube wall, and
• wherein the elevations and depressions are circumferentially formed in a thread-like manner with an axial pitch.

The crash energy absorber proposed here is designed as a single tubular element, that is to say without further formwork, which would be set up, for example, to absorb radially acting forces resulting from a deformation. The corrugation is designed like a circumferentially stamped thread. Through the use of a circumferentially stamped round thread as a trigger mechanism for the buckling of the folds, which dissipates a great deal of energy, the tubular element falls under axial pressure load, preferably circumferentially, into a diamond deformation mode or, alternatively, forms annular folds. Such a diamond deformation mode is distinguished by the fact that a particularly uniform force-displacement curve is achieved during axial compression. The elevations and depressions alternate in the axial direction, the axial direction being defined by the geometric tube axis. If the tubular element is cut axially, the result is the corrugation with an axial course. If the tube element is rotated a little about the tube axis, the axial one shifts Position of the peaks and valleys compared to the previous angular position. This displacement corresponds to the thread-like pitch, ie a ratio of the change in angle to the axial displacement of the elevations and depressions.

The end faces are on the one hand the impact side in the case of a crash as designed, and on the other hand the fastening side to the rest of the body. The end face pointing outwards away from the body is referred to here as the front end face, even if, when used in a motor vehicle, it only points forwards at the front in relation to a main direction of travel when driving forwards, but backwards at the rear and to the right or the rocker panel points to the left. The end face on the body is correspondingly referred to here as the rear end face.

The corrugation is radially inside and radially outside corresponding in that the corrugation due to the manufacturing process, for example flow-forming or embossing, is mapped accordingly in a one-sided tool, for example, due to the material behavior and the wall thickness of the pipe wall. In the case of a two-sided embossing tool, the two antagonists of the embossing tool are designed to correspond, as is the case with flow-forming, the flow-forming mandrel and the forming rollers. In other manufacturing methods, the radially inner shape is formed separately from the radially outer shape, for example, but corresponds to one another, as explained in connection with embossing.

In an advantageous embodiment of the crash energy absorber, the corrugation is formed starting directly at the front face.

In an advantageous embodiment of the crash energy absorber, the corrugation ends in front of the rear face.

In an advantageous embodiment of the crash energy absorber, the amplitude of the corrugation decreases from the front face to the rear face.

In an advantageous embodiment of the crash energy absorber, the corrugation is formed by means of flow-forming or embossing in the previously axially flat pipe wall.

In an advantageous embodiment of the crash energy absorber, a trigger is formed by means of a locally increased amplitude.

In an advantageous embodiment of the crash energy absorber, the tube element is manufactured as a continuously drawn or welded tube.

• - eine Karosserie;
• - eine Mehrzahl von Rädern, welche in der Karosserie aufgehängt sind;
• - zumindest eine Knautschzone, umfassend einen Stoßfänger und/oder einen Schweller;

wobei die Knautschzone zumindest einen Crash-Energieabsorber nach einer Ausführungsform gemäß der obigen Beschreibung umfasst, wobei die Rohrachse in Richtung eines auslegungsgemäßen jeweiligen Haupteinschlags mit der vorderen Stirnseite von der Karosserie weg nach außen weisend ausgerichtet ist.According to a further aspect, a motor vehicle is proposed which has at least the following components:

• - a body;
• - a plurality of wheels suspended in the body;
• - At least one crumple zone comprising a bumper and/or a rocker;

wherein the crumple zone comprises at least one crash energy absorber according to an embodiment as described above, wherein the tube axis is oriented in the direction of a designed respective main impact with the front face facing outwards away from the body.

1. i. Bereitstellen des Rohrelements;
2. ii. Drückwalzen oder Prägen von der Wellung in die Rohrwandung des Rohrelements.

According to a further aspect, a manufacturing method for a crash energy absorber according to an embodiment according to the above description is proposed, having at least the following steps:

1. i. providing the tubular member;
2. ii. Flow-forming or embossing of the corrugation into the tube wall of the tube element.

In an advantageous embodiment of the manufacturing method, the tubular element is in step i. provided with the tube wall in a undulation-free condition.

• 1 in einer perspektivischen Ansicht ein Crash-Energieabsorber,
• 2 in einer perspektivischen Ansicht einen Crash-Energieabsorber mit abnehmender Amplitude,
• 3 in perspektivischer Ansicht eine Drückwalz-Vorrichtung,
• 4 in einer schematischen Ansicht ein Ausschnitt eines Crash-Energieabsorbers mit Trigger,
• 5 ein Diagramm mit Kraft-Zeit-Verläufen für einen Crash-Energieabsorber, und
• 6 in einer schematischen Draufsicht ein Kraftfahrzeug mit Crash-Energieabsorbern.

Exemplary embodiments of the invention are explained in more detail below with reference to the drawing. Show it

• 1 a perspective view of a crash energy absorber,
• 2 a perspective view of a crash energy absorber with decreasing amplitude,
• 3 a perspective view of a flow-forming device,
• 4 in a schematic view a section of a crash energy absorber with trigger,
• 5 a diagram with force-time curves for a crash energy absorber, and
• 6 in a schematic top view, a motor vehicle with crash energy absorbers.

1 shows a tube element 10 with a tube axis 11, a tube diameter 12 and a pipe wall 13, and a front end face 14 and a rear end face 15, the tubular element 10 being used as a crash energy absorber 100 for a motor vehicle 200. It is thus possible to construct a crash energy absorber 100 that folds lighter than previously known solutions and is nevertheless robust with high energy absorption, with the crash energy absorber 100 having only the tubular element 10 as the compressing, ie energy-absorbing element. The x-axis (x) is coaxial with the tube axis 11, the z-axis (z) is in the radial direction, and perpendicular to the z-axis (z), the y-axis (y) is in the transverse direction. For example, here the tube element 10 is manufactured as a continuously drawn tube or as a tube composed of several sections with a corresponding number of circumferential seams or welded from one or more bent metal sheets with a corresponding number of longitudinal seams. For orientation, it should be mentioned that the front end face 14 is shown facing away from the viewer in the perspective view in the image and the rear end face 15 is accordingly facing. Here, the tube wall 13 has an axially running corrugation 20 with axially alternating elevations 21 and depressions 22 all around. The corrugation 20 is formed radially on the inside and outside of the pipe wall 13 to correspond, with the elevations 21 and depressions 22 being formed circumferentially with an axial pitch 23 like a thread. In the specific embodiment, the corrugation 20 extends with a constant amplitude 24 starting immediately at the front end face 14 and ending at the rear end face 15 . The corrugation 20 is formed to correspond radially on the inside and radially on the outside in such a way that an (almost) constant wall thickness 25 is formed. This can be produced inexpensively, for example by means of the production process of flow-forming or embossing.

2 10 shows a tubular element 10 that is largely the same as that in FIG 1 , which can be used as a crash energy absorber 100 for a motor vehicle 200. The view orientation is the same as that of 1 . Here the corrugation 20 is also formed starting immediately at the front face 14, whereas in this embodiment the amplitude 24 of the corrugation 20 is formed decreasing, namely here due to the decreasing depression 22 towards the rear face 15. The corrugation 20 is thus in rear quarter of the crash energy absorber 100, and the tube member 10 has an end portion at the rear end face 15 in which no corrugation 20 is provided. It should be pointed out at this point that in this special embodiment, due to a constant slope 23 of the elevations 21 and depressions 22 of the constant, outer or corrugation-free pipe diameter 12, i.e. with the elevations 21 not protruding radially beyond the designated pipe diameter 12, the axial Extension of the elevations 21 from the front face 14 towards the rear face 15 increasing and the axial extent of the depressions 22 from the front face 14 towards the rear face 15 is formed decreasing. In an embodiment not shown here, with a constant pitch 23 and a constant tube diameter 12 , the axial extent of the depressions 22 is formed increasing or constant from the front face 14 to the rear face 15 .

For example, a thread shape, a thread depth, ie amplitude 24 of the corrugation 20, a pitch 23, a thread length and/or areas with increasing or decreasing thread depth are expertly adapted to a design load case. Other parameters that can be adjusted by an expert are a pipe material quality, a wall thickness 25 and a pipe diameter 12. A thread form is, for example, a round thread or a trapezoidal thread.

Unlike in the illustrated embodiment, for example, the corrugation 20 is formed as follows: extending at an axial distance from the front face 14, with increasing and/or variable amplitude 24 from the front face 14 to the rear face 15, with decreasing and/or variable pitch 23 over the axial extent of the corrugation 20 and/or with an area without corrugation 20 over the axial extent of the tubular element 10, and with a variable pipe diameter 12 and/or variable wall thickness 25. On the front face 14 and/or on the rear end face 15 of crash energy absorber 100, corrugation 20 begins, for example, either directly with full amplitude 24 or begins running in, for example steadily increasing, with depression 21 preferably being progressively formed and all elevations 21 being arranged in a smooth envelope of tubular element 10. As the corrugation 20 arrives, the amplitude 24 of the corrugation 20 gradually increases or decreases. On the tubular element 10, for example, axial or peripheral areas are provided completely without corrugation 20, for example, to facilitate the connection to other components. The amplitude 24 of the corrugation 20 is also formed increasing and then decreasing again in the axially central region of the tubular element 10, for example. In one embodiment, a trigger mechanism is thus formed in order to be able to determine the position of the first fold of the fold buckling. Compare the following explanations to the in 4 shown trigger 26. In one embodiment, at least one embossing is on the profile edges and / or the profile side surfaces of the corrugation 20 or other areas of the Tubular element 10 is provided. Furthermore, at least one cutout, such as a hole, is additionally, preferably alternatively, provided in order to form a trigger. Such a trigger is therefore a local weakening and therefore induces the location of the first plastic deformation in the case of a professional design. In the case of a pipe element 10 with a thread-like corrugation 20, a circumferential weakening is introduced over the (entire) length of the corrugation, for example over the entire length of the pipe. An additional trigger 26 is therefore advantageously introduced for a defined starting point. For example, the circumferential depression 22 is applied to a greater extent for this purpose in a specific area than in the rest of the corrugation 20. The trigger 26 is preferably introduced on one side of the profile and for preferably a complete circumnavigation, ie over 360°. In terms of manufacturing technology, this can be easily integrated into cost-effective shaping processes.

3 shows a flow-forming device 300, by means of which a tubular element 10 shown as an example for a crash energy absorber 100 can be manufactured in a highly automated manner. A flow-forming mandrel 50 mounted centrally on an axis of rotation S, for example congruently with the pipe axis 11, is fitted with a piece of pipe 52, for example smooth or corrugated, and clamped. The piece of pipe 52 is accommodated on the contoured flow-forming mandrel 50 with little play. The piece of pipe 52 is fixed on the flow-forming mandrel 50 by means of a pressure disk 53, which is guided in the clamping direction I, and is set in rotary motion about the axis of rotation S. The pipe is carried along by frictional locking. The thread-like corrugation 20 is formed by rotating the flow-forming mandrel 50 and the rolling force R of a plurality of forming rollers 51 acting from the outside, which are also referred to as flow-forming rollers. The shaping rollers 51 act locally on the circumference of the tube piece 52 from the radially outside. As a result of the direct pressure of the rollers, the wall of the tube is plastically deformed. The defined axial movement of the forming rollers 51 imprints the desired contour, namely the corrugation 20 , of the flow-forming mandrel 50 into the tube wall 13 . The inner contour of the flow-forming mandrel 50 is thus molded directly onto the piece of pipe 52 . After the thread-like corrugation 20 has been completely formed, the pipe element 10 is removed by screwing it down from the flow-forming mandrel 50. The pipe section 52 is removed from the flow-forming mandrel 50 after the pressure disk 53 has been removed with a screwing rotary motion. If the deepest contour, ie the largest recess 22 is in the axial center of the tubular element 10, the flow-forming mandrel 50 is preferably divided axially. This makes it easy to remove the tubular element 10 .

Possible forms of the thread-like corrugation 20 in the application area for a motor vehicle 200 are a thread pitch of 10 mm to 70 mm, a thread depth of 2 mm to about 20 mm, rounding radii within the thread geometry of at least twice the sheet thickness, i.e. the wall thickness 25. The thread geometry is, for example, a trapezoid, a sine curve or a parabolic shape. In addition, the axial extent of the elevations 21 and depressions 22 have different widths, for example. In one embodiment, a reduction in the thread depth, ie the amplitude 24, is provided in the axial direction, which is preferably formed continuously.

4 shows a schematic view of a section of a tubular element 10 with the tubular axis 11 for a crash energy absorber 100 with a trigger 26. In the figure, elevations 21 and depressions 22 can be seen on the left and right, which run around like a thread and are therefore axial to one another on the left and right are offset, such as in 1 and 2 shown. In this representation, the amplitude 24 is constant for the sake of clarity without restricting the generality over the axial section shown. Only the trigger 26 is designed with a greater indentation 22 , ie an increased amplitude 24 . This ensures that the plastic deformation of the tubular element 10 in the event of a crash occurs first at precisely this point, precisely at the trigger 26 .

5 shows a graphic representation of force-time curves for a crash energy absorber 100 according to FIG 1 in a chart. The time in milliseconds is plotted on the abscissa A, for example each vertical line corresponds to five milliseconds. The force in kilonewtons is plotted on the ordinate O, for example each horizontal line corresponds to twenty kilonewtons. The solid curve a shows the force-time curve under an exactly axial impact, i.e. along the ideal direction F of the main impact. The dashed curve b shows the force-time profile at an angle of 10° to the exact axial orientation of the inclined impact. Immediately after an impact, both curves a, b initially rise steeply, with the 10° curve b rising less steeply than the 0° curve a, the maximum being significantly lower and the 10° curve b accelerating earlier specific strength level levels off. It should be noted that the force level of both curves a, b remains constant over a very long period of time, namely in a force-constant area C, and that the force level of both curves a, b is almost identical before the force level for both impact angles drops almost simultaneously. For example, effective crash energy absorption is over 45 ms at a force level over a period of about 40 ms is about 70 kN. Under certain circumstances, a different force-time curve is desired. The corrugation 20 is then to be adjusted accordingly, including the parameters affected by it, as excerpts of which are mentioned above.

The fact that the force level is almost constant over a long period of time follows from the circumferential diamond deformation mode, in which the tubular element 10, if it is circular, assumes a diamond shape radially inside and outside, buckling at the depressions 22 in an axial plan view. A more uniform force-displacement characteristic is thus created as a result of the continuous formation of folds during axial compression of the tubular element 10 . Such a crash energy absorber 100 in a motor vehicle 200 can therefore be made shorter than previously known embodiments and vehicle overhangs can be reduced. This results from increased material utilization for increased crash energy absorption or a lighter construction with the same crash energy absorption.

6 shows a motor vehicle 200 with a plurality of crash energy absorbers 100, for example as in FIG 1 or 2 shown. For orientation it should be mentioned that the front 32 of the motor vehicle 200 is arranged on the left in the image and the rear 33 and the driver's cab 34 are arranged between the front 32 and the rear 33 on the right in the image. The main direction of travel is thus defined from right to left. The motor vehicle 200 includes a body 30, indicated only by dashed lines, in which the driver's cab 34 is accommodated, and wheels 31 for mobile locomotion of the motor vehicle 200. To protect the body 30 from damage or for the first crash energy absorption to protect the occupants in a severe crash, a plurality of crumple zones 40 is provided. For the particularly endangered frontal and rear-side main impacts, a crumple zone 40 is provided here in the front 32 and in the rear 33, which has a bumper 41 and a plurality of crash energy absorbers 100, here two arranged in parallel, for example as in 1 or 2 shown. The respective tubular axis 11 of the crash energy absorber 100 is aligned in the designed direction F of the main impact with the front face 14 pointing outwards away from the body 30, i.e. pointing to the left in the front 32 according to the illustration and to the right in the rear 33 according to the illustration pointing. Two lateral crumple zones 40 are also shown here, which are arranged above and below the driver's cab 34 according to the illustration. In the embodiment shown, these lateral crumple zones 40 only include a conventionally suspended rocker panel 42. However, it is particularly preferred to have at least one, preferably a plurality of, crash energy absorbers 100 between the body 30 and the rocker panel 42 or in the respective rocker panel 42 of the motor vehicle 200 arranged, for example to replace a conventional steel profile or aluminum profile. In particular, this can be implemented in a space-efficient manner with a crash energy absorber 100 that is designed to be significantly shorter than in previously known embodiments in this area of the motor vehicle 200 that is critical in terms of installation space.

• - im Boden von gepanzerten Fahrzeugen, beispielsweise zum Schutz der Insassen vor Sprengladungen und ähnlichem, sowie
• - im Fahrwerk beziehungsweise in den Kufen von einem Luftfahrtzeug, wie beispielsweise einem Flugzeug oder Hubschrauber, zum Schutz des Luftfahrtzeugs und/oder der Insassen bei einer zu harten Landung.

Other possible applications for this crash energy absorber 100 are:

• - in the bottom of armored vehicles, for example to protect the occupants from explosive charges and the like, as well as
• - In the landing gear or in the skids of an aircraft, such as an airplane or helicopter, to protect the aircraft and / or the occupants in a hard landing.

Reference List

100

Crash energy absorber

200

motor vehicle

300

flow-forming device

10

tube element

11

pipe axis

12

pipe diameter

13

pipe wall

14

front face

15

rear face

20

curl

21

elevation

22

deepening

23

pitch

24

amplitude

25

Wall thickness

26

triggers

30

body

31

wheel

32

front

33

Rear

34

driver's cabin

40

crumple zone

41

bumper

42

sills

50

spinning mandrel

51

form roll

52

piece of pipe

53

pressure disc

S

axis of rotation

R

rolling force

I

clamping direction

f

direction of the main impact

A

abscissa

O

ordinate

C

force constant area

a

first curve

b

second curve

x

X axis

y

y-axis

e.g

z-axis

QUOTES INCLUDED IN DESCRIPTION

This list of the documents cited by the applicant was 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.

Patent Literature Cited

• DE 10039594 A1 [0004]
• US 2004/0060790 A1 [0004]

Claims (10)

Crash energy absorber (100) for a motor vehicle (200), exclusively comprising a single tubular element (10) which has: a tube axis (11), a tube diameter (12) and a tube wall (13), as well as a front face (14) and a rear face (15), the tube wall (13) having a circumferential, axially running corrugation (20) with axially alternating elevations (21) and depressions (22), the corrugation (20) being formed to correspond radially on the inside and outside of the tube wall (13), and wherein the elevations (21) and depressions (22) are formed circumferentially like a thread with an axial pitch (23). Crash Energy Absorber (100) after claim 1 wherein the corrugation (20) is formed beginning immediately at the front face (14). Crash Energy Absorber (100) after claim 1 or 2 wherein the corrugation (20) is formed terminating in front of the rear face (15). Crash energy absorber (100) according to one of the preceding claims, wherein the amplitude (24) of the corrugation (20) decreases from the front face (14) towards the rear face (15). Crash energy absorber (100) according to one of the preceding claims, wherein the corrugation (20) is formed by means of pressure rolling or embossing in the previously axially flat tube wall (13). Crash energy absorber (100) according to one of the preceding claims, wherein a trigger (26) is formed by means of a locally increased amplitude (24). Crash energy absorber (100) according to one of the preceding claims, wherein the tube element (10) is manufactured as a continuously drawn or welded tube. Motor vehicle (200), having at least the following components: - a body (30); - a plurality of wheels (31) suspended in the body (30); - At least one crumple zone (40) comprising a bumper (41) and/or a rocker panel (42); wherein the crumple zone (40) comprises at least one crash energy absorber (100) according to one of the preceding claims, wherein the tube axis (11) in the direction (F) of a respective main impact according to the design with the front face (14) away from the body (30). is oriented outwards. Manufacturing method for a crash energy absorber (100) according to one of Claims 1 until 7 , comprising at least the following steps: i. providing the tubular member (10); ii. Flow-forming or embossing of the corrugation (20) into the tube wall (13) of the tube element (10). manufacturing process claim 9 , where in step i. the tubular element (10) is provided as a tubular piece (52) with the tubular wall (13) in a corrugated state.

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