Energy absorption device

The present invention relates to an energy absorption device (1) for a bumper arrangement of a vehicle, with a hollow longitudinal section (2) intended for deformation, a rolled-back region (3) adjoining the hollow longitudinal section, and an extension section (4) connected to the rolled-back region. In order to improve an energy absorption device of this type to the extent that obliquely acting accident forces can be absorbed with a high degree of efficiency in as simple a manner as possible, it is proposed, in an initial state prior to energy absorption, to orient the hollow longitudinal section (2) obliquely with respect to the axial direction of the extension section (4).

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a national entry application of PCT Application WO 2008/067951 filed on Nov. 29, 2007, entitled “Energy Absorption Device” which claims priority from German Utility Model No. 20 2006 018 616 filed on Dec. 8, 2006, entitled “Energieabsorptionsvorrichtung” (Energy Absorption Device), and German Patent No. 10 2006 057 993 filed on Dec. 8, 2006 entitled “Energieabsorptionsvorrichtung” (Energy Absorption Device), the disclosures of which are incorporated herein by reference for all purposes.

FIELD OF THE INVENTION

The present invention relates to an energy absorption device.

BACKGROUND OF THE INVENTION

The present invention relates to an energy absorption device with a first hollow longitudinal section with a first horizontal cross section width and a second hollow longitudinal section with a second horizontal cross section width, as well as a rolled-back transition section between the two hollow longitudinal sections.

Energy absorption devices of this type are used in vehicles and, located, for example, between bumper and chassis. In an accident, they plastically deform and thereby absorb energy. In light accidents, the ability to absorb energy can be sufficient in order to prevent a plastic deformation of the chassis.

In order to guarantee faultless deformation, i.e. telescoping together, the energy absorption device is mounted parallel to the longitudinal direction of the vehicle.

In practice however, accidental forces can occur that are active oblique to the longitudinal direction of the vehicle. In such a case it can happen that the hollow longitudinal section of the energy absorption device positions itself oblique relative to the hollow longitudinal section. In order to control such an oblique position, i.e. to align both hollow longitudinal sections straight again with respect to each other, from DE 103 24 403 A1 a specific design of the transition section is known. On the outside of the transition section, a large, U-shaped curve is provided. Against it, the inner hollow longitudinal section comes to abut and when it is telescoped together it is aligned straight again. An inner U-shaped curve of the transition section is designed with a small radius, as a result of which the inner hollow longitudinal section is always mounted close to the outer, large curve.

A similar arrangement in which a hollow longitudinal section on the side of the bumper is straightened again is known from U.S. Pat. No. 6,702,345 B1.

One possibility for absorbing obliquely acting accident forces is known from U.S. Pat. No. 6,802,458 B2. Here, a generic energy absorption device is used, which is aligned at oblique to the longitudinal direction of the vehicle. Thus an oblique accident force acts in longitudinal direction in the energy absorption device, whereby it can faultlessly telescope together.

U.S. Pat. No. 6,802,548 B2 proposes the use of a cup-shaped shock absorption element, which is mounted before the energy absorption device on the bumper side. In the event of an obliquely acting accident force with respect to the longitudinal axis of the energy absorption device, with the help of the cup-shaped shock absorption element a pivoting of the hollow longitudinal section is prevented or at least largely minimized.

The present invention further concerns an energy absorption device for a shock absorption arrangement of a vehicle with a hollow longitudinal section designed for deformation, that is aligned oblique to the longitudinal direction of the vehicle and a section that follows it that is a rolled-back section at which the mounting plane of the energy absorption device is provided which defines the mounting plane of the energy absorption device.

From DE 19 31 844 A, an energy absorption device is known which is provided with a certain tube for deformation and a following rolled-back section to which an extension piece is connected which extends outward. The extension piece is mounted at a guide component that is designed as a circular disk. The extension piece and the guide piece are aligned parallel to the horizontal cross section plane of the tube. In this manner, the tube can faultlessly deform rolling back and project through the opening of the guide component.

SUMMARY OF THE INVENTION

The present invention relates to an energy absorption device with a first hollow longitudinal section with a first horizontal cross section width and a second hollow longitudinal section with a second horizontal cross section width, as well as a rolled-back transition section between the two hollow longitudinal sections.

The present invention is based on the objective of improving a generic energy absorption device in such a way that in as simple a way as possible, obliquely acting accident forces can be absorbed with a high degree of efficiency, as well as a process for manufacturing such an energy absorption device.

The problem is solved in accordance to the invention with an energy absorption device with the characteristics of the claims.

With an oblique alignment of the hollow longitudinal section to the axial direction of the extension section, obliquely acting accident forces can be buffered well and absorbed. The deformation process runs surprisingly faultlessly and a similarly a high degree of flow of force can be achieved as in the energy absorption devices in which the axial direction of the extension section is aligned parallel to the axial direction of a hollow longitudinal section.

Advantageously, the axial direction of the hollow longitudinal section or the extension section can be aligned oblique to the longitudinal direction of the vehicle and the axial direction of the respectively other section essentially parallel to the longitudinal direction of the vehicle. Thereby, oblique accident forces can be buffered easily and the forces can still be introduced relatively straight into the vehicle chassis, for example, into a longitudinal carrier of the chassis, at which the energy absorption device can be mounted.

Especially preferred, the hollow longitudinal section can be aligned oblique by approximately 5° to 20° with respect to the axial direction of the extension section, preferably by approximately 8° to 12°, particularly preferred by approximately 10°. In this way, oblique accident forces can be buffered well and absorbed well and in spite of that, even forces acting parallel to the longitudinal direction of the vehicle can still be buffered and absorbed.

Particularly favorably, a guide can be provided on which the hollow longitudinal section rolls off during deformation. In this way, a telescoping motion with a high degree of stability results.

The problem is also solved according to the invention with an energy absorption device with the characteristics of the claims.

With the oblique alignment of the horizontal direction of the hollow longitudinal section with respect to the mounting plane, accident forces acting oblique to the longitudinal direction of the vehicle can be absorbed well. The deformation process is surprisingly faultless and an approximate efficiency factor in energy absorption can be achieved as it is possible in energy absorption devices in which the mounting plane is aligned parallel to the horizontal direction of the hollow longitudinal section.

Advantageously, the mounting plane can be aligned approximately perpendicular to the longitudinal direction of the vehicle. Thereby, the hollow longitudinal section is aligned oblique to the longitudinal direction of the vehicle and can, for the most part, accept oblique accident forces corresponding to its longitudinal direction. By way of the mounting section, the remaining forces can, to a large extent, be passed on in the longitudinal direction of the vehicle.

Preferably, the rolled-back region can be designed at an end section of the energy absorption device. Thus, the rolled-back deformation of the hollow longitudinal section begins at the end of the energy absorption device.

Particularly favorable, the energy absorption device can be mountable in the direction of the longitudinal section approximately at approximately the height of the rolled-back section at a chassis structure. In this way, the energy absorption device can be mounted with a high degree of stability. Moreover the alignment of the hollow longitudinal section can adapt well to those accident forces, the direction of which deviates from the original direction of its longitudinal direction.

Particularly advantageously, the rolled-back section can have an only U-shaped roll-back shape. Thus, the transition form the longitudinal section to the mounting section is simple and can also be realized in a narrower space.

Particularly preferred, the mounting section can be designed like a flange, like a flap or a collar. Thus, the energy absorption device can be easily and 2-dimensionally mounted on a vehicle.

Particularly favorable can be a vehicle structure with an energy absorption device with at least one of the previously mentioned designs, whereby the vehicle structure has a cladding which forms a guide for the hollow longitudinal section, on which such can be rolled off during deformation. In this way, existing structures of a vehicle are usable for guided telescoping of the hollow longitudinal section, for example, a longitudinal carrier, especially an interior space of such. By rolling off, the contact of cladding and rolling-back longitudinal section works faultlessly.

Moreover, the problem is solved according to the invention, with an energy absorption device with the characteristics of the claims.

With the oblique alignment of the hollow longitudinal sections, obliquely acting accident forces can be buffered and absorbed well. Thereby, surprisingly a similarly a high degree of progression of force as in the energy absorption devices with longitudinal sections that are aligned straight is achieved, i.e. a high degree of efficiency in energy absorption is achieved.

Preferably, that hollow longitudinal section that has greater roll-back-capability can be aligned oblique to the direction of the vehicle. In this way, an oblique accident force can be absorbed especially efficiently. The longitudinal section designated for deformation can accept the accident force in its longitudinal direction.

Particularly favorably, the hollow longitudinal section with smaller horizontal cross section width can be the more capable of rolling back hollow longitudinal section of the energy absorption device. In this way, the hollow longitudinal section with larger horizontal cross sectional width can be used for stabilization; it has, as it were, the broader support structure.

Particularly advantageously, the hollow longitudinal section with larger horizontal cross sectional width can form a guide for the hollow longitudinal section with smaller horizontal cross sectional width. While telescoping together, the longitudinal section with smaller horizontal cross-sectional width can support itself at the longitudinal section with larger horizontal cross-sectional width and roll off on it. In this way, a telescoping motion results with a high degree of stability.

The problem is solved further with a process with the characteristics of the claims.

With this process, an energy absorption device with obliquely aligned hollow longitudinal sections can be manufactured simply and with a high degree of precision, particularly concerning the angularity of the hollow longitudinal sections to one another.

Particularly advantageously, the tube of first horizontal cross section width can be enlarged in sections to the second horizontal cross section width with the help of an interior high pressure deformation. As a result of this, the longitudinal section of larger horizontal cross section width can be manufactured with a high degree of precision and simultaneously strengthened by the deformation; this means that it receives a higher deformation resistance.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 1shows an energy absorption device1of a first embodiment of the invention shown in a perspective view. The energy absorption device1has a hollow longitudinal section2that is designated for deformation. Following the hollow longitudinal section2is a rolled-back section3, at which a mounting section4is provided as extension section. The mounting section defines a mounting plane of the energy absorption device1.

In this embodiment of the invention, the mounting section4is designed approximately flange-like and the mounting plane5is specified by an abutment surface6of the mounting section4on the side of rolled-back section3.

It is also possible to design the mounting section like a flap or a collar.

The hollow longitudinal section2is shaped like a tube in this embodiment of the invention. However, other open or closed hollow-body-like forms are also possible, for example, with an oblique horizontal cross section.

InFIG. 2, the energy absorption device1is shown in a lateral view. From this illustration it can be seen particularly clearly that the mounting plane5is aligned oblique with respect to the horizontal direction of hollow longitudinal section2. This means that it runs oblique to the—not shown—straight line perpendicular to longitudinal axis7of hollow longitudinal section2. In other words, a normal8of mounting plane5runs oblique to longitudinal axis7of hollow longitudinal section2. Thus, the hollow longitudinal section is aligned oblique to the axial direction of the mounting section. The normal8runs in axial direction of the mounting section.

The mounting plane and the horizontal direction make an angle of approximately 5° to 20°, preferably an angle of 8° to 12° and particularly preferred an angle of approximately 10°. In other words, the normal8and the longitudinal axis7of hollow longitudinal section2make an angle9of the previously described dimension. With this angularity oblique to the longitudinal direction of the vehicle acting accident forces can be buffered and absorbed particularly well, for example, accident forces that act oblique at 10° to the longitudinal direction of the vehicle. But accident forces that act parallel to the longitudinal direction of the vehicle can still be accepted well and absorbed.

InFIG. 3, a longitudinal cross section of the energy absorption device according to line inFIG. 2is shown. It can be seen from this that the rolled-back section3that is designed in the end section10of the energy absorption device has a purely U-shaped rolled-back section with a U-arc17. From the outer U-section11, the rolled-back section3transitions directly into mounting section4.

In this embodiment of the invention mounting section4starts in direct proximity of hollow longitudinal section2. This means that the distance of the mounting section4to the hollow longitudinal section2is small compared to the width of the horizontal cross section of hollow longitudinal section2. Moreover, the mounting section in the direction of the hollow longitudinal section is approximately at the height of the rolled-back region3.

By providing mounting section4in the area of the end section10of the energy absorption device and close to the second hollow longitudinal section2, the energy absorption device is stable and can be mounted directly on a vehicle structure. Thereby, an end that is located opposite to the rolled-back region3of the energy absorption device is sufficiently movable in order to adapt to the accident forces, whose direction runs oblique to the longitudinal axis7of the hollow longitudinal section. Above the rolled-back region3, a pivoting of hollow longitudinal section2can be offset, whereby in a circumference section, a rolling-back deformation of the hollow longitudinal section can occur.

FIG. 4shows the energy absorption device schematically in a position that is mounted between the chassis structure13and the bumper arrangement14. The chassis structure13can, for example, be a longitudinal carrier, whose longitudinal direction15runs parallel to the longitudinal direction of the vehicle.

The energy absorption device1is mounted on the chassis structure13in such a way that the normal8of mounting plane5and the longitudinal direction15of the chassis structure run parallel to one another. In this embodiment of the invention, they even coincide. Accordingly, the mounting plane5is aligned approximately perpendicular to the longitudinal direction of the vehicle and the longitudinal axis7of hollow longitudinal section2runs at the angle of the dimension mentioned, oblique to the longitudinal direction of the vehicle.

InFIGS. 1 to 4, the energy absorption device is shown in initial condition prior to an energy absorption. If, perhaps, an accident force16acts in the direction of the longitudinal axis7of hollow longitudinal section2, the energy absorption device plastically deforms rolling back. Thereby, the U-arc17of the rolled-back region is bent and continually, new material of the deforming hollow longitudinal section2that is rolling-back forms an antecedent arc.

The hollow longitudinal section telescopes into a cavity18of the chassis structure13. During progressive energy-absorbing telescoping into it, the leading curve comes to abut with a cladding19of chassis structure13. The cladding19serves as support of the hollow longitudinal section and as guide for additional rolling-back deformation. The hollow longitudinal section can roll off from cladding19in rolling-back manner. For this reason, the contact with the cladding happens faultlessly.

The energy absorption device can be manufactured by a thermoforming process out of a flat material, for example out of a blank. In the process, a part of the flat material is used for designing the hollow longitudinal section2and the rolled-back region3. A part of the flat material remains flat and is used for designing the mounting section4.

InFIG. 5, an energy absorption device101of a second embodiment of the invention is shown in a perspective view, inFIG. 6in a top view and inFIG. 7in a longitudinal cross section according toFIG. 6. The energy absorption device101has a first hollow longitudinal section102, which has a first horizontal cross section width103and a second hollow longitudinal section104, which has a second horizontal cross section width105. In this example of an embodiment, the first horizontal cross section width103is smaller than the second horizontal cross section width105.

The first and second hollow longitudinal section102,104are designed tube-shaped in this embodiment. However, other open or closed hollow-body-like forms are also possible, for example with an angular horizontal cross section.

Between the two hollow longitudinal sections102,104, a rolled-back transition section106is designed.

One could also say that a rolled-back region follows a hollow longitudinal section that is designated for deformation, which is connected to an extension section. Depending on the embodiment, the first hollow longitudinal section or the second hollow longitudinal section can be the extension section.

The rolled-back transition section has an essentially S-shaped or double-U-shaped longitudinal cross section profile, as can be seen inFIG. 7. A first U-arc107emanates from first hollow longitudinal profile102and is located within the second hollow longitudinal section104. A second U-arc108starts at the second hollow longitudinal profile104and is located outside of the first hollow longitudinal section102and surrounds such.

The first hollow longitudinal section102and the second hollow longitudinal section104are oblique to one another, whereby their longitudinal axis109,110are at an angle111. Angle111is selected in a range of approximately 5° to 20°, preferably in a range of approximately 8° to 12°, and particularly preferred in a range of approximately 10°. In this way, obliquely acting accident forces can be dissipated well, especially in accidents with approximately 10° incline to the longitudinal direction of the vehicle.

In this embodiment of the invention, the energy absorption device is designed in one piece.

InFIG. 8it is illustrated, how the energy absorption device101can be mounted in a vehicle. In the present example of an embodiment, it is provided between a chassis structure112and a bumper arrangement113. Thereby, the illustration inFIG. 8is a schematic view of the longitudinal cross section profiles.

The bumper arrangement113can be a horizontal carrier or a horizontal profile of a bumper, and the chassis structure112can be a longitudinal carrier of a vehicle chassis. In this example of an embodiment, the second hollow longitudinal section with larger horizontal cross section width is mounted at the chassis structure112, and its longitudinal axis110runs parallel to the longitudinal axis114of the chassis structure112, whereby these two longitudinal axes110,114coincide in this embodiment of the invention.

The longitudinal axis114of the chassis structure112runs parallel to the longitudinal direction of the vehicle. Thus, the first hollow longitudinal section102with smaller horizontal cross section width is mounted oblique to the longitudinal direction of the vehicle. The longitudinal axis109of the first hollow longitudinal section consequently makes the same angle with the longitudinal direction of the vehicle as in the longitudinal axis110of the second hollow longitudinal section104.

Embodiments are also possible in which the longitudinal axis of the hollow longitudinal section with smaller horizontal cross section width runs parallel to the longitudinal axis of the chassis structure and it is mounted on such. The hollow longitudinal section with larger horizontal cross section width would then be located running obliquely to the longitudinal direction of the vehicle.

In the present embodiment of the invention, the first hollow longitudinal section that is located on the bumper side has a higher capability of rolling back than the second hollow longitudinal section that is mounted on the chassis side. Hereby, the energy-absorbing deformation of the energy absorption device101takes place essentially at the expense of the first hollow longitudinal section102. This means that in this embodiment of the invention, the second hollow longitudinal section is the extension section.

With this arrangement, accident forces acting oblique to the longitudinal direction of the vehicle, particularly perhaps accident forces acting in longitudinal direction109of the first hollow longitudinal section102are especially well absorbed, as can be seen in the schematic illustrations of simulations inFIGS. 9 to 11. The chassis structure112and the bumper arrangement113are illustrated—conditionally interrupted by the simulation model—and the chassis structure is rendered in a structure that runs horizontal to the second hollow longitudinal section.

FIG. 9shows energy absorption device101in an initial condition prior to absorption of the accident energy, i.e. in the condition as it is shown inFIGS. 5 to 8.

When an accident force acts, the first hollow longitudinal section102begins to deform plastically rolling-back from U-arc107. The more the direction of the accident force coincides with the longitudinal axis of the first hollow longitudinal section102, the more the circumference section of first hollow longitudinal section102—which starts immediately—deforms by rolling back.

A deviation of the direction of the accident force115from the direction of the longitudinal axis109of the first longitudinal section102is compensated by the quasi lose mounting of the transition area by a rolling-back deformation, which at first takes place in only one circumference section.

When it telescopes together, the first U-arc107of transition section106is bent and always new material of the first hollow longitudinal section102now forms an antecedent arc170. This reaches the interior side of the second hollow longitudinal section104. The second hollow longitudinal section104thereby forms a guide for first hollow longitudinal section102. Thereby, the first longitudinal section rests on the second hollow longitudinal section and rolls off on such, as it is shown inFIGS. 10 and 11.

The accident force that is absorbed by the obliquely aligned first hollow longitudinal section102is introduced by the second hollow longitudinal section still relatively straight into the chassis structure112. With its larger horizontal cross section width105, the second hollow longitudinal section104is thereby stabilized well.

In spite of using an energy absorption device in which the hollow longitudinal sections are aligned oblique to one another, surprisingly, during the energy absorption a high degree of flow and a high degree of progression of force is achieved. The progression of force and the efficiency of the energy absorption lie in a similar range as in energy absorption devices in which the hollow longitudinal sections are aligned straight with respect to one another.

InFIG. 12, a force flow diagram is shown for the energy absorption device in accordance with the invention. The abscissa axis represents the path of the approaching of the outer ends of the energy absorption device and the ordinate, the force that is applied to these ends. A first section of the path120contains the Hook range. With the transition into the second path section121, the plastic deformation of the energy absorption device starts. In the course of the second path section121, the expenditure of force increases by sections and, and thereafter falls again somewhat. This increased expenditure of energy is required for the bending of the original first U-arc107.

After the expenditure of energy falls in the second path section121, the expenditure of energy significantly increases in a third path section122by an amount identified by legend123.

This increase in expenditure of energy is required for the deformation of the inner, first hollow longitudinal section102by rolling back subject to an enlargement of diameter.

In the following, processes in accordance with the invention for manufacturing a one piece energy absorption device101of the second embodiment of the invention are described.

InFIG. 13, a tube130with first horizontal cross section width103is shown which is used in the first embodiment of the manufacturing process according to the invention. With a high interior pressure deformation process, the horizontal cross section width of tube130is enlarged in sections. Thereby, a cone-shaped—in longitudinal cross section—transition section131is formed between the thus created hollow longitudinal sections102,104, as is shown inFIG. 14.

The two hollow longitudinal sections102,104are not pressed toward one another in longitudinal direction, i.e. the cone-shaped transition section131is compressed, whereby an S-shaped or double-U-shaped transition section is created. Subsequently, the hollow longitudinal sections102,104are brought into an angled alignment with one another with a tool, whereby the transition section plastically transforms and takes on the form shown inFIGS. 5 to 7.

InFIGS. 15 and 16, a second embodiment of the manufacturing process according to the invention is illustrated. Here, a tube140is used, which is designed as shown inFIG. 13, however, it has a larger horizontal cross section width. The tube140is clamped between axial bearings or brackets142,143. With the help of a spinning tool145that works in the direction of arrow144and is shown inFIG. 15, the horizontal cross section width of tube140is narrowed in sections. As a result, a transition section141is formed, which at first has a cone-shaped profile in longitudinal cross section.

As a result of the narrowing of the horizontal cross section width, without axial bearing142,143, the length of tube140would lengthen. However, as axial bearings142,143forces the tube to retain its axial length, the transition section141is deformed rolling back. Thus, the formation of an S-shaped or a double-U-shaped transition section is an integrated process in this manufacturing process.

Subsequently, the longitudinal sections102,104that were created are obliquely aligned with one another with a tool, whereby the transition area plastically deforms and takes on the form shown inFIGS. 5 to 7.

It is also possible to manufacture the energy absorption device with spinning tools, however, without axial bearings142,143. In this process, the transition section141is compressed after roller-burnishing as in the first embodiment of the manufacturing process.

The second U-arc108, i.e. the U-arc that is not intended for rolled-back deformation bordering on the second hollow longitudinal section104, can be stabilized by a joining process. With that, a deformation is countered at the expense of the second hollow longitudinal section. As joining material, adhesive, welding material or soldering material can be used, which is put into this U-arc108.

Stabilization by joining has a similar effect as a work-hardening or the provision of a trueing in the second U-arc. These steps can be performed in addition or alternatively.

The work-hardening steps can also be performed on the first U-arc107, when the second hollow longitudinal section is intended for rolled-back deformation.

The energy absorption device can, for example, be manufactured from steel with induced plasticity. During deformation, they experience a significant increase of extensibility at increased density. In this manner, the energy absorption device can also be manufactured by roller-burnishing by narrowing the horizontal cross section width, whereby the area of narrowed cross section width, i.e. the first hollow longitudinal section still remains the horizontal cross section that is more capable of being rolled back, even though its density increases somewhat as a result of the deformation.

As steels with induced plasticity, LIP steels (light weight steels with induced plasticity) can be used, for example, XIP steels (extremely high strength steels with induced plasticity) or TWIP steels (twinning induced plasticity.

The energy absorption device of the first embodiment of the invention can also be manufactured from the named steels.

It should be appreciated that the foregoing description is illustrative in nature and that the present invention includes modifications, changes, and equivalents thereof, without departure from the scope of the invention.