WO2015003983A1

WO2015003983A1 - Impact protection device for a motor vehicle

Info

Publication number: WO2015003983A1
Application number: PCT/EP2014/064128
Authority: WO
Inventors: Rolf Schwarzer; Marco Toeller
Original assignee: Kirchhoff Automotive Deutschland Gmbh
Priority date: 2013-07-08
Filing date: 2014-07-03
Publication date: 2015-01-15
Also published as: DE102013107179B4; DE102013107179A1

Abstract

The invention relates to a impact protection device (1) for a motor vehicle comprising an essentially transverse beam (2) made of, in the cross-section, a C-shaped profile, having at least one energy absorption component section (3, 3.1) integrated therein and at least one longitudinal support connecting section (4, 4.1) integrated therein. The transverse beam (2) is closed at least in the periphery of the energy absorption section thereof (3, 3.1) which is predominantly made of TWIP-steel and which is designed for forming a shell on the outer side (9, 9.1) directed in the y-direction.

Description

Shock absorbing device for a motor vehicle

Technical area

The invention relates to a substituted shock absorption device for a motor vehicle, comprising a substantially made of a cross-sectionally C-shaped cross member, which is arranged open in the direction of the body, with at least one integrally formed therein energy absorption component section and with at least one integrally formed therein longitudinal support connection portion.

Background of the invention

With a multi-part construction of conventional impact absorption devices for motor vehicles, a large number of individual processes occur during the production process. In this case, such a shock absorbing device, as is apparent from DE 20 2012 104 1 17 U1, usually a cross member, two spaced apart and attached to this crash boxes, as well as materially connected connection plates, so-called baseplates, for attachment to the longitudinal members of the body , The cross member can be designed as an open or closed profile. An open profile is usually represented by a single substantially U-, C- or hat-shaped sheet metal shell. By contrast, a closed profile is understood to mean either a U-, C- or hat-shaped shell profile, which is provided on its rear side with a striking plate or, for example, an extruded extrusion profile or a profile in which just mentioned shell designs are directed opposite to one another and along their longitudinal course ie transverse to the direction of travel and thus in the y-direction, are at least partially connected such that they support each other at least on their sides or flanks parked on it. However, with both closed and open profiles it is not necessary to close the respective outer sides to improve the impact properties.

To make production more economical, it is known in the art to substitute such a multi-part device. This is done by trying to map the functionality of the individual components at best in a single component. The crossbeam itself should be rigid and extremely strong trained to counteract occurring bending loads can. The attached crash boxes, on the other hand, serve primarily to absorb the impact energy in the event of an impact. Therefore, a substituted shock absorption device essentially consists of only one cross member, in which the crash boxes are integrated as energy absorption component sections and the base plates are integrally formed as side member connection sections.

As can be seen from DE 10 2008 026 334 A1, a rear or front cross member designed as a hat profile open on one side is shown, wherein the cross-sectional depth varies over its longitudinal direction, whereby the resistance moment of the cross member can be influenced. However, in the embodiment of this solution, it is necessary to introduce further deformation elements in each case into the outer regions of the crossbeam formed deeper than the middle section of the crossbeam. Although the use of open profiles is accompanied by a reduction in weight compared with closed profiles, the production process is still expensive.

DE 10 2007 038 496 A1 addresses the disadvantage described in DE 10 2008 026 334 A1 by disclosing therein a method for producing a U-shaped cross member, which has a middle section and respectively adjoining connecting sections which at the same time terminate as Serve Crashbox and are integrally formed with the cross member. In order for the cross member to meet the desired crash requirements, i. rigid and firm, but additional steps, such as additional hardening necessary.

DE 197 15 874 A1 shows a front structure for a passenger car with an upper and lower cross member assembly, which are connected to each other by at least two spaced apart in the vehicle direction tension struts force transfer. A cross member shown here shows a U-shaped cross member profile with lateral leg extensions which protrude approximately horizontally in the vehicle longitudinal direction to the rear. The mentioned leg extensions are detachable on the longitudinal member sections of the body structure, preferably by means of screw connections. fixed and locked inward.

DE 10 2006 057 993 A1 discloses an energy absorption device having a first hollow longitudinal section of first cross-sectional depth and a second hollow longitudinal section of second cross-sectional width and an inverted transitional region between the hollow longitudinal sections, in which these are aligned obliquely to one another prior to energy absorption. Among other things, the device can be manufactured from TWIP steels.

A problem in the prior art is also that open profiles, in contrast to closed profiles have a much lower energy absorption potential. This can be countered, either additional steps, such as partial hardening, or the introduction of additional reinforcing elements are required. In a conventional multi-part embodiment, there are also the disadvantages in terms of process control, tolerance compensation and high costs associated therewith.

It is therefore an object of the invention to provide a shock absorption device for a motor vehicle which eliminates or at least reduces the problems previously discussed in relation to the prior art by fulfilling the required legal provisions of various crash requirements in terms of weight savings, space flexibility and ease of manufacture.

The problem is solved by the aforementioned generic shock absorption device in which the cross member is formed closed at least in the extent of its energy absorption sections of TWIP steel and to form a shell at its pointing in the y direction outer side.

Advantageous embodiments are specified in the dependent claims.

In the context of these statements, the words "front", "rear", "top", "bottom", "outside", "inside", "side" are all references Descriptions of the standardized directions in a vehicle, where "front" and "rear" directions in the x-axis, "top" and "bottom" directions in the z-axis and "outside", "inside" or "laterally" directions in the y axis.

The substituted impact absorption device of the present invention is characterized in particular by the fact that the advantages of a closed and an open profile can be combined with one another by means of a so-called TWIP steel. TWIP steel (Twinning Induced Plasticity) is a reduced-density steel grade that undergoes twinning during plastic deformation, which causes the steel to strongly solidify with high elongation at fracture.

In particular, the property of high ductility has been made in the present invention for the benefit of the shock absorption device in one piece in at least one deep drawing process is designed such that the basically C-shaped shell profile of the cross member at its outer, pointing in the y direction sides closed is. The integrally formed energy absorption component section of the shell profile formed in this way is further formed in lateral view in its cross section larger than the rest of the cross section of the shell profile.

In the prior art, the use of conventional steel grades, such as DP800, in single-piece impact absorbers has allowed maximum draw depths of 45 mm, whereas with TWIP steel draw depths of up to 200 mm can be achieved before cracking occurs ,

Surprisingly, it has been found that conventional multi-part impact absorption devices can be completely substituted and by the deeper than 45mm formed Energieabsorptionsbauteil- section in combination with the formation of each closed outer side of the shell profile, the energy absorption compared to open profiles has significantly increased and in comparison to closed Profiles has already achieved similar values. The force level of the shock absorption device could therefore be improved overall by the frames of the shell profile are dimensionally stable supported without having to bring in other components.

Further, it has surprisingly been found in the impact absorbing device according to the invention that it does not collapse in the event of an impact, but the formed energy absorption regions undergo a folding process even without the introduction of beads, which among other things explain the good energy absorption results.

An advantage of the present invention is the high degree of integration that no additional components, such as separate crash boxes or connecting plates for connection to a side member must be made. As a result, the manufacturing process is simplified and also runs much faster. This is mainly because no additional welding operations must be performed and any tolerance problems of a multi-part assembly in the device according to the invention are not existent. In addition, the deep drawing methods and apparatuses commonly used in the automotive industry for forming body panels can also be used to manufacture the shock absorbing device of the present invention. As a result, a reliable and robust forming process is available on the one hand, and high repeatability on the other.

The fact that the one-piece shock absorbing device is extremely variable in the structural designs, also offers the advantage that account can be taken with regard to the flexibility required by car manufacturers in the design space, for example, in terms of size and geometry. Selecting the material also results in lower weight and lower product costs.

In the following, the invention will be described by way of example with reference to the attached drawings, wherein further advantages and preferred embodiments of the present invention are described in the attached drawings Those skilled in the art will become apparent without departing from the spirit and scope of the invention.

IN THE DRAWINGS SHOWS:

Fig. 1 is an isometric view of a first embodiment of the shock absorbing device according to the invention;

Fig. 2 is a front view of the shock absorbing device of the embodiment of Fig. 1;

Fig. 3 is a plan view of the shock absorbing device of the embodiment of Fig. 1;

Fig. 4 is a sectional view of the shock absorbing device of the embodiment of Fig. 1 along the line A-A;

Fig. 5: a rear view of another embodiment of the shock absorbing device according to the invention.

DETAILED DESCRIPTION

With reference to FIGS. 1 to 3, the substituted shock absorbing device 1 for a motor vehicle comprises a cross member 2 with a substantially C-shaped shell profile, which is arranged open towards the body, with at least one integrated therein energy absorption component section 3, 3.1 and at least one longitudinal carrier connection section 4, 4.1 integrally formed therein.

In this case, the impact absorption device 1 is preferably produced continuously from a TWIP steel, for example from HSD 600, by a deep-drawing process, as an open hollow profile in the form of a substantially C-shaped design. The opening of the C-shaped cross member 2 is in the direction of the body, thus opposite to the direction of travel (x-direction), and is preferably over its longitudinal course, ie transverse to the direction of travel (y-direction), bent towards the rear. It goes without saying that the cross member naturally also comes from a tailor Rolled Blank can be formed.

It remains to be noted, however, that the shock absorption device 1 can certainly also be formed in mate alkombinations, provided that at least the energy absorption section 3, 3.1 consists of TWIP steel. In such a configuration, it makes sense to provide at least the adjacent to the respective energy absorption section 3, 3.1 first section of the actual cross member 2 made of TWIP steel. In this respect, it is then also possible to form the device according to the invention, for example, as a tailored welded blank.

For stiffening the shock absorbing device 1, a shock absorbing device 1 is preferably fully circumferential flange formed on the C-shaped cross member 2 in the z direction, which is turned off by the frames 10, 10.1 and the contour of the cross member 2 to preferably 90 °. In addition, a bead 7 extending transversely to the direction of travel is preferably introduced in the front side of the cross member 2 for stiffening purposes.

Further, an opening 6, 6.1 is formed in the front side in each case in addition to the running transversely to the direction of travel bead 6, 6.1, which is suitable for receiving additional attachments, such as a towing device, threaded sleeves, nuts, etc.

It remains to be noted, however, that such a bead is merely optional and therefore can be omitted, introduced in multiple training or at other locations of the shock absorbing device 1. As is obvious to the person skilled in the art, such an alternative location would be, for example, the energy absorption section 3, 3.1, which would additionally assist in the event of an impact of the folding process, which would also be present without introduced beads.

The shock absorption device 1 comprises two energy-absorbing sections 3, 3.1 designed in integrated construction. In the illustrated embodiment, the energy absorption sections 3, 3.1 have been created from one and the same board with the cross member 2 in the course of a forming process. Hereinafter, the energy absorption section 3 will be described. It is understood that the same statements speaking for the energy absorption section 3.1 apply. The energy absorption section 3 is formed on an outer side of the cross member 2 such that it is pulled substantially lower than the viewed over its longitudinal average portion of the cross member 2. Thus, the cross section of the energy absorption component section 3 is greater than the cross section of the other cross member 2, ie substantially the central region of the cross member 2. This is particularly clear from the cross-sectional view along the line AA of Fig. 4. The transition from the energy absorption section 3 to the central region of the cross member 2 is preferably flowing. In addition, it is characteristic that the outer side of the shell profile 2 is formed closed, so that structurally a conventional crash box is shown integrated, which is open towards the inside and to the rear and therefore brings a material savings compared to the conventional devices. In this case, a drawing depth of more than 45 mm, preferably 1 15 mm realized. The energy absorption section 3 is, viewed over the longitudinal extension of the cross member 2, formed so broad that this width largely corresponds to the width of the longitudinal member to be connected (not shown).

In general, it should be noted at this point that, with at least one deep-drawing operation in further embodiments (not shown), drawing depths in a range from 80 mm to 200 mm are preferably realized.

Furthermore, the impact absorption device 1 comprises two longitudinal carrier connection sections 4, 4.1, which are designed in integrated construction. In the following, the side member connecting portion 4 will be described. It is understood that the same statements apply accordingly to the side member connecting section 4.1. The flange 8 enclosing the energy absorption section 3 forms the side member connection section 4 in this region. This is provided with openings 6.2, 6.3, 6.8, 6.9 via which the impact absorption device 1 is connected to the longitudinal member of a body by means of connecting elements. It will be apparent to a person skilled in the art that optionally a reinforcing plate can also be interposed during the connection to the side member. With reference to FIG. 5, a further embodiment of the impact absorption device 1 according to the invention is shown there. Characteristic is the additional attachment of a striker plate 5 at the rear of the cross member 2, which further increases the flexural rigidity of the shock absorbing device 1. It would also be conceivable, of course, to provide the cross member 2 with a plurality of strike plates in its rear region, which are arranged at different sections. Incidentally, the statements made for the first embodiment apply.

In a further embodiment (not shown), the cross member 2 over its longitudinal course straight or space-optimized, for example, by an S-shaped transition from the Energieabsorptionsbauteilab- section to the central region of the cross member 2 is formed.

The above explanations make it clear that the impact absorbing device 1 designed according to the invention has eliminated or at least reduced the problems discussed in the prior art by combining the advantages of closed and fully opened profiles. With appropriate weight savings through the optimal use of material in combination with the changed geometric design of the shock absorbing device, both an easier, as well as a more cost-effective manufacturability has been achieved. The resulting space flexibility is also achieved while maintaining the required legal provisions regarding the various crash requirements.

The foregoing description represents only preferred embodiments. The current claims are not limited solely to these embodiments. Rather, all equivalent changes and modifications that may be inferred or made in this field by one of ordinary skill in the art are intended to be within the scope of the present invention to the extent of the claims hereof. LIST OF REFERENCE NUMBERS

A shock absorbing device

crossbeam

Energy absorption component section

Longitudinal beams connecting section

striking plate

opening

Beading

flange

outer side

frame

Claims

claims

One-piece Stoßabsorptionsvorhchtung for a motor vehicle, comprising a substantially made of a cross-sectionally C-shaped cross member (2), which is arranged open towards the body, with at least one integrally formed therein energy absorption component section (3, 3.1) and at least one therein integrated longitudinal member connecting portion (4, 4.1), characterized in that the cross member (2) at least in the circumference of its energy absorption sections (3, 3.1) made of TWIP steel and to form a shell at its pointing in the y direction outer side (9 , 9.1) is formed closed.

Shock absorbing device according to claim 1, characterized in that in the cross member (2) at least one opening (6, 6.1, 6.2, 6.3, 6.4, 6.5, 6.6, 6.7, 6.8, 6.9) and / or at least one bead (7) is formed.

Shock absorption device according to claim 1 or 2, characterized in that the cross member (2) over its longitudinal extension is substantially straight, bent backwards and / or designed space-optimized.

Shock absorbing device according to one of the preceding claims, characterized in that the cross member (2) is formed with at least one further attachment and / or at least partially provided in a rear region with at least one strike plate (5).

Shock absorbing device according to one of the preceding claims, characterized in that the cross member (2) is designed as a Tailor Rolled Blank or Tailored Welded Blank.

Impact absorption device according to one of the preceding claims, characterized in that the cross member (2) is with its integrated energy absorption component sections (3, 3.1) made of TWIP steel.

Shock absorbing device according to one of the preceding claims, characterized in that the outer side (9, 9.1) of the cross member (2) and / or the integrally formed energy absorption component sections (3, 3.1) has a drawing depth of more than 45 mm.

Shock absorbing device according to one of the preceding claims, characterized in that the outer side (9, 9.1) of the cross member (2) and / or the integrally formed energy absorption component section (3, 3.1) after at least one deep drawing operation preferably a drawing depth of 80 mm to 200 mm.

Shock absorption device according to one of the preceding claims, characterized in that the cross-section, starting from the correspondingly integrally formed energy absorption component section (3, 3.1), is larger than the cross section of the remaining cross member (2).

Shock absorption device according to one of the preceding claims, characterized in that the at least one side member connecting portion (4, 4.1) by a at least one integrally formed Energieabsorptionsbauteilab- section (3, 3.1) along the contour of the cross member (2) encircling and preferably parked at 90 ° Flange (8) is formed.