Bottom plate of motor vehicle

Abstract

The invention relates to an underfloor (1) of a motor vehicle, having a flat floor (2) and having a deformation (3) in the form of at least one flange (10) on each of two longitudinal sides lying opposite each other in the transverse direction of the motor vehicle, the underfloor (1) extending between a front axle and a rear axle of the motor vehicle, the lower base plate (1) is thermally deformed and press-hardened as a one-piece sheet-metal deformation component in a press stroke, regions having different tensile strengths Rm and / or wall thicknesses are formed, and an outwardly projecting flange (10) is provided, the flange has a bolt hole as a tightening point to the motor vehicle body and the flange (10) is soft and has a tensile strength Rm of less than 1000 MPa.

Description

Technical Field

[0001] The invention relates to a lower floor panel of a motor vehicle. Background Art

[0002] It is known from the prior art that motor vehicle bodies are manufactured as so-called monocoques. Such motor vehicles are driven by internal combustion engines, but increasingly also by electric motors.

[0003] The monocoque motor vehicle body is composed of individual body parts, such as A-pillars, B-pillars, C-pillars, vehicle door sills and various crossbeams or longitudinal beams, which are located on the window frame, but also on the floor, for example. To this end, the individual components are processed by deformation technology and then joined to each other, in particular welded. This forms a monocoque motor vehicle body. DE 10 2004 037 789 B3 discloses a floor of a motor vehicle. Summary of the invention

[0004] Starting from the prior art, the object of the present invention is to produce the lower underbody of a monocoque motor vehicle body more cost-effectively and with greater geometrical precision than the prior art with its production method, wherein at the same time specific rigidity or crash characteristics as well as stone chip impact and aerodynamics can be set.

[0005] According to the invention, the above-mentioned object is achieved by a lower floor of a motor vehicle.

[0006] The invention relates to a lower floor panel of a motor vehicle, which has a flat bottom and a deformation in the form of at least one flange on two longitudinal sides lying opposite each other in the transverse direction of the motor vehicle. The lower floor panel extends on the motor vehicle body between the front axle and the rear axle and thus forms essentially the entire bottom of at least the passenger compartment of the motor vehicle. It can therefore also be said to be the motor vehicle bottom itself.

[0007] Therefore, it can also be understood as a lower floor assembly in the sense of the present invention. Therefore, at least the vehicle door sill, the footboard or the floor and optionally or alternatively the footboard are provided with a battery slot arranged vertically with respect to the vehicle, and the lower floor is arranged below these components as an underrun protection plate and a protection plate. At least another of the above components can be a region that has been thermally deformed and press-hardened and also has different tensile strengths Rm and / or different wall thicknesses.

[0008] According to the invention, the lower base plate is characterized in that it is hot-formed and press-hardened as a one-piece sheet metal deformation component in one press stroke, wherein regions with mutually different tensile strengths Rm are formed. Alternatively or additionally, regions with mutually different wall thicknesses can also be formed.

[0009] Alternatively or additionally, there is a flange with bolt holes as screwing points to the motor vehicle body. Thus, the lower floor is screwed to the motor vehicle body from below, for example below the floor of the motor vehicle body or below the battery carrier.

[0010] Alternatively or additionally in turn, the lower floor panel is then arranged beneath the motor vehicle floor panel.

[0011] The lower floor is therefore characterized by simple production based on a large-format press, with which the lower floor is manufactured. This ensures a high overall precision of the lower floor itself. In the sense of the invention, one-piece is to be understood as being manufactured from a sheet metal blank. The sheet metal blank itself is preferably manufactured as a tailored blank. Therefore, the individual plates are welded together to form a large sheet metal blank. Preferred butt welding can be performed here. However, lap welding can be performed to produce the sheet metal blank as a tailored blank. The tailored blank is then manufactured in a deformation press in one press stroke. By using heat hardening technology and press hardening technology, areas with different tensile strengths from one another are set during the heat hardening operation and the press hardening operation. Therefore, the rigidity requirements on the lower floor can be set consciously, but the collision characteristics can also be set.

[0012] The high-strength region has a tensile strength of greater than 1000 MPa. The high-strength region has a tensile strength of greater than 1350 MPa. A tensile strength Rm greater than 1500 MPa, in particular greater than 1800 MPa, can also be set.

[0013] In this context, softer regions, so-called soft zones, are formed having a tensile strength of less than 1000 MPa, preferably less than 850 MPa, in particular a tensile strength of between 550 MPa and 850 MPa.

[0014] Furthermore, the side of the lower floor panel that is located on the outside in the transverse direction of the vehicle can be particularly preferably designed as an inner rocker shell. For this purpose, a deformation portion and in particular a connecting flange are then provided, so that the inner rocker shell, that is, the inner half shell of the rocker, is formed in one piece through the outer side of the lower floor panel. The outer shell of the rocker is then attached, whereby a hollow profile of the motor vehicle and thus a side rocker is produced in cross section.

[0015] In the outer side region, a soft longitudinal strip is formed with respect to the transverse direction of the vehicle. This soft longitudinal strip then extends in the longitudinal direction of the vehicle itself. As a result, the intensity of the initial collision deformation can be reduced. However, since only the longitudinal strip is designed to be soft, with a tensile strength Rm of less than 1000 MPa, the adjacent regions, i.e. the inner region of the lower floor and the outer region together with the vehicle sill, provide high rigidity in the case of a side impact, especially in the extreme test.

[0016] In another preferred design variant, the lower floor extends in the longitudinal direction of the vehicle to below at least one central longitudinal section of the front axle and / or to below at least one central longitudinal section of the rear axle. Preferably, the lower floor can also cover at least 75% of the respective longitudinal extension of the respective axle, thus covering at least 75% of the front axle and at least 75% of the rear axle in the longitudinal direction. Thus, the lower floor also serves as a protective plate, for example in the event of an obstacle.

[0017] For this reason, in particular, a reinforcement bead can also be formed, for example a longitudinal and / or transverse bead. It is also advantageous in the sense of the present invention to form an X-shaped reinforcement bead, thus forming a reinforcement bead that crosses itself in its longitudinal direction.

[0018] Furthermore, planar floor regions, in particular with rounded edges or elliptical in top view, are designed as soft regions. Thus, deformation behavior is achieved in the event of a crash. By virtue of these regions being designed as planar regions, but nevertheless surrounded by hard regions, preferably hard longitudinal regions or longitudinal sections also extend in the longitudinal and transverse directions. In the lower floor panel, sufficient rigidity is achieved in the longitudinal direction of the vehicle, but also in the transverse direction of the vehicle, even in the event of a crash.

[0019] Furthermore, a flange is formed in the cross section, which protrudes outward in the transverse direction of the motor vehicle. The protruding flange is formed to be soft.

[0020] In another preferred design variant, a hollow profile can be used on the inner side of the deformed edge. This hollow profile can be used to reinforce the motor vehicle body. The hollow profile itself can be made of light metal material, for example. The hollow profile can be provided for connecting a battery carrier. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Other advantages, features, characteristics and aspects of the present invention are the subject of the following description. Preferred design variants are shown in schematic diagrams. These drawings help to simplify the understanding of the present invention. It is shown in them:

[0022] Figure 1 A lower floor panel for use in a motor vehicle body is shown;

[0023] Figure 2 Shown along Figure 1 A cross-sectional view taken along the cutting line ll-ll;

[0024] Figure 3 An alternative design variant is shown;

[0025] Figure 4 a and Figure 4 b shows a top view and a cross-sectional view;

[0026] Figure 5 a and Figure 5 b shows an alternative top view and a cross-sectional view;

[0027] Figure 6 a and Figure 6 b shows an alternative top view and a cross-sectional view;

[0028] Figure 7 a and Figure 7 b shows an alternative top view and a cross-sectional view;

[0029] Figure 8 a and Figure 8 b shows an alternative top view and a cross-sectional view;

[0030] Fig. 9 a and Fig. 9 b shows an alternative top view and cross-sectional view.

[0031] List of reference numerals:

[0032] 1: Lower base plate

[0033] 2: Surface bottom

[0034] 3: Deformation

[0035] 4: Front

[0036] 5: Dorsal

[0037] 6: Battery slot

[0038] 7: Inside

[0039] 8: Hollow profile

[0040] 9: wall

[0041] 10: Flange

[0042] 11: Threshold

[0043] 12: Threshold plate

[0044] 13: Vertical bar

[0045] 14: Elliptical area

[0046] 15: Curling or strengthening curling

[0047] X: Longitudinal direction of the vehicle

[0048] Y: Transverse direction of the vehicle DETAILED DESCRIPTION

[0049] In the figures, the same reference numerals are used for identical or similar components, even if a repeated description is omitted for the sake of simplicity.

[0050] Figure 1 A lower floor panel 1 for use in a motor vehicle body is shown. The lower floor panel 1 has a flat bottom 2 and, with respect to the vehicle transverse direction Y, a deformation 3 in the form of a circumferential wall on two opposite sides. In addition, flanges or the like described below can also be formed. Deformations 3 can also be present on the front side 4 with respect to the vehicle longitudinal direction X, just as on the rear side 5, wherein the rear side 5 is also with respect to the vehicle longitudinal direction X. The lower floor panel 1 preferably has an extension of more than 150 cm×100 cm in a top view, thus in the vehicle longitudinal direction X and in the vehicle transverse direction Y.

[0051] Figure 2 Shown along Figure 1 11-11. The lower floor 1 is arranged below the battery compartment 6. A cross-sectional hollow profile 8 is arranged on the inner side 7. A deformation 3 with an outwardly flared wall 9 and a flange 10 protruding in the transverse direction Y of the vehicle are formed on the respective opposite sides. A vehicle door sill 11 is connected to the flange 10, for example.

[0052] Figure 3 An alternative design variant is shown. On the side of the lower floor panel 1, the wall 9 similarly forms the inner part of the rocker shell. Here, the outer rocker panel 12 is welded, so that a motor vehicle rocker is provided in cross section. This again saves spare parts and similarly increases the geometric accuracy. For example, a battery compartment 6 can be inserted into the lower floor panel 1.

[0053] Figure 4 a and Figure 4 b shows a top view and a cross-sectional view. It can be seen that the side walls 9 are each bent over on opposite sides in the transverse direction Y of the vehicle and are additionally formed again with flanges that are tilted upwards.

[0054] according to Figure 5 a and Figure 5 b, the corresponding longitudinal strip 13 is designed as a soft zone. This longitudinal strip 13 extends over the entire length of the lower floor 1 in the longitudinal direction X of the vehicle. The longitudinal strip has a reduced strength. For example, a strength of from 550 MPa to 800 MPa. The planar area and the flange are preferably press-hardened and have a tensile strength Rm of more than 1000 MPa.

[0055] Figure 6 a and Figure 6 B shows a similar design variant, wherein the flange 10 is configured as a soft zone, wherein the soft zone or the transition zone to the high-strength zone can also extend into the edge region. Here, for example, tearing can be avoided in a collision situation by connection with another welded component.

[0056] Figure 7 a and Figure 7 b shows another design variant. Here, oval soft areas 14 are formed together as so-called soft areas in the surface area of ​​the lower floor 1. The advantage of this local soft area is that it ensures particularly good protection against puncture and seating from stone impacts from the roadway without causing a risk of fracture in the high-strength connection area to the vehicle body (at the bolt points). These oval areas 14 then have a tensile strength of preferably less than 1000 MPa. As a result, local soft areas can be formed in the lower floor 1. Between them, sections of the type of crossbeam and longitudinal beam are then generated in the transverse direction Y of the vehicle and in the longitudinal direction X of the vehicle with a tensile strength of more than 1000 MPa, thereby providing sufficient rigidity.

[0057] Figure 8 a and Figure 8 b shows Figure 7 a and Figure 7 b A similar embodiment variant, in which the oval region is significantly larger here, so that two regions are formed. Thus, for a vehicle that is too deep, a soft region is formed for each of the two front seats and the rear seat in the longitudinal direction X of the vehicle. Figure 7 In the case of a, different soft areas are constructed for the two front seat areas and for the two rear seat areas, respectively. For example, when connected to the seat rails, the soft areas can prevent the seat rails from detaching in the event of a crash.

[0058] Fig. 9 a and Fig. 9 b shows another design variant of the lower floor 1 according to the invention. The lower floor is protected from below in the longitudinal direction X of the vehicle just in the area of ​​the front side 4 and the back side 5 of the lower floor 1 in the length region of a vehicle axle not shown in detail, for example an axle subframe, with respect to the vertical direction of the vehicle. In addition, reinforcement beads 15 are formed in the lower floor 1. These reinforcement beads 15 then extend in the transverse direction Y of the vehicle and in the longitudinal direction X of the vehicle. However, the reinforcement beads 15 can also be formed in an X-shaped manner and intersect themselves in their extension. Thus, for example, the area of ​​the corresponding vehicle axle is shown on the left and right with respect to the plane of the figure.

[0059] The individual exemplary embodiments described above may have their individual features combined with one another as desired, together with the respectively attendant advantages, without departing from the scope of the present invention.

[0060] The steel types used can be used as examples for all the variants of the invention below. In particular, different types of steel can be combined with one another in tailored blanks. The corresponding strength ranges for hard or soft areas or strong or ductile areas can be derived from the table. All alloy components are given in % by weight, with residual iron and impurities caused by melting being added to the corresponding hardenable steel alloy.

[0061]

Claims

1. A lower floor panel (1) of a motor vehicle, comprising a flat bottom (2) and a deformation portion (3) in the form of at least one flange (10) on two longitudinal sides lying opposite each other in the transverse direction of the motor vehicle, the lower floor panel (1) extending between a front axle and a rear axle of the motor vehicle, wherein: The lower base plate (1) is thermally deformed and press-hardened as a one-piece sheet metal deformation component in one press stroke, wherein regions with different tensile strengths Rm and / or wall thicknesses are constructed, characterized in that there is an outwardly protruding flange (10) with bolt holes as tightening points to the motor vehicle body, and the flange (10) is constructed to be soft and has a tensile strength Rm of less than 1000 MPa.

2. A lower floor panel (1) of a motor vehicle, the lower floor panel having a flat bottom (2) and a deformation portion (3) in the form of at least one flange (10) on two longitudinal sides lying opposite each other in the transverse direction of the motor vehicle, the lower floor panel (1) extending between a front axle and a rear axle of the motor vehicle, the lower floor panel (1) being arranged below the vehicle body floor, and the lower floor panel (1) being a one-piece sheet metal deformation component which is thermally deformed and press-hardened in one press stroke, wherein: The invention relates to a vehicle having regions with different tensile strengths Rm and / or wall thicknesses, characterized in that in at least one outer side region relative to the transverse direction (Y) of the vehicle, a soft longitudinal strip (13) extending in the longitudinal direction (X) of the vehicle is respectively constructed, and having a tensile strength Rm of less than 1000 MPa.

3. The lower base plate (1) according to claim 1, characterized in that: The high-strength region has a tensile strength of 1350 MPa or more.

4. The lower base plate (1) according to any one of the preceding claims, characterized in that A soft region is formed which has a tensile strength Rm of less than 850 MPa.

5. The lower base plate (1) according to any one of the preceding claims, characterized in that The outer side of the lower floor panel (1) in the transverse direction (Y) of the vehicle is configured as an inner rocker shell, or a rocker inner reinforcement which can be arranged between the inner rocker shell and the outer rocker shell.

6. The lower base plate (1) according to any one of claims 1 or 3-5, characterized in that: In at least one outer side region, with respect to the vehicle transverse direction (Y), a soft longitudinal strip (13) extending in the vehicle longitudinal direction (X) is formed with a tensile strength of less than 1000 MPa.

7. The lower base plate (1) according to any one of the preceding claims, characterized in that The lower floor panel (1) extends in the longitudinal direction of the motor vehicle to below at least a central longitudinal section of the front axle and / or to below at least a central longitudinal section of the rear axle.

8. The lower base plate (1) according to any one of the preceding claims, characterized in that A reinforcing bead (15) is formed in the lower base plate (1).

9. The lower base plate (1) according to any one of claims 2 to 8, characterized in that: The deformation portion (3) has a flange (10) protruding outward.

10. The lower base plate (1) according to any one of claims 2 to 9, characterized in that: The flange (10) protruding outward is designed to be soft.

11. The lower base plate (1) according to any one of the preceding claims, characterized in that A hollow profile (8) is used on the inner side of the deformation portion (3), in particular as a battery protection structure.

12. The lower base plate (1) according to any one of the preceding claims, characterized in that Use tailor-welded blanks.

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