Vehicle floor panel reinforcement element

Abstract

FIELD: floor panel reinforced element.SUBSTANCE: reinforcing element (1) of a floor panel for a motor vehicle (100), attached to a floor panel (3) and comprising at least: a longitudinal section (11) extending substantially in the longitudinal direction from the instrument panel (4) to the transition section (31) and forming with said floor panel (3) a front hollow space (10) in the longitudinal direction, a front transverse section (21) extending substantially in the transverse direction between the right and left side parts (61, 62) of the lower frame rails of the body of said vehicle and forming with said floor panel (3) a front hollow space (20) in the transverse direction and connected to said front longitudinal section (11) in the front transition section (31), wherein said reinforcing element (1) of the floor panel is made by molding a solid metal blank (7).EFFECT: improved performance during a collision and a reduction in the weight of the floor structure.7 cl, 9 dwg

Description

[0001] The invention relates to structural parts for a vehicle and, in particular, to a reinforcing structure of a vehicle floor panel.

[0002] Vehicle manufacturers are facing increasing demands to improve vehicle passive safety, reduce vehicle weight to minimize greenhouse gas emissions in the case of internal combustion engines, or increase driving range in the case of electric vehicles, while maintaining low production costs and high productivity.

[0003] The floor panel reinforcement is a key structural component of a vehicle, contributing to occupant safety in the event of a frontal or side collision. It also plays an important role in protecting the battery or high-voltage battery and its housing (high-voltage battery housing) in electric or hybrid vehicles, or the hydrogen fuel tank in fuel cell vehicles. When a vehicle is subjected to a frontal collision, the longitudinal members of the floor panel reinforcement capture the impact energy transmitted by the frontal impact control system, absorbing part of the impact energy and preventing it from penetrating into the passenger compartment.Similarly, the floor panel reinforcement cross members capture impact energy transmitted by the body's lower side members, absorbing and preventing impact energy penetration. Furthermore, the floor panel reinforcement plays a significant role in ensuring the overall rigidity of the vehicle body.

[0004] To improve the safety performance of the vehicle, the floor panel reinforcement is used in a number of regulatory tests, such as:

[0005] - Small Overlap Rigid Barrier Impact (SORB) test developed by the Insurance Institute for Highway Safety (IIHS), in which a vehicle is subjected to a 25% width overlap impact with a rigid barrier traveling at 40 mph (64.4 km / h),

[0006] - IIHS Overlap Deformable Barrier (ODB) Frontal Impact Test, which involves a vehicle being impacted with only a 25% width overlap by a deformable barrier traveling at 40 mph (64.4 km / h),

[0007] - The US New Car Assessment Program (USNCAP) fixed pole impact test, in which a vehicle traveling at an initial lateral speed of 32.2 km / h (20.7 mph) is subjected to a side impact with a fixed pole,

[0008] - Moving Deformable Barrier (MDB) side impact tests, in which the vehicle is side-impacted with a 1500 kg deformable barrier moving at 50 km / h.

[0009] The object of the invention is to provide a floor panel reinforcement element that exhibits exceptional crash performance. Another object of the invention is to provide a vehicle with a floor panel reinforcement element according to the invention.

[0010] An object of the invention is also to provide a floor panel reinforcing element that is lighter in weight than known designs, thereby providing fuel savings in the case of internal combustion engines and a longer driving range in the case of electric motor-driven vehicles.

[0011] Furthermore, the invention addresses the challenges of increasing productivity, simplifying design, and reducing costs in vehicle manufacturing. The invention essentially proposes a floor panel reinforcement element containing fewer parts than standard designs. The innovative design can be manufactured and assembled in very few steps compared to standard designs. Along with simplifying manufacturing, the reduction in the number of production steps also reduces the environmental impact of the production process and the overall CO2 emissions of vehicle manufacturing.

[0012] The objective of the invention is achieved by a reinforcing element for a floor panel as defined in claim 1, optionally comprising the features of claims 2-6, taken individually or in any possible combination. Another objective of the invention is achieved by a motor vehicle as defined in claim 7.

[0013] In the following description and claims, terms indicating location and direction are defined according to generally accepted directions for the assembled vehicle.

[0014] In particular, the terms "top", "up", "upper", "above", "lower", "below", "under", etc. are defined according to the direction of the height of the vehicle. The terms "front", "rear", "forward", "backward", etc. are defined according to the longitudinal direction of the vehicle, i.e. the direction in which the vehicle moves in a straight line. The terms "left", "right", "lateral", etc. are defined according to the orientation parallel to the width of the vehicle. The terms "inner" and "outer" are defined according to the direction of the width of the vehicle: "inner" means closest to the central axis of the vehicle, i.e. closest to the inner side of the vehicle, while "outer" means located at a distance from the said central axis of the vehicle, in fact, near the outer side of the vehicle.The same applies to the terms "outer" and "center": the "outer" portion is located closest to the vehicle's outer edge, and the "center" portion is located closest to the vehicle's center. The term "horizontal" refers to the orientation of a plane containing the longitudinal and transverse directions. The term "vertical" refers to the orientation containing the vertical direction.

[0015] In the drawings shown, orientations and spatial references are represented using X, Y, and Z coordinates, where Z is the vehicle's vertical direction, X is the vehicle's longitudinal direction, and Y is the vehicle's transverse direction. This applies to each figure. When a figure is two-dimensional, the axis located outside the figure is indicated by a dot within a circle when it points toward the reader, and by a cross within a circle when it points away from the reader, according to generally accepted conventions.

[0016] The expressions "substantially parallel" and "substantially perpendicular" mean a direction which may deviate from the parallel or perpendicular direction by no more than 15°.

[0017] The term "steel sheet" refers to a flat sheet of steel. It has a front and back surface, also referred to as the top and bottom surfaces or the upper and lower surfaces. The distance between these surfaces is called the sheet thickness. Thickness can be measured, for example, with a micrometer, the micrometer's pin and anvil are placed on the front and back surfaces. The thickness of a molded part can be measured in a similar manner.

[0018] The average thickness of a part or section of a part means the total average thickness of the material from which the part is made after it has been formed into a three-dimensional part from the original flat sheet.

[0019] Pattern welded blanks are manufactured by assembling, for example by laser welding, multiple sheets or cut blanks of steel, known as sub-blanks, together to optimize the performance of the part at various locations, reduce the overall weight of the part, and reduce the overall cost of the part. Sub-blanks that form pattern welded blanks can be assembled with or without overlap, for example, they can be laser butt welded together (without overlap) or resistance spot welded (with overlap).

[0020] Unlike a pattern-welded blank, a solid blank is a blank that consists of one separate auxiliary blank without multiple auxiliary blanks combined with each other.

[0021] Rolled specially designed blank is a blank having multiple sheet thicknesses obtained through the rolling operation in the steel sheet manufacturing process.

[0022] Tensile strength, yield strength, and elongation are measured according to ISO 6892-1, published in October 2009. Tensile test specimens are cut from flat sections. If necessary, small tensile test specimens are used to test the entire flat section of the part.

[0023] The bending angle is measured according to the VDA-238 bending standard. For the same material, the bending angle depends on the thickness. For a better understanding, the bending angle values ​​​​in the present invention are described for a thickness of 1.5 mm. If the thickness is not equal to 1.5 mm, the bending angle value should be converted to a thickness of 1.5 mm using the following expression, where α1.5 is the bending angle converted to a thickness of 1.5 mm, t is the thickness, and αt is the bending angle for thickness t:

[0024] α1.5 = (αt × √t) / √1.5

[0025] Hot stamping is a steel forming process that involves heating a steel blank or a preformed part made from a steel blank to a temperature at which the microstructure of the steel at least partially transforms to austenite, forming the blank or preformed part at high temperature by stamping it, and simultaneously quenching the formed part to obtain a microstructure having very high strength, with a possible additional redistribution or tempering step during heat treatment.

[0026] A multi-stage hot stamping process is a specific type of hot stamping process that includes at least one stamping step and consists of at least two processing steps performed at a high temperature above 300°C. For example, a multi-stage process may include an initial stamping operation and a subsequent hot trimming operation, so that the finished part exiting the hot stamping operation does not require subsequent trimming. For example, a multi-stage process may include multiple sequential stamping steps to produce parts with more complex shapes that could otherwise be achieved with a single stamping operation. For example, in a multi-stage process, parts are automatically transferred from one operation to another, such as using a transfer press.For example, the parts remain in the same tool, which is a universal tool and can perform various operations such as the first stamping operation and the subsequent trimming operation in the tool.

[0027] The term "local longitudinal deformation" refers to the deformation mode of a part, typically a highly compliant part, that is subjected to a compressive load and gradually absorbs the mechanical energy of the compressive load by forming a series of corrugations through successive longitudinal deformations of the part. As a result, the length of the part measured in the direction of the compressive load after deformation becomes shorter than the original length of the part in the specified direction. In other words, when a part responds to a compressive load through longitudinal bending, it folds upon itself, similar to a plastic bottle with a compressive load applied between the top and bottom.

[0028] Fig. 1 shows a perspective view of a vehicle comprising a floor panel reinforcing element according to the invention;

[0029] Fig. 2 – the first embodiment of the reinforcing element of the floor panel according to the invention, perspective view;

[0030] in Fig. 3 – a second embodiment of a reinforcing element of a floor panel according to the invention, a perspective view;

[0031] Fig. 4 – a third embodiment of a reinforcing element of a floor panel according to the invention, a perspective view;

[0032] Fig. 5 – a fourth embodiment of a reinforcing element of a floor panel according to the invention, perspective view;

[0033] Fig. 6 – a fifth embodiment of a reinforcing element of a floor panel according to the invention, a perspective view;

[0034] in Fig. 7 – a metal blank used for the production of a reinforcing element of a floor panel according to the invention, perspective view;

[0035] in Fig. 8A – a reinforcing element of the floor panel according to the first embodiment in Fig. 1, top view; and

[0036] in Fig. 8B is a section along the axis AA shown in Fig. 8A.

[0037] It should be noted that, compared with the original computer simulation of the reinforcing element of the floor panel used for the first embodiment, the section in Fig. 8B is specially extended in the vertical direction to more clearly depict the height of the side wall H 20 .

[0038] For clarity, Figs. 2-6 show the floor panel reinforcement elements separately from the surrounding vehicle components. However, below, the elements in the figures are described in their assembled state within the vehicle structure.

[0039] With reference to Fig. 1, the passenger compartment 101 of the automobile 100 is a space for the passengers of the vehicle. For obvious safety reasons, said passenger compartment 101 of the automobile must be protected in the event of a traffic accident. The lower part of the passenger compartment of the automobile is limited by a floor panel 3, which extends in the longitudinal direction from the instrument panel 4 in the front part to the inclined board 5 in the rear part. The floor panel 3 additionally extends in the transverse direction between the right and left side portions 61, 62 of the lower body rails. In the case of an electric vehicle, the high-voltage battery housing is generally located below the floor panel 3.

[0040] The reinforcing element 1 of the floor panel according to the invention is located on top of said floor panel 3 and comprises side walls that extend at least in the vertical direction from a base height corresponding to the height of the floor panel 3 to a greater height above the floor panel 3. The expression "the side walls extend at least in the vertical direction" means that the direction in which the side walls extend contains at least a vertical component, but also contains a longitudinal and / or transverse component. In other words, the side walls extend in the vertical direction, possibly at an angle to the vertical direction.

[0041] The reinforcing element 1 of the floor panel extends in the longitudinal direction from the instrument panel 4 to the rear of the vehicle. In the transverse direction, the reinforcing element 1 of the floor panel extends between the right and left side portions 61, 62 of the lower body rails. As described below, according to a specific embodiment, the reinforcing element 1 of the floor panel can extend in the longitudinal direction to the rear of the vehicle up to the inclined board 5, and it can also extend in the longitudinal direction only to a place located in front of the inclined board 5. On the other hand, the reinforcing element 1 of the floor panel according to the invention necessarily extends in the transverse direction between the right and left side portions 61, 62 of the lower body rails.

[0042] With reference to Fig. 2, the reinforcing element 1 of the floor panel according to the invention comprises at least a front longitudinal section 11, a front transverse section 21 and a front transition section 31. In the assembled state in the vehicle, said front longitudinal section 11 extends substantially in the longitudinal direction from the instrument panel 4 to the front transition section 31. In the assembled state in the vehicle, said front transverse section 21 extends substantially in the transverse direction between the right and left side portions 61, 62 of the lower body rails. The front transition section 31 provides a transition in orientation between the front longitudinal section 11, which extends in the longitudinal direction, and the front transverse section 21, which extends substantially in the transverse direction. For this purpose, the side walls of the front transition section 31 are curved.

[0043] Referring to Fig. 2 and 8A, the curvature of said side walls of the transition section 31 is measured by the radius of curvature R1, R2 for the right and left side walls, respectively. Said radius of curvature R1, R2 is defined as the radius of the circle, the arc of which most closely approximates the curvilinear shape of the side walls of the transition section 31. Said circles, designated in Fig. 8A as C1 and C2, correspond to the right-hand and left-hand radii of curvature R1, R2.

[0044] In the assembled state in the vehicle, the reinforcing element 1 of the floor panel is at least attached to the floor panel 3, for example, by spot welding on the shelves or laser welding on the shelves, for example, remote laser welding or remote intermittent laser welding. In a particular embodiment, the reinforcing element 1 of the floor panel is also attached to the instrument panel 4. Due to the fact that the side walls extend at least in the vertical direction, the assembled reinforcing element 1 of the floor panel forms with the floor panel 3 a front longitudinal hollow space 10 in the longitudinal direction and a front transverse hollow space 20 in the transverse direction. The said front longitudinal hollow space 10 extends, essentially, in the longitudinal direction from the instrument panel 4 to the front transition section 31.Said transverse hollow space 20 extends substantially in the transverse direction between the right and left side portions 61, 62 of the lower body frame rails. The front longitudinal and transverse hollow spaces 10, 20 are connected in the front transition section 31.

[0045] The front longitudinal and transverse cavities 10 and 20 play a significant role in counteracting impact energy, absorbing impact energy and increasing the overall rigidity of the vehicle. In fact, it is the presence of these cavities that ensures the overall inertia and, thus, the vehicle's structural resistance.

[0046] The reinforcing element of the floor panel according to the invention is manufactured by molding a solid metal blank to give it the desired shape of the finished part. The molding is accomplished, for example, by stamping the metal blank. For example, this operation is hot stamping or a multi-stage hot stamping operation.

[0047] An example of such a solid metal blank 7 is shown in Fig. 7. The blank shown corresponds to the blank that is used to manufacture the reinforcing element 1 of the floor panel from Fig. 3.

[0048] For example, a solid metal workpiece is a workpiece welded by laser welding from several sub-workpieces joined by laser butt welding, spot welding, or a combination of both. For example, a solid metal workpiece is a rolled, specially designed workpiece.

[0049] Because the floor panel reinforcement is machined from a single, solid metal blank, the manufacturing process is significantly simplified compared to traditional designs, in which multiple parts are machined from several different blanks and then joined together. This simplified manufacturing process increases productivity and reduces costs during vehicle production. By reducing logistics and manufacturing complexity, this simplified manufacturing process also contributes to lower CO2 emissions during vehicle production.

[0050] Another advantage of combining longitudinal and transverse elements into a single, integral part machined from a single blank is the elimination of assembly points, which can cause structural weaknesses. In fact, since the part is a stand-alone component, it contains no assembly points between individual sub-components, which can be a potential source of structural weakness. For example, when welding individual parts of a traditional multi-component structure, heat-affected zones created during the welding operation, or the weld points themselves, can weaken the assembly, leading to failure in the event of a collision, fatigue stress, or other factors. Furthermore, the absence of assembly points also ensures optimal interaction between the various reinforcing structural elements.For example, when the part is subjected to longitudinal stresses in the event of a frontal collision, the front longitudinal section 11 contributes significantly to counteracting and absorbing the impact energy, and also relies on the front transverse section 21 to counteract and absorb part of the impact energy and direct said impact energy in the transverse direction, so that as much of the structure as possible counteracts the absorption of the impact energy.

[0051] Furthermore, the absence of assembly points between multiple individual parts reduces overall weight. In fact, assembling multiple parts requires overlapping areas where two thicknesses of metal overlap, leading to increased weight compared to a single, integrated structure.

[0052] In the specific example shown in Fig. 2, the front longitudinal section 11 comprises a front longitudinal rib 12 located at the top of said longitudinal section. Said rib 12 increases the rigidity and, thus, the crash resistance and rigidity characteristics of said front longitudinal section 11.

[0053] In the specific embodiment shown in Fig. 2, the front transverse section 21 comprises a front longitudinal rib 22 located at the top of said transverse section. Said rib 22 increases the rigidity and, thus, the crash resistance and rigidity characteristics of said front transverse section 21.

[0054] In a specific embodiment, a specific ratio limit is set between the radii of curvature of the side wall in the transition portion 31 and the height of the side wall in the transition portion 31. More specifically, with reference to Figs. 8A and 8B, the dimensions H1 and H2 are the heights of the right and left side walls of the transition portion 31, respectively, at the point where the side wall forms an angle of 20° with the transverse direction. In Figs. 8A and 8B, the points at which the right and left side walls form an angle of 20° with the transverse direction are respectively designated as A1 and A2.

[0055] If the structure of the reinforcing element of the floor panel provides several individual front longitudinal sections 11, and thus several front transition sections 31, as shown in Fig. 3, it is necessary to take into account the role of each of these transition sections 31 in setting the above-mentioned limit of the ratios.

[0056] The number n of the front longitudinal sections 11 is an integer equal to or greater than 1, based on the number of individual front longitudinal sections 11 in the reinforcing element of the floor panel. For example, in Fig. 2, the number n = 1, while in Fig. 3, the number n = 2.

[0057] In a specific embodiment, the product of the number n of individual front longitudinal sections 11 by the ratio of the sum of the radii R1, R2 of curvature of the side walls of the transition section to the sum of the heights H1, H2 of the side walls of the transition section is at least equal to 4. This can be expressed by the following formula:

[0058]

[0059] The inventors have found that crash safety, particularly resistance to side impact crashes, is improved by ensuring a minimal ratio between the curvature of the sidewalls in the transition sections and the height of the sidewall of the transition section adjacent to the transition section. In fact, during a side impact, the sidewalls of the front transverse section absorb and resist the compressive load during a crash. The curvature of the sidewalls in the transition sections 31 potentially weakens the said compressive load, at which stress concentration can lead to crushing. The inventors have found that by ensuring the above-mentioned ratio, excellent transverse dynamic loading characteristics of the reinforcing element of the floor panel can be achieved.

[0060] For example, the inventors found that very good side impact performance was achieved by using the following floor panel reinforcements:

[0061] Example 1 (see Fig. 2) Example 2 (see Fig. 3) First transition section R1 (mm) 144 76 R2 (mm) 144 64 H1 (mm) 32 34 H2 (mm) 32 34 Second transition section R1 (mm) - 76 R2 (mm) 63 H1 (mm) 34 H2 (mm) 34 n 1 2 4,5 4,1

[0062] In a specific embodiment, the front longitudinal section 11 also comprises a deformable section extending along the front portion of said front longitudinal section 11, and a non-deformable section extending along the rear portion of said section 11. The plastic deformation resistance of the deformable section is lower than the plastic deformation resistance of the non-deformable section. For example, the product of the tensile strength by the average thickness of said deformable section is less than the product of the tensile strength by the average thickness of said non-deformable section. Advantageously, in the event of a frontal impact, this makes it possible to manufacture the reinforcing element 1 of the floor panel comprising a front portion corresponding to the deformable section, which is subject to plastic deformation, for example, local longitudinal deformations, thereby absorbing part of the impact energy. At the same time, the non-deformable section located on the rear side, i.e.closest to the vehicle occupants will resist energy penetration, thereby protecting the occupants and the high voltage battery housing while transferring the remaining impact energy to the rest of the vehicle structure.

[0063] In a specific embodiment, the front transverse section 21 also comprises a deformable section extending along the distal portion of said front transverse section and a non-deformable section extending along the central portion of said section. In a specific embodiment, the deformable sections are located on both sides of the front transverse section. The plastic deformation resistance of said deformable section is less than the plastic deformation resistance of said non-deformable section. For example, the product of the tensile strength and the average thickness of said deformable section is less than the product of the tensile strength and the average thickness of said non-deformable section.Advantageously, in the event of a side impact, this allows the reinforcing element 1 of the floor panel to be manufactured with a rear portion corresponding to the deformable area, which undergoes plastic deformation, such as localized longitudinal deformation, thereby absorbing some of the impact energy. At the same time, the non-deformable portion located toward the center, i.e., closest to the vehicle occupants, will resist energy penetration, thereby protecting the occupants and the high-voltage battery housing, while transferring the remaining impact energy to the rest of the vehicle structure.

[0064] In a specific embodiment, the above-described deformable and non-deformable sections are obtained by manufacturing a reinforcing element of the floor panel using a laser-welded blank that contains a material that, after molding, has a lower resistance to plastic deformation in the deformable sections than in the non-deformable sections.

[0065] In the specific embodiment shown in Fig. 2, the reinforcing element 1 of the floor panel consists of only a front longitudinal section 11 and a front transverse section 21. For example, the front longitudinal section is located centrally, for example, aligned with the center of the instrument panel 4. For example, the front longitudinal section replaces an element better known as a tunnel reinforcing element. For example, the front transverse section replaces the floor crossbar under the front seat.

[0066] In the specific embodiment shown in Fig. 3, the reinforcing element 1 of the floor panel consists of only two front longitudinal sections 11 and a front transverse section 21. For example, the front longitudinal sections are located in the direction of the side of the floor panel reinforcement, for example, aligned with the front longitudinal elements located at the front end of the vehicle (not shown in the figures).

[0067] In the specific embodiment shown in Fig. 3, the reinforcing element 1 of the floor panel comprises two front longitudinal sections 11 and a front transverse section 21. For example, the front longitudinal sections are located in the direction of the side of the floor panel reinforcement, for example aligned with the front longitudinal elements located at the front end of the vehicle (not shown in the figures).

[0068] In the specific embodiment shown in Fig. 3 and 4, the reinforcing element 1 of the floor panel comprises a front transverse section 21 and at least another transverse section 22 extending substantially in the transverse direction between the side portions 61, 62 of the lower body rails and having side walls extending at least in the vertical direction, so that said transverse section 22 forms a hollow space in the transverse direction with the floor panel 3. As an advantage, this allows the transverse elements to be integrated into the reinforcing element of the floor panel, using the above-described advantages of simplifying the manufacture and optimizing the design.

[0069] In a specific embodiment, the reinforcing element 1 of the floor panel comprises an additional transverse section 22 having a deformable section extending along the distal portion of said additional transverse section and a non-deformable section extending along the central portion of said section. In a specific embodiment, the deformable sections are located on both sides of the additional transverse section. The plastic deformation resistance of said deformable section is less than the plastic deformation resistance of said non-deformable section. For example, the product of the tensile strength and the average thickness of said deformable section is less than the product of the tensile strength and the average thickness of said non-deformable section.Advantageously, in the event of a frontal impact, this allows the reinforcing element 1 of the floor panel to be manufactured with a rear portion corresponding to the deformable area, which undergoes plastic deformation, such as localized longitudinal deformation, thereby absorbing some of the impact energy. At the same time, the non-deformable portion, located centrally, i.e., closest to the vehicle occupants, will resist energy penetration, thereby protecting occupants and the high-voltage battery housing, while transferring the remaining impact energy to the rest of the vehicle structure.By combining this embodiment with the above-described embodiment, in which the front transverse section 21 also comprises a distal portion having a deformable section, the deformable sections of the front transverse section 21 and one or more additional transverse sections 22 can interact to absorb energy in the event of a side impact, and the non-deformable sections interact to resist energy penetration.

[0070] In the specific embodiment shown in Fig. 3, the additional transverse section 22 is attached to the reinforcing element of the floor panel by means of lateral intermediate sections 23, which extend substantially in the longitudinal direction between the sides of the transverse sections. This design allows for the easy integration of the reinforcing element of the floor panel into the vehicle during its assembly and ensures a very high structural strength of the reinforcing element 1 of the floor panel. The presence of two lateral intermediate sections 23 further increases the strength of the floor panel assembly and its contribution to ensuring the rigidity of the vehicle body.

[0071] In the specific embodiment shown in Fig. 4, the additional transverse section 22 is attached to the reinforcing element of the floor panel via a central intermediate section 24. For example, said central intermediate section 24 comprises side walls extending at least in the vertical direction and forming an additional hollow space in the longitudinal direction with the floor panel 3. Advantageously, this allows for an increased load transfer path of the front longitudinal section, thereby increasing frontal impact resistance. This also improves the overall rigidity characteristics of the vehicle.

[0072] In the specific embodiment shown in Fig. 5, the reinforcing element of the floor panel comprises two additional cross members 22, each of which is attached to the reinforcing element 1 of the floor panel by means of a central intermediate section 24. In the specific embodiment shown in Fig. 5, the reinforcing element 1 of the floor panel also comprises an inclined board 5. This design makes it possible to obtain a very large reinforcing element of the floor panel, thereby providing additional advantages of the above-described effects of combining parts.

[0073] In the specific embodiment shown in Fig. 6, the reinforcing element of the floor panel comprises two additional cross members 22, directly attached to each other and to the front cross section 21. This makes it possible to obtain a very strong, compact and rigid structure.

[0074] In the specific embodiment shown in Fig. 7, the metal blank 7 used to manufacture the reinforcing element 1 of the floor panel also comprises overlays 8 to locally increase the thickness and, therefore, the structural strength of the part. The overlays are manufactured by attaching an additional, smaller metal blank on top of the original metal blank, for example, using spot welding or laser welding.

[0075] In a particular embodiment, the reinforcing element of the floor panel is manufactured by hot stamping, and the blanks used to manufacture it comprise one or more of the following materials, either in the form of solid blanks or combined in the form of welded composite blanks:

[0076] - steel having the following composition in mass%: 0.06% ≤ C ≤ 0.1%, 1% ≤ Mn ≤ 2%, Si ≤ 0.5%, AI ≤ 0.1%, 0.02% ≤ Cr ≤ 0.1%, 0.02% ≤ Nb ≤ 0.1%, 0.0003% ≤ B ≤ 0.01%, N ≤ 0.01%, S ≤ 0.003%, P ≤ 0.020%, less than 0.1% Cu, Ni and Mo, the rest is iron and inevitable impurities resulting from the production process. Due to this compositional range, the yield strength of the corresponding zone after hot stamping is 700–950 MPa, the tensile strength is 950–1200 MPa, and the bending angle is greater than 75°. For example, this material is used in deformable sections of the reinforcing element of the floor panel, since its large bending angle, combined with its high mechanical properties, allows it to absorb a large amount of impact energy, for example, due to localized longitudinal deformations;

[0077] - steel with a tensile strength after hot stamping of 1300–1650 MPa and a yield strength of 950–1250 MPa;

[0078] - steel with a tensile strength after hot stamping of 1300–1650 MPa, a yield strength of 950–1250 MPa and a bending angle greater than 75°;

[0079] - steel having the following composition in mass%: 0.020% ≤ C ≤ 0.25%, 1.1% ≤ Mn ≤ 1.4%, 0.15% ≤ Si ≤ 0.35%, Cr ≤ 0.30%, 0.020% ≤ Ti ≤ 0.060%, 0.020% ≤ Al ≤ 0.060%, S ≤ 0.005%, P ≤ 0.025%, 0.002% ≤ B ≤ 0.004%, the rest is iron and inevitable impurities resulting from the production process. Due to this composition range, the tensile strength of the corresponding part zone after hot stamping is 1300–1650 MPa, and the yield strength is 950–1250 MPa. For example, this steel composition is used in the non-deformable section of the floor panel reinforcement, as it prevents the penetration of impact energy due to its high mechanical properties;

[0080] - steel with a tensile strength after hardening under press above 1800 MPa;

[0081] - steel having the following composition in % by mass: 0.024% ≤ C ≤ 0.38%, 0.40% ≤ Mn ≤ 3%, 0.10% ≤ Si ≤ 0.70%, 0.015% ≤ Al ≤ 0.070%, Cr ≤ 2%, 0.25% ≤ Ni ≤ 2%, 0.015% ≤ Ti ≤ 0.10%, Nb ≤ 0.060%, 0.0005% ≤ B ≤ 0.0040%, 0.003% ≤ N ≤ 0.010%, S ≤ 0.005%, P ≤ 0.025%, the remainder being iron and unavoidable impurities from the manufacturing process. This compositional range results in a tensile strength of over 1800 MPa in the corresponding area of ​​the floor panel reinforcement after hot stamping. For example, this material is used in the non-deformable zone;

[0082] - steel having the following composition in mass%: C: 0.15-0.25%, Mn: 0.5-1.8%, Si: 0.1-1.25%, Al: 0.01-0.1%, Cr: 0.1-1.0%, Ti: 0.01-0.1%, B: 0.001-0.004%, P ≤ 0.020%, S ≤ 0.010%, N ≤ 0.010% and containing, if necessary, one or more of the following elements in mass%: Mo ≤ 0.40%, Nb ≤ 0.08%, Ca ≤ 0.1%, the rest is iron and unavoidable impurities resulting from melting. Due to this composition range, the tensile strength of the corresponding area of ​​the reinforcing element of the floor panel after hot stamping is above 1350 MPa, and the bending angle is more than 70°;

[0083] - steel having the following composition in % by mass: C: 0.26 - 0.40%, Mn: 0.5 - 1.8%, Si: 0.1 - 1.25%, Al: 0.01 - 0.1%, Cr: 0.1 - 1.0%, Ti: 0.01 - 0.1%, B: 0.001 - 0.004%, P ≤ 0.020%, S ≤ 0.010%, N ≤ 0.010% and containing, if necessary, one or more of the following elements in percentage by mass: Ni ≤ 0.5%, Mo ≤ 0.40%, Nb ≤ 0.08%, Ca ≤ 0.1%, the rest is iron and inevitable impurities as a result of melting. Due to this range of composition, the tensile strength of the corresponding zone of the reinforcing element of the floor panel after hot stamping is above 1500 MPa, and the bending angle is greater than 70°;

[0084] - steel having the following composition in % by mass: C: 0.2 – 0.34%, Mn: 0.50 – 1.24%, Si: 0.5 – 2%, P ≤ 0.020%, S ≤ 0.010%, N ≤ 0.010% and containing, if necessary, one or more of the following elements in percentage by mass: Al ≤ 0.2%, Cr ≤ 0.8%, Nb ≤ 0.06%, Ti ≤ 0.06%, B ≤ 0.005%, Mo ≤ 0.35%, the rest is iron and unavoidable impurities resulting from melting. Due to this composition range, the tensile strength of the corresponding area of ​​the reinforcing element of the floor panel after hot stamping is equal to or higher than 1000 MPa, and the bending angle is greater than 55°;

[0085] - steel having the following composition in % by mass: C: 0.13 – 0.4%, Mn: 0.4 – 4.2%, Si: 0.1 – 2.5%, Cr ≤ 2%, Mo ≤ 0.65%, Nb ≤ 0.1%, Al ≤ 3.0%, Ti ≤ 0.1%, B ≤ 0.005%, P ≤ 0.025%, S ≤ 0.01%, N ≤ 0.01%, Ni ≤ 2.0%, Ca ≤ 0.1%, W ≤ 0.30%, V ≤ 0.1%, Cu ≤ 0.2% and confirming the following combination: 114 – 68*C – 18*Mn + 20*Si - 56*Cr - 60*Ni – 36*Al + 38*Mo + 79*Nb - 17691*B < 20, the rest is iron and unavoidable impurities resulting from melting. For example, this composition is used in hot stamping of a part using a multi-stage process;

[0086] - Steel with an aluminum-based metallic coating applied. The term "aluminum-based" means a coating that contains at least 50% by weight of aluminum. For example, the metallic coating is an aluminum-based coating containing Si in an amount of 8-12% by weight. For example, the metallic coating is applied by immersing the base material in a molten metal bath. Advantageously, applying an aluminum-based metallic coating eliminates the formation of surface scale during the heating stage of the hot stamping process, which, in turn, allows the production of hot stamping parts without the subsequent sandblasting operation. In addition, the aluminum-based coating also provides anti-corrosion protection for the part during vehicle operation;

[0087] - steel with an applied aluminum-based metallic coating containing 2.0–24.0% by weight of zinc, 1.1–12.0% by weight of silicon, optionally 0–8.0% by weight of magnesium, and optionally additional elements selected from Pb, Ni, Zr, or Hf, wherein the mass content of each additional element is less than 0.3% by weight; the rest is aluminum and unavoidable impurities. Advantageously, the metallic coating of this type provides very good anti-corrosion protection for the part, as well as a good surface appearance after hot stamping.

[0088] In a specific embodiment, the reinforcing element of the floor panel is manufactured by hot stamping of a welded blank welded using laser welding and containing at least one auxiliary blank having a metallic coating based on aluminum, and said auxiliary blanks with an aluminum coating are pre-prepared by ablation of at least a portion of the aluminum present in the coating, which would contaminate the weld and degrade its mechanical properties.

[0089] In a specific embodiment, the reinforcing element of the floor panel is manufactured by hot stamping a welded blank welded using laser welding and containing at least one auxiliary blank having at least one side coated with a top layer that increases emissivity. Said top layer that increases emissivity is applied to the uppermost surface of said auxiliary blank. Said top layer that increases emissivity allows for the surface of said auxiliary blank to be obtained, having a higher emissivity compared to the same auxiliary blank that is not coated with a top layer that increases emissivity. Said top layer that increases emissivity can be applied to either the upper or lower side of the auxiliary blank.Said emissivity-enhancing top layer can be applied to both sides of said auxiliary workpiece. If said auxiliary workpiece contains a metallic coating, as described above, the emissivity-enhancing top layer is applied over said metallic coating. In fact, for the emissivity-enhancing top layer, to increase the surface emissivity, it is necessary to coat the outermost surface of the auxiliary workpiece. Advantageously, said emissivity-enhancing top layer increases the heating rate of said auxiliary workpiece and, therefore, improves productivity during the heating stage of the hot stamping process.When using several auxiliary blanks with different thicknesses, the said top layer, which increases the emissivity, is advantageously applied to the auxiliary blanks having the greatest thickness in order to reduce the difference in heating time between the different auxiliary blanks and, therefore, to increase productivity, to increase the process window in the hot stamping process and to obtain, as a result, a finished part having uniform surface properties.

Claims

1. A reinforcing element (1) of a floor panel for a vehicle (100), attached to a floor panel (3) and comprising at least a front longitudinal section (11), a front transverse section (21) and a front transition section (31), so that: each of said front longitudinal section (11), front transverse section (21) and front transition section (31) comprises at least left and right side walls extending from the floor panel (3) at least in the vertical direction to a height exceeding the height of the floor panel (3), said front longitudinal section (11) extends substantially in the longitudinal direction from the instrument panel (4) to the front transition section (31) and forms with said floor panel (3) a front hollow space (10) in the longitudinal direction, said front transverse section (21) extends substantially in the transverse direction between the right and left side parts (61, 62) of the lower body rails of said vehicle and forms with said floor panel (3) a front hollow space (20) in the transverse direction and is connected to said front longitudinal section (11) in a front transition section (31), wherein said reinforcing element (1) of the floor panel is made by molding a solid metal blank (7).

2. A reinforcing element (1) of a floor panel according to claim 1, in which said solid metal blank (7) is a laser-welded blank containing several auxiliary blanks.

3. A reinforcing element (1) of a floor panel according to claim 1 or 2, in which said reinforcing element (1) of the floor panel is manufactured by hot stamping of said solid metal blank (7).

4. A reinforcing element (1) of a floor panel according to any one of paragraphs 1-3, comprising: n separate front longitudinal sections (11) and corresponding front transition sections (31), where n is an integer equal to or greater than 1, for each front transition section (31), right and left side walls, having respectively a radius R1, R2 of curvature and a height H1, H2, defined as the height in the vertical direction of the said right and left side walls of the transition section, at the point where the said side walls form an angle of 20° with the transverse direction, where the product of n by the ratio of the sum of the radii R1, R2 of the curvature of the side walls of the front transverse section to the sum of the heights H1, H2 of the side walls of the front transverse section is at least equal to 4 5. The reinforcing element (1) of the floor panel according to any one of claims 1 to 4, further comprising at least one additional transverse section (22) extending substantially in the transverse direction between the side portions (61, 62) of the lower body rails and having side walls extending at least in the height direction so that the said at least one additional transverse section (22) forms an additional hollow space in the transverse direction with the floor panel (3), wherein the said at least one additional transverse section (22) is attached to the reinforcing element of the floor panel by means of lateral intermediate sections (23) which extend substantially in the longitudinal direction between the side sides of the transverse sections (21, 22).

6. The reinforcing element (1) of the floor panel according to any one of claims 1 to 4, further comprising at least one additional transverse section (22) extending substantially in the transverse direction between the side portions (61, 62) of the lower body rails and having side walls extending at least in the height direction so that the said at least one additional transverse section (22) forms an additional hollow space in the transverse direction with the floor panel (3), wherein the said at least one additional transverse section (22) is attached to the reinforcing element of the floor panel by means of a central intermediate section (24).

7. A vehicle (100) comprising a reinforcing element (1) of a floor panel according to any one of claims 1-6.

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