Vehicle instrument panel assembly

Abstract

An instrument panel assembly (1) for a motor vehicle (100), the instrument panel assembly (1) comprising a lower instrument panel (21) and an upper instrument panel (22), such that:-said lower instrument panel (21) and said upper instrument panel (22) are each manufactured by forming a single metal sheet,-said lower instrument panel (21) further comprises a lower portion (211) and an overlapping portion (212),-said upper instrument panel (22) further comprises an upper portion (221) and an overlapping portion (222), -once assembled to form the dashboard assembly (1), the dashboard lower part (21) and the dashboard upper part (22) overlap each other in respective overlapping portions (212, 222) of the dashboard lower part (21) and the dashboard upper part (22) to form an overlapping portion (12) of the dashboard assembly and do not overlap each other in a lower portion (211) of the lower dashboard and an upper portion (221) of the upper dashboard.

Description

Technical Field

[0001] The present invention relates to structural components for motor vehicles and, in particular, to instrument panel assemblies for vehicles. Background Art

[0002] Automobile manufacturers are facing increasingly demanding requirements. They are required to increase the passive safety of vehicles and at the same time reduce vehicle weight in order to minimize greenhouse gas emissions for internal combustion engines or to increase the vehicle's driving range for electric vehicles. At the same time, vehicle production costs must remain low and productivity must remain high. In addition, automobile manufacturers want to simplify vehicle production by reducing the number of individual components that make up the vehicle.

[0003] The instrument panel assembly separates the front motor compartment from the passenger compartment. It is a large assembly comprising several sub-assemblies, typically about ten individual sub-assemblies. It extends over the entire width of the vehicle and over a substantial part in the height direction. It is involved in absorbing the impact energy and resisting intrusion in the event of a frontal impact or in the event of a side impact. It is an important structural element and a key passenger safety component among the key passenger safety components. It also plays an important role in ensuring the overall rigidity of the body-in-white.

[0004] The instrument panel assembly is involved in improving the safety performance of the vehicle in various regulatory tests such as:

[0005] - The Insurance Institute for Highway Safety (IIHS) Small Overlap Rigid Barrier (SORB) impact, in which a vehicle is struck by a rigid barrier moving at 64.4 km / h with an overlap of only 25% in width.

[0006] - IIHS front overlap deformable barrier (ODB), where the vehicle is impacted by a rigid barrier moving at 64.4 km / h with an overlap of only 40% in width.

[0007] - United States New Car Assessment Program (USNCAP) pole test, in which a vehicle with an initial lateral velocity of 32.2 km / h strikes a fixed pole on its side.

[0008] - The IIHS side movable deformable barrier (MDB) test, in which a vehicle is impacted on its side by a deformable barrier weighing 1500kg and travelling at 50km / h.

[0009] The tests themselves are becoming increasingly rigorous, with higher crash energies and stricter requirements. Summary of the invention

[0010] The object of the present invention is to provide an instrument panel assembly having a very high impact management efficiency. The object of the present invention is also to provide a vehicle having an instrument panel assembly according to the present invention.

[0011] It is also an object of the present invention to provide an instrument panel assembly which has a lower weight than existing designs, thereby saving fuel in the case of an internal combustion engine and increasing the driving range in the case of an electric engine driven vehicle.

[0012] Furthermore, the present invention aims to address the challenges of increasing productivity, reducing complexity and reducing costs in vehicle production. In fact, the present invention provides an instrument panel assembly that has fewer parts compared to a reference design. The design of the present invention can be produced and assembled with very few manufacturing steps compared to the reference. In addition to simplifying production, reducing costs and increasing productivity, reducing the number of production steps also reduces the environmental footprint of the production process and reduces the overall CO2 emissions when manufacturing a vehicle. DETAILED DESCRIPTION

[0013] The object of the invention is achieved by providing an instrument panel assembly according to claim 1 , optionally comprising the features of claims 2 to 4 taken alone or in any possible combination. Another object of the invention is achieved by providing a motor vehicle according to claim 5 .

[0014] In the following description and appended claims, directional terms are defined according to the general orientation of the vehicle in which they are installed.

[0015] In particular, the terms "top", "up", "upper", "above", "bottom", "lower", "lower", "below", etc. are defined according to the height direction of the vehicle. The terms "front", "rear", "rear", "front", "forward", "rearward", etc. are defined according to the longitudinal direction of the vehicle, i.e. the direction in which the vehicle moves when following a straight line. The terms "left", "right", "lateral", etc. are defined according to an orientation parallel to the width of the vehicle. The terms "inside", "outside" should be understood according to the width direction of the vehicle: "inside" is closest to the central axis of the vehicle, i.e. closest to the inside of the vehicle, while "outside" is positioned further away from the central axis of the vehicle, in fact closer to the outside of the vehicle. The same applies to the terms "distal" and "central": the "distal" part is positioned closest to the outside of the vehicle, and the "central" part is positioned closest to the center of the vehicle. The term "horizontal" refers to the orientation of a plane including the longitudinal direction and the transverse direction. The term "vertical" refers to any orientation including the height direction.

[0016] In the following figures, orientation and spatial references are all made using X, Y, Z coordinate references, where Z is the height direction of the vehicle, X is the longitudinal direction of the vehicle, and Y is the lateral direction of the vehicle. References are indicated in each figure. When the figures are 2D plan views, following established convention, an axis outside the figure is indicated by a dot in a circle when it is pointing towards the reader, and by a cross in a circle when it is facing away from the reader.

[0017] The term “substantially parallel” or “substantially perpendicular” means that the direction may deviate from the parallel direction or the perpendicular direction by no more than 15°.

[0018] Steel plate refers to a flat steel plate. The steel plate has a top face and a bottom face, which are also referred to as top side and bottom side or as top surface and bottom surface. The distance between the faces is designated as the thickness of the plate. The thickness can be measured, for example, using a micrometer, the spindle and anvil of which are placed on the top and bottom faces. In a similar manner, the thickness can also be measured on formed parts.

[0019] By average thickness of a component or average thickness of a portion of a component is meant the overall average thickness of the material constituting the component after it has been formed from an initially flat sheet into a three-dimensional component.

[0020] A custom welded blank is made by assembling together, for example by laser welding, several steel plates or cut steel blanks, called sub-blanks, in order to optimize the performance of the component in different areas thereof, thereby reducing the overall component weight and reducing the overall component cost. The sub-blanks forming the custom welded blank can be assembled with or without overlap, for example, the sub-blanks can be laser butt welded (without overlap), or the sub-blanks can be spot welded to each other (with overlap).

[0021] In contrast to a custom welded blank, a monolithic blank refers to a blank comprising one single sub-blank, rather than a blank comprising several sub-blanks combined together.

[0022] The customized rolled blank is a blank having multiple plate thicknesses obtained by differential rolling during the steel plate production process.

[0023] The ultimate tensile strength, yield strength and elongation are measured according to ISO standard ISO 6892-1 published in October 2009. The tensile test specimens are cut from a flat area. If necessary, use undersized tensile test specimens to fit the entire available flat area on the component.

[0024] The bending angle is measured according to the VDA-238 bending standard. For the same material, the bending angle depends on the thickness. For simplicity, the bending angle values ​​of the present invention refer to a thickness of 1.5 mm. If the thickness is different from 1.5 mm, the bending angle values ​​need to be normalized to 1.5 mm by the following calculation, where α1.5 is the bending angle normalized to 1.5 mm, t is the thickness, and αt is the bending angle for thickness t:

[0025] α1.5=(αt×√t) / √1.5

[0026] Hot stamping is a forming technology for steel which involves heating a steel blank or a preformed part made from a steel blank until the microstructure of the steel is at least partially transformed into austenite, forming the blank or preformed part at high temperature by stamping it and simultaneously quenching the formed part to obtain a microstructure with very high strength, possibly with an additional partitioning or tempering step during the heat treatment.

[0027] A multi-step hot stamping process is a specific type of hot stamping process that includes at least one stamping step and includes at least two process steps performed at a high temperature greater than 300°C. For example, a multi-step process may involve a first stamping operation and a subsequent hot trimming operation, so that the finished component at the outlet of the hot stamping process does not require further trimming. For example, a multi-step process may involve several consecutive stamping steps in order to manufacture a component with a more complex shape than can be achieved using a single stamping operation. For example, in a multi-step process, the component is automatically transferred from one operation to another, such as using a transfer press. For example, the component stays in the same tool, which is a multifunctional tool that can perform different operations, such as a first stamping operation and a subsequent in-tool trimming operation.

[0028] - Figure 1 is a perspective view of a motor vehicle highlighting the location of the instrument panel components,

[0029] - Figure 2 is a three-dimensional view of the instrument panel assembly and its surrounding components.

[0030] - Figure 3 is a perspective view of an instrument panel assembly according to the prior art - in this case, the instrument panel assembly is fully assembled,

[0031] - Figure 4 is a perspective view of an instrument panel assembly according to the prior art - in this case the different individual components which are joined together to form the instrument panel assembly have been offset from one another in order to clearly and individually represent each component,

[0032] - Figure 5is a perspective view of an embodiment of an instrument panel assembly according to the invention - in this case the instrument panel assembly is fully assembled,

[0033] - Figure 6 is a perspective view of an embodiment of an instrument panel assembly according to the invention - in this case the different individual components which are joined together to form the instrument panel assembly have been offset from one another in order to clearly and individually represent each component,

[0034] - Fig. 7A is already based on Figure 5 A perspective view of the right-hand side of the instrument panel assembly according to the invention after the left-hand side of the instrument panel has been cut away by the defined AA plane,

[0035] - Figure 7B is based on Figure 5 A schematic cross section of the instrument panel assembly according to the present invention in the defined AA cross-sectional direction,

[0036] - Fig. 8A is a schematic diagram of an embodiment of a custom welded blank for manufacturing an upper instrument panel according to the present invention,

[0037] - Figure 8B is a schematic diagram of an embodiment of a custom welded blank for manufacturing a lower instrument panel according to the present invention,

[0038] - Fig. 9A This is a three-dimensional image simulating the IIHS front overlapping deformable barrier (ODB) impact test at time t=0s, that is, before the barrier is about to hit the vehicle

[0039] - Fig. 9B Means the same thing, but only shows the front motor and instrument panel assembly in order to focus on the interaction between these two elements during the crash test,

[0040] - Fig. 10A , Fig. 10B and Fig.11A , Fig. 11B The evolution of the previously described impact test simulation at t=0.085 s and t=0.105 s, respectively, is shown.

[0041] Reference Figure 1 and Figure 2, the passenger compartment 101 of the motor vehicle 100 is a volume accessible to the occupants of the vehicle. The front motor compartment 102 of the vehicle 100 is a volume located in the front of the vehicle, extending transversely across the width of the vehicle and longitudinally between the front bumper (not shown in the figure) and the passenger compartment 101. Although it is often referred to as the front motor compartment or front engine room, in fact in some vehicles it may not contain an engine or motor (for example, in a vehicle where the engine or motor is at the rear, centrally or directly attached to the wheels). In this case, it can be used as a storage compartment, sometimes called a "front trunk". It is usually closed by a hood on the top (not shown in the figure).

[0042] For obvious safety reasons, the passenger compartment 101 needs to be protected in the event of an impact. The lower part of the passenger compartment is defined by a floor panel 3, which extends transversely between right and left sill beams 6. In the case of an electric vehicle, a high voltage (HV) battery housing is usually located below the floor panel 3.

[0043] The instrument panel assembly 1 is a structural component that defines the passenger compartment 101 at the lower front end of the passenger compartment 101 and separates the passenger compartment 101 from the front motor compartment 102. The instrument panel assembly 1 is also called a firewall or a cowling. It extends in a generally longitudinal and height direction between the floor panel 3 and the windshield (not shown in the figure). There may also be an intermediate portion between the instrument panel assembly 1 and the windshield, such as, for example, an upper cowling portion 4, such as Figure 2 The upper fairing part can be dedicated, for example, to supporting the windshield and / or the hood hinge. In any case, the upper fairing part does not function as a main structural component in the vehicle and in particular does not play a role in the event of a frontal collision, in which elements located inside the front motor compartment are pushed back and hit the dashboard.

[0044] The instrument panel assembly 1 occupies the entire lateral space of the vehicle between the right side sill beam 6 and the left side sill beam 6 and between the right lower A-pillar 2 and the left lower A-pillar 2. Figure 2 It is usually attached to the following elements of the body in white:

[0045] - in front of the right and left front members 5 , and in front of the right and left upper fender beams 7 ,

[0046] - on the side of the right side sill beam 6 and the left side sill beam 6 and on the side of the right lower A pillar 2 and the left lower A pillar 2,

[0047] Towards the rear of the vehicle to the floor panel 3 , the tunnel nose 8 (which may not be present in the case of a purely electric drive vehicle) and to a floor reinforcement which is attached to the floor panel 3 and which is not shown in the drawings.

[0048] It should be noted that the above list of connected components is not restrictive and is not necessarily comprehensive, as it depends on the design of the selected vehicle structure. The present invention is specifically related to the instrument panel assembly 1 and can be applied to instrument panel assemblies connected to different types of surrounding components. In any case, it is important that the instrument panel assembly 1 occupies a central position in the front load path of the vehicle, thereby obtaining important forces from the front impact management structure such as, for example, the front member 5 and the upper fender beam 7. It also occupies a central position in the front lateral load path, such as between the front portion of the side sill beam 6 and the majority of the front portion of the lower A-pillar 2. Therefore, the instrument panel assembly is an essential component of the vehicle's front impact management system and side impact management system, involving the absorption, transmission and distribution of impact energy. It is also an important anti-intrusion component because it is located between the trajectory of the front motor and the front occupant of the vehicle in the event of a frontal impact. If no motor is located in the front motor compartment 102, the instrument panel assembly is directly located between the passenger compartment and the elements of the impacting vehicle.

[0049] Reference Figure 3 , which is an instrument panel assembly 1 according to the prior art, which usually has a generally curved shape, with the upper part being located closer to the front of the vehicle than the lower part. It also usually has several openings communicating with the front motor compartment, such as, for example, an opening 9 through which a pedal mechanism is inserted, or an opening 10 through which a steering column is inserted.

[0050] Reference Figure 4 , which is an exploded view of an instrument panel assembly according to the prior art, which is made of a plurality of individual parts assembled together, for example, by spot welding. Figure 3 and Figure 4 In the example below, ten separate widgets make up the dashboard component:

[0051] - a right lower side part 11 and a left lower side part 11,

[0052] - a lower central part 12,

[0053] - a right side bracket 13 and a left side bracket 13,

[0054] - reinforcing beam 14,

[0055] - a right upper side part 15 and a left upper side part 15,

[0056] - upper central part 16,

[0057] - Upper right reinforcement member 17.

[0058] In the event of a frontal collision, the front motor will be pushed backward toward the passenger compartment, and the reinforcing cross member 14 plays an important role in resisting intrusion. The reinforcing cross member 14 generally has an Ω shape and constitutes a hollow body extending in the lateral direction when assembled with the remaining sub-components in the sub-components, which effectively resists intrusion. The right side bracket 13 and the left side bracket 13 also form a hollow body on the side of the instrument panel assembly, which further constitutes resistance to intrusion, especially in the case of a collision with a small overlap in the width direction, which basically concentrates its energy only on one side of the instrument panel assembly. In addition, the side bracket 13 forms a strong assembly with the lower A-pillar and helps to improve the impact resistance of the vehicle when it is hit by a side collision.

[0059] The right upper reinforcement member 17 serves to provide additional rigidity in the area supporting the pedal mechanism.

[0060] The previously described instrument panel assembly design comprises a large number of individual subcomponents, which results in a complex logistics and manufacturing chain. This also presents high costs in terms of the tools used to form the individual components and in terms of the assembly to hold them all together. Furthermore, since the components are held together, for example, by spot welding, they may tear apart from one another during the life of the vehicle in the event of significant stresses such as stresses caused by a crash or simple repetitive fatigue stresses. The presence of many subcomponents is therefore also a source of potential structural weaknesses.

[0061] Reference Figure 5 and Figure 6 In contrast, the instrument panel assembly according to the present invention includes only two components, the lower instrument panel component 21 and the upper instrument panel component 22. The lower instrument panel component 21 and the upper instrument panel component 22 are each manufactured by forming a single metal sheet. For example, at least one of them is manufactured by hot stamping a single metal sheet. For example, at least one of them is manufactured by hot stamping a single metal sheet using a multi-step process. For example, at least one of them is manufactured by stamping a custom welded blank. For example, at least one of them is manufactured by stamping a custom rolled blank.

[0062] Reference Figure 6 , the lower instrument panel component 21 includes a lower portion 211 and an overlapping portion 212 located at the upper portion of the lower instrument panel component 21. The upper instrument panel component 22 includes an upper portion 221 and an overlapping portion 222 located at the lower portion of the upper instrument panel component 22. Once assembled, the lower instrument panel overlapping portion 212 and the upper instrument panel overlapping portion 222 are superimposed on each other (hence the term overlap). The portion of the instrument panel assembly 1 where the lower instrument panel component and the upper instrument panel component overlap each other is referred to as the overlapping portion 12. On the other hand, once the instrument panel is assembled, the lower portion 211 of the lower instrument panel component and the upper portion 221 of the upper instrument panel component do not overlap each other.

[0063] Reference Figure 7B , which is a schematic cross section of an instrument panel assembly 1 according to the invention, the overlapping portion 12 comprises at least one flat overlapping area 122 in which the upper instrument panel 21 and the lower instrument panel 22 lie flat against each other. In other words, in at least one flat overlapping area 122 of the overlapping portion 12, the instrument panel lower overlapping part 212 and the instrument panel upper overlapping part 222 have the same shape so that once assembled, they fit flat against each other in said flat overlapping area 122. The upper instrument panel 22 and the lower instrument panel 21 can be assembled together in at least one flat overlapping area 122, for example by resistance spot welding or by laser welding. The flat overlapping area 122 also provides the technical advantage of having greatly increased resistance to intrusion, since two layers of shaped metal sheets are available in this area to jointly resist intrusion.

[0064] In a specific embodiment, Fig. 7A and Figure 7B As depicted above, the overlapping area 122 also includes at least one hollow portion 120 in which the overlapping portion 212 of the upper instrument panel and the overlapping portion 222 of the lower instrument panel are spaced apart from each other in the longitudinal direction so as to define together an internal volume comprised between said overlapping portion 212 and said overlapping portion 222. Advantageously, the presence of the hollow portion 120 allows increasing the overall rigidity of the instrument panel assembly 1 and also allows better resistance to intrusion. In fact, the presence of the hollow portion 120 gives the instrument panel assembly rigidity and makes it more difficult for the instrument panel assembly to deform in said hollow portion.

[0065] In the figures, the hollow portion 120 is formed by designing substantially horizontal walls in the upper instrument panel overlap 212 over the entire width of the component and also by designing substantially horizontal walls in the side portions of the lower instrument panel overlap 222 - the central portion of the lower instrument panel overlap 222 remains substantially flat in the hollow portion 120, acting as a flat closed plate for the internal volume. Advantageously, this design allows for a larger hollow volume to be created in the sides of the instrument panel assembly, thereby allowing for further resistance to side intrusion. This is particularly useful in the case of a frontal collision with small overlap, during which the load will be primarily applied only on one side of the component.

[0066] The hollow portion 120 may be designed in different ways, such as by using a rounded bead-like shape in the corresponding lower instrument panel overlap portion 222 and / or upper instrument panel overlap portion 212 .

[0067] Generally speaking, if the horizontal wall is designed as a metal plate with excellent mechanical resistance, the amount of impact energy absorbed and the amount of intrusion resistance will be greater. For example, if the horizontal wall is designed as a metal plate with a maximum metal plate thickness, or with a maximum yield strength, or with a maximum product of yield strength and metal plate thickness, the amount of impact energy absorbed and the amount of intrusion resistance will be greater.

[0068] The design of the present invention allows to greatly simplify the concept and manufacturing process of the instrument panel assembly by reducing the number of sub-components. In turn, it allows to greatly reduce the number of assembly points between sub-components.

[0069] The reduction in the number of overlapping areas required to assemble the different subcomponents in conjunction with the optimal choice of materials also leads to a significant reduction in the weight of the assembly.

[0070] Furthermore, the design of the invention reproduces in a simplified manner the key safety features of the prior art design and in particular the reinforcement of the dashboard assembly in its central portion. Said reinforcement is ensured, for example, by a reinforcement crossbeam 14 in the prior art design. In the design of the invention, said reinforcement is ensured by doubling the plate thickness in the overlapping portion 12, optionally enhanced by the presence of a hollow portion 120 in the overlapping portion 12. The overlapping portion 12 of the design of the invention allows preventing the front motor from penetrating the passenger compartment 101. It also allows increasing the overall rigidity of the component and allows resisting the transverse compressive loads exerted on the component in the event of a side impact.

[0071] In a specific embodiment, the instrument panel assembly is manufactured by hot stamping a steel sheet, and a blank for producing the instrument panel assembly includes one of the following materials combined in the form of an integral blank or in the form of a custom welded blank:

[0072] - Steel having a composition including, by weight percentage, 0.06% ≤ C ≤ 0.1%, 1% ≤ Mn ≤ 2%, Si ≤ 0.5%, Al ≤ 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% of Cu, Ni and Mo, the remainder being iron and unavoidable impurities resulting from smelting. Within this composition range, the yield strength of the corresponding region after hot stamping is comprised between 700 MPa and 950 MPa, the tensile strength is between 950 MPa and 1200 MPa, and the bending angle is greater than 75°. For example, this material is used in the region corresponding to the upper portion 221 of the upper instrument panel, because this material absorbs energy without breaking, and this region does not need to resist intrusion as much as the upper instrument panel overlap portion 222.

[0073] - Steels having an ultimate tensile strength after hot stamping comprised between 1300 and 1650 MPa and a yield strength comprised between 950 and 1250 MPa.

[0074] - Steels having an ultimate tensile strength after hot stamping comprised between 1300 and 1650 MPa, a yield strength comprised between 950 and 1250 MPa and a bending angle greater than 75°.

[0075] - Steel having a composition including, by weight percentage, 0.20%≤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 remainder being iron and unavoidable impurities resulting from smelting. Within this composition range, the ultimate tensile strength of the corresponding region of the component after hot stamping is comprised between 1300 MPa and 1650 MPa and the yield strength is comprised between 950 MPa and 1250 MPa. For example, this steel composition is used for the region corresponding to the overlapping portion 12 of the instrument panel assembly (i.e., for the steel constituting the overlapping portion 212 of the lower instrument panel component and the overlapping portion 222 of the upper instrument panel component). In fact, this steel grade has high anti-intrusion properties.

[0076] - Steels having a tensile strength above 1800 MPa after press hardening.

[0077] - Steel having a composition including, by weight percentage, the following: 0.24% ≤ 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 resulting from smelting. Within this composition range, the tensile strength of the corresponding area of ​​the instrument panel component after hot stamping is higher than 1800 MPa. For example, this material is used in the overlapping part 12 to benefit from its high anti-intrusion properties.

[0078] - Steel having a composition including the following by weight percentage: C: 0.15% to 0.25%, Mn: 0.5% to 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 the composition of the steel optionally contains one or more of the following elements by weight percentage: Mo≤0.40%, Nb≤0.08%, Ca≤0.1%, and the remaining components are iron and unavoidable impurities resulting from smelting. Within this composition range, the tensile strength of the corresponding area of ​​the instrument panel component after hot stamping is higher than 1350MPa, and the bending angle is greater than 70°.

[0079] - Steel having a composition including the following by weight percentage: C: 0.26% to 0.40%, Mn: 0.5% to 1.8%, Si: 0.1% to 1.25%, Al: 0.01% to 0.1%, Cr: 0.1% to 1.0%, Ti: 0.01% to 0.1%, B: 0.001% to 0.004%, P≤0.020%, S≤0.010%, N≤0.010%, and the composition of the steel optionally contains one or more of the following elements by weight percentage: Ni≤0.5%, Mo≤0.40%, Nb≤0.08%, Ca≤0.1%, and the remaining components are iron and unavoidable impurities resulting from smelting. Within this composition range, the tensile strength of the corresponding area of ​​the instrument panel component after hot stamping is higher than 1350MPa, and the bending angle is greater than 70°.

[0080] - Steel having a composition including the following by weight percentage: C: 0.2% to 0.34%, Mn: 0.50% to 1.24%, Si: 0.5% to 2%, P≤0.020%, S≤0.010%, N≤0.010%, and the composition of the steel optionally contains one or more of the following elements by weight percentage: Al: ≤0.2%, Cr≤0.8%, Nb≤0.06%, Ti≤0.06%, B≤0.005%, Mo≤0.35%, and the remaining components are iron and unavoidable impurities generated by smelting. Within this composition range, the tensile strength of the corresponding area of ​​the instrument panel component after hot stamping is equal to or higher than 1000 MPa, and the bending angle is greater than 55°.

[0081] - Steel having a composition including, in percentage by weight: C: 0.13% to 0.4%, Mn: 0.4% to 4.2%, Si: 0.1% to 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 verifying the following combination: 114-68*C-18*Mn+20*Si-56*Cr-60*Ni-36*Al+38*Mo+79*Nb-17691*B<20, the remainder being iron and unavoidable impurities resulting from smelting. For example, this composition is used when hot stamping parts using a multi-step process.

[0082] - Steel coated with an aluminium-based metallic coating. By aluminium-based is meant a coating comprising at least 50% aluminium by weight. For example, the metallic coating is an aluminium-based coating comprising 8 to 12% Si by weight. The metallic coating is applied, for example, by immersing the base material in a bath of molten metal. Advantageously, applying the aluminium-based metallic coating avoids the formation of surface scale during the heating step of the hot stamping process, which in turn allows the production of the component by hot stamping without subsequent sandblasting operations. Furthermore, the aluminium-based coating also provides corrosion protection to the component when used on vehicles.

[0083] - Steel coated with an aluminum-based metal coating comprising 2.0 to 24.0% by weight of zinc, 1.1 to 12.0% by weight of silicon, optionally 0 to 8.0% by weight of magnesium, and optionally an additional element selected from Pb, Ni, Zr or Hf, the content of each additional element by weight being less than 0.3% by weight, the remainder being aluminum and optionally unavoidable impurities. Advantageously, this type of metal coating provides very good corrosion protection to the component and a good surface appearance after hot stamping.

[0084] In a particular embodiment, at least the upper or lower instrument panel is manufactured by hot stamping a laser welding blank comprising at least one sub-blank having an aluminum-based metal coating, and the aluminum-coated sub-blank is previously prepared by ablation of at least a portion of the metal coating on the edge to be welded. Advantageously, this removes part of the aluminum present in the coating, which would contaminate the weld and deteriorate its mechanical properties.

[0085] In a particular embodiment, at least one of the instrument panel upper part or the instrument panel lower part is manufactured by hot stamping a laser welded blank, the laser welded blank comprising at least one sub-blank having at least one side portion with an emissivity increasing top layer on top. The emissivity increasing top layer is applied on the outermost surface of the sub-blank. The emissivity increasing top layer allows the surface of the sub-blank to have a higher emissivity compared to the same sub-blank not coated with the emissivity increasing top layer. The emissivity increasing top layer can be applied on the top side or the bottom side of the sub-blank. The emissivity increasing top layer can also be applied on both sides of the sub-blank. If the sub-blank includes a metal coating, as described above, the emissivity increasing top layer is applied on top of the metal coating. In fact, for the emissivity increasing top layer to increase the emissivity of the surface, it needs to cover the outermost surface of the sub-blank. Advantageously, the emissivity increasing top layer will allow increasing the heating rate of the sub-blank and thus increasing the productivity of the heating step of the hot stamping process. When using several sub-blanks of different thickness, the emissivity-increasing top layer is advantageously applied to the sub-blank with the greatest thickness in order to reduce the differences in heating times between the different sub-blanks and thus improve productivity, increase the hot stamping process window and generally allow obtaining a finished part with uniform surface properties.

[0086] In a specific embodiment, the upper panel and the lower panel are connected by Fig. 8A and Figure 8B The custom welded blanks schematically shown above are manufactured by hot stamping. The steel grades and thicknesses will be further detailed by reference to the following table (which can be produced using the detailed embodiments for steel grade chemistry described above):

[0087]

[0088] Steel D1000 has a lower yield strength but a high bending angle. Therefore, it will deform and absorb energy more easily than steel U1500. On the other hand, due to its higher strength, steel U1500 will have a better anti-intrusion behavior than D1000.

[0089] Reference Fig. 8A , the custom welded blank for the upper instrument panel 22 is composed of three sub-blanks 221A, 221B and 222A having the following grades and thicknesses:

[0090] Sub-blank number Steel Grade thickness 221A D1000 1.4mm 221B D1000 1.0mm 222A U1500 2.5mm

[0091] Sub-blanks 221A and 221B correspond to the upper portion 221 of the upper instrument panel component once the component is formed. Sub-blank 222A, on the other hand, corresponds to the overlapping portion 222 of the upper instrument panel component once the component is formed.

[0092] As mentioned above, the anti-intrusion function of the instrument panel assembly is mainly ensured by the overlapping portion 12. Therefore, the sub-blank 222A of the current embodiment is made of extremely high-strength steel grade D1500 and has a high thickness of 2.5 mm. Moreover, in the case of the current embodiment, once formed, the overlapping portion 222 of the upper instrument panel comprises substantially horizontal walls so as to form a hollow portion 120 within the overlapping portion 12. As in the case of the current embodiment, the choice of a very high-strength, high-thickness material in this portion will advantageously increase the rigidity and anti-intrusion performance of the component.

[0093] On the other hand, the upper part of the upper instrument panel is allowed to deform without breaking during a frontal collision in order to absorb energy. Therefore, steel grade D1000 is selected for sub-blanks 221A and 221B. In addition, since 221A is located in the area where the pedal mechanism is inserted, a higher thickness is selected for this sub-blank to increase the rigidity in this area.

[0094] Since sub-blank 222A has a significantly higher thickness compared to the other sub-blanks, it would be interesting to provide the above-mentioned emissivity increasing top layer on at least one side of sub-blank 222A in order to ensure that the heating rate in the austenitizing furnace is as uniform as possible for all areas of the custom welded blank.

[0095] Turning to the lower instrument panel 21, the custom welded blank used to manufacture it consists of four sub-blanks 212A, 212B, 211A, 211B and 21A having the following grades and thicknesses:

[0096] Sub-blank number Steel Grade thickness 212A U1500 1.6mm 212B U1500 1.6mm 211A U1500 1.5mm 211B U1500 1.5mm 21A U1500 1.2mm

[0097] Once the part is formed, the sub-blanks 212A and 212B correspond to the overlapping portion 212 of the lower instrument panel upper part. On the other hand, once the part is formed, the sub-blanks 211A and 211B correspond to the lower portion 211 of the lower instrument panel part. Once the part is formed, the sub-blank 21A spans both the overlapping portion and the lower portion.

[0098] As can be seen, the material thickness on the sub-blanks (212A, 212B, 211A, 211B) occupying the side portions of the component is greater than the material thickness on the sub-blank (21A) occupying the central portion of the component. This is to provide better resistance of the component in the event of a partial overlap impact, such as that simulated by the ODB or SORB regulatory tests detailed above. In addition, due to the need for a higher resistance to intrusion in the overlapping portion, the blanks 212A, 212B corresponding to the side portions of the overlapping portion have a greater thickness than the blanks corresponding to the lower portion.

[0099] The above embodiment allows to significantly reduce the number of spot welds used to assemble the instrument panel. For example, it allows to reduce the number of spot welds from 158 spot welds in the assembly of the prior art (see Figure 3 and Figure 4 ) is reduced to 80 spot welds in the current embodiment of the invention ( Figure 5 and Figure 6 ).

[0100] It also allows for an overall weight reduction: the prior art assembly weighs 18.70 kg, while the inventive design weighs 17.34 kg, a significant 7% weight reduction.

[0101] The inventors have found that the same safety performance can be achieved in the above IIHS ODB and SORB crash tests between the above 18.70kg prior art design and the 17.34kg inventive design. This shows that the inventive design allows a better compromise between safety performance and component weight than the prior art.

[0102] Fig. 9A , FIG. 9B to FIG. 11A , Fig. 11B The above embodiment of the present invention is related to the simulated IIHS front overlap deformable barrier (ODB) impact test. In this test, the vehicle is hit by a rigid barrier (not shown in the figure for clarity) moving at 64.4 km / h with only 40% overlap in width.

[0103] At the beginning of the test, before the barrier hits the vehicle ( Fig. 9A and Fig. 9B ), the motor 18 is located at a certain distance from the instrument panel assembly 1. Once the collision object hits the vehicle, the collision object pushes the motor 18 backward toward the vehicle compartment, and finally hits the instrument panel assembly 1 at t = 0.085s ( Fig. 10A , Fig. 10B The impact also has the effect of tilting the motor 18 at a certain angle, as can be seen in the figure. At t = 0.105 s, the impactor reaches its maximum penetration depth ( Fig.11A and 11B ). Simulations show that the instrument panel assembly resists motor intrusion into the passenger compartment, particularly due to the overlap 12. The upper and lower instrument panels dent under the pressure exerted by the motor, but there is no significant intrusion, and the overlap 12 remains rigid.

Claims

1. An instrument panel assembly (1) for a motor vehicle (100), the instrument panel assembly (1) occupying the entire lateral space between the right side sill beam (6) and the left side sill beam (6) and between the right lower A-pillar (2) and the left lower A-pillar (2) of the motor vehicle, the instrument panel assembly (1) separating a front motor compartment (102) from a passenger compartment (101) and comprising a lower instrument panel (21) and an upper instrument panel (22), such that: - the lower instrument panel (21) and the upper instrument panel (22) are each manufactured by forming a single metal sheet, - the lower panel (21) further comprises a lower portion (211) and an overlapping portion (212), - the upper panel (22) further comprises an upper portion (221) and an overlapping portion (222), - once assembled to form the instrument panel assembly (1), the instrument panel lower component (21) and the instrument panel upper component (22) overlap each other in respective overlapping portions (212, 222) of the instrument panel lower component (21) and the instrument panel upper component (22) to form an overlapping portion (12) of the instrument panel assembly, and do not overlap each other in the lower portion (211) of the lower instrument panel and the upper portion (221) of the upper instrument panel, The overlapping portion (12) of the instrument panel assembly (1) comprises at least one flat overlapping portion (122) in which the lower instrument panel (11) and the upper instrument panel (12) lie flat against each other.

2. The instrument panel assembly (1) for a motor vehicle (100) according to claim 1, wherein: At least one of the lower instrument panel (21) and the upper instrument panel (22) is manufactured by stamping a custom welded blank.

3. An instrument panel assembly (1) for a motor vehicle (100) according to claim 1 or 2, wherein: At least one of the lower instrument panel (21) and the upper instrument panel (22) is manufactured by hot stamping.

4. An instrument panel assembly (1) for a motor vehicle (100) according to any one of claims 1 to 3, wherein: The overlapping portion (12) further includes a hollow portion (120), in which the overlapping portion (212) of the lower instrument panel and the overlapping portion (222) of the upper instrument panel are spaced apart from each other in a longitudinal direction to form a hollow volume between the overlapping portion (212) of the lower instrument panel and the overlapping portion (222) of the upper instrument panel.

5. A motor vehicle (100) comprising an instrument panel assembly (1) according to any one of claims 1 to 4.

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