hood, interior element and motor vehicle

Abstract

Front hood (2) with an outer element (7) and an inner element (8), the latter having a flank region (9, 10) extending at least partially in a vehicle height direction, which is subjected to a load in the vehicle height direction upon an impact from above on the outer element (7) of the front hood (2), wherein the flank region (9, 10) extending at least partially in the vehicle height direction comprises a predetermined breaking section (13) arranged in the vehicle height direction between two displacement sections (11, 12), which breaks or fails upon an impact on the outer element (7) of the front hood (2) occurring above the predetermined breaking section (13) such that the displacement sections (11, 12) are displaced relative to each other in the vehicle height direction by the load on the outer element (7), wherein the breaking or failure of the predetermined breaking section (13) and the relative displacement of the displacement sections (11, 12) achieve a desired cause compliance,characterized in that the predetermined breaking section (13) in the flank area (9, 10) extending at least partially in the vehicle height direction comprises a planar additional element (30) formed from a fracture-agile material with at least one predetermined breaking point, wherein the predetermined breaking section (13) is shown only with the planar additional element (30), wherein the inner element (8) is formed from a fiber composite material (28).

Description

[0001] The invention relates to a front hood according to the preamble of claim 1. The invention also relates to a motor vehicle with such a front hood.

[0002] German patent application DE 10 2011 109 468 A1 discloses a front hood with two outer layers and a foam-like intermediate layer, wherein at least one recess is provided in a lower outer layer to increase compliance and to provide pedestrian protection. German utility model application DE 20 2017 103 405 U1 discloses a front hood with an inner sheet and an outer sheet, wherein the inner sheet is weakened by perforation to provide pedestrian protection. International patent application WO 2012 / 096 244 A1 discloses a front hood structure with a shock-absorbing part consisting of breakable parts that locally reduce its strength. German patent application DE 102 47 425 A1 discloses a sandwich-shaped front hood structure with a top layer, an intermediate layer, and a multi-part substructure that breaks into several parts when subjected to force.where predetermined breaking points are represented in the form of fiber breaks and reduced cross-sections in the substructure. U.S. Patent Application US 2008 / 0185874A1 discloses a hood made of a fiber-reinforced composite material with a mesh-like resin network between different fiber-reinforced composite layers, wherein the mesh-like resin network contains a flexible resin with a low affinity for adhesion to a matrix resin of the fiber-reinforced composite layers. U.S. Patent Application US 2010 / 0045070A1 discloses a unit comprising a motor vehicle hood and a lining of the motor vehicle hood, wherein the lining extends over the entire surface of the hood and is designed to stiffen the hood near its circumference by forming a hollow body with it at least over a portion of its circumference, wherein the lining, in the portion forming the hollow body,a cross-section substantially in a U-shape, comprising a bottom and side walls, wherein the bottom or at least one of the side walls has at least locally a weakening zone dimensioned such that, upon impact of the hood with the head of a pedestrian, as soon as the bottom of the hollow body comes to rest on a hard spot located high in the engine compartment, the weakening zone breaks, wherein the weakening zone is further dimensioned to break by allowing at least one part forming the hollow body, in particular at least one part of a wall forming the side wall of the hollow body, to indent into the engine compartment deeper than the hard spot. Japanese patent application JP 2009-234380A discloses a vehicle front section with a hood covering the engine compartment; and with a body frame,which, in the closed state, is located between the hood and the body frame and is essentially vertically deformable. International Patent Application WO 2012 / 080602A1 discloses a front section of a vehicle, such as a motor vehicle, comprising a hood with an inner lining, mounted between the front bumper and the windshield of the vehicle, and a transverse cowl grille, mounted between the windshield and the hood, and having a front section located under a rear section of the hood when the latter is in the closed position, wherein the hood and its inner lining, as well as the cowl grille, are capable of deforming upon impact by a pedestrian on the rear section of the hood.to absorb the impact. German patent application DE 100 62 155 A1 discloses an impact-absorbing hood for a vehicle, comprising an upper sheet metal panel and a substructure connected to it, formed from a single or multi-part inner sheet metal panel or from several such inner sheet metal panels, which has a frame and a stiffening structure formed within it from bows, wherein at least the frame is connected to the upper sheet metal panel, wherein the stiffening structure is connected to the frame by connection points forming predetermined breaking points and / or the bows or a part thereof have such predetermined breaking points. Japanese patent application JP 2007 - 038 733 A discloses a vehicle body front structure in which a damping element is arranged between the hood and a body component. German patent application DE 10 2011 118 690 A1 discloses a front hood for a passenger car,with a structure consisting of two spaced-apart cover layers, between which at least one core element of the structure is arranged, with a first sub-area and with at least one adjacent second sub-area which has a higher compliance than the first sub-area, wherein the higher compliance is formed by a separating layer incorporated between the cover layers, by which wall regions of the structure adjacent to the separating layer are separated from one another. Japanese patent application JP 2018-192827A discloses a vehicle exterior panel produced by laminating several fiber-reinforced resin layers from the inside of the vehicle to the outside, wherein the fiber direction in the several fiber-reinforced resin layers runs along one direction.which intersects the longitudinal direction of the vehicle. German patent application DE 195 14 324 A1 discloses a hood arrangement for absorbing an impact acting on the hood of a motor vehicle in a collision, presenting an ideal relationship between a reaction force and a stroke of a deformed outer hood panel.

[0003] The object of the invention is to improve the impact damping on a front hood according to the preamble of claim 1.

[0004] The problem is solved by a front hood with the features of new claim 1. Relative displacement of the displacement sections means that one of the displacement sections, in particular the uppermost displacement section, can displace relative to the other displacement section, especially downwards. The vehicle's vertical direction is also referred to as the z-direction. The z-direction is perpendicular to a plane spanned by a longitudinal direction of the vehicle, also referred to as the x-direction, and a transverse direction of the vehicle, also referred to as the y-direction. The front hood, which can also be referred to as a front flap, serves to close a trunk and / or electronics compartment of a motor vehicle located in the front area.For the proper functioning of the vehicle, it is essential that the hood provides a fluid-tight seal to the trunk and / or electronics compartment in the front of the vehicle, reliably preventing contamination of the trunk and / or electronics compartment, and in particular the unwanted ingress of water, when closed. To this end, the hood comprises an outer element forming the outer skin and an inner element sealing the trunk or electronics compartment. According to a key aspect of the invention, the inner element is designed such that, in the event of an impact from above, for example by a pedestrian, particularly a head impact, the outer element of the hood can move downwards with little or no resistance. This downward movement of the outer element is facilitated by the predetermined breaking point in the flank area of ​​the inner element.If the predetermined breaking point breaks or fails, the displacement sections of the inner element can shift relative to each other in the vehicle's vertical direction. The breaking or failure of the predetermined breaking point, in combination with the relative displacement of the displacement sections, causes the outer element to deform in the desired manner upon impact from above. This resulting compliance effectively reduces the resistance of the closed hood in the event of a head impact. This improves pedestrian protection on the vehicle equipped with the hood. Among other advantages, the hood design allows the outer element to be completely closed. Furthermore, the outer element can be advantageously designed without creases or other features that are typically used on hoods to improve pedestrian protection.The planar additional element is selectively incorporated into the inner element during its manufacture, particularly when made of a fiber-reinforced composite material. This offers the advantage, among others, that the material from which the inner element is formed does not itself need to be used to create the predetermined breaking point. The predetermined breaking point is advantageously represented solely by the planar additional element. This is particularly beneficial when creating the predetermined breaking point in the material of the inner element is difficult and / or costly. The embodiments described above have proven highly effective for inner sheet metal. However, for an inner element made of fiber-reinforced composite material, implementing these embodiments may result in increased manufacturing costs.Therefore, the embodiment described above with the flat additional element is particularly advantageous when the inner element is made of a fiber composite material.

[0005] A preferred embodiment of the front hood is characterized in that the predetermined breaking point is limited by defined embrittled areas in the flank region extending at least partially in the vehicle's height direction. These defined embrittled areas can be created on the inner element, for example, by targeted and concentrated heat input, which embrittles or thins the metallurgical structure of the metallic material from which the inner element is formed. When a load is applied from above to the outer element, the defined embrittled areas cause cracks to form abruptly on the inner element, resulting in the predetermined breaking point breaking away.

[0006] Another preferred embodiment of the front hood is characterized in that the predetermined breaking point is delimited in the flank area, which extends at least partially in the vehicle's height direction, by micro-recesses that are sealed by a conventional paint application. The micro-recesses enable targeted micro-weakening of the inner element around the predetermined breaking point. This allows the predetermined breaking point to be at least partially detached from the inner element in the desired manner, thus enabling the relative displacement of the displacement sections in the vehicle's height direction. The micro-recesses can, for example, be designed such that a small circumferential groove or micro-groove is created around the predetermined breaking point, which is filled with paint. Depending on the embodiment, the predetermined breaking point is held in the inner element solely by the paint.Depending on the design, it can also be helpful to hold the predetermined breaking point against the inner element during normal operation of the vehicle by means of further measures, such as the insertion of a suitable fabric.

[0007] Another preferred embodiment of the front hood is characterized in that the predetermined breaking point is limited by defined reductions in wall thickness in the flank area extending at least partially in the vehicle's height direction. These reductions in wall thickness, combined with a corresponding weakening of the material, create, for example, at least one weakening line that limits the predetermined breaking point. Depending on the design, the weakening line can extend around the entire predetermined breaking point. However, it is also possible that only individual weakening lines are provided, which partially limit the predetermined breaking point.

[0008] Another preferred embodiment of the hood is characterized in that the predetermined breaking point in the flank area, which extends at least partially in the vehicle's height direction, is bounded by a joint with webs that connect the predetermined breaking point to the displacement sections. The webs ensure that the predetermined breaking point is securely held to the inner element during normal vehicle operation and, in combination with a conventional paint application, is not visible. Advantageously, the webs are designed to break upon impact from above on the hood, thus enabling the desired relative displacement of the displacement sections on the inner element.

[0009] Another preferred embodiment of the front hood is characterized in that the predetermined breaking point transverse to the vehicle's vertical direction has a dimension more than twice that of the predetermined breaking point in the vehicle's vertical direction. This improves the desired effect with regard to pedestrian protection. Depending on the size and shape of the affected flank area on the inner element, several predetermined breaking points can also be advantageously arranged one above the other in the vehicle's vertical direction.

[0010] The invention further relates to an inner element for a previously described front hood. The inner element is separately marketable.

[0011] The invention further relates to a motor vehicle with a previously described front hood. Advantageously, the motor vehicle is a purely electric vehicle.

[0012] Further advantages, features, and details of the invention will become apparent from the following description, in which various exemplary embodiments are described in detail with reference to the drawing. The drawing shows: Fig. 1 a perspective view of an interior element of a hood of a vehicle Fig. 2 motor vehicles shown; Fig. 2 a perspective view of a motor vehicle with a hood; Fig. 3 a schematic representation of a flank area at which in Fig. 1 shown inner element of the front hood according to a first embodiment; Fig. 4. The representation of a section along a line IV-IV in Fig. 3; Fig. 5 a similar representation as in Fig. 3 according to a second embodiment; Fig. 6. A section view through an inner element connected to an outer element, which is designed with a predetermined breaking point, in a normal operating condition of a motor vehicle equipped with the front hood closed; Fig. 7 the front hood Fig. 6 in the event of a simulated head impact, in which the predetermined breaking section releases and allows a relative displacement of two displacement sections of the inner element; Fig. 8 a similar representation as in Fig. 3 according to a further embodiment; Fig. 9 the representation of a section along line IX-IX in Fig. 8; Fig. 10 a similar representation as in Fig. 7 with an inner element made of a fiber composite material; and Fig. 11 an embodiment with an additional element for representing the predetermined breaking point in or on the inner element of the front hood.

[0013] In Fig. Figure 2 shows a motor vehicle 1 with a hood 2, two fenders 3, 4 and two headlights 5, 6, shown in perspective. The hood 2 comprises an outer element 7 and an inner element 8, which is in Fig. 1 is shown.

[0014] In Fig. Figure 1 shows that the inner element 8 of the front hood comprises flank sections 9 and 10, which extend at least partially in a vehicle height direction, also referred to as the z-direction. "Partially" in this context means that the flank sections 9 and 10 do not necessarily extend exactly in the z-direction. As can be seen in Fig. 1 looks diagonally to the vehicle's height direction.

[0015] In the Fig. 3, Fig. 4, Fig. 5, Fig. 6, Fig. 7, Fig. 8, Fig. 9, Fig. 10 to Fig. Figure 11 shows various embodiments in which the inner element 8 of the front hood is specifically designed with a predetermined breaking point 13. The predetermined breaking point 13 is arranged in the vehicle height direction between two displacement sections 11, 12. If the predetermined breaking point 13 breaks or fails, this allows a relative displacement of the displacement sections 11, 12 in the vehicle height direction.

[0016] This means that when the predetermined breaking section 13 breaks, the displacement section 12 shifts downwards relative to the displacement section 11. This provides increased flexibility at this point for pedestrian protection.

[0017] In Fig. Figure 3 shows that the predetermined breaking point 13 essentially has the shape of an elongated hole. The predetermined breaking point 13 is completely enclosed by weakening lines 14 and 15. Weakening line 14 is located in the vehicle height direction between the predetermined breaking point 13 and the displacement section 12. Weakening line 15 is located in the vehicle height direction between the displacement section 11 and the predetermined breaking point 13.

[0018] In Fig. Figure 4 indicates that the weakening lines 14 and 15 are achieved through targeted embrittlement of the material, particularly sheet metal. This targeted embrittlement is made possible, for example, by focused heat input using a laser.

[0019] In the event of a head impact on the hood from above, a stress jump occurs along the structural embrittlement in the area of ​​the weakening lines 14, 15, which leads to a sudden crack formation in the inner element around the predetermined breaking point 13.

[0020] In Fig. Figure 5 shows that the weakening lines 14, 15 can also be achieved by micro-weakening of the material from which the inner element 8 is formed. The predetermined breaking point 13 is partially triggered by mechanical separation.

[0021] This creates a small circumferential joint that is only connected to the sheet metal material from which the inner element 8 is formed at defined webs 16 to 19. The force required to release the predetermined breaking section from the inner element 8 can be adjusted and / or controlled by the width and number of the webs 16 to 19.

[0022] In Fig. 6 indicates that the predetermined breaking point 13 is in normal operation of the motor vehicle due to the in Fig. 5, designated as bridges 16 to 19, remain connected to the relocation sections 11 and 12. In Fig. The outer element 7, for example, is formed from an outer sheet 21. The inner element 8, for example, is formed from an inner sheet 22. In a connection area 23, the inner sheet 22 is connected to the outer sheet 21, for example by welding or bonding.

[0023] In Fig. Figure 7 is indicated by an arrow 25 and a contour line 26, showing how the inner element 8 fails upon a head impact during operation of the motor vehicle against the outer element 7. In this process, the predetermined breaking section 13 releases as desired, allowing a relative displacement of the displacement section 12 relative to the displacement section 11. Fig. 7 in the direction of arrow 25 downwards.

[0024] The inner element 8, with the predetermined breaking section 13 and the webs 16 to 19, can be manufactured by stamping, etching, or laser cutting. The webs 16 to 19 are as small as possible, for example, only 0.5 millimeters long. This allows for the desired seal on the inner element 8 to be achieved through conventional dip coating. The surface tension of the coating covers the gaps between the predetermined breaking section 13 and the displacement sections 11, 12 in the area of ​​the weakening lines 14, 15 between the webs 16 to 19.

[0025] In the Fig. 8 and Fig. Figure 9 shows that the weakening lines 14, 15 can also be achieved solely through targeted material weakening in the material from which the inner element is formed. The desired material weakening can be achieved, for example, by a suitable punch / die combination in conjunction with a pressing process for manufacturing the inner element from a sheet of metal.

[0026] During cold forming in the pressing process, additional structural changes occur in the sheet metal, causing local, stress-induced changes in stiffness. This allows the deformation behavior of the internal element under load to be specifically controlled or adjusted.

[0027] In Fig. Figure 10 indicates that the inner element 8 can also be made from a fiber-reinforced composite material 28. The fiber-reinforced composite material 28 comprises individual layers of a fiber-reinforced fabric embedded in a resin. Designing such laminates to withstand breakage and / or tearing is rather difficult.

[0028] In Fig.Figure 11 indicates that, in the case of an inner element 8 made of a fiber-reinforced composite material 28, a planar additional element 30 is advantageously incorporated into the inner element 8 to represent the predetermined breaking point 13. The additional element 30 is advantageously made of a fracture-resistant material, for example, a material with the short designation PPT 40.

[0029] Furthermore, the additional element 30 is advantageously provided with predetermined breaking points, which serve to represent the weakening lines 14, 15 between the predetermined breaking section 13 and the displacement sections 11, 12. The planar additional element 30 is embedded with its end sections 31, 32 in the fiber composite material 28 from which the inner element 8 is formed. Reference sign 1 motor vehicle 2 Front hood 3 fenders 4 fenders 5 headlights 6 headlights 7 Exterior element 8 interior elements 9 flank area 10 Flank area 11 Relocation section 12 Relocation section 13 Breakaway section 14 Weakness line 15 Weakness line 16 Bridge 17 Bridge 18 Bridge 19 Bridge 21 Outer sheet 22 Inner sheet 23 Connection area 25 Arrow 26 Contour line 28 Fiber composite material 30 Additional element 31 Final section 32 End section

Claims

Front hood (2) with an outer element (7) and an inner element (8), the latter having a flank region (9, 10) extending at least partially in a vehicle height direction, which is subjected to a load in the vehicle height direction upon an impact from above on the outer element (7) of the front hood (2), wherein the flank region (9, 10) extending at least partially in the vehicle height direction comprises a predetermined breaking section (13) arranged in the vehicle height direction between two displacement sections (11, 12), which breaks or fails upon an impact on the outer element (7) of the front hood (2) occurring above the predetermined breaking section (13) such that the displacement sections (11, 12) are displaced relative to each other in the vehicle height direction by the load on the outer element (7), wherein the breaking or failure of the predetermined breaking section (13) and the relative displacement of the displacement sections (11, 12) achieve a desired cause compliance,characterized in that the predetermined breaking section (13) in the flank area (9, 10) extending at least partially in the vehicle height direction comprises a planar additional element (30) formed from a fracture-agile material with at least one predetermined breaking point, wherein the predetermined breaking section (13) is shown only with the planar additional element (30), wherein the inner element (8) is formed from a fiber composite material (28). Front hood (2) according to claim 1, characterized in that the predetermined breaking section (13) in the flank area (9,10) extending at least partially in the vehicle height direction is limited by defined embrittled areas. Front hood (2) according to one of the preceding claims, characterized in that the predetermined breaking section (13) in the flank area (9,10) extending at least partially in the vehicle height direction is limited by micro recesses which are closed by a conventional paint application. Front hood (2) according to one of the preceding claims, characterized in that the predetermined breaking section (13) in the flank area (9,10) extending at least partially in the vehicle height direction is limited by defined wall thickness reductions. Front hood (2) according to one of the preceding claims, characterized in that the predetermined breaking section (13) in the flank area (9,10) extending at least partially in the vehicle height direction is limited by a joint with webs (16-19) which connect the predetermined breaking section (13) with the displacement sections (11,12). Front hood (2) according to one of the preceding claims, characterized in that the predetermined breaking section (13) has a dimension transverse to the vehicle height direction which is more than twice as large as the dimension of the predetermined breaking section (13) in the vehicle height direction. Interior element (8) for a front hood (2) according to one of the preceding claims. Motor vehicle (1) with a front hood (2) according to one of claims 1 to 6 .

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