DE102009059984A1 - Front flap for a motor vehicle - Google Patents

Abstract

The invention relates to a front flap for a motor vehicle with an outer panel and an inner panel (3), which are interconnected at their peripheral outer edges. The inner panel (3) has a head impact zone formed by a deformation structure (4) for protecting pedestrians in a collision with the motor vehicle and a frame (5) at least partially delimiting the deformation structure (4) and forming the outer edge of the inner panel (3). According to the invention, it is provided that the outer sheet is made of steel or aluminum and the inner sheet (3) is made of steel and / or aluminum, wherein the front flap is constructed in mixed construction and consists at least partially of steel and at least partially of aluminum.

Description

The invention relates to a front flap for a motor vehicle with an outer panel and an inner panel, which are interconnected at their peripheral outer edges, the inner panel for protecting pedestrians in a collision with the motor vehicle formed by a deformation structure head impact zone and the deformation structure at least partially limiting and having the outer edge of the inner panel forming frame.

Motor vehicles must always meet higher safety requirements. The measures to increase the passive safety of the motor vehicle concern not only the protection of the vehicle occupants, but increasingly also the protection of pedestrians or other road users in the event of a collision with the motor vehicle. In collisions of a pedestrian with a motor vehicle, especially in a frontal impact, the pedestrian is often levered in the lower leg area and strikes with his upper body or his head on the front door of the vehicle, which can lead to serious injury to the pedestrian. Of particular interest is the minimization of the head injury risk of a pedestrian, for whose determination the so-called "Head-Injury-Criteria" (HIC) was developed. To test and determine the HIC impact tests have been developed with test specimens, in which the acceleration curve of the specimen, which simulates the head of a pedestrian, on impact, for example on the front door of a motor vehicle, measured and the HIC is determined.

To minimize the HIC or to reduce the risk of injury to the pedestrian, the potential impact area of the pedestrian on the front flap must be as flexible and deformable as possible. However, only a very small clearance is available between the front flap and the units, so that the deformation path by which the front flap can yield in the event of a collision with a pedestrian is only very small. Furthermore, in order to protect the vehicle occupants in the event of a frontal impact, the front flap must meet specified stiffness requirements and be designed in such a way that a defined deformation and thus a targeted energy conversion takes place by compressing the front flap in the vehicle longitudinal direction.

In order to meet these contradictory requirements, the front flap is often designed as an assembly of the visible side of the front flap outer sheet and arranged below the outer panel inner panel, which has in a potential impact area of the head or the upper body deformation and / or stiffening elements which the front flap in the predetermined impact zones can absorb and reduce the impact energy particularly effective. Such a front door is already out of the DE 10 2005 027 124 A1 known, wherein the outer panel and the inner panel made of steel or aluminum.

Another front flap is out of the DE 299 24 443 U1 known. The sandwich panel-shaped front flap has a continuous outer panel, a continuous inner panel and an intermediate layer of an energy absorbing material disposed between the inner and outer panels, the material of the inner and outer panels being aluminum or steel. The intermediate layer is designed as a honeycomb structure, as aluminum or plastic foam or as structured polypropylene or polyurethane.

The invention has for its object to provide a suitable for pedestrian protection front flap available, which has the necessary to protect the vehicle occupant stiffness and low weight.

This object is achieved with a front flap according to the features of claim 1. The dependent claims relate to particularly expedient developments of the invention.

According to the invention, therefore, a front flap is provided in which the outer sheet is made of steel or aluminum and the inner sheet of steel and / or aluminum, wherein the front flap is at least partially made of steel and at least partially made of aluminum. Such a front flap in mixed construction has compared to a front flap, which consists entirely of steel, a much lower weight. In particular, by the components made of steel and the component stiffness associated therewith, the protection of the vehicle occupants can be ensured in a head-on collision by a defined deformation in the vehicle longitudinal direction and a targeted energy conversion. Furthermore, the deformation path in a collision with a pedestrian is much smaller than with a front flap, which is made entirely of aluminum. The front flap of aluminum and steel according to the invention thus forms the optimum compromise in terms of weight, rigidity and the requirements of pedestrian protection, in particular with regard to minimizing the HIC value.

In a particularly advantageous variant of the present invention, it is provided that the front flap has an outer sheet of aluminum and an inner sheet of steel. Due to the fact that the trained as a continuous sheet metal part and the Visible side of the front flap forming outer panel is made entirely of aluminum, the front flap has a very low weight. The required stiffness of the front flap is ensured by the inner steel sheet.

Another very convenient variant is also created by the fact that the outer sheet is made of steel and the inner sheet of aluminum. As a result of the embodiment mentioned, an optimum front flap with a good HIC value, in particular with regard to pedestrian protection, is made available. The result is a small deformation path, as in a collision of the pedestrian on the outer panel immediately much mass is coupled. A sufficient rigidity of the front door can be ensured by the fact that the sheet thickness of the inner panel made of aluminum increases and / or the frame of the inner panel is increased.

According to the invention it is further provided that the outer panel and the inner panel are interconnected by a rabbet joint, wherein in an area of the rabbet joint an additional material-locking and / or positive connection between outer panel and inner panel is provided. Aluminum has a much greater thermal expansion at higher temperatures because the coefficient of thermal expansion of aluminum is almost twice the thermal expansion coefficient of steel. The front flap can be exposed to these higher temperatures during the production process, for example in the context of cathodic dip painting and the subsequent drying or during operation of the motor vehicle, for example by solar radiation or by the waste heat of the engine. Due to the additional cohesive or positive fixing of the inner panel and the outer panel, a distortion of the front flap at high temperatures, which results from the different linear expansion of aluminum and steel, prevented and the dimensional accuracy of the front flap and a uniform Fugenmaß to the adjacent components, for example the fenders, the windshield and the front of the motor vehicle, guaranteed. Furthermore, the deformation of the front flap can be compensated at high temperatures by an introduced into the outer panel and / or the inner panel geometric crowning. In this case, targeted deformations are introduced into the sheets, which are smoothed out by applying temperature in the KTL process and the resulting thermal expansion of the respective material.

The additional fixation between the outer panel and the inner panel can be done for example by resistance spot soldering or induction soldering, by a one-sided clinching or by a trained as a socket impression in the two sheets. Furthermore, the fold region can be angled relative to the horizontally oriented front flap such that the fold region is arranged substantially perpendicular to the outer panel forming the visible side of the front flap. Another variant for additional fixation is characterized in that the inner panel has an opening in the rebate area, into which the folded end portion of the outer panel is pushed. This results in an additional positive fixation between the inner panel and the outer panel.

A further particularly advantageous embodiment of the invention provides that in the region of the hinge connection, a mass which prevents direct contact of the outer panel and the inner panel and / or seals the hinge connection is arranged. By introducing a sealant in the space between the inner panel and the outer panel in the rebate direct contact between the material of the inner panel and the material of the outer panel and the ingress of water is prevented in the rebate area. The sealing of the folding area can be done for example by PVC mass and / or by wax spraying or wax flooding. By preventing the direct contact of the steel member with the aluminum member and preventing the penetration of water into this contact portion, contact corrosion between the steel member and the aluminum member is effectively prevented. Alternatively or additionally, an adhesive between the inner panel and the outer panel can be arranged in the rebate area. By pre-gelling the adhesive or by choosing a suitable 2-component adhesive, the adhesive can cure before being exposed to the temperature in the production process, thereby preventing component warpage.

The contact corrosion takes place in particular when two different types of metal, such as aluminum and steel, are electrically conductively connected to each other. Due to the different number of electrons on the shell of the metal atoms, unequal metals always have a potential difference (voltage), which causes the so-called battery effect. As a result of the flow of electrons, the less noble of the two metals corrodes. This effect is amplified and accelerated many times by the action of an electrolyte, for example water. The contact corrosion can thus be effectively prevented by the introduction of a suitable mass in the rebate area, since the mass prevents direct contact between the sheets and additionally the penetration of water into the rebate area.

The design possibilities of the front flap are also increased by the fact that the inner panel is formed in several parts, wherein the deformation structure and the frame of the inner panel are formed as separate components and connected to each other. This results in further variants with regard to the design of the front flap, whereby it can be better and more easily adapted to the possibly changing legal requirements regarding the HIC value, the required stiffness or the desired weight.

In this case, it proves to be particularly advantageous if the outer panel and the frame of the inner panel are made of aluminum and the deformation structure is made of steel. The deformation structure formed as a grid can be connected in such an embodiment in an advantageous manner only after the KTL process with the frame of the inner panel. As a result, a heat distortion due to different materials can be prevented, since the KTL process initially only the components made of aluminum are supplied. When the two inner sheet members are bonded together, contact corrosion between the aluminum frame and the steel mesh can be prevented. To protect against corrosion, the steel component can also be powder-coated. The adhesive used must then be cured afterwards.

The connection between the frame and the deformation structure can also be done by clinching or punch riveting in addition to gluing. By clinch gluing or stamped rivet bonding results in a high head and Schälzugfestigkeit, such a connection must be made due to the required accessibility of the joint before making the seam connection between the outer panel and the frame of the inner panel.

Furthermore, it can be provided that the outer panel and the frame of the inner panel are made of steel and the deformation structure is made of aluminum. Due to the steel outer panel, an optimal HIC value can be set by the early connection of mass. The torsional rigidity is also optimally adjusted by the steel frame, whereby the aluminum deformation structure saves weight compared to a pure steel front flap.

Another particularly expedient development of the present invention is also provided in that in a connection region between the frame and the deformation structure in the frame and / or in the deformation structure, a curvature compensating for the different thermal expansion of aluminum and steel is provided. Due to the curvature, a hinge-shaped transition between the two inner sheet metal parts is made available, by which at higher temperatures a different temperature expansion without a delay of the front flap is made possible. When expanding the material of the components of the curved portion of the respective sheet can be smoothed. The connection between the frame and the deformation structure of the inner panel can be made by an adhesive and an additional fixing element.

According to the invention it is also provided that the frame of the inner panel consists of several interconnected individual frame parts. As a result, the material waste in the production of the frame can be kept low. For the connection of the individual frame parts, a joining process is required, whereby the stability and rigidity of the frame are improved by the additional soldering or welding seams.

The invention allows numerous embodiments. To further clarify its basic principle, some of them are shown in the drawing and will be described below. This shows in

1 a perspective view of a front door according to the invention for a motor vehicle;

2 a perspective view of an inner panel of in 1 illustrated front flap;

3 a first embodiment of an edge region of the front door in a schematic representation;

4 a second embodiment of an edge region of the front door in a schematic representation;

5 a third embodiment of an edge region of the front door in a schematic representation;

6 a fourth embodiment of an edge region of the front door in a schematic representation;

7 a fifth embodiment of an edge region of the front door in a schematic representation;

8th a sixth embodiment of an edge region of the front door in a schematic representation;

9 a schematic representation of a second embodiment of the inner panel of the front door in a plan view.

1 shows a front flap 1 for a motor vehicle with an outer panel 2 and one in 2 illustrated inner panel 3 , which are connected to each other at their peripheral outer edges. The inner sheet 3 has to protect pedestrians in a collision with the motor vehicle through a deformation structure 4 formed head impact zone and a deformation structure 4 surrounding frame 5 on.

According to the invention, it is provided that the front flap 1 is formed in a mixed construction consisting of steel and aluminum. Here, the outer panel 2 made of aluminum and the inner sheet 3 Made of steel.

Aluminum has a much greater thermal expansion than steel at higher temperatures because the coefficient of thermal expansion of aluminum is almost twice as high as the thermal expansion coefficient of steel. The front flap 1 may be exposed to these higher temperatures during the production process, for example in the context of cathodic dip painting and the subsequent drying, or during operation of the motor vehicle, for example by solar radiation or by the waste heat of the engine.

3 shows a border area of the front flap 1 in a schematic and sectional illustration. The outer panel 2 and the inner sheet 3 are through a rabbet connection 6 connected with each other. To the greater extent of the outer panel 2 made of aluminum opposite the inner panel 3 made of steel, has a folding flange 7 the seam connection 6 compared to the commonly used in the prior art folding flanges on a greater length. Through this extension area (ΔL) of the folding flange 7 will ensure that the seam connection 6 between the outer panel 2 and the inner panel 3 even at higher temperatures and the associated different length expansion of steel and aluminum does not solve.

In this case, one is in the area of the seam connection 6 arranged and trained as a relining adhesive mass 8th soft, so that at a different extent of the outer panel 2 and the inner panel 3 due to high temperatures or temperature differences no sign of the relining adhesive on the visible side of the outer panel 3 results.

The 4 to 7 show alternative possibilities, the outer panel 2 and the inner sheet 3 in the area of the hinge connection 6 in addition to fix, caused by high temperatures distortion of the front door 1 or the outer sheet 2 and the inner panel 3 to prevent.

The additional fixation between the outer panel 2 and the inner panel 3 For example, by a one-sided clinching or by a trained as a socket impression 9 in the two sheets 2 . 3 respectively ( 4 ).

Furthermore, the seam connection 6 such relative to the horizontally oriented front door 1 be angled that the seam connection 6 substantially perpendicular to the visible side of the front door 1 forming outer panel 2 is arranged ( 5 ).

Another variant for additional fixation is achieved in that the inner panel 3 in the area of the hinge connection 6 an opening 10 in which the folded end portion 11 of the outer panel 2 or the folding flange 7 is pushed into it. This results in an additional positive fixation between the inner panel 3 and the outer panel 2 ( 6 ).

In addition, the fixation between the outer panel 2 and the inner panel 3 also done by resistance spot soldering. Here, a solder deposit is first in the fold connection 6 introduced and then using a welding tongs or by induction soldering a solder joint between the sheets 2 . 3 produced. To prevent the contact corrosion, it is important to the solder joint or the Falzverbindung 6 good seal. The seal can be made by a PVC mass 8th respectively. Into the interior of the hinge connection 6 can by wax spraying or wax flooding an additional mass 8th' be introduced ( 7 ).

8th shows a further embodiment of the edge region of the front door 1 , where the inner sheet 3 the front flap 1 is formed in two parts. The frame 5 and the deformation structure 4 of the inner panel 3 are formed as separate components and connected together. The frame 5 of the inner panel 3 exists, as well as the outer panel 2 , aluminum and the lattice-shaped deformation structure 4 is made of steel. The lattice-shaped deformation structure 4 can in such an embodiment of the front door 1 only after the cathodic dip painting with the frame 5 of the inner panel 3 be connected so that a heat distortion can be excluded due to the different thermal expansion coefficients of steel and aluminum. The connection between the frame 5 and the deformation structure 4 done by adhesive (mass 8th ) and an additional clinched or punched rivet connection 12 , In a transition area between the frame 5 and the deformation structure 4 has the deformation structure 4 a trained as a flap curvature 13 on, which works like a hinge with different expansion of the materials or components in heat.

To an inner panel 3 with an outer frame 5 The frame is made of aluminum to minimize material waste 5 in an in 9 shown variant of several interconnected frame parts 14 composed. The individual frame parts 14 are then by an additional joining process, in particular by soldering 15 , connected with each other. Due to the additional soldered seams 15 will increase the stability and rigidity of the inner panel 3 improved.

In the case of a two-part inner panel 3 can the frame 5 and the outer panel of course also made of steel and the deformation structure 4 be made of aluminum. Likewise, a variant, after which the outer panel 2 made of steel and the inner sheet 3 completely made of aluminum, possible.

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 102005027124 A1 [0004]
• DE 29924443 U1 [0005]

Claims (10)

Front flap ( 1 ) for a motor vehicle with an outer panel ( 2 ) and an inner panel ( 3 ), which are connected to each other at their peripheral outer edges, wherein the inner sheet ( 3 ) to protect pedestrians in a collision with the motor vehicle by a deformation structure ( 4 ) formed head impact zone and a deformation structure ( 4 ) at least partially delimiting and the outer edge of the inner panel ( 3 ) forming frames ( 5 ), characterized in that the outer panel ( 2 ) made of steel or aluminum and the inner panel ( 3 ) is made of steel and / or aluminum, wherein the front flap ( 1 ) consists at least partially of steel and at least partially of aluminum. Front flap ( 1 ) according to claim 1, characterized in that the outer panel ( 2 ) made of aluminum and the inner sheet ( 3 ) is made of steel. Front flap ( 1 ) according to claims 1 or 2, characterized in that the outer panel ( 2 ) made of steel and the inner sheet ( 3 ) is made of aluminum. Front flap ( 1 ) according to at least one of the preceding claims, characterized in that the outer panel ( 2 ) and the inner panel ( 3 ) by a folding connection ( 6 ) are interconnected, wherein in a region of the hinge connection ( 6 ) an additional cohesive and / or positive connection between outer panel ( 2 ) and inner sheet ( 3 ) is provided. Front flap ( 1 ) according to at least one of the preceding claims, characterized in that in the region of the hinge connection ( 6 ) one the direct contact of the outer sheet ( 2 ) and the inner panel ( 3 ) and / or the seam connection ( 6 ) sealing compound ( 8th . 8th' ) is arranged. Front flap ( 1 ) according to at least one of the preceding claims, characterized in that the inner panel ( 3 ) is formed in several parts, wherein the deformation structure ( 4 ) and the frame ( 5 ) of the inner panel ( 3 ) are formed as separate components and connected to each other. Front flap ( 1 ) according to at least one of the preceding claims, characterized in that the outer panel ( 2 ) and the frame ( 5 ) of the inner panel ( 3 ) are made of aluminum and the deformation structure ( 4 ) is made of steel. Front flap ( 1 ) according to at least one of the preceding claims, characterized in that the outer panel ( 2 ) and the frame ( 5 ) of the inner panel ( 3 ) are made of steel and the deformation structure ( 4 ) is made of aluminum. Front flap ( 1 ) according to at least one of the preceding claims, characterized in that in a connecting region between the frame ( 5 ) and the deformation structure ( 4 ) in the framework ( 5 ) and / or in the deformation structure ( 4 ) a curvature compensating for the different thermal expansion of aluminum and steel ( 13 ) is provided. Front flap ( 1 ) according to at least one of the preceding claims, characterized in that the frame ( 5 ) of the inner panel ( 3 ) of a plurality of interconnected individual frame parts ( 14 ) consists.

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