The present invention relates to a motor vehicle having a body with a preform element or a preform structure, and in particular to a motor vehicle having a body with a preform structure that allows an optimized connection between two or more preform elements.
In the automotive industry, the increase in electrically operated vehicles is being accompanied by a growing demand for lightweight and also resource-conserving solutions for increasing energy efficiency. Fiber composite materials are becoming ever more established in association with lightweight construction.
On account of their outstanding mechanical properties, components of carbon-fiber-reinforced plastic form a major group among the fiber composite materials. The numerous advantages of carbon-fiber-reinforced plastic components over conventional components, such as for example great stiffness, corrosion resistance, stress-appropriate design, etc., are consequently also of interest for the automotive industry.
On account of the production sequences in the automotive industry, so-called performs or preform elements, which have already been brought into a form adapted to the application, are used. Preforms and preform elements, or preforms for short, are often produced from a layering of fiber mats, which are placed together and cut, and already brought into the necessary three-dimensional form.
Because of the sometimes complex structures in automobile construction, often two or more preforms or preform elements are connected together to form an overall structure. In an interfacial region, the individual preforms or preform elements have to be connected. Since a butt joint is generally not advisable for reasons of stability, the connection generally takes place by an overlapping of the adjoining border regions.
In spite of overlapping, it is generally intended to avoid a step, at least on one side of the connection. Since the preforms or preform elements have a certain wall thickness, in a preform element the border region is often cranked, i.e. has a double bend, in which the level of the surface is set back by the material thickness of the adjoining preform element.
In the case of fiber composite materials, in particular also carbon-fiber-reinforced plastics, there is a material-weakening offset of the wall in this region. In order to achieve a minimum stability, reinforcement would be necessary in the region of a weakening of the material, but in turn results in an increase in weight.
Against this background, an object of the present invention can be considered to be that of providing a preform structure that has a greater stability with regard to a connection of two or more preform elements with the same weight or a lower weight with the same stability.
According to an embodiment of the invention given by way of example, a motor vehicle including a body with preform elements is provided, having a first stack of a plurality of fiber mats with a common first outer contour, a first preform area, a first preform border region and a first preform edge.
The first preform edge delimits at least part of the outer contour, wherein the first border region extends between the preform area and the first preform edge, wherein the preform border region is separated from the preform area adjoining it by a first bend and the first border region is inclined with respect to the first preform area adjoining it.
In this way it is possible to provide a preform element which, on account of its inclined and angled-away border region, can be connected to a corresponding part of a further preform element, so that a weak point created by a crank (elbow) can be avoided.
According to a further embodiment of the invention given by way of example, a motor vehicle having a body with a preform structure is provided, with a preform element as described above and a second preform element. The second preform element has a second stack of a plurality of fiber mats with a common second outer contour, a second preform area, a second preform border region and a second preform edge.
The second preform edge delimits at least part of the second outer contour, wherein the second border region extends between the second preform area and the second preform edge. The first border region and the second border region form an overlap.
In this way it is possible to provide a preform structure that is made up, for example, of two preform elements, wherein a material-weakening crank or double step in a preform structure can be avoided at the connecting region between the first preform element and the second preform element by the configuration of a bent-away and inclined border region of at least one preform element.
It is important here that the preform elements can be prefabricated separately, and can be connected to one another in the prefabricated form. In particular, the configuration of the previously described preform structure with the preform elements makes it possible for example to avoid individual fiber layers alternately overlapping one another in the border region of the two preform elements.
By contrast with the embodiment described above, fabrication of preforms is not possible when there is an alternating overlap of the individual fiber layers of two adjoining fiber layer stacks. Rather, the individual fiber layers must be individually laid on in an adjoining overlapping manner, which inevitably means that a great amount of work is involved. In the case of a preform, however, the prefabrication is performed on the basis of the form and dimensions of a fiber layer stack.
Therefore, a connection of the preform elements must be performed in some way other than an alternating overlap of individual layers. In particular, the preform structure according to the invention can also be used in the fabrication of large numbers of articles, particularly because a time-consuming alternating overlap of the adjoining fiber layer stacks can be avoided by the special configuration of the preform border regions with an inclination and a bend in delimitation with respect to an adjoining preform area.
According to an embodiment of the invention given by way of example, the fiber mats are carbon fiber mats. In this way it is possible to provide a lightweight material that has great stability and, according to current knowledge, is harmless with respect to both environmental and health aspects.
According to embodiments of the invention given by way of example, the carbon fiber mats are woven. In this way it is possible to provide a structure of a fiber mat that is in itself already pre-stabilized. In addition, it is possible to apply different weaving patterns, which are in particular reflected in different forms that a fiber mat stack is intended to take.
According to an embodiment of the invention given by way of example, the carbon fiber mats are laid in such a way that the carbon fibers are aligned substantially the same and are stitched transversely. In this way, an increase in the thickness of the carbon fiber mats can be avoided by a laid structure, in particular if a thread for the transverse stitching is thinner than the stitched carbon fiber structure.
According to an embodiment of the invention given by way of example, the second preform border region is separated from the second preform area adjoining it by a second bend and the second border region is inclined with respect to the second preform area adjoining it. In this way, the at least two preform elements have border regions bent away in a coinciding manner, so that a substantially symmetrical connection can be produced in the overlapping region.
According to an embodiment of the invention given by way of example, the first preform border region and the second preform border region, respectively, abut one another in an overlapping manner on one side, which lies away from the respective bending direction. In this way it is possible to produce a connection in which the two preform areas of the two preform elements adjoining one another can lie on a plane without an offset in relation to one another, while the preform border regions can overlap one another as a result of the bending away.
According to an embodiment of the invention given by way of example, the second border region has an increasing reduction of a material thickness of the second preform element in the direction of the second preform edge. In this way it can be achieved that the preform structure is not obtrusive in the overlapping region on one side, and consequently a uniform, continuous level of the two preform areas and of the overlapping region is possible.
According to an embodiment of the invention given by way of example, the overlap is widened in the direction of an edge of the preform structure in a structure edge region. In this way it can be achieved that there is a greater overlap in particular in an edge region that is usually subjected to greater stress, and consequently the edge stability of the preform structure is reinforced, in particular, in the transitional region from a first preform element to a second preform element.
According to an embodiment of the invention given by way of example, at least one out of the first border region and the second border region has a smaller material thickness than the material thickness of the corresponding adjoining preform area in such a way that a set-back step is created at the corresponding bend on the side facing away from the bending direction.
In this way, the overlapping region can be made thinner, so that the overlapping region has a smaller thickness than the sum of the material thickness in the first preform area region and the material thickness in the second preform area region. In other words, with the same material thickness of the two preform areas, the overlapping region can be made thinner than twice the material thickness.
According to an embodiment of the invention given by way of example, the first border region goes over laterally in the direction of and up to a structure edge into a first border edge region, and the second border region goes over laterally in the direction of and up to the structure edge into a second border edge region.
One out of the first border edge region and the second border edge region is unbent with respect to the corresponding adjoining preform area and the other out of the first border edge region and the second border edge region is set back in the bending direction with respect to the corresponding preform area in the overlapping region by a material thickness of the one preform element.
The side of the one border edge region facing away from the overlap and the area oriented in the same direction of the preform area adjoining the other border edge region have a coinciding level.
In this way, one and the same level of the preform element areas and the overlapping region can be provided in particular in a structure edge region on one side, so that, for example, flat-abutting flanges can be applied to the preform structure, in particular in the border region. In particular, the flanges can in this way be fabricated unbent, bringing about the advantageous effect of the preform structure with bent-away edge regions away from the structure edge regions.
It should be understood that the individual features described above are of course also combined with one another, whereby in some cases even advantageous effects that go beyond the sum of the individual effect can be obtained.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of one or more preferred embodiments when considered in conjunction with the accompanying drawings.