Front-end structure for a motor vehicle

Abstract

Front-end structure (1) for a motor vehicle (5) comprising two longitudinal members (10) spaced apart from each other, each having a first deformation element (15) at its respective end, and a cross member (20) which is arranged at one end on the first deformation elements (15) and which at the other end accommodates a second deformation element (25) and a bumper cover (30), wherein in the area where the cross member (20) is adjacent to the first deformation elements (15) there is a third deformation element (35) whose stiffness is greater than the stiffness of the second deformation element (25) and whose stiffness is less than or equal to the stiffness of the first deformation element (15), characterized in thatthat the third deformation element (35) and the first deformation element (15) are arranged essentially centrally to each other and the third deformation element (35) is detachably attached to the first deformation element (15).

Description

[0001] The present invention relates to a front-end construction structure for a motor vehicle according to claim 1 and to a motor vehicle equipped therewith according to claim 5.

[0002] DE 10 2012 008 832 A1 discloses a front-end structure for a motor vehicle comprising two spaced-apart longitudinal members, each of which has a first deformation element (sometimes also called a crash box or deformation box) at its respective end, and a cross member. The cross member is arranged at one end on the first deformation elements or crash / deformation boxes and at the other end accommodates a second deformation element (usually a partially reversible medium- or low-density foam, for example, made of expanded polypropylene) and a bumper cover.

[0003] The aim of this design is to reduce the risk of injury to people involved in a crash, particularly pedestrians. The first deformation element and the second deformation element perform different functions: In a crash in which the motor vehicle collides with a low energy input (e.g. 1 kJ due to an impact with a pedestrian), the second deformation element absorbs the existing kinetic energy. In these cases, mechanical stress on the first deformation element is negligible. In a collision with a medium (e.g. from 2.5 kJ to 20 kJ in the case of a collision between two motor vehicles) to high energy input (e.g. over 25 kJ, also in the case of a collision between two motor vehicles), both the first deformation element and the second deformation element absorb kinetic energy by first deforming the second and then the first deformation element.In practice, this design has proven itself in principle, but the second deformation element has comparatively large dimensions in the vehicle's longitudinal direction (i.e., in the x-direction in a vehicle's own Cartesian coordinate system) and a relatively large depth. This consequently leads to a comparatively large overhang of the front part of the body and limitations in both the structural and aesthetic design of correspondingly equipped vehicles.

[0004] Further relevant front-end structures for motor vehicles are known from DE 10 2006 041 0985 A1 and DE 101 43 890 A1.

[0005] Finally, DE 10 2009 040 602 A1 discloses a front-end structure for a motor vehicle comprising two spaced-apart longitudinal members each having a first deformation element at their respective ends, and a cross member arranged at one end on the first deformation elements and at the other end accommodating a second deformation element and a bumper cover. In the region where the cross member is adjacent to the first deformation elements, there is a third deformation element whose stiffness is greater than the stiffness of the second deformation element, the stiffness of the third deformation element being less than or equal to the stiffness of the first deformation element.

[0006] The object of the present invention is to provide an alternative to the prior art. In particular, the object of the invention is to increase freedom in the structural and aesthetic design of motor vehicles without deviating in the slightest from the existing high safety standards.

[0007] This object is achieved by a front-end structure for a motor vehicle having the features of claim 1.

[0008] The front-end structure for a motor vehicle has two spaced-apart longitudinal members and a cross member. A first deformation element is arranged on the end of each longitudinal member, i.e. at the front in the main direction of travel of the motor vehicle. The cross member, in turn, is arranged with one section on the first deformation elements and accommodates a second deformation element and a bumper cover with a section opposite thereto. In the area in which the cross member is adjacent to the first deformation elements, there is a third deformation element whose stiffness is greater than the stiffness of the second deformation element. The third deformation element locally increases the stiffness of the front-end structure so that intrusion is reduced or even avoided in the event of a crash.Since the third deformation element is at least partially surrounded by the second deformation element due to its positioning near the first deformation element, the desired protective function for pedestrians or similar persons who collide with the motor vehicle with relatively low energy input is maintained. This is especially true if the second deformation element is located in front of the third deformation element in the main direction of travel of the motor vehicle. Overall, a suitable construction or selection of a third deformation element creates a further degree of freedom for the technical and aesthetic design of a motor vehicle without compromising the safety of road users, be they pedestrians or similar persons or vehicle occupants.

[0009] The stiffness of the third deformation element is not only greater than the stiffness of the second deformation element, but also less than the stiffness of the first deformation element, or substantially equal to the stiffness of the first deformation element, or greater than the stiffness of the first deformation element. This allows the device according to the invention to be individually adapted to a wide variety of load cases and energy inputs.

[0010] In the event of a collision with low energy input, the second deformation element can therefore still deform, particularly with a suitable selection of materials, design, and / or attachment, without the third deformation element being subjected to lasting mechanical stress. In an impact with higher energy input, the third deformation element is deformed by absorbing the kinetic energy depending on the selected stiffness. In a collision with a relatively high energy input, the third deformation element can, depending on the selected stiffness, completely collapse in order to absorb a large portion of the kinetic energy. Overall, this design not only improves the protection of those involved in a crash, but also advantageously leads to the avoidance or minimization of repair damage after a collision.

[0011] A particularly compact design of the front-end structure is achieved according to the invention in that the third deformation element and the first deformation element are arranged substantially centrally to one another.

[0012] The detachable attachment of the third deformation element to the longitudinal member, as provided according to the invention, makes the front-end structure particularly easy to produce. Furthermore, its replacement after a crash is also easily accomplished. Furthermore, this advantageously enables the front-end structure according to the invention to be easily adapted to accident-relevant country-specific requirements.

[0013] Advantageously, a particularly compact construction of the front-end structure according to the invention is achieved if the third deformation element is at least partially accommodated in the second deformation element.

[0014] For simplified and therefore cost-effective production, in particular by extrusion or casting, the third deformation element can be designed as a hollow chamber profile.

[0015] According to the invention, the third deformation element can be made of any material, for example, steel, aluminum, an aluminum foam, a fiber composite material, in particular with a glass fiber and / or carbon fiber content, a plastic, in particular an expanded polypropylene foam, or a mix of the aforementioned. For the purpose of facilitating assembly and increasing the service life of the front-end structure according to the invention, the third deformation element can be made of the same material as the first deformation element and / or the longitudinal members.

[0016] The aforementioned problem is also solved by a motor vehicle with a front-end structure of the type described. The aforementioned advantages apply accordingly.

[0017] The features of the present invention described above can be combined with one another as far as possible, even if not explicitly described above.

[0018] The following is a brief description of figures of the present invention. Fig. 1 shows a front-end structure according to the invention on a motor vehicle according to the invention in plan view. Fig. 2 shows the inventive front-end structure of the Fig. 1 without a second deformation element in a perspective top view. Fig. 3 shows a section of the Fig. 1 or 2 shown front-end structure in perspective sectional view.

[0019] The following is made with reference to Fig. 1 to 3 provide a detailed, non-prejudicial, particularly limiting, description of an embodiment of the present invention. Identical elements are provided with identical reference numerals unless otherwise stated.

[0020] Fig. 1 shows a front-end structural structure 1 according to the invention on a motor vehicle 5 according to the invention, which is shown here only symbolically, in a plan view. The front-end structural structure 1 has two longitudinal members 10, which are located in the front region of the motor vehicle 5. The longitudinal members 10, which can serve, for example, as engine mounts, have a first deformation element 15 at their respective front ends. A cross member 20 is fastened to this first deformation element in the further front region, i.e. viewed in the main direction of travel F. The cross member 20 accommodates a second deformation element 25 and a bumper cover 30. The first deformation element 15 is also known per se as a so-called crash box or deformation box. The second deformation element 25 is also known per se and can, for example, consist of a partially reversible foam made of expanded polypropylene.According to the invention, a third deformation element 35 is provided, the rigidity of which is greater than the rigidity of the second deformation element 25. Furthermore, according to the invention, the third deformation element is located in the region in which the cross member 20 and the first deformation element 15 are adjacent to one another. As . Fig. 1, a longitudinal member 10, a first deformation element 15 and a third deformation element 35 are thus located essentially parallel to one another in the x-direction of the vehicle's own Cartesian coordinate system.

[0021] This orientation is reflected in Fig. 2, whereby neither the longitudinal members 10 nor the second deformation element 25 nor the bumper cover 30 are shown here. The third deformation element 35 is flush with the first deformation element 15 and is also received in the cross member 20. This achieves a compact design of the front-end structure 1 according to the invention.

[0022] The Fig. 2 indicated section A is enlarged in Fig. 3 in section, wherein a part of the second deformation element 25 in Fig. 3 is also indicated. In the example shown here, the third deformation element 35 is designed as a hollow cross-section, which in its upper region has an outer flange 50 resting on a portion of the first deformation element 15, which is fastened to the first deformation element 15 by means of a fastening means 40, in this case a screw.

[0023] The third deformation element 35 can, in principle, be made of any material, for example, steel or plastic, in particular an expanded polypropylene foam. However, it is preferred that the stiffness of the third deformation element 35 is less than the stiffness of the first deformation element 15, or equal to the stiffness of the first deformation element 15, or greater than the stiffness of the first deformation element 15. In the event of a frontal crash, depending on the kinetic energy occurring in the frontal crash, first a deformation of the second deformation element 25 occurs, followed by a more or less pronounced deformation of the third deformation element 35 and a more or less pronounced deformation of the first deformation element 15. The third deformation element 35 is designed as a hollow cross-section, which, for example, has a depth (ieLength in the x-direction) of 35 mm and thus corresponds to approximately 1 / 2 to 1 / 3 of the length of the second deformation element 25. However, this is not mandatory; rather, another suitable length of the third deformation element 35 can also be selected. The hollow chamber of the third deformation element 35 has a number of chambers 45 (in the exemplary embodiment shown here, these are two chambers 45), the number, size and position of which within the third deformation element 35 can be calculated and designed depending on the desired deformation behavior, in particular the desired energy conversion of kinetic energy generated during a crash. List of reference symbols 1 Frontend structure 5 Motor vehicle 10 longitudinal members 15 First deformation element 20 cross members 25 Second deformation element 30 bumper cover 35 Third deformation element 40 fasteners 45 Chamber 50 outer flange A section F Main direction of travel x, y, z vehicle-specific Cartesian coordinate system

Claims

[1] Front-end construction structure (1) for a motor vehicle (5) with two longitudinal members (10) spaced apart from one another and having a first deformation element (15) at their respective ends, and with a cross member (20) which is arranged at one end on the first deformation elements (15) and at the other end receives a second deformation element (25) and a bumper cover (30), wherein in the region in which the cross member (20) is adjacent to the first deformation elements (15), there is a third deformation element (35) whose stiffness is greater than the stiffness of the second deformation element (25) and the stiffness of the third deformation element (35) is less than or equal to the stiffness of the first deformation element (15), characterized bythat the third deformation element (35) and the first deformation element (15) are arranged substantially centrally to one another and the third deformation element (35) is detachably fastened to the first deformation element (15). [2] Front-end structure (1) according to one of the preceding claims, characterized by that the third deformation element (35) is at least partially accommodated in the second deformation element (25). [3] Front-end structure (1) according to one of the preceding claims, characterized by that the third deformation element (35) is designed as a hollow chamber profile, preferably as a hollow cross-section. [4] Front-end structure (1) according to one of the preceding claims, characterized by that the third deformation element (35) consists of the same material as the first deformation element (15) and / or the longitudinal members (10). [5] Motor vehicle (5), characterized bya front-end structure (1) according to one of the preceding claims.

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