Absorption element and assembly method

Abstract

Absorption element (1) for use in a road vehicle for absorbing energy in an impact situation with a metal tube (4) which forms a cavity (6) and is closed at each end by a connecting plate (5) and a rear wall (4a), characterized in that insert elements (7) made of an energy-absorbing plastic are installed axially between the connecting plate (5) and the rear wall (4a).

Description

[0001] The invention relates to an absorption element for use in a road vehicle for absorbing energy in an impact situation, comprising a metal tube which forms a cavity and is closed at each end by a connecting plate and a rear wall.

[0002] The invention also relates to a method for assembling an absorption element. State of the art

[0003] Bumpers are positioned transversely at the front and rear of a motor vehicle, between the body's plastic cladding and the vehicle's frame. To prevent damage to the vehicle structure in low-speed frontal or rear impacts, deformation elements, or impact absorption elements, are integrated. These impact absorption elements are thin-walled, typically rectangular components made of steel, aluminum, or plastic. They can be manufactured by joining pressed sheet metal shells or as a single piece, for example, as an extruded aluminum profile.

[0004] Positioned between the vehicle's longitudinal frame member and the bumper crossmember, impact absorption elements absorb the kinetic energy resulting from an impact by converting it into deformation work. This prevents permanent damage to the longitudinal frame member when a critical load level is exceeded. The impact absorption elements are typically adapted to the vehicle structure and its specific requirements. Furthermore, they must meet the diverse requirements of legal regulations, as well as varying vehicle weights and material hardness. Therefore, the impact absorption elements are designed to be vehicle-specific. Ideally, the impact absorption elements should absorb as much energy as possible while simultaneously minimizing the vehicle's additional weight.

[0005] Impact absorption elements are known from the prior art. WO 2012 / 040 826 A1 describes a scalable impact absorption element whose cross-section consists of a 10-sided polygon. The described impact absorption element is symmetrical about a central axis. The previously known absorption element is designed for use in a road vehicle to absorb energy in an impact situation and consists of a metal tube that forms a cavity and is closed at each end by a connecting plate and a rear wall.

[0006] Depending on the requirements of the specific vehicle, crash management systems may utilize thick walls and axially long boxes. Furthermore, due to design limitations, an efficiency of "only" 90% can be achieved.

[0007] The thick walls result in high weight when using steel, while aluminum also incurs high material costs. The energy dissipation efficiency cannot reach the optimal 100%.

[0008] Therefore, especially for rail vehicles, there is another approach using a combination of materials.

[0009] From EP 2 072 370 A1, an energy-absorbing device is known, comprising a regeneratively designed damping element for damping tensile and impact forces occurring during normal driving operation, and a destructively designed energy-absorbing element. The energy-absorbing element is designed to activate upon exceeding a predetermined critical impact force and to convert at least a portion of the impact forces transmitted via the energy-absorbing device into heat and deformation work through plastic deformation. Suitable damping elements include, for example, rubber spring elements arranged between the two pressure plates. This energy absorption is reversible.

[0010] From DE 22 62 293 A an absorption element for absorbing energy in an impact situation with a metal tube is known, wherein an insert element is installed between a connecting plate and a back wall.

[0011] The object of the invention is to propose an improved absorption element for a road vehicle that meets the requirements for deformation and stability while maintaining low weight. Description of the invention

[0012] The problem is solved with an absorption element for use in a road vehicle to absorb energy in an impact situation with a metal tube that forms a cavity and is closed at each end by a connecting plate and a back wall, wherein insert elements made of an energy-absorbing plastic are installed axially between the connecting plate and the back wall.

[0013] The combination of metal and plastic allows for an improved design of the absorption element. The use of the elastic plastic makes it possible to design the walls of the metal tube with a reduced thickness, thus saving material.

[0014] The metal tube has a cross-section that is at least four-sided.

[0015] The design of the metal tube can vary.

[0016] The insert elements have a cylindrical shape. Other cross-sections for the insert elements are possible, deviating from this cylindrical shape.

[0017] The insert elements feature structures such as grooves and ring areas.

[0018] The insert elements have devices on their base surfaces for attachment to the connection plate and / or the back wall.

[0019] The insert elements have a central bore into which a mandrel is pressed.

[0020] The insert elements have projections on their base surfaces that engage in corresponding recesses in the connecting plate and / or the back wall.

[0021] The task can also be solved using a method for assembling an absorption element with the following steps: Attaching and securing the insert elements to the connection plate Attaching the metal tube to the connection plate Attaching the metal tube to the connection plate Sealing the cavity of the metal tube with the insert elements against the back wall.

[0022] The metallic absorption element's functionality is supported by an insert made of energy-absorbing plastic. Description of the characters Fig. Figure 1 shows an absorption element at its installation location in the prior art. Fig. 2 and Fig. Figure 3 shows an absorption element according to the invention, Fig. 4 and Fig. Figure 5 shows an example of an insert element.

[0023] In Fig. Figure 1 shows the installation location of the absorption element. The absorption element 1 is located between a cross member 3 and a connection plate 5. The connection plate 5 serves as a flange to attach the absorption element to a longitudinal member of the vehicle, which is not shown. Due to their ease of manufacture, conventional absorption elements with a square or rectangular cross-section are frequently used. Since an absorption element with a polygonal cross-section has significantly higher strength and stiffness, such absorption elements are increasingly being used. Fig. Figure 1 shows, for example, an octagonal absorption element extending along an axial axis a.

[0024] An absorption element can be formed in one or more sections, for example by bending, rolling, punching, pressing, drawing, hydroforming, molding, extrusion, cutting and forging.

[0025] The sections formed in this way can be joined by welding, gluing, fastening or other known joining techniques, forming a cavity.

[0026] Fig. 2 and Fig. Figure 3 shows the solution according to the invention, wherein the absorption element 1 is constructed from a metal tube 4 with arbitrary cross-sectional shapes. In the exemplary embodiment, four insert elements 7 can be seen in the cavity 6 of the metal tube 4.

[0027] The insert elements 7 each extend from the connection plate 5 to the rear wall 4a of the metal tube 4.

[0028] The insert elements are designed as circular cylinders and consist of an energy-absorbing plastic material. The plastic material can be machined to influence the elastic properties of the insert elements 7. In the illustrated embodiment, the insert elements 7 have circular grooves 7a. These grooves can have different axial lengths. The ring sections 7b remaining between the grooves 7a have the same or different axial lengths.

[0029] The insert elements 7 lie with their base surfaces 7d and 7c against the respective walls of the metal tube 4.

[0030] In the embodiment of the Fig. Figure 4 shows a mandrel 8 which is inserted into a central bore 10 of the insert element 7. This mandrel serves, firstly, to influence the elastic properties of the insert element, but can also be used to fasten the insert element to the connecting plate 5 via the base surface 7d.

[0031] Fig. Figure 5 schematically shows another fastening option. The insert element 7 has a projection 9 on its base surface 7d, which is inserted into a corresponding receiving opening in the connection plate 5.

[0032] During assembly, all insert elements 7 are first attached to, or inserted into, the connection plate 5. The prefabricated metal tube with its back panel 4a is placed onto the insert elements 7 and connected to the connection plate 5. If this is done under a certain amount of tension, it is not necessary to also attach the insert elements 7 to the back panel 4a. It is possible to simply provide a recess or to form a small guide contour in the back panel.

[0033] The insert elements 7 can be attached to the connection plate 5 in different ways. For example, inserting them into a designated opening and securing them with a specially designed pin have already been discussed. Reference symbol: 1 absorption element 3 impact crossbeams 4 tubes 4a Back wall 5 Connection plate 6 Cavity 7 Insert element 7a Nut 7b Ring area 7c, 7d Floor area 8 Dorn 9 Cantilever 10 Drilling

Claims

[1] Absorption element (1) for use in a road vehicle for absorbing energy in an impact situation with a metal tube (4) which forms a cavity (6) and is closed at each end by a connecting plate (5) and a rear wall (4a), characterized by , that insert elements (7) made of an energy-absorbing plastic are installed axially between the connection plate (5) and the rear wall (4a). [2] Absorption element (1) according to claim 1, characterized by , that the metal tube (4) has a cross-section of at least four squares. [3] Absorption element (1) according to one of claims 1 or 2, characterized by , that the insert elements (7) have a cylindrical shape. [4] Absorption element (1) according to any one of the preceding claims, characterized by that the insert elements (7) have structures such as grooves (7a) and ring areas (7b). [5] Absorption element (1) according to any one of the preceding claims, characterized by, that the insert elements (7) have on their base surfaces (7c, 7d) devices for fastening to the connecting plate (5) and / or the rear wall (4a). [6] Absorption element (1) according to any one of the preceding claims, characterized by that the insert elements (7) have a central bore (10) into which a mandrel (8) is pressed. [7] Absorption element (1) according to any one of the preceding claims, characterized by , that the insert elements (7) have projections (9) on their base surfaces (7c, 7d) which engage in corresponding recesses in the connecting plate (5) and / or the back wall (4a). [8] Method for assembling an absorption element (1) according to one of the preceding claims comprising the following steps: Attaching and securing the insert elements (7) to the connection plate (5). Attaching the metal tube (4) to the connection plate (5). Attaching the metal tube (4) to the connection plate (5). Closing the cavity (6) of the metal tube (4) with the insert elements (7) with the back wall (4a).

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