A crash box for absorbing impact energy released in an accident

Abstract

The invention relates to a crash box that can reduce high peak force values (F p ) at the time of an accident and increase the specific energy absorption by increasing the amount of energy absorbed at the time of a crash.

Description

[0001] A CRASH BOX FOR ABSORBING IMPACT ENERGY RELEASED IN AN ACCIDENT

[0002] Technical Field

[0003] The invention relates to a crash box that can reduce high peak force values (FP) at the time of an accident and increase the specific energy absorption by increasing the amount of energy absorbed at the time of a crash.

[0004] State of the Art

[0005] Crash boxes have a variety of design factors and are continuously improved by engineers to optimize their ability to absorb crash energy during accidents. These design factors include the choice of material, the location of the box, its geometry, and design variables according to the crash speed. The crash box developed by taking these factors into account aims to extend the contact time between the vehicle and the passenger and to distribute the energy.

[0006] Crash boxes, one of the passive safety systems in the car, function as shock absorption in the event of an accident, as mentioned above. During impact damping, the crash boxes are folded in themselves like an accordion by undergoing plastic deformation. During the first folding, the maximum force formed in the force-displacement graph is called the peak force (Fp) value. The high peak force values of the crash box are undesirable as they can cause the crash energy to be transmitted directly to the passenger cabin or in-vehicle equipment.

[0007] In order to increase the efficiency of energy absorbers, it is the specific energy absorption (SEA) in another data that converts the crushing energy per unit mass into strain energy by deformation. It is an important characteristic that the crash boxes have high SEA values. Increasing the SEA value is of critical importance for companies in the automotive sector. SEA is an important parameter that measures the amount of deformation that occurs in a vehicle during a crash and its ability to absorb energy. High SEA values mean that a vehicle absorbs (absorbs) energy better in the event of a crash and therefore increases driver and passenger safety.

[0008] In addition to helping to absorb the crash energy arising from vehicle accidents, the crash box is one of the important components that contribute to passenger safety. The vehicle body can be thought of as a protective shell that protects the passengers. Some systems, such as the chassis that make up the vehicle's frame system, are designed to be rigid so that they do not bend in the event of an accident and do not harm the passenger. It is in systems designed to act and deform in a way that minimizes damage to passengers. These systems, which deform and absorb the forces affecting cars in the event of a crash and consist of many components, are classified as energy absorbers. One of these components is the crash boxes called the passive safety system, which are positioned between the vehicle front / rear bumper and the chassis and folded like an accordion to reduce damage to the chassis.

[0009] If the impact energy is not adequately absorbed, the occupants of the vehicle may be exposed to high levels of energy, causing unintended consequences such as injury and death. Therefore, there are various articles, patent, or utility model applications in the current system regarding crash boxes. Some of the studies focus on increasing the energy absorption capacity of crash boxes and bumpers by applying design changes and alternative geometries that promote more deformation during crash, thus increasing the energy absorption capacity. [1] In addition, other studies investigate the effect of the materials used and aim to improve the energy absorption performance by adding metal foam into the crash boxes [2] or by investigating the energy absorption capacity of different materials. [3]

[0010] Application "US 2013 / 0193699 Al" in the state of the art relates to a polymeric crash box that can be applied in the automotive field and can be used as a temporary element, especially in the bumper part of a motor vehicle. In particular, the invention relates to a crash box produced by injection molding and having a substantially alveolar structure with a good impact strength and high hardness. The object of the present invention is to provide a polymeric crash box for a vehicle that allows for an overall reduction of the weight of the bumper structure, as well as a minimum reduction of the impact force transmitted to a frame of the vehicle. The crash box dampens or can gradually dissipate some of the kinetic energy through plastic deformation. Said system has the ability to absorb energy based on plastic deformation. Therefore, the specified crash box creates some friction that partially absorbs energy on the principle of forming folding lobes based on plastic deformation when exposed to any impact.

[0011] Application "US 2017 / 0327066 Al" in the state of the art relates to an impact energy absorption device developed for vehicles. In the invention, an impact energy absorber device is developed comprising a plurality of cells grouped together to form a matrix structure that defines the assembly region and the contact region. Thus, it is ensured that the cells are crushed along a relevant contact region. In an embodiment of the invention, each of the cells of the device is thinned outwardly in a direction from the assembly region to the contact region. In this way, it is ensured that the energy from the impacts of the device from various angles is absorbed. Said system has the ability to absorb energy based on plastic deformation. Therefore, the specified crash box creates some friction that partially absorbs energy on the principle of forming folding lobes based on plastic deformation when exposed to any impact.

[0012] Application "TR 2019 / 17284" in the state of the art relates to the assisted crash box. The subject of the invention is a supported crash box with increased energy damping capacity, especially in low-speed crashes, reducing buffer interference by providing balanced force transfer to the vehicle body. A braced crash box includes support pieces made of steel material that are attached to a lower-cost rear crash traverse assembly for this purpose. The support pieces positioned on the lower and upper surfaces of a supported crash box increase the energy damping capacity of the crash box and reduce buffer interference, especially in low-speed crashes.

[0013] There is no interlocking principle in the crash boxes in the applications of the prior art. For this reason, it cannot adequately meet the negative effects of the shock waves that occur during the crash and thus ensure energy absorption. In the current studies, the energy absorption capacities of the crash boxes with different cross-sectional geometries were examined using both the experimental and finite element methods. Another study focused on the energy absorption properties of crash boxes made of glass fiber reinforced plastic with various geometries. However, these solutions cannot adequately ensure energy absorption.

[0014] As a result, there is a need for a new technology that provides energy absorption by friction force, unlike the crash boxes that provide energy absorption by folding in a classical way due to the negativities described above and the inadequacy of the current solutions on the subject.

[0015] Brief Description and Objects of the Invention

[0016] The invention can reduce damage in the vehicle by absorbing and damping more energy during crash, thus increasing the safety of passengers.

[0017] The invention can also prevent the transmission of shock waves caused by the crash to the vehicle chassis and thus provide a more controlled energy absorption during the crash compared to the current system. With the invention, energy damping capacity has been increased in low speed or high-speed crashes and a crash box has been developed that reduces buffer interference by providing balanced force transfer to the vehicle body.

[0018] With the invention, since the folding mode starts in the last stages of the deformation, the maximum peak force (FF) value can be reduced by approximately 11%. In addition, it dampens the negative effects of impact energy better than exponentially energy-absorbing systems by increasing the specific energy absorption (SEA) value. For this purpose, there are recesses, protrusions and crushing beads on the components that make up the invention. These recesses, protrusions and crushing beads mentioned during the crash create friction force. In addition, frictional force is also created by the resistance applied by the crushing beads on the walls of the components during the collapse of the crash box formed by the components.

[0019] Descriptions of the Figures

[0020] Figure 1 : An isometric view of the crash box that absorbs energy by friction force.

[0021] Figure 2: A side view of the crash box that absorbs energy by friction force.

[0022] Figure 3: A view of the crash box subject to the invention subject to the axial impact load.

[0023] Figure 4: A view of the force-displacement graph of the crash box subject to the invention subject to the axial impact load.

[0024] Figure 5: A view of the part of the crash box where it is positioned in the vehicle.

[0025] Element Numbers Specified in the Figures

[0026] In order to better explain the crash box developed by this invention, the parts and elements in the figures are numbered and the corresponding numbers are given below:

[0027] 1. Recess

[0028] 2. Protrusion

[0029] 3. Crushing beads

[0030] 4. Component

[0031] Detailed Description of the Invention

[0032] The invention relates to a crash box positioned on the chassis in the front of the vehicle as seen in Figure 5, which can reduce high peak force values (FP) at the time of an accident and increase the specific energy absorption by increasing the amount of energy absorbed at the time of a crash. The crash box, which consists of a three-component (4) structure, operates on the principle of intertwining multiple parts when the axial impact load is applied.

[0033] The crash box developed with the invention consists of at least three components (4). There are recesses (1) and protrusions (2) on the wall of each of these components (4) positioned parallel to the vehicle frame as can be seen from Figure 5. Friction force is generated thanks to the recesses (1) and protrusions (2) placed on the side walls of the components (4) that can be intertwined during the crash. Frictional force is also created by the resistance applied by the crushing beads (3) on the walls of the components (4) during the collapse of the crash box formed by the components (4). To increase the resistance of the friction force on the side walls of the components (4), the crushing beads (3) are positioned in opposite directions. In the energy absorption process, the crushing beads (3) contribute to the folding of the crash box formed by the three component (4) and its gradual collapse for energy absorption up to its maximum capacity.

[0034] The recess (1), protrusion (2), crushing beads (3) and the component (4) on which the recess (1), protrusion (2), crushing beads (3) are positioned, which constitute the crash box made of high strength and energy absorption steel (DP600, DP800 and DP 1000) sheet profile material, which are widely used in the automotive industry, are produced by using high precision CNC sheet metal cutting and press brake bending machines. The length and width dimensions of the crash box are designed with appropriate tolerances and dimensions in terms of the standard manufacturing process. The crash box developed with the invention consists of three components (4) intertwined 10 mm in zero tolerance. For all analyses, the dimensions of the crash box, which consists of three components (4), both classical and frictional, are 235 mm long and 110 mm wide. The crushing beads (3) at the corners of the components (4) forming the crash box are positioned at the middle level of the recess (1) and protrusions (2) on the edges.

[0035] The recesses (1) and protrusions (2) in the crash box developed with said invention first penetrate each other under the axial impact load and then continue to absorb energy by folding the components (4) on top of each other until they reach the maximum energy absorption capacity.

[0036] The friction crash box is assembled with three components (4) intertwined with 10 mm overlap without tolerance. When an axial force is applied as in Figure3, no joining element is used in order not to prevent the intertwining of the three components (4). As can be seen in r?

[0037] Figured, it was observed that the maximum peak force (p) value decreased by approximately 11% since the folding mode started in the last stages of the deformation. When the effect of the energy absorbed by the friction force on the deformation behavior of thin-walled structures is evaluated numerically, it is seen that the frictional crash box increases the specific energy absorption by 16% and the total absorbed energy (ET) performance by 26% compared to the existing crash boxes. It can be seen from Figure 4 that the friction force and energy absorption have the ability to improve the crash resistance of the vehicles.

[0038] The three peak force values (FP) corresponding to the contact of the rigid object with each component (4) forming the crash box are read from the graph in Figure 4. It can be seen from Figure 4 that the kinetic energy of the rigid body is initially transmitted to the first part in the inner section, then to the second part in the middle section at the deformation distance of 84mm, and finally to the third part in the outer section at the deformation distance of 175mm. This sequential force transfer contributed decisively to the energy absorption of the crash box.

[0039] The rigid object transmitted force to the three components (4) forming the crash box. The energy transfer is expressed in the graph in Figure 4, respectively, to the inner, middle, and outer component. In the systems that absorb energy by folding in a single component normally, the peak force is formed during the first folding, while in the new system that absorbs energy by the multi-component friction force, the maximum peak force is reached in the later stages of the deformation process since they begin to fold after being intertwined.

[0040] References

[0041] [1] Gabriel Jiga, §tefan Stamin, Gabriela Dinu, Daniel Vlasceanu, Dorina Popovici, Material and shape crash-box influence on the evaluation of the impact energy absorption capacity during a vehicle collision, Ciencia & Tecnologia dos Materials, Volume 28, Issue 1, 2016, Pages 67-72, ISSN 0870-8312, https : / / doi . . ct t.2016.03.001 .

[0042] [2] A.K. Toksoy, M. Giiden, Partial Al foam filling of commercial 1050H14 Al crash boxes: The effect of box column thickness and foam relative density on energy absorption, Thin- Walled Structures, Volume 48, Issue 7, 2010, Pages 482-494, ISSN 0263-8231, https: / / doi.Org / 10.1016 / j.tws.2010.02.002.

[0043] [3] M. Seitzberger, F.G. Rammerstorfer, R. Gradinger, H.P. Degischer, M. Blaimschein, C. Wai ch, Experimental studies on the quasi-static axial crushing of steel columns filled with aluminium foam, International Journal of Solids and Structures, Volume 37, Issue 30, 2000, Pages 4125-4147, ISSN 0020-7683, https: / / doi.org / 10.1016 / 80020-7683(99)00136-5.

Claims

CLAIMS1. A crash box for absorbing impact energy released in an accident, characterized in comprising;• Recesses (1) and protrusions (2) positioned on side walls of components (4) parallel to vehicle frame,• At least three components (4) that provide damping interlocking in a crash by means of friction force created during crash by the recesses (1) and protrusions (2) positioned on side walls and crushing beads (3) positioned on corners of the side walls.

2. A crash box according to claim 1, characterized in that crushing beads (3) positioned in opposite directions to increase the resistance of the friction force on the side walls of the components (4).

3. A crash box according to claim 1, characterized in that the recesses (1), protrusions (2), crushing beads (3) and the components (4) on which the recesses (1), protrusions (2), crushing beads (3) are positioned, are made of dual -phase steel having high strength and energy absorption ability.

4. A crash box according to claim 1, wherein length of the components (4) is 235 mm.

5. A crash box according to claim 1, wherein width of the components (4) is 110 mm.

6. A crash box according to claim 1, characterized in comprising crushing beads (3) at the corners of the components (4) forming the crash box where crushing beads (3) are positioned midway between the recesses (1) and protrusions (2) on the edges.

Images