Energy-absorbing device with pedestrian protection function for a motor vehicle and motor vehicle having such an energy-absorbing device

Abstract

The energy-absorbing device according to the invention for a motor vehicle with pedestrian protection has a deformation structure (10) which is switchably deformable at different force levels depending on the impulse. The energy-absorbing device also has a sensor carrier (20) which is arranged parallel to the deformation structure and projects beyond the deformation structure in the direction of deformation towards the outside of the vehicle. The sensor carrier is configured to hold a crash detection sensor (21).

Description

TECHNICAL FIELD

[0001] The invention relates to an energy-absorbing device with pedestrian protection for a motor vehicle, for example a passenger car or a truck, having a deformation structure which is switchably deformable at different force levels depending on the impulse. BACKGROUND

[0002] Known front ends of motor vehicles have, for example, a bumper beam which is fixed on the front end of the longitudinal beam and a bumper cover between which a soft foam is arranged which is deformable at a relatively low load level in order to protect pedestrians. The soft foam is provided for pedestrian protection in order to protect pedestrians, if necessary, from direct or indirect collisions with the hard, rigid structure of the motor vehicle, for example the bumper beam.

[0003] In addition, there is the requirement that the motor vehicle remains undamaged in the event of a collision in a very low speed range, for example up to 4 km / h, in which the pedestrian protection is not relevant due to the low speed. For this purpose, the intrusion depth of the collision partner is to be as small as possible.

[0004] In addition, at slightly higher speeds, which are also not relevant for the pedestrian protection, it is required that the damage in the event of a collision is as small as possible and that the cooler structure, for example in the region of the front end of the vehicle, is not damaged. For this purpose, it is helpful if the structure located in front of the bumper beam already has sufficient ability to absorb the collision energy. For this purpose, the intrusion depth of the collision partner is also to be as small as possible.

[0005] The various requirements are partly contrary to one another and require a relatively long vehicle overhang at the vehicle head and thus greater weight and an adverse effect on the driving dynamics.

[0006] In order to solve the resulting target conflicts, it is proposed in DE 102010054641 A1, for example, that a bumper assembly with a beam is fixed on the vehicle body by means of a crash box. A pedestrian protection element for soft impact on pedestrians is formed in front of the beam in the driving direction. In addition, a deflectable energy-absorbing element is provided which can be deflected in front of the pedestrian protection element and thus enable a high energy absorption in the event of a collision in which a higher collision energy absorption capacity of the motor vehicle collision structure is required.

[0007] DE 102012112636 A1 also shows a bumper assembly with a bumper beam and a pedestrian protection element which can be converted from a rigid state into a relatively soft state for pedestrian protection by means of an actuator.

[0008] The bumper assemblies described in DE 102010054641 A1 and DE 102012112636 A1 have in common that for this purpose a crash sensor or a pre-crash sensor is required, according to the output signal of which it is possible to switch between a state of the crash structure which is hard and inflexible with a high crash energy absorption capacity and a state of the crash structure which is soft with a low crash energy absorption capacity which is advantageous for pedestrian protection.

[0009] It is also known from DE 102016204264 A1 a deformation structure of this type having at least a first layer and a second layer which are arranged at a distance from one another in the deformation direction or load direction and displaceable relative to one another. The first layer and the second layer have complementary protrusions and recesses which are configured such that the protrusions of the first layer and the recesses of the second layer and the protrusions of the second layer and the recesses of the first layer can sink into one another. The first layer and the second layer are connected to one another by deformable web elements such that in the case of a large impulse in the deformation direction the protrusions of the first layer sink into the recesses of the second layer and the protrusions of the second layer sink into the recesses of the first layer such that the deformation of the deformation structure in the deformation direction takes place at a relatively low force level and such that in the case of a small impulse in the deformation direction the protrusions of the first layer hit onto the protrusions of the second layer so that a further deformation of the deformation structure in the deformation direction takes place at a relatively high force level.

[0010] However, the switchable deformation structure makes it difficult to provide a reliable crash detection sensor. SUMMARY

[0011] It is the task of the present application to provide an energy absorption device for a motor vehicle having a deformation structure which can be switched depending on the impulse and a motor vehicle having such an energy absorption device, in which a crash can be reliably detected.

[0012] To this end, the application proposes an energy-absorbing device for a motor vehicle having pedestrian protection, which has a deformation structure that is switchably deformable at different force levels depending on the impulse and a sensor carrier that is arranged parallel to the deformation structure in the direction of deformation and protrudes beyond the deformation structure in the direction of deformation toward the outside of the vehicle and serves as a holder for a crash-detection sensor, the deformation structure comprising at least a first layer and a second layer, which are arranged at a distance from one another in the direction of deformation and are displaceable relative to one another, the first layer and the second layer having complementary protrusions and recesses, which are configured such that the protrusions of the first layer can sink into the recesses of the second layer and the protrusions of the second layer can sink into the recesses of the first layer, the first layer and the second layer being connected to one another by a deformation-control mechanism such that, in the case of a high impulse in the direction of deformation, the protrusions of the first layer sink into the recesses of the second layer and the protrusions of the second layer sink into the recesses of the first layer, so that the deformation of the deformation structure in the direction of deformation takes place at a low force level, and such that, in the case of a low impulse in the direction of deformation, the protrusions of the first layer hit against the protrusions of the second layer, so that the deformation of the deformation structure in the direction of deformation takes place at a high force level, wherein the protrusions of the second layer also have steps and the protrusions of the first layer have steps that are complementary to the steps of the second layer, such that, in the case of a low impulse in the direction of deformation, the opposite steps and complementary steps hit against one another and form a form-locking engagement in the lateral direction.

[0013] The application also proposes a motor vehicle having an energy-absorbing device according to the application, which is arranged between a vehicle-skin element and a vehicle-body carrier element.

[0014] The energy-absorbing device for a motor vehicle having pedestrian protection according to the application has a deformation structure that is switchably deformable at different force levels depending on the impulse. The energy-absorbing device also has a sensor carrier that is arranged parallel to the deformation structure and protrudes beyond the deformation structure in the direction of deformation toward the outside of the vehicle. The sensor carrier is configured for holding a crash-detection sensor.

[0015] The direction of deformation can essentially coincide with the longitudinal direction of the vehicle. The direction of deformation corresponds to the direction of potential impact. The sensor carrier protrudes relative to the deformation structure such that a first impact load acts first on the sensor carrier in the event of an impact. By means of the impact load acting on the sensor carrier, the crash-detection sensor can detect the impact load. In this way, an impact can be detected. In particular, an impact can be detected, as a result of which the deformation structure is loaded by the impact load.

[0016] Preferably, the deformation structure and the sensor carrier are arranged directly adjacent to each other.

[0017] According to a preferred development of the energy-absorbing device according to the application, the sensor carrier is deformable at a low force level.

[0018] The low force level means that the sensor carrier is deformable at a force level which is at most the force level at which the deformation structure begins to deform (before the conversion of the impulse according to the deformation structure takes place). The low force level for deforming the sensor carrier is for example at most 1 kN. The stroke at which the sensor carrier is deformable at the low force level is for example 30 mm.

[0019] Thus, the sensor device can detect a collision more easily or with greater accuracy.

[0020] Advantageously, the sensor carrier consists of foam, for example pedestrian protection foam which is usually arranged between a bumper cover and a bumper beam. The foam can be made of foamed polypropylene, for example foamed polypropylene with a density of 30 g / l.

[0021] Advantageously, the collision detection sensor is used to detect a collision with a person, so that active pedestrian protection measures can be introduced in the event of a detected collision. Active pedestrian protection measures can include lifting a front cover or / and releasing a pedestrian protection airbag.

[0022] According to a development of the application, the collision detection sensor comprises a deformable gas-filled hose and a pressure measuring device for measuring the gas pressure in the hose.

[0023] If the hose is deformed as a result of a collision, a change in the pressure in the hose results therefrom, so that a collision can be concluded.

[0024] Advantageously, the collision detection sensor is arranged at an outer end of the sensor carrier. The outer end refers to the end of the sensor carrier which faces outwards from the vehicle. With regard to the direction of deformation or collision, the outer end is the front end of the sensor carrier.

[0025] Thus, the collision load acts as directly as possible on the collision detection sensor, so that a collision can be detected more reliably and more quickly.

[0026] According to a further development of the application, the deformation structure has at least one first layer and one second layer, which are arranged spaced apart from one another in the deformation direction or load direction and displaceable relative to one another. The first layer and the second layer have complementary protrusions and recesses, which are configured such that the protrusions of the first layer and the recesses of the second layer and the protrusions of the second layer and the recesses of the first layer can sink into one another. The first layer and the second layer are connected to one another by a deformation control mechanism, such that, in the case of a high impulse in the deformation direction, the protrusions of the first layer sink into the recesses of the second layer and the protrusions of the second layer sink into the recesses of the first layer, in order for the deformation of the deformation structure in the deformation direction to take place at a relatively low force level, and such that, in the case of a small impulse in the deformation direction, the protrusions of the first layer come onto the protrusions of the second layer, in order for a further deformation of the deformation structure in the deformation direction to take place at a relatively high force level or for a higher force to be able to be transmitted by the deformation structure.

[0027] The deformation structure can be deformed at different energy levels and thus has different stiffnesses depending on the load situation, i.e. the impact impulse. Here, the "switching" between the two stiffnesses takes place automatically independently of a sensor device or actuator. Here, the setting of the stiffnesses is achieved by the defined, geometrically complementary configuration of the first layer and the second layer and the connection of these layers via the deformation control mechanism. In the case of a small impulse, the protrusions of the oppositely arranged layers come onto one another. By virtue of the separate configuration of the layers and the deformation control mechanism, the deformation structure can be manufactured cost-advantageously using manufacturing methods which are suitable for mass production. The requirements placed on the deformation control mechanism, which is to control the deformation of the deformation structure, are also different from the requirements placed on the layers, which should be sufficiently rigid and hard, if necessary, in order to transmit sufficient force, in particular in the case of a small impulse, so that the separate manufacture allows greater freedom in the design according to requirements.

[0028] Advantageously, the deformation control mechanism can have a plurality of elastically deformable control tabs. The control tabs connect the layers to one another and determine, in particular, the mutual distance of the layers in the initial position and the kinematics or movement characteristics of the layers in the case of the application of a load in the impact direction depending on the level of the impact impulse.

[0029] The elastic configuration of the control tabs makes the deformation of the deformation structure reversible, at least in certain cases.

[0030] According to a preferred development, at least two deformation control mechanisms are provided. Here, advantageously, the deformation control mechanisms are arranged on oppositely arranged end portions or end sections of the first layer and the second layer and are connected to the first layer and the second layer.

[0031] Thus, the deformation of the deformation structure can be better controlled under load.

[0032] According to one preferred development of the deformation structure, the first and second layers are respectively formed integrally as a die casting, in particular of plastic.

[0033] Thus, the layers can be produced cost-effectively in large quantities. Thus, the deformation structure can also be formed sufficiently easily.

[0034] According to another preferred development, the first and second layers are respectively formed integrally by sheet metal forming. In particular, the layers are produced by deep drawing or roll forming. Here, the layers can be produced from sheet steel or light metal sheet.

[0035] Thus, the layers can also be produced cost-effectively in large quantities. Particularly rigid stable layers can also be formed from sheet metal.

[0036] According to another preferred development of the deformation structure, the first and second layers are respectively formed integrally as an extruded profile, in particular an aluminum extruded profile.

[0037] Thus, the layers can also be produced cost-effectively in large quantities with respect to weight and high rigidity under load with low impact.

[0038] According to one development, the first layer and the second layer can also be moved parallel to one another in one direction by the deformation control mechanism.

[0039] In particular, the deformation control mechanism can be designed such that it fails brittlely and / or plastically in the case of high impact and can be reversibly elastically deformed in the case of low impact. The deformation control mechanism can have control links which act in a manner similar to the kinematics of a hinge. Here, the control links can enable a deflection movement of the first and second layers relative to one another, in the course of which the first and second layers are displaced parallel to one another and in the direction of deformation (towards one another).

[0040] Thus, a defined deflection movement of the first and second layers towards one another is possible and can reliably assume a position of increased rigidity of the first and second layers relative to one another.

[0041] In the case of a high collision impulse, the failure of the control web impedes the deflection movement of the first layer and the second layer relative to one another. Because of the failure of the control web, the first layer and the second layer move essentially only in the deformation direction towards one another without lateral deflection movement.

[0042] Preferably, in the deformation structure according to the application, the first layer and the second layer are essentially congruent.

[0043] This facilitates the production of the deformation structure. Thus, the complementary protrusions and recesses are also realized in a simple manner.

[0044] According to a preferred development of the deformation structure, the protrusions of the first layer and the recesses of the second layer and the recesses of the first layer and the protrusions of the second layer are arranged opposite one another in the initial state of the deformation structure.

[0045] Thus, in the case of a small collision impulse, the deformation structure can be deformed in the deformation direction at a relatively low force level.

[0046] According to a particularly preferred development, the first layer and the second layer are each formed in the form of a wave plate. Here, the crests and troughs form the protrusions and recesses.

[0047] Preferably, the protrusions and recesses (crests and troughs) can have a trapezoidal shape.

[0048] By means of the geometric configuration, the protrusions and recesses of the opposite layers can easily be moved into one another.

[0049] According to the application, the deformation structure can have a plurality of layers, wherein two adjacent layers each form a first layer and a second layer. The deformation structure can for example have three, four, five, six or more layers.

[0050] It is furthermore preferred that one or both outer layers, i.e. the outer or end layers, are formed positionally fixed.

[0051] Preferably, the deformation structure has an odd number of adjacent layers, which are formed in pairs as the first layer and the second layer.

[0052] Thus, the two outermost layers can be formed positionally fixed. Here, in the case of a small impulse or applied force, only the layers arranged between the outermost layers are displaced in the lateral direction.

[0053] A particularly preferred deformation structure has exactly three layers.

[0054] This is the smallest unit in which the two outermost layers are positionally fixed. In this case, only the intermediate layer, which can be the second layer for example, is subjected to parallel movement with respect to the two outermost layers in the case of a small impact.

[0055] Advantageously, the deformation control mechanism is designed in such a way that adjacent layers can be displaced in opposite directions in the case of a small impact. Here, the "displacement action" refers, for example, to a deflection movement of the layers in opposite directions.

[0056] Thus, a uniform deformation of the deformation structure having a plurality of layers is achieved in the case of a small impact.

[0057] Preferably, the deformation control mechanism is arranged in contact with or constitutes the sensor carrier.

[0058] Thus, the sensor carrier can assist or influence the function of the deformation device.

[0059] Preferably, the deformation structure and the sensor carrier are arranged between a vehicle skin element and a vehicle body carrier element. The vehicle skin element can be a bumper cover. The vehicle body carrier element can be a bumper beam.

[0060] A further aspect of the application relates to a motor vehicle, in particular a passenger car or a truck, having an energy absorption device according to the application, which is arranged between a vehicle skin element and a vehicle body carrier element.

[0061] Advantageously, the sensor carrier can extend in the vehicle transverse direction.

[0062] Here, not only can a deformation structure be arranged below the sensor carrier, but also above the sensor carrier.

[0063] Advantageously, the sensor carrier can be fixed to the bumper beam. Here, the sensor carrier has a free front end. In addition or alternatively, the deformation structure can be fixed to the bumper beam.

[0064] Here, in the case of an impact, the sensor carrier and the deformation structure are supported on the vehicle body carrier element.

[0065] One outer layer of the deformation structure can be positionally fixedly fixed to the vehicle body carrier element. Further outer layers can also be positionally fixedly supported. Here, preferably, an odd number of layers, in particular three layers, are provided.

[0066] By means of the motor vehicle according to the application with the sensor carrier and the deformation structure, no crash sensor and actuator are required in order to actively lock or unlock the mechanical means if necessary and thus to be able to switch as required between a structure with "soft" deformation behavior and a structure with "stiff" deformation behavior. The motor vehicle according to the application with the sensor carrier and the deformation structure automatically functions in dependence on the crash impulse, which in turn depends on the crash speed of the motor vehicle. The deformation direction is in particular the crash direction and in applications for pedestrian protection in the motor vehicle head essentially the vehicle longitudinal direction.

[0067] Thus, in the case of a low crash impulse and thus in the case of a low crash speed of the motor vehicle, the deflection of the opposing layers takes place in such a way that the protrusions of the opposing layers oppose one another and support one another. The deformation structure thus functions stiffly. In the case of a high crash impulse and thus in the case of a high crash speed, the opposing layers do not deflect in such a way that the opposing protrusions and recesses of the opposing layers can be displaced into one another. Thus, the deformation structure responds more softly over a longer deformation distance.

[0068] The deformation structure may, for example, be designed in such a way that, at crash impulses occurring up to a threshold speed of the motor vehicle, the deformation structure responds more stiffly and deforms under greater force. Thus, in the case of a low crash speed (at very low speeds) the crash load can be transmitted to the rear-lying vehicle body elements or, at slightly higher speeds but below the threshold speed, sufficient energy absorption takes place by means of the deformation structure to protect the rear-lying components. Thus, in each case repair costs can be reduced - for example in the case of so-called parking crashes, for example up to 4 km / h - which can be limited to, for example, repair of scratches if necessary.

[0069] The threshold speed may, for example, be 20 km / h or a similar speed.

[0070] The pedestrian protection device may, for example, also be designed in such a way that, at crash impulses occurring from a threshold speed of the motor vehicle, the deformation structure responds more softly and deforms under less force. This is particularly advantageous in the case of a frontal crash of a pedestrian with a motor vehicle from the threshold speed, since in this case less crash force acts on the pedestrian.

[0071] The above-listed refinements of the application can be combined with one another arbitrarily as far as this is possible and meaningful. BRIEF DESCRIPTION OF DRAWINGS

[0072] The following brief description of the drawings is made.

[0073] Figure 1An energy absorption device according to an embodiment of the application is shown schematically in a perspective view.

[0074] Figure 2 A deformation structure of the energy absorption device according to the embodiment of the application is shown schematically in a perspective view.

[0075] Figure 3 A deformation structure according to the embodiment of the application in an initial position is shown schematically in a side view.

[0076] Figure 4 A deformation structure according to the embodiment of the application in a collision load situation with a small collision impulse is shown schematically in a side view.

[0077] Figure 5 A deformation structure according to the embodiment of the application in a collision load situation with a large collision impulse is shown schematically in a side view. DETAILED DESCRIPTION

[0078] Reference is made subsequently to the accompanying Figures 1 to 5 An embodiment of the application is described.

[0079] Figure 1 An energy absorption device 1 according to a first embodiment of the application is shown in a perspective view in an initial position. The energy absorption device 1 is embodied at a front end of a motor vehicle front section, in particular at a front end of a motor vehicle head section, at a bumper beam 40. The bumper beam 40 is connected by a left crash box with a left motor longitudinal beam and by a right crash box with a right motor longitudinal beam. The energy absorption device 1 is arranged in a space between a not shown vehicle skin, i.e. a bumper cover, and the bumper beam 40.

[0080] As shown in Figure 1 The energy absorption device 1 has a plurality of deformation structures 10 which are switchably deformable at different force levels depending on the impulse. In particular, the energy absorption device 1 has a first deformation structure 10a, a second deformation structure 10b, a third deformation structure 10c and a fourth deformation structure 10d. Figure 1A pair of deformable structures 10 is shown. The pair of deformable structures 10 consists of a lower deformable structure 10 and an upper deformable structure 10. The lower deformable structure 10 and the upper deformable structure 10 are arranged at a certain distance from each other in the vehicle height direction. The pairing and the distance between them can increase the effect of the deformable structures 10 in the vehicle height direction. One deformable structure 10 is fixed at this position on the bumper beam 40. Advantageously, multiple pairs of deformable structures 10 are arranged in the vehicle lateral direction. For example, a pair of deformable structures 10 can be arranged in the left middle region of the bumper beam 40 and a pair of deformable structures 10 can be arranged in the right middle region of the bumper beam 40. The energy absorption device 1 also has a sensor bracket 20, which is also fixed to the bumper beam 40 parallel to and directly adjacent to the deformable structures 10. In particular, the sensor bracket 20 extends between the pairs of deformable structures 10. The sensor bracket 20 extends forward along the longitudinal direction of the vehicle (i.e., the potential collision direction and deformation direction) beyond the deformable structure 10 by approximately 10 mm to 40 mm. The sensor bracket 20 extends substantially along the entire length (in the y-direction) of the bumper beam 40 in the lateral direction of the vehicle. The sensor bracket 20 serves as a support for the collision detection sensor 21. The sensor bracket 20 is composed of pedestrian protection foam known to deform at low force levels.

[0081] As in Figure 1 As shown, the mating of the deformable structures 10 is not provided across the entire width of the bumper beam 40. Known pedestrian protection foam is provided in the area between the bumper beam 40 and the bumper cover where the deformable structures 10 are not located. The sensor bracket 20 extends across the entire width of the bumper beam 40.

[0082] Then refer to the appendix. Figure 3 , 4 Section 5 explains the working principle of the deformable structure 10.

[0083] As in Figure 2As is shown in Fig. 1, the deformation structure 10 has exactly three layers 3, 5, 3 which are arranged one after the other. The layers 3, 5, 3 are spaced apart from one another by a distance and are connected to one another at opposite sides of the layers 3, 5, 3 by two deformation control mechanisms 7. The two deformation control mechanisms 7 are fixedly connected to each layer 3, 5, 3 at a plurality of locations, namely in this embodiment three locations. Each deformation control mechanism 7 has three control tabs 71 for each layer pair. The control tabs 71 are so inclined or, respectively, arcuately configured that they exert a hinge action in a specific direction in relation to the collision load or, respectively, the collision impulse. The control tabs 71 extend between two opposite fixed tabs 73, respectively. The control tabs 71 between the uppermost layer 3 and the middle layer 5 and the control tabs 71 between the middle layer 5 and the lowermost layer 3 are inversely configured, so that the hinge action of the control tabs points in opposite directions. Each fixed tab 73 is assigned to one of the layers 3, 5, 3. On each fixed tab 73 there are three protrusions for engagement with corresponding openings in the layer 3, 5, 3 to which the fixed tab 73 belongs. Each deformation control mechanism 7 is made in one piece from a plastic injection-molded part. The deformation control mechanisms 7 can also have more or fewer control tabs 71. This is in particular also dependent on the size of the layers 3, 5, 3 or, respectively, the deformation structure 10. More than 3 layers, preferably an odd number of layers, are also possible. Correspondingly, in this case the deformation control mechanisms have a corresponding number of fixed tabs. In this case, the hinge action of the control tabs takes place in opposite directions for each adjacent layer pair.

[0084] The layers 3, 5, 3 of the deformation structure 10 are made of aluminum extruded profiles. Thus, the layers can be manufactured cost-advantageously and cut to the desired length. It is also conceivable to manufacture the layers 3, 5, 3 from aluminum by a further manufacturing process. The layers 3, 5, 3 have a trapezoidal configuration.

[0085] The deformation control mechanisms 7 have protrusions which are provided for engagement with the assigned lateral openings 37, 57 (see Fig. 5) of the layers 3, 5, 3. Figure 3 , 4 The protrusions 51 of the layer 5 also have steps 55. The protrusions 31 of the layer 3 have recesses or, respectively, steps 33 which are complementary to the steps 55. In the case of a collision with a relatively small collision impulse, the opposite steps 55 and recesses come into one another and form a form-locking engagement in the lateral or, respectively, transverse direction, as is shown in Fig. 2. Thus, the layers 3, 5, 3 are held more stably in the position and a reliable force introduction onto the bumper beam is established. Figure 4

[0086] ​In the event of a vehicle collision, the impact force is transmitted from the bumper cover to the sensor bracket 20, enabling the collision detection sensor 21 to detect the collision. During a collision, the collision load first acts on the sensor bracket 20 in the area of ​​the deformable structure 10, causing the sensor bracket to deform at a low force level until the collision load contacts the deformable structure 10, at which point the collision load determines the deformation force level. The deformation force level of the sensor bracket 20 is not greater than the deformation force level of the deformable structure 10. Function and effect of deformation.

[0087] Figure 3 This shows the initial or normal positions of layers 3, 5, and 3 before the collision (corresponding to...). Figure 2 (Perspective view in the image).

[0088] Reference Figure 4 and Figure 5 The diagram illustrates the function of the deformable structure 10 under different collision load conditions. In the event of a frontal collision between a motor vehicle and an object or person, the load, or at least the resultant force of the collision load, acts on the deformable structure 10 along the longitudinal direction of the vehicle (i.e., the deformation direction D), wherein the foremost layer 3 (the uppermost layer in the diagram) moves towards the middle layer 5 under the more elastic deformation of the control tab 71. The middle layer 5 also moves towards the rearmost layer 3 (the lowermost layer in the diagram). At the initial position of the deformable structure 10 (in... Figure 3 As shown in the diagram, the protrusion 31 of layer 3 and the recess 52 of layer 5 are opposite each other. If layers 3 and 5 are not connected to each other by the control tab 71, then adjacent layers 3 and 5 can move towards each other and into each other from the initial position with minimal resistance and virtually no obstruction.

[0089] Figure 4 The diagram illustrates a collision load scenario with a small impact impulse, for example, when the vehicle's collision speed is below a predetermined collision speed of 20 km / h, and the impact impulse is not particularly important for pedestrian protection. Figure 5 The diagram illustrates a collision load condition with a high impact impulse, for example, when the vehicle's collision speed is equal to or greater than a predetermined collision speed of 20 km / h. Here, the predetermined collision speed is mentioned only as an example and may have different values.

[0090] First, refer to Figure 4 The function of the deformable structure 10 is described in the event of a collision between a motor vehicle and another vehicle at a speed of less than 20 km / h.

[0091] The control tab 71 is configured and designed such that, in the event of a small impact impulse, adjacent layers 3 and 5 undergo a deflection motion relative to each other when they are pressed against each other. Because the lowest layer 3 is fixed to the bumper beam, and the highest layer 3 is also substantially fixed in position during the impact due to the force, only the middle layer 5 can be displaced and moved parallel to each other in a predetermined direction P via the control tab 71. Here, the control tab 71 functions, for example, like a so-called membrane hinge, which assists in the deflection motion or defines the deflection trajectory. With the deflection motion, adjacent layers 3 and 5 move parallel to each other in addition to moving toward each other. Here, the protrusion 31 of layer 3 reaches a position opposite to the protrusion 51 of layer 5, until the upper side or end side of the protrusion 31 of layer 3 contacts the upper side or end side of the protrusion 51 of layer 5. Figure 4 (as shown in the diagram). Here, the upper or end sides of protrusions 31 and 51 are designed in such a way that further parallel movement of layers 3 and 5 relative to each other becomes difficult. For example, protrusions 31 and 51 may be provided with measures to increase the coefficient of friction, such as corrugations.

[0092] Therefore, in cases of slow collision speed and thus small collision impulse, the deformable structure 10 adjusts according to the collision load level. Figure 4 In the event of a collision, the impact load is directly transferred to the structure of the vehicle behind it (i.e., the bumper beam 40), or at a higher load level, i.e., at a higher collision speed, the individual layers 3, 5, 3 of the deformable structure 10 fail brittlely by fracture and / or fail by plastic deformation after the protrusions 31, 51 come into contact with each other. Preferably, the deformable structure 10 is designed such that it does not fail and thus the intrusion depth of the impacting vehicle remains small. Here, the intrusion depth of the obstacle or the other vehicle is minimized by the small deformation of the deformable structure and the so-called impact box effectively absorbs the impact energy, through which the bumper beam is connected to the longitudinal beams (motor brackets) of the vehicle body. Thus, overall, the damage to the vehicle is kept sufficiently low.

[0093] In particular, the deformation structure 10 can be designed in such a way that it can transfer the crash load onto the crash structure at a crash speed, for example, of less than 4 km / h without the deformation structure 10 failing. That is, the control web 7 is deformed only elastically and the structure of the layers 3 and 5 does not fail as such. This is advantageous if no repairable damage to the motor vehicle is to occur in the case of a so-called parking crash or in similar situations and has an influence on the insurance classification of the motor vehicle, for example. The deformation structure 10 is elastically returned to its initial position after the parking crash by the elastic return force of the deformation control 7. At a crash speed of from 4 km / h up to approximately 20 km / h, the crash energy is so high that the crash box must absorb the crash energy by deformation, wherein the crash load is transferred onto the crash box via the bumper beam in the position shown in Figure 3 Fig. 3 (as far as possible without further deformation). However, the damage to the front end of the vehicle front can be kept relatively small overall by the small intrusion depth mentioned.

[0094] Reference is subsequently made to Figure 5 Fig. 4, which describes the function of the deformation structure 10 in the case of a crash of the motor vehicle at a crash speed of equal to or greater than 20 km / h.

[0095] The control web 71 is designed and arranged in such a way that it fails or is more or less folded together in the case of a high crash impulse, so that it cannot perform a hinge action. Here, the inertia of the layers 3, 5, 3 is so great in the case of a high crash impulse that the control web 71 cannot cause or assist the lateral displacement movement (parallel displacement) of the layers 3, 5, 3. As a result, the protrusion 31 of the layer 3 and the recess 52 of the layer 5 and the protrusion 51 of the layer 5 and the recess 32 of the layer 3 move directly towards one another. In the further course of the crash and the deformation of the deformation structure 1, the protrusion 31 of the layer 3 is completely displaced into the recess 52 of the layer 5. The protrusion 51 of the layer 5 is also completely displaced into the recess 32 of the layer 3. Since, for this purpose, essentially no deformation of the structure of the layer 3 or the layer 5 is required and only the control web 71 is deformed, the deformation of the deformation structure 1, at least up to the state shown in Figure 4 Fig. 4, takes place at a relatively low force level.

[0096] This is advantageous in this respect, since from a collision speed of approximately 20 km / h it is important that the front end of the motor vehicle vehicle front and in particular the bumper cover connected with the deformation structure 1 responds sufficiently softly for the protection of pedestrians at low levels of deformation force. The front end then behaves similarly softly as in the case of the known pedestrian protection foam provided instead of the deformation structure according to the application. If the collision partner is a pedestrian, then advantageously a relatively small force acts on the pedestrian at speeds of approximately 20 km / h and above.

[0097] Thus, in general the target conflict can be solved by the deformation structure 1 according to the application, which on the one hand achieves a sufficiently large rigidity of the deformation structure 1 at very low collision speeds, which are not important for pedestrian protection, or in other words a sufficiently large level of deformation force of the deformation structure 1, or in other words a sufficiently large transfer of force onto the structure with the bumper beam behind the deformation structure into the crash box, or on the other hand ensures sufficient pedestrian protection by a low level of deformation force at slightly higher collision speeds, which are important for pedestrian protection.

Claims

1. Energy-absorbing device for a motor vehicle with pedestrian protection function, having a deformation structure (10) which is switchably deformable at different force levels depending on the impulse and a sensor carrier (20) which is arranged parallel to the deformation structure (10) in the deformation direction, which projects beyond the deformation structure (10) in the direction of the vehicle exterior in the deformation direction and which serves as a holder for a crash detection sensor (21), which deformation structure (10) comprises at least a first layer (3) and a second layer (5) which are arranged at a distance from one another in the deformation direction and are displaceable relative to one another, which first layer (3) and second layer (5) have complementary protrusions (31, 51) and recesses (32, 52), which are configured such that the protrusions (31) of the first layer (3) and the recesses (52) of the second layer (5) and the protrusions (51) of the second layer (5) and the recesses (32) of the first layer (3) can sink into one another, which first layer (3) and second layer (5) are connected to one another by a deformation control mechanism (7) such that, in the case of a high impulse in the deformation direction, the protrusions (31) of the first layer (3) sink into the recesses (52) of the second layer (5) and the protrusions (51) of the second layer (5) sink into the recesses (32) of the first layer (3) so that the deformation of the deformation structure (10) in the deformation direction takes place at a low force level, and such that, in the case of a small impulse in the deformation direction, the protrusions (31) of the first layer (3) hit against the protrusions (51) of the second layer (5) so that the deformation of the deformation structure (10) in the deformation direction takes place at a high force level, wherein The protrusion (51) of the second layer (5) also has a step (55), the protrusion (31) of the first layer (3) has a step (33) complementary to the step (55), so that in the case of a small impulse in the deformation direction, the opposite steps (55) and (33) hit each other and form a form-locking scarf in the lateral direction.

2. The energy absorbing device of claim 1, wherein, The sensor carrier (20) can be deformed at low force levels.

3. The energy absorbing device of claim 1 or 2, wherein, The collision detection sensor (21) is used to detect a collision with a person in order to introduce active pedestrian protection measures.

4. The energy absorbing device of claim 1 or 2, wherein, The collision detection sensor (21) comprises a deformable gas-filled hose and a pressure measuring device for measuring the gas pressure in the hose.

5. The energy absorbing device of claim 1 or 2, wherein, The collision detection sensor (21) is arranged at an outer end of the sensor carrier (20).

6. The energy absorbing device of claim 1 or 2, wherein, The deformation control mechanism (7) is arranged in contact with the sensor carrier (20).

7. The energy absorbing device of claim 1 or 2, wherein, The deformation structure (10) and the sensor carrier (20) are arranged between a vehicle skin element and a vehicle body carrier element.

8. The energy absorbing device of claim 2, wherein, The sensor carrier (20) is made of foam.

9. The energy absorbing device of claim 8, wherein, The foam is a pedestrian protection foam.

10. The energy absorbing device of claim 3, wherein, The person is a pedestrian.

11. The energy absorbing device of claim 1 or 2, wherein, The collision detection sensor (21) is used to detect a collision with a person in order to introduce active pedestrian protection measures in the event of a detected collision.

12. The energy absorbing device of claim 7, wherein, The vehicle skin element is a bumper cover.

13. The energy absorbing device of claim 7, wherein, The vehicle body carrier element is a bumper beam.

14. Motor vehicle having an energy-absorbing device according to one of claims 1 to 13, which is arranged between a vehicle skin element and a vehicle body carrier element.

15. The motor vehicle of claim 14, wherein, The sensor carrier (20) extends in the vehicle transverse direction and is provided with a deformation structure (10) both below and above the sensor carrier (20).

16. Motor vehicle according to claim 14 or 15, wherein The sensor carrier (20) and the deformation structure (10) are fixed at a bumper beam (40).

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