Collision detection device

Abstract

Collision detection device for a vehicle for detecting a collision of the vehicle with a pedestrian, wherein a first collision sensor device (2) and at least one further collision sensor device (3) are provided one above the other and at a distance from each other in the front area (10) of the vehicle (1), each extending over at least a part of the vehicle width, and wherein an evaluation device (4) is provided or formed which, upon detection of a collision by the collision sensor devices (2, 3), sends an activation signal to a pedestrian protection device (5) of the vehicle (1), and wherein the evaluation device (4) is designed such that it sends the activation signal to the pedestrian protection device (5) only if at least two of the collision sensor devices (2, 3) independently detect a collision, characterized in that the respective collision sensor device (2, 3) is connected by a contact strip (20;30) is formed, which has a plurality of electrical contacts (23, 24, 25, 26, 27; 33, 34, 35, 36, 37) connected in parallel to each other, and the contact strip (20) of the first collision sensor device (2) and the contact strip (30) of at least one further collision sensor device (3) are electrically connected in series and are components of a circuit (40) forming or comprising the evaluation device (4).

Description

TECHNICAL AREA The invention relates to a collision detection device for a vehicle for detecting a collision between the vehicle and a pedestrian. It further relates to a vehicle with such a collision detection device. BACKGROUND OF THE INVENTION In the event of a collision between a vehicle and a pedestrian, pedestrian protection devices on the vehicle must be activated as quickly as possible to minimize the impact of the pedestrian on the front of the vehicle, for example, on the hood. This is achieved, for instance, by lifting the front hood (engine cover) in the area adjacent to the windshield to create a greater distance between the hood and the rigid engine components below. The mechanism for the sudden lifting of the hood constitutes a pedestrian protection device. Other pedestrian protection devices can include airbags that deploy between the hood and the windshield in the event of a pedestrian collision. It is obvious that the available time between the detection of a pedestrian collision and the full readiness of the pedestrian protection system is extremely short. Therefore, the detection of a collision between a vehicle and a pedestrian must be extremely fast and highly reliable. False triggers, which could occur, for example, when the vehicle collides with a small animal, must be avoided. STATE OF THE ART From EP 2 678 191 B1, an impact sensor is known comprising an elastically deformable hose extending substantially across the width of the vehicle and at least one pressure sensor, wherein the hose is mounted behind a bumper cover in front of a rigid bumper crossmember. An elastic damping element, consisting, for example, of an energy-absorbing foam, is provided between the bumper cover and the hose. In the event of a collision of the vehicle with an object, for example, a pedestrian's leg, this front area of ​​the bumper cover is the first to make contact with the pedestrian, whereupon an impulse force is exerted on the bumper cover, from there on the elastic damping element, and from there on the pressure hose.This force acting on the pressure hose causes it to compress radially, as the hose is supported by the rigid bumper crossmember, which does not yield under this force. This compression forces fluid from the hose through a pressure sensor, which detects the fluid flow and sends a signal to detect the collision. However, this well-known impact sensor is unable to distinguish between a collision with a pedestrian's body part and a collision with a small animal, so there is a risk of false triggering in the event of a collision with small animals. A similar device is known from DE 10 2015 210 191 A1. This device also offers no possibility of distinguishing between a collision with a pedestrian and a collision with a small animal. DE 10 2006 050 098 A1 discloses a collision detection device that is similar in design to the two known collision detection devices described above. However, this collision detection device has two pressure hoses arranged vertically one above the other and spaced apart from each other. These hoses extend essentially across the width of the vehicle and are each connected to a pressure sensor. Since both pressure hoses are arranged one above the other between a rigid bumper cross member, against which they are supported, and a shock absorber located behind the bumper skin, and since both pressure hoses are simultaneously subjected to the pressure force by the same shock absorber in the event of a collision, these two pressure hoses, together with their respective pressure sensors, form a collision detection device with redundant pressure sensor devices.Therefore, this collision detection device cannot distinguish between a collision with a pedestrian and a collision with a small animal. Furthermore, DE 10 2010 053 312 A1 discloses a sensor device for detecting an impact on a vehicle, comprising a first sensor arranged on a first hose filled with a fluid, wherein a second sensor arranged on a second hose filled with a fluid is additionally provided, and wherein a pedestrian protection device coupled to the sensor device can only be triggered in the event of an impact detected by both sensors. Furthermore, a pedestrian protection system for a motor vehicle with an impact detection sensor for detecting an impact of a pedestrian on the motor vehicle is known from DE 10 2004 023 669 A1. Furthermore, DE 100 02 110 A1 discloses a method for triggering protective measures in the event of a collision between a vehicle and a pedestrian. PRESENTATION OF THE INVENTION The object of the present invention is to provide a collision detection device for a vehicle for detecting a collision between a vehicle and a pedestrian, which enables a reliable distinction between a collision with a pedestrian and a collision with a small animal. This problem is solved by the collision detection device with the features of claim 1. This collision detection device for a vehicle, designed to detect a collision between the vehicle and a pedestrian, comprises a first collision sensor and at least one further collision sensor, arranged one above the other and spaced apart, in the front of the vehicle. Each sensor extends over at least a portion of the vehicle's width. An evaluation unit is provided or formed, which, upon detection of a collision by the collision sensors, sends an activation signal to a pedestrian protection device of the vehicle. This collision detection device is characterized by the fact that the evaluation unit is configured to send the activation signal to the pedestrian protection device only if at least two of the collision sensors independently detect a collision. Furthermore, the respective collision sensor device is formed by a contact strip that has a plurality of electrical contacts connected in parallel. Such a contact strip, which is provided in the foremost area, for example directly behind the bumper skin, delivers a signal earlier than the pressure hose solutions of the prior art. Furthermore, the contact strip of the first collision sensor device and the contact strip of at least one further collision sensor device are electrically connected in series. In addition, the contact strips are components of a circuit that forms or comprises the evaluation unit. ADVANTAGES The inventive provision of at least two independent collision sensor devices arranged one above the other at a vertical distance from each other, and the design of the evaluation device such that it sends the activation signal for the pedestrian protection device of the vehicle to the pedestrian protection device only when at least two of the collision sensor devices independently detect a collision, makes it possible to distinguish collisions of small animals, in which only one, for example the lower one, of the collision sensor devices detects a collision, from a collision in which two or more collision sensor devices detect the collision.If a collision is detected not only by one of the collision sensor devices, but also by the other collision sensor device(s), for example by a collision sensor device located above it, this is an indication that there is no collision with a small animal. This series electrical circuit makes it easy to detect pressure on all collision sensor devices, namely by switching all collision sensor devices in such a case. Further preferred and advantageous features of the collision detection device according to the invention are the subject of dependent claims 2 to 6. It is particularly advantageous if the evaluation device receives a speed signal representing the current vehicle speed and if the evaluation device is designed in such a way that it only sends the activation signal to the pedestrian protection device if the current vehicle speed is within a predetermined activation speed range between a lower activation speed and an upper activation speed. This advanced feature ensures that minor parking bumps occurring at low speeds below the lower activation speed do not trigger the pedestrian protection device. Limiting the upper activation speed range also prevents the pedestrian protection device from activating in collisions occurring at higher speeds, which are typically collisions with other vehicles or objects. This means that, for example, in higher-speed collisions, the hood remains in its locked normal position, thus contributing more effectively to the dissipation of collision energy than when in its pedestrian protection position.In all other collisions occurring within the activation speed range, the detection of pedestrian accidents according to the invention is carried out with the corresponding activation of the pedestrian protection device. It is particularly advantageous if the specified activation speed range is between 5 km / h and 70 km / h, preferably between 10 km / h and 60 km / h, and more preferably between 20 km / h and 50 km / h. These are speed ranges where, for example in urban traffic, the risk of pedestrian collisions is higher than at speeds above this range. If electrical contacts are provided, it is advantageous to design the contacts in the contact strips such that, in the event of pressure applied due to a collision, they switch from an open contact state to a closed, electrically conductive contact state. However, with appropriate evaluation electronics, it is also possible to design the contact strips so that, in the event of pressure applied due to a collision, they open the electrical contact and thus interrupt the current flow, which can then be interpreted by the evaluation device as a collision signal. A particularly advantageous design is one in which the circuit includes a speed-dependent activation switch that is electrically connected in series with the contact strips of the collision sensor devices. This allows the vehicle's current speed to be used in evaluating the collision signals and determining whether a pedestrian accident has occurred. It is beneficial if the speed-dependent activation switch is closed when the vehicle's current speed is within the activation speed range. It is further advantageous if an electrically operated actuator of the pedestrian protection device is integrated into the circuit. In this case, particularly if the contacts of the contact strips switch to their electrically closed state in the event of a collision-induced impulse force, and if the speed-dependent activation switch, if one is provided, is also closed within the activation speed range, a generated or externally applied current can then flow directly to the actuator through the circuit and electrically actuate it. It is advantageous if the circuit has an electrical power source or is electrically connected to an electrical power source that provides sufficient electrical energy to operate the actuator of the pedestrian protection device. The part of the problem directed towards the vehicle is solved by a vehicle with a collision detection device according to claim 7. Preferred embodiments of the invention with additional design details and further advantages are described and explained in more detail below with reference to the accompanying drawing. BRIEF DESCRIPTION OF THE DRAWINGS It shows: Fig. 1 the front of a motor vehicle equipped with a collision detection device according to the invention; Fig. 2 an enlarged and partially cutaway view of detail I from Fig. 1; Fig. 3 a bottom view of the vehicle front from Fig. 2 in the direction of arrow III in Fig. 2; Fig. 4 a schematic representation of a contact strip in the normal state; Fig. 5 the contact strip according to Fig. 4 in the case of a collision impulse; Fig. 6 a schematic circuit diagram of a collision detection device according to the invention with the switches open; Fig. 7 the schematic circuit diagram of the collision detection device in the case of a "parking bump"; Fig. 8 the schematic circuit diagram of the collision detection device according to the invention in the case of a pedestrian collision; Fig. 9 the schematic circuit diagram of the collision detection device according to the invention in the case of a small animal collision; Fig.10 the schematic circuit diagram of the collision detection device according to the invention in the state of a collision at higher speed above the activation speed range and Fig. 11 the integration of a speed-dependent activation switch into a vehicle BUS. PRESENTATION OF PREFERRED EXECUTION EXAMPLES Figure 1 shows the front area of ​​a vehicle 1 equipped with a collision detection device according to the invention. The collision detection device comprises two collision sensor devices 2, 3, which are arranged one above the other and vertically spaced apart from each other in the front area 10 of the vehicle 1, behind or integrated into a front panel 12. The collision sensor devices 2, 3 and their arrangement in the front area 10 of the vehicle 1 are described in more detail in conjunction with Figure 2. Fig. 2 shows a section of the front area 10 of the vehicle 1 according to detail I in Fig. 1 with the front fairing 12 partially cut away. The front fairing 12 has an elastic bumper skin 11, which defines the outer edge of the front fairing 12 and its outer contour. This front fairing 12 forms an upper bumper bulge 14, which is located at the usual bumper height below an upper radiator grille 13. A lower bulge 16 of the front grille 12, which forms, for example, a spoiler lip, is formed vertically spaced below the bumper bulge 14. A lower radiator grille 15 is provided between the upper bulge 14 and the lower bulge 16.The two ridges 14, 16 are not only spaced apart in the vertical direction (Z-direction), but also in the longitudinal direction of the vehicle (X-direction), namely in such a way that the upper bumper ridge 14 protrudes slightly forward over the lower ridge 16, as shown in Fig. 2 by the distance x. A first collision sensor device 2 is provided in the upper bumper rim 14 and a second collision sensor device 3 is provided in the lower rim 16, which are described below. The upper collision sensor device 2 has a contact strip 20 that is mounted directly behind the bumper skin 11 and extends, as shown in Fig. 3, over substantially the entire width of the vehicle in the Y direction along the contour of the front fairing 12. The front of the contact strip 20 is in contact with the inside of the bumper skin 11 or is slightly spaced from it. The rear of the contact strip 20 bears against the front of an elastically or plastically deformable support body 22. This support body 22 consists, for example, of an impact-energy-absorbing plastic foam. The support body 22 bears against a substantially rigid upper bumper crossmember 17 of the vehicle 1. The further, lower collision sensor device 3, constructed in the same manner, also has a contact strip 30, which is likewise arranged behind the bumper skin 11 at a distance from it or in contact with its inner surface. The back side of the contact strip 30 is supported against a lower support body 32, which – like the upper support body 22 – preferably consists of a shock-absorbing plastic foam. The lower support body 32 is supported against a substantially rigid lower bumper cross member 18. Although in the example shown and described above the respective contact strip 20, 30 is arranged between the bumper skin 11 and the associated support body 22 or 23, it is of course also possible to arrange the respective contact strip between the associated support body and the associated bumper crossmember. It is also possible to provide a pressure hose instead of the respective electrical contact strip, which—as in the prior art—is connected to a pressure sensor. The present invention is therefore not limited to the embodiment of the collision sensor devices 2, 3 with electrical contact strips shown and described in the figures, but also includes other collision sensor devices, such as the pressure sensor devices known from the prior art. The operation of the collision sensor devices 2, 3 equipped with the electrical contact strips 20, 30 will now be explained in more detail with reference to Fig. 4 and Fig. 5. Figures 4 and 5 each show a schematic representation of a contact strip 20, 30, wherein the contact strips 20, 30 are identically constructed and function in the same way. The electrical contact strip 20 has an elastically deformable, waterproof covering 20' that surrounds the electrical components described below. An electrical supply line 21 and an electrical discharge line 21' lead from the outside through the wall of the covering 20' into the interior of the covering 20'. Between the electrical supply line 21 and the electrical discharge line 21', a plurality of electrical switches 23, 24, 25, 26, 27, spaced apart in the transverse direction Y of the vehicle, are arranged and are connected in parallel between the electrical supply line 21 and the electrical discharge line 21'. Thus, as soon as just one of the electrical contacts 23, 24, 25, 26, 27 is closed, an electrically conductive connection is established between the electrical supply line 21 and the electrical discharge line 21'. Instead of an electrical parallel circuit with a plurality of switches 23, 24, 25, 26, 27 arranged across the vehicle width in the Y-direction and spaced apart from each other, other technical solutions are of course possible that make it possible to close an electrical contact at any point along the longitudinal extent of the respective contact strip when external pressure is applied. For example, two electrical conductors extending along the length of the contact strip can be provided inside the casing 20', spaced apart from each other, which come into electrically conductive contact with each other when pressure is applied to the contact strip. Fig. 5 shows the electrical contact strip 30 in the event of a collision of the vehicle 1 with an obstacle H. When the vehicle 1 collides with the obstacle H, the elastic bumper skin 11 first comes into contact with the obstacle H and is indented by it, as schematically illustrated in Fig. 5. During its collision-induced deformation, the bumper skin 11 then contacts the elastic covering 30' of the electrical contact strip 30, which is also indented at this point. At the point of contact with the obstacle, the contacts located in the area of ​​deformation of the covering 30' are closed, thus establishing an electrically conductive connection between the electrical supply line 31 and the electrical return line 31'. It is irrelevant whether the contact strip in question is equipped with discrete switches or whether, as described above as an alternative solution, it has two parallel conductors that come into contact with each other. The different functional states of the collision detection device according to the invention are described below with reference to Figs. 6, 7, 8, 9, 10 to 11. Figures 6, 7, 8, 9, 10 to 11 schematically depict the respective collision detection device as an electrical circuit diagram. In this circuit diagram, the first, upper collision sensor 2 and the further, lower collision sensor 3 are each represented as a switch S1 and S2, respectively. The two switches S1 and S2 each have a switching path x1 and x2, respectively, which represents the distance an obstacle must travel from the initial contact with the outer surface of the bumper cover 11 to a point where the switch closes and establishes an electrically conductive connection. The switching paths x1 and x2 of the two collision sensor assemblies 2 and 3 can be the same or different in length. Furthermore, the circuit shown in Figures 6, 7, 8, 9, 10 to 11 is provided with a vehicle speed-dependent switch S3, which is open or closed depending on the current vehicle speed, as will be explained further below in connection with Figure 11. Switch S3 thus forms a speed-dependent activation switch 42. In the circuits shown in Figs. 6, 7, 8, 9, 10 to 11, an electrical current source 6 is also provided, which can be formed, for example, by the vehicle battery or another vehicle-side electrical power supply device, which, for example, only supplies electrical current when the ignition is switched on and the vehicle is in operation. Finally, the circuit shown in Figures 6, 7, 8, 9, 10 to 11 also includes a schematically represented actuator 50 of a pedestrian protection device 5 (not shown in detail). Such a protection device can, for example, be formed by an electrically, pneumatically, or spring-actuated ejector mechanism that abruptly lifts the front hood 19 of the vehicle in the rear area near the windshield, as symbolically represented by arrow F in Figure 1. Accordingly, the actuator 50 is an actuating element that activates the pedestrian protection device 5 accordingly, for example, by abruptly lifting the hood in the direction of arrow F. Alternatively or additionally, an airbag can also be provided in the area between the rear end of the front hood 19 and the windshield of the vehicle 1, which is deployed by the actuator 50. As can be seen in Figures 6, 7, 8, 9, 10 to 11, the electrical power source 6, the switches S1, S2 and S3, and the actuator 50 are connected to each other by electrical conductors and form a closed circuit when the switches are closed (Figure 8). This circuit 40 with its described components thus forms a simple logic evaluation device 4 for detecting a vehicle collision. In a more complex design of a collision detection device according to the invention, in which the collision sensor devices are not formed by electrical contact strips, but for example by pneumatic or hydraulic pressure sensors, as has already been described in detail, an evaluation device formed by a computer can be provided, to which the signals from the pressure sensors and the signal of a speed measuring device are supplied and which outputs an activation signal to the actuator 50. Fig. 6 shows an operating state in which no collision is detected; switches S1 and S2 are open. The speed-dependent switch S3 is also open, indicating that the vehicle is stationary or moving at a speed outside the activation speed range; the vehicle is therefore slower than the lower activation speed v1 or faster than the upper activation speed v2. Figure 7 shows the same circuit diagram as Figure 6, but in an operating state in which switch S1, representing the upper, first collision sensor 2, is closed and switch S2, representing the further, lower collision sensor 3, is open. The speed-dependent switch S3 is also open; the vehicle is therefore traveling at a speed below or above the activation speed range. This state occurs, for example, when the vehicle collides with an obstacle at low speed, i.e., in a so-called "parking bump." In this case, the upper bumper bulge 14, which is located further forward, strikes the obstacle, while the slightly rearward lower bulge 16 does not touch it. In this scenario, only switch S1 is closed, while switches S2 and S3 remain open.Consequently, the actuator 50 is not supplied with electrical energy from the power source 6 and the pedestrian protection device 5 is not triggered. The collision detection device is ready when the current vehicle speed is within the activation speed range, i.e., between the lower activation speed v1 and the upper activation speed v2. The lower activation speed v1 can be, for example, 5 or 8 km / h, which corresponds to the vehicle rolling along gently. It can also be, for example, 10 km / h or 20 km / h, with the speed range between 10 km / h and 20 km / h encompassing speeds typically encountered when maneuvering and, for example, parking. The upper activation speed v2 can, for example, be 50 km / h, which corresponds to the speed limit in built-up areas in most European countries; however, it can also be 60 km / h or 70 km / h, or any other speed between 50 km / h and 70 km / h. This results in an activation speed range that lies between a lower activation speed v1 and an upper activation speed v2 within the aforementioned spectrum. The closed switch position of the speed-dependent switch S3 shown in Fig. 8 therefore indicates that the collision detection device is ready for the activation of the pedestrian protection device. In the example shown in Fig. 8, switch S1, representing the upper collision sensor device 2, and switch S2, representing the lower collision sensor device 3, are closed, indicating that both the upper bumper rim 14 and the lower rim 16 have come into contact with an obstacle. This occurs, for example, when the vehicle 1 collides with a pedestrian's leg. In this case, it is to be expected that the pedestrian will fall onto the hood 19 of the vehicle 1. Since all switches S1, S2, and S3 of the circuit 40 are closed, the actuator 50 of the pedestrian protection device 5 is supplied with electrical energy by the electrical power source 6, and the pedestrian protection device 5 is activated, as symbolized by the lightning bolt in the actuator 50. Fig. 9 shows a state in which the vehicle is also moving at a speed within the activation speed range, as indicated by the closed position of the speed-dependent switch S3. Traveling at a speed within this range, the vehicle collides with a small animal, for example, a fox, which corresponds to the scenario of a typical wildlife collision. The small animal collides with the upper bumper bulge 14, thus activating the upper collision sensor 2, symbolized by the closed position of switch S1. There is no actual collision between the lower bulge 16 and the small animal, so the lower collision sensor 3 is not activated, symbolized by the open position of switch S2.Consequently, no current flows from the electrical power source 6 to the actuator 50 of the pedestrian protection device 5, and therefore the device is not triggered. Similar to the example shown in Fig. 9, a collision with an even smaller animal, for example a wildlife collision with a hare, occurs only in the area of ​​the lower ridge 16 and not in the area of ​​the upper bumper ridge 14. This results in the lower switch S2 being closed, but the upper switch S1 remaining open. In this case as well, the pedestrian protection device 5 is not triggered. Figure 10 shows an operating condition in which the vehicle collides with an obstacle at a speed above the upper activation speed. The speed-dependent switch S3 is open, and since the collision is detected by both collision sensor devices 2 and 3 at this high speed, both switch S1 and switch S2 are closed. However, because the speed-dependent switch S3 is open, no electrical energy flows from the electrical power source 6 to the actuator 50 of the pedestrian protection device 5, so it does not trigger. Figure 11 schematically illustrates the connection of the speed-dependent switch S3 of circuit 40 to the other vehicle sensors. Switch S3 is formed by a speed-dependent activation switch 42, which includes a control unit 43 that receives a speed signal Sv, for example, from a CAN bus 44. This speed signal Sv is generated, for example, by wheel speed sensors and provided by a control unit 45 for dynamic stability control in the CAN bus 44. In the control unit 43 of the activation switch 42, the received speed signal Sv is evaluated to determine whether the vehicle speed represented by the signal Sv lies within the activation speed range. For this purpose, the lower activation speed v1 and the upper activation speed v2 are stored in a memory unit of the control unit 43. If this evaluation shows that the vehicle is moving at a speed within the activation speed range, a corresponding signal is sent to the actual switch S3, which is formed, for example, by a mechanical relay or electronic switching elements such as transistors or thyristors. This causes the switch S3 to close, creating an electrically conductive path. In the event that a greater electrical power is required for the actuation of the actuator 50 of the pedestrian protection device 5 than the power provided by the electrical power source 6 or the electrical power that can be transmitted in the circuit 40, the control unit 43 may have an electrical power amplifier which transmits the required electrical power to the actuator 50 in the event of triggering. The device may in particular have features that represent a combination of the respective individual features of the claims.

Claims

Collision detection device for a vehicle for detecting a collision of the vehicle with a pedestrian, wherein a first collision sensor device (2) and at least one further collision sensor device (3) are provided one above the other and at a distance from each other in the front area (10) of the vehicle (1), each extending over at least a part of the vehicle width, and wherein an evaluation device (4) is provided or formed which, upon detection of a collision by the collision sensor devices (2, 3), sends an activation signal to a pedestrian protection device (5) of the vehicle (1), and wherein the evaluation device (4) is designed such that it sends the activation signal to the pedestrian protection device (5) only if at least two of the collision sensor devices (2, 3) independently detect a collision, characterized in that the respective collision sensor device (2, 3) is connected by a contact strip (20;30) is formed, which has a plurality of electrical contacts (23, 24, 25, 26, 27; 33, 34, 35, 36, 37) connected in parallel to each other, and the contact strip (20) of the first collision sensor device (2) and the contact strip (30) of at least one further collision sensor device (3) are electrically connected in series and are components of a circuit (40) forming or comprising the evaluation device (4). Collision detection device according to claim 1, characterized in that the evaluation unit (4) receives a speed signal representing the current vehicle speed and that the evaluation unit (4) is designed such that it sends the activation signal to the pedestrian protection device (5) only if the current vehicle speed is within a predetermined activation speed range between a lower activation speed (v1) and an upper activation speed (v2). Collision detection device according to claim 2, characterized in that the predetermined activation speed range is between 5 km / h and 70 km / h, preferably between 10 km / h and 60 km / h, more preferably between 20 km / h and 50 km / h. Collision detection device according to one of the preceding claims, characterized in that the circuit (40) has a speed-dependent activation switch (42) which is electrically connected in series with the contact strips (20, 30). Collision detection device according to claim 4, characterized in that an electrically operated actuator (50) of the pedestrian protection device (5) is integrated into the electrical circuit (40). Collision detection device according to claim 4 or 5, characterized in that the circuit (40) has an electrical power source (6) or is electrically connected to such a source. Vehicle with a collision detection device according to one of the preceding claims.

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