JP6593647B2 - Vehicle collision detection device - Google Patents

Description

  The present invention relates to a vehicle collision detection device that detects a collision of a pedestrian or the like with a vehicle.

  2. Description of the Related Art Conventionally, there is a vehicle including a vehicle collision detection device configured to include a deformation sensor such as a piezoelectric film as a vehicle collision detection device for detecting that a collision has occurred in a vehicle. In this vehicle collision detection device, a planar piezoelectric film is provided on the inner surface of the bumper cover along the vehicle width direction to detect a collision on the front surface of the vehicle. The piezoelectric film is made of a piezoelectric polymer material or the like, and generates a charge when applied with a strain, and conversely generates a strain when applied with a charge. In the vehicle collision detection device having this configuration, when a pedestrian or the like collides with the bumper cover, the piezoelectric film is deformed along with the deformation of the bumper cover, and the voltage of the piezoelectric film changes. Based on detecting this voltage change, it is detected that a collision has occurred in the vehicle.

Japanese Patent Laying-Open No. 2005-147983

  In the above-described vehicle collision detection device, for example, a deformation sensor such as a piezoelectric film covered with a covering member is attached to the back surface of the bumper cover along the vehicle width direction. Here, the bumper cover is made of a resin member such as polypropylene, and has a temperature characteristic that the amount of deformation with respect to a predetermined load increases as the temperature increases. For this reason, when the temperature rises, the amount of deformation of the bumper cover at the time of collision increases, and accordingly, the voltage change of the piezoelectric film also increases. Therefore, in the vehicle collision detection apparatus having the deformation sensor, it is assumed that the output of the deformation sensor differs depending on the temperature even if the impact force applied to the bumper is the same. Therefore, there is a problem that it is necessary to prevent a decrease in collision detection accuracy due to variation.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a vehicle collision detection device that can prevent a decrease in collision detection accuracy associated with a temperature change.

The vehicle collision detection device (1) according to claim 1, which has been made to solve the above-mentioned object, is provided along the vehicle width direction on the vehicle rear side of the bumper cover (7) of the vehicle. A deformation sensor (2) for outputting an electric displacement by a load applied in accordance with the deformation of the cover; and a temperature characteristic in which a deformation amount with respect to a predetermined load increases with an increase in temperature, a bumper cover, a deformation sensor, A plurality of intermediate members (3, 31) that are sandwiched between them and arranged at intervals in the vehicle width direction and to the bumper cover based on the electrical displacement of the deformation sensor that is output as the bumper cover is deformed. collision detecting unit for detecting that the object (H) collides with (5), Bei give a intermediate member is the same or increased rate with increasing temperature of the deformation amount for a given applied load is the increase rate of the bumper cover More than that That has a temperature characteristic, further, are arranged apart in the vehicle width direction length or intervals bumper cover is deformed when the object of collision (L, L1) in the vehicle width direction.

  According to this configuration, by arranging a plurality of intermediate members having a temperature characteristic in which the deformation amount with respect to a predetermined load load increases as the temperature rises between the bumper cover and the deformation sensor, the intermediate member becomes hard at low temperatures. Since it is difficult to deform, the external force accompanying the collision is transmitted to the deformation sensor with almost no absorption by the intermediate member, and the deformation sensor is deformed. On the other hand, when the temperature is high, the intermediate member softens and deforms preferentially over the deformation sensor, and a part of the load is absorbed. Therefore, the load applied to the deformation sensor is suppressed, and the deformation of the deformation sensor is suppressed. As a result, it is possible to prevent the voltage change of the deformation sensor from increasing as the temperature rises, and the collision detection accuracy of the vehicle collision detection device resulting from the variation in the output of the deformation sensor accompanying the temperature change. Can be prevented. In addition, the code | symbol in the bracket | parenthesis of each means described in this column and the claim shows the correspondence with the specific means as described in embodiment mentioned later.

1 is a diagram illustrating an overall configuration of a vehicle collision detection device according to a first embodiment of the present invention. It is an enlarged view of the bumper part of FIG. FIG. 3 is a III-III cross-sectional view of the bumper portion of FIG. 2. It is a block diagram which shows the electric constitution of the collision detection apparatus for vehicles of 1st Embodiment. It is a schematic diagram which shows the mode of the collision of the object to a bumper cover at the time of low temperature. It is a schematic diagram which shows the mode of the collision of the object to a bumper cover at the time of high temperature. It is a graph which shows the temperature characteristic of the load-displacement characteristic of a bumper cover. It is a graph which shows the temperature characteristic of the load-displacement characteristic of an intermediate member. It is a graph which compares and shows the relationship between the load applied to a piezoelectric film, and a temperature change by the presence or absence of an intermediate member. It is a flowchart which shows the flow of the collision determination process in 1st Embodiment. It is an enlarged view of the bumper part in a 2nd embodiment. It is sectional drawing of the bumper part in 3rd Embodiment. It is sectional drawing of the bumper part in 4th Embodiment. It is sectional drawing of the bumper part in 5th Embodiment.

[First Embodiment]
Hereinafter, a vehicle collision detection apparatus according to a first embodiment of the present invention will be described with reference to FIGS. As shown in FIGS. 1 and 2, the vehicle collision detection device 1 of this embodiment includes a piezoelectric film 2 (corresponding to a deformation sensor), an intermediate member 3, a speed sensor 4, a collision detection ECU 5, and the like. . This vehicle collision detection apparatus 1 detects a collision of an object (that is, a pedestrian H) with a bumper 6 provided in front of the vehicle. As shown in FIG. 3, the bumper 6 is mainly composed of a bumper cover 7, a bumper absorber 8, and a bumper reinforcement 9.

  Although not shown, the piezoelectric film 2 is a thin film-like member configured to have a piezoelectric element sandwiched between a pair of electrodes. The piezoelectric film 2 has a long rectangular shape in the vehicle width direction (that is, the vehicle left-right direction), and is provided along the vehicle width direction on the vehicle rear side of the bumper cover 7 as shown in FIGS. Moreover, the piezoelectric film 2 is arrange | positioned in the vehicle up-down direction position where the pedestrian H is assumed to collide on the vehicle rear side of the bumper cover 7, as shown in FIG.

  The piezoelectric film 2 is made of a piezoelectric polymer material such as polyvinylidene fluoride. The piezoelectric film 2 outputs an electric displacement proportional to the stress when a load is applied from the outside and a stress is applied, and conversely, when an electric displacement is applied, a distortion proportional to the electric displacement is generated. When the bumper cover 7 is deformed due to a collision with a pedestrian H or the like, the piezoelectric film 2 of the present embodiment is loaded with an intermediate member 3 described later, and outputs a voltage proportional to the load.

  Further, as shown in FIG. 1, the piezoelectric film 2 has one end portion (that is, the left end portion in the vehicle width direction) connected to the collision detection ECU 5 via a transmission line. The piezoelectric film 2 outputs an electric displacement (that is, a voltage) proportional to the load applied with the deformation of the bumper cover 7 at the time of collision to the collision detection ECU 5 via a signal line.

  In the present embodiment, a plurality of intermediate members 3 are arranged between the bumper cover 7 and the piezoelectric film 2 at a predetermined interval in the vehicle width direction. Specifically, nine intermediate members 3 are arranged at equal intervals L in the vehicle width direction. The length of the interval L between the intermediate members 3 is set to a length in the vehicle width direction (for example, about 100 mm) at which the bumper cover 7 is deformed when the pedestrian H collides. Specifically, the length of the interval L is set to about 200 mm, for example.

  The plurality of intermediate members 3 are respectively sandwiched between the bumper cover 7 and the piezoelectric film 2. Specifically, each intermediate member 3 is, for example, bonded and fixed to the rear surface of the bumper cover 7 and the front surface of the piezoelectric film 2. Each intermediate member 3 has a rectangular cross-sectional shape and extends in the vehicle vertical direction.

  Each intermediate member 3 is made of synthetic rubber (for example, ethylene propylene rubber), and as shown in FIG. 8, a predetermined load load at a high temperature is higher than a deformation amount S1 with respect to a predetermined load load F at a low temperature. It has a temperature characteristic that the deformation amount S2 with respect to F becomes larger. The material of the intermediate member 3 may be any material as long as it has a temperature characteristic equal to or higher than that of the bumper cover 7 shown in FIG. 7, and may be an elastomer, a synthetic resin, or the like.

  The speed sensor 4 is a sensor device that detects the speed of the vehicle, and is electrically connected to the collision detection ECU 5 via a signal line. The speed sensor 4 transmits a signal proportional to the vehicle speed to the collision detection ECU 5.

  The collision detection ECU 5 is composed mainly of a CPU, and controls the overall operation of the vehicle collision detection apparatus 1. As shown in FIGS. 1 and 4, the collision detection ECU 5 is provided in the vehicle and is electrically connected to the piezoelectric film 2, the speed sensor 4, and the pedestrian protection device 10. A voltage signal from the piezoelectric film 2, a speed signal from the speed sensor 4, and the like are input to the collision detection ECU 5. The collision detection ECU 5 executes a predetermined collision determination process on the basis of the voltage signal from the piezoelectric film 2 output along with the deformation of the bumper cover 7 and the speed signal from the speed sensor 4, and outputs to the bumper cover 7. A collision of an object such as a pedestrian H is detected. When the collision detection ECU 5 determines that a collision with a pedestrian has occurred, the collision detection ECU 5 outputs a control signal to operate the pedestrian protection device 10.

  The bumper 6 is for reducing an impact at the time of a vehicle collision, and includes a bumper cover 7, a bumper absorber 8, a bumper reinforcement 9, and the like. The bumper cover 7 is provided so as to cover the components of the bumper 6 and is a resin member such as polypropylene. The bumper cover 7 constitutes the appearance of the bumper 6 and at the same time constitutes a part of the appearance of the entire vehicle.

  The bumper absorber 8 is disposed at a position facing the front surface 9 a of the bumper reinforcement 9. The bumper absorber 8 is a member that has an impact absorbing function in the bumper 6 when it collides with a pedestrian H of the vehicle, and is made of, for example, foamed polypropylene.

  The bumper reinforcement 9 is a rigid member made of metal such as aluminum which is disposed in the bumper cover 7 and extends in the vehicle width direction. As shown in FIG. It is. The bumper reinforcement 9 has a front surface 9a that is a surface on the front side of the vehicle and a rear surface 9b that is a surface on the rear side of the vehicle. As shown in FIGS. 1 and 2, the bumper reinforcement 9 is attached to the front end of a side member 11 that is a pair of metal members extending in the vehicle front-rear direction.

  Usually, in a vehicle collision accident, the vehicle often collides with a pedestrian H or the like existing in the traveling direction of the vehicle (that is, in front of the vehicle). For this reason, in this embodiment, the piezoelectric film 2 is disposed on the vehicle rear side of the bumper cover 7 provided in the front of the vehicle via the intermediate member 3, and the impact caused by the collision with the pedestrian H in the front of the vehicle is It is transmitted from the bumper cover 7 to the piezoelectric film 2 via the intermediate member 3.

  Although not shown, the fitting convex portion provided on the rear surface of the bumper absorber 8 is fitted into the fitting concave portion provided on the front surface 9a of the bumper reinforcement 9, so that the bumper reinforcement of the bumper absorber 8 is provided. Assume that the attachment to the ment 9 is performed.

  For example, a pop-up hood is used as the pedestrian protection device 10. This pop-up hood raises the rear end of the engine hood instantly after detecting a vehicle collision, increases the clearance between the pedestrian H and a hard part such as the engine, and uses that space to the pedestrian H's head. The impact energy on the head of the pedestrian H is reduced. Instead of the pop-up hood, a cowl airbag or the like that buffers the impact of the pedestrian H by deploying the airbag from the engine hood outside the vehicle body to the lower portion of the front window may be used.

  Next, operation | movement at the time of the collision of the vehicle collision detection apparatus 1 in this embodiment is demonstrated. When an object such as a pedestrian H collides with the front of the vehicle, the bumper cover 7 is deformed by an impact caused by the collision with the pedestrian H. Subsequently, an external force accompanying the collision is applied to the intermediate member 3 provided on the rear surface of the bumper cover 7, and a load is applied to the piezoelectric film 2 via the intermediate member 3. At this time, the piezoelectric film 2 outputs a voltage signal proportional to the applied load to the collision detection ECU 5.

  Here, as shown in FIG. 8, the intermediate member 3 has a temperature characteristic in which the rate of increase accompanying the temperature rise of the deformation amount with respect to the predetermined load S is equal to or higher than the rate of increase in the bumper cover 7 shown in FIG. It is what has. That is, in the intermediate member 3, the deformation amount S2 with respect to the load load S at the high temperature is larger than the deformation amount S1 with respect to the predetermined load load S at the low temperature. Accordingly, as shown in FIG. 5, since the intermediate member 3 is hard and difficult to deform at low temperatures, the external force accompanying the collision is transmitted to the piezoelectric film 2 with almost no absorption by the intermediate member 3, and the piezoelectric film 2 is deformed. To do. On the other hand, when the temperature is high, as shown in FIG. 6, the intermediate member 3 becomes soft and deforms preferentially over the piezoelectric film 2 so that a part of the load is absorbed. The load is suppressed and the deformation of the piezoelectric film 2 is suppressed.

  Therefore, as shown in FIG. 9, when the temperature is changed with the same impact force applied to the bumper cover 7, the load applied to the piezoelectric film 2 increases as the temperature rises in the comparative example without the intermediate member 3. On the other hand, in the present embodiment having the intermediate member 3, the load applied to the piezoelectric film 2 is substantially constant regardless of the temperature rise. That is, by providing the intermediate member 3 between the bumper cover 7 and the piezoelectric film 2, it is possible to prevent the voltage change of the piezoelectric film 2 from being affected by the temperature rise.

  That is, in the comparative example in which the intermediate member 3 is not provided between the bumper cover 7 and the piezoelectric film 2, as shown in FIG. 7, when the temperature is higher than the deformation amount Sb1 of the bumper cover 7 with respect to a predetermined load F at a low temperature. The amount of deformation Sb2 of the bumper cover 7 with respect to the load F is increased. For this reason, the increasing rate of the deformation amount accompanying the temperature rise of the bumper cover 7 directly affects the deformation amount of the piezoelectric film 2, and the output of the piezoelectric film 2 at the time of collision increases with the temperature rise. On the other hand, in the present embodiment in which the intermediate member 3 is provided between the bumper cover 7 and the piezoelectric film 2, the distortion of the piezoelectric film 2 increases because the intermediate member 3 is not easily deformed at low temperatures as shown in FIG. 5. On the other hand, since the intermediate member 3 deforms preferentially over the piezoelectric film 2 as shown in FIG. 6 at a high temperature, the distortion of the piezoelectric film 2 is reduced. Thereby, it is suppressed that the output of the piezoelectric film 2 at the time of a collision varies with a temperature rise.

  Further, in the present embodiment, the plurality of intermediate members 3 are arranged with an interval L in the vehicle width direction that is equal to or longer than the vehicle width direction length at which the bumper cover 7 is deformed when the pedestrian H collides. As a result, as shown in FIGS. 5 and 6, it is possible to increase the probability that the pedestrian H will collide at the position in the vehicle width direction between the adjacent intermediate members 3, and the piezoelectric by providing the intermediate member 3 described above. The output adjustment effect of the film 2 can be obtained satisfactorily.

  Next, the flow of the collision determination process by the vehicle collision detection apparatus 1 having the above configuration will be described with reference to the flowchart of FIG. However, this flowchart is an example, and the present invention is not limited to this. In the collision determination process of this embodiment, it is determined whether or not a collision with the pedestrian H that requires the operation of the pedestrian protection device 10 has occurred based on the detection results of the piezoelectric film 2 and the speed sensor 4.

  First, in the flowchart of FIG. 10, in step S1 (hereinafter, step is omitted), the collision detection ECU 5 of the vehicle collision detection device 1 acquires the vehicle speed from the output from the speed sensor 4, and the vehicle speed is predetermined in S2. It is determined whether or not it is within the operating range. The operating range of the vehicle speed is, for example, a range of 25 km to 55 km / h. This operating range is due to the fact that the speed at which the pedestrian protection function of the pedestrian protection device 10 acts effectively is determined by conditions such as the vehicle shape.

  In the case of No in S2, the collision detection ECU 5 determines that the vehicle speed is not within the operating range, and returns to S1. On the other hand, in the case of Yes in S2, the collision detection ECU 5 determines that the vehicle speed is within the operating range, acquires the voltage value of the piezoelectric film 2 in S3, and proceeds to S4.

  In S4, the collision detection ECU 5 determines whether or not the voltage value of the piezoelectric film 2 is greater than or equal to a threshold value. If No in S4, that is, if the voltage value of the piezoelectric film 2 is less than the threshold value, the process returns to S1. On the other hand, if Yes in S4, that is, if the voltage value of the piezoelectric film 2 is equal to or greater than the threshold value, the process proceeds to S5, and the collision detection ECU 5 determines that a collision with the pedestrian H of the vehicle has occurred.

  Note that the threshold value for collision determination is set to a value larger than the voltage value output from the piezoelectric film 2 at the time of collision with an OFF requirement target object such as a roadside marker (that is, OFF collision). This makes it possible to distinguish a collision with a pedestrian H or the like that is an ON requirement target (ie, an ON collision) and an OFF collision.

  And in S6, collision detection ECU5 outputs the control signal which operates the pedestrian protection apparatus 10, and operates the pedestrian protection apparatus 10. FIG. Thereby, the impact to the pedestrian H by the collision with the pedestrian H of a vehicle is reduced.

  As described above, the vehicle collision detection apparatus 1 according to the first embodiment is provided along the vehicle width direction on the vehicle rear side of the bumper cover 7 of the vehicle, and accompanying the deformation of the bumper cover 7 at the time of the collision. A piezoelectric film 2 as a deformation sensor that outputs an electrical displacement (that is, voltage) by a load applied thereto, a temperature characteristic in which a deformation amount with respect to a predetermined load load F increases as the temperature rises; Based on the electrical displacement of the piezoelectric film 2 that is output along with the deformation of the bumper cover 7 and the intermediate member 3 that is sandwiched between the piezoelectric film 2 and arranged at intervals L in the vehicle width direction. A collision detection ECU 5 that is a collision detection unit that detects that an object (that is, a pedestrian H) has collided with the bumper cover 7.

  According to this configuration, a plurality of intermediate members 3 having a temperature characteristic in which the deformation amount with respect to a predetermined load is increased as the temperature rises are disposed between the bumper cover 7 and the piezoelectric film 2. Since the member 3 is hard and difficult to deform, the external force accompanying the collision is transmitted to the piezoelectric film 2 without being absorbed by the intermediate member 3 and the piezoelectric film 2 is deformed. On the other hand, since the intermediate member 3 becomes soft and deforms preferentially over the piezoelectric film 2 at a high temperature and a part of the load is absorbed, the load applied to the piezoelectric film 2 is suppressed, and the deformation of the piezoelectric film 2 is prevented. It is suppressed. Thereby, it is possible to prevent the voltage change of the piezoelectric film 2 from being affected by the temperature rise, and the collision of the vehicle collision detection device 1 caused by the variation of the output of the piezoelectric film 2 at the time of the collision with the temperature change. A decrease in detection accuracy can be prevented.

  Further, the intermediate member 3 is made of synthetic rubber, and has a temperature characteristic that an increase rate of the deformation amount with respect to a predetermined load F with a temperature increase is equal to or higher than an increase rate in the bumper cover 7.

  According to this configuration, the intermediate member 3 is made of synthetic rubber having a temperature characteristic in which an increase rate of the deformation amount with respect to a predetermined load F with a temperature increase is equal to or higher than an increase rate in the bumper cover 7. The intermediate member 3 can be hard and difficult to deform, and the intermediate member 3 can be softened and easily deformed at high temperatures. As a result, the external force associated with the collision is transmitted to the piezoelectric film 2 almost without being absorbed by the intermediate member 3 at a low temperature, whereas the intermediate member 3 is preferentially deformed over the piezoelectric film 2 at a high temperature to cause a load load. By absorbing a part of the load, the load applied to the piezoelectric film 2 can be reliably suppressed.

  Further, the intermediate member 3 is disposed with an interval L in the vehicle width direction that is equal to or longer than the vehicle width direction length at which the bumper cover 7 is deformed when the pedestrian H collides. According to this configuration, the plurality of intermediate members 3 are disposed with an interval L in the vehicle width direction that is greater than or equal to the vehicle width direction length at which the bumper cover 7 is deformed when the pedestrian H collides. And as shown in FIG. 6, the output adjustment of the piezoelectric film 2 at the time of the temperature rise by providing the above-mentioned intermediate member 3 so that the pedestrian H collides at the vehicle width direction position between the adjacent intermediate members 3. The effect can be obtained satisfactorily.

  Moreover, the intermediate member 3 is arrange | positioned at equal intervals L in the vehicle width direction. According to this configuration, the plurality of intermediate members 3 are arranged at equal intervals L along the vehicle width direction between the bumper cover 7 and the piezoelectric film 2, so that the thin film-like piezoelectric film 2 is mounted on the vehicle. It is possible to reliably prevent bending in the front-rear direction, and the piezoelectric film 2 can be stably disposed at a predetermined position on the vehicle rear side of the bumper cover 7.

  Moreover, the intermediate member 3 is extended in the vehicle up-down direction. According to this configuration, since the intermediate member 3 extends in the vehicle vertical direction, a bonding area between the piezoelectric film 2 and the intermediate member 3 can be secured, and the piezoelectric film 2 can be stably bonded to the intermediate member 3. Can be fixed.

[Second Embodiment]
Next, a second embodiment of the present invention will be described with reference to FIG. In FIG. 11, the same parts as those of the above-described embodiment are denoted by the same reference numerals, description thereof is omitted, and only different parts are described. In the vehicle collision detection apparatus 1 according to the second embodiment, as shown in FIG. 11, the plurality of intermediate members 3 are arranged at different intervals in the vehicle width direction according to the vehicle width direction position of the bumper cover 7. It is installed.

  Specifically, eight intermediate members 3 are arranged on the rear surface of the bumper cover 7. Of these, two intermediate members 3 are provided in each of the portions where the bumper cover 7 is curved in the vehicle front-rear direction, that is, the left and right corner portions C indicated by the enclosure lines in FIG. And the space | interval L2 of each intermediate member 3 in this corner part C is narrower than the space | interval L1 of the part which the other part, for example, the bumper cover 7 ahead of a vehicle has comprised linear form.

  That is, the interval L1 is set to about 300 mm to 400 mm, for example. On the other hand, the interval L2 is set to about 50 mm, for example. Each intermediate member 3 is sandwiched between the bumper cover 7 and the piezoelectric film 2 and extends in the vehicle vertical direction, as in the first embodiment. Further, as shown in FIG. 8, each intermediate member 3 has a temperature characteristic in which the rate of increase accompanying the temperature rise of the deformation amount with respect to a predetermined load F is equal to or higher than the rate of increase in the bumper cover 7 shown in FIG. 7. Have. Therefore, similarly to the first embodiment, by providing the plurality of intermediate members 3 at intervals in the vehicle width direction, it is possible to prevent the voltage change of the piezoelectric film 2 from being affected by the temperature rise. .

  In the vehicle collision detection apparatus 1 according to the second embodiment described above, the intermediate member 3 is disposed with different intervals L1 and L2 in the vehicle width direction according to the vehicle width direction position of the bumper cover 7, and at least The bumper cover 7 is disposed at a portion curved in the vehicle front-rear direction (that is, the corner portion C).

  In the vehicle collision detection device 1 of the second embodiment, the same effect as that of the first embodiment can be obtained. In particular, since the plurality of intermediate members 3 are disposed at the corner portion C where at least the bumper cover 7 is curved in the vehicle front-rear direction, the portion where the piezoelectric film 2 is arranged in a curved state and easily falls off is provided as an intermediate member. 3 is securely supported, the piezoelectric film 2 can be more stably disposed at a predetermined position on the vehicle rear side of the bumper cover 7.

[Third Embodiment]
Next, a third embodiment of the present invention will be described with reference to FIG. In FIG. 12, the same parts as those in the above embodiment are denoted by the same reference numerals, description thereof is omitted, and only different parts will be described.

  In the vehicle collision detection apparatus 1 according to the third embodiment, the plurality of intermediate members 31 are disposed with a space L in the vehicle width direction and with a predetermined space in the vehicle vertical direction. Specifically, on the rear surface of the bumper cover 7, nine vehicle width direction positions spaced at equal intervals L in the vehicle width direction shown in FIG. Individual intermediate members 31 are provided.

  The distance L between the intermediate members 31 in the vehicle width direction is equal to or greater than the vehicle width direction length (for example, about 100 mm) at which the bumper cover 7 is deformed when the pedestrian H collides, as in the first embodiment. Is set to about 200 mm, for example. The interval between the intermediate members 31 arranged in the vehicle vertical direction is set to about 20 mm to 30 mm, for example.

  Each intermediate member 31 is sandwiched between the bumper cover 7 and the piezoelectric film 2 as in the first embodiment. Each intermediate member 31 is made of synthetic rubber (for example, ethylene propylene rubber). As shown in FIG. 8, the rate of increase of the deformation amount with respect to a predetermined load F as the temperature rises is shown in FIG. It has a temperature characteristic equal to or higher than the increase rate in the cover 7. Therefore, by providing the plurality of intermediate members 31 at intervals in the vehicle width direction, it is possible to prevent the voltage change of the piezoelectric film 2 from being affected by the temperature rise as in the first embodiment. .

  In the vehicle collision detection apparatus 1 according to the third embodiment described above, the intermediate member 31 is disposed at a predetermined interval in the vehicle width direction and the vehicle vertical direction. In the vehicle collision detection apparatus 1 of the third embodiment, the same effect as that of the first embodiment can be obtained.

[Fourth Embodiment]
Next, a fourth embodiment of the present invention will be described with reference to FIG. In FIG. 13, the same parts as those in the above-described embodiment are denoted by the same reference numerals, description thereof is omitted, and only different parts are described. In the vehicle collision detection device 1 of the fourth embodiment, a support member 21 that covers the entire outer peripheral portion of the piezoelectric film 2 is provided.

  The support member 21 is made of a material (for example, synthetic resin) having higher rigidity than the piezoelectric film 2 and is for supporting the piezoelectric film 2. The support member 21 is a rectangular plate-like member that covers the entire outer peripheral portion of the piezoelectric film 2, and is provided on the vehicle rear side of the bumper cover 7 along the vehicle width direction.

  In the fourth embodiment, as in the third embodiment, the plurality of intermediate members 31 are spaced apart in the vehicle width direction shown in FIG. 2 and spaced apart in the vehicle vertical direction. Arranged. Specifically, on the rear surface of the bumper cover 7, there are 27 intermediate members, three in each of the nine positions in the vehicle width direction spaced at equal intervals L in the vehicle width direction and spaced in the vehicle vertical direction. 31 is provided. The distance L between the intermediate members 31 in the vehicle width direction is set to about 200 mm, for example. The interval between the intermediate members 31 arranged in the vehicle vertical direction is set to about 20 mm to 30 mm, for example.

  Each intermediate member 31 is sandwiched between the bumper cover 7 and the piezoelectric film 2 whose entire outer periphery is covered with the support member 21. The support member 21 and the intermediate member 31 are bonded and fixed, for example. As in the first embodiment, each intermediate member 31 is made of, for example, synthetic rubber. As shown in FIG. 8, the rate of increase of the deformation amount with respect to a predetermined load F as the temperature rises is as shown in FIG. 7. It has a temperature characteristic that is equal to or higher than the increase rate in the bumper cover 7 shown. Further, it is assumed that the support member 21 has a rigidity that does not hinder the deformation of the piezoelectric film 2 at the time of collision.

  Next, the operation | movement at the time of the collision of the vehicle collision detection apparatus 1 in 4th Embodiment is demonstrated. When a pedestrian H or the like collides in front of the vehicle, the bumper cover 7 is deformed by an impact caused by the collision with the pedestrian H. Subsequently, an external force due to the collision is applied to the intermediate member 31 provided on the rear surface of the bumper cover 7, and a load is applied to the piezoelectric film 2 whose entire outer peripheral portion is covered by the support member 21 via the intermediate member 31. At this time, the piezoelectric film 2 outputs a voltage signal proportional to the applied load to the collision detection ECU 5. As in the first embodiment, since the plurality of intermediate members 31 are arranged at intervals in the vehicle width direction, it is possible to prevent the voltage change of the piezoelectric film 2 from being affected by the temperature rise. It has become.

  In the vehicle collision detection apparatus 1 of the fourth embodiment described above, the same effect as that of the first embodiment can be obtained. In particular, since the entire outer peripheral portion of the piezoelectric film 2 is covered with the support member 21, the thin film-like piezoelectric film 2 can be stably fixed to the intermediate member 3.

[Fifth Embodiment]
Next, a fifth embodiment of the present invention will be described with reference to FIG. In FIG. 14, the same parts as those in the above embodiment are denoted by the same reference numerals, description thereof is omitted, and only different parts will be described.

  In the fifth embodiment, the support member 22 is provided on the surface of the piezoelectric film 2 on the vehicle front side. The support member 22 is bonded and fixed between the intermediate member 3 and the piezoelectric film 2. The support member 22 is made of a material (for example, synthetic resin) having higher rigidity than the piezoelectric film 2. The support member 22 is a rectangular plate-like member, and is provided on the vehicle rear side of the bumper cover 7 along the vehicle width direction. The support member 22 is assumed to have a rigidity that does not hinder the deformation of the piezoelectric film 2 at the time of collision.

  In the fifth embodiment, the plurality of intermediate members 3 are arranged at intervals L in the vehicle width direction, as in the first embodiment. Specifically, as shown in FIG. 2, nine intermediate members 3 are arranged at equal intervals L in the vehicle width direction. In addition, the intermediate member 3 of the fifth embodiment is disposed between the piezoelectric film 2 and the bumper cover 7 via the support member 22. Each intermediate member 3 is made of, for example, synthetic rubber, as in the first embodiment. As shown in FIG. 8, the rate of increase accompanying the temperature rise of the deformation amount with respect to a predetermined load F is shown in FIG. 7. It has a temperature characteristic that is equal to or higher than the increase rate in the bumper cover 7 shown.

  Next, the operation | movement at the time of the collision of the vehicle collision detection apparatus 1 in 5th Embodiment is demonstrated. When a pedestrian H or the like collides in front of the vehicle, the bumper cover 7 is deformed by an impact caused by the collision with the pedestrian H. Subsequently, an external force due to the collision is applied to the intermediate member 3 provided on the rear surface of the bumper cover 7, and a load is applied to the piezoelectric film 2 whose outer peripheral portion is covered with the support member 22 through the intermediate member 3. Will be added. At this time, the piezoelectric film 2 outputs a voltage signal proportional to the applied load to the collision detection ECU 5. In addition, by providing the some intermediate member 3 at intervals in the vehicle width direction, it is possible to prevent the voltage change of the piezoelectric film 2 from being affected by the temperature rise as in the first embodiment. .

  In the vehicle collision detection apparatus 1 according to the fifth embodiment described above, the piezoelectric film 2 is covered with the support member 22 on the rear side of the outer peripheral portion. Also in the vehicle collision detection apparatus 1 of the fifth embodiment, the same effect as that of the first embodiment can be obtained. In particular, since the rear side of the outer peripheral portion of the piezoelectric film 2 is covered by the support member 22, it can be disposed on the rear side of the bumper cover 7 with the thin film-like piezoelectric film 2 stably supported.

[Other Embodiments]
The present invention is not limited to the above-described embodiment, and various modifications or expansions can be made without departing from the spirit of the present invention. For example, in the said embodiment, although the piezoelectric film 2 shall be used as a deformation | transformation sensor, it is not restricted to this. Any deformation sensor may be used as long as it outputs an electric displacement due to a load applied in accordance with the deformation of the bumper cover 7 at the time of a collision. In addition, a pyrofilm made of pyroelectric material may be used. Also, the same effects as those of the above embodiment can be obtained. The electric displacement means a change in electric energy. The electric displacement includes a change in an optical signal, and an optical fiber may be used as a deformation sensor.

  In the fifth embodiment, the piezoelectric film 2 is disposed on the surface of the support member 22 on the vehicle rear side. However, the piezoelectric film 2 may be disposed on the surface of the support member 22 on the vehicle front side. . Further, it is assumed that the number and location of the intermediate members 3 and 31 can be changed as appropriate.

1 Vehicle collision detection device 2 Piezoelectric film (deformation sensor)
21, 22 Support member 3, 31 Intermediate member 5 Collision detection ECU (collision detection unit)
6 Bumper 7 Bumper cover 8 Bumper absorber 9 Bumper reinforcement L, L1, L2 Distance H Pedestrian

Claims (9)

A deformation sensor (2) that is provided along the vehicle width direction on the vehicle rear side of the bumper cover (7) of the vehicle, and that outputs an electric displacement due to a load applied in association with the deformation of the bumper cover at the time of a collision;
An intermediate member having a temperature characteristic in which the amount of deformation with respect to a predetermined load increases as the temperature rises, and is interposed between the bumper cover and the deformation sensor and arranged in a plurality in a vehicle width direction. (3, 31),
A collision detection unit (5) for detecting that an object (H) has collided with the bumper cover, based on an electrical displacement of the deformation sensor output in association with the deformation of the bumper cover;
Bei to give a,
The intermediate member has a temperature characteristic in which an increase rate of the deformation amount with respect to a predetermined load is increased by a temperature increase that is equal to or higher than an increase rate in the bumper cover. A vehicle collision detection device (1) that is disposed with a gap (L, L1) that is not less than a length in the vehicle width direction to be deformed, spaced in the vehicle width direction . The collision detection device for a vehicle according to claim 1 , wherein the intermediate members are arranged at equal intervals (L) in the vehicle width direction. 2. The vehicle collision detection device according to claim 1 , wherein the intermediate member is disposed at a different interval (L1, L2) in the vehicle width direction according to a vehicle width direction position of the bumper cover. 4. The vehicle collision detection device according to claim 3 , wherein the intermediate member is disposed at least in a portion (C) where the bumper cover is curved in the vehicle longitudinal direction. The said intermediate member (3) is a vehicle collision detection apparatus as described in any one of Claim 1 to 4 extended in the vehicle up-down direction. The said intermediate member (31) is a vehicle collision detection apparatus as described in any one of Claim 1 to 4 arrange | positioned at intervals in the vehicle up-down direction. The said collision sensor is a vehicle collision detection apparatus as described in any one of Claim 1 to 6 with which at least one part of the outer peripheral part is covered with the supporting member (21, 22). The collision detection device for a vehicle according to any one of claims 1 to 7 , wherein the deformation sensor is a piezoelectric film. The vehicle collision detection device according to any one of claims 1 to 8 , wherein the intermediate member is made of any one of a synthetic rubber, an elastomer, and a synthetic resin.

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