JP2009227089A - Vehicle collision detecting device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a vehicle collision detecting device for detecting a pressure change in a chamber while allowing easy mounting of a pressure sensor on a chamber member and surely securing required sensor accuracy. <P>SOLUTION: A pressure receiving portion 7a of the pressure sensor 7 is inserted through a mounting hole 11h of the chamber member 1 into a chamber space 11a and mounted therein for detecting collision on the vehicle bumper in accordance with the detection result of the pressure sensor 7. A clearance S is provided between the mounting hole 11h and the pressure receiving portion 7a. The area of the clearance S is set within a threshold value which is defined by a predetermined relational expression derived from a relationship between a speed variation and the area of the clearance to the volume of the chamber space. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a vehicle collision detection device, and more particularly to a vehicle collision detection device that determines the type of a collision object based on a pressure change in a vehicle bumper.

  In recent years, for the purpose of protecting pedestrians, in order to protect pedestrians when a collision detection device is attached to the vehicle bumper, the type of collision object is determined at the time of collision with the vehicle, and it is determined that the vehicle is a pedestrian Techniques for operating these devices (for example, active hoods and cowl airbags) have been proposed, and their practical application has been studied.

  That is, when the collision object is not a pedestrian, various adverse effects occur when a protective device on the hood (for example, an active hood) is operated. For example, if it cannot be distinguished from a pedestrian when it collides with a lightweight fallen object such as a triangular cone or a signboard under construction, the protection device is activated wastefully and extra repair costs are generated. In addition, if it is indistinguishable from a pedestrian when it collides with a fixed wall such as a concrete wall or a vehicle, the hood will move backward with the hood lifted, so there is a risk that the hood may enter the passenger compartment and harm the passenger. is there. As described above, it is required to accurately determine the type of the collision object.

  2. Description of the Related Art Conventionally, a vehicle collision detection device has been proposed in which a chamber member is disposed in an absorber portion in a vehicle bumper and a type of a collision object is determined by detecting a pressure change in the chamber space at the time of a collision. (For example, see Patent Documents 1 and 2).

  These conventional vehicle collision detection devices include a chamber member disposed in a vehicle bumper and having a chamber space formed therein, and a pressure sensor for detecting the pressure in the chamber space, and a pressure receiving portion of the pressure sensor. The pressure sensor is attached to the chamber member so as to be inserted into the chamber space from the mounting hole provided in the chamber member, and the collision with the vehicle bumper is detected based on the detection result of the pressure sensor.

For example, air is sealed in the chamber space, and a pressure receiving portion of the pressure sensor is inserted into the chamber space via an attachment hole. In such an example, the pressure sensor is a sensor device that can detect a gas pressure, and is configured to be able to detect a change in pressure of air in the chamber space. In this case, the pressure in the chamber space needs to be equal to the outside, that is, maintained at atmospheric pressure at the time of non-collision. On the other hand, since the pressure receiving portion of the pressure sensor is attached by being inserted into the chamber space from the attachment hole, the mounting hole area is required to have a mechanical tolerance with respect to the diameter of the pressure receiving portion to be inserted.
JP 2007-290682 A JP 2007-290689 A

  However, the larger the mounting hole area, the easier it is to attach the pressure sensor to the chamber member. On the other hand, if the mounting hole area is too large, the pressure in the chamber space will be lost at the time of collision, resulting in a decrease in sensor accuracy. There is a risk of inviting. Moreover, the chamber member may be provided with other holes such as a drain hole in addition to the mounting holes.

    Conventionally, no effective proposal has been made regarding the area of the mounting hole or the drainage hole in relation to the required sensor accuracy and chamber volume.

  The present invention has been made in view of the above problems, and in a vehicle collision detection device for detecting a pressure change in a chamber disposed in a vehicle bumper, the pressure sensor can be easily attached to a chamber member. Another object of the present invention is to provide a technique capable of reliably ensuring the sensor accuracy required for a pressure sensor.

  Hereinafter, each means suitable for solving the above-described problems will be described with additional effects and the like as necessary.

1. A chamber member disposed in the vehicle bumper and having a chamber space formed therein; and a pressure sensor configured to detect a pressure in the chamber space, and a pressure receiving portion of the pressure sensor is provided in the chamber member. In the vehicle collision detection device configured to be inserted by being inserted into the chamber space from an attachment hole and configured to detect a collision with the vehicle bumper based on a detection result of the pressure sensor,
A vehicle collision detection device, wherein a gap is provided at least between the attachment hole and the pressure receiving portion.

  According to the means 1, since the gap is provided between the pressure receiving portion of the pressure sensor and the mounting hole, the pressure sensor can be easily attached to the chamber member, and the inside of the chamber space can be connected to the outside via the gap. Since the pressure is easily maintained, the sensor accuracy required for the pressure sensor can be ensured.

  2. The area of the gap is set within a threshold defined by a predetermined relational expression defined in relation to the target sensor accuracy of the pressure sensor with respect to the volume of the chamber space. The vehicle collision detection device according to claim 1.

  According to the means 2, it is possible to prevent the sensor accuracy targeted for the pressure sensor from becoming difficult to be secured due to the gap being too large, and the area of the gap is defined in relation to the target sensor accuracy. Since it is expressed by a predetermined relational expression, it becomes easy to ensure target sensor accuracy.

  3. The vehicle collision detection device according to claim 2, wherein the predetermined relational expression is derived from a relationship between a speed variation with respect to a volume of the chamber space and an area of a gap.

  According to the means 3, variation due to the speed of the sensor accuracy of the pressure sensor can be prevented, and good sensor accuracy can be obtained by optimizing the gap area.

  4). In addition to the mounting holes, the chamber member is provided with other holes that allow the chamber space to communicate with the outside, and the total area of the other holes and the gap is the total area of the chamber space. 4. The vehicle collision detection device according to any one of means 2 or 3, wherein the vehicle collision detection device is set within the threshold with respect to a volume.

  According to the means 4, good sensor accuracy can be obtained by optimizing the area of the whole hole (gap) that communicates the chamber space including other holes with the outside.

  5). 4. The vehicle collision detection device according to claim 3, wherein the other hole is a drain hole of the chamber member.

  According to the means 5, good sensor accuracy can be obtained by optimizing the area of the whole hole (gap) that communicates the chamber space including the drain hole and the outside.

6). The vehicle collision detection device according to any one of means 2 to 5, wherein an area of the gap or the total area is set to 0.1 mm ² or more and 300 mm ² or less.

  According to the means 6, it is easy to attach the pressure sensor to the chamber member, and it is possible to obtain good sensor accuracy in which, for example, speed variation is suppressed to ± 10% or less.

  Hereinafter, an embodiment in which a vehicle collision detection device of the present invention is embodied will be described in detail with reference to the drawings. FIG. 1 is a cross-sectional view of a vehicle collision detection device according to an embodiment of the present invention disposed in a vehicle bumper as viewed from the vehicle width direction. FIG. 2 is a diagram schematically illustrating a state in which the pressure sensor is attached to the chamber member in the vehicle collision detection device of the present embodiment. In FIG. 2, the bumper reinforcement 2 to which the main body having the sensor element of the pressure sensor 7 is fixed is omitted. For convenience of illustration, the orientation and shape of the pressure sensor 7 and the chamber member 1 are different from those in FIG.

  As shown in FIGS. 1 and 2, the vehicle collision detection apparatus according to the embodiment of the present invention includes a chamber member 1 disposed in a vehicle bumper and having a chamber space 11a formed therein, and a chamber space 11a. A pressure sensor 7 for detecting the pressure of the pressure sensor 7, and a pressure introducing pipe 7 a as a pressure receiving portion of the pressure sensor 7 (hereinafter, also referred to as a pressure receiving portion 7 a) is provided in a mounting hole 11 h (see FIG. 2) is inserted into the chamber space 11a, and a collision with the vehicle bumper is detected based on the detection result of the pressure sensor 7. As shown in FIG. 2, this embodiment is characterized in that a gap S is provided at least between the mounting hole 11 h of the chamber member 1 and the pressure receiving portion 7 a of the pressure sensor 7.

  Hereinafter, first, an outline of the entire vehicle bumper, and then a structure for attaching the pressure sensor 7 to the chamber member 1 will be described.

  As shown in FIG. 1, a bumper reinforcement 2, a chamber member 1, and an absorber 3 are provided in the vehicle bumper (the vehicle rear side of the bumper cover 4). The chamber member 1 and the absorber 3 are disposed on the vehicle front side of the bumper reinforcement 2, and the absorber 3 is disposed adjacent to the lower portion of the chamber member 1. A front side member 5 of the vehicle is adjacent to the bumper reinforcement 2 on the vehicle rear side.

  The chamber member 1 is disposed in the vehicle bumper on the vehicle front side of the bumper reinforcement 2, and a chamber space 11 a is formed inside the main body 11 having a shape substantially along the bumper reinforcement 2. The entire chamber member 1 is integrally formed by blow molding using a resin material (for example, low density polyethylene).

  The bumper reinforcement 2 is a substantially band-shaped metal frame having a surface facing the bumper cover 4 and is fixed to the front side member 5 of the vehicle in a state along the width direction of the vehicle. As shown in FIG. 1, the bumper reinforcement 2 has an eye-shaped cross-sectional structure in which a beam is provided.

  The absorber 3 is fixed to the lower side of the bumper reinforcement 2, and the surface facing the inner wall surface of the bumper cover 4 is formed in a curved shape that is curved along the inner peripheral surface of the bumper cover 4 (in the drawing). Is abbreviated to a rectangular cross section). The absorber 3 is generally formed of a foamed resin in order to absorb the impact caused by the collision by its own deformation.

  The pressure sensor 7 is, for example, a known sensor that can detect a change in gas pressure, and includes a pressure introduction pipe 7a as a pressure receiving portion that introduces pressure into the sensor element. The main body of the pressure sensor 7 having a sensor element is fixed in the bumper reinforcement 2, and the distal end side of the pressure introduction pipe (pressure receiving portion) 7 a is inserted into the chamber space 11 a of the chamber member 1.

  The chamber member 1 disposed on the vehicle front side of the bumper reinforcement 2 transmits its deformation due to the impact of the collision to the pressure sensor 7 as a pressure fluctuation accompanying distortion of the chamber space 11a provided therein. The pressure sensor 7 detects the pressure fluctuation of the air introduced from the chamber space 11a via the pressure receiving part 7a inserted into the chamber space 11a, and transmits it to, for example, a control circuit having a determination circuit (not shown). The control circuit detects the presence or absence of a collision of a pedestrian or the like with the vehicle bumper based on the pressure detection signal input from the pressure sensor 7.

  As described above, the chamber member 1 has a chamber space 11a formed inside the main body 11, and gas (air) is sealed in the chamber space 11a. In the default state, the gas in the chamber space 11a is ideally maintained at the same pressure as the atmospheric pressure. For this purpose, the chamber space 11a is preferably communicated with the outside.

  Here, as described above, since the pressure receiving portion 7a of the pressure sensor 7 is inserted into the chamber space 11a from the mounting hole 11h of the chamber member 1, the vehicle collision detection device of this embodiment is shown in FIG. As described above, a gap S is provided between the inserted pressure receiving portion 7a and the mounting hole 11h. Thereby, atmospheric pressure and the pressure in the chamber space 11a can be made equal. Moreover, the structural effect that the assembly of the pressure sensor 7 to the chamber member 1 is facilitated can also be obtained.

  The present inventor can obtain the above effect by providing the gap S between the pressure receiving portion 7a of the pressure sensor 7 and the mounting hole 11h of the chamber member 1, but if the area of the gap S is too large, the collision occurs. It has been found that the sensor accuracy of the pressure sensor 7 decreases due to the difference (variation) in the pressure change in the chamber space 11a due to the change in speed (high and low).

  3A and 3B are diagrams showing the relationship between the size of the gap area and the speed variation of the pressure change amount. FIG. 3A shows a case where the gap area is small, and FIG. 3B shows a case where the gap area is large. . As shown in FIG. 3 (a), when the gap area is smaller than when there is no gap, the variation in the pressure change amount in the chamber space due to the collision speed is small, but shown in FIG. 3 (b). Thus, when the gap area is larger than when there is no gap, the variation in the amount of pressure change in the chamber space due to the level of the collision speed increases. This is considered to be because when the gap area is large, the pressure fluctuation caused by leakage from the gap also increases.

  Therefore, the difference in pressure value when the collision speed is different differs depending on the gap area, and the smaller the gap area, the more the fluctuation due to the difference in the collision speed can be suppressed.

  Thus, the chamber member of the pressure sensor 7 is provided by providing the clearance S between the attachment portion of the pressure sensor 7 to the chamber member 1, that is, the pressure receiving portion 7 a of the pressure sensor 7 and the attachment hole 11 h of the chamber member 1. Assembly to 1 becomes easy. Further, at this time, by reducing the area of the gap S, it is possible to suppress the pressure fluctuation caused by the leakage from the gap S and prevent the sensor accuracy of the pressure sensor 7 from being lowered.

  In view of this, the present inventor is able to secure the target sensor accuracy of the pressure sensor 7 by suppressing the difference in the pressure change amount (speed variation) due to the collision speed if the area of the gap S is kept small. Were verified by experiments, and the optimization of the area of the gap S formed in the chamber member 1 was intended.

  FIG. 4 is a graph showing the relationship between the difference in chamber volume and the pressure and the area of the gap S obtained by the above-described experiment. FIG. The relationship between the gap areas, FIG. 5B, shows the relationship between the pressure and the gap area when the chamber volume is relatively large.

As shown in FIGS. 4A and 4B, in this experiment, two chamber members having a chamber volume of 411 [cm ³ ] and 1961 [cm ³ ] are used, and the same collision energy of 120 [J] is applied to the collision velocity. Were applied at 25 km / h and 55 km / h, respectively.

As shown in FIGS. 4 (a) and 4 (b), in both chamber members of chamber volumes 411 [cm ³ ] and 1961 [cm ³ ], the detected pressure only decreases as the gap area increases. In addition, it was confirmed that the difference (speed variation) in the pressure change amount on the vertical axis of the graph also increased between the collision speed of 25 km / h and 55 km / h. That is, in FIGS. 4 (a) and 4 (b), when the clearance area is about 44 [mm ² ], the collision speed is 25 km / h (lower plot) and between 55 km / h (upper plot). The difference in the pressure change amount (speed variation) is shown by using an arrow, but it can be easily seen from the graph that the interval indicated by this arrow becomes narrower and larger as the gap area becomes smaller.

  Therefore, although there is a difference depending on the chamber volume, it has been found that a decrease in sensor accuracy due to speed variation can be reduced by reducing the gap area.

  Next, the present inventor calculated the relationship between the speed variation for each chamber volume and the gap area based on the experimental results shown in FIGS. Subsequently, the relationship between the chamber volume and the gap area with respect to the target speed variation was obtained from the relationship between the calculated speed variation and the gap area.

  FIG. 5A is a graph showing the relationship between the speed variation and the gap area for each chamber volume, and FIG. 5B is a graph showing the relationship between the chamber volume and the gap area with respect to the target speed variation.

As shown in FIG. 5A, in both cases of the chamber volume 411 [cm ³ ] and 1961 [cm ³ ], the speed variation increases linearly as the gap area increases, but the chamber volume is small. In the case of 411 [cm ³ ], the increase in speed variation becomes steeper. From the graph of the linear function shown in the same figure, when the velocity variation is y and the gap area [mm ² ] is x, the relational expression y = 0.0001x + 0.0103 in the case of the chamber volume 411 [cm ³ ]. In the case of (primary expression) and chamber volume 1961 [cm ³ ], the relational expression (primary expression) y = 0.0008x + 0.006 was obtained.

Next, as shown in FIGS. 5A and 5B, first, a clearance area of about 25 [mm ² ] with respect to the chamber volume 411 [cm ³ ] when the speed variation is 0.06 (± 6%) is shown. 5 (b), and then plot the gap area of about 68 [mm ² ] against the chamber volume 1961 [cm ³ ] when the speed variation is 0.06 (± 6%). The relationship between the chamber volume and the gap area when the speed variation was 0.06 (± 6%) was obtained by connecting the plotted points with straight lines. Similarly, the gap area of about 47 [mm ² ] against the chamber volume 411 [cm ³ ] when the speed variation is 0.1 (± 10%) is plotted in FIG. 5B, and then the speed variation is 0. By plotting a gap area of about 118 [mm ² ] against a chamber volume of 1961 [cm ³ ] at 1 (± 10%) in the same figure and connecting both plot points with a straight line, the speed variation is 0. The relationship between the chamber volume and the gap area at 1 (± 10%) was determined. Furthermore, by the same method, the relationship between the chamber volume and the clearance area when the speed variation is 0.02 (± 2%), 0.04 (± 4%), 0.08 (± 8%) is also obtained. Are also shown in the figure.

As shown in FIG. 5 (b), in any speed variation from 0.02 (± 2%) to 0.1 (± 10%), the smaller the chamber volume, the smaller the gap area must be. However, it has been found that if the speed variation can be tolerated, the gap area for each chamber volume can be increased accordingly. From the graph of the linear function shown in the figure, when the gap area [mm ² ] is y and the chamber volume [cm ³ ] is x, when the speed variation is 0.1 (± 10%), y = When the relational expression (primary expression) is 0.0454x + 28.57 and the speed variation is 0.08 (± 8%), the relational expression (primary expression) y = 0.036x + 21.882 and the speed variation is 0.8. In the case of 06 (± 6%), the relational expression (primary expression) y = 0.0267x + 15.194, and in the case where the speed variation is 0.04 (± 4%), the relation y = 0.0173x + 8.506 When the equation (primary equation) and the speed variation were 0.02 (± 2%), the relational equation (primary equation) y = 0.008x + 1.8182 was obtained.

From the result shown in FIG. 5 (b), for example, when it is desired to keep the speed variation within 0.1 (± 10%) as the target sensor accuracy, for each chamber volume [cm ³ ], What is necessary is just to set clearance gap area [mm < ² >] within the threshold value (area value) obtained by the relational expression (primary expression) of y = 0.0454x + 28.57. For example, if the allowable speed variation is ± 10%, the gap area can be increased to nearly 120 mm ² when the chamber volume is 2000 cm ³ .

On the other hand, for example, when it is desired to suppress the speed variation within 0.02 (± 2%) as the target sensor accuracy, each gap area [mm ² ] is set to y = y for each chamber volume [cm ³ ]. What is necessary is just to set within the threshold value (area value) obtained by the relational expression (primary expression) of 0.008x + 1.8182. For example, if the allowable speed variation is ± 2%, the gap area must be smaller than 20 mm ² when the chamber volume is 2000 cm ³ .

  Similarly, if you want to keep the speed variation as the target sensor accuracy within 0.04 (± 4%), 0.06 (± 6%), and 0.08 (± 8%) What is necessary is just to set within the threshold value (area value) obtained by (primary formula).

Actually, the variation due to the speed varies depending on the pressure sensor mounted for each vehicle type, but it is desirable to suppress it to ± 10% or less, for example. On the other hand, the normal chamber volume is around 6000 cm ³ Therefore, it is preferable to keep the area of the gap S within, for example, 300 mm ² . On the other hand, in this embodiment, since the clearance S is provided at least between the attachment hole 11h and the pressure receiving portion 7a, the area of the clearance S should not be 0 [zero]. If it is ² , the operational effect of facilitating the assembly of the pressure sensor 7 to the chamber member 1 can be obtained, and the speed variation can be minimized. When considering the gap S, the lower limit can of course be set based on the tolerance required in mechanical engineering, in addition to the minimum gap of 0.1 mm ² or more in the present embodiment.

  By the way, the chamber member 1 may be provided with a drain hole or the like as another hole for communicating the chamber space 11a with the outside in addition to the mounting hole 11h described above. Therefore, in the present embodiment, the total area obtained by combining the areas of the other holes and the gap area described above is set within the threshold value described above with respect to the chamber volume.

  FIG. 6 is a cross-sectional view schematically showing a structure in which a water drain hole Wh is provided in the chamber member 1 in addition to the gap S between the pressure receiving portion 7a of the pressure sensor 7 and the mounting hole 11h.

  As shown in FIG. 6, in the present embodiment, the chamber member 1 is formed with a drain hole Wh in the bottom of the chamber member 1 in addition to the mounting hole 11 h described above. The drain hole Wh is provided to prevent water from accumulating in the chamber member 1 and affecting the pressure variation of the air in the chamber space 11a.

  It is clear that the variation in the pressure change in the chamber space 11a due to the collision speed is also caused by the pressure fluctuation caused by the leakage from the drain hole Wh. Therefore, in the present embodiment, the total area obtained by combining the area of the drain hole Wh and the area of the gap S shown in FIG. 2 is the predetermined amount described above for each chamber volume with respect to the volume of the chamber space 11a. It was set within the threshold value defined by the relational expression.

Thereby, even when other holes such as the drain hole Wh are provided, the clearance S between the mounting hole 11h of the chamber member 1 and the pressure receiving portion 7a of the pressure sensor 7 in consideration of the other holes. Can be set. In addition, the area of the other holes such as the drain hole Wh can be set without reducing the sensor accuracy. Furthermore, in the present embodiment, only one water drain hole Wh is formed in the chamber member 1 in addition to the attachment hole 11h. It is also possible to investigate how many drain holes can be formed in addition to the gap S between the two.
As described above, in practice, it is desirable to keep the speed variation within ± 10%, while the normal chamber volume is around 6000 cm ^3. Therefore, it is preferable to keep the upper limit of the total area, which is the sum of the area of the drain hole Wh and the area of the gap S, within 300 mm ² , for example. On the other hand, the lower limit of the total area may be 0.1 mm ² for the reason described above.

  As described above, according to the present embodiment, since the gap S is provided between the mounting hole 11h of the chamber member 1 and the pressure receiving portion 7a of the pressure sensor 7, the pressure sensor 7 can be easily attached to the chamber member 1. In addition, since the inside of the chamber space 11a is easily maintained at the same pressure as the outside through the gap S, it is possible to ensure the sensor accuracy required for the pressure sensor 7.

  In addition, the area of the gap S is set within the threshold value defined by the above-described predetermined relational expression defined in relation to the target sensor accuracy of the pressure sensor 7 with respect to the volume of each chamber space 11a. Thus, it becomes easy to ensure the target sensor accuracy of the pressure sensor 7.

  In the present embodiment, since the above-described predetermined relational expression is derived from the relationship between the speed variation with respect to the volume of the chamber space 11a and the area of the gap S, variation due to the speed of the sensor accuracy of the pressure sensor 7 can be prevented. Good sensor accuracy can be obtained by optimizing the area of the gap S.

  Further, the chamber member 1 is provided with a drain hole Wh as another hole for communicating the chamber space 11a and the outside in addition to the attachment hole 11h, and the area of the drain hole Wh and the area of the gap S are matched. Since the total area is set within the above-described threshold with respect to the volume of each chamber space 11a, the entire hole (gap) that communicates the outside with the chamber space 11a including the drain hole Wh as another hole. Good sensor accuracy can be obtained by optimizing the area.

  Thus, the threshold value defined by the predetermined relational expression obtained by the above-described experiment is applied not only to the clearance of the attachment port of the pressure sensor 7 to the chamber member 1 but also to other holes. For example, the gap of the attachment port of the pressure sensor 7 to the chamber member 1 can be made small and other holes can be combined and set within the threshold value. That is, the clearance of the attachment port of the pressure sensor 7 to the chamber member 1 may be set within the threshold value, and if there are other holes, the clearance of the attachment port of the pressure sensor 7 may be reduced and If these holes are combined and set within the threshold value, a target speed variation, for example, ± 10% or less can be obtained.

That is, according to the present embodiment, since the area of the gap S or the total area is set to 0.1 mm ² or more and 300 mm ² or less, the pressure sensor 7 can be easily attached to the chamber member 1 and the speed can be increased. Good sensor accuracy can be obtained in the pressure sensor 7 with variation being suppressed to ± 10% or less.

  As described above, according to this embodiment, in the vehicle collision detection device that detects a pressure change in the chamber member 1 disposed in the vehicle bumper, the pressure sensor 7 can be easily attached to the chamber member 1. In addition, the sensor accuracy required for the pressure sensor 7 can be reliably ensured.

  In addition, this invention is not limited to embodiment mentioned above, A various change is possible in the range which does not deviate from the main point of this invention. For example, an example in which the gap S and the drain hole Wh are formed has been shown. Of course, holes other than these may be provided in the chamber member, and in that case, the total area including the areas of the holes is The threshold value is set within the threshold defined by the above-described predetermined relational expression.

It is sectional drawing which looked at the vehicle collision detection apparatus of embodiment of this invention arrange | positioned in a vehicle bumper from the vehicle width direction. It is a figure which shows the outline of the state which attached the pressure sensor to the chamber member in the collision detection apparatus for vehicles of embodiment of this invention. It is a figure which shows the relationship between the magnitude | size of a clearance gap area, and the speed variation of the amount of pressure changes, (a) shows the case where the clearance gap area is small, (b) shows the case where the clearance gap area is large, respectively. It is a graph which shows the difference of a chamber volume, and the relationship of a pressure and a clearance area, (a) is a relationship of the pressure and clearance gap area when a chamber volume is comparatively small, (b) is a case where a chamber volume is comparatively large. The relationship between pressure and gap area is shown respectively. (A) is a graph showing the relationship between the speed variation and the gap area for each chamber volume, and (b) is a graph showing the relationship between the chamber volume and the gap area with respect to the target speed variation. It is sectional drawing which shows the outline of the structure which provided the drainage hole in the chamber member in addition to the clearance gap between the pressure receiving part and attachment hole of a pressure sensor.

Explanation of symbols

1: Chamber member 11: Body 11a: Chamber space 2: Bumper reinforcement 3: Absorber 4: Bumper cover 5: Front side member 7: Pressure sensor 7a: Pressure introducing pipe (pressure receiving portion)
11h: mounting hole S: gap Wh: drain hole

Claims (6)

A chamber member disposed in the vehicle bumper and having a chamber space formed therein; and a pressure sensor configured to detect a pressure in the chamber space, and a pressure receiving portion of the pressure sensor is provided in the chamber member. In the vehicle collision detection device configured to be inserted by being inserted into the chamber space from an attachment hole and configured to detect a collision with the vehicle bumper based on a detection result of the pressure sensor,
A vehicle collision detection device, wherein a gap is provided at least between the attachment hole and the pressure receiving portion.   The area of the gap is set within a threshold defined by a predetermined relational expression defined in relation to a target sensor accuracy of the pressure sensor with respect to a volume of the chamber space. Item 2. The vehicle collision detection device according to Item 1.   The vehicle collision detection device according to claim 2, wherein the predetermined relational expression is derived from a relationship between a speed variation with respect to a volume of the chamber space and an area of a gap.   In addition to the mounting holes, the chamber member is provided with other holes that allow the chamber space to communicate with the outside, and the total area of the other holes and the gap is the total area of the chamber space. The vehicle collision detection device according to claim 2, wherein the vehicle collision detection device is set within the threshold with respect to a volume.   The vehicle collision detection device according to claim 3, wherein the other hole is a drain hole of the chamber member. 6. The vehicle collision detection device according to claim ² , wherein an area of the gap or the total area is set to 0.1 mm ² or more and 300 mm ² or less.

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