WO2016157734A1 - Vehicle collision detection device - Google Patents

Abstract

A vehicle collision detection device according to the present invention has: a bumper absorber (2) that is disposed at a vehicle front side of a bumper reinforcement (9); a detection tube member (3) that is mounted in a groove section (2a) formed on the bumper absorber and that has a hollow section (3a) formed therein; and a pressure sensor (4) that detects the pressure in the hollow section. The vehicle collision detection device detects a collision of an object against a bumper on the basis of a pressure detection result obtained by the pressure sensor. While mounted in the groove section of the bumper absorber, the detection tube member is configured such that load/pressure-change characteristic, which is the relationship between a load imposed at the time of a collision and a pressure change in the hollow section, has temperature characteristics that offset the temperature characteristic of the load/displacement characteristic of the bumper absorber and such that a detected pressure value detected by the pressure sensor becomes equal to or higher than a predetermined reference value that is required to determine a collision of the object.

Description

Vehicle collision detection device Cross-reference of related applications

This application is based on Japanese Patent Application No. 2015-76091 filed on April 2, 2015, the contents of which are incorporated herein by reference.

The present disclosure relates to a vehicle collision detection device for detecting a collision with a pedestrian or the like.

Conventionally, there are vehicles equipped with a pedestrian protection device for reducing the impact on the pedestrian when the pedestrian collides with the vehicle. In this vehicle, a bumper unit is provided with a collision detection device, and when this sensor detects that a pedestrian or the like has collided with the vehicle, the pedestrian protection device is activated to reduce the impact on the pedestrian. . An example of a pedestrian protection device is a pop-up hood. This pop-up hood raises the rear end of the engine hood when a vehicle collision is detected, increases the clearance (clearance) between the pedestrian and hard parts such as the engine, and uses that space to the pedestrian's head. Absorbs collision energy and reduces impact on the head.

In the above-described vehicle collision detection device, a chamber member having a chamber space formed therein is disposed on the vehicle front side of a bumper reinforcement in a vehicle bumper, and the pressure in the chamber space is measured by a pressure sensor. To detect. With this configuration, when an object (pedestrian or the like) collides with the bumper (bumper cover), the chamber member is deformed along with the deformation of the bumper cover, and a pressure change is generated in the chamber space. The pressure sensor detects this pressure change to detect a pedestrian collision.

In recent years, a tube-type vehicle collision detection device that detects a collision using a tube member that is smaller and more easily mounted than the above-described chamber-type vehicle collision detection device has been proposed. This vehicle collision detection device includes a bumper absorber disposed on the front side of a bumper reinforcement in a vehicle bumper, and a hollow tube mounted in a groove formed in the bumper absorber along the vehicle width direction. A member and a pressure sensor for detecting a pressure in the tube member. When a pedestrian or the like collides with the front of the vehicle, the bumper absorber is deformed while absorbing the impact, and at the same time, the tube member is also deformed. At this time, the pressure in the tube member rises, and the collision with the pedestrian of the vehicle is detected based on detecting this pressure change by the pressure sensor.

Special table 2014-505629

In the above-described vehicle collision detection device, the deformation amount of the collision portion of the tube member (the portion that deforms with the deformation of the bumper cover at the time of collision) is affected by the temperature characteristics of the bumper absorber. The bumper absorber has a temperature characteristic that a deformation amount is small at a low temperature and a deformation amount is large at a high temperature. For this reason, the amount of deformation of the tube member at the time of collision is small at a low temperature and large at a high temperature. As described above, since the amount of deformation of the tube member with respect to a predetermined load varies with the temperature change, it is assumed that the output of the pressure sensor varies with the temperature change. Therefore, in order to improve the collision detection accuracy, there is a problem that it is necessary to suppress variations in the output of the pressure sensor with a temperature change.

This disclosure is intended to provide a vehicle collision detection device capable of detecting a collision of a pedestrian or the like with high accuracy regardless of a temperature change.

In one aspect of the present disclosure, a collision detection device for a vehicle includes a bumper absorber disposed in a vehicle front side of a bumper reinforcement in a bumper of the vehicle, and a groove formed in the bumper absorber along the vehicle width direction. And a pressure sensor for detecting the pressure in the hollow portion of the detection tube member, and an object to the bumper based on the pressure detection result by the pressure sensor. Detect collisions. When the tube member for detection is installed in the groove of the bumper absorber, the load-pressure change characteristic, which is the relationship between the load applied at the time of collision and the pressure change in the hollow part, is the load-displacement characteristic of the bumper absorber. It has a temperature characteristic that cancels out the temperature characteristic, and is configured such that the pressure detection value detected by the pressure sensor is equal to or greater than a predetermined reference value required to determine the collision of the object.

According to this configuration, since the load-pressure change characteristic of the tube member for detection has a temperature characteristic that cancels the temperature characteristic of the load-displacement characteristic of the bumper absorber in a state where it is mounted in the groove portion of the bumper absorber. , It is possible to suppress the output of the pressure sensor from varying with the temperature change. Thereby, the fall of the collision detection precision accompanying a temperature change can be suppressed, and collisions, such as a pedestrian, can be detected with high precision irrespective of a temperature change. Further, since the detection tube member is configured such that the pressure detection value detected by the pressure sensor is equal to or greater than a predetermined reference value required to determine the collision of the object, the vehicle collides with the object. It is possible to reliably prevent the vehicle collision detection device from erroneously detecting an object collision based on the pressure detection value detected by the pressure sensor due to the influence of various noises that occur in a non-use environment.

1 is a diagram illustrating an overall configuration of a vehicle collision detection device according to an embodiment. 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 sectional drawing which shows the internal structure of a pressure sensor. It is an expanded sectional view of the groove part of the bumper absorber of FIG. It is a figure which shows the temperature characteristic of the load-displacement characteristic of a bumper absorber. It is a figure which shows the temperature characteristic of the load-pressure change characteristic in the state which mounted | wore the groove part of the bumper absorber with the detection tube member. It is a figure which shows the hardness of the tube member for a detection, and the minimum output value of a pressure sensor.

A vehicle collision detection apparatus according to an embodiment will be described with reference to FIGS. As shown in FIGS. 1 to 3, the vehicle collision detection device 1 of this embodiment includes a bumper absorber 2, a hollow detection tube member 3, a pressure sensor 4, a speed sensor 5, a collision detection ECU 6, and the like. The vehicle collision detection device 1 detects a collision of an object (such as a pedestrian) with a bumper 7 provided in front of the vehicle. As shown in FIG. 3, the bumper 7 is mainly composed of a bumper cover 8, a bumper absorber 2, and a bumper reinforcement 9.

The bumper absorber 2 is a member having an impact absorbing function in the bumper 7, and is made of, for example, foamed polypropylene. In the present embodiment, a foamed polypropylene having a foaming ratio set to 20 times is used as the material of the bumper absorber 2. The bumper absorber 2 is disposed at a position facing the front surface 9a of the bumper reinforcement 9 (the vehicle front side).

On the rear surface 2b of the bumper absorber 2, a groove 2a for mounting the detection tube member 3 is formed extending in the vehicle width direction (the vehicle left-right direction) (see FIG. 3). The groove 2a has a rectangular cross section and is formed along the vehicle width direction. In addition, the cross-sectional shape of the groove part 2a is not restricted to a rectangle, It can change suitably.

As shown in FIG. 5, the length Lh in the vehicle vertical direction of the groove 2a is set to be longer than the length (outer diameter D) of the detection tube member 3 in the vehicle vertical direction. In this case, the length Lh is about 10 mm. Further, the length Lw of the groove 2a in the vehicle front-rear direction is set to the same length as the length of the outer diameter D of the detection tube member 3.

As shown in FIGS. 1 and 2, the detection tube member 3 is a tubular member having a hollow portion 3a formed therein and extending in the vehicle width direction. The tube member 3 for detection is mounted in the groove 2a of the bumper absorber 2 described above, and is disposed in a position facing the front surface 9a of the bumper reinforcement 9 (vehicle front side) in the bumper 7 of the vehicle. Both ends of the detection tube member 3 are curved in a substantially U shape and connected to a pressure sensor 4 to be described later on the left and right outer sides of the bumper reinforcement 9 in the vehicle width direction.

The detection tube member 3 has a circular cross-sectional shape and is made of synthetic rubber, for example, silicone rubber. In the present embodiment, a silicone rubber having a rubber hardness of 40 to 60 according to a JIS standard K6253 type A durometer is used as the material of the tube member 3 for detection. The silicone rubber preferably has a rubber hardness of 40 to 60, more preferably a rubber hardness of 60.

The outer diameter of the detection tube member 3 is 7 to 10 mm. The wall thickness of the detection tube member 3 is 1 to 3 mm. In the example shown in FIG. 5, the outer shape of the detection tube member 3 is an outer diameter D = 8 [mm] and a wall thickness t = 2 [mm].

The pressure sensor 4 is disposed on the vehicle rear side with respect to the front surface 9a of the bumper reinforcement 9. Specifically, two pressure sensors 4 are installed on the rear surface 9b of the left and right ends of the bumper reinforcement 9, and are fixedly attached by fastening bolts (not shown). In this embodiment, redundancy and detection accuracy are ensured by installing two pressure sensors 4 in this way.

2 and 4, the pressure sensor 4 is connected to both left and right ends of the detection tube member 3, and is configured to detect the pressure in the hollow portion 3a of the detection tube member 3. Specifically, the pressure sensor 4 is a sensor device that detects a change in the pressure of the gas, and detects a change in the pressure of the air in the hollow portion 3 a of the detection tube member 3. As shown in FIG. 1, the pressure sensor 4 is electrically connected to a collision detection ECU (Electronic Control Unit) 6 via a transmission line, and outputs a signal proportional to the pressure to the collision detection ECU 6. The collision detection ECU 6 detects a pedestrian collision with the bumper 7 based on the pressure detection result by the pressure sensor 4. Further, the collision detection ECU 6 is electrically connected to the pedestrian protection device 10.

As shown in FIG. 4, the pressure sensor 4 includes a main body portion 40, a sensor portion 41, a pressure introduction pipe 42, and a connector portion 43. The main body 40 is a box-shaped case for housing the sensor unit 41. The sensor unit 41 is made of a substrate or the like provided with a sensor element for pressure detection. The pressure introduction tube 42 is a substantially cylindrical tube for introducing the pressure in the detection tube member 3 into the sensor unit 41, and is inserted into the hollow portion 3 a of the detection tube member 3 from the main body unit 40. . The sensor unit 41 detects a pressure change in the hollow portion 3 a of the detection tube member 3 through the pressure introduction tube 42. The sensor unit 41 is electrically connected to a connector 44 provided in the connector unit 43, and transmits a signal proportional to the pressure to the collision detection ECU 6 via the connector 44 and the signal line (see FIG. 1).

In the vehicle collision detection apparatus 1 of the present embodiment, the pressure detection value detected by the pressure sensor 4 when colliding with an object is designed to be equal to or greater than a reference value for determining whether or not the object is in collision. . Here, the “reference value” of the pressure sensor 4 is a noise generated in a use environment in which the vehicle does not collide with an object, such as vibration noise generated as the vehicle travels, or electrical noise of the pressure sensor 4. It is a threshold value for distinguishing between a pressure detection value detected by the pressure sensor 4 due to influence and a pressure detection value at the time of collision of an object. Therefore, the “reference value” is set to a value larger than the pressure detection value detected by the pressure sensor 4 due to the influence of noise generated in a use environment where the vehicle does not collide with an object. This prevents the vehicular collision detection device 1 from erroneously detecting a collision with an object based on the output of the pressure sensor 4 when the vehicle is traveling.

The speed sensor 5 is a sensor device that detects the speed of the vehicle, and is electrically connected to the collision detection ECU 6 via a signal line. The speed sensor 5 transmits a signal proportional to the vehicle speed to the collision detection ECU 6.

The collision detection ECU 6 is composed mainly of a CPU and controls the overall operation of the vehicle collision detection apparatus 1 and is electrically connected to the pressure sensor 4 and the pedestrian protection apparatus 10 (FIG. 1). reference). A pressure signal (pressure data) from the pressure sensor 4 is input to the collision detection ECU 6. The collision detection ECU 6 executes a predetermined collision determination process based on the pressure detection result (input signal) by the pressure sensor 4 and detects a collision of an object such as a pedestrian with the bumper 7, and the pedestrian protection device 10. Is activated.

The bumper 7 is for reducing an impact at the time of a vehicle collision, and includes a bumper cover 8, a bumper absorber 2, a bumper reinforcement 9, and the like. The bumper cover 8 is provided so as to cover the components of the bumper 7 and is a resin member such as polypropylene. The bumper cover 8 constitutes the appearance of the bumper 7 and at the same time constitutes a part of the appearance of the entire vehicle.

The bumper reinforcement 9 is a rigid member made of metal such as aluminum which is disposed in the bumper cover 8 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, there are many cases where the vehicle collides with a pedestrian or a vehicle existing in the traveling direction of the vehicle (front of the vehicle). For this reason, in this embodiment, the pressure sensor 4 is disposed on the rear surface 9b of the bumper reinforcement 9, and an impact (external force) associated with a collision with a pedestrian or vehicle in front of the vehicle is provided in front of the vehicle. The bumper reinforcement 9 protects the direct transmission from the bumper cover 8 or the like to the pressure sensor 4.

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

Next, the operation at the time of collision of the vehicle collision detection apparatus 1 in the present embodiment will be described. When an object such as a pedestrian collides with the front of the vehicle, the bumper cover 8 of the bumper 7 is deformed by an impact caused by the collision with the pedestrian. Subsequently, the bumper absorber 2 is deformed while absorbing the impact, and at the same time, the detection tube member 3 is also deformed. At this time, the pressure in the hollow portion 3 a of the detection tube member 3 rises rapidly, and this pressure change is transmitted to the pressure sensor 4. There is a predetermined relationship (load-pressure change characteristic) between the load applied at the time of collision and the pressure change in the hollow portion 3a.

Here, the deformation amount of the detection tube member 3 is affected by the characteristics of the bumper absorber 2. As shown in FIG. 6, the load-displacement characteristic of the bumper absorber 2 alone has a temperature characteristic that the deformation amount is small at a low temperature and large at a high temperature with respect to a predetermined load. Accordingly, the deformation amount of the detection tube member 3 is small at low temperatures and large at high temperatures. For this reason, it is assumed that the output of the pressure sensor 4 varies as the temperature changes.

Therefore, in this embodiment, by appropriately setting the material of the bumper absorber 2 and the material / outer shape of the detection tube member 3, it is possible to suppress a decrease in collision detection accuracy due to a temperature change. That is, as described above, foamed polypropylene having a foaming ratio of 20 times is used as the material of the bumper absorber 2, and silicone rubber is used as the material of the detection tube member 3. Moreover, the outer shape of the tube member for detection 3 was circular in cross section, and was set to an outer diameter of 8 mm and a wall thickness of 2 mm.

Further, the silicone rubber having a rubber hardness of 40 to 70 according to JIS K6253 type A durometer is used. This silicone rubber has little change in hardness (rigidity) due to temperature change. On the other hand, the bumper absorber 2 becomes less rigid as the temperature increases. For this reason, as the temperature increases, the difference in rigidity between the bumper absorber 2 and the detection tube member 3 increases, and the relative hardness of the detection tube member 3 with respect to the bumper absorber 2 increases. Thereby, it can suppress that the output of the pressure sensor 4 varies when the deformation amount of the tube member 3 for detection changes with temperature changes.

That is, as shown in FIG. 7, the change rate (inclination) of the pressure detection value of the pressure sensor 4 can be reduced from a low temperature to a high temperature. In addition, a result was obtained in which the rate of change (inclination) of the output of the pressure sensor 4 accompanying the temperature change decreases as the rubber hardness increases. That is, it is possible to satisfactorily suppress a decrease in collision detection accuracy by reducing variations in the output of the pressure sensor 4 caused by a temperature change.

On the other hand, the pressure detection value detected by the pressure sensor 4 needs to be equal to or greater than the “reference value” described above. As shown in FIG. 8, a test result was obtained in which the minimum output value of the pressure sensor 4 was smaller when the hardness of the tube member for detection 3 was higher than when the hardness was small. The “minimum output value” of the pressure sensor 4 is the minimum value of the detected value of the pressure sensor 4 that is expected when various conditions such as temperature are assumed. When the hardness is 40 to 60, the minimum output value of the pressure sensor 4 is larger than the “reference value”. On the other hand, in the case of hardness 70, the minimum output value of the pressure sensor 4 was less than the “reference value”.

From the results described above, the material of the tube member 3 for detection is optimal when the rubber hardness of the silicone rubber is 60, and the rubber hardness is preferably 40-60. In the present embodiment, the material of the detection tube member 3 satisfies the above conditions, so that the load-pressure change characteristic of the detection tube member 3 is the temperature characteristic of the load-displacement characteristic of the bumper absorber 2. Can offset well. Here, “cancellation” is not limited to completely canceling out the temperature characteristic of the load-displacement characteristic of the bumper absorber 2 100%. The “offset” includes a case where an offset effect of less than 100%, for example, about 80% is obtained. Thereby, it is possible to satisfactorily suppress the output of the pressure sensor 4 from varying with a temperature change, and to effectively suppress a decrease in the collision detection accuracy of the vehicle collision detection device 1 due to the temperature change. In addition, as a material of the tube member 3 for a detection, if the same effect can be acquired elsewhere, it can change suitably.

Furthermore, in this embodiment, the degree of canceling effect brought about by the temperature characteristic of the load-pressure change characteristic of the detection tube member 3 described above is higher in the temperature range from the normal temperature to the high temperature than in the temperature range from the low temperature to the normal temperature. As a result, it was obtained. In particular, when the rubber hardness of the silicone rubber is 60, the output of the pressure sensor 4 with respect to a predetermined load can be made constant (does not change) in the temperature range from room temperature to high temperature.

In the present embodiment, the length Lh in the vehicle vertical direction of the groove portion 2a of the bumper absorber 2 is longer than the length (outer diameter D) of the detection tube member 3 in the vehicle vertical direction. A gap is formed on the upper and rear sides of the detection tube member 3 in the vehicle. Thereby, the space for the tube member 3 for a detection to deform | transform to an up-down direction at the time of a collision is ensured.

Subsequently, the collision detection ECU 6 of the vehicle collision detection device 1 executes a predetermined collision determination process based on the detection results of the pressure sensor 4 and the speed sensor 5. In this collision determination process, the effective mass of the collision object is calculated from the detection results of the pressure sensor 4 and the speed sensor 5, and when this effective mass is larger than a predetermined threshold, it is determined that a collision with a pedestrian has occurred. . Furthermore, when the vehicle speed is within a predetermined range (for example, a range of 25 km to 55 km / h), it is determined that a collision with a pedestrian that requires operation of the pedestrian protection device 10 has occurred.

Here, the “effective mass” refers to a mass calculated using the relationship between momentum and impulse from the detection value of the pressure sensor 4 at the time of collision. When a collision between a vehicle and an object occurs, the value of the detected pressure sensor 4 is different in a collision object (OFF requirement object) such as a roadside marker having a mass different from that of a pedestrian (ON requirement object). For this reason, by setting a threshold value between the effective mass of the human body and the mass of another assumed collision object, it is possible to classify the types of the collision object. This effective mass is calculated by dividing the constant integral value of the pressure value detected by the pressure sensor 4 at a predetermined time by the vehicle speed detected by the speed sensor 5 as shown in the following equation.

M = (∫P (t) dt) / V (Expression 1)
M is an effective mass, P is a value detected by the pressure sensor 4 at a predetermined time, t is a predetermined time (for example, several ms to several tens of ms), and V is a vehicle speed at the time of collision. As another method for calculating the effective mass, it is possible to calculate using an equation E = 1/2 · MV ² representing the kinetic energy E of the collided object. In this case, the effective mass is calculated by M = 2 · E / V ² .

When the collision detection ECU 6 determines that a collision has occurred with a pedestrian that requires the operation of the pedestrian protection device 10, the collision detection ECU 6 outputs a control signal for operating the pedestrian protection device 10 to operate the pedestrian protection device 10. As described above, the impact on the pedestrian is reduced.

As described above, the vehicle collision detection apparatus 1 according to the first embodiment includes the bumper absorber 2 disposed on the front side of the bumper reinforcement 9 in the bumper 7 of the vehicle, and the bumper absorber 2 on the bumper absorber 2. A detection tube member 3 in which a hollow portion 3a is formed inside a groove portion 2a formed along the width direction, and a pressure sensor 4 for detecting the pressure in the hollow portion 3a of the detection tube member 3 And detecting a collision of an object (pedestrian) with the bumper 7 based on a pressure detection result by the pressure sensor 4. The tube member 3 for detection has a load-pressure change characteristic that is a relationship between a load applied at the time of a collision and a pressure change in the hollow portion 3a when the bumper absorber 2 is attached to the groove 2a of the bumper absorber 2. A temperature characteristic that cancels the temperature characteristic of the load-displacement characteristic, and the pressure detection value detected by the pressure sensor 4 is greater than or equal to a predetermined reference value required to determine the collision of an object (pedestrian) It is comprised so that it may become.

According to this configuration, the load-pressure change characteristic of the tube member 3 for detection has a temperature characteristic that cancels the temperature characteristic of the load-displacement characteristic of the bumper absorber 2 in a state where it is mounted in the groove 2a of the bumper absorber 2. Therefore, it is possible to suppress the output of the pressure sensor 4 from varying as the temperature changes. Thereby, the fall of the collision detection precision accompanying a temperature change can be suppressed, and collisions, such as a pedestrian, can be detected with high precision irrespective of a temperature change. Further, since the detection tube member 3 is configured such that the pressure detection value detected by the pressure sensor 4 is equal to or greater than a predetermined reference value required to determine the collision of the object, the vehicle Based on the pressure detection value detected by the pressure sensor 4 under the influence of various noises that occur in a use environment that does not collide with the vehicle, the vehicle collision detection device 1 can be reliably prevented from erroneously detecting an object collision. .

Further, the detection tube member 3 has a temperature characteristic that the difference in rigidity from the bumper absorber 2 increases as the temperature increases. According to this configuration, since the detection tube member 3 has a temperature characteristic in which the difference in rigidity from the bumper absorber 2 increases as the temperature increases, the bumper absorber 2 whose deformation amount varies with a temperature change. The temperature characteristics of the load-displacement characteristics can be offset well by the temperature characteristics of the detection tube member 3 whose relative rigidity increases as the temperature increases. Thereby, the fall of the collision detection precision accompanying a temperature change can be suppressed reliably.

Further, the temperature characteristic of the load-pressure change characteristic of the tube member 3 for detection is more in the temperature range from the normal temperature to the high temperature than the low temperature to the normal temperature, and the temperature characteristic of the load-displacement characteristic of the bumper absorber 2 is offset. The degree to do becomes large.

According to this configuration, the load-displacement characteristic of the bumper absorber 2 is higher when the temperature characteristic of the load-pressure change characteristic of the tube member 3 for detection is in the temperature range from normal temperature to high temperature than from low temperature to normal temperature. Since the degree of canceling the temperature characteristic is increased (see FIG. 7), when the ambient temperature around the vehicle rises from the normal temperature to the high temperature, the above-described canceling effect can be sufficiently exerted, and the high temperature regardless of the temperature change. Collision detection can be performed with high accuracy.

Also, the “reference value” is set to a value larger than the pressure detection value detected by the pressure sensor 4 due to the influence of noise generated in a use environment where the vehicle does not collide with an object. According to this configuration, the pressure detection value of the pressure sensor 4 due to the deformation of the detection tube member 3 at the time of a collision of a pedestrian or the like is a pressure sensor due to the influence of noise generated in a use environment where the vehicle does not collide with an object 4 is set to be equal to or greater than the “reference value” that is a value larger than the pressure detection value detected by No. 4 (see FIG. 8), and therefore the influence of noise generated in a use environment in which the vehicle does not collide with an object. The output of the pressure sensor 4 can be reliably distinguished from the output of the pressure sensor 4 when a pedestrian or the like collides.

The detection tube member 3 is made of silicone rubber having a rubber hardness of 40 to 60 according to a JIS standard K6253 type A durometer. According to this configuration, the load-pressure change characteristic of the detection tube member 3 can satisfactorily satisfy the desired temperature characteristic described above. That is, the temperature characteristic of the load-displacement characteristic of the bumper absorber 2 can be offset well by the temperature characteristic of the load-pressure change characteristic of the detection tube member 3.

The bumper absorber 2 is made of foamed polypropylene, and the foamed polypropylene has a foaming ratio of 20 times. According to this structure, the temperature characteristic which combined the bumper absorber 2 and the detection tube member 3 can fully exhibit the said cancellation effect.

The detection tube member 3 has a circular cross-sectional shape, an outer diameter of 8 mm, and a wall thickness of 2 mm. According to this configuration, the above-described canceling effect can be satisfactorily obtained, and the detection tube member 3 can be easily bent. Therefore, the end of the detection tube member 3 is adapted to correspond to the position where the pressure sensor 4 is disposed. It can be easily connected to the pressure sensor 4 by bending the portion.

Further, the groove 2 a is provided on the rear surface 2 b of the bumper absorber 2. According to this configuration, the detection tube member 3 can be stably disposed on the vehicle front side of the bumper reinforcement 9 and the detection tube member 3 can be easily assembled to the bumper absorber 2.

In the present embodiment, by arranging two pressure sensors 4 on the left and right end portions of the rear surface 9b of the bumper reinforcement 9, it is possible to detect a pressure change in the detection tube member 3 with high accuracy and to provide redundancy. Can be secured. That is, by performing collision determination using the outputs of the two pressure sensors 4, it is possible to prevent erroneous detection and perform accurate collision detection.

The present disclosure is not limited to the above-described embodiment, and various modifications or extensions can be made without departing from the gist of the present disclosure. For example, in the above embodiment, the detection tube member 3 has a circular cross-sectional shape, but is not limited thereto. If the detection tube member 3 has a temperature characteristic that can offset the temperature characteristic of the load-displacement characteristic of the bumper absorber 2, the cross-sectional shape thereof may be changed as appropriate.

Moreover, in the said embodiment, although it determines with the collision with the pedestrian who requires the action | operation of the pedestrian protection apparatus 10 having arisen when the effective mass becomes more than a predetermined threshold value in a collision determination process, it is restricted to this. Absent. For example, a pressure value detected by the pressure sensor 4, a pressure change rate, or the like may be used as a threshold for collision determination.

In addition, although two pressure sensors 4 are disposed on the left and right ends of the rear surface 9b of the bumper reinforcement 9, the present invention is not limited to this, and the position and number of the pressure sensors 4 can be changed as appropriate. For example, the pressure sensor 4 may be fixed to the inner wall surface of the bumper reinforcement 9.

Claims (11)

1. A bumper absorber (2) disposed on the front side of the bumper reinforcement (9) in the bumper (7) of the vehicle;
   A tube member for detection (3) having a hollow portion (3a) formed in a groove (2a) formed in the bumper absorber along the vehicle width direction;
   In a vehicle collision detection apparatus, comprising: a pressure sensor (4) for detecting a pressure in the hollow portion of the detection tube member; and detecting a collision of an object with the bumper based on a pressure detection result by the pressure sensor. ,
   The detection tube member has a load-pressure change characteristic, which is a relationship between a load applied at the time of a collision and a pressure change in the hollow portion when the bumper absorber is mounted in the groove portion of the bumper absorber. It has a temperature characteristic that cancels the temperature characteristic of the load-displacement characteristic, and is configured such that the pressure detection value detected by the pressure sensor is greater than or equal to a predetermined reference value required to determine the collision of the object Vehicle collision detection device.
2. 2. The vehicle collision detection device according to claim 1, wherein the detection tube member has a temperature characteristic in which a difference in rigidity from the bumper absorber increases as the temperature increases.
3. When the temperature characteristic of the load-pressure change characteristic of the detection tube member is in the temperature range from normal temperature to high temperature rather than from low temperature to normal temperature, the temperature characteristic of the load-displacement characteristic of the bumper absorber is offset. The collision detection device for a vehicle according to claim 1 or 2, wherein a degree of the increase is increased.
4. 4. The reference value according to claim 1, wherein the reference value is set to a value larger than a pressure detection value detected by the pressure sensor due to an influence of noise generated in a use environment where the vehicle does not collide with an object. The vehicle collision detection device according to one item.
5. The vehicle collision detection device according to any one of claims 1 to 4, wherein the detection tube member is made of silicone rubber.
6. The vehicle collision detection device according to claim 5, wherein the silicone rubber has a rubber hardness of 40 to 60 according to a JIS K6253 type A durometer.
7. The vehicular collision detection device according to any one of claims 1 to 6, wherein the bumper absorber is made of foamed polypropylene.
8. The vehicle collision detection device according to claim 7, wherein the expanded polypropylene has an expansion ratio of 20 times.
9. The vehicle collision detection device according to any one of claims 1 to 8, wherein the detection tube member has a circular cross-sectional shape.
10. 10. The vehicle collision detection device according to claim 9, wherein the detection tube member has an outer diameter of 7 to 10 mm and a thickness of 1 to 3 mm.
11. 11. The vehicle collision detection device according to claim 1, wherein the groove is provided on a rear surface (2 b) of the bumper absorber.
    
    

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