JP2006321430A - Collision detection device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To enhance detection accuracy of collision by a collision detection device. <P>SOLUTION: The collision detection device 1 is provided with an optical fiber 3 arranged along an outer surface part of a vehicle; transmission light amount detection means 7, 9 for detecting the transmission light amount of the optical fiber 3; and a collision determination means 11 for determining that an object collides to the outer surface part of the vehicle when the transmission light amount detected by the transmission light amount detection means 7, 9 is a predetermined amount or lower. Further, a circular ring-like member 5 for fastening the optical fiber 3 is circumferentially provided on an outer periphery of the optical fiber 3. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a collision detection device that detects a collision of an object with a vehicle.

2. Description of the Related Art Conventionally, a collision detection sensor that detects a collision based on a change in the amount of light transmitted through an optical fiber disposed in a reinforcing member of a vehicle is known (see, for example, Patent Document 1). The collision detection sensor detects a collision based on a change in the amount of transmitted light when the obstacle collides with the vehicle and the optical fiber is deformed.
Japanese Patent No. 2895667

  However, in the collision detection sensor shown in Patent Document 1, since the deformation resistance of the optical fiber varies depending on the temperature change, the deformation amount of the optical fiber with respect to the same collision load varies, and the transmitted light amount varies. Therefore, the amount of transmitted light at the time of the collision load varies due to the temperature change of the optical fiber, and there is a possibility that the collision detection accuracy by the collision detection device is lowered.

  The present invention is for solving such a problem, and a main object thereof is to improve the accuracy of collision detection by the collision detection device.

  One aspect of the present invention for achieving the above object includes an optical fiber disposed along an outer surface portion of a vehicle, a transmitted light amount detecting means for detecting the transmitted light amount of the optical fiber, and the transmitted light amount detecting means. A collision determination unit that determines that an object has collided with the outer surface of the vehicle when the detected transmitted light amount is equal to or less than a predetermined amount, the collision detection device comprising: The collision detection device is characterized in that an annular member for fastening the optical fiber is provided around.

  Moreover, in this one aspect | mode, the said annular member changes the clamping force with respect to the said optical fiber according to ambient temperature, for example.

  According to this aspect, an annular member for fastening the optical fiber is provided around the outer periphery of the optical fiber.

  Thereby, as the temperature rises, the tightening force by the annular member decreases, and the amount of light transmitted through the optical fiber increases. On the other hand, as the temperature rises, the deformation resistance of the optical fiber decreases, and the decrease in the amount of transmitted light at the time of a collision load increases and tends to decrease. Therefore, the decreasing tendency of the transmitted light amount due to the deformation resistance of the optical fiber is canceled by the increase of the transmitted light amount due to the annular member.

  As the temperature decreases, the tightening force by the annular member increases, and the amount of light transmitted through the optical fiber decreases. On the other hand, as the temperature decreases, the deformation resistance of the optical fiber increases, and the decrease in the amount of transmitted light at the time of collision load becomes smaller and tends to increase. Therefore, the increasing tendency of the transmitted light amount due to the deformation resistance of the optical fiber is canceled by the decrease of the transmitted light amount due to the annular member.

  That is, fluctuations in the amount of light transmitted through the optical fiber due to temperature changes are suppressed by tightening the annular member, and the accuracy of collision detection by the collision detection device can be improved.

  Furthermore, in this aspect, the annular member is preferably a bimetal. Thereby, the tightening force by the annular member can be adjusted with higher accuracy.

  In this one aspect, the transmitted light amount detecting means includes a light projecting portion that makes light incident on one end side of the optical fiber, and transmits the transmitted light that is incident on the light projecting portion and passes through the optical fiber. And a light receiving portion for receiving light on the side.

  According to the present invention, it is possible to improve the accuracy of collision detection by the collision detection device.

  Hereinafter, the best mode for carrying out the present invention will be described with reference to the accompanying drawings. The basic concept of the vehicle collision detection device, the main hardware configuration, the operating principle, the basic control method, and the like are known to those skilled in the art, and thus detailed description thereof is omitted.

  FIG. 1 is a view showing a state where a collision detection apparatus according to an embodiment of the present invention is mounted on a vehicle, and is a view showing an optical fiber cable. FIG. 2 is a schematic diagram showing a system configuration of the collision detection apparatus 1 according to an embodiment of the present invention.

  A collision detection apparatus 1 according to the present embodiment includes an optical fiber cable (optical fiber) 3 disposed along an outer surface portion of a vehicle such as a vehicle front or rear bumper, a vehicle left and right door, or the like.

  For example, the optical fiber cable 3 is formed in a U shape, and is bonded along a bumper reinforcement (bumper reinforcing member) in a state of being molded with a mold rubber or the like. Further, the optical fiber cable 3 is folded in a U shape at one end of the bumper reinforcement. The U-shaped optical fiber cables 3 are arranged in parallel in the vehicle vertical direction, but are shown in parallel in the vehicle longitudinal direction for easy viewing in FIG.

  Such an optical fiber cable 3 is composed of, for example, a core portion made of high refractive index silicon rubber and a clad portion made of low refractive index silicon rubber, and the outer peripheral surface is covered with fluorine-based rubber. The light incident from one end side of the optical fiber cable 3 is transmitted to the other end side of the optical fiber cable 3 while repeating total reflection at the boundary surface between the core portion and the cladding portion.

  One annular member 5 for fastening the optical fiber cable 3 is provided around the outer periphery of the optical fiber cable 3 (FIG. 3A), but the number of the annular members 5 provided may be arbitrary. (FIG. 3C). The annular member 5 is provided around the end of the optical fiber cable 3, but can be attached to any position as long as it does not affect object collision detection.

  The annular member 5 is formed of, for example, one type of metal such as iron, but may be formed of a bimetal obtained by bonding two types of metals having different coefficients of thermal expansion, and may be made of any material such as resin. It may be formed. That is, as will be described later, any material can be applied as long as it is a material that generates an optimum tightening force for the optical fiber cable 3.

  When a bimetal is used as the annular member 5, for example, the thermal expansion coefficient α of the inner metal 5a is set larger than the thermal expansion coefficient β of the outer metal 5b (α> β). In this case, since the inner diameter of the annular member 5 is reduced at low temperatures, the tightening force of the annular member 5 on the optical fiber cable 3 is increased (FIG. 4). On the other hand, since the inner diameter of the annular member 5 increases at high temperatures, the tightening force of the annular member 5 on the optical fiber cable 3 decreases.

  Thus, by using a bimetal for the annular member 5, the change in the tightening force due to the annular member 5 accompanying a temperature change can be made more remarkable, and the adjustment range of the tightening force is expanded. Therefore, the tightening force of the annular member 5 can be adjusted with higher accuracy.

  Note that the shape of the annular member 5 may be a continuous annular shape (FIG. 3B). In consideration of the assembling property when assembled to the optical fiber cable 3, the annular member 5 has a circular shape. A part of the ring may be divided (FIG. 3A).

  When the optical fiber cable 3 is tightened by the annular member 5, the transmitted light leaks at the tightened portion or the like. Thereby, the transmitted light quantity in the optical fiber cable 3 decreases.

  For example, as the temperature increases, the annular member 5 expands and the inner diameter increases. When the inner diameter of the annular member 5 increases, the fastening force to the optical fiber cable 3 decreases. In this case, the transmitted light leaking from the optical fiber cable 3 decreases, and the transmitted light amount in the optical fiber cable 3 increases. On the other hand, as the temperature decreases, the annular member 5 contracts and the inner diameter decreases. When the inner diameter of the annular member 5 decreases, the tightening force to the optical fiber cable 3 increases. In this case, the amount of transmitted light leaking from the optical fiber cable 3 increases, and the amount of transmitted light in the optical fiber cable 3 decreases.

  The tightening force of the annular member 5 to the optical fiber cable 3 as described above is such that the annular member 5 is first assembled to the optical fiber cable 3 and then compressed and deformed by a jig or the like (see FIG. 5) It is adjusted so that a predetermined tightening force is generated at a predetermined temperature.

  Connected to one end of the optical fiber cable 3 is a light projecting unit 7 having a light source 7a such as an incandescent lamp, a laser element, and a light emitting diode (LED), and a light amount adjusting circuit 7b for adjusting the light amount of the light source 7a. Has been. When the light projecting unit 7 receives a predetermined trigger signal, the light projecting unit 7 makes light having a certain wavelength incident on one end side of the optical fiber cable 3.

  For example, the light projecting unit 7 may be configured so that light is continuously incident on one end side of the optical fiber cable 3 until an IG (ignition) switch of the vehicle is turned on and then turned off. . Further, the light projecting unit 7 may be configured so that light is continuously incident on one end of the optical fiber cable 3 when the vehicle engine is driven and the vehicle speed is 0 or more.

  The other end of the optical fiber cable 3 receives light transmitted through the optical fiber cable 3 that is incident from the light projecting unit 7 and generates an electrical signal according to the amount of received light (transmitted light amount). Is connected. The light receiving unit 9 includes a light conversion element 9a such as a photodiode that generates an electrical signal according to the amount of transmitted light, and an amplification circuit 9b that amplifies the electrical signal generated by the light conversion element 9a with a predetermined amplification factor. Yes.

  The light receiving unit 9 and the light projecting unit 7 are connected to an ECU 11 that determines whether or not an object has collided with a bumper or the like based on a change in an electrical signal generated by the light receiving unit 9. When the electrical signal from the light receiving unit 9 becomes a predetermined value or less, the ECU 11 determines that an object has collided with the bumper and outputs a collision signal.

  For example, an airbag system may be connected to the ECU 11. In this case, when the airbag system receives a collision signal output from the ECU 11, the airbag system is configured to operate the inflator and inflate and deploy the airbag. Therefore, if the collision detection accuracy by the collision detection device 1 is improved, vehicle safety by the airbag system is improved.

  The ECU 11 is composed of a microcomputer, and executes various processes according to control and arithmetic programs, and also controls a CPU (Central Processing Unit) for controlling each part of the apparatus 1 and a ROM (Read Only Memory) for storing an execution program for the CPU. ), A readable / writable RAM (Random Access Memory) for storing operation results, a timer, a counter, an input interface, an output interface, and the like.

  By the way, when an object collides with the bumper, the optical fiber cable 3 is compressed and deformed, and the amount of transmitted light transmitted through the optical fiber cable 3 is reduced (FIG. 6). The ECU 11 determines that the object has collided with the bumper and outputs a collision signal when the amount of transmitted light is equal to or less than a predetermined amount.

  Further, the optical fiber cable 3 softens with increasing temperature, and the deformation resistance decreases. For this reason, the amount of deformation of the optical fiber cable 3 at the time of a collision load increases, and the amount of transmitted light transmitted through the optical fiber cable 3 decreases greatly.

  FIG. 7 shows the relationship between the amount of light transmitted through the optical fiber cable 3 and the collision load applied to the optical fiber cable 3 when the temperature of the optical fiber cable 3 is T1, T2, T3 (T1 <T2 <T3) It is a figure which shows an example. In FIG. 7, the vertical axis represents the amount of light transmitted through the optical fiber cable 3, and the horizontal axis represents the collision load applied to the optical fiber cable 3.

  As shown in FIG. 7, when the temperature becomes higher in the order of T1, T2, and T3, the deformation resistance of the optical fiber cable 3 decreases as described above, and the decrease in the amount of transmitted light increases. As a result, in the conventional collision detection device, although the load applied to the optical fiber cable is the same, the amount of light transmitted through the optical fiber cable varies depending on the temperature, and the accuracy of collision detection may be reduced.

  Therefore, in the collision detection apparatus 1 according to the present invention, the annular member 5 is provided around the outer periphery of the optical fiber cable 3 in order to suppress the fluctuation of the transmitted light amount of the optical fiber cable 3 due to the temperature change as described above. Has been.

  As a result, as the temperature rises, the deformation resistance of the optical fiber cable 3 decreases, and the decrease in the amount of transmitted light at the time of a collision load increases and tends to decrease. On the other hand, when the temperature rises, the tightening force of the annular member 5 decreases and the amount of transmitted light increases. Therefore, the decreasing tendency of the transmitted light amount due to the deformation resistance of the optical fiber cable 3 is canceled by the increase of the transmitted light amount due to the tightening force of the annular member 5.

  Further, as the temperature decreases, the deformation resistance of the optical fiber cable 3 increases, and the decrease in the amount of transmitted light at the time of a collision load becomes smaller and tends to increase. On the other hand, as the temperature decreases, the tightening force of the annular member 5 increases and the amount of transmitted light decreases. Therefore, the increasing tendency of the transmitted light amount due to the deformation resistance of the optical fiber cable 3 is canceled by the decrease of the transmitted light amount due to the tightening force of the annular member 5. That is, fluctuations in the amount of light transmitted through the optical fiber cable 3 due to temperature changes are suppressed, and the accuracy of collision detection by the collision detection device 1 can be improved.

  As shown in FIG. 7, for example, the transmitted light amount variation curve (1) (solid line) at the reference temperature T1 is brought close to the transmitted light amount variation curve (3) (solid line) at the temperature T3, and the transmitted light amount variation curve (1) ′ ( The initial tightening force of the annular member 5 is adjusted so as to be a dotted line. In this case, the transmitted light amount variation curve (2) (solid line) at the temperature T2 also approaches the transmitted light amount variation curve (3) (solid line) at the temperature T3.

  Also, in the transmitted light amount fluctuation curve, in the collision load region A where an actual collision occurs, variation in the transmitted light amount of the optical fiber cable 3 due to temperature change is suppressed, so that the accuracy of collision detection by the collision detection device 1 is efficiently improved. Can be improved.

  Further, an air inlet for cooling the radiator of the engine is disposed in the vicinity of the substantially central portion of the optical fiber cable 3, so that the temperature at the substantially central portion of the optical fiber cable 3 is at the left and right end portions. Lower than temperature. Therefore, the tightening force of the annular member 5 is set according to the temperature environment of the mounting position.

  The tightening force of the annular member 5 on the optical fiber cable 3 includes the coefficient of thermal expansion of the material forming the annular member 5, the shape (inner diameter, thickness, etc.) of the annular member 5, It is adjusted by changing the number, the initial tightening force by the jig, and the like.

  As described above, the annular member 5 for fastening the optical fiber cable 3 is provided around the outer periphery of the optical fiber cable 3. Thereby, as the temperature rises, the tightening force by the annular member 5 decreases, and the amount of transmitted light in the optical fiber cable 3 increases. On the other hand, as the temperature rises, the deformation resistance of the optical fiber cable 3 decreases, and the decrease in the amount of transmitted light at the time of a collision load increases and tends to decrease. Therefore, the decreasing tendency of the transmitted light amount due to the deformation resistance of the optical fiber cable 3 is canceled by the increase of the transmitted light amount by the annular member 5.

  Further, as the temperature decreases, the tightening force by the annular member 5 increases, and the amount of transmitted light in the optical fiber cable 3 decreases. On the other hand, as the temperature decreases, the deformation resistance of the optical fiber cable 3 increases, and the decrease in the amount of transmitted light at the time of collision load becomes smaller and tends to increase. Therefore, the increasing tendency of the transmitted light amount due to the deformation resistance of the optical fiber cable 3 is canceled by the decrease of the transmitted light amount due to the annular member 5.

  That is, fluctuations in the amount of light transmitted through the optical fiber cable 3 due to temperature changes are suppressed by tightening the annular member 5, and the accuracy of collision detection by the collision detection device 1 can be improved.

  The best mode for carrying out the present invention has been described above with reference to one embodiment. However, the present invention is not limited to the embodiment, and the above-described embodiments are within the scope of the present invention. Various modifications and substitutions can be made to the embodiment.

  For example, in the above embodiment, the ECU 11 may detect the temperature in the vicinity of the optical fiber cable 3 based on the amount of transmitted light received by the light receiving unit 9.

  As described above, the annular member 5 changes the tightening force applied to the optical fiber cable 3 according to the temperature, and changes the amount of light transmitted through the optical fiber cable 3. Therefore, a predetermined relationship (FIG. 8) between the transmitted light amount received by the light receiving unit 9 and the temperature is experimentally obtained in advance, and this predetermined relationship is stored in the ROM of the ECU 11. The ECU 11 detects the temperature in the vicinity of the optical fiber cable 3 based on the amount of transmitted light received by the light receiving unit 9 and a predetermined relationship stored in the ROM. In addition, in FIG. 8, the predetermined relationship when the annular member 5 is formed of bimetal is illustrated.

  The present invention can be used for a collision detection device for a vehicle. The appearance, weight, size, running performance, etc. of the vehicle to be mounted are not limited.

It is a figure which shows the state with which the collision detection apparatus which concerns on one Example of this invention was mounted in the vehicle, and is a figure which shows an optical fiber cable. It is the schematic which shows the system configuration | structure of the collision detection apparatus which concerns on one Example of this invention. (A) It is the elements on larger scale which show the state by which the annular member was provided in the outer periphery of the optical fiber cable, and is a figure which shows the annular member by which a part of annular shape was parted. (B) It is the elements on larger scale which show the state by which the annular member was provided in the outer periphery of the optical fiber cable, and is a figure which shows the annular member in which the annular ring was formed continuously. (C) It is a figure which shows the state by which three annular members were provided in the outer periphery of the optical fiber cable. It is a figure which shows the annular member comprised with the bimetal, and is a figure which shows the state change of the annular member accompanying a temperature change. It is a figure which shows the state which fastens an annular | circular shaped member with a jig | tool. It is a figure which shows the state in which the transmitted light amount in an optical fiber cable when an object collides with a bumper reduces. It is a figure which shows an example of the relationship between the transmitted light amount of an optical fiber cable, and the collision load applied to an optical fiber cable when the temperature of an optical fiber cable is T1, T2, T3. It is a figure which shows an example of the predetermined relationship of the transmitted light amount of an optical fiber cable, and temperature.

Explanation of symbols

1 Collision detection device 3 Optical fiber cable (optical fiber)
5 Toroidal member 7 Projection part (Transmission light quantity detection means)
9 Light-receiving part
11 ECU (collision judging means)

Claims (4)

An optical fiber disposed along the outer surface of the vehicle;
Transmitted light amount detecting means for detecting the transmitted light amount of the optical fiber;
A collision determination device comprising: a collision determination unit that determines that an object has collided with an outer surface portion of the vehicle when the transmitted light amount detected by the transmitted light amount detection unit is a predetermined amount or less;
A collision detection device characterized in that an annular member for fastening the optical fiber is provided around the outer periphery of the optical fiber. The collision detection device according to claim 1,
The collision detection device according to claim 1, wherein the annular member changes a tightening force with respect to the optical fiber according to an ambient temperature. The collision detection device according to claim 1 or 2,
The collision detecting device, wherein the annular member is a bimetal. The collision detection device according to any one of claims 1 to 3,
The transmitted light amount detecting means receives a light incident on one end side of the optical fiber and transmitted light that is incident on the light projecting part and passes through the optical fiber on the other end side of the optical fiber. And a light receiving unit.

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