JP4791782B2 - Shock detection optical fiber sensor - Google Patents

Description

  The present invention relates to an impact detection optical fiber sensor for detecting an impact.

  The impact detection sensor is provided in a vehicle such as an automobile, and is for detecting (sensing) an impact at the time of collision with another vehicle or an obstacle.

  As an impact detection sensor, an electric sensor that includes a pressure sensor, an acceleration sensor, or a strain gauge and detects an impact by observing changes in pressure, acceleration, or strain measured by the sensors is generally known. An optical fiber type that includes an optical fiber made of glass (quartz or the like) or plastic and detects an impact by observing a change in the amount of light transmitted through the optical fiber is generally known. This type of optical fiber type impact detection sensor is also described in Patent Document 1.

JP-T-2002-531812

  By the way, among the conventional shock detection sensors described above, the electric type sensor detects the shock and the electric signal detected by the sensor is easily affected by electric noise / electromagnetic noise.・ There was a problem that it was difficult to distinguish from electromagnetic noise. In addition, the electrical signal has a problem that transmission loss is large.

  In order to solve these problems, the present applicants have previously proposed an impact detection optical fiber sensor using an optical fiber that is not easily affected by electrical noise and electromagnetic noise and has a small transmission loss (Japanese Patent Application 2004). -261232).

  As shown in FIG. 7, the impact detection optical fiber sensor 70 includes an optical fiber 71 for detecting impact, a light source (not shown) connected to one end of the optical fiber 71, and the other end of the optical fiber 71. A connected light receiver (not shown) and a load concentrating plate 72 provided along the longitudinal direction of the optical fiber 71 for supporting a load applied to the optical fiber 71 are provided. The optical fiber 71 and the load concentration plate 72 are covered and integrated with a molding material 73, and the optical fiber 71, the load concentration plate 72, and the molding material 73 constitute a sensor unit 74.

  A plurality of protrusions 75 are formed on one surface (the upper side in FIG. 7) of the load concentration plate 72 at predetermined intervals along the longitudinal direction of the optical fiber 71. The heights of the protrusions 75 are all equal, and the optical fiber 71 and the protrusions 75 are in contact with each other.

  When an impact load is applied to the sensor unit 74 due to a collision with another vehicle or an obstacle, the optical fiber 71 is pressed against the projection 75 side of the load concentrating plate 72 to bend or compress. Then, since bending loss and compression loss corresponding to the impact occur in the optical fiber 71, the presence / absence and magnitude of the impact can be detected from the loss amount. The amount of loss of the optical fiber 71 can be measured by observing a change in the amount of transmitted light transmitted through the optical fiber 71.

  However, the impact detection optical fiber sensor 70 shown in FIG. 7 has a problem that the detection sensitivity varies depending on the direction in which the impact is applied. That is, when an impact is applied to the front surface of the sensor portion 74 (upper side in FIG. 7B), the optical fiber 71 is slightly shifted in the lateral direction (width direction) of the load concentration plate 72, and the impact is applied. As compared with the case where the optical fiber 71 is applied straight from the front of the sensor unit 74, the force for pressing the optical fiber 71 against the protrusion 75 side of the load concentration plate 72 is reduced. Therefore, depending on the direction of impact application, bending and compression acting on the optical fiber 71 are insufficient, and a predetermined deformation cannot be obtained, and the impact may be underestimated.

  By the way, when manufacturing the load concentrating plate 72 described above, a steel material having a thickness sufficient to form the protrusion 75 is cut into a mountain shape by wire-cut electric discharge machining or the like. For example, in wire-cut electric discharge machining, when a steel material having a thickness of 5 mm and a length of 200 mm is processed into the load concentration plate 72, it takes about one hour. Moreover, in wire-cut electric discharge machining, there is a restriction that machining on equipment is not possible if the length is a large steel material having a length of 1 m or more.

  Therefore, an object of the present invention is to provide an impact detection optical fiber sensor that can suppress variations in detection sensitivity due to a shift in the direction of impact application.

  Another object of the present invention is to provide an impact detection optical fiber sensor that can shorten the processing time of the load concentration plate.

To achieve the above object, the invention of claim 1 is directed to an optical fiber for detecting an impact, a light source connected to one end of the optical fiber, and a light receiver connected to the other end of the optical fiber. , An impact detection device comprising a load concentration plate provided along the longitudinal direction of the optical fiber for supporting a load applied to the optical fiber, and a mold material covering the optical fiber and the load concentration plate. In the optical fiber sensor, the load concentration plate includes a plate body formed along the longitudinal direction of the optical fiber, a plurality of holes formed at predetermined intervals in the longitudinal direction of the plate body, and a space between the holes. A connecting portion formed on the optical fiber , the connecting portion having a concave portion formed in a substantially concave shape having a bottom portion and two side portions when viewed from the axial direction of the optical fiber , place the fiber molded When, as the molding material is interposed between the optical fiber and the recess portion of the side, which is optical fiber impulse sensor, characterized in that it is formed wider than the diameter of the optical fiber.

  The invention according to claim 2 is the impact detecting optical fiber sensor according to claim 1, wherein the load concentrating plate is formed by pressing the plate body to form the hole, the connecting portion, and the indented portion. .

  According to the present invention, there is an excellent effect that variation in detection sensitivity due to displacement in the direction of impact application can be suppressed.

  DESCRIPTION OF EMBODIMENTS Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

  The impact detection optical fiber sensor of the present embodiment is provided in a vehicle such as an automobile, and is for detecting the presence / absence and magnitude of an impact at the time of collision with another vehicle or an obstacle.

  FIG. 1 is a perspective view of an impact detection optical fiber sensor according to an embodiment of the present invention. 2A is a plan view, FIG. 2B is a sectional view taken along line IIb-IIb in FIG. 2A, and FIG. 2C is a sectional view taken along line IIc- in FIG. It is IIc arrow directional cross-sectional view, (d) is IId-IId arrow directional cross-sectional view of Fig.2 (a). 3 shows a load concentrating plate, (a) is a plan view, (b) is a sectional view taken along line IIIb-IIIb in FIG. 3 (a), and (c) is IIIc in FIG. 3 (a). FIG. 3 is a cross-sectional view taken along line -IIIc, and (d) is a cross-sectional view taken along line IIId-IIId in FIG.

  As shown in FIG. 1, an impact detection optical fiber sensor 1 of this embodiment includes a sensor unit 3 having a plastic optical fiber 2 (hereinafter referred to as POF) for detecting an impact, and a semiconductor laser connected to one end of the POF 2. And a light receiver (not shown) such as a photodiode connected to the other end of the POF 2. In this embodiment, a heat-resistant plastic optical fiber (hereinafter referred to as HPOF) having heat resistance is used as POF2.

  As shown in FIG. 2, the HPOF 2 of the present embodiment includes a core portion 4 having a substantially circular cross section for propagating light, and a clad portion 5 having a substantially circular cross section provided to cover the outer periphery of the core portion 4. It consists of and. The clad part 5 is provided concentrically with the core part 4. As the core part 4, a synthetic resin excellent in heat resistance (for example, an acrylic resin, a cross-linked acrylic resin (thermosetting acrylic resin), or a silicone resin) can be used. As the clad part 5, a synthetic resin (for example, a fluorine-based resin such as an ethylene propylene resin) having a lower refractive index than that of the core part 4 and excellent in heat resistance, water resistance, and mechanical properties is used. it can.

  The sensor unit 3 is provided so as to extend along the longitudinal direction of the HPOF 2 and covers the load concentration plate (load transmission plate) 10 for supporting the load applied to the HPOF 2, and the HPOF 2 and the load concentration plate 10. And a molding material 11 for integrating them. As the load concentration plate 10, a material harder than HPOF 2 such as iron (for example, cold rolled steel plate), hard plastic, brass, or stainless steel can be used. Further, as the molding material 11, a synthetic resin (for example, silicone rubber) that is softer than HPOF2 and has flexibility can be used.

  As shown in FIG. 3, the load concentration plate 10 is provided with a plurality of protrusions 12 that are provided at predetermined intervals along the longitudinal direction of the HPOF 2 and support the impact load applied to the HPOF 2, and abut against the HPOF 2. It is formed.

  The load concentration plate 10 according to the present embodiment includes a plate body 13 provided to extend along the longitudinal direction of the HPOF 2 and a plurality of substantially I-shaped plates formed at predetermined intervals in the longitudinal direction of the plate body 13. It has a hole 14 and a connecting portion 15 formed between the adjacent holes 14. The connecting portion 15 has a recessed portion 16 formed in a substantially concave shape when viewed from the axial direction of the HPOF 2 (see FIG. 3B). Protruding portions 17 extending in the longitudinal direction of the plate body 13 are provided at both ends of the recessed portion 16. These indentations 16 and protrusions 17 constitute the projections 12 described above.

  In the present embodiment, the bottom portion 16a of the recessed portion 16 is formed in a planar shape in a side view so as to hold the HPOF 2 (see FIG. 3D). Further, the protrusion 17 is formed in an R shape in a side view so as to prevent the HPOF 2 from being cut when the HPOF 2 is bent (see FIG. 3D). Further, the indented portion 16 and the protruding portion 17 are formed wider than the diameter of HPOF 2 (that is, the diameter of the cladding portion 5) (see FIG. 2B).

  As shown in FIGS. 1 and 2, HPOF 2 is disposed on the bottom 16 a of the recessed portion 16 of the load concentration plate 10, and the HPOF 2 and the load concentration plate 10 are covered with a molding material 11 and integrated. Thereby, the outer periphery of HPOF2 is covered with the molding material 11, and the molding material 11 is interposed between the HPOF2 and the side portion 16b of the indented portion 16 (see FIG. 2B). Here, the thickness of the load concentrating plate 10 (plate body 13) is preferably formed such that the portion where the HPOF 2 is disposed (that is, the bottom portion 16a of the recessed portion 16) is thinner than the other portions.

  In the present embodiment, press working is used when the load concentration plate 10 is manufactured.

  First, a plurality of substantially I-shaped holes 14 are formed in a flat plate (see reference numeral 20 in FIG. 4A) at predetermined intervals in the longitudinal direction by pressing (punching). Thereby, the connecting portion 15 is formed between the adjacent holes 14, and the protruding portions 17 are formed at both ends of the connecting portion 15. Next, the upper surface of the protrusion 17 is processed into a curved surface by pressing (crushing).

  Thereafter, as shown in FIG. 4A, the flat plate 20 is placed on the concave mold 21 so that the curved surface of the projecting portion 17 is on the upper side, and as shown in FIG. The flat plate 20 is pressed from above with a convex mold 22, and the connecting portion 15 is bent downward to form the indented portion 16. Thereby, the load concentration board 10 shown in FIG. 3 can be obtained.

  In the present embodiment, an extrusion method is used when the load concentration plate 10 is covered with the molding material 11 in order to manufacture the impact detection optical fiber sensor 1.

  In this extrusion method, the load concentration plate 10 is inserted from an insertion port of an extruder (not shown), and the load concentration plate 10 covered with raw rubber (mold material 11) is pushed out to the discharge port side of the extruder. To do. In the present embodiment, when performing the extrusion method, a mandrel (not shown) made of SUS (stainless steel) is disposed on the portion of the load concentration plate 10 where the HPOF 2 is disposed (that is, the indented portion 16), and the load concentration. The plate 10 and the mandrel were inserted from the insertion port side of the extruder and pushed out to the discharge port side.

  If the load concentration board 10 is coat | covered with raw rubber (mold material 11) over the full length, they will be bridge | crosslinked and raw rubber (mold material 11) will be hardened. Then, after the raw rubber (mold material 11) is cured, the mandrel is pulled out from the mold material 11, and HPOF2 is inserted into the mold material 11 instead of the drawn mandrel. When the HPOF 2 is inserted into the mold material 11, compressed air is fed into the hole of the mold material 11 formed by pulling out the mandrel and the hole is enlarged. The compressed air may be fed into the hole of the molding material 11 from the HPOF2 insertion side or from the side opposite to the HPOF2 insertion side.

  When the position of the HPOF 2 inserted into the mold material 11 is determined and the feeding of the compressed air is finished, the hole of the mold material 11 contracts and the HPOF 2 and the mold material 11 are brought into close contact with each other. Thereby, the impact detection optical fiber sensor 1 shown in FIGS. 1 and 2 can be obtained. Note that, when the HPOF 2 is inserted into the hole of the mold material 11, even if a gap is formed between the HPOF 2 and the mold material 11, when the impact detection optical fiber sensor 1 is assembled at a predetermined position, the clamping pressure when the sensor is fixed Thus, the gap between the HPOF 2 and the molding material 11 is eliminated.

  The impact detection optical fiber sensor 1 of the present embodiment can detect an impact from the front of the vehicle by installing the sensor unit 3 in a bumper portion in front of the vehicle. Assembling position of the sensor unit 3 is the bumper surface, the back side of the bumper (that is, between the bumper and the shock absorber (buffer material)), embedding in the shock absorber, or between the shock absorber and the bumper reinforcement, etc. It may be on a route through which a load is transmitted when an impact is applied in the vehicle. Further, when the sensor unit 3 is installed at a position close to the surface of the bumper of the vehicle, if the sensor unit 3 is installed above and below the vehicle, the height of the center of gravity of the collision target can be determined, so that it is more efficient. It is possible to distinguish the collision object well.

  Moreover, what is necessary is just to arrange | position the sensor part 3 to the back and side surface of a vehicle when detecting the impact from the back and side of a vehicle.

  Next, the operation of this embodiment will be described.

  The light output from the light source enters the light receiver through the HPOF2. The transmitted light amount (light intensity) detected by the light receiver is transmitted to the outside of the sensor as an electric signal through a signal line (not shown).

  When an impact load is applied to the sensor unit 3 due to a collision with another vehicle or an obstacle, the HPOF 2 is bent between the projections 12 of the load concentration plate 10 as shown in FIG. 5, or the projection as shown in FIG. 12 is pressed and compressed. Then, bending loss (microbending loss) or compression loss corresponding to the impact occurs in HPOF2, and the amount of transmitted light that propagates through HPOF2 changes according to the bending loss or compression loss. On the other hand, when the time elapses from the impact application, the shape of the HPOF 2 is restored by the elastic force of the molding material 11, so that the impact detection optical fiber sensor 1 can be used repeatedly.

  In the present embodiment, the load concentration plate 10 includes a plate body 13 formed along the longitudinal direction of the HPOF 2, a plurality of holes 14 formed at predetermined intervals in the longitudinal direction of the plate body 13, and the holes 14. A connecting portion 15 formed between them, and the connecting portion 15 has a recessed portion 16 formed in a substantially concave shape when viewed from the axial direction of the HPOF 2, and the HPOF 2 is arranged in the recessed portion 16. . Therefore, when the impact is applied to the front surface of the sensor unit 3 (upper side in FIG. 2B) as shown by the arrow in FIG. 6, the HPOF 2 is on the side 16 b side of the recessed portion 16. Although it is pressed to the side, the elastic force of the molding material 11 interposed between the HPOF 2 and the side part 16b of the indented part 16 is pushed back to the side opposite to the side part 16b of the indented part 16, so Deviation in the horizontal direction (width direction) is reduced. Further, since HPOF2 is deformed by obtaining a reaction force from the side portion 16b of the recessed portion 16 through the molding material 11 interposed between the side portion 16b of the recessed portion 16 and the impact is applied at an inclination. It is also possible to detect the impact of the. Therefore, it is possible to suppress variations in detection sensitivity due to deviation in the direction of impact application.

  Moreover, in this embodiment, since the hole 14, the connection part 15, and the hollow part 16 of the load concentration board 10 were formed by pressing the flat plate 20, these holes 14, the connection part 15, and the hollow part 16 were formed. The processing time of the load concentrating plate 10 can be shortened as compared with the case of forming by wire cut electric discharge machining or the like. For example, when the hole 14 is formed by pressing (punching) the flat plate 20 having a thickness of 1 mm and a length of 200 mm, the processing is completed in about 10 seconds. In press working, even a large flat plate 20 having a length of 1 m or more can be processed relatively easily.

  In this embodiment, since the molding material 11 is interposed between the HPOF 2 and the side portion 16b of the recessed portion 16, the molding material 11 serves as a buffer material, and the HPOF 2 directly contacts the side portion 16b of the recessed portion 16. There is an advantage that the HPOF 2 is less likely to be cut than the contact.

  The present invention is not limited to the embodiment described above.

  For example, the cross-sectional shapes of the core part 4 and the clad part 5 of HPOF 2 are not limited to the above-described embodiment. For example, the core part 4 and the clad part 5 may be formed in other shapes such as a rectangular cross section and an elliptical cross section.

  In the above-described embodiment, a plastic optical fiber is used as the optical fiber 2, but a glass optical fiber can also be used as the optical fiber 2. However, due to the characteristics of glass, the glass optical fiber is likely to be deteriorated in mechanical strength by bending or compression, and the glass optical fiber may be cut when an impact is applied. For this reason, as the optical fiber 2, it is desirable to use a plastic optical fiber that is unlikely to cause a decrease in mechanical strength as in the present embodiment.

  In the above-described embodiment, the hole 14, the connection portion 15, and the recess portion 16 of the load concentration plate 10 are formed by pressing the flat plate 20. However, the hole 14 and the connection portion 15 of the load concentration plate 10 are formed. In addition, the recess 16 may be formed by molding.

  Moreover, if the sensor part 3 of the impact detection optical fiber sensor 1 of the above-mentioned embodiment is installed in the door confinement part of a vehicle, it will become possible to detect opening and closing of a door.

  Furthermore, since the impact detection optical fiber sensor 1 of the above-described embodiment is a load sensor, it is possible to measure the axle weight of the passing vehicle if the sensor unit 3 is embedded in the road. At that time, if the sensor unit 3 is embedded in a bridge pier or the like so that the weight can be measured, the total weight of the vehicle passing through the bridge can be measured, and an analogy such as deterioration of the bridge can be made.

It is a perspective view of an impact detection optical fiber sensor concerning one embodiment of the present invention. The sensor part is shown, (a) is a plan view, (b) is a sectional view taken along line IIb-IIb in FIG. 2 (a), and (c) is taken along line IIc-IIc in FIG. 2 (a). It is a sectional view taken along the line IId-IId in FIG. 2A. The load concentration board is shown, (a) is a plan view, (b) is a sectional view taken along line IIIb-IIIb in FIG. 3 (a), and (c) is a line IIIc-IIIc in FIG. 3 (a). It is arrow sectional drawing, (d) is a IIId-IIId arrow sectional drawing of Fig.3 (a). (A) And (b) is the schematic which shows the manufacturing method of a load concentration board. It is side surface sectional drawing of a sensor part which shows the state by which the optical fiber was bent by the impact application. It is front sectional drawing of a sensor part which shows the state by which the optical fiber was compressed by the impact application. The impact detection optical fiber sensor which the present applicants proposed previously is shown, (a) is side sectional drawing, (b) is a VIIb-VIIb arrow sectional view of Drawing 7 (a), (c ) Is a sectional view taken along line VIIc-VIIc in FIG.

Explanation of symbols

1 Optical fiber sensor for impact detection 2 Optical fiber (POF, HPOF)
DESCRIPTION OF SYMBOLS 10 Load concentration board 11 Mold material 13 Plate body 14 Hole 15 Connection part 16 Recessed part

Claims (2)

An optical fiber for detecting an impact, a light source connected to one end of the optical fiber, a light receiver connected to the other end of the optical fiber, and a light source provided along the longitudinal direction of the optical fiber. In an impact detection optical fiber sensor comprising a load concentration plate for supporting a load applied to a fiber, and a mold material covering the optical fiber and the load concentration plate ,
Upper Symbol load concentration plate is a plate member formed along a longitudinal direction of the optical fiber, a plurality of holes formed at predetermined intervals in the longitudinal direction of the plate body, which is formed between them holes With a connection part ,
The connection portion has a hollow portion formed in a substantially concave shape composed of a bottom portion and two side portions when viewed from the axial direction of the optical fiber ,
The indented portion is formed wider than the diameter of the optical fiber so that the molding material is interposed between the optical fiber and the side portion of the indented portion when the optical fiber is disposed and molded. An impact detection optical fiber sensor characterized by that.   The impact detection optical fiber sensor according to claim 1, wherein the load concentrating plate is formed by pressing the plate body to form the hole, the connecting portion, and the indented portion.

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