JP4783160B2 - Shock detecting optical fiber sensor and manufacturing method thereof - Google Patents

Description

  The present invention relates to an impact detection optical fiber sensor for detecting an impact and a manufacturing method thereof.

  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 (impact detection optical fiber sensor) is also described in Patent Documents 1 and 2, and the like.

  The present applicants are developing an impact detection optical fiber sensor using an optical fiber which is not easily affected by electric noise and electromagnetic noise and has a small transmission loss.

  As shown in FIG. 5, the impact detection optical fiber sensor includes an optical fiber 51 for detecting an impact, a light emitting element (not shown) connected to one end of the optical fiber 51, and the other end of the optical fiber 51. And a load concentrating plate 52 that is arranged along the longitudinal direction of the optical fiber 51 and has a plurality of irregularities. The optical fiber 51 and the load concentrating plate 52 are covered and integrated with a molding material 53, and the optical fiber 51, the load concentrating plate 52, and the molding material 53 constitute a sensor unit 54.

  A plurality of protrusions 55 are formed on one side of the load concentration plate 52 (upper side in FIG. 5) at a predetermined interval along the longitudinal direction of the optical fiber 51. The heights of the protrusions 55 are all equal, and the optical fiber 51 and the protrusions 55 are in contact with each other.

  When an impact load is applied to the sensor unit 54 due to a collision with another vehicle, an obstacle, or the like, the optical fiber 51 is pressed against the protrusion 55 side of the load concentrating plate 52 and bent or compressed. Then, since bending loss and compression loss corresponding to the impact are generated in the optical fiber 51, it is possible to detect the presence / absence and magnitude of the impact from these loss amounts. The amount of loss of the optical fiber 51 can be measured by observing a change in the amount of light transmitted through the optical fiber 51.

  Here, when the load concentrating plate 52 is covered with the molding material 53 in order to manufacture the impact detection optical fiber sensor, an extrusion method is used.

  In this extrusion method, the load concentration plate 52 is inserted from an insertion port of an extruder (not shown), and the load concentration plate 52 covered with raw rubber (mold material 53) is pushed out to the discharge port side of the extruder. To do. When performing the extrusion method, a metal mandrel (not shown) is disposed in a portion of the load concentrating plate 52 where the optical fiber 51 is disposed, and the load concentrating plate 52 and mandrel are inserted from the insertion port side of the extruder. It is inserted and pushed out to the discharge port side.

  When the load concentration plate 52 is covered with raw rubber over the entire length, the raw rubber (mold material 53) is vulcanized (or crosslinked) and cured. Then, after the raw rubber (mold material 53) is cured, the mandrel is pulled out from the mold material 53, and the optical fiber 51 is inserted into the mold material 53 instead of the drawn mandrel, so that the sensor of the impact detection optical fiber sensor shown in FIG. Part 54 can be obtained.

Japanese Examined Patent Publication No. 6-48220 Japanese Patent Laying-Open No. 2005-140752

  By the way, in order to insert the optical fiber 51 into the hole of the molding material 53 formed by pulling out the mandrel, the outer diameter of the mandrel is formed larger than the outer diameter of the optical fiber 51. Accordingly, a gap is formed between the hole and the optical fiber 51. When a load is applied to the sensor unit 54, the optical fiber 51 can be deformed (bent / compressed) until the gap is crushed. There was a problem that a dead zone in which the sensor did not function in a low load region occurred.

  Further, it is possible to prevent a gap from being formed between the optical fiber 51 and the molding material 53 by simultaneously pushing out the optical fiber 51 and the load concentration plate 52. However, it is difficult to bring out the shape of the molding material 53 only by extruding and voids are generated when the raw rubber is vulcanized (or at the time of crosslinking). Therefore, the molding material 53 is molded and vulcanized (or at the time of crosslinking). In order to remove the voids in the molding material 53 generated in the above, high-temperature pressing is performed on the molding material 53 after vulcanization (or crosslinking). During this high temperature pressing, the portion of the optical fiber 51 that is softened at a high temperature is in contact with the load concentrating plate 52, and the initial deformation of the optical fiber 51 increases the transmitted light loss of the optical fiber 51. As a result, there has been a problem that appropriate impact detection cannot be performed.

  Accordingly, an object of the present invention is to eliminate (suppress) the generation of a dead band in a low load region by preventing a gap between the optical fiber and the molding material without giving initial deformation to the optical fiber. It is an object of the present invention to provide an impact detection optical fiber sensor and a method of manufacturing the same.

In order to achieve the above object, an invention according to claim 1 covers an optical fiber, a load concentrating plate having a plurality of projections and depressions arranged along the longitudinal direction of the optical fiber, and covering the optical fiber and the load concentrating plate. In the manufacturing method of an impact detection optical fiber sensor comprising a molding material to be coated, the optical fiber is coated with the molding material by extrusion to form an optical fiber block, and the load concentration plate is coated with the molding material. A method for manufacturing an impact detection optical fiber sensor, comprising: forming a load concentrating plate block and integrating the optical fiber block and the load concentrating plate block by bonding.

  According to a second aspect of the present invention, when the optical fiber block is formed, a portion of the optical fiber that is in contact with the load concentration plate and an end face of the molding material that covers the optical fiber are flush with each other. It is a manufacturing method of the impact detection optical fiber sensor of Claim 1.

  According to a third aspect of the present invention, when the load concentrating plate block is formed, a portion of the load concentrating plate in contact with the optical fiber and an end surface of the mold material covering the load concentrating plate are flush with each other. The method for manufacturing an impact detection optical fiber sensor according to claim 1 or 2.

  According to a fourth aspect of the present invention, there is provided the method for producing an impact detecting optical fiber sensor according to the first aspect, wherein the outer periphery of the optical fiber is completely covered with the molding material when the optical fiber block is formed.

  The invention according to claim 5 is the manufacturing of the impact detecting optical fiber sensor according to claim 1 or 4, wherein the outer surface of the load concentration plate is completely covered with the molding material when the load concentration plate block is formed. Is the method.

  The invention according to claim 6 is the impact detection according to any one of claims 1 to 5, wherein characteristics are changed between the mold material covering the optical fiber and the mold material covering the load concentration plate. It is a manufacturing method of an optical fiber sensor.

According to a seventh aspect of the present invention, there is provided an optical fiber for detecting an impact, a light emitting element connected to one end of the optical fiber, a light receiving element connected to the other end of the optical fiber, and a longitudinal direction of the optical fiber. An impact detection optical fiber sensor comprising a load concentrating plate having a plurality of projections and depressions disposed along the optical fiber and a mold material covering the optical fiber and the load concentrating plate, and the optical fiber is covered with the mold material by extrusion. The optical fiber block is formed, and the load concentration plate is covered with the molding material to form the load concentration plate block, and the optical fiber block and the load concentration plate block are bonded together to be integrated. This is an impact detection optical fiber sensor.

  According to the present invention, it is possible to eliminate the gap between the optical fiber and the molding material without giving initial deformation to the optical fiber, and it is possible to eliminate (suppress) the generation of the dead band in the low load region. Excellent effect.

  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 shows an impact detection optical fiber sensor according to an embodiment of the present invention, in which (a) is a front view, (b) is a cross-sectional view taken along line Ib-Ib in FIG. (C) is a sectional view taken along line Ic-Ic in FIG.

  As shown in FIGS. 1A to 1C, the impact detection optical fiber sensor of the present embodiment is connected to a sensor unit 2 having an optical fiber 1 for detecting an impact and one end of the optical fiber 1. The light emitting device (not shown) such as a semiconductor laser and a light receiving device (not shown) such as a photodiode connected to the other end of the optical fiber 1 are mainly configured.

  As shown in FIGS. 1B and 1C, the optical fiber 1 includes a core portion 3 having a substantially circular cross section for propagating light, and a cross section provided so as to cover the outer periphery of the core portion 3. The clad part 4 has a substantially hollow annular shape. The clad part 4 is provided concentrically with the core part 3.

  As the optical fiber 1, a plastic optical fiber (hereinafter referred to as POF) can be used. In that case, as the core part 3, a synthetic resin (for example, an acrylic resin, a crosslinked acrylic resin (thermosetting acrylic resin), or a silicone resin) having excellent heat resistance can be used. Moreover, as the clad part 4, a synthetic resin (for example, a fluorine-based resin such as a fluoroethylene propylene resin) having a refractive index lower than that of the core part 3 and excellent in heat resistance, water resistance and mechanical properties is used. be able to.

  As shown in FIG. 1A to FIG. 1C, the sensor unit 2 is arranged along the longitudinal direction of the POF 1 and is a load concentration plate (stress concentration plate) for concentrating the load applied to the POF 1. 5, and a molding material 6 that covers the POF 1 and the load concentration plate 5 and integrates them. The load concentrating plate 5 is provided with a plurality of projections 7 provided at predetermined intervals along the longitudinal direction of the POF 1 and abutting against the POF 1.

  As the load concentration plate 5, a material harder than POF 1 such as iron (for example, cold rolled steel plate), hard plastic, brass or stainless steel can be used. Further, as the molding material 6, a synthetic resin (for example, silicone rubber) that is softer than the POF 1 and has flexibility can be used.

  The load concentration plate 5 of the present embodiment includes a plate body 8 provided to extend along the longitudinal direction of the POF 1, a plurality of holes 9 formed at predetermined intervals in the longitudinal direction of the plate body 8, and And a connecting portion 10 formed between the adjacent holes 9. The connecting portion 10 constitutes the projection 7 described above.

  A flat surface portion 10a that is flat in a side view and is in contact with the outer periphery of the POF 1 is formed at the central portion of the connection portion 10 in the longitudinal direction of the POF 1. Further, at both ends of the connecting portion 10 in the longitudinal direction of the POF 1, R portions 10 b having an R shape in side view are formed to prevent the POF 1 from being cut when the POF 1 is bent.

  In the present embodiment, the sensor unit 2 includes an optical fiber block 12 formed by covering POF 1 with a mold material 11a, and a load concentration plate block 13 formed by covering the load concentration plate 5 with a mold material 11b. . The optical fiber block 12 and the load concentrating plate block 13 are bonded and integrated.

  The impact detection optical fiber sensor of this embodiment can detect the impact from the front of a vehicle by installing the sensor part 2 in the bumper part of a vehicle front part.

  When the impact detection optical fiber sensor of the present embodiment detects an impact caused by a collision with a pedestrian, if the hood is raised or the airbag is inflated outside the hood, a secondary collision (impact on the bumper) Can be reduced to a pedestrian. When the hood is raised, the space with the engine or the like in the hood is widened, so that the impact on the pedestrian during the secondary collision can be reduced.

  However, when an impact due to a collision with a utility pole or the like is detected, it is necessary not to raise the bonnet. The collision object can be identified by estimating the magnitude of impact at the time of collision.

  Moreover, it becomes possible to prevent the pedestrian from directly colliding with the vehicle by opening the airbag at the hard part of the vehicle body of the wiper or the pillar part.

  Some have a mechanism that reduces the impact on pedestrians during secondary collisions by making the wiper fixing part (support part) movable. It is possible to operate the wiper fixing part only at a limited time.

  In addition to the above, instead of inflating the airbag to the outside of the hood, inflating the airbag to the lower side of the hood (engine room side) also reduces the impact on pedestrians during secondary collisions. Can do. It is easy to store a mechanism for inflating the airbag on the engine room side of the bonnet.

  Next, the usage method of the impact detection optical fiber sensor of this embodiment is demonstrated.

  The optical signal output from the light emitting element is incident on the light receiving element via POF1. The optical signal (transmitted light amount) detected by the light receiving element is transmitted to the signal processing side outside the sensor.

  When an impact load is applied to the sensor unit 2 due to a collision with another vehicle or an obstacle, the POF 1 is bent between the projections 7 of the load concentration plate 5 or pressed against the projections 7 and compressed. Then, bending loss (microbending loss) and compression loss corresponding to the impact occur in POF1, and the amount of transmitted light that propagates through POF1 changes according to the bending loss or compression loss.

  On the other hand, when time elapses from the impact application, the shape of the POF 1 is restored by the elastic force of the molding material 6 (11a, 11b), so that the impact detection optical fiber sensor can be used repeatedly.

  Next, the manufacturing method of the impact detection optical fiber sensor of this embodiment is demonstrated.

  In this embodiment, the extrusion method is used when the POF 1 or the load concentration plate 5 is covered with the molding material 6 (11a, 11b) in order to manufacture an impact detection optical fiber sensor. In this extrusion method, POF 1 or load concentration plate 5 is inserted from an insertion port of an extruder (not shown), and POF 1 or load concentration plate 5 covered with raw rubber (molding material 6 (11a, 11b)) is extruded. It pushes out to the discharge port side.

  In this embodiment, when the POF 1 or the load concentrating plate 5 is covered with raw rubber (mold material 6 (11a, 11b)), the POF 1 and the load concentrating plate 5 are inserted separately from the insertion port side of the extruder. It pushes out to the discharge port side. That is, in this embodiment, the POF 1 and the load concentrating plate 5 are separately covered with the molding materials 11a and 11b.

  As shown in FIG. 2A, when POF 1 is covered with raw rubber over a predetermined length, the raw rubber (mold material 11a) is vulcanized (or crosslinked) and cured. Thereafter, the molding material 11a is molded and the molding material 11a is hot-pressed to form the optical fiber block 12 in order to remove voids in the molding material 11a generated during vulcanization (or crosslinking).

  Here, in this embodiment, when the optical fiber block 12 is formed, the portion (the lowermost surface in the illustrated example) that contacts the load concentrating plate 5 in the POF 1 and the end surface (lower surface in the illustrated example) of the molding material 11a are surfaces. To be united (located on the same plane).

  On the other hand, as shown in FIG. 2B, when the load concentrating plate 5 is covered with the raw rubber over the entire length, the raw rubber (mold material 11b) is vulcanized (or crosslinked) and cured. Thereafter, the mold material 11b is molded, and the mold material 11b is hot-pressed to form the load concentration plate block 13 in order to remove voids in the mold material 11b generated during vulcanization (or crosslinking).

  Here, in the present embodiment, when the load concentration plate block 13 is formed, the portion of the load concentration plate 5 that contacts the POF 1, that is, the tip of the protrusion 7 of the load concentration plate 5 (the upper surface in the illustrated example), and the molding material 11b. The end surface (the upper surface in the illustrated example) is flush with (is located on the same surface).

  Then, as shown in FIG. 2C, the optical fiber block 12 and the load concentrating plate block 13 are bonded together so that the optical fiber block 12 and the load concentrating plate block 13 are integrated. An adhesive or the like can be used when the optical fiber block 12 and the load concentration plate block 13 are bonded together.

  In short, in the present embodiment, the optical fiber block 12 is formed by coating POF1 with the molding material 11a, and the load concentration plate block 13 is formed by coating the load concentration plate 5 with the molding material 11b. 12 and the load concentrating plate block 13 are bonded together to be integrated.

  That is, in the present embodiment, the POF 1 and the load concentrating plate 5 are separately covered with the molding materials 11a and 11b, so that no gap is formed between the POF 1 and the molding material 11a (6). And the mold material 11a can be brought into close contact with each other, and the generation of a dead zone in a low load region can be eliminated (suppressed). Further, the mold material 11a covering the POF 1 and the mold material 11b covering the load concentration plate 5 can be separately hot pressed, and the POF 1 is not deformed by the load concentration plate 5 during the high temperature pressing. Therefore, appropriate impact detection without initial deformation of the POF 1 is possible.

  Further, according to the present embodiment, when the optical fiber block 12 is formed, the portion of the POF 1 in contact with the load concentration plate 5 and the end surface of the molding material 11a are flush with each other, and the load concentration plate block 13 is formed such that the portion of the load concentrating plate 5 in contact with the POF 1 and the end surface of the molding material 11b are flush with each other, so that the optical fiber block 12 and the load concentrating plate block 13 are bonded together. , POF 1 can be brought into contact with the projection 7 of the load concentration plate 5.

  Next, the manufacturing method of the impact detection optical fiber sensor which concerns on other embodiment is demonstrated.

  In the embodiment shown in FIG. 3, the molding material 21a (that is, the molding material 21a on the optical fiber block 22 side) covering the POF 1 shown in FIG. 3 (a) and the load concentration plate 5 shown in FIG. 3 (b) are covered. The molding material 21b (that is, the molding material 21b on the load concentrating plate block 23 side) changes the characteristics (for example, elasticity (hardness), etc.) of the molding materials 21a and 21b. By doing so, the deformation shape of the POF 1 is controlled after the optical fiber block 22 and the load concentrating plate block 23 are bonded together as shown in FIG. Sensitivity can be adjusted.

  For example, the molding material 21a for covering the POF 1 and the molding material 21b for covering the load concentrating plate 5 by blending a vulcanizing agent (or crosslinking agent) such as sulfur added to the raw rubber when the raw rubber is vulcanized (or crosslinked). And can change the characteristics. In this embodiment, the elasticity of the molding material 21 a that covers the POF 1 is made higher than the elasticity of the molding material 21 b that covers the load concentration plate 5. Note that the elasticity of the mold material 21 a covering the POF 1 may be lower than the elasticity of the mold material 21 b covering the load concentration plate 5.

  In the embodiment shown in FIG. 4, unlike the embodiment shown in FIG. 2, when forming the optical fiber block 32, the outer periphery of the POF 1 is completely covered with the molding material 31a as shown in FIG. Like to do. Further, as shown in FIG. 4B, when the load concentration plate block 33 is formed, the outer surface of the load concentration plate 5 is completely covered with the molding material 31b. By doing so, as shown in FIG. 4C, the POF 1 and the load concentration plate 5 are molded on the optical fiber block 32 side until the optical fiber block 32 and the load concentration plate block 33 are bonded together. It is possible to prevent the material 31a and the mold material 31b on the load concentration plate block 33 side from falling off.

  By the way, in the embodiment shown in FIG. 4, as shown in FIG. 4C, the mold materials 31 a and 31 b are interposed between the POF 1 and the protrusion 7 of the load concentration plate 5. The molding materials 31 a and 31 b interposed between the POF 1 and the projection 7 of the load concentration plate 5 can prevent (suppress) the POF 1 from being cut when the POF 1 is pressed against the projection 7. In addition, the sensitivity of the sensor can be adjusted by appropriately setting the thickness in the load input direction of the molding materials 31a and 31b interposed between the POF 1 and the protrusion 7 of the load concentration plate 5.

The impact detection optical fiber sensor which concerns on one Embodiment of this invention is shown, (a) It is a front view, (b) is Ib-Ib arrow sectional drawing of Fig.1 (a), (c) is a figure. It is Ic-Ic line arrow directional cross-sectional view of 1 (b). (A) to (c) is a schematic diagram for explaining a manufacturing method of an impact detection optical fiber sensor according to an embodiment of the present invention. (A) to (c) is a schematic diagram for explaining a manufacturing method of an impact detection optical fiber sensor according to another embodiment. (A) to (c) is a schematic diagram for explaining a manufacturing method of an impact detection optical fiber sensor according to another embodiment. The impact detection optical fiber sensor which the present applicants are developing is shown, (a) is a sectional side view, (b) is a sectional view taken along line Vb-Vb in FIG.

Explanation of symbols

1 Optical fiber (POF)
5 Load Concentration Plate 6 Mold Material 7 Protrusion 11a, 11b Mold Material 12 Optical Fiber Block 13 Load Concentration Plate Block 21a, 21b Mold Material 22 Optical Fiber Block 23 Load Concentration Plate Block 31a, 31b Mold Material 32 Optical Fiber Block 33 Load Concentration Plate block

Claims (7)

A method of manufacturing an impact detection optical fiber sensor comprising: an optical fiber; a load concentrating plate having a plurality of projections and depressions arranged along the longitudinal direction of the optical fiber; and a mold material covering the optical fiber and the load concentrating plate The optical fiber is coated with the mold material by extrusion to form an optical fiber block, and the load concentration plate is coated with the mold material to form a load concentration plate block. A manufacturing method of an impact detection optical fiber sensor characterized by integrating by sticking a board block.   2. The impact detection according to claim 1, wherein when the optical fiber block is formed, a portion of the optical fiber that contacts the load concentration plate and an end surface of the molding material that covers the optical fiber are flush with each other. Manufacturing method of optical fiber sensor.   The portion of the load concentration plate that contacts the optical fiber and the end surface of the molding material that covers the load concentration plate are flush with each other when the load concentration plate block is formed. A method of manufacturing the shock detection optical fiber sensor as described.   2. The method of manufacturing an impact detection optical fiber sensor according to claim 1, wherein when forming the optical fiber block, an outer periphery of the optical fiber is completely covered with the molding material.   5. The method of manufacturing an impact detection optical fiber sensor according to claim 1, wherein when forming the load concentration plate block, an outer surface of the load concentration plate is completely covered with the molding material.   The method for producing an impact detection optical fiber sensor according to any one of claims 1 to 5, wherein characteristics are changed between the molding material that covers the optical fiber and the molding material that covers the load concentration plate. An optical fiber for detecting an impact, a light emitting element connected to one end of the optical fiber, a light receiving element connected to the other end of the optical fiber, and a plurality arranged along the longitudinal direction of the optical fiber In an impact detection optical fiber sensor comprising a load concentrating plate having unevenness and a mold material covering the optical fiber and the load concentrating plate, the optical fiber is covered with the mold material by extrusion to form an optical fiber block And the load-concentrating plate is covered with the mold material to form a load-concentrating plate block, and the optical fiber block and the load-concentrating plate block are bonded together to be integrated. Sensor.

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