JP4809680B2 - Impact detection sensor - Google Patents

Description

  The present invention relates to an impact detection sensor that detects an impact when a vehicle collides with a pedestrian or the like.

  As an impact detection sensor that detects impact when a vehicle collides with a pedestrian, another vehicle, or an obstacle, for example, an optical fiber is used, and the impact is detected from optical transmission loss due to bending or distortion of the optical fiber due to impact. (For example, patent document 1).

Japanese Patent Laying-Open No. 2005-140752

  As an impact detection sensor using an optical fiber, in order to increase sensitivity, a sensor provided with a metal plate having a concavo-convex portion along the longitudinal direction of the optical fiber as shown in FIG. 5 has been studied. 5 includes an optical fiber 52, a metal plate 53 provided with a concavo-convex portion by punching, and a mold portion 54 formed of a resin such as silicone rubber that covers the optical fiber 52 and the metal plate 53. It is composed of The mold part 54 is molded in a substantially rectangular cross section.

  The impact detection sensor 51 provided with the metal plate 53 has the following problems.

  Since the metal plate 53 is arranged along the optical fiber 52, the length of the collision detection sensor 51 that can be manufactured at a time in the manufacturing process is limited, and the cost including the parts cost of the metal plate 53 is high. Further, since the impact detection sensor 51 is provided with the metal plate 53, the flexibility is not good. Moreover, the application direction of the impact which can be detected was limited (in FIG. 5, the vertical direction in the figure can be detected).

  On the other hand, when installing an impact detection sensor in a vehicle, etc., an ON / OFF detection sensor (for example, a cord switch) is separately detected to detect the impact caused by a collision in order to prevent the impact detection sensor from malfunctioning. Etc.).

  An object of the present invention is to provide an impact detection sensor having a configuration in which sensitivity is improved without using a metal plate, and a detection sensor for preventing malfunction.

In order to achieve the above object, an impact detection sensor of the present invention includes a plastic optical fiber, a light source connected to one end of the plastic optical fiber, a light receiver connected to the other end of the plastic optical fiber, and the plastic A cord switch wound around an optical fiber, and the cord switch are arranged in a longitudinal direction along the inner surface of a cross-section hollow insulator made of a restoring rubber or a restoring plastic in a state where at least two electrode wires are not in electrical contact with each other. An impact detection sensor comprising: a cord switch disposed in a spiral shape; and a mold portion that covers the plastic optical fiber and the cord switch.

The cross-sectional shape of the mold part is preferably substantially circular.

  The impact detection sensor of the present invention has an optical fiber, a cord switch wound around the optical fiber, and a mold part that covers the optical fiber and the cord switch, thereby improving sensitivity and preventing malfunction by the cord switch. It is possible to realize a configuration including a sensing sensor for use.

  Hereinafter, an embodiment of the present invention will be described in detail with reference to the accompanying drawings.

  FIG. 1 shows an embodiment of the impact detection sensor of the present invention. The impact detection sensor 1 includes an optical fiber 2, a cord switch 3 wound around the optical fiber 2, and a mold portion 4 that covers the optical fiber 2 and the cord switch 3. The cord switch 3 is wound around the optical fiber 2 in a spiral shape along the longitudinal direction.

  As the optical fiber 2, a plastic optical fiber (POF), particularly a heat-resistant plastic fiber (HPOF) can be preferably used. In this embodiment, HPOF is used as the optical fiber 2. The HPOF 2 includes a core 5 having a circular cross section for propagating light and a clad 6 having a cylindrical cross section that covers the outer periphery of the core 5 concentrically. As a material of the core 5, a synthetic resin excellent in heat resistance, for example, an acrylic resin, a crosslinked acrylic resin (thermosetting acrylic resin), or a silicone resin is used. As a material of the clad 6, a synthetic resin excellent in heat resistance, water resistance, and mechanical properties, for example, a fluororesin such as a fluorinated ethylene propylene resin is used. In HPOF2, optical transmission loss occurs according to bending and compression. As the optical fiber 2, a glass optical fiber can be used in addition to the plastic optical fiber.

  As the cord switch 3, a cord switch described in Japanese Patent Publication No. 9-21235 is used. The cord switch 3 includes an electrode wire 8 and a hollow insulator 7. The electrode wire 8 is spirally arranged in the longitudinal direction along the inner surface of the hollow insulator 7 made of a restoring rubber or a restoring plastic while maintaining a predetermined interval. The hollow insulator 7 holds and fixes the electrode wire 8 in a spiral shape without being in electrical contact, is easily deformed by an external force, and immediately recovers when the external force disappears. The electrode wire 8 is made of a metal conductor such as a copper wire or a copper alloy or a metal stranded wire obtained by twisting a plurality of metal strands. Furthermore, the electrode wire 8 has a structure in which a conductive rubber layer or a conductive plastic layer is provided on the outer periphery of the metal conductor wire in order to improve the restoring property and the holding and fixing force of the electrode wire by the hollow insulator 3. . Since the electrode wires 8 come into contact with each other when the hollow insulator 7 is deformed by an external force, by applying a voltage to the electrode wires 8 in advance and detecting that the electrode wires 8 are short-circuited from changes in voltage or current, The deformation of the cord switch 3 is detected. The cord switch 3 is not limited to the one in the present embodiment, and any cord switch 3 may be used as long as it has flexibility to be wound around the optical fiber 2 and has a switch function in the wound state. A cord switch of the form can be used.

  The mold part 4 is formed by molding around the HPOF 2 around which a cord switch is wound using a synthetic resin (for example, silicone rubber) softer than the optical fiber 2 (HPOF 2 in this embodiment). The mold part is molded so as to have a substantially circular cross section. The cross-sectional shape of the mold part 4 may be an ellipse or an oval according to the application of the impact detection sensor 1.

  FIG. 2 shows a view when the impact detection sensor of the present invention is laid on a bumper of a vehicle. The impact detection sensor 1 is laid in a bumper of a vehicle by bending it into a U shape. In the impact detection sensor 1, a light source 22 made of LED or LD is connected to one end of the HPOF 2 exposed from the impact detection sensor 1, and a light receiver 23 made of PD is connected to the other end of the HPOF 2 similarly exposed. The light source 22 and the light receiver 23 are connected to an impact analysis apparatus (not shown) by electric wires (power supply line, ground line, signal line) 24. An electrode wire (not shown) exposed from the cord switch 3 is connected to a pressure sensing device (not shown).

  Next, the operation of the impact detection sensor of the present invention will be described.

  During normal times when no impact is applied to the impact detection sensor 1, the light transmitted to the HPOF 2 has no transmission loss due to bending or distortion, and the electrode wires 8 of the cord switch 3 are insulated from each other.

  When an impact is applied to the impact detection sensor 1, as shown in FIGS. 3 (a) and 3 (b), the impact detection sensor 1 is deformed by receiving a load from one direction indicated by an arrow in a certain region in the longitudinal direction. To do. The cord switch 3 is deformed by receiving a load, and the electrode wire 8 is short-circuited. Changes in voltage, current, and resistance due to a short circuit are sent to the pressure sensing device as a short circuit signal. Thereby, it is detected that an impact is actually applied to the impact detection sensor 1. Since the cord switch 3 is wound around the HPOF 2, the HPOF 2 is bent and distorted by the cord switch 3. Due to this bending and distortion, an optical transmission loss corresponding to the impact occurs. As shown in FIG. 4, the amount of light transmitted through the HPOF 2 decreases rapidly when an impact is applied, and then gradually decreases and returns to the original amount of light. The impact analysis apparatus estimates the property, weight, size, and the like of the impacted object from the waveform shape of the transmitted light amount.

  Next, the operation of the impact detection sensor of the present invention will be described.

  The impact detection sensor of the present invention can detect an impact from a change in the amount of light transmitted through the optical fiber, and has a cord switch, so that it is possible to apply an impact without providing a separate sensor for preventing malfunction. Can detect presence or absence.

  Moreover, since the impact detection sensor of this invention has flexibility, it can be bent easily and is excellent in the attachment property to an installation location.

  Further, in the impact detection sensor of the present invention, the application direction of the impact that can be detected is not limited.

  In addition, the impact detection sensor of the present invention has a configuration in which a cord switch is wound around an optical fiber and a mold part is formed on the outer periphery thereof, so that it can be manufactured in a long length and cost can be reduced. is there.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a structural diagram of an impact detection sensor showing an embodiment of the present invention, where (a) is a cross-sectional view of a cross section perpendicular to the longitudinal direction, and (b) is a side perspective view. It is laying figure of the impact detection sensor of this invention. It is a structural view at the time of impact application of the impact detection sensor of the present invention, (a) is a cross-sectional view of a cross section perpendicular to the longitudinal direction, (b) is a side perspective view. It is a time waveform figure of the transmitted light amount and resistance value which the impact detection sensor of this invention outputs. It is a figure of an example of an impact detection sensor.

Explanation of symbols

1 Impact detection sensor 2 Optical fiber (for example, HPOF)
3 Cord switch 4 Mold part

Claims (2)

Plastic optical fiber,
A light source connected to one end of the plastic optical fiber;
A receiver connected to the other end of the plastic optical fiber;
A cord switch wound around the plastic optical fiber;
The cord switch is arranged in a spiral shape in the longitudinal direction along the inner surface of a cross-section hollow insulator made of a restoring rubber or a restoring plastic in a state where at least two electrode wires are not in electrical contact with each other. And
A mold part covering the plastic optical fiber and the cord switch;
An impact detection sensor comprising: The impact detection sensor according to claim 1, wherein a cross-sectional shape of the mold part is substantially circular .

Images