JPS5848005A - Optical fiber cable of harness for automobile - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an optical fiber cable in which protrusions are periodically provided on the outer peripheral surface of the cable in order to prevent excessive bending.

Transmission of control signals inside an automobile can be performed using optical fibers. Conventionally, optical fiber cables have had a constant cross-sectional shape.

For example, it is a cable with a smooth circular cross section and an outer diameter of 2 to 3 m. This has a fiber core in the center, Kevlar for reinforcement around it, and a flexible resin fiber cord covering the outside.

The fiber core wire is a quartz wire coated with a resin such as nylon or polyethylene. The quartz wire (1) has a higher tensile strength than the copper wire, but it does not undergo plastic deformation.
May cause brittle fracture. Since it is coated with resin,
Fiber core wire resists bending well.

However, if the surface of the quartz wire is scratched, it will easily break from there.

Even if there are no scratches at first, if the cable is bent repeatedly, scratches will appear on the surface of the wire. In particular, if the wire is bent with a small radius of curvature, the wire will break.

The present invention is intended to solve these drawbacks, and aims to provide an optical fiber cable having periodic protrusions on its outer peripheral surface.

EMBODIMENT OF THE INVENTION Hereinafter, the structure, operation, and effect of the present invention will be explained in detail with reference to drawings showing examples.

FIG. 1 is a partially cutaway perspective view of an optical fiber cable according to an embodiment of the present invention.

This optical fiber cable A has a fiber core 1 at the center. Kevlar 2 for tensile reinforcement is provided around the core wire. Further, on the outside of the Kevlar 2, a flexible and thick fiber cord 3 made of synthetic resin is provided. Conventional fiber optic cables consist of cord 3 or simply a uniform circular cross-section.

In the present invention, the fiber cord 31 has a small diameter section 4 having a small diameter and a large diameter section 5 having a large diameter, which are alternately and continuously formed.

When this is strongly curved, it becomes as shown in Figure 2.

The fiber core wire 1 is located at the neutral line, and the cord 3 extends on the outside of this line, and contracts on the inside of this line. Therefore, the radius of curvature R of the curved portion becomes smaller in inverse proportion to the bending force.

However, the radius of curvature R does not become infinitely small.

There is a lower limit. The inner ends 6, 6 of the large diameter portion 5 are in contact next to each other and are prevented from curving further.

3 is a cross-sectional plan view of the curved optical fiber cable of FIG. 2; FIG. The radius of curvature when the large circular diameter portion 5 touches the inner end 6.6, that is, the minimum radius of curvature R, mn, is the diameter of the small circular diameter portion 4, d, the axial length, and the large circular diameter portion 5. It can be evaluated as follows, assuming that the diameter is D and the axial length is b.

That is, assuming that the fiber core wire 1 is on the neutral line and does not expand or contract, it is given by:

In the example shown in FIG. 3, the small diameter portion 4 and the large diameter portion 5 are made of the same synthetic resin. This can be manufactured using a special extrusion process.

However, the present invention is not limited to this, and it is sufficient that the small circular diameter portion 4 and the large circular diameter portion 5 are effectively repeatedly formed. Therefore, it is possible to simply insert rings having an outer diameter D, an inner diameter d, and a thickness b into a straight cross-sectional cord having a diameter d at intervals of a, and then adhere them.

The optical fiber cable of the present invention is not limited to a circular cross section. An elliptical cross section or a gate-shaped rectangular cross section may also be used.

FIG. 4 is a partially cutaway perspective view of an optical fiber cable according to another embodiment.

The optical fiber cable B has a fiber core 1 and a Kevlar 2 passed through the center of a flat cord main body 7 having a width f and a height g.

In addition, on the lower surface of the eccentric code main body 7, width f and height 11
Square protrusions 8 are provided periodically. The flat cord main body 7 and the rectangular protrusion 8 can be molded at the same time, but the rectangular protrusion 8 may be bonded or welded later.

The axial length of the square protrusion gA8 is k, and the interval between adjacent square protrusions 8 is j.

If the optical fiber cable B is bent in the direction in which the rectangular protrusion 8.8 is provided -1- downward, the end sides 9, 9 of the adjacent protrusions 8, 8 will eventually come into contact. This prevents the radius of curvature R from becoming too small.

With the same assumptions as in the previous example, the minimum radius of curvature R,n is given by:

The protrusions do not necessarily have to be separated.

It doesn't matter if they are consecutive.

Figure 5 shows an optical fiber cable C with a spiral protrusion.
FIG. This is the code main body 1 with a circular cross section.
0, a spiral protrusion 11 with a width is formed on the outside. Since it is a spiral, the protrusion 11 is continuous.

Assuming that the pitch of the spiral is a -1-b, the outer diameter of the cord body]0 is d, and the outer diameter of the spiral protrusion]1 is D, the minimum radius of curvature R, can be expressed by the above equation (1). can.

As in the previous examples, the main body 1o and the spiral protrusion 11 can be extruded together at the same time, or the helical protrusion 11 is glued or welded to the outer surface of the cord main body 1o in a spiral shape. You may also do this.

The protrusion does not need to be continuous in the direction perpendicular to the axis. There may be many isolated protrusions.

FIG. 6 is a partial plan view of an optical fiber cable D having a large number of isolated protrusions on its outer surface.

This optical fiber cable D has a cord main body 1 with a circular cross section.
A large number of cylindrical projections 14 are provided on the surface of 3.

If the axial direction is the Z axis, in a certain X, y plane, "l
Y I M I There is a protrusion in the Y-axis direction. This is provided for each pitch l).

Furthermore, a protrusion is provided at a position that forms an angle of 45° with these at a distance of half a pitch.

In other words, (1) at the position Z=np (n is an integer) (1,0), (0,1), (-1,0),
Four protrusions of (0, -1) and four protrusions of (0, -1) are provided.

This is just one example; the number N of protrusions on the -xy plane and the number m of twisted positions within one pitch P are arbitrary.

Generally, the position of a protrusion can be expressed by the above definition. This shows the n-th pitch, the first twisting position, and the three-dimensional position of the S-th protrusion on this plane (1≦[5m, l≦S≦N).

In this example, the protrusion shape is cylindrical. However, it may have a rectangular shape or an elliptical cross-sectional shape.

Furthermore, not only one type of protrusion shape but also two types of protrusion shapes may be provided periodically.

The main body of the code may be square instead of circular.

In the example shown in FIG. 4, the main body of the cord was formed with a flat rectangular cross section, so the long sides had square protrusions 8, 8.・・・・・・
・ has been established.

However, in the case of a square cross-section cord, it is better to provide protrusions on both sides. This is because it can curve in either direction.

FIG. 7 is a partially cutaway perspective view showing such an embodiment.

The optical fiber cable E has a cord main body 15 having a square cross section and having a fiber core wire 1 and a Kevlar 2 at the center, and a large number of rectangular parallelepiped-shaped protrusions are provided periodically.

The protrusions 16 are provided on the four sides of the main body 15, but instead of being continuous four pieces, there are notches 17 at the corners. Since this cable has a square cross section with side f,
It is easy to bend left and right, but it is difficult to bend diagonally.

Therefore, a 45° corner is cut out.

The height of the protrusion 16 is ll, and the axial thickness of the protrusion 16 is k.
, if the gap between the protrusions is j, then the minimum radius of curvature can be expressed as.

As explained in detail, the optical fiber cable of the present invention is provided with periodic protrusions on the outer peripheral surface of the main body of the cord, so that the protrusions come into contact with each other to prevent excessive bending of the cable. be able to.

The optical fiber cable of an automobile harness is sometimes attached to the automobile body and a movable part such as a door, and is subjected to repeated bending stress. Also, during installation, it may be incorrectly bent excessively.

In this case, the optical fiber inside the cable is likely to break.

The present invention provides a protrusion in the shape of the outer sheath of the cable,
Prevents cables from bending due to excessive curvature. Therefore, the optical fiber is not subjected to excessive bending stress and is less susceptible to brittle fracture.

The present invention has the effect of preventing the optical fiber from being cut and extending its life.

In this way, it is a useful invention.

[Brief explanation of the drawing]

FIG. 1 is a partially cutaway perspective view of an optical fiber cable according to an embodiment of the present invention, in which the cord has a circular cross section and the protruding portion also has a circular cross section. FIG. 2 is a plan view of the optical fiber cable in a curved state. FIG. 3 is a cross-sectional plan view of the optical fiber cable of FIG. 2. FIG. 4 is a partially cutaway perspective view of an optical fiber cable according to another embodiment, and the cord has a flat rectangular cross section. FIG. 5 is a partial plan view of an optical fiber cable according to a third embodiment, which has a helical protrusion. FIG. 6 is a partial plan view of an optical fiber cable according to a fourth embodiment, in which a large number of cylindrical projections are provided on the outer surface of the cord. FIG. 7 is a partially cutaway perspective view of an optical fiber cable according to a fifth embodiment, in which the cord has a square cross section and rectangular protrusions are provided on four sides. ■... Fiber core wire □ 2... Kevlar 3... Fiber cord 4... Small circle diameter section 5... Large circle diameter section 6... Inner end 7 ・... Code main body 8 ... Square protrusion 10 ... Code main body 11 ... Spiral protrusion 13 ... Code main body 14 ... Cylindrical projection 15 - Code main body 16 ... Protrusion Parts A, B, C, D, E... Optical fiber cables

Claims (1)

[Claims] An optical fiber cable for an automotive harness characterized by periodically providing protrusions on the outer peripheral surface to prevent excessive curvature.