JP2006147410A - Coaxial cable - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a coaxial cable reducing noise generated when the coaxial cable vibrates and collides with a surrounding construction. <P>SOLUTION: The coaxial cable 1 is composed of a central conductor 3, an insulation body 5 covering the outer periphery of the central conductor 3, an external conductor 7 shielding the outer periphery of the insulation body 5, and a sheath 9 covering the outer periphery of the external conductor 7. The sheath 9 is made of a material and formed into a shape of reducing a vibration impact sound. For example, a plurality of protrusions 9C are formed radially on the outer periphery of the sheath 9 at regular intervals. Consequently, when the coaxial cable 1 collides with the surrounding construction, the plurality of protrusions 9C absorb and reduce the vibration impact sound, and the noise is reduced. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a coaxial cable, and more particularly to a coaxial cable that reduces noise generated when a coaxial cable installed inside an electric device or a moving body vibrates with a surrounding structure.

  Referring to FIG. 9, a conventional coaxial cable 101 has a structure in which a central conductor 103 made of copper wire having an outer diameter of 0.5 mmφ and polyethylene insulation in which the outer periphery of the central conductor 103 is coated to an outer diameter of 1.6 mmφ. A body 105, an outer conductor 107 made of a copper wire braid shielded on the outer periphery of the insulator 105, and a resin such as vinyl chloride (PVC) or polyethylene having an outer diameter of 3.0 mm. And a cylindrical sheath 109.

  The coaxial cable 101 as described above is used everywhere in indoors, outdoors, in equipment, vehicles, and the like for transmission of high-frequency electrical signals. Moreover, since the coaxial cable 101 is generally a linear body exceeding several meters, in the mounting structure of the coaxial cable 101, the building is formed by binding or adhesive tape at a plurality of points or in the longitudinal direction of the coaxial cable 101. It is fixed to the structure.

  When the coaxial cable 101 is used in a place where the coaxial cable 101 vibrates, for example, in a place such as a vibrating mechanical device or a vehicle, quietness may be required as an environment in the mechanical device or the vehicle. The problem in this case is that the coaxial cable 101 floats in the air at a portion other than the attachment point, so that the coaxial cable 101 also vibrates due to the vibration of the mechanical device or the vehicle, and the amplitude of the coaxial cable 101 is increased. If it becomes large, it will collide with surrounding structures, generate noise, and degrade the calm environment. However, the structure of the conventional coaxial cable 101 cannot avoid noise generated when it collides with or comes into contact with surrounding structures.

  Conventionally, as a countermeasure, noise generated by installing a soft sponge or rubber material between the coaxial cable 101 floating in the air and the structure is absorbed.

  Another example for conventional soundproofing is not the coaxial cable 101 as described above, but an example of an inner cable. That is, piles are formed radially around the core yarn to form a molding, and this molding is wound around the groove formed by the helical teeth of the geared cable and the core cable, or in the folds of the outer layer of the shaft cable. There is a method of absorbing the noise of the cable by bonding and configuring (for example, see Patent Document 1).

  Or there is an example of a soundproof toothed cable. A general toothed cable includes a core made of a metal stranded wire and a tooth (coil) made of a metal wire spirally wound at equal intervals with a gap around the core. The toothed cable has flexibility and is slidably accommodated inside the conduit, and is then driven by being engaged with a gear or other toothed cable. And a driven member is connected to the end part or the middle, and it is used for other various machines, for example, remote operation of opening and closing of a sunroof of a car, and raising and lowering of a window glass. At this time, a soundproof toothed cable has been proposed in order to prevent the generated noise.

As this soundproof toothed cable, a synthetic resin or rubber tube is tightly wound between the above-mentioned teeth (coils) and spirally wound on the core, and the outer surface of the tube is outside the outer surface of the teeth. This is a method of absorbing noise by winding so as to protrude in the direction (see, for example, Patent Document 2).
JP-A-6-294460 Japanese Patent No. 3226893

  By the way, the above-described conventional coaxial cable 101 has a problem that a new part such as sponge or rubber is required, and the part cost is increased, and further, the attachment cost is inevitably increased. In other words, this conventional technology requires a cheap and high-performance industrial product, so there is no doubt that further improvement should be made.

  Also, in the above-described conventional Patent Document 1 and Patent Document 2, it is obvious that in any case, the structure is complicated, resulting in an increase in the cost of the cable.

  The present invention has been made to solve the above-described problems.

A coaxial cable according to the present invention comprises a central conductor, an insulator coated on the outer periphery of the central conductor, an outer conductor shielded on the outer periphery of the insulator, and a sheath coated on the outer periphery of the outer conductor. In
The sheath is formed of an outer peripheral shape or material that reduces vibration impact sound.

  In the coaxial cable according to the present invention, it is preferable that a plurality of protrusions are formed radially at equal intervals in the circumferential direction of the sheath on the outer periphery of the sheath.

  In the coaxial cable of the present invention, in the coaxial cable, the cross-sectional shape of the protrusion is preferably a polygon, an arc, or a combination of a polygon and an arc.

  In the coaxial cable according to the present invention, in the coaxial cable, in the longitudinal direction of the sheath, the shape of the protrusion is preferably a fixed height, a polygon, an arc, or a combination of a polygon and an arc. .

  In the coaxial cable according to the present invention, in the coaxial cable, the material of the sheath is made of foamed polyethylene, and the thickness of the sheath is 1.5 mm or more and 3.0 mm or less. preferable.

  As can be understood from the means for solving the problems as described above, according to the present invention, the outermost sheath of the coaxial cable itself reduces vibration and impact sound generated by colliding with surrounding structures. Therefore, when the coaxial cable collides with a surrounding structure, the structure of the sheath absorbs and reduces vibration impact sound, and noise can be reduced.

  Embodiments of the present invention will be described below with reference to the drawings.

  Referring to FIG. 1, a coaxial cable 1 according to a first embodiment of the present invention has a central conductor 3 made of a copper wire having an outer diameter of 0.5 mm, for example, at the center of the cable 1 with respect to the paper surface. Are extended in a direction perpendicular to each other. Further, the periphery of the center conductor 3 is covered with an insulator 5 made of a resin such as polyethylene so that the outer diameter a is 1.6 mmφ, for example. Further, the outer periphery of the insulator 5 is shielded by an outer conductor 7 made of, for example, a copper wire braid. A sheath 9 made of a resin such as vinyl chloride (PVC) or polyethylene is provided on the outer periphery of the outer conductor 7.

   The coaxial cable 1 transmits a high-frequency electrical signal between the center conductor 3 and the outer conductor 7, and the sheath 9 is used to protect the outer conductor 7 from the center conductor 3. Is.

  In general, the coaxial cable 1 of the present invention is characterized in that the sheath 9 is composed of an outer peripheral shape or material that reduces vibration and impact noise.

  In this respect, the coaxial cable 1 according to the first embodiment has a cylindrical shape in which the sheath 9 has a constant thickness on a plane perpendicular to the longitudinal direction of the coaxial cable 1, as shown in FIG. Of the sheath thick portion 9A, and a projection portion 9B composed of eight projections 9C formed radially at equal intervals on the outer circumference of the sheath thick portion 9A. .

  In the first embodiment, the outer diameter of the sheath thick portion 9A, that is, the outer diameter b of the inscribed circle with the protrusion 9B is 3.0 mmφ, and the eight protrusions 9B have the eight diameters. Each of the projections 9C has a triangular cross-sectional shape. The triangular projection 9C has a projection bottom width c of 1.2 mm and a projection height d of 1.5 mm. Therefore, the outer diameter e of the circumscribed circle of the protrusion 9B is 6.0 mmφ, and the outer diameter e of the circumscribed circle is the outer diameter dimension of the coaxial cable 1 of the first embodiment.

  With the configuration described above, in the coaxial cable 1 according to the first embodiment, the sheath 9 has eight protrusions 9C arranged at equal intervals in the circumferential direction on the outer periphery of the sheath thick part 9A. Therefore, even if the coaxial cable 1 collides with the surrounding structure so as to generate a vibration impact sound, the impact can be absorbed by the protrusion 9C of the protrusion 9B to reduce noise.

  Next, the manufacturing process of the coaxial cable 1 of the first embodiment will be described.

  Referring to FIG. 2, (1) as an insulating process part, the central conductor 3 is fed into, for example, an extrusion head 13 as an extrusion mold of an extrusion molding machine 11, and the center is formed in the extrusion head 13. The conductor 3 is extrusion coated with an insulator 5 made of polyethylene.

  In the extrusion head 13 of the extrusion molding machine 11, a nipple (not shown) that allows the central conductor 3 to pass through is installed at a predetermined position in a die for extruding polyethylene of the insulator 5 described above. In other words, the central conductor 3 is sent so as to pass through the die through a predetermined position in the nipple, and the polyethylene as the insulator 5 flows through the flow path in the die and passes the central conductor 3 from the tip of the die. The insulation 5 is covered and fixed so as to be substantially at the center, and is extruded.

  Thereafter, (2) as a braiding step, the outer periphery of the insulator 5 is braided with a copper wire by the outer conductor braiding device 15 and shielded by the outer conductor 7.

  Next, the cable 1A in which the outer conductor 7 is shielded is sent into the extrusion head 19 of the extrusion machine 17, and the periphery of the outer conductor 7 in the extrusion head 19 is chlorinated in the first embodiment. It is extrusion coated with a sheath 9 made of vinyl (PVC).

  At this time, (3) as a sheath process part, the inside of the extrusion head 19 of the extruder 17 includes a die (not shown) having a die hole for extruding the vinyl chloride (PVC) of the sheath 9 in the cross-sectional shape shown in FIG. A nipple (not shown) having a nipple hole through which the cable 1A with the outer conductor 7 shielded passes is provided at a predetermined position in the die. The shape of the die hole is such that the cross-sectional shape of the sheath 9 is a cylindrical sheath thick portion 9A having a constant thickness as shown in FIG. 1, and radially on the outer periphery of the sheath thick portion 9A. It is formed so as to be composed of the eight triangular protrusions 9C formed.

  Accordingly, the cable 1A is sent so as to pass through the die through a predetermined position in the nipple, and the polyethylene flows through the flow path in the die so that the cable 1A is passed through the sheath 9 of the sheath 9 from the tip end of the die. The thick part 9A is extrusion-molded by being fixed so as to be substantially at the center position. As described above, the outer diameter b of the sheath thick portion 9A of the sheath 9 (inscribed circle of the protrusion 9B) is 3.0 mmφ, and the outer diameter e of the circumscribed circle is 6.0 mmφ. 1 is manufactured. In FIG. 2, (1) insulation process, (2) braiding process, and (3) sheath process are depicted on the same production line, but (1) insulation process, (2) braiding process, and (3) sheath process. May be a separate production line.

  Referring to FIG. 3, the coaxial cable 21 according to the second embodiment of the present invention will be described by assigning the same reference numerals to the same parts as those of the coaxial cable 1 of the first embodiment described above.

  In the coaxial cable 21 of the second embodiment, the central conductor 3, the insulator 5, and the outer conductor 7 are similar in configuration, size, material, and the like to the coaxial cable 1 of the first embodiment. The cross-sectional shape of the sheath 23 is different from the sheath 9 of the coaxial cable 1 according to the first embodiment. However, the material of the sheath 23 is the same as that of the sheath 9.

  That is, the sheath 23 includes a cylindrical sheath thick portion 23A having a constant thickness on a surface perpendicular to the longitudinal direction of the coaxial cable 21, and an outer periphery of the sheath thick portion 23A at equal intervals in the circumferential direction. And a protrusion 23B including 16 protrusions 23C formed radially.

  In the second embodiment, the outer diameter of the sheath thick part 23A, that is, the outer diameter b of the inscribed circle with the protrusion 23B is 3.0 mmφ, and the 16 protrusions 23B have 16 pieces. Each of the projections 23C has a triangular cross-sectional shape. The triangular projection 9C has a projection bottom width c of 0.6 mm and a projection height d of 1.5 mm. Therefore, the outer diameter e of the circumscribed circle of the protrusion 23B is 6.0 mmφ, and the outer diameter e of the circumscribed circle is the outer diameter dimension of the coaxial cable 21 of the second embodiment.

  With the configuration described above, in the coaxial cable 21 according to the second embodiment, the sheath 23 is arranged on the outer periphery of the sheath thick portion 23A with 16 projections 23C arranged at equal intervals in the circumferential direction. Therefore, the shock absorbing ability is improved as compared with the case where the number of the protrusions 9C of the coaxial cable 1 is eight. Therefore, even if the coaxial cable 21 collides with a surrounding structure and a vibration impact sound is generated, the impact is absorbed by the projection 23C of the projection 23B, so that the noise can be further reduced than the coaxial cable 1.

  4A to 4I, in the coaxial cable 1 and the coaxial cable 21 according to the first and second embodiments described above, the protrusions 9C in the circumferential direction of the sheaths 9 and 23, Although the case where the cross-sectional shape of 23C is the triangle shown in FIG. 4A has been described, for example, polygons such as FIGS. 4B to 4I, arcs, or combinations of polygons and arcs. Any shape or other shapes may be used. 4 (B) is a semi-elliptical or semi-circular shape, FIG. 4 (C) is a trapezoid or inverted trapezoid, FIG. 4 (D) is a rectangle, FIG. 4 (E) is a combination of a trapezoid and a triangle, and FIG. ) Is a combination of trapezoids and semi-elliptical circles, FIG. 4G is a combination of rectangles and triangles, FIG. 4H is a combination of rectangles and semi-elliptical circles, and FIG. 4I is a combination of rectangles and trapezoids. It is a combination.

  Referring to FIGS. 5A to 5E, the coaxial cable 1 and the coaxial cable 21 of the first and second embodiments described above are cross sections of the protrusions 9C and 23C in the longitudinal direction of the sheaths 9 and 23, respectively. The shape may be, for example, a fixed height, a polygon, an arc, or a combination of a polygon and an arc as shown in FIGS. 5A to 5E, or other shapes. Incidentally, FIG. 5A is a fixed shape, FIG. 5B is a triangle, FIG. 5C is a semi-elliptical circle, FIG. 5D is a trapezoid, and FIG. 5E is a rectangle.

  Referring to FIG. 6, a coaxial cable 25 according to a third embodiment of the present invention will be described by assigning the same reference numerals to the same parts as those of the coaxial cable 1 of the first embodiment described above.

  In the coaxial cable 25 according to the third embodiment, the central conductor 3, the insulator 5, and the outer conductor 7 are configured such as the shape, size, and material of the coaxial cables 1 and 21 according to the first and second embodiments. Is the same, but the sheath 27 is different.

  That is, the sheath 27 of the third embodiment is made of 70% foamed polyethylene, and the thickness of the sheath 27 is such that the outer diameter e of the sheath 27 is 6.0 mmφ. As the sheath 27, the material of the sheath 27 is not limited to the above-mentioned foamed polyethylene, and other foamed resin, and the thickness of the sheath 27 is 1.5 mm or more and 3.0 mm or less. It consists of That is, if the thickness of the sheath 27 is less than 1.5 mm and the thickness of the sheath 27 exceeds 3.0 mm, the impact absorbing effect is not so irritating.

  With the above configuration, in the coaxial cable 25 according to the third embodiment, the sheath 27 adds a flexibility as a foamed structure to improve the shock absorption capability, so that the coaxial cable 25 collides with surrounding structures. Even if vibration impact sound is generated, the shock can be absorbed by the foamed structure of the sheath 27 to reduce the noise.

  Referring to FIGS. 7 and 8, the intensity of noise generated from the conventional general cable 101 was compared with the coaxial cables 1, 2, 25 of the first, second, and third embodiments described above. .

  The noise measurement test method at this time will be explained. As shown in FIG. 7, the test piece 29 of each cable 1, 21, 25, 101 has a central portion 0.5m of a 1 m long cable that vibrates. It is attached to the testing machine 31. That is, the test piece 29 of each cable is gripped and fixed to the fixed end 33 of the vibration tester 31 at one end on the right side in FIG. 7, and the excitation end 35 of the vibration tester 31 is at the other end on the left side in FIG. To be gripped. Each test piece 29 is vibrated up and down by the vibration end 35 reciprocating up and down as indicated by arrows in FIG. The vibration frequency is 20 Hz, for example. However, this vibration frequency can be arbitrarily changed.

  The maximum amplitude of the test piece 29 of each cable is about 10 mm, and an iron plate 37 having a thickness of 1 mm is placed in the vicinity of the maximum amplitude. Further, a noise meter 39 is installed below the iron plate 37.

  Due to the reciprocating motion of the excitation end 35 of the vibration testing machine 31 above and below, the test piece 29 of each cable vibrates up and down like the dotted line and the two-dot chain line in FIG. The generated sound is measured by the sound level meter 39. The measurement frequency was 10 to 100,000 Hz (100 kHz). The measurement results are as shown in FIG.

The structure and material of each sheath 9, 23, 27, 109 of the test piece 29 of each cable used in this noise measurement test are as shown in Table 1. The center conductor 3 is a copper wire having an outer diameter of 0.5 mmφ, the insulator 5 is polyethylene having an outer diameter of 1.6 mmφ, and the outer conductor 7 is a copper wire braid, and has the same structure.

  As can be seen from FIG. 8, the generated sound of the coaxial cables 1, 21, 25 of the first, second and third embodiments, the generated sound of the conventional coaxial cable 101, and the ambient noise level are compared. Then, the noise level becomes maximum when the frequency is 10,000 Hz, and the noise level of the conventional cable is about 80 dB.

  However, at the same frequency, the noise level of the coaxial cable 21 of the second embodiment of the present invention is the lowest at about 30 dB, then the noise level of the coaxial cable 1 of the first embodiment is about 44 dB, and the third level. The noise level of the coaxial cable 25 of the embodiment is about 66 dB, which is lower than the noise level of the conventional coaxial cable 101, and a soundproofing effect is recognized. In particular, in the coaxial cable 21 of the second embodiment, the noise level is lowered to a level close to the surrounding noise level, and it can be seen that the soundproofing effect is great.

  In addition, this invention is not limited to embodiment mentioned above, It can implement in another aspect by making an appropriate change. Although the embodiment of the present invention has been described using the coaxial cable, the present invention is not limited to the coaxial cable and can be applied to other fields. For example, it can be applied to a pair cable. Moreover, it can be applied not only to communication cables but also to, for example, an green cable that transmits a DC signal as a linear body, and a power line that transmits electric power. Furthermore, the present invention can be applied to a linear body used in an environment where noise is not desired, such as a machine control cable. Further, the present invention can be applied not only to a cable having a cross-sectional shape of a linear cylinder but also to a cable member having a cross-sectional shape of a flat plate or a prism.

It is sectional drawing of the coaxial cable of 1st Embodiment of this invention. It is a schematic explanatory drawing which shows the manufacturing process of the coaxial cable of 1st Embodiment. It is sectional drawing of the coaxial cable of 2nd Embodiment of this invention. It is a fragmentary sectional view showing the shape of each projection of the circumference direction of the coaxial cable of the 1st and 2nd embodiments. It is a fragmentary sectional view which shows the shape of each protrusion of the longitudinal direction of the coaxial cable of 1st, 2nd embodiment. It is sectional drawing of the coaxial cable of 3rd Embodiment of this invention. It is a schematic explanatory drawing of the vibration testing machine used in the noise measurement test. It is a graph which shows the measurement result obtained by the noise measurement test. It is sectional drawing of the conventional coaxial cable.

Explanation of symbols

1 Coaxial cable (of the first embodiment)
3 Central conductor 5 Insulator 7 Outer conductor 9 Sheath 9A Sheath thick part 9B Protrusion 9C Protrusion 21 Coaxial cable (of the second embodiment)
23 Sheath 23A Sheath thick part 23B Protrusion 23C Protrusion 25 Coaxial cable (of the third embodiment)
27 Sheath 29 Test piece 31 Vibration testing machine 33 Fixed end 35 Excitation end 37 Iron plate 39 Sound level meter

Claims (5)

In a coaxial cable comprising a center conductor, an insulator coated on the outer periphery of the center conductor, an outer conductor shielded on the outer periphery of the insulator, and a sheath covering the outer periphery of the outer conductor,
The coaxial cable is characterized in that the sheath is made of an outer peripheral shape or material that reduces vibration and impact noise.   2. The coaxial cable according to claim 1, wherein a plurality of protrusions are radially formed on the outer periphery of the sheath at equal intervals in the circumferential direction of the sheath.   The coaxial cable according to claim 2, wherein a cross-sectional shape of the protrusion is any one of a polygon, an arc, or a combination of a polygon and an arc.   4. The coaxial cable according to claim 2, wherein in the longitudinal direction of the sheath, the cross-sectional shape of the protrusion is any one of a constant height, a polygon, an arc, or a combination of a polygon and an arc. The coaxial cable according to claim 1, wherein the sheath is made of foamed polyethylene, and the sheath has a thickness of 1.5 mm or more and 3.0 mm or less.

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