JP2016181657A - Waterproof shield structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a waterproof structure that can secure both the magnetic shield effect and the waterproof performance for the connection portion between a shield cable and a connector with a simple configuration.SOLUTION: A connector boot (shield member) 3 which is formed of conductive rubber and configured by integrating a cylindrical cable-side contact part 31 and a cylindrical connector-side contact part 32 is disposed so as to cover the connection portion S between a shield cable 1 and a connector 2. The inner peripheral surface 31a of the cable-side contact part 31 of the connector boots 3 is brought into close contact with the outer peripheral surface of a shield layer (braided shield 11) of the shielded cable 1, and the inner peripheral surface 32a of the connector-side contact part 32 is brought into close contact with the outer peripheral surface 21a of the connector 1. With such a configuration, both the magnetic shield effect and the waterproof performance for the connection portion J between the shield cable 1 and the connector 2 can be secured, and the number of working steps and the number of parts can be reduced.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a waterproof shield structure at a connection portion between a shielded cable and a connector.

  A shielded cable in which a cable (insulated wire) is covered with a braided shield (shield layer) may be used as a cable for connecting an electronic device or the like for EMC (Electro Magnetic Compatibility). In such a shielded cable, by connecting the braided shield to the ground potential, it is possible to suppress radiation of electromagnetic wave noise and to suppress mixing of electromagnetic wave noise through the cable.

  When a shielded cable is connected to an electronic device via a connector, it is necessary to take EMC measures for the connection portion between the shielded cable and the connector. As the EMC countermeasure structure (shield structure), a structure in which a braided shield and a connector (metal shell) are connected by soldering and the connection portion is covered with a metal foil has been adopted. In this shield structure, when waterproof performance is required, a rubber cover or the like having a waterproof property is attached to the connection portion (the outer peripheral portion of the metal foil).

  As another shield structure, the end of the braided shield of the shield cable is expanded according to the shape of the shield shell (connector), and the expanded portion is covered on the outer periphery of the shield shell, and the expanded portion is secured by caulking. There is a structure of joining to a shield shell (see, for example, Patent Documents 1 and 2).

JP 2012-169497 A JP 2009-153280 A

  By the way, according to the above-described shield structure (prior art), the number of work steps increases. That is, in the former shield structure, an operation of connecting the braided shield and the connector by soldering and an operation of covering the connection portion with the metal foil are required. Also, in the latter shield structure, the end of the braided shield of the shield cable is expanded, and the expanded part is joined to the shield shell by caulking with the expanded part covered on the outer periphery of the shield shell. In either case, the number of work steps is increased. Further, when waterproof performance is required, it is necessary to take measures to ensure waterproofness, and there is a problem that extra man-hours and number of parts are required for ensuring the waterproofness.

  The present invention has been made in consideration of such circumstances, and provides a waterproof shield structure that can ensure both the magnetic shield effect and waterproof performance of the connection portion between the shield cable and the connector with a simple configuration. The purpose is to do.

  The waterproof shield structure of the present invention is a shield structure of a connection portion between a shielded cable and a connector whose outer periphery is covered with a shield layer (for example, a braided shield), which is formed of conductive rubber and has a cylindrical cable side contact. A cylindrical shield member (connector boot) integrally formed with the cylindrical connector side contact portion, and the cylindrical shield member is disposed so as to cover a connection portion between the shield cable and the connector. And the inner peripheral surface of the cable side contact portion of the shield member is in close contact with the outer peripheral surface of the shield layer of the shield cable, and the inner peripheral surface of the connector side contact portion is in close contact with the outer peripheral surface of the connector. Is a technical feature.

  According to the waterproof shield structure of the present invention, the connection portion between the shield cable and the connector is covered with the cylindrical shield member, and the inner peripheral surface of the cable side contact portion of the shield member is the shield layer of the shield cable. Since the inner peripheral surface of the connector side contact portion is in close contact with the outer peripheral surface of the connector, the shield layer of the shield cable and the connector are electrically connected by the shield member, and the shield member It is possible to prevent water from entering the inside. Thereby, it is possible to ensure both the magnetic shielding effect and the waterproof performance of the connecting portion between the shielded cable and the connector.

  Furthermore, since the shield member is formed of conductive rubber (elastic body), the shield cable is provided in each of the cable side contact portion and the connector side contact portion with the diameters of the cable side contact portion and the connector side contact portion expanded. The shield layer and the connector are inserted, and then the cable-side contact portion and the connector-side contact portion are contracted (reduced diameter). Thus, since the shield member can be easily attached to the connection portion between the shield cable and the connector, the number of work steps can be reduced as compared with the above-described conventional technology. In addition, since both the electromagnetic shielding effect and the waterproof performance can be ensured only by mounting the shield member, the work man-hours and the number of parts are not increased for waterproofing measures.

  As described above, according to the waterproof shield structure of the present invention, it is possible to ensure both the magnetic shield effect and the waterproof performance of the connection portion between the shield cable and the connector with a simple configuration, and the number of work steps and parts The score can also be reduced.

  In the waterproof shield structure of the present invention, a protrusion or a protrusion that protrudes inward from the inner peripheral surface may be formed on the inner peripheral surface of the cable-side contact portion of the shield member. By adopting such a structure, the contact area between the cable-side contact portion and the shield layer is increased, and the electrical contact state between the cable-side contact portion and the shield layer becomes better. Can be increased. And since the protrusion or protrusion of the inner peripheral surface of a cable side contact part bites into the outer peripheral part of a shielded cable, it can prevent removal from the connector of a shielded cable.

  In the waterproof shield structure of the present invention, it is preferable to use a shield member made of conductive rubber in which carbon nanotubes are dispersed in silicon rubber. When the shield member is formed of silicon rubber in which carbon nanotubes are dispersed in this way, a shield member having excellent conductivity can be realized, and the electromagnetic shielding effect can be further enhanced.

  According to the waterproof shield structure of the present invention, it is possible to ensure both the magnetic shield effect and the waterproof performance of the connection portion between the shield cable and the connector with a simple configuration.

It is a longitudinal cross-sectional view which shows one Embodiment of the waterproof shield structure of this invention. FIGS. 2A and 2B are a front view and a longitudinal sectional view, respectively, of a connector boot used in the waterproof shield structure of FIG. FIGS. 3A and 3B are a front view and a longitudinal sectional view showing another example of the connector boot, respectively. 4A and 4B are a front view and a longitudinal sectional view showing another example of the connector boot, respectively. It is a perspective view which shows other embodiment of the waterproof shield structure of this invention. It is a figure which shows typically an example of the experimental apparatus used for radiation noise measurement. It is a graph which shows the measurement result of radiation noise.

  Hereinafter, embodiments of the present invention will be described with reference to FIGS. 1 and 2.

  First, the shielded cable 1 includes a braided shield (shield layer) 11 that covers an insulated wire (not shown). The braided shield 11 is formed by weaving a metal wire made of a copper wire or the like into a tube shape, for example. A metal connector (shield shell) 2 is connected to one end of the shield cable 1. Specifically, the end of the insulated wire of the shielded cable 1 (the end of the strand) is connected to a connection terminal (not shown) inside the connector 2, and the connection portion between the shielded cable 1 and the connector 2 A connector boot 3 as a shield member is attached to J.

  The connector boot 3 is a stepped cylindrical member formed of conductive rubber (details will be described later), and includes a cylindrical cable side contact portion 31, a cylindrical connector side contact portion 32, A cylindrical taper portion 33 therebetween is integrally formed.

  The inner diameter (diameter) of the cable side contact portion 31 is set to a dimension smaller than the outer diameter of the shielded cable 1 (outer diameter (diameter) of the braided shield 11) by a predetermined amount. In a state where the shielded cable 1 is fitted, the cable side contact portion 31 and the shielded cable 1 are brought into close contact with each other with a strong contact force.

  The inner diameter of the connector side contact portion 32 is set to a size smaller by a predetermined amount than the outer diameter of the portion of the connector 2 where the connector boot 3 is mounted (hereinafter referred to as the contact portion 21). In a state where the contact portion 21 of the connector 2 is fitted into the connector 32, the connector-side contact portion 32 and the contact portion 21 of the connector 2 are brought into close contact with each other with a strong contact force.

  Here, the conductive rubber constituting the connector boot 3 is obtained by dispersing carbon nanotubes (CNT) and carbon black (CB) as conductive materials in silicon rubber. Carbon composite filler containing ~ 30 wt% and carbon black 90 ~ 70 wt% is uniformly dispersed in silicon rubber, carbon composite filler in a ratio of 10-50 wt% and silicon rubber in a ratio of 90-50 wt% Is included. Moreover, it is preferable that the conductive rubber used in the present embodiment has an electromagnetic wave shielding property at a frequency of 100 MHz in the KEC method of 35 dB or more.

  And the connector boot 3 excellent in electroconductivity is realizable by forming the connector boot 3 with the conductive rubber of such a composition.

  Further, since the connector boot 3 formed of the conductive rubber having such a composition has high stretchability, the inner diameter of the cylindrical cable side contact portion 31 and the inner diameter of the cylindrical connector side contact portion 32 are the same as the connector 2. It is possible to expand the diameter so as to be larger than the maximum outer diameter.

  Next, a procedure for attaching the connector boot 3 to the connection portion J between the shielded cable 1 and the connector 2 will be described.

  First, the diameter of the connector boot 3 is increased using a predetermined jig so that the inner diameter of the cable-side contact portion 31 and each diameter of the connector-side contact portion 32 are larger than the maximum outer diameter of the connector 2. With the diameter expanded as described above, the connector 2 is inserted into the connector boot 3 through the opening 3a on the one end side of the connector boot 3 (opening on the cable side contact portion 31 side), and the contact of the inserted connector 2 is reached. The part 21 is arranged in the connector side contact part 32, and the braided shield 11 of the shielded cable 1 is arranged in the cable side contact part 31. Thereafter, the jig is removed. By removing this jig, the entire connector boot 3 contracts (reduces diameter), the inner peripheral surface 31a of the cable side contact portion 31 comes into close contact with the outer peripheral surface 11a of the braided shield 11 of the shielded cable 1, and the connector side The inner peripheral surface 32 a of the contact portion 32 is in close contact with the outer peripheral surface 21 a of the contact portion 21 of the connector 2. As a result, the connector boot 3 is attached to the connection portion J between the shield cable 1 and the connector 2, and the waterproof shield structure shown in FIG. 1 can be obtained.

  In such a waterproof shield structure, the connector (shield shell) 2 is electrically connected to the housing (ground potential) of the electronic device, and is electrically connected to the connector 2 via the connector boot 3. The braided shield 11 is connected to the ground potential.

  As described above, in the waterproof shield structure of the present embodiment, the braided shield 11 of the shield cable 1 and the connector 2 are electrically connected by the connector boot (conductive rubber) 3 and the shield cable 1 Since the connecting portion J between the connector 2 and the connector 2 is covered with the connector boot (conductive rubber) 3, the magnetic shielding effect of the connecting portion J between the shielded cable 1 and the connector 2 can be ensured. Moreover, the inner peripheral surface 31 a of the cable-side contact portion 31 of the connector boot 3 is in close contact with the outer peripheral surface 11 a of the braided shield 11 of the shielded cable 1, and the inner peripheral surface 32 a of the connector-side contact portion 32 is in contact with the outer peripheral surface 21 a of the connector 2. Since they are in close contact with each other, it is possible to prevent water from entering the inside of the connector boot 3 and to secure the waterproof performance of the connecting portion J between the shielded cable 1 and the connector 2.

  As described above, according to the waterproof shield structure of the present embodiment, both the electromagnetic shielding effect and the waterproof performance are ensured with a simple configuration in which the connector boot 3 is simply attached to the connection portion J between the shield cable 1 and the connector 2. In addition, it is possible to reduce the number of work steps and the number of parts.

<Modification>
Next, another example of the connector boot used in the waterproof shield structure of the present embodiment will be described with reference to FIGS.

  The connector boot 103 shown in FIG. 3 is characterized in that a plurality of circular protrusions 131b.. 131b protruding inward from the inner peripheral surface 131a are formed on the inner peripheral surface 131a of the cable side contact portion 31. There are other configurations, which are the same as those of the connector boot 3 described above.

  If a plurality of protrusions 131b.. 131b are provided on the inner peripheral surface 131a of the cable-side contact portion 31 as in this modification, the contact area between the cable-side contact portion 31 and the braided shield 11 increases. Since the electrical contact state between the cable side contact portion 31 and the braided shield 11 becomes better, the electromagnetic shielding effect can be further enhanced. Moreover, since the plurality of protrusions 131b.. 131b on the inner peripheral surface 131a of the cable side contact portion 31 bite into the outer peripheral portion of the shielded cable 1, it is possible to prevent the shielded cable 1 from being detached from the connector 2.

  The connector boot 203 shown in FIG. 4 has a plurality of protrusions 231b, which extend in the axial direction of the connector boot 203 on the inner peripheral surface 231a of the cable-side contact portion 31 and project inward from the inner peripheral surface 231a. -It has the characteristics in that 231b is formed, and the other configuration is the same as the connector boot 3 described above.

  Thus, even when a plurality of protrusions 231b... 231b are provided on the inner peripheral surface 231a of the cable-side contact portion 31, the contact area between the cable-side contact portion 31 and the braided shield 11 increases, and the cable side Since the electrical contact state between the contact portion 31 and the braided shield 11 becomes better, the electromagnetic shielding effect can be further enhanced. Moreover, since the protrusions 231b,... 231b of the inner peripheral surface 231a of the cable side contact portion 31 bite into the outer peripheral portion of the shielded cable 1, it is possible to prevent the shielded cable 1 from being detached from the connector 2.

  In the above embodiment, the example in which the waterproof shield structure of the present invention is applied to the connection portion between the cylindrical connector (shield shell) 2 and the shield cable 1 has been described. However, the present invention is not limited to this. The waterproof shield structure of the invention can also be applied to a waterproof shield structure at a connection portion between an oval connector (shield shell) and a shield cable.

  Moreover, although the above embodiment demonstrated the example which applied the waterproof shield structure of this invention to the connection part of the shielded cable 1 and the connector 2 in which the shield layer was comprised with the braided shield 11, it is restricted to this In addition, the present invention can also be applied to a waterproof shield structure at a connection portion between a shielded cable having a shield layer using copper foil or aluminum foil and a connector.

<Other embodiments>
In the above embodiment, the waterproof shield structure of the connection portion between one shielded cable 1 and the connector 2 has been described. However, the present invention is not limited to this, for example, three shielded cables and three-phase cables. It can also be applied to a waterproof shield structure at the connection with the connector.

  Specifically, for example, as shown in FIG. 5, a connector boot (conducting material) in which three cylindrical cable side contact portions 531... 531 and one cylindrical connector side contact portion 532 are integrally formed. The connector boot 503 is attached to the connection portion of the three shielded cables 501... 501 and the three-phase connector 502 to secure both the electromagnetic shielding effect and the waterproof performance. You may do it. In the waterproof shield structure shown in FIG. 5, as in the above-described embodiment, the conductive rubber constituting the connector boot 503 is made of carbon nanotubes (CNT) and carbon black (CB) as conductive materials. It is preferable to use a material dispersed in silicon rubber.

<Experimental example>
First, the measurement object S used in the experiment will be described.

  In the waterproof shield structure shown in FIG. 1, the shield cable 1 has a diameter of 10.5 mm, a length of 500 mm, and the contact portion 21 of the connector 2 has a diameter of 18 mm.

  In the connector boot 3, 10 to 50% by weight of a carbon composite filler containing 10 to 30% by weight of carbon nanotubes and 90 to 70% by weight of carbon black was uniformly dispersed in 90 to 50% by weight of silicon rubber. It was produced using a thing (conductive rubber). The dimensions of the connector boot 3 are as follows: the inner diameter of the cable side contact portion 31 is 9.4 mm, the inner diameter of the connector side contact portion 31 is 17.5 mm, and the wall thickness is 2 mm (the connector boot 3 is attached to the shielded cable 1 and the connector 2 Dimension before).

  A device under test S was prepared by attaching such a connector boot 3 to the connection portion J between the shielded cable 1 and the connector 2 (an example of the waterproof shield structure in FIG. 1).

  With respect to this measurement object S, emission noise was measured according to CISPR25. A schematic configuration of the experimental apparatus is shown in FIG.

  In the experimental apparatus shown in FIG. 6 (apparatus conforming to CISPR25), a measurement table 302 is arranged in an anechoic chamber 301. As the measurement table 302, a copper plate 321 is disposed at a height of 900 mm from the darkroom floor, and a rectangular table (made of foamed polystyrene: thickness 50 mm) 322 is placed on the copper plate 321 (grounded to the darkroom floor). A thing was used. An object to be measured S (with the connector boot 3 attached to the connecting portion between the shielded cable 1 and the connector 2) is placed on the table 322 at a position 100 mm from the edge of the copper plate 321 and parallel to the edge of the copper plate 321. Placed on. The comb generator 303 was disposed on one end side (connector side) of the device under test S in a state covered with a conductive cloth, and a signal generated by the comb generator 303 was transmitted to the device under test S.

  Then, a rod antenna and an antenna (bilog antenna) 304 are installed on the side of the object to be measured S (distance = 1000 mm) at a height h = 1000 mm, and noise (electromagnetic waves) emitted from the object to be measured S ) And the received signal was subjected to frequency analysis using a spectrum analyzer (not shown). The results (experimental results of the example) are shown in FIG. Further, as a comparative example, a case where a connector boot was not attached to the connection portion between the shielded cable 1 and the connector 2 was measured under the same conditions. The result is shown in FIG.

  From the results shown in FIG. 7, the example (with the connector boot 3 attached) has less radiation noise than the comparative example (without the connector boot 3 attached), that is, the electromagnetic shielding effect is higher. I understand that. In particular, in the high frequency range, it can be seen that the example has a higher electromagnetic shielding effect of about 40 dB than the comparative example. From these results, it was confirmed that a sufficient electromagnetic shielding effect can be obtained by attaching the connector boot 3 to the connection portion between the shielded cable 1 and the connector 2.

  In FIG. 7, the graph is interrupted at 30 MHz because the antenna for detecting electromagnetic waves is changed at 30 MHz.

DESCRIPTION OF SYMBOLS 1 Shield cable 11 Braided shield 11a Outer surface of braided shield 2 Connector (made of metal)
21 Contact portion of connector 21a Outer peripheral surface of contact portion 3 Connector boot (shielding member made of conductive rubber)
31 Cable side contact portion 31a Inner peripheral surface of cable side contact portion 32 Connector side contact portion 32a Inner peripheral surface of connector side contact portion J Connection portion between shield cable and connector

Claims (3)

It is a waterproof shield structure of the connection part between the shield cable and the connector whose outer periphery is covered with a shield layer,
A cylindrical shield member formed of conductive rubber and integrally formed with a cylindrical cable side contact portion and a cylindrical connector side contact portion,
The cylindrical shield member is disposed so as to cover the connection portion between the shield cable and the connector, and the inner peripheral surface of the cable-side contact portion of the shield member is in close contact with the outer peripheral surface of the shield layer of the shield cable. And the inner peripheral surface of the said connector side contact part is closely_contact | adhered to the outer peripheral surface of the said connector, The waterproof shield structure characterized by the above-mentioned. The waterproof shield structure according to claim 1,
A waterproof shield structure characterized in that a protrusion or a protrusion protruding inward from the inner peripheral surface is formed on the inner peripheral surface of the cylindrical cable side contact portion of the shield member. In the shield structure according to claim 1 or 2,
A waterproof shield structure, wherein the shield member is made of conductive rubber in which carbon nanotubes are dispersed in silicon rubber.

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