JP2024140902A - Power cable connection - Google Patents

Abstract

To provide a power cable connection portion that can suppress a sheath from shifting relative to a shielding layer.SOLUTION: A power cable connection portion includes a plurality of power cables each having a shielding layer and a sheath covering an outer periphery of the shielding layer, a rubber spacer attached to an outer periphery of the sheath of each of the plurality of power cables to bundle the plurality of power cables, a bracket holding the outer periphery of the rubber spacer so as to fasten the rubber spacer, and a cold shrink tube covering the outer periphery of the sheath of each of the plurality of power cables at a position closer to the tip of each of the plurality of power cables than the rubber spacer, and an end face of the cold shrink tube contacts an end face of the rubber spacer, and the outer peripheries of adjacent cold shrink tubes contact each other.SELECTED DRAWING: Figure 1

Description

This disclosure relates to a connection part for a power cable.

Patent Document 1 discloses a power cable terminal portion that includes a power cable having a shielding layer and a sheath, a spring ring, a shrink tube, an intervening tape, and a fixing bracket. The spring ring is wrapped around the outer peripheral surface of the sheath so as to bite into it. The shrink tube covers the spring ring and the outer peripheral surface of the sheath together. A bulge is formed in the shrink tube by the spring ring. The intervening tape is wrapped around the outer peripheral surface of the shrink tube at a position farther from the tip of the power cable than the bulge. The fixing bracket has two divided pieces that sandwich the outer peripheral surface of the intervening tape.

Japanese Patent Application Publication No. 10-210642 Japanese Patent Application Publication No. 8-340627

Due to the manufacturing process, the sheath has residual tensile strain along the length of the power cable. This residual strain is released by the thermal effects of heat cycles, such as changes in outside temperature and current flow. When the residual strain is released, the sheath contracts along the length of the sheath. This contraction of the sheath is called shrink back. When the sheath contracts, it shifts relative to the shielding layer. The shielding layer may be damaged by the load applied by the contraction of the sheath.

In Patent Document 1, a spring ring that is inserted into the sheath and a bulge in the shrink tube formed by the spring ring prevent the sheath from shifting relative to the shielding layer.

One of the objectives of this disclosure is to provide a power cable connection that can effectively prevent the sheath from shifting relative to the shielding layer.

The connection portion of the power cable of the present disclosure includes:
A plurality of power cables each having a shielding layer and a sheath covering an outer periphery of the shielding layer;
a rubber spacer attached to an outer peripheral surface of the sheath of each of the plurality of power cables to bundle the plurality of power cables;
a bracket that grips an outer peripheral surface of the rubber spacer so as to fasten the rubber spacer;
a cold shrink tube covering an outer circumferential surface of the sheath of each of the plurality of power cables at a position closer to a tip of each of the plurality of power cables than the rubber spacer,
an end surface of the cold shrink tube contacts an end surface of the rubber spacer;
The outer circumferential surfaces of the adjacent cold shrink tubes are in contact with each other.

The connection portion of the power cable disclosed herein can effectively prevent the sheath from shifting relative to the shielding layer.

FIG. 1 is a schematic front view showing a power cable according to an embodiment. FIG. 2 is a cross-sectional view taken along line II-II of FIG. FIG. 3 is a cross-sectional view taken along line III-III of FIG. FIG. 4 is a cross-sectional view taken along line IV-IV of FIG.

Description of the embodiments of the present disclosure
First, the embodiments of the present disclosure will be listed and described.

(1) A connection portion of a power cable according to one embodiment of the present disclosure includes:
A plurality of power cables each having a shielding layer and a sheath covering an outer periphery of the shielding layer;
a rubber spacer attached to an outer peripheral surface of the sheath of each of the plurality of power cables to bundle the plurality of power cables;
a bracket that grips an outer peripheral surface of the rubber spacer so as to fasten the rubber spacer;
a cold shrink tube covering an outer circumferential surface of the sheath of each of the plurality of power cables at a position closer to a tip of each of the plurality of power cables than the rubber spacer,
an end surface of the cold shrink tube contacts an end surface of the rubber spacer;
The outer circumferential surfaces of the adjacent cold shrink tubes are in contact with each other.

In the connection part of the power cable in (1) above, the end face of each cold shrink tube is in contact with the end face of the rubber spacer, and the outer surfaces of adjacent cold shrink tubes are in contact with each other, which effectively prevents the sheath from shifting relative to the shielding layer.

(2) In the connection part of the power cable of (1) above,
The length along which the outer circumferential surfaces of adjacent cold-shrinkable tubes are in contact with each other along the axis of the cold-shrinkable tube may be 10% or more of the length along the axis of the cold-shrinkable tube.

The connection part of the power cable in (2) above can more effectively prevent the sheath from shifting relative to the shielding layer, compared to a case where the length over which the outer surfaces of adjacent cold-shrinkable tubes are in contact with each other along the axis of the cold-shrinkable tube is less than 10% of the length along the axis of the cold-shrinkable tube.

(3) In the connection part of the power cable described in (1) or (2),
The length over which the outer circumferential surfaces of adjacent cold-shrinkable tubes are in contact with each other around the axis of the cold-shrinkable tube may be 3% or more of the circumferential length of the cold-shrinkable tube.

The length over which the outer surfaces of adjacent cold-shrinkable tubes are in contact with each other along the axis of the cold-shrinkable tube is 3% or more of the circumference of the cold-shrinkable tube, so that the outer surfaces of adjacent cold-shrinkable tubes press against each other and come into contact. Therefore, the connection part of the power cable in (3) above can more effectively prevent the sheath from shifting relative to the shielding layer.

Details of the embodiments of the present disclosure
The details of the connection part of the power cable of the present disclosure will be described below. The same reference numerals in the drawings indicate the same or corresponding parts. The size of the members shown in each drawing is expressed for the purpose of clarifying the description, and does not necessarily represent the actual size.

<<Embodiment>>
[Power cable connection]
A power cable connection part 1 according to an embodiment will be described with reference to Figs. 1 to 4. As shown in Fig. 1, the power cable connection part 1 includes a plurality of power cables 2, a rubber spacer 3, a bracket 4, and a plurality of cold shrink tubes 5. Each power cable 2 includes a shielding layer 25 and a sheath 26 covering the outer periphery of the shielding layer 25. The rubber spacer 3 is attached to the outer periphery of the sheath 26 of each power cable 2 to bundle the plurality of power cables 2. The bracket 4 holds the outer periphery of the rubber spacer 3 so as to tighten the rubber spacer 3. Each cold shrink tube 5 covers the outer periphery of the sheath 26 at a specific position. One of the features of the power cable connection part 1 is that each cold shrink tube 5 has an end face that is in contact with the end face of the rubber spacer 3. Hereinafter, a case in which the power cable connection part 1 is a terminal connection part of the power cable will be described as an example. In the following description, the positions of the rubber spacer 3, the bracket 4, and each cold shrink tube 5 close to the tip of the power cable 2 are referred to as first positions, and the positions farther from the tip of the power cable 2 are referred to as second positions.

[Power cable]
Each power cable 2 includes, in order from the inner circumference, a conductor, an inner semiconductive layer, an insulator, an outer semiconductive layer, a shielding layer 25, and a sheath 26. The conductor, the inner semiconductive layer, the insulator, and the outer semiconductive layer are omitted from the illustration. Each power cable 2 may not include the inner semiconductive layer and the outer semiconductive layer as necessary. The tip of each power cable 2 is stripped in steps. By being stripped in steps, the conductor and the insulator are exposed from the sheath 26. The exposed conductor is covered with a rubber molded part (not shown) from the end of the sheath 26. The number of power cables 2 in this example is three. That is, the connection portion 1 of the power cable includes a three-core (three-phase) power cable 2. The material of the sheath 26 is, for example, polyethylene resin or polyvinyl chloride resin. The polyethylene resin sheath 26 is prone to shrink back. However, even if the sheath 26 is prone to shrink-back, the rubber spacer 3, bracket 4, and each cold shrink tube 5 described later can effectively prevent the sheath 26 from shifting relative to the shielding layer 25. The power cables 2 and rubber molded parts in this example can be made of known power cables and rubber molded parts. For convenience of explanation, the inside of the sheath 26 is not shown in Figure 3.

[Rubber spacer]
As shown in Fig. 3, the rubber spacer 3 is attached to the outer peripheral surface of the sheath 26 of each power cable 2 to bundle the multiple power cables 2. The rubber spacer 3 in this example bundles three-core (three-phase) power cables 2 together. The rubber spacer 3 is provided at a position farther from the tip of the power cable 2 than the rubber molded part. The rubber spacer 3 is fastened by a bracket 4, which will be described later. Therefore, the rubber spacer 3 applies a predetermined surface pressure to the outer peripheral surface of each sheath 26. Therefore, the rubber spacer 3 is effectively prevented from shifting relative to each sheath 26. The rubber spacer 3 can be formed of a known rubber spacer.

The rubber spacer 3 is a cylindrical body. As shown in FIG. 4, the rubber spacer 3 has a first end surface 31 at a first position and a second end surface 32 at a second position. As shown in FIG. 3, the rubber spacer 3 has a plurality of storage holes 35 and a plurality of cutouts 36. Each storage hole 35 stores a power cable 2. The number of storage holes 35 is the same as the number of power cables 2. In this example, the number of storage holes 35 is three. Each storage hole 35 is formed along the direction along the axis of the rubber spacer 3. Each storage hole 35 penetrates the first end surface 31 and the second end surface 32. Each cutout 36 is an opening for fitting each power cable 2 into the storage hole 35 from the outside of the rubber spacer 3. The number of cutouts 36 is the same as the number of storage holes 35. In this example, the number of cutouts 36 is three. Each cutout 36 is formed in series with the storage hole 35.

The rubber spacer 3 may further have a first flange 33 as shown in Figs. 1, 2, and 4. The first flange 33 is formed on the outer periphery of the end of the rubber spacer 3 at the first position. The first flange 33 covers the first end faces 411a and 421a described later as shown in Figs. 2 and 4. The first flange 33 can also be prevented from shifting relative to each sheath 26 by abutting and stopping the first flange 33 against the first end faces 411a and 421a. Therefore, the rubber spacer 3 is likely to effectively prevent each sheath 26 from shifting relative to the shielding layer 25. The rubber spacer 3 may further have a second flange 34 as shown in Figs. 1 and 4. The second flange 34 is formed on the outer periphery of the end of the rubber spacer 3 at the second position. The rubber spacer 3 may not have the second flange 34. As shown in FIG. 4, the second flange 34 covers the second end faces 411b and 421b described below. The first flange 33 and the second flange 34 prevent the rubber spacer 3 from shifting relative to the bracket 4 in either the direction toward the tip of the power cable 2 or the direction away from the tip.

[bracket]
The bracket 4 attaches a plurality of power cables 2 shown in Fig. 1 to an attachment target. As shown in Fig. 3, the bracket 4 grips the outer peripheral surface of the rubber spacer 3. The bracket 4 tightens the rubber spacer 3. The rubber spacer 3 tightened by the bracket 4 applies a predetermined surface pressure to each sheath 26. The material of the bracket 4 is, for example, steel, cast iron, aluminum, or an aluminum alloy. The bracket 4 can be configured as a known bracket. The bracket 4 in this example includes a main body 41, a pressing member 42, and a tightening member 43.

(Main unit)
The main body 41 is for fixing the bracket 4 itself to the mounting object. The main body 41 includes a semicircular curved portion 411, flange portions 412 formed on both sides of the curved portion 411, and a fixing base 413 formed on the outer surface of the curved portion 411. The curved portion 411 is used to place the rubber spacer 3 between the curved portion 411 and a curved portion 421 of the pressing member 42 described later. The curved portion 411 surrounds a part of the outer circumferential surface of the rubber spacer 3. The curved portion 411 has a first end surface 411a at a first position and a second end surface 411b at a second position as shown in FIG. 4. The first end surface 411a is covered by the first flange portion 33 as shown in FIG. 2 and FIG. 4. The second end surface 411b is covered by the second flange portion 34. The two flange portions 412 are used to fix the pressing member 42 to the main body 41 as shown in FIG. 3. Each flange portion 412 is formed with a through hole 412h through which a fastening member 43 described later is inserted. The fixing base 413 fixes the main body 41 to an attachment object. The attachment object is, for example, an arm. The fixing base 413 is formed with a through hole through which a fastening member for fixing the main body 41 to the attachment object is inserted. The fastening member and the through hole are omitted in the illustration. The fastening member can be a bolt.

(Pressing member)
The pressing member 42 sandwiches the rubber spacer 3 together with the main body 41. The pressing member 42 faces the inner surfaces of the curved portion 411 and the flange portion 412 of the main body 41. The rubber spacer 3 is disposed between the pressing member 42 and the main body 41. The pressing member 42 includes a semicircular curved portion 421 and flange portions 422 formed on both sides of the curved portion 421. The curved portion 421 surrounds a part of the outer peripheral surface of the rubber spacer 3. As shown in FIG. 4, the curved portion 421 has a first end surface 421a at a first position and a second end surface 421b at a second position. The second end surface 421b is covered by the second flange portion 34. As shown in FIG. 3, each flange portion 422 is fixed to each flange portion 412 of the main body 41 by a fastening member 43. Each flange portion 422 has a through hole 422h through which the fastening member 43 is inserted.

(Fastening member)
The fastening member 43 fastens the flange portion 412 of the main body 41 and the flange portion 422 of the pressing member 42 together to fix the main body 41 and the pressing member 42. The fastening member 43 clamps the curved portion 411 of the main body 41 and the curved portion 421 of the pressing member 42 so as to fasten the rubber spacer 3 disposed between the curved portions 411, 421. A bolt can be used as the fastening member 43.

[Cold shrink tube]
As shown in Figs. 1 and 4, each cold shrink tube 5 covers the outer circumferential surface of each sheath 26 at a position closer to the tip of each power cable 2 than the bracket 4. For convenience of explanation, Fig. 4 shows only the cold shrink tube 5 in cross section. Each cold shrink tube 5 in this example has a single-layer structure as shown in Fig. 2. For convenience of explanation, the inside of each cold shrink tube 5 is not shown in Fig. 2. Each cold shrink tube 5 sufficiently tightens the outer circumferential surface of each sheath 26, so that it does not slip relative to each sheath 26 due to friction. The material of the cold shrink tube 5 is, for example, ethylene propylene rubber, chloroprene rubber, butylene rubber, silicon rubber, natural rubber, fluororubber, or silicone-modified ethylene propylene rubber. The cold shrink tube 5 can be formed of a known cold shrink tube. For example, the outer layer structure of JP-A-11-98674 can be used as the known cold shrink tube.

As shown in FIG. 4, each cold shrink tube 5 has a first end face 51 in a first position and a second end face 52 in a second position. Each second end face 52 is in contact with the first end face 31. The outer circumferential surfaces of adjacent cold shrink tubes 5 are in contact with each other. Each second end face 52 is in contact with the first end face 31, and the outer circumferential surfaces of adjacent cold shrink tubes 5 are in contact with each other, thereby effectively preventing each sheath 26 from shifting relative to each shielding layer 25.

As shown in FIG. 4, the length of contact between the outer circumferential surfaces of adjacent cold shrink tubes 5 along the axis of the cold shrink tube 5 is called the first contact length L1. The first contact length L1 is, for example, 10% or more of the length along the axis of the cold shrink tube 5. When the first contact length L1 is 10% or more of the length along the axis of the cold shrink tube 5, it is easier to effectively suppress the displacement of each sheath 26 with respect to each shielding layer 25 compared to when the first contact length L1 is less than 10% of the length along the axis of the cold shrink tube 5. The first contact length L1 may further be 15% or more of the length along the axis of the cold shrink tube 5, and may particularly be 20% or more of the length along the axis of the cold shrink tube 5. The interval between adjacent power cables 2 becomes wider toward the tip of the multiple power cables 2. Therefore, the first contact length L1 is, for example, 50% or less of the length along the axis of the cold shrink tube 5.

2, the length of contact between the outer circumferential surfaces of adjacent cold shrink tubes 5 along the axis of the cold shrink tube 5 is called the second contact length L2. The second contact length L2 is, for example, 3% or more of the circumference of the cold shrink tube 5. When the second contact length L2 is 3% or more of the circumference of the cold shrink tube 5, the outer circumferential surfaces of adjacent cold shrink tubes 5 press against each other and contact each other, compared to when the second contact length L2 is less than 3% of the circumference of the cold shrink tube 5. Therefore, when the second contact length L2 is 3% or more of the circumference of the cold shrink tube 5, the sheath 26 is more effectively prevented from shifting relative to each shielding layer 25, compared to when the second contact length L2 is less than 3% of the circumference of the cold shrink tube 5. The second contact length L2 may further be 5% or more of the circumference of the cold shrink tube 5, or may be particularly 10% or more of the circumference of the cold shrink tube 5. Although it depends on the diameter of each power cable 2, the second contact length L2 is, for example, 20% or less of the circumference of the cold shrink tube 5.

Each cold shrink tube 5 can be produced as follows. Each cold shrink tube 5 in an expanded state is placed on the outer periphery of each sheath 26. The diameter of each cold shrink tube 5 can be expanded by a known diameter expanding tube. For example, the core member of JP 11-98674 A can be used as a known diameter expanding tube. The core member is disassembled by fraying into a string shape. By gradually disassembling and pulling out the diameter expanding tube placed inside each cold shrink tube 5 in an expanded state, the diameter of each cold shrink tube 5 can be reduced and attached to the outer periphery of each sheath 26.

The present invention is not limited to these examples, but is indicated by the claims, and is intended to include all modifications within the meaning and scope of the claims.

REFERENCE SIGNS LIST 1 Power cable connection portion 2 Power cable 25 Shielding layer 26 Sheath 3 Rubber spacer 31 First end surface 32 Second end surface 33 First flange portion 34 Second flange portion 35 Storage hole 36 Notch portion 4 Bracket 41 Main body 411 Curved portion 411a First end surface 411b Second end surface 412 Flange portion 412h Through hole 413 Fixing base 42 Pressing member 421 Curved portion 421a First end surface 421b Second end surface 422 Flange portion 422h Through hole 43 Fastening member 5 Cold shrink tube 51 First end surface 52 Second end surface L1 First contact length L2 Second contact length

Claims (3)

A plurality of power cables each having a shielding layer and a sheath covering an outer periphery of the shielding layer;
a rubber spacer attached to an outer peripheral surface of the sheath of each of the plurality of power cables to bundle the plurality of power cables;
a bracket that grips an outer peripheral surface of the rubber spacer so as to fasten the rubber spacer;
a cold shrink tube covering an outer circumferential surface of the sheath of each of the plurality of power cables at a position closer to a tip of each of the plurality of power cables than the rubber spacer,
an end surface of the cold shrink tube contacts an end surface of the rubber spacer;
The outer circumferential surfaces of the adjacent cold shrink tubes are in contact with each other.
Power cable connection. The power cable connection according to claim 1, wherein the length over which the outer circumferential surfaces of adjacent cold shrink tubes are in contact with each other along the axis of the cold shrink tube is 10% or more of the length along the axis of the cold shrink tube. The power cable connection according to claim 1 or 2, wherein the length over which the outer circumferential surfaces of adjacent cold shrink tubes are in contact with each other along the axis of the cold shrink tube is 3% or more of the circumference of the cold shrink tube.

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