Cold shrink tube, cable connection structure, and cable connection method

Abstract

To provide a technique that enables good coating processing with a cold shrink tube to be performed even when the areas to be coated include areas of different radial sizes.SOLUTION: A cold shrink tube includes a tubular member formed from an insulating and elastic material, and is configured such that the tubular member expands in diameter when a core portion is attached inside the tube, and the tubular member contracts in diameter when the core member is pulled out from inside the tube. The tubular member includes a thick-diameter portion and a thin-diameter portion with different tube diameters when in a non-expanded state in which the core member is not attached.SELECTED DRAWING: Figure 4

Description

Technical Field

[0001] The present disclosure relates to a room temperature shrinkable tube, a cable connection structure, and a cable connection method.

Background Art

[0002] Connection points between power cables, connection points between power cables and device terminal parts, etc. are generally subjected to a coating process for waterproofing, moistureproofing, electrical insulation, mechanical protection, etc. The coating process may be performed using a room temperature shrinkable tube having better workability than a heat shrinkable tube.

[0003] As a room temperature shrinkable tube, there is known one having a linear cylindrical tubular member and configured to adhere and coat a connection point by utilizing the shrinking force of the tubular member generated by pulling out and removing a core member mounted inside the tube (see, for example, Patent Document 1, etc.).

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] In addition to the locations where conductor connection tubes (sleeves) and insulating tubes (insulating cylinders) necessary for cable connection are arranged, the locations where the sheath of the power cable is exposed so as to be continuous with the said locations are also included in the locations to be coated. That is, the locations to be coated include locations with different radial sizes mixed therein. Therefore, if the tubular member of the room temperature shrinkable tube is in a straight cylindrical shape, there is a possibility that a good coating process cannot necessarily be performed. For example, when performing a coating process with a room temperature shrinkable tube adapted to the small diameter portion, there is a possibility that the surface pressure on the large diameter portion becomes excessive after the shrinkage of the tubular member. Further, for example, when performing a coating process with a room temperature shrinkable tube adapted to the large diameter portion, there is a possibility that the restraining force on the sheath, which is the small diameter portion, becomes insufficient even after the shrinkage of the tubular member. In particular, regarding the sheath, since shrinkage over time due to the shrink-back phenomenon can occur, it is preferable to obtain a sufficient and reliable restraining force even under such circumstances.

[0006] The present disclosure provides a technique capable of favorably performing a coating process with a room temperature shrinkable tube even when locations with different radial sizes are mixed as the locations to be coated.

Means for Solving the Problems

[0007] According to one aspect of the present disclosure, There is provided a room temperature shrinkable tube having a tubular member formed of a material having insulation and elasticity, wherein the tubular member is configured to expand in diameter by mounting a core member into the tube and to contract in diameter by pulling out the core member from the tube, The tubular member has a thick diameter portion and a thin diameter portion having different tube diameters from each other in a non-expanded diameter state in which the core member is not mounted. A room temperature shrinkable tube is provided.

Advantages of the Invention

[0008] According to the present disclosure, even when locations with different radial sizes are mixed as the locations to be coated, a coating process with a room temperature shrinkable tube can be favorably performed.

Brief Description of the Drawings

[0009]

Figure 1

Figure 2

Figure 3

Figure 4

Modes for Carrying Out the Invention

[0010] [Description of Embodiments of the Present Disclosure] <Findings Obtained by the Inventor> First, the findings obtained by the inventor of the present application will be described.

[0011] Power cables for power transmission applications are used by being connected to other power cables by a straight connection part or a branch connection part, or by being connected to a device terminal part such as a directly connected T-type terminal by a terminal connection part. That is, a power cable uses another power cable or a device terminal part as a connection partner and is used by being connected to that connection partner. Here, the structure for connecting the power cable and the connection partner is referred to as a "cable connection structure".

[0012] FIG. 1 is an explanatory diagram showing an example of a cross-sectional configuration of a cable connection structure by a straight connection part. The cable connection structure in the legend is for linearly connecting the same type of power cables 1 to each other. Each power cable 1 is composed of a conductor 1a covered by a sheath 1b. However, at the connection end side, it is gradually peeled off step by step from the axial tip of the conductor 1a in the opposite direction (so-called "step peeling"). That is, between the exposed portion of the conductor 1a at the tip and the covered portion by the sheath 1b, there is a step peeling portion 1c where the cable internal semiconductor layer, the cable insulation layer, the cable external semiconductor layer, and the cable metal shielding layer are sequentially exposed. Then, the exposed portion of the conductor 1a of each power cable 1 is surrounded by a conductor connection tube 2, and the conductor connection tube 2 and the step peeling portion 1c of each power cable 1 are surrounded by an insulating cylinder 3. Further, an ACP tape (semi-conductive fusion tape) 4, a flat braided wire 5, a grounding spring 6, a semi-conductive tape 7, etc. are arranged as required, and the connection state of each power cable 1 is established by these. Note that these components are based on known technologies, and further explanations are omitted here.

[0013] In such a cable connection structure, a covering process is performed on the connection portion between the power cables 1. The covering process is performed using normal temperature shrinkable tubes 8 and 10. Specifically, the outer peripheral side of the insulating cylinder 3 is covered by the normal temperature shrinkable tube 8. Further, the outer peripheral side is covered by the normal temperature shrinkable tube 10 over the range from the outer peripheral portion of the normal temperature shrinkable tube 8 to the exposed portion of the sheath 1b continuous therewith. Note that the vicinity of the edge of the normal temperature shrinkable tube 10 is sealed by a sealing member 9 such as an adhesive polyethylene tape.

[0014] When performing the covering process with the normal temperature shrinkable tubes 8 and 10, particularly for the covering portion by the normal temperature shrinkable tube 10, portions with different radial sizes are mixed. For example, the outer peripheral portion of the normal temperature shrinkable tube 8 covering the insulating cylinder 3 and the exposed portion of the sheath 1b have different radial sizes. Therefore, the inventor of the present application has obtained the knowledge that if a tubular member with a straight cylindrical shape is used as the normal temperature shrinkable tube 10, there is a possibility that a good covering process cannot be necessarily performed.

[0015] Specifically, for example, if the covering process is performed using a heat-shrinkable tube with a diameter dimension adjusted to the exposed portion of the sheath 1b, which is a small-diameter portion, there is a risk that the surface pressure on the outer peripheral portions of the insulating cylinder 3, which is a large-diameter portion, and the heat-shrinkable tube 8 will become excessive after the shrinkage of the tubular member. Further, for example, if the covering process is performed using a heat-shrinkable tube with a diameter dimension adjusted to the outer peripheral portions of the insulating cylinder 3, which is a large-diameter portion, and the heat-shrinkable tube 8, there is a risk that the restraining force on the exposed portion of the sheath 1b, which is a small-diameter portion, will be insufficient even after the shrinkage of the tubular member. In particular, with respect to the sheath 1b, since shrinkage over time due to the shrink-back phenomenon can occur, it is preferable to ensure that a sufficient and reliable restraining force can be obtained even under such circumstances.

[0016] That is, the inventor of the present application has found a new problem regarding the heat-shrinkable tube 10 that covers a covering portion where portions having different radial sizes are mixed. Specifically, if the large-diameter portion side is too thin, there is a risk that the surface pressure will become excessive, and if the small-diameter portion side is too thick, there is a risk that the restraining force on the sheath 1b will be insufficient.

[0017] Here, the problem found by the inventor of the present application has been specifically described by taking the cable connection structure using a straight connection portion as an example. However, the same problem can also occur in the cable connection structure using a branch connection portion. Furthermore, the same problem can occur not only when another power cable is the connection partner but also in the cable connection structure when a device terminal portion such as a device-direct T-type terminal is the connection partner. This is because, in any case, different-sized portions in the radial direction can be mixed in the covering portion by the heat-shrinkable tube.

[0018] In order to solve the new problems described above, the inventor of the present application has devised a heat-shrinkable tube, a cable connection structure, and a cable connection method, which will be described in the following embodiment.

[0019] <Embodiments of the Present Disclosure> Next, the embodiments of the present disclosure will be listed and described.

[0020] [1] The room temperature shrinkable tube according to one aspect of the present disclosure has a tubular member formed of a material having insulation and elasticity, and the tubular member expands in diameter by attaching a core member into the tube, and is configured to shrink in diameter by pulling out the core member from the tube. The room temperature shrinkable tube is such that, in a non-expanded diameter state where the core member is not attached, the tubular member has a thick diameter portion and a thin diameter portion with different tube diameters from each other. According to this configuration, even when there are portions with different radial sizes as the portions to be coated, the coating process with the room temperature shrinkable tube can be performed well.

[0021] [2] In the room temperature shrinkable tube according to [1] above, the tubular member has a stepped portion connecting the thick diameter portion and the thin diameter portion, and at least one of the cross-sectional shapes at the continuous portion with the thick diameter portion or the continuous portion with the thin diameter portion of the stepped portion is formed in an R shape. According to this configuration, for the tubular member, deterioration, damage, etc. caused by stress concentration accompanied by elastic deformation can be prevented in advance.

[0022] [3] In the room temperature shrinkable tube according to [1] above, the tubular member has a stepped portion connecting the thick diameter portion and the thin diameter portion, the stepped portion has a cross-sectional shape at the continuous portion with the thick diameter portion and the continuous portion with the thin diameter portion formed in a rectangular shape, and has a tapered shape portion whose tube diameter changes along the tube axis direction between the respective continuous portions. According to this configuration, for the tubular member, generation of a load due to not following the shape of the portion to be sealed can be suppressed, and deterioration, damage, etc. caused by the load can be prevented in advance.

[0023] [4] In the room temperature shrinkable tube according to any one of [1] to [3] above, the length of the thin diameter portion in the tube axis direction is formed to be 50 mm or more and 250 mm or less. According to this configuration, it is possible to obtain sufficient restraint force by securing the wrap length while suppressing the deterioration of the workability of the coating process.

[0024] [5] A cable connection structure according to another aspect of the present disclosure is A cable connection structure that connects a cable in which a conductor is covered with a sheath and a connection partner of the cable, Comprising a normal temperature shrinkable tube arranged to cover the connection portion between the cable and the connection partner, The normal temperature shrinkable tube has a tubular member formed of a material having insulation and elasticity. The tubular member is configured to expand in diameter when a core member is mounted inside the tube, and to contract in diameter when the core member is pulled out from inside the tube. The tubular member has a thick diameter portion and a thin diameter portion with different tube diameters in a non-expanded diameter state where the core member is not mounted, and is arranged such that the contracted thin diameter portion is in a state of being pressure-bonded to the outer peripheral surface of the sheath. According to this configuration, even when there are portions with different radial sizes as the portions to be coated, the coating process with the normal temperature shrinkable tube can be performed well.

[0025] [6] A cable connection method according to still another aspect of the present disclosure is A cable connection method used when connecting a cable in which a conductor is covered with a sheath and a connection partner of the cable, A procedure of preparing a normal temperature shrinkable tube having a configuration in which a tubular member formed of a material having insulation and elasticity has a thick diameter portion and a thin diameter portion with different tube diameters in a non-expanded diameter state where the core member is not mounted, while the tubular member is in an expanded diameter state when a core member is mounted inside the tube, A procedure of arranging the normal temperature shrinkable tube so as to enclose the portion to be sealed at the connection portion between the cable and the connection partner inside the tube of the tubular member, A procedure of pulling out the core member from inside the tubular member in the normal temperature shrinkable tube to reduce the diameter of the tubular member, and covering the portion to be sealed with the tubular member in a state where the reduced-diameter small-diameter portion is crimped to the outer peripheral surface of the sheath in the cable. is provided. According to this configuration, even when there are portions with different radial sizes as the portions to be coated, the coating process with the normal temperature shrinkable tube can be performed well.

[0026] [Details of Embodiments of the Present Disclosure] Next, embodiments of the present disclosure will be described below with reference to the drawings. It should be noted that the present disclosure is not limited to these examples, and is shown by the claims, and is intended to include all modifications within the meaning and scope equivalent to the claims.

[0027] [One Embodiment of the Present Disclosure] Here, as an embodiment of the present disclosure, a case of linearly connecting the same type of power cables 1 to each other is taken as an example.

[0028] The cable connection structure and the cable connection method according to the present embodiment have a great feature in the normal temperature shrinkable tube 10 that performs a coating process on a portion including the exposed portion of the sheath 1b among the respective components required for cable connection.

[0029] (1) Configuration of the normal temperature shrinkable tube The normal-temperature shrinkable tube 10 has a tubular member formed in a hollow tubular (tube-like) shape from a material having waterproofness, weather resistance, insulation, and elasticity. The material for forming the tubular member is, for example, ethylene propylene rubber (EPDM), chloroprene rubber, butyl rubber, silicone rubber, natural rubber, fluorine-based rubber, silicone-modified EPDM, etc. And, by attaching a core member in which a rod-shaped resin material is spirally wound to the inside of the tubular member, the tubular member is expanded in diameter, and it is configured such that the tubular member contracts in diameter by pulling out the core member from inside the tube. The resin material for forming the core member is, for example, polypropylene, polyethylene, ABS, polyamide, etc.

[0030] FIG. 2 is a side cross-sectional view showing a configuration example of the tubular member in the normal-temperature shrinkable tube according to the present embodiment. The illustration shows the cross-sectional configuration of the tubular member in a non-expanded diameter state in which the core member is not attached.

[0031] As shown in FIG. 2, in the present embodiment, the tubular member 11 included in the normal-temperature shrinkable tube 10 has a thick-diameter portion 13 and a thin-diameter portion 14 having different tube diameters from each other in a non-expanded diameter state in which the core member is not attached. The thick-diameter portion 13 and the thin-diameter portion 14 are in a relationship in which the inner tube diameter of the thick-diameter portion 13 > the inner tube diameter of the thin-diameter portion 14 holds.

[0032] Note that the inner tube diameters of the thick-diameter portion 13 and the thin-diameter portion 14 respectively correspond to the size (nominal cross-sectional area) of the power cable 1, but the details thereof will be described later. The length in the tube axis direction will also be described in detail later.

[0033] Further, the tubular member 11 has a stepped portion 15 that connects the thick-diameter portion 13 and the thin-diameter portion 14 therebetween. Thereby, the tubular member 11 is configured such that the thick-diameter portion 13, the stepped portion 15, and the thin-diameter portion 14 are arranged in order along the tube axis direction, and the thick-diameter portion 13 and the thin-diameter portion 14 are arranged concentrically due to the intervention of the stepped portion 15.

[0034] The stepped portion 15 has an R-shaped cross-sectional shape at at least one, preferably both, of the continuous portion 15a with the large-diameter portion 13 or the continuous portion 15b with the small-diameter portion 14. The R-shape referred to here means a shape with rounded corners. In the illustrated example, the cross-sectional shape of both continuous portions 15a and 15b is an R-shape. Note that the significance of the R-shape, the preferred R (radius) dimension, etc. will be described in detail later.

[0035] Incidentally, FIG. 2 merely shows a single configuration example. That is, in the present embodiment, the tubular member of the room-temperature shrinkable tube 10 is not limited to the single configuration example shown in FIG. 2, and may be of other configuration examples.

[0036] FIG. 3 is a side cross-sectional view showing another configuration example of the tubular member in the room-temperature shrinkable tube according to the present embodiment. Similar to the case of FIG. 2, the illustrated example shows the cross-sectional configuration of the tubular member in the non-expanded diameter state in which the core member is not attached.

[0037] As shown in FIG. 3, the tubular member 12 of the room-temperature shrinkable tube 10 has a large-diameter portion 13 and a small-diameter portion 14 with different tube diameters from each other in the non-expanded diameter state in which the core member is not attached. This point is the same as the case of the tubular member 11 shown in FIG. 2. However, for the tubular member 12 shown in FIG. 3, the configuration of the stepped portion 15 connecting the large-diameter portion 13 and the small-diameter portion 14 is different.

[0038] In the tubular member 12 of FIG. 3, the stepped portion 15 has a cross-sectional shape at the continuous portion 15a with the large-diameter portion 13 and the continuous portion 15b with the small-diameter portion 14 that is not an R-shape but an angular shape. The angular shape referred to here means a sharp-cornered shape without rounding or a shape having a small amount of rounding that can be regarded as the same as the sharp-cornered shape. Further, the stepped portion 15 has a tapered shape portion 15c whose tube diameter changes along the tube axis direction between the respective continuous portions 15a and 15b. The tapered shape portion 15c is formed such that the inner diameter of the tube gradually expands from the side of the small-diameter portion 14 toward the side of the large-diameter portion 13. Note that the significance of the tapered shape portion 15c, etc. will be described in detail later.

[0039] As described above, in this embodiment, the tubular members 11 and 12 of the room temperature shrinkable tube 10 only need to have at least a large diameter portion 13 and a small diameter portion 14, and the specific configuration of the step portion 15 connecting these is not limited to a specific mode.

[0040] (2) Procedure of cable connection method Subsequently, the procedure for connecting power cables 1 while using the room temperature shrinkable tube 10 having the tubular members 11 and 12 described above will be described as the procedure of the cable connection method according to this embodiment.

[0041] The cable connection method according to this embodiment is used at a construction site for connecting power cables 1. At the construction site, first, an operator establishes the connection state of the power cables 1 while using a conductor connection tube 2, an insulating cylinder 3, an ACP tape 4, a flat braided wire 5, a grounding spring 6, a semiconductive tape 7, etc. Then, the outer peripheral side of the insulating cylinder 3 is covered with a room temperature shrinkable tube 8 whose tubular member is a straight cylinder. So far, it is as shown in the cable connection structure of FIG. 1 and can be carried out using known techniques.

[0042] Thereafter, a covering process using the room temperature shrinkable tube 10 is performed on the range from the outer peripheral portion of the room temperature shrinkable tube 8 to the exposed portion of the sheath 1b continuous therewith (that is, the portion including the exposed portion of the sheath 1b). The covering process using the room temperature shrinkable tube 10 is performed according to the procedure described below.

[0043] As a first step, first, a room temperature shrinkable tube 10 for the covering process is prepared. As the room temperature shrinkable tube 10, as described above, the tubular members 11 and 12 are configured to have at least a large diameter portion 13 and a small diameter portion 14, and a state in which the tubular member 11 is expanded in diameter by mounting a core member into the tube of the tubular members 11 and 12 is prepared.

[0044] FIG. 4 is a side sectional view showing a configuration example of a normal temperature shrinkable tube prepared in one procedure of the cable connection method according to the present embodiment. The illustrated example shows a state in which a tubular member 12 having a stepped portion 15 with a tapered portion 15c is expanded by mounting core members 17 and 18. However, the normal temperature shrinkable tube 10 to be prepared is not limited to this, and a tube expanded from a tubular member 11 having an R-shaped stepped portion 15 may be used (see, for example, FIG. 2).

[0045] As shown in FIG. 4, in the normal temperature shrinkable tube 10 to be prepared, core members 17 and 18 are mounted inside the tube of the tubular member 12, and thereby the tubular member 12 is in an expanded state. The core members 17 and 18 are formed by spirally winding a rod-shaped resin material (for example, a polypropylene material). The mounting of the core members 17 and 18 may be performed before the start of the coating process with the normal temperature shrinkable tube 10. For example, it may be considered that this is already performed at the stage before the factory shipment of the normal temperature shrinkable tube 10.

[0046] In the present embodiment, it is assumed that the mounting of the core members 17 and 18 is performed individually for the large-diameter portion 13 and the small-diameter portion 14 in the tubular member 12. That is, a core member 17 that expands according to the large-diameter portion 13 is mounted on the large-diameter portion 13. Further, a core member 18 that expands according to the small-diameter portion 14 is mounted on the small-diameter portion 14. Thereby, even after the expansion by the core members 17 and 18, the relationship that the inner diameter of the tube of the large-diameter portion 13 > the inner diameter of the tube of the small-diameter portion 14 is maintained between the large-diameter portion 13 and the small-diameter portion 14.

[0047] In this way, if each diameter expansion is carried out individually, even when the tubular member 12 has a large-diameter portion 13 and a small-diameter portion 14, the diameter expansion for each of the large-diameter portion 13 and the small-diameter portion 14 can be appropriately carried out. For example, if each diameter expansion is carried out uniformly to the same diameter, there is a possibility that the amount of elastic deformation when expanding the small-diameter portion 14 becomes excessive compared to the large-diameter portion 13. However, by carrying out each diameter expansion individually, such a possibility can be eliminated. That is, for each of the large-diameter portion 13 and the small-diameter portion 14, a diameter expansion can be carried out so as to fall within an appropriate range of the amount of elastic deformation.

[0048] Also, if each diameter expansion is carried out individually, the core member 17 attached to the large-diameter portion 13 and the core member 18 attached to the small-diameter portion 14 can be pulled out separately and independently from the inside of the tubular member 12. Therefore, the large-diameter portion 13 and the small-diameter portion 14 can be individually reduced in diameter, which is very preferable for improving the workability of the coating process.

[0049] Furthermore, if each diameter expansion is carried out individually, by optimizing the amount of elastic deformation of the large-diameter portion 13 and the small-diameter portion 14, the amount of elastic deformation of the stepped portion 15 located between them can also be optimized. That is, similar to the small-diameter portion 14, it is possible to eliminate the possibility that the amount of elastic deformation of the stepped portion 15 becomes excessive.

[0050] Regarding this point, for example, it is preferable to have a portion where the stepped portion 15 is formed in an R shape, like the tubular member 11 shown in FIG. 2. If it is in an R shape, stress concentration during elastic deformation can be suppressed, and deterioration, damage, etc. caused by such stress concentration can be prevented in advance. For suppressing stress concentration, for example, an R shape with an R (radius) dimension of about 1 mm or more and 10 mm or less may be sufficient. However, it is not essential to be in an R shape. For example, even if it is not in an R shape but in various shapes like the tubular member 12 shown in FIG. 3, it is possible to appropriately optimize the amount of elastic deformation in the stepped portion 15 as described above without problems.

[0051] In addition, the room-temperature shrinkable tube 10 prepared in the first step shall be sized to correspond to the thickness of the power cable 1. The thickness of the power cable 1 is classified into nominal sizes such as "60", "100", "150", ··· according to the nominal cross-sectional area (mm 2 ). Therefore, for example, if the thickness of the power cable 1 is "100", a room-temperature shrinkable tube 10 sized to correspond to "100" shall be prepared. The size mentioned here refers to the size in the radial direction.

[0052] Specifically, for the small-diameter part 14, prepare a room-temperature shrinkable tube 10 formed with an inner tube diameter larger than the outer diameter of the sheath 1b of the power cable 1 during diameter expansion and a smaller inner tube diameter than the outer diameter of the sheath 1b during diameter contraction. Also, since the radial sizes of the conductor connection tube 2, the insulating cylinder 3, etc. are also specified according to the thickness of the power cable 1, for the large-diameter part 13 as well, prepare a room-temperature shrinkable tube 10 formed with an inner tube diameter larger than the outer diameter of the insulating cylinder 3, etc. during diameter expansion and a smaller inner tube diameter than the outer diameter of the insulating cylinder 3, etc. during diameter contraction. Regarding how large the inner tube diameter should be during diameter expansion and how small the inner tube diameter should be during diameter contraction, it may be preset so that the desired surface pressure can be obtained during diameter contraction, taking into account the elastic modulus of the tubular member 12 and the surface pressure described later.

[0053] Regarding the size of the room-temperature shrinkable tube 10 to be prepared, if multiple types of power cables 1 with different thicknesses such as "60", "100", "150", ··· can be the objects of cable connection, manufacture multiple types of room-temperature shrinkable tubes 10 corresponding to each of them, and select the one with the size corresponding to the thickness of the power cable 1 actually to be constructed from among them. In that case, the types of sizes of the room-temperature shrinkable tube 10 do not necessarily have to individually correspond to the types of thicknesses of the power cable 1. Considering elastic deformation, for example, it is also possible to share the same-sized room-temperature shrinkable tubes 10 for "60" and "100".

[0054] Here, the size of the heat-shrinkable tube 10 in the radial direction has been described, but the length of the heat-shrinkable tube 10 in the tube axis direction will be described in detail later.

[0055] After preparing the heat-shrinkable tube 10 in the first step, subsequently, as the second step, the prepared heat-shrinkable tube 10 is arranged at a location to be coated with the heat-shrinkable tube 10. Here, the location to be coated is among the locations to be sealed at the connection portion between the power cables 1, particularly the location including the edge of the heat-shrinkable tube 8. Specifically, it is the location ranging from the outer peripheral portion of the heat-shrinkable tube 8 to the exposed portion of the sheath 1b connected thereto. The heat-shrinkable tube 10 is arranged so as to enclose the location to be sealed including the edge of such a heat-shrinkable tube 8 inside the tube.

[0056] The heat-shrinkable tube 10 is arranged such that the thick-diameter portion 13 of the heat-shrinkable tube 10 encloses the outer peripheral portion of the heat-shrinkable tube 8, and the thin-diameter portion 14 of the heat-shrinkable tube 10 encloses the location including the exposed portion of the sheath 1b. Regarding the arrangement in such a manner, since the heat-shrinkable tube 10 has a stepped portion 15 between the thick-diameter portion 13 and the thin-diameter portion 14, it can be performed very simply by utilizing the positioning by butting the stepped portion 15. That is, by performing the positioning using the stepped portion 15, the heat-shrinkable tube 10 can be easily and surely arranged with respect to the location to be sealed by the heat-shrinkable tube 10.

[0057] After arranging the heat-shrinkable tube 10 in the second step, subsequently, as the third step, the core members 17, 18 are pulled out from inside the tube of the tubular member 12 in the heat-shrinkable tube 10.

[0058] For example, regarding the thick-diameter portion 13, the extending end 17a of the core member 17 extending from the edge on the side opposite to the thin-diameter portion 14 side in the thick-diameter portion 13 is pulled out toward the outside of the thick-diameter portion 13 (the side away from the thin-diameter portion 14). As a result, the core member 17 is gradually pulled out along the spiral winding order from the side close to the thin-diameter portion 14. When the core member 17 is pulled out, the thick-diameter portion 13 loses the support by the core member 17 and elastically deforms in the direction of diameter reduction. Then, after the diameter reduction, the thick-diameter portion 13 is in a state of being crimped to the outer peripheral surface of the portion (the outer peripheral portion of the normal-temperature shrinkable tube 8) enclosed in the thick-diameter portion 13.

[0059] Also, regarding the thin-diameter portion 14, the extending end 18a of the core member 18 extending from the edge on the side opposite to the thick-diameter portion 13 side in the thin-diameter portion 14 is pulled out toward the outside of the thin-diameter portion 14 (the side away from the thick-diameter portion 13). As a result, the core member 18 is gradually pulled out along the spiral winding order from the side close to the thick-diameter portion 13. When the core member 18 is pulled out, the thin-diameter portion 14 loses the support by the core member 18 and elastically deforms in the direction of diameter reduction. Then, after the diameter reduction, the thin-diameter portion 14 is in a state of being crimped to the outer peripheral surface of the portion (including the exposed portion of the sheath 1b) enclosed in the thin-diameter portion 14.

[0060] Note that the order of pulling out the core members 17 and 18 may be to pull out the core member 17 first, or conversely, the core member 18 may be pulled out first, or they may be pulled out simultaneously.

[0061] When the thick-diameter portion 13 and the thin-diameter portion 14 are reduced in diameter by pulling out the core members 17 and 18, the portion to be sealed enclosed in the tube of the normal-temperature shrinkable tube 10 is covered and sealed by the tubular member 12 after the diameter reduction. At this time, surface pressure is applied to the portion to be sealed by the crimping of the tubular member 12. The surface pressure here refers to the pressing force per unit area applied in the normal direction of the surface to the surface of the portion to be sealed.

[0062] In this embodiment, the tubular member 12 has a thick-diameter portion 13 and a thin-diameter portion 14. Therefore, even when there are portions with different radial sizes at the location to be sealed by the room-temperature shrinkable tube 10, good coating treatment with appropriate surface pressure can be performed on each portion by reducing the diameters of the thick-diameter portion 13 and the thin-diameter portion 14.

[0063] Specifically, at the location to be sealed by the room-temperature shrinkable tube 10, the outer peripheral portion of the room-temperature shrinkable tube 8 covering the insulating cylinder 3 and the exposed portion of the sheath 1b have different radial sizes. In this case, in this embodiment, for the sealing of the outer peripheral portion of the room-temperature shrinkable tube 8, it is performed by reducing the diameter of the thick-diameter portion 13 with a corresponding diameter dimension. Also, for the sealing of the exposed portion of the sheath 1b, it is performed by reducing the diameter of the thin-diameter portion 14 with a corresponding diameter dimension. Therefore, even when there are portions with different radial sizes mixed at the location to be sealed, by reducing the diameters of the thick-diameter portion 13 and the thin-diameter portion 14 with corresponding diameter dimensions for sealing, it is possible to prevent the surface pressure on the insulating cylinder 3, which is the large-diameter portion, and the outer peripheral portion of the room-temperature shrinkable tube 8 from becoming excessive, or the surface pressure on the exposed portion of the sheath 1b, which is the small-diameter portion, from being insufficient and the restraining force on the exposed portion from being insufficient.

[0064] In particular, for the sheath 1b, shrinkage over time due to the shrink-back phenomenon may occur. Even in such a situation, since sufficient surface pressure can be ensured by the pressure bonding of the thin-diameter portion 14 to the exposed portion of the sheath 1b, it is possible to suppress the surface pressure from becoming insufficient due to the occurrence of the shrink-back phenomenon. That is, by the thin-diameter portion 14 covering the exposed portion of the sheath 1b, it becomes very useful in eliminating the possibility of insufficient restraining force on the exposed portion regardless of the occurrence of the shrink-back phenomenon.

[0065] The binding force referred to here is specified by multiplying the surface pressure applied by the crimping of the tubular member 12 by the crimping area. It can be said that the crimping area highly depends on the length in the tube axis direction of the normal temperature shrinkable tube 10 with respect to changes in its size. Therefore, in order to ensure the binding force for the exposed portion of the sheath 1b, in addition to sufficiently ensuring the surface pressure obtained by reducing the diameter of the small-diameter portion 14, it is important that the length of the small-diameter portion 14 in the tube axis direction is appropriately set.

[0066] Based on this, in the present embodiment, it is preferable that the small-diameter portion 14 is formed to have a length in the tube axis direction of 50 mm or more and 250 mm or less. If it is 50 mm or more, even if there are exposed portions of the ACP tape 4, the flat braided wire 5, the grounding spring 6, etc. between the normal temperature shrinkable tube 8 covering the insulating cylinder 3 etc. and the exposed portion of the sheath 1b, while covering these, it is possible to secure the minimum necessary lap length (overlapping length) for the small-diameter portion 14 to cover the exposed portion of the sheath 1b. And by securing the minimum necessary lap length, a minimum necessary binding force can be obtained for the exposed portion of the sheath 1b. Also, if it is 250 mm or less, while ensuring sufficient binding force for the exposed portion of the sheath 1b, it is possible to suppress the deterioration of the workability of the covering process due to the small-diameter portion 14 becoming longer than necessary.

[0067] By going through the above respective procedures, even when there are locations with different radial sizes mixed in the location to be sealed, the tubular member 12 can perform good covering processing with appropriate surface pressure and binding force for each location.

[0068] This can be realized by the tubular member 12 having the large-diameter portion 13 and the small-diameter portion 14. Therefore, not only when the covering process is performed using the tubular member 12 shown in FIG. 3 as described above, but also when the covering process is performed using the tubular member 11 shown in FIG. 2, for example, it is exactly the same.

[0069] In addition, when the coating process is performed using the tubular member 11 shown in FIG. 2, as described above, at the stepped portion 15, stress concentration during elastic deformation can be suppressed, and deterioration, damage, etc. caused by such stress concentration can be prevented in advance. On the other hand, when the coating process is performed using the tubular member 12 shown in FIG. 3, since the stepped portion 15 has the tapered portion 15c, it is possible to make the tapered portion 15c conform to the shape of the location where the ACP tape 4, the flat braided wire 5, the grounding spring 6, etc. are arranged. Therefore, generation of a load due to non-conformity of the shape can be suppressed, and deterioration, damage, etc. caused by such a load can be prevented in advance.

[0070] In any case, it is assumed that the inner diameters of the tubular members 11 and 12 are designed such that each of the large-diameter portion 13 and the small-diameter portion 14 generates a surface pressure within a desired range with respect to the coating location (location to be sealed) in the crimped state after diameter reduction. Here, the desired range is, for example, 0.05 MPa or more and 0.2 MPa or less. If it is 0.05 MPa or more, it is a necessary and sufficient surface pressure, and if it is 0.2 MPa or less, it is possible to suppress the surface pressure from becoming excessive. This shall hold true regardless of the type of thickness of the power cable 1. In other words, in the first step, a heat-shrinkable tube 10 sized corresponding to the thickness of the power cable 1 is prepared so as to obtain a surface pressure belonging to the desired range.

[0071] Also, for each of the large-diameter portion 13 and the small-diameter portion 14, it is assumed that the inner diameter is designed such that the relationship of the surface pressure by the large-diameter portion 13 < the surface pressure by the small-diameter portion 14 holds. Since the exposed portion of the sheath 1b is included in the coating location by the small-diameter portion 14, considering the occurrence of the shrink-back phenomenon, etc., it is preferable to emphasize the surface pressure by the small-diameter portion 14 in order to perform a good coating process with appropriate surface pressure and restraint force.

[0072] After going through the above steps, if the vicinity of the edges of the tubular members 11 and 12 is sealed by the seal member 9, the cable connection structure according to the present embodiment is configured.

[0073] (3) Effects according to this embodiment According to this embodiment, one or more of the following effects can be achieved.

[0074] (a) According to this embodiment, the tubular members 11 and 12 have the large-diameter portions 13 and the small-diameter portions 14. Therefore, even when there are portions with different radial sizes at the location to be sealed by the room-temperature shrinkable tube 10, good coating treatment with appropriate surface pressure can be performed on each portion by the shrinkage of the large-diameter portions 13 and the small-diameter portions 14. For example, when the exposed portion of the sheath 1b, which is a small-diameter portion, is included in the location to be sealed, even if there is a risk of shrinkage over time due to the shrink-back phenomenon of the sheath 1b, the small-diameter portion 14 covers the exposed portion of the sheath 1b, making it possible to cover the small-diameter portion with sufficient surface pressure and restraint force while eliminating such a risk.

[0075] (b) According to this embodiment, since the tubular members 11 and 12 have the large-diameter portions 13 and the small-diameter portions 14, positioning when arranging the room-temperature shrinkable tube 10 can be performed very simply by utilizing the stepped portion 15 between these large-diameter portions 13 and small-diameter portions 14. Therefore, the room-temperature shrinkable tube 10 can be easily and surely arranged with respect to the location to be sealed by the room-temperature shrinkable tube 10, which is very preferable for improving the workability of the coating treatment as a result.

[0076] (c) As described in this embodiment, if there is a portion where the stepped portion 15 is formed in an R shape, stress concentration when the tubular members 11 and 12 are elastically deformed can be suppressed, and deterioration, damage, etc. caused by such stress concentration can be prevented in advance.

[0077] (d) As described in this embodiment, if the stepped portion 15 has the tapered shape portion 15c, it becomes possible to align the tapered shape portion 15c with the shape of the location to be sealed, so the generation of a load due to non-alignment of the shapes can be suppressed, and deterioration, damage, etc. caused by such a load can be prevented in advance.

[0078] (e) As described in this embodiment, if the length of the small-diameter portion 14 in the tube axis direction is formed to be 50 mm or more and 250 mm or less, it is possible to secure the minimum lap length necessary for the small-diameter portion 14 to cover the exposed portion of the sheath 1b, and while securing sufficient restraint force on the exposed portion of the sheath 1b, it is possible to suppress the deterioration of the workability of the covering process due to the small-diameter portion 14 becoming longer than necessary.

[0079] <Modification example, etc.> As described above, one embodiment of the present disclosure has been specifically described. However, the present disclosure is not limited to the above-described embodiment, and various modifications can be made without departing from the gist thereof.

[0080] For example, in the above-described embodiment, the case of mainly connecting power cables 1 to each other has been described as an example. However, the present disclosure is not limited thereto, and for example, the case where a device terminal portion such as a device direct connection T-type terminal is the connection partner can be applied in exactly the same manner.

[0081] Further, the cable connection structure described in the above-described embodiment is merely one specific example, and as long as the tubular member constituting the normal temperature shrinkable tube has a large-diameter portion and a small-diameter portion, other components may be replaced or changed.

Explanation of reference numerals

[0082] 1 Power cable 1a Conductive wire 1b Sheath 2 Conductor connection tube 3 Insulating cylinder 4 ACP tape 5 Flat braided wire 6 Grounding spring 7 Semiconducting tape 8 Normal temperature shrinkable tube 9 Sealing member 10 Normal temperature shrinkable tube 11 Tubular member 12 Tubular member 13 Large-diameter portion 14 Small-diameter portion 15 Step portion 15a Continuous portion 15b Continuous portion 15c Tapered portion 17 Core member 17a Extended end 18 Core member 18a Extended end

Claims

1. A room-temperature shrinkable tube having a tubular member formed of a material having insulation and elasticity, wherein the tubular member expands in diameter when a core member is inserted into the tube, and contracts in diameter when the core member is withdrawn from the tube, The tubular member has a thick-diameter portion and a thin-diameter portion having different tube diameters from each other in a non-expanded diameter state in which the core member is not attached. Room-temperature shrinkable tube.

2. The tubular member has a stepped portion connecting the thick-diameter portion and the thin-diameter portion, At least one of the cross-sectional shapes at the continuous portion with the thick-diameter portion or the continuous portion with the thin-diameter portion of the stepped portion is formed in an R shape. The room-temperature shrinkable tube according to claim 1.

3. The tubular member has a stepped portion connecting the thick-diameter portion and the thin-diameter portion, The stepped portion has a cross-sectional shape formed in a square shape at the continuous portion with the thick-diameter portion and the continuous portion with the thin-diameter portion, and has a tapered shape portion in which the tube diameter changes along the tube axis direction between the respective continuous portions. The room-temperature shrinkable tube according to claim 1.

4. The thin-diameter portion is formed to have a length in the tube axis direction of 50 mm or more and 250 mm or less. The room-temperature shrinkable tube according to any one of claims 1 to 3.

5. A cable connection structure for connecting a cable in which a conductor is covered with a sheath and a connection partner of the cable, Comprising a room-temperature shrinkable tube arranged to cover a connection portion between the cable and the connection partner, The room-temperature shrinkable tube has a tubular member formed of a material having insulation and elasticity, and is configured such that the tubular member expands in diameter when a core member is inserted into the tube, and contracts in diameter when the core member is withdrawn from the tube. The tubular member has a thick-diameter portion and a thin-diameter portion with different pipe diameters in a non-expanded diameter state where the core member is not attached, and is arranged such that the reduced-diameter thin-diameter portion is in a state of being crimped to the outer peripheral surface of the sheath. Cable connection structure.

6. A cable connection method used when connecting a cable in which a conducting wire is covered by a sheath and a connection partner of the cable, comprising: Preparing a heat-shrinkable tube at normal temperature having a tubular member formed of a material having insulation and elasticity, wherein the tubular member is in an expanded diameter state by mounting a core member into the tube of the tubular member, while in a non-expanded diameter state where the core member is not mounted, the tubular member has a thick-diameter portion and a thin-diameter portion with different pipe diameters; Arranging the heat-shrinkable tube at normal temperature so as to enclose a portion to be sealed at a connection location between the cable and the connection partner within the tube of the tubular member; Pulling out the core member from the tube of the tubular member in the heat-shrinkable tube at normal temperature to reduce the diameter of the tubular member, and covering the portion to be sealed with the tubular member in a state where the reduced-diameter thin-diameter portion is crimped to the outer peripheral surface of the sheath in the cable. A cable connection method comprising the above steps.

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