Power Cable Connection Device

Abstract

To provide a power cable connection device capable of reducing stress generated in a porcelain tube.SOLUTION: A power cable connection device includes: a porcelain tube into which a power cable is inserted; a pipe member exhibiting higher rigidity than that of the porcelain tube and provided inside the porcelain tube so as to face the power cable; an embedded member exhibiting higher rigidity than that of the porcelain tube, partially embedded in the porcelain tube, and arranged at a position on an outer peripheral side of the pipe member; a first semi-conductive layer provided between the pipe member and the porcelain tube; and a second semi-conductive layer provided between the embedded member and the porcelain tube. At least one boundary of a boundary between an outer peripheral surface of the pipe member and the first semi-conductive layer and a boundary between an inner peripheral surface of the embedded member and the second semi-conductive layer has a stress relaxation layer.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a power cable connection device. [Background technology]

[0002] Patent Document 1 discloses a power cable connection device for connecting a power cable to other electric wires, etc. The power cable connection device described in Patent Document 1 includes a porcelain bushing made of a polymer-based material, a metal pipe member disposed on the inner periphery of the porcelain bushing, a first semiconductive layer disposed between the pipe member and the porcelain bushing, a metal embedded member formed in an annular shape so as to surround the pipe member from the outer periphery and partly embedded in the porcelain bushing, and a second semiconductive layer provided between the embedded member and the porcelain bushing. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2016-116279 Summary of the Invention [Problem to be solved by the invention]

[0004] Here, the first semiconductive layer disposed between the porcelain bushing and the metal pipe member is fixed to both the porcelain bushing and the pipe member, and the second semiconductive layer disposed between the porcelain bushing and the metal embedded member is fixed to both the porcelain bushing and the embedded member. This prevents gaps from being formed between the porcelain bushing and the pipe member and between the porcelain bushing and the embedded member, and prevents discharges from occurring in the gaps. However, in this case, because the thermal expansion coefficients of the porcelain bushing, the metal pipe member, and the metal embedded member are different, stress is likely to occur, particularly in the interposed portion of the porcelain bushing sandwiched between the embedded member and the pipe member. For example, when the porcelain bushing attempts to shrink more radially inward than the pipe member and the embedded member, stress is generated in the interposed portion of the porcelain bushing due to the pull of the embedded member on the outer periphery. Furthermore, when the porcelain tube attempts to expand more radially outward than the pipe member and the embedded member, stress is generated in the intervening portion of the porcelain tube due to the pulling of the pipe member on the inner periphery thereof. If the stress described above becomes excessively large or if the stress described above occurs repeatedly, cracks may occur in the porcelain tube, and the insulating properties of the porcelain tube may be reduced.

[0005] The present invention has been made in view of the above circumstances, and has an object to provide a power cable connection device that can reduce stress generated in a porcelain bushing. [Means for solving the problem]

[0006] In order to achieve the above-mentioned object, the present invention provides a power cable connection device comprising: a porcelain tube into which a power cable is inserted; a pipe member which is arranged inside the porcelain tube so as to face the power cable and has higher rigidity than the porcelain tube; an embedded member which is arranged on the outer periphery of the pipe member and has a part embedded in the porcelain tube and has higher rigidity than the porcelain tube; a first semiconductive layer which is provided between the pipe member and the porcelain tube; and a second semiconductive layer which is provided between the embedded member and the porcelain tube, wherein at least one of the boundary between the outer periphery of the pipe member and the first semiconductive layer and the boundary between the inner periphery of the embedded member and the second semiconductive layer has a stress relaxation layer. [Effects of the Invention]

[0007] According to the present invention, it is possible to provide a power cable connection device that can reduce stress generated in a porcelain bushing. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a cross-sectional view of a power cable connection device according to a first embodiment. [Figure 2] 2 is an enlarged cross-sectional view of the embedded member and its surroundings in FIG. 1. FIG. [Figure 3] FIG. 3 is a cross-sectional view taken along the line III-III in FIG. 2. [Figure 4] FIG. 10 is an enlarged cross-sectional view of the periphery of a buried member of a power cable connection device according to a second embodiment. [Figure 5] FIG. 11 is an enlarged cross-sectional view of the periphery of a buried member of a power cable connection device according to a third embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0009] [First embodiment] A first embodiment of the present invention will be described with reference to Figures 1 to 3. The embodiment described below is shown as a preferred specific example for carrying out the present invention, and although various technically preferable technical matters are specifically exemplified, the technical scope of the present invention is not limited to this specific embodiment.

[0010] (Power cable connection device 1) FIG. 1 is a cross-sectional view of a power cable connection device 1 according to this embodiment. As shown in FIG. 1, the power cable connection device 1 includes a main body 2, a cover 3, and a connection portion 4. The main body 2 ensures electrical insulation between the stepped stripped power cable 10 and components arranged around the power cable 10. The cover 3 covers a portion of the main body 2. The connection portion 4 is a component for connecting the power cable 10 to the outside of the power cable connection device 1. Hereinafter, the direction in which the central axis C of the power cable 10 extends will be referred to as the axial direction X. The side of the power cable 10 in the axial direction X that is connected to the connection portion 4 will be referred to as the tip side X1, and the opposite side will be referred to as the base side X2.

[0011] (Main body 2) The main body 2 includes a porcelain tube 21, a pipe member 22, a first semiconductive layer 23, an embedded member 24, a second semiconductive layer 25, and a third semiconductive layer 26. The porcelain tube 21 is made of, for example, a polymer-based material formed into a tubular shape and is flexible. Examples of polymer-based materials that can be used to form the porcelain tube 21 include silicone rubber, ethylene propylene rubber (EPM), and ethylene propylene diene rubber (EPDM). In particular, using a material for the porcelain tube 21 with a relatively high tear strength can more easily prevent cracks from occurring in the porcelain tube 21, while using a material with a relatively low modulus of elasticity can more easily insert the power cable 10 into the porcelain tube 21. Annular umbrella portions 211 protruding outward are provided at multiple locations at predetermined intervals in the axial direction X on the outer periphery of the porcelain tube 21. Forming a plurality of umbrella portions 211 in the porcelain tube 21 makes it possible to ensure a creeping distance on the outer peripheral surface of the porcelain tube 21 and to suppress the occurrence of creeping discharge along the surface of the porcelain tube 21. The porcelain tube 21 is molded by insert molding, in which the pipe member 22, the first semiconductive layer 23, the embedded member 24, the second semiconductive layer 25, the third semiconductive layer 26, etc. are arranged in a mold, and then molten resin that constitutes the porcelain tube 21 is injected into the mold and hardened.

[0012] The pipe member 22 is made of a material having higher rigidity than the porcelain tube 21, such as a metal such as brass or an aluminum alloy. The pipe member 22 is arranged on the inner periphery of the porcelain tube 21. The pipe member 22 serves to reinforce the flexible porcelain tube 21. An end portion on the tip side X1 of the pipe member 22 protrudes from the porcelain tube 21 and is electrically connected to the power cable 10 via a connection portion 4 described below. An end portion on the base side X2 of the pipe member 22 faces the buried member 24 in the radial direction via the porcelain tube 21 or the like. The inner diameter of the pipe member 22 is larger than the outer diameter of the portion of the power cable 10 that is arranged inside the pipe member 22. This makes it easier to insert the power cable 10 into the pipe member 22.

[0013] The first semiconductive layer 23 is disposed between the pipe member 22 and the porcelain tube 21. The first semiconductive layer 23 has the property of adhering to both the pipe member 22 and the porcelain tube 21. However, as described below, the boundary between the first semiconductive layer 23 and the outer circumferential surface 220 of the pipe member 22 has a portion where the first semiconductive layer 23 is not adhered. The first semiconductive layer 23 is formed in a cylindrical shape so as to surround the pipe member 22 from the outer circumferential side, except for the tip portion. The first semiconductive layer 23 is also disposed between the power cable 10 and the porcelain tube 21 on the base end side X2 of the pipe member 22. The first semiconductive layer 23 is made of an elastic semiconductive material, such as silicone rubber, EPM, or EPDM, which is made conductive by dispersing conductive powder such as carbon in the material. The first semiconductive layer 23 serves to prevent deterioration of the porcelain tube 21 due to electric field concentration near the inner circumferential surface of the porcelain tube 21.

[0014] The embedded member 24 includes a tubular portion 241 and a flange portion 242. The tubular portion 241 is formed in a cylindrical shape, and the flange portion 242 is formed in an annular shape so as to protrude radially outward from the tubular portion 241. The embedded member 24 is disposed on the radially outer side of the pipe member 22 and is disposed so as to face an end portion of the base end side X2 of the pipe member 22 via the porcelain tube 21. The embedded member 24 is embedded in the porcelain tube 21 so that a mating surface 242a with the cover 3, which is provided on the surface of the base end side X2 of the flange portion 242, is exposed. The embedded member 24 is also provided with a female threaded hole 242b that opens into the mating surface 242a. The cover 3 and the attached member 100 are fastened together between the bolt 12 and the female threaded hole 242b, thereby fastening the power cable connection device 1 to the attached member 100. The buried member 24 is made of a material having higher rigidity than the porcelain tube 21, such as a metal such as brass or an aluminum alloy. The buried member 24 is connected to a ground potential when the power cable connection device 1 is in use. The linear expansion coefficients of the pipe member 22 and the buried member 24 are each smaller than the linear expansion coefficient of the porcelain tube 21.

[0015] The second semiconductive layer 25 is disposed between the embedded member 24 and the porcelain tube 21. The second semiconductive layer 25 has the property of adhering to both the embedded member 24 and the porcelain tube 21. However, as described below, the boundary between the second semiconductive layer 25 and the inner circumferential surface 240 of the embedded member 24 has a portion where the second semiconductive layer 25 is not adhered. In this embodiment, the second semiconductive layer 25 is disposed over the entire opposing region of the embedded member 24 and the porcelain tube 21, and the embedded member 24 and the porcelain tube 21 are not in direct contact with each other. Similar to the first semiconductive layer 23, the second semiconductive layer 25 is made of an elastic semiconductive material, such as silicone rubber, EPM, or EPDM, which is imparted with conductivity by dispersing conductive powder such as carbon in the material. The second semiconductive layer 25 serves to prevent deterioration of the porcelain tube 21 due to electric field concentration near the surface of the porcelain tube 21 facing the embedded member 24.

[0016] FIG. 2 is an enlarged cross-sectional view of the periphery of the embedded member 24 in FIG. 1 . FIG. 3 is a cross-sectional view taken along the line III-III in FIG. 2 . A release agent 5 is provided at the boundary between the outer peripheral surface 220 of the pipe member 22 and the first semiconductive layer 23, and at the boundary between the inner peripheral surface 240 of the embedded member 24 and the second semiconductive layer 25. The release agent 5 has releasability to at least one of the pipe member 22 and the embedded member 24 and the first semiconductive layer 23 and the second semiconductive layer 25, for example. For example, a fluorine-based release agent or a silicone-based release agent can be used as the release agent 5. When a fluorine-based release agent is used as the release agent 5, the release agent 5 provided at the boundary between the pipe member 22 and the first semiconductive layer 23 will be referred to as a first release agent 51, and the release agent 5 provided at the boundary between the embedded member 24 and the second semiconductive layer 25 will be referred to as a second release agent 52. When no particular distinction is required, these will simply be referred to as release agents 5. The release agent 5 may contain a release component such as a fluorine compound and a solvent. The amount of the release agent 5 may decrease or disappear when the solvent evaporates during the production of the power cable connection device 1.

[0017] As shown in FIG. 2, a region where an inner circumferential surface 240 of the embedded member 24 in the axial direction X (i.e., a surface facing the inner circumferential side of the tubular portion 241 and extending along the axial direction X) is formed is referred to as an inner circumferential surface region R. In this case, the first release agent 51 and the second release agent 52 are each formed in the inner circumferential surface region R in the axial direction X. Furthermore, as shown in FIG. 3, the first release agent 51 and the second release agent 52 are each formed over the entire periphery of the inner circumferential surface region R in the axial direction X. In this embodiment, the first release agent 51 is applied to the entire outer circumferential surface 220 of the pipe member 22, and the second release agent 52 is provided over the entire opposing region between the embedded member 24 and the second semiconductive layer 25. Note that, depending on the type of release agent 5, the thickness of the release agent 5 may be extremely thin. However, in FIG. 2, the thickness of the release agent 5 is exaggerated for convenience.

[0018] By disposing the release agent 5 as described above, it is possible to form unbonded portions at the boundary between the outer circumferential surface 220 of the pipe member 22 and the first semiconductive layer 23, and at the boundary between the embedded member 24 and the second semiconductive layer 25. Here, a state in which two members are bonded to each other refers to a state in which, when a force acts on the two members to pull them apart, a tensile stress acts at the boundary between them, and a state in which the two members are firmly bonded to each other by adhesion, crimping, or the like. For example, if the boundary between the outer circumferential surface 220 of the pipe member 22 and the first semiconductive layer 23 is not bonded, the outer circumferential surface 220 of the pipe member 22 and the first semiconductive layer 23 will not pull on each other during repeated thermal expansion and contraction of the entire power cable connection device 1. Furthermore, if the boundary between the outer peripheral surface 220 of the pipe member 22 and the first semiconductive layer 23 is not fixed, when the first semiconductive layer 23 is peeled off from the outer peripheral surface 220 of the pipe member 22, at least no visually visible residue of the first semiconductive layer 23 remains on the outer peripheral surface 220 of the pipe member 22. The same applies to the boundary between the embedding member 24 and the second semiconductive layer 25. In this embodiment, at least the boundary between the entire outer peripheral surface 220 of the pipe member 22 and the first semiconductive layer 23 and the boundary between the entire inner peripheral surface 240 of the embedding member 24 and the second semiconductive layer 25 are not fixed. Furthermore, in this embodiment, at least in the inner peripheral surface region R in the axial direction X, both the boundary between the outer peripheral surface 220 of the pipe member 22 and the first semiconductive layer 23 and the boundary between the inner peripheral surface 240 of the embedding member 24 and the second semiconductive layer 25 are not fixed.

[0019] 1 , the third semiconductive layer 26 is formed on the inside of the end portion of the base end side X2 of the porcelain tube 21 and has an annular shape. The power cable 10 is inserted into the inside of the third semiconductive layer 26, and the third semiconductive layer 26 comes into contact with the outer circumferential surface of the inserted power cable 10. Like the first semiconductive layer 23 and the second semiconductive layer 25, the third semiconductive layer 26 is made of an elastic semiconductive material, such as silicone rubber, EPM, or EPDM, which is made conductive by dispersing conductive powder such as carbon in the material. The third semiconductive layer 26 serves to prevent deterioration of the porcelain tube 21 due to concentration of an electric field near the inner circumferential surface of the porcelain tube 21.

[0020] The surface portions of the main body 2 that come into contact with the outer surface of the power cable 10 (i.e., the inner surface of the porcelain tube 21, the inner surface of the portion of the first semiconductive layer 23 located on the base end side X2 of the pipe member 22, and the inner surface of the third semiconductive layer 26) are smaller in outer diameter than the portions of the power cable 10 that are located inside the surface portions before the power cable 10 is inserted into the main body 2. The power cable 10 is inserted into the main body 2 while spreading out the surface portions, and is in close contact with the surface portions when inserted into the main body 2.

[0021] (Cover 3) The cover 3 is made of brass, aluminum alloy, or the like and is formed into a cylindrical shape, and covers from the outer periphery the main body 2 that protrudes from the embedded member 24 to the base end side X2. A cover flange 31 that protrudes to the outer periphery is formed at the end of the tip end side X1 of the cover 3. When the power cable connection device 1 is fixed to the attached member 100, the flange 242 of the embedded member 24, the cover flange 31, and the attached member 100 are overlapped in this order, and the bolt 12 is screwed into the female screw hole 242b formed in the flange 242 of the embedded member 24, thereby fixing the power cable connection device 1 to the attached member 100.

[0022] The gap between the end of the base end side X2 of the cover 3 and the power cable 10 is sealed by a sealing portion 13. The sealing portion 13 is formed by wrapping an adhesive-provided polyethylene tape, epoxy tape, or the like around the outer periphery of the power cable 10, and provides a liquid-tight seal between the cover 3 and the power cable 10.

[0023] (Connection 4) 1, the connection part 4 includes a conductor connecting rod 41, a high-voltage shield 42, a fixed terminal 43, and a co-fastening nut 44. The conductor connecting rod 41 has a connection hole 411 formed along the axial direction X that is open on the base end side X2. The conductor part 101 exposed from the insulating coating of the power cable 10 is inserted into the connection hole 411, and the end of the conductor connecting rod 41 on the base end side X2 is crimped toward the conductor part 101. In this way, the conductor connecting rod 41 and the power cable 10 are connected. In addition, the conductor connecting rod 41 has a male thread part 412 formed on the tip end side X1 that protrudes.

[0024] The high-voltage shield 42 is made of a conductor and has a cylindrical shape with a bottom that is open on the base end side X2. A side wall 421 of the high-voltage shield 42 covers, from the outer periphery, the tip portion of the pipe member 22 that protrudes from the porcelain tube 21 on the tip end side X1. The male thread portion 412 penetrates the bottom wall 422 of the high-voltage shield 42.

[0025] The fixed terminal 43 is plate-shaped and faces the surface on the tip side X1 of the high-voltage shield 42. The fixed terminal 43 is formed with a first hole 431 for inserting the male thread portion 412 and a second hole 432 for connecting an electric wire or the like for connecting the fixed terminal 43 to the outside. The fixed terminal 43 and the high-voltage shield 42 are fastened together between the conductor connecting rod 41 and a fastening nut 44, whereby the fixed terminal 43, the high-voltage shield 42, and the conductor connecting rod 41 are electrically connected to one another.

[0026] (Example of using the power cable connection device 1) Next, an example of how the power cable connection device 1 of this embodiment can be used will be described. The power cable connection device 1 is attached, for example, to the roof of a railway vehicle so that the porcelain pipe 21 is exposed to the outside of the railway vehicle. In this case, a wall portion constituting the roof of the railway vehicle serves as the attachment target 100. The power cable connection device 1 can be used, for example, for electrical connection between adjacent railway vehicles, electrical connection with a pantograph, etc.

[0027] (Functions and Effects of the First Embodiment) In this embodiment, at least one of the boundary between the outer circumferential surface 220 of the pipe member 22 and the first semiconductive layer 23 and the boundary between the inner circumferential surface 240 of the embedded member 24 and the second semiconductive layer 25 has an unbonded portion. This reduces thermal stress that may occur in the interposed portion 212 (see FIG. 2 ), which is a portion of the porcelain tube 21 interposed in the radial direction between the inner circumferential surface 240 of the embedded member 24 and the outer circumferential surface 220 of the pipe member 22. This will be described below.

[0028] There is a difference in linear expansion coefficient between the metallic pipe member 22 and the embedded member 24 and the porcelain tube 21. Therefore, in the interposed portion 212 of the porcelain tube 21 sandwiched between the pipe member 22 and the embedded member 24, if the first semiconductive layer 23 is fixed to both the pipe member 22 and the porcelain tube 21 and the second semiconductive layer 25 is fixed to both the embedded member 24 and the porcelain tube 21, thermal stress is likely to occur in the interposed portion 212. For example, when the porcelain tube 21 attempts to contract more inwardly than the pipe member 22 and the embedded member 24 in response to a temperature change, the outer periphery of the interposed portion 212 is pulled by the inner periphery surface 240 of the embedded member 24, and stress is likely to occur in the interposed portion 212. Furthermore, when the porcelain tube 21 attempts to expand more outward than the pipe member 22 and the buried member 24 in response to a temperature change, the inner peripheral portion of the interposed portion 212 is pulled toward the inner peripheral surface of the pipe member 22, and thermal stress is likely to occur in the interposed portion 212. Such thermal stress occurs, for example, when shrinkage stress remains after the porcelain tube 21 is formed, or when the temperature of each portion of the power cable connection device 1 changes while the power cable connection device 1 is in use. If the thermal stress described above becomes excessively large or if the thermal stress described above occurs repeatedly, cracks may occur in the interposed portion 212, and the electrical insulation between the buried member 24 and the porcelain tube 21 may deteriorate.

[0029] Therefore, in this embodiment, at least one of the boundary between the outer circumferential surface 220 of the pipe member 22 and the first semiconductive layer 23 and the boundary between the inner circumferential surface 240 of the embedded member 24 and the second semiconductive layer 25 has an unbonded portion. This makes it possible to prevent the interposed portion 212 from being pulled by the pipe member 22 and the embedded member 24 when the porcelain tube 21 attempts to contract more inwardly than the pipe member 22 and the embedded member 24 in response to a temperature change, and when the porcelain tube 21 attempts to expand more outwardly than the pipe member 22 and the embedded member 24 in response to a temperature change, thereby reducing thermal stress generated in the interposed portion 212. As a result, it is possible to prevent cracks from occurring in the interposed portion 212 and the insulating performance of the porcelain tube 21 from being reduced.

[0030] Furthermore, at least one of the boundary between the outer circumferential surface 220 of the pipe member 22 and the first semiconductive layer 23 and the boundary between the inner circumferential surface 240 of the embedded member 24 and the second semiconductive layer 25 has an unbonded portion in the inner circumferential surface region R where the inner circumferential surface 240 of the embedded member 24 is formed in the axial direction X. Therefore, it is possible to effectively suppress stress generated in the interposed portion 212 in the porcelain tube 21, where stress is more likely to be generated.

[0031] Furthermore, the release agent 5 is present at at least one of the boundaries between the outer peripheral surface 220 of the pipe member 22 and the first semiconductive layer 23 and the boundary between the inner peripheral surface 240 of the embedded member 24 and the second semiconductive layer 25. This makes it possible to easily form an unbonded portion at at least one of the boundaries between the outer peripheral surface 220 of the pipe member 22 and the first semiconductive layer 23 and the boundary between the inner peripheral surface 240 of the embedded member 24 and the second semiconductive layer 25. Furthermore, by disposing the release agent 5, it is possible to prevent spaces from being formed at the boundaries between the pipe member 22 and the first semiconductive layer 23 and the boundaries between the embedded member 24 and the second semiconductive layer 25, and it is possible to prevent discharge from occurring between the pipe member 22 and the first semiconductive layer 23 and between the embedded member 24 and the second semiconductive layer 25.

[0032] As described above, according to this embodiment, it is possible to provide a power cable connection device that can reduce stress generated in the porcelain bushing.

[0033] In this embodiment, an example has been shown in which the release agent 5 remains at the boundary between the outer circumferential surface 220 of the pipe member 22 and the first semi-conductive layer 23, and at the boundary between the inner circumferential surface 240 of the embedded member 24 and the second semi-conductive layer 25, but the present invention is not limited to this. For example, the release agent 5 may be present during the manufacturing process of the power cable connection device 1, but may have disappeared by the time the power cable connection device 1 is completed as a product. Even in this case, by disposing the release agent 5 at the boundary between the outer circumferential surface 220 of the pipe member 22 and the first semi-conductive layer 23, and at the boundary between the inner circumferential surface 240 of the embedded member 24 and the second semi-conductive layer 25 during the manufacturing process of the power cable connection device 1, it is possible to make these boundaries unfixed.

[0034] In this embodiment, the release agent 5 is used to form an unbonded portion at at least one of the boundary between the outer peripheral surface 220 of the pipe member 22 and the first semiconductive layer 23 and the boundary between the inner peripheral surface 240 of the embedded member 24 and the second semiconductive layer 25. However, the present invention is not limited to this. For example, after the first semiconductive layer 23 is formed on the outer peripheral surface 220 of the pipe member 22, a cylindrical member can be inserted between them and then removed, thereby making the boundary between the outer peripheral surface 220 of the pipe member 22 and the first semiconductive layer 23 unbonded. A similar modification can also be made to the boundary between the embedded member 24 and the second semiconductive layer 25.

[0035] In addition, in the present embodiment, an unbonded portion is formed at both the boundary between the outer circumferential surface 220 of the pipe member 22 and the first semiconductive layer 23 and the boundary between the inner circumferential surface 240 of the embedded member 24 and the second semiconductive layer 25. However, this is not limited thereto, and it is sufficient that an unbonded portion is formed at at least one of the boundaries. For example, in the present embodiment, the first release agent 51 provided at the boundary between the pipe member 22 and the first semiconductive layer 23 may be eliminated. In this case, a stress relaxation layer may be formed at the boundary between the pipe member 22 and the first semiconductive layer 23. The stress relaxation layer is a member for reducing stress generated in the porcelain tube 21 due to thermal changes, and may be formed, for example, from insulating rubber that is bonded to the pipe member 22 and the first semiconductive layer 23 but has lower elasticity than the porcelain tube 21 (for example, an elastic modulus of 1 MPa or less). Alternatively, the stress relaxation layer may be made of a material (for example, an electrically insulating engineering plastic) having a linear expansion coefficient between the linear expansion coefficient of the pipe member 22 and the linear expansion coefficient of the first semiconductive layer 23. The boundary between the embedded member 24 and the second semiconductive layer 25 can also be modified to the same effect.

[0036] [Second embodiment] FIG. 4 is an enlarged cross-sectional view of the periphery of the buried member 24 of the power cable connection device 1 in this embodiment. In this embodiment, a pipe member 22 is formed with a plurality of holes 221 penetrating the pipe member 22 in the radial direction. The pipe member 22 has a large number of holes 221 formed in at least an inner peripheral surface region R in the axial direction X, where an inner peripheral surface 240 of the buried member 24 is formed. At least the inner peripheral surface region R in the axial direction X of the pipe member 22 is configured in a mesh-like shape, and each mesh portion forms a hole 221. During insert molding to form the porcelain bushing 21, the hole 221 is not completely blocked by the molten resin that forms the porcelain bushing 21, and the inside of the hole 221 is left empty. In the region of the pipe member 22 where the hole 221 exists, adhesion between the pipe member 22 and the first semiconductive layer 23 is prevented. Note that a portion of the first semiconductive layer 23 may enter the hole 221. The inner peripheral end of the inner space of each hole 221 opens into the space on the outer peripheral side of the power cable 10 .

[0037] Other configurations of this embodiment are the same as those of the first embodiment. In addition, among the symbols used in the second embodiment and the following embodiments, the same symbols as those used in the previous embodiments represent the same components, etc. as in the previous embodiments, unless otherwise specified.

[0038] (Functions and Effects of the Second Embodiment) In this embodiment, since the pipe member 22 has a large number of holes 221 formed therein, adhesion between the pipe member 22 and the first semi-conductive layer 23 is prevented in the region where the holes 221 exist in the pipe member 22. Therefore, it is possible to easily form a portion at the boundary between the pipe member 22 and the first semi-conductive layer 23 that is not adhered to each other. In addition, this embodiment also has the same functions and effects as the first embodiment.

[0039] In this embodiment, a release agent 5 may be provided on the outer peripheral surface 220 of the pipe member 22 and on the inner peripheral surfaces of each of the numerous holes 221, as in the first embodiment, to further suppress adhesion between the pipe member 22 and the first semiconducting layer 23.

[0040] In this embodiment, at least a portion of the pipe member 22 is made mesh-like, thereby forming the meshed portions into the holes 221. However, the present invention is not limited to this, and at least a portion of the pipe member 22 may be made of a porous member (e.g., porous metal). In this case, it is preferable that the holes of the porous member communicate with the pipe member 22 from the inner peripheral surface to the outer peripheral surface 220 of the pipe member 22.

[0041] [Third embodiment] FIG. 5 is an enlarged cross-sectional view of the periphery of the buried member 24 of the power cable connection device 1 in this embodiment. This embodiment differs from the first embodiment in that the length of the pipe member 22 is changed and the first release agent (see reference numeral 51 in FIG. 2) is eliminated. That is, in this embodiment, the first semiconductive layer 23 is fixed to both the outer circumferential surface 220 of the pipe member 22 and the porcelain tube 21. The end of the base end side X2 of the pipe member 22 is positioned closer to the tip end side X1 than the end of the tip end side X1 of the inner circumferential surface 240 of the buried member 24. That is, in the axial direction X, the pipe member 22 is positioned farther toward the X1 side than the inner circumferential surface region R. The second release agent 52 is provided over the entire opposing region between the buried member 24 and the second semiconductive layer 25. The other configurations are the same as those in the first embodiment.

[0042] (Functions and Effects of the Third Embodiment) In this embodiment, in the axial direction X, the pipe member 22 is disposed at a position farther toward the X1 side than the inner circumferential surface region R. Therefore, in the inner circumferential surface region R in the axial direction X, the inner circumferential surface 240 of the embedded member 24 and the porcelain tube 21 are not constrained to each other in the radial direction, and stress can be prevented from being generated in the portion 213 of the porcelain tube 21 located on the inner circumferential side of the inner circumferential surface 240 of the embedded member 24. In addition, this embodiment also has the same effects as the first embodiment.

[0043] (Summary of the embodiment) Next, the technical ideas grasped from the above-described embodiments will be described by using the reference numerals and the like in the embodiments. However, the reference numerals and the like in the following description do not limit the components in the claims to the members and the like specifically shown in the embodiments.

[0044] [1] A porcelain tube (21) into which a power cable (10) is inserted, a pipe member (22) that is disposed inside the porcelain tube (21) so as to face the power cable (10) and has higher rigidity than the porcelain tube (21), a buried member (24) that is disposed at a position on the outer periphery side of the pipe member (22) and is partially buried in the porcelain tube (21) and has higher rigidity than the porcelain tube (21), and a space between the pipe member (22) and the porcelain tube (21). and a second semi-conductive layer (25) provided between the buried member (24) and the porcelain tube (21), wherein at least one of the boundary between an outer peripheral surface (220) of the pipe member (22) and the first semi-conductive layer (23) and the boundary between an inner peripheral surface (240) of the buried member (24) and the second semi-conductive layer (25) has an unbonded portion.

[0045] [2] The power cable connection device (1) described in [1], wherein at least one of the boundaries between the outer peripheral surface (220) of the pipe member (22) and the first semiconductive layer (23) and the boundary between the inner peripheral surface (240) of the embedded member (24) and the second semiconductive layer (25) has an unfixed portion in the region where the inner peripheral surface of the embedded member (24) in the axial direction is formed.

[0046] [3] The power cable connection device (1) according to [1] or [2], wherein a release agent (5) is present at at least one of the boundaries between the outer peripheral surface (220) of the pipe member (22) and the first semiconductive layer (23) and the boundary between the inner peripheral surface (240) of the embedded member (24) and the second semiconductive layer (25).

[0047] [4] The power cable connection device (1) according to any one of [1] to [3], wherein the pipe member (22) has a plurality of holes (221) formed therein that penetrate the pipe member (22) in the radial direction.

[0048] Although the embodiments of the present invention have been described above, the invention according to the claims is not limited to the above-described embodiments. It should be noted that not all of the combinations of features described in the embodiments are necessarily essential to the means for solving the problems of the invention. Furthermore, the present invention can be appropriately modified and implemented within the scope of its spirit. [Explanation of symbols]

[0049] 10...Power cable 21...Insulator tube 22...Pipe member 220...Outer surface of the pipe member 221...hole 23...First semiconductive layer 24...Buried material 240...Inner surface of buried member 25...Second semiconductive layer 5...Mold release agent R…Area R

Claims

1. a porcelain tube into which a power cable is inserted; a pipe member having higher rigidity than the porcelain bushing, the pipe member being disposed inside the porcelain bushing so as to face the power cable; an embedded member that is disposed at a position closer to an outer periphery of the pipe member, that is partially embedded in the porcelain bushing, and that has higher rigidity than the porcelain bushing; a first semiconductive layer provided between the pipe member and the porcelain bushing; a second semiconductive layer provided between the embedded member and the porcelain bushing, at least one of a boundary between an outer circumferential surface of the pipe member and the first semiconductive layer and a boundary between an inner circumferential surface of the embedded member and the second semiconductive layer has a stress relaxation layer; The pipe member has a number of holes formed therein that penetrate the pipe member in the radial direction. Power cable connection device.

2. The stress relaxation layer is made of insulating rubber having lower elasticity than the porcelain bushing. The power cable connection device according to claim 1 .

3. The elastic modulus of the stress relaxation layer is 1 MPa or less. The power cable connection device according to claim 1 or 2.

4. the stress relaxation layer is provided at the boundary between the outer circumferential surface of the pipe member and the first semiconductive layer, the stress relaxation layer has a linear expansion coefficient between the linear expansion coefficient of the pipe member and the linear expansion coefficient of the first semiconductive layer; The power cable connection device according to any one of claims 1 to 3.

5. the stress relaxation layer is provided at the boundary between the inner circumferential surface of the embedded member and the second semiconductive layer, the stress relaxation layer has a linear expansion coefficient between the linear expansion coefficient of the embedded member and the linear expansion coefficient of the second semiconductive layer; The power cable connection device according to any one of claims 1 to 4.

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