Power cable connection structure

Abstract

To provide a power cable connection structure capable of suppressing breakage of a support member.SOLUTION: A power cable connection structure 1 comprises: a power cable 41 in which a cable conductor 411 is exposed on a cable distal end side; a bushing unit 2 which includes an inner conductor 22 which is electrically connected with the cable conductor 411, a bushing 21 in which the inner conductor 22 is embedded, and an insertion hole 20 formed therein into which a distal end portion of the power cable 41 is inserted; a stress cone 44 which is mounted to the power cable 41; a pressing device 45 including a presser 451 which is disposed on a cable proximal end side of the stress cone 44 and presses the stress cone 44 toward the cable distal end side and an energization member 453 which energizes the presser 451 toward the cable distal end side; a support member which is fixed to the bushing unit 2 and supports the pressing device 45; and a damper 47 which absorbs a force which acts on the support member when the presser 451 is displaced to the cable proximal end side against an energizing force of the energization member 453.SELECTED DRAWING: Figure 2

Description

[Technical Field]

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

[0002] Patent Document 1 discloses a cable connection structure including a porcelain bushing unit, a power cable, a stress cone, a pressing device, and a support member. The porcelain bushing unit has an inner conductor embedded therein and an insertion hole formed therein. The tip of the power cable is inserted into the insertion hole of the porcelain bushing unit, and the cable conductor is electrically connected to the inner conductor. The stress cone is attached to the power cable and is made of rubber. The pressing device is attached to the power cable and presses the stress cone toward the tip of the cable. The support member is fixed to the porcelain bushing unit and supports the pressing device.

[0003] In the power cable connection structure described in Patent Document 1, the pressing device includes a plunger, multiple shafts, multiple springs, and a washer. The plunger abuts against the stress cone and presses the stress cone toward the cable tip. The multiple shafts protrude from the plunger toward the cable base end. The multiple springs are attached to each of the multiple shafts and urge the plunger toward the cable tip. The washer is located on the cable base end side of the spring and is supported by the support member by abutting against a step formed on the support member. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2012-029497 Summary of the Invention [Problem to be solved by the invention]

[0005] In the power cable connection structure described in Patent Document 1, when an arc discharge occurs in the space around the current-carrying portion between the inner conductor of the insulator tube unit and the cable conductor of the power cable, the temperature in the space rises, which can increase the internal pressure. If the internal pressure in this space increases, the power cable, the stress cone, and the plunger of the pressing device are pressed toward the base end of the cable, and a strong force is applied to the support member through the washer of the pressing device, and in the worst case scenario, the support member may break.

[0006] The present invention has been made in view of the above circumstances, and has an object to provide a power cable connection structure that can suppress breakage of a support member. [Means for solving the problem]

[0007] In order to achieve the above-mentioned object, the present invention provides a power cable connection structure comprising: a power cable having an exposed cable conductor at the tip end of the cable; an insulator tube unit having an inner conductor electrically connected to the cable conductor and an insulator tube in which the inner conductor is embedded, the insulator tube unit having an insertion hole into which the tip end of the power cable is inserted; a stress cone attached to the power cable; a pressing device arranged on the cable base end side of the stress cone and having a pusher that pushes the stress cone toward the cable tip end and a biasing member that biases the pusher toward the cable tip end; a support member fixed to the insulator tube unit and supporting the pressing device; and a damper that absorbs the force acting on the support member when the pusher is displaced toward the cable base end against the biasing force of the biasing member. [Effects of the Invention]

[0008] According to the present invention, it is possible to provide a power cable connection structure that can suppress breakage of the support member. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a cross-sectional view of a power cable connection structure according to an embodiment. [Figure 2]FIG. 2 is an enlarged view of a part of FIG. [Figure 3] 1 is an exploded cross-sectional view of a power cable connection structure according to an embodiment. [Figure 4] 2 is a cross-sectional view perpendicular to the axial direction of the power cable according to the embodiment. FIG. [Figure 5] FIG. 2 is an exploded perspective view of the pressing device according to the embodiment. [Figure 6] FIG. 4 is a partially enlarged cross-sectional view of the power cable connection structure when the damper is in operation in the embodiment. [Figure 7] 4 is a partially enlarged cross-sectional view of the power cable connection structure when the pressure release section is in operation in the embodiment. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0010] [Embodiment Mode] Embodiments of the present invention will be described with reference to Figures 1 to 7. The embodiments described below are shown as preferred specific examples for carrying out the present invention, and although some of the embodiments specifically exemplify various technically preferred aspects, the technical scope of the present invention is not limited to these specific embodiments.

[0011] (Power cable connection structure 1) FIG. 1 is a cross-sectional view of a power cable connection structure 1 according to this embodiment.

[0012] The power cable connection structure 1 is mounted on, for example, a railway vehicle. As shown in Fig. 1, the power cable connection structure 1 electrically connects two power cables 41 to which a high voltage is applied. The power cable connection structure 1 can be installed above an installation surface 10, such as the roof of the railway vehicle, using a fixing member (not shown).

[0013] The power cable connection structure 1 comprises a porcelain tube unit 2 having a porcelain tube 21, a case 3 covering the porcelain tube unit 2, and two cable assemblies 4 having power cables 41 and assembled to the porcelain tube unit 2.

[0014] (porcelain tube unit 2) The porcelain tube unit 2 includes a porcelain tube 21, an internal conductor 22 embedded in the porcelain tube 21, and a plurality of nut members 23. The porcelain tube unit 2 has an insertion hole 20 formed therein into which the tip end of a power cable 41 is inserted. In this embodiment, the porcelain tube unit 2 has two insertion holes 20 formed therein that open toward opposite sides. The tip end of two power cables 41 is inserted into each of the two insertion holes 20. The inner side of the insertion hole 20 is defined by the internal conductor 22, and the opening side is defined by the porcelain tube 21.

[0015] The porcelain bushing 21 is made of an electrically insulating resin such as an epoxy resin, etc. In this embodiment, the porcelain bushing 21 is formed in a generally cylindrical shape and is long in the direction in which the two insertion holes 20 open.

[0016] Fig. 2 is an enlarged view of a portion of Fig. 1. Fig. 3 is an exploded cross-sectional view of the power cable connection structure 1. As shown in Figs. 2 and 3, the inner surface of the porcelain tube 21 that defines the insertion hole 20 has an inclined inner surface 211. The inclined inner surface 211 is formed in a tapered shape so that the diameter increases toward the opening side of the insertion hole 20. A stress cone 44 is pressed against the inclined inner surface 211 by a pressing device 45.

[0017] The porcelain tube 21 is formed integrally with the internal conductor 22 and the nut member 23, for example, by insert molding, in which molten epoxy resin is poured into a mold in which the internal conductor 22 and the nut member 23 are placed and hardened.

[0018] The inner conductor 22 is made of a conductor and is embedded in the porcelain tube 21. As shown in Fig. 1 , the inner conductor 22 electrically connects the cable conductors 411 of the two power cables 41. The inner conductor 22 has two boss portions 221, a connecting portion 222, and two cylindrical wall portions 223.

[0019] The two boss portions 221 are located at the bottom positions of the two insertion holes 20, respectively, and protrude into the two insertion holes 20. Two relay members 100 (described below) attached to the two power cables 41 are fastened to the two boss portions 221 with bolts, respectively. The two boss portions 221 are connected to each other by a connecting portion 222.

[0020] The two cylindrical wall portions 223 extend from the connecting portion 222 to the opening sides of the two insertion holes 20, respectively, and each have a cylindrical shape. The cylindrical wall portion 223 surrounds the connection portion between the power cable 41 and the inner conductor 22. One cylindrical wall portion 223 defines one insertion hole 20, and the other cylindrical wall portion 223 defines the other insertion hole 20.

[0021] The plurality of nut members 23 are embedded on the outer periphery of each insertion hole 20 in the porcelain tube 21. Each nut member 23 is a cap nut provided with an internally threaded hole that opens to the opening side of the insertion hole 20 located on the inner periphery side. A bolt 12 for fixing the porcelain tube unit 2 to the case 3 is screwed into the internally threaded hole of the nut member 23.

[0022] (Case 3) 1 to 3, the case 3 is made of a highly rigid and conductive material such as metal. The case 3 and a cover 46 (described later) are mechanically and electrically connected to each other and are connected to a ground potential during use. The case 3 has two first case members 31 fixed to the porcelain bushing unit 2 and a second case member 32 that covers the porcelain bushing unit 2.

[0023] The first case member 31 is formed in an annular shape. One first case member 31 is fixed to a nut member 23 located on the outer periphery of one insertion hole 20 using a bolt 12, and the other first case member 31 is fixed to a nut member 23 located on the outer periphery of the other insertion hole 20 using a bolt 12.

[0024] The second case member 32 has a cylindrical shape and covers the porcelain tube 21. Both ends of the second case member 32 are fitted into the two first case members 31.

[0025] (Cable assembly 4) As shown in Figures 1 to 3, the cable assembly 4 includes a power cable 41, a connection terminal 42, a stopper 43, a stress cone 44, a pressing device 45, a cover 46, a damper 47, a pressure release section 48, a damper operation detection section 49, and a pressure release detection section 40.

[0026] Hereinafter, the direction in which the central axis C of the power cable 41 extends will be referred to as the cable axial direction. One side in the cable axial direction that is inserted into the insertion hole 20 of the power cable 41 will be referred to as the cable tip side, and the opposite side will be referred to as the cable base side. For example, in Fig. 1, for the cable assembly 4 located on the right side, the left side is the cable tip side and the right side is the cable base side, and for the cable assembly 4 located on the left side, the right side is the cable tip side and the left side is the cable base side.

[0027] Fig. 4 is a cross-sectional view perpendicular to the axial direction of a power cable 41. As shown in Fig. 4, the power cable 41 includes, in order from the center, a cable conductor 411, a cable inner semiconductive layer 412, a cable insulator 413, a cable outer semiconductive layer 414, a cable shield layer 415, and a cable sheath 416.

[0028] The cable conductor 411 is formed, for example, by twisting together multiple wires. The cable inner semiconductive layer 412 and the cable outer semiconductive layer 414 are provided to reduce the concentration of electric fields and are formed, for example, by extruding a polymer material that has been made conductive by dispersing conductive powder such as carbon. The cable insulator 413 and the cable sheath 416 are formed, for example, by extruding an insulating material. The cable shield layer 415 is formed, for example, by a wire wound transversely around the cable outer semiconductive layer 414 and is grounded during use.

[0029] As shown in FIGS. 2 and 3, the power cable 41 is stripped in stages so that the cable conductor 411, the cable insulator 413, the cable outer semiconductive layer 414, and the cable shield layer 415 are exposed in this order from the cable tip.

[0030] The connection terminal 42 has a crimping portion 421 crimped to the cable conductor 411, and an insertion portion 422 extending from the crimping portion 421 in the cable axial direction and inserted into the relay member 100. The crimping portion 421 is mechanically and electrically connected to the cable conductor 411 by being crimped to the cable conductor 411. The insertion portion 422 is inserted into the inside of the cylindrical relay member 100.

[0031] The relay member 100 electrically connects the connection terminal 42 and the internal conductor 22. In this embodiment, the relay member 100 is a so-called tulip contact, but is not limited to this and other contact members may be used. The relay member 100 is fitted onto the connection terminal 42 and fastened to the boss portion 221 with a bolt.

[0032] The stopper 43 is formed in an annular shape and fitted onto the power cable 41. The tip of the stress cone 44 abuts against the surface of the stopper 43 on the cable base end side, and the tubular wall portion 223 of the inner conductor 22 of the porcelain tube unit 2 abuts against the surface on the cable tip end side. The stopper 43 receives a pressing force in the cable axial direction that is applied to the stress cone 44 by a pressing device 45.

[0033] The stress cone 44 is attached to the power cable 41. Specifically, the stress cone 44 is fitted onto the outer periphery of the cable insulator 413 and the cable outer semiconductive layer 414. In this embodiment, the stress cone 44 is composed of two parts, and includes an insulating part 441 on the cable tip side and a semiconductive part 442 on the cable base end side.

[0034] The insulating portion 441 is made of an elastic insulator such as silicone rubber, ethylene propylene rubber (EPM), or ethylene propylene diene rubber (EPDM). The inner periphery of the insulating portion 441 is in contact with the cable insulator 413. The outer periphery of the insulating portion 441 has a tapered first inclined outer surface 441a that narrows in diameter toward the cable tip. When the stress cone 44 is pressed toward the cable tip by the pressing device 45, the first inclined outer surface 441a is brought into close contact with the inclined inner surface 211 of the insertion hole 20 over the entire circumference. As a result, the first space S1 in the insertion hole 20, where the connection portion between the cable conductor 411 and the inner conductor 22 is located, becomes an enclosed space.

[0035] The semiconductive portion 442 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 inner periphery of the semiconductive portion 442 is in contact with the cable outer semiconductive layer 414, and is connected to a ground potential via the cable outer semiconductive layer 414. The semiconductive portion 442 may be grounded to the cover 46 or the like via the pressing device 45. The outer periphery of the semiconductive portion 442 has a tapered second inclined outer surface 442a whose diameter decreases toward the cable base end. The second inclined outer surface 442a is in contact with a plunger 451 (described later) of the pressing device 45, and is the surface that receives the pressing force from the plunger 451.

[0036] The pressing device 45 is disposed on the cable base end side of the stress cone 44 and presses the stress cone 44 toward the cable tip side. The pressing device 45 compresses the stress cone 44 in the cable axial direction, thereby increasing the adhesion between the stress cone 44 and the power cable 41 and the inner surface of the insertion hole 20. The pressing device 45 is formed in a roughly cylindrical shape overall, and is attached to the power cable 41 so that the power cable 41 passes inside it.

[0037] 5 is an exploded perspective view of the pressing device 45. As shown in FIGS. 2, 3, and 5, in this embodiment, the pressing device 45 includes a plunger 451 disposed on the cable base end side of the stress cone 44, a plurality of shafts 452 connected to the plunger 451, a plurality of urging members 453 disposed on the cable base end side of the plunger 451 and urging the plunger 451 toward the cable tip side, and washers 454 disposed on the cable base end side of the plurality of urging members 453. Note that while FIG. 5 illustrates only one set of the shaft 452, the urging member 453, and the damper 47, in reality, there are the same number of sets of the shaft 452, the urging member 453, and the damper 47 as the number of screw holes 451c and shaft insertion holes 454a, respectively, which will be described later.

[0038] The plunger 451 is a member that abuts against the stress cone 44 and presses the stress cone 44 toward the cable tip side. The plunger 451 is formed in a substantially cylindrical shape. The inner peripheral surface 451a of the plunger 451 is formed in a tapered shape so that the diameter decreases toward the cable base end side, and abuts against the second inclined outer surface 442a of the stress cone 44.

[0039] The plunger 451 has an arrangement surface 451b on which the biasing member 453 is arranged. The arrangement surface 451b has an annular shape and faces the cable base end side. A plurality of screw holes 451c are opened in the arrangement surface 451b. In this embodiment, there are eight screw holes 451c, eight shafts 452, eight shaft insertion holes 454a (described later), and eight dampers 47. The plurality of screw holes 451c are formed at equal intervals in the circumferential direction. A plurality of shafts 452 are connected to the plurality of screw holes 451c, respectively.

[0040] The multiple shafts 452 are integrated with the plunger 451 by being screwed into the multiple screw holes 451c, respectively. That is, when the plunger 451 is displaced in the cable axial direction, the multiple shafts 452 are similarly displaced. The multiple shafts 452 are passed through the multiple biasing members 453, respectively, and pass through the washers 454 to protrude further toward the cable base end than the washers 454.

[0041] The biasing member 453 is, for example, a coil spring that is elastically deformable in the cable axial direction. The biasing member 453 is sandwiched between the arrangement surface 451b of the plunger 451 and the surface of the washer 454 on the cable tip side in a state where it is compressed in the cable axial direction beyond its free length. As a result, the restoring force of the multiple biasing members 453 presses the plunger 451 toward the cable tip side, and the plunger 451 presses the stress cone 44. The biasing member 453 is supported by the washer 454 from the cable base end side.

[0042] The washer 454 has an annular shape, and the power cable 41 is passed through the center thereof. A plurality of shaft insertion holes 454a are formed in the washer 454, through which the plurality of shafts 452 are respectively inserted. The washer 454 is supported so as to be immovable relative to the cover 46 by the outer circumferential edge of the surface on the cable base end side abutting against a support portion 462 (described below) provided on the cover 46.

[0043] The cover 46 is formed in a cylindrical shape and surrounds the pressing device 45 from the outer periphery. The second space S2 in the cover 46 where the pressing device 45 is arranged is an enclosed space. That is, the spaces between the multiple members surrounding the second space S2 (for example, between the cover 46 and the first case member 31, between the cover 46 and the power cable 41, etc.) are sealed.

[0044] The cover 46 has a flange 461 that protrudes outward at the end on the cable tip side, and is fixed to the first case member 31 at the flange 461. In this embodiment, the cover 46 is fixed to the first case member 31 using a stud bolt 13 that is threaded into the first case member 31 and a nut 14 that is threaded onto the stud bolt 13. The end of the cover 46 on the cable base end side is in close contact with the power cable 41 via an elastically deformable cylindrical elastic sheet 11.

[0045] A support portion 462 that supports the pressing device 45 is formed on the inner periphery of the cover 46. The support portion 462 is a portion that receives the urging force of the urging member 453 toward the cable base end side. In this embodiment, the support portion 462 is formed in a stepped shape with an inner diameter that decreases toward the cable base end side, and a washer 454 abuts on the surface facing the cable tip side. The support portion 462 is formed around the entire periphery. The cover 46 is fixed to the porcelain bushing unit 2 (in this embodiment, it is indirectly fixed via the first case member 31), and also constitutes a support member that supports the pressing device 45.

[0046] An opposing portion 463 that faces the plurality of shafts 452 in the cable axial direction is formed on the inner periphery of the cover 46 at a position away from the plurality of shafts 452 toward the cable base end side. The opposing portion 463 is formed such that a part of the inner periphery of the cover 46 protrudes inward along the entire circumference.

[0047] The cover 46 has a pressure release section 48 that releases the internal pressure when the internal pressure (i.e., the pressure in the second space S2) rises. The pressure release section 48 has a through-hole 481 formed in the cover 46 and a plug section 482 that closes the through-hole 481. When the internal pressure of the cover 46 rises, the internal pressure within the cover 46 pushes the plug section 482 out of the through-hole 481, and the air within the cover 46 is released from the through-hole 481 to the outside of the cover 46, thereby releasing the internal pressure of the cover 46.

[0048] The through hole 481 is formed, for example, in a cylindrical shape. The through hole 481 may be formed in a tapered shape so that the diameter increases as the through hole 481 approaches the outside of the cover 46. In this embodiment, the through hole 481 is formed to penetrate the facing portion 463 in the cable radial direction. The power cable connection structure 1 is installed on the railway vehicle with the through hole 481 opening downward (i.e., toward the installation surface 10). This prevents moisture from entering the cover 46 through the through hole 481 and also prevents the plug portion 482 from flying off when the pressure release portion 48 is activated.

[0049] Stopper portion 482 is press-fitted into through hole 481. From the viewpoint of ensuring a seal between through hole 481 and stopper portion 482, at least the portion of stopper portion 482 that comes into contact with the inner surface of through hole 481 is preferably made of an elastic material such as rubber. For example, stopper portion 482 may be entirely made of an elastic material such as rubber, or may be made of a main body made of a highly rigid material such as metal and an O-ring or the like attached to the main body. Note that, for example, when power cable connection structure 1 is housed in a case, it is not necessarily necessary to ensure a seal between stopper portion 482 and through hole 481, and stopper portion 482 may be entirely made of a highly rigid material such as metal.

[0050] The configuration of the pressure release portion 48 is not limited to this. For example, a configuration may be adopted in which a portion of the cover 46 is made thin-walled, and the internal pressure of the cover 46 can be released by intentionally breaking this thin-walled portion when the internal pressure of the cover 46 increases. Also, for example, a configuration may be adopted in which a cross-shaped or other notch is made in a portion of the cover 46, and the cover 46 opens from this notch when the internal pressure of the cover 46 increases.

[0051] A plurality of dampers 47 are disposed between the opposing portion 463 and each of the plurality of shafts 452. The dampers 47 absorb the force acting on the cover 46 when the plunger 451 is displaced toward the cable base end against the biasing force of the biasing member 453. The damper 47 may be, for example, a gas damper using a gas such as nitrogen gas, one using an elastic body such as rubber, or one made of steel (for example, a steel material made like a spring). A gas damper containing nitrogen gas is preferable as the damper 47, as it is less susceptible to temperature effects and can be placed in a small space. The operation of the damper 47 will be described later.

[0052] The damper 47 may be in contact with both the facing portion 463 and the shaft 452, or may be in contact with only one of the facing portion 463 and the shaft 452. When the damper 47 is in contact with only one of the facing portion 463 and the shaft 452 and is separated from the other, when the plunger 451 is displaced toward the cable base end against the biasing force of the biasing member 453, the damper 47 is sandwiched between the facing portion 463 and the shaft 452, and the function of the damper 47 is exhibited. From the viewpoint of exhibiting the function of the damper 47 as early as possible, the damper 47 is preferably disposed in a state where it is sandwiched between both the facing portion 463 and the shaft 452.

[0053] The power cable connection structure 1 of this embodiment further includes a damper operation detection unit 49 that detects that the damper 47 has been activated. If the damper 47 is a gas damper, the damper operation detection unit 49 may detect the operation of the damper 47 based on a change in pressure within the damper 47. The damper operation detection unit 49 may also be a switch that is pressed by the displacement of the shaft 452 toward the cable base end when the damper 47 is activated. The damper operation detection unit 49 may also be capable of measuring the distance between the shaft 452 and the opposing portion 463, and may determine that the damper 47 has been activated when this distance becomes equal to or smaller than a predetermined distance. As long as the operation of the damper 47 can be detected, the means for realizing the damper operation detection unit 49 is not limited to the above, and various structures may be employed.

[0054] The damper operation detection unit 49 outputs to the outside the detection result of the operation of the damper 47. For example, the damper operation detection unit 49 outputs an electric signal indicating the operation status of the damper 47 to the driver's seat of the railway vehicle on which the power cable connection structure 1 is mounted, a control center that monitors the operation status of the railway vehicle, or the like.

[0055] The power cable connection structure 1 of this embodiment further includes a pressure release detection unit 40 that detects activation of the pressure release unit 48. The pressure release detection unit 40 can be, for example, a sensor that detects the passage of an object (i.e., the plug 482) slightly outside the through-hole 481. The pressure release detection unit 40 can also be, for example, a sensor that can measure the internal pressure of the cover 46, and can detect activation of the pressure release unit 48 when the internal pressure of the cover 46 rises once and then suddenly returns to atmospheric pressure. Alternatively, the means for realizing the pressure release detection unit 40 is not limited to the above, and various structures can be adopted as long as the activation of the pressure release unit 48 can be detected.

[0056] The pressure release detection unit 40 outputs to the outside the detection result of the operation of the pressure release unit 48. For example, the pressure release detection unit 40 outputs an electric signal indicating the operation status of the pressure release unit 48 to the driver's seat of the railway vehicle on which the power cable connection structure 1 is mounted, a control center that monitors the operation status of the railway vehicle, or the like.

[0057] (Operation of the damper 47 and the pressure release section 48) Next, the operation of the damper 47 and the pressure release section 48 will be described with reference to Figures 6 and 7. Figure 6 is a partially enlarged cross-sectional view of the power cable connection structure 1 when the damper 47 is operating. Figure 7 is a partially enlarged cross-sectional view of the power cable connection structure 1 when the pressure release section 48 is operating.

[0058] The damper 47 and the pressure release part 48 are activated, for example, when an arc discharge occurs due to an abnormal current flow or the like in the first space S1 around the connection part between the power cable 41 and the inner conductor 22. If an arc discharge occurs in the first space S1 and the connection part between the power cable 41 and the inner conductor 22 melts, the temperature of the first space S1 rises, and the pressure in the first space S1 also rises.

[0059] 6, when the pressure in the first space S1 increases, a force F (for example, a load of 20 kN or more and 200 kN or less) acts on the power cable 41, the stress cone 44, and the plunger 451 toward the cable base end due to the pressure in the first space S1, displacing the power cable 41, the stress cone 44, and the plunger 451 toward the cable base end. At this time, if the damper 47 were not present, the force F acting on the power cable 41, the stress cone 44, and the plunger 451 would be concentrated on the support portion 462 of the cover 46 via the biasing member 453 and the washer 454, and if this force F becomes excessive (i.e., exceeds the tensile strength of the material constituting the cover 46), there is a risk that the cover 46 will not be able to withstand it and will break.

[0060] On the other hand, in this embodiment, when the power cable 41, the stress cone 44, and the plunger 451 attempt to be displaced toward the cable base end side by the force F, each damper 47 is compressed between the opposing portion 463 and each shaft 452, and the force F is absorbed by the damper 47. Therefore, the force F is prevented from being transmitted to the cover 46, and the breakage of the cover 46 is prevented.

[0061] Furthermore, when the stress cone 44 is pushed toward the cable base end due to an increase in internal pressure in the first space S1, the first space S1 can communicate with the second space S2. As a result, the pressure in the first space S1 escapes to the second space S2, and the pressure in the second space S2 increases. If the pressure in the second space S2 increases excessively, the plug portion 482 is pushed out from the through hole 481 toward the installation surface 10 (i.e., the pressure release portion 48 is activated). As a result, the spaces inside and outside the cover 46 communicate with each other via the through hole 481, and the internal pressure of the cover 46 is released. As described above, the damper 47 and the pressure release section 48 operate.

[0062] (Actions and Effects of the Embodiments) The power cable connection structure 1 of this embodiment includes a damper 47 that absorbs the impact (i.e., force F) that acts on the cover 46 serving as a support member when the plunger 451 is displaced toward the cable base end against the biasing force of the biasing member 453. Therefore, even if the internal pressure of the first space S1 that accommodates the connection portion between the power cable 41 and the inner conductor 22 increases and the power cable 41, stress cone 44, and plunger 451 are pressed toward the cable base end, the application of a strong force to the support member (cover 46 in this embodiment) that supports the pressing device 45 is suppressed, and breakage of the support member is suppressed. Furthermore, even if the support member breaks, the power cable connection structure 1 of this embodiment prevents the broken support member from flying out of the power cable connection structure 1 because the damper 47 absorbs the impact.

[0063] The support member is a cover 46 that surrounds the pressing device 45 from the outer periphery. The pressing device 45 further includes a washer 454 that is disposed on the cable base end side of the biasing member 453 and supported by the cover 46, and a plurality of shafts 452 that are connected to the plunger 451 and pass through the washer 454. The damper 47 is disposed between at least one of the plurality of shafts 452 and the cover 46 in the cable axial direction. This allows the space on the cable base end side of the plurality of shafts 452 to be effectively used as an arrangement space for the damper 47, and prevents the power cable connection structure 1 from becoming large.

[0064] The cover 46 also has a pressure release section 48 that releases the internal pressure when the internal pressure increases, thereby preventing the internal pressure of the cover 46 from becoming excessive.

[0065] Furthermore, pressure release section 48 has a through hole 481 formed in cover 46 and a plug section 482 that closes through hole 481. Therefore, pressure release section 48 can be realized with a simple structure.

[0066] Furthermore, through-hole 481 is formed to open vertically downward, which prevents moisture from penetrating from the outside to the inside of cover 46 through through-hole 481 and also prevents stopper portion 482 from scattering.

[0067] Moreover, the power cable connection structure 1 of this embodiment further includes a damper operation detection unit 49 that detects the operation of the damper 47. As described above, the damper 47 can be activated in response to an abnormality in the electrical current between the power cable 41 and the inner conductor 22, and by detecting the operation of the damper 47, it is possible to detect the abnormality in the electrical current.

[0068] The power cable connection structure 1 of this embodiment further includes a pressure release detection unit 40 that detects activation of the pressure release unit 48. As described above, the pressure release unit 48 can be activated in response to an abnormality in electrical conduction between the power cable 41 and the inner conductor 22, and detecting the activation of the pressure release unit 48 makes it possible to detect the abnormality in electrical conduction.

[0069] As described above, according to this embodiment, it is possible to provide a power cable connection structure that can suppress breakage of the support member.

[0070] [Variations] Possible modifications of the power cable connection structure 1 according to the embodiment will be described.

[0071] In the embodiment, the two insertion holes 20 of the porcelain tube unit 2 are opened to face in opposite directions, but this is not limiting. For example, the opening direction of one insertion hole 20 and the opening direction of the other insertion hole 20 may be in a direction that intersects with each other.

[0072] Furthermore, the number of the porcelain bushing unit 2 is not particularly limited as long as it has at least one insertion hole 20. For example, the porcelain bushing unit 2 may be a so-called cable head having only one insertion hole 20. In a cable head, the porcelain bushing is not covered by a case, and the outer circumferential surface of the porcelain bushing is formed in a wavy shape to ensure a creepage distance. Furthermore, the porcelain bushing unit 2 may have three or more insertion holes 20 formed therein, and may electrically connect three or more power cables 41.

[0073] Furthermore, in the embodiment, the pressing device 45 is supported by the cover 46 by the washer 454 abutting against a stepped portion of the cover 46, but this is not limiting. For example, a male thread may be formed on the outer peripheral surface of the washer 454, and the washer 454 may be supported by the cover 46 by screwing into a female thread formed on the inner peripheral surface 451 a of the cover 46. Furthermore, the washer 454 may be supported by the cover 46 by bolting, welding, or the like.

[0074] Furthermore, in the embodiment, the plurality of dampers 47 are arranged between each of the plurality of shafts 452 and the opposing portion 463 of the cover 46, but this is not limiting. For example, the dampers 47 may be arranged between some of the plurality of shafts 452 and the opposing portion 463. However, if the dampers 47 are arranged only between one shaft 452 and the opposing portion 463, for example, it is difficult for the dampers 47 to receive the load acting from the plunger 451 in a balanced manner, and there is also a risk that the shock absorption capacity of the dampers 47 will be insufficient. Therefore, it is preferable to arrange the dampers 47 between the plurality of shafts 452 and the opposing portion 463.

[0075] Furthermore, when the damper 47 is made of an elastic body or the like, the damper 47 may be formed in an annular shape, and one damper 47 may be sandwiched between a plurality of shafts 452 and the cover 46 .

[0076] Furthermore, the damper 47 may be disposed between the washer 454 and the plunger 451 (for example, at a location where the shaft 452 is not present).

[0077] Furthermore, the pressing device 45 does not need to have the washer 454. In this case, for example, a configuration may be adopted in which the cable base end side of the urging member 453 is supported by directly contacting the cover 46. In this case, the damper 47 may be disposed at a location between the cover 46 and the plunger 451 where the urging member 453 is not present.

[0078] Furthermore, pressure release portion 48 may be provided at multiple locations on cover 46. However, from the standpoint of preventing plug portion 482 from scattering, it is preferable to provide pressure release portion 48 at only one location on cover 46.

[0079] (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.

[0080] [1] A power cable connection structure 1 comprising: a power cable 41 having a cable conductor 411 exposed at the cable tip end; an insulator tube unit 2 having an inner conductor 22 electrically connected to the cable conductor 411 and a porcelain tube 21 in which the inner conductor 22 is embedded, the insulator tube unit 2 having an insertion hole 20 into which the tip end of the power cable 41 is inserted; a stress cone 44 attached to the power cable 41; a pressing device 45 having a plunger 451 arranged on the cable base end side of the stress cone 44 and pressing the stress cone 44 toward the cable tip end side, and a biasing member 453 biasing the plunger 451 toward the cable tip end side; a support member fixed to the insulator tube unit 2 and supporting the pressing device 45; and a damper 47 absorbing a force acting on the support member when the plunger 451 is displaced toward the cable base end against the biasing force of the biasing member 453.

[0081] [2] The power cable connection structure 1 described in [1], wherein the support member is a cover 46 that surrounds the pressing device 45 from the outer periphery, the pressing device 45 further includes a washer 454 that is arranged on the cable base end side of the biasing member 453 and is supported by the cover 46, and a plurality of shafts 452 that are connected to the plunger 451 and pass through the washer 454, and the damper 47 is arranged between at least one of the plurality of shafts 452 and the cover 46 in the cable axial direction.

[0082] [3] The power cable connection structure 1 according to [1] or [2], further comprising a cover 46 surrounding the pressing device 45 from the outer periphery, the cover 46 having a pressure release section 48 that releases internal pressure when the internal pressure rises.

[0083] [4] The power cable connection structure 1 described in [3], wherein the pressure release portion 48 has a through hole 481 formed in the cover 46 and a plug portion 482 that closes the through hole 481.

[0084] [5] The power cable connection structure 1 according to [4], wherein the through hole 481 is formed so as to open downward in the vertical direction.

[0085] [6] The power cable connection structure 1 according to any one of [1] to [5], further comprising a damper operation detection unit 49 that detects that the damper 47 has been activated.

[0086] [7] The power cable connection structure 1 according to any one of [3] to [5], further comprising a pressure release detection unit 40 that detects that the pressure release unit 48 has been activated.

[0087] (Addendum) 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]

[0088] 1...Power cable connection structure 2...Porcelain tube unit 20...Insertion hole 21...Insulator 22...Inner conductor 40...Pressure release detection unit 41...Power cable 411...Cable conductor 44...Stress cone 45...Pressing device 451...Press 452...shaft 453... Urging member 454...Washer 46...Cover 47...Damper 48...Pressure relief section 481...Through hole 482...Plug part 49...Damper operation detection unit

Claims

1. a power cable having an exposed cable conductor at the tip of the cable; a porcelain bushing unit including an inner conductor electrically connected to the cable conductor and an inner conductor-embedded porcelain bushing unit having an insertion hole into which a tip end of the power cable is inserted; a stress cone attached to the power cable; a pressing device having a pusher disposed on the cable base end side of the stress cone and pressing the stress cone toward the cable tip side, and a biasing member that biases the pusher toward the cable tip side; a support member fixed to the porcelain bushing unit and supporting the pressing device; a damper that absorbs the force acting on the support member when the pusher is displaced toward the cable base end against the biasing force of the biasing member. Power cable connection structure.

2. the support member is a cover that surrounds the pressing device from the outer periphery side, the pressing device further includes a washer disposed on the cable base end side of the biasing member and supported by the cover, and a plurality of shafts connected to the plunger and passing through the washer, The damper is disposed between at least one of the shafts and the cover in the cable axial direction. The power cable connection structure according to claim 1 .

3. a cover that surrounds the pressing device from an outer periphery side; The cover has a pressure release portion that releases internal pressure when the internal pressure increases. The power cable connection structure according to claim 1 or 2.

4. The pressure release portion has a through hole formed in the cover and a plug portion that closes the through hole. The power cable connection structure according to claim 3 .

5. The through hole is formed to open downward in the vertical direction. The power cable connection structure according to claim 4 .

6. Further, a damper operation detection unit is provided to detect that the damper has been operated. The power cable connection structure according to claim 1 or 2.

7. Further comprising a pressure release detection unit that detects that the pressure release unit has been activated. The power cable connection structure according to claim 3 .

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