Cable connection structure

Abstract

To provide a cable connection structure capable of suppressing occurrence of dielectric breakdown in a high stress portion sandwiched between a pipe member and an embedded member in a radial direction in a bushing tube.SOLUTION: A cable connection structure includes: a pipe member disposed on an outer peripheral side of a power cable; a bushing disposed on an outer peripheral side of the pipe member and made of a rubber material; and an embedded member embedded in the bushing. The bushing includes a high-stress portion sandwiched between the pipe member and the embedded member in a radial direction. When S-N characteristics of the high-stress portion are measured, a stress-piece amplitude σ is 1.0 MPa or more when the number of repetitions N is 107.SELECTED DRAWING: Figure 1

Description

[Technical Field]

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

[0002] Patent Document 1 discloses a cable connection structure. The cable connection structure is a component for connecting a power cable to other electric wires, etc. The cable connection structure includes a pipe member arranged on the outer periphery of the power cable, a porcelain bushing arranged on the outer periphery of the pipe member, and an embedded member embedded in the porcelain bushing. The porcelain bushing is made of a rubber material. The pipe member and the embedded member are made of metal. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2022-128719 Summary of the Invention [Problem to be solved by the invention]

[0004] The porcelain bushing has a portion (hereinafter referred to as a high stress portion) that is sandwiched between the pipe member and the embedded member in the radial direction. The high stress portion is subjected to electrical stress and mechanical stress. As a result of research, the inventors have found that if a foreign object is present in the high stress portion, dielectric breakdown is likely to occur in the high stress portion.

[0005] In one aspect of the present disclosure, it is preferable to provide a cable connection structure that can suppress the occurrence of dielectric breakdown in a high stress portion. [Means for solving the problem]

[0006] One aspect of the present disclosure is a power cable including a pipe member arranged on an outer circumferential side of a power cable, a porcelain tube made of a rubber material arranged on the outer circumferential side of the pipe member, and an embedded member embedded in the porcelain tube, wherein the porcelain tube has a high stress portion sandwiched in a radial direction between the pipe member and the embedded member, and when an SN characteristic of the high stress portion is measured, the number of repetitions N is 10 7 The cable connection structure has a stress piece amplitude σ of 1.0 MPa or more when A cable connection structure that is one aspect of the present disclosure can suppress the occurrence of dielectric breakdown in high stress areas.

[0007] Another aspect of the present disclosure is a cable connection structure comprising: a pipe member arranged on the outer periphery of a power cable; a porcelain tube made of a rubber material arranged on the outer periphery of the pipe member; and an embedded member embedded in the porcelain tube, wherein the porcelain tube has a high-stress portion radially sandwiched between the pipe member and the embedded member, and the high-stress portion does not contain foreign matter having a size of 1 μm or more. A cable connection structure that is another aspect of the present disclosure can suppress the occurrence of dielectric breakdown in high stress areas. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a side cross-sectional view illustrating the configuration of a cable connection structure according to a first embodiment. [Figure 2] FIG. 2 is an enlarged cross-sectional view showing the periphery of a high stress portion in FIG. 1. [Figure 3] FIG. 1 is a plan view showing the shape and size of a dumbbell test piece. [Figure 4] 1 is a graph showing the transition of stress applied to a dumbbell test piece when measuring the SN characteristics. [Figure 5] 10 is a graph showing the relationship between the number of repetitions N and the stress piece amplitude σ. [Figure 6] FIG. 2 is a block diagram showing the configuration of an injection molding device. [Figure 7] FIG. 2 is an explanatory diagram illustrating the configuration and functions of a measurement unit. [Figure 8] Fig. 8A is an explanatory diagram showing a state in which the two-component mixed liquid rubber flowing inside the connection part does not contain foreign matter, and Fig. 8B is an explanatory diagram showing measurement data acquired by the measurement unit and transmitted to the determination unit in the state shown in Fig. 8A. [Figure 9] Fig. 9A is an explanatory diagram showing a state in which foreign matter is contained in the two-component mixed liquid rubber flowing inside the connection part, and Fig. 9B is an explanatory diagram showing measurement data acquired by the measurement part and transmitted to the determination part in the state shown in Fig. 9A. [Figure 10] FIG. 10 is a side cross-sectional view showing the position and movement direction of the ultrasonic sensor when a second foreign object measurement is performed. [Figure 11] 10 is an orthogonal cross-sectional view showing the position and movement direction of the ultrasonic sensor when a second foreign object measurement is performed. FIG. [Figure 12] 1 is a graph showing the SN characteristics measured for a dumbbell test piece DA that does not contain foreign matter and a dumbbell test piece DB that contains foreign matter. DETAILED DESCRIPTION OF THE INVENTION

[0009] Exemplary embodiments of the present disclosure will now be described with reference to the drawings. First Embodiment 1. Configuration of cable connection structure 1 The configuration of a cable connection structure 1 will be described with reference to Figs. 1 and 2. The cable connection structure 1 is a component for connecting a power cable 10 to other electric wires, etc. The cable connection structure 1 is attached to the roof of a railway vehicle, for example. The cable connection structure 1 can be used for electrical connections between adjacent railway vehicles, electrical connections with pantographs, etc.

[0010] (1-1) Overall configuration of cable connection structure 1 The cable connection structure 1 is a component that is attached near the end of a power cable 10. As shown in Figure 1, the cable connection structure 1 includes a main body 3, a flange 5, a cover 7, a sealing portion 8, and a connection portion 9.

[0011] (1-2) Configuration of the main body 3 The main body 3 is a member that ensures electrical insulation between the power cable 10 and members arranged around the power cable 10. The axial direction of the power cable 10 is defined as the axial direction X. In the axial direction X, the side of the connection portion 9 is defined as the tip side X1. The tip side X1 is the tip side of the power cable 10. The side opposite the tip side X1 is defined as the base side X2.

[0012] As shown in FIG. 1 , the main body 3 includes a porcelain tube 11, a pipe member 13, a first semiconductor layer 15, an embedded member 17, a second semiconductor layer 19, and a third semiconductor layer 21. The porcelain tube 11 is a tubular member. The axial direction of the porcelain tube 11 is parallel to the axial direction X. The power cable 10 is inserted inside the porcelain tube 11. Therefore, the porcelain tube 11 is disposed on the outer circumferential side of the power cable 10. The outer circumferential side refers to the side that is located in a radial direction of the power cable 10 and away from the center of the power cable 10. The porcelain tube 11 extends to the tip of the power cable 10 at its tip side X1. The porcelain tube 11 extends to the inside of the cover 7 at its base side X2. The porcelain tube 11 is made of a rubber material. Examples of the rubber material include silicone rubber.

[0013] The porcelain tube 11 has a plurality of umbrella portions 11A. The umbrella portions 11A are formed on the outer peripheral surface of the porcelain tube 11 in a portion not covered by the flange 5 and the cover 7. The umbrella portions 11A protrude toward the outer peripheral side. When viewed from a certain viewpoint in the axial direction X, the umbrella portions 11A have an annular shape. The plurality of umbrella portions 11A are arranged at predetermined intervals along the axial direction X. By providing a plurality of umbrella portions 11A, the creeping distance on the outer peripheral surface of the porcelain tube 11 is increased. A long creeping distance can suppress creeping discharge along the outer peripheral surface of the porcelain tube 11.

[0014] The pipe member 13 is a cylindrical member. The axial direction of the pipe member 13 is parallel to the axial direction X. The pipe member 13 is arranged on the inner periphery side of the porcelain bushing 11. Therefore, the porcelain bushing 11 is arranged on the outer periphery side of the pipe member 13. The power cable 10 is inserted inside the pipe member 13. Therefore, the pipe member 13 is arranged on the outer periphery side of the power cable 10.

[0015] The pipe member 13 protrudes further on the tip side X1 than the porcelain tube 11 and the power cable 10. The end of the base side X2 of the pipe member 13 and the end of the base side X2 of the buried member 17 are at approximately the same position in the axial direction X.

[0016] The inner diameter of the pipe member 13 is larger than the outer diameter of the power cable 10. This makes it easy to insert the power cable 10 into the inside of the pipe member 13. The pipe member 13 is made of, for example, a material that is more rigid than the porcelain tube 11. Examples of materials for the pipe member 13 include metals. Examples of metals include brass and aluminum alloys.

[0017] The first semiconductor layer 15 is provided so as to be interposed between the pipe member 13 and the porcelain tube 11. The first semiconductor layer 15 extends on the tip side X1 to near the tips of the power cable 10 and the porcelain tube 11. The first semiconductor layer 15 extends further toward the base side X2 than the pipe member 13. The portion of the first semiconductor layer 15 that extends further toward the base side X2 than the pipe member 13 is disposed so as to be interposed between the porcelain tube 11 and the power cable 10.

[0018] The first semiconductor layer 15 is made of, for example, an elastic semiconductive material. The first semiconductor layer 15 is made of, for example, a material in which conductive powder is dispersed in a matrix. Examples of the matrix include silicone rubber, EPM, and EPDM. Examples of the conductive powder include carbon. The first semiconductor layer 15 prevents the porcelain tube 11 from deteriorating due to the concentration of an electric field near the inner circumferential surface of the porcelain tube 11.

[0019] The embedded member 17 includes a tubular portion 17A and a flange portion 17B. The tubular portion 17A has a cylindrical shape. The axial direction of the tubular portion 17A is parallel to the axial direction X. The flange portion 17B is located closer to the base end X2 than the tubular portion 17A. When viewed from a viewpoint in the axial direction X, the flange portion 17B has an annular shape. The flange portion 17B protrudes more radially outward than the tubular portion 17A.

[0020] The embedded member 17 is arranged on the outer periphery of the base end side X2 of the pipe member 13. The embedded member 17 is arranged on the outer periphery of the power cable 10 and the first semiconductor layer 15. Most of the embedded member 17 is embedded in the porcelain tube 11. However, a mating surface portion 17C of the embedded member 17 is not embedded in the porcelain tube 11 and is exposed. The mating surface portion 17C is the surface of the base end side X2 of the flange portion 17B. A female screw hole 31 is provided in the flange portion 17B. The female screw hole 31 opens at the mating surface portion 17C.

[0021] The embedded member 17 faces the pipe member 13 in the radial direction, with the first semiconductor layer 15, the porcelain tube 11, and the second semiconductor layer 19 interposed therebetween. The radial direction is the radial direction of the power cable 10. The embedded member 17 is made of, for example, a material that is more rigid than the porcelain tube 11. Examples of materials for the embedded member 17 include metals. Examples of metals include brass and aluminum alloys. For example, when the cable connection structure 1 is used, the embedded member 17 is connected to a ground potential. It is preferable that the linear expansion coefficients of the embedded member 17 and the pipe member 13 are each smaller than the linear expansion coefficient of the porcelain tube 11.

[0022] A portion of the second semiconductor layer 19 is provided so as to be interposed between the embedded member 17 and the porcelain tube 11. A portion of the second semiconductor layer 19 extends further toward the base end side X2 than the embedded member 17, and is provided so as to be interposed between the flange 5 and the porcelain tube 11. A portion of the second semiconductor layer 19 extends further toward the base end side X2 than the flange 5, and is in contact with the porcelain tube 11.

[0023] Examples of materials for the second semiconductor layer 19 include the same as the materials for the first semiconductor layer 15. The second semiconductor layer 19 suppresses deterioration of the porcelain tube 11 due to concentration of an electric field near the surface of the porcelain tube 11 facing the embedded member 17.

[0024] The third semiconductor layer 21 is provided so as to be interposed between the portion of the porcelain tube 11 on the base end side X2 and the power cable 10. Examples of materials for the third semiconductor layer 21 include the same materials as those for the first semiconductor layer 15. The third semiconductor layer 21 suppresses deterioration of the porcelain tube 11 due to concentration of an electric field near the inner circumferential surface of the porcelain tube 11.

[0025] (1-3) Configuration of flange 5 The flange 5 is a plate-shaped member. The thickness direction of the flange 5 is parallel to the axial direction X. When viewed from a certain viewpoint in the axial direction X, the flange 5 has an annular shape. The flange 5 is located between the embedded member 17 and the cover 7 in the axial direction X. The flange 5 is provided on the outer periphery side of the porcelain tube 11 and the second semiconductor layer 19. The flange 5 protrudes further outward than other parts of the main body 3.

[0026] The flange 5 is in contact with the mating surface portion 17C. The flange 5 has a bolt hole 33 formed therein. The bolt hole 33 penetrates the flange 5 in the axial direction X. The flange 5 is fixed to the embedded member 17 by passing a bolt 35 through the bolt hole 33 from the base end side X2 and screwing it into the female threaded hole 31.

[0027] Bolt holes 34 are provided in flange 5. Bolt holes 34 penetrate flange 5 in axial direction X. Bolt holes 34 are provided on the outer circumferential side of bolt holes 33. Flange 5 is fixed to a workpiece (not shown). Bolt holes 34 are used when fixing flange 5 to the workpiece using bolts. The workpiece is, for example, a wall portion that constitutes the roof of a railway vehicle.

[0028] The flange 5 is provided with a female threaded hole 37. The female threaded hole 37 opens on the surface of the flange 5 on the base end side X2. The female threaded hole 37 is provided on the outer circumferential side of the bolt hole 33 and on the inner circumferential side of the bolt hole 34. The flange 5 may be made of a material similar to that of the embedded member 17.

[0029] (1-4) Configuration of the cover 7 and the sealing portion 8 The cover 7 has a cylindrical shape. The axial direction of the cover 7 is parallel to the axial direction X. The cover 7 is located on the base end side X2 of the flange 5 in the axial direction X. The cover 7 covers the portion of the main body 3 that is on the base end side X2 of the flange 5 from the outer periphery. The cover 7 has a flange portion 7A on the tip side X1. The flange portion 7A protrudes outer periphery more than other portions of the cover 7.

[0030] The flange 7A has a bolt hole 39. The bolt hole 39 penetrates the flange 7A in the axial direction X. The cover 7 is fixed to the flange 5 by passing a bolt 41 through the bolt hole 39 from the base end side X2 and screwing it into the female threaded hole 37. The cover 7 may be made of a material similar to that of the embedded member 17.

[0031] The sealing portion 8 provides a seal between the end of the cover 7 on the base end side X2 and the power cable 10. The sealing portion 8 is formed, for example, by wrapping an adhesive-provided polyethylene tape, epoxy tape, or the like around the outer periphery of the power cable 10. The sealing portion 8 provides a liquid-tight seal between the cover 7 and the power cable 10, for example.

[0032] (1-5) Configuration of the connection part 9 The connection part 9 is provided on the tip side X1 of the main body 3. The connection part 9 includes a conductor connecting rod 43, a high-voltage shield 45, a fixed terminal 47, and a co-fastening nut 49. The conductor connecting rod 43 is a rod-shaped member. The axial direction of the conductor connecting rod 43 is parallel to the axial direction X. A connection hole 43A is formed in the conductor connecting rod 43. The connection hole 43A is open at an end of the conductor connecting rod 43 on the base side X2. The connection hole 43A extends along the axial direction X.

[0033] At the end of the tip side X1 of the power cable 10, the conductor portion 10A is not covered with an insulating coating and is exposed. The exposed conductor portion 10A is inserted into the connection hole 43A. The portion of the conductor connecting rod 43 that surrounds the connection hole 43A is crimped toward the conductor portion 10A. This electrically connects the conductor connecting rod 43 and the power cable 10.

[0034] A base end side X2 portion of the conductor connecting rod 43 is housed inside the pipe member 13. A male thread portion 43B is provided on a tip end side X1 portion of the conductor connecting rod 43. The male thread portion 43B protrudes toward the tip end side X1.

[0035] The high-voltage shield 45 is a cylindrical member with a bottom. The high-voltage shield 45 has a bottom 45A and a side wall 45B. The high-voltage shield 45 is oriented such that the bottom 45A faces the tip side X1. The portion of the pipe member 13 near the tip of the tip side X1 is not covered by the porcelain tube 11. The side wall 45B covers the portion of the pipe member 13 that is not covered by the porcelain tube 11 from the outer periphery. The portion of the conductor connecting rod 43 on the tip side X1 penetrates the bottom 45A and protrudes further toward the tip side X1 than the high-voltage shield 45.

[0036] The fixed terminal 47 is a plate-shaped member. The thickness direction of the fixed terminal 47 is parallel to the axial direction X. The fixed terminal 47 has a first hole 47A and a second hole 47B. The first hole 47A and the second hole 47B each penetrate the fixed terminal 47 in the thickness direction.

[0037] The fixed terminal 47 is located closer to the tip end X1 than the high-voltage shield 45 and is in contact with the high-voltage shield 45. The male thread portion 43B passes through the first hole 47A and protrudes further to the tip end X1 than the fixed terminal 47. A co-fastening nut 49 is attached to the male thread portion 43B. By tightening the co-fastening nut 49, the fixed terminal 47 and high-voltage shield 45 are co-fastened between the conductor connecting rod 43 and the co-fastening nut 49. The fixed terminal 47, high-voltage shield 45, and conductor connecting rod 43 are electrically connected. The second hole 47B is used to connect the fixed terminal 47 to an electric wire, etc.

[0038] 2. Characteristics of high stress section 11B 1 and 2, the portion of the porcelain tube 11 that is sandwiched radially between the pipe member 13 and the embedded member 17 is designated as the high stress portion 11B. Compared to other portions of the porcelain tube 11 (i.e., portions of the porcelain tube 11 that are not sandwiched between the pipe member 13 and the embedded member 17), the high stress portion 11B is a portion that is more susceptible (higher) to mechanical stress caused by thermal stress due to temperature changes and electrical stress caused by an electric field when a voltage is applied during use. The radial thickness of the high stress portion 11B is 16 mm.

[0039] The SN characteristics of the high stress portion 11B can be measured as follows. First, a sheet-like member is cut out from the high stress portion 11B. The thickness of the sheet-like member is 2 mm. Next, a dumbbell test piece D having the shape and size shown in Figure 3 is cut out from the sheet-like member. The dimensions in Figure 3 are in mm.

[0040] Next, dumbbell test piece D is attached to a testing machine to measure the SN characteristics. The testing machine is an electromagnetic force type micro testing machine (Micro Servo MMT series) manufactured by Shimadzu Corporation. The model number of the testing machine is MMT-250NV-10. The test environment is room temperature, normal humidity, and normal pressure. Room temperature is 25°C.

[0041] When measuring the SN characteristics, stress is repeatedly applied to dumbbell test piece D as shown in Figure 4. The stress changes regularly at a constant period T. The stress waveform is a sine wave. Period T corresponds to 2 Hz. The measurement mode is tensile mode (pulsating). Stress is repeatedly applied until dumbbell test piece D breaks. The stress piece amplitude σ when applying stress is constant within one test. The number of times stress is applied until dumbbell test piece D breaks is defined as the number of repetitions N.

[0042] By performing this test once, one measurement point is obtained, which is a combination of the number of repetitions N and the stress piece amplitude σ. This test is repeated three or more times while changing the value of the stress piece amplitude σ. As a result, a graph is obtained that shows the relationship between the number of repetitions N and the stress piece amplitude σ, as shown in Figure 5. The graph has three or more measurement points.

[0043] Next, as shown in FIG. 5, an approximation curve representing the relationship between the number of repetitions N and the stress piece amplitude σ is calculated based on three or more measurement points. Next, based on the approximation curve, when the number of repetitions N is 10 7 Calculate the stress piece amplitude σ when the number of repetitions N is 10 7 When the stress piece amplitude σ is 1.0 MPa or more, it is preferable that the stress piece amplitude σ is 1.0 MPa or more.

[0044] When measuring the SN characteristics, the level of the stress piece amplitude σ value is 3 or more. The level of the stress piece amplitude σ is determined as follows: A dumbbell test piece D is attached to a testing machine and a tensile test is performed, and the stress at which the dumbbell test piece D breaks (hereinafter referred to as the tensile breaking stress) is measured. 90% of the obtained tensile breaking stress is set as the first level of the stress piece amplitude σ. With the stress piece amplitude σ set as the first level, the number of repetitions N is measured using the method described above.

[0045] Next, the second level stress piece amplitude σ is set based on the number of repetitions N when the stress piece amplitude σ is at the first level, the first level stress piece amplitude σ, and the tensile breaking stress. With the stress piece amplitude σ at the second level, the number of repetitions N is measured using the method described above.

[0046] Similarly, the stress piece amplitude σ of the (n+1)th level is set based on the number of repetitions N when the stress piece amplitude σ is at the nth level, the stress piece amplitude σ of the nth level, and the tensile breaking stress. With the stress piece amplitude σ at the (n+1)th level, the number of repetitions N is measured using the method described above. n is a natural number of 2 or greater.

[0047] When observing the high stress portion 11B using an electron microscope, it is preferable that no foreign matter 153 having a size of 1 μm or more is present in the high stress portion 11B. The foreign matter 153 is, for example, a portion that is a different color than the surrounding area. Alternatively, the foreign matter 153 is a portion that has a different elastic modulus than the surrounding area. The size of the foreign matter 153 is the value measured in the direction in which the size is greatest.

[0048] For example, the porcelain bushing 11 including the high stress portion 11B is made of a two-component mixed liquid rubber 105 formed by mixing an A component 113A and a B component 113B. The two-component mixed liquid rubber 105 is, for example, liquid silicone rubber. For example, one of the A component 113A and the B component 113B contains TiO2, a white colorant.

[0049] For example, the foreign matter 153 is a portion that occurs when agent A 113A and agent B 113B are not uniformly mixed and hardening proceeds quickly. The mass ratio of Ti in the foreign matter 153 is M1 mass %. The mass ratio of Ti in the normal portion is M2 mass %. The normal portion is the portion of the high stress portion 11B excluding the foreign matter 153. The method for measuring the mass ratio of Ti is SEM-EDX. The value obtained by dividing M1 by M2 is M1 / M2. The value of M1 / M2 is, for example, 0.6 or less.

[0050] As a method for reducing the amount of foreign matter 153 contained in the high stress portion 11B of the manufactured cable connection structure 1, for example, there is the following defective product exclusion method. In the defective product exclusion method, the amount of foreign matter 153 contained in the high stress portion 11B is measured. Methods for measuring the amount of foreign matter 153 include, for example, the first foreign matter measurement or the second foreign matter measurement described below. If the result of measuring the amount of foreign matter 153 shows that the high stress portion 11B contains a large amount of foreign matter 153, the main body portion 3 including that high stress portion 11B is determined to be defective and is not used in the manufacture of the cable connection structure 1.

[0051] By using this defective product exclusion method, the amount of foreign matter 153 contained in the high stress portion 11B of the manufactured cable connection structure 1 is reduced. For example, the high stress portion 11B of the manufactured cable connection structure 1 will no longer contain foreign matter 153 with a size of 1 μm or more.

[0052] The fewer the foreign matter 153 contained in the high stress portion 11B, the greater the number of repetitions N is. 7 By carrying out the above-described defective product exclusion method, the number of foreign particles 153 contained in the high stress portion 11B of the manufactured cable connection structure 1 is reduced, and the number of repetitions N is 10 7 For example, by performing the above-described defective product exclusion method, the number of repetitions N can be increased to 10 7 When the stress piece amplitude σ is 1.0 MPa or more,

[0053] 3. Manufacturing method of main body 3 (3-1) Configuration of injection molding device 101 For example, an injection molding apparatus 101 shown in Figures 6 and 7 is used to manufacture the main body 3. As shown in Figure 6, the injection molding apparatus 101 includes an injection unit 103. The injection unit 103 is a member that forms and injects two-component mixed liquid rubber 105.

[0054] The injection unit 103 includes a main body 107, a screw 109, and an injection port 111. The main body 107 is a hollow cylindrical member. The screw 109 is housed inside the main body 107. The axial direction of the screw 109 coincides with the axial direction of the main body 107. The screw 109 is rotatable.

[0055] The inside and outside of the main body 107 are connected through the inlet 111. Agent A 113A, which is the main agent of the two-component mixed liquid rubber 105, and agent B 113B, which is a curing agent of the two-component mixed liquid rubber 105, can be fed into the inlet 111. The fed agent A 113A and agent B 113B enter the inside of the main body 107. Agent A 113A and agent B 113B are, for example, silicone polymers.

[0056] Inside main body 107, screw 109 rotates, causing component A 113A and component B 113B to mix, forming two-component mixed liquid rubber 105. Two-component mixed liquid rubber 105 is, for example, liquid silicone rubber.

[0057] As the screw 109 rotates, the two-component mixed liquid rubber 105 flows inside the main body 107 in a flow direction F shown in Figure 6. The two-component mixed liquid rubber 105 is injected from an outlet 115 at one end of the main body 107.

[0058] The injection molding apparatus 101 includes a molding section 121. The molding section 121 includes a mold 123. The molding section 121 is a member that molds the two-component mixed liquid rubber 105 injected from the injection section 103 within the cavity of the mold 123. Within the cavity of the mold 123, the two-component mixed liquid rubber 105 is subjected to primary crosslinking. After the two-component mixed liquid rubber 105 is removed from the mold 123, the two-component mixed liquid rubber 105 is subjected to secondary crosslinking.

[0059] The injection molding apparatus 101 includes a connection part 131. The connection part 131 is a member that connects the injection part 103 and the mold 123. The connection part 131 is a hollow cylindrical member. The two-component mixed liquid rubber 105 injected from the injection part 103 flows inside the connection part 131 in a flow direction F and is introduced into the cavity of the mold 123. The connection part 131 is a flow path for the two-component mixed liquid rubber 105 from the injection part 103 to the mold 123.

[0060] The injection molding apparatus 101 includes a measurement unit 141. The measurement unit 141 is provided outside the connection unit 131. The measurement unit 141 is provided, for example, at a position facing the outer circumferential surface of the connection unit 131. As shown in FIG. 7 , the measurement unit 141 transmits an ultrasonic signal 143 into the inside of the connection unit 131. The ultrasonic signal 143 enters the inside of the two-component mixed liquid rubber 105 flowing inside the connection unit 131.

[0061] The ultrasonic signal 143 is reflected by foreign matter 153 contained in the two-component mixed liquid rubber 105 or the inner surface of the connection portion 131, generating a reflected signal 145. In other words, the reflected signal 145 is a signal generated by the ultrasonic signal 143. The foreign matter 153 is, for example, an early reaction product generated from the component A 113A and the component B 113B. The foreign matter 153 is likely to be generated when the component A 113A and the component B 113B are poorly mixed in the injection portion 103. The foreign matter 153 has a higher viscosity than normal portions of the two-component mixed liquid rubber 105.

[0062] The measurement unit 141 receives the reflected signal 145. For example, when performing an injection molding method, the measurement unit 141 repeatedly transmits an ultrasonic signal 143 and receives a reflected signal 145 at predetermined time intervals. The transmission of the ultrasonic signal 143 and the reception of the reflected signal 145 will be referred to as a first foreign matter measurement below. An example of the measurement unit 141 is an ultrasonic flow meter. An example of the ultrasonic flow meter is an ultrasonic Doppler flow meter.

[0063] The injection molding apparatus 101 includes a determination unit 151. The determination unit 151 includes a calculation device. The calculation device is, for example, a PC. The determination unit 151 can communicate with the measurement unit 141 via wired communication or wireless communication. The determination unit 151 acquires measurement data from the measurement unit 141. The measurement data includes the result of the first foreign matter measurement performed by the measurement unit 141. The measurement data includes the reception result of the reflected signal 145.

[0064] The determination unit 151 stores the measurement data acquired from the measurement unit 141. The determination unit 151 determines whether or not the two-component mixed liquid rubber 105 contains foreign matter 153 based on the measurement data. For example, the determination unit 151 notifies the result of the determination by an image, a sound, or the like. The determination unit 151 also stores the result of the determination. The determination unit 151 also transmits the result of the determination to an external device, or the like.

[0065] The method by which the determination unit 151 determines whether or not the two-component mixed liquid rubber 105 contains foreign matter 153 will be described with reference to Figures 8A, 8B, 9A, and 9B. Figure 8A shows a state in which the two-component mixed liquid rubber 105 flowing inside the connection unit 131 does not contain foreign matter 153. The ultrasonic signal 143 is reflected by an opposite surface 131A, which is on the inner surface of the connection unit 131 opposite the measurement unit 141, and generates a reflected signal 145A. The reflected signal 145A is generated when the ultrasonic signal 143 is reflected by the opposite surface 131A.

[0066] Fig. 8B shows the measurement data acquired by measurement unit 141 and transmitted to determination unit 151 in the state shown in Fig. 8A. Reflected signal 145A appears in the measurement data. In the measurement data, the signal received earlier than reflected signal 145A is the signal received when ultrasonic signal 143 was transmitted. Reflected signal 145B, which will be described later, does not appear in the measurement data shown in Fig. 8A.

[0067] 9A shows a state in which foreign matter 153 is contained in two-component mixed liquid rubber 105 flowing inside connecting portion 131. A part of ultrasonic signal 143 is reflected by foreign matter 153, generating reflected signal 145B. Reflected signal 145B is generated when ultrasonic signal 143, part of reflected signal 145, is reflected by foreign matter 153. In addition, a part of ultrasonic signal 143 is reflected by opposite surface 131A, generating reflected signal 145A.

[0068] Fig. 9B shows the measurement data acquired by measurement unit 141 and transmitted to determination unit 151 in the state shown in Fig. 9A. Reflected signals 145A and 145B appear in the measurement data shown in Fig. 9B. Because foreign object 153 is closer to measurement unit 141 than to opposite surface 131A, measurement unit 141 receives reflected signal 145B earlier than it receives reflected signal 145A.

[0069] The determination unit 151 determines whether or not the reflected signal 145B appears in the measurement data. For example, the determination unit 151 determines whether or not the reflected signal 145B appears in the measurement data by comparing the measurement data with a reference. The reference is, for example, measurement data when there is no foreign matter 153 in the two-component mixed liquid rubber 105, and is stored in advance by the determination unit 151. The reference has, for example, a waveform similar to that of the measurement data shown in FIG. 8B.

[0070] If it is determined that the reflected signal 145B appears in the measurement data, the determination unit 151 determines that the two-component mixed liquid rubber 105 contains a foreign matter 153. If it is determined that the reflected signal 145B does not appear in the measurement data, the determination unit 151 determines that the two-component mixed liquid rubber 105 does not contain a foreign matter 153.

[0071] (3-2) Manufacturing of the main body 3 by the injection molding device 101 The main body 3 can be manufactured using the injection molding device 101 as follows: Agent A 113A and Agent B 113B are charged into the charging port 111. Inside the main body 107, the screw 109 rotates, causing the agents A 113A and B 113B to mix, and the two-component mixed liquid rubber 105 is formed.

[0072] As the screw 109 rotates, the two-component mixed liquid rubber 105 flows in the flow direction F shown in Figure 6 inside the main body 107. The two-component mixed liquid rubber 105 is injected from the outlet 115 of the main body 107.

[0073] The two-component mixed liquid rubber 105 injected from the outlet 115 flows inside the connecting portion 131 and is introduced into the cavity of the mold 123. The pipe member 13, the first semiconductor layer 15, the embedded member 17, the second semiconductor layer 19, and the third semiconductor layer 21 are arranged in advance in the cavity of the mold 123. The two-component mixed liquid rubber 105 becomes the porcelain tube 11 in the cavity of the mold 123. As a result, the main body 3 is obtained. That is, the main body 3 is manufactured by injection molding.

[0074] When the main body 3 is being manufactured, the measurement unit 141 performs a first foreign matter measurement and acquires the measurement data. For example, the first foreign matter measurement is repeatedly performed at predetermined time intervals. The measurement unit 141 transmits the measurement data to the determination unit 151. For example, the measurement unit 141 repeatedly transmits the measurement data at predetermined time intervals. The determination unit 151 determines whether the two-component mixed liquid rubber 105 contains foreign matter 153 based on the measurement data acquired from the measurement unit 141.

[0075] For example, the determination unit 151 repeatedly determines whether or not the two-component mixed liquid rubber 105 contains foreign matter 153 at predetermined time intervals. For example, the determination unit 151 determines whether or not the two-component mixed liquid rubber 105 contains foreign matter 153 every time measurement data is acquired. For example, the determination unit 151 notifies the result of the determination by image, sound, etc. Furthermore, the determination unit 151 stores the result of the determination. Furthermore, the determination unit 151 transmits the result of the determination to an external device, etc.

[0076] If the determination unit 151 determines that the two-component mixed liquid rubber 105 contains foreign matter 153, the main body 3 manufactured immediately before and after that determination is deemed defective and is not used in the manufacture of the cable connection structure 1. As a result, the high stress portion 11B of the manufactured cable connection structure 1 is less likely to contain foreign matter 153. For example, the high stress portion 11B of the manufactured cable connection structure 1 does not contain foreign matter 153 that is 1 μm or larger in size.

[0077] (3-3) Second foreign body measurement After the main body 3 is manufactured, a process (hereinafter referred to as second foreign matter measurement) is performed to measure the foreign matter 153 in the high stress portion 11B using the ultrasonic sensor 201 shown in FIGS.

[0078] When performing the second foreign object measurement, the main body 3 is prepared as shown in Figures 10 and 11. At this time, the power cable 10 is not attached to the main body 3. The ultrasonic sensor 201 is placed inside the pipe member 13. The ultrasonic sensor 201 transmits an ultrasonic signal 243 in the circumferential direction. The ultrasonic signal 243 enters the high stress portion 11B. The ultrasonic signal 243 is reflected by the foreign object 153 contained in the high stress portion 11B or the inner surface of the buried member 17, generating a reflected signal 245. The ultrasonic sensor 201 receives the reflected signal 245.

[0079] The reflected signal 245 reflected by the foreign object 153 and the reflected signal 245 reflected by the inner surface of the embedded member 17 differ in the timing at which the reflected signal 245 is received or in the intensity of the reflected signal 245. Therefore, based on the reflected signal 245, it can be determined whether or not the foreign object 153 is present on the path of the ultrasonic signal 243.

[0080] It is preferable to perform the second foreign object measurement over the entire high stress portion 11B. For example, as shown in Figure 10, the second foreign object measurement is performed repeatedly while moving the ultrasonic sensor 201 in the axial direction X. In this way, the second foreign object measurement can be performed over the entire high stress portion 11B in the axial direction X.

[0081] 11, the second foreign matter measurement is repeatedly performed while the ultrasonic sensor 201 is moved in the circumferential direction θ along the inner circumferential surface of the pipe member 13. In this way, the second foreign matter measurement can be performed over the entire high stress portion 11B in the circumferential direction θ.

[0082] Furthermore, by combining moving the ultrasonic sensor 201 in the axial direction X with moving the ultrasonic sensor 201 in the circumferential direction θ, a second foreign matter measurement can be performed on the high stress portion 11B over the entire area in both the axial direction X and the circumferential direction θ.

[0083] Alternatively, multiple ultrasonic sensors 201 may be arranged along the axial direction X so as to cover the entire high stress portion 11B. In this case, the ultrasonic sensors 201 do not need to be moved in the axial direction X. Furthermore, multiple ultrasonic sensors 201 may be arranged along the inner circumferential surface of the pipe member 13 over the entire circumference in the circumferential direction θ. In this case, the ultrasonic sensors 201 do not need to be moved in the circumferential direction θ. Furthermore, multiple ultrasonic sensors 201 may be arranged along the axial direction X and over the entire circumference in the circumferential direction θ. In this case, the ultrasonic sensors 201 do not need to be moved in the axial direction X and the circumferential direction θ.

[0084] Alternatively, n ultrasonic sensors 201 may be arranged at equal intervals along the circumferential direction θ, where n is a natural number equal to or greater than 2. In this case, by moving each ultrasonic sensor 201 in the circumferential direction θ within a range of (360 / n) degrees, the second foreign matter measurement can be performed on the high stress portion 11B over the entire circumferential direction θ.

[0085] If a foreign object 153 is detected in the high stress portion 11B as a result of the second foreign object measurement, the main body portion 3 including that high stress portion 11B is deemed defective and is not used in the manufacture of the cable connection structure 1. As a result, the high stress portion 11B of the manufactured cable connection structure 1 is unlikely to contain foreign objects 153. For example, the high stress portion 11B of the manufactured cable connection structure 1 does not contain foreign objects 153 that are 1 μm or larger in size.

[0086] 4. Effects of the cable connection structure 1 (1A) When the SN characteristics of the high stress portion 11B in the cable connection structure 1 of the present disclosure were measured, 7 When the stress piece amplitude σ is 1.0 MPa or more, the amount of foreign matter 153 contained in the high stress portion 11B is small.

[0087] The relationship between the SN characteristics of the high stress portion 11B and the presence of the foreign matter 153 in the high stress portion 11B is confirmed by the following test. In the test, a silicone rubber sheet was first produced by press molding. The silicone rubber production conditions were the same as those for producing the porcelain tube 11. The thickness of the sheet was 2 mm. Next, a dumbbell test piece DA having the shape and size shown in Figure 3 was cut out from the sheet. The dumbbell test piece DA did not contain any foreign matter 153.

[0088] Furthermore, dumbbell test specimen DB was produced in a manner basically similar to that of dumbbell test specimen DA. However, when producing dumbbell test specimen DB, foreign matter 153 was embedded in the silicone rubber sheet when it was produced by press molding. When foreign matter 153 was embedded, the sheet was in a state where it had undergone primary crosslinking but not secondary crosslinking. After foreign matter 153 was embedded in the sheet, the sheet was subjected to secondary crosslinking. Furthermore, when cutting out dumbbell test specimen DB from the sheet, the position at which dumbbell test specimen DB was cut out was adjusted so that the embedded foreign matter 153 was aligned with the benchmark line of dumbbell test specimen DB (i.e., the constricted portion of dumbbell test specimen DB).

[0089] The foreign matter 153 embedded in the dumbbell test piece DB was collected from the injection molding machine 101. The foreign matter 153 was a semi-cured silicone rubber. The SN characteristics of the dumbbell test pieces DA and DB were measured using the method described in the section "2. Characteristics of the high stress portion 11B."

[0090] When measuring the SN characteristics of the dumbbell test specimen DA, the stress bar amplitude σ was set to six levels. The six levels of stress bar amplitude σ were 1.32 MPa, 1.54 MPa, 1.53 MPa, 1.45 MPa, 1.53 MPa, and 1.48 MPa, respectively. When measuring the SN characteristics of the dumbbell test specimen DB, the stress bar amplitude σ was set to five levels. The five levels of stress bar amplitude σ were 0.93 MPa, 0.40 MPa, 0.43 MPa, 0.33 MPa, and 0.42 MPa, respectively. The measurement results of the SN characteristics are shown in Figure 12.

[0091] In the case of dumbbell specimen DA, the number of repetitions N is 10 7 On the other hand, in the case of the dumbbell test piece DB, the stress amplitude σ was 1.0 MPa or more when the number of repetitions N was 10 7 The stress amplitude σ was less than 1.0 MPa when the number of repetitions N was 10 7 When the stress piece amplitude σ is 1.0 MPa or more at this time, it is confirmed that there are few foreign particles 153 in the high stress portion 11B. When the SN characteristics of the high stress portion 11B in the cable connection structure 1 of the present disclosure are measured, 7 Since the stress piece amplitude σ at this time is 1.0 MPa or more, the amount of foreign matter 153 contained in the high stress portion 11B is small.

[0092] Furthermore, by analyzing products in which dielectric breakdown actually occurred in high stress portion 11B, the inventors discovered that the cause of dielectric breakdown in high stress portion 11B was foreign matter 153. As described above, in the cable connection structure 1 of the present disclosure, the amount of foreign matter 153 contained in high stress portion 11B is small, so dielectric breakdown is unlikely to occur in high stress portion 11B.

[0093] (1B) In the cable connection structure 1 of the present disclosure, the high stress portion 11B does not include any foreign matter 153 having a size of 1 μm or more. Therefore, dielectric breakdown is unlikely to occur in the high stress portion 11B.

[0094] <Other embodiments> Although the embodiments of the present disclosure have been described above, the present disclosure is not limited to the above-described embodiments and can be implemented in various modified forms.

[0095] (1) It is possible to perform one of the first foreign substance measurement and the second foreign substance measurement without performing the other. Also, foreign substance 153 may be detected by a method different from the first foreign substance measurement and the second foreign substance measurement. (2) The function of one component in each of the above embodiments may be shared among multiple components, or the functions of multiple components may be performed by one component. Also, part of the configuration of each of the above embodiments may be omitted. Furthermore, at least part of the configuration of each of the above embodiments may be added to or substituted for the configuration of another of the above embodiments.

[0096] (3) In addition to the cable connection structure described above, the present disclosure can also be realized in various forms, such as a system that includes the cable connection structure as a component, a method for manufacturing a cable connection structure, and a method for measuring foreign matter. [Explanation of symbols]

[0097] 1...cable connection structure, 3...main body portion, 5...flange, 7...cover, 7A...flange portion, 8...sealing portion, 9...connection portion, 10...power cable, 10A...conductor portion, 11...porcelain tube, 11A...umbrella portion, 11B...high stress portion, 13...pipe member, 15...first semiconductor layer, 17...embedded member, 17A...tube portion, 17B...flange portion, 17C...mating surface portion, 19...second semiconductor layer, 21...third semiconductor layer, 31...female thread hole, 33, 34, 39...bolt hole, 35, 41...bolt, 37...female thread hole, 43...conductor connection rod, 43A...connection hole, 43B...male thread portion, 45...high voltage shield, 45 A...bottom, 45B...side wall, 47...fixed terminal, 47A...first hole, 47B...second hole, 49...co-fastening nut, 101...injection molding device, 103...injection section, 105...liquid-mixed liquid rubber, 107...main body, 109...screw, 111...feed port, 113A...agent A, 113B...agent B, 115...exit, 121...molding section, 123...mold, 131...connection section, 131A...opposite side, 141...measurement section, 143, 243...ultrasonic signal, 145, 245...reflected signal, 145A...reflected signal, 145B...reflected signal, 151...determination section, 153...foreign matter, 201...ultrasonic sensor

Claims

1. a pipe member disposed on an outer periphery of the power cable; a porcelain bushing made of a rubber material and arranged on an outer circumferential side of the pipe member; an embedded member embedded in the porcelain tube; Equipped with the porcelain bushing includes a high-stress portion sandwiched between the pipe member and the embedded member in a radial direction, When the SN characteristics of the high stress area were measured, ７ When the stress piece amplitude σ is 1.0 MPa or more, Cable connection structure.

2. The cable connection structure according to claim 1, The high stress portion does not contain foreign matter having a size of 1 μm or more. Cable connection structure.

3. a pipe member disposed on an outer periphery of the power cable; a porcelain bushing made of a rubber material and arranged on an outer circumferential side of the pipe member; an embedded member embedded in the porcelain tube; Equipped with the porcelain bushing includes a high-stress portion sandwiched between the pipe member and the embedded member in a radial direction, The high stress portion does not contain foreign matter having a size of 1 μm or more. Cable connection structure.

4. The cable connection structure according to any one of claims 1 to 3, The rubber material is silicone rubber. Cable connection structure.

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