JP7498040B2 - cable - Google Patents

Description

The present invention relates to a cable that makes it difficult for water to penetrate the insulation.

Conventionally, a technology for cables using cross-linked polyethylene or the like as an insulator is known, for example, as disclosed in Patent Document 1. The cable 1 shown in FIG. 5 of Patent Document 1 is also called a CV cable (high voltage CV cable). In cable 1, an inner semiconductive layer 3 is coated on a conductor 2, and an insulator 4 made of cross-linked polyethylene or the like is extrusion coated on top of that. Furthermore, an outer semiconductive layer 5 is coated on this insulator 4, a copper shielding layer 6 made of copper tape or the like is formed on this outer semiconductive layer 5, and a sheath 7 made of polyvinyl chloride or the like is coated on this copper shielding layer 6.

However, if the cable 1 is installed in a moist environment, there is a risk that water may penetrate into the cable 1 (insulator 4) and cause water treeing in the insulator 4. In this way, if water treeing occurs in the insulator 4, the cable 1 disclosed in Patent Document 1 has a problem in that there is a risk of a decrease in insulation resistance.

Japanese Patent Application Laid-Open No. 8-161943

As alternative cable (waterproof cable) technologies to the technology of Patent Document 1, which has the above-mentioned problems, there are generally known cable 100 (prior art 1) shown in Figure 6 of this patent application, and cable 200 (prior art 2) shown in Figure 7 of this patent application. Note that a "waterproof cable" is a cable that has a structure that makes it difficult for water to penetrate into the cable (insulator).

The cable 100 shown in FIG. 6 has a waterproof structure with a metal exterior (metal corrugated) 108. The cable 100 has an inner semiconductive layer 102, an insulator 103, an outer semiconductive layer 104, a shielding layer 105 (corresponding to the copper shielding layer 6 in Patent Document 1), a holding winding tape 106, a sheath 107, and a metal exterior 108, which are arranged in this order on the conductor 101.

The cable 200 shown in FIG. 7 has a waterproof structure with a waterproof layer 207 of metal laminate tape. The cable 200 has an inner semiconductive layer 202, an insulator 203, an outer semiconductive layer 204, a shielding layer 205 (corresponding to the copper shielding layer 6 in Patent Document 1), a holding tape 206, a waterproof layer 207, and a sheath 208, which are arranged in this order on the conductor 201. The waterproof layer 207 is formed by "vertical wrapping" the metal laminate tape, and an overlapping portion 209 is formed. The overlapping portion 209 is a portion formed by overlapping one end and the other end of the metal laminate tape in the circumferential direction and fusing them together.

However, the cable 100 shown in FIG. 6 is difficult to bend because it has a metal exterior 108, and the metal exterior 108 must be removed when processing the ends. Therefore, the cable 100 has a problem in that the workability of the installation work may be reduced.

Another problem with cable 100 is that it is difficult to manufacture metal exterior 108. Therefore, cable 100 has a problem in that there is a risk of reduced manufacturing efficiency.

On the other hand, the cable 200 shown in FIG. 7 has a water-proof layer 207 of metal laminate tape under the sheath 208, so it is easier to bend and the terminals can be easily processed compared to the cable 100 (see FIG. 6). Therefore, it can be said that the cable 200 has better workability in the installation work than the cable 100.

However, in cable 200, wrinkles tend to occur in the overlapping portion 209 of the waterproof layer 207 when cable 200 is bent, and the overlapping portion 209 is not sufficiently fused, resulting in inconsistent waterproof performance. Therefore, cable 200 has a problem in that there is a risk that water may easily penetrate into the insulator 203.

In addition, cable 200 has the problem that it is difficult to manufacture because, for example, care must be taken when wrapping the metal laminate tape around one end and the other end in the circumferential direction of the metal laminate tape to prevent a decrease in the water-proofing performance at the overlapping portion 209. Therefore, cable 200 has the problem that the manufacturing efficiency of cable 200 may decrease, similar to cable 100 (see FIG. 6).

The present invention was made in consideration of the above circumstances, and aims to provide a cable that is less susceptible to water seeping into the insulator than conventional techniques.

(1) The cable of the present invention described in claim 1, which has been made to solve the above- mentioned problems, comprises an insulator and a sheath, successively disposed on a conductor, the sheath comprising a lubricating layer in which a plurality of foamed cells containing a lubricant are formed, the sheath comprising an inner layer disposed inside the sheath and an outer layer formed to cover the outer periphery of the inner layer, the outer layer being formed as the lubricating layer .

According to the present invention having the above characteristic (1), the sheath is provided with a lubricating layer, so the sheath has water repellency and lubricity. The water repellency of the sheath makes it difficult for water to penetrate into the insulator even when the cable according to the present invention is installed in a moist location.

In addition, according to the present invention, the sheath has lubricity, which improves the slipperiness of the sheath and makes the installation surface easier to slip when laying the cable. Therefore, the ease of installation of the cable is improved compared to the conventional technology.

In addition, according to the present invention, since the infiltration of water into the insulator is prevented by the sheath rather than using the metal exterior (metal corrugation) or metal laminate tape used in the prior art, the cable has good flexibility and terminal processing can be easily performed. Therefore, from this point of view as well, the workability of cable installation work is improved compared to the prior art.

According to the present invention, the outer layer of the sheath is a lubricating layer (foamed layer) having a plurality of foamed cells containing a lubricant, and the inner layer is formed as a layer having no foamed cells (non-foamed layer). By having the non-foamed layer in the sheath, the tensile properties required for the sheath are maintained and deterioration of the sheath due to the lubricant is prevented.

( 2 ) The cable of the present invention described in claim 2 is the cable described in claim 1 , characterized in that the thickness of the inner layer not having the foam cells is 80% or more and 90% or less of the thickness of the sheath.

According to the present invention having the above characteristic ( 2 ), the thickness of the layer (non-foamed layer) in the sheath that does not have foamed cells containing a lubricant is 80% or more and 90% or less of the thickness of the sheath. This makes it clearer that the tensile properties required of the sheath are maintained and that deterioration of the sheath due to the lubricant is prevented.

( 3 ) The cable of the present invention described in claim 3 is the cable described in claim 1 or 2 , characterized in that a water-repellent coating is formed on the outer peripheral surface of the sheath.

According to the present invention having the above feature ( 3 ), a water-repellent coating is formed on the outer surface of the sheath, so that even if water adheres to the sheath, this coating makes it difficult for the water to penetrate into the insulator. When the coating is formed on the outer surface of the sheath , even if water adheres to the outer surface of the sheath, the water is repelled by the coating and slides down the outer surface of the sheath. Therefore, it is possible to prevent water from penetrating into the cable at the outer surface of the sheath.

( 4 ) The cable of the present invention described in claim 4 is the cable described in claim 1, 2 or 3 , characterized in that the foamed cells are formed so that the cell diameter is at least a size that allows the lubricant to penetrate and is 120 μm or less.

According to the present invention having the above characteristic ( 4 ), the cell diameter of the foamed cells in the lubricating layer is at least a size that allows the lubricant to penetrate and is 120 μm or less, so that the lubricant that has penetrated the lubricating layer can be sufficiently retained on the outer circumferential surface of the sheath. Therefore, by sufficiently retaining the lubricant on the outer circumferential surface of the sheath, the water repellency of the sheath is fully exhibited.

( 5 ) The method for manufacturing a cable of the present invention described in claim 5 , which has been made to solve the above problems, is characterized by including the steps of: covering a conductor with an insulator and a sheath having an inner layer and an outer layer in that order; foaming the outer layer of the sheath; and impregnating the foamed outer layer of the sheath with a lubricant to form a lubricating layer.

( 6 ) The method for manufacturing a cable of the present invention described in claim 6 , which has been made to solve the above problems, includes a step of sequentially covering a conductor with an insulator and a sheath having an inner layer and an outer layer , and a step of foaming the outer layer of the sheath, and in the step of covering the sheath, a lubricant is mixed into the material of the outer layer of the sheath, and a lubricating layer is formed by impregnating the foamed outer layer of the sheath with the lubricant.

According to the present invention having the above features ( 5 ) and ( 6 ), a lubricating layer is formed on the outer layer of the sheath, so that a cable having a water-repellent and lubricating sheath can be manufactured. Since the outer layer of the sheath has water-repellency, water is less likely to penetrate into the insulation even if the manufactured cable is installed in a moist place.

In addition, according to the present invention, the sheath has lubricity, which improves the slipperiness of the sheath, making it possible to manufacture a cable that slides easily on the installation surface when the cable is laid. This results in a cable that is easier to install than the conventional technology.

In addition, according to the present invention, it is possible to manufacture a cable that can prevent water from entering the insulator by using a sheath, without using a metal exterior (metal corrugated) or metal laminate tape, etc., as in the conventional technology, and therefore it is possible to obtain a cable that has good flexibility and allows easy terminal processing. Therefore, from this point of view, it is possible to obtain a cable that is easier to install than the conventional technology.

The present invention has the advantage of making it more difficult for water to penetrate the insulator than conventional techniques.

FIG. 1 is a diagram showing an embodiment of a cable according to the present invention, and is a partially cutaway perspective view of an end of the cable. 2 is a cross-sectional view taken along line AA in FIG. 1. 3 is an enlarged cross-sectional view of a portion surrounded by a virtual line indicated by an arrow B in FIG. 2. 1A and 1B are diagrams illustrating a method for manufacturing a cable according to the present invention, in which (a) is a partial cross-sectional view of a sheath showing the state in which the outer layer of the sheath has been foamed, and (b) is a diagram illustrating the work of impregnating the outer layer of the sheath shown in (a) with a lubricant. 10A to 10C are diagrams for explaining the operation of the cable according to the present invention when it is installed in a moist environment. FIG. 1 is a diagram showing a cable according to prior art 1, and is a partially cutaway perspective view of an end of the cable. FIG. 13 is a diagram showing a cable according to prior art 2, and is a partially cutaway perspective view of an end of the cable.

Below, an embodiment of the cable according to the present invention will be described with reference to Figures 1 to 5.

Figure 1 shows an embodiment of a cable according to the present invention, and is a partially cutaway perspective view of the end of the cable. Figure 2 is a cross-sectional view taken along the line A-A in Figure 1. Figure 3 is an enlarged cross-sectional view of the area enclosed by the imaginary line indicated by the arrow B in Figure 2. Figure 4 is a diagram explaining the manufacturing method of the cable according to the present invention, where (a) is a partial cross-sectional view of the sheath showing the state in which the outer layer of the sheath has been foamed. (b) is a diagram explaining the process of impregnating the outer layer of the sheath shown in (a) with a lubricant. Figure 5 is a diagram explaining the operation of the cable according to the present invention when it is installed in a moist environment.

In the following description, specific shapes, materials, values, directions, etc. are merely examples to facilitate understanding of the present invention, and may be modified as appropriate to suit the application, purpose, specifications, etc.

In Figures 1 and 2, reference numeral 1 indicates an embodiment of a cable according to the present invention. Cable 1 is also known as a CV cable (high-voltage CV cable), and is a waterproof cable with a structure that makes it difficult for water to penetrate into the insulator 4 (described below). Hereinafter, in this specification, cable 1 may be referred to as a "waterproof cable" or a "CV cable (high-voltage CV cable)" as appropriate.

The cable 1 shown in Figures 1 and 2 includes a conductor 2, an inner semiconductive layer 3, an insulator 4, an outer semiconductive layer 5, a shielding layer 6, a pressure winding tape 7, and a sheath 8. Each component of the cable 1 will be described below.

First, the conductor 2 will be described.
The conductor 2 shown in Figs. 1 and 2 supplies electric current and is of a known type.

Next, the internal semiconducting layer 3 will be described.
1 and 2 is formed to a predetermined thickness by extruding a resin composition imparted with electrical conductivity onto the outer periphery of the conductor 2. Examples of the resin composition imparted with electrical conductivity that forms the internal semiconductive layer 3 include those that use an olefin-based resin, such as polyethylene, or an ethylene-based copolymer, such as an ethylene-vinyl acetate copolymer, or an ethylene-ethyl acrylate copolymer, as the main material, and that are blended with conductive carbon black, such as furnace black, acetylene black, or ketjen black.

Next, the insulator 4 will be described.
1 and 2 is formed to a predetermined thickness by extruding an insulating resin onto the outer periphery of the internal semiconducting layer 3. Examples of the insulating resin include polyolefin resins. Examples of polyolefin resins include polyethylene (PE), polypropylene (PP), ethylene-vinyl acetate copolymer (EVA), ethylene-ethyl acrylate copolymer (EEA), ethylene-α-olefin copolymer, and ethylene-propylene copolymer.

Next, the outer semiconductive layer 5 will be described.
1 and 2 is formed to a predetermined thickness by, for example, wrapping a semiconductive tape, which is a fibrous (cloth) tape that has been given electrical conductivity, around the outer periphery of the insulator 4, or by extruding a resin composition that has been given electrical conductivity similar to that of the inner semiconductive layer 3, around the outer periphery of the insulator 4. Note that the outer semiconductive layer 5 may be formed by a combination of the above two methods.

Next, the shielding layer 6 will be described.
1 and 2 is formed of a metal tape such as a copper tape. The shielding layer 6 is formed to a predetermined thickness by winding the metal tape such as the copper tape around the outer periphery of the outer semiconductive layer 5. When forming the shielding layer 6, by winding the metal tape around the outer periphery of the outer semiconductive layer 5, the flexibility of the cable 1 is not affected when the cable 1 is bent. Since the cable 1 includes the shielding layer 6, it is possible to obtain shielding performance.

Next, the pressure winding tape 7 will be described.
1 and 2 is wound around the outer periphery of the shielding layer 6. Examples of the holding down winding tape 7 include polyester nonwoven fabric, nylon nonwoven fabric, polypropylene tape, polyester tape, glass tape, paper tape, and ceramic paper.

Next, the sheath 8 will be described.
The sheath 8 shown in Figures 1 and 2 constitutes the outermost layer of the cable 1 and is a characteristic part of the present invention. As shown in Figures 1 and 2, the sheath 8 has a two-layer structure of an inner layer 9 and an outer layer 10. In Figure 2, reference numeral 11 denotes the inner peripheral surface, and reference numeral 12 denotes the outer peripheral surface.

The inner layer 9 shown in FIG. 2 is a layer of the sheath 8 that is disposed on the central axis side of the cable 1 (the conductor 2 side), and may be called the "first layer." The outer layer 10 shown in FIG. 2 is a layer of the sheath 8 that is disposed outside the inner layer 9, and may be called the "second layer." Below, the inner layer 9 and the outer layer 10 will be described separately.

First, the inner layer 9 will be described.
In this embodiment, the inner layer 9 shown in Figures 1 and 2 is formed to a predetermined thickness by extruding an insulating resin onto the outer periphery of the pressure winding tape 7. The inner layer 9 in this embodiment is formed as a layer that does not have foam cells 13 (see Figure 3), which will be described later, and can be called a "non-foamed layer." Examples of the insulating resin include polyolefin resins and vinyl chloride resins. Specific examples of polyolefin resins are the same as those of the insulator 4. Examples of vinyl chloride resins include vinyl chloride resins.

Here, in this embodiment, the inner layer 9 is formed so that its thickness is 80% or more and 90% or less of the total thickness of the sheath 8. In this embodiment, the inner layer 9 is formed so that its thickness is 80% of the total thickness of the sheath 8.

As described above, the thickness of the inner layer 9 (non-foamed layer) in the sheath 8 is set to 80% or more and 90% or less of the thickness of the sheath 8 in order to maintain the tensile properties required of the sheath 8, and also to prevent deterioration of the sheath 8 due to the lubricant 15 when the lubricant 15 is impregnated into the outer layer 10 as described below (see Figure 3).

Next, the outer layer 10 will be described.
In this embodiment, the outer layer 10 shown in Figures 1 and 2 corresponds to the "lubricating layer" described in the claims. The outer layer 10 in this embodiment can be called a "foamed layer." The outer layer 10 is formed to a predetermined thickness by extruding an insulating resin onto the outer periphery of the inner layer 9.

The resin having the insulating properties may be a polyolefin resin or a vinyl chloride resin, as in the insulator 4 and the inner layer 9 (specific examples of the polyolefin resin and the vinyl chloride resin are the same as those in the insulator 4 and the inner layer 9). The outer layer 10 is foamed by blending a foaming agent with the polyolefin resin or the vinyl chloride resin.

As the foaming agent, for example, inorganic foaming agents such as sodium bicarbonate, ammonium bicarbonate, and ammonium carbonate, and organic foaming agents such as azo compounds, sulfohydrazide compounds, nitroso compounds, and azide compounds can be suitably used. The foaming agent is mixed into the resin by directly kneading the foaming agent into the resin. Alternatively, a master batch containing the foaming agent may be prepared in advance, and the master batch may be kneaded with the resin. If necessary, a suitable foaming promoter may be used in combination.

As shown in FIG. 3, the outer layer 10 in this embodiment has a plurality (a large number) of foam cells 13 formed therein throughout the entire outer layer 10. Also, as shown in FIG. 3, the outer layer 10 in this embodiment has a coating 14 formed on its outer surface (the outer surface 12 of the sheath 8).

The foam cells 13 shown in FIG. 3 are spaces (voids) with an elliptical cross section formed by bubbles generated by foaming the resin forming the outer layer 10 with a foaming agent. Note that the cross-sectional shape of the foam cells 13 may be approximately circular.

As shown in FIG. 3, the foam cells 13 contain a lubricant 15 (lubricating oil). The lubricant 15 has water repellency and lubricity. In this embodiment, an example of the lubricant 15 is Fomblin (registered trademark) PFPE (perfluoropolyether) manufactured by SOLVAY.

The foam cells 13 are formed so that the cell diameter D (the major axis of the foam cells 13 in this embodiment) shown in FIG. 3 is 120 μm or less. There is no particular limit to the lower limit of the cell diameter D of the foam cells 13, but it is at least a size (diameter) that allows the lubricant 15 to penetrate into the foam cells 13.

As described above, the cell diameter D of the foamed cells 13 is set to 120 μm or less because forming foamed cells 13 with a cell diameter D of 120 μm or less makes it possible to adequately retain the lubricant 15 that has permeated the outer layer 10 on the outer surface 12 of the sheath 8. Here, if the cell diameter D of the foamed cells 13 exceeds 120 μm, the lubricant 15 will be more likely to permeate the outer layer 10, but the lubricant 15 will not be able to be adequately retained on the outer surface 12 of the sheath 8, and there is a risk that the water repellency of the sheath 8 will not be fully exhibited.

The coating 14 shown in FIG. 3 is water-repellent and is a film that is formed over time on the outer surface 12 of the sheath 8 by impregnating the outer layer 10 with a lubricant 15 after or during the formation of the outer layer 10.

As shown in FIG. 3, a coating 14 is formed on the outer peripheral surface 12 of the sheath 8. Even if water droplets 16 (see FIG. 5) adhere to the outer peripheral surface 12 of the sheath 8, the water droplets 16 are repelled by the coating 14, and the water droplets 16 slide down the outer peripheral surface 12 of the sheath 8.

Next, a manufacturing process (manufacturing method) for the cable 1 according to the present embodiment will be described.
First, the inner semiconductive layer 3, the insulator 4, the outer semiconductive layer 5, and the shielding layer 6 are formed in this order on the conductor 2.

The outer semiconductive layer 5 is formed by wrapping semiconductive tape around the outer periphery of the insulator 4 by taping, or by extruding a resin composition that has been made conductive. The shielding layer 6 is formed by wrapping a metal tape, such as copper tape, around the outer periphery of the outer semiconductive layer 5 by taping. After the shielding layer 6 is formed, a holding tape 7 is wrapped around the outer periphery of the shielding layer 6 by taping.

Then, the sheath 8 (inner layer 9 and outer layer 10) is formed. The sheath 8 is formed by two-layer extrusion molding on the outer circumference of the holding and wrapping tape 7 after the holding and wrapping tape 7 is wound.

Thereafter, the outer layer 10 of the sheath 8 is foamed. When the sheath 8 is extruded, the foaming agent is directly mixed into the resin that is the material for the outer layer 10, or a master batch containing the foaming agent is prepared in advance and then kneaded, whereby the outer layer 10 is foamed and numerous foam cells 13 are formed (see FIG. 4(a)).

The formation of the sheath above forms the cable 1. After the sheath 8 is extruded, the cable 1 is cooled by immersing it in cooling water (e.g., passing it through a cooling water tank) to stop the foaming of the outer layer 10.

After the foaming of the outer layer 10 is stopped, the cable 1 (sheath 8) is dried, and the cable 1 is immersed in cooling water to remove the cooling water that has infiltrated into the foam cells 13 of the outer layer 10, leaving the foam cells 13 empty.

After the drying of the cable 1 (sheath 8) is completed, the lubricant 15 is sprayed evenly onto the outer surface 12 of the sheath 8 in the entire circumferential direction of the cable 1, so that the outer layer 10 is impregnated with the lubricant 15 (see FIG. 4(b)). The lubricant 15 is sprayed by bringing the nozzle 17 close to the outer surface 12 of the sheath 8.

In this embodiment, the outer layer 10 is impregnated with the lubricant 15 by spraying the lubricant 15 as described above, but the present invention is not limited to this. Alternatively, the outer layer 10 may be impregnated with the lubricant 15 by, for example, immersing the cable 1 in the lubricant 15 (for example, passing it through a lubricant tank). Furthermore, when the sheath 8 is extrusion molded, the lubricant 15 may be mixed with the resin that is the material for the outer layer 10 together with the foaming agent.

By thoroughly impregnating the outer layer 10 with the lubricant 15, the lubricant 15 is contained within the foam cells 13, and the lubricant 15 is sufficiently retained on the outer surface 12 of the sheath 8. This forms a coating 14 on the outer surface 12 of the sheath 8 (see Figure 3). This completes the manufacturing of the cable 1.

Next, the operation of the present invention when the cable 1 according to this embodiment is laid in a place where there is moisture and during the work of laying the cable 1 will be described.
According to the cable 1 of the present embodiment as described above, the sheath 8 is provided with the outer layer 10 (lubricating layer), and therefore the sheath 8 has water repellency and lubricity. Because the sheath 8 has water repellency, water is less likely to penetrate into the insulator 4 even when the cable 1 is installed in a location where moisture is present (a location where water droplets 16 may adhere to the cable 1 as shown in FIG. 5).

In addition, according to the cable 1 of this embodiment, the sheath 8 has lubricity, which improves the slipperiness of the sheath 8, making it possible to make the installation surface of the cable 1 slippery when the cable 1 is laid. Therefore, the ease of installation of the cable 1 is improved compared to the conventional technology.

In addition, the cable 1 according to this embodiment does not use the metal exterior (metal corrugated) 108 in prior art 1 (see FIG. 6) or the water-proof layer 207 of metal laminate tape in prior art 2 (see FIG. 7), and instead uses the sheath 8 to prevent water from entering the insulator 4, so the cable 1 has good flexibility and terminal processing can be easily performed. Therefore, from this point of view as well, the workability of the cable 1 in installation work is improved compared to the prior art.

In addition, according to the cable 1 of this embodiment, the outer layer 10 of the sheath 8 is a lubricating layer (foamed layer) having a plurality of foamed cells 13 containing the lubricant 15, and the inner layer 9 is formed as a layer (non-foamed layer) that does not have foamed cells 13. By having the inner layer 9 (non-foamed layer) of the sheath 8, the tensile properties required of the sheath 8 are maintained and deterioration of the sheath 8 due to the lubricant 15 is prevented.

In addition, with the cable 1 according to this embodiment, the thickness of the inner layer 9 in the sheath 8 is 80% or more and 90% or less of the thickness of the sheath 8, so it is clearer that the tensile properties required of the sheath 8 are maintained, and it is clearer that deterioration of the sheath 8 due to the lubricant 15 is prevented.

In addition, according to the cable 1 of this embodiment, a coating 14 is formed on the outer surface 12 of the sheath 8, and this coating 14 makes it difficult for water droplets 16 to penetrate into the insulator 4 (see Figures 1 and 2) even if they adhere to the sheath 8, as shown in Figure 5. When the coating 14 is formed on the outer surface 12 of the sheath 8, even if water droplets 16 adhere to the outer surface 12 of the sheath 8, the coating 14 repels the water droplets 16, causing them to slide down the outer surface 12 of the sheath 8. Therefore, it is possible to prevent water from penetrating into the cable 1 at the outer surface 12 of the sheath 8.

In addition, with the cable 1 according to this embodiment, the cell diameter D (see FIG. 3) of the foamed cells 13 in the outer layer 10 is at least large enough for the lubricant 15 to penetrate, and is no larger than 120 μm, so that the lubricant 15 that has permeated the outer layer 10 can be sufficiently retained on the outer surface 12 of the sheath 8. Therefore, by sufficiently retaining the lubricant 15 on the outer surface 12 of the sheath 8, the water repellency of the sheath 8 is fully exhibited.

Next, the effects of the cable 1 according to the present embodiment will be described.
As described above with reference to Figures 1 to 5, the cable 1 according to this embodiment has the effect of making it more difficult for water to penetrate into the insulator 4 than the conventional technology.

Next, features other than those described in the claims will be described.
The cable 1 according to the present invention as described in the claims is characterized by the following features (1) to (5).

(1) The cable 1 is characterized in that it "has an insulator 4 and a sheath 8, successively disposed on a conductor 2, and the sheath 8 has a lubricating layer in which a plurality of foamed cells 13 containing a lubricant 15 are formed."

(2) The cable 1 is characterized in that "in the cable 1 described in (1) above, the sheath 8 comprises an inner layer 9 disposed inside the sheath 8 and an outer layer 10 formed to cover the outer periphery of the inner layer 9, and one of the inner layer 9 and the outer layer 10 is formed as the lubricating layer."

(3) The cable 1 is characterized in that "in the cable 1 described in (2) above, when either the inner layer 9 or the outer layer 10 is formed as the lubricating layer, the thickness of the other of the inner layer 9 or the outer layer 10 is 80% or more and 90% or less of the thickness of the sheath 8."

(4) The cable 1 is characterized in that "in the cable 1 described in (1), (2) or (3) above, the sheath 8 has a water-repellent coating 14 formed on at least one of its inner surface 11 and outer surface 12."

(5) The cable 1 is characterized in that "in the cable 1 described in (1), (2), (3) or (4) above, the foam cells 13 are formed so that the cell diameter D is at least a size that allows the lubricant 15 to penetrate, and is 120 μm or less."

The cable 1 according to the present invention is characterized by the above features (1) to (5) as well as the following feature (6).

(6) The cable 1 is characterized in that "the cable 1 described in (1), (2), (3), (4) or (5) above has a shielding layer 6 between the insulator 4 and the sheath 8."

The effects of the cable 1 characterized by the above (6) will be described.
That is, according to the cable 1, in addition to providing the same effects as the above-described embodiment, the cable 1 is provided with the shielding layer 6, and thus has the effect of providing the cable 1 with shielding performance.

Of course, the present invention can be modified in many ways without departing from the spirit of the invention.

In the above description, the cable 1 (see FIG. 1) is configured as a "lubricating layer" in which the outer layer 10 of the sheath 8 is formed with a plurality of foamed cells 13 containing a lubricant 15, as shown in FIG. 3, but this is not limiting and the following configurations may also be used.

In other words, although not shown, the cable according to the present invention may adopt a configuration in which the inner layer of the sheath is formed as a "lubricating layer" in which multiple foamed cells containing a lubricant are formed. When the inner layer is formed as the above-mentioned lubricating layer, although not shown, the outer layer of the sheath is formed so that its thickness is 80% or more and 90% or less of the thickness of the entire sheath.

When the above-mentioned configuration is adopted, the water-repellent coating is formed on the inner peripheral surface of the sheath. By forming a coating on the inner peripheral surface of the sheath, even if water penetrates into the outer layer of the sheath, the inner layer and coating can prevent further water penetration. Therefore, a cable having the above-mentioned configuration can achieve the same effects as the above-described embodiment.

REFERENCE SIGNS LIST 1...cable, 2...conductor, 3...inner semiconductive layer, 4...insulator, 5...outer semiconductive layer, 6...shielding layer, 7...holding winding tape, 8...sheath, 9...inner layer, 10...outer layer (lubricating layer), 11...inner circumferential surface, 12...outer circumferential surface, 13...foamed cells, 14...coating, 15...lubricant, 16...water droplets, 17...nozzle

Claims (6)

An insulator and a sheath are sequentially provided on a conductor;
The sheath is
A lubricating layer is provided in which a plurality of foamed cells containing a lubricant are formed ,
The sheath is
an inner layer disposed inside the sheath;
an outer layer formed to cover the outer periphery of the inner layer;
Equipped with
The outer layer is formed as the lubricating layer.
A cable characterized by: 2. The cable according to claim 1 ,
a thickness of the inner layer having no foam cells being 80% or more and 90% or less of a thickness of the sheath, 3. The cable according to claim 1 or 2 ,
A cable comprising: a water-repellent coating formed on an outer peripheral surface of the sheath. 4. The cable according to claim 1, 2 or 3 ,
The foam cells are
the cell diameter is at least a size that allows the lubricant to penetrate, and is 120 μm or less. A step of sequentially covering a conductor with an insulator and a sheath having an inner layer and an outer layer ;
foaming the outer layer of the sheath;
impregnating the outer layer of the foamed sheath with a lubricant to form a lubricating layer;
A method for manufacturing a cable comprising: A step of sequentially covering a conductor with an insulator and a sheath having an inner layer and an outer layer ;
foaming the outer layer of the sheath;
Including,
In the step of covering the sheath,
a lubricant is mixed into a material for the outer layer of the sheath, and a lubricating layer is formed by impregnating the outer layer of the foamed sheath with the lubricant.

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