JPH09298827A - Covering tube in wire connection - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a covering tube at a low cost with good sealing characteristics for a wiring with anomalous cross section by providing a pre- stretched tube only at an opening edge. SOLUTION: A covering tube 10 has an elastic sleeve part 12 and a seal part 14 at both opening ends of the sleeve part 12. A sealing part 14 is made up of a first elastic element 16 elongated in a body with the sleeve part 12, a second elastic element 18 provided at a round position inside the first elastic element 16, a removable core element 20 for holding the first and second elastic members 16 and 18 in a coaxially enlarged state. The first elastic element 16 is made of elastomer with 10 to 100kgf/cm<2> in JIS-K6301 standard and tensile stress of 300%. The second elastic element 18 is made of elastomer with 30Hs or below in JIS/A standard. The sealing part 14 has good sealing characteristics for an anomalous cross-section wire through deformation of the second elastic element 18.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a covering tube for a wire connecting portion for applying moisture proof, electrical insulation, and mechanical protection to a wire connecting portion such as a straight connecting portion or a branch connecting portion.

[0002]

2. Description of the Related Art Conventionally, an electric wire conductor exposed at a connection portion between electric wires (cables) or a connection portion between an electric wire and another conductive terminal member is covered with a coating for the purpose of moisture proofing, electrical insulation, and mechanical protection. For this purpose, various methods are used. For example, a method of winding a waterproof pressure-sensitive adhesive tape on a connection portion, a method of covering the connection portion with a separate pipe member and then sealing an end of the tube member with a waterproof pressure-sensitive adhesive tape, a paste of mastic or the like on the connection portion A method of winding a waterproof pressure-sensitive adhesive tape on a coated member is well known as a simple and inexpensive method. However, the process of winding the waterproof pressure-sensitive adhesive tape tends to cause a difference in finished state depending on an operator. However, there is a problem that it is difficult to perform uniform and stable processing.

[0003] In order to easily and stably impart sufficient moisture-proofing properties, electrical insulation properties, and mechanical protection properties to a wire connection part, an inner diameter dimension exceeding an outer diameter dimension of the connection part and a total length of the connection part are exceeded. A covering tube (hereinafter, referred to as a shrinkable tube) is known in which a tube member having a length is shrunk by some means after being arranged so as to surround the connecting portion, and the shrinking force tightly covers the connecting portion. . This type of shrinkable tube includes a heat shrinkable tube (see Japanese Patent Application Laid-Open No. 1-295614) in which a tube member made of a polymer material having high heat shrinkability is heated and shrunk using an external heat source, and a tube having a small permanent elongation. The entire length of the tubular member made of an elastomer is elastically expanded (radially expanded) in advance by a cylindrical core member made of a hard plastic or the like, and is elastically contracted by removing the core member at the time of attachment to the connection portion. Elastic shrinkable tube with core to be made (see JP-A-3-143217)
There is.

[0004] All of the above-mentioned shrinkable tubes can shorten the working time and stabilize the finished state.
Since the pipe member adheres to the wire conductor and the wire jacket by its own contraction force, the advantage that sufficient moisture-proof, electrical insulation and mechanical protection properties can be provided to the connection portion without using a waterproof adhesive tape. Having. However, the heat-shrinkable tube has the problem of requiring a heat source such as a burner at the time of work, and has a problem that the heat-shrinkage work requires skill to obtain a uniform shrink shape. On the other hand, an elastic shrinkable tube with a core (generally referred to as PST (pre-stretched tube)) does not require skill in shrinking work, but the longer the tube member is, the longer it takes to remove the core member, and Due to the existence of the pipe member, the pipe member cannot be bent when it is attached to the electric wire connection portion, which makes it difficult to perform the work. While confirming the above, the pipe member could not be attached to the connecting portion, and the reliability of the coating treatment tended to be lowered.

[0005] To solve such a problem of the elastically shrinkable tube with a core, Japanese Patent Application Laid-Open No. Hei 7-57798 discloses a coated tube having a PST structure seal portion only in a region near the tube opening end. Is disclosed.
That is, this covering tube includes a tubular sleeve portion having a plurality of open ends, and a tubular seal portion provided at each open end of the sleeve portion, and each seal portion is integrally connected to the sleeve portion. It is formed from a tube element and a removable core element arranged radially inside the tube element to hold the tube element in an elastically expanded state. Therefore, in this covered tube, the total length of the core element provided in each seal portion is reduced as compared with the case where the entire tube has the PST structure, and thus the work time required for removing the core element is reduced. Further, since the core element is not arranged on the sleeve portion covering the electric wire connection portion, the sleeve portion can be flexed freely in the mounting operation, so that the mounting workability can be improved and the position of the electric wire connection portion in the sleeve portion can be improved. The covering tube can be mounted at an appropriate position while confirming the tactile sensation.

By the way, it is known that the electric wires installed outdoors are not only provided with a smooth circular cross section, but also provided with a modified cross section having corners and irregularities. For example, in an area with a large amount of snow, especially in winter, in order to prevent disconnection due to the weight of snow accumulated on the electric wire, an electric wire in which a ridge protruding radially from the outer surface of the electric wire jacket is formed in the longitudinal direction ( Generally, an SN-OC electric wire) is used.
When the shrink tube is directly used for an electric wire having such a modified cross section, a gap is formed between the wire jacket and the shrink tube around the ridge, and sufficient moisture resistance and electric insulation are obtained. Becomes difficult. Therefore, conventionally, for an electric wire having an irregular cross section, an elastic contraction tube with a core is attached after applying a mastic to the electric wire connecting portion. However, in this method, there are problems that the mastic protrudes from the shrinkable tube and stains the surroundings, and that it takes a long time for the mastic to sufficiently follow the surface of the deformed electric wire and cure.

Japanese Unexamined Patent Publication (Kokai) No. 7-298473 discloses a covered tube capable of obtaining sufficient moisture resistance and electric insulation for an electric wire having a modified cross section. This coated tube has a PST structure over the entire length of the tube, and the tube member whose diameter is expanded by the core member has a two-layer structure in which an elastomer having a hardness smaller than that of the outer layer is arranged in the inner layer. To be done. Therefore, according to this coated tube, the flexible inner layer sufficiently follows the surface of the deformed electric wire due to the contraction of the tube member after the core member is removed, and the contraction force of the outer layer provides a sufficient sealing effect.

[0008]

Problems to be Solved by the Invention Japanese Patent Application Laid-Open No. 7-57798
Since the tube element of each seal part has a single-layer structure, the covered tube disclosed in Japanese Patent Publication has a problem in that it is difficult to obtain sufficient moisture resistance and electric insulation for an electric wire having a modified cross section as described above. Have. On the other hand, JP-A-7-298473
In the coated tube disclosed in Japanese Patent Publication, since the core member is disposed over the entire length of the tube, it takes time to remove the core member, and the presence of the core member deteriorates the mounting workability and reduces the reliability of the coating process. Have a problem to do.

Further, in any of the coated tubes described in any of the publications, as in the case of applying the configuration of the coated tube to, for example, a branch connection portion of an electric wire, a diameter expansion dimension at each open end, that is, a core member (or core element). When the outer diameter dimensions of () are different, the following problems occur. For example, when the coated tube is applied to the Y-branch connection portion of the electric wire, a total of two branched electric wires inserted into the tube from the two open ends of the coated tube for the branched electric wire are used for the main electric wire.
After pulling out from one open end and connecting both branch electric wires to one main electric wire, shift the covering tube and place the electric wire connection part inside the tube, and remove the core member in that state, so that the covering tube becomes an electric wire. It is attached to the connection part. Therefore, the opening end of the coating tube on the main electric wire side must be greatly expanded by using a core member having a diameter larger than that of the opening end on the branch electric wire side. When the main electric wire and the branch electric wire have substantially the same diameter, the pipe member (or the pipe element) at the opening end on the main electric wire side, which is thus greatly expanded, expands smaller after removing the core member. Similar to the pipe member at the open end of the branched electric wire, it is required that the main electric wire can be shrunk to substantially the same diameter to exhibit the same sealing ability as the branch electric wire. Therefore, when manufacturing such a branched coated tube, a material having a permanent elongation property sufficient to exert sufficient sealing ability at the opening end of the main electric wire side, which has a larger diameter, is used as the material for the pipe member. Although such a material is to be selected, such a material has an excessive capacity with respect to the portion other than the opening end on the main wire side, which causes a problem that the material cost unnecessarily increases.

The object of the present invention is to provide P only in the region near the opening end.
By providing the ST structure, it is possible to obtain excellent moistureproofness and electrical insulation even for an electric wire having an irregular cross section in the covered tube of the electric wire connecting portion having improved mounting workability and covering reliability. In addition, even in applications where different diameter expansion dimensions are required for each opening end, such as application to a branch connection part, it is possible to suppress an increase in material cost by providing a desired sealing ability to a desired opening end. It is to provide a covering tube for a wire connecting portion.

[0011]

To achieve the above object, the present invention provides a tubular sleeve portion made of an electrically insulating elastomer having a plurality of open ends, and a plurality of open ends of the sleeve portion. And a tubular seal portion having electrical insulation provided on the pipe element, each of the seal portions being disposed radially inside the pipe element and the pipe element connected to the sleeve portion to elastically expand the pipe element. In a sheath tube of a wire connection formed of a removable core element that holds in a radial state, at least one tube element of a seal part has a first elastic element integrally extended from a sleeve part, and a first elastic element. There is provided a covering tube for a wire connecting portion, comprising a second elastic element sandwiched between an elastic element and a core element.

Further, the present invention provides the coating tube for the electric wire connecting portion, wherein the second elastic element is made of an elastomer having a hardness smaller than that of the first elastic element.

Further, according to the present invention, in the above-mentioned covering tube for the electric wire connecting portion, the hardness of the second elastic element is JIS-A.
The standard is 30 Hs or less, and the first elastic element is 10 kgf / cm ²
Providing a coating tube with a 300% tensile stress value in the range of ~100kgf / cm ^2.

Further, the present invention provides the coating tube for the electric wire connecting portion, wherein the second elastic element is made of an elastomer whose permanent elongation is smaller than that of the first elastic element.

Further, in the present invention, in the covering tube for the electric wire connecting portion, the permanent elongation of the first elastic element is 10%.
Is in the range of up to 30% and the permanent elongation of the second elastic element is 10
Provide a coated tube that is less than%.

Further, according to the present invention, in the above-mentioned sheath tube of the electric wire connecting portion, at least one pipe element of the seal portion is sandwiched between the second elastic element and the core element.
A covering tube further comprising an elastic element, wherein the second elastic element is made of an elastomer whose permanent elongation is smaller than that of the first elastic element and the third elastic element is made of an elastomer whose hardness is smaller than that of the second elastic element. provide.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail based on preferred embodiments with reference to the accompanying drawings. In the multiple drawings, the same or similar components are denoted by common reference numerals. FIG. 1 shows a sheath tube 10 for a wire connecting portion according to an embodiment of the present invention. Coating tube 10
Consists of a generally cylindrical tube member having two open ends,
Mainly, the linear connection portion between electric wires having substantially the same outer diameter is covered and accommodated for the purpose of moisture proof, electrical insulation, and mechanical protection. The covering tube 10 has a tubular shape having a length capable of surrounding a conductor portion exposed at the ends of two electric wires and interconnected with each other, and an end portion of an electric wire jacket adjacent to the conductor portions of each electric wire. The sleeve portion 12 is provided. As will be described later, the sleeve portion 12 preferably has an inner diameter larger than outer diameters of the conductor portion and the end portion of the electric wire jacket. The sleeve portion 12 is essentially made of an elastomer having electrical insulation and flexibility, and is freely deformable in accordance with the bending of the electric wire to be covered.

At the two open ends of the sleeve portion 12, PS
Each of the T-structure seal portions 14 is formed. Each seal portion 14 serves as a pipe element connected to the sleeve portion 12,
First tubular shape integrally extended from the sleeve portion 12
The elastic element 16 and the tubular second elastic element 18 arranged as a separate element inside the first elastic element 16 in the radial direction are provided. The first elastic element 16 and the second elastic element 18 are preferably made of elastomers having mutually different characteristics, as described later. Furthermore, each seal portion 14 is a tubular core element 20 that is removably arranged inside the second elastic element 18 in the radial direction.
Is provided. The core element 20 has an inner diameter dimension that is sufficiently larger than the outer diameter dimension of the electric wire jacket of the electric wire to be covered.
The elastic element 16 and the second elastic element 18 are elastically expanded in diameter, and the first elastic element 16 and the second elastic element are maintained while maintaining the inner diameter dimension of the core element itself against the elastic recovery (contraction) force thereof. 18 is held in an elastically expanded state.

As will be described later, when the covering tube 10 is attached to the electric wire connecting portion, the sleeve portion 12 covers and accommodates the electric wire connecting portion, and the first elastic element 16 and the second elastic element 18 of the seal portion 14 are the core elements. When 20 is removed, it elastically contracts, and under the tightening force due to the contraction, it comes into close contact with the vicinity of the end of the electric wire jacket of the electric wire connecting portion. The sleeve portion 12 and the first elastic element 16 of each seal portion 14 are integrally formed of the same material, preferably by an injection molding process.

As described above, the seal portion 14 provided with the two-layer tube element has the tube element when the first elastic element 16 and the second elastic element 18 of the tube element are expanded by the core element 20 to a predetermined diameter. Since the tensile stress applied to the element is dispersed in each element 16 and 18, when compared with the single-layer tube element of the prior art (for example, described in JP-A-7-57798) in the same size (thickness, diameter), the material The requirements for the physical properties of are relaxed. For example, when the tube elements are compared in the same size, the
The permanent elongation properties required for layered tube elements are more relaxed than those required for conventional single layer tube elements. In other words, the two-layer tube element of the present invention can have a larger diameter expansion ratio than the conventional single-layer tube element when made from materials having the same permanent elongation properties. Such an effect acts extremely effectively, for example, when the coating tube is applied to the Y-branch connection part of the electric wire (an application example to the Y-branch connection part will be described later as another embodiment).

Further, in the seal portion 14 having the two-layer tube element, various effects can be obtained by forming the first elastic element 16 and the second elastic element 18 of the tube element from elastomers having physical properties different from each other. Cause For example, if the second elastic element 18 of the inner layer is formed of an elastomer having a low hardness, even if the hardness of the first elastic element 16 of the outer layer is set high in order to maintain the mechanical protection function, the above-mentioned S
An excellent sealing effect can be obtained even for an electric wire having an irregular cross section having unevenness on the surface such as an N-OC electric wire. Regarding the application to the electric wire having such a modified cross section, the characteristics of the covering tube 10 will be described below in terms of materials.

The first elastic element 16 constituting the outer layer of the tubular element of the seal portion 14 is made of an elastomer having physical properties preferable as PST, such as electric insulation, high elastic recovery rate and excellent permanent elongation characteristics. In particular, for example, the above-mentioned SN-
Even under low temperature conditions that are the operating environment of the OC electric wire, a strong tightening force can be continuously applied to the electric wire jacket via the second elastic element 18, resulting in an excellent moisture-proof effect, electric insulation effect and mechanical protection. It is desirable to use a material that can exert its action. Specific examples of the material of the first elastic element 16 include ethylene propylene rubber (especially EPDM), chloroprene rubber, butyl rubber, silicone rubber, natural rubber, fluorine rubber, silicone-modified EPDM, and the like. Of these, silicone rubber is a particularly preferable material because it does not deteriorate in properties over a wide temperature range, has excellent weather resistance, has high water repellency, and has excellent electrical insulating properties.

More specifically, the first elastic element 16 is
Based on the measuring method based on JIS-K6301, 1
0kgf / cm ² ~ 100kgf / cm ² (0.98MP ~ 9.8MP)
Of an elastomer having a 300% tensile stress value in the range of. When the 300% tensile stress value is less than 10 kgf / cm ² , the tightening force to the electric wire connecting portion generated through the second elastic element 18 at the time of elastic contraction of the seal portion 14 is insufficient, and the electric wire connecting portion is airtight and moisture-proof. When the pressure exceeds 100 kgf / cm ² , the force required to elastically expand the diameter of the first elastic element 16 and the second elastic element 18 for installing the core element 20 in the seal portion 14 increases. However, it becomes difficult to manufacture the coated tube 10. The 300% tensile stress value is preferably 20 kgf / cm ^{2 to} 60 kgf / cm ² (1.96 MP to 5.8) in order to obtain effective airtightness, moisture proofness, etc. for the electric wire connecting portion.
8MP) range, more preferably 30kgf / cm ^{2 to} 50kg
The range is f / cm ² (2.94 to 4.9 MP).

The first elastic element 16 is further provided with JIS-K6.
30Hs based on the measurement method (A type) based on 301
It consists of an elastomer having a hardness in the range of -60 Hs.
When the hardness is less than 30 Hs, the material is too soft and the mechanical protection function is deteriorated, and the airtightness of the electric wire connecting portion obtained through the second elastic element 18 when the first elastic element 16 elastically contracts, Moisture-proof property deteriorates. Further, when the hardness exceeds 60 Hs, the elongation of the material decreases, and the force required to elastically expand the diameter of the first elastic element 16 and the second elastic element 18 in order to install the core element 20 in the seal portion 14. And the manufacturing of the coated tube 10 becomes difficult.

The second elastic element 18 forming the inner layer of the tube element of the seal portion 14 is sandwiched between the first elastic element 16 and the core element 20 when the covering tube 10 is not used, and is attached to the wire connecting portion. Sometimes the core element 20 is removed so that it elastically contracts together with the first elastic element 16 and the strong tightening force generated by the first elastic element 16 causes close contact with the end portion of the wire jacket of the wire connecting portion. To be done. Such a second
The elastic element 18 is made of an elastomer having the same physical properties as PST as the first elastic element 16, and in particular,
Silicone rubber is also the most suitable material in terms of little deterioration of properties under low temperature conditions.

Further, the second elastic element 18 can be easily provided between the electric wire jacket and the first elastic element 16 when the covering tube 10 is used for an electric wire having an irregular cross section such as an SN-OC electric wire. It deforms and follows unevenness on the surface of the electric wire satisfactorily, and makes it possible to obtain sufficient moisture resistance and electric insulation under the strong tightening force of the first elastic element 16. In order to achieve such properties, it is desirable to introduce a chemically or physically crosslinked structure into the elastomer of the second elastic element 18, and a foamed elastomer may be used.

More specifically, the second elastic element 18 is JIS
-Based on the measuring method (A type) based on K6301,
It consists of an elastomer having a hardness of 30 Hs or less. If the hardness is 30 Hs or more, the material is too hard, and the deformation followability with respect to the wire jacket surface having a modified cross section such as an SN-OC wire deteriorates, and when the seal portion 14 elastically contracts, the wire jacket surface and the second wire are removed. A gap is formed between the elastic element 18 and the airtightness, moistureproofness, etc. of the electric wire connecting portion are insufficient. The elastomer of the second elastic element 18 preferably has a hardness of 5 Hs or more based on the measuring method (A type) according to JIS-K6301. When the hardness is less than 5 Hs, the viscosity is high and the core element 20 is easily stuck to the outer surface, has high fluidity, and easily protrudes from between the electric wire and the covering tube 10, resulting in deformation that follows irregularities on the electric wire outer surface. It takes time and the heat resistance decreases. The more preferred hardness of the elastomer of the second elastic element 18 is in the range of 7 Hs to 25 Hs, and the most preferred hardness is in the range of 10 Hs to 20 Hs.

The second elastic element 18 is JIS-K63.
1 kgf / cm ² to 50 based on the measurement method according to 01.
300% of the range of kgf / cm ² (0.098MP-4.9MP)
It is preferably composed of an elastomer having a tensile stress value. When the 300% tensile stress value is less than 1 kgf / cm ² , the fluidity is high, and when the seal portion 14 elastically contracts, it easily sticks out between the electric wire and the covering tube 10, and 50 kgf / cm ²
When it exceeds, the deformation followability with respect to the surface of the electric wire jacket having the irregular cross section is deteriorated, and a gap is easily generated between the surface of the electric wire jacket and the second elastic element 18 when the seal portion 14 elastically contracts. A more preferable 300% tensile stress value is 3 kg.
The range is f / cm ^{2 to 20} kgf / cm ² (0.294 MP to 1.96 MP).

The other physical properties of the first elastic element 16 and the second elastic element 18 of the seal portion 14 (eg, permanent elongation, tensile strength, etc.) are arbitrary within a range suitable for PST. Also,
The first elastic element 16 and the second elastic element 18 of the seal portion 14
The axial length of is appropriately set according to the seal distance (the length required to obtain a reliable seal) determined by the voltage applied to the applied electric wire of the coated tube 10, but is 10 mm or more. It is preferably dimensioned. In the illustrated embodiment, the first elastic element 16 has a length projecting outward in the axial direction from the second elastic element 18 so that the second elastic element 18 does not protrude from the seal portion 14. Further, the radial thickness of the tube element including the first elastic element 16 and the second elastic element 18 of the seal portion 14 is also appropriately set according to the seal distance, but is preferably 3 mm or more.

The core element 20 of the seal portion 14 is a cylindrical member made of, for example, a hard plastic, and the first elastic element 16 and the second elastic element 18 resist the elastic recovery (contraction) force thereof and the elasticity described above. It has sufficient rigidity to keep the diameter expanded. Suitable materials for the core element 20 include cellulose acetate or butyrate, polypropylene, polyethylene, polyvinyl chloride and the like.

The core element 20 includes a groove or weakening line 22 extending spirally over the entire length of its cylindrical wall and a sleeve portion 12.
And an extension portion 24 extending in a strip shape at an end portion disposed adjacent to. The extension portion 24 is passed through the inside of the core element 20, and the tip thereof is pulled out from the axially outer end of the seal portion 14. The core element 20 is a covering tube 1
When 0 is attached to the wire connecting portion, the extension portion 24 is continuously broken along the weakening line 22 by pulling the extension portion 24 from the outside of the seal portion 14 and removed from the seal portion 14. Therefore, the core element 20 preferably has an inner diameter dimension that allows the extension portion 24 to be easily pulled by utilizing the gap between the electric wire jacket and the core element 20 in a state where the electric wire is accommodated in the seal portion 14. .

As described above, in the coated tube 10, the core elements 20 arranged in the seal portions 14 at both ends have a length corresponding to the sealing distance required for the applicable electric wire, regardless of the total length of the coated tube 10. Good. As a result, the time required for the removal work of the core element 20 is significantly shortened as compared with the covering tube having the PST structure over the entire length. In addition, the material cost and the amount of waste caused by the core element 20 are reduced.

Next, the coated tube 10 having the above structure
The action and effect of will be described with reference to FIGS. As shown in FIG. 2, for example, in a linear connection portion of an SN-OC electric wire 30 (hereinafter, simply referred to as an electric wire 30), a jacket 32 and an insulator (not shown) of two electric wires 30 to be connected are provided. The conductors 34 exposed by the removal are connected to each other by the connector 36. Initially, the sheath tube 10 should have one seal 14 to 1 prior to the interconnection of the two wires 30.
The electric wire 30 is inserted, the exposed conductor 34 is pulled out from the other seal portion 14 to the outside of the covering tube 10, and is connected to the exposed conductor 34 of the other electric wire 30 by the connector 36. Next, the coating tube 10 is moved to position the connector 36 substantially at the center of the sleeve portion 12,
It is placed in a ready position (FIG. 2) surrounding the end portion of the jacket 32 of each wire 30, the exposed conductor 34, and the connector 36.

At this time, the inner diameter of the sleeve portion 12 is set so that a gap 38 is formed between the inner surface of the sleeve portion 12 and the outer surfaces of the outer jacket 32, the conductor 34, and the connector 36. Friction resistance when the electric wire 30 is inserted into the tube 10 is reduced, and the electric wire 30 can be easily inserted. Alternatively, the gap 38 may be reduced as much as possible so that the sleeve portion 12 does not tighten the wire connection portion. Further, by forming the sleeve portion 12 from the flexible material as described above, it is possible to squeeze the tubular wall of the sleeve portion 12 with a finger and confirm the position of the connector 36 in the covering tube 10. Become.

The sheath tube 10 is placed in the preparation position shown in FIG. 2, and the core element 20 of the seal portion 14 is spirally broken along the weakening line 22 by pulling the tip of the extension portion 24 in the direction of the arrow A in the figure. While removing it from the seal portion 14.
As a result, the first elastic element 16 and the second elastic element 18 of the seal portion 14 come into close contact with the outer surface of the jacket 32 of the electric wire 30 under the tightening force due to their elastic contraction (see FIG. 3).
At this time, the second elastic element 18 made of an elastomer having a hardness of 30 Hs (JIS / A) or less is 10 kgf / cm ²
Due to the strong tightening force of the first elastic element 16 made of an elastomer having a 300% tensile stress value of 100 kgf / cm ^2, the radially protruding ridges 40 provided on the outer surface of the jacket 32 of the electric wire 30. The first elastic element 1 is easily deformed following the deformation.
At least a watertight seal is provided between 6 and the jacket 32 (see FIG. 4).

The first elastic element 16 and the second elastic element of the seal portion 14
The magnitude of the tightening force due to the elastic contraction of the elastic element 18 depends on the value of so-called seal stress (%). In the present embodiment, the outer diameter dimension of the applied electric wire (that is, the protrusion 40
In order to obtain a seal stress of 5% or more in the first elastic element 16 in accordance with the outer diameter dimension of the outer cover 32 of the portion not having a portion, when the diameter of the covering tube 10 is not increased, particularly when the seal portion 14 is not expanded. The diameter dimension (that is, the inner diameter dimension of the first elastic element 16 excluding the core element 20 when the diameter is not expanded) is set. Thereby, even for an electric wire having a modified cross section such as the SN-OC electric wire 30, necessary and sufficient moisture-proof, electrical insulation, and mechanical protection effects can be obtained. Note that the seal stress is calculated by the following equation. Seal stress = [(outer diameter of wire jacket 32-inner diameter of first elastic element 16 when not expanded) / first elastic element 1 when not expanded
6 inner diameter] x 100

Moisture proof and electric insulation effects of the electric wire connecting portion by the above-mentioned coated tube 10 and the grounds for limiting numerical values are as follows.
Further clarification will be made by the evaluation results of the following experiments. The coated tube 10 to be tested is, in particular, 3
The sleeve portion 12 and the first elastic element 16 are integrally formed by die molding from three kinds of PST silicone rubbers I, II, and III having different 100% tensile stress values. Three types of PS with different size (JIS-A)
From the silicone rubber i, ii, iii for T, the second elastic element 1
8 was formed by die molding and arranged on the radially inner side of the first elastic element 16 was used. The characteristic values in each table are
It is measured according to JIS-K6301.

[0038]

[Table 1]

[0039]

[Table 2]

Nine kinds of coating tubes in which the seal portions 14 were formed by combining the respective first elastic elements 16 and the respective second elastic elements 18 were attached to the linear connecting portion of the SN-OC electric wire 30. After that, the connection portion was submerged in water, the insulation resistance between the conductor 34 and water was measured by an insulation resistance meter under the condition of DC 1000 V, and the waterproof insulation characteristics were comparatively evaluated (Experiment 1). Also,
Air pressure was applied to the electric wire connection portion from the end of the electric wire at a portion away from the electric wire connection portion where the covering tube 10 was attached, and the pressure at the time of air leak was measured to compare and evaluate the airtight property (Experiment 2). Table 3 shows the evaluation results.

[0041]

[Table 3]

In the present embodiment, the sealing performance required for the SN-OC electric wire 30 is obtained when the waterproof insulation characteristic of 2000 MΩ or more and the airtight characteristic of 0.38 kgf / cm ² or more are obtained. And Therefore, among the above materials, the first elastic element 16 and the second elastic element 18 are composed of III (300% tensile stress = 20 kgf / cm ² ) silicone rubber and iii (hardness = 15 Hs) silicone rubber. The one consisting of the combination shows the most excellent sealing performance,
Combination of II (10 kgf / cm ² ) and ii (25 Hs) and
It will be appreciated that the combination of III and ii will provide the next required sealing performance.

Further, in order to compare the present invention with the prior art, the unused coated tube 10 was placed in an environment of -20 ° C.
After leaving for 8 hours, the core element 20 is pulled out from the seal portion 14, and the time required for the first elastic element 16 and the second elastic element 18 to contract to the outer diameter dimension of the jacket of the applicable electric wire is measured, The low temperature shrinkage characteristics were comparatively evaluated (Experiment 3). Experiment 3
Then, using the coating tube 10 formed of the combination of the first elastic element 16 of III and the second elastic element 18 of iii shown in Table 3, as an example of the coating treatment according to the related art of the comparison target,
(1) A wire connection part is covered by winding a waterproof tape, (2) A connection part is insulated with a silicone rubber PST having a conventional one-layer tube member,
And (3) the connection part was treated with a conventional butyl rubber mastic built-in type PST for insulation treatment. Table 4 shows the evaluation results.

[0044]

[Table 4]

As can be seen from Table 4, the coated tube according to the present invention has much better waterproof insulation property and airtight property than the conventional waterproof tape treatment and silicone rubber PST treatment. The butyl rubber mastic built-in type PST has the same waterproof insulation property and airtight property. Further, regarding the low temperature shrinkage property, the result is far superior to the conventional butyl rubber mastic built-in type PST.

In the above embodiment, the coated tube 10 applied to the linear connection portion of the electric wire is shown, but the coated tube according to the present invention can also be used for the branch connection portion of the electric wire. As another embodiment of the present invention, a covering tube 50 applied to a branch connection part is shown in FIGS.

The covering tube 50 is composed of a substantially Y-shaped cylindrical tube member having three open ends, and is mainly used for moisture-proofing, electrical insulation, and mechanical protection of the Y-branch connecting portion of electric wires having substantially the same outer diameter. Covered for purpose. The covering tube 50 is
A length capable of surrounding the conductor portion 74 exposed at the ends of the three electric wires 70a and 70b and interconnected with each other, and the end portion of the electric wire jacket 72 adjacent to the conductor portions 74 of the electric wires 70a and 70b. And a Y-branched tubular sleeve portion 52 having The sleeve portion 52 is used for the conductor portion 7 as described later.
4 and the wire jacket 72 (eg, having a smooth cylindrical outer surface) preferably has an inner diameter dimension that is greater than the outer diameter dimension of the distal portion. The sleeve portion 52 is essentially made of an electrically insulating and flexible elastomer, and is freely deformable in response to the bending of the electric wire to be covered.

Of the three open ends of the sleeve part 52, one open end through which the main electric wire 70a is passed has a PS having a two-layer tube element similar to the seal part 14 of the covering tube 10 of FIG.
The T-structure seal portion 54a is formed. That is, the seal portion 54a is a tubular element connected to the sleeve portion 52, and is fixed to a tubular first elastic element 56 integrally extended from the sleeve portion 52 and a radially inner side of the first elastic element 56. And a tubular second elastic element 58 arranged. The first elastic element 56 and the second elastic element 58 are made of elastomers having mutually different characteristics as described later. Further, the seal portion 54a includes a large-diameter tubular core element 60 that is removably arranged inside the second elastic element 58 in the radial direction. The core element 60 has an inner diameter dimension that is sufficiently larger than the total value of the outer diameter dimensions of the electric wire jackets 72 of the two branch electric wires 70b, as will be described later, and the first elastic element 56 and the second elastic element 58 are elastic. The diameter of the first elastic element 56 and the second elastic element 58 are elastically expanded while the inner diameter is maintained against their elastic recovery (contraction) force.

Of the three open ends of the sleeve portion 52, the other two open ends through which the branch electric wire 70b is passed have a PST structure seal portion 54b having a single-layer tube element similar to the prior art.
Is formed. That is, each seal portion 54b includes a tube element 62 integrally extended from the sleeve portion 52, and a small-diameter tubular core element 64 that is removably arranged inside the tube element 62 in the radial direction. Each core element 64 has an inner diameter dimension sufficiently larger than the outer diameter dimension of the electric wire jacket 72 of one branch electric wire 70b, and elastically expands the pipe element 62, and at the same time, recovers its elastic (contracting) force. The tube element 62 is held in an elastically expanded state while maintaining the inner diameter of the tube element.

When the covering tube 50 is attached to the branch connecting portion of the electric wire, the sleeve portion 52 covers and accommodates the electric wire connecting portion,
The first elastic element 56 and the second elastic element 5 of the seal portion 54a.
8 and the tube element 62 of the seal portion 54b are the core elements 6
By removing 0 and 64, elastic contraction occurs, and under the tightening force due to the contraction, the electric wires 70a and 70b come into close contact with the portions near the ends of the electric wire jacket 72. The sleeve part 5
2, the first elastic element 56 of the seal portion 54a and the seal portion 5
The 4b tube element 62 is preferably formed by an injection molding process.
They are integrally formed from the same material. As a result, the covering tube 50 is provided with excellent moisture-proofing action, electrical insulating action and mechanical protecting action for the electric wire branch connection portion at low cost.

In the covering tube 50, the main electric wire 70 is inevitably attached to the branch connecting portion of the electric wire as will be described later.
The seal portion 54a through which a passes is expanded by the core element 60 to have a larger diameter than each seal portion 54b through which the branch electric wire 70b passes, and after the core element 60 is removed, the seal portion 54a has substantially the same outer diameter as the branch electric wire 70b. It is required that the main electric wire 70a has a sealing effect equivalent to that of each sealing portion 54b. Therefore, if the prior art is applied to such a branch-type coated tube, a material having an excellent permanent elongation property capable of exhibiting a sufficient sealing ability in a main wire side seal portion having a larger diameter is obtained. Is selected as the main material (i.e., the material of the sleeve portion and the tube element of each seal portion), but such a material is excessive for each seal portion on the branch electric wire side, and the material cost of the sheath tube is unnecessary. Growing challenges arise.

On the other hand, in the present embodiment, the main material of the covering tube 50 is selected on the basis of the permanent elongation characteristics required for the pipe element 62 of each seal portion 54b having a relatively small diameter, and the covering tube 50 is made of a material. The cost of the material is kept low, and the pipe element of the seal portion 54a that is greatly expanded has two pipe elements.
As a layered structure, as described above, the condition for the required permanent elongation property was relaxed so that the diameter could be greatly expanded. In this case, even if the second elastic element 58 is formed of the same material having the same permanent elongation characteristics as the main material (that is, the material of the sleeve portion 52, the first elastic element 56 and the tube element 62), theoretically, to some extent. The effect of can be expected. However, by using an expensive material having a permanent elongation characteristic superior to that of the main material for the second elastic element 58, the sealing ability of the sealing portion 54a is surely improved, and each sealing portion 5 is
It is possible to exhibit the sealing ability equivalent to that of 4b. From this viewpoint, the characteristics of the material of the covering tube 50 will be described below.

The first elastic element 56, which constitutes the outer layer of the tubular element of the seal portion 54a, is made of an elastomer having physical properties preferable as PST, such as electric insulation, high elastic recovery rate and excellent permanent elongation characteristics. Specific examples of the material of the first elastic element 56 include ethylene propylene rubber (especially EPD).
M), chloroprene rubber, butyl rubber, silicone rubber, natural rubber, fluorine rubber, silicone modified EPDM
And the like. Of these, EPDM is weather resistant,
It has excellent electrical insulation and water resistance, and is inexpensive,
It is a particularly preferable material.

More specifically, the first portion of the seal portion 54a is
The elastic element 56 is made of EPDM having a permanent elongation in the range of 10% to 30% based on the measuring method according to JIS-K6301. For the elastomer having a permanent elongation of less than 10%, silicone rubber is an appropriate material that can be produced by the current technology in consideration of the anti-tracking property required for the electric wire coating material. Generally, it is expensive, and there is a fear that the material cost of the covering tube 50 may increase. On the other hand, the permanent elongation is 1
EPDM in the range of 0% to 30% can be made cheaply and easily. Further, when the permanent elongation exceeds 30%, the tightening force due to the elastic contraction of the first elastic element 56 of the seal portion 54a is deteriorated with the passage of time, and the moistureproof and electric insulating functions of the seal portion 54a tend to be deteriorated. .

The second elastic element 58, which constitutes the inner layer of the tube element of the seal portion 54a, is made of an elastomer having the same physical properties as PST as the first elastic element 56, and in particular, it is measured according to JIS-K6301. Based on the method, silicone rubber with a permanent elongation of less than 10% is a preferred material. If the permanent elongation is 10% or more,
Since only the sealing ability equivalent to that of the elastic element 56, that is, the sealing ability equal to that of each branch portion 54b on the branch electric wire side, can be exhibited, the main electric wire side seal portion 54a having a larger diameter is expanded.
Then, the tightening force due to the elastic contraction of the second elastic element 58 deteriorates with the passage of time, and the moistureproof and electrical insulating functions of the seal portion 54a tend to deteriorate. Such silicone rubber is a material that is extremely expensive as compared with EPDM, but since it is sufficient to dispose only one seal portion 54a in the covering tube 50, the entire covering tube 50 is covered with such a silicone rubber. In comparison, it is possible to suppress the material cost from rising.

Incidentally, the first elastic element 56 of the seal portion 54a.
The other physical properties of the second elastic element 58 (for example, 300% tensile stress, hardness, etc.) are arbitrary within a range suitable for PST.
However, the second elastic element 58 that comes into contact with the electric wire jacket can be formed of a material having a hardness smaller than that of the first elastic element 56 that is exposed to the surrounding environment, and in that case, similar to the covering tube 10 of FIG. Since the second elastic element 58 can easily follow the irregularities on the surface of the electric wire jacket, the sealing ability of the seal portion 54a is further improved.

In addition, the first elastic element 56 of the seal portion 54a.
And the axial length of the second elastic element 58, and the seal portion 5.
The axial length of the tube element 62 of 4b is appropriately set according to the seal distance (the length required to obtain a reliable seal) determined by the voltage applied to the applied electric wire of the covering tube 50. Are preferably 10 mm or more. Similarly, the radial thickness of the pipe element in which the first elastic element 56 and the second elastic element 58 of the seal portion 54a are combined, and the radial thickness of the pipe element 62 of the seal portion 54b are also appropriate according to the seal distance. It is set, but it is preferably 3 mm or more.

Each core element 6 of the seal portions 54a and 54b
Reference numerals 0 and 64 denote cylindrical members made of, for example, hard plastic, which are used to elastically expand the first elastic element 56, the second elastic element 58, and the tube element 62 against the elastic recovery (contraction) force. It has enough rigidity to keep the diameter. Suitable materials for the core elements 60, 64 include cellulose acetate or butyrate, polypropylene, polyethylene, polyvinyl chloride and the like.

Each of the core elements 60 and 64 has the same structure as the core element 20 of the sheath tube 10 of FIG.
Therefore, each core element 60, 64 has a coating tube 50.
When the extension portions 66 are attached to the electric wire connection portion, the extension portions 66 are continuously broken along the weakening line 68 by pulling the extension portions 66 from the outside of the seal portions 54a and 54b.
Removed from 54b.

As described above, in the covering tube 50, the core elements 60 arranged in the seal portions 54a and 54b at the respective open ends,
Regardless of the total length of the covering tube 50, 64 may have a length corresponding to the sealing distance required for the applicable electric wire. As a result, the time required for the removal work of the core elements 60, 64 is significantly reduced as compared to the coated tube having the PST structure over the entire length. Also, the core elements 60, 64
Reduces material costs and waste.

Next, the coated tube 50 having the above structure
The action and effect of will be described. As shown in FIG. 6, at the Y-branch connection portion of the electric wire, the three electric wires 70a, 70b to be connected are connected.
The conductors 74 exposed by the removal of the jacket 72 and the insulator (not shown) are connected to each other by the connector 76. First, the covering tube 50 has three electric wires 70.
Prior to the interconnection of a and 70b, each small-diameter seal portion 5
One branch electric wire 70b is inserted from each of 4b, exposed conductors 74 thereof are drawn out from the large-diameter seal portion 54a to the outside of the covering tube 50, and are connected to the exposed conductors 74 of the main electric wire 70a by the connector 76. . Next, the coating tube 50 is moved to position the connector 76 substantially in the center of the sleeve portion 52, while the end portions of the outer cover 72 of the electric wires 70a and 70b, the exposed conductors 74, and the connector 76 are positioned.
Is placed in a ready position to surround the.

At this time, the inner diameter of the sleeve portion 52 is set so that a gap 78 is formed between the inner surface of the sleeve portion 52 and the outer surfaces of the outer cover 72, the conductor 74, and the connector 76. The frictional resistance when inserting the electric wires 70a and 70b into the tube 50 is reduced, and the electric wires 70a and 70b can be easily inserted. Alternatively, the gap 78 may be reduced as much as possible so that the sleeve portion 52 does not tighten the wire connection portion.
Further, by forming the sleeve portion 52 from the flexible material as described above, it is possible to squeeze the tubular wall of the sleeve portion 52 with a finger and confirm the position of the connector 76 in the covering tube 50. Become.

The covering tube 50 is placed in the above-mentioned preparation position, and the core elements 60 and 64 of the seal portions 54a and 54b are
By pulling the tips of the extension portions 66, the seal portions 54a, 5a, 5a are broken while being spirally broken along the weakening line 68.
Remove from 4b. Thereby, the first elastic element 56 and the second elastic element 58 of the seal portion 54a, and the seal portion 54a.
The tube element 62 of b is respectively the outer sheath 72 of the main electric wire 70a and the branch electric wire 7 under the tightening force by those elastic contractions.
It adheres to the outer surface of the jacket 0b (see FIG. 7). At this time, the second elastic element 58 of the seal portion 54a, which is made of an elastomer having a permanent elongation of less than 10%, causes the seal portion 5 to move.
Although the inner diameter of the tube element 62 of 4b is about twice as large as that of the tube element 62 of 4b, the main electric wire 70 is elastically contracted well.
It comes into close contact with the outer surface of the outer cover 72 of a. In addition, each seal part 5
Since the diameter of the tube element 62 of 4b is expanded within a range in which the required sealing ability can be sufficiently exhibited, the tube element 62 of 4b elastically contracts well and adheres to the outer surface of the jacket 72 of the branch electric wire 70b.

Here, the first elastic element 5 of the seal portion 54a.
6 has a larger diameter than the tube element 62 of the seal portion 54b, but since the second elastic element 58 is arranged on the radially inner side, the amount of expansion in the circumferential direction when the first elastic element 56 is expanded. Is smaller than the same elongation amount of the second elastic element 58. Therefore, even if the first elastic element 56 is made of a material having a permanent elongation characteristic inferior to that of the second elastic element 58, the first elastic element 56 contracts well by the removal of the core element 60, and the first elastic element 56 and the second elastic element 56. It provides the necessary sealing action with 58. Further, as described above, even when both seal portions 54a and 54b seal an electric wire having the same diameter, the first elastic element 56 has the initial inner diameter dimension when the diameter is not expanded by the thickness of the second elastic element 58. Since it can be designed larger than the pipe element 62, and the inner diameter dimension in the sealed state after contraction can be set larger than the pipe element 62 by the thickness of the second elastic element 58, the same elastic elongation characteristic as that of the pipe element 62 causes the first elastic element 56 and Second elastic element 58
To provide the required sealing action. In this way, the seal portion 54a can exhibit the same sealing ability as that of each seal portion 54b.

The first elastic element 56 and the second elastic element 5
If there is a risk that the sealing action between the first elastic element 56 and the first elastic element 56 will be insufficient, the permanent elongation of the material of the first elastic element 56 is approximated to 10% as much as possible, or the first elastic element 56 and the second elastic element 58.
It is desirable to fix the gap between them with an appropriate means such as an adhesive.

The first elastic element 56 and the second elastic element 58 of the seal portion 54a, and the pipe element 62 of the seal portion 54b.
The magnitude of the tightening force due to elastic contraction depends on the value of so-called seal stress (%). In the present embodiment, 5% of the first elastic element 56 and the tube element 62 correspond to the outer diameter dimension of the jacket 72 of the applied electric wires 70a and 70b.
In order to obtain the above-mentioned sealing stress, the diameter dimension of the covering tube 50, in particular, the seal portions 54a and 54b in the non-expanded state (that is, the first elastic element 56 and the tube in the non-expanded state excluding the core elements 60 and 64). The inner diameter dimension of the element 62) is set. As a result, necessary and sufficient moisture proof, electrical insulation, and mechanical protection effects can be obtained for the electric wires 70a and 70b. Note that the seal stress is calculated by the following equation. Seal stress = [(outer diameter of wire jacket 72-inner diameter of first elastic element 56 or tube element 62 when not expanded) / inner diameter of first elastic element 56 or tube element 62 when not expanded] × 100

The moisture-proof and electrical-insulating effects of the electric wire branch connection portion by the above-mentioned coated tube 50 and the grounds for limiting the numerical values will be further clarified by the evaluation results of the following experiments.
The coated tube 50 to be tested is, as shown in Table 5, 1
The sleeve portion 52, the first elastic element 56 and the tube element 62 are integrally formed by die molding from EPDM having a permanent elongation of 0% to 30%, and in particular, three types of P having different permanent elongations are used.
The second elastic element 58 was formed from the ST silicone rubbers i, ii, and iii by die molding, and was arranged radially inside the first elastic element 56. The characteristic values in the table are
It is measured according to JIS-K6301.

[0068]

[Table 5]

Three types of coating tubes in which the respective first elastic elements 56 and the respective second elastic elements 58 were combined to form the seal portion 54a were attached to the Y branch connection portions of the electric wires 70a and 70b. After that, the connection portion was submerged in water, the insulation resistance between the conductor 74 and water was measured by an insulation resistance meter under the condition of DC 1000 V, and the waterproof insulation characteristics were comparatively evaluated (Experiment 1). In addition, air pressure is applied to the electric wire connection portion from the electric wire end portion of the portion away from the electric wire connection portion where the covering tube 10 is mounted,
The pressure at the time of air leak was measured and the airtightness was comparatively evaluated (Experiment 2). The evaluation results are shown in Table 6.

[0070]

[Table 6]

According to the present embodiment, when the waterproof insulation characteristic of 2000 MΩ or more and the airtight characteristic of 0.38 kgf / cm ² or more are obtained, the sealing performance required for the electric wires 70a and 70b is obtained. To do. Therefore, among the above-mentioned materials, a combination of the first elastic element 56 made of EPDM and the second elastic element 58 made of ii (permanent elongation = 9%) or iii (5% of the same) of silicone rubber is
It will be understood that it exhibits excellent sealing performance.

Further, in order to compare the present invention with the prior art, a covering tube 50 made up of a combination of the first elastic element 56 and the second elastic element 58 of iii shown in Table 6 was used, and a comparison target was used. As an example of coating treatment by conventional technology,
(1) The connection portion of the electric wire is covered by winding a waterproof tape. (2) The connection portion is covered with a plastic branch tube member, and both ends of the tube member are sealed with waterproof tape over 30 mm. And (3) a connection part insulated by a branched PST made of silicone rubber based on the prior art. Table 7 shows the evaluation results.

[0073]

[Table 7]

As can be seen from Table 7, the coated tube according to the present invention has far better results in both waterproof insulating property and airtight property than the conventional waterproof tape treatment and pipe member + waterproof tape treatment. The waterproof insulation property and airtight property equivalent to those of the branched type PST made of silicone rubber according to the prior art were obtained. Further, with regard to the material cost, it can be manufactured at a much lower cost than the conventional branched type PST made of silicone rubber.

8-10 show a coated tube 80 according to yet another embodiment of the present invention. Coating tube 80
Is intended to be applied to a Y-branch connection portion of an electric wire such as an SN-OC electric wire having an uneven surface, and the covered tube 10 of FIG. 1 and the covered tube 50 of FIG.
It has a configuration that combines the features of and. Therefore, the covering tube 80 is exposed at the ends of the three electric wires 100a and 100b and is interconnected with the conductor portion 104, and each electric wire 1
Y having a length capable of surrounding the end portions of the electric wire jacket 102 adjacent to the conductor portions 104 of 00a and 100b.
A branched tubular sleeve portion 82 is provided. Sleeve part 82
Is a conductor portion 104 and an electric wire jacket 102 (for example, SN-
It preferably has an inner diameter larger than the outer diameter of the end portion of the ridge 106 as an OC electric wire).
The sleeve portion 82 is essentially made of an elastomer having electrical insulation and flexibility, and is freely deformable in response to the bending of the electric wire to be covered.

Of the three open ends of the sleeve portion 82, one open end through which the main electric wire 100a is passed is formed with a seal portion 84a having a PST structure having three layers of tube elements. That is, the seal portion 84a serves as a pipe element connected to the sleeve portion 82, and is fixed to a tubular first elastic element 86 integrally extended from the sleeve portion 82 and radially inward of the first elastic element 86. Tubular second elastic element 88 to be arranged
And a tubular third elastic element 90 fixedly arranged inside the second elastic element 88 in the radial direction. These elastic elements 86, 88, 90 are made of elastomers having mutually different characteristics as described later. Further, the seal portion 84a includes a large-diameter tubular core element 92 that is removably arranged inside the third elastic element 90 in the radial direction. 2 core elements 92
The branch element 100b has an inner diameter dimension that is sufficiently larger than the total outer diameter dimension of the electric wire jacket 102, and the elastic element 86,
The elastic elements 86, 88, 90 are elastically expanded, and the elastic elements 86, 88, 90 are elastically expanded while maintaining the inner diameter dimension against their elastic recovery (contraction) force.

Of the three open ends of the sleeve part 82, the other two open ends through which the branch electric wire 100b is passed have a two-layer tube element similar to the seal part 14 of the sheath tube 10 of FIG. The seal portion 84b of the structure is formed. That is, each seal portion 84b is a tubular element connected to the sleeve portion 82, and has a tubular first elastic element 94 integrally formed from the sleeve portion 82, and is fixed radially inward of the first elastic element 94. Tubular second elastic element 96 disposed in the
With. The first elastic element 94 and the second elastic element 96 are made of elastomers having mutually different characteristics. Furthermore, each seal portion 84 b includes a small-diameter tubular core element 98 that is removably arranged inside the second elastic element 96 in the radial direction. Each core element 98 has an inner diameter dimension sufficiently larger than the outer diameter dimension of the electric wire jacket 102 of one branch electric wire 100b, and elastically expands the elastic elements 94 and 96, and
The elastic elements 94 and 96 are held in the elastically expanded state while maintaining the inner diameter dimension against their elastic recovery (contraction) force.

When the covering tube 80 is attached to the branch connecting portion of the electric wire, the sleeve portion 82 covers and accommodates the electric wire connecting portion,
The first elastic element 86 and the second elastic element 88 of the seal portion 84a.
And the third elastic element 90, and the first elastic element 94 and the second elastic element 96 of the seal portion 84b are the core elements 92, 9 respectively.
8 is removed to elastically contract, and the electric wire jacket 1 of each of the electric wires 100a and 100b under the tightening force due to the contraction.
It adheres to the part near the end of 02. The sleeve portion 8
2, the first elastic element 86 of the seal portion 84a and the seal portion 8
The first elastic element 94 of 4b is integrally formed from the same material, preferably by an injection molding process.

The first elastic element 86 forming the outer layer of the tube element of the seal portion 84a and the first elastic element 94 forming the outer layer of the tube element of the seal portion 84b have electrical insulation, high elastic recovery rate, and excellent permanent property. It is made of an elastomer having physical properties preferable as PST, such as elongation properties. In particular, similar to the first elastic element 56 of the seal portion 54a of the covering tube 50 of FIG. 5, EPDM having a permanent elongation in the range of 10% to 30% based on the measuring method according to JIS-K6301.
Is a suitable material.

Furthermore, the first elastic element 8 of the seal portion 84a
6 and the 1st elastic element 94 of the seal part 84b are 10 kgf / cm < ² > -based on the measuring method based on JIS-K6301 similarly to the 1st elastic element 16 of the seal part 14 of the coating tube 10 of FIG. 100 kgf / cm ² (0.98MP-9.
It consists of an elastomer having a 300% tensile stress value in the range of 8MP).

The second elastic element 88, which constitutes the intermediate layer of the tube element of the seal portion 84a, is made of an elastomer also having physical properties preferable as PST, and particularly, the second elastic element of the seal portion 54a of the covering tube 50 of FIG. 5 is used. Similar to 58, a silicone rubber having a permanent elongation of less than 10% is a preferable material based on the measuring method according to JIS-K6301.

The third elastic element 90 forming the inner layer of the pipe element of the seal portion 84a and the second elastic element 96 forming the inner layer of the pipe element of the seal portion 84b are also made of an elastomer having physical properties preferable as PST. In particular, similar to the second elastic element 18 of the seal portion 14 of the covering tube 10 of FIG. 1, the measuring method (A according to JIS-K6301)
Based on the shape, silicone rubber having a hardness of 30 Hs or less is a suitable material.

According to the coated tube 80 having the above structure, when the coated tube 80 is used for an electric wire having a modified cross section such as the SN-OC electric wires 100a and 100b, the hardened tube has a hardness of 30 Hs (JIS / A) or less. The third elastic element 90 of the seal portion 84a and the second elastic element 96 of the seal portion 84b, which are made of an elastomer having a thickness, are respectively 10 kgf /
It is formed on the outer surface of the jacket 102 of each wire by the strong tightening force of the first elastic element 86 and the first elastic element 94 made of an elastomer having a 300% tensile stress value of cm ^{2 to} 100 kgf / cm ² . It easily deforms following the irregularities (for example, the protrusions 106). Further, the second elastic element 88 of the seal portion 84a made of an elastomer having a permanent elongation of less than 10%.
Despite the fact that the inner diameter of the seal portion 84b is about twice as large as that of the first elastic element 94 of the seal portion 84b, it elastically contracts satisfactorily and the third elastic element 90 is moved to the outer sheath 1 of the main electric wire 100a.
It adheres to the outer surface of 02. Moreover, since the diameter of the first elastic element 94 of each seal portion 84b is expanded within a range in which the required sealing ability can be sufficiently exerted, the first elastic element 94 elastically contracts well and the second elastic element 96 covers the branch electric wire 100b. It adheres to the outer surface of 102.

[0084]

As is apparent from the above description, according to the present invention, an electric wire having improved mounting workability and coating reliability by disposing the PST structure only in the seal portions near the plurality of open ends. In the covering tube of the connecting portion, the pipe element whose diameter is expanded by the core element in at least one seal portion has a two-layer structure composed of the first elastic element and the second elastic element, so that the physical properties of the material of each layer are appropriately set. By selecting it, it is possible to obtain excellent moisture resistance, electrical insulation and mechanical protection characteristics even for electric wires having irregular cross-sections such as SN-OC electric wires, and also for application to branch connection parts. Even in an application in which different diameter expansion dimensions are required for each seal portion, it has become possible to give a desired sealing ability to a desired seal portion. Therefore, according to the present invention, it is possible to provide a high-performance coated tube for a wire connecting portion at low cost.

[Brief description of drawings]

FIG. 1 is a partially cutaway front view of a covering tube according to an embodiment of the present invention.

2 is a cross-sectional front view of the sheath tube of FIG. 1 attached to a wire connection, showing the core element before removal.

FIG. 3 is a partially cutaway front view of the covering tube of FIG. 1 attached to a wire connecting portion, showing a state after the core element of one sealing portion is removed.

FIG. 4 is a sectional view taken along line IV-IV in FIG. 3;

FIG. 5 is a partially cutaway front view of a covering tube according to another embodiment of the present invention.

6 is a partially cutaway front view of the covering tube of FIG. 5 mounted on a wire connecting portion, showing a state before removal of a core element.

FIG. 7 is a partially cutaway front view of the sheath tube of FIG. 5 mounted on the wire connection, showing the core element after removal.

FIG. 8 is a partially cutaway front view of a covering tube according to still another embodiment of the present invention.

9 is a partially cutaway front view of the sheath tube of FIG. 8 mounted on a wire connection, showing the core element after removal.

10 is a cross-sectional view taken along the line XX of FIG.

[Explanation of symbols]

 10, 50, 80 ... Covering tube 12, 52, 82 ... Sleeve portion 14, 54a, 54b, 84a, 84b ... Sealing portion 16, 56, 86, 94 ... First elastic element 18, 58, 88, 96 ... Second Elastic element 20, 60, 64, 92, 98 ... Core element 90 ... Third elastic element

Claims (6)

[Claims] 1. A tubular sleeve portion made of an electrically insulating elastomer having a plurality of open ends, and an electrically insulating tubular seal portion provided at each of the plurality of open ends of the sleeve portion. A tubular element connected to the sleeve portion, and a removable core element disposed radially inside the tubular element for holding the tubular element in an elastically expanded state. And a first elastic element in which the tube element of at least one of the seal portions is integrally extended from the sleeve portion, and the first elastic element and the core element. And a second elastic element that is sandwiched between the second elastic element and the second elastic element. 2. The covering tube for a wire connecting portion according to claim 1, wherein the second elastic element is made of an elastomer having a hardness lower than that of the first elastic element. 3. The hardness of the second elastic element is 30 Hs or less according to JIS-A standard, and the first elastic element has a hardness of 10 kgf / cm.
The coated tube for a wire connecting portion according to claim 1 or 2, which has a 300% tensile stress value in the range of ^{2 to} 100 kgf / cm ² . 4. The second elastic element is made of an elastomer having a permanent elongation smaller than that of the first elastic element.
The covered tube of the electric wire connecting portion described in. 5. The permanent elongation of the first elastic element is from 10% to.
30%, and the permanent elongation of the second elastic element is 1
It is less than 0%, The coating tube of the electric wire connection part of Claim 4. 6. The tube element of at least one of the seal portions further comprises a third elastic element sandwiched between the second elastic element and the core element, the second elastic element comprising: The first elastic element is made of an elastomer having a smaller permanent elongation, and the third elastic element is made of an elastomer having a lower hardness than the second elastic element.
The covered tube of the electric wire connecting portion described in.