Water-stopping structure for electric wire bundle and its manufacturing method

Abstract

To provide a cut-off structure of a wire bundle which can sufficiently fill a gap between a plurality of wires due to cut-off, even when the respective wires are thick wire bundles.SOLUTION: A cut-off structure 1 of a wire bundle W includes a plurality of wires Wa to Wg, a thermoplastic resin sheet 2 provided so as to be wound around the plurality of wires Wa to Wg, and a heat-shrinkable tube 4 covering the thermoplastic resin sheet 2. The gap between the plurality of wires Wa to Wg is filled with the heated and softened thermoplastic resin sheet 2.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to a waterproof structure for an electric wire bundle and a manufacturing method thereof. [Background technology]

[0002] Conventionally, when a bundle of electric wires (wire harness) is passed through a through hole formed in advance in a plate material, a grommet is attached to the periphery of the through hole to protect the bundle of electric wires from the periphery of the through hole. In order to prevent water from entering from one end side (engine room side) of the through hole to the other end side (inside the vehicle interior) through gaps between the electric wires of the bundle of electric wires, a waterproofing treatment is sometimes applied to the bundle of electric wires. In Patent Document 1, waterproofing is performed by inserting the bundle of electric wires into the through hole of the grommet and filling the gaps between the electric wires with a waterproofing agent such as silicone. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2017-10649 A Summary of the Invention [Problem to be solved by the invention]

[0004] However, when the individual electric wires in a bundle are thick, the gaps between the electric wires become large, and the waterproofing agent such as silicone may not penetrate sufficiently into these large gaps, and the waterproofing agent may not be able to sufficiently fill the gaps between the electric wires.

[0005] The present invention has been made in consideration of the problems inherent in the conventional techniques, and an object of the present invention is to provide a waterproof structure for an electric wire bundle, and a manufacturing method thereof, which can sufficiently fill gaps between a plurality of electric wires to stop water even when each electric wire is a thick electric wire bundle. [Means for solving the problem]

[0006] A waterproof structure for an electric wire bundle according to one embodiment of the present invention comprises a plurality of electric wires, a thermoplastic resin sheet wrapped around the plurality of electric wires, and a heat-shrinkable tube covering the thermoplastic resin sheet, and gaps between the plurality of electric wires are filled with the heated and softened thermoplastic resin sheet.

[0007] A manufacturing method for a waterproof structure for an electric wire bundle according to an embodiment of the present invention includes the steps of wrapping a thermoplastic resin sheet around a plurality of electric wires, covering the thermoplastic resin sheet with a heat shrink tube, and softening the thermoplastic resin sheet by heating the heat shrink tube, and filling gaps between the plurality of electric wires with the softened thermoplastic resin sheet. Effect of the Invention

[0008] According to the present invention, it is possible to provide a waterproof structure for an electric wire bundle and a manufacturing method thereof that can sufficiently fill gaps between multiple electric wires to stop water even when each electric wire is a thick electric wire bundle. [Brief description of the drawings]

[0009] [Figure 1] 1 is a schematic perspective view showing an example of a water stopping structure for an electric wire bundle according to an embodiment; [Diagram 2] FIG. 1 is a schematic plan view illustrating an example of a water stopping structure for an electric wire bundle according to an embodiment. [Diagram 3] FIG. 3 is a cross-sectional view taken along line AA in FIG. 2. [Figure 4] 5A to 5C are explanatory diagrams showing an example of a process in a manufacturing method of a waterproof structure for an electric wire bundle. [Diagram 5] 5A to 5C are explanatory diagrams showing an example of a process in a manufacturing method of a waterproof structure for an electric wire bundle. [Figure 6] 5A to 5C are explanatory diagrams showing an example of a process in a manufacturing method of a waterproof structure for an electric wire bundle. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Hereinafter, a waterproof structure for an electric wire bundle and a manufacturing method thereof according to the present embodiment will be described in detail with reference to the drawings. Note that the dimensional ratios in the drawings are exaggerated for the convenience of explanation and may differ from the actual ratios.

[0011] FIG. 1 is a perspective view showing a waterproof structure 1 for an electric wire bundle W according to this embodiment, FIG. 2 is a plan view showing the waterproof structure 1 for an electric wire bundle W according to this embodiment, and FIG. 3 is a cross-sectional view taken along line AA in FIG. 2.

[0012] The water stopping structure 1 according to this embodiment includes a bundle of electric wires W, also called a wire harness, a thermoplastic resin layer 3, and a heat shrink tube 4.

[0013] The electric wire bundle W is a bundle (a bundle of thick electric wires) of a plurality of (seven in the illustrated example) thick electric wires Wa, Wb, Wc, Wd, We, Wf, and Wg, and these electric wires Wa to Wg extend parallel to each other. In this embodiment, one electric wire Wa of the plurality of electric wires Wa to Wg is disposed at the center of the electric wire bundle W. However, this is not limited to this, and two or more electric wires of the plurality of electric wires Wa to Wg may be disposed at the center of the electric wire bundle W. Note that the terms "thick electric wire" and "thick electric wire" in this specification refer to, for example, a wire having a diameter of 5 mm or more.

[0014] The thermoplastic resin layer 3 is formed of a thermoplastic resin sheet 2 such as a butyl sheet or a hot melt sheet (thermoplastic polymer sheet), and this thermoplastic resin sheet 2 is provided so as to be wound around the plurality of electric wires Wa-Wg. The thermoplastic resin sheet 2 is also provided so as to be wound around the plurality of electric wires Wa-Wg so as to be in contact with all of the plurality of electric wires Wa-Wg. As will be described in detail later, when the heat shrink tube 4 is heated, the thermoplastic resin sheet 2 softens, and the gaps between the plurality of electric wires Wa-Wg are filled with the softened thermoplastic resin sheet 2. Thereafter, the softened thermoplastic resin sheet 2 is cooled and solidified, thereby forming the thermoplastic resin layer 3.

[0015] The heat shrink tube 4 covers the electric wires Wa-Wg constituting the electric wire bundle W and the thermoplastic resin layer 3 (thermoplastic resin sheet 2). The length L (see FIG. 2) of the heat shrink tube 4 is, for example, about 50 mm. The heat shrink tube 4 is formed of a synthetic resin material such as a polyolefin resin. The heat shrink tube 4 may have a double structure with an adhesive layer provided on the inner layer, or may have a single structure with no adhesive layer provided on the inner layer. The adhesive layer (adhesive) provided on the inner layer of the heat shrink tube 4 is, for example, a hot melt adhesive containing a thermoplastic polymer as a component and having a melting point of about 90°C.

[0016] Hereinafter, a method for manufacturing the waterproof structure 1 for an electric wire bundle W according to this embodiment will be described.

[0017] 4 to 6 are explanatory views showing steps in a manufacturing method of a waterproof structure 1 for an electric wire bundle W according to this embodiment.

[0018] First, the thermoplastic resin sheets 2 are arranged so as to be in contact with all of the electric wires Wa to Wg in the electric wire bundle W (see FIG. 4).

[0019] Next, the thermoplastic resin sheet 2 on which the electric wires Wa to Wg are arranged is rolled into a cylindrical shape (see FIG. 5). That is, the thermoplastic resin sheet 2 is wound around the electric wires Wa to Wg in a spiral shape as viewed from the longitudinal direction of the electric wire bundle W so as to come into contact with all of the electric wires Wa to Wg.

[0020] Next, the thermoplastic resin sheet 2 rolled into a cylindrical shape is covered with a heat shrink tube 4 (see FIG. 6).

[0021] Then, the heat shrink tube 4 is heated to soften the thermoplastic resin sheet 2, and the gaps between the plurality of electric wires Wa to Wg are filled with the softened thermoplastic resin sheet 2. After the heat shrink tube 4 is heated, the heat shrink tube 4 is cooled (including natural cooling). In this manner, the thermoplastic resin sheet 2 filling the gaps between the plurality of electric wires Wa to Wg is cooled and solidified, and a thermoplastic resin layer 3 is formed (see FIG. 3).

[0022] The heat shrink tube 4 may be of a double structure with an adhesive layer provided on the inner layer, or may be of a single layer with no adhesive layer provided on the inner layer.

[0023] Due to the shrinkage force of the heat shrink tube 4 and the phenomenon in which the thermoplastic resin sheet 2 becomes soft when heated, the softened thermoplastic resin sheet 2 spreads into the gaps between the plurality of electric wires Wa to Wg.

[0024] After the heat shrink tube 4 has shrunk, the cross-sectional shape of the portion of the electric wire bundle W covered with the heat shrink tube 4 becomes circular, making it possible to place a grommet (not shown) on the heat shrink tube 4, thereby completing the waterproofing treatment of the electric wire bundle W.

[0025] A thermoplastic resin sheet 2 is placed on the electric wire bundle W, and a heat shrink tube 4 is heat-shrunk from above the thermoplastic resin sheet 2, so that gaps between the electric wires Wa-Wg are sealed by the thermoplastic resin sheet 2. Therefore, even if the electric wires Wa-Wg are thick, the electric wire bundle W with the heat shrink tube 4 attached thereto can be passed through the grommet all at once.

[0026] Next, the effect of the waterproof structure 1 for the electric wire bundle W will be described.

[0027] Thus, the waterproof structure 1 for the electric wire bundle W according to this embodiment includes a plurality of electric wires Wa-Wg, a thermoplastic resin sheet 2 provided so as to be wound around the plurality of electric wires Wa-Wg, and a heat-shrinkable tube 4 covering the thermoplastic resin sheet 2. Gaps between the plurality of electric wires Wa-Wg are filled by the heated and softened thermoplastic resin sheet 2.

[0028] By shrinking the heat shrink tube 4 on the thermoplastic resin sheet 2 arranged on the electric wire bundle W, the heat applied during shrinkage and the shrinking force of the heat shrink tube 4 bring the electric wire bundle W and the thermoplastic resin sheet 2 into close contact with each other, filling the gaps between the electric wires Wa to Wg. Then, the thermoplastic resin sheet 2 filling the gaps between the electric wires Wa to Wg is cooled and solidified, forming a thermoplastic resin layer 3. In addition, because a smooth circular cross section is formed by the shrinkage of the heat shrink tube 4, a grommet can be placed directly on the heat shrink tube 4 to ensure the water stopping performance of the water stopping structure 1.

[0029] The flowability of the thermoplastic resin sheet 2 can be ensured by softening the thermoplastic resin sheet 2 due to the heat generated when the heat shrink tube 4 shrinks. This makes it possible to fill (permeate) the gaps between the multiple electric wires Wa to Wg with the thermoplastic resin sheet 2 by utilizing the pressure (shrinkage force) toward the center when the heat shrink tube 4 shrinks.

[0030] After the heat shrink tube 4 shrinks, the cross-sectional shape of the portion of the electric wire bundle W covered with the heat shrink tube 4 becomes circular, making it possible to place a grommet on the heat shrink tube 4, thereby completing the waterproofing of the electric wire bundle W.

[0031] A thermoplastic resin sheet 2 is placed on the electric wire bundle W, and a heat shrink tube 4 is heat-shrunk from above the thermoplastic resin sheet 2, so that gaps between the electric wires Wa-Wg are sealed by the thermoplastic resin sheet 2. Therefore, even if the electric wires Wa-Wg are thick, the electric wire bundle W with the heat shrink tube 4 attached thereto can be passed through the grommet all at once.

[0032] This eliminates the need to fill the gaps between the electric wires with a waterproofing agent as in the past, and saves the labor required for manual work. This makes it possible to reliably prevent water from entering between the electric wires Wa to Wg, improving quality, and reducing the number of workers and costs.

[0033] In the waterproof structure 1 for the electric wire bundle W according to this embodiment, the thermoplastic resin sheet 2 may be provided so as to be wound around the electric wires Wa to Wg so as to be in contact with all of the electric wires Wa to Wg.

[0034] In this manner, by winding the thermoplastic resin sheet 2 around the electric wires Wa to Wg, the gaps can be filled efficiently even if the electric wires Wa to Wg are thick electric wires.

[0035] The manufacturing method of the water-stopping structure 1 for the electric wire bundle W according to this embodiment includes a step of winding a thermoplastic resin sheet 2 around the electric wires Wa to Wg, and a step of covering the thermoplastic resin sheet 2 with a heat-shrinkable tube 4. The manufacturing method of the water-stopping structure 1 for the electric wire bundle W also includes a step of softening the thermoplastic resin sheet 2 by heating the heat-shrinkable tube 4, and filling gaps between the electric wires Wa to Wg with the softened thermoplastic resin sheet 2.

[0036] By shrinking the heat shrink tube 4 on the thermoplastic resin sheet 2 arranged on the electric wire bundle W, the heat applied during shrinkage and the shrinking force of the heat shrink tube 4 bring the electric wire bundle W and the thermoplastic resin sheet 2 into close contact with each other, filling the gaps between the electric wires Wa to Wg. The thermoplastic resin sheet 2 filling the gaps between the electric wires Wa to Wg is then cooled and solidified to form a thermoplastic resin layer 3. In addition, because a smooth circular cross section is formed by the shrinkage of the heat shrink tube 4, a grommet (not shown) can be placed directly on the heat shrink tube 4 to ensure the water stopping performance of the water stopping structure 1.

[0037] The flowability of the thermoplastic resin sheet 2 can be ensured by softening the thermoplastic resin sheet 2 due to the heat generated when the heat shrink tube 4 shrinks. This makes it possible to fill (permeate) the gaps between the multiple electric wires Wa to Wg with the thermoplastic resin sheet 2 by utilizing the pressure (shrinkage force) toward the center when the heat shrink tube 4 shrinks.

[0038] After the heat shrink tube 4 shrinks, the cross-sectional shape of the portion of the electric wire bundle W covered with the heat shrink tube 4 becomes circular, making it possible to place a grommet on the heat shrink tube 4, thereby completing the waterproofing of the electric wire bundle W.

[0039] A thermoplastic resin sheet 2 is placed on the electric wire bundle W, and a heat shrink tube 4 is heat-shrunk from above the thermoplastic resin sheet 2, so that gaps between the electric wires Wa-Wg are sealed by the thermoplastic resin sheet 2. Therefore, even if the electric wires Wa-Wg are thick, the electric wire bundle W with the heat shrink tube 4 attached thereto can be passed through the grommet all at once.

[0040] In the manufacturing method of the waterproof structure 1 for the electric wire bundle W according to this embodiment, the thermoplastic resin sheet 2 may be wrapped around the electric wires Wa to Wg so as to be in contact with all of the electric wires Wa to Wg.

[0041] In this manner, by winding the thermoplastic resin sheet 2 around the electric wires Wa to Wg, the gaps can be filled efficiently even if the electric wires Wa to Wg are thick electric wires.

[0042] Although the present embodiment has been described above, the present embodiment is not limited to this, and various modifications are possible within the scope of the gist of the present embodiment. [Explanation of symbols]

[0043] 1. Water-stopping structure 2 Thermoplastic resin sheet 4 Heat shrink tubing W Wire bundle Wa Electric Wire Wb wire Wc wire Wd wire We wire Wf wire Wg wire

Claims

1. A plurality of wires; A thermoplastic resin sheet provided so as to be wound around the electric wires; A heat shrink tube covering the thermoplastic resin sheet, The heat shrink tube has a double structure in which an adhesive layer is provided on the inner layer, The adhesive layer is made of a hot melt adhesive containing a thermoplastic polymer as a component, Gaps between the plurality of electric wires are filled with the thermoplastic resin sheet softened by heating. Waterproof structure for wire bundles.

2. The waterproof structure for an electric wire bundle according to claim 1 , wherein the thermoplastic resin sheet is provided so as to be wrapped around the plurality of electric wires so as to be in contact with all of the plurality of electric wires.

3. wrapping a thermoplastic resin sheet around a plurality of electric wires; A step of covering the thermoplastic resin sheet with a heat shrink tube having an inner layer made of a hot melt adhesive containing a thermoplastic polymer as a component; and heating the heat shrink tube to soften the thermoplastic resin sheet, thereby filling gaps between the electric wires with the softened thermoplastic resin sheet. A method for manufacturing a waterproof structure for a bundle of electric wires.

4. The method for manufacturing a waterproof structure for an electric wire bundle according to claim 3 , wherein the thermoplastic resin sheet is wrapped around the electric wires so as to be in contact with all of the electric wires.

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