Connecting structure and method for manufacturing the same
The connection structure addresses placement restrictions by using crimped conductors and resin-molded bodies for enhanced waterproofing, enabling flexible LED lamp arrangement and high IPX7 performance.
Patent Information
- Authority / Receiving Office
- JP · JP
- Patent Type
- Applications
- Current Assignee / Owner
- HIRAKAWA HEWTECH
- Filing Date
- 2026-03-03
- Publication Date
- 2026-05-19
AI Technical Summary
Conventional lighting devices restrict the arrangement of straight tube-shaped LED lamps due to direct connection with waterproof sockets, limiting their placement flexibility.
A connection structure involving a first and second conductor connected by a crimped straight butt joint sleeve, covered by a heat-shrinkable tube and resin-molded inner and outer bodies, with adhesive filling gaps for enhanced waterproofing.
Improves waterproof performance, allowing flexible placement of LED lamps and achieving high IPX7 rating, enabling outdoor use in environments like plant cultivation facilities.
Smart Images
Figure 2026083250000001_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to a connection structure and a manufacturing method thereof.
Background Art
[0002] In recent years, in order to reduce the number of components and costs, a waterproof socket capable of directly connecting a straight tube-shaped LED lamp and a lighting device using the same have been proposed (see, for example, Patent Document 1).
[0003] The waterproof socket described in Patent Document 1 accommodates the base portion at one end of a straight tube-shaped LED lamp of a single-side power supply type and supplies power to the straight tube-shaped LED lamp via socket terminals. The socket terminals have a structure for connecting one connection wire and another connection wire. Thereby, power can be supplied from an external power source to a plurality of straight tube-shaped LED lamps via the connection wires, and the straight tube-shaped LED lamps can be used, for example, in a lighting device for artificially cultivating vegetables or the like.
Prior Art Documents
Patent Documents
[0004]
Patent Document 1
Summary of the Invention
Problems to be Solved by the Invention
[0005] According to the conventional lighting device, since the straight tube-shaped LED lamp to be connected is directly connected to the waterproof socket provided on the connection wire, there is a problem that the arrangement of the straight tube-shaped LED lamp is restricted by the waterproof socket (for example, the straight tube-shaped LED lamp cannot be arranged away from the connection wire).
[0006] An object of the present invention is to provide a connection structure with improved waterproof performance and a manufacturing method thereof.
Means for Solving the Problems
[0007] [1] A first electric wire having a first conductor, A second wire having a second conductor, A conductor connection portion that electrically connects the first conductor and the second conductor, A tubular body covering the aforementioned conductor connection portion and its surroundings, The inner molded body is resin-molded on the outside of the tubular body, A connecting structure comprising an outer molded body formed from resin on the outside of the inner molded body. [2] The connection structure according to [1], wherein the number of second conductors is greater than the number of first conductors. [3] The conductor connection portion is the connection structure according to [1] or [2], wherein the first conductor and the second conductor are electrically connected by crimping. [4] The connection structure according to [3], wherein the conductor connection portion is a straight butt joint sleeve. [5] The connecting structure according to [1], wherein the tubular body is a heat-shrinkable tube. [6] The connection structure according to [5], further comprising an adhesive for filling the gap between the inner surface of the heat shrinkable tube and the conductor connection portion and its surroundings. [7] A pair of first wires having a first conductor, Two pairs of second wires having a second conductor, A first conductor connection portion that electrically connects one of the pair of first conductors to one of the two pairs of second conductors, A second conductor connection part that electrically connects the other first conductor of the pair of first conductors and the other second conductor of the pair of second conductors, A first tubular body covering the first conductor connection and its surrounding area, A second tubular body covering the second conductor connection and its surrounding area, The first tubular body and the second tubular body are resin-molded inner molded bodies, A connecting structure comprising an outer molded body formed from resin on the outside of the inner molded body. [8] A connection step of electrically connecting the first conductor of the first electric wire and the second conductor of the second electric wire by a conductor connection part, A covering step of covering the conductor connection portion and its surroundings with a tubular body, A first resin molding step involves positioning the tubular body and then resin molding an inner molded body onto the outside of the tubular body, A method for manufacturing a connecting structure, comprising: a second resin molding step of resin molding an outer molded body onto the outside of the inner molded body while the inner molded body is positioned; and a second resin molding step of resin molding an outer molded body onto the outside of the inner molded body. [9] A first connection step in which one of the pair of first conductors of a pair of first wires and one of the two pairs of second conductors of two pairs of second wires are electrically connected by a first conductor connection part, A second connection step involves electrically connecting the other first conductor of the pair of first conductors and the other second conductor of the pair of second conductors using a second conductor connection part. A first covering step of covering the first conductor connection portion and its surrounding area with a first tubular body, A second covering step in which the second conductor connection portion and its surrounding area are covered with a second tubular body, A first resin molding step involves molding an inner molded body onto the outside of the first tubular body and the second tubular body while the first tubular body and the second tubular body are positioned, A method for manufacturing a connecting structure, comprising: a second resin molding step of resin molding an outer molded body onto the outside of the inner molded body while the inner molded body is positioned; and a second resin molding step of resin molding an outer molded body onto the outside of the inner molded body. [Effects of the Invention]
[0008] According to the present invention, it is possible to improve waterproofing. [Brief explanation of the drawing]
[0009] [Figure 1] Figure 1 is a plan view showing a schematic example of the configuration of a lighting device according to an embodiment of the present invention. [Figure 2A] Figure 2A shows an example of the external shape of the branching section, where (a) is a plan view, (b) is a left side view, and (c) is a right side view. [Figure 2B] FIG. 2B shows an example of the external shape of the branch portion, (d) is a front view, (e) is a rear view, and (f) is a bottom view. [Figure 3] FIG. 3 is a cross-sectional view taken along line C-C of FIG. 2B(d). [Figure 4] FIG. 4(a) is a perspective view for explaining the connection method of the conductors, and FIG. 4(b) is a cross-sectional view taken along line D-D of FIG. 4(a). [Figure 5] FIG. 5 shows an example of the external shape of the inner molded body, (a) is a plan view, and (b) is a front view. [Figure 6] FIG. 6 is a plan view showing an example of the plug connector of Modification 1.
Mode for Carrying Out the Invention
[0010] Hereinafter, embodiments of the present invention will be described with reference to the drawings. In each figure, components having substantially the same function are denoted by the same reference numerals, and redundant descriptions thereof are omitted.
[0011] [Embodiment] FIG. 1 is a plan view showing a schematic configuration example of a lighting device according to an embodiment of the present invention. This lighting device 100 includes a power supply unit 110, a plurality (N) of lighting fixtures 120, and a wire harness 1 that supplies power from the power supply unit 110 to the plurality of lighting fixtures 120. Here, A is the upstream side and B is the downstream side. The power supply unit 110 is an example of a power supply device or an upstream device. The lighting fixture 120 is an example of a connection target or a downstream device. N is, for example, 40, and may also be 2.
[0012] The wire harness 1 comprises a main cable 2A connected to the power supply unit 110, a plurality (N-2) of main cables 2B sequentially connected to the main cable 2A, a main cable 2C connected to the most downstream main cable 2B among the plurality of main cables 2B, a plurality (N-1) of branching points 3 provided one at each of the plurality of branching points on the main cables 2A, 2B, and 2C, a plurality (N-1) of branch cables 4 branched from the plurality of branching points 3, and a plurality (N) of plug connectors 5A provided at the ends of the most downstream main cable 2C and the plurality of branch cables 4 opposite to the branching points 3, to which a plurality of lighting fixtures 120 are connected. When referring to the main cables 2A, 2B, and 2C collectively, they are hereinafter referred to as main cable 2. There are usually two or more branching points 3, but there may be one. Main cable 2 is an example of a main cable. Branch cable 4 is an example of a branch cable.
[0013] In conventional designs, if the lighting fixture 120 is directly connected to the main cable 2 via a waterproof socket, the lighting fixture 120 cannot be placed far from the main cable 2, and its placement is restricted by the waterproof socket. Therefore, this embodiment employs a configuration in which the lighting fixture 120 is connected to the main cable 2 via a branch cable 4. This allows the lighting fixture 120 to be placed at any position (for example, far from or close to the main cable 2) and in any orientation (for example, parallel or perpendicular to the main cable 2), thereby improving the flexibility of the lighting fixture 120's placement.
[0014] Multiple main cables 2B may be the same length. For example, the length of the main cable 2B may be slightly longer than the length of the lighting fixture 120. This allows the lighting fixture 120 to be positioned parallel to the main cable 2B. Alternatively, multiple main cables 2B may be the same length. Furthermore, the length of the downstream main cable 2C (B) may be the sum of the length of the main cable 2B and the length of the branch cable 4. This allows the plug connector 5A side of the main cable 2C to be positioned in the same direction as the branch cable 4, as shown by the dashed line in Figure 1, and the main cable 2C to be treated similarly to the branch cable 4.
[0015] In this embodiment, the main cable 2 and branch cable 4 are, for example, two-core power cables having a pair of power lines. The detailed configuration of the main cable 2 and branch cable 4 in this embodiment will be described later. Note that the main cable 2 and branch cable 4 can be cables having a core configuration appropriate to the connection target, as shown below. (i) Power cable having an earth wire and a pair of power wires (ii) Power cable with three power lines (iii) Signal cable having two or more signal lines (iv) A cable with three or more cores having power lines and signal lines
[0016] Furthermore, the main cable 2 and the branch cables 4 may also be insulated wires in which multiple conductors are spaced apart and their outer circumference is covered with a single insulator. Cables and insulated wires are examples of electric wires.
[0017] The plug connector 5A can be one with a number of poles corresponding to the number of cores in the main cable 2C and the branch cable 4. In this embodiment, the plug connector 5A uses one with a number of poles (2 poles) corresponding to the number of cores (2 cores) in the main cable 2C and the branch cable 4. Furthermore, if waterproofing is required, it is preferable that the plug connector 5A is equipped with a waterproof sealing ring on the mating portion 50. This makes it possible to obtain high waterproofing performance (for example, IPX7 of the IEC standard (no water ingress even when temporarily submerged under a certain water pressure)), and the wire harness 1 can be installed outdoors or in places where watering is performed (for example, a plant cultivation factory). Note that the waterproofing performance may also be IPX6 of the IEC standard (not adversely affected by strong water jets from any direction) or IPX5 (not adversely affected by water jets from any direction).
[0018] As the lighting fixture 120, for example, a single-sided power supply type linear LED lamp can be used. The linear LED lamp comprises a cylindrical pipe member formed from acrylic resin, polycarbonate resin, etc., a pair of cap-shaped cover members that close both ends of the pipe member, a circuit board housed inside the pipe member with multiple LED elements mounted along its longitudinal direction, and a receptacle connector 121 provided on one of the pair of cover members and connected to a plug connector 5A. The LED element is an example of a light-emitting element. Note that the light-emitting element is not limited to an LED element, and may be a fluorescent lamp, incandescent bulb, organic EL, inorganic EL, etc. The number of light-emitting elements may be one per branch cable 4 or per main cable 2C. Note that if waterproofing is required, the receptacle connector 121 is preferably equipped with a waterproof sealing ring at the mating part. This makes it possible to obtain high waterproof performance (for example, IEC standard IPX7, etc.). Note that the waterproof performance may be IEC standard IPX6, IPX5, etc.
[0019] The power supply unit 110 can use a power supply corresponding to the linear LED lamp of the lighting fixture 120. Specifically, if the linear LED lamp has a built-in converter that converts AC power to DC power, the power supply unit 110 can use an AC power supply (e.g., AC100V, AC200V, etc.). If the linear LED lamp does not have the above-mentioned converter built-in, the power supply unit 110 can use a DC power supply (e.g., DC12V, DC24V, etc.).
[0020] Furthermore, the downstream equipment connected to the main cable 2C and the multiple branch cables 4 is not limited to the lighting fixture 120, but may also be the equipment shown below. (i) Equipment that requires a power supply (ii) Equipment that requires a power supply and transmits and receives signals. (iii) Devices that do not require a power supply but transmit and receive signals.
[0021] The upstream equipment connected to the upstream side A of the main cable 2A is not limited to the power supply unit 110, but may also be the equipment shown below. (i) Equipment that supplies power (ii) Equipment that supplies power and transmits and receives signals (iii) Devices that do not receive power but transmit and receive signals
[0022] Examples of signals transmitted and received between upstream and downstream equipment include control signals and drive signals.
[0023] (External shape of the branching section) Figures 2A and 2B show an example of the external shape of the branch section 3, where (a) is a plan view, (b) is a left side view, (c) is a right side view, (d) is a front view, (e) is a rear view, and (f) is a bottom view. The branch section 3 consists of a main cable holding section 3a formed along the main cable 2B and a branch cable holding section 3b formed along the branch cable 4, and has an overall shape that is roughly T-shaped. As will be explained later in Figure 3, it comprises a pair of heat shrinkable tubes 31, an inner molded body 32 formed by resin molding on the outside of the pair of heat shrinkable tubes 31, and an outer molded body 33 formed by resin molding on the outside of the inner molded body 32, and the shape of the outermost outer molded body 33 determines the external shape of the branch section 3. A main cable 2B (or main cable 2A) is led out from the outer molded body 33 to the upstream side A, a main cable 2B (or main cable 2C) is led out from the outer molded body 33 to the downstream side B, and a branch cable 4 is led out from the outer molded body 33 in a direction that intersects with the main cable 2B.
[0024] In this embodiment, the angle θ at which the branch cable 4 is drawn out relative to the main cable 2B(2C) on the downstream side B is 90°, but it may be less than 90° (e.g., 45°) or greater than 90° (e.g., 135°). Alternatively, the branch cable 4 may be drawn out parallel to the main cable 2B(2C) (θ=0°). In this case, the branch cable 4 may be in contact with the main cable 2B(2C) or at a distance from it.
[0025] The trunk cable holding section 3a has tapered ends 3c and 3d so that the thickness of the inner molded body 32 and the outer molded body 33 does not become partially thicker. This makes it easier to inject molten resin into the cavity when forming the inner molded body 32 and the outer molded body 33 by injection molding or the like.
[0026] An overhanging portion 33a protrudes from the base of the roughly T-shaped outer molded body 33, and a mounting hole 33b is formed in the overhanging portion 33a. A cable tie can be passed through the mounting hole 33b, and the branching portion 3 can be attached to a frame (for example, a frame that supports the lighting fixture 120) with the cable tie. Note that the overhanging portion 33a and the mounting hole 33b may be provided in other locations, or in two or more locations. Furthermore, the overhanging portion 33a and the mounting hole 33b may be omitted.
[0027] (Internal structure of the branching section) Figure 3 is a cross-sectional view of line CC in Figure 2B(d). The main cable 2 is, for example, a two-core power cable in which a pair of insulated wires 20 are covered with a sheath 23. The branch cable 4 is, for example, a two-core power cable in which a pair of insulated wires 40 are covered with a sheath 43. The insulated wires 20 of the main cable 2 include a main conductor 21 and an insulator 22 covering the outer circumference of the main conductor 21, as shown in Figure 4 which will be described later. The insulated wires 40 of the branch cable 4 include a branch conductor 41 and an insulator 42 covering the outer circumference of the branch conductor 41, as shown in Figure 4 which will be described later. For example, stranded wires made by twisting together multiple metal strands can be used as the main conductor 21 and the branch conductor 41. Alternatively, single wires may be used instead of stranded wires for the main conductor 21 and the branch conductor 41. The insulators 22 and 42 are formed from resin materials such as polyvinyl chloride and polyethylene. The sheaths 23 and 43 are formed from resin materials such as polyvinyl chloride and polyethylene.
[0028] The branch section 3 comprises a pair of straight butt joint sleeves 30 that electrically connect the main conductors 21 of a pair of insulated wires 20 constituting the main cable 2 on the upstream side A to the main conductors 21 of a pair of insulated wires 20 constituting the main cable 2 on the downstream side B and the branch conductors 41 of a pair of insulated wires 40 constituting the branch cable 4; a pair of heat shrink tubing 31 that cover the pair of straight butt joint sleeves 30 and their surroundings; an inner molded body 32 that is resin-molded on the outside of the heat shrink tubing 31 with the pair of heat shrink tubing 31 positioned relative to an inner molded body mold; and an outer molded body 33 that is resin-molded on the outside of the inner molded body 32 with the inner molded body 32 positioned relative to an outer molded body mold. The straight butt joint sleeves 30 are an example of a conductor connection section. The heat shrink tubing 31 are an example of a tubular body. The heat-shrinkable tube 31, inner molded body 32, and outer molded body 33 are examples of covering parts formed from insulating material. The inner molded body 32 and outer molded body 33 may also be formed from a single molded body.
[0029] The straight butt joint sleeve 30 can be, for example, a JIS C2806 bare crimp sleeve for copper wire. The straight butt joint sleeve 30 is formed from, for example, a soft conductive material (for example, oxygen-free copper). The straight butt joint sleeve 30 electrically connects the upstream main conductor 21 of A and the downstream main conductor 21 and branch conductor 41 of B by crimping them together in a straight line. Alternatively, other sleeves that electrically connect conductors by crimping, or connecting members that electrically connect conductors by welding, fusion, etc., may be used instead of the straight butt joint sleeve 30.
[0030] The heat-shrinkable tube 31 is made from polyethylene resin, polyolefin resin, fluororesin, etc., and shrinks radially when heat is applied. The heat-shrinkable tube 31 may also be a commercially available double-layered tube with a layer of hot-melt adhesive on the inside. In this case, by heating the heat-shrinkable tube with hot-melt adhesive, the heat-shrinkable tube shrinks radially, and the hot-melt adhesive penetrates the gap between the inner surface of the heat-shrinkable tube and the straight butt joint sleeve 30 and its surroundings (insulated wires 20, 40, conductors 21, 41, etc.), filling the gap with the hot-melt adhesive and making it possible to obtain high waterproof performance (for example, IPX7 of the IEC standard). Alternatively, instead of using a heat-shrinkable tube with hot-melt adhesive, it is also possible to apply hot-melt adhesive to the straight butt joint sleeve 30 and its surroundings and then cover the heat-shrinkable tube 31, or to cure a water-resistant adhesive (such as instant adhesive) beforehand and then cover the heat-shrinkable tube 31. Considering the control of the wall thickness of the hot-melt adhesive and the adhesion between the hot-melt adhesive and the heat-shrinkable tube 31 (which is difficult with fluororesins), the aforementioned heat-shrinkable tube with hot-melt adhesive is preferred. The hot-melt adhesive and the water-resistant adhesive are examples of adhesives that fill the gap between the inner surface of the heat-shrinkable tube and the conductor connection part and its surroundings. Alternatively, instead of the heat-shrinkable tube 31, a tubular molded body made of resin may be used, an insulating adhesive such as a hot-melt adhesive may be applied, or insulating tape may be wrapped around it.
[0031] The inner molded body 32 may be formed, for example, from a flexible resin material (e.g., flexible polyvinyl chloride, polyethylene, etc.) by resin molding (e.g., injection molding, compression molding, extrusion molding, calendering, transfer molding, lamination molding, etc.).
[0032] The outer molded body 33 may be formed, for example, from a flexible resin material (e.g., flexible polyvinyl chloride, polyethylene, etc.) by resin molding (e.g., injection molding, compression molding, extrusion molding, calendering, transfer molding, lamination molding, etc.).
[0033] By forming the inner molded body 32 and the outer molded body 33 from a flexible resin material, the branch section 3 can be made flexible, thereby reducing the load on the main cable 2 and the branch cable 4 when they are laid. Furthermore, by forming the inner molded body 32 and the outer molded body 33 by injection molding, it becomes possible to stably mass-produce products of the same quality.
[0034] (Method of connecting conductors) Figure 4(a) is a perspective view illustrating the method of connecting conductors, and Figure 4(b) is a cross-sectional view of the line DD in Figure 4(a). The straight butt joint sleeve 30 has a cylindrical shape and includes a first opening 30a on one side into which the main conductor 21 of the upstream side A is inserted, a second opening 30b on the other side into which the main conductor 21 and branch conductors 41 of the downstream side B are inserted, and a wire stopper 30c provided in the center. The straight butt joint sleeve 30 is used by inserting the main conductor 21 of the upstream side A into the first opening 30a until its tip touches the wire stopper 30c, and inserting the main conductor 21 and branch conductors 41 of the downstream side B into the second opening 30b until their tips touch the wire stopper 30c, and then crimping the crimping portion 30d of the first opening 30a and the crimping portion 30e of the second opening 30b with the main conductor 21 of the upstream side A and the main conductor 21 and branch conductors 41 of the downstream side B in a straight butt position. This allows for easy electrical connection between the main conductor 21 of the upstream side A and the main conductor 21 and branch conductors 41 of the downstream side B.
[0035] (Composition of the inner molded body) Figure 5 shows an example of the external shape of the inner molded body 32, where (a) is a plan view and (b) is a front view. The inner molded body 32 includes a plurality of positioning holes 32a through which positioning pins pass during resin molding, a plurality of positioning protrusions 32b for positioning the inner molded body 32 during resin molding of the outer molded body 33, and two grooves 32c. By providing the grooves 32c, the linear butt joint sleeve 30 with the heat shrink tubing 31 attached can be positioned so that it does not move in the vertical direction in Figure 5(b).
[0036] (Method of manufacturing a wire harness) Next, an example of a method for manufacturing the wire harness 1 will be described.
[0037] (1) Preparation of main cables and branch cables Prepare the main cable 2A at the upstream end A, multiple main cables 2B connected to main cable 2A, the main cable 2C at the downstream end B, and multiple branch cables 4. At this time, expose both ends of the main conductor 21 of the insulated wire 20 of main cable 2, and both ends of the branch conductor 41 of the insulated wire 40 of branch cable 4.
[0038] (2) Connection of conductors using a straight butt sleeve Insert the main conductor 21 of the upstream side A into the first opening 30a of the straight butt sleeve 30 until the tip of the main conductor 21 touches the wire stopper 30c, and insert the main conductor 21 and branch conductor 41 of the downstream side B into the second opening 30b of the straight butt sleeve 30 until the tips of the main conductor 21 and branch conductor 41 touch the wire stopper 30c. Next, crimp the crimping portion 30d of the first opening 30a and the crimping portion 30e of the second opening 30b. This electrically connects the main conductor 21 of the upstream side A and the main conductor 21 and branch conductor 41 of the downstream side B. In this manner, connect the conductors of one branch section 3 using a pair of straight butt sleeves 30, and connect the conductors of the other branch sections 3 in the same way.
[0039] (3) Attaching heat shrink tubing A heat-shrinkable tube 31 with hot-melt adhesive on the inside is placed over the straight butt joint sleeve 30 and its surroundings. Heat is applied to shrink the heat-shrinkable tube 31 radially, and the heat-shrinkable tube 31 covers the straight butt joint sleeve 30 and its surroundings via the hot-melt adhesive. In this manner, one pair of straight butt joint sleeves 30 and one pair of heat-shrinkable tubes 31 with hot-melt adhesive on the inside are attached to one branch section 3, and the same process is repeated for the other branch sections 3.
[0040] (4) Positioning of the heat shrink tubing A pair of heat-shrinkable tubes 31, attached to a pair of straight butt joint sleeves 30 to which the main cable 2 and branch cable 4 are connected, are placed on the lower mold of the inner molded body (not shown). At this time, as shown in Figure 3, a positioning pin is inserted into a hole formed in the lower mold of the inner molded body corresponding to the positioning hole 32a, and the pair of heat-shrinkable tubes 31 and the pair of insulated wires 40 of the branch cable 4 are positioned relative to the lower mold of the inner molded body using the positioning pin. A hole for inserting a positioning pin is also formed in the upper mold of the inner molded body.
[0041] (5) Formation of the inner molded body For example, the inner molded body 32 is formed by injection molding. That is, the lower and upper molds of the inner molded body mold are brought together, and molten first resin (for example, flexible polyvinyl chloride) is injected into the cavity (first space) between the lower and upper molds of the inner molded body mold. After the first resin cools and solidifies, the solidified molded product is released from the inner molded body mold. As a result, the main cable 2 is led out to the upstream side A, and the main cable 2 and branch cables 4 are led out to the downstream side B, and the inner molded body 32 is formed in this manner. The positioning pin is removed from the inner molded body mold. In this way, one inner molded body 32 is formed for one branch section 3, and the same inner molded body 32 is formed for the other branch sections 3.
[0042] (6) Formation of the outer molded body For example, an outer molded body 33 is formed on the outside of an inner molded body 32 by injection molding. That is, the inner molded body 32 is placed on the lower mold of the outer molded body mold, and the upper mold is aligned with the lower mold of the outer molded body mold. At this time, the inner molded body 32 is positioned relative to the outer molded body mold by the positioning projection 32b formed on the inner molded body 32. Note that in the plane of Figures 3 and 5(a), the positioning projection 32b is provided only at the bottom because molten second resin is injected from the spool provided above, pushing the inner molded body 32 downwards. For this reason, the positioning projection 32b may be provided at other locations depending on the position on the spool.
[0043] Next, molten second resin (for example, flexible polyvinyl chloride) is injected into the cavity (second space) between the lower and upper molds of the outer molded body mold. After the second resin cools and solidifies, the solidified molded product is released from the outer molded body mold. As a result, the main cable 2 is led out to the upstream side A, and the main cable 2 and branch cables 4 are led out to the downstream side B, forming the outer molded body 33. One outer molded body 33 is formed for one branch section 3 in this manner, and outer molded bodies 33 are formed similarly for the other branch sections 3.
[0044] (7) Connecting the plug connector Plug connectors 5A are connected to the ends of the main cable 2C at the downstream end B and the multiple branch cables 4. The wire harness 1 is manufactured in this manner. When in use, the main cable 2A at the upstream end A is connected to the power supply unit 110.
[0045] Note that the order of the above steps may be changed. For example, when preparing the main cable 2C and branch cables 4, plug connectors 5A may be connected to the ends of the main cable 2C and the multiple branch cables 4.
[0046] (Effects of the embodiment) This embodiment provides the following effects. (a) Since the lighting fixtures 120 are connected to the main cable 2 via branch cables 4, the degree of freedom in arranging the lighting fixtures 120 can be improved. (b) The main conductor 21 on the upstream side A and the main conductor 21 and branch conductor 41 on the downstream side B are connected with a straight butt joint sleeve 30, and the straight butt joint sleeve 30 and its surroundings are covered with a heat shrink tube 31 via hot melt adhesive, and further covered with a double molded body consisting of an inner molded body 32 and an outer molded body 33, thereby improving the waterproofness of the branch section 3 and making it possible to obtain high waterproof performance (for example, IPX7 of the IEC standard). Depending on the application, a lower waterproof performance than IPX7, such as IPX6 or IPX5 of the IEC standard, may be acceptable, or it may be acceptable to have almost no waterproof performance at all. (c) Power can be supplied to multiple lighting fixtures 120 by main cables 2B and 2C branched from a single main cable 2A and branch cables 4.
[0047] (Variation 1) Figure 6 is a plan view showing an example of a plug connector according to Modification 1. In the above embodiment, a plug connector 5A was used in which the orientation of the mating portion 50 is the same as the longitudinal direction of the branch cable 4. However, the plug connector 5B of Modification 1 is an L-shaped plug connector, and the orientation of the mating portion 50 into which the receptacle connector 121 of the lighting fixture 120 is mated is perpendicular to the longitudinal direction of the branch cable 4. As a result, the lighting fixture 120 can be positioned parallel to the main cable 2 without bending the branch cable 4.
[0048] Similar to plug connector 5A, the L-shaped plug connector 5B should also have a number of poles (2 poles) corresponding to the number of cores (2 cores) of the main cable 2C and branch cable 4. Furthermore, if waterproofing is required, it is preferable that plug connector 5B be equipped with a waterproof sealing ring on the mating portion 50. This makes it possible to obtain high waterproof performance (for example, IEC standard IPX7). Note that waterproof performance may also be IEC standard IPX6, IPX5, etc. [Examples]
[0049] A waterproof performance test was conducted on the heat-shrinkable tube 31 constituting the branch section 3, with and without hot-melt adhesive, and the test results are shown in Table 1.
[0050] (Target of the test) The following Examples 1 and 2 were used as test subjects. In Example 1, a commercially available heat-shrinkable tube with a hot-melt adhesive layer on the inside was used as the heat-shrinkable tube 31. In Example 2, a heat-shrinkable tube without a hot-melt adhesive layer on the inside (adhesive-free) was used as the heat-shrinkable tube 31. In both Examples 1 and 2, the inner molded body 32 and the outer molded body 33 were formed by injection molding.
[0051] (Judgment criteria) Immediately after performing tests for each level of waterproof performance according to IEC standards, a voltage of 1500V was applied between the electrodes for 1 minute, and the presence or absence of dielectric breakdown was used as the determination result. In the determination results in Table 1, a circle (○) indicates no dielectric breakdown (OK), and a cross (×) indicates dielectric breakdown occurred (NG).
[0052] [Table 1]
[0053] (Test results) In Example 1, where a heat-shrinkable tube with hot-melt adhesive was used as the heat-shrinkable tube 31, it was found to meet the IEC standards IPX1 to IPX7. In Example 2, where a heat-shrinkable tube without adhesive was used as the heat-shrinkable tube 31, it was found to meet the IEC standards IPX1 and IPX2. In other words, it was found that the waterproof performance is significantly improved by providing hot-melt adhesive on the inside of the heat-shrinkable tube 31.
[0054] Although embodiments of the present invention have been described above, the embodiments of the present invention are not limited to those described above, and various modifications and implementations are possible. [Explanation of Symbols]
[0055] 1…Wire harness, 2, 2A~2C…Main cable, 3…Branch section, 3a…Main cable holder, 3b…Branch cable holder, 4…Branch cable, 5A, 5B…Plug connector, 20…Insulated wire, 21…Main conductor, 22…Insulator, 23…Sheath, 30…Sleeve for straight butt joint, 30a…First opening, 30b…Second opening, 30c…Wire stopper, 30d, 30e…Crimping section 31…Heat shrink tubing, 32…Inner molded body, 32a…Positioning hole, 32b…Positioning projection, 32c…Groove, 33…Outer molded body, 33a…Protruding part, 33b…Mounting hole, 40…Insulated wire, 41…Branch conductor, 42…Insulator, 43…Sheath, 50…Matching part, 100…Lighting device, 110…Power supply unit, 120…Lighting fixture, 121…Receptacle connector, A…Upstream side, B…Downstream side
Claims
1. A first electric wire having a first conductor, A second electric wire having a second conductor, A conductor connection portion that electrically connects the first conductor and the second conductor, A tubular body covering the aforementioned conductor connection portion and its surroundings, The inner molded body is resin-molded on the outside of the tubular body, The outer molded body is resin-molded on the outside of the inner molded body, A connection structure equipped with [a specific feature].
2. The number of the second conductors is greater than the number of the first conductors. The connection structure according to claim 1.
3. The conductor connection portion electrically connects the first conductor and the second conductor by crimping. The connection structure according to claim 1 or 2.
4. The aforementioned conductor connection portion is a sleeve for straight butt joints. The connection structure according to claim 3.
5. The tubular body is a heat-shrinkable tube. The connection structure according to claim 1.
6. An adhesive is used to fill the gap between the inner surface of the heat shrink tube and the conductor connection part and its surroundings. The connection structure according to claim 5, further comprising the features described in claim 5.
7. A pair of first electric wires (20, 20) having first conductors (21, 21), Two pairs of second wires (20, 20, 40, 40) having second conductors (21, 21, 41, 41), A first conductor connection part (30) electrically connects one of the pair of first conductors (21, 21) and one of the two pairs of second conductors (21, 21, 41, 41), A second conductor connection part (30) electrically connects the other first conductor (21) of the pair of first conductors (21, 21) and the other second conductor (21, 41) of the two pairs of second conductors (21, 21, 41, 41), The first conductor connection portion (30) and the first tubular body (31) covering the surrounding area, The second conductor connection portion (30) and the second tubular body (31) covering its periphery, The first tubular body (31) and the second tubular body (31) are resin-molded inner molded body (32) on the outside, The outer molded body (33) is resin-molded on the outside of the inner molded body (32), A connecting structure (3) equipped with the following:
8. A connection step of electrically connecting the first conductor of the first electric wire and the second conductor of the second electric wire by a conductor connection part, A covering step of covering the conductor connection portion and its surroundings with a tubular body, A first resin molding step involves positioning the tubular body and then resin molding an inner molded body onto the outside of the tubular body, A second resin molding step involves molding an outer molded body onto the outside of the inner molded body while the inner molded body is positioned, A method for manufacturing a connecting structure that includes a connecting structure.
9. A first connection step involves electrically connecting one first conductor (21) of a pair of first conductors (21, 21) of a pair of first electric wires (20, 20) and one second conductor (21, 21, 41, 41) of two pairs of second electric wires (20, 20, 40, 40) using a first conductor connection part (30), A second connection step involves electrically connecting the other first conductor (21) of the pair of first conductors (21, 21) and the other second conductor (21, 41) of the pair of second conductors (21, 21, 41, 41) using a second conductor connection part (30). A first covering step involves covering the first conductor connection portion (30) and its surrounding area with a first tubular body (31), A second covering step in which the second conductor connection portion (30) and its surrounding area are covered with a second tubular body (31), A first resin molding step in which, with the first tubular body (31) and the second tubular body (31) positioned, an inner molded body (32) is resin-molded on the outside of the first tubular body (31) and the second tubular body (31), A second resin molding step involves resin molding an outer molded body (33) to the outside of the inner molded body (32) while the inner molded body (32) is positioned, A method for manufacturing a connecting structure (3) including the connecting structure.