Conductor wire

Abstract

To provide a conductor wire that can maintain a bent shape while using a small diameter Litz wire. [Solution] A conductor wire 1 comprising a central conductor wire 2 and an outer layer conductor wire 5 arranged on the outer circumference of the central conductor wire 2, wherein the outer layer conductor wire 5 is composed of a plurality of outer layer strands 6, the diameter of the central strands 3 constituting the central conductor wire 2 is larger than the diameter of the outer layer strands 6, and a coating 7 is formed on the outer layer strands 6.

Description

Technical Field

[0001] The present invention relates to a conductor wire formed by twisting a plurality of conductor strands and having a bent portion, and particularly to one capable of maintaining a bent shape.

Background Art

[0002] In a conventional structure, it is known that a stator of a rotating electrical machine consists of a stator core and a coil attached to the stator core (see, for example, Patent Documents 1 to 4). In recent years, a segment conductor type rotating electrical machine that forms a coil loop by welding a plurality of U-shaped or S-shaped coil segments is also known (see, for example, Patent Documents 5 to 6).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Patent Document 3

Patent Document 4

Patent Document 5

Patent Document 6

Summary of the Invention

Problems to be Solved by the Invention

[0004] While the segment conductor system offers a high coil occupancy rate within the volume of a rotating electric machine, it faces the challenge of larger eddy current losses compared to conventional bundled coils in rotating electric machines used at high speeds (high frequencies). Eddy current losses are heavily influenced by frequency and leakage flux, with leakage flux acting most strongly on the inner diameter side of the coil (closest to the rotor). Therefore, it has been known that rotating electric machines used at high speeds (high frequencies) have drawbacks in terms of power efficiency. Although it is known that reducing leakage flux and thus eddy current losses can be achieved by forming coils with thin-diameter conductors called Litz wires, it is difficult to maintain the shape of the coil segments with thin-diameter Litz wires, making it challenging to preserve the U-shape of the coil segments. Maintaining the U-shape of the coil segments is required for simple and stable stator assembly, whether in automated manufacturing processes using robots or manual processes.

[0005] This invention was made to solve the problems of the prior art, and its objective is to provide a conductor wire that can maintain a bent shape while using a small diameter Litz wire. [Means for solving the problem]

[0006] To achieve the above objective, the conductor wire according to the present invention is a conductor wire comprising a central conductor wire and an outer layer conductor wire arranged on the outer circumference of the central conductor wire, wherein the outer layer conductor wire is composed of a plurality of outer layer strands, the diameter of the central strand constituting the central conductor wire is larger than the diameter of the outer layer strands, and a coating is formed on the outer layer strands. Furthermore, it is conceivable that the outer layer conductor wire is formed by twisting the outer layer strands together so as to follow the outer circumference of the central conductor wire. Furthermore, it is conceivable that the outer layer wires have a fixing portion in which they are fixed to other outer layer wires via the coating. Furthermore, the conductor wire has a pair of ends, and the conductor wire has a substantially straight section extending substantially in a straight line from the ends, as well as a bent section continuous with the substantially straight section, and the conductor wire has the fixing section at a position from the boundary between the substantially straight section and the bent section, in the direction of the substantially straight section, and until the outer layer strands make one full rotation around the outer circumference of the central conductor wire. Furthermore, it is conceivable that the above-mentioned central conductor wire consists of a single central strand. Furthermore, it is possible that the aforementioned central conductor wire is made up of multiple central strands twisted together. Furthermore, it is possible that the outer layer wires mentioned above are made by twisting together thin wires. Furthermore, it is possible that the outer layer conductor wire is made by twisting together the outer layer strands. Furthermore, it is possible that the central strand mentioned above is compressed. Furthermore, it is conceivable that the direction in which the outer layer conductor wires are twisted together along the outer circumference of the central conductor wire is the same as the direction in which the thin-diameter strands constituting the outer layer strands are twisted. Furthermore, it is possible that a gap is formed between the central conductor wire and the outer layer conductor wire. Furthermore, it is conceivable that an insulating coating is formed on the outer circumference of the above-mentioned outer layer conductor wire. [Effects of the Invention]

[0007] According to the present invention, since it is possible to maintain a bent shape while using a small-diameter Litz wire, the coil segment, which is the conductor wire, can be easily inserted into the stator core while maintaining its U-shape. Furthermore, because a small-diameter Litz wire is used, the amount of leakage magnetic flux can be reduced, resulting in good power efficiency. [Brief explanation of the drawing]

[0008] [Figure 1] This figure shows an embodiment of the present invention, a partially cutaway side view of a conductor wire. [Figure 2] This figure shows a schematic cross-sectional view of a conductor wire, illustrating an embodiment of the present invention. [Figure 3]This figure shows an embodiment of the present invention, a partially cutaway side view of a conductor wire. [Figure 4] This figure shows a schematic cross-sectional view of a conductor wire, illustrating an embodiment of the present invention. [Figure 5] This figure shows an embodiment of the present invention, a partially cutaway side view of a conductor wire. [Figure 6] This figure shows a schematic perspective view of a conductor wire, illustrating an embodiment of the present invention.

[0009] The conductor wire 1 according to Embodiment 1 will be described with reference to Figures 1 and 2. First, the conductor of the central conductor wire 2 is composed of a single central strand 3 made of tinned soft copper wire with a diameter of 1.2 mm, which is thicker than the outer layer strands 6. Next, a coating 4 consisting of an outer layer of PU (polyurethane) and an inner layer of PAI (polyamide-imide) is applied to the outer circumference of the single central strand 3 by dip and roll scraping to form a total thickness of 0.0035 mm, thereby forming the central conductor wire 2. An outer layer conductor wire 5 is formed on the outer circumference of this central conductor wire 2. The outer layer conductor wire 5 is composed of multiple outer layer strands 6, and a coating 7 with a thickness of 0.0035 mm is formed on the outer layer strands 6, similar to the central conductor wire 2. The diameter of the outer layer strands 6 after coating is 0.20 mm, and it is composed of S-twist with a sub-twist pitch of 15 mm and S-twist with a main twist pitch of 30 mm. The outer layer conductor wire 5 is formed by twisting 98 of these outer layer strands 6 together in an S-twist with a twist pitch of 30 mm along the outer circumference of the central conductor wire 2. These outer layer strands 6 are also called Litz wire. After twisting the outer layer conductor wire 5 onto the outer circumference of the central conductor wire 2, a PI (polyimide) tape is wrapped horizontally as an insulating coating 8 to create the conductor wire 1. Here, after the horizontal wrapping of the insulating coating 8, the conductor wire 1 is pressed into a four-way simultaneous roll called a Turks roll system or Turks head roll, which allows it to have the rectangular cross-sectional shape shown in Figure 2.

[0010] Furthermore, the conductor wire 1 according to Embodiment 2 will be described with reference to Figures 3-4. First, the conductor of the central conductor wire 2 is thicker than the outer layer strands 6 and is composed of seven central strands 3 made of tinned soft copper wire with a diameter of 0.4 mm each. At this time, the central conductor wire 2 may be compressed as needed. Next, a coating 4 consisting of an outer layer PU (polyurethane) and an inner layer PAI (polyamide-imide) is applied to the outer circumference of the central strands 3 by dip and roll scraping to form a total thickness of 0.0035 mm, thereby forming the central conductor wire 2. After the formation of the central conductor wire 2, an outer layer conductor wire 5 is formed on the outer circumference of the central conductor wire 2, as in Embodiment 1. The outer layer conductor wire 5 is composed of multiple outer layer strands 6, and a coating 7 with a thickness of 0.0035 mm is formed on the outer layer strands 6, similar to the central conductor wire 2. The diameter of the outer layer strands 6 after coating is 0.20 mm, and it is composed of S-twist with a sub-twist pitch of 15 mm and S-twist with a main twist pitch of 30 mm. The outer layer conductor wire 5 is formed by twisting 98 of these outer layer strands 6 together in an S-twist with a twist pitch of 30 mm along the outer circumference of the central conductor wire 2. These outer layer strands 6 are also called Litz wire. After forming the outer layer conductor wire 5 on the outer circumference of the central conductor wire 2, a PI (polyimide) tape is wrapped horizontally as an insulating coating 8 to create the conductor wire 1. Here, after the horizontal wrapping of the insulating coating 8, the conductor wire 1 can be pressed into a four-way simultaneous roll called a Turks roll system or Turks head roll to obtain the rectangular cross-sectional shape shown in Figure 4.

[0011] In the conductor wire 1 of Embodiments 1 and 2, a bent portion 12 can be formed by bending the wire at three predetermined angles, resulting in a U-shape as shown in Figures 5 and 6. The bending method can be any known method, such as using a jig or bending with an automatic processing machine. The conductor wire 1 has a substantially straight portion 11 extending from a pair of ends 10 to the bent portion 12, with the boundary between the substantially straight portion 11 and the bent portion 12 being defined as the boundary portion 13. Furthermore, the substantially straight portion 11 in Figures 5 and 6 has a substantially rectangular cross-sectional shape. However, for use as a coil segment of a stator, the substantially straight portion 11 may also incorporate twists or other shapes, and its cross-sectional shape may be deformed from a substantially rectangular shape.

[0012] It is preferable that, in the direction from the boundary portion 13 toward the substantially straight portion 11 and at a position until the outer layer strands 6 go around the outer periphery of the center conductor wire 2, there is a fixing portion 14 in which the outer layer strands 6 are fixed to other outer layer strands 6 via the coating 7. Preferably, in the circumferential direction of the substantially straight portion 11, all the outer layer strands 6 are fixed to each other. Also, it is preferable that the longer the length of the portion where the fixing occurs in the longitudinal direction of the substantially straight portion 11 is, the greater the fixing strength of the fixing portion 14 is. By having the fixing portion 14, it is possible to suppress the outer layer strands 6 from slipping relative to each other at the bent portion 12, and prevent the outer layer strands 6 from shifting in the longitudinal direction. Therefore, it is possible to prevent the ends of the outer layer strands 6 from being uneven, and improve the dimensional stability of the stator core to which the conductor wire 1 is assembled. The formation of the fixing portion 14 may be performed by a method of welding (compacting) while compressing a predetermined portion, a method of melting the coating 7 by heating, a so-called caulking using a caulking fitting or the like, soldering, brazing, fixing with an adhesive, friction stir welding, or the like. Also, in the case of welding, various welding methods such as arc welding, gas welding, resistance welding, and laser welding may be appropriately used.

[0013] Regarding the conductor wire 1 of Embodiments 1 and 2, the bent portion 12 is formed with a bending angle of 120 degrees, and the length of the substantially straight portion 11 is 120 mm. The portion from the boundary portion 13 toward the substantially straight portion 11 and until the outer layer strands 6 go around the outer periphery of the center conductor wire 2 is present at a position 30 mm from the bent portion 12.

[0014] Also, as shown in FIGS. 2 and 4, there may be a gap between the center conductor wire 2 and the outer conductor wire 5. By having a gap between the center conductor wire 2 and the outer conductor wire 5, it is possible to suppress the heat spot phenomenon that occurs when the outer conductor wire 5 crushes the center conductor wire 2 and the outer conductor wire 5 breaks. There is no limitation on the method of forming the gap. For example, when the conductor wire 1 is pushed into a predetermined mold to have a rectangular cross-sectional shape, a mold with a margin in volume can be used to naturally form a gap.

[0015] In Embodiments 1 and 2, the outer layer strands 6 are aligned around the outer circumference of the central conductor wire 2 and twisted together along the outer circumference of the central conductor wire 2 to form the outer layer conductor wire 5. Before this, the outer layer strands 6 may be twisted together first. By twisting only the outer layer strands 6 together first, the floating of the outer layer strands 6 can be suppressed, and the fine irregularities that appear on the insulating coating 8 of the conductor wire 1 can be reduced.

[0016] In embodiments 1 and 2, the wire diameters of the central strand 3 and the outer layer strand 6 are different, resulting in a difference in resistance and an unbalanced resistance value for each strand. However, in AC rotating electric machines used at high speeds (high frequencies), the current flow obstruction called impedance is largely influenced by the reactance component, while the resistance component does not depend on frequency and is therefore masked by the effect of reactance. For this reason, the conductor wire 1 of embodiments 1 and 2 is a particularly preferred configuration for AC rotating electric machines used at high speeds (high frequencies). Furthermore, in the high-frequency range, the skin effect is known, in which a back electromotive force is generated near the center of the conductor due to mutual inductance, causing current to flow on the surface of the conductor. Therefore, even if the central strand 3 is thicker than the outer layer strand 6, only the surface of the conductor is used as the path for current flow, so the effect of the difference in cross-sectional area is small even when using conductors with different cross-sectional areas.

[0017] The present invention is not limited to the embodiments described above, and other embodiments such as the following are also conceivable.

[0018] The materials and stranding configuration of the central conductor wire 2, central strands 3, outer layer conductor wire 5, and outer layer strands 6 can be appropriately designed to suit the intended use and purpose. For example, as the material for the conductor strands, in addition to the tinned soft copper wire mentioned above, wires made of various conductor materials such as nickel-plated soft copper wire, soft copper wire, copper alloy wire, aluminum alloy wire, and stainless steel wire can be used. Furthermore, the stranding pitch and stranding direction (S-twist, Z-twist) can also be appropriately set according to the required characteristics. The central conductor wire 2 and outer layer conductor wire 5 can also be made of composite strands. Here, when an insulating coating 8 is formed on the outer circumference of the outer layer conductor wire 5, it is preferable that the stranding direction of the outer layer strands 6 constituting the outer layer conductor wire 5 and the direction in which the outer layer conductor 5 is wound along the outer circumference of the central conductor wire 2 are in the same direction. This makes it less likely for wrinkles to form in the insulating coating 8 when the conductor wire 1 is bent. It is also preferable that the central strand 3 is located in the central part of the conductor wire 1. This makes it less likely for the twist to break down during bending, and also improves the shape stability and reproducibility of the bent shape.

[0019] In the above embodiment 2, the central conductor wire 2 may be subjected to compression. This increases the conductor occupancy rate per unit cross-sectional area, allowing for a reduction in the diameter of the conductor wire 1. Note that the higher the compression ratio, the better the maintenance of the bent shape, but the more difficult the bending process becomes. Therefore, whether or not to compress, the degree of compression, and the compression method should be designed appropriately according to the required characteristics. A compression ratio of approximately 1 to 5% is preferable. The compression ratio can be calculated as [(outer diameter before compression - outer diameter after compression) / outer diameter before compression].

[0020] Furthermore, the conductor wire 1 of the present invention can also be made into an insulated wire by forming any insulating coating 8. For example, the insulating coating 8 can be formed by solid extrusion or tubing extrusion. When the insulating coating 8 is formed by solid extrusion, the insulating coating 8 bites into the outer circumference of the outer layer conductor wire 5, which tends to make bending difficult. On the other hand, with tubing extrusion, a gap can be formed between the outer circumference of the outer layer conductor wire 5 and the insulating coating 8, making bending easier, but if the bending angle is large or the bending radius is small, the insulating coating 8 may wrinkle. Depending on the required bending shape, it is conceivable to appropriately use solid extrusion and tubing extrusion. In addition, an insulating tube that is attached afterwards can also be considered as one form of insulating coating 8. It is possible to use the conductor wire 1 without forming the insulating coating 8. Various materials can be used to constitute the insulating coating 8, such as polyethylene resin, polypropylene resin, polyurethane resin, polyester resin, fluororesin, aromatic polyamide resin, aliphatic polyamide resin, vinyl chloride resin, modified noryl resin (polyphenylene oxide resin), polystyrene resin, synthetic rubber, fluororubber, silicone rubber, acrylic rubber, butyl rubber, chloroprene rubber, ethylene-based thermoplastic elastomer, urethane-based thermoplastic elastomer, styrene-based thermoplastic elastomer, polyester-based thermoplastic elastomer, etc. In addition, materials such as glass fibers, aromatic polyamide fibers, polyphenylene sulfide fibers, and polyester fibers that are braided together and coated with various paints can also be used as appropriate.

[0021] Various types of connectors can be attached to both ends of the conductor wire 1 as described above. Methods for attaching the connectors include, for example, crimping using a crimping tool, soldering, brazing, adhesive fixing, and friction stir welding. In the case of welding, various welding methods such as arc welding, gas welding, resistance welding, and laser welding can be used as appropriate.

[0022] As detailed above, the conductor wire and insulated wire according to the present invention have excellent properties for maintaining their bent shape. Such conductor wires and insulated wires can be suitably used as lead wires and power wires in various devices such as rotating electric machines, home appliances, industrial machinery, automobiles, and power supply devices. [Industrial applicability]

[0023] As detailed above, the conductor wire according to the present invention has excellent properties for maintaining its bent shape. Such a conductor wire can be suitably used as coil segments, lead wires, and power lines in various devices such as rotating electric machines, home appliances, industrial machinery, automobiles, and power supply devices. [Explanation of symbols]

[0024] 1 Conductor wire 2. Center conductor wire 3 Center strand 4 Covering 5. Outer layer conductor wire 6 Outer layer wire 7 Coating 8. Insulating coating 10 End 11. Roughly straight section 12. Bending section 13 Boundary

Claims

1. A conductor wire consisting of a central conductor wire and an outer layer conductor wire arranged around the outer circumference of the central conductor wire, The above outer layer conductor wire is composed of multiple outer layer strands, The diameter of the central strand constituting the above central conductor wire is greater than the diameter of the outer layer strand. A conductor wire in which a coating is formed on the outer layer strands described above.

2. The conductor wire according to claim 1, wherein the outer layer conductor wire is formed by twisting the outer layer strands together along the outer circumference of the central conductor wire.

3. The conductor wire according to claim 2, wherein the outer layer strand has a fixing portion that is fixed to another outer layer strand via the coating.

4. The above conductor wire has a pair of ends, The above-mentioned conductor wire has a substantially straight section extending substantially in a straight line from the above-mentioned end, and also has a bent section continuous with the substantially straight section. When the boundary between the above-mentioned substantially straight section and the above-mentioned bent section is defined as the boundary of the above-mentioned conductor wire, The conductor wire according to claim 3, wherein the fixing portion is located at a position from the boundary portion in the direction of the substantially straight portion and until the outer layer strands make one full circle around the outer circumference of the central conductor wire.

5. The conductor wire according to claim 4, wherein the above-mentioned central conductor wire consists of a single central strand.

6. The conductor wire according to claim 4, wherein the central conductor wire is made up of multiple central strands twisted together.

7. The conductor wire according to claim 4, wherein the outer layer strands are made by twisting together small-diameter strands.

8. The conductor wire according to claim 4, wherein the outer layer conductor wire is formed by twisting together the outer layer strands.

9. A conductor wire according to any one of claims 1 to 8, wherein the above-mentioned central strand is compressed.

10. A conductor wire according to any one of claims 1 to 8, wherein the direction in which the outer layer conductor wires are twisted together along the outer circumference of the central conductor wire and the direction in which the thin-diameter strands constituting the outer layer strands are twisted are the same.

11. A conductor wire according to any one of claims 1 to 8, wherein a gap is formed between the central conductor wire and the outer layer conductor wire.

12. A conductor wire according to any one of claims 1 to 8, wherein an insulating coating is formed on the outer circumference of the outer layer conductor wire.

Images