INOSHITA HIROFUMI (JP)
ADACHI HIRONARI (JP)
MIZUSHIMA DAISUKE (JP)
| JP2002027693A | 2002-01-25 |
| CLAIMS: 1. A manufacturing method for a collective conducting wire, comprising: applying a lubricant, to which sulfate is added, onto a plurality of conductor lines; forming a conductor bundle by bundling the plurality of the conductor lines; and forming the collective conducting wire by performing plastic working of the conductor bundle. 2. The manufacturing method for the collective conducting wire according to claim 1 , wherein an oxide film containing CuO is formed on surfaces of the conductor lines after the plastic working. 3. The manufacturing method for the collective conducting wire according to claim 1 or 2, wherein a product containing CuS04 is formed on the surfaces of the conductor lines after the applying. 4. The manufacturing method for the collective conducting wire according to any one of claims 1 to 3, further comprising: heating the collective conducting wire after the collective conducting wire is formed by the plastic working. 5. The manufacturing method for the collective conducting wire according to any one of claims 1 to 4, wherein the concentration of the sulfate in the lubricant is 1.0 to 2.4 mol / 1. 6. The manufacturing method for the collective conducting wire according to any one of claims 2 to 5, wherein the oxide film has a thickness of 130 nm to 300 nm. 7. A motor comprising: a coil made of the collective conducting wire manufactured by the manufacturing method according to any one of claims 1 to 6. |
MOTOR
BACKGROUND OF THE INVENTION
1. Field of the Invention
[0001] The invention relates to a manufacturing method for a collective conducting wire, and a motor. 2. Description of Related Art
[0002] There is a collective conducting wire in which a plurality of conductor lines are bundled. In such a collective conducting wire, an insulation film is sometimes formed between each of the bundled conductor lines. The conductor lines are insulated from each other by the insulation film. Use of this kind of collective conducting wire as a coil is preferred because of an eddy-current loss becomes low.
[0003] For example, in a manufacturing method disclosed in Japanese Patent Application Publication No. 2002-027693 (JP 2002-027693 A), after a plurality of conductor lines covered by an insulation film is bundled, the plurality of bundled conductor lines are press-formed, thereby manufacturing a collective conducting wire.
[0004] However, in the manufacturing method disclosed in JP 2002-027693 A, the insulation film is sometimes ruptured at the time of press forming, causing electric connection between the conductor lines with each other.
SUMMARY OF THE INVENTION
[0005] The invention provides a manufacturing method for a collective conducting wire, in which it is further ensured that conductor lines are insulated from each other, and a motor. [0006] A first aspect of the invention relates to a manufacturing method for a collective conducting wire. The manufacturing method for the collective conducting wire includes applying a lubricant, to which sulfate is added, onto a plurality of conductor lines (for example, strands), forming a conductor bundle (for example, a bundled collective conductor) by bundling the plurality of the conductor lines, and forming the collective conducting wire (for example, a collective conductor) by performing plastic working of the conductor bundle.
[0007] According to the above aspect, the collective conducting wire is manufactured, in which it is further ensured that the conductor lines are insulated from each other.
[0008] In the above aspect, an oxide film containing CuO may be formed on surfaces of the conductor lines after the plastic working. A product containing CuS0 4 may be formed on the surfaces of the conductor lines after the applying. The manufacturing method may further include heating the collective conducting wire after the collective conducting wire is formed by the plastic working. A concentration of the sulfate in the lubricant may be 1.0 to 2.4 mol / 1. A thickness of the oxide film may be 130 nm to 300 nm.
[0009] Meanwhile, a second aspect of the invention relates to a motor. The motor has a coil that is made of the collective conducting wire manufactured by the manufacturing method for a collective conducting wire stated above.
[0010] According to the above aspect, a motor having a coil with low eddy-current loss is obtained.
BRIEF DESCRIPTION OF THE DRAWINGS
[0011] Features, advantages, and technical and industrial significance of exemplary embodiments of the invention will be described below with reference to the accompanying drawings, in which like numerals denote like elements, and wherein: FIG. 1 is a sectional view of a collective conducting wire according to a first embodiment of the invention;
FIG. 2 is a flowchart showing a manufacturing method according to the first embodiment of the invention;
FIG. 3 is a schematic view showing an example of the manufacturing method according to the first embodiment of the invention;
FIG. 4 is a graph showing electric resistance relative to an oxide film thickness; and
FIG. 5 is a graph showing a decreasing rate of eddy-current loss.
DETAILED DESCRIPTION OF EMBODIMENTS
First embodiment
[0012] A collective conducting wire obtained by a manufacturing method according to a first embodiment is explained with reference to FIG. 1. FIG. 1 is a sectional view of a collective conducting wire according to the first embodiment.
[0013] As shown in FIG. 1 , a collective conducting wire 20 is a linear- body including one center strand 1 and a plurality of peripheral strands 2. In the section of the collective conducting wire 20, the peripheral strands 2 are arranged so as to surround the center strand 1. An insulation film 3 is formed between the center strand 1 and the peripheral strands 2. In the section of the collective conducting wire 20, the insulation film 3 is a film having a length L and a thickness t. The length L is equal to a circumference of the center strand 1 and a part of a circumference of the peripheral strand 2. The thickness t does not necessarily have to be constant, and only needs to be within a given range. The insulation film 3 electrically insulates the center strand 1 and the peripheral strands 2 from each other, and also electrically insulates peripheral strands 2 from each other. When the collective conducting wire 20 is used as a coil, it is possible to obtain a coil with low eddy-current loss. [0014] Next, a manufacturing method according to the first embodiment is explained with reference to FIG. 2. FIG. 2 is a flowchart showing the manufacturing method according to the first embodiment.
[0015] First of all, lubricant is applied to a plurality of strands (application step S I). The plurality of strands may be aligned in one direction by using a roller and so on for the sake of workability. As the strands, conductor lines may be used, which are made of a material containing at least copper. Examples of the material include copper and copper alloy. An example of the lubricant used here is a lubricant used for wire drawing, to which sulfate (R - O - S0 2 - O - R) is added. An example of sulfate is dimethyl sulfate.
[0016] When the lubricant is applied on the strands, sulfate and copper (Cu) contained in the strands react to each other. Then, a product containing copper sulfate (CuS0 4 ) is formed on surfaces of the strands.
[0017] Next, a conductor bundle is formed by bundling the plurality of strands (bundling step S2). In order to adjust a space between the strands, arrangement of each of the strands may be changed as appropriate.
[0018] Next, a collective conducting wire is formed by conducting plastic working of the conductor bundle (plastic working step S3). Examples of the plastic working include alignment, twisting, and pressing. Due to the plastic working, the collective conducting wire sometimes generates heat. Due to the heat generation, a product containing CuS0 4 could have a chemical reaction expressed by chemical formula 1.
CuS0 4 → CuO + S0 3 ... (Chemical formula 1)
When this chemical reaction happens, an oxide film containing CuO is formed on surfaces of the strands.
[0019] Finally, the collective conducting wire is heated in a heating furnace as necessary (heating step S4). Instead of the heating furnace, a high-frequency heating apparatus, for example, may be used. The chemical reaction expressed by the chemical formula 1 is promoted further, and it is further ensured that the oxide film containing CuO is formed on the surfaces of the strands. Also, the thickness of the oxide film containing the CuO is increased.
[0020] Next, an example of the above-mentioned manufacturing method according to the first embodiment is explained by using FIG. 3. FIG. 3 is a schematic view showing an example of the manufacturing method according to the first embodiment. This example is a manufacturing method for continuously manufacturing a collective conducting wire 202 from a group of conductor lines 198 by using a manufacturing apparatus 140. In FIG. 3, a state of the group of conductor lines 198 is schematically shown where conductor lines 109 are aligned from the back to the front of the sheet surface.
[0021] A strand feeder 141 sends the group of conductor lines 198 to first rolling mill rolls 142. As shown in a schematic view 158, the conductor line 109 is a linear body having a circular section. The conductor line 109 is a part of the group of conductor lines
198 that form peripheral strands 1 10.
[0022] The first rolling mill rolls 142 receive the group of conductor lines 198 from the strand feeder 141 , and form the peripheral strands 1 10 from a part of the group of conductor lines 198 as shown in a schematic view 159. The first rolling mill rolls 142 plastically deform the conductor lines 109. A sectional shape of the peripheral strand 1 10 is, for example, a trapezoid.
[0023] The first rolling mill rolls 142 send a group of strands 199, which is made of the peripheral strands 1 10 and a center strand 130, to a speed-adjusting guide roller 143.
A state of the group of strands 199 is schematically shown where each of the strands is aligned from the back to the front of the sheet surface.
[0024] The speed-adjusting guide roller 143 receives the group of strands 199 from the first rolling mill rolls 142, and removes flexure of the peripheral strands 1 10 caused in a strand processing step. The speed-adjusting guide roller 143 sends the group of strands 199 to the direction-adjusting rollers 144.
[0025] The direction-adjusting rollers 144 receive the group of strands 199 from the speed-adjusting guide roller 143. The direction-adjusting rollers 144 expand each of the strands of the group of strands 199 and creates a positional relationship in which the peripheral strands 1 10 surround the center strand 130.
[0026] The direction-adjusting rollers 144 also adjust positions and directions of the peripheral strands 1 10 so that an inner periphery of the peripheral strand 1 10 faces each side of the center strand 130. The direction-adjusting rollers 144 send the group of strands 199 to a clamp 145.
[0027] In a process of sending the group of conductor lines 198 from the strand feeder 141 to the clamp 145, a lubricant is applied to at least one of the group of conductor lines 198 and the group of strands 199. In short, in this example, any of the steps from sending the group of conductor lines 198 from the strand feeder 141 to the clamp 145 corresponds to the application step S I . It is particularly preferred that the lubricant is applied to the group of strands 199 because the lubricant is more likely to remain sufficiently on surfaces of the peripheral strands 1 10 and the center strand 130.
[0028] Next, the clamp 145 receives the group of strands 199 from the direction-adjusting rollers 144. The clamp 145 aligns the group of strands 199, arranges the peripheral strands 1 10 around the center strand 130, and forms an aligned collective conducting wire, or an aligned collective conductor 200. The clamp 145 forms the aligned collective conductor 200 so that an inner periphery of the peripheral strand 1 10 faces each side of an outer surface of the center strand 130. In this example, the step in which the clamp 145 forms the aligned collective conductor 200 corresponds to the bundling step S2.
[0029] The clamp 145 applies given pressure to the aligned collective conductor 200 towards the center of the aligned collective conductor 200. Therefore, as shown in a schematic view 160, the center strand 130 and the peripheral strands 1 10, as well as the peripheral strands 1 10 come closer to each other in a section 190 of the aligned collective conductor 200. The clamp 145 sends the aligned collective conductor 200 to a rotating machine 146.
[0030] The rotating machine 146 rotates in a given rotation direction 152. In FIG. 3, the rotation direction 152 contains a direction in which the aligned collective conductor 200 is twisted in a right screw direction. The rotating machine 146 twists the aligned collective conductor 200 about the center strand 130 as a twisting step, and forms a twisted collective conductor 201.
[0031] As shown in a schematic view 161 , the aligned collective conductor 200 is a collective conductor in which the center strand 130 and the peripheral strands 1 10 having a given shape are aligned. Therefore, the rotating machine 146 is able to form a section 191 that keeps a substantially circular shape of the section 190. The rotating machine 146 sends the twisted collective conductor 201 to a clamp 147.
[0032] The clamp 147 receives the twisted collective conductor 201 from the rotating machine 146. The clamp 147 applies given pressure to the twisted collective conductor 201 towards the center of the twisted collective conductor 201. Therefore, the center strand 130 and the peripheral strands 1 10, as well as the peripheral strands 1 10, which are now less closely in contact with each other due to the twisting step, are again brought into close contact with each other. The clamp 147 sends the twisted collective conductor 201 to the speed-adjusting guide roller 148.
[0033] The speed-adjusting guide roller 148 receives the twisted collective conductor 201 from the clamp 147, and removes flexure of the twisted collective conductor 201 caused in the twisting step. The speed-adjusting guide roller 148 sends the twisted collective conductor 201 to second rolling mill rolls 151.
[0034] The second rolling mill rolls 151 receive the twisted collective conductor 201 from the speed-adjusting guide roller 148. As the plastic working step S3, the second rolling mill rolls 151 apply substantially planar pressure to the twisted collective conductor 201 in a vertical direction in the drawing in a case where the twisted collective conductor 201 has a substantially rectangular shape.
[0035] As shown in a schematic view 162, the second rolling mill rolls 151 give lateral wall surfaces 194 to top and bottom ends of a section 192 of the collective conducting wire 202 shown in the drawing. The second rolling mill rolls 151 send the collective conducting wire 202 to a heating furnace 150. [0036] The heating furnace 150 receives the collective conducting wire 202 from the second rolling mill rolls 151 and heats the collective conducting wire 202 as the heating step S4. The heating furnace 150 may send the collective conducting wire 202 to a coil manufacturing step if necessary.
[0037] In the first embodiment described above, the aligned collective conductor
200 is twisted by passing through the direction-adjusting rollers 144, the clamp 145, the rotating machine 146, and the clamp 147, and the twisted collective conductor 201 is thus formed. However, it is also possible to form a collective conductor with right-left reversal twists. The collective conductor with right-left reversal twists is, for example, a twisted collective conductor having a twisted portion twisted so as to be spiral around the center strand 130, and a reverse twisted portion twisted in the reverse direction to the twisting direction of the twisted portion. In the collective conductor with right-left reversal twists, a non-twisted portion, which is in parallel to the axis of the center strand 130, may be formed between the twisted portion and the reverse twisted portion.
[0038] A manufacturing method for the collective conductor with right-left reversal twists is explained. After the bundling step S2 described in the foregoing first embodiment is completed, the clamp 145 allows the aligned collective conductor 200 to pass through the rotating machine 146 and further sends the aligned collective conductor 200 to the clamp 147. Thereafter, the clamp 145 and the clamp 147 clamp the collective conductor 200 all at the same time, and fix the axis of the aligned collective conductor 200. While the clamp 145 and the clamp 147 are clamping the aligned collective conductor 200, the rotating machine 146 rotates in the given rotation direction 152, and twists the aligned collective conductor 200. Then, the collective conductor with right-left reversal twists is formed. The collective conductor with right-left reversal twists has the twisted portion and the reverse twisted portion on both sides across the rotating machine 146.
Considerations regarding an oxide film thickness
[0039] Next, a preferred range of the thickness t of the oxide film formed between the conductor lines of the collective conducting wire is explained by using FIG. 4. FIG. 4 is a graph showing electric resistance relative to oxide film thicknesses. [0040] As shown in FIG. 4, when the thickness of the oxide film is over 130 nm, electric resistance of the oxide film could exceed 0.3 Ω. From past experiments, it is already known that an eddy-current loss of a coil is reduced when the electric resistance between conductor lines exceeds 0.3 Ω in a collective conducting wire. This means that an oxide film thickness required for reducing an eddy-current loss of a coil is at least 130 nm.
[0041] When the thickness of the oxide film is over 300 nm, the oxide film is sometimes unable to be adhered to the conductor lines and thus separated from the conductor lines. A thickness of the oxide film required for ensuring adhesion strength with the conductor lines is 300 nm or smaller.
[0042] Accordingly, it is preferred that the oxide film thickness is 130 nm or more but not exceeding 300 nm, because both an eddy-current loss reduction and ensuring adhesion strength are achievable.
Considerations regarding sulfate concentration in a lubricant
[0043] Next, a preferred range of a sulfate concentration in the lubricant is explained by using FIG. 1 again.
[0044] Formulas are established for a number of moles n E of sulfate contained in the lubricant per unit length of the strand, and a number of moles n c of CuO per unit length of the oxide film formed between the strands. Then, a concentration C E of sulfate in the lubricant is obtained by using that fact that these numbers of moles are equal to each other.
[0045] The number of moles n E [mol] of sulfate is obtained by formula 1 below. n E = CE x Vi u . . . (Formula 1 )
C E [mol / 1] : Concentration of sulfate in the lubricant
Vi u [mm 3 ] : Volume of the lubricant that can exist between the strands per unit length
[0046] Next, the volume V )u of the lubricant that can exist between the strands per unit length is obtained by formula 2 below.
V| U = L x t s x 1 [mm 3 ] . .. (Formula 2)
L [mm] : Length of a space between the strands to which the oxide film is desired to be given (see FIG. 1 ) t s [mm] : Space between the strands
[0047] The space t s between the strands is 0.01 mm. Therefore, formula 2 is able to be deformed into formula 3.
Viu = L x 10 "5 [mol / mm 3 ] = L x 10 "8 [mol I L] . . . (Formula 3)
Further, the number of moles ΠΕ [mol] of sulfate is expressed by formula 4 below from the above-mentioned formula 1 and formula 3.
n E = C E x L x 10 "8 [mol] . .. (Formula 4)
[0048] Next, a formula is established for the number of moles n c of CuO per unit length in the oxide film formed between the strands. The number of moles n c of CuO per unit length in the oxide film formed between the strands is obtained by the following formula 5.
nc = fi x p / Mc . .. (Formula 5)
Vfl : Volume of the oxide film per unit length of the collective conducting wire
p : Density of CuO
M c : Molar mass of CuO
[0049] Next, the volume Vn [mm 3 ] of the oxide film per unit length of the collective conducting wire is expressed by the following formula 6.
Vn = L x t . .. (Formula 6)
t : Oxide film thickness (see FIG. 1 ) [mm]
[0050] A density p [g / mm 3 ] of CuO is 6.31 x 10 "3 , and a molar mass M c [g / mol] of CuO is 79.545. Then, the number of moles n c of the copper oxide CuO is expressed by formula 7 below.
n c = L x t x p / M c n c = L x t x (6.31 x 10 '3 ) / 79.545 n c = L x t x (7.93 x 10 '5 ) .. . (Formula 7)
[0051] Since the number of moles n E and the number of moles nc are equal to each other, the following formula 8 is established from the foregoing formula 3 and the formula 6.
C E x L x l0 "8 = L x t x (7.93 x 10 '5) ) . . . (Formula 8)
If L and so on are erased from formula 7, the following formula 9 is obtained. C E = t x 7.93 x 10 3 . . . (Formula 9)
[0052] As described above, a preferred range of the thickness t of the oxide film is 130 nm or more but not exceeding 300 nm. Upper and lower limit values of the preferred range of the thickness t of the oxide film are assigned to the foregoing formula 7. Then, the concentration C E of sulfate in the lubricant is obtained as 1.0 to 2.4 mol / 1. Accordingly, it is preferred that the concentration CE of sulfate in the lubricant is 1.0 to 2.4 mol / 1 because it is ensured that the thickness t of the oxide film is 130 nm or more but not exceeding 300 nm.
[0053] According to the first embodiment described so far, the insulation film having a given range of thickness is formed on the surfaces of the conductor lines, thereby ensuring that the conductor lines are separated from each other by the insulation film. This means that it is possible to manufacture a collective conducting wire, in which it is further ensured that the conductor lines are insulated from each other.
[0054] There is a manufacturing method for a collective conducting wire, in which a plurality of bear copper wires are press-formed, a fluid for forming an oxide film is then allowed to enter between the copper wires, and the oxide film is formed between the copper wires by heating and so on. In such a manufacturing method, there are cases where the fluid for forming the oxide film is unable to enter between the copper wires and the oxide film is thus not formed. Meanwhile, according to the foregoing first embodiment, it is ensured that the lubricant, to which sulfate is added, is applied to the conductor lines as a fluid for forming the oxide film and it is thus possible to manufacture the collective conducting wire in which it is further ensured that the conductor lines are insulated from each other.
[0055] In the first embodiment, the heating step S4 is carried out, but the heating step S4 may be omitted as necessary. For example, the heating step S4 may be omitted when processing heat is generated in the strands in the plastic working step S3, and the oxide film containing CuO is formed sufficiently.
[0056] Next, the collective conducting wire is manufactured by using the manufacturing method according to the first embodiment, and tests for measuring an eddy-current loss of the manufactured collective conducting wire are explained by using FIG. 5. FIG. 5 is a graph showing a decreasing rate of eddy-current loss. For comparison with an example, an eddy-current loss in a comparative example was also measured. The comparative example is a collective conducting wire manufactured by the same manufacturing method to the method according to the first embodiment, except that the lubricant was not used.
[0057] As shown in FIG. 5, in the example, a decreasing rate of eddy-current loss is over 80%. 80% is a calculated value of a decreasing rate of eddy-current loss in a case where the conductor lines are separated from each other by the insulation film having a given thickness, and thus insulated from each other without fail. In short, 80% is an ideal value of the decreasing rate of eddy-current loss. In the example, it is considered that the conductor lines included in the collective conducting wire are insulated from each other without fail by the insulation film having a given thickness.
[0058] Meanwhile, in the comparative example, a decreasing rate of eddy-current loss was about 40%. The decreasing rate of eddy-current loss in the comparative example is significantly lower than 80% that is the ideal decreasing rate. In other words, in the comparative example, it is considered that the conductor lines included in the collective conducting wire are not insulated from each other by an insulation film. Thus, the conductor lines are in direct contact with each other, and thus conductive with each other in each area.
Application examples
[0059] It is possible to form a coil by using the collective conducting wire obtained by the manufacturing method according to the first embodiment. Therefore, this embodiment is suitable for the following applications.
[0060] A motor is able to have a coil made of the collective conducting wire manufacturing by the foregoing manufacturing method. Since the coil has a small eddy-current loss, the motor with the small coil is able to achieve performance equal to that of a conventional motor. [0061] An automobile is light-weighted by having such a motor, while maintaining conventional performance. From a weight reduction viewpoint, it is preferred that an automobile has a driving part having such a motor. The motor is especially suitable for a hybrid car, and a plug-in hybrid car.
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