SPOOL AND ELECTRIC LATHE

Abstract

This coil is used in an electric lathe comprising: a rotor rotatable about an axis; and a cylindrical stator facing the rotor radially and centered on the axis. The stator has: a stator core having an annular yoke centered on the axis and several teeth projecting radially inward from the inner circumferential surface of the yoke and aligned at intervals in the circumferential direction; and the coil covering the circumference of the teeth. The coil has several individual coils covering the teeth from the outer circumferential side and stacked radially with respect to the axis. A section of each individual coil, containing end sections on both sides in the circumferential direction with respect to the axis, is a high-resistance section in which the electrical resistance is higher than the electrical resistance of the remaining section.

Description

Technical field

[0001] The present disclosure relates to a coil and an electric lathe.

[0002] Priority is claimed by the Japanese patent application No. 2023-116020 filed on July 14, 2023, the contents of which are incorporated herein by reference. State of the art

[0003] An electric motor, a type of electric lathe, contains a rotor that rotates around an axis and a tubular stator that covers a rotor core on one side. The rotor contains a core and a permanent magnet. The stator contains a core and several coils attached to the core. When current is applied to the coil, an electromagnetic force is generated between the permanent magnet and the coil, causing the rotor to rotate around the axis. When constructing the coil, it is common practice to wind a copper wire or similar material around teeth of the stator core to form the coil in a ring shape. However, when constructing the coil, it is necessary to insulate the windings from one another to reduce copper loss.Therefore, in the technique according to PTL 1, a laser is irradiated onto copper powder, which is a material of a conductor, and ceramic powder, which is a material of an insulating layer, and an insulating film and a coil are formed by three-dimensional additive manufacturing. List of citations from patent literature

[0004] [PTL 1] Japanese unexamined patent application publication no. 2016-039662 Summary of the invention: Technical problem

[0005] However, if the surface area of ​​the copper is increased to increase the volume factor, a large eddy current will be generated in the copper when the electric lathe is driven at high speed and high frequency, leading to a problem of increased copper loss.

[0006] The present disclosure provides a coil and an electric lathe in which copper loss is further reduced. Solution to the problem

[0007] A coil according to the present disclosure is a coil used in an electric lathe comprising a rotor rotatable about an axis and a tubular stator facing the rotor in a radial direction and centered on the axis, wherein the stator has a stator core comprising an annular yoke centered on the axis and several teeth projecting radially inward from an inner circumferential surface of the yoke and arranged at intervals in a circumferential direction, and the coil covering a circumference of the teeth, wherein the coil comprises several individual coils covering the teeth from an outer circumferential side and laminated in the radial direction with respect to the axis, wherein in each individual coil a section comprising both end sections in the circumferential direction with respect to the axis is a high-resistance section.which has a higher electrical resistance than the electrical resistance of the remaining section.

[0008] An electric lathe according to the present disclosure comprises the rotor, the stator core and the coil provided in the stator core. Advantageous effects of the invention

[0009] According to the present disclosure, it is possible to provide a coil and an electric lathe in which copper loss is further reduced. Brief description of the drawings Fig. Figure 1 is a cross-sectional view showing a configuration of an electric lathe according to a first embodiment of the present disclosure. Fig. Figure 2 is an enlarged cross-sectional view of a coil according to the first embodiment of the present disclosure. Fig. Figure 3 is a cross-sectional view of the coil according to the first embodiment of the present disclosure when viewed in a radial direction. Fig. Figure 4 is an enlarged view of main parts showing a modification example of the coil according to the first embodiment of the present disclosure. Fig. Figure 5 is an enlarged cross-sectional view of a coil according to a second embodiment of the present disclosure. Fig. Figure 6 is an enlarged cross-sectional view showing a modification example of the coil according to the second embodiment of the present disclosure. Description of embodiments <Erste Ausführungsform>

[0010] Below, a coil 30 and an electric motor 1 (electric lathe) are described according to the embodiment of the present disclosure with reference to Fig. 1 to 3 described. (Configuration of electric motor 1)

[0011] As in Fig. As shown in Figure 1, the electric motor 1 comprises a rotor 10 and a stator 20. The rotor 10 has a columnar shape extending along an axis X and is mounted to rotate about the axis X. Although not shown in detail, the rotor 10 contains a permanent magnet. The stator 20 has a tubular shape that covers the rotor 10 from one outer circumferential side. That is, the stator 20 has a tubular shape centered on the axis X. The stator 20 contains a stator core 21 and the coil 30.

[0012] The stator core 21 contains a yoke 22 and several teeth 23. The yoke 22 has an annular shape centered on the X axis. The several teeth 23 are provided on an inner circumferential surface of the yoke 22. The teeth 23 project radially inward from the inner circumferential surface of the yoke 22 with respect to the X axis. Several teeth 23 are provided at intervals in a circumferential direction with respect to the X axis.

[0013] The tooth 23 comprises a tooth body 41 and a flange section 42. The tooth body 41 extends radially. One dimension of the tooth body 41 in the circumferential direction is constant over its entire radial extent. The coil 30, which will be described later, is arranged around the tooth body 41. The flange section 42 is located at a tip section (i.e., an end section on an inner radial surface) of the tooth body 41. The flange section 42 projects from a tip end of the tooth body 41 to both sides in the circumferential direction. The flange section 42 is designed to prevent the coil 30, which will be described later, from falling off the tooth body 41. (Configuration of coil 30)

[0014] The coil 30 is designed to be wound around the tooth body 41. That is, the coil 30 has a ring-shaped form with its radial direction relative to the X axis as a central axis. As in Fig. As shown in Figure 2, the coil 30 contains several individual coils 31 laminated in the radial direction.

[0015] The individual coil 31 has a ring-shaped form with a central axis in the radial direction with respect to the axis X. Viewed in one direction of the axis X, the individual coil 31 has a rectangular cross-sectional shape. The multiple individual coils 31 cover a circumference of the tooth body 41 to form a spiral shape. That is, the individual coils 31 are electrically connected to each other to form a coil 30. Furthermore, in the example of Fig. 2. The dimension of the individual coil 31 gradually decreases in the circumferential direction from one radial outer side to the radial inner side. This serves to avoid physical interference with another coil 30 that is adjacent in the circumferential direction.

[0016] A section containing both end sections of the single coil 31 in the circumferential direction is a high-resistance section 51, which has a higher electrical resistance than the remaining section (that is, a central section in the circumferential direction excluding both end sections). The resistance changes discontinuously at a boundary between the high-resistance section 51 and the remaining section. The high-resistance section 51 is formed, for example, by reducing the power of a laser compared to that of the remaining section in a case where the coil 30 is manufactured by a three-dimensional additive manufacturing device. Therefore, the high-resistance section 51 has a lower material fill rate than the remaining section. In other words, the material porosity is high in the high-resistance section 51. As a result, current flow is less likely.This means that the electrical resistance is high. Copper is a suitable material for forming coil 30. In a case of three-dimensional additive manufacturing, copper powder can be melted and solidified by irradiating the powder with a laser to obtain a predetermined shape for coil 30.

[0017] Furthermore, as indicated by a dashed line in Fig. Figure 3 shows that, in a case where the coil 30 is viewed from the radial inside, the high-resistance section 51 is provided only in a section that overlaps the tooth 23 in the single coil 31. In other words, the high-resistance section 51 is not provided in a section of the single coil 31 that does not overlap the tooth 23, i.e., at a coil end 60. A distribution of properties of the single coil 31 can also be achieved by the three-dimensional additive manufacturing described above. (Effects and Effects)

[0018] Next, the operation of the electric motor 1 will be described. When the electric motor 1 is driven, current is first supplied to each coil 30. Then, an electromagnetic force is generated between the coil 30 and the permanent magnet of the rotor 10. A rotational force is exerted on the rotor 10 by this electromagnetic force. As a result, the rotor 10 rotates about the axis X. The rotational force of the rotor 10 is taken from one end of the shaft and used for various applications.

[0019] Here, when forming the coil 30, it is common practice to wind a copper wire or similar material around the teeth 23 of the stator core 21 to form the coil 30 into a ring shape. Furthermore, when forming the coil 30, it is necessary to insulate the windings of the coil 30 to reduce copper loss. Therefore, in the prior art, a laser is applied to the copper powder, which is the conductor material, and the ceramic powder, which is the insulating layer material, and the insulating film and the coil 30 are formed by three-dimensional additive manufacturing.

[0020] However, if the copper surface area is increased to improve the volumetric efficiency, a large eddy current is generated in the copper when the electric lathe is driven at high speed and frequency, leading to increased copper loss. Therefore, in the present embodiment, each of the configurations described above is used.

[0021] Here, large eddy currents tend to flow in both end sections of the single coil 31 in the circumferential direction, increasing with the rotation of the rotor 10. According to the configuration described above, since the high-resistance section 51 is formed in both end sections of the single coil 31 in the circumferential direction, eddy currents are less likely to flow in the high-resistance section 51. In particular, since the material fill rate is relatively low, the resistance with respect to the current is high in the high-resistance section 51. Therefore, the eddy currents tend to be blocked in the high-resistance section 51. As a result, the eddy currents in the entire coil 30 are reduced, and the copper loss of the coil 30 can be reduced. Therefore, it is possible to provide an electric motor 1 with a higher efficiency.

[0022] Here, in the section of the single coil 31 that does not overlap the tooth 23, i.e., the coil end 60, since the magnetic leakage flux of the coil 30 is not coupled, the DC copper loss can increase if the high-resistance section 51 is provided in this section. However, according to the configuration described above, since the high-resistance section 51 is provided in a section different from the coil end 60, the increase in DC copper loss can be minimized, while the AC copper loss can be suppressed to a maximum extent.

[0023] Furthermore, according to the configuration described above, the high-resistance section 51 can be easily and cost-effectively configured simply by changing the material fill rate. In particular, in a case where three-dimensional additive manufacturing is used, the high-resistance section 51 can be easily formed by simply reducing the laser power to control the material fill rate. As a result, it is possible to significantly reduce the manufacturing costs of the coil 30.

[0024] The first embodiment of the present disclosure has been described above. Various changes and modifications can be made to the above configuration within a scope of protection that does not deviate from the core of the present disclosure.

[0025] For example, in the first embodiment, the example described is one in which the resistance changes discontinuously at the boundary between the high-resistance section 51 and the remaining section. On the other hand, it is, as a modification example in Fig. As shown in Figure 4, it is also possible to use a configuration in which the electrical resistance of the high-resistance section 51 and the remaining section changes continuously. In other words, the electrical resistance gradually increases from the central section in the circumferential direction towards both end sections. According to this configuration, a section with locally changing resistance is not formed. Therefore, it is possible to suppress the occurrence of a section with an increase in local eddy currents. As a result, it is possible to further reduce the copper loss of the entire coil 30.

[0026] Furthermore, the electrical resistance of the region in the central section can be configured circumferentially such that it increases from the single coil 31 on the radial outer side to the single coil 31 on the radial inner side. Additionally, the electrical resistance of the high-resistance sections 51 on both sides can be configured circumferentially such that it gradually increases from the single coil 31 on the radial outer side to the single coil 31 on the radial inner side. In particular, an example is considered in which the volume occupied by the high-resistance section 51 increases from the single coil 31 on the radial outer side to the single coil 31 on the radial inner side.

[0027] According to the configuration described above, since the electrical resistance is high in the area on the inside of the radial (that is, the area near the rotor) where eddy currents are likely to occur, it is possible to effectively suppress the occurrence of eddy currents. <Zweite Ausführungsform>

[0028] Next, a second embodiment of the present disclosure will be described with reference to Fig. 5 described. The same configurations as those of the first embodiment are designated with the same reference numerals and a detailed description thereof is omitted.

[0029] As in Fig. As shown in Figure 5, in the present embodiment the high-resistance section 51 is provided only in the single coil 31 on the side near the rotor 10. In particular, in the example of Fig. 5 The high-resistance section 51 is formed in only two individual coils 31, counted from the radial inner side on which the rotor 10 is located. The configuration and properties of the high-resistance section 51 itself are the same as those described in the first embodiment. (Effects and Effects)

[0030] Since the entire coil 30 is excited by the rotor 10, large eddy currents tend to flow in the single coil 31 on the side closest to the rotor 10. According to the configuration described above, because the high-resistance section 51 is only located in the single coil 31 on the side closest to the rotor 10, eddy currents can be suppressed more efficiently and effectively. Therefore, it is possible to further reduce the copper loss of the entire coil 30. Conversely, if the high-resistance section 51 is located in a section where eddy currents are unlikely to occur, the DC copper loss may increase, and the performance of the entire coil 30 may deteriorate. According to the configuration described above, it is possible to minimize the AC copper loss while avoiding this possibility. Therefore, the efficiency of the electric motor 1 can be further improved.

[0031] The second embodiment of the present disclosure has been described above. Various changes and modifications can be made to the above configuration within a scope of protection that does not deviate from the core of the present disclosure.

[0032] For example, in the second embodiment, the example described is in which the high-resistance section 51 is formed only in two individual coils 31, counted from the side of rotor 10. However, depending on the size, design, and specifications of the electric motor 1, as shown in Fig.As shown in Figure 6, the high-resistance section 51 is formed only in the first individual coil 31, counting from the side of rotor 10. According to this configuration, eddy currents can be suppressed even more efficiently and effectively compared to a case where the high-resistance section 51 is provided in the remaining individual coils 31. Therefore, it is possible to further reduce the AC copper loss of the entire coil 30. (Other embodiments)

[0033] Although the embodiment of the present disclosure has been described in detail above with reference to the drawings, the specific configuration of the present disclosure is not limited to the embodiment, and the present disclosure contains design changes or the like within a scope that does not deviate from the core of the present disclosure.

[0034] For example, the number of coils (30) or the number of teeth (23) described in the embodiment above are examples and can be appropriately increased or decreased depending on the design or specification. Even in this case, the same effects and properties as those described above can be obtained.

[0035] Furthermore, the number of individual coils, 31, is also an example and can be appropriately changed depending on the design or specification. Even in this case, the same effects and properties as described above can be achieved.

[0036] As described in the embodiment above, it is desirable to use three-dimensional additive manufacturing to obtain coil 30. However, as long as formation is physically possible, other methods, such as casting, can also be used.

[0037] Furthermore, the embodiment described above includes an example where the coil 30 is used in the electric motor 1. However, the application of the coil 30 is not limited to the electric motor 1, and the coil 30 can also be used in a generator, which is another type of electric rotary engine. In this case, applying a rotational force to the rotor 10 generates an induced current in the coil 30, and alternating current power can be obtained.

[0038] Furthermore, the configuration of the electric motor 1 is not limited by the embodiment described above. That is, while each of the embodiments described above includes an example where the rotor 10 is arranged on the inner circumferential side of the stator 20, a configuration where the rotor 10 is arranged on the outer circumferential side of the stator 20 can also be used. In this case, where the high-resistance section 51 is provided only in the single coil 31 on the side of the rotor 10 described in the second embodiment, the high-resistance section 51 is formed only in the single coil 31 on the radial outer side. With this configuration, the same effects and properties as described above can also be obtained. <Ergänzende Anmerkungen>

[0039] The coil 30 and the electric lathe according to each embodiment are understood, for example, as follows.

[0040] (1) A coil 30 according to a first aspect is a coil 30 used in an electric lathe comprising a rotor 10 rotatable about an axis X and a tubular stator 20 radially oriented towards the rotor 10 and centered on the axis X, wherein the stator 20 has a stator core 21 having an annular yoke 22 centered on the axis X and several teeth 23 projecting radially inwards from an inner circumferential surface of the yoke 22 and spaced at intervals in a circumferential direction, and the coil 30 covering a circumference of the teeth 23, wherein the coil 30 comprises several individual coils 31 covering the teeth 23 from an outer circumferential side and laminated radially with respect to the axis X, each individual coil 31 having a section comprising both end sections in the circumferential direction with respect to the X-axis, it contains a high-resistance section 51,which has a higher electrical resistance than the electrical resistance of the remaining section.

[0041] Here, large eddy currents tend to flow in both end sections of the single coil 31 in the circumferential direction, with the rotation of the rotor 10. According to the configuration described above, since the high-resistance section 51 is formed in both end sections of the single coil 31 in the circumferential direction, the eddy currents are impeded by the high resistance. As a result, it is possible to reduce the copper loss of the entire coil 30.

[0042] (2) A coil 30 according to a second aspect is the coil 30 according to (1), wherein in each individual coil 31 the electrical resistance gradually increases from a central section in the circumferential direction to both end sections.

[0043] According to the configuration described above, since the electrical resistance gradually increases towards both end sections in the circumferential direction, a section with locally changing resistance is not formed. Therefore, it is possible to suppress the occurrence of a section with increasing local eddy currents. Consequently, it is possible to further reduce the copper loss of the entire coil 30.

[0044] (3) A coil 30 according to a third aspect is the coil 30 according to (1) or (2), wherein the high-resistance section 51 is provided only in the single coil 31 on one side near the rotor 10.

[0045] Since the entire coil 30 is excited by the rotor 10, large eddy currents tend to flow in the single coil 31 on the side closest to the rotor 10. According to the configuration described above, because the high-resistance section 51 is only located in the single coil 31 on the side closest to the rotor 10, eddy currents can be suppressed more efficiently and effectively. Therefore, it is possible to further reduce the copper loss of the entire coil 30.

[0046] (4) A coil 30 according to a fourth aspect is the coil 30 according to one of (1) to (3), wherein the high-resistance section 51 is provided only in the single coil 31 in a first stage, counted from the rotor 10.

[0047] According to the configuration described above, since the high-resistance section 51 is only provided in the single coil 31 in the first stage, counting from the rotor 10, eddy currents can be suppressed even more efficiently and effectively compared to a case where the high-resistance section 51 is provided in the remaining single coil 31. Therefore, it is possible to further reduce the copper loss of the entire coil 30.

[0048] (5) A coil 30 according to a fifth aspect is the coil 30 according to one of (1) to (4), wherein the high-resistance section 51 is provided only in a section which overlaps the tooth 23 in the single coil 31 when viewed in the radial direction.

[0049] Here, in the section of the single coil 31 that does not overlap the tooth 23, i.e., the coil end 60, since the magnetic leakage flux of the coil 30 is not coupled, the DC copper loss can increase if the high-resistance section 51 is provided in this section. However, according to the configuration described above, since the high-resistance section 51 is provided in a section different from the coil end 60, the increase in DC copper loss can be minimized, while the AC copper loss can be suppressed to a maximum extent.

[0050] (6) A coil 30 according to a sixth aspect is the coil 30 according to one of (1) to (5), wherein the high-resistance section 51 is configured to have a higher electrical resistance by having a lower fill rate of material than a fill rate of material of the remaining section.

[0051] According to the configuration described above, the high-resistance section 51 can be easily and cost-effectively configured simply by changing the material fill rate. In particular, in a case where three-dimensional additive manufacturing is used, the high-resistance section 51 can be formed by simply reducing the laser power. As a result, it is possible to significantly reduce the manufacturing costs of the coil 30.

[0052] (7) A coil 30 according to a seventh aspect is the coil 30 according to one of (1) to (6), wherein an electrical resistance of a region in a central section increases in the circumferential direction from the single coil 31 on a radial outside to the single coil 31 on a radial inside.

[0053] According to the configuration described above, since the electrical resistance is high in the area on the inside of the radial (that is, the area near the rotor) where eddy currents are likely to occur, it is possible to effectively suppress the occurrence of eddy currents.

[0054] (8) A coil 30 according to an eighth aspect is the coil 30 according to one of (1) to (7), wherein electrical resistances of the high-resistance sections 51 on both sides in the circumferential direction from the single coil 31 on a radial outside to the single coil 31 on a radial inside.

[0055] According to the configuration described above, since the electrical resistance is high in the area on the inside of the radial (that is, the area near the rotor) where eddy currents are likely to occur, it is possible to effectively suppress the occurrence of eddy currents.

[0056] (9) A coil 30 according to a ninth aspect is the coil 30 according to one of (1) to (8), wherein a volume occupied by the high-resistance sections 51 on both sides in the circumferential direction increases from the single coil 31 on a radial outside to the single coil 31 on a radial inside.

[0057] According to the configuration described above, since the electrical resistance is high in the area on the inside of the radial (that is, the area near the rotor) where eddy currents are likely to occur, it is possible to effectively suppress the occurrence of eddy currents.

[0058] (10) An electric lathe according to a tenth aspect comprises the rotor 10, the stator core 21 and the coil 30 according to any of (1) to (9) which is provided in the stator core 21.

[0059] According to the configuration described above, it is possible to provide an electric lathe in which copper loss is reduced and efficiency is significantly improved. Industrial applicability

[0060] According to the present disclosure, it is possible to provide a coil and an electric lathe in which copper loss is further reduced. Reference symbol list 1 electric motor 10 Rotor 20 Stator 21 Stator core 22 yoke 23 teeth 30 coil 31 single coil 41 Tooth bodies 42 Flange section 51 High-resistance section 60 Coil end X-axis QUOTES INCLUDED IN THE DESCRIPTION

[0000] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature

[0000] JP 2023-116020

[0002] JP 2016-039662

[0004]

Claims

[1] Coil used in an electric lathe, which contains: a rotor that can rotate around an axis, and a tubular stator facing the rotor in a radial direction and centered on the axis, the stator having a stator core comprising an annular yoke centered on the axis and several teeth projecting radially inwards from an inner circumferential surface of the yoke and arranged at intervals in a circumferential direction, and the coil covering a circumference of the teeth, wherein the coil comprises several individual coils that cover the teeth from an outer circumferential side and are laminated in the radial direction with respect to the axis, wherein in each individual coil a section which contains both end sections in the circumferential direction with respect to the axis is a high-resistance section which has a higher electrical resistance than an electrical resistance of any remaining section. [2] Coil according to claim 1, wherein in each individual coil the electrical resistance gradually increases from a central section in the circumferential direction to both end sections. [3] Coil according to claim 1 or 2, wherein the high-resistance section is provided only in the single coil on one side near the rotor. [4] Coil according to claim 1, wherein the high resistance section is provided only in the single coil in a first stage, counted from the rotor. [5] Coil according to claim 1, wherein the high-resistance section is provided only in a section which overlaps the tooth in the single coil when viewed in the radial direction. [6] Coil according to claim 1, wherein the high-resistance section is configured to have a higher electrical resistance by having a lower fill rate of material than a fill rate of material of the remaining section. [7] Coil according to claim 1, wherein an electrical resistance of a region in a central section increases in the circumferential direction from the single coil on a radial outer side to the single coil on a radial inner side. [8] Coil according to claim 1, wherein electrical resistances of the high-resistance sections on both sides gradually increase in the circumferential direction from the single coil on a radial outer side to the single coil on a radial inner side. [9] Coil according to claim 1, wherein a volume occupied by the high-resistance sections on both sides in the circumferential direction increases from the single coil on a radial outer side to the single coil on a radial inner side. [10] Electric lathe comprising: the rotor; the stator core; and the coil according to claim 1, which is provided in the stator core.

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