Motor

Abstract

The purpose of the invention is to reduce the temperature rise speed of a motor. The motor comprises a stator and a rotor. The rotor has a plurality of permanent magnets and rotates with respect to the stator. The stator has a stator core (3), a coil (4), and an insulating member (6). The coil (4) is formed by winding a conductive wire (41) a plurality of times with respect to the stator core (3). In the coil (4), adjacent portions of the conductive wire (41) are separated from each other. The insulating member (6) has electrical insulation properties. The insulating member (6) covers the coil (4) and is disposed so as to fill between adjacent portions of the conductive wire (41). The insulating member (6) includes a phase change material (71).

Description

motor

[0001] The present disclosure relates generally to motors, and more particularly to motors including a stator having coils.

[0002] Patent Document 1 discloses an actuator assembly having an armature and a coil winding, in which a PCM material is disposed around the coil winding, partially encapsulated around and inside the coil winding, and partially disposed on the coil winding.

[0003] Special Publication No. 2005-523676

[0004] However, in an actuator assembly (motor) such as that disclosed in Patent Document 1, a temperature rise in the motor when operating under high load conditions becomes a problem.

[0005] The present disclosure has been made in view of the above-mentioned circumstances, and has an object to provide a motor that can reduce the rate of temperature rise.

[0006] A motor according to one aspect of the present disclosure includes a stator and a rotor. The rotor has a plurality of permanent magnets and rotates relative to the stator. The stator has a stator core, a coil, and an insulating member. The coil is formed by winding a conductor multiple times around the stator core. In the coil, adjacent portions of the conductor are spaced apart. The insulating member has electrical insulation properties. The insulating member is arranged to cover the coil and fill the spaces between adjacent portions of the conductor. The insulating member includes a phase change material.

[0007] According to the present disclosure, the rate of temperature rise can be reduced.

[0008] FIG. 1 is a schematic diagram showing the configuration of a motor according to an embodiment. FIG. 2 is a schematic cross-sectional view showing a main part of a motor according to an embodiment. FIG. 3 is a schematic cross-sectional view showing a coil and its vicinity provided in the motor according to an embodiment. FIG. 4 is a schematic diagram for explaining a phase change material provided in the motor according to an embodiment. FIG. 5 is an explanatory diagram for explaining the temperature rise rate of the motor according to an embodiment. FIG. 6 is a graph showing the results of a thermal analysis of the motor according to an embodiment. FIG. 7 is a graph showing the results of a thermal analysis of the motor according to Modification 1. FIG. 8 is a schematic cross-sectional view showing a main part of a motor according to Modification 2. FIG. 9 is a schematic cross-sectional view showing a main part of a motor according to Modification 3. FIG. 10 is a schematic cross-sectional view showing a main part of a motor according to Modification 4.

[0009] Preferred embodiments of the present disclosure will be described in detail below with reference to the drawings. Common elements in the embodiments described below are designated by the same reference numerals, and redundant descriptions of the common elements may be omitted. The following embodiments and modifications are merely a portion of various embodiments of the present disclosure. Various modifications of the following embodiments and modifications may be made depending on the design, etc., as long as the object of the present disclosure can be achieved. The configurations of the embodiments and modifications may also be combined as appropriate.

[0010] The drawings described in this disclosure are schematic diagrams, and the ratios of the sizes and thicknesses of the components in the drawings do not necessarily reflect the actual dimensional ratios. Note that the arrows indicating the directions in the drawings are merely examples and are not intended to define the directions in which the motor 1 should be used. Furthermore, the arrows indicating the directions in the drawings are merely shown for the purpose of explanation and do not have any substance.

[0011] (1) Overview First, an overview of a motor 1 according to an embodiment will be described with reference to FIGS. 1 and 2. FIG.

[0012] 1 is a schematic diagram showing the configuration of a motor 1 according to this embodiment. As shown in FIG. 1, the motor 1 according to this embodiment includes a stator 2 and a rotor 5.

[0013] The rotor 5 has a plurality of permanent magnets 52 (eight in the example of FIG. 1 ) and rotates relative to the stator 2 .

[0014] The stator 2 has a stator core 3, a plurality of coils 4 (nine in the example of FIG. 1 ), and a plurality of insulating members 6 (nine in the example of FIG. 1 ). Here, the plurality of coils 4 and the plurality of insulating members 6 correspond one-to-one.

[0015] 2 is a schematic cross-sectional view showing a main portion of the motor 1 according to this embodiment. As shown in FIG. 2, the coil 4 is formed by winding a conductor 41 multiple times around the stator core 3. In the coil 4, adjacent portions of the conductor 41 are spaced apart. In the following description, "wound multiple times" may be simply referred to as "wound."

[0016] The insulating member 6 has electrical insulation properties. The insulating member 6 is disposed so as to cover the coil 4 and fill the spaces between adjacent portions of the conductive wire 41. The insulating member 6 includes a phase change material (PCM) 71. The phase change material 71 melts at a specific temperature and absorbs thermal energy.

[0017] The motor 1 of this embodiment is, for example, a servo motor. During high-load operation, such as during servo lock, the output of the motor 1 is, for example, approximately 350% of the rated output. Therefore, a challenge for the motor is how to suppress temperature increases during high-load operation.

[0018] For example, in the actuator assembly of Patent Document 1, when the coil winding is formed, one portion of the conductor wire of the coil winding may come into contact with another portion. According to the motor 1 of this embodiment, the conductor wire 41 of the coil 4 is wound around the stator core 3 so that adjacent portions are spaced apart, and the insulating member 6 is arranged to fill the gaps between adjacent portions of the conductor wire 41. The insulating member 6 also includes a phase change material 71. As a result, the phase change material 71 is evenly arranged between adjacent portions of the conductor wire 41, making it possible to more effectively utilize the latent heat effect of the phase change material 71 and reduce the rate at which the temperature of the motor 1 rises.

[0019] (2) Details The detailed configuration of the motor 1 according to this embodiment will be described below with reference to FIGS.

[0020] (2.1) Motor Configuration The motor 1 is, for example, an inner rotor type servo motor. The motor 1 transmits rotational force to a load, such as an industrial machine, a conveying machine, a machine tool, or a robot, to drive the load. Note that the motor 1 is supplied with power from, for example, a control device.

[0021] 1, the motor 1 includes a stator 2, a rotor 5, and a housing 10. The housing 10 accommodates the stator 2 and the rotor 5.

[0022] (2.2) Rotor Configuration The rotor 5 has a rotor core 51 , a plurality of (eight in the example of FIG. 1 ) permanent magnets 52 , and a motor shaft 53 .

[0023] The rotor core 51 is disposed inside the stator 2. The rotor core 51 has a cylindrical shape centered on the motor shaft 53. The rotor core 51 is made of, for example, iron. However, the rotor core 51 may also be made of silicon steel, permalloy, ferrite, or the like. The rotor core 51 holds a plurality of permanent magnets 52.

[0024] The plurality of permanent magnets 52 are arranged on the outer periphery of the rotor core 51. The plurality of permanent magnets 52 are arranged so that north poles and south poles are alternately arranged in the circumferential direction of the rotor core 51. The plurality of permanent magnets 52 are, for example, permanent magnets such as neodymium magnets.

[0025] The motor shaft 53 is fixed to the inner periphery of the rotor core 51. The motor shaft 53 has a cylindrical shape.

[0026] The rotor core 51 and the motor shaft 53 rotate integrally around the rotation axis Ax1 due to the interaction between the magnetic fields generated by the multiple permanent magnets 52 and the magnetic fields generated by current flowing through the multiple coils 4 of the stator 2.

[0027] (2.3) Configuration of the Stator The overall shape of the stator 2 is a cylinder centered on the motor shaft 53. The stator 2 has a stator core 3, a plurality of coils 4, and a plurality of insulating members 6.

[0028] The stator core 3 is made of, for example, silicon steel and has an outer circumferential portion 32 and a plurality of teeth 31 (nine teeth in the example of FIG. 1 ).

[0029] The outer peripheral portion 32 has a cylindrical shape with the motor shaft 53 at its center.

[0030] The teeth 31 are arranged at equal intervals along the circumferential direction of the outer circumferential portion 32. The teeth 31 protrude from the inner circumferential surface of the outer circumferential portion 32 toward the motor shaft 53 along the radial direction of the motor shaft 53. The teeth 31 are winding axes of the corresponding coils 4. In other words, the winding axis direction D1 of the coils 4 (see FIG. 2) is aligned with the radial direction of the motor shaft 53.

[0031] The coils 4 are arranged at equal intervals along the circumferential direction of the motor shaft 53. The coils 4 correspond one-to-one to the teeth 31.

[0032] FIG. 3 is a schematic cross-sectional view showing the coil 4 and its vicinity provided in the motor 1 according to this embodiment. As shown in FIG. 3, the coil 4 according to this embodiment has a conductor 41 and an insulating coating 42 that covers the conductor 41. The insulating coating 42 has electrical insulation properties. The thickness of the insulating coating 42 is, for example, approximately 0.0125 mm to 0.015 mm. The insulating member 6 is disposed so as to cover the periphery of the insulating coating 42. Note that it is not essential that the coil 4 has the insulating coating 42.

[0033] The conductor 41 is, for example, a copper wire. In this embodiment, the conductor 41 is a round wire. This allows the insulating member 6 to occupy a larger proportion of the space SP1 (see FIG. 2 ). Here, the space SP1 is a space around the tooth 31, centered on the tooth 31, for winding the conductor 41 around the tooth 31. The diameter (width) of the conductor 41 is, for example, approximately 0.25 mm or more and 0.5 mm or less. In the motor 1 of this embodiment, increasing the proportion of the insulating member 6 containing the phase change material 71 increases the latent heat effect of the phase change material 71, thereby further reducing the rate at which the temperature of the motor 1 rises.

[0034] The conductor wire 41 is wound multiple times around the corresponding tooth 31 of the stator core 3. More specifically, the conductor wire 41 is wound multiple times along the winding axis direction D1 of the coil 4. The conductor wire 41 is wound in multiple layers so as to spread outward as viewed from the winding axis direction D1 of the coil 4. In other words, the conductor wire 41 is wound around the tooth 31 so as to be layered in a layer direction D2 that is perpendicular to the winding axis direction D1 as viewed from the winding axis direction D1.

[0035] In addition, "orthogonal (perpendicular)" as used herein does not only refer to a state in which the angle between two elements is strictly 90 degrees, but also includes a state in which two elements intersect within a certain range of difference. In other words, the angle between two elements that are perpendicular to each other falls within a certain range of difference from 90 degrees (for example, 5 degrees or less). In other words, "orthogonal" as used herein includes cases in which the angle between two elements is 85 degrees or more and 95 degrees or less.

[0036] 2 is a schematic cross-sectional view of the teeth 31 and the coils 4 cut along an imaginary plane. In this embodiment, the normal direction of the imaginary plane is along the axial direction of the motor shaft 53. Furthermore, in this embodiment, the imaginary plane cuts through the center of the teeth 31 in the axial direction of the motor shaft 53. In addition, the insulating coating 42 that covers the conductor wires 41 is not shown in FIG.

[0037] As shown in Fig. 2, adjacent portions of the conductor 41 are spaced apart. In the present disclosure, "adjacent portions of the conductor 41" includes adjacent portions of the conductor 41 in the winding axis direction D1 and adjacent portions of the conductor 41 in the layer direction D2. For example, in this embodiment, adjacent portions of the conductor 41 in the winding axis direction D1 are spaced apart by a first distance D3 or more. Furthermore, adjacent portions of the conductor 41 in the layer direction D2 are spaced apart by a second distance D4 or more. In this embodiment, the first distance D3 and the second distance D4 are the same length, but the first distance D3 and the second distance D4 may be different lengths.

[0038] In this embodiment, the conductor 41 is wound in multiple layers around the teeth 31 of the stator core 3 so that multiple cross sections of the conductor 41 included in one cut surface of the coil 4 are arranged in a staggered pattern. This increases the occupancy rate (or space factor) of the conductor 41 in the space SP1. According to the motor 1 of this embodiment, increasing the space factor of the conductor 41 reduces loss in the coil 4 and increases the heat capacity of the coil 4, thereby further slowing the rate at which the temperature of the motor 1 rises.

[0039] The insulating members 6 correspond one-to-one to the coils 4. The insulating members 6 have electrical insulation properties. In this embodiment, the insulating members 6 are adhesives such as epoxy resin adhesives or silicone adhesives. The insulating members 6 cover the coils 4 and are arranged so as to fill the gaps between adjacent portions of the conductor wires 41. Note that "filling the gaps between adjacent portions of the conductor wires 41" may mean that an insulating coating 42 is interposed between the conductor wires 41 and the insulating members 6.

[0040] The insulating member 6 includes a phase change material 71. The phase change material 71 includes paraffin such as Vaseline, wax, or grease (lubricant). The phase change material 71 melts at a specific temperature and absorbs thermal energy around the phase change material 71.

[0041] 4 is a schematic diagram illustrating the phase change material 71 included in the motor 1 according to this embodiment. As shown in FIG. 4 , in this embodiment, the phase change material 71 is encapsulated in a capsule 72. In other words, the insulating member 6 includes a plurality of phase change material capsules 7. Note that FIG. 4 is a perspective view in which a portion of the capsule 72 is broken away, and although the phase change material 71 appears exposed outside the capsule 72 in FIG. 4 , in reality, the phase change material 71 is not exposed outside the capsule 72.

[0042] The capsules 72 are microcapsules made of, for example, acrylic resin, urethane resin, etc. By using the phase change material 71 that is pre-encapsulated in the capsules 72, it is possible to reduce the effort required to seal the phase change material 71 and to suppress the expansion and contraction of the phase change material 71.

[0043] Furthermore, the melting temperature of the phase change material 71 in this embodiment is higher than the saturation temperature (or maximum temperature) of the coil 4 during rated operation of the motor 1. Note that the "rated operation of the motor 1" in this disclosure refers to operating the motor 1 at a torque and rotation speed equivalent to the rated output of the motor 1.

[0044] FIG. 5 is an explanatory diagram illustrating the rate of temperature rise of the motor 1 according to this embodiment. FIG. 5 is an explanatory diagram illustrating the rate of temperature rise of the motor 1. Graph G21 in FIG. 5 is a graph showing the relationship between the operating time and the temperature of the coil 4 in the motor 1 according to this embodiment. Graph G22 is a graph showing the relationship between the operating time and the temperature of the coil in a motor according to a comparative example. The motor 1 according to this embodiment and the motor according to the comparative example have the same configuration except for the difference in the melting temperature of the phase change material. In the motor according to the comparative example, the melting temperature of the phase change material contained in the insulating member is lower than the saturation temperature of the coil during rated operation of the motor according to the comparative example. In the following description, the temperature of the coil 4 in the motor 1 according to this embodiment may be simply referred to as the "temperature of the coil 4," and the temperature of the coil in the motor according to the comparative example may be simply referred to as the "temperature of the comparative example coil."

[0045] Timing T0 is the timing when motor 1 of this embodiment and the comparative motor begin rated operation. Timing T1 is the timing when the temperature of the comparative coil reaches temperature K1. Here, temperature K1 is the melting temperature of the phase change material of the comparative motor. In other words, the phase change material of the comparative motor begins to melt at timing T1. As a result, the rate of temperature rise of the comparative coil becomes slower than the rate of temperature rise of coil 4 until the phase change material of the comparative motor finishes melting.

[0046] Timing T2 is the timing when the temperature of coil 4 reaches temperature K3. Temperature K3 is the saturation temperature of coil 4 and the comparative example coil during rated operation of motor 1 and the comparative example motor. Timing T3 is the timing when melting of the phase change material of the comparative example motor is completed. Note that temperature K2, which is the temperature of the comparative example coil at timing T3, is lower than temperature K3. Timing T4 is the timing when the temperature of the comparative example coil reaches temperature K3.

[0047] Timing T5 is the timing when the motor 1 of this embodiment and the motor of the comparative example begin high-load operation. Timing T6 is the timing when the temperature of the coil 4 reaches temperature K4. Here, temperature K4 is the melting temperature of the phase change material 71 of the motor 1. In other words, at timing T6, the phase change material 71 of the motor 1 begins to melt. As a result, the rate of temperature rise of the coil 4 becomes slower than the rate of temperature rise of the coil of the comparative example until the melting of the phase change material 71 is completed (until timing T8).

[0048] Timing T7 is the timing when the temperature of the comparative example coil reaches temperature K6, which is the maximum allowable temperature of coil 4 of motor 1 and the coil of the comparative example motor. In other words, in the comparative example motor, the temperature of the comparative example coil reaches the maximum allowable temperature during time X2 between timing T0 and timing T7.

[0049] Timing T8 is the timing when melting of the phase change material 71 of the motor 1 is completed. Note that temperature K5, which is the temperature of the coil 4 at timing T8, is lower than temperature K6. Timing T9 is the timing when the temperature of the coil 4 reaches temperature K6. In other words, in the motor 1 of this embodiment, the temperature of the coil 4 reaches the maximum allowable temperature during the time X1 between timing T0 and timing T9.

[0050] Here, time X1 is longer than time X2. In other words, according to the motor 1 of this embodiment, the melting temperature of the phase change material 71 is higher than the saturation temperature of the coil 4 during rated operation of the motor 1, which makes it possible to further reduce the rate at which the temperature of the motor 1 rises.

[0051] (3) Method of Forming Coil and Insulating Member Next, a method of forming the coil 4 and insulating member 6 of this embodiment will be described.

[0052] In this embodiment, the coil 4 and insulating member 6 are formed by applying the base material of the insulating member 6, which is an adhesive (i.e., the insulating member 6 before hardening), to the conductive wire 41 that forms the coil 4, and then winding the conductive wire 41 multiple times around the teeth 31. Here, the conductive wire 41 is wound around the teeth 31 so that adjacent portions of the conductive wire 41 are spaced apart. The conductive wire 41 is wound in multiple layers and is wound around the teeth 31 so that multiple cross sections of the conductive wire 41 included in one cut surface of the coil 4 are staggered. As time passes after the conductive wire 41 is wound around the teeth 31, the base material, which is the adhesive, hardens and the insulating member 6 is formed.

[0053] As described above, in the motor 1 of this embodiment, the coil 4 and the insulating member 6 are formed by applying the base material (the insulating member 6 before hardening) containing the phase change material to the conductor 41 and then winding the conductor 41 around the teeth 31. In this way, the phase change material 71 is evenly distributed around the conductor 41, which makes it possible to more effectively utilize the latent heat effect of the phase change material 71 and further reduce the rate at which the temperature of the motor 1 rises.

[0054] (4) Effects The inventors performed thermal analysis using a computer system and software to verify the effects of the motor 1 of this embodiment. The inventors performed thermal analysis using a computer system and software under multiple conditions in which the insulating member thickness A1 (see FIG. 3) and the content of the phase change material 71 contained in the insulating member 6 were changed. Note that the insulating member thickness A1 is equal to the first distance D3, for example.

[0055] FIG. 6 is a graph showing the results of thermal analysis of the motor 1 according to this embodiment. Graph G1 in FIG. 6 shows the results of thermal analysis of a comparative motor. Graph G1 shows the results of thermal analysis when the insulating member thickness A1 is 0.1 mm and the phase change material 71 content is 0%. Graph G2 shows the results of thermal analysis when the insulating member thickness A1 is 0.1 mm and the phase change material 71 content is 10%. Graph G3 shows the results of thermal analysis when the insulating member thickness A1 is 0.1 mm and the phase change material 71 content is 50%. Graph G4 shows the results of thermal analysis when the insulating member thickness A1 is 0.1 mm and the phase change material 71 content is 100%. Graph G5 shows the results of thermal analysis when the insulating member thickness A1 is 0.2 mm and the phase change material 71 content is 50%. Graph G6 shows the results of thermal analysis when the insulating member thickness A1 is 0.3 mm and the content of the phase change material 71 is 50%.

[0056] 6, the greater the content of phase change material 71 in insulating member 6, the greater the reduction in the rate of temperature rise of motor 1. Furthermore, the greater the insulating member thickness A1, that is, the greater the amount of phase change material 71 in space SP1, the greater the reduction in the rate of temperature rise of motor 1.

[0057] (5) Modifications Modifications of the above embodiment are listed below.

[0058] (5.1) Modification 1 The motor 1 of modification 1 differs from the motor 1 of the above embodiment in that the coils 4 and insulating members 6 are formed, for example, by a 3D printer (3-dimensional printer). The coils 4 and insulating members 6 are formed by the 3D printer so as to cover the periphery of the teeth 31, i.e., to fill the space SP1. However, the coils 4 and insulating members 6 may be formed in advance by the 3D printer and attached to the teeth 31.

[0059] In the motor 1 of the first modified example, the insulating member 6 is made of, for example, a synthetic resin. More specifically, the insulating member 6 is made of a synthetic resin that has a lower thermal resistance than the insulating member 6 that is an adhesive.

[0060] By forming the coil 4 and the insulating member 6 using a 3D printer, the spacing (first spacing D3) between adjacent portions of the conductor 41 in the winding axis direction D1 of the coil 4 can be made constant. In other words, the spacing (first spacing D3) between adjacent portions of the conductor 41 in the winding axis direction D1 of the coil 4 is constant in the conductor 41 of Modification 1. In the present disclosure, "constant spacing" does not necessarily mean that the spacing is strictly constant, and may include an error of, for example, about 5%.

[0061] Furthermore, in the conducting wire 41 of the first modification, the distance (second distance D4) between adjacent portions in the layer direction D2 of the coil 4 is constant.

[0062] By forming the coil 4 and the insulating member 6 using a 3D printer, it is possible to more reliably fill the gaps between adjacent portions of the conductor 41 with the insulating member 6. As a result, in the coil 4 of Modification 1, electrical insulation between adjacent portions of the conductor 41 can be ensured even if the conductor 41 is not covered with the insulating coating 42. In the motor 1 of Modification 1, the conductor 41 is directly covered by the insulating member 6 so as to be in contact with the insulating member 6. This reduces the thermal resistance between the conductor 41 and the insulating member 6, and can slow the rate at which the temperature of the coil 4 (or the conductor 41) rises.

[0063] The inventors have performed thermal analysis using a computer system and software to verify the effects of motor 1 of Modification 1. The inventors have performed thermal analysis using a computer system and software under multiple conditions in which the material of insulating member 6, the content of phase change material 71 contained in insulating member 6, the presence or absence of insulating coating 42, etc. have been changed.

[0064] FIG. 7 is a graph showing the results of thermal analysis of the motor 1 according to the first modification. Graph G11 in FIG. 7 shows the results of thermal analysis of the motor of the comparative example. Graph G11 shows the results of thermal analysis when the insulating member 6 is adhesive, the content of the phase change material 71 is 0%, and the conductor 41 is covered with the insulating coating 42. Graph G12 shows the results of thermal analysis when the insulating member 6 is synthetic resin, the content of the phase change material 71 is 0%, and the conductor 41 is covered with the insulating coating 42. Graph G13 shows the results of thermal analysis when the insulating member 6 is synthetic resin, the content of the phase change material 71 is 10%, and the conductor 41 is covered with the insulating coating 42. Graph G14 shows the results of thermal analysis when the insulating member 6 is synthetic resin, the content of the phase change material 71 is 20%, and the conductor 41 is covered with the insulating coating 42. Graph G15 shows the results of thermal analysis when the insulating member 6 is made of synthetic resin, the content of phase change material 71 is 50%, and the conducting wire 41 is covered with the insulating coating 42. Graph G16 shows the results of thermal analysis when the insulating member 6 is made of synthetic resin, the content of phase change material 71 is 0%, and the conducting wire 41 is not covered with the insulating coating 42. Graph G17 shows the results of thermal analysis when the insulating member 6 is made of synthetic resin, the content of phase change material 71 is 50%, and the conducting wire 41 is not covered with the insulating coating 42.

[0065] 7, the greater the content of phase change material 71 in insulating member 6, the more effectively the rate at which the temperature rises in motor 1 can be reduced. Furthermore, when conductor 41 is not covered with insulating coating 42, that is, when conductor 41 is directly covered with insulating member 6, the rate at which the temperature rises in motor 1 can be reduced even more.

[0066] (5.2) Modification 2 Fig. 8 is a schematic cross-sectional view showing a main part of the motor 1 according to Modification 2. As shown in Fig. 8, the conductor 41 may be wound in multiple layers and wound around the teeth 31 of the stator core 3 so that a plurality of cross sections of the conductor 41 included in one cut surface of the coil 4 are arranged in a matrix (checkerboard) configuration.

[0067] This increases the occupancy rate of the insulating member 6 in the space SP1. In other words, according to the motor 1 of the second modification, the amount of the phase change material 71 in the space SP1 can be increased, and the rate at which the temperature of the motor 1 rises can be further reduced.

[0068] (5.3) Modification 3 Fig. 9 is a schematic cross-sectional view showing a main part of the motor 1 according to Modification 3. As shown in Fig. 9, the conductor 41 of the motor 1 according to Modification 3 is a rectangular wire.

[0069] This increases the occupancy rate (or space factor) of the conducting wire 41 in the space SP1. According to the motor 1 of the third modification, increasing the space factor of the conducting wire 41 reduces loss in the coil 4 and increases the heat capacity of the coil 4, thereby further reducing the rate at which the temperature of the motor 1 rises.

[0070] 9 is a rectangular wire having a rectangular cross section, but the conductor 41 may be a rectangular wire having a cross section of another polygonal shape such as a hexagon.

[0071] (5.4) Modification 4 Fig. 10 is a schematic cross-sectional view showing a main part of the motor 1 according to Modification 4. As shown in Fig. 10, the conductor 41 of the motor 1 according to Modification 4 is a rectangular wire.

[0072] This allows the occupancy rate (or space factor) of the conducting wire 41 in the space SP1 to be increased. According to the motor 1 of the fourth modification, by increasing the space factor of the conducting wire 41, it is possible to further reduce loss in the coil 4 and increase the heat capacity of the coil 4, thereby further reducing the rate at which the temperature of the motor 1 rises.

[0073] (5.5) Other Modifications In the above embodiment, the motor 1 is an inner rotor motor, but the motor 1 may be an outer rotor motor. Also, in the above embodiment, the motor 1 is a servo motor, but the motor 1 may be a motor other than a servo motor.

[0074] (Aspects) As is clear from the above-described embodiments and modifications, a motor (1) according to a first aspect includes a stator (2) and a rotor (5). The rotor (5) has a plurality of permanent magnets (52) and rotates relative to the stator (2). The stator (2) includes a stator core (3), a coil (4), and an insulating member (6). The coil (4) is formed by winding a conductor (41) multiple times around the stator core (3). In the coil (4), adjacent portions of the conductor (41) are spaced apart. The insulating member (6) has electrical insulation properties. The insulating member (6) is arranged to cover the coil (4) and fill the spaces between adjacent portions of the conductor (41). The insulating member (6) includes a phase change material (71).

[0075] According to this aspect, the rate at which the temperature of the motor (1) rises can be reduced.

[0076] In the motor (1) according to the second aspect, in the first aspect, the phase change material (71) is encapsulated in a capsule (72).

[0077] According to this aspect, it is possible to reduce the effort required to seal the phase change material (71) and to suppress the expansion and contraction of the phase change material (71).

[0078] In the motor (1) according to the third aspect, in the first or second aspect, the insulating member (6) is an adhesive.

[0079] According to this embodiment, the rate at which the temperature of the motor (1) rises can be further reduced.

[0080] In the motor (1) according to the fourth aspect, in any one of the first to third aspects, the distance between adjacent portions of the conductor (41) in the winding axis direction (D1) of the coil (4) is constant.

[0081] In the motor (1) according to the fifth aspect, in any one of the first to fourth aspects, the conductor (41) is directly covered by the insulating member (6) so as to be in contact with the insulating member (6).

[0082] According to this embodiment, the rate at which the temperature of the conductor (41) rises can be reduced.

[0083] In the motor (1) according to the sixth aspect, in any of the first to fifth aspects, the melting temperature of the phase change material (71) is higher than the saturation temperature of the coil (4) during rated operation of the motor (1).

[0084] According to this embodiment, the rate at which the temperature of the motor (1) rises can be further reduced.

[0085] In the motor (1) according to the seventh aspect, in any of the first to sixth aspects, the conductor (41) is wound in multiple layers and is wound around the stator core (3) so that multiple cross sections of the conductor (41) included in one cut surface of the coil (4) are arranged in a matrix.

[0086] According to this embodiment, the rate at which the temperature of the motor (1) rises can be further reduced.

[0087] In the motor (1) according to the eighth aspect, in any of the first to sixth aspects, the conductor (41) is wound in multiple layers and is wound around the stator core (3) so that multiple cross sections of the conductor (41) included in one cut surface of the coil (4) are staggered.

[0088] According to this embodiment, the rate at which the temperature of the motor (1) rises can be further reduced.

[0089] In the motor (1) according to a ninth aspect, in any one of the first to eighth aspects, the conducting wire (41) is a round wire.

[0090] According to this embodiment, the rate at which the temperature of the motor (1) rises can be further reduced.

[0091] In the motor (1) according to a tenth aspect, in any one of the first to eighth aspects, the conductor (41) is a rectangular wire.

[0092] According to this embodiment, the rate at which the temperature of the motor (1) rises can be further reduced.

[0093] In the motor (1) according to the eleventh aspect, in the tenth aspect, the conductor (41) is a rectangular wire.

[0094] According to this embodiment, the rate at which the temperature of the motor (1) rises can be further reduced.

[0095] The configurations other than the first aspect are not essential for the motor (1) and can be omitted as appropriate.

[0096] The motor of the present disclosure can reduce the rate at which the temperature of the motor rises, which is particularly advantageous when the motor is operated under high load conditions. In this way, the motor of the present disclosure is industrially useful.

[0097] REFERENCE SIGNS LIST 1 Motor 2 Stator 3 Stator core 4 Coil 41 Conductive wire 5 Rotor 52 Permanent magnet 6 Insulating member 71 Phase change material 72 Capsule D1 Winding axis direction

Claims

1. A motor comprising: a stator; and a rotor having a plurality of permanent magnets and rotating relative to the stator, wherein the stator comprises: a stator core; coils each having a conductor wound around the stator core a plurality of times with adjacent portions of the conductor spaced apart; and an insulating member having electrical insulation properties, covering the coil, and arranged so as to fill the spaces between the adjacent portions of the conductor, the insulating member including a phase change material.

2. The motor according to claim 1, wherein the phase change material is encapsulated.

3. The motor according to claim 1 or 2, wherein the insulating member is an adhesive.

4. The motor according to claim 1 or 2, wherein the spacing between adjacent portions of the conducting wire in the direction of the winding axis of the coil is constant.

5. The motor according to claim 1 or 2, wherein the conductor is directly covered by the insulating member so as to be in contact with the insulating member.

6. The motor according to claim 1 or 2, wherein the melting temperature of the phase change material is higher than the saturation temperature of the coil during rated operation of the motor.

7. The motor according to claim 1 or 2, wherein the conductor is wound in multiple layers around the stator core such that a plurality of cross sections of the conductor included in one cross section of the coil are arranged in a matrix.

8. The motor according to claim 1 or 2, wherein the conductor is wound in multiple layers around the stator core so that a plurality of cross sections of the conductor included in one cross section of the coil are arranged in a staggered pattern.

9. The motor according to claim 1 or 2, wherein the conductor wire is a round wire.

10. The motor according to claim 1 or 2, wherein the conductor wire is a square wire.

11. The motor according to claim 10, wherein the conductor wire is a rectangular wire.

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