motor

Abstract

To provide a synchronous type motor that can reduce cogging torque without reducing output torque.SOLUTION: In a motor, a radial outer surface of a magnet insertion hole 24 of a rotor core has a pair of magnet opposite faces 245 opposite to the ends of a first magnet 22 and a second magnet 23, and a pair of circumferential end faces 246 extending from the ends in a circumferential direction of the magnet opposite faces 245 along an outer peripheral surface of the rotor core. The motor satisfies (0.92≤RT / ST≤0.96). RT: the center angle of each intersection between the magnet opposite faces 245 and the circumferential end faces 246. ST: with the magnetic pole corresponding number defined by dividing the total number of teeth 32 by the total number of magnetic poles composed of the first magnets 22 and the second magnets 23, the center angle between circumferential insides 321a of radial inner ends of teeth bases 321, to which coils 33 are attached, of teeth 32 at both ends in the circumferential direction of the magnetic pole corresponding number of teeth 32 arranged side by side in the circumferential direction.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a motor. [Background Art]

[0002] Conventionally, a rotor of a synchronous motor includes a plurality of permanent magnets that are inserted into a plurality of magnet insertion holes formed along an outer circumferential edge and each constitute a magnetic pole. A flux barrier formed of a gap is formed at each of opposing end portions of two oppositely arranged permanent magnets. A magnetic path portion is formed between these flux barriers. Torque ripple is reduced by optimizing the width of the opposing surface of the magnetic path portion. [Prior Art Documents] [Patent Documents]

[0003] [Patent Document 1] Japanese Unexamined Patent Publication No. 2015-53778 [Summary of the Invention] [Problem to be Solved by the Invention]

[0004] As in the synchronous motor described above, merely optimizing the width between the flux barriers does not sufficiently reduce torque ripple during rotation, and in particular, the effect of reducing cogging torque is low.

[0005] Accordingly, an object of the present invention is to provide a synchronous motor that can reduce cogging torque without reducing output torque. [Means for Solving the Problem]

[0006] An exemplary motor of the present invention comprises a shaft extending along a central axis, a rotor fixed to the shaft and rotatable together with the shaft about the central axis, and a stator radially opposite the rotor. The stator has a plurality of teeth extending radially inward from an annular stator core located radially outward from the rotor, each having a tooth base to which a coil is attached. The rotor has a plurality of magnet pairs arranged circumferentially, each having first and second magnets that are spaced further apart circumferentially toward the radially outward direction, and a rotor core having a plurality of magnet insertion holes into which a pair of the first and second magnets are inserted. The radially outward surface of the magnet insertion hole widens circumferentially toward the radially outward direction, and has a pair of magnet-facing surfaces that face the respective radially outward ends of the first and second magnets, The rotor has a pair of circumferential end faces extending from the circumferential end of the magnet-facing surface along the outer circumferential surface of the rotor core. When viewed in the direction along the central axis, the central angle of each intersection of the magnet-facing surface and the circumferential end faces with respect to the central axis is defined as the rotor feature value RT, and the number of magnetic poles obtained by dividing the total number of teeth by the total number of magnetic poles composed of the first magnet and the second magnet is defined as the number of magnetic poles, and the central angle of the radial inner end of the circumferential inner surface of the tooth base of the two teeth arranged at both ends aligned with respect to the number of magnetic poles in the circumferential direction is defined as the stator feature value ST, then 0.92 ≤ RT / ST ≤ 0.96 is satisfied. [Effects of the Invention]

[0007] According to an exemplary motor of the present invention, it is a synchronous motor, and smooth rotation is possible by reducing cogging torque. [Brief explanation of the drawing]

[0008] [Figure 1] Figure 1 is a perspective view of an exemplary motor of the present invention. [Figure 2] Figure 2 is a view of the motor, an example of the present invention shown in Figure 1, from the axial direction. [Figure 3] Figure 3 is a partially enlarged view of an exemplary motor of the present invention shown in Figure 2. [Figure 4] Figure 4 is a graph showing the results of an exemplary experiment 1 of the present invention. [Figure 5] Figure 5 is a graph showing the results of an exemplary experiment 2 of the present invention. [Modes for carrying out the invention]

[0009] The following description of an electric vehicle motor according to an embodiment of the present invention will be given with reference to the drawings. However, the scope of the present invention is not limited to the following embodiments and can be arbitrarily modified within the scope of the technical concept of the present invention.

[0010] In this specification, the direction parallel to the central axis Cx of the motor 100 shown in Figure 1 is referred to as the "axial direction." The radial direction perpendicular to the central axis Cx is simply referred to as the "radial direction," and the circumferential direction centered on the central axis Cx is simply referred to as the "circumferential direction."

[0011] Furthermore, in this specification, "ring-shaped" includes not only shapes that are continuous and uninterrupted throughout the entire circumferential region centered on the central axis Cx, but also shapes that have one or more breaks in a portion of the entire region centered on the central axis Cx.

[0012] Furthermore, in the positional relationship between any of the directions, lines, and planes and any of the others, "parallel" includes not only a state in which the two never intersect no matter how far they are extended, but also a state in which they are substantially parallel. Similarly, "orthogonal" includes not only a state in which the two intersect at a 90-degree angle, but also a state in which they are substantially perpendicular and a state in which they are substantially orthogonal. In other words, "parallel" and "orthogonal" each include a state in which there is an angular difference in the positional relationship between the two that does not deviate from the spirit of the present invention. Note that these are merely descriptive terms and are not intended to limit actual positional relationships, directions, or names.

[0013] <Motor 100> Figure 1 is a perspective view of an exemplary motor 100 of the present invention. Figure 2 is a view of the exemplary motor 100 of the present invention shown in Figure 1, viewed from the axial direction. Figure 3 is a partially enlarged view of the exemplary motor 100 of the present invention shown in Figure 2. As shown in Figures 1 and 2, the motor 100 is an 8-pole, 48-slot synchronous electric motor. That is, the motor 100 has 8 magnetic poles 101. In the motor 100, the 8 magnetic poles 101 are arranged at equal intervals in the circumferential direction.

[0014] As shown in Figures 1 and 2, the motor 100 includes a shaft 10, a rotor 20, and a stator 30. In the motor 100, the stator 30 is positioned radially outward from the rotor 20. The radial inner end of the stator 30 faces the radial outer end of the rotor 20 in the radial direction. That is, the stator 30 faces the rotor 20 in the radial direction.

[0015] <Shaft 10> The shaft 10 extends along the central axis Cx. The shaft 10 is cylindrical and rotatable about the central axis Cx. The shaft 10 is rotatably supported in the case (not shown) of the motor 100 via bearings (not shown).

[0016] <Rotor 20> The rotor 20 is cylindrical and extends in a direction along the central axis Cx which extends in the axial direction. In the motor 100 of this embodiment, the rotor 20 is fixed to the shaft 10 and is rotatable together with the shaft 10 about the central axis Cx. The rotor 20 has a rotor core 21 and a plurality of magnet pairs arranged in the circumferential direction. Each magnet pair has a first magnet 22 and a second magnet 23. In the rotor 20, the first magnet 22 and the second magnet 23 of one magnet pair are arranged further apart in the circumferential direction as they extend radially outward.

[0017] <Rotacore 21> The rotor core 21 is formed using a magnetic material. In the present embodiment, the rotor core 21 is a laminated body formed by laminating electromagnetic steel sheets in the axial direction. The rotor core 21 has a shaft hole 211 and a plurality of magnet insertion holes 24. The shaft hole 211 is disposed at the center when viewed in the axial direction and extends along the axial direction. The shaft hole 211 penetrates the rotor core 21 in the axial direction. The shaft 10 is press-fitted into the shaft hole 211. Thereby, the shaft 10 is fixed to the rotor core 21. The fixing of the shaft 10 and the rotor core 21 is not limited to press-fitting, and a wide range of methods that can firmly fix the shaft 10 and the rotor core 21 without deteriorating the rotational balance therebetween, such as welding, adhesion, and screwing, can be adopted.

[0018] A first magnet 22 and a second magnet 23 are inserted into each magnet insertion hole 24.

[0019] <First magnet 22 and second magnet 23> Both the first magnet 22 and the second magnet 23 are permanent magnets having the same flat plate shape (rectangular parallelepiped shape). That is, the first magnet 22 and the second magnet 23 have a rectangular parallelepiped shape. One side in the thickness direction of the first magnet 22 and the second magnet 23 is an N pole, and the other side is an S pole. In the rotor 20, for the first magnet 22 and the second magnet 23 inserted into one magnet insertion hole 24, one of the N pole and the S pole is disposed radially inward, and the other is disposed radially outward. In the circumferentially adjacent magnet insertion holes 24, the arrangement of the N pole and the S pole is reversed.

[0020] The method for fixing the first magnet 22 and the second magnet 23 to the rotor core 21 is, for example, adhesion. The fixing method is not limited to adhesion, and a wide range of methods that can firmly fix the first magnet 22 and the second magnet 23 to the rotor core 21, such as pressing by a separate non-magnetic component and insert molding with resin or the like, can be adopted. Furthermore, a plurality of these fixing methods may be used in combination.

[0021] <Magnet insertion hole 24> Viewed from the axial direction, the magnet insertion holes 24 widen circumferentially as they extend radially outward. In the motor 100 of this embodiment, each magnet insertion hole 24 is a continuous hole in the circumferential direction, and its circumferential middle portion is V-shaped, bending radially inward. The first magnet 22 and the second magnet 23 are arranged along the central axis Cx from one axial end of the rotor core 21. With this arrangement, the circumferential length of the first magnet 22 and the circumferential length of the second magnet 23 are equal. This arrangement maintains a balance between the magnetic flux from the first magnet 22 and the magnetic flux from the second magnet 23, thereby suppressing cogging torque.

[0022] The magnet insertion hole 24 has a radial inner surface 241 and a radial outer surface 242. The radial inner surface 241 and the radial outer surface 242 are radially opposite to each other. The pair of radial inner surfaces 241 are plane-symmetric with respect to a plane that includes the line where the two surfaces intersect and the central axis. The pair of radial outer surfaces 242 are also plane-symmetric with respect to the same plane as the pair of radial inner surfaces 241.

[0023] Furthermore, the magnet insertion hole 24 has a pair of first protrusions 243 and a second protrusion 244. The pair of first protrusions 243 are provided at both ends in the circumferential direction of the radial inner surface 241 and protrude radially outward. The second protrusion 244 is provided at the circumferential center of the radial outer surface 242 and protrudes radially inward.

[0024] The pair of radially outer surfaces 242 of the magnet insertion hole 24 each have a magnet-facing surface 245 and a circumferential end surface 246. The pair of magnet-facing surfaces 245 widen circumferentially as they extend radially outward, facing the radially outer ends of the first magnet 22 and the second magnet 23, respectively. The circumferential length of the magnet-facing surfaces 245 is longer than the circumferential lengths of the first magnet 22 and the second magnet 23, respectively. The pair of circumferential end surfaces 246 extend from the circumferential ends of the pair of magnet-facing surfaces 245 along the outer circumferential surface of the rotor core 21. In the motor 100 of this embodiment, the pair of magnet-facing surfaces 245 are in contact with the first magnet 22 and the second magnet 23, respectively, but they may not be in contact.

[0025] The first magnet 22 and the second magnet 23 are inserted into the magnet insertion hole 24. At this time, the circumferentially outer surfaces of the first magnet 22 and the second magnet 23 are in contact with the first protrusion 243. Also, the circumferentially opposing surfaces of the first magnet 22 and the second magnet 23 are in contact with the second protrusion 244. In this state, the first magnet 22 and the second magnet 23 are fixed in place by adhesive.

[0026] Furthermore, the fixing of the first magnet 22 and the second magnet 23 is not limited to adhesive bonding; methods such as pressing with a separate part or insert molding with resin may also be employed. In addition, a wide range of fixing methods can be adopted that firmly fix the first magnet 22 and the second magnet 23 without disrupting the balance of the rotor 20 during rotation. This suppresses circumferential displacement of the first magnet 22 and the second magnet 23 when the rotor 20 rotates.

[0027] As shown in Figure 3, by inserting the first magnet 22 and the second magnet 23 into the magnet insertion hole 24 and fixing them in place, flux barriers 247 are formed at both circumferential ends of the first magnet 22 and the second magnet 23.

[0028] More specifically, a first flux barrier 247a is provided in the magnet insertion hole 24 surrounded by one circumferential side surface of the first magnet 22, the magnet-facing surface 245, the circumferential end surface 246, and the first protrusion 243. A second flux barrier 247b is provided in the magnet insertion hole 24 surrounded by the other circumferential side surface of the second magnet 23, the magnet-facing surface 245, the circumferential end surface 246, and the first protrusion 243. A third flux barrier 247c is provided in the magnet insertion hole 24 surrounded by the other circumferential side surface of the first magnet 22, the second protrusion 244, one circumferential side surface of the second magnet 23, and the radial inner surface 241. By providing the flux barriers 247, abrupt changes in magnetic flux are suppressed, and torque fluctuations are reduced. Therefore, torque ripple when the rotor 20 rotates is suppressed.

[0029] The first magnet 22 and the second magnet 23 are inserted into the magnet insertion holes 24 and fixed in place, thereby forming magnetic poles Mp on the rotor 20. As shown in Figures 1 and 2, the rotor 20 has eight magnet insertion holes 24. In other words, in the motor 100 of this embodiment, the total number of magnetic poles Mp is eight.

[0030] In the motor 100 of this embodiment, the first magnet 22 and the second magnet 23 are inserted into a single magnet insertion hole 24, but the configuration is not limited to this. The magnet insertion hole may consist of two independent holes, with the first magnet 22 inserted into one and the second magnet 23 into the other. Even in such a case, a magnet-facing surface and a circumferential end surface are formed in each hole.

[0031] <Stata 30> The stator 30 has a stator core 31, teeth 32, and coils 33 (see Figures 2 and 3). The stator 30 is fixed to the motor case of the motor 100.

[0032] <Stator Core 31> The stator core 31 is formed using a magnetic material. In this embodiment, the stator core 31 is an annular structure positioned radially outward from the rotor 20 and is a laminate formed by stacking electromagnetic steel sheets in the axial direction. The stator core 31 is an annular structure surrounding the central axis Cx. The stator core 31 is fixed inside the motor case.

[0033] Multiple teeth 32 extend radially inward from the stator core 31, and coils 33 are attached to them. The multiple teeth 32 are arranged circumferentially. Each tooth 32 has a tooth base 321 and a tooth tip 322. The tooth base 321 is the portion that protrudes from the stator core 31. In this embodiment of the motor 100, the total number of teeth 32 is 48.

[0034] In each tooth 32, an insulator (not shown) is attached to at least the tooth base 321. The insulator is made of an electrically insulating material such as resin. A wire is wound around the tooth base 321 of each tooth 32 covered by the insulator to form a coil 33. That is, each tooth 32 has a tooth base 321 to which the coil 33 is attached. The wire is, for example, an enamel-coated copper wire or a metal wire covered with an insulating material. The presence of the insulator suppresses leakage and discharge from the coil 33 to the teeth 32.

[0035] The tooth tip 322 is connected to the radially inward end of the tooth base 321 and extends in both the circumferential directions. By providing the tooth tip 322, radial inward displacement of the conductor is suppressed when the conductor is wound around the tooth base 321 to form the coil 33. The insulator may cover at least the portion of the tooth tip 322 that may come into contact with the coil 33.

[0036] The coils 33 positioned on each tooth 32 are electrically connected by connecting wires (not shown). In this embodiment, the connecting wires are part of the conductor. However, the examples are not limited to this, and the connecting wires may be separate components from the conductor. When a drive current is supplied to each coil 33, the stator 30 is energized. The energization of the stator 30 causes the rotor 20 to rotate (drive).

[0037] <Optimization of Motor 100> Motor 100 has the configuration described above. Depending on the intended use, motor 100 requires that the rotor 20 rotate as smoothly as possible. In other words, rotation of the rotor 20 is required to suppress torque fluctuations (torque ripple). In motor 100, torque ripple is suppressed by reducing cogging torque.

[0038] The inventors of the present invention noticed that the cogging torque changes by adjusting the relative shape of the magnet insertion hole 24 and the teeth 32. Therefore, in order to quantitatively show the relationship between the shapes of the magnet insertion hole 24 and the teeth 32 in the motor 100, the rotor characteristic value RT, the stator characteristic value ST, and the shape coefficient RT / ST were defined as follows (see Figure 3).

[0039] As shown in Figure 3, the intersection point Cp is defined as the point where the magnet-facing surface 245 and the circumferential end surface 246 intersect when viewed from the direction of the central axis Cx. The intersection points Cp of a pair of magnet-facing surfaces 245 and a pair of circumferential end surfaces 246 are also separated in the circumferential direction and form a pair. The rotor feature value RT is defined as the central angle of the pair of intersection points Cp with respect to the central axis Cx. The rotor feature value RT represents the region in which magnetic flux flows at each magnetic pole Mp of the rotor 20.

[0040] Furthermore, the number of magnetic poles Mn is calculated by dividing the total number of teeth 32 by the total number of magnetic poles Mp composed of the first magnet 22 and the second magnet 23. In the motor 100 of this embodiment, the total number of teeth 32 is 48 and the total number of magnetic poles Mp is 8, so the number of magnetic poles Mn is 6. In this way, by making the total number of teeth 32 a multiple of the total number of magnetic poles Mp, the calculation of the shape coefficient RT / ST is made easy, and the manufacturing of a motor 100 with an optimized shape is made easy.

[0041] Then, viewed from the direction of the central axis Cx, the teeth 32 located at both ends in the circumferential direction of the Mn teeth 32 arranged in the circumferential direction are defined as end teeth 32a (see Figure 3). The stator characteristic value ST is the central angle between the circumferential inner ends 321a (see Figure 3) of the radial inner ends of the tooth base 321 of a pair of end teeth 32a, with the central axis Cx as the center. The stator characteristic value ST is the region (angle) from which the magnetic flux at the tooth 32 is received by the region where the magnetic flux flows at the magnetic pole Mp of the rotor 20.

[0042] The shape coefficient RT / ST is a variable that indicates the relationship between the magnet insertion hole 24 and the teeth 32, and is the value obtained by dividing the rotor feature value RT by the stator feature value ST.

[0043] An experiment was conducted to investigate the relationship between the shape coefficient RT / ST, defined as described above, and the cogging torque. Details of the experiment are shown below. In the experiment, models with different dimensions for each part were prepared using the motor 100 described above as the basic configuration, and the cogging torque was measured for each model when the shape coefficient RT / ST changed. The shape coefficient RT / ST was adjusted by changing the rotor characteristic value RT while keeping the stator characteristic value ST a fixed value. More specifically, the shape coefficient RT / ST was adjusted by changing the lengths of the magnet opposing surface 245 and the circumferential end surface 246.

[0044] <Experiment 1> First, the cogging torque was measured for three types of motors 100 in which the circumferential length L of the first magnet 22 and the circumferential length L of the second magnet 23 were constant, but the diameter d of the rotor 20 was different, when the shape coefficient RT / ST was changed.

[0045] Experiment 1 used three models, Model A, Model B, and Model C, each with a different rotor diameter d. Model A has a rotor diameter d of 97.4 mm. Model B has a rotor diameter d of 90 mm. Model C has a rotor diameter d of 105 mm. In each model, the diameter d and inner diameter of the stator 30 were determined to match the diameter of the rotor 20. The circumferential length L of the first magnet 22 and the second magnet 23 was 9.6 mm in all models.

[0046] The results of Experiment 1 are shown in Figure 4. Figure 4 is a graph showing the results of Experiment 1. The graph in Figure 4 shows the relationship between the shape coefficient RT / ST and the cogging torque ratio Rc when the circumferential length L of the first magnet 22 and the second magnet is kept constant and the diameter of the rotor 20 is changed. In Figure 4, the horizontal axis is the shape coefficient RT / ST. The vertical axis is the cogging torque ratio Rc. Here, the cogging torque ratio Rc is the ratio of the cogging torque to the maximum torque in each model. More specifically, the cogging torque ratio Rc is cogging torque / maximum torque. The results for Model A are shown by a solid line, the results for Model B by a dashed line, and the results for Model C by a dashed line.

[0047] As shown in Figure 4, it was found that the cogging torque ratio Rc of all three models, A, B, and C, has a minimum value. The shape factor RT / ST at which the minimum value occurs differs depending on the model, but it was found to be approximately between 0.92 and 0.96. Based on the results of Experiment 1, the shape factor that can suppress cogging torque to a small extent is 0.92 ≤ RT / ST ≤ 0.96.

[0048] Furthermore, the diameter d of the rotor 20 is between 90 mm and 105 mm. This configuration allows for the easy manufacture of a motor 100 with an optimized shape.

[0049] <Experiment 2> Next, the cogging torque was measured for three types of motors 100 in which the diameter d of the rotor 20 was constant, but the circumferential length L between the first magnet 22 and the second magnet 23 was different, when the shape coefficient RT / ST was changed.

[0050] In Experiment 2, three models, Model A, Model D, and Model E, were used, each with a different circumferential length L between the first magnet 22 and the second magnet 23. Model A is the same as Model A in Experiment 1, with a circumferential length L of 9.6 mm between the first magnet 22 and the second magnet 23. Model D has a circumferential length L of 9 mm between the first magnet 22 and the second magnet 23. Model E has a circumferential length L of 10 mm between the first magnet 22 and the second magnet 23. The diameter d of the rotor 20 is 97.4 mm in all models.

[0051] The results of Experiment 2 are shown in Figure 5. Figure 5 is a graph showing the results of Experiment 2. The graph in Figure 5 shows the relationship between the shape factor RT / ST and the cogging torque ratio Rc when the diameter of the rotor 20 is kept constant and the circumferential length L between the first magnet 22 and the second magnet 23 is varied. In Figure 5, the horizontal axis is the shape factor RT / ST. The vertical axis is the cogging torque ratio Rc. Here, the cogging torque ratio Rc is the same as in Figure 4. The results for Model A are shown by a solid line, the results for Model D by a dotted line, and the results for Model C by a dashed line.

[0052] As shown in Figure 5, it was found that the cogging torque ratio Rc of all three models, A, D, and E, has a minimum value. The shape factor RT / ST at which the minimum value occurs differs depending on the model, but it was found to be approximately between 0.92 and 0.96. Based on the results of Experiment 1, the shape factor that can suppress cogging torque to a small extent is 0.92 ≤ RT / ST ≤ 0.96.

[0053] Furthermore, the circumferential length L between the first magnet 22 and the second magnet 23 inserted into the magnet insertion hole 24 is 9 mm or more and 10 mm or less.

[0054] Based on Experiments 1 and 2, the motor 100 of this embodiment can suppress cogging torque to a small level when 0.92 ≤ RT / ST ≤ 0.96 is satisfied, regardless of the diameter d of the rotor 20 and the circumferential length L between the first magnet 22 and the second magnet 23.

[0055] In other words, in this embodiment, when the motor 100 is viewed in the direction along the central axis Cx, the central angle of each intersection of the magnet-facing surface 245 and the circumferential end surface 246 with respect to the central axis Cx is defined as the rotor characteristic value RT, and the number of magnetic pole correspondences Mn is the value obtained by dividing the total number of teeth 32 by the total number of magnetic poles Mp composed of the first magnet 22 and the second magnet 23, and the central angle of the radial inner end 321a of the circumferential inner surface of the tooth base 321 of the two teeth 32a arranged at both ends with a magnetic pole correspondence number Mn aligned in the circumferential direction is defined as the stator characteristic value ST, then the motor satisfies 0.92 ≤ RT / ST ≤ 0.96.

[0056] In motor 100, by keeping the cogging torque low, torque ripple during the rotation of rotor 20 is suppressed, allowing rotor 20 to rotate smoothly. This reduces vibration and noise. Furthermore, by keeping the cogging torque low, the torque required to start motor 100 can be reduced. This makes it possible to reduce the power required for starting.

[0057] <Summary> The motor 100 of the present invention has the following configuration.

[0058] (1) The rotor comprises a shaft extending along a central axis, a rotor fixed to the shaft and rotatable together with the shaft about the central axis, and a stator radially opposite the rotor. The stator is, The rotor has a plurality of teeth that extend radially inward from an annular stator core located radially outward, and each tooth has a tooth base to which a coil is attached. The rotor is It has a first magnet and a second magnet that are arranged further apart in the circumferential direction as they extend radially outward, and a plurality of magnet pairs arranged in the circumferential direction, The rotor core has a plurality of magnet insertion holes into which a pair of first magnets and a second magnet are inserted. The radially outward surface of the magnet insertion hole is The surface widens circumferentially as it extends radially outward, and has a pair of magnet-facing surfaces that face the radially outward ends of the first magnet and the second magnet, It has a pair of circumferential end faces extending from the circumferential end of the magnet-facing surface along the outer circumferential surface of the rotor core. Viewed in the direction along the central axis, the central angle of each intersection point between the magnet-facing surface and the circumferential end surface, with respect to the central axis, is defined as the rotor characteristic value RT. A motor that satisfies 0.92 ≤ RT / ST ≤ 0.96, where the number of magnetic poles is obtained by dividing the total number of teeth by the total number of magnetic poles composed of the first magnet and the second magnet, and the stator characteristic value ST is the central angle of the radial inner end of the circumferential inner surface of the tooth base of the two teeth arranged at both ends in the circumferential direction by the number of magnetic poles, with respect to the central axis.

[0059] (2) The motor according to (1), wherein the total number of teeth is 48 and the total number of magnetic poles is 8.

[0060] (3) The motor according to (1) or (2), wherein the first magnet and the second magnet are identical rectangular parallelepipeds, and the circumferential length of the first magnet and the circumferential length of the second magnet inserted into the magnet insertion hole are 9 mm or more and 10 mm or less.

[0061] (4) A motor according to any one of (1) to (3), wherein the circumferential length of the first magnet inserted into the magnet insertion hole is equal to the circumferential length of the second magnet.

[0062] (5) The motor according to any one of (1) to (4), wherein the diameter of the rotor is 90 mm or more and 105 mm or less.

[0063] Although embodiments of the present invention have been described above, the configurations and combinations thereof in the embodiments are merely examples, and additions, omissions, substitutions, and other modifications to the configurations are possible without departing from the spirit of the present invention. Furthermore, the present invention is not limited by the embodiments. [Industrial applicability]

[0064] The configuration of this invention can be used as an electric motor. [Explanation of symbols]

[0065] 100 motor 101 magnetic pole 10 shafts 20 rotors 21 Rotor Core 211 Shaft Hole 22 First Magnet 23 Second Magnet 24 Magnet insertion holes 241 Radial inner surface 242 Radial outer surface 243 First protrusion 244 Second protrusion 245 Magnet opposing surface 246 Circumferential end face 247 Flux Barrier 30 staters 31 Stator Core 32 Teeth 321 Teeth base 322 Tooth tip 32a Outer end teeth 321a Circumferential inside 33 coils

Claims

1. A shaft extending along the central axis, A rotor fixed to the shaft and capable of rotating together with the shaft about a central axis, The rotor and the stator are radially opposite each other, The stator is, The rotor has a plurality of teeth that extend radially inward from an annular stator core located radially outward, and each tooth has a tooth base to which a coil is attached. The rotor is It has a first magnet and a second magnet, which are flat plates that constitute the magnetic poles, and a plurality of magnet pairs arranged in the circumferential direction, A rotor core having a plurality of magnet insertion holes into which a pair of first magnets and a second magnet are inserted, The radially outward surface of the magnet insertion hole is Arranged circumferentially such that, when viewed along the central axis, the central part in the circumferential direction is V-shaped with the radially inward bending portion, and a pair of magnet-facing surfaces facing the radially outward ends of the first magnet and the second magnet, It has a pair of circumferential end faces extending from the circumferential end of the magnet-facing surface along the outer circumferential surface of the rotor core, Viewed in the direction along the central axis, the central angle of each intersection point between the magnet-facing surface and the circumferential end surface, with respect to the central axis, is defined as the rotor characteristic value RT. When the number of teeth is divided by the total number of magnetic poles to obtain the number of magnetic pole correspondences, and the central angle of the radial inner end of the circumferential inner surface of the tooth base of the two teeth arranged at both ends in the circumferential direction with respect to the central axis is defined as the stator characteristic value ST, A motor that satisfies the condition 0.92 ≤ RT / ST ≤ 0.

96.

2. The total number of teeth is 48. The motor according to claim 1, wherein the total number of magnetic poles is 8.

3. The first magnet and the second magnet are identical rectangular parallelepiped shapes. The motor according to claim 1 or claim 2, wherein the circumferential length of the first magnet inserted into the magnet insertion hole and the circumferential length of the second magnet are 9 mm or more and 10 mm or less.

4. The motor according to claim 3, wherein the circumferential length of the first magnet inserted into the magnet insertion hole is equal to the circumferential length of the second magnet.

5. The motor according to claim 1 or claim 2, wherein the diameter of the rotor is 90 mm or more and 105 mm or less.

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