Electric motors, fans, and air conditioners

Abstract

The electric motor comprises: a rotor having 10×N magnetic poles (N is an integer greater than or equal to 1); and a stator having 9×N teeth. The central tooth (311) comprises a first main body (311a) and a first tooth tip (311b). The downstream tooth (312) comprises a second main body (312a) and a second tooth tip (312b). When the maximum length of the first upstream portion (321a) of the first tooth tip (311b) in the first upstream radial direction is TCR, and the maximum length of the second upstream portion (322a) of the second tooth tip (312b) in the second upstream radial direction is TBR, the electric motor (1) satisfies TCR>TBR.

Description

Technical Field

[0001] The present disclosure relates to electric motors. Background Art

[0002] Generally, a 10-pole, 9-slot motor is known. This motor has a large winding coefficient, allowing for efficient use of the magnetic flux of the magnets within the motor. However, this motor suffers from a large radial excitation force, which causes noise. Therefore, a motor has been proposed in which the radial thickness of the tip of the center tooth among three adjacent teeth is thinner than the radial thickness of the tip of the adjacent teeth (for example, Patent Document 1).

[0003] Prior art literature

[0004] Patent Literature

[0005] Patent Document 1: International Publication No. 2015 / 029256 Summary of the Invention

[0006] Problems to be solved by the invention

[0007] However, in the conventional technology, the density of the magnetic flux flowing into three adjacent teeth is unbalanced between these teeth, and this unbalance causes noise when the rotor rotates.

[0008] An object of the present disclosure is to improve the density imbalance of magnetic flux flowing into teeth of a stator core and reduce noise during rotor rotation.

[0009] Means for solving problems

[0010] The electric motor disclosed herein comprises:

[0011] a rotor having 10×N magnetic poles, where N is an integer greater than or equal to 1; and

[0012] The stator comprises: an annular core back; 9×N teeth extending from the annular core back toward the rotor; and a three-phase coil wound around the 9×N teeth in a concentrated winding manner.

[0013] The three-phase coils are wound around the 9×N teeth so that the three-phase coils wound around three circumferentially adjacent teeth among the 9×N teeth form the same phase.

[0014] The central tooth located in the center of the three teeth around which the three-phase coil forming the same phase is wound has:

[0015] a first main body portion extending from the annular core back toward the rotor; and

[0016] a first tooth front end portion, which is located at the end of the central tooth and extends along the circumferential direction;

[0017] The first tooth tip portion includes a first upstream portion located upstream in the rotational direction of the rotor and a first downstream portion located downstream in the rotational direction.

[0018] The downstream side tooth located on the downstream side in the rotation direction among the three teeth has:

[0019] a second main body portion extending from the annular core back toward the rotor; and

[0020] a second tooth front end portion, which is located at the end of the downstream side tooth and extends along the circumferential direction;

[0021] The second tooth tip portion includes a second upstream portion located on the upstream side in the rotation direction and a second downstream portion located on the downstream side in the rotation direction.

[0022] In a plane perpendicular to the axial direction, a direction parallel to a first upstream straight line passing through a boundary between the first main body portion and the first upstream portion and the rotation center of the rotor is defined as a first upstream radial direction.

[0023] In the plane, a direction parallel to a second upstream straight line passing through a boundary between the second main body portion and the second upstream portion and the rotation center is defined as a second upstream radial direction.

[0024] In the plane, let the maximum length of the first upstream portion in the first upstream radial direction be TCR, and let the maximum length of the second upstream portion in the second upstream radial direction be TBR. In this case,

[0025] Satisfies TCR>TBR.

[0026] A fan according to another aspect of the present disclosure includes:

[0027] blades; and

[0028] The electric motor drives the blades.

[0029] Another aspect of the present disclosure relates to an air conditioner comprising:

[0030] indoor unit; and

[0031] an outdoor unit connected to the indoor unit,

[0032] The indoor unit, the outdoor unit, or both the indoor unit and the outdoor unit include the electric motor.

[0033] Effects of the Invention

[0034] According to the present disclosure, it is possible to improve the density imbalance of magnetic flux flowing into the teeth of the stator core and reduce noise generated during the rotation of the rotor. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 This is a partial cross-sectional view schematically showing the electric motor according to the first embodiment.

[0036] Figure 2 It is a cross-sectional view schematically showing the motor in the xy plane.

[0037] Figure 3 It is a cross-sectional view schematically showing the rotor.

[0038] Figure 4 It is a cross-sectional view schematically showing a stator.

[0039] Figure 5 It is a cross-sectional view showing an example of a coil.

[0040] Figure 6 It shows Figure 4 An enlarged view of a portion of the stator is shown.

[0041] Figure 7 is a top view showing the central tooth.

[0042] Figure 8 It is a top view showing the downstream side teeth.

[0043] Figure 9 It is a top view showing the upstream side teeth.

[0044] Figure 10 is a top view showing the central tooth.

[0045] Figure 11 It is a top view showing the downstream side teeth.

[0046] Figure 12 It is a top view showing the upstream side teeth.

[0047] Figure 13 This is a graph showing the maximum value of magnetic flux density at the upstream side of the tip of each of three circumferentially adjacent teeth wound with coils forming the same phase when the rotor of the electric motor as a comparative example rotates.

[0048] Figure 14 The graph shows the maximum values of magnetic flux density at each measuring point at the tip of each of three circumferentially adjacent teeth wound with coils forming the same phase when the rotor of an electric motor as a comparative example rotates.

[0049] Figure 15 This is a diagram showing another example of a stator core.

[0050] Figure 16 This is a diagram schematically showing a fan according to the second embodiment.

[0051] Figure 17 This is a diagram schematically showing the configuration of an air conditioner according to Embodiment 3. DETAILED DESCRIPTION

[0052] Implementation method 1.

[0053] In the xyz rectangular coordinate system shown in each figure, the z-axis direction (z-axis) represents the direction parallel to the axis Ax of the motor 1, the x-axis direction (x-axis) represents the direction perpendicular to the z-axis direction, and the y-axis direction (y-axis) represents the direction perpendicular to both the z-axis direction and the x-axis direction. The axis Ax is the center of rotation of the rotor 2, that is, the rotation axis of the rotor 2. The direction parallel to the axis Ax is also called the "axial direction of the rotor 2" or simply the "axial direction". The radial direction is the radial direction of the rotor 2 or the stator 3, and is the direction perpendicular to the axis Ax. The xy plane is a plane perpendicular to the axial direction. Arrow D10 represents the circumferential direction centered on the axis Ax. The circumferential direction of the rotor 2 or the stator 3 is also simply referred to as the "circumferential direction".

[0054] Figure 1 This is a partial cross-sectional view schematically showing the electric motor 1 according to the first embodiment.

[0055] Figure 2 1 is a schematic cross-sectional view of the motor 1 in the xy plane. Arrow D11 among the arrows shown in D10 indicates the rotation direction of the rotor 2. Arrow D12 among the arrows shown in D10 indicates the direction opposite to the rotation direction of the rotor 2.

[0056] The motor 1 includes a rotor 2, a stator 3, a circuit board 4, a molded resin 5, and bearings 7a and 7b that rotatably hold the rotor 2. The motor 1 is, for example, a permanent magnet synchronous motor (also called a brushless DC motor) such as an embedded permanent magnet motor.

[0057] The bearings 7a and 7b rotatably support the rotor 2.

[0058] Rotor 2

[0059] The rotor 2 is rotatably arranged inside the stator 3. An air gap exists between the rotor 2 and the stator 3. The rotor 2 rotates around the axis Ax.

[0060] Figure 3 It is a cross-sectional view schematically showing the rotor 2 .

[0061] The rotor 2 includes a resin 21 , at least one permanent magnet 22 serving as a main magnet, and a shaft 23 .

[0062] The permanent magnet 22 is longer in the axial direction than the stator core 31. This structure provides an advantage in that the magnetic flux from the rotor 2 can also easily flow into both ends of the stator core in the axial direction.

[0063] A rotor core can also be used in place of resin 21. In this case, the rotor core is formed from multiple electromagnetic steel sheets. Each electromagnetic steel sheet has a thickness of, for example, 0.2 mm to 0.5 mm. The electromagnetic steel sheets are stacked axially. However, the rotor core can also be a resin core formed by mixing soft magnetic material and resin, instead of multiple electromagnetic steel sheets. The rotor core functions as a back yoke in rotor 2.

[0064] Each permanent magnet 22 is, for example, a rare-earth magnet containing neodymium, a rare-earth magnet containing samarium, or a ferrite magnet containing iron.

[0065] exist Figure 3 In the example shown, rotor 2 is an SPM (Surface Permanent Magnet) rotor. Specifically, multiple permanent magnets 22 are mounted on the outer circumference of resin 21. Each permanent magnet 22 is magnetized in the radial direction. Consequently, magnetic flux from the permanent magnets 22 flows into stator core 31.

[0066] The rotor 2 has 10×N magnetic poles (N is an integer greater than 1). In this embodiment, N=1. Figure 3 In the example shown, the rotor 2 has 10 magnetic poles. Figure 3 In the example shown, the rotor 2 has ten permanent magnets 22 .

[0067] Instead of the SPM rotor, an IPM (Interior Permanent Magnet) rotor may be used as the rotor 2. When the rotor 2 is an IPM rotor, permanent magnets 22 serving as main magnets are inserted into a plurality of magnet insertion holes formed in the resin 21 or the rotor core.

[0068] The shaft 23 is inserted into a hole formed in the center portion of the resin 21 , for example.

[0069] The shaft 23 is integrated with the resin 21 by caulking or a resin such as polybutylene terephthalate (PBT). The shaft 23 may be fixed to the resin 21 by press-fitting or shrink-fitting.

[0070] Stator 3

[0071] Figure 4 It is a cross-sectional view schematically showing the stator 3 .

[0072] The stator 3 is arranged outside the rotor 2. The stator 3 includes a stator core 31 and at least one coil 32. The stator 3 may also include at least one insulator 33.

[0073] The stator core 31 has a core back 31a (also called a yoke) and 9×N teeth 31b extending from the core back 31a toward the rotor 2. The core back 31a is, for example, an annular core back. In this embodiment, N=1. Therefore, Figure 4 In the example shown, the stator core 31 has nine teeth 31 b and nine slots.

[0074] Each tooth 31b extends in the radial direction. In other words, each tooth 31b extends from the core back 31a toward the rotation center of the rotor 2. Figure 4 In the example shown, the stator core 31 has nine teeth 31 b.

[0075] The stator core 31 is composed of, for example, a plurality of thin magnetic iron plates. The stator core 31 is, for example, a plurality of electromagnetic steel plates stacked in the axial direction. The stator core 31 is an annular core. The thickness of each electromagnetic steel plate of the stator core 31 is, for example, 0.2 mm to 0.5 mm.

[0076] Figure 5 3 is a cross-sectional view showing an example of the coil 32 .

[0077] The coils 32 are three-phase coils. That is, the coils 32 have three phases: U phase, V phase, and W phase. Each coil 32 is wound around each tooth 31b using concentrated winding. The coils 32 are formed from a conductive wire having a diameter D1.

[0078] The coils 32 are wound around the 9×N teeth 31 b so that the coils 32 wound around three teeth 31 b adjacent to each other in the circumferential direction among the 9×N teeth form the same phase.

[0079] When the stator 3 has an insulator 33, the coil 32 is wound around the insulator 33 attached to the stator core 31. In this case, the coil 32 is insulated by the insulator 33. The coil 32 is made of a material containing copper or aluminum, for example.

[0080] Insulator 33 is made of an insulating resin such as polybutylene terephthalate (PBT), polyphenylene sulfide (PPS), liquid crystal polymer (LCP), or polyethylene terephthalate (PET). Resin insulator 33 is, for example, an insulating film having a thickness of 0.035 mm to 0.4 mm.

[0081] For example, the insulator 33 is integrally molded with the stator core 31. However, the insulator 33 may be molded separately from the stator core 31. In this case, the insulator 33 is embedded in the stator core 31 after being molded.

[0082] In this embodiment, the stator core 31, coil 32, and insulator 33 are covered with molded resin 5. Alternatively, the stator core 31, coil 32, and insulator 33 may be fixed by, for example, a cylindrical housing made of a material containing iron. In this case, for example, the stator 3 and the rotor 2 are covered by the cylindrical housing by shrink fit.

[0083] The circuit board 4 is fixed to the stator 3 . The circuit board 4 has a driving element for controlling the motor 1 .

[0084] The mold resin 5 integrates the circuit board 4 and the stator 3. The mold resin 5 is, for example, a thermosetting resin such as unsaturated polyester resin (BMC) or epoxy resin.

[0085] The stator core 31 will be described in detail.

[0086] Figure 6 It shows Figure 4 An enlarged view of a portion of the stator 3 is shown.

[0087] In the xy plane, the central tooth 31b of the three circumferentially adjacent teeth 31b is referred to as the "central tooth 311." In the xy plane, the tooth 31b located downstream in the rotational direction of the rotor 2 of the three circumferentially adjacent teeth 31b is referred to as the "downstream tooth 312." In the xy plane, the upstream tooth 31b of the three circumferentially adjacent teeth 31b is referred to as the "upstream tooth 313."

[0088] Coils 32 of the same phase are wound around the central tooth 311, the downstream teeth 312, and the upstream teeth 313. That is, when current flows through the coils 32, the coils 32 wound around the central tooth 311, the coils 32 wound around the downstream teeth 312, and the coils 32 wound around the upstream teeth 313 form the same phase (e.g., U-phase, V-phase, or W-phase).

[0089] 〈Central tooth 311〉

[0090] Figure 7 31 is a top view showing the central tooth 311 .

[0091] The center tooth 311 is the center tooth among the three circumferentially adjacent teeth 31b around which the coil 32 forming the same phase is wound. The center tooth 311 has a first body portion 311a (also called the center body portion) and a first tooth tip portion 311b (also called the center tooth tip portion).

[0092] The first main body portion 311a extends from the core back 31a toward the rotor 2. The first tooth tip portion 311b is located at the radial end of the center tooth 311 and extends in the circumferential direction. The first tooth tip portion 311b faces the rotor 2.

[0093] The first tooth tip portion 311 b includes a first upstream portion 321 a located upstream in the rotational direction of the rotor 2 , and a first downstream portion 321 b located downstream in the rotational direction of the rotor 2 .

[0094] <Downstream side teeth 312>

[0095] Figure 8 31 is a top view showing the downstream side teeth 312 .

[0096] The downstream teeth 312 are located downstream in the rotational direction of the rotor 2, among the three circumferentially adjacent teeth 31b around which the coils 32 forming the same phase are wound. Specifically, the downstream teeth 312 are located downstream of the central teeth 311 in the rotational direction of the rotor 2. The downstream teeth 312 have a second main body portion 312a (also referred to as the downstream main body portion) and a second tooth tip portion 312b (also referred to as the downstream tooth tip portion).

[0097] The second main body portion 312a extends from the core back 31a toward the rotor 2. The second tooth tip portion 312b is located at the radial end of the downstream tooth 312 and extends circumferentially. The second tooth tip portion 312b faces the rotor 2.

[0098] The second tooth tip portion 312 b includes a second upstream portion 322 a located upstream in the rotational direction of the rotor 2 , and a second downstream portion 322 b located downstream in the rotational direction of the rotor 2 .

[0099] Upstream tooth 313

[0100] Figure 9 It is a plan view showing the upstream-side teeth 313 .

[0101] The upstream tooth 313 is the tooth located upstream in the rotational direction of the rotor 2, among the three circumferentially adjacent teeth 31b around which the coil 32 forming the same phase is wound. That is, the upstream tooth 313 is located upstream of the central tooth 311 in the rotational direction of the rotor 2. The upstream tooth 313 has a third main body portion 313a (also referred to as the upstream main body portion) and a third tooth tip portion 313b (also referred to as the upstream tooth tip portion).

[0102] The third main body portion 313a extends from the core back 31a toward the rotor 2. The third tooth tip portion 313b is located at the radial end of the upstream tooth 313 and extends in the circumferential direction. The third tooth tip portion 313b faces the rotor 2.

[0103] The third tooth tip portion 313 b includes a third upstream portion 323 a located upstream in the rotational direction of the rotor 2 , and a third downstream portion 323 b located downstream in the rotational direction of the rotor 2 .

[0104] Figure 10 31 is a top view showing the central tooth 311 .

[0105] In the xy plane, a direction parallel to the first upstream straight line L11 is defined as a "first upstream radial direction," where the first upstream straight line L11 passes through the boundary P11 between the first main body portion 311a and the first upstream portion 321a and the rotation center of the rotor 2. In the xy plane, a direction parallel to the first downstream straight line L12 is defined as a "first downstream radial direction," where the first downstream straight line L12 passes through the boundary P12 between the first main body portion 311a and the first downstream portion 321b and the rotation center of the rotor 2.

[0106] like Figure 10 As shown, the length TCR is the length of the first tooth tip portion 311b (specifically, the first upstream portion 321a) on the first upstream straight line L11 in the xy plane. In this embodiment, the length TCR is the maximum length of the first tooth tip portion 311b (specifically, the first upstream portion 321a) in the first upstream radial direction in the xy plane. Figure 10 As shown, the length TCL is the length of the first tooth tip portion 311b (specifically, the first downstream portion 321b) on the first downstream straight line L12 in the xy plane. In the present embodiment, the length TCL is the maximum length of the first tooth tip portion 311b (specifically, the first downstream portion 321b) in the first downstream radial direction in the xy plane.

[0107] Figure 11 31 is a top view showing the downstream side teeth 312 .

[0108] In the xy plane, a direction parallel to the second upstream straight line L21 is defined as a "second upstream radial direction," where the second upstream straight line L21 passes through the boundary P21 between the second main body portion 312a and the second upstream portion 322a, and the rotation center of the rotor 2. In the xy plane, a direction parallel to the second downstream straight line L22 is defined as a "second downstream radial direction," where the second downstream straight line L22 passes through the boundary P22 between the second main body portion 312a and the second downstream portion 322b, and the rotation center of the rotor 2.

[0109] like Figure 11 As shown, the length TBR is the length of the second tooth tip portion 312b (specifically, the second upstream portion 322a) on the second upstream straight line L21 in the xy plane. In this embodiment, the length TBR is the maximum length of the second tooth tip portion 312b (specifically, the second upstream portion 322a) in the second upstream radial direction in the xy plane. Figure 11 As shown, the length TBL is the length of the second tooth tip portion 312b (specifically, the second downstream portion 322b) on the second downstream straight line L22 in the xy plane. In the present embodiment, the length TBL is the maximum length of the second tooth tip portion 312b (specifically, the second downstream portion 322b) in the second downstream radial direction in the xy plane.

[0110] Figure 12 It is a plan view showing the upstream-side teeth 313 .

[0111] In the xy plane, a direction parallel to the third upstream straight line L31 is defined as a "third upstream radial direction," where the third upstream straight line L31 passes through the boundary P31 between the third main body portion 313a and the third upstream portion 323a, and the rotation center of the rotor 2. In the xy plane, a direction parallel to the third downstream straight line L32 is defined as a "third downstream radial direction," where the third downstream straight line L32 passes through the boundary P32 between the third main body portion 313a and the third downstream portion 323b, and the rotation center of the rotor 2.

[0112] like Figure 12 As shown, the length TFR is the length of the third tooth tip portion 313b (specifically, the third upstream portion 323a) on the third upstream straight line L31 in the xy plane. In this embodiment, the length TFR is the maximum length of the third tooth tip portion 313b (specifically, the third upstream portion 323a) in the third upstream radial direction in the xy plane. Figure 12As shown, the length TFL is the length of the third tooth tip portion 313b (specifically, the third downstream portion 323b) on the third downstream straight line L32 in the xy plane. In the present embodiment, the length TFL is the maximum length of the third tooth tip portion 313b (specifically, the third downstream portion 323b) in the third downstream radial direction in the xy plane.

[0113] Figure 13 This is a graph showing the maximum value of the magnetic flux density at the upstream side of the tip of each of three circumferentially adjacent teeth wound with coils forming the same phase when the rotor of the motor as a comparative example rotates. These three teeth have the same shape. Figure 13 In the graph, measurement point 1 is the upstream portion of the tooth tip of the center tooth among the three teeth. The maximum magnetic flux density at measurement point 1 is assumed to be 1. Measurement point 2 is the upstream portion of the tooth tip of the downstream tooth among the three teeth. The graph at measurement point 2 shows the ratio to the maximum magnetic flux density at measurement point 1. Measurement point 3 is the upstream portion of the tooth tip of the upstream tooth among the three teeth. The graph at measurement point 3 shows the ratio to the maximum magnetic flux density at measurement point 1.

[0114] like Figure 13 As shown, in this case, the magnetic flux density is largest at the upstream side portion of the tooth tip of the center tooth, and is smallest at the upstream side portion of the tooth tip of the downstream tooth.

[0115] Specifically, of the magnetic flux flowing into the three circumferentially adjacent teeth wound with coils forming the same phase, the largest amount flows into the center tooth. Of the magnetic flux flowing into the three circumferentially adjacent teeth wound with coils forming the same phase, the smallest amount flows into the downstream teeth. Consequently, an imbalance in magnetic flux density occurs between the center tooth and the downstream teeth. This imbalance causes noise during rotor rotation.

[0116] Figure 14 This is a graph showing the maximum value of the magnetic flux density at each measuring point on the tip of each of three circumferentially adjacent teeth wound with coils forming the same phase when the rotor of the motor as a comparative example rotates. Figure 14 In the test, points 1 to 3 are Figure 13 Corresponding to measurement points 1 to 3 in .

[0117] exist Figure 14 In the graph, the measurement point 4 is the downstream side portion of the tooth tip of the center tooth among the three teeth. The graph at the measurement point 4 is the ratio of the maximum value of the magnetic flux density at the measurement point 1. Figure 14 In the graph, the measurement point 5 is the downstream side portion of the tooth tip of the downstream tooth among the three teeth. The graph at the measurement point 5 is the ratio of the maximum value of the magnetic flux density at the measurement point 1. Figure 14In the graph, measurement point 6 is the downstream side portion of the tooth tip of the upstream tooth among the three teeth. The graph at measurement point 6 is the ratio of the maximum value of the magnetic flux density at measurement point 1 to that at measurement point 1.

[0118] In this embodiment, the relationship between the lengths TCR and TBR satisfies TCR > TBR. Therefore, the magnetic flux density of the second upstream portion 322a of the downstream tooth 312 increases during rotor 2 rotation. Consequently, the difference between the magnetic flux density of the second upstream portion 322a of the downstream tooth 312 and the magnetic flux density of the first upstream portion 321a of the center tooth 311 is reduced compared to the comparative example. As a result, the imbalance in magnetic flux density between the downstream tooth 312 and the center tooth 311 is reduced compared to the comparative example, reducing the noise generated during rotor 2 rotation.

[0119] When the relationship between lengths TCR and TBR satisfies TCR>TBR, the surface area of downstream teeth 312 around which coils 32 are wound increases. Therefore, more coils 32 can be wound around downstream teeth 312, reducing copper losses. Consequently, the efficiency of motor 1 can be improved.

[0120] like Figure 13 As shown, the magnetic flux density at the upstream portion of the tooth tip of the upstream tooth is greater than the magnetic flux density at the upstream portion of the tooth tip of the downstream tooth. Therefore, in this embodiment, the relationship between length TFR and length TBR satisfies TFR>TBR. Consequently, the magnetic flux density at the second upstream portion 322a of the downstream tooth 312 increases during rotor 2 rotation. Consequently, the difference between the magnetic flux density at the second upstream portion 322a of the downstream tooth 312 (i.e., measurement point 2) and the magnetic flux density at the third upstream portion 323a of the upstream tooth 313 (i.e., measurement point 3) is smaller than in the comparative example. As a result, the noise generated during rotor 2 rotation can be reduced compared to the comparative example.

[0121] like Figure 13 As shown, the magnetic flux density is highest at the upstream portion of the tooth tip of the center tooth (i.e., measurement point 1), second highest at the upstream portion of the tooth tip of the upstream tooth (i.e., measurement point 3), and lowest at the upstream portion of the tooth tip of the downstream tooth (i.e., measurement point 2). Therefore, in this embodiment, the relationship between lengths TCR, TFR, and TBR satisfies TCR > TFR > TBR. Consequently, the difference in magnetic flux density between the three teeth 311, 312, and 313 is smaller than in the comparative example. As a result, the noise generated during the rotation of the rotor 2 can be reduced compared to the comparative example.

[0122] like Figure 14As shown, the magnetic flux density at the downstream portion of the tooth tip (i.e., measuring point 4) is lower than the magnetic flux density at the upstream portion of the tooth tip (i.e., measuring point 1). Therefore, in this embodiment, the relationship between length TCR and length TCL satisfies TCR > TCL. Consequently, compared to the comparative example, the magnetic flux density at the first downstream portion 321b of the center tooth 311 during rotor 2 rotation increases. Consequently, compared to the comparative example, the difference between the magnetic flux density at the first downstream portion 321b and the magnetic flux density at the first upstream portion 321a of the center tooth 311 decreases. As a result, the noise generated during rotor 2 rotation can be reduced compared to the comparative example.

[0123] like Figure 14 As shown, in the downstream tooth, the magnetic flux density at the downstream portion of the tooth tip (i.e., measuring point 5) is lower than the magnetic flux density at the upstream portion of the tooth tip (i.e., measuring point 2). Therefore, in this embodiment, the relationship between length TBR and length TBL satisfies TBR>TBL. Consequently, compared to the comparative example, the magnetic flux density of the second downstream portion 322b of the downstream tooth 312 during rotor 2 rotation increases. Consequently, compared to the comparative example, the difference between the magnetic flux density of the second downstream portion 322b and the magnetic flux density of the second upstream portion 322a of the downstream tooth 312 is reduced. As a result, the noise generated during rotor 2 rotation can be reduced compared to the comparative example.

[0124] like Figure 14 As shown, the magnetic flux density at the downstream portion of the tooth tip (i.e., measuring point 6) on the upstream tooth is lower than the magnetic flux density at the upstream portion of the tooth tip (i.e., measuring point 3). Therefore, in this embodiment, the relationship between length TFR and length TFL satisfies TFR > TFL. Consequently, compared to the comparative example, the magnetic flux density of the third downstream portion 323b of the upstream tooth 313 during rotor 2 rotation increases. Consequently, compared to the comparative example, the difference between the magnetic flux density of the third downstream portion 323b and the magnetic flux density of the third upstream portion 323a on the upstream tooth 313 is reduced. As a result, the noise generated during rotor 2 rotation can be reduced compared to the comparative example.

[0125] like Figure 14 As shown, the magnetic flux density flowing into the downstream portion of the tooth tip is highest at the upstream tooth (i.e., measuring point 6), second highest at the downstream tooth (i.e., measuring point 5), and lowest at the center tooth (i.e., measuring point 4). Therefore, in this embodiment, the relationship between lengths TFL, TBL, and TCL satisfies TFL > TBL > TCL. Consequently, the difference in magnetic flux density between the three teeth 311, 312, and 313 is smaller than in the comparative example. As a result, the noise generated during the rotation of the rotor 2 can be reduced compared to the comparative example.

[0126] like Figure 14 As shown, the magnetic flux density is highest at the upstream portion of the center tooth (i.e., measuring point 1). The magnetic flux density then decreases in the order of the upstream portion of the upstream tooth (i.e., measuring point 3), the upstream portion of the downstream tooth (i.e., measuring point 2), the downstream portion of the upstream tooth (i.e., measuring point 6), the downstream portion of the downstream tooth (i.e., measuring point 5), and the downstream portion of the center tooth (i.e., measuring point 4). Therefore, in this embodiment, the relationship between lengths TCR, TFR, TBR, TFL, TBL, and TCL satisfies TCR > TFR > TBR > TFL > TBL > TCL. Consequently, the difference in magnetic flux density between the three teeth 311, 312, and 313 is smaller than in the comparative example. As a result, the noise generated during the rotation of the rotor 2 can be reduced compared to the comparative example.

[0127] When coil 32 is formed from a conductive wire having a diameter of D1, the relationship between length TCR, length TCL, and diameter D1 satisfies (TCR - TCL) ≥ D1. In this case, the relationship TCR > TCL is satisfied, and the surface area of central teeth 311, where the conductive wire can be wound, can be increased. As a result, the density of coils 32 in the slots can be increased, copper losses can be reduced, and the efficiency of motor 1 can be improved.

[0128] The relationship between length TCR, length TCL, and diameter D1 preferably satisfies (TCR - TCL) = D1. In this case, the space within the slots of stator 3 can be effectively utilized. In other words, coil 32 can be efficiently wound around center tooth 311. As a result, stator 3 can be miniaturized, improving the efficiency of motor 1.

[0129] When coil 32 is formed from a conductive wire having a diameter of D1, the relationship between length TBR, length TBL, and diameter D1 satisfies (TBR - TBL) ≥ D1. In this case, the relationship TBR > TBL is satisfied, and the surface area of downstream teeth 312, where the conductive wire can be wound, can be increased. As a result, the density of coils 32 in the slots can be increased, copper losses can be reduced, and the efficiency of motor 1 can be improved.

[0130] The relationship between length TBR, length TBL, and diameter D1 preferably satisfies (TBR - TBL) = D1. In this case, the space within the slots of stator 3 can be effectively used. In other words, coil 32 can be efficiently wound around downstream teeth 312. As a result, stator 3 can be miniaturized, improving the efficiency of motor 1.

[0131] When coil 32 is formed from a conductive wire having a diameter of D1, the relationship between length TFR, length TFL, and diameter D1 satisfies (TFR - TFL) ≥ D1. In this case, the relationship TFR > TFL is satisfied, and the surface area of upstream teeth 313, where the conductive wire can be wound, can be increased. As a result, the density of coils 32 in the slots can be increased, copper losses can be reduced, and the efficiency of motor 1 can be improved.

[0132] The relationship between length TFR, length TFL, and diameter D1 preferably satisfies (TFR - TFL) = D1. In this case, the space within the slots of stator 3 can be effectively used. In other words, coil 32 can be efficiently wound around upstream teeth 313. As a result, stator 3 can be miniaturized, improving the efficiency of motor 1.

[0133] Variation example.

[0134] Figure 15 This is a diagram showing another example of the stator core 31 .

[0135] In the modified example, in the xy plane, the central tooth 311, the downstream tooth 312, and the upstream tooth 313 are line-symmetrical about a center line L41 radially passing through the center of the central tooth 311. Therefore, the length TCR is equal to the length TCL, the length TBR is equal to the length TFL, and the length TBL is equal to the length TFR.

[0136] In this case, the structure of the front side of the stator core 31 is identical to the structure of the back side of the stator core 31. Therefore, during the motor manufacturing process, the motor can be manufactured without having to worry about the orientation of the stator core 31. For example, when placing the stator core 31 in a mold, the stator core 31 can be placed in the mold without having to worry about its orientation. As a result, work efficiency can be improved.

[0137] Implementation method 2.

[0138] Figure 16 This is a diagram schematically showing a fan 60 according to the second embodiment.

[0139] The fan 60 includes blades 61 and a motor 62. The fan 60 is also called a blower. The blades 61 are formed of, for example, polypropylene (PP) containing glass fiber.

[0140] Motor 62 is motor 1 of Embodiment 1. Blades 61 are fixed to the shaft of motor 62. Motor 62 drives blades 61. Specifically, motor 62 rotates blades 61. When motor 62 is driven, blades 61 rotate, generating airflow. This allows fan 60 to blow air.

[0141] In the fan 60 of the second embodiment, the motor 1 described in the first embodiment is applied to the motor 62 , and thus the same advantages as those described in the first embodiment can be obtained. In addition, the efficiency of the fan 60 can be improved.

[0142] Implementation method 3.

[0143] An air conditioner 50 (also referred to as a refrigeration air-conditioning device or a refrigeration cycle device) according to Embodiment 3 will be described.

[0144] Figure 17 This is a diagram schematically showing the configuration of an air conditioner 50 according to Embodiment 3.

[0145] The air conditioner 50 of Embodiment 3 includes an indoor unit 51 as a blower (first blower), refrigerant piping 52, and an outdoor unit 53 as a blower (second blower) connected to the indoor unit 51. For example, the outdoor unit 53 is connected to the indoor unit 51 via the refrigerant piping 52.

[0146] Indoor unit 51 includes a motor 51a (e.g., motor 1 in Embodiment 1); a blower 51b driven by motor 51a to blow air; and a housing 51c covering motor 51a and blower 51b. Blower 51b includes, for example, blades 51d driven by motor 51a. Blades 51d are fixed to the shaft of motor 51a, for example, to generate airflow.

[0147] The outdoor unit 53 includes: a motor 53a (for example, the motor 1 of embodiment 1); an air supply unit 53b; a compressor 54; a heat exchanger (not shown); and a housing 53c that covers the air supply unit 53b, the compressor 54, and the heat exchanger. The air supply unit 53b is driven by the motor 53a to supply air. The air supply unit 53b includes, for example, blades 53d, which are driven by the motor 53a. For example, the blades 53d are fixed to the shaft of the motor 53a and generate airflow. The compressor 54 includes: a motor 54a (for example, the motor 1 of embodiment 1); a compression mechanism 54b (for example, a refrigerant circuit) that is driven by the motor 54a; and a housing 54c that covers the motor 54a and the compression mechanism 54b.

[0148] In the air conditioner 50, at least one of the indoor unit 51 and the outdoor unit 53 includes the motor 1 described in Embodiment 1. That is, the indoor unit 51, the outdoor unit 53, or both the indoor unit 51 and the outdoor unit 53 include the motor 1 described in Embodiment 1. Specifically, at least one of the motors 51a and 53a uses the motor 1 described in Embodiment 1 as a drive source for the air supply unit. That is, the indoor unit 51, the outdoor unit 53, or both the indoor unit 51 and the outdoor unit 53 use the motor 1 described in Embodiment 1. The motor 1 described in Embodiment 1 can also be used for the motor 54a of the compressor 54.

[0149] The air conditioner 50 can perform air conditioning such as cooling operation in which cold air is delivered from the indoor unit 51, or heating operation in which warm air is delivered. In the indoor unit 51, the motor 51a is a driving source for driving the blower 51b. The blower 51b can deliver conditioned air.

[0150] In the indoor unit 51, the electric motor 51a is fixed to the housing 51c of the indoor unit 51 by screws, for example. In the outdoor unit 53, the electric motor 53a is fixed to the housing 53c of the outdoor unit 53 by screws, for example.

[0151] In the air conditioner 50 of Embodiment 3, the motor 1 described in Embodiment 1 is applied to at least one of the motors 51a and 53a, thereby achieving the same advantages as those described in Embodiment 1. As a result, the efficiency of the air conditioner 50 can be improved.

[0152] Furthermore, when the motor 1 of Embodiment 1 is used as a drive source for a blower (e.g., indoor unit 51), the same advantages as those described in Embodiment 1 can be achieved. Consequently, a decrease in the efficiency of the blower can be prevented. A blower having the motor 1 of Embodiment 1 and blades (e.g., blades 51d or 53d) driven by the motor 1 can be used independently as a device for blowing air. This blower can also be applied to equipment other than the air conditioner 50.

[0153] Furthermore, when the electric motor 1 of the first embodiment is used as a driving source for the compressor 54 , it is possible to obtain the same advantages as those described in the first embodiment. As a result, the efficiency of the compressor 54 can be improved.

[0154] The electric motor 1 described in the first embodiment can be mounted on a device having a drive source, such as a ventilation fan, a home appliance, or a machine tool, in addition to the air conditioner 50 .

[0155] The features of each embodiment and the features of each modification described above can be combined with each other.

[0156] Label Description

[0157] 1. 51a, 53a, 54a, 62: electric motor; 2: rotor; 3: stator; 21: resin; 22: permanent magnet; 31: stator core; 31a: core back; 31b: tooth; 32: coil; 311: central tooth; 311a: first main body; 311b: first tooth front end; 312: downstream tooth; 312a: second main body; 312b: second tooth front end; 313: upstream tooth; 313a: third main body; 313b: third tooth front end; 321a: first upstream portion; 321b: first downstream portion; 322a: second upstream portion; 322b: second downstream portion; 323a: third upstream portion; 323b: third downstream portion.

Claims

1. An electric motor, wherein: The electric motor has: a rotor having 10×N magnetic poles, where N is an integer greater than or equal to 1; and A stator having: an annular core back; 9×N teeth extending from the annular core back toward the rotor; and a 3-phase coil wound around the 9×N teeth in a concentrated winding manner, The three-phase coils are wound around the 9×N teeth so that the three-phase coils wound around three circumferentially adjacent teeth among the 9×N teeth form the same phase. The central tooth located in the center of the three teeth around which the three-phase coil forming the same phase is wound has: a first main body portion extending from the annular core back toward the rotor; and a first tooth front end portion, which is located at the end of the central tooth and extends along the circumferential direction; The first tooth tip portion includes a first upstream portion located upstream in the rotational direction of the rotor and a first downstream portion located downstream in the rotational direction. The downstream side tooth located on the downstream side in the rotation direction among the three teeth has: a second main body portion extending from the annular core back toward the rotor; and a second tooth front end portion, which is located at the end of the downstream side tooth and extends along the circumferential direction; The second tooth tip portion includes a second upstream portion located on the upstream side in the rotation direction and a second downstream portion located on the downstream side in the rotation direction. In a plane perpendicular to the axial direction, a direction parallel to a first upstream straight line passing through a boundary between the first main body portion and the first upstream portion and the rotation center of the rotor is defined as a first upstream radial direction. In the plane, a direction parallel to a second upstream straight line passing through a boundary between the second main body portion and the second upstream portion and the rotation center is defined as a second upstream radial direction. In the plane, let the maximum length of the first upstream portion in the first upstream radial direction be TCR, and let the maximum length of the second upstream portion in the second upstream radial direction be TBR. In this case, Satisfies TCR>TBR.

2. The electric motor according to claim 1, wherein The upstream side tooth located on the upstream side in the rotation direction among the three teeth has: a third main body portion extending from the annular core back portion toward the rotor; and a third tooth front end portion, which is located at the end of the upstream tooth and extends along the circumferential direction; The third tooth tip portion includes: a third upstream portion located on the upstream side in the rotation direction; and a third downstream portion located on the downstream side in the rotation direction. In the plane, a direction parallel to a third upstream straight line is defined as a third upstream radial direction, wherein the third upstream straight line passes through a boundary between the third main body portion and the third upstream portion and the rotation center. In the plane, let the maximum length of the third upstream portion in the third upstream radial direction be TFR. In this case, Satisfy TFR>TBR.

3. The electric motor according to claim 1, wherein The upstream side tooth located on the upstream side in the rotation direction among the three teeth has: a third main body portion extending from the annular core back portion toward the rotor; and a third tooth front end portion, which is located at the end of the upstream tooth and extends along the circumferential direction; The third tooth tip portion includes: a third upstream portion located on the upstream side in the rotation direction; and a third downstream portion located on the downstream side in the rotation direction. In the plane, a direction parallel to a third upstream straight line is defined as a third upstream radial direction, wherein the third upstream straight line passes through a boundary between the third main body portion and the third upstream portion and the rotation center. In the plane, let the maximum length of the third upstream portion in the third upstream radial direction be TFR. In this case, Satisfies TCR>TFR>TBR.

4. The electric motor according to any one of claims 1 to 3, wherein In the plane, a direction parallel to a first downstream straight line is defined as a first downstream radial direction, wherein the first downstream straight line passes through a boundary between the first main body portion and the first downstream portion and the rotation center. In the plane, let the maximum length of the first downstream portion in the first downstream radial direction be TCL. In this case, Meet TCR>TCL.

5. The electric motor according to any one of claims 1 to 3, wherein In the plane, a direction parallel to a second downstream straight line is defined as a second downstream radial direction, wherein the second downstream straight line passes through a boundary between the second main body portion and the second downstream portion and the rotation center. In the plane, the maximum length of the second downstream portion in the second downstream radial direction is TBL. In this case, Satisfies TBR>TBL.

6. The electric motor according to claim 2 or 3, wherein: In the plane, a direction parallel to the third downstream side straight line is defined as a third downstream side radial direction, wherein the third downstream side straight line passes through the boundary between the third main body portion and the third downstream side portion and the rotation center. In the plane, let the maximum length of the third downstream portion in the third downstream radial direction be TFL. In this case, Satisfies TFR>TFL.

7. The electric motor according to any one of claims 1 to 6, wherein The three-phase coil is formed by a wire with a diameter of D1. In the plane, a direction parallel to a first downstream straight line is defined as a first downstream radial direction, wherein the first downstream straight line passes through a boundary between the first main body portion and the first downstream portion and the rotation center. In the plane, let the maximum length of the first downstream portion in the first downstream radial direction be TCL. In this case, Satisfy (TCR-TCL)≥D1.

8. The electric motor according to any one of claims 1 to 7, wherein The three-phase coil is formed by a wire with a diameter of D1. In the plane, a direction parallel to a second downstream straight line is defined as a second downstream radial direction, wherein the second downstream straight line passes through a boundary between the second main body portion and the second downstream portion and the rotation center. In the plane, the maximum length of the second downstream portion in the second downstream radial direction is TBL. In this case, Satisfy (TBR-TBL)≥D1.

9. The electric motor according to claim 2 or 3, wherein: The three-phase coil is formed by a wire with a diameter of D1. In the plane, a direction parallel to the third downstream side straight line is defined as a third downstream side radial direction, wherein the third downstream side straight line passes through the boundary between the third main body portion and the third downstream side portion and the rotation center. In the plane, let the maximum length of the third downstream portion in the third downstream radial direction be TFL. In this case, Satisfy (TFR-TFL)≥D1.

10. The electric motor according to claim 1, wherein The upstream side tooth located on the upstream side in the rotation direction among the three teeth has: a third main body portion extending from the annular core back portion toward the rotor; and a third tooth front end portion, which is located at the end of the upstream tooth and extends along the circumferential direction; The third tooth tip portion includes: a third upstream portion located on the upstream side in the rotation direction; and a third downstream portion located on the downstream side in the rotation direction. In the plane, a direction parallel to a first downstream straight line is defined as a first downstream radial direction, wherein the first downstream straight line passes through a boundary between the first main body portion and the first downstream portion and the rotation center. In the plane, a direction parallel to a second downstream straight line is defined as a second downstream radial direction, wherein the second downstream straight line passes through a boundary between the second main body portion and the second downstream portion and the rotation center. In the plane, a direction parallel to the third downstream side straight line is defined as a third downstream side radial direction, wherein the third downstream side straight line passes through the boundary between the third main body portion and the third downstream side portion and the rotation center. In the plane, let the maximum length of the first downstream side portion in the first downstream side radial direction be TCL, in the plane, let the maximum length of the second downstream side portion in the second downstream side radial direction be TBL, in the plane, let the maximum length of the third downstream side portion in the third downstream side radial direction be TFL. In this case, Satisfies TFL>TBL>TCL.

11. The electric motor according to claim 10, wherein Satisfies TCR>TFR>TBR>TFL>TBL>TCL.

12. The electric motor according to claim 1, wherein In the plane, the three teeth are line-symmetrical about a center line passing through the center of the central tooth in the radial direction.

13. A fan, wherein: The fan has: blades; and The electric motor according to any one of claims 1 to 12, which drives the blades.

14. An air conditioner, wherein: The air conditioner comprises: indoor unit; and an outdoor unit connected to the indoor unit, The indoor unit, the outdoor unit, or both the indoor unit and the outdoor unit include the electric motor according to any one of claims 1 to 12.

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