Motor

Abstract

The purpose of the present disclosure is to achieve improvement in motor performance. A motor (1) comprises a stator (2) and a first rotor (R1). The first rotor (R1) has a permanent magnet (P1), is disposed so as to face the stator (2), and rotates about a rotary axis (L1). The stator (2) has a plurality of stator cores (3) arranged in an annular shape along a circumferential direction (A2) of the rotary axis (L1). The plurality of stator cores (3) each have a plurality of core pieces (4) and an armature coil (5) wound around the plurality of core pieces (4). The plurality of core pieces (4) each have an asymmetric shape in the axial direction (first direction A1) of the rotary axis (L1).

Description

[Technical field]

[0001] The present disclosure relates generally to a motor, and more particularly to a permanent magnet synchronous motor having a rotor provided with a permanent magnet. [Background technology]

[0002] Patent Document 1 discloses an axial gap type rotating electric machine. This rotating electric machine has a stator, a rotor, a variable gap mechanism, and a housing. The stator includes a plurality of coils arranged in the circumferential direction around the axis, and a stator core arranged inside the coil, and is held by the housing. The rotor has the axis as a rotating shaft, a plurality of permanent magnets arranged in the circumferential direction around the axis, and a rotor core, and is arranged so as to sandwich the stator from the axial direction. According to this rotating electric machine, the variable gap mechanism moves the rotor in the axial direction by a power source different from the rotational force of the rotating electric machine, thereby making it possible to change the width of the air gap.

[0003] However, in a rotating electric machine (motor), the induced voltage waveform is distorted due to the superposition of harmonic components, and the deviation from an ideal sine wave increases, which may result in a decrease in motor performance. Therefore, further improvement in motor performance is desired. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2012-130086 A Summary of the Invention

[0005] The present disclosure has been made in consideration of the above circumstances, and has an object to provide a motor that can improve motor performance.

[0006] A motor according to one aspect of the present disclosure includes a stator and a rotor. The rotor has a permanent magnet, is disposed opposite the stator, and rotates about a rotation shaft. The stator has a plurality of stator cores disposed in an annular shape along the circumferential direction of the rotation shaft, and a plurality of armature coils wound around the plurality of stator cores, respectively. Each of the plurality of stator cores has a plurality of core pieces. Each of the plurality of core pieces has an asymmetric shape in the axial direction of the rotation shaft. The core pieces each have a plurality of extending portions that extend in a direction perpendicular to the axial direction as viewed along the radial direction of the rotation shaft, and the core pieces of each of the stator cores have a step portion where at least one of the extending portions of adjacent stator cores in the circumferential direction is arranged in contact with each other. [Brief description of the drawings]

[0007] [Figure 1] 1A and 1B are perspective views of a motor according to an embodiment of the present invention with a second rotor removed; [Diagram 2] FIG. 2 is a side view of the motor. [Diagram 3] FIG. 3 is a perspective view of one of the stator cores in the motor. [Figure 4] FIG. 4 is a perspective view of the stator core excluding the armature coil. [Diagram 5] FIG. 5 is an exploded perspective view of three core pieces in the stator core of the above embodiment. [Figure 6] FIG. 6 is a partial cross-sectional perspective view of the motor. [Figure 7] 7A and 7B are diagrams for explaining the difference in magnetic flux density between a motor of a comparative example and the above motor. [Figure 8] FIG. 8 is an external view of a ceiling fan equipped with the above motor. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] (Embodiment) Hereinafter, a motor 1 according to an embodiment will be described with reference to FIGS. 1A to 8. FIG.

[0009] (1) Overview As shown in FIGS. 1A, 1B, and 2, a motor 1 according to this embodiment includes a stator 2 and a rotor (first rotor R1).

[0010] The first rotor R1 has a permanent magnet P1, is disposed opposite the stator 2, and rotates about the rotation axis L1. Here, the first rotor R1 and the stator 2 face each other in the axial direction of the rotation axis L1 (hereinafter sometimes referred to as the "first direction A1") via an air gap (first gap G1) as shown in FIG. 2. In other words, the motor 1 according to this embodiment is a so-called axial gap type motor. However, the motor 1 may also be a radial gap type motor. The rotation axis L1 here is a virtual axis passing through the central axis of the shaft 6 (shaft portion).

[0011] The stator 2 has a plurality of stator cores 3 arranged in an annular shape along the circumferential direction of the rotation axis L1 (hereinafter sometimes referred to as the "second direction A2"), and a plurality of armature coils 5 wound around the stator cores 3, respectively. As shown in FIG. 3, each of the plurality of stator cores 3 has a plurality of core pieces 4. As shown in FIG. 5, each of the plurality of core pieces 4 has an asymmetric shape in the axial direction (first direction A1) of the rotation axis L1. As an example, in this embodiment, the number of stator cores 3 is 12. As another example, the plurality of core pieces 4 is composed of three core pieces 4. The numbers of the stator cores 3 and the core pieces 4 are not limited to the above numbers.

[0012] According to this configuration, each of the core pieces 4 has an asymmetric shape in the axial direction (first direction A1) of the rotation axis L1, which suppresses the saturation state of the core in the motor 1, thereby reducing the proportion of harmonics (e.g., third harmonics), and thus improving the motor performance.

[0013] (2) Details As described above, the motor 1 of this embodiment is an axial gap type motor. As shown in Fig. 8, the motor 1 is a motor used in, for example, a ceiling fan 100. The axial gap type motor 1 is easier to make smaller (particularly thinner) than a radial gap type motor, and is easily applied to devices such as the ceiling fan 100 where a thin design for aesthetic appearance is desired.

[0014] As shown in FIGS. 1A, 1B, 2 and 6, the motor 1 includes a stator 2, a pair of rotors (a first rotor R1 and a second rotor R2), a shaft 6, and a pair of bearings 7, 8 (bearing portions).

[0015] In this embodiment, the first rotor R1 and the second rotor R2 are arranged in the axial direction (first direction A1) with the stator 2 interposed therebetween. That is, here, the motor 1 is, as an example, a double-rotor axial gap motor.

[0016] For the sake of convenience, the following description may refer to the side of the first rotor R1 relative to the stator 2 as the lower side, and the side of the second rotor R2 relative to the stator 2 as the upper side. In other words, the first direction A1 corresponds to the up-down direction. However, this definition of the up-down direction is not intended to limit the manner in which the motor 1 is used.

[0017] The stator 2 has twelve stator cores 3 arranged annularly along the circumferential direction of the rotation axis L1, i.e., the second direction A2, and twelve coils (armature coils 5) wound around the twelve stator cores 3. The stator 2 further has a holding portion H1 and an outer ring J1.

[0018] As shown in FIG. 3, each stator core 3 has a plurality of (three here) core pieces 4. The plurality of core pieces 4 are arranged along the radial direction of the rotation axis L1 (hereinafter, sometimes referred to as the "third direction A3" (see FIG. 1A)). Three core pieces 4 form one tooth T1 (see FIGS. 3 to 5). In the following, in order to distinguish the three core pieces 4 from one another, they may be referred to as the first core piece 41, the second core piece 42, and the third core piece 43, respectively. The first core piece 41, the second core piece 42, and the third core piece 43 are arranged in this order in a direction (outward) away from the rotation axis L1 in the radial direction (third direction A3). That is, the first core piece 41 is closest to the rotation axis L1 among the three core pieces 4, and the third core piece 43 is located at a position farthest from the rotation axis L1 among the three core pieces 4.

[0019] The first core laminations 41 and the second core laminations 42 are in contact with each other in the third direction A3. The second core laminations 42 and the third core laminations 43 are in contact with each other in the third direction A3.

[0020] 5, each core piece 4 has an overall shape resembling a letter H rotated approximately 90 degrees when viewed along the radial direction (third direction A3) of the rotation axis L1. The dimensions of the three core pieces 4 in the first direction A1 are approximately equal to each other. However, the shapes of the core pieces 4 are different from each other.

[0021] Each core piece 4 is formed by laminating a plurality of laminated steel plates made of soft magnetic material such as electromagnetic steel plates in one direction. The lamination direction of the plurality of laminated steel plates is, for example, parallel to a first direction A1 (see FIG. 5).

[0022] More specifically, each core piece 4 has a standing portion 401 (first portion), a tip portion 402 (second portion), and a base portion 403 (third portion) as shown in Fig. 5. In Fig. 5, a direction perpendicular to the first direction A1 and the third direction A3 is sometimes referred to as a "fourth direction A4".

[0023] 5, the standing portion 401 has a rectangular prism shape extending along the first direction A1. The standing portion 401 connects the tip end 402 and the base end 403 so as to maintain the tip end 402 and the base end 403 facing each other in the first direction A1.

[0024] As described below, the standing portion 401 is a portion around which the armature coil 5 is mainly wound. In other words, the dimension of the standing portion 401 in the first direction A1 is substantially equal to the dimension of the armature coil 5 in the first direction A1.

[0025] The dimensions of the standing portions 401 of the three core pieces 4 in the first direction A1 are slightly different due to slight differences in the thicknesses of the tip portions 402 of the three core pieces 4. The dimensions of the standing portions 401 of the three core pieces 4 in the third direction A3 are generally equal to one another. The dimensions of the standing portions 401 of the three core pieces 4 in the fourth direction A4 are different from one another, with the dimensions increasing in the order of the first core piece 41, the second core piece 42, and the third core piece 43 (the first core piece 41 has the smallest dimension in this order).

[0026] The standing portions 401 of the three core pieces 4 are aligned along the third direction A3. Each of the standing portions 401 of the three core pieces 4 is in contact with the adjacent standing portions 401.

[0027] The tip portion 402 has a substantially rectangular plate shape as shown in Figs. 3 to 5. The tip portion 402 is a portion located on the upper side of the standing portion 401. The tip portion 402 is disposed with its thickness direction facing the first direction A1. The tip portion 402 is a portion facing the second rotor R2. In particular, the tip portion 402 faces the second rotor R2 via an air gap (second gap G2).

[0028] The tip portions 402 extend away from the standing portion 401 to both the left and right in the fourth direction A4. The tip portions 402 of the three core pieces 4 are aligned along the third direction A3. Each of the tip portions 402 of the three core pieces 4 is in contact with the adjacent tip portions 402.

[0029] Here, the multiple core pieces 4 in this embodiment have multiple extension portions 40 that respectively extend in a direction (fourth direction A4) perpendicular to the axial direction (first direction A1) when viewed along the radial direction (third direction A3) of the rotation axis L1. Here, as an example, a portion of the tip portion 402 that extends further to the right than the standing portion 401 when viewed along the third direction A3 corresponds to the extension portion 40. In other words, the extension portion 40 is a portion of the tip portion 402 that extends clockwise from the standing portion 401 when the twelve stator cores 3 arranged in an annular shape are viewed from above (see FIGS. 1B and 6).

[0030] In this embodiment, the dimensions of the multiple extension portions 40 in the axial direction (first direction A1) of each stator core 3 are different from one another (see FIG. 5). That is, the thicknesses of the extension portions 40 of the three core pieces 4 are different from one another.

[0031] Specifically, the extending portion 40 of the second core laminations 42 has a generally constant thickness across both ends in the fourth direction A4. However, the extending portion 40 of the first core laminations 41 has a step on its lower surface, and the thickness is not constant across both ends in the fourth direction A4. That is, the extending portion 40 of the first core laminations 41 has a portion near the upright portion 401 where the thickness is greater than that of the extending portion 40 of the second core laminations 42. Also, the extending portion 40 of the third core laminations 43 is approximately twice as thick as the extending portion 40 of the second core laminations 42.

[0032] As such, there are differences in thickness among the extension portions 40 of the three core pieces 4, but the upper surfaces of the extension portions 40 of the three core pieces 4 are arranged so as to be roughly flush (see Figures 1B, 3, 4 and 6).

[0033] The lengths (dimension in the fourth direction A4) of the extending portions 40 of the first core laminations 41 and the second core laminations 42 are approximately equal. On the other hand, the length of the extending portion 40 of the third core laminations 43 is shorter than the lengths of the extending portions 40 of the first core laminations 41 and the second core laminations 42.

[0034] As shown in Fig. 3, the tips of the extension portions 40 of the three core laminations 4 all protrude outward beyond the armature coil 5. However, the amount of protrusion of the extension portions 40 from the armature coil 5 differs among the three core laminations 4. Specifically, the tip of the extension portion 40 of the second core lamination 42 is disposed in a manner that protrudes beyond the tip of the extension portion 40 of the first core lamination 41 (see Figs. 3 and 4). Moreover, the tip of the extension portion 40 of the third core lamination 43 is disposed in a manner that recedes rearward beyond the tips of the extension portions 40 of the first core lamination 41 and the second core lamination 42 (see Figs. 3 and 4).

[0035] In this embodiment, each of the multiple (here, three) core pieces 4 of the multiple (here, twelve) stator cores 3 has a step portion 410 (see Figs. 3 to 5) where at least one of the multiple extension portions 40 of the stator cores 3 adjacent in the circumferential direction (second direction A2) is in contact with and arranged. Specifically, the surface of the tip portion 402 of each core piece 4 opposite to the extension portion 40 in the fourth direction A4 is recessed in the direction approaching the base end portion 403. Here, among the extension portions 40 of the three core pieces 4, the extension portions 40 of the first core piece 41 and the second core piece 42 contact the step portions 410 of the three core pieces 4 of the adjacent stator core (see Figs. 1B and 6). The extension portion 40 of the third core piece 43 does not rest on the step portions 410 of the three core pieces 4 of the adjacent stator core because the protruding amount is small.

[0036] In short, the extensions 40 of the two core pieces 4 of the twelve stator cores 3 arranged in an annular shape are in contact with the step 410 of the stator core 3 adjacent in the clockwise direction, so that the surfaces of the extensions 40 of the twelve stator cores 3 are substantially flush with each other. Therefore, when viewed as a whole, the extensions 40 of the twelve stator cores 3 have a shape that is connected as if they were a single annular core.

[0037] As shown in Figs. 3 to 5, the base end 403 is in the shape of a substantially rectangular plate. The base end 403 is a portion located below the standing portion 401. The base end 403 is disposed such that its thickness direction faces the first direction A1. The base end 403 is a portion facing the first rotor R1. In particular, the base end 403 faces the permanent magnet P1 of the first rotor R1 via an air gap (first gap G1).

[0038] The base end portions 403 extend away from the standing portion 401 to both the left and right in the fourth direction A4. The base end portions 403 of the three core pieces 4 are aligned along the third direction A3. Each of the base end portions 403 of the three core pieces 4 is in contact with the adjacent base end portions 403.

[0039] The base ends 403 of the three core laminations 4 have different dimensions (lengths) in the fourth direction A4, and as an example here, the dimensions increase in the order of the first core lamination 41, the second core lamination 42, and the third core lamination 43 (the first core lamination 41 has the smallest dimension). The base ends 403 of the three core laminations 4 have substantially the same dimensions (thicknesses) in the first direction A1, and substantially the same dimensions (widths) in the third direction A3.

[0040] The bottom surfaces of the base ends 403 of the three core laminations 4 are arranged to be generally flush. Both longitudinal ends of the base ends 403 of the three core laminations 4 all protrude outward beyond the armature coil 5. However, the amount of protrusion of the base ends 403 from the armature coil 5 is smaller than the amount of protrusion of the tip ends 402.

[0041] In each core piece 4, the tip end 402 has a longer dimension in the fourth direction A4 than the base end 403. That is, each core piece 4 has an asymmetric shape in the up-down direction when viewed along the third direction A3. In addition, each core piece 4 has an asymmetric shape in the left-right direction (fourth direction A4) when viewed along the third direction A3 because a step portion 410 or the like is provided.

[0042] As can be seen from the above description, each core piece 4 in this embodiment has an asymmetric shape in the axial direction (first direction A1, i.e., the up-down direction) of the rotation axis L1. Each of the core pieces 4 also has an asymmetric shape in the direction perpendicular to the axial direction (first direction A1) when viewed along the radial direction (third direction A3) of the rotation axis L1.

[0043] Each stator core 3 further has an insulating portion K1 (see FIG. 4) having electrical insulation properties. The insulating portion K1 is, for example, a resin member. The first core laminations 41, the second core laminations 42, and the third core laminations 43 are bundled together so as to be covered by the insulating portion K1 in a manner in which the adjacent core laminations 4 are in contact with each other. In particular, the insulating portion K1 covers the upright portions 401 of the three core laminations 4, and the tip end portions 402 and base end portions 403 are disposed outside the insulating portion K1.

[0044] Each armature coil 5 is wound around a corresponding tooth T1 of the stator core 3. Here, each armature coil 5 is wound around the tooth T1 so as to cover the surface of the insulating portion K1. That is, each armature coil 5 covers the standing portion 401 via the insulating portion K1, and the tip end 402 and base end 403 are disposed outside the armature coil 5.

[0045] The armature coils 5 are connected, for example, in a three-phase Y-connection (star connection). A driving circuit including an inverter circuit or the like supplies the 12 armature coils 5 with three-phase (U-phase, V-phase, W-phase) rectified AC current (driving current) at a predetermined timing, causing a pair of rotors (first rotor R1 and second rotor R2) to rotate relative to the stator 2. That is, when the armature coils 5 are energized, the corresponding stator core 3 is excited, and the stator 2 generates a magnetic field. This magnetic field attracts or repels a magnetic field generated by a permanent magnet P1 of the first rotor R1, which will be described later, causing the first rotor R1 to rotate around the rotation axis L1. The second rotor R2 is physically connected to the first rotor R1 via a connecting member formed, for example, of aluminum die casting, and rotates around the rotation axis L1 together with the rotation of the first rotor R1. Note that the second rotor R2 may also be provided with a permanent magnet, in which case the connecting member may be omitted.

[0046] The holding portion H1 is configured to hold a plurality of stator cores 3 on the shaft 6. Specifically, as shown in Fig. 1B and Fig. 6, the holding portion H1 has a center plate H10 and twelve spokes H11.

[0047] The center plate H10 has a disk shape. The center plate H10 has a through hole penetrating in the thickness direction at the center thereof, and the shaft 6 is inserted through the through hole.

[0048] The twelve spokes H11 extend radially from the center plate H10 along the radial direction of the rotation axis L1 (third direction A3). Each of the twelve spokes H11 has a rectangular column shape. The twelve spokes H11 extend toward the twelve stator cores 3 in a one-to-one correspondence manner, and are configured to connect the twelve stator cores 3 to the center plate H10. The tip of each spoke H11 is fixed to, for example, the first core piece 41 of the tooth T1 of the corresponding stator core 3.

[0049] The holding portion H1 is fixed to the shaft 6. In other words, the stator 2 is fixed to the shaft 6 which is held in a housing that accommodates the motor 1. That is, in the present embodiment, as an example, even if a driving current is supplied from the driving circuit to the armature coil 5, the shaft 6 does not rotate, and the first rotor R1 and the second rotor R2 rotate relative to the stator 2 and the shaft 6 via a pair of bearings 7, 8.

[0050] The outer ring J1 is configured to position the multiple stator cores 3. The outer ring J1 is generally in a flat lattice shape in the axial direction (first direction A1) of the rotation axis L1. Specifically, as shown in Fig. 1B and Fig. 6, the outer ring J1 has a pair of annular portions J10 and multiple (four here) column portions J11.

[0051] Each annular portion J10 is a dodecagonal annular portion as viewed along the first direction A1. A pair of annular portions J10 face each other in the first direction A1 and are disposed in such a manner that the twelve stator cores 3 are sandwiched between them. Each annular portion J10 is disposed such that the twelve small piece portions J13 (see FIGS. 1B and 6) corresponding to the sides of the dodecagon correspond one-to-one to the twelve stator cores 3.

[0052] As an example, each small piece portion J13 of the upper annular portion J10 of the pair of annular portions J10 is fixed to the outer surface of the tip end portion 402 of the third core lamination 43 of the corresponding stator core 3. Also, each small piece portion J13 of the lower annular portion J10 of the pair of annular portions J10 is fixed to the outer surface of the base end portion 403 of the third core lamination 43 of the corresponding stator core 3.

[0053] The four pillar portions J11 are columnar portions extending along the first direction A1. The four pillar portions J11 connect the pair of annular portions J10 to each other in the first direction A1. The dimension (length) of each pillar portion J11 in the first direction A1 is slightly larger than the dimension of the armature coil 5 in the first direction A1.

[0054] Each armature coil 5 is disposed so as to protrude slightly outward from each annular portion J10 (see FIG. 1B and FIG. 6).

[0055] The shaft 6 is a hollow cylinder with both upper and lower ends open. The central axis of the shaft 6 coincides with the rotation axis L1. The shaft 6 holds the stator 2, the first rotor R1, the second rotor R2, and bearings 7 and 8.

[0056] 1A, 1B, and 2, the first rotor R1 has a permanent magnet P1 and a retaining plate R10. The first rotor R1 is a rotor disposed below the stator 2. The first rotor R1 is disposed opposite the stator 2, and rotates about a rotation axis L1.

[0057] The permanent magnet P1 is thin and doughnut-shaped. The permanent magnet P1 has a diameter substantially equal to the diameter of the outer ring J1 of the stator 2. The central axis of the permanent magnet P1 coincides with the central axis of the stator 2. An insertion hole is provided in the center of the permanent magnet P1, and the shaft 6 is inserted into the insertion hole. The permanent magnet P1 is, for example, a one-sided multi-pole magnetized type. The upper surface of the permanent magnet P1 is magnetized with N poles and S poles alternately along the circumferential direction. The upper surface of the permanent magnet P1 faces the stator 2 via a first gap G1. The first rotor R1 having the permanent magnet P1 rotates by being attracted or repelled by the magnetic field generated by the stator 2.

[0058] The retaining plate R10 holds the permanent magnet P1 on its upper surface. The retaining plate R10 is disk-shaped. The central axis of the retaining plate R10 coincides with the rotation axis L1. The retaining plate R10 has a diameter larger than the diameters of the stator 2 and the permanent magnet P1. The retaining plate R10 is made of, for example, a soft magnetic material.

[0059] The retaining plate R10 has a housing portion R11 (see FIG. 2) in its center for housing the bearing 7. The housing portion R11 is formed by recessing the center of the retaining plate R10 downward. The housing portion R11 has a hole for leading out the lower end of the shaft 6 downward with the shaft 6 inserted and fixed in the inner ring of the bearing 7. The outer ring of the bearing 7 is fixed in the housing portion R11. Therefore, the retaining plate R10 and the permanent magnet P1 are rotatable relative to the shaft 6 via the bearing 7.

[0060] The second rotor R2 is a rotor disposed above the stator 2. The second rotor R2 is disk-shaped. The central axis of the second rotor R2 coincides with the rotation axis L1. The second rotor R2 has a diameter larger than that of the stator 2. The second rotor R2 is formed, for example, from a soft magnetic material. The second rotor R2 has approximately the same shape and dimensions as the retaining plate R10 of the first rotor R1. The second rotor R2 is formed, for example, from a common member with the retaining plate R10.

[0061] The second rotor R2 is disposed with its lower surface facing the stator 2 via the second gap G2, and rotates about the rotation axis L1. Unlike the first rotor R1, the second rotor R2 does not have a permanent magnet. In this embodiment, as described above, the second rotor R2 is physically connected to the first rotor R1 via a connecting member made of aluminum die casting, and rotates integrally with the first rotor R1.

[0062] The second rotor R2 has a housing portion R21 (see FIG. 2) in its center for housing the bearing 8. The housing portion R21 is formed by recessing the center of the second rotor R2 upward. The housing portion R21 has a hole for leading out the upper end of the shaft 6 upward with the shaft 6 inserted and fixed in the inner ring of the bearing 8. The outer ring of the bearing 8 is fixed in the housing portion R21. Therefore, the second rotor R2 is rotatable relative to the shaft 6 via the bearing 8.

[0063] The multiple blades 101 (see FIG. 8) of the ceiling fan 100 are attached to a connecting member made, for example, of die-cast aluminum that connects the first rotor R1 and the second rotor R2, and rotate in conjunction with the rotation of the first rotor R1 and the second rotor R2.

[0064] (3) Harmonics of induced voltage Hereinafter, the advantages of the motor 1 of this embodiment will be described from the viewpoint of harmonics of the induced voltage.

[0065] In a permanent magnet synchronous motor, in which a permanent magnet is provided in the rotor, an induced voltage proportional to the rotor rotation speed, etc. is generated when the rotor rotates. In particular, the induced voltage of, for example, the U-phase may be superimposed with a third harmonic, which has a significantly larger amplitude than the second harmonic or the fourth or higher harmonics.

[0066] Such superposition of third harmonics distorts the induced voltage waveform, causing it to deviate more from an ideal sine wave. The above-mentioned distortion of the induced voltage waveform also causes distortion of the current waveform, making it difficult to supply drive current to the motor 1. For example, in sensorless control, parameters such as phase voltage and current are measured to estimate the rotor angle and speed, but the above-mentioned distortion of the induced voltage waveform creates errors in the estimation of the rotor angle and speed. The distortion of the induced voltage waveform can also cause high vibration and high noise in the motor 1. Therefore, in order to improve motor performance, it is desirable to suppress the distortion of the induced voltage waveform.

[0067] Here, the inventors prepared a motor 1X (see FIG. 7A) as a comparative example and verified the distribution of magnetic flux density between the motor 1 of this embodiment and the motor 1X. With some exceptions, the configuration of the motor 1X is generally the same as the configuration of the motor 1. In the following, for the motor 1X, components that are substantially the same as those of the motor 1 may be given the same reference symbols as those of the motor 1, and descriptions thereof may be omitted as appropriate.

[0068] FIG. 7A shows the distribution of magnetic flux density for motor 1X of a comparative example (in FIG. 7A, only approximately the front half is shown). FIG. 7B shows the distribution of magnetic flux density for motor 1 of this embodiment. In FIGS. 7A and 7B, darker areas are areas with relatively lower magnetic flux density, and lighter areas are areas with relatively higher magnetic flux density (shown in grayscale, and white areas are not necessarily areas with the highest magnetic flux density). Note that in FIGS. 7A and 7B, the coil 5, second rotor R2, shaft 6, bearings 7, 8, etc. are not shown.

[0069] 7A, the motor 1X includes a stator 2X and a first rotor R1 having a permanent magnet P1. The stator 2X includes a plurality of stator cores 3X and an annular core T2X (only half of which is shown in FIG. 7A). In other words, the motor 1X includes an annular core T2X that does not exist in the motor 1.

[0070] The annular core T2X is made of a zinc-plated steel plate. The annular core T2X is disposed on the multiple stator cores 3X. That is, the annular core T2X faces the second rotor R2 (not shown in FIG. 7A) via a second gap G2 (not shown in FIG. 7A).

[0071] Each stator core 3X has three core pieces 4X that form teeth T1X. All three core pieces 4X are H-shaped and have the same shape. In particular, unlike the core pieces 4 of the motor 1, each core piece 4X has a symmetrical shape in the first direction A1 (vertical direction) and also has a symmetrical shape in the fourth direction A4.

[0072] As can be seen by comparing the magnetic flux density distributions of motor 1 and motor 1X, which have different configurations, in motor 1X there are regions X1-X5 where the magnetic flux density is locally very high. It is believed that a saturated state (magnetic saturation) of the core occurs in such regions X1-X5. When magnetic saturation occurs in the core, it is believed that the proportion of third harmonics increases. On the other hand, in FIG. 7B, which shows the magnetic flux density distribution of motor 1, there are no regions where the magnetic flux density is locally very high. In other words, it can be said that motor 1 has a structure in which magnetic saturation is less likely to occur than motor 1X.

[0073] The motor 1 of this embodiment has a unique structure, unlike the motor 1X. That is, in the motor 1 of this embodiment, each stator core 3 has a plurality of core pieces 4, and each core piece 4 has an asymmetric shape in the first direction A1 (up-down direction). Therefore, it is considered that the saturation state of the core in the motor 1 is suppressed, and as a result, the proportion of the third harmonic can be reduced. As a result, the motor performance can be improved.

[0074] In addition, in this embodiment, each core piece 4 also has an asymmetric shape in the direction (fourth direction A4) perpendicular to the axial direction (first direction A1), thereby further suppressing the core saturation state and reducing the proportion of harmonics.

[0075] In particular, in this embodiment, each core piece 4 is provided with an extension portion 40, and each extension portion 40 contacts the step portion 410 of the adjacent stator core 3, and the multiple extension portions 40 are arranged in a ring shape as a whole. Therefore, the multiple extension portions 40 can function as a part that forms a magnetic circuit, like the annular core T2X of the motor 1X of the comparative example. As a result, in the motor 1, it is not necessary to provide the annular core T2X of the motor 1X of the comparative example separately. In other words, the motor 1 of this embodiment has a reduced number of parts compared to the motor 1X. In addition, compared to the case where the annular core T2X is provided as in the motor 1X of the comparative example, the presence of many small gaps (air gaps) between the multiple extension portions 40 arranged in a ring shape can further suppress the saturation state of the core.

[0076] In this embodiment, the multiple extension parts 40 are located on the side of the second rotor R2 that does not have a permanent magnet, opposite the first rotor R1 that has the permanent magnet P1, that is, on the tip end 402 rather than the base end 403. In other words, the multiple extension parts 40 are arranged to face the second rotor R2 only on the side of the second rotor R2 that does not have a permanent magnet, out of the first rotor R1 and the second rotor R2. This can further suppress the saturation state of the core.

[0077] Furthermore, in this embodiment, the motor 1 is a double-rotor motor having a pair of rotors, and therefore the proportion of harmonics can be reduced while improving the torque compared to a single-rotor motor.

[0078] (4) Variations The above embodiment is merely one of various embodiments of the present disclosure. The above embodiment can be modified in various ways depending on the design and the like as long as the object of the present disclosure can be achieved.

[0079] Modifications of the above embodiment are listed below. Each modification described below can be applied in appropriate combination with the above embodiment or other modifications. Hereinafter, the above embodiment may be referred to as a "basic example."

[0080] In the basic example, the extending portion 40 is provided at the tip portion 402 of each core piece 4. However, the extending portion 40 may be provided at the base end portion 403. In this case, the step portion 410 may be provided at the base end portion 403.

[0081] In the basic example, when the twelve annularly arranged stator cores 3 are viewed from above, the extension portion 40 extends clockwise from the standing portion 401 of the tip portion 402. However, the extension portion 40 may extend counterclockwise from the standing portion 401. In this case, the step portion 410 is also disposed on the opposite side of the extension portion 40.

[0082] In the basic example, the extension portion 40 of the third core lamination 43 does not rest on the step portion 410 of the adjacent stator core because the amount of protrusion is small. However, the amount of protrusion of the extension portion 40 of the third core lamination 43 may also be increased so that it rests on the step portion 410 of the adjacent stator core.

[0083] In the basic example, the motor 1 is a double rotor type motor, but it may also be a single rotor type motor.

[0084] In a basic example, the motor 1 is used in a ceiling fan 100. However, the use of the motor 1 is not particularly limited. The motor 1 of the present disclosure can be applied to, for example, a motor for a ventilation fan, an in-wheel motor or a wheel motor for an electric vehicle or the like, a hub motor for an electric bicycle or the like, or a motor built into a hard disk drive, etc.

[0085] (5) Summary As described above, the motor (1) according to the first aspect includes a stator (2) and a rotor (first rotor R1). The rotor (first rotor R1) has a permanent magnet (P1), is disposed facing the stator (2), and rotates about a rotating shaft (L1). The stator (2) has a plurality of stator cores (3) disposed in an annular shape along the circumferential direction (second direction A2) of the rotating shaft (L1), and a plurality of armature coils (5) wound around the stator cores (3), respectively. Each of the plurality of stator cores (3) has a plurality of core pieces (4). Each of the plurality of core pieces (4) has an asymmetric shape in the axial direction (first direction A1) of the rotating shaft (L1).

[0086] According to this embodiment, each of the core pieces (4) has an asymmetric shape in the axial direction (first direction A1) of the rotating shaft (L1), which suppresses the core from becoming saturated, thereby reducing the proportion of harmonics, and thus improving the motor performance.

[0087] With respect to the motor (1) of the second aspect, in the first aspect, each of the multiple core pieces (4) further has an asymmetric shape in a direction perpendicular to the axial direction (first direction A1) when viewed along the radial direction (third direction A3) of the rotation axis (L1).

[0088] According to this embodiment, the saturation state of the core can be further suppressed, and the proportion of harmonics can be reduced.

[0089] With regard to the motor (1) of the third aspect, in the first or second aspect, the multiple core pieces (4) have multiple extension portions (40) each extending in a direction perpendicular to the axial direction (first direction A1) when viewed along the radial direction (third direction A3) of the rotation axis (L1).

[0090] According to this embodiment, the multiple extensions (40) can function as parts that form a magnetic circuit.

[0091] Regarding the motor (1) according to the fourth aspect, in the third aspect, the dimensions of the multiple extensions (40) in the axial direction (first direction A1) are different from one another.

[0092] According to this embodiment, the saturation state of the core can be further suppressed, and the proportion of harmonics can be reduced.

[0093] With respect to the motor (1) of the fifth aspect, in the third or fourth aspect, each of the multiple core pieces (4) of the multiple stator cores (3) has a step portion (410) in which at least one of the multiple extension portions (40) of adjacent stator cores (3) in the circumferential direction (second direction A2) is arranged in contact with the step portion (410).

[0094] According to this embodiment, the multiple extensions (40) can function as an annular core for forming a magnetic circuit, making it unnecessary to provide an annular core separately from the multiple stator cores (3).

[0095] Regarding the motor (1) according to the sixth aspect, in any one of the first to fifth aspects, the plurality of core pieces (4) include three core pieces (4).

[0096] According to this embodiment, the saturation state of the core can be further suppressed, and the proportion of harmonics can be reduced.

[0097] Regarding the motor (1) according to the seventh aspect, in any one of the first to sixth aspects, the multiple core pieces (4) are aligned along the radial direction (third direction A3) of the rotation shaft (L1).

[0098] According to this embodiment, the saturation state of the core can be further suppressed, and the proportion of harmonics can be reduced.

[0099] The motor (1) according to an eighth aspect is any one of the first to seventh aspects, and further includes a second rotor (R2) in addition to the first rotor (R1) as a rotor. The first rotor (R1) and the second rotor (R2) are arranged in the axial direction (first direction A1) with the stator (2) interposed therebetween.

[0100] According to this aspect, it is possible to provide a motor (1) capable of reducing the proportion of harmonics while improving torque.

[0101] Regarding the motor (1) according to the ninth aspect, in the eighth aspect, the second rotor (R2) does not have a permanent magnet.

[0102] According to this embodiment, it is possible to provide a motor (1) capable of improving torque and further reducing the proportion of harmonics.

[0103] In the motor (1) according to the tenth aspect, in the ninth aspect, the core pieces (4) each have a plurality of extending portions (40) extending in a direction perpendicular to the axial direction (first direction A1) when viewed along the radial direction (third direction A3) of the rotation shaft (L1). The extending portions (40) are arranged only on the side of the second rotor (R2) that does not have a permanent magnet, between the first rotor (R1) and the second rotor (R2), so as to face the second rotor (R2).

[0104] According to this embodiment, the saturation state of the core can be further suppressed.

[0105] The motor (1) according to an eleventh aspect is the motor according to any one of the first to tenth aspects, which is used in the ceiling fan (100).

[0106] According to this aspect, it is possible to provide a motor (1) for a ceiling fan (100) that can improve motor performance.

[0107] The configurations according to the second to eleventh aspects are not essential to the motor (1) and may be omitted as appropriate. [Explanation of symbols]

[0108] 100 Ceiling Fan 1 Motor 2 Stator 3 Stator core 4 Core pieces 40 Extension 410 Multilayered section 5 Armature coil A1 1st direction (axial direction) A2 2nd direction (circumferential direction) A3 3rd direction (radial direction) L1 Rotational Axis P1 permanent magnet R1 First rotor R2 Second rotor

Claims

1. A stator; a rotor having a permanent magnet, disposed opposite the stator, and rotating about a rotation axis; Equipped with the stator includes a plurality of stator cores arranged in an annular shape along a circumferential direction of the rotating shaft, and a plurality of armature coils wound around the plurality of stator cores, Each of the plurality of stator cores has a plurality of core pieces, Each of the plurality of core pieces has an asymmetric shape in an axial direction of the rotation shaft, The plurality of core pieces each have a plurality of extending portions each extending in a direction perpendicular to the axial direction as viewed along a radial direction of the rotation shaft, Each of the core pieces of the plurality of stator cores has a step portion where at least one of the extension portions of the stator cores adjacent to each other in the circumferential direction is arranged in contact with the step portion. Motor.

2. Each of the plurality of core pieces further has an asymmetric shape in a direction perpendicular to the axial direction as viewed along the radial direction of the rotation shaft. The motor according to claim 1 .

3. The dimensions of the plurality of extension portions in the axial direction are different from each other, 3. The motor according to claim 1 or 2.

4. The plurality of core pieces consists of three core pieces, The motor according to any one of claims 1 to 3.

5. The plurality of core pieces are aligned along the radial direction of the rotating shaft, The motor according to any one of claims 1 to 4.

6. Further comprising a second rotor in addition to the first rotor as the rotor, the first rotor and the second rotor are arranged in the axial direction with the stator interposed therebetween; The motor according to any one of claims 1 to 5.

7. The second rotor does not have a permanent magnet.

7. The motor according to claim 6.

8. The plurality of core pieces have a plurality of extension portions each extending in a direction perpendicular to the axial direction as viewed along the radial direction of the rotation shaft, the plurality of extension portions are disposed only on a side of the second rotor that does not have a permanent magnet, among the first rotor and the second rotor, so as to face the second rotor.

8. The motor according to claim 7.

9. A motor for use in a ceiling fan. The motor according to any one of claims 1 to 8.

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