electric motor

Abstract

A motor of the present application has a rotor fixed to a rotating shaft, a stator disposed around the rotor with a gap in a radial direction orthogonal to the axial direction of the rotating shaft, and a housing that houses the rotor and the stator. The rotor has a plurality of rotor cores formed of a soft magnetic material and a rotor fixing member that fixes the rotor cores. The stator has a plurality of stator cores formed of a soft magnetic material, a stator fixing member that fixes the stator cores, and a coil wound around each stator core. The rotor and the stator are each two or more groups stacked in the axial direction of the rotating shaft.

Description

Technical Field

[0001] This invention relates to electric motors, and more particularly to radial gap-type motors. Background Technology

[0002] As a radial clearance type electric motor, the electric motor described in Japanese Patent Application Publication No. 2004-343905 is known, for example. The electric motor described in Japanese Patent Application Publication No. 2004-343905 is a so-called external rotor type electric motor, which has: a stator, which is fixed to a rotating shaft and has a plurality of stator cores protruding in a direction away from the rotating shaft and coils wound around each stator core; and a rotor, which is arranged to surround the stator in a radial direction orthogonal to the rotating shaft and has a plurality of rotor cores facing opposite to the stator cores. Summary of the Invention

[0003] However, the aforementioned external rotor type motor has a structure in which the stator core and coil are arranged on the inner side of the motor (i.e., the rotating shaft side). Therefore, if the number of coil turns is increased in order to improve the output torque of the motor, there is a problem that the overall size of the motor becomes larger and it is difficult to achieve miniaturization.

[0004] This invention was made to solve such a technical problem, and its purpose is to provide an electric motor that can improve output torque and achieve miniaturization.

[0005] The electric motor of the present invention has a rotor fixed to a rotating shaft and a stator arranged around the rotor in a radial direction orthogonal to the axial direction of the rotating shaft, spaced apart from the rotor; the rotor has a plurality of first cores formed of a soft magnetic material and a rotor fixing member for fixing the first cores; the stator has a plurality of second cores formed of a soft magnetic material, a stator fixing member for fixing the second cores, and a coil wound on each of the second cores; the rotor and the stator are each in two or more sets, stacked axially on the rotating shaft.

[0006] The electric motor of the present invention has a stator with multiple second cores and coils wound on each second core arranged outside the rotor. Therefore, compared with conventional external rotor type motors, it is easier to ensure a large space for the coils and increase the number of coil turns. As a result, the output torque of the motor can be improved and the motor can be miniaturized. Moreover, since there are two or more sets of rotors and stators stacked axially along the rotation axis, the output torque of the motor can be further improved compared with the case where there is only one rotor and one stator.

[0007] In the electric motor of the present invention, it is preferable that the first winding core and the second winding core are configured such that their respective width directions are along the rotation direction of the rotor; the width of the first winding core is larger than the width of the second winding core. This allows for a further increase in the space of the coils, thus further improving the output torque of the electric motor.

[0008] Furthermore, in the electric motor of the present invention, it is preferable that the first core and the second core are configured such that their respective width directions are parallel to the axial direction of the rotation axis; the number of the first core and the second core are the same; when the number of the second core is set to Ns and the number of rotor and stator groups is set to n, the energization of each group is switched such that the rotors of the first to nth groups rotate 360° / (Ns×n) each time. In this way, each rotor can rotate continuously, thus driving the electric motor more smoothly.

[0009] Furthermore, in the electric motor of the present invention, it is preferable that the second winding cores of all groups are arranged in the same position; in the initial position, the first winding core of the first group is arranged relative to the second winding core of the first group at a position rotated 360° / (Ns×n) in the opposite direction to the rotation direction of the rotation axis, and the first winding cores of the first to nth groups are arranged in each group at a position rotated 360° / (Ns×n) in the opposite direction to the rotation direction of the rotation axis. This allows each rotor to rotate continuously, thus enabling smoother motor drive.

[0010] Furthermore, in the electric motor of the present invention, it is preferable that the first winding cores of all groups are arranged in the same position; in the initial position, the second winding cores of the first group are arranged relative to the first winding cores of the first group at a position rotated 360° / (Ns×n) in the rotation direction of the rotation axis, and the second winding cores of the first to nth groups are arranged in a position rotated 360° / (Ns×n) in the rotation direction of the rotation axis for each group. This allows each rotor to rotate continuously, thus enabling smoother motor drive.

[0011] According to the present invention, it is possible to improve the output torque and achieve miniaturization. Attached Figure Description

[0012] Hereinafter, the features, advantages, and technical and industrial significance of exemplary embodiments of the present invention will be described with reference to the accompanying drawings, wherein similar reference numerals denote similar elements.

[0013] Figure 1 This is a schematic top view showing the electric motor of the first embodiment.

[0014] Figure 2 It is along Figure 1A schematic cross-sectional view of line AA.

[0015] Figure 3 It is a three-dimensional diagram used to illustrate the method of forming the rotor core and stator core.

[0016] Figure 4 It is along Figure 2 A partial schematic cross-sectional view of the BB line.

[0017] Figure 5 This is a schematic cross-sectional view showing the case where the thickness of the rotor core is greater than the thickness of the stator core.

[0018] Figure 6 This is a graph showing the core area ratio and torque ratio of the motor in this embodiment and a conventional IPM.

[0019] Figure 7 This is a schematic top view showing the electric motor of the second embodiment.

[0020] Figure 8 It is along Figure 7 An exploded 3D view of the CC line.

[0021] Figure 9 This is a cross-sectional view used to illustrate the energization of the electric motor in the second embodiment. Detailed Implementation

[0022] Hereinafter, embodiments of the electric motor of the present invention will be described with reference to the accompanying drawings. In the description of the drawings, the same elements are given the same reference numerals and repeated descriptions are omitted. In addition, in order to avoid complexity of the description, in the following description, "radial direction orthogonal to the axis of rotation" is sometimes omitted and simply referred to as "radial direction".

[0023] [First Implementation]

[0024] Figure 1 This is a schematic top view showing the electric motor of the first embodiment. Figure 2 It is along Figure 1 A schematic cross-sectional view along line AA. The motor 1 in this embodiment is a motor that does not employ magnets. This motor 1 is a so-called internal rotor type motor, having: a metal rotating shaft 2; a rotor 3 fixed to the rotating shaft 2; a stator 4 arranged opposite to the rotor 3 in a radial direction orthogonal to the axial direction of the rotating shaft 2 and spaced apart from the rotor 3; and a housing 5 for housing the rotor 3 and the stator 4.

[0025] The rotor 3 and stator 4 are each in two sets, stacked along the axial direction of the rotation axis 2. In this embodiment, relative to... Figure 2On the paper, the upper stator 4 and rotor 3 are designated as the first group, and the lower stator 4 and rotor 3 are designated as the second group. In this embodiment, an example is shown where the rotor 3 has 4 poles and the stator 4 has 6 poles in each group, but the number of poles of the rotor 3 and stator 4 is not limited to this. Furthermore, the number of poles of the rotor 3 is the same as the number of rotor cores 32 (described later), and the number of poles of the stator 4 is the same as the number of stator cores 42 (described later).

[0026] The housing 5 includes a cylindrical side portion 51 and a pair of circular plate-shaped cover portions 52 that block the openings at both ends of the side portion 51. A bearing component 53 that rotatably supports the rotating shaft 2 is installed at the center of each cover portion 52. The material of the housing 5 is not particularly limited, but from the viewpoint of mechanical strength and heat dissipation, it is preferably made of metal.

[0027] The rotor 3 has a plurality of (four in this case) rotor cores (first cores) 32 arranged at equal intervals along the circumference of the motor 1 and a rotor fixing member 31 for fixing each rotor core 32.

[0028] The rotor core 32 is, for example, composed of a U-shaped cut core made of a soft magnetic material. Figure 3 As shown, the cutting core is formed by dividing a coiled body 3a, which is formed by winding a strip of soft magnetic material multiple times. Figure 3 The designation L indicates the division position of the winding body 3a. Furthermore, when the width of the rotor core 32 is equal to the width of the stator core 42 (described later) and the thickness of the rotor core 32 is equal to the thickness of the stator core 42, one rotor core 32 and one stator core 42 can be formed from one winding body 3a. When the widths or thicknesses of the two are different, two rotor cores 32 (or stator cores 42) can be formed from one winding body 3a.

[0029] The rotor core 32 is configured such that its width direction is along the rotation direction of the rotor 3 (i.e., the circumferential direction of the motor 1). Furthermore, the width direction here is... Figure 3 The short side direction of the strip-shaped soft magnetic material shown.

[0030] The material of the rotor core 32 is not particularly limited as long as it is a soft magnetic material. For example, it can be oriented or non-oriented electromagnetic steel sheet, iron-based soft magnetic amorphous material, cobalt-based soft magnetic amorphous material, nanocrystalline soft magnetic material, iron-cobalt based Borman-Dour alloy material, etc. In this embodiment, oriented electromagnetic steel sheet is preferred. This is because, in the case of oriented electromagnetic steel sheet, the crystal orientation is consistent in its long side direction (also known as the rolling direction), and there is an easy magnetization axis in this direction. Therefore, the resulting rotor core 32 has excellent magnetic properties.

[0031] The rotor core 32 has two end faces (segmented surfaces) 32a and 32b facing the same direction. The end faces 32a and 32b of the rotor core 32 are radially opposite to the end faces 42a and 42b of the stator core 42 (described later). When the end faces 32a and 32b of the rotor core 32 are facing the end faces 42a and 42b of the stator core 42 (described later), magnetic flux exiting from the end face 42a or 42b of the stator core 42 enters the end face 32a or 32b of the rotor core 32, passes through the rotor core 32, and exits from the end face 32b or 32a to enter the end face 42b or 42a of the stator core 42.

[0032] like Figure 2 As shown, the rotors 3 of the first group and the rotors 3 of the second group are arranged adjacent to each other along the axial direction of the rotation shaft 2. Furthermore, adjacent rotor cores 32 are fixed to each other by welding, bonding, or winding with resin tape.

[0033] The rotor fixing component 31 consists of a connecting component 311 that is connected to the rotating shaft 2 and extends radially, and a clamping component 312 that is connected to the top end of the connecting component 311 and clamps and fixes the rotor core 32 from around it. The material of the rotor fixing component 31 is not particularly limited as long as it is a non-magnetic material, but it is preferably a non-magnetic metal such as stainless steel, or a carbon fiber or organic material with low conductivity, or a high-strength and high-toughness ceramic material.

[0034] On the other hand, the stator 4 has a plurality of (here, 6) stator cores (second winding cores) 42 arranged at equal intervals along the circumference of the motor 1, a stator fixing member 41 for fixing each stator core 42, and a coil 43 wound around each stator core 42.

[0035] The stator core 42 is, for example, a U-shaped cut core made of a soft magnetic material. As described above. Figure 3 As shown, the cutting core is formed by dividing a wound body 3a, which is made by winding a strip of soft magnetic material multiple times. The stator core 42 is configured such that its width direction is along the rotation direction of the rotor 3.

[0036] The material of the stator core 42 is not particularly limited as long as it is a soft magnetic material. For example, it can be oriented or non-oriented electromagnetic steel plate, iron-based soft magnetic amorphous material, cobalt-based soft magnetic amorphous material, nanocrystalline soft magnetic material, iron-cobalt based Bormen-Dour alloy material, etc. However, oriented electromagnetic steel plate is preferred. This is because, in the case of oriented electromagnetic steel plate, the crystal orientation is consistent along its long side direction (also known as the rolling direction), and there is an easy magnetization axis in this direction. Therefore, the resulting stator core 42 has excellent magnetic properties.

[0037] Furthermore, the methods for forming the stator core 42 and the rotor core 32 are not limited to those described above. For example, the core can also be formed by bending strip-shaped soft magnetic material into a U-shape and stacking multiple sheets. Alternatively, the core can be formed by other methods such as sintering or casting without stacking strip-shaped soft magnetic material.

[0038] The stator core 42 has two end faces (segmentation surfaces) 42a and 42b facing the same direction. For example, the end face 42a of the stator core 42 faces the end face 32a of the rotor core 32, and the end face 42b faces the end face 32b of the rotor core 32.

[0039] like Figure 2 As shown, there are also two groups of stators 4. The first group of stators 4 and the second group of stators 4 are arranged adjacent to each other along the axial direction of the rotation shaft 2. Furthermore, adjacent stator cores 42 are fixed to each other by welding, bonding, or winding with resin tape.

[0040] The stator fixing component 41 comprises an abutting portion 411 that abuts against the outer wall of the side portion 51 of the housing 5, an insertion portion 412 that bends from both ends of the abutting portion 411 and can be inserted into a slot (not shown) provided in the side portion 51 of the housing 5, and a holding portion 413 that connects to the insertion portion 412 and holds the coil 43 and the stator core 42. The material of the stator fixing component 41 is not particularly limited as long as it is a non-magnetic material, but it is preferably a non-magnetic metal such as stainless steel, or a low-conductivity carbon fiber or organic material, or a high-strength and high-toughness ceramic material.

[0041] Coil 43 is a winding formed by winding a conductor multiple times. In this embodiment, for example... Figure 4 As shown, coil 43 is wound in two layers in such a way that it winds around adjacent stator cores 42 to each other.

[0042] If a current, such as a rectangular wave, is energized to coil 43 at a predetermined timing, a magnetic flux is generated within stator core 42. The rotor core 32 of rotor 3 is attracted by this magnetic flux, causing rotor 3 to rotate. Specifically, by energizing coil 43 wound around predetermined stator core 42, a magnetic flux is generated in predetermined stator core 42. This magnetic flux pulls rotor core 32 to a position opposite to predetermined stator core 42, causing rotor core 32 to rotate by a predetermined angle. Next, energizing coil 43 of predetermined stator core 42 is stopped, and energizing coil 43 of adjacent stator core 42 is performed, causing adjacent stator core 42 to generate magnetic flux. Thus, through the magnetic flux of adjacent stator core 42, rotor core 32 is pulled to a position opposite to adjacent stator core 42, causing rotor core 32 to rotate further by a predetermined angle. By repeating this process, rotor 3 rotates continuously.

[0043] Next, an example of a combination of the number of rotor cores 32 and the number of stator cores 42 will be explained. Here, the number of rotor cores 32 is set as Nr, the number of stator cores 42 is set as Ns, and the step angle is set as ε. The rotor angle (i.e., the spacing between the rotor cores 32 in the circumferential direction of the motor 1) θr is calculated using θr = 360° / Nr. The stator angle (i.e., the spacing between the stator cores 42 in the circumferential direction of the motor 1) θs is calculated using θs = 360° / Ns. Furthermore, the step angle ε refers to the rotation angle of the rotation axis 2 for each pulse of the rectangular wave current of the input coil 43.

[0044] When the number of stator cores 42, Ns, is greater than the number of rotor cores 32, Nr (i.e., Ns > Nr), the step angle ε is ε = 360°(1 / Nr - 1 / Ns). Therefore, Ns = 360° × Nr / (360° - ε × Nr). Using this formula, we can find combinations where Nr and Ns are integers for any step angle ε. An example of this is shown in Table 1 below.

[0045] Table 1

[0046]

[0047] On the other hand, when the number of stator cores 42, Ns, is less than the number of rotor cores 32, Nr (i.e., Ns < Nr), the step angle ε is ε = 360°(1 / Ns - 1 / Nr), therefore, Ns = 360° × Nr / (360° + ε × Nr). Using this formula, it is possible to find combinations where Nr and Ns are integers for any step angle ε. An example of this is shown in Table 2 below.

[0048] Table 2

[0049]

[0050] Among the combinations shown in Tables 1 and 2 above, the combination of a three-phase driven motor that operates via a universal converter or a two-phase driven motor that can reduce converter elements and has a synchronous pole number of 6 or more is particularly powerful because it can achieve high torque.

[0051] In the electric motor 1 of this embodiment, the width Wr of the rotor core 32 and the width Ws of the stator core 42 can be different. For example... Figure 1 As shown, the width Wr of the rotor core 32 is preferably larger than the width Ws of the stator core 42. This allows for a larger space for the coil 43, increasing the number of turns and thus improving the output torque of the motor 1.

[0052] Furthermore, in the electric motor 1 of this embodiment, the thickness tr of the rotor core 32 and the thickness ts of the stator core 42 can be different. For example... Figure 5 As shown, the thickness tr of the rotor core 32 is preferably greater than the thickness ts of the stator core 42. This further increases the output torque of the motor 1. Furthermore, as the thickness tr of the rotor core 32 increases compared to the thickness ts of the stator core 42, the length of the rotor core 32 along the axial direction of the rotating shaft 2 also increases. Therefore, to avoid interference between the rotor core 32 and the cover portion 52, a stepped portion 521 (see reference) can be provided in the cover portion 52, for example. Figure 5 ).

[0053] The motor 1 constructed as described above has a stator 4, which has multiple stator cores 42 and coils 43 wound around each stator core 42, arranged outside the rotor 3. Therefore, compared with conventional external rotor type motors, it is easier to ensure a large space for the coils 43 and increase the number of turns of the coils 43. As a result, the output torque of the motor 1 can be improved and the motor 1 can be miniaturized. Moreover, since there are two or more sets of rotors 3 and stators 4 stacked axially on the rotation shaft 2, the output torque of the motor 1 can be further improved compared with the case where there is only one rotor and one stator.

[0054] To verify the effectiveness of motor 1, the inventors of this application used an existing IPM (Interior Permanent Magnet) motor as a comparison benchmark and studied the core area ratio and torque ratio using the combinations of motors shown in Table 3 below. The results are as follows: Figure 6 As shown. In Figure 6 In the diagram, the "area ratio" indicated by the dashed line is a torque indicator relative to existing IPM motors, based on the proportional relationship between the motor's output torque and the core area (total pole area). The "B reflection" indicated by the solid line reflects the influence of magnetic flux density B and the core area, based on the relationship that the motor's output torque in current IPMs is proportional to the magnetic flux density B, while in the motor 1 of this embodiment, the motor's output torque is proportional to the square of the magnetic flux density B. The "torque diameter reflection" indicated by the dashed line reflects the influence of the core area, magnetic flux density B, and torque diameter, based on the proportional relationship between the motor's output torque and the torque center diameter.

[0055] Table 3

[0056]

[0057] like Figure 6 As can be seen from the figure, the motor of this embodiment can improve the output torque of the motor compared with the current IPM motor.

[0058] [Second Implementation]

[0059] The following is based on Figures 7-9 The second embodiment of the electric motor will now be described. The electric motor 6 of the second embodiment differs from the first embodiment in that the number of rotor cores 32 and stator cores 42 are the same and their respective width directions are parallel to the axial direction of the rotation shaft 2. Hereinafter, the description will focus on the differences from the electric motor 1 of the first embodiment.

[0060] Figure 7 This is a schematic top view showing the electric motor of the second embodiment. Figure 8 It is along Figure 7 An exploded 3D view of the CC line. Figure 7 In order to make it easier to understand the inside of the motor 6, the state of the cover 52 of the housing 5 is shown after it has been removed. Figure 8 In this text, the housing 5, the rotating shaft 2, and the stator base 44 (described later) are omitted.

[0061] like Figure 7 and Figure 8 As shown, the electric motor 6 includes: a metal rotating shaft 2; a rotor 3 fixed to the rotating shaft 2; a stator 4 arranged radially opposite to the rotor 3 with a gap between them; and a housing 5 housing the rotor 3 and the stator 4. The rotor 3 and stator 4 are each in three sets, stacked along the axial direction of the rotating shaft 2. In this embodiment, relative to... Figure 8 On the paper, the stator 4 and rotor 3 located at the top are designated as the first group, the stator 4 and rotor 3 located at the bottom are designated as the third group, and the stator 4 and rotor 3 located in between are designated as the second group. In each group, the number of poles of rotor 3 and stator 4 is 12 (i.e., Ns = Nr = 12).

[0062] Furthermore, the number of poles of rotor 3 and stator 4 is not limited to 12. From the viewpoint of ensuring output torque, it is preferable that 3 ≤ Ns = Nr ≤ 40. In addition, considering that a large drive voltage is required if the frequency is too high, and the need to reduce iron losses, it is preferable that 3 ≤ Ns = Nr ≤ 24.

[0063] The rotor 3 has a circular plate-shaped rotor base (rotor fixing component) 33 made of non-magnetic material, and 12 rotor cores 32 fixed along the circumference of the rotor base 33 (in other words, the circumference of the motor 6). The rotor base 33 is fixed to the rotation shaft 2. The rotor base 33 is made of the same material as the rotor fixing component 31 described in the first embodiment. Furthermore, the 12 rotor cores 32 are arranged such that their respective width directions are parallel to the axial direction of the rotation shaft 2, and are evenly spaced along the circumference of the rotor base 33. The rotor cores 32 are fixed to the rotor base 33 by being inserted into through holes (not shown) provided in the rotor base 33.

[0064] The stator 4 has a stator base (stator fixing member) 44 in the shape of a ring plate made of non-magnetic material, 12 stator cores 42 fixed along the circumference of the stator base 44 (in other words, the circumference of the motor 6), and coils 43 wound around the stator cores 42. The stator base 44 is fixed to the housing 5. The stator base 44 is made of the same material as the stator fixing member 41 described in the first embodiment. Furthermore, the 12 stator cores 42 are arranged such that their respective width directions are parallel to the axial direction of the rotation shaft 2, and are arranged at equal intervals along the circumference of the stator base 44. The stator cores 42 are fixed to the stator base 44 by being inserted into through holes (not shown) provided in the stator base 44. Two coils 43 connected in series are wound around each stator core 42.

[0065] In the electric motor 6 of this embodiment, when the number of rotor 3 and stator 4 groups is set to n, the energization of each group is switched such that the rotor 3 of the first to the nth group rotates 360° / (Ns×n) each time. As mentioned above, Ns=12 and n=3, so the energization of these three groups is switched sequentially such that the rotor 3 of the first to the third group rotates 360° / (12×3)=10° each time. That is to say, the electric motor 6 in this case is a three-phase driven electric motor. Hereinafter, based on Figure 9 A detailed explanation will be provided. Furthermore... Figure 9 The direction indicated by the middle arrow is the rotation direction of rotor 3 (i.e., the rotation direction of rotating shaft 2).

[0066] like Figure 9 As shown, in the initial position, the rotor core 32 of the first group is positioned relative to the stator core 42 of the first group, rotated 10° in the opposite direction to the rotation direction of the rotating shaft 2 (clockwise in this case). The rotor core 32 of the second group is positioned relative to the stator core 42 of the second group, rotated 20° clockwise. The rotor core 32 of the third group is positioned relative to the stator core 42 of the third group, rotated 30° clockwise. That is, the rotor cores 32 of the first to third groups are positioned with each group rotated 10° clockwise. On the other hand, the stator cores 42 of the first to third groups are positioned in the same position along the axial direction of the rotating shaft 2. That is, the stator cores 42 of all groups are positioned identically.

[0067] If, from this initial position, only the coil 43 wound around the first group of stator cores 42 is energized (only the first group is energized), a magnetic flux is generated in the stator core 42. Through this magnetic flux, the first group of rotor cores 32 is attracted, causing the first group of rotors 3 to rotate 10° in the direction of rotation of the rotating shaft 2 (counterclockwise in this case). Accompanying the rotation of the first group of rotors 3, the second and third groups of rotors 3, which are also fixed to the rotating shaft 2, also rotate 10° counterclockwise. Therefore, the result of energizing only the coil 43 wound around the first group of stator cores 42 is as follows: Figure 9 As shown, the rotor core 32 of the first group is located at 0° relative to the stator core 42 of the first group (i.e., the two are in the same position), the rotor core 32 of the second group is located at 10° clockwise relative to the stator core 42 of the second group, and the rotor core 32 of the third group is located at 20° clockwise relative to the stator core 42 of the third group.

[0068] Next, if only the coil 43 wound around the stator core 42 of the second group is energized (only the second group is energized), a magnetic flux is generated in the stator core 42, attracting the rotor core 32 of the second group, thereby causing the rotor 3 of the second group to rotate 10° counterclockwise. Consequently, the rotors 3 of the first and third groups also rotate 10° counterclockwise respectively. Therefore, the result of energizing only the coil 43 wound around the stator core 42 of the second group is as follows... Figure 9 As shown, the rotor core 32 of the first group is located at a position 10° counterclockwise relative to the stator core 42 of the first group (in Figure 9 The rotor core 32 of the second group is located at 0° relative to the stator core 42 of the second group (i.e., the positions of the two are the same), and the rotor core 32 of the third group is located at 10° clockwise relative to the stator core 42 of the third group.

[0069] Next, if only the coil 43 wound around the third group of stator cores 42 is energized (only the third group is energized), a magnetic flux is generated in the stator core 42, attracting the rotor core 32 of the third group, thus causing the rotor 3 of the third group to rotate 10° counterclockwise. Consequently, the rotors 3 of the first and second groups also rotate 10° counterclockwise. Therefore, the result of energizing only the coil 43 wound around the third group of stator cores 42 is as follows: Figure 9 As shown, the rotor core 32 of the first group is located at a position 20° counterclockwise relative to the stator core 42 of the first group (in Figure 9 The rotor core 32 of the second group is located 10° counterclockwise relative to the stator core 42 of the second group (at -20°). Figure 9 (The value is -10°), and the rotor core 32 of the third group is located at 0° relative to the stator core 42 of the third group (i.e., the positions of the two are the same).

[0070] By repeatedly switching the power on each group, rotor 3 rotates continuously.

[0071] In addition to achieving the same effects as in the first embodiment described above, the electric motor 6 according to this embodiment can be driven more smoothly.

[0072] Furthermore, in this embodiment, for example, all groups of rotor cores 32 may be arranged in the same position. In the initial position, the stator core 42 of the first group is arranged 10° rotated in the rotation direction of the rotating shaft 2 (e.g., counterclockwise) relative to the rotor core 32 of the first group. Additionally, the stator cores 42 of the first to third groups are arranged in positions where each group is rotated 10° in the rotation direction of the rotating shaft 2. In this way, by repeatedly switching the energization of each group, the motor 6 can be driven more smoothly.

[0073] Furthermore, in the electric motor 6 of this embodiment, the number n of rotor 3 and stator 4 is preferably 2 ≤ n ≤ 5. This is because if the number of groups exceeds 5, the length of the motor along the axial direction of the rotating shaft 2 becomes larger, thereby hindering the miniaturization of the electric motor 6.

[0074] Furthermore, the inventors of this application compared the torque ratio, rotor diameter ratio a (which affects the torque), length ratio b (of the rotational force generating part), and square ratio c (of the magnetic flux density) of the motor 6 (radial gap type motor) of this embodiment with the same volume and a conventional axial gap-type SR motor (AGSRM) based on AGSRM. The results are shown in Table 4 below. "Rotor diameter" is based on AGSRM and is compared with the thickness of the rotor core 32 in the motor of this embodiment (see reference). Figure 3 The length of the part generating the rotational force is equivalent to the width of the stator core 42 in the motor of this embodiment (see reference). Figure 1 The Ws shown is equivalent.

[0075] As shown in Table 4, the rotor diameter of the motor 6 in this embodiment can be increased compared to the conventional AGSRM. Furthermore, while conventional AGSRMs could only use non-directional electromagnetic steel plates, the motor 6 in this embodiment can use directional electromagnetic steel plates. Using directional electromagnetic steel plates increases the magnetic flux density, thus increasing the torque. As a result, even in a radially spaced motor without magnets, torque equal to or greater than that of conventional AGSRMs can be obtained.

[0076] Table 4

[0077]

[0078] The embodiments of the present invention have been described in detail above, but the present invention is not limited to the embodiments described above. Various design changes can be made without departing from the spirit of the present invention as set forth in the claims.

Claims

1. An electric motor having a rotor fixed to a rotating shaft and a stator disposed around the rotor in a radial direction orthogonal to the axial direction of the rotating shaft, spaced apart from the rotor; The rotor has a plurality of first cores formed of soft magnetic material, and rotor fixing components for fixing these first cores; The stator has a plurality of second cores formed of soft magnetic material, a stator fixing component for fixing the second cores, and a coil wound on each of the second cores; The rotor and the stator are each in two or more sets, stacked axially on the rotating shaft. The first core and the second core are configured such that their respective width directions are parallel to the axial direction of the rotation axis; The number of the first core and the second core are the same; When the number of the second winding cores is set to Ns and the number of rotor and stator groups is set to n, the energization of each group is switched in such that the rotors of the first to nth groups rotate 360° / (Ns×n) each time. The second core of all groups is positioned in the same location; In the initial position, the first core of the first group is positioned relative to the second core of the first group at a position rotated 360° / (Ns×n) in the opposite direction to the rotation direction of the rotation axis, and the first cores of the first to n groups are positioned in each group at a position rotated 360° / (Ns×n) in the opposite direction to the rotation direction of the rotation axis.

2. The electric motor as described in claim 1, The first core of all groups is positioned in the same location; In the initial position, the second core of the first group is positioned relative to the first core of the first group at a position rotated 360° / (Ns×n) in the rotation direction of the rotation axis, and the second cores of the first to nth groups are positioned in each group at a position rotated 360° / (Ns×n) in the rotation direction of the rotation axis.

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