Rotor

Abstract

The rotor is rotatable about a vertically extending central axis, and has a cylindrical rotor core, a first magnet, and a second magnet. The rotor core has a plurality of first housing holes and second housing holes extending in the axial direction and arranged in the circumferential direction. The first magnet is housed in the first housing hole so that first gaps are provided on both sides in the radial direction. The second magnet is accommodated in the second accommodating hole in a manner that second gaps are arranged on two sides of the second magnet in the circumferential direction. When viewed in the axial direction, two first receiving holes are separated from each other in pairs toward the outside in the radial direction and extend in a V-shape in the radial direction. A second storage hole is disposed between each of the pair of first storage holes. When viewed in the axial direction, the angle obtained by adding all center angles formed by connecting both circumferential ends of each second housing hole and the center axis is 55% or more and 70% or less with respect to the entire circumference of the rotor core.

Description

Technical Field

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

[0002] A conventional rotor includes a rotor core portion, a first magnet, and a second magnet. The rotor core portion has second insertion holes (first accommodation holes) extending in the axial direction and arranged in a plurality in the circumferential direction, and first insertion holes (second accommodation holes), and is cylindrical. The first magnet is accommodated in the first insertion hole. The second magnet is accommodated in the second insertion hole. When viewed in the axial direction, two of the second insertion holes are paired and separated as they face the radially outer side, and extend in a V shape in the radial direction. One first insertion hole is arranged between each pair of second insertion holes. (For example, refer to Patent Document 1) Prior Art Documents Patent Documents

[0003] Patent Document 1: WO 2018 / 159181 Summary of the Invention Technical Problem to be Solved by the Invention

[0004] However, although the conventional rotor is an invention aiming to improve the demagnetization resistance, it does not consider the electromagnetic excitation force generated by the electromagnetic force of the motor. Therefore, it may not be possible to obtain the most suitable torque while reducing the electromagnetic excitation force.

[0005] An object of the present invention is to provide a rotor that can obtain the most suitable torque while reducing the electromagnetic excitation force. Technical Solution for Solving the Technical Problem

[0006] An exemplary rotor of the present invention is rotatable about a central axis extending vertically, and has a cylindrical rotor core portion, a first magnet, and a second magnet. The rotor core portion has first accommodation holes and second accommodation holes extending in the axial direction and arranged in a plurality in the circumferential direction. The first magnet is accommodated in the first accommodation hole with first gaps provided on both radial sides. The second magnet is accommodated in the second accommodation hole with second gaps provided on both circumferential sides. When viewed in the axial direction, two of the first accommodation holes are paired and separated as they face the radially outer side, and extend in a V shape in the radial direction. One second accommodation hole is arranged between each pair of the first accommodation holes. When viewed in the axial direction, the sum of the central angles formed by connecting the circumferential ends of each second accommodation hole to the central axis is 55% or more and 70% or less with respect to the entire circumference of the rotor core portion. Advantages of the Invention

[0007] According to the exemplary present invention, it is possible to provide a rotor that can obtain the most suitable torque while reducing the electromagnetic excitation force. Brief Description of the Drawings

[0008] Figure 1is a longitudinal sectional view schematically showing a motor according to an embodiment of the present invention. Figure 2 is a cross-sectional view showing a part of a motor according to an embodiment of the present invention. Figure 3 is a cross-sectional view showing a magnified part of a motor according to an embodiment of the present invention. Figure 4 is a cross-sectional view showing a magnified part of a motor according to an embodiment of the present invention. Figure 5 is a graph showing the relationship between the ratio (%) of the angle θm to the entire circumference of the rotor core 110 and the electromagnetic exciting force (N) and torque (Nm) of the 24th harmonic component. Figure 6 is a graph showing the relationship between the ratio (%) of the angle θm to the entire circumference of the rotor core 110 and the electromagnetic exciting force (N) and torque (Nm) of the 48th harmonic component. Figure 7 is a graph showing the relationship between the ratio (%) of the angle θn to the entire circumference of the rotor core 110 and the 48th harmonic component and torque (Nm). DETAILED DESCRIPTION

[0009] Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the drawings. In addition, in this specification, the rotation axis of the motor 1 is referred to as the "central axis", and the direction parallel to the central axis C is referred to as the "axial direction". Further, the directions orthogonal to the central axis C of the motor 1 are respectively referred to as the "radial direction", and the direction along the arc centered on the central axis C of the motor 1 is referred to as the "circumferential direction". Moreover, in this application, the shape and positional relationship of each part are described with the axial direction as the up-down direction. In addition, the up-down direction is only a term used for convenience of description and does not limit the actual positional relationship and direction in the motor 1.

[0010] (1. Structure of the motor) A motor 1 according to an exemplary embodiment of the present invention will be described. Figure 1 is a longitudinal sectional view schematically showing the motor 1 according to an embodiment of the present invention, Figure 2 is a cross-sectional view showing a part of the motor 1. Figure 3 , Figure 4 is a cross-sectional view showing a magnified part of the motor 1. In addition, in Figure 2 , Figure 3 and Figure 4 , the illustration of the shaft 30 and the coil 23 is omitted.

[0011] The motor 1 includes a rotor 10, a stator 20, and a shaft 30. The shaft 30 is a columnar metal member that rotates about the central axis C extending in the up-down direction.

[0012] The stator 20 includes a housing 21, a stator core 22, and a coil 23. The housing 21 is formed in a cylindrical shape and houses the stator core 22. The housing 21 has a bottom plate portion 21a and a top plate portion 21b. The bottom plate portion 21a is disposed on the lower side in the axial direction of the stator core 22 and holds the lower bearing 23a. The top plate portion 21b is disposed on the upper side in the axial direction of the stator core 22 and holds the upper bearing 23b.

[0013] The lower bearing 23a and the upper bearing 23b rotatably support the shaft 30 on the housing 21.

[0014] The stator core 22 is formed by laminating a plurality of annular electromagnetic steel sheets in the axial direction. The stator core 22 has a core back 221 and teeth 222. That is, the stator 20 has a core back 221 and teeth 222. The core back 221 is in an annular shape, is disposed on the radially outer side of the rotor 10, and surrounds the central axis C. The teeth 222 protrude radially inward from the core back 221 and are arranged in m×6 (m is an integer) in the circumferential direction.

[0015] The plurality of teeth 222 are arranged at equal intervals in the circumferential direction around the central axis C. In the present embodiment, 48 teeth 222 are arranged.

[0016] The tooth 222 has a base portion 222a and an umbrella-shaped portion 222b (see Figure 3 ). The base portion 222a extends radially inward from the core back 221. The umbrella-shaped portion 222b protrudes from the radially inner end portion of the base portion 222a toward both circumferential sides. The circumferential length of the umbrella-shaped portion 222b is larger than the circumferential length at the radially inner end portion of the base portion 222a.

[0017] The radially inner surface of the umbrella-shaped portion 222b is a curved surface along the circumferential direction. When observed in the axial direction, the radially inner surface of the umbrella-shaped portion 222b is formed in an arc shape centered on the central axis C. The radially inner surface of the umbrella-shaped portion 222b faces the outer peripheral surface of the rotor core 110 described later with a gap in the radial direction. The circumferentially adjacent umbrella-shaped portions 222b are arranged with a slot 223 therebetween.

[0018] The coil 23 is formed by winding a wire around the tooth 222 with an insulator (not shown) interposed therebetween. Thus, the coil 23 is inserted into each slot 223. In the present embodiment, the coil 23 is wound in a distributed manner, and each coil 23 is wound across a plurality of teeth 222.

[0019] (2. Structure of the Rotor) The rotor 10 is rotatable about the central axis C extending vertically, and has 2×n (n is an integer) magnetic poles. The rotor 10 includes a rotor core 110, a plurality of first magnets 120a, 120b, and a plurality of second magnets 130.

[0020] The rotor core 110 is formed in a cylindrical shape by laminating annular electromagnetic steel sheets in the axial direction. The rotor core 110 has first receiving holes 111a, 111b, a second receiving hole 112, and a shaft hole 113. The shaft hole 113 extends in the axial direction and presses the shaft 30 into the inside thereof. Thereby, the shaft 30 is fixed to the rotor core 110.

[0021] The rotor core 110 has a plurality of magnetic pole portions 160N, 160S. The magnetic pole portion 160N has an N pole on the outer peripheral surface of the rotor core 110. The magnetic pole portion 160S has an S pole on the outer peripheral surface of the rotor core 110.

[0022] Each of the magnetic pole portions 160N, 160S is composed of a pair of first receiving holes 111a, 111b, a second receiving hole 112, a pair of first magnets 120a, 120b, and a second magnet 130.

[0023] In the present embodiment, four magnetic pole portions 160N and four magnetic pole portions 160S are provided respectively, and the rotor 10 has eight magnetic poles. The four magnetic pole portions 160N and the four magnetic pole portions 160S are alternately arranged in the circumferential direction. The structures of the magnetic pole portions 160N and 160S are the same except that the magnetic poles on the outer peripheral surface of the rotor core 110 are different and the circumferential positions are different. In addition, the number of magnetic poles of the rotor 10 is not limited to eight, and may be 2×n (n is an integer).

[0024] (3. Structure of the first receiving hole) The first receiving holes 111a, 111b extend in the axial direction and are arranged in plurality in the circumferential direction. In each of the magnetic pole portions 160N, 160S, the pair of first receiving holes 111a, 111b are arranged at intervals in the circumferential direction. In the present embodiment, the first receiving hole 111a and the first receiving hole 111b are symmetrically arranged in the circumferential direction with a magnetic pole center line d line therebetween when viewed in the axial direction. The magnetic pole center line d is an imaginary line that passes through the circumferential center of the second magnet 130 and the central axis C in each of the magnetic pole portions 160N, 160S and extends in the reference direction X.

[0025] In the present embodiment, when viewed in the axial direction, the magnetic pole center line d passes through the circumferential center of the tooth 222. Alternatively, the circumferential center of the tooth 222 may be arranged to deviate from the magnetic pole center line d in the circumferential direction.

[0026] The first receiving hole 111a is arranged on the circumferential side (the counterclockwise side when viewed in the axial direction) of the magnetic pole center line d. The first receiving hole 111b is arranged on the other circumferential side (the clockwise side when viewed in the axial direction) of the magnetic pole center line d. The first receiving hole 111a and the first receiving hole 111b are alternately arranged in the circumferential direction.

[0027] The first accommodation holes 111a and 111b extend in a direction in which they are circumferentially separated from each other as viewed axially along the direction from the radially inner side toward the radially outer side. Thus, the circumferential distance between the first accommodation hole 111a and the first accommodation hole 111b becomes larger as it goes from the radially inner side toward the radially outer side. That is, the first accommodation holes 111a and 111b are separated in pairs as they face toward the radially outer side (stator 20 side) and extend radially in a V shape as viewed axially.

[0028] (4. Structure of the second accommodation hole) The second accommodation holes 112 extend axially and a plurality of them are arranged circumferentially. One second accommodation hole 112 is arranged between each pair of the first accommodation holes 111a and 111b.

[0029] In the present embodiment, the second accommodation holes 112 are arranged at the radially outer end portion of the rotor core 110. As viewed axially, the second accommodation holes 112 extend in a substantially straight line along a direction orthogonal to the magnetic pole center line d, and are in a line-symmetrical shape with respect to the magnetic pole center line d.

[0030] One circumferential end of the second accommodation hole 112 (the end on the counterclockwise side as viewed axially) is arranged at a circumferential interval from the radially outer end of the first accommodation hole 111a. The other circumferential end of the second accommodation hole 112 (the end on the clockwise side as viewed axially) is arranged at a circumferential interval from the radially outer end of the first accommodation hole 111b.

[0031] In the present embodiment, as viewed axially, the central angle θa formed by connecting the two circumferential ends of the second accommodation hole 112 to the central axis C is equal to the central angle θb formed by connecting the two circumferential ends of the four teeth 222 arranged circumferentially to the central axis C (refer to Figure 3 ). Thus, the torque ripple of the rotor 10 can be reduced. Therefore, the motor 1 can be made to have low vibration and low noise. More specifically, the generated torque ripple is the synthesis of the ripples of a plurality of torques. In the present embodiment, the ripple of the torque of the multiple of eight pole numbers, that is, the 24th torque, is reduced. As a result, the synthesized torque ripple is reduced.

[0032] In addition, by making the central angle θa small, the circumferential widths of the second gaps 151 and 152 are also small. Thus, the flow of the magnetic fluxes of the first magnets 120a and 120b and the second magnet 130 is not easily obstructed by the second gaps 151 and 152. Therefore, the torque of the motor 1 increases as the central angle θa is made small. In addition, the 24th component of the electromagnetic exciting force acting between the rotor 10 and the stator 20 also increases as the central angle θa is made small (refer to Figure 5)。On the other hand, the electromagnetic exciting force of the 48th component acting between the rotor 10 and the stator 20 increases as the central angle θa is made smaller when the central angle θa is less than a specified value. However, when the central angle θa is greater than the specified value, it increases as the central angle θa is made larger (refer to Figure 6 ).

[0033] Preferably, the angle θm obtained by adding up all the central angles θa of the eight second receiving holes 112 (in this embodiment, θm = θa × 8) is 55% or more and 70% or less with respect to the entire circumference (360°) of the rotor core 110. Furthermore, it is more preferable that the angle θm is 67.5% or less with respect to the entire circumference of the rotor core 110.

[0034] When the angle θm is formed to be less than 55% with respect to the entire circumference of the rotor core 110, the rising rate of the torque decreases and the rising rate of the electromagnetic exciting force of the 24th component becomes larger (refer to Figure 5 ).

[0035] On the other hand, when the angle θm is formed to be greater than 70% with respect to the entire circumference of the rotor core 110, although the torque decreases, the electromagnetic exciting force of the 24th component increases (refer to Figure 5 ). Therefore, by making θm 55% or more and 70% or less with respect to the entire circumference of the rotor core 110, it is possible to obtain the most suitable torque while reducing the electromagnetic exciting force of the 24th component.

[0036] Furthermore, when the angle θm is formed to be greater than 67.5% with respect to the entire circumference of the rotor core 110, although the torque decreases, the rising rate of the electromagnetic exciting force of the 48th component becomes larger (refer to Figure 6 ). Therefore, by making θm 67.5% or less with respect to the entire circumference of the rotor core 110, it is possible to obtain the most suitable torque while reducing the electromagnetic exciting force of the 48th component.

[0037] (5. Structure of the first magnet and the second magnet) The first magnets 120a, 120b and the second magnet 130 are in the shape of a rectangular parallelepiped in this embodiment, and the type is not particularly limited. The first magnets 120a, 120b and the second magnet 130 can be, for example, neodymium magnets or ferrite magnets.

[0038] The first magnet 120a is received in the first receiving hole 111a with first gaps 141a, 142a provided on both sides in the radial direction. The first magnet 120b is received in the first receiving hole 111b with first gaps 141b, 142b provided on both sides in the radial direction. The second magnet 130 is received in the second receiving hole 112 with second gaps 151, 152 provided on both sides in the circumferential direction.

[0039] By increasing the central angle θc formed by connecting the circumferential ends of the second magnet 130 to the central axis C when viewed axially, the circumferential widths of the second gaps 151 and 152 become smaller (see Figure 3 ). At this time, the torque of the motor 1 increases as the central angle θc increases (see Figure 7 ). The electromagnetic vibration force of the 48th harmonic component increases as the central angle θc decreases when the central angle θc is less than the first specified value. In addition, the electromagnetic vibration force of the 48th harmonic component increases as the central angle θc increases when the central angle θc is greater than the second specified value (see Figure 7 ). The first specified value is less than the second specified value.

[0040] Preferably, the angle θn obtained by adding up all the central angles θc of the eight second magnets 130 (in this embodiment, θn = θc × 8) is 32.0% or more and 39.5% or less with respect to the entire circumference (360°) of the rotor core 110.

[0041] When the angle θn is formed to be less than 32.0% of the entire circumference of the rotor core 110, the torque decreases and the electromagnetic vibration force of the 48th harmonic component increases (see Figure 7 ). On the other hand, when the angle θn is formed to be greater than 39.5% of the entire circumference of the rotor core 110, the torque increases, but the electromagnetic vibration force of the 48th harmonic component also increases (see Figure 7 ). Therefore, by making θn 55% or more and 70% or less with respect to the entire circumference of the rotor core 110, it is possible to obtain the most suitable torque while further reducing the electromagnetic vibration force of the 48th harmonic component.

[0042] In each of the magnetic pole portions 160N and 160S, the magnetic poles on the radially outer side of the first magnets 120a and 120b are the same as the magnetic poles on the radially outer side of the second magnet 130. In addition, the magnetic poles on the radially inner side of the first magnets 120a and 120b are the same as the magnetic poles on the radially inner side of the second magnet 130.

[0043] The first magnets 120a and 120b have the same shape. When viewed axially, the first magnets 120a, 120b, and the second magnet 130 are rectangular. When viewed axially, the long sides of the first magnets 120a and 120b are arranged along the radial direction. The first magnets 120a and 120b are separated from each other in the circumferential direction as they go from the radially inner side to the radially outer side. When viewed axially, the first magnets 120a and 120b are symmetrically arranged with respect to the magnetic pole center line d. When viewed axially, the second magnet 130 is arranged such that its long side is orthogonal to the radial direction.

[0044] When viewed axially, the length of the short sides of the first magnets 120a and 120b (the circumferential width of the first magnets 120a and 120b) L1 is longer than the length of the short sides of the second magnet 130 (the radial width of the second magnet 130) L2 (see Figure 3 ). Thereby, the torque ripple of the rotor 10 can be further reduced.

[0045] In the first gaps 141a, 141b, 142a, 142b and the second gaps 151, 152, it is difficult for magnetic flux to pass through, and the flow of magnetic flux is suppressed. A non-magnetic part such as a resin part may be disposed inside the first gaps 141a, 141b, 142a, 142b and the second gaps 151, 152.

[0046] In the first accommodation holes 111a, the first gap 141a is disposed radially inside the first magnet 120a, and the first gap 142a is disposed radially outside the first magnet 120a. In the first accommodation hole 111b, the first gap 141b is disposed radially inside the first magnet 120b, and the first gap 142b is disposed radially outside the first magnet 120b.

[0047] In the present embodiment, the circumferential both side surfaces of the first magnets 120a and 120b are in contact with the inner surfaces of the first accommodation holes 111a and 111b over the entire axial direction. In addition, the radially inner side surfaces of the first magnets 120a and 120b are respectively exposed to the first gaps 141a and 141b. The radially outer side surfaces of the first magnets 120a and 120b are respectively exposed to the first gaps 142a and 142b.

[0048] The inner first gap 141a has a first inner peripheral surface 1411a and a second inner peripheral surface 1412a. The first inner peripheral surface 1411a is a plane orthogonal to the reference direction X (magnetic pole center line d) when viewed axially.

[0049] The second inner peripheral surface 1412a is continuously provided adjacent to the first inner peripheral surface 1411a in the circumferential direction, and is a plane orthogonal to the circumferential side surface of the first magnet 120a when viewed axially (see Figure 4 ). That is, the second inner peripheral surface 1412a is orthogonal to the following side surface: the side surface of the outer periphery of the first magnet 120a that is inclined in a direction away from the magnetic pole center line d. The second inner peripheral surface 1412a is located at a position radially outside the radially inner end of the first magnet 120a. Thereby, the radially inner end of the first magnet 120a protrudes into the inner first gap 141a.

[0050] The inner first gap 141b has a first inner peripheral surface 1411b and a second inner peripheral surface 1412b. The first inner peripheral surface 1411b is a plane orthogonal to the reference direction X (magnetic pole center line d) when viewed axially.

[0051] The second inner circumferential surface 1412b is continuously provided adjacent to the first inner circumferential surface 1411b in the circumferential direction, and is a plane orthogonal to the circumferential side surface of the first magnet 120b when viewed axially (see Figure 4 ). That is, the second inner circumferential surface 1412b is orthogonal to the following side surface: the side surface of the outer circumference of the first magnet 120a inclined in the direction away from the magnetic pole center line d. The second inner circumferential surface 1412b is located at a position radially outside the radially inner end of the first magnet 120b. Thus, the radially inner end of the first magnet 120b protrudes into the first gap 141b on the inner side. Therefore, the torque ripple of the rotor 10 can be further reduced.

[0052] In addition, when viewed axially, the radial lengths L3 of the outer first gaps 142a and 142b are greater than 1 / 2 of the radial length (the length of the long side of the first magnets 120a and 120b) L4 of the first magnet 120a (see Figure 4 ). Thus, the torque ripple of the rotor 10 can be further reduced.

[0053] The second gap 151 is disposed on the circumferential side (the counterclockwise side when viewed axially) of the second magnet 130 in the second receiving hole 112. The second gap 152 is disposed on the other circumferential side (the clockwise side when viewed axially) of the second magnet 130 in the second receiving hole 112.

[0054] Both radial side surfaces of the second magnet 130 are in contact with the inner surface of the second receiving hole 112 throughout the entire axial direction. In addition, one circumferential side of the second magnet 130 is exposed to the second gap 151. The other circumferential side of the second magnet 130 is exposed to the second gap 152.

[0055] In the present embodiment, the second magnet 130 is disposed between the first magnets 120a and 120b in the circumferential direction, and is located at a position radially outside the radially outer ends of the first magnets 120a and 120b.

[0056] In addition, in each of the magnetic pole portions 160N and 160S, the circumferential both ends P1 of the second magnet 130 projected onto the imaginary reference plane T perpendicular to the reference direction X are located on the circumferentially inner side of the circumferential inner ends P2 of the pair of first magnets 120a and 120b projected onto the reference plane T. That is, when viewed axially, the distance between the magnetic pole center line d and the circumferential outer end of the second magnet 130 is smaller than the distance between the magnetic pole center line d and the circumferential inner ends of the first magnets 120a and 120b.

[0057] In addition, the circumferential both ends P3 of the second receiving hole 112 projected onto the reference plane T overlap with the first magnets 120a and 120b projected onto the reference plane T (perpendicular Figure 3)。Thus, the torque ripple of the rotor 10 can be further reduced.

[0058] In addition, the circumferential distance W1 between the circumferentially adjacent first gap 142a and the second gap 151 is greater than the circumferential distance W2 between the circumferentially adjacent first gaps 142a and 142b (see Figure 4 )。Thus, the torque ripple of the rotor 10 can be further reduced.

[0059] In addition, the radial distance W3 between the radially outer end of the second magnet 130 and the outer peripheral edge of the rotor core 110 is longer than the radial distance W4 between the radially inner end of the tooth 222 and the outer peripheral edge of the rotor core 110. In addition, the distance W3 is longer than the radial distance W5 between the circumferentially outer ends of the second gaps 151 and 152 and the outer peripheral edge of the rotor core 110. In addition, the distance W3 is longer than the radial distance W6 between the radially outer ends of the first gaps 142a and 142b and the outer peripheral edge of the rotor core 110. Thus, the torque ripple of the rotor 10 can be further reduced.

[0060] Next, regarding the effects of the present invention, samples are used for further detailed description. In the motors 1 of Samples A to D, 48 teeth 222 are arranged, and four magnetic pole portions 160N and four magnetic pole portions 160S are provided respectively. The four magnetic pole portions 160N and the four magnetic pole portions 160S are alternately arranged in the circumferential direction.

[0061] The angle θn obtained by adding up all the central angles θc of the eight second magnets 130 in Sample A is 34% with respect to the entire circumference of the rotor core 110. The angle θn in Sample B is 36.5% with respect to the entire circumference of the rotor core 110. The angle θn in Sample C is 39% with respect to the entire circumference of the rotor core 110.

[0062] Figure 5 The relationships between the ratio (%) of the angle θm with respect to the entire circumference of the rotor core 110 and the 24th-order component of the electromagnetic exciting force (N) and the ratio (%) of the angle θm with respect to the entire circumference of the rotor core 110 and the torque (Nm) when the motors 1 of Samples A to C are rotated at a low speed (3000 rpm) are shown. Figure 5 In, the relationship between the ratio (%) of the angle θm with respect to the entire circumference of the rotor core 110 and the 24th-order component of the electromagnetic exciting force (N) is represented by a solid line, and the relationship between the ratio (%) of the angle θm with respect to the entire circumference of the rotor core 110 and the torque (Nm) is represented by a dashed line. Thus, the changes in the torque and the 24th-order component of the electromagnetic exciting force when the circumferential width of the second receiving hole 112 is changed are shown.

[0063] In addition, Figure 6Shows the relationship between the ratio (%) of the angle θm to the full circumference of the rotor core 110 and the electromagnetic excitation force (N) of the 48th harmonic component, and the relationship between the ratio (%) of the angle θm to the full circumference of the rotor core 110 and the torque (Nm) when the motor 1 of samples A to C rotates at a low speed (3000 rpm). Figure 6 Among them, the relationship between the ratio (%) of the angle θm to the full circumference of the rotor core 110 and the electromagnetic excitation force (N) of the 48th harmonic component is represented by a solid line, and the relationship between the ratio (%) of the angle θm to the full circumference of the rotor core 110 and the torque (Nm) is represented by a dashed line. Thus, the changes in torque and the electromagnetic excitation force of the 48th harmonic component when the circumferential width of the second receiving hole 112 is changed are shown.

[0064] The angle θm of sample D is 65% of the full circumference of the rotor core 110. Figure 7 Shows the relationship between the ratio (%) of the angle θn to the full circumference of the rotor core 110 and the electromagnetic excitation force (N) of the 48th harmonic component, and the relationship between the ratio (%) of the angle θn to the full circumference of the rotor core 110 and the torque (Nm) when the motor 1 of sample D rotates at a low speed (3000 rpm). Figure 7 Among them, the relationship between the ratio (%) of the angle θn to the full circumference of the rotor core 110 and the electromagnetic excitation force (N) of the 48th harmonic component is represented by a solid line, and the relationship between the ratio (%) of the angle θn to the full circumference of the rotor core 110 and the torque (Nm) is represented by a dashed line. Thus, the changes in torque and the electromagnetic excitation force of the 48th harmonic component when the circumferential width of the second receiving hole 112 is constant and the circumferential width of the second magnet 130 is changed are shown.

[0065] From Figure 5 It can be clarified that in the motor 1 of sample A, when the angle θm is formed to be less than 55% of the full circumference of the rotor core 110, the rising rate of torque in sample A decreases, and the rising rate of the electromagnetic excitation force of the 24th harmonic component increases.

[0066] In addition, in the motor 1 of sample A, when the angle θm is formed to be greater than 70% of the full circumference of the rotor core 110, although the torque decreases, the electromagnetic excitation force of the 24th harmonic component increases. Therefore, by making θm 55% or more and 70% or less of the full circumference of the rotor core 110, the most suitable torque can be obtained while reducing the electromagnetic excitation force of the 24th harmonic component.

[0067] From Figure 6It is clear that in the motor 1 of sample C, when the angle θm is formed to be greater than 67.5% of the full circle of the rotor core 110, although the torque decreases in sample C, the rising rate of the electromagnetic exciting force of the 48th harmonic component becomes larger. Therefore, by making θm 67.5% or less of the full circle of the rotor core 110, it is possible to obtain the most suitable torque while reducing the electromagnetic exciting force of the 48th harmonic component.

[0068] From Figure 7 It is clear that in the motor 1 of sample D, when the angle θn is formed to be less than 32.0% of the full circle of the rotor core 110, the torque decreases and the electromagnetic exciting force of the 48th harmonic component increases. On the other hand, when the angle θn is formed to be greater than 39.5% of the full circle of the rotor core 110, the torque increases, but the electromagnetic exciting force of the 48th harmonic component also increases. Therefore, by making θn 55% or more and 70% or less of the full circle of the rotor core 110, it is possible to obtain the most suitable torque while further reducing the electromagnetic exciting force of the 48th harmonic component.

[0069] <6. Other> Above, the embodiments of the present invention have been described. In addition, the scope of the present invention is not limited to the above embodiments. The present invention can be implemented with various modifications added without departing from the gist of the invention. Moreover, the above embodiments can be combined arbitrarily as appropriate. For example, in the present embodiment, when viewed axially, the central angle θa formed by connecting the circumferential ends of the second receiving hole 112 to the central axis C is equal to the central angle θb formed by connecting the circumferential ends of the four teeth 222 arranged in the circumferential direction to the central axis C, but the central angle θa and the central angle θb may also be different.

[0070] <7. Supplementary Note> As described above, a rotor 10 according to one embodiment of the present disclosure can rotate about a central axis C extending vertically. The rotor includes: a rotor core portion 110, which has first accommodation holes 111a, 111b and a second accommodation hole 112 that extend axially and are arranged circumferentially in plurality, and has a cylindrical shape; first magnets 120a, 120b, which are accommodated in the first accommodation holes in such a manner that first gaps 141a, 141b, 142a, 142b are provided on both radial sides; and a second magnet 130, which is accommodated in the second accommodation hole in such a manner that second gaps 151, 152 are provided on both circumferential sides. When viewed axially, two of the first accommodation holes are paired and separated toward the radial outside and extend in a V shape in the radial direction. One second accommodation hole is arranged between a pair of the first accommodation holes. When viewed axially, an angle θm obtained by adding up all the central angles θa formed by connecting the circumferential ends of each of the second accommodation holes to the central axis is 55% or more and 70% or less with respect to the entire circumference of the rotor core portion (first structure).

[0071] In addition, in the above first structure, when viewed axially, an angle θm obtained by adding up all the central angles θa formed by connecting the circumferential ends of each of the second accommodation holes to the central axis is 67.5% or less with respect to the entire circumference of the rotor core portion (second structure).

[0072] In addition, in the above first or second structure, when viewed axially, an angle θn obtained by adding up all the central angles θc formed by connecting the circumferential ends of each of the second magnets to the central axis is 32.0% or more and 39.5% or less with respect to the entire circumference of the rotor core portion (third structure).

[0073] In addition, in any one of the above first to third structures, it may be configured that when viewed axially, circumferential ends P1 of the second magnet projected onto a reference plane T perpendicular to a magnetic pole center line d passing through the circumferential center of the second magnet and the central axis are located on the circumferentially inner side of circumferential inner ends P2 of a pair of the first magnets projected onto the reference plane (fourth structure).

[0074] In addition, in the above fourth structure, it may be configured that circumferential ends P3 of the second accommodation hole projected onto the reference plane overlap with the first magnets projected onto the reference plane (fifth structure).

[0075] In addition, in any one of the above first to fifth structures, it may be configured that a circumferential distance W1 between the first gap arranged on the radial outside of the first magnet and the second gap circumferentially adjacent to the first gap is longer than a circumferential distance W2 between the circumferentially adjacent first gaps arranged on the radial outside of the first magnet (sixth structure).

[0076] In addition, in any one of the first to sixth structures described above, it may also be configured such that the circumferential width L1 of the first magnet is larger than the radial width L2 of the second magnet (seventh structure).

[0077] In addition, in any one of the first to seventh structures described above, it may also be configured such that the first gap disposed radially inside the first magnet has: first inner circumferential surfaces 1411a and 1411b, which are orthogonal to a magnetic pole center line passing through the circumferential center of the second magnet and the central axis when viewed axially; and second inner circumferential surfaces 1412a and 1412b, which are continuously provided adjacent to the first inner circumferential surfaces in the circumferential direction and are orthogonal to the circumferential side surfaces of the first magnet when viewed axially (eighth structure).

[0078] In addition, in any one of the first to eighth structures described above, it may also be configured such that the radial length L3 of the first gap disposed radially outside the first magnet is greater than 1 / 2 of the radial length L4 of the first magnet (ninth structure).

[0079] In addition, in any one of the first to ninth structures described above, it may also be configured such that the radial distance W3 between the radially outer end of the second magnet and the outer peripheral edge of the rotor core is longer than the radial distance W4 between the radially inner end of the tooth and the outer peripheral edge of the rotor core, and is longer than the radial distance W5 between the circumferentially outer end of the second gap and the outer peripheral edge of the rotor core, and is longer than the radial distance W6 between the radially outer end of the first gap disposed radially outside the first magnet and the outer peripheral edge of the rotor core (tenth structure). Industrial Applicability

[0080] The present invention can be used, for example, in electric devices equipped with motors, automobiles, ships, aircraft, trains, electric assist bicycles, wind power generators, etc. Reference Signs

[0081] 1 Motor 10 Rotor 20 Stator 21 Housing 21a Bottom Plate Portion 21b Top Plate Portion 22 Stator Core 23 Coil 23a Lower Bearing 23b Upper Bearing 30 Shaft 100 Motor 110 Rotor Core 111a, 111b First receiving holes 112 Second receiving hole 113 Axial hole 120a, 120b First magnets 121a Inner circumferential side surface 130 Second magnet 141a, 141b, 142a, 142b First gaps 1411a, 1411b First inner circumferential surfaces 1412a, 1412b Second inner circumferential surfaces 151, 152 Second gaps 160N, 160S Pole parts 221 Core back 222 Teeth 222a Base parts 222b Umbrella-shaped parts 223 Grooves C Central axis L1, L2, L3, L4 Lengths T Reference plane W1, W2, W3, W4, W5 Widths X Reference direction d Magnetic pole center line θa, θb, θc Central angles θm, θn Angles

Claims

1. A rotor, The rotor is capable of rotating about a central axis extending vertically, characterized in that, having: a cylindrical rotor core having first receiving holes and second receiving holes that extend in the axial direction and are arranged in a plurality in the circumferential direction; a first magnet received in the first receiving hole with first gaps provided on both radial sides; and a second magnet received in the second receiving hole with second gaps provided on both circumferential sides, when viewed in the axial direction, two of the first receiving holes are paired and separated as they face the radially outer side and extend in a V shape in the radial direction, one of the second receiving holes is arranged between each pair of the first receiving holes, when viewed in the axial direction, the sum of the central angles formed by connecting the circumferential ends of each of the second receiving holes to the central axis is 55% or more and 70% or less with respect to the entire circumference of the rotor core.

2. The rotor according to claim 1, wherein when viewed in the axial direction, the sum of the central angles formed by connecting the circumferential ends of each of the second receiving holes to the central axis is 67.5% or less with respect to the entire circumference of the rotor core.

3. The rotor according to claim 1 or 2, wherein when viewed in the axial direction, the sum of the central angles formed by connecting the circumferential ends of each of the second magnets to the central axis is 32.0% or more and 39.5% or less with respect to the entire circumference of the rotor core.

4. The rotor according to claim 1 or 2, wherein when viewed in the axial direction, the circumferential ends of the second magnet projected onto a reference plane are located at a position circumferentially inside the circumferential inner ends of the pair of first magnets projected onto the reference plane, and the reference plane is perpendicular to the magnetic pole center line passing through the circumferential center of the second magnet and the central axis.

5. The rotor according to claim 4, wherein the circumferential ends of the second receiving hole projected onto the reference plane overlap with the first magnets projected onto the reference plane.

6. The rotor according to claim 1 or 2, wherein the circumferential distance between the first gap arranged on the radially outer side of the first magnet and the second gap circumferentially adjacent to the first gap is longer than the circumferential distance between the circumferentially adjacent first gaps arranged on the radially outer side of the first magnet.

7. The rotor according to claim 1 or 2, wherein the circumferential width of the first magnet is larger than the radial width of the second magnet.

8. The rotor according to claim 1 or 2, wherein the first gap arranged on the radially inner side of the first magnet has: a first inner circumferential surface that is orthogonal to the magnetic pole center line passing through the circumferential center of the second magnet and the central axis when viewed in the axial direction; and a second inner circumferential surface that is continuously arranged adjacent to the first inner circumferential surface in the circumferential direction and is orthogonal to the circumferential side surface of the first magnet when viewed in the axial direction.

9. The rotor according to claim 1 or 2, wherein The radial length of the first gap disposed radially outside the first magnet is greater than 1 / 2 of the radial length of the first magnet.

10. The rotor according to claim 1 or 2, characterized in that the radial distance between the radially outer end of the second magnet and the outer peripheral edge of the rotor core is longer than the radial distance between the radially inner end of the tooth and the outer peripheral edge of the rotor core, and is longer than the radial distance between the circumferentially outer end of the second gap and the outer peripheral edge of the rotor core, and is longer than the radial distance between the radially outer end of the first gap disposed radially outside the first magnet and the outer peripheral edge of the rotor core.

Images