Rotor and motor

[0022] <1. The first embodiment>

[0023] <1-1. Structure of motor>

[0024] figure 1 It is a longitudinal cross-sectional view of the motor 1 of the first embodiment. The motor 1 is used in home appliances such as air conditioners and washing machines, for example. However, the motor 1 of the present invention can also be used for applications other than household appliances. For example, the motor 1 of the present invention may be mounted on transportation equipment such as automobiles or rail vehicles, OA equipment, medical equipment, tools, large industrial equipment, etc., to generate various driving forces.

[0025] This motor 1 is a so-called inner rotor type motor in which a rotor 32 is arranged on the radially inner side of a stator 21. Such as figure 1 As shown, the motor 1 has a stationary part 2, a rotating part 3, an upper bearing part 71 and a lower bearing part 72. The stationary part 2 is fixed to the frame of the device in which the motor 1 is mounted. The rotating part 3 is supported via the upper bearing part 71 and the lower bearing part 72 so as to be rotatable with respect to the central axis 9 extending up and down of the stationary part 2.

[0026] The stationary part 2 has a stator 21, a housing 22 and a cover 23.

[0027] The stator 21 is an armature that generates magnetic flux in accordance with a drive current supplied from an external power source through a circuit board (not shown) provided in the motor 1. The stator 21 is arranged on the radially outer side of the rotor 32 and surrounds the rotor 32 in a ring shape. The stator 21 has a stator core 211, an insulator 212 and a plurality of coils 213.

[0028] The stator core 211 is formed of, for example, laminated steel plates formed by laminating a plurality of electromagnetic steel plates in the axial direction. The stator core 211 is a magnetic body having an annular core back 41 and a plurality of teeth 42 protruding radially inward from the core back 41. The core back 41 and the central axis 9 are arranged substantially coaxially. In addition, the outer peripheral surface of the core back 41 is fixed to the inner peripheral surface of the side wall 221 described later of the housing 22. As a result, the entire stator 21 is fixed to the housing 22. The plurality of teeth 42 are arranged at substantially equal intervals in the circumferential direction.

[0029] The insulating member 212 is formed of resin as an insulator. The upper surface, the lower surface, and both end surfaces in the circumferential direction of each tooth 42 are covered by the insulating member 212. The coil 213 is composed of a conductive wire wound around the plurality of teeth 42 via an insulating member 212. The insulating member 212 is interposed between the tooth 42 and the coil 213, thereby preventing the tooth 42 and the coil 213 from being electrically short-circuited. In addition, instead of the insulator 212, the surface of the teeth 42 may be coated with insulation.

[0030] The housing 22 is a container that holds the stator 21. The housing 22 has a substantially cylindrical side wall 221 and a bottom 222 closing the lower portion of the side wall 221. The side wall 221 extends from the outer peripheral portion of the bottom 222 toward the upper side in the axial direction, and extends in a cylindrical shape in the axial direction with the center axis 9 as the center. In addition, a recess 223 for arranging the lower bearing portion 72 is provided around the center axis 9 of the bottom 222 of the housing 22.

[0031] The cover 23 covers the opening of the upper part of the housing 22. The lower surface of the cover 23 is fixed to the upper end of the housing 22 by bonding, screw fastening, or the like. The stator 21 and the rotor 32 are housed in an internal space surrounded by the housing 22 and the cover 23. A circular hole 231 for arranging the upper bearing portion 71 is provided around the center axis 9 of the cover 23. The circular hole 231 penetrates the center of the cover 23 in the axial direction.

[0032] The rotating part 3 has a shaft 31 and a rotor 32.

[0033] The shaft 31 is a cylindrical member extending in the vertical direction along the central axis 9. The material of the shaft 31 is stainless steel, for example. The shaft 31 is inserted into the radially inner side of the inner core portion 50 of the rotor 32 described later, and is fixed to the inner peripheral surface of the inner core portion 50 by press-fitting. However, the outer peripheral surface of the shaft 31 may be fixed to the inner peripheral surface of the inner core portion 50 by other methods such as adhesion or thermo-compression fitting. In addition, the inner ring 712 of the upper bearing portion 71 and the inner ring 722 of the lower bearing portion 72 are respectively fixed to the outer peripheral surfaces of the upper and lower portions of the shaft 31 by press fitting or the like. Thereby, the shaft 31 and the rotor 32 can rotate about the center axis 9 with respect to the stationary part 2 including the housing 22 while being supported by the upper bearing portion 71 and the lower bearing portion 72. In addition, the shaft 31 has a head 311 protruding upward from the cover 23. The head 311 is connected to a part to be driven via a power transmission mechanism such as a gear.

[0034] The rotor 32 extends in a cylindrical shape along the central axis 9 around the shaft 31. The rotor 32 is fixed to the outer peripheral surface of the shaft 31 and can rotate with the shaft 31 around the central axis 9. In addition, the rotor 32 is arranged on the radially inner side of the stator 21. The outer peripheral surface of the rotor 32 and the radially inner end surface of the teeth 42 of the stator 21 are opposed to each other in the radial direction with a small gap therebetween.

[0035] figure 2 It is a plan view of the rotor 32 of the first embodiment. Such as figure 1 with figure 2 As shown, the rotor 32 has a rotor core 321, a plurality of (ten in this embodiment) magnets 322 and a resin part 323. But when figure 2 Here, the illustration of the resin portion 323 is omitted.

[0036] The rotor core 321 is a cylindrical member surrounding the shaft 31. The rotor core 321 is composed of a plurality of thin-plate cores 500 of electromagnetic steel sheets as magnetic materials. A plurality of thin-plate cores 500 are laminated in the axial direction to form a laminated steel plate. If laminated steel plates are used, eddy currents generated in the rotor core 321 can be suppressed. Therefore, the magnetic flux can efficiently flow in the rotor core 321. An insertion hole 320 extending in the axial direction is provided in the center of an inner core portion 50 described later of the rotor core 321. The shaft 31 is pressed into the insertion hole 320 of the rotor core 321. A more detailed structure of the rotor core 321 will be described later.

[0037] The plurality of magnets 322 are arranged at substantially equal intervals from each other in the circumferential direction around the center axis 9. In this embodiment, a substantially rectangular parallelepiped magnet 322 is used. In addition, the plurality of magnets 322 are respectively housed in the magnet insertion space 510 and fixed to the iron core magnetic pole portion 51 by bonding or the like. The magnet insertion space 510 is provided in an adjacent iron core of the rotor iron core 321, which will be described later. Between the magnetic poles 51. In addition, the corners of the magnet 322 may be chamfered or tapered.

[0038] Such as figure 2 As shown, the rotor 32 of the present invention has a spoke-type rotor structure. That is, the plurality of magnets 322 are respectively arranged such that the pair of magnetic pole surfaces 324 respectively face the circumferential direction. In addition, adjacent magnets 322 are arranged to face each other with the same pole. According to this structure, the area of ​​the magnetic pole surface 324 of the magnet 322 can be ensured to be larger, and more magnetic flux can be used (refer to figure 2 Dotted arrow in).

[0039] The resin part 323 is formed by injection molding of resin in which at least a part of the rotor core 321 and the plurality of magnets 322 are used as insert members. The resin part 323 includes an upper resin part 91, a lower resin part 92 and a plurality of columnar resin parts 93. The upper resin portion 91 covers the upper surface of the plurality of iron core magnetic pole portions 51 of the rotor core 321 and the upper surface of the plurality of magnets 322. The lower resin portion 92 covers the lower surfaces of the plurality of iron core magnetic pole portions 51 and the lower surfaces of the plurality of magnets 322. Each columnar resin portion 93 connects the upper resin portion 91 and the lower resin portion 92 in the axial direction. In addition, a part of the columnar resin portion 93 covers the radially outer surface of the plurality of magnets 322. Thereby, the fixing strength of the plurality of magnets 322 is improved, and the plurality of magnets 322 are prevented from jumping out to the upper side, the lower side, and the radially outer side. In addition, through the entire resin portion 323, the rigidity of the entire rotor 32 is improved.

[0040] The upper bearing portion 71 and the lower bearing portion 72 are arranged between the housing 22 and the cover 23 and the shaft 31. For the upper bearing portion 71 and the lower bearing portion 72 of the present embodiment, ball bearings in which the outer ring and the inner ring are relatively rotated via a ball are used. However, instead of ball bearings, other types of bearings such as sliding bearings or fluid bearings can also be used.

[0041] The outer ring 711 of the upper bearing portion 71 is arranged in the circular hole 231 of the cover 23 and is fixed to the cover 23. In addition, the outer ring 721 of the lower bearing portion 72 is arranged in the recess 223 of the housing 22 to be fixed to the housing 22. On the other hand, the inner ring 712 of the upper bearing portion 71 and the inner ring 722 of the lower bearing portion 72 are fixed to the shaft 31. Thereby, the shaft 31 is supported so as to be rotatable with respect to the housing 22 and the cover 23.

[0042] In such a motor 1, when a drive current is supplied from an external power source to the coil 213 of the stationary part 2 via the above-mentioned wire, a radial magnetic flux is generated in the plurality of teeth 42 of the stator core 211. Then, the circumferential torque is generated by the action of the magnetic flux between the teeth 42 and the rotor 32. As a result, the rotating part 3 rotates about the central axis 9 with respect to the stationary part 2.

[0043] <1-2. Detailed structure of rotor core>

[0044] Next, a more detailed structure of the rotor core 321 will be described. image 3 It is a partial plan view of the rotor 32 of the first embodiment.

[0045] Such as figure 2 with image 3 As shown, the rotor core 321 of this embodiment has an inner core portion 50, a plurality of (10 in this embodiment) core magnetic pole portions 51, a circumferential connection portion 52, and a plurality of (in this embodiment) There are 10) radial connection portions 53 and a plurality of (20 in this embodiment) protrusion portions 54.

[0046] The inner core portion 50 is fixed to the outer peripheral surface of the shaft 31 and extends in a cylindrical shape in the axial direction along the central axis 9. When the inner core part 50 forms the resin part 323 by resin injection molding, it is connected with the plurality of core magnetic pole parts 51, the circumferential connection part 52, the plurality of radial connection parts 53, the plurality of protrusions 54 and the plurality of magnets 322. The parts are embedded in the resin part 323 together. Thereby, the inner iron core portion 50 is fixed to the plurality of iron core magnetic pole portions 51, the circumferential connection portion 52, the plurality of radial connection portions 53, the plurality of protrusion portions 54, and the plurality of magnets 322.

[0047] The plurality of core magnetic pole portions 51 are arranged at substantially equal intervals from each other in the circumferential direction around the center axis 9. When viewed in the axial direction, each core magnetic pole portion 51 has a fan shape. The circumferential connection portion 52 expands in an annular shape with the center axis 9 as the center at a position radially inward of the plurality of core magnetic pole portions 51 and the plurality of magnets 322. The plurality of radial connection portions 53 respectively connect the plurality of core magnetic pole portions 51 and the circumferential connection portion 52 in the radial direction. Each radial connection portion 53 is connected to the vicinity of the central portion of each core magnetic pole portion 51 in the circumferential direction.

[0048] In addition, at a position radially outward from the circumferential connection portion 52 and radially inward from the plurality of core magnetic pole portions 51, the two protruding portions 54 respectively extend from the plurality of radial connection portions 53 to opposite sides in the circumferential direction. prominent. In addition, each protrusion 54 is in contact with the radially inner surface of the magnet 322. As a result, the magnet 322 is positioned radially inward by each protrusion 54. In the rotor core 321 of the present embodiment, a circumferential gap 55 surrounded by each core magnetic pole portion 51, each radial connection portion 53, each protrusion 54 and each magnet 322 is formed. One columnar resin part among the plurality of columnar resin parts 93 is filled in the circumferential gap part 55. However, the circumferential gap 55 may be a gap. When viewed in the axial direction, the radially inner corner portion 511 of the circumferential side surface of the magnet 322 faces the circumferential gap portion 55.

[0049] Figure 4 It is a partial plan view showing the result of analyzing the flow of magnetic flux in the rotor 32 (excluding the inner core portion 50) and the stator 21 of the present embodiment. As a comparative example, Figure 5 It is a partial plan view showing the result of analyzing the flow of magnetic flux in the conventional rotor (excluding the inner core portion) and the stator. in Figure 4 with Figure 5 In the figure, the flow of magnetic flux obtained as a result of the analysis is illustrated with a fine arrow.

[0050] Such as Figure 4 with Figure 5 As shown, in the motor 1 having the rotor 32 of the present embodiment, the magnetic flux flowing to the stator 21 side is increased compared to the motor having the conventional rotor. That is, it can be seen that the induced voltage for generating the torque of the motor 1 is increased. This is because, in the present embodiment, the radially inner corner 511 of the circumferential side surface of the magnet 322 does not face the rotor core 321, but faces a gap or air that contains a resin with a large magnetic resistance. The circumferential gap portion 55 of the gap. As a result, compared to the case where the corner of the magnet is brought into contact with the rotor core as in the conventional rotor, it is possible to suppress a part of the magnetic flux generated from the portion of the magnet 322 including the vicinity of the corner 511 at the corner. Around 511 circulates or flows radially inward via the rotor core 321.

[0051] In addition, when viewed in the axial direction, the circumferential gap portion 55 of the present embodiment is inclined radially outward as it goes toward the central portion of the core magnetic pole portion 51 in the circumferential direction. Thereby, the magnetic flux generated from the portion of the circumferential side surface of the magnet 322 including the vicinity of the radially inner corner portion 511 can be directed toward the radially outer stator 21 side. As a result, the induced voltage generated by the action of the magnetic flux between the rotor 32 and the stator 21 can be further increased, and the torque of the motor 1 can be improved. In addition, in this embodiment, a structure is adopted in which the portion of the magnet 322 forming the corner portion 511 reliably faces the circumferential gap portion 55 in the circumferential direction. As a result, the magnetic flux generated from the magnet 322 can be more directed toward the stator 21 on the radially outer side.

[0052] In addition, in this embodiment, the two protruding portions 54 respectively protrude from the plurality of radial connection portions 53 to both sides in the circumferential direction. In addition, each protrusion 54 does not contact the circumferential side surface of the magnet 322, but contacts the end surface on the inner side in the radial direction. Thereby, the magnetic flux generated from the corners 511 on both sides of the circumferential side surface of the magnet 322 on the radially inner side can be directed toward the stator 21 on the radially outer side. In addition, the magnetic flux distribution in the core magnetic pole portion 51 can be made uniform on both sides in the circumferential direction, and the magnetic unbalance can be suppressed. Thereby, the rotating part 3 of the motor 1 can be rotated more smoothly. However, it is also possible to adopt a structure in which only one protrusion 54 respectively protrudes from the plurality of radial connection portions 53 to one side in the circumferential direction.

[0053] <2. The second embodiment>

[0054] Next, the second embodiment of the present invention will be described. In addition, the following description will focus on the differences from the first embodiment, and overlapping descriptions of the same parts as the first embodiment will be omitted.

[0055] Image 6 It is a plan view of the rotor 32B of the second embodiment. But when Image 6 In this, illustration of the resin part is omitted. Figure 7 It is a partial plan view of the rotor 32B of the second embodiment. Such as Image 6 with Figure 7 As shown, the rotor 32B has a rotor core 321B, a plurality of (ten in this embodiment) magnets 322B, and a resin part. But when Image 6 with Figure 7 In this, illustration of the resin part is omitted.

[0056] The rotor core 321B has an inner core portion 50B, a plurality of (10 in this embodiment) core magnetic pole portion 51B, a circumferential connection portion 52B, and a plurality of (10 in this embodiment) radially connected The portion 53B and a plurality of (20 in this embodiment) protrusion portions 54B. In addition, in the rotor core 321B of the present embodiment, a circumferential gap portion 55B surrounded by each core magnetic pole portion 51B, each radial connection portion 53B, each protrusion 54B, and each magnet 322B is formed. The circumferential gap portion 55B is a gap or void in which the resin forming the resin portion is sandwiched. In addition, when viewed in the axial direction, the radially inner corner portion 511B of the circumferential side surface of the magnet 322B faces the circumferential gap portion 55B. In addition, the inner core portion 50B, the plurality of core magnetic pole portions 51B, the circumferential connection portion 52B, the radial connection portion 53B, the plurality of protruding portions 54B, the circumferential gap portion 55B, the plurality of magnets 322B, and the resin of the present embodiment The parts respectively have the inner core part 50, the plurality of core magnetic pole parts 51, the circumferential connection portion 52, the radial connection portion 53, the plurality of protrusions 54, the circumferential gap portion 55, and the plurality of magnets of the first embodiment. 322 and the resin part 323 have the same structure.

[0057] In addition, the rotor core 321B of the present embodiment is provided with a radial gap portion 56B, which is a gap extending radially outward from a part of the inner peripheral surface of each core magnetic pole portion 51B. The radial gap portion 56B is connected to the circumferential inner end portion of the circumferential gap portion 55B of the core magnetic pole portion 51B, and extends in the radial direction.

[0058] Figure 8 It is a partial plan view showing the result of analyzing the flow of magnetic flux in the rotor 32B (excluding the inner core portion 50B) and the stator of the present embodiment. in Figure 8 In the figure, the flow of magnetic flux obtained as a result of the analysis is illustrated with a fine arrow.

[0059] Such as Figure 8 As shown, in the motor having the rotor 32B of the present embodiment, compared with the conventional rotor ( Figure 5 ) Motor increases the magnetic flux flowing to the stator side. That is, it can be seen that the induced voltage for generating the torque of the motor is increased. As in the first embodiment, the radially inner corner 511B of the circumferential side surface of the magnet 322B does not face the rotor core 321B, but faces the circumference of the gap between the resin with large magnetic resistance or the gap between the air. To the gap 55B. As a result, compared to the case where the corner of the magnet is brought into contact with the rotor core as in the conventional rotor, it is possible to suppress a part of the magnetic flux generated from the portion of the magnet 322B including the vicinity of the corner 511B from being at the corner. It circulates around 511B or flows radially inward via rotor core 321B.

[0060] In addition, in the motor having the rotor 32B of the present embodiment, compared to the motor 1 having the rotor 32 of the first embodiment ( Figure 4 ), further increasing the magnetic flux flowing to the stator side. That is, it can be seen that the induced voltage for generating the torque of the motor is further increased. This is because when the radial gap 56B is provided in addition to the circumferential gap 55B as in the present embodiment, even if the magnetic flux generated from the magnetic pole surface 324B of the magnet 322B intends to pass through the core magnetic pole 51B It flows inward in the radial direction from the vicinity of the central portion in the circumferential direction, and is not blocked by the radial gap portion 56B, which is a gap that sandwiches resin with a large magnetic resistance or a gap that sandwiches air. Therefore, it is possible to further suppress the magnetic flux generated from the magnetic pole surface 324B of the magnet 322B, particularly the magnetic flux generated from the vicinity of the center of the magnetic pole surface 324B of the magnet 322B, from flowing toward the radially inner side. Therefore, the magnetic flux generated from the magnet 322B can be more directed toward the outer end surface of the core magnetic pole portion 51B, that is, the stator side on the radially outer side. As a result, it is possible to further increase the motor torque.

[0061] In addition, in this embodiment, the two protruding portions 54B respectively protrude from the plurality of radial connection portions 53B to both sides in the circumferential direction. In addition, radial gap portions 56B are formed on both sides of the radial connection portion 53B in the circumferential direction. In addition, the radial connection portion 53B of the present embodiment extends on a straight line in the radial direction in the vicinity of the central portion in the circumferential direction of each core magnetic pole portion 51B. Thereby, the magnetic flux distribution in the core magnetic pole portion 51B can be made uniform on both sides in the circumferential direction, and magnetic imbalance can be suppressed. However, it is also possible to adopt a structure in which only one protruding portion 54B protrudes from the plurality of radial connection portions 53B to one side in the circumferential direction, and the radial gap portion 56B is formed only on this side of the radial connection portion 53B.

[0062] In addition, in at least the circumferential gap portion 55B and the radial gap portion 56B in the rotor core 321B of the present embodiment, the above-mentioned columnar resin portion 93 extends in the axial direction and covers at least a part of the radial connection portion 53B. As a result, the radial connection portion 53B, which is a low-strength portion of the rotor core 321B, is covered and reinforced with resin, thereby increasing the strength of the entire rotor core 321B.

[0063] in Figure 7 Here, the radial component of the distance from the position P1 located at the radially innermost position in the circumferential gap portion 55B to the position P2 located at the radially outermost position in the radial gap portion 56B is defined as The first length is L1. In addition, the radial component of the distance from the portion P1 located on the radially innermost position in the circumferential gap portion 55B to the portion P3 located on the radially outermost position in the core magnetic pole portion 51B is defined as The second length is L2.

[0064] As a comparative example with this embodiment, Picture 9 It is a partial plan view showing the result of analyzing the flow of magnetic flux in the rotor (excluding the inner core portion) and the stator when the ratio of the first length L1 to the second length L2 is too large. in Picture 9 In the figure, the flow of magnetic flux obtained as a result of the analysis is illustrated with a fine arrow.

[0065] Such as Picture 9 As shown, in a motor having a rotor with an excessively large ratio of the first length L1 to the second length L2, compared to the motor having the rotor 32B of the present embodiment ( Figure 8 ), reducing the magnetic flux flowing to the stator side. That is, it can be seen that the induced voltage for generating the torque of the motor is reduced. This is because, if the radial length of the radial gap is too long as in the comparative example, the volume of the iron core magnetic pole part that can flow the magnetic flux is too small, thus greatly reducing the magnetism generated from the magnet. The amount of magnetic flux that reaches the outer end surface of the core magnetic pole portion, that is, the radially outer stator side.

[0066] Picture 10 It is a graph showing the result of analyzing the relationship between the ratio of the first length L1 to the second length L2 and the induced voltage Vi. in Picture 10 Here, the vertical axis represents the ratio of the induced voltage Vi to the maximum value Vmax of the induced voltage Vi described later. The horizontal axis represents the ratio of the first length L1 to the second length L2.

[0067] Such as Picture 10 As shown, it can be seen that when the ratio of the first length L1 to the second length L2 is about 80% or less, as the ratio of the first length L1 to the second length L2 increases, the induced voltage Vi is relative to the induced The ratio of the maximum voltage Vmax gradually becomes larger. In particular, when the ratio of the first length L1 to the second length L2 is approximately 78%, the induced voltage Vi becomes the maximum value Vmax. However, when the ratio of the first length L1 to the second length L2 exceeds about 80%, the ratio of the induced voltage Vi to the maximum value Vmax of the induced voltage does not become large, and when it exceeds about 92%, it greatly decreases . This is because if the radial length of the radial gap 56B is too long as described above, the volume of the iron core magnetic pole part 51B that can flow the magnetic flux is excessively reduced, so the generation from the magnet 322B is greatly reduced. The amount of the magnetic flux that reaches the outer end surface of the core magnetic pole portion 51B, that is, the magnetic flux on the radially outer side of the stator.

[0068] In addition, it can be seen that when the ratio of the first length L1 to the second length L2 is about 80% or less, as the ratio of the first length L1 to the second length L2 decreases, the induced voltage Vi is relative to the induced voltage The ratio of the maximum value Vmax gradually decreases. In particular, when the ratio of the first length L1 to the second length L2 is less than about 22%, the ratio of the induced voltage Vi to the maximum value Vmax of the induced voltage is greatly reduced. This is because when the ratio of the first length L1 to the second length L2 is too small, it is difficult to obtain the effect of the provision of the radial gap 56B, and a part of the magnetic flux generated from the magnet 322B in the radial inner circumferential direction The connection part 52B side flows. Based on the above analysis results, considering the errors generated during manufacturing, by setting the first length L1 to approximately 0.25 times or more and approximately 0.9 times or less the second length L2, the magnetic flux generated from the magnet 322B can be increased. It faces the outer end surface of the core magnetic pole portion 51B, that is, the stator side on the radially outer side.

[0069] <3. Modifications>