Motor

Abstract

To provide a motor that can improve energy efficiency.SOLUTION: A motor comprises a rotor having a rotor core. The rotor core has a magnet hole and clearances provided via a partition wall on both sides of the magnet hole in the circumferential direction.SELECTED DRAWING: Figure 6

Description

[Technical field]

[0001] The present disclosure relates to a motor. [Background technology]

[0002] In the technical field related to motors, there is known a motor as disclosed in Patent Document 1. In Patent Document 1, a permanent magnet is disposed in an embedding hole in a rotor core. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2014-197970 A Summary of the Invention [Problem to be solved by the invention]

[0004] Incidentally, in Patent Document 1, the magnet torque is increased and the amount of magnets per pole is increased in order to increase the torque by using the reluctance torque. However, when the amount of magnets per pole is increased, the voltage induced in the stator winding becomes a distorted waveform containing many harmonics, and there is a possibility that the energy efficiency of the motor will decrease.

[0005] An object of the present disclosure is to provide a motor that can improve energy efficiency. [Means for solving the problem]

[0006] According to the present disclosure, there is provided a motor including a rotor having a rotor core, the rotor core having a magnet hole and a gap provided on both circumferential sides of the magnet hole with a partition wall interposed therebetween. Effect of the Invention

[0007] According to the present disclosure, it is possible to provide a motor that can improve energy efficiency. [Brief description of the drawings]

[0008] [Figure 1] FIG. 1 is a vertical cross-sectional view showing a motor device according to an embodiment. [Diagram 2] FIG. 2 is a cross-sectional plan view showing the motor device according to the embodiment. [Diagram 3] FIG. 3 is a schematic diagram of a part of the rotor according to the embodiment, viewed from above. [Figure 4] FIG. 4 is a schematic diagram of a part of the rotor according to the embodiment, viewed from above. [Diagram 5] FIG. 5 is a schematic diagram of a part of the rotor according to the embodiment, viewed from above. [Figure 6] FIG. 6 is a schematic diagram of a part of the rotor according to the embodiment, viewed from above. [Figure 7] FIG. 7 is a diagram showing the relationship between the cogging torque and torque according to the angle θi according to the embodiment. [Figure 8] FIG. 8 is a diagram showing the relationship between the cogging torque and the torque ripple according to the embodiment, depending on the angle θo. [Figure 9] FIG. 9 is a diagram showing the relationship of torque with angle θo according to the embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Hereinafter, an embodiment will be described with reference to the drawings. The components of the embodiment described below can be appropriately combined. In addition, there are cases where some components are not used.

[0010] In the embodiment, the direction parallel to the rotation axis AX of the rotor 7 is appropriately referred to as the axial direction. The radial direction of the rotation axis AX of the rotor 7 is appropriately referred to as the radial direction. The direction going around the rotation axis AX of the rotor 7 is appropriately referred to as the circumferential direction or the rotation direction.

[0011] A position or direction on one side in the axial direction will be referred to as the upper side or upward direction, as appropriate, and a position or direction on the other side in the axial direction will be referred to as the lower side or downward direction, as appropriate. In the radial direction, a position or direction closer to the rotation axis AX of the rotor 7 will be referred to as the radially inner side or inner direction, as appropriate, and a position or direction farther from the rotation axis AX of the rotor 7 will be referred to as the radially outer side or outer direction, as appropriate. A position or direction on one side in the circumferential direction will be referred to as the forward side or forward direction, as appropriate, and a position or direction on the other side in the circumferential direction will be referred to as the reverse side or reverse direction, as appropriate.

[0012] [Motor device] Fig. 1 is a longitudinal sectional view showing a motor device 1 according to an embodiment. Fig. 2 is a plan sectional view showing the motor device 1 according to an embodiment. The motor device 1 generates a torque for driving a hydraulic pump of, for example, an electric hydraulic excavator, which is a type of construction machine.

[0013] The motor device 1 has a motor 2 and a motor case 3. The motor 2 includes a rotor 7, a stator 8, and a fixed ring 9. The motor 2 is an inner rotor type. The stator 8 is disposed around the rotor 7. The rotor 7 rotates about a rotation axis AX.

[0014] The rotor 7 includes a rotor core 21, a permanent magnet 22, and a rotor shaft 23.

[0015] The rotor core 21 includes a plurality of stacked steel plates. The steel plates are metal plates whose main component is iron. The rotor core 21 is disposed so as to surround the rotation axis AX.

[0016] The permanent magnets 22 are supported by the rotor core 21. The permanent magnets 22 are disposed inside the rotor core 21. A plurality of the permanent magnets 22 are disposed around the rotation axis AX.

[0017] The rotor core 21 has a plurality of magnet holes 24 spaced apart in the circumferential direction. The plurality of magnet holes 24 are spaced apart in the circumferential direction at equal intervals. The magnet holes 24 are provided so as to penetrate the upper end surface and the lower end surface of the rotor core 21. Permanent magnets 22 are arranged in the magnet holes 24. In the embodiment, the number of magnet holes 24 is 24. In the embodiment, the permanent magnet 22 is divided into a plurality of parts in the axial direction and arranged inside the rotor core 21.

[0018] The rotor shaft 23 extends in the axial direction. The central axis of the rotor shaft 23 coincides with the rotation axis AX. The rotor shaft 23 is disposed inside the rotor core 21. The rotor core 21 and the rotor shaft 23 are fixed. An upper portion of the rotor shaft 23 protrudes upward from the upper end surface of the rotor core 21. A lower portion of the rotor shaft 23 protrudes downward from the lower end surface of the rotor core 21.

[0019] The stator 8 includes a stator core 13, an insulator 14 fixed to the stator core 13, and a coil 15 attached to the stator core 13 via the insulator 14.

[0020] Stator core 13 is arranged around rotor core 21. Stator core 13 includes a plurality of stacked steel plates. The steel plates are metal plates whose main component is iron. Stator core 13 has an annular yoke and a plurality of teeth protruding radially inward from the inner peripheral surface of the yoke. The yoke is arranged to surround rotation axis AX. A plurality of teeth are arranged in the circumferential direction. The plurality of teeth are arranged at equal intervals in the circumferential direction. A slot is provided between adjacent pairs of teeth.

[0021] The insulator 14 is disposed so as to cover at least a portion of the surface of the stator core 13. The insulator 14 is an electrically insulating member made of synthetic resin. The insulator 14 is fixed to the stator core 13. The stator core 13 and the coils 15 are electrically insulated by the insulator 14. In the embodiment, the insulator 14 is attached to the stator core 13 after being molded by any molding method such as injection molding.

[0022] The coils 15 are wound around the teeth via the insulators 14. In the embodiment, the coils 15 are wound around the teeth by concentrated winding. A portion of the coils 15 is disposed inside the slot. A portion of the coils 15 protrudes upward from the upper end surface of the stator core 13. A portion of the coils 15 protrudes downward from the lower end surface of the stator core 13. In the embodiment, the coils 15 are wound around each tooth. That is, one coil 15 is wound around each tooth.

[0023] A driving current is supplied to the coils 15 via the connection terminals 10. The coils 15 are connected to each other via crossover wires 11. When the driving current is supplied to the coils 15, a rotating magnetic field is generated between the coils 15 and the rotor 7, causing the rotor to rotate.

[0024] The fixing ring 9 is disposed around the stator core 13. The fixing ring 9 is fixed to the stator core 13.

[0025] The motor case 3 houses the motor 2. The motor case 3 is disposed around the fixing ring 9. The motor case 3 has a case body 4 and a case lid 5.

[0026] A refrigerant flow path 18 is formed on the inner circumferential surface of the case body 4. The refrigerant flow path 18 is formed so as to be recessed radially outward from the inner circumferential surface of the case body 4. The refrigerant flow path 18 is spiral. The refrigerant flow path 18 is provided so as to go around the rotation axis AX. The refrigerant flow path 18 may be pulsatile.

[0027] The refrigerant flow path 18 is connected to each of the refrigerant supply circuit 16 and the refrigerant discharge circuit 17. The refrigerant is supplied to the refrigerant flow path 18 via the refrigerant supply circuit 16. The refrigerant flows through the refrigerant flow path 18. The refrigerant that has flowed through the refrigerant flow path 18 is discharged from the refrigerant flow path 18 via the refrigerant discharge circuit 17.

[0028] The case lid 5 is disposed so as to close the opening at the upper end of the case body 4. The case body 4 and the case lid 5 are fixed with bolts 6. The internal space of the motor case 3 is an enclosed space.

[0029] Fig. 3 is a schematic diagram of a part of the rotor 7 according to the embodiment as viewed from above. Fig. 4 is a schematic diagram of a part of the rotor 7 according to the embodiment as viewed from above. Fig. 4 corresponds to an enlarged view of a part of Fig. 3. Fig. 5 is a schematic diagram of a part of the rotor 7 according to the embodiment as viewed from above. Fig. 6 is a schematic diagram of the rotor 7 according to the embodiment as viewed from above.

[0030] Rotor core 21 has a plurality of magnet holes 24 spaced apart in the circumferential direction, and gaps 30 provided on both circumferential sides of magnet holes 24 with partition walls 50 interposed therebetween.

[0031] The partition wall 50 is a part of the rotor core 21. The partition wall 50 separates the magnet holes 24 and the air gaps 30. The magnet holes 24 and the air gaps 30 are each formed by, for example, drilling holes in the rotor core 21. The magnet holes 24 and the air gaps 30 are not connected to each other.

[0032] A gap 30 is provided on both circumferential sides of each of the multiple magnet holes 24, with a partition wall 50 interposed between them. The distance between the magnet hole 24 and the gap 30 arranged on the circumferential forward side of the magnet hole 24 is equal to the distance between the magnet hole 24 and the gap 30 arranged on the circumferential reverse side of the magnet hole 24.

[0033] Magnet holes 24 are provided so as to penetrate through the upper end surface and the lower end surface of rotor core 21. Air gaps 30 are provided so as to penetrate through the upper end surface and the lower end surface of rotor core 21.

[0034] In a plane perpendicular to the rotation axis AX, the magnet hole 24 has a rectangular shape that is long in the circumferential direction. In a plane perpendicular to the rotation axis AX, the permanent magnet 22 has a rectangular shape that is long in the circumferential direction. The end face of the permanent magnet 22 facing radially outward and the end face facing radially inward are in contact with the inner surface of the magnet hole 24. The end face of the permanent magnet 22 facing the circumferential forward rotation side and the end face facing the circumferential reverse rotation side are in contact with the inner surface of the magnet hole 24. That is, the permanent magnet 22 is arranged in the magnet hole 24 without any gaps. As shown in FIG. 4, a minute gap 25 may be present between the corner of the permanent magnet 22 and the magnet hole 24. Also, a minute gap may be present between the outer periphery of the permanent magnet 22 and the magnet hole 24. The gap 25 may be filled with a synthetic resin.

[0035] In the circumferential direction, the dimension of the gap 30 is smaller than the dimension of the magnet hole 24. In the radial direction, the dimension of the gap 30 is larger than the dimension of the magnet hole 24. In the radial direction, the outer end of the gap 30 is located radially outward of the outer end of the magnet hole 24.

[0036] 4, the circumferential dimension Wa of the radially inner edge of the gap 30 is smaller than the circumferential dimension Wb of the radially outer edge of the gap 30. The circumferential dimension of the gap 30 increases radially outward. In a plane perpendicular to the rotation axis AX, the shape of the gap 30 is substantially trapezoidal.

[0037] 3 and 4, the second magnet hole 24B is provided adjacent to the circumferentially forward side of the first magnet hole 24A. The distance F between the first gap 30A provided on the circumferentially forward side of the first magnet hole 24A and the second gap 30B provided on the circumferentially reverse side of the second magnet hole 24B is greater than the dimension G of the partition wall 50 in the circumferential direction.

[0038] The rotor core 21 has a first recess 41 recessed radially inward from the outer circumferential surface of the rotor core 21, and a second recess 42 recessed radially inward from the outer circumferential surface of the rotor core 21. Each of the first recess 41 and the second recess 42 has a groove shape that is long in the axial direction. The first recess 41 is provided across the upper end and the lower end of the rotor core 21. The second recess 42 is provided across the upper end and the lower end of the rotor core 21.

[0039] In the circumferential direction, the first recess 41 is provided at a position closer to the first magnet hole 24A than the center of the first gap 30A. As shown in Fig. 4, the gap 30 is adjacent to the magnet hole 24 and has an edge EL extending in the radial direction. At least a portion of the first recess 41 is provided on an extension line extending radially outward from the edge EL.

[0040] In the circumferential direction, the second recess 42 is provided between the first gap 30A and the second gap 30B.

[0041] As shown in Fig. 5 and Fig. 6, in a plane perpendicular to the rotation axis AX of the rotor 7, the angle between a first line connecting the rotation axis AX and the end of the first recess 41 on the reverse circumferential side and a second line connecting the rotation axis AX and the end of the first recess 41 on the forward circumferential side is θi. The angle between the first line and a reference axis RL, which is a third line connecting the rotation axis AX and the centers of the first gap 30A and the second gap 30B, is θil. The angle between the reference axis RL and the second line is θis. The number of pole pairs of the rotor 7 is p. The reference axis RL is a line passing through the centers of the first gap 30A and the second gap 30B in the circumferential direction. In this case, the first recess 41 satisfies the following condition.

[0042] θi = θil - θis … (1) θis<θil …(2) 24 / p≦θis≦34 / p …(3) 24 / p≦θil≦34 / p …(4)

[0043] As shown in Fig. 5 and Fig. 6, in a plane perpendicular to the rotation axis AX of the rotor 7, the angle between the fourth line connecting the rotation axis AX and the end of the second recess 42 on the reverse circumferential side and the fifth line connecting the rotation axis AX and the end of the second recess 42 on the forward circumferential side is θo. The angle between the fourth line and the reference axis RL, which is the third line connecting the rotation axis AX and the centers of the first gap 30A and the second gap 30B, is θol. The angle between the third line and the fifth line is θos. The number of pole pairs is p. The reference axis RL is a line passing through the centers of the first gap 30A and the second gap 30B in the circumferential direction. In this case, the second recess 42 satisfies the following condition.

[0044] θo=θol-θos …(5) θos<θol …(6) 0≦θos≦10 / p …(7) 0≦θol≦10 / p …(8)

[0045] 7 is a diagram showing the relationship between the cogging torque and torque according to the embodiment of the present invention, in which the horizontal axis indicates the value of [θis / p-θil / p], and the vertical axis indicates the cogging torque and torque.

[0046] As shown in FIG. 7, by providing the first recess 41, the cogging torque is reduced and the torque is increased. As shown by the arrow Ya, the larger the value on the horizontal axis, the closer the first recess 41 is to the gap 30. Also, the larger the value on the horizontal axis, the smaller the cogging torque is and the greater the torque is. The line SL indicates the upper limit of the mechanical strength of the rotor 7. When the condition exceeds the line SL, the mechanical strength of the rotor 7 falls below the allowable value. Therefore, as shown by the arrow Yb, it is preferable to select the value on the horizontal axis to be smaller than the line SL. The value on the horizontal axis is best close to the line SL within a range smaller than the line SL. By satisfying the conditions of the above-mentioned formulas (1) to (4), the cogging torque can be suppressed without reducing the torque while suppressing the deterioration of the rotor strength.

[0047] Fig. 8 is a diagram showing the relationship between cogging torque and torque ripple depending on angle θo according to the embodiment. Fig. 9 is a diagram showing the relationship between torque depending on angle θo according to the embodiment. In Fig. 8, the horizontal axis shows the value of [θos / p-θol / p], and the vertical axis shows torque ripple and cogging torque. In Fig. 9, the horizontal axis shows the value of [θos / p-θol / p], and the vertical axis shows torque.

[0048] As shown by the arrow Yc in FIG. 8, the smaller the value on the horizontal axis, the more the torque ripple decreases. However, in the range shown by the arrow Yd, the cogging torque increases. By making the value on the horizontal axis smaller than the range shown by the arrow Yd, both the torque ripple and the cogging torque can be reduced. On the other hand, as shown by the arrow Ye in FIG. 9, the smaller the value on the horizontal axis, the more the torque decreases. Therefore, by setting the value on the horizontal axis to a value shown in the range Ra, it is possible to maintain the torque while reducing both the torque ripple and the cogging torque. In the embodiment, by satisfying the conditions of the above-mentioned equations (5) to (8), it is possible to maintain the torque while reducing both the torque ripple and the cogging torque.

[0049] [effect] As described above, according to the embodiment, it is possible to suppress the cogging torque and torque ripple without reducing the torque, and to improve the energy efficiency of the motor 2. Furthermore, according to the embodiment, the partition wall 50 is provided between the magnet hole 24 in which the permanent magnet 22 is arranged and the gap 30, so that it is possible to maintain the mechanical strength due to centrifugal force and to suppress a decrease in the strength of the rotor 7. According to the embodiment, it is possible to obtain the flux barrier effect while suppressing a decrease in the strength of the rotor 7. [Explanation of symbols]

[0050] 1...motor device, 2...motor, 3...motor case, 4...case body, 5...case lid, 6...bolt, 7...rotor, 8...stator, 9...fixing ring, 10...connecting terminal, 11...crossover, 13...stator core, 14...insulator, 15...coil, 16...refrigerant supply circuit, 17...refrigerant discharge circuit, 18...refrigerant flow path, 21...rotor core, 22...permanent magnet, 23...rotor shaft, 24...magnet hole, 24A...first magnet hole, 24B...second magnet hole, 25...gap, 30...void, 30A...first gap, 30B...second gap, 41...first recess, 42...second recess, 50...partition wall.

Claims

1. A rotor having a rotor core, The rotor core is A magnet hole; and a gap provided on both circumferential sides of the magnet hole via a partition wall. Motor.

2. The rotor core has a plurality of recesses recessed radially inward from an outer circumferential surface. The motor according to claim 1 .

3. a permanent magnet disposed in the magnet hole; The circumferential end faces of the permanent magnets contact the inner surfaces of the magnet holes. The motor according to claim 1 .

4. The gap is provided so as to penetrate from an end face on one axial side of the rotor core to an end face on the other axial side. The motor according to claim 1 .

5. The circumferential dimension of the gap increases radially outward.

5. The motor according to claim 4.

6. The magnet holes are provided at intervals in the circumferential direction, a second magnet hole is provided adjacent to one circumferential side of the first magnet hole, a distance between a first gap provided on one circumferential side of the first magnet hole and a second gap provided on the other circumferential side of the second magnet hole is greater than a dimension of the partition wall in the circumferential direction; The motor according to claim 2.

7. The recess includes a first recess provided at a position closer to the first magnet hole than a center of the first gap in the circumferential direction.

7. The motor according to claim 6.

8. the first gap has a radially extending edge adjacent the first magnet bore; At least a portion of the first recess is provided on an extension line of the edge.

8. The motor according to claim 7.

9. θi is an angle formed by a first line connecting the rotation axis of the rotor and an end of the first recess on the other circumferential side and a second line connecting the rotation axis and an end of the first recess on one circumferential side in a plane perpendicular to the rotation axis of the rotor; θil is an angle between the first line and a third line connecting the rotation axis and the center of the first gap and the second gap, The angle between the third line and the second line is θis. If the number of pole pairs is p, θi=θil−θis, θis<θil, 24 / p≦θis≦34 / p, 24 / p≦θil≦34 / p, Satisfy the condition of 8. The motor according to claim 7.

10. The recess includes a second recess provided between the first gap and the second gap in the circumferential direction.

8. The motor according to claim 7.

11. θo is an angle formed by a fourth line connecting the rotation axis of the rotor and the other circumferential end of the second recess and a fifth line connecting the rotation axis and the one circumferential end of the second recess in a plane perpendicular to the rotation axis of the rotor; The angle between the fourth line and a third line connecting the rotation axis and the center of the first gap and the second gap is θol, The angle between the third line and the fifth line is θos. If the number of pole pairs is p, θo=θol−θos, θos<θol, 0≦θos≦10 / p, 0≦θol≦10 / p, Satisfy the condition of The motor according to claim 10.

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