Motor

Abstract

This motor comprises: a stator core; a coil disposed in a slot of the stator core; and a rotor opposing the stator core. When the number of poles of the rotor is taken as P, the number of slots of the stator core as S, and the positive integer as n, the coil is wound around the teeth of the stator core by concentrated winding at one slot pitch in the circumferential direction of the stator core so as to satisfy the conditions of P = 2n and S = 3n.

Description

Motor

[0001] The present disclosure relates to a motor.

[0002] 2. Description of the Related Art In the technical field of motors, an electric motor such as that disclosed in Patent Document 1 is known.

[0003] JP 2010-158100 A

[0004] A motor has multiple coils, and if there is a difference in resistance among the multiple coils due to, for example, differences in the lengths of the wires that form the coils, the performance of the motor can be reduced.

[0005] The present disclosure aims to suppress deterioration in motor performance.

[0006] According to the present disclosure, there is provided a motor comprising a stator core, coils arranged in slots of the stator core, and a rotor facing the stator core, wherein the coils are wound around the teeth of the stator core by concentrated winding at a one-slot pitch around the circumferential direction of the stator core so as to satisfy the conditions P = 2n and S = 3n, where P is the number of poles of the rotor, S is the number of slots in the stator core, and n is a positive integer.

[0007] According to the present disclosure, deterioration in motor performance is suppressed.

[0008] FIG. 1 is a perspective view showing a stator according to an embodiment. FIG. 2 is a diagram for explaining the phase order of coils in the case of 12 poles (24 poles) and 18 slots according to an embodiment. FIG. 3 is a diagram for explaining the phase order of coils in the case of 18 poles (36 poles) and 27 slots according to an embodiment. FIG. 4 is a diagram for explaining the phase order of coils in the case of 24 poles (48 poles) and 36 slots according to an embodiment. FIG. 5 is a diagram showing a coil connection diagram in the case of 12 poles (24 poles) and 18 slots according to an embodiment. FIG. 6 is a diagram showing a coil connection diagram in the case of 18 poles (36 poles) and 27 slots according to an embodiment. FIG. 7 is a diagram showing a coil connection diagram in the case of 24 poles (48 poles) and 36 slots according to an embodiment.

[0009] Hereinafter, embodiments will be described with reference to the drawings. The components of the embodiments described below can be combined as appropriate. In addition, some components may not be used.

[0010] In the embodiment, a direction parallel to the central axis AX of the stator 1 will be referred to as the axial direction, a direction radial from the central axis AX of the stator 1 will be referred to as the radial direction, and a direction circumferentially around the central axis AX of the stator 1 will be referred to as the circumferential direction or the rotational direction.

[0011] A position or direction on one side in the axial direction will be referred to as the upper side or the upper 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 the lower direction, as appropriate. In the radial direction, a position or direction close to the central axis AX of the stator 1 will be referred to as the radially inner side or the inner direction, as appropriate, and a position or direction away from the central axis AX of the stator 1 will be referred to as the radially outer side or the outer direction, as appropriate. A position or direction on one side in the circumferential direction will be referred to as the forward side or the 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 the reverse direction, as appropriate.

[0012] [Stator] Fig. 1 is a perspective view showing a stator 1 according to an embodiment. The stator 1 is used in an inner rotor type motor. The stator 1 is disposed around a rotor (not shown). The rotor rotates about a central axis AX. The motor generates a rotational force for driving a hydraulic pump of, for example, an electric hydraulic excavator, which is a type of construction machine.

[0013] The stator 1 includes a stator core 2 , an insulator 3 fixed to the stator core 2 , and a coil 4 attached to the stator core 2 via the insulator 3 .

[0014] The stator core 2 includes a plurality of stacked steel plates. The steel plates are metal plates whose main component is iron. The stator core 2 has an annular yoke and a plurality of teeth 22 that protrude radially inward from the inner peripheral surface of the yoke. The yoke is arranged to surround the central axis AX. A plurality of teeth 22 are arranged in the circumferential direction. The plurality of teeth 22 are arranged at equal intervals in the circumferential direction. A slot 23 is provided between each pair of adjacent teeth 22.

[0015] The insulator 3 is disposed so as to cover at least a portion of the surface of the stator core 2. The insulator 3 is an electrically insulating member made of synthetic resin. The insulator 3 is fixed to the stator core 2. The stator core 2 and the coils 4 are electrically insulated by the insulator 3. In this embodiment, the insulator 3 is molded by any molding method, such as injection molding, and then attached to the stator core 2.

[0016] In the embodiment, the insulator 3 is divided in both the axial direction and the circumferential direction. The insulator 3 includes an upper-end insulator 5, an intermediate insulator 6, and a lower-end insulator 7. The upper-end insulator 5, the intermediate insulator 6, and the lower-end insulator 7 are arranged in the axial direction. At least a portion of the upper-end insulator 5 is arranged above the intermediate insulator 6. At least a portion of the lower-end insulator 7 is arranged below the intermediate insulator 6.

[0017] The upper-end insulator 5 is fixed to the upper end of the stator core 2. The lower-end insulator 7 is fixed to the lower end of the stator core 2. The intermediate insulator 6 is arranged closer to the center of the stator core 2 in the axial direction than the upper-end insulator 5. That is, the intermediate insulator 6 is arranged lower than the upper-end insulator 5 in the axial direction. The intermediate insulator 6 is arranged closer to the center of the stator core 2 in the axial direction than the lower-end insulator 7. That is, the intermediate insulator 6 is arranged higher than the lower-end insulator 7 in the axial direction. The upper-end insulator 5 is connected to the upper end of the intermediate insulator 6. The lower-end insulator 7 is connected to the lower end of the intermediate insulator 6.

[0018] The coils 4 are wound around the teeth 22 via the insulators 3. In the embodiment, the coils 15 are wound by concentrated winding around the teeth 24 at one slot pitch in the circumferential direction of the stator core 2. A portion of the coils 4 is arranged inside the slots 23. A portion of the coils 4 protrudes upward from the upper end surface of the stator core 2. A portion of the coils 4 protrudes downward from the lower end surface of the stator core 2. In the embodiment, the coils 4 are wound one by one around each tooth 22. That is, one coil 4 is wound around one tooth 22. The coils 4 are arranged at one slot pitch in the circumferential direction of the stator core 2. When a portion of the coil 4 is arranged in a first slot 23, another portion of the coil 4 is arranged in a second slot 23 that is adjacent to the first slot 23 in the circumferential direction.

[0019] Each of the multiple coils 4 is assigned to one of the U-phase coil, V-phase coil, and W-phase coil. In the example shown in FIG. 1 , 12 coils 4 are assigned to the U-phase coil, 12 coils 4 are assigned to the V-phase coil, and 12 coils 4 are assigned to the W-phase coil.

[0020] A drive current is supplied to the coil 4 via connection terminals 8. The connection terminals 8 include a U-phase connection terminal 8U to which a U-phase drive current is supplied, a V-phase connection terminal 8V to which a V-phase drive current is supplied, and a W-phase connection terminal 8W to which a W-phase drive current is supplied. When a drive current is supplied to the coil 4, a rotating magnetic field is generated between the coil 4 and the rotor, causing the rotor to rotate.

[0021] The coils 4 are connected via crossover wires 9. A plurality of crossover wires 9 are provided. In the example shown in Fig. 1, the crossover wires 9 include a crossover wire 9U, a crossover wire 9V, and a crossover wire 9W.

[0022] As described above, the stator 1 is used in an inner rotor motor. A rotor (not shown) is disposed inside the stator 1. The rotor faces the stator core 2. The rotor has a rotor core and a magnet supported by the rotor core. The rotor core includes a plurality of laminated steel plates. The magnet is a permanent magnet. The magnet is disposed inside the rotor core. A plurality of magnets are disposed around the central axis AX. The rotor core has a plurality of magnet holes spaced apart in the circumferential direction. The magnet is disposed in the magnet hole. The motor is an interior permanent magnet (IPM) motor in which permanent magnets are embedded inside the rotor core. Note that the motor may also be a surface permanent magnet (SPM) motor in which permanent magnets are attached to the surface of the rotor core. A plurality of magnets are disposed at equal intervals in the circumferential direction.

[0023] In the following description, the number of coils 4 will be referred to as the number of slots S, and the number of magnets will be referred to as the number of poles P, as appropriate.

[0024] In this embodiment, the number of poles P is an integer multiple of 2. The number of slots S is an integer multiple of 3. In other words, when n is a positive integer, the motor has the coils 4 wound around the teeth 24 of the stator core 2 at one slot pitch in a concentrated winding manner so as to satisfy the conditions P = 2n and S = 3n.

[0025] In this embodiment, when the number of poles of the rotor is P, the number of slots of the stator core 2 is S, and m is a natural number, the motor satisfies the following conditions: S = 9 × (m + 1) (1) P = 2 / 3 × S (2A)

[0026] The motor may satisfy the following conditions: S=9×(m+1) (1) P=4 / 3×S (2B)

[0027] For example, when the natural number m is 1 and the number of slots S is 18, the number of poles P is 12 according to formula (2A), and the number of poles P is 24 according to formula (2B). When the natural number m is 2 and the number of slots S is 27, the number of poles P is 18 according to formula (2A), and the number of poles P is 36 according to formula (2B). When the natural number m is 3 and the number of slots S is 36, the number of poles P is 24 according to formula (2A), and the number of poles P is 48 according to formula (2B).

[0028] In the following description, the number of poles that satisfies formula (2B) will be written in parentheses after the number of poles that satisfies formula (2A). That is, when the natural number m is 1 and the number of slots S is 18, the number of poles P is 12 (24). When the natural number m is 2 and the number of slots S is 27, the number of poles P is 18 (36). When the natural number m is 3 and the number of slots S is 36, the number of poles P is 24 (48).

[0029] FIG. 2 is a diagram for explaining the phase order of the coils 4 in the case of a 12-pole (24-pole) 18-slot rotor according to the embodiment. FIG. 3 is a diagram for explaining the phase order of the coils 4 in the case of a 18-pole (36-pole) 27-slot rotor according to the embodiment. FIG. 4 is a diagram for explaining the phase order of the coils 4 in the case of a 24-pole (48-pole) 36-slot rotor according to the embodiment. FIG. 5 is a diagram showing a connection diagram of the coils 4 in the case of a 12-pole (24-pole) 18-slot rotor according to the embodiment. FIG. 6 is a diagram showing a connection diagram of the coils 4 in the case of a 18-pole (36-pole) 27-slot rotor according to the embodiment. FIG. 7 is a diagram showing a connection diagram of the coils 4 in the case of a 24-pole (48-pole) 36-slot rotor according to the embodiment.

[0030] As described above, the coils 4 are arranged at one slot pitch in the circumferential direction of the stator core 2. That is, one coil 4 is wound around one tooth 22. The coils 4 include a U-phase coil, a V-phase coil, and a W-phase coil.

[0031] The U-phase coils 4U are connected in three groups in parallel. The V-phase coils 4V are connected in three groups in parallel. The W-phase coils 4W are connected in three groups in parallel. In other words, if a plurality of coils 4 connected in series are considered to be one group of coils, the stator 1 has a first group of U-phase coils 4U, a second group of U-phase coils 4U, and a third group of U-phase coils 4U that are connected in parallel to each other. The stator 1 has a first group of V-phase coils 4V, a second group of V-phase coils 4V, and a third group of V-phase coils 4V that are connected in parallel to each other. The stator 1 has a first group of W-phase coils 4W, a second group of W-phase coils 4W, and a third group of W-phase coils 4W that are connected in parallel to each other.

[0032] In the embodiment, the position of the coil 4 in the circumferential direction of the stator core 2 is referred to as a slot number Nx as appropriate. The slot numbers Nx are assigned in ascending order in the forward circumferential direction.

[0033] When n is a natural number, the U-phase coils 4U are arranged in slot numbers N9n-8, N9n-5, and N9n-2. That is, the slot number of the first group of U-phase coils 4U is N9n-8. The slot number of the second group of U-phase coils 4U is N9n-5. The slot number of the third group of U-phase coils 4U is N9n-2.

[0034] When n is a natural number, the V-phase coils 4V are arranged in slot numbers N9n-7, N9n-4, and N9n-1. That is, the slot number of the V-phase coils 4V in the first group is N9n-7. The slot number of the V-phase coils 4V in the second group is N9n-4. The slot number of the V-phase coils 4V in the third group is N9n-1.

[0035] When n is a natural number, the W-phase coils 4W are arranged in slot numbers N9n-6, N9n-3, and N9n-0. That is, the slot number of the W-phase coils 4W in the first group is N9n-6. The slot number of the W-phase coils 4W in the second group is N9n-3. The slot number of the W-phase coils 4W in the third group is N9n-0.

[0036] If the motor has 12 poles (24 poles) and 18 slots, the natural number n can be 1 and 2. If the motor has 18 poles (36 poles) and 27 slots, the natural number n can be 1, 2, and 3. If the motor has 24 poles (48 poles) and 36 slots, the natural number n can be 1, 2, 3, and 4.

[0037] If the motor has 12 poles (24 poles) and 18 slots, the slot numbers of the first group of U-phase coils 4U are N1 and N10, the slot numbers of the second group of U-phase coils 4U are N4 and N13, and the slot numbers of the third group of U-phase coils 4U are N7 and N16.

[0038] If the motor has 12 poles (24 poles) and 18 slots, the slot numbers of the V-phase coils 4V in the first group are N2 and N11, the slot numbers of the V-phase coils 4V in the second group are N5 and N14, and the slot numbers of the V-phase coils 4V in the third group are N8 and N17.

[0039] If the motor has 12 poles (24 poles) and 18 slots, the slot numbers of the W-phase coils 4W in the first group are N3 and N12, the slot numbers of the W-phase coils 4W in the second group are N6 and N15, and the slot numbers of the W-phase coils 4W in the third group are N9 and N18.

[0040] If the motor has 18 poles (36 poles) and 27 slots, the slot numbers of the first group of U-phase coils 4U are N1, N10, and N19. The slot numbers of the second group of U-phase coils 4U are N4, N13, and N22. The slot numbers of the third group of U-phase coils 4U are N7, N16, and N25.

[0041] If the motor has 18 poles (36 poles) and 27 slots, the slot numbers of the V-phase coils 4V in the first group are N2, N11, and N20. The slot numbers of the V-phase coils 4V in the second group are N5, N14, and N23. The slot numbers of the V-phase coils 4V in the third group are N8, N17, and N26.

[0042] If the motor has 18 poles (36 poles) and 27 slots, the slot numbers of the W-phase coils 4W in the first group are N3, N12, and N21. The slot numbers of the W-phase coils 4W in the second group are N6, N15, and N24. The slot numbers of the W-phase coils 4W in the third group are N9, N18, and N27.

[0043] If the motor has 24 poles (48 poles) and 36 slots, the slot numbers of the first group of U-phase coils 4U are N1, N10, N19, and N28. The slot numbers of the second group of U-phase coils 4U are N4, N13, N22, and N31. The slot numbers of the third group of U-phase coils 4U are N7, N16, N25, and N34.

[0044] If the motor has 24 poles (48 poles) and 36 slots, the slot numbers of the V-phase coils 4V in the first group are N2, N11, N20, and N29. The slot numbers of the V-phase coils 4V in the second group are N5, N14, N23, and N32. The slot numbers of the V-phase coils 4V in the third group are N8, N17, N26, and N35.

[0045] If the motor has 24 poles (48 poles) and 36 slots, the slot numbers of the W-phase coils 4W in the first group are N3, N12, N21, and N30. The slot numbers of the W-phase coils 4W in the second group are N6, N15, N24, and N33. The slot numbers of the W-phase coils 4W in the third group are N9, N18, N27, and N36.

[0046] 5, 6, and 7, the input point for inputting a drive current to the U-phase coil 4U of the first group is designated as input point U1, the input point for inputting a drive current to the U-phase coil 4U of the second group is designated as input point U2, and the input point for inputting a drive current to the U-phase coil 4U of the third group is designated as input point U3. The input point for inputting a drive current to the V-phase coil 4V of the first group is designated as input point V1, the input point for inputting a drive current to the V-phase coil 4V of the second group is designated as input point V2, and the input point for inputting a drive current to the V-phase coil 4V of the third group is designated as input point V3. The input point for inputting a drive current to the W-phase coil 4W of the first group is designated as input point W1, the input point for inputting a drive current to the W-phase coil 4W of the second group is designated as input point W2, and the input point for inputting a drive current to the W-phase coil 4W of the third group is designated as input point W3.

[0047] Input points U1, U2, and U3 are connected to connection terminal 8U. Input points V1, V2, and V3 are connected to connection terminal 8V. Input points W1, W2, and W3 are connected to connection terminal 8W.

[0048] As shown in Figures 5, 6, and 7, in the cases where the motor has 12 poles (24 poles) and 18 slots, the motor has 18 poles (36 poles) and 27 slots, and the motor has 24 poles (48 poles) and 36 slots, the mutual distances between input point U1, input point V1, input point W1, input point U2, input point V2, input point W2, input point U3, input point V3, and input point W3 can be shortened. 5, 6, and 7, input point V1 is arranged next to the circumferentially forward side of input point U1, input point W1 is arranged next to the circumferentially forward side of input point V1, input point U2 is arranged next to the circumferentially forward side of input point W1, input point V2 is arranged next to the circumferentially forward side of input point U2, input point W2 is arranged next to the circumferentially forward side of input point V2, input point U3 is arranged next to the circumferentially forward side of input point W2, input point V3 is arranged next to the circumferentially forward side of input point U3, and input point W3 is arranged next to the circumferentially forward side of input point V3.

[0049] The distance between the input point U1 and the input point V1 in the circumferential direction is substantially equal to the dimension of one coil 4. The distance between other pairs of adjacent input points is also substantially equal to the dimension of one coil 4.

[0050] Since the distance between adjacent pairs of input points is short, when the coils 4 of one group are formed from a single wire, differences in the lengths of the wires of the multiple groups are suppressed.

[0051] That is, it is possible to prevent differences in the lengths of the wires forming the different phase coils 4. For example, it is possible to prevent differences in the lengths of the wires forming the first group of U-phase coils 4U, the first group of V-phase coils 4V, and the first group of W-phase coils 4W.

[0052] This also reduces differences in the lengths of the wires forming the same phase coils 4. For example, this reduces differences in the lengths of the wires forming the first group of U-phase coils 4U, the second group of U-phase coils 4U, and the third group of U-phase coils 4U.

[0053] If differences in resistance values ​​occur among the multiple coils 4 due to differences in the lengths of the wires forming the coils 4, the performance of the motor may be degraded. According to the embodiment, differences in the lengths of the wires forming the coils 4 of different phases are suppressed. Differences in the lengths of the wires forming the coils 4 of the same phase are suppressed. Therefore, when the motor is a three-phase motor and the U-phase coil 4U, V-phase coil 4V, and W-phase coil 4W are connected in parallel, differences in resistance values ​​between the coils 4 of different phases and differences in resistance values ​​between the coils 4 of the same phase are suppressed.

[0054] [Effects] As described above, according to the embodiment, by devising a wire routing when forming the coils 4, it is possible to suppress differences in resistance between the coils 4 of different phases and between the coils 4 of the same phase. Since differences in resistance between the coils 4 of the same phase are suppressed, circulating currents in the coils 4 of the same phase are prevented. This suppresses deterioration in motor performance.

[0055] 1... stator, 2... stator core, 3... insulator, 4... coil, 5... upper end insulator, 6... intermediate insulator, 7... lower end insulator, 8... connection terminal, 8U... U-phase connection terminal, 8V... V-phase connection terminal, 8W... W-phase connection terminal, 9... jumper wire, 9U... jumper wire, 9V... jumper wire, 9W... jumper wire, 22... teeth, 23... slot

Claims

1. A motor comprising: a stator core; coils arranged in slots of the stator core; and a rotor facing the stator core, wherein the coils are wound around the teeth of the stator core using concentrated winding at a one-slot pitch around the circumferential direction of the stator core so as to satisfy the conditions: P = 2n, S = 3n, where P is the number of poles of the rotor, S is the number of slots of the stator core, and n is a positive integer.

2. The motor according to claim 1, which satisfies the following condition, where m is a natural number: S = 9 x (m + 1), P = 2 / 3 x S, or P = 4 / 3 x S.

3. The motor according to claim 1 or 2, wherein the coils are arranged at one slot pitch in the circumferential direction of the stator core, the coils include a first phase coil, a second phase coil, and a third phase coil, each of the first phase coil, the second phase coil, and the third phase coil are connected in parallel in groups of three, and when a slot number Nx represents a coil position in the circumferential direction of the stator core, n is a natural number, and the slot numbers Nx are assigned in ascending order in the circumferential direction, the first phase coils are arranged in slot numbers N9n-8, N9n-5, N9n-2, the second phase coils are arranged in slot numbers N9n-7, N9n-4, N9n-1, and the third phase coils are arranged in slot numbers N9n-6, N9n-3, N9n-0.

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