JP7483577B2 - Stator coil assembly and electric motor having the same - Google Patents

Description

The present invention relates to a stator-coil assembly and an electric motor equipped with the same.

For example, in the electric motor shown in Patent Document 1 below, multiple coils are formed from a single continuous coil wire (conductor).

JP 2019-97309 A

In the above electric motor, coils of different phases are arranged between coils of the same phase formed from a single coil wire, so that jumper wires connecting the coils of the same phase are provided across the other coils. In this case, the jumper wires connecting the coils of each phase (U-phase, V-phase, W-phase) are provided on one axial side of the stator core, so space is required to place the jumper wires of each phase on one axial side of the stator core, increasing the axial dimension of the electric motor.

For example, if each coil is made from a separate coil wire and both ends of each coil are connected to a bus bar, jumper wires connecting the coils are not needed, and the axial dimension of the electric motor can be reduced. However, connecting both ends of each coil to a bus bar in this way increases the number of contact points between the coils and the bus bar, reducing productivity.

Therefore, the present invention aims to increase the productivity of electric motors by reducing the number of contact points between the coil and the bus bar.

To solve the above problems, the present invention provides a stator-coil assembly for an electric motor having a stator core with multiple teeth spaced apart in the circumferential direction and coils wound around each tooth, in which adjacent coils of the same phase are formed from a single continuous coil wire.

In this way, in the present invention, adjacent coils of the same phase are formed from a single continuous coil wire. This makes it possible to reduce the number of contacts between the coils and the busbar compared to connecting both ends of each coil to the busbar (i.e., providing twice as many contacts as the number of coils).

In the above stator coil assembly, adjacent coils of the same phase are formed by continuously winding the coil wire around adjacent teeth on the stator core. Specifically, after winding the coil wire around one of the adjacent teeth, the coil wire is wound around the other adjacent tooth while maintaining the tension of the coil wire. At this time, the adjacent coils are pulled closer to each other due to the tension of the jumper wire. The teeth of the stator core are arranged radially, and the spacing between adjacent teeth becomes smaller toward the inner diameter, so that the adjacent coils are pulled closer to each other, which may cause the coils to shift toward the inner diameter relative to the teeth.

It is therefore preferable to provide a locking portion on the insulator disposed between the stator core and the coil, and to engage the jumper wires connecting the coils of adjacent coils of the same phase with the locking portion of the insulator from the outer diameter side. In this way, by engaging the jumper wires connecting the coils with the locking portion of the insulator from the outer diameter side, both coils can be pulled to the outer diameter side via the jumper wires, preventing each coil from shifting to the inner diameter side.

The electric motor described above can be formed with multiple coil groups consisting of adjacent coils of the same phase. In this case, if contact points with the bus bar are provided at both ends of the coil wire of each coil group, the number of contact points can be reduced by half compared to when both ends of all coils are connected to the bus bar.

The electric motor described above can be configured to form multiple coil sets consisting of adjacent coils of the same phase, with the coil sets of the same phase spaced apart in the circumferential direction between the coil sets of different phases. In this case, if the coil sets of the same phase spaced apart in the circumferential direction are formed from a single continuous coil wire and contacts with the bus bar are provided at both ends of this coil wire, the number of contacts between the coil wire and the bus bar can be further reduced compared to when both ends of the coil wire of each coil set are connected to the bus bar. In this case, if a contact with a power supply line is provided on the jumper wire connecting the coil sets of the same phase spaced apart in the circumferential direction, a circuit in which both coil sets are arranged in parallel can be formed.

As described above, the present invention reduces the number of contact points between the coil wire and the bus bar, thereby improving the productivity of the stator-coil assembly and, ultimately, the productivity of the electric motor.

FIG. 2 is a cross-sectional view of an electric motor. FIG. 2 is a perspective view of a stator-coil assembly according to one embodiment of the present invention. FIG. 2 is a side view of the stator-coil assembly as viewed from the outer diameter side. FIG. 2 is a front view of the stator-coil assembly as viewed from the axial direction. 4 is a cross-sectional view taken along line XX in FIG. 3. FIG. 2 is a circuit diagram showing a connection state of each coil of the stator-coil assembly. FIG. 11 is a cross-sectional view of a stator-coil assembly according to another embodiment. FIG. 8 is a circuit diagram showing the connection state of each coil of the stator-coil assembly of FIG. 7.

The following describes an embodiment of the present invention with reference to the drawings.

The electric motor 1 shown in FIG. 1 is a three-phase DC brushless motor, and mainly includes a stator coil assembly 2 according to one embodiment of the present invention, a rotor 3, a rotating shaft 4, a bus bar 5, and a housing 6. The stator coil assembly 2 is fixed to the inner peripheral surface of the housing 6. The rotating shaft 4 is rotatably attached to the housing 6 via a bearing 7. The rotor 3 has a rotor core fixed to the rotating shaft 4 and a magnet fixed to the outer periphery of the rotor core. The rotor 3 and the rotating shaft 4 rotate together by controlling the current supplied from an external power source with an inverter circuit and supplying it to the stator coil assembly 2. This electric motor 1 is a fractional groove motor in which P:N is other than 2:3 (i.e., 2N/3P is not an integer) when the number of magnetic poles of the rotor 3 is P and the number of grooves between the teeth in the stator coil assembly 2 is N, and specifically, it is a 10-pole, 12-groove fractional groove motor in which P:N is 10:12. There are other fractional groove motors, such as 8-pole, 9-groove and 14-pole, 18-groove.

As shown in Figures 2 to 4, the stator-coil assembly 2 has a stator core 10, an insulator 20, and a coil 30.

As shown in FIG. 5, the stator core 10 has a cylindrical portion 11 and a number of teeth 12 protruding inward from the cylindrical portion 11. The stator core 10 is integrally formed, for example, from laminated steel sheets made of a laminate of electromagnetic steel sheets with an insulating coating, or from a powder core made of a compact of soft magnetic powder with an insulating coating. The teeth 12 are arranged at multiple locations (12 locations in the illustrated example) that are equally spaced in the circumferential direction. In the illustrated example, a flange portion 12a is provided at the inner diameter end of each tooth 12.

The insulator 20 is a resin part that is disposed between the stator core 10 and the coil 30 and insulates them from each other. In this embodiment, the insulator 20 has a cylindrical tooth covering portion 21 that covers each tooth 12 of the stator core 10, a circumferential portion 22 that continues the outer diameter end of each tooth covering portion 21 in the circumferential direction, and an annular portion 23 (see FIG. 4) provided at one axial end of each tooth covering portion 21. The insulator 20 is formed, for example, in two parts separated at the axial center, and is attached to the stator core 10 from both axial sides. Alternatively, the insulator 20 may be formed as a single piece by injection molding the resin with the stator core 10 as an insert part.

The coils 30 are made of coil wire wound in a concentrated manner around the outer periphery of each tooth 12 of the stator core 10 (see FIG. 5). The coil wire is made of a conductor (e.g., copper wire) coated with an insulating material such as enamel. All coils 30 are in phase with the coil 30 adjacent to them in the circumferential direction, and a pair of adjacent coils 30 in phase form a coil set 40. In this embodiment, as shown in FIG. 4, a first U-phase coil set 40 (U1), a second U-phase coil set 40 (U2), a first V-phase coil set 40 (V1), a second V-phase coil set 40 (V2), a first W-phase coil set 40 (W1), and a second W-phase coil set 40 (W2) are provided.

Each coil group 40 is formed from a single continuous coil wire. Specifically, in the first U-phase coil group 40 (U1) shown on the right side of FIG. 6, the coil wire is wound in the forward direction (clockwise direction) around the teeth 12 on the right side of the figure to form one coil 30, and then the coil wire is wound in the reverse direction (counterclockwise direction) around the teeth 12 on the left side of the figure to continuously form the other coil 30, thereby forming the coil group 40. Both ends of the coil wire of each coil group 40 thus formed are connected to the conductor of the bus bar 5 (see FIG. 1). Specifically, both ends of the coil wire of each coil group 40 are attached to the conductor of the bus bar 5 by fusing or the like in a state in which electricity can be passed through them, and these contact points P are provided. The arrows on the coil wire in FIG. 6 indicate the winding direction and order of the coil wire.

In this embodiment, the coil wire of each coil group 40 is star-connected. Specifically, one end of the coil wire of each coil group 40 is connected to the neutral wire 5a of the busbar 5, and the other end of the coil wire of each coil group 40 is connected to the conductor to which the connection terminal 5b of the busbar 5 is connected. This connects the first U-phase coil group 40 (U1) and the second U-phase coil group 40 (U2), the first V-phase coil group 40 (V1) and the second V-phase coil group 40 (V2), and the first W-phase coil group 40 (W1) and the second W-phase coil group 40 (W2) in parallel. A power supply line from an external power source is connected to the connection terminal 5b of the busbar 5.

In this way, by forming adjacent coils 30 of the same phase from a single continuous coil wire, the number of contact points P (fusing points) between the coil wire and the busbar 5 can be reduced compared to when each coil 30 is formed from a separate coil wire, improving the productivity of the stator-coil assembly 2 and ultimately improving the productivity of the electric motor 1.

The coil wire has a portion that forms adjacent coils 30 of the same phase, and a jumper wire 31 that connects both coils 30. When forming each coil 30, a certain amount of tension must be applied to the coil wire, so tension is also applied to the jumper wire 31 that connects the coils 30, and both coils 30 are pulled toward each other. However, because adjacent teeth 12 both extend toward the axis, if both coils 30 are pulled toward each other, there is a risk that both coils 30 will shift toward the side where the spacing between the teeth 12 is narrower, i.e., toward the inner diameter.

In this embodiment, therefore, the insulator 20 is provided with a locking portion 24, and the jumper wire 31 is engaged with the locking portion 24 from the outer diameter side. Specifically, as shown in Figs. 2 to 4, the locking portions 24 protruding in one axial direction are provided at multiple locations in the circumferential direction of the annular portion 23 provided at one axial end (left side in Fig. 3) of the insulator 20. The locking portions 24 may be integrally formed with the annular portion 23, or the locking portions 24 formed separately may be fixed to the annular portion 23. The jumper wire 31 of the coil wire forming each coil set 40 is engaged with the locking portion 24 of the insulator 20 from the outer diameter side. In this way, the movement of the coil 30 toward the inner diameter side can be restricted via the jumper wire 31 formed by the locking portion 24. In particular, in the illustrated example, a flange portion 24a (see Fig. 3) extending to the outer diameter side is provided at one axial end of the locking portion 24, making it easier to engage the jumper wire 31 with the locking portion 24.

The present invention is not limited to the above embodiment. Other embodiments of the present invention will be described below, but duplicate explanations of points similar to the above embodiment will be omitted.

7 and 8, the first U-phase coil set 40 (U1) and the second U-phase coil set 40 (U2) are formed with one continuous coil wire, the first V-phase coil set 40 (V1) and the second V-phase coil set 40 (V2) are formed with one continuous coil wire, and the first W-phase coil set 40 (W1) and the second W-phase coil set 40 (W2) are formed with one continuous coil wire. As shown in FIG. 8, both ends of the coil wire that continuously forms the pair of coil sets 40 of each phase are connected to the neutral wire 5a of the busbar 5 by fusing or the like (star connection). In this way, by forming the pair of coil sets 40 of each phase (a total of four coils 30) with a single coil wire, the number of contact points P between the coils 30 and the busbar 5 is further reduced.

The coil wire forming the U-phase coil sets 40 (U1), 40 (U2) is provided with a jumper wire 32 (U) that connects the two coil sets 40 (U1), 40 (U2). The coil wire forming the V-phase coil sets 40 (V1), 40 (V2) is provided with a jumper wire 32 (V) that connects the two coil sets 40 (V1), 40 (V2). The coil wire forming the W-phase coil sets 40 (W1), 40 (W2) is provided with a jumper wire 32 (W) that connects the two coil sets 40 (W1), 40 (W2). The jumper wires 32 (U), 32 (V), 32 (W) are connected to the external power supply line 8 by fusing or the like, and are provided with contact points Q. As a result, the first U-phase coil set 40 (U1) and the second U-phase coil set 40 (U2), the first V-phase coil set 40 (V1) and the second V-phase coil set 40 (V2), and the first W-phase coil set 40 (W1) and the second W-phase coil set 40 (W2) are connected in parallel. In this case, the bus bar 5 is provided with only the conductor of the neutral line 5a, and is not provided with a connection terminal or the like to which the power supply line is connected.

In addition, in this embodiment, as shown in FIG. 7, the coil wire jumpers 32(U), 32(V), and 32(W) of each phase have portions disposed radially outward from the outer circumferential surface of the stator core 10. Specifically, the insulator 20 is provided with a locking portion 25 disposed radially outward from the outer circumferential surface of the stator core 10, and the jumpers 32(U), 32(V), and 32(W) are routed around the outer circumferential side of the locking portion 25. In this way, by arranging a portion of each jumper 32(U), 32(V), and 32(W) radially outward from the stator core 10, it becomes easier to connect the power supply lines 8 to the jumpers 32(U), 32(V), and 32(W).

The electric motor 1 described above is incorporated into an electric oil pump that is installed in, for example, a vehicle with an idling stop function or a hybrid vehicle. When the engine is stopped, the electric oil pump draws oil from an oil reservoir at the bottom of the transmission case, and then discharges the oil and pumps it into the transmission, thereby ensuring the necessary oil pressure within the transmission.

REFERENCE SIGNS LIST 1 Electric motor 2 Stator-coil assembly 3 Rotor 4 Rotating shaft 5 Bus bar 6 Housing 7 Bearing 8 Power supply line 10 Stator core 11 Cylindrical portion 12 Teeth 20 Insulator 24 Locking portion 30 Coil 31 Crossover wires 32 (U), 32 (V), 32 (W) (connecting coils together) Crossover wire 40 (connecting coil sets together) Coil set P Contact point between coil wire and bus bar Q Contact point between coil wire (crossover wire) and power supply line

Claims (9)

A stator-coil assembly for an electric motor having a stator core having a plurality of teeth spaced apart in a circumferential direction and a coil wound around each of the teeth,
Adjacent coils of the same phase are formed from a single continuous coil wire ,
an insulator disposed between the stator core and the coil;
A locking portion is provided on the insulator,
A stator coil assembly in which a crossover wire connecting adjacent coils of the same phase among the coil wires is engaged with a locking portion of the insulator from the outer diameter side while tension is applied thereto . the insulator has a plurality of tooth covering portions covering each tooth of the stator core, an annular portion provided at one axial end of the plurality of tooth covering portions, and the locking portion protruding in one axial direction from the annular portion,
2. The stator coil assembly according to claim 1 , wherein the locking portion has a flange portion extending radially outward from one axial end of the locking portion . The stator-coil assembly according to claim 1 or 2, in which a plurality of coil groups are formed from adjacent coils of the same phase, and contacts with the busbar are provided on both ends of the coil wire of each coil group. forming a plurality of coil sets each made up of adjacent coils of the same phase, the coil sets of the same phase being spaced apart in the circumferential direction with a coil set of a different phase therebetween;
3. A stator coil assembly according to claim 1 or 2, wherein a set of coils of the same phase spaced apart in the circumferential direction are formed from a single continuous coil wire, and contact points with the bus bar are provided at both ends of the coil wire. The stator-coil assembly according to claim 4, in which a contact point with a power supply line is provided on a crossover wire that connects coil sets of the same phase that are spaced apart in the circumferential direction. An electric motor comprising a stator-coil assembly according to any one of claims 1 to 5, a rotor disposed on the inner circumference of the stator-coil assembly, and a bus bar to which the stator-coil assembly is connected. The electric motor of claim 6 is a fractional groove motor in which the ratio of the number of magnetic poles of the rotor to the number of grooves between the teeth of the stator-coil assembly is other than 2:3. An electric motor as described in claim 7, in which the ratio of the number of magnetic poles of the rotor to the number of grooves between the teeth of the stator-coil assembly is 10:12. An electric motor according to any one of claims 6 to 8, in which the coils of each phase are connected in a star connection.

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