Rotor of rotary electric machine

Abstract

This rotor of a rotary electric machine, which is connected to a crankshaft of an engine comprises a rotor core and a hub that supports the rotor core by means of a plurality of spokes. Each of the plurality of spokes is inclined so as to receive a tensile load during regeneration.

Description

Rotor of a rotating electrical machine

[0001] The present invention relates to a rotor of a rotating electrical machine.

[0002] Patent Document 1 discloses an engine generator including an outer rotor supported by an output shaft of an engine and a cooling fan provided on a side surface of the outer rotor.

[0003] Japanese Patent Application Laid-Open No. 2000-328940

[0004] By the way, in a rotating electrical machine such as an engine generator, when the rotor has a relatively large diameter, the amount of vibration and variation of the rotor in the radial outer direction increases, and it may be necessary to increase the gap between the magnet of the rotor and the coil of the stator. However, when the above gap is increased, the power generation efficiency of the rotating electrical machine decreases.

[0005] An object of the present invention is to provide a rotor of a rotating electrical machine capable of suppressing the amount of displacement of the rotor in the radial outer direction.

[0006] A rotor of a rotating electrical machine according to an aspect of the present invention is connected to a crankshaft of an engine and includes a rotor core and a hub that supports the rotor core via a plurality of spokes, and each of the plurality of spokes is inclined so as to receive a tensile load during regeneration.

[0007] According to the rotor of the rotating electrical machine, the amount of displacement of the rotor in the radial outer direction can be suppressed.

[0008] FIG. 1 is a cross-sectional view showing the structure of a rotor of a rotating electrical machine according to an embodiment. FIG. 2 is a schematic view showing the structure of the rotor as viewed from one axial side. FIG. 3A is an explanatory view showing the structure of the rotor and the stator in the A-A cross section in FIG. 1A. FIG. 3B is a front view showing the structure of the rotor and the stator as viewed from one axial side. FIG. 4A is a schematic view showing the structure of the rotor and the fins as viewed from one axial side. FIG. 4B is a perspective view showing the mounting structure of the fins.

[0009] Hereinafter, the rotor 2 of the rotating electrical machine according to the embodiment will be described with reference to the drawings. For components having the same functions as those already described, the same reference numerals will be given and the description will be omitted.

[0010] As illustrated in Figure 1, the motor 1, which is a rotating electric machine, is connected to the engine 11 and functions as an electric motor that drives the wheels of an electric vehicle or hybrid vehicle. The motor 1 also functions as a generator that performs regeneration using the driving force generated by the rotation of the wheels. As illustrated in Figure 1, the motor 1 comprises a rotor 2, a stator 7, and a housing 8 to which the stator 7 is fixed. Here, for the sake of explanation, the height direction of the motor 1 in Figure 1 is referred to as the up and down direction. Also, in the left and right direction (axial direction S) in Figure 1, the left side is referred to as one side and the right side as the other side. Note that in Figure 2-4B, the reference numerals for spokes 5, magnets 6, stator core 7A, coils 9, and fins 21 are representative, and the reference numerals for some spokes 5, magnets 6, stator core 7A, coils 9, and fins 21 are omitted. Also, the shape of each spoke 5 in Figures 2 and 4A is simplified.

[0011] The rotor 2 is connected to the crankshaft 12 of the engine 11 and is rotatable about the central axis of the motor 1, which passes through the axial direction S. As illustrated in Figures 1, 2, and 3B, the rotor 2 comprises a rotor core 3 provided on the radially outward side, a hub 4 provided on the radially inward side, and a plurality of spokes 5 connecting the rotor core 3 and the hub 4.

[0012] The rotor 2 extends radially outward from the hub 4, which is connected to the crankshaft 12, at an angle. The rotor core 3 is formed at the radially outer end of the rotor 2, extending from one side to the other in the axial direction S. As illustrated in Figure 1, a plurality of magnets 6 are laid and fixed on the radially inner surface of the rotor core 3.

[0013] Each spoke 5 connects the hub 4 to the rotor core 3. As illustrated in Figures 1, 2, and 3B, each spoke 5 is connected to the hub 4 at a first connection point 5A. Each spoke 5 is connected to the rotor core 3 at a second connection point 5B. In other words, the hub 4 supports the rotor core 3 via multiple spokes 5. As the hub 4 rotates via the crankshaft 12, the spokes 5, rotor core 3, and magnet 6 rotate.

[0014] As illustrated in Figures 1 and 3A, the stator 7 is located radially inward of the rotor core 3 and is fixed to the inner circumference of the housing 8. A coil 9 is wound around and fixed to each of the multiple stator cores 7A provided radially outward of the stator 7. As illustrated in Figures 1 and 3A, the stator cores 7A face the radially inward surface of the magnet 6 of the rotor core 3 in the radial direction.

[0015] As illustrated in Figure 1, the housing 8 has a ring shape and comprises an inner circumference and an outer circumference. The inner circumference is the inner part of the ring shape and constitutes the radially inner part of the housing 8. The inner circumference extends in the axial direction S, and the stator 7 is fixed to the radially outer surface of the inner circumference. As illustrated in Figure 1, the housing 8 extends radially outward from the other end of the inner circumference in the axial direction S. The outer circumference is the outer circumference of the ring shape and constitutes the radially outer part of the housing 8. The outer circumference extends from the radially outer end of the housing 8 from one side to the other in the axial direction S. Therefore, for example, when the motor 1 is viewed from the other side in the axial direction S, the housing 8 covers the stator 7 (stator core 7A), coil 9, rotor core 3, and magnet 6.

[0016] As illustrated in Figures 2, 3B, and 4A, each of the multiple spokes 5 is positioned at an inclination with respect to the radial direction. More specifically, each of the multiple spokes 5 is positioned at an inclination so as to receive a tensile load during regeneration. As illustrated in Figure 2, during regeneration, the rotor 2 rotates in the rotational direction R. At this time, a tensile load T is input to each of the multiple spokes 5 as the hub 4 pulls each of the multiple spokes 5 along the rotational direction R. By inclining each of the multiple spokes 5 with respect to the radial direction so as to be nearly parallel to the direction of the tensile load T, the tensile load can be appropriately received. This suppresses deformation of the entire rotor 2 due to the tensile load T. That is, by positioning each of the multiple spokes 5 at an inclination with respect to the radial direction, the length of the spokes 5 becomes longer than if each of the multiple spokes 5 were not inclined with respect to the radial direction. As a result, the rigidity against radial displacement at the tip of the spoke 5 is reduced, making the second connection portion 5B between the rotor core 3 and the spoke 5 more susceptible to radial displacement, and local deformation of the rotor core 3 at the second connection portion 5B is mitigated. As a result, the amount of displacement throughout the rotor 2 is suppressed, the displacement of the gap between the magnet 6 of the rotor core 3 and the stator core 7A is reduced, and a stable output can be obtained.

[0017] As illustrated in Figures 2, 3B, and 4A, each of the multiple spokes 5 is inclined to be located towards the rear in the rotational direction of the crankshaft 12 as it moves away from the hub 4. That is, the second connection part 5B is located further rear in the rotational direction R of the hub 4 than the first connection part 5A in the radial direction. With this arrangement, each of the multiple spokes 5 can appropriately receive the tensile load T during regeneration. In addition, because the spokes 5 are inclined with respect to the coil 9 of the stator core 7A, the magnetic flux that may be generated in the spokes 5 is suppressed compared to when the spokes 5 are not inclined. As a result, the amount of change in the magnetic flux that may be generated in the spokes 5 when the rotor 2 rotates is reduced. Therefore, with this configuration, eddy currents generated in the spokes 5 can be suppressed compared to when the spokes 5 are not inclined with respect to the radial direction. Accordingly, power loss and heat generation due to eddy currents can be suppressed with this configuration.

[0018] As illustrated in Figure 2-4A, the rotor has seven spokes 5. Also, as illustrated in Figure 3A, the motor 1 is configured with 16 pole pairs of magnets 6 with different polarities and 24 slots of coil 9. In other words, the number of spokes 5 is less than or equal to the number of poles of the rotor core 3. As a result, eddy currents generated in the spokes 5 can be suppressed more effectively compared to the case where there are many spokes 5.

[0019] As illustrated in Figure 2-4A, each of the multiple spokes 5 is formed to be thicker on the hub 4 side than on the rotor core 3 side. That is, at the second connection portion 5B side of each of the multiple spokes 5, the external dimension in the direction perpendicular to the axis of the spoke 5 (hereinafter referred to as the orthogonal dimension) is larger than the orthogonal dimension of the spoke 5 at the first connection portion 5A side of each of the multiple spokes 5. As a result, eddy currents generated on the rotor core 3 side of the spokes 5 can be suppressed more effectively compared to the case where the orthogonal dimension of the spokes 5 is smaller on the hub 4 side than on the rotor core 3 side.

[0020] As illustrated in Figures 4A and 4B, fins 21 are provided on at least some of the multiple spokes 5. The fins 21 are made of a non-conductive material such as resin and have an inclined surface 21R that intersects with the rotation axis direction (axial direction S) of the crankshaft 12. This allows for the generation of a flow that agitates the air inside the motor 1 in the axial direction S when the rotor 2 rotates.

[0021] As illustrated in Figure 4B, the fins 21 are configured to be detachable from multiple spokes 5. The fins 21 can be temporarily held in place by inserting the projections of the fins 21 into recesses provided on the inner circumferential surface of the rotor core 3 near the second connection portion 5B, and then fixed by bolting the fastening portion 22, which has a bolt hole, to the fastened portion 5C near the second connection portion 5B. Therefore, any number of fins 21 can be attached to each of the multiple spokes 5. Furthermore, the fins 21 can be easily removed from the multiple spokes 5 by releasing the bolt fastening at the fastened portion 5C.

[0022] (1) The rotor 2 of the rotating electric machine according to the embodiment is connected to the crankshaft 12 of the engine 11 and comprises a rotor core 3 and a hub 4 that supports the rotor core 3 via a plurality of spokes 5, and each of the plurality of spokes 5 is inclined to receive a tensile load T during regeneration. With the above configuration, deformation of the entire rotor 2 due to the tensile load T can be suppressed. That is, by arranging each of the plurality of spokes 5 at an angle, the length of the spokes 5 becomes longer than if each of the plurality of spokes 5 were not inclined. As a result, the rigidity against radial displacement at the tip of the spoke 5 is reduced, so the second connection portion 5B between the rotor core 3 and the spokes 5 is more easily displaced radially, and local deformation of the rotor core 3 at the second connection portion 5B is mitigated. As a result, the amount of displacement of the entire rotor 2 is suppressed, the displacement of the gap between the magnet 6 of the rotor core 3 and the stator core 7A is small, and a stable output can be obtained. Furthermore, for example, if the engine 11 is a 3-cylinder engine, the effect obtained by the above configuration becomes more pronounced because the explosion load per cylinder is large. Furthermore, by arranging each of the multiple spokes 5 at an angle, the resistance with the air inside the rotor 2 can be reduced, and wind noise generated by the rotational motion of the rotor 2 can be suppressed. In addition, by shaping each of the multiple spokes 5 at an angle, when the rotor 2 is cast from the molten metal material, a vortex flow is generated in the circumferential direction of the hub 4 (in a direction perpendicular to the axial direction S) as the metal material flows from the hub 4 to the spoke 5. This creates a flow that separates impurities in the metal material toward the tip of the spoke 5, which can improve the material strength of the rotor 2 as a casting.

[0023] (2) In this embodiment, each of the multiple spokes 5 is inclined to be located towards the rear in the rotational direction of the crankshaft 12 as it moves away from the hub 4. With this configuration, the spokes 5 are inclined with respect to the coils 9 of the stator core 7A, so the magnetic flux that can be generated in the spokes 5 is reduced compared to when the spokes 5 are not inclined. As a result, the amount of change in magnetic flux in the spokes 5 is reduced when the rotor 2 rotates. As a result, eddy currents generated in the spokes 5 can be suppressed. This makes it possible to suppress power loss and heat generation due to eddy currents.

[0024] (3) Furthermore, in this embodiment, the number of spokes 5 is less than or equal to the number of poles of the rotor core 3. This makes it possible to further reduce the eddy currents generated in the spokes 5 compared to the case where there are many spokes 5. As a result, power loss and heat generation due to eddy currents can be further suppressed.

[0025] (4) In this embodiment, each of the multiple spokes 5 is thicker on the hub 4 side than on the rotor core 3 side. That is, at the first connection portion 5A side of each of the multiple spokes 5, the external dimension in the direction perpendicular to the axis of the spoke 5 (hereinafter referred to as the perpendicular dimension) is larger than the perpendicular dimension of the spoke 5 at the second connection portion 5B side of each of the multiple spokes 5. As a result, eddy currents generated on the rotor core 3 side of the spokes 5 can be suppressed more effectively compared to the case where the perpendicular dimension of the spokes 5 is larger on the rotor core 3 side than on the hub 4 side. Furthermore, by reducing the perpendicular dimension of the spokes 5 on the rotor core 3 side, where the peripheral speed is higher, air resistance can be reduced compared to the case where the perpendicular dimension of the spokes 5 on the rotor core 3 side is larger.

[0026] (5) Furthermore, in this embodiment, at least some of the spokes 5 are provided with fins 21 having a surface 21R that intersects with the rotation axis direction of the crankshaft 12. As a result, when the rotor 2 rotates, the intersecting surface (inclined surface) 21R can generate a flow that agitates the air inside the motor 1 in the axial direction S, thereby suppressing a localized rise in temperature in the rotor 2.

[0027] (6) In this embodiment, the fins 21 are detachable from the multiple spokes 5. This allows the weight of the motor 1 to be adjusted. By adjusting the number and position of the fins 21, they can function as an outer balancer to suppress vibrations of the engine 11. For example, in the case of a three-cylinder engine, a balance weight may be provided outside the engine 11. In such cases, by adjusting the weight of the motor 1 by appropriately attaching and detaching the fins 21, they can function properly as an outer balancer.

[0028] The embodiments described above are merely illustrative examples provided to facilitate understanding of the invention. The technical scope of the invention is not limited to the specific technical matters disclosed in the embodiments above, but also includes various modifications, changes, and alternative technologies that can be easily derived therefrom.

[0029] 2. Rotor 3. Rotor core 4. Hub 5. Spokes 11. Engine 12. Crankshaft 21. Fins 21R. Inclined surface (intersecting surface)

Claims

1. A rotor for a rotating electric machine, connected to the crankshaft of an engine, comprising: a rotor core; and a hub supporting the rotor core via a plurality of spokes, wherein each of the plurality of spokes is inclined to receive a tensile load during regeneration.

2. The rotor of a rotating electric machine according to claim 1, wherein each of the plurality of spokes is inclined to be located on the rearward side in the rotational direction of the crankshaft as it moves away from the hub.

3. The rotor of the rotating electric machine according to claim 2, wherein the plurality of spokes are composed of a number less than or equal to the number of poles of the rotor core.

4. The rotor of a rotating electric machine according to claim 2 or 3, wherein each of the plurality of spokes is thicker on the hub side than on the rotor core side.

5. The rotor of a rotating electric machine according to any one of claims 2 to 4, wherein at least some of the plurality of spokes are provided with fins having surfaces that intersect with respect to the rotation axis direction of the crankshaft.

6. The rotor of the rotating electric machine according to claim 5, wherein the fins are detachable from the plurality of spokes.

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