Rotor, rotary electric machine, and vehicle driving device

Abstract

This rotor comprises: a rotor core into which a shaft is fitted and which is formed by laminating plate-like members having formed therein through holes; end plates that sandwich the rotor core from both sides in the rotation axis direction to stabilize the same; and magnet covers that each cover a surface, of the corresponding end plate, positioned on the side opposite to the rotor core. Each of the end plates has: an annular part into which the shaft is fitted; a plurality of bolt insertion parts which project outward in the radial direction from the annular part and have formed therein bolt insertion holes into which bolts are inserted; and cutouts which are each formed between adjacent two bolt insertion parts and have portions recessed toward the rotation axis. The cutouts are arranged in a manner of at least partially overlapping with the through holes in the rotation axis direction. Each of the magnet covers has formed therein holes which at least partially overlap with the cutouts in the rotation axis direction.

Description

Rotor, rotating electric machine and vehicle drive device

[0001] The present invention relates to a rotor, a rotating electric machine, and a vehicle drive device.

[0002] A rotor core of a rotating electric machine such as a motor or generator includes multiple plate-shaped members stacked in the direction of the rotor's rotation axis. The plate-shaped members often have perforations formed therethrough in the direction of the rotation axis to relieve stress generated by rotor rotation, reduce the rotor's weight, and improve the rotor's cooling efficiency. The rotor core is formed by sandwiching and fixing multiple plate-shaped members between two end plates from both sides in the direction of the rotation axis. The end plates have perforations formed in positions that overlap with the perforations in the plate-shaped members. An example of such an end plate is an annular fixing plate disclosed in Patent Document 1. End plates are generally often annular plates.

[0003] Japanese Patent Application Laid-Open No. 2020-115730

[0004] However, in an annular end plate, the radial distance from the edge to the perforation hole may become short depending on the position where the perforation hole is formed in the end plate, the shape and dimensions of the perforation hole in the end plate, etc. In such a case, the annular end plate may break due to stress when the rotor rotates at high speed.

[0005] On the other hand, if the dimensions of the holes in an annular end plate are reduced or the holes are positioned away from the edges to prevent this phenomenon from occurring, the holes may end up being blocked. If the end plate blocks the holes in the rotor core, the refrigerant will not easily come into contact with the holes, reducing the cooling efficiency of the rotor. Furthermore, if the end plate blocks the holes in the rotor core, the entire end plate will be relatively heavy, making it difficult to reduce the weight of the rotor.

[0006] Therefore, an object of the present invention is to provide a rotor, a rotating electric machine, and a vehicle drive device that can efficiently cool the rotor while reducing the rotor's weight.

[0007] In order to solve the above-mentioned problems, the rotor of the present invention includes a rotor core formed by stacking a shaft and plate-like members each having a through hole formed therein in a direction of a rotation axis and into which the shaft is fitted, end plates that sandwich and fix the rotor core from both sides in the direction of the rotation axis, and a magnet cover that covers the surface of the end plate located opposite the rotor core. The end plates have an annular portion into which the shaft is fitted, a plurality of bolt insertion portions that protrude radially outward from the annular portion and have bolt insertion holes for inserting bolts, and notches formed between two adjacent bolt insertion portions in a direction around the rotation axis and recessed toward the rotation axis, the notches being positioned so as to at least partially overlap the through holes in the direction of the rotation axis, and the magnet cover has holes formed therein that at least partially overlap the notches in the direction of the rotation axis.

[0008] In the rotor of the present invention, the hole formed in the magnet cover at least partially overlaps with the punched hole in the direction of the rotation axis.

[0009] A rotating electric machine according to the present invention includes the rotor described above.

[0010] A vehicle drive device according to the present invention includes the above-described rotating electric machine.

[0011] According to the present invention, it is possible to efficiently cool the rotor while reducing the weight of the rotor.

[0012] 1 is an exploded perspective view of a vehicle drive device according to an embodiment; FIG. 2 is a perspective view of an end plate according to an embodiment; FIG. 3 is a perspective view of an end plate and a rotor core according to an embodiment;

[0013] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is an exploded perspective view of a vehicle drive device according to an embodiment. The vehicle drive device 1 is mounted on, for example, an electric vehicle to rotate the wheels of the electric vehicle. The vehicle drive device 1 also includes a motor, which is an example of a rotating electric machine.

[0014] As shown in Fig. 1, the vehicle drive device 1 includes a housing 10, a bearing 20, a resolver 30, a stator 40, a shaft 50, a rotor 60, a bearing 70, and a bracket 80. The vehicle drive device 1, excluding the housing 10, forms a motor, which is an example of a rotating electric machine. In the following description, an X-axis parallel to the rotation axis of the rotor 60, a Y-axis perpendicular to the X-axis, and a Z-axis perpendicular to the X-axis and Y-axis are used. The X-axis, Y-axis, and Z-axis form a right-handed system.

[0015] The housing 10 incorporates a gear case frame assembly 11, an inverter assembly 12, and terminals 13. The gear case frame assembly 11 includes a transmission and a group of associated parts. The inverter assembly 12 includes an inverter and a group of associated parts. The terminals 13 are electrically connected to a coil 42 (described later) and supply AC power generated by the inverter to the coil 42.

[0016] The outer ring of the bearing 20 is fitted into the housing 10. The shaft 50 is fitted into the inner ring of the bearing 20, and the end of the shaft 50 on the −X direction side is supported in a manner that allows it to rotate around the rotation axis.

[0017] The resolver 30 is, for example, a one-phase excitation, two-phase output variable reluctance (VR) resolver, and includes a resolver connector 31, a VR resolver stator 32, a VR resolver rotor 33, and a fixing ring 34.

[0018] The resolver connector 31 is attached to the housing 10, receives the analog signal output by the VR resolver stator 32, and transmits it to a resolver digital (RD) converter (not shown). The RD converter converts the analog signal into a digital signal. This digital signal is used to calculate the rotation angle of the rotor 60.

[0019] The VR resolver stator 32 is attached to the housing 10 and includes a primary coil that applies a reference signal to the VR resolver rotor 33, and a secondary coil that is electrically connected to the RD converter. When a reference signal is input to the primary coil, the VR resolver stator 32 outputs the above-mentioned analog signal from the secondary coil.

[0020] The VR resolver rotor 33 includes a relay coil and is attached to the shaft 50 by a fixing ring 34. The VR resolver rotor 33 rotates around the rotation axis together with the shaft 50, thereby changing the relative positions of the primary coil and secondary coil of the VR resolver 32.

[0021] The stator 40 includes a stator core 41, a coil 42, terminals 43, a thermistor 44, and a thermistor connector 45. The stator core 41 is a cylindrical member into which the shaft 50 and rotor 60 are inserted, and has multiple teeth formed on the inside. The coil 42 is formed by winding copper wire around the teeth. When current is applied to the coil 42, it generates a magnetic force that rotates the rotor 60. The terminals 43 electrically connect the coil 42 to the terminals 13. The thermistor 44 outputs an electrical signal that depends on the temperature of the coil 42. The thermistor connector 45 receives the electrical signal and transmits it to a device that uses the electrical signal to calculate the temperature of the coil 42.

[0022] The shaft 50 is a rod-shaped member that is fitted into a rotor core 61 (described later) and supports the rotor 60 in a manner that allows the rotor 60 to rotate around a rotation axis. The shaft 50 is hollow, and a helical gear is formed at the end on the +X direction side.

[0023] The rotor 60 includes a rotor core 61 , an end plate 62 , an end plate 63 , a magnet cover 64 , a magnet cover 65 , a bolt 66 , and a bolt 67 .

[0024] The rotor core 61 is formed by stacking plate-shaped members in the direction of the rotation axis so that the edges of holes (described later) coincide on a plane perpendicular to the rotation axis, and the shaft 50 is fitted into the plate-shaped members. The plate-shaped members are made of electromagnetic steel, and have a shaft fitting hole 61H, a magnet fitting hole 610H, a hole 611H, and a hole 612H formed therein.

[0025] The shaft insertion hole 61H is formed by passing through the plate-like member in the direction of the rotation axis, and is a hole into which the shaft 50 is inserted. The magnet insertion hole 610H is a hole into which the magnet 61M is inserted. The punched holes 611H and 612H are holes formed by passing through the plate-like member in the direction of the rotation axis. The punched holes 611H and 612H are formed to relieve stress generated by the rotation of the rotor 60, relieve stress generated by the shaft 50 being shrink-fitted to the rotor core 61, reduce the weight of the rotor 60, improve the cooling efficiency of the rotor 60, etc.

[0026] The end plates 62 and 63 are members that sandwich and secure the rotor core 61 from both sides in the direction of the rotation axis. FIG. 2 is a perspective view showing an end plate according to an embodiment. FIG. 2 shows the end plate 62. FIG. 3 is a perspective view showing the end plate and the rotor core according to an embodiment. As shown in FIG. 2, the end plate 62 has an annular portion 620, a bolt insertion portion 621, and a bolt insertion portion 622. Also, as shown in FIG. 2, the end plate 62 is formed with a shaft insertion hole 620H, a bolt insertion hole 621H, a bolt insertion hole 622H, two recesses 62D, and a notch 62C.

[0027] The annular portion 620 is an annular portion of the end plate 62 around a shaft insertion hole 620H into which the shaft 50 is inserted. The shaft insertion hole 620H penetrates the end plate 62 in the direction of the rotation axis, and is a hole into which the shaft 50 is inserted.

[0028] The bolt insertion portion 621 protrudes outward in the radial direction from the annular portion 620, and has a bolt insertion hole 621H formed therein, into which the bolt 66 shown in Fig. 3 is inserted. The bolt insertion hole 621H is a circular hole that penetrates the end plate 62 in the direction of the rotation axis, and has a chamfered edge.

[0029] The bolt insertion portion 622 protrudes outward in the radial direction from the annular portion 620, and has a bolt insertion hole 622H formed therein, into which the bolt 67 shown in Fig. 3 is inserted. The bolt insertion hole 622H is a circular hole that penetrates the end plate 62 in the direction of the rotation axis.

[0030] The two recesses 62D are formed on both sides of the bolt insertion hole 621H or the bolt insertion hole 622H in the circumferential direction of a circle centered on the rotation axis. The recesses 62D are formed to avoid interference between the end plate 62 and the crimps that connect the plate-like members that form the rotor core 61.

[0031] The notch 62C is formed between the bolt insertion portions 621 and 622 that are adjacent in the direction around the rotation axis, and is recessed toward the rotation axis. As shown in Fig. 3, the notch 62C overlaps the entirety of the punched hole 611H in the direction of the rotation axis. As shown in Fig. 3, the bolts 66 and 67 are inserted into the punched hole 612H.

[0032] The magnet cover 64 covers the surface of the end plate 62 opposite the rotor core 61, i.e., the surface on the -X direction side of the end plate 62. This prevents the magnet 61H from falling off the rotor core 61. The magnet cover 64 also has a hole 64H formed therein, the hole 64H at least partially overlapping in the direction of the rotation axis with the notch 62C formed in the end plate 62. The hole 64H is shown in FIG. 1. The hole 64H may also at least partially overlap in the direction of the rotation axis with the hole 611H formed in the rotor core 61.

[0033] The magnet cover 65 covers the surface of the end plate 63 opposite the rotor core 61, i.e., the surface on the +X direction side of the end plate 63. In this way, the magnet cover 65 prevents the magnet 61H from falling off the rotor core 61. The magnet cover 65 also has a hole 65H formed therein, which at least partially overlaps in the direction of the rotation axis with a notch similar to the notch 62C formed in the end plate 63. The hole 65H is shown in FIG. 1. The hole 65H may also at least partially overlap in the direction of the rotation axis with a hole 611H formed in the rotor core 61.

[0034] The outer ring of bearing 70 is fitted into bracket 80. The shaft 50 is fitted into the inner ring of bearing 70, and the end of shaft 50 on the +X direction side is supported in a manner that allows rotation around the rotation axis. In addition, bearing 70 is fixed to shaft 50 by a snap ring 71.

[0035] The bracket 80 is a cover that closes the opening of the housing 10 from the +X direction. The bracket 80 is arranged to sandwich the bearing 20, the resolver 30, the stator 40, the shaft 50, the rotor 60, the bearing 70, etc. together with the housing 10 in the X direction.

[0036] The rotor 60 according to the embodiment has been described above. The rotor 60 includes an end plate 62 and an end plate 63. The end plate 62 has a notch 62C recessed toward the rotation axis at a portion closest in the direction around the rotation axis and located at a distance greater than a predetermined distance from the bolt insertion hole 621H or the bolt insertion hole 622H into which the bolt 66 or the bolt 67 is inserted. The end plate 62 is also positioned such that the notch 62C overlaps with the punched hole 611H in the direction of the rotation axis. The end plate 63 is a member similar to the end plate 62.

[0037] As a result, end plates 62 and 63 do not block ventilation holes 611H formed in rotor core 61. Therefore, end plates 62 and 63 allow refrigerant such as cooling oil atomized by the rotation of the rotor to flow through holes 64H or 65H into ventilation holes 611H by cavity flow, thereby efficiently cooling rotor core 61H. Furthermore, because rotor 60 has notch 62C formed in end plate 62 and a notch similar to notch 62C formed in end plate 63, rotor 60 is lighter than end plates without notch 62C, etc.

[0038] Furthermore, because the rotor 60 has the cutouts 62C formed in the end plates 62, the contact area between the rotor core 61 and the magnet cover 64 is increased, thereby improving the heat dissipation performance from the rotor core 61 to the magnet cover 64. Similarly, because the rotor 60 has cutouts similar to the cutouts 62C formed in the end plates 63, the contact area between the rotor core 61 and the magnet cover 65 is increased, thereby improving the heat dissipation performance from the rotor core 61 to the magnet cover 65.

[0039] Furthermore, the hole 64H formed in the magnet cover 64 and the hole 65H formed in the magnet cover 65 may at least partially overlap with the hole 611H formed in the rotor core 61 in the direction of the rotation axis.

[0040] This allows the rotor 60 to smoothly introduce refrigerant such as cooling oil that has been atomized by the rotation of the rotor through the cavity flow via the holes 64H and the notches 62C into the vent holes 611H, thereby efficiently cooling the rotor core 61H. Similarly, this allows the rotor 60 to smoothly introduce refrigerant such as cooling oil that has been atomized by the rotation of the rotor through the cavity flow via the holes 65H and the notches similar to the notches 62C into the vent holes 611H, thereby efficiently cooling the rotor core 61H.

[0041] In the above-described embodiment, the end plates 62 and 63 are incorporated into the motor of the vehicle drive device 1, but the present invention is not limited to this. The end plates 62 and 63 may be incorporated into the motor of a general drive device, rather than the vehicle drive device 1. Furthermore, the end plates 62 and 63 may be incorporated into a generator that converts mechanical energy into electrical energy, rather than the motor of the drive device.

[0042] In the above-described embodiment, the case where the notch 62C overlaps the entire perforation hole 611H in the direction of the rotation axis has been described as an example, but the present invention is not limited to this. The notch 62C may overlap a part of the perforation hole 611H in the direction of the rotation axis.

[0043] Furthermore, in the above-described embodiment, the bolts 66 and 67 are inserted into the perforations 612H, but this is not limiting. The bolts 66 and 67 may be inserted into the perforations 611H. In this case, the cutouts 62C are arranged so that at least a portion of each cutout 62C overlaps with the perforations 612H in the direction of the rotation axis. Furthermore, the magnet cover 64 is arranged so that at least a portion of each hole 64H overlaps with the perforations 612H in the direction of the rotation axis. Similarly, the magnet cover 65 is arranged so that at least a portion of each hole 65H overlaps with the perforations 612H in the direction of the rotation axis.

[0044] In the above-described embodiment, the recessed portion 62D is formed in the end plate 62, but the present invention is not limited to this. In the end plate according to the embodiment, the recessed portion 62D may not be formed if the rotor core is formed by connecting plate-like members together by a method other than crimping, such as adhesive.

[0045] The preferred embodiments of the present invention have been described above. However, the present invention is not limited to the above-described embodiments. In other words, the present invention includes embodiments in which various modifications, substitutions, design changes, etc. have been made based on the spirit of the present invention, and does not exclude these embodiments.

[0046] 1... Vehicle drive device, 50... Shaft, 60... Rotor, 61... Rotor core, 62, 63... End plates, 64, 65... Magnet cover

Claims

1. A rotor comprising: a shaft; a rotor core formed by stacking plate-like members each having a hole formed therein in the direction of the rotation axis, and into which the shaft is fitted; end plates that sandwich and fix the rotor core from both sides in the direction of the rotation axis; and a magnet cover covering the surface of the end plate located opposite the rotor core, wherein the end plates have an annular portion into which the shaft is fitted, a plurality of bolt insertion portions that protrude radially outward from the annular portion and have bolt insertion holes into which bolts are inserted, and a notch formed between two adjacent bolt insertion portions in a direction around the rotation axis and recessed toward the rotation axis, the notch being positioned so that at least a portion of the notch overlaps with the hole in the direction of the rotation axis; and the magnet cover has a hole formed in which at least a portion of the notch overlaps with the notch in the direction of the rotation axis.

2. The rotor according to claim 1, wherein the hole formed in the magnet cover at least partially overlaps with the punched hole in the direction of the rotation axis.

3. A rotating electrical machine equipped with the rotor according to claim 1 or 2.

4. A vehicle drive device comprising the rotating electric machine according to claim 3.

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