Rotary electrical machine

Abstract

This rotary electrical machine comprises: a cylindrical stator; a rotor that is disposed inside the stator and that is formed by layering plate-shaped members in the direction of the rotation axis; and a shaft that is fitted into the rotor and that supports the rotor in such a manner that the rotor can rotate about the rotation axis. The rotor has an in-rotor conduit that is formed by layering a plurality of plate-shaped members in each of which at least one conduit forming hole is formed, in a state where some of openings of the conduit forming holes overlap in the rotation axis direction, and that has an outlet which communicates with a space between the stator and the rotor. The shaft has an in-shaft conduit that communicates with an outlet of an in-housing conduit formed in a housing of a motor and with an inlet of the in-rotor conduit.

Description

Rotating electric machines

[0001] The present invention relates to a rotating electric machine.

[0002] Rotating electric machines such as motors and generators sometimes have difficulty operating efficiently due to heat generated by their coils during operation. For this reason, technologies for cooling the coils installed in rotating electric machines have been developed. One example of such technologies is the cooling device disclosed in Patent Document 1. This cooling device includes a cooling oil pipe that is disposed along the rotational axis above the vertically highest points of the stator core and coil ends, and that discharges cooling oil from a discharge hole to an oil application point on the outer circumferential surface of the coil end.

[0003] Japanese Patent Application Laid-Open No. 2006-115651

[0004] However, the cooling device described above cools the portion of the coil where the cooling oil does not pass only by heat conduction from that portion to the portion where the cooling oil does pass. As a result, the cooling device described above may not be able to cool the coil efficiently. Furthermore, the cooling device described above may not be able to cool the coil uniformly because the temperature of the cooling oil increases as it flows downward.

[0005] SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a rotating electric machine that can efficiently cool the coils mounted therein.

[0006] In order to achieve the above object, a rotating electric machine of the present invention includes a cylindrical stator, a rotor disposed inside the stator and formed by stacking plate-like members in the direction of a rotation axis, and a shaft fitted into the rotor and supporting the rotor so that the rotor can rotate about the rotation axis. The rotor is formed by stacking a plurality of the plate-like members, each having at least one conduit-forming hole, such that openings of the conduit-forming holes partially overlap in the direction of the rotation axis, and includes an internal-rotor conduit whose outlet leads to a space between the stator and the rotor. The shaft has an internal-shaft conduit that leads to an outlet of an internal-casing conduit formed in a motor housing and to an inlet of the internal-rotor conduit.

[0007] At least one of the conduit-forming holes may be a depression formed in the surface of the plate-like member or a through-hole that penetrates the plate-like member.

[0008] The rotor internal conduit may have an outlet formed within a predetermined distance from a plane perpendicular to the rotation axis of the rotor, passing through the center of the rotor in the direction of the rotation axis, and an intersection between the plane and a coil attached to the stator.

[0009] The rotor internal conduit may have an outlet formed within a predetermined distance from a portion of the coil attached to the stator whose temperature is equal to or higher than a predetermined temperature.

[0010] The rotor internal conduit may be formed by stacking two types of plate-like members having conduit-forming holes formed at different positions.

[0011] The rotor internal conduit may be formed along a straight line perpendicular to the rotation axis of the rotor.

[0012] At least one of the conduit forming holes may be formed between two adjacent poles in the rotor.

[0013] According to the present invention, it is possible to efficiently cool a coil mounted on a rotating electrical machine.

[0014] Fig. 1 is a cross-sectional view taken along a plane passing through the rotation axis of the motor according to the embodiment; Fig. 2 is a cross-sectional view taken along a plane perpendicular to the rotation axis of the motor according to the embodiment; Fig. 3 is a perspective view showing an in-shaft conduit and an in-rotor conduit according to the embodiment; Fig. 4 is a view showing a plate-shaped member having holes formed therein that form the in-rotor conduit according to the embodiment; Fig. 5 is a view showing a plate-shaped member having holes formed therein that form the in-rotor conduit according to the embodiment;

[0015] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. Fig. 1 is a cross-sectional view of a motor according to an embodiment taken along a plane passing through a rotation axis of the motor. Fig. 2 is a cross-sectional view of a motor according to an embodiment taken along a plane perpendicular to the rotation axis of the motor.

[0016] The motor 1 is mounted on, for example, an electric vehicle to rotate the wheels of the electric vehicle. The motor 1 is an example of a rotating electric machine. As shown in FIGS. 1 and 2 , the motor 1 includes a housing 20, a housing 30, housing forming members 40, 50, a shaft 60, a rotor 70, and a stator 80. In the following description, an X-axis parallel to the rotation axes of the shaft 60 and the rotor 70, 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.

[0017] The housing 20 is a cylindrical member that houses the shaft 60, rotor 70, stator 80, etc. The housing 20 also has a conduit 21, a filter 22, and a conduit 23 attached thereto, forming an internal conduit 20P inside the housing 20. The conduit 21 is a pipe into which a refrigerant flows to cool each part of the motor 1 by flowing through the parts, and is attached to the housing 20 along the Z direction. The internal conduit 20P is a cylindrical pipe into which the refrigerant flows from the conduit 21. The filter 22 prevents foreign matter contained in the refrigerant that has flowed down to the −Z direction side of the housing 20 or the housing 30 from entering the conduit 23. The conduit 23 is a cylindrical pipe into which the refrigerant that has flowed down to the −Z direction side of the housing 20 or the housing 30 flows.

[0018] The housing 30 is a cylindrical member attached to the end of the housing 20 on the -X direction side. An internal housing conduit 30P is formed inside the housing 30. The internal housing conduit 30P is a cylindrical tube into which the refrigerant flows from the internal housing conduit 20P. The housing 30 also has a hole into which the end of the shaft 60 on the -X direction side is inserted and a hole into which a bearing 64 (described later) is inserted.

[0019] Housing forming member 40 is a disk-shaped member that covers the opening on the +X direction side of housing 20. Housing forming member 40 also has formed therein a hole into which the end of shaft 60 on the +X direction side is inserted, a hole into which bearing 61 is attached, a hole into which bearing 62 is attached, and a hole into which bearing 63 is attached.

[0020] The housing forming member 50 is a plate-like member that covers the opening on the −X direction side of the housing 30. An internal housing conduit 50P is also formed in the housing forming member 50. The internal housing conduit 50P is a cylindrical tube into which the refrigerant flows from the internal housing conduit 30P.

[0021] The shaft 60 is a rod-shaped member that is fitted into the rotor 70 and supports the rotor 70 in a manner that allows the rotor 70 to rotate about the rotation axis. The end of the shaft 60 on the +X direction side is inserted into a hole formed in the housing 40 and is rotatably supported by bearings 61, 62, and 63 attached to the housing 40. The end of the shaft 60 on the −X direction side is inserted into a hole formed in the housing 30 and is rotatably supported by bearing 64 attached to the housing 30.

[0022] FIG. 3 is a perspective view showing an internal-shaft conduit according to an embodiment. The shaft 60 is formed with an internal-shaft conduit 60P. As shown in FIG. 1, the internal-shaft conduit 60P includes a conduit 601P, a conduit 602P, and a conduit 603P. As shown in FIG. 1, the conduit 601P is a cylindrical tube into which the refrigerant flows from the internal-casing conduit 50P and leads to the outlet of the internal-casing conduit 50P. As shown in FIGS. 1 to 3, the conduit 602P is a cylindrical tube into which the refrigerant flows from the conduit 601P and has a larger cross-sectional area taken along a plane parallel to the YZ plane than the conduit 601P. As shown in FIGS. 1 to 3, the conduit 603P is a cylindrical tube into which the refrigerant flows from the conduit 602P and leads to the inlet of the internal-rotor conduit 70P, which will be described later.

[0023] The rotor 70 is a member that rotates due to the magnetic force generated by the stator 80 and is disposed inside the stator 80. The rotor 70 is made by stacking multiple annular plate-shaped members in the direction of the rotation axis. These plate-shaped members are made of electromagnetic steel sheets. Each of these plate-shaped members has a hole in the center into which the shaft 60 is inserted, and holes into which permanent magnets are inserted are regularly arranged along the circumferential direction.

[0024] 3 is a perspective view showing an internal-rotor conduit according to an embodiment. The rotor 70 includes an internal-rotor conduit 70P. The internal-rotor conduit 70P is a pipe into which the refrigerant flows from the conduit 603P. The inlet of the internal-rotor conduit 70P is connected to the outlet of the conduit 603, and the outlet of the internal-rotor conduit 70P is connected to the space between the stator 80 and the rotor 70. The internal-rotor conduit 70P is formed by stacking plate-like members each having at least one hole formed therein such that the openings of the hole overlap in a direction parallel to the rotational axis of the rotor 70. Specifically, the internal-rotor conduit 70P is formed by stacking two types of plate-like members each having a hole formed at different positions.

[0025] 4 is a diagram showing a plate-shaped member 71 having holes formed therein for forming the rotor internal conduits according to the embodiment. As shown in FIG. 4, plate-shaped member 71 has permanent magnet insertion holes 701, permanent magnet insertion holes 703, stress relief holes 705, shaft insertion holes 706, conduit forming holes 711H, 712H, 713H, and 714H formed therein.

[0026] As shown in Fig. 4, a total of eight permanent magnet insertion holes 701 and eight permanent magnet insertion holes 703 are formed at equal intervals in the circumferential direction. Each permanent magnet insertion hole 701 is a hole that penetrates the plate-like member 71, and as shown in Fig. 2, a permanent magnet 702 is inserted into each permanent magnet insertion hole 701. Similarly, each permanent magnet insertion hole 703 is a hole that penetrates the plate-like member 71, and as shown in Fig. 2, a permanent magnet 704 is inserted into each permanent magnet insertion hole 701.

[0027] Furthermore, a pair of permanent magnets 702 and 704 adjacent to each other in the circumferential direction forms one pole of the motor 1. For example, the permanent magnets 702 and 704 form a south pole or a north pole in the region M shown in Fig. 2. Similarly, other pairs of permanent magnets 702 and 704 also form such poles.

[0028] As shown in Figure 4, there are four stress relief holes 705 in total, all of which are formed at equal intervals in the circumferential direction. Each of the stress relief holes 705 is a hole that passes through the plate-like member 71, and is formed for the purposes of alleviating stress that is concentrated at specific points on the plate-like member 71 due to centrifugal force generated as the rotor 70 rotates, and for the purposes of reducing the weight of the rotor 70. Bolts may also be inserted into the stress relief holes 705 when the rotor 70 is assembled.

[0029] The shaft insertion hole 706 is a circular hole that is provided in the center of the plate-like member 71 and passes through the plate-like member 71. The shaft 60 is inserted into the shaft insertion hole 706.

[0030] Conduit forming holes 711H, 712H, 713H, and 714H are all recesses formed in the surface of plate-shaped member 71. Specifically, conduit forming holes 711H, 712H, 713H, and 714H are all holes in which the surface of plate-shaped member 71 is recessed toward the +X direction in a narrow rectangular region that is elongated in a direction perpendicular to the rotation axis of rotor 70. Furthermore, conduit forming holes 711H, 712H, 713H, and 714H all have the same depth.

[0031] Conduit forming holes 711H, 712H, 713H, and 714H are located at the same circumferential position and have the same short side lengths. Furthermore, conduit forming holes 711H, 712H, 713H, and 714H have long sides parallel to a line perpendicular to the rotational axis of rotor 70. Furthermore, conduit forming holes 711H, 712H, 713H, and 714H are arranged in the following order outward from shaft insertion hole 706: conduit forming hole 711H, conduit forming hole 712H, conduit forming hole 713H, and conduit forming hole 714H. Furthermore, conduit forming holes 711H, 712H, 713H, and 714H are formed between two adjacent poles.

[0032] 5 is a diagram showing a plate-shaped member 72 having holes formed therein that form rotor internal conduits according to an embodiment. As shown in Fig. 5, plate-shaped member 72 has permanent magnet insertion holes 701, permanent magnet insertion holes 703, stress relief holes 705, shaft insertion holes 706, conduit forming holes 721H, conduit forming holes 722H, and conduit forming holes 723H formed therein. Note that permanent magnet insertion holes 701, permanent magnet insertion holes 703, stress relief holes 705, and shaft insertion holes 706 shown in Fig. 5 are the same as permanent magnet insertion holes 701, permanent magnet insertion holes 703, stress relief holes 705, and shaft insertion holes 706 shown in Fig. 4, respectively.

[0033] Conduit forming holes 721H, 722H, and 723H are all recesses formed in the surface of plate-shaped member 72. Specifically, conduit forming holes 721H, 722H, and 723H are all holes in which the surface of plate-shaped member 71 is recessed toward the −X direction in a narrow rectangular region extending in a direction perpendicular to the rotation axis of rotor 70. Conduit forming holes 721H, 722H, and 723H all have the same depth.

[0034] Conduit forming holes 721H, 722H, and 723H are positioned at the same position in the circumferential direction and have the same short side lengths as conduit forming holes 711H, 712H, 713H, and 714H. Furthermore, the long sides of conduit forming holes 721H, 722H, and 723H are parallel to a line perpendicular to the rotational axis of rotor 70. Furthermore, conduit forming holes 721H, 722H, and 723H are arranged in this order from shaft insertion hole 706 outward. Furthermore, conduit forming holes 721H, 722H, and 723H are formed between two adjacent poles.

[0035] Plate-like member 71 and plate-like member 72 are stacked such that the opening of conduit forming hole 711H, conduit forming hole 712H, conduit forming hole 713H, or conduit forming hole 714H overlaps in the X direction with the opening of conduit forming hole 721H, conduit forming hole 722H, or conduit forming hole 723H. In this case, the +Z side of the opening of conduit forming hole 711H overlaps in the X direction with the −Z side of the opening of conduit forming hole 721H. Also, in this case, the +Z side of the opening of conduit forming hole 721H overlaps in the X direction with the −Z side of the opening of conduit forming hole 712H.

[0036] Similarly, in the above case, the +Z side of the opening of conduit forming hole 712H and the −Z side of the opening of conduit forming hole 722H overlap in the X direction. In the above case, the +Z side of the opening of conduit forming hole 722H and the −Z side of the opening of conduit forming hole 713H overlap in the X direction. In the above case, the +Z side of the opening of conduit forming hole 713H and the −Z side of the opening of conduit forming hole 723H overlap in the X direction. In the above case, the +Z side of the opening of conduit forming hole 723H and the −Z side of the opening of conduit forming hole 714H overlap in the X direction.

[0037] Due to the shapes and arrangement of the above-described conduit forming holes 711H, 721H, etc., the rotor internal conduit 70P is formed along a straight line perpendicular to the rotation axis of the rotor 70, and meanders within a plane including the straight line. The rotor internal conduit 70P also leads to the outlet of the conduit 603P, and is a pipe that leads to the space between the stator 80 and the rotor 70.

[0038] Furthermore, the internal-rotor conduit 70P has an outlet formed within a predetermined distance from the intersection of a plane perpendicular to the rotational axis of the rotor 70 and passing through the center of the rotor 70 in the direction of the rotational axis with the coil 82 attached to the stator 80. The portion of the coil 82 close to the intersection is more susceptible to eddy current loss and heat generation than the other portions. Therefore, the predetermined distance needs to be a distance that allows a sufficient amount of refrigerant to be supplied from the internal-rotor conduit 70P to the portion of the coil 82 close to the intersection where heat generation due to eddy current loss is greater than that of the other portions of the coil 82.

[0039] The rotor 70 also includes a clamp 73, a clamp 74, a clamp cover 75, and a clamp cover 76. The clamps 73 and 74 are annular members that clamp and fasten the plate-like members 71, 72, and other plate-like members that form the rotor 70 in the X direction. The clamp cover 75 is an annular member that covers the end face of the rotor 70 on the +X direction side and the clamp 73. The clamp cover 76 is an annular member that covers the end face of the rotor 70 on the -X direction side and the clamp 74.

[0040] 1 and 2, the stator 80 includes a stator core 81 and a coil 82. The stator core 81 is a cylindrical member into which the shaft 60 and the rotor 70 are inserted, and has a plurality of teeth formed on the inside. The coil 82 is formed by winding copper wire around the teeth. When current is applied to the coil 82, it generates a magnetic force that rotates the rotor 70.

[0041] Next, the flow of refrigerant according to this embodiment will be described with reference to Figures 1 and 2. After flowing into conduit 21, the refrigerant flows through in-casing conduits 20P, 30P, and 50P, as shown by the arrows in Figure 1, and then flows into conduit 601P, which constitutes in-shaft conduit 60P. Next, the refrigerant flows through conduits 601P, 602P, and 603P, which constitute in-shaft conduit 60P, and then flows into in-rotor conduit 70P.

[0042] The refrigerant present inside the conduit 603P or the in-rotor conduit 70P is released into the space between the stator 80 and the rotor 70 by centrifugal force generated by the rotation of the shaft 60 and the rotor 70, and cools the coil 82, etc. Next, the refrigerant passes through the space between the stator 80 and the rotor 70 and flows down to the −Z direction side of the housing 20 or the housing 30.

[0043] The refrigerant then passes through filter 22 and flows into conduit 23. The refrigerant that has flowed into conduit 23 flows into a pump installed at the end of conduit 23 and is sent to a water-cooled cooler installed at the end of the pump. The refrigerant that has been cooled by the water-cooled cooler flows back into conduit 21.

[0044] The motor 1, which is an example of a rotating electric machine according to an embodiment, has been described above. The motor 1 includes a shaft conduit 60P and a rotor conduit 70P. The shaft conduit 60P communicates with the outlet of the housing conduit 50P formed in the housing of the motor 1 and the inlet of the rotor conduit 70P. The rotor conduit 70P is formed by stacking plate-shaped members 71 and 72 such that a portion of the openings of the conduit forming holes 711H and 712H overlap in the direction of the rotation axis. The rotor conduit 70P has an outlet that communicates with the space between the stator 80 and the rotor 70.

[0045] As a result, the motor 1 can supply the refrigerant directly to the space between the stator 80 and the rotor 70, thereby efficiently cooling the coil 82. The motor 1 can also supply the refrigerant to the in-shaft conduit 60P, thereby efficiently cooling the shaft 60P. The motor 1 can also supply the refrigerant to the in-rotor conduit 70P, thereby efficiently cooling the rotor 70. Furthermore, by efficiently cooling the coil 82, the motor 1 can reduce the volume of the coil 82, thereby reducing the cost of manufacturing the coil 82 and enabling the motor 1 to be made more compact.

[0046] Furthermore, the rotor internal conduit 70P is perpendicular to the rotation axis of the rotor 70, and has an outlet formed within a predetermined distance from the intersection of a plane passing through the center of the rotor 70 in the direction of the rotation axis and the coil 82 attached to the stator 80. This allows the motor 1 to supply a sufficient amount of refrigerant to the part of the coil 82 that generates particularly large amounts of heat due to eddy current loss, and to sufficiently cool that part.

[0047] Furthermore, the rotor internal conduit 70P is formed by stacking two types of plate-like members, 71 and 72, which have holes formed in different positions. This makes it possible to form the rotor 70 of the motor 1 using only three types of plate-like members: the plate-like members 71 and 72, and a plate-like member that does not have the conduit-forming holes 711H and 721H for forming the rotor internal conduit 70P. Therefore, the motor 1 requires only three types of molds to manufacture the rotor 70, thereby reducing the cost required to manufacture the rotor 1.

[0048] Furthermore, the intra-rotor conduit 70P is formed along a straight line perpendicular to the rotation axis of the rotor 70. This allows the motor 1 to efficiently transfer the centrifugal force generated by the rotation of the rotor 70 to the refrigerant present inside the intra-rotor conduit 70P and efficiently release the refrigerant into the space between the stator 80 and the rotor 70. Therefore, the motor 1 efficiently cools the coil 82.

[0049] Furthermore, conduit forming holes 711H, 712H, 713H, and 714H are formed between two adjacent poles on rotor 70. Similarly, conduit forming holes 721H, 722H, and 723H are formed between two adjacent poles on rotor 70. This allows motor 1 to suppress the occurrence of magnetic flux saturation and torque reduction caused by the narrowing of the path of magnetic flux passing through each pole.

[0050] In the above-described embodiment, the conduit-forming holes 711H and the like shown in Fig. 4 are recesses formed in the surface of the plate-like member 71, but this is not intended to be limiting. Furthermore, the conduit-forming holes 712H and the like shown in Fig. 5 are recesses formed in the surface of the plate-like member 72, but this is not intended to be limiting. At least one of the holes forming the rotor internal conduits may be a through-hole that penetrates the plate-like member.

[0051] Furthermore, the outlet of the internal rotor conduit 70P may be formed within a predetermined distance from a portion of the coil 82 attached to the stator 80 where the temperature exceeds a predetermined temperature. This predetermined distance must be a distance that allows a sufficient amount of refrigerant to be supplied from the internal rotor conduit 70P to the portion of the coil 82 where the temperature exceeds the predetermined temperature. This allows the motor 1 to supply a sufficient amount of refrigerant to a portion of the coil 82 where the temperature exceeds the predetermined temperature due to the influence of the structure of the casing 20 or other components around the coil 82, and to sufficiently cool that portion.

[0052] Furthermore, in the above-described embodiment, the rotor internal conduit 70P is formed along a straight line perpendicular to the rotational axis of the rotor 70, but this is not limiting. The rotor internal conduit according to the embodiment may have any path from the inlet to the outlet. For example, the rotor internal conduit according to the embodiment may be formed along a straight line that passes through the rotational axis of the rotor 70 from the inlet to the outlet but is not perpendicular to the rotational axis of the rotor 70. Furthermore, for example, the rotor internal conduit according to the embodiment may be curved midway. In these cases, three or more types of plate-shaped members having different hole patterns are required.

[0053] In the above-described embodiment, the motor 1 is a motor mounted on an electric vehicle to rotate the wheels of the electric vehicle, but the present invention is not limited to this. The motor according to the embodiment may be a motor used for purposes other than rotating the wheels of an electric vehicle.

[0054] In the above-described embodiment, the motor 1 has been described as an example of a rotating electric machine, but the rotating electric machine according to the embodiment may be a generator that converts mechanical energy into electrical energy, instead of the motor 1 that converts electrical energy into mechanical energy.

[0055] 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.

[0056] DESCRIPTION OF SYMBOLS 1...motor, 60...shaft, 600P...conduit inside shaft, 70...rotor, 70P...conduit inside rotor, 711H, 712H, 713H, 714H, 721H, 722H, 723H...holes, 80...stator, 82...coil

Claims

1. A rotating electric machine comprising: a cylindrical stator; a rotor disposed inside the stator and formed by stacking plate-like members in the direction of a rotation axis; and a shaft fitted into the rotor and supporting the rotor in a manner that allows the rotor to rotate around the rotation axis, wherein the rotor is formed by stacking a plurality of the plate-like members, each having at least one conduit forming hole, in a state where portions of the openings of the conduit forming holes overlap in the direction of the rotation axis, and the rotor has an internal conduit whose outlet leads to a space between the stator and the rotor, and the shaft has an internal conduit that leads to an outlet of an internal conduit formed in a motor housing and to an inlet of the internal rotor conduit.

2. A rotating electric machine according to claim 1, wherein at least one of the conduit forming holes is a recess formed in the surface of the plate-like member or a through-hole penetrating the plate-like member.

3. A rotating electric machine according to claim 2, wherein the outlet of the rotor internal conduit is formed within a predetermined distance from the intersection of a plane passing through the center of the rotor in the direction of the rotation axis and the coil attached to the stator, the plane being perpendicular to the rotation axis of the rotor.

4. A rotating electric machine according to claim 2, wherein the outlet of the rotor internal conduit is formed within a predetermined distance from a portion of the coil attached to the stator where the temperature exceeds a predetermined temperature.

5. A rotating electric machine according to claim 2 or 3, wherein the rotor internal conduit is formed by stacking two types of plate-like members having conduit forming holes formed at different positions.

6. A rotating electric machine according to claim 2 or 3, wherein the rotor internal conduit is formed along a straight line perpendicular to the rotation axis of the rotor.

7. A rotating electric machine according to claim 2 or 3, wherein at least one of the conduit forming holes is formed between two adjacent poles in the rotor.

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