Rotating electric machine

Abstract

The present invention provides a rotating electrical machine, comprising: a rotor; and a stator disposed on the outside in the radial direction of the rotor, in which the rotor has: a first flow path extending in the radial direction and having a first discharge opening that opens toward the outside in the radial direction; and a second flow path that extends in the radial direction and has a second discharge port that opens toward the outside in the radial direction, the second discharge port being provided closer to the stator than the first discharge port, and the second flow path having a curved portion at least partially having a curved shape.

Description

Technical Field

[0001] The present invention relates to a rotating electrical machine. Background Art

[0002] In order to improve the cooling performance of rotating electrical machines, the following structure has been developed: by effectively utilizing centrifugal force, cooling oil is sprayed from the rotor in a rotary motion, and the magnets and coils are oil-cooled through a system. However, in such an oil cooling method, mechanical losses unique to oil cooling are generated due to the movement and agitation of the cooling oil, so it is required to reduce mechanical losses in the same way as improving the cooling efficiency. In particular, in an oil cooling structure having a flow path formed long in the radial direction, the refrigerant is excessively accelerated by the large centrifugal force when the rotor rotates at high speed, resulting in a problem of increased energy loss. For example, Patent Document 1 discloses a motor in which a portion of the flow path of the end plate is opened in the axial direction, guiding the cooling oil axially outward, thereby preventing the cooling oil from intruding into the gap and reducing losses.

[0003] Prior art literature

[0004] Patent Literature

[0005] Patent Document 1: International Publication No. 2018 / 030218 Summary of the Invention

[0006] Problems to be solved by the invention

[0007] While the technology of Patent Document 1 prevents cooling oil from intruding into the gap during forward rotation of the rotor, the opposite effect occurs during reverse rotation. Therefore, even if mechanical losses during forward rotation are reduced, mechanical losses during reverse rotation increase. In view of this, an object of the present invention is to provide a rotating electrical machine that achieves both reduced mechanical losses during high-speed rotation and suppressed increases in mechanical losses during low-speed reverse rotation, while also achieving enhanced cooling.

[0008] Solutions to Problems

[0009] The rotating electrical machine comprises: a rotor; and a stator, which is arranged radially outside the above-mentioned rotor, wherein the above-mentioned rotor has: a first flow path, which extends radially and has a first discharge port opening toward the above-mentioned radial outside; and a second flow path, which extends radially and has a second discharge port opening toward the above-mentioned radial outside, the above-mentioned second discharge port is arranged at a position closer to the above-mentioned stator than the above-mentioned first discharge port, and the above-mentioned second flow path has a curved portion, at least a portion of which is a curved portion.

[0010] Effects of the Invention

[0011] According to the present invention, it is possible to provide a rotating electric machine that takes into account both the reduction of mechanical losses during high-speed rotation and the suppression of an increase in mechanical losses during low-speed reverse rotation, and achieves high cooling performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 is an electric drive system mounted on a vehicle.

[0013] Figure 2 is an explanatory diagram of a rotating electric machine in an electric drive system according to an embodiment of the present invention.

[0014] Figure 3 is Figure 2 an explanatory diagram of the structure of the rotor of the rotating electric machine

[0015] Figure 4 is an explanatory diagram of an end plate forming first and second flow paths according to an embodiment of the present invention.

[0016] Figure 5 is a modification example. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0017] Hereinafter, embodiments of the present invention will be described with reference to the drawings. The following description and drawings are illustrative of the present invention, and for the sake of clarity of explanation, appropriate omissions and simplifications have been made. The present invention can also be implemented in various other ways. Unless otherwise specified, each component can be either single or multiple.

[0018] For ease of understanding of the invention, the positions, sizes, shapes, ranges, etc. of the respective components shown in the drawings sometimes do not represent the actual positions, sizes, shapes, ranges, etc. Therefore, the present invention is not necessarily limited to the positions, sizes, shapes, ranges, etc. disclosed in the drawings.

[0019] (An embodiment and overall structure of the present invention)

[0020] ( Figure 1 )

[0021] The vehicle 10 operates the tire 11 by driving the electric drive system 12. The motor included in the electric drive system 12 promotes heat dissipation by allowing cooling oil to flow inside. The cooling oil is cooled by an oil cooler 13 serving as a heat exchanger and circulates between the electric drive system 12 and the oil cooler 13 through a cooling system 12a. The oil cooler 13 is connected not only to the cooling system 12a but also to a cooling system (water cooling) 13a of the vehicle 10. The heat of the cooling water flowing in the cooling system 13a is released to the outside of the vehicle from a cooler 14.

[0022] ( Figure 2 )

[0023] The electric drive system 12 includes a motor 1 which has a rotor 2 and a stator 9 disposed radially outside the rotor 2. The motor 1 is connected via a shaft 3 to a speed reducer 15 or the like that reduces and outputs the rotational speed of power through gears or the like.

[0024] The electric drive system 12 introduces a refrigerant that is cooled by an oil cooler 13 and pressurized and conveyed by an oil pump 17 into the motor 1. This refrigerant flows through the refrigerant flow path inside the rotor 2 via the hollow portion of the shaft 3 from the oil cooler 13. Thereby, the refrigerant cools the rotor 2 and the permanent magnet 4.

[0025] The refrigerant passing through the refrigerant flow path of the shaft 3 and the rotor 2 is discharged from the refrigerant discharge port formed on the side surface of the rotor 2 toward the coil 9a of the stator 9, thereby also cooling the coil 9a. Details of the discharge port will be described later. The discharged refrigerant flows downward in the vertical direction of the drawing due to gravity in the internal space of the motor 1 and flows into the oil pan 16. The refrigerant is pressurized and conveyed from the oil pan 16 to the oil pump 17 and is conveyed from the oil pump 17 to the oil cooler 13.

[0026] In addition, the oil pump 17 can be an electric oil pump or a mechanical oil pump. Also, the refrigerant can pass through other cooling paths such as the cooling path of the stator 9 before flowing into the flow path inside the rotor 2 from the oil cooler 13. Regarding the oil pan 16, the lower part of the rotor 2 itself can be used as the oil pan. Also, the oil cooler 13 can be either air-cooled or water-cooled. In the case of water-cooling, the cooling oil passing through the motor 1 is cooled by the cooling water of the vehicle cooling system.

[0027] ( Figure 3 )

[0028] The rotor 2 is formed by laminating electromagnetic steel sheets (thin plates) to form a rotor core. The rotor 2 has a shaft 3 and a magnet 4, and the shaft 3 is rotatably held by bearings. In addition, the rotor 2 has: a first flow path 6 that extends in the radial direction and has a first discharge port 6a that opens toward the radial outside; and a second flow path 7 that extends in the radial direction and has a second discharge port 7a that opens toward the radial outside. The second discharge port 7a is provided at a position closer to the stator 9 than the first discharge port 6a.

[0029] ( Figure 4 )

[0030] Figure 4 Figure (a) is an explanatory diagram of one surface of an end plate 5 provided at the axial end of the rotor 2 shown in Figure 3 , and figure (b) is regarding Figure 4 Figure (b) is regarding Figure 4Explanatory drawing of the surface on the opposite side of the end plate 5 in (a). In addition, the first flow path 6 and the second flow path 7 are respectively formed in a non-overlapping manner in the axial direction. The second flow path 7 has a curved portion 7b with at least a part being curved. On the other hand, the first flow path 6 is linear. When the rotor 2 rotates at high speed, the flow rate of the refrigerant flowing in the second flow path 7 increases. On the other hand, when the rotor 2 rotates at low speed, the flow rate of the refrigerant flowing in the first flow path 6 increases.

[0031] In a structure with such a change in the flow rate ratio, by setting the second flow path 7 as a curved structure, it is possible to prevent excessive acceleration of the cooling oil when the rotor 2 rotates at high speed and reduce the collision between the cooling oil and the refrigerant flow path. In addition, since the first flow path 6 is linear, it is possible to suppress an increase in loss during reverse rotation of the rotor 2. In addition, the first flow path 6 may also be a structure in which at least a part has a curvature smaller than that of the curved portion 7b. Thus, an increase in loss during reverse rotation can also be suppressed.

[0032] In the rotor 2, the radius of curvature of the curved portion 7b increases as it approaches the radially outer side. Thus, when the rotor 2 rotates at high speed, it is possible to reduce the loss of the kinetic energy of the refrigerant.

[0033] The first flow path 6 and the second flow path 7 are formed by the end plate 5 disposed on the axial end surface of the rotor 2. The end plate 5 is fixed to the rotor 2 via bolt holes 8 by bolts or the like. Thus, the first flow path 6 and the second flow path 7 can be manufactured without changing the shape of the rotor core, so it is easy to manufacture.

[0034] The opening surface of the second discharge port 7a is smaller than the opening surface of the first discharge port 6a. Thus, it is possible to prevent the acceleration of the cooling oil flowing inside the second flow path 7 with a larger flow rate during high-speed rotation of the rotor 2, slow down the refrigerant speed, and reduce the loss through the refrigerant with the reduced speed. In addition, an increase in loss during low-speed reverse rotation of the rotor 2 can also be suppressed.

[0035] The closer the curved portion 7b is to the second discharge port 7a side, the more it is inclined in the direction opposite to the main rotation direction R of the rotating electric machine 1. By adopting such a structure, it is possible to reduce the force exerted on the flow path wall by the refrigerant during high-speed rotation of the rotor 2 and reduce the loss.

[0036] For example, when viewed from the axial direction of the rotor 2, the curved portion 7b is an involute curve shape. Since the curved portion 7b of the second flow path 7 with a larger flow rate during high-speed rotation of the rotor 2 is an involute curve shape, when the cooling path is arranged along this trajectory, the cooling oil will not collide with the cooling path wall, so it will not be subjected to the force generated by the rotation of the rotor 2 and will not be accelerated, thus effectively reducing the loss.

[0037] (Modification example)

[0038] ( Figure 5)

[0039] The second flow path 7 includes an outlet flow path 7c formed at one axial end of the rotor 2, having a curved portion 7b and connected to the second outlet port 7a; an inlet flow path 7d formed at the other axial end of the rotor 2; and an axial flow path 7e connecting the outlet flow path 7c and the inlet flow path 7d. The provision of the axial flow path 7e allows for more efficient cooling of the magnets 4 inserted into the rotor 2.

[0040] The structure of the present invention described above can improve the power consumption of vehicle 10 by reducing the loss caused by the circulation of cooling oil during the high-speed rotation of rotor 2. Furthermore, the speed at which the refrigerant impinges on coil 9a can be reduced, thereby reducing refrigerant foaming. Furthermore, the present invention is applicable not only to automotive drive systems but also to drive systems other than those used in vehicles.

[0041] According to one embodiment of the present invention described above, the following effects are achieved.

[0042] (1) A motor 1 comprising: a rotor 2; and a stator 9 arranged radially outward of the rotor 2, wherein the rotor 2 comprises: a first flow path 6 extending radially and having a first discharge port 6a opening radially outward; and a second flow path 7 extending radially and having a second discharge port 7a opening radially outward. The second discharge port 7a is provided at a position closer to the stator 9 than the first discharge port 6a. The second flow path 7 comprises a curved portion 7b at least part of which is curved. Thus, a motor 1 can be provided which takes into account both the reduction of mechanical loss during high-speed rotation and the suppression of increased mechanical loss during low-speed reverse rotation, and achieves high cooling.

[0043] (2) The first flow path 6 is in a straight line shape. This can suppress an increase in loss when the rotor 2 rotates in the reverse direction at a low speed.

[0044] (3) At least a portion of the first flow path 6 has a curvature smaller than that of the curved portion 7b. This can suppress an increase in loss during low-speed reverse rotation of the rotor 2.

[0045] (4) The curvature radius of the curved portion 7b increases radially outward. This further reduces the kinetic energy loss of the refrigerant when the rotor 2 rotates at high speed.

[0046] (5) The curved portion 7b has an involute curve shape when viewed from the axial direction of the rotor 2. This can further reduce the kinetic energy loss of the refrigerant when the rotor 2 rotates at a high speed.

[0047] (6) The first flow path 6 and the second flow path 7 are formed by the end plate 5 disposed on the axial end surface of the rotor 2. This facilitates the manufacture of the flow paths 6 and 7.

[0048] (7) The second flow path 7 includes: a discharge-side flow path 7c formed at one axial end of the rotor 2, having a curved portion 7b, and connected to the second discharge port 7a; an inflow-side flow path 7d formed at the other axial end of the rotor 2; and an axial flow path 7e connecting the discharge-side flow path 7c and the inflow-side flow path 7d. Thereby, the cooling performance of the magnet of the rotor 22 can be improved.

[0049] (8) The opening area of the second discharge port 7a is smaller than that of the first discharge port 6a. Thereby, an increase in loss during low-speed rotation of the rotor 2 can be suppressed.

[0050] (9) The closer the curved portion 7b is to the second discharge port 7a side, the more it inclines in the direction opposite to the main rotation direction R of the rotating electric machine 1. Thereby, the loss during high-speed rotation of the rotor 2 can be reduced.

[0051] In addition, the present invention is not limited to the above-described embodiments, and various modifications and other structures can be combined within the scope not departing from its gist. Further, the present invention is not limited to including all the structures described in the above embodiments, and also includes a structure in which a part of the structure is deleted.

[0052] Reference Signs

[0053] 1 - motor, 2 - rotor, 3 - shaft, 4 - magnet, 5 - end plate, 6 - first flow path, 6a - first discharge port, 7 - second flow path, 7a - second discharge port, 7b - curved portion, 7c - discharge-side flow path, 7d - inflow-side flow path, 7e - axial flow path, 8 - bolt hole, 9 - stator, 9a - coil, 10 - vehicle, 11 - tire, 12 - electric drive system, 12a - cooling system of the electric drive system, 13 - oil cooler, 13a - cooling system of the vehicle, 14 - refrigerator, 15 - reducer, 16 - oil pan, 17 - oil pump.

Claims

1. A rotating electric machine includes: a rotor; and a stator disposed radially outside the rotor. The rotating electric machine is characterized in that the rotor has: a first flow path extending in the radial direction and having a first discharge port opening toward the radial outside; and a second flow path extending in the radial direction and having a second discharge port opening toward the radial outside, the second discharge port is provided at a position closer to the stator than the first discharge port, at least a part of the second flow path has a curved portion having a curved shape.

2. The rotating electric machine according to claim 1, characterized in that the first flow path has a linear shape.

3. The rotating electric machine according to claim 1, characterized in that at least a part of the first flow path has a curvature smaller than that of the curved portion.

4. The rotating electric machine according to claim 1, characterized in that the radius of curvature of the curved portion increases toward the radial outside.

5. The rotating electric machine according to claim 4, characterized in that when viewed from the axial direction of the rotor, the curved portion has an involute curve shape.

6. The rotating electric machine according to claim 1, characterized in that the first flow path and the second flow path are formed by an end plate disposed on the axial end face of the rotor.

7. The rotating electric machine according to claim 6, characterized in that the second flow path includes: a discharge-side flow path formed at one axial end of the rotor, having the curved portion, and connected to the second discharge port; an inflow-side flow path formed at the other axial end of the rotor; and an axial flow path connecting the discharge-side flow path and the inflow-side flow path.

8. The rotating electric machine according to claim 1, characterized in that the opening area of the second discharge port is smaller than that of the first discharge port.

9. The rotating electric machine according to claim 1, characterized in that the curve of the curved portion inclines in a direction opposite to the main rotation direction of the rotating electric machine as it approaches the second discharge port.

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