A cooling structure for an electric motor rotor assembly

Abstract

A cooling structure of a motor rotor assembly, comprising a rotor shaft, a rotor hub, a rotor core, the rotor hub being fixed on the rotor shaft, the outer circle of the rotor hub being interference fitted with the rotor core, a blind hole oil channel being provided on the rotor shaft along the axial direction, one end of the blind hole oil channel being located on the end face of the rotor shaft for the cooling oil to enter, the other end extending radially to form a plurality of rotor oil channels, a plurality of connecting oil channels being provided on the rotor hub along the radial direction, the number of the connecting oil channels being the same as that of the rotor oil channels, one end of each connecting oil channel being communicated with one rotor oil channel respectively, the other end being connected with an annular oil channel, both ends of the annular oil channel being connected with a cavity, a plurality of cooling oil holes being provided on the outer circle of the rotor hub, the cooling oil holes being communicated with the annular oil channel, a plurality of oil injection holes being provided on the end face of each end of the rotor hub, the oil injection holes being communicated with the cavity.

Description

Technical Field

[0001] This invention relates to the field of motor heat dissipation, and more specifically to a cooling structure for a motor rotor assembly. Background Technology

[0002] With the rapid development of the new energy vehicle industry, the drive motor, as a core component of the three-electric system of new energy vehicles, faces increasingly stringent performance requirements. Users are increasingly demanding lighter, higher-power, and higher-speed motors. However, the increase in motor power and speed inevitably leads to serious heat generation issues, and the motor's heat dissipation effect directly determines its operating performance and service life.

[0003] Currently, the main cooling methods for drive motors are water cooling or oil cooling. Water cooling often involves creating water channels inside the motor housing. With this structure, the coolant cannot directly contact the stator and stator windings, and only a small amount of heat generated by the stator can be exchanged out of the system, making it impossible for the motor to operate for extended periods.

[0004] Existing oil cooling methods mainly employ an oil spray cooling structure, with oil channels corresponding to both the rotor shaft and rotor hub. Driven by an oil pump, the cooling oil first flows into the rotor shaft oil channel, then enters the internal oil channel of the rotor hub, where it indirectly exchanges heat with the rotor core through the oil channel wall, thus cooling the rotor core. After flowing through the internal oil channel of the rotor hub, the cooling oil is directly sprayed from the oil spray holes on the rotor hub end face to the stator windings, cooling them. However, this oil cooling structure has significant shortcomings: because the rotor core and cooling oil are in indirect contact, the heat exchange efficiency is limited, resulting in poor cooling of the rotor core; simultaneously, the cooling oil is only sprayed at a fixed point at the stator end, limiting the contact area with the stator and failing to achieve uniform cooling of the stator windings and stator core. This easily leads to problems such as localized overheating and uneven temperature distribution in the stator, resulting in low overall heat dissipation efficiency and difficulty in meeting the heat dissipation requirements of high-load, high-power-density motors. Summary of the Invention

[0005] To address the aforementioned problems, this invention provides a cooling structure for an electric motor rotor assembly. It directly cools the rotor core by setting cooling oil holes and atomizes and sprays the cooling oil through micron-sized oil spray holes to uniformly dissipate heat from the stator and magnets, thereby increasing the cooling area and better reducing the temperature of the motor stator and rotor.

[0006] To achieve the above objectives, the technical solution of the present invention is as follows: a cooling structure for a motor rotor assembly, comprising a rotor shaft, a rotor hub, and a rotor core. The rotor hub is fixed on the rotor shaft, and the rotor core is interference-fitted to the outer circumference of the rotor hub. A blind-hole oil passage is provided along the axial direction of the rotor shaft. One end of the blind-hole oil passage is located at the end face of the rotor shaft for allowing cooling oil to enter, and the other end extends radially to form multiple rotor oil passages. The rotor hub is provided radially to form multiple connecting oil passages, the same number as the rotor oil passages. One end of each connecting oil passage is connected to a rotor oil passage, and the other end is connected to an annular oil passage. Both ends of the annular oil passage are connected to cavities. Multiple cooling oil holes are provided on the outer circumference of the rotor hub, and the cooling oil holes are connected to the annular oil passages. Multiple rings of oil spray holes are provided on both end faces of the rotor hub, and the oil spray holes are connected to the cavities.

[0007] Preferably, the diameter of the injection hole is 100–200 μm.

[0008] Preferably, the injection hole is an inclined hole in the outward direction, with an inclination angle of 45° to 60°.

[0009] Preferably, the number of cooling oil holes is the same as the number of connecting oil passages.

[0010] Preferably, the position of the cooling oil hole corresponds to the outlet position of the connecting oil passage.

[0011] The beneficial effects of this invention are as follows: 1. The cooling oil holes on the outer circumference of the rotor hub of the present invention are directly connected to the annular oil channel. The cooling oil can directly contact the rotor core through the cooling oil holes, replacing the traditional indirect heat exchange method, which greatly improves the heat exchange efficiency of the rotor core, quickly removes the heat generated by the rotor operation, and improves the cooling effect of the rotor from the root.

[0012] 2. The multi-ring oil injection holes provided on both ends of the rotor hub of the present invention have a micron-level aperture. After the cooling oil flows into the oil injection holes through the cavity, it will be sprayed out in an atomized state. At the same time, the oil injection holes are inclined along the outer periphery, which greatly expands the contact area between the cooling oil and the stator winding, stator core and magnets, avoids the cooling dead angle caused by traditional fixed-point spraying, and realizes uniform cooling of the stator and magnets throughout the entire area.

[0013] 3. After the cooling oil of the present invention enters the blind hole oil passage, it flows into the annular oil passage through the rotor oil passage and the connecting oil passage. One path directly cools the rotor core through the cooling oil hole, and the other path flows into the cavity through the annular oil passage and cools the stator and magnets through the oil spray hole by atomization. This forms a dual-path heat dissipation system of direct rotor cooling and stator atomization cooling, realizing synchronous and efficient cooling of the motor stator and rotor, and significantly reducing the overall operating temperature of the motor.

[0014] 4. The number and position of the cooling oil holes in this invention correspond one-to-one with the number and outlet position of the connecting oil channels, ensuring that the cooling oil can flow into the cooling oil holes after connecting to the oil channels to cool the rotor core. Attached Figure Description

[0015] Figure 1 This is a cross-sectional structural diagram of the present invention; Figure 2 This is a schematic cross-sectional view of the rotor shaft of the present invention; Figure 3 This is a schematic diagram of the first cross-sectional structure of the rotor hub of the present invention; Figure 4 This is a schematic diagram of the second cross-sectional structure of the rotor hub of the present invention; Figure 5 This is a schematic diagram of the rotor hub of the present invention. Detailed Implementation

[0016] See Figures 1 to 5 A cooling structure for an electric motor rotor assembly includes a rotor shaft 1, a rotor hub 2, and a rotor core 3. The rotor hub 2 is fixed on the rotor shaft 1, and the outer circumference of the rotor hub 2 is interference-fitted with the rotor core 3. A blind hole oil passage 11 is provided along the axial direction of the rotor shaft 1. One end of the blind hole oil passage 11 is located at the end face of the rotor shaft 1 for the entry of cooling oil, and the other end extends radially with four rotor oil passages 12. The rotor hub 2 is provided with four connecting oil passages 21 radially. One end of each connecting oil passage 21 is connected to a rotor oil passage 12, and the other end is connected to an annular oil passage 22. Both ends of the annular oil passage 22 are connected to cavities 23. A plurality of cooling oil holes 24 are provided on the outer circumference of the rotor hub 2. The number of cooling oil holes 24 is the same as the number of connecting oil passages 21. In this embodiment, there are four. The advantage of this arrangement is that it allows the cooling oil to be evenly distributed from each connecting oil passage to each cooling oil hole on the circumference of the rotor hub, achieving uniform circumferential cooling of the rotor core and improving the overall effect of direct cooling of the rotor.

[0017] The position of the cooling oil hole 24 corresponds to the outlet position of the connecting oil passage 21. This allows the cooling oil to enter the cooling oil hole directly from the connecting oil passage, reducing the stagnation, backflow and energy loss of the cooling oil in the annular oil passage, ensuring the flow speed of the cooling oil, and allowing the cooling oil to quickly reach the cooling part of the rotor core and complete the heat exchange, thereby maximizing the heat exchange efficiency of the direct cooling of the rotor.

[0018] The cooling oil hole 24 is connected to the annular oil channel 22. Four rings of oil spray holes 25 are provided on both ends of the rotor hub 2. The oil spray holes 25 are connected to the cavity 23. The diameter of the oil spray hole 25 is 100-200μm. In this embodiment, it is set to 100μm. The micron-level aperture design allows the cooling oil to be sprayed out in an atomized state when it flows through the oil spray hole, rather than the traditional fixed-point liquid spray. The atomized cooling oil can greatly increase the contact area with the stator winding, stator core and magnets, eliminate the stator cooling dead zone, effectively solve the problem of uneven stator temperature distribution and local overheating, and improve the uniformity and comprehensiveness of stator cooling. The oil injection hole 25 is an inclined hole in the outward direction with an inclination angle of 45° to 60°. This inclination angle allows the atomized cooling oil to be accurately sprayed in the outward direction of the stator, covering more areas of the stator end and surrounding area, rather than just spraying it in a single position on the stator. This further expands the range of action of the cooling oil, allowing the stator winding and iron core to achieve uniform cooling throughout the entire area, and completely solving the problem of incomplete cooling of traditional oil-cooled stators.

[0019] This invention constructs a dual-path oil cooling system combining direct rotor cooling and multi-directional stator oil injection cooling, solving the heat dissipation problem of traditional oil cooling. On one hand, by setting cooling oil holes connected to annular oil channels on the outer circumference of the rotor hub, the cooling oil can directly contact the rotor core, replacing the traditional indirect heat exchange method via the oil channel walls. This fundamentally improves the heat exchange efficiency of the rotor core and solves the problem of poor rotor cooling. Furthermore, the use of cooling oil holes instead of annular openings ensures structural stability during rotor core assembly. On the other hand, by designing a complete flow path from blind-hole oil channels, rotor oil channels, connecting oil channels, annular oil channels, cavities to oil injection holes, the cooling oil can be sprayed from the oil injection holes on both ends of the rotor hub. This breaks the limitation of traditional oil cooling, which only sprays at fixed points on the stator ends, providing a structural basis for full-area stator cooling. Simultaneously, the compact design of the connections between the oil channels, holes, and cavities ensures a smooth and unrestricted cooling oil flow path, guaranteeing efficient oil delivery and solving the problem of low overall heat dissipation efficiency in traditional oil cooling, thus meeting the heat dissipation requirements of high-power motors.

[0020] The rotor hub of this invention is formed by die casting. Its internal oil channels and cavities are made using a sand core. Before casting, a sand core with a shape matching the internal cavity is made using coated sand or resin sand. During the pouring of molten iron, this sand core is placed inside the mold cavity. After the molten iron is poured in, it solidifies around the sand core. After the molten iron cools, the internal sand is removed by vibration or other methods, and the space previously occupied by the sand core forms the required internal cavity. This structure is simple and compact, providing convenience for motor heat dissipation.

[0021] See Figure 1The red arrow in the figure indicates the flow direction of the cooling oil in this invention. Specifically, the cooling oil is first pumped into the blind hole oil passage of the rotor shaft by an oil pump, and then enters the connecting oil passage of the rotor hub after passing through the rotor oil passage. After exiting the connecting oil passage, part of the cooling oil rushes into the cooling oil hole to directly contact the rotor core for cooling and cooling. The other part passes through the annular oil passage into the cavities on both sides. Under the action of centrifugal force, it is atomized and sprayed out through the micron-level oil spray holes to uniformly spray the entire stator and rotor magnets, thereby achieving heat dissipation and cooling.

[0022] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications made to the present invention by those skilled in the art without departing from the spirit of the present invention shall fall within the protection scope of the present invention.

Claims

1. A cooling structure for a motor rotor assembly, comprising a rotor shaft (1), a rotor hub (2), and a rotor core (3), wherein the rotor hub (2) is fixed on the rotor shaft (1), and the outer circle of the rotor hub (2) is interference-fitted with the rotor core (3), characterized in that: The rotor shaft (1) is provided with a blind hole oil passage (11) along the axial direction. One end of the blind hole oil passage (11) is located on the end face of the rotor shaft (1) for cooling oil to enter. The other end extends radially with multiple rotor oil passages (12). The rotor hub (2) is provided with multiple connecting oil passages (21) in the same number as the rotor oil passages (12) along the radial direction. One end of each connecting oil passage (21) is connected to a rotor oil passage (12), and the other end is connected to an annular oil passage (22). Both ends of the annular oil passage (22) are connected to cavities (23). Multiple cooling oil holes (24) are provided on the outer circumference of the rotor hub (2). The cooling oil holes (24) are connected to the annular oil passages (22). Multiple rings of oil spray holes (25) are provided on both end faces of the rotor hub (2). The oil spray holes (25) are connected to cavities (23).

2. The cooling structure for a motor rotor assembly according to claim 1, characterized in that: The diameter of the oil injection hole (25) is 100-200 μm.

3. The cooling structure for a motor rotor assembly according to claim 1, characterized in that: The oil injection hole (25) is an inclined hole in the outward direction, with an inclination angle of 45° to 60°.

4. The cooling structure for a motor rotor assembly according to claim 1, characterized in that: The number of cooling oil holes (24) is the same as the number of connecting oil passages (21).

5. The cooling structure for a motor rotor assembly according to claim 1, characterized in that: The location of the cooling oil hole (24) corresponds to the outlet location of the connecting oil passage (21).

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