A compound cooling structure of oil cooling and winding oil immersion for a hollow shaft of a permanent magnet motor

Abstract

This invention provides a composite cooling structure for a hollow shaft and winding oil immersion in a permanent magnet motor, relating to the field of permanent magnet motor cooling technology. Firstly, the motor shaft is designed as a hollow structure to allow for the arrangement of oil circuits, enabling rapid cooling of the motor's permanent magnets. One end of the shaft serves as the oil inlet, and the other end as the oil outlet. Stator slots are opened on the stator core to house the stator windings. Oil cup devices are arranged on both sides of the stator core along the axial direction to provide overall oil immersion cooling of the winding ends. Above the oil cups on both sides, oil channels that rotate coaxially with the shaft are arranged, and these rotating oil channels are connected to the shaft via oil pipes. This invention achieves simultaneous cooling of the motor's permanent magnets and winding ends through an internal circulating oil circuit, resulting in better cooling performance compared to a single cooling method.

Description

Technical Field

[0001] This invention relates to the field of permanent magnet motor cooling technology, and in particular to a composite cooling structure for a hollow shaft of a permanent magnet motor that combines oil cooling with oil immersion in the windings. Background Technology

[0002] In recent years, permanent magnet motors have been widely used in fields with strict weight and space requirements, such as electric vehicles, ship propulsion, and aerospace, due to their high efficiency and excellent electromagnetic performance. With increasing demands for motor winding current density and overall power density, motor structures have become more compact, leading to a rapid increase in temperature rise at the motor winding ends and increased difficulty in heat dissipation. Excessive temperature rise will seriously affect the reliability of motor operation; therefore, designing an efficient cooling system is crucial for the long-term stable operation of the motor.

[0003] In existing motor cooling structures, liquid cooling media such as water and oil have a higher specific heat capacity than air, resulting in better cooling performance than air cooling. However, water cooling cannot directly cool the ends of the motor windings, failing to effectively suppress temperature rise during motor operation. Oil cooling structures use oil as the cooling medium, effectively absorbing the heat generated by the motor. Oil has excellent insulating properties, allowing direct contact with windings and magnetic materials, directly cooling the heat source, and is neither magnetic nor electrical, thus not affecting the motor's electromagnetic field characteristics.

[0004] However, existing oil-cooled structures often suffer from uneven cooling, short cooling time of the central winding, and difficulty in local heat dissipation. Therefore, designing a motor cooling system with high cooling efficiency is crucial to ensuring the long-term stable operation of the motor. Summary of the Invention

[0005] This invention proposes a composite cooling structure for the hollow shaft of a permanent magnet motor, which combines oil cooling with oil immersion in the windings. This structure aims to solve the problems that existing cooling structures cannot effectively suppress the temperature rise of the rotor core and winding ends, thus affecting the stable operation and safety performance of the motor.

[0006] This invention provides a composite cooling structure for a hollow shaft oil-cooled permanent magnet motor and an oil-immersed winding, including a motor body and a cooling structure. The motor body has end caps at both ends of its housing. Inside the housing, a stator core, a rotor core, and a shaft are arranged in sequence. The stator core has stator windings wound in its stator slots. The rotor core has permanent magnets. The shaft has a hollow structure with an internal circulating oil circuit.

[0007] The two oil cups of the cooling structure are fixed on both sides of the stator core along the axial direction. Each oil cup contains cooling oil, which directly submerges the end of the stator winding.

[0008] Rotating oil passages are provided above the two oil bowls. The rotating oil passages are connected to the circulating oil passages of the hollow rotating shaft through oil pipes. The rotating oil passages are coaxial with the hollow rotating shaft and rotate synchronously with the hollow rotating shaft.

[0009] Furthermore, an oil hole is provided on the circumference of the hollow shaft, and the oil pipe is connected to the internal circulation oil circuit of the hollow shaft through the oil hole.

[0010] Furthermore, the rotating oil passage is provided with a rotating oil passage inlet and a rotating oil passage outlet;

[0011] The oil bowl has an oil inlet and an oil outlet, with the oil inlet located at the highest radial position of the oil bowl and the oil outlet located at the lowest radial position of the oil bowl.

[0012] When the rotating oil passage rotates with the shaft until the oil outlet of the rotating oil passage is circumferentially aligned with the oil inlet of the oil bowl, cooling oil is injected into the oil bowl from the rotating oil passage; when the oil inlet of the rotating oil passage is circumferentially aligned with the oil outlet of the oil bowl, the cooling oil returns from the oil bowl to the rotating oil passage.

[0013] Furthermore, the oil cup is in close contact with the axial end face of the stator core, and the cooling oil in the oil cup directly immerses the end of the stator winding.

[0014] Furthermore, both the rotating oil passage and the oil pipe are made of aluminum alloy.

[0015] Furthermore, ball bearings are embedded between the rotating oil channel and the oil bowl.

[0016] Furthermore, a hollow metal O-ring is provided between the rotating oil passage and the oil cup as a dynamic sealing structure.

[0017] Compared with the prior art, the present invention has the following advantages:

[0018] The permanent magnet motor's hollow shaft oil-cooled and winding oil-immersed composite cooling structure of the present invention, by axially fixing the oil cup structure in the stator core, directly immerses the winding end in the cooling oil, increasing the contact area with the heat source, and can more effectively remove the heat generated by the winding, thereby significantly improving the winding cooling efficiency; at the same time, the circulating oil circuit in the shaft can be closer to the heat source, thereby more effectively removing the heat generated by the permanent magnet, further improving the rotor cooling efficiency; in addition, the present invention integrates the cooling oil circuit into the hollow shaft and the oil cups on both sides, eliminating the need to arrange complex oil passage structures on the housing, reducing processing difficulty and manufacturing cost. Attached Figure Description

[0019] The above and other objects, features, and advantages of exemplary embodiments of the present invention will become readily apparent upon reading the following detailed description with reference to the accompanying drawings. In the drawings, several embodiments of the invention are illustrated by way of example and not limitation, with the same or corresponding reference numerals denoteing the same or corresponding parts, wherein:

[0020] Figure 1 This is an axial cross-sectional view of the motor cooling structure;

[0021] Figure 2 This is a radial cross-sectional view of the motor cooling structure;

[0022] Figure 3 This is a diagram of the motor cooling structure.

[0023] Figure 4 Here is a structural diagram of the oil bowl;

[0024] Figure 5 This is a diagram of the rotating oil passage structure.

[0025] Figure 6 Assembly drawing of rotary oil passage and oil cup;

[0026] Figure 7 This is a schematic diagram of the oil cup and oil circuit structure;

[0027] Figure 8 This is a cross-sectional view of a hollow metal O-ring.

[0028] In the diagram: 1. Housing; 2. End cover; 3. Stator core; 4. Stator winding; 5. Rotor core; 6. Rotor support; 7. Shaft; 8. Permanent magnet; 9. Oil pipe; 10. Rotating oil passage; 11. Oil cup; 12. Oil hole; 13. Oil cup inlet; 14. Oil cup outlet; 15. Rotating oil passage inlet; 16. Rotating oil passage outlet; 17. Oil cup groove; 18. Ball bearing; 19. Hollow metal O-ring. Detailed Implementation

[0029] The exemplary embodiments disclosed in this application will now be described in more detail with reference to the accompanying drawings. While exemplary embodiments of this application are shown in the drawings, it should be understood that this application can be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided to enable a more thorough understanding of this application and to fully convey the scope of this application to those skilled in the art. Unless otherwise specified, the technical means used in the embodiments are conventional means well known to those skilled in the art.

[0030] like Figure 1-3As shown, this invention provides a composite cooling structure for a hollow shaft oil-cooled permanent magnet motor and an oil-immersed winding, including a motor body and a cooling structure. The motor body has end caps 2 at both ends of its housing 1. Inside the housing 1, a stator core 3, a rotor core 5, and a shaft 7 are sequentially arranged. A stator winding 4 is wound in the stator slots of the stator core 3. A permanent magnet 8 is mounted on the rotor core 5. The shaft 7 is a hollow structure with an internal circulating oil passage. Two oil cups 11 of the cooling structure are fixed to the axial sides of the stator core 3, each containing cooling oil that directly immerses the ends of the stator winding 4. Rotating oil channels 10 are respectively arranged above the two oil cups 11. These rotating oil channels 10 are connected to the circulating oil passage of the hollow shaft 7 via oil pipes 9, and are coaxially arranged with and rotate synchronously with the hollow shaft 7.

[0031] Thus, the composite cooling structure of hollow shaft oil cooling and winding oil immersion in the permanent magnet motor of the present invention, on the one hand, by fixing oil cups 11 at both ends of the stator core 3 axially and directly immersing the ends of the stator windings 4 in the cooling oil in the oil cups 11, significantly increases the contact area between the cooling medium and the winding ends, improves the heat exchange efficiency, and effectively suppresses the temperature rise of the winding ends; on the other hand, the circulating oil circuit built into the shaft 7 can transport the cooling oil to the vicinity of the rotor core 5 and the permanent magnet 8, directly carrying away the heat generated by the permanent magnet 8, and improving the heat dissipation capacity of the rotor system; the above two cooling paths share the same circulating oil circuit, realizing the simultaneous cooling of the ends of the motor stator windings 4 and the rotor permanent magnet 8. Compared with a single cooling method, the cooling is more uniform and the overall heat dissipation efficiency is higher, which is beneficial to improving the power density and operational reliability of the motor.

[0032] Optionally, the rotating shaft 7 fixes the rotor core 5 by a heat-shrinking process, and the permanent magnet 8 is fixed to the rotor core 5 by adhesive. The stator core 3 has stator slots, and the stator winding 4 is placed in the stator slots. There is an air gap between the permanent magnet 8 on the stator and the rotor.

[0033] Optionally, the hollow shaft 7 has an oil hole 12 in the circumferential direction, and the oil pipe 9 is connected to the internal circulation oil circuit of the hollow shaft 7 through the oil hole 12.

[0034] Optionally, such as Figure 5 As shown, the rotating oil passage 10 is provided with a rotating oil passage inlet 15 and a rotating oil passage outlet 16, and the rotating oil passage inlet 15 and the rotating oil passage outlet 16 are arranged alternately.

[0035] like Figure 4 As shown, the oil bowl 11 has an oil bowl inlet 13 and an oil bowl outlet 14, with the oil bowl inlet 13 located at the highest radial position of the oil bowl 11 and the oil bowl outlet 14 located at the lowest radial position of the oil bowl 11.

[0036] like Figure 7As shown, when the rotating oil passage 10 rotates with the rotating shaft 7 until the oil outlet 16 of the rotating oil passage is circumferentially aligned with the oil inlet 13 of the oil bowl, the cooling oil is injected into the oil bowl 11 from the rotating oil passage 10; when the oil inlet 15 of the rotating oil passage is circumferentially aligned with the oil outlet 14 of the oil bowl, the cooling oil returns to the rotating oil passage 10 from the oil bowl 11.

[0037] Optionally, the oil cup 11 is in close contact with the axial end face of the stator core 3, and the cooling oil in the oil cup 11 directly submerges the end of the stator winding 4.

[0038] Optionally, both the rotating oil passage 10 and the oil pipe 9 are made of aluminum alloy.

[0039] Optionally, a ball bearing 18 is embedded between the rotating oil passage 10 and the oil bowl 11, such as... Figure 6 As shown, the oil bowl 11 has an oil bowl groove 17 axially formed on its outer surface to hold the ball 18. The diameter of the groove opening of the oil bowl 17 is the same as the diameter of the ball 18 to ensure that the groove opening of the oil bowl 17 and the ball 18 are tightly installed. A layer of lubricant is applied to the outer surface of the ball 18 to reduce the friction between the ball 18 and the groove opening 17, as well as between the ball 18 and the rotating oil passage 10.

[0040] Optionally, such as Figure 8 As shown, a hollow metal O-ring 19 is provided between the rotating oil passage 10 and the oil cup 11 as a dynamic sealing structure. Thus, the rotating oil passage 10 and the oil cup 11 are sealed using the hollow metal O-ring 19. Dedicated annular sealing grooves are provided on both sides of the oil cup inlet 13 and oil cup outlet 14 of the oil cup 11, and the hollow metal O-ring 19 is installed in the sealing groove. When the hollow metal O-ring 19 is installed in the sealing groove, it is compressed, resulting in elastic deformation. Through the elastic deformation of the hollow metal O-ring 19, it tightly fits against the contact surface of the rotating oil passage 10 and the oil cup 11, thereby achieving a seal. Simultaneously, to reduce friction between the hollow metal O-ring 19 and the rotating oil passage 10, a layer of silicone oil should be applied to the outer surface of the hollow metal O-ring 19 for lubrication.

[0041] like Figure 3 As shown, the motor cooling structure is located on both sides of the motor axis, and the cooling oil circulation process is as follows:

[0042] Cooling oil, driven by an external oil pump, enters the internal circulation circuit of the rotating shaft 7 from one end. During its flow through the shaft, it directly absorbs the heat generated by the rotor core 5 and permanent magnet 8, effectively reducing rotor temperature rise. Subsequently, the cooling oil enters the oil pipe 9 through the circumferential oil holes 12 on the rotating shaft 7, and is then transported by the oil pipe 9 to the rotating oil passage 10, which rotates coaxially and synchronously with the rotating shaft 7. When the rotating oil passage 10 rotates until its outlet 16 circumferentially aligns with the oil inlet 13 of the oil bowl 11 at its highest radial position, the cooling oil is injected into the oil bowl 11 under oil pressure and centrifugal force. The cooling oil in the oil bowl 11 directly submerges the ends of the stator winding 4. Due to the direct contact between the oil and the heat source and the large contact area, the heat generated at the winding ends is quickly carried away, significantly suppressing winding temperature rise. After absorbing heat, the cooling oil flows downwards under gravity. The oil flows out through the oil bowl 14 at the lowest radial position of the oil bowl 11. When the rotating oil passage 10 rotates until its rotating oil passage inlet 15 is circumferentially aligned with the oil bowl outlet 14, the hot oil is drawn back into the rotating oil passage 10 and returns to the internal circulation oil circuit of the rotating shaft 7 through another oil pipe 9. Finally, it flows out of the motor from the other end of the rotating shaft 7, is cooled by the external radiator, and is recycled again. In the above process, the friction between the rotating oil passage 10 and the oil bowl 11 is reduced by the ball bearing 18 and a dynamic seal is achieved with the help of the metal hollow O-ring 19, which ensures the sealing performance at the rotating interface and the reliability of long-term operation. Thus, efficient cooling of the rotor permanent magnet 8 and the stator winding 4 ends is achieved simultaneously with a single oil passage. Compared with the traditional single cooling method, the cooling is more uniform and the overall heat dissipation efficiency is higher, which is conducive to improving the power density and continuous operation capability of the motor.

[0043] According to Newton's law of heat dissipation, the heat carried away by convection is:

[0044]

[0045] In the formula, Q is the heat dissipated by convection; h is the convection heat dissipation coefficient; and A is the contact area between the solid and the fluid. The temperature of the solid; The temperature of the fluid.

[0046] The composite cooling structure of this invention directly immerses the end of the stator winding 4 in the cooling oil within the oil bowl 11. The cooling oil has a convective heat transfer coefficient h that is significantly higher than that of air, and the oil in the oil bowl 11 is continuously circulated to replenish the low-temperature oil, maintaining a large temperature difference between the winding surface and the oil. According to Newton's law of heat dissipation, the convective heat dissipation of this invention is also significantly superior to air cooling or indirect water cooling. Therefore, the composite cooling structure of this invention has higher cooling efficiency from a heat transfer theory perspective.

[0047] In this invention, the oil circuits of the rotating shaft 7 and the oil cup 11 are interconnected; there is no need to arrange complex oil channels on the housing 1. The oil in the rotating shaft 7 carries away the heat of the rotor core 5 through circulation. The cooling oil in the oil cup 11 directly contacts the stator winding 4. The cooling oil carries away the heat at the end of the winding through circulation in the oil cup 11. Compared with other non-direct contact cooling methods, this method is more effective in reducing the temperature at the end of the winding and improving the heat dissipation efficiency of the motor.

[0048] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A composite cooling structure for a hollow shaft oil-cooled and winding oil-immersed permanent magnet motor, comprising a motor body and a cooling structure, wherein end caps (2) are respectively provided at both ends of the housing (1) of the motor body, and a stator core (3), a rotor core (5) and a shaft (7) are sequentially arranged inside the housing (1), wherein a stator winding (4) is wound in the stator slot of the stator core (3), and a permanent magnet (8) is provided on the rotor core (5), characterized in that, The rotating shaft (7) has a hollow structure with a built-in circulating oil circuit; The two oil cups (11) of the cooling structure are fixed on the two axial sides of the stator core (3), and each oil cup (11) contains cooling oil, which directly submerges the end of the stator winding (4). Rotating oil passages (10) are provided above the two oil bowls (11). The rotating oil passages (10) are connected to the circulating oil passages of the hollow rotating shaft (7) through oil pipes (9). The rotating oil passages (10) are coaxially arranged with the hollow rotating shaft (7) and rotate synchronously with the hollow rotating shaft (7).

2. The composite cooling structure of hollow shaft oil cooling and winding oil immersion in a permanent magnet motor according to claim 1, characterized in that, The hollow shaft (7) has an oil hole (12) in its circumferential direction, and the oil pipe (9) is connected to the internal circulation oil circuit of the hollow shaft (7) through the oil hole (12).

3. The composite cooling structure of hollow shaft oil cooling and winding oil immersion in a permanent magnet motor according to claim 1, characterized in that, The rotary oil passage (10) is provided with a rotary oil passage inlet (15) and a rotary oil passage outlet (16). The oil bowl (11) is provided with an oil bowl inlet (13) and an oil bowl outlet (14), and the oil bowl inlet (13) is located at the highest radial position of the oil bowl (11), and the oil bowl outlet (14) is located at the lowest radial position of the oil bowl (11). When the rotating oil passage (10) rotates with the rotating shaft (7) until the oil outlet (16) of the rotating oil passage is circumferentially aligned with the oil inlet (13) of the oil bowl, the cooling oil is injected into the oil bowl (11) through the rotating oil passage (10); when the oil inlet (15) of the rotating oil passage is circumferentially aligned with the oil outlet (14) of the oil bowl, the cooling oil returns to the rotating oil passage (10) through the oil bowl (11).

4. The composite cooling structure of hollow shaft oil cooling and winding oil immersion in a permanent magnet motor according to claim 1, characterized in that, The oil cup (11) is in close contact with the axial end face of the stator core (3), and the cooling oil in the oil cup (11) directly submerges the end of the stator winding (4).

5. The composite cooling structure of hollow shaft oil cooling and winding oil immersion in a permanent magnet motor according to claim 1, characterized in that, The rotating oil passage (10) and the oil pipe (9) are both made of aluminum alloy.

6. The composite cooling structure of hollow shaft oil cooling and winding oil immersion in a permanent magnet motor according to claim 1, characterized in that, A ball bearing (18) is embedded between the rotating oil channel (10) and the oil bowl (11).

7. The composite cooling structure of hollow shaft oil cooling and winding oil immersion in a permanent magnet motor according to claim 1, characterized in that, A hollow metal OO-ring (19) is provided on the contact surface between the rotating oil passage (10) and the oil bowl (11) as a dynamic sealing structure.

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