Oil-cooled permanent magnet motor

Abstract

The invention relates to an oil-cooled permanent magnet motor which comprises a shell, a rotor and a stator, an isolation cylinder is arranged in the shell and divides the interior of the shell into a plurality of mounting cavities, and the rotor is arranged in a second mounting cavity; the stator divides the first mounting cavity into an oil cooling cavity and an oil outlet cavity, an oil duct hole is formed in the stator, and the oil cooling cavity is communicated with the oil outlet cavity through the oil duct hole; the stator and the shell are matched to form a plurality of annular oil ducts and a plurality of axial oil ducts, and the second annular oil duct is communicated with the third annular oil duct; the first axial oil duct is communicated with the first annular oil duct and the second annular oil duct, the third annular oil duct is communicated with the second axial oil duct, and the second axial oil duct and the first axial oil duct are arranged in a staggered mode. The shell is provided with an oil inlet hole and an oil outlet hole, and the oil inlet hole is communicated with the second axial oil duct; the oil outlet hole is communicated with the oil outlet cavity; spraying holes are formed in the inner circumferential face of the shell and communicate with the first annular oil way and the oil cooling cavity. According to the structure, high-efficiency and reliable operation of the high-power-density motor is realized.

Description

Technical Field

[0001] This invention relates to the field of permanent magnet motors, specifically to an oil-cooled permanent magnet motor. Background Technology

[0002] Permanent magnet motors are widely used in various industrial applications due to their high efficiency, wide speed range, high power density, and excellent control performance. Their application is particularly important in aerospace, electric vehicles, and industrial automation. However, with continuous technological advancements and increasing application demands, the requirements for motor miniaturization, weight reduction, and high-speed, high-power characteristics are also increasing. These trends lead to a continuous increase in motor power density, and correspondingly, the heat generated during motor operation also increases. Temperature rise has gradually become a key issue limiting the further development of permanent magnet motors.

[0003] Excessive temperature rise in motors has two main negative impacts on permanent magnet motors. First, the temperature rise leads to overheating of the stator windings, which not only accelerates the aging of the insulation system and increases maintenance costs, but can also cause insulation failure and motor burnout in severe cases. Second, high temperatures can cause irreversible demagnetization of the permanent magnet material in the rotor, which will permanently reduce the motor's efficiency and lifespan. Therefore, how to effectively solve the heat dissipation problem of high-speed, high-power permanent magnet motors has become a pressing technical challenge in this field.

[0004] Currently, common cooling methods for permanent magnet motors include natural cooling, air cooling, water cooling, and oil cooling. Among these, traditional cooling methods such as natural cooling, air cooling, and water cooling are gradually becoming unable to meet the cooling requirements under high power density and high-speed operating conditions. Summary of the Invention

[0005] This invention provides an oil-cooled permanent magnet motor, the purpose of which is to solve the problems of difficult heat dissipation due to high motor power density and high friction loss due to high motor speed.

[0006] To achieve the above objectives, the present invention provides an oil-cooled permanent magnet motor, comprising a housing, a rotor, and a stator. An isolation cylinder is disposed within the housing, dividing the interior of the housing into a first mounting cavity and a second mounting cavity, wherein:

[0007] The rotor is disposed in the second mounting cavity;

[0008] The stator is disposed in the first mounting cavity, which divides the first mounting cavity into an oil cooling cavity and an oil outlet cavity. The stator is provided with an oil passage hole, which connects the oil cooling cavity and the oil outlet cavity.

[0009] The stator and the housing cooperate to form a closed first annular oil passage, a second annular oil passage, a third annular oil passage, a first axial oil passage, and a second axial oil passage between the outer circumferential surface of the stator and the inner circumferential surface of the housing. The first annular oil passage is close to the oil cooling cavity; the second annular oil passage and the third annular oil passage are connected and close to the oil outlet cavity; the first axial oil passage is connected to the first annular oil passage and the second annular oil passage; the third annular oil passage is close to the oil outlet cavity and is connected to the second axial oil passage; the second axial oil passage is offset from the first axial oil passage.

[0010] The outer casing is provided with an oil inlet and an oil outlet. The oil inlet is located on the side near the oil cooling cavity and is connected to the second axial oil passage. The oil outlet is connected to the oil outlet cavity. The inner circumferential surface of the outer casing is also provided with a spray hole, which is connected to the first annular oil passage and the oil cooling cavity.

[0011] Furthermore, a second annular groove is formed on the outer circumferential surface of the stator near the oil outlet cavity, and a first axial groove is formed on the outer circumferential surface of the stator along the axial direction. The outer circumferential surface of the stator and the inner circumferential surface of the outer shell respectively enclose the second annular groove and the first axial groove to form the second annular oil passage and the first axial oil passage.

[0012] The inner circumferential surface of the housing has a first annular groove on the side near the oil cooling cavity and a third annular groove on the side near the oil outlet cavity. The outer circumferential surface of the stator and the inner circumferential surface of the housing enclose the first annular groove and the third annular groove to form the first annular oil passage and the third annular oil passage, respectively. The inner circumferential surface of the housing has a second axial groove in the axial direction. The outer circumferential surface of the stator and the inner circumferential surface of the housing enclose the second axial groove to form the second axial oil passage.

[0013] Furthermore, the spray holes are inclined toward the winding end side of the stator.

[0014] Furthermore, the oil passage hole is a rectangular hole opened along the axial direction in the iron core teeth of the stator.

[0015] Furthermore, the insulating cylinder is a carbon fiber cylinder.

[0016] Furthermore, the stator includes a plurality of stator slots and a plurality of stator teeth, the plurality of stator teeth alternating with the plurality of stator slots, and the oil passage hole located on each of the stator teeth.

[0017] Furthermore, the housing includes a base, a front cover, and a rear cover. The two ends of the rotor are respectively mounted on the front cover and the rear cover via a bearing, and the two ends of the base are respectively fixed on the front cover and the rear cover.

[0018] Furthermore, a sealing ring is provided on the contact surface where the base connects to the front end cover and the rear end cover.

[0019] Furthermore, a sealing ring is provided on the contact surface where the isolation cylinder connects with the front end cover and the rear end cover.

[0020] Furthermore, the number of oil inlet holes and oil outlet holes is three, the number of spray holes is thirty-six, the number of second axial oil channels is three, and the number of first axial oil channels is fifteen.

[0021] Beneficial effects

[0022] Compared with existing technologies, the present invention provides an oil-cooled permanent magnet motor. This motor utilizes an insulating cylinder within the outer casing to divide the interior into two mounting cavities. The rotor is located in the second mounting cavity, while the stator is mounted in the first mounting cavity. This structural design allows the stator to achieve oil cooling through closed oil channels (including annular and axial oil channels) formed between its outer circumferential surface and the inner circumferential surface of the outer casing, increasing the contact area between the cooling oil and the heat-generating components and improving heat exchange efficiency. The cooling oil enters through the oil inlet, circulates through the oil channels, and exits through the oil outlet, effectively carrying away heat and maintaining a low-temperature environment inside the motor.

[0023] Furthermore, this design, through a sealed fit between the stator and the housing, prevents cooling oil from leaking to the outside of the motor or entering the high-speed rotor area, avoiding problems such as atomization and increased frictional losses caused by oil entering the rotor area. The spray nozzles further optimize the oil flow distribution, ensuring sufficient cooling of the winding ends and other critical hot spots, thereby improving the overall operating efficiency and lifespan of the motor. This structural design not only enhances the motor's heat dissipation capacity but also reduces frictional losses caused by high speeds, achieving efficient and reliable operation of high-power-density motors. Attached Figure Description

[0024] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below.

[0025] Figure 1 This is an overall internal sectional view of the oil-cooled permanent magnet motor disclosed in an embodiment of the present invention.

[0026] Figure 2 This is a partial cross-sectional view of the oil-cooled permanent magnet motor disclosed in an embodiment of the present invention.

[0027] Figure 3 This is a cross-sectional structural diagram of the base disclosed in an embodiment of the present invention.

[0028] Figure 4 This is a cross-sectional structural diagram of the stator disclosed in an embodiment of the present invention.

[0029] Figure 5 This is a flow path diagram of the cooling oil disclosed in the embodiments of the present invention.

[0030] Reference numerals: 1. Front end cover; 2. Base; 3. Rear end cover; 4. Rotor; 5. Stator; 6. Isolation cylinder; 7. First annular oil passage; 8. Second annular oil passage; 9. Third annular oil passage; 10. First axial oil passage; 11. Second axial oil passage; 12. Oil inlet; 13. Oil outlet; 14. Spray hole; 15. Stator slot; 16. Stator tooth; 17. Sealing ring; 18. Protrusion; 101. First mounting cavity; 102. Second mounting cavity; 103. Oil cooling cavity; 104. Oil outlet cavity; 105. Oil passage hole. Detailed Implementation

[0031] like Figures 1-4 As shown, this embodiment provides an oil-cooled permanent magnet motor, which is particularly suitable for applications requiring efficient heat dissipation, such as electric vehicles and industrial automation equipment. This design optimizes the motor's thermal management through an improved oil cooling system, thereby enhancing performance and reliability.

[0032] The motor includes a housing, a rotor 4, and a stator 5. The housing includes a frame 2, a front cover 1, and a rear cover 3. The interior of the housing is divided into two main mounting cavities by an insulating cylinder 6: a first mounting cavity 101 and a second mounting cavity 102 (see...). Figure 2 The rotor 4 is installed in the second mounting cavity 102, while the stator 5 is located in the first mounting cavity 101;

[0033] The stator 5 further divides the first mounting cavity 101 into an oil cooling cavity 103 and an oil outlet cavity 104. The stator 5 has multiple oil passage holes 105 that connect the oil cooling cavity 103 and the oil outlet cavity 104. The outer circumferential surface of the stator 5 mates with the inner circumferential surface of the outer shell to form multiple annular and axial oil passages: the first annular oil passage 7 is located near the oil cooling cavity 103; the second annular oil passage 8 and the third annular oil passage 9 are located near the oil outlet cavity 104, and the machined second annular oil passage 8 and third annular oil passage 9 are aligned and connected; the first axial oil passage 10 connects the first annular oil passage 7 and the second annular oil passage 8, while the third annular oil passage 9 connects to the second axial oil passage 11, and the second axial oil passage 11 is offset from the first axial oil passage 10.

[0034] The outer casing is provided with an oil inlet 12 and an oil outlet 13. The oil inlet 12 is located on one side of the oil cooling cavity 103 and is connected to the second axial oil passage 11. In addition, a spray hole 14 is provided on the inner circumferential surface of the outer casing. The spray hole 14 is connected to the first annular oil passage 7 and the oil cooling cavity 103, and the cooling effect is enhanced by spraying.

[0035] like Figure 1 and Figure 5 As shown, after the housing, rotor 4, and stator 5 are assembled, the interference fit between the outer circumferential surface of the stator 5 and the inner circumferential surface of the housing forms the aforementioned oil passage. When the cooling oil enters from the oil inlet 12, it travels along the second axial oil passage 11 to the second annular oil passage 8 and the third annular oil passage 9, then enters the first axial oil passage 10 on the outer circumferential surface of the stator 5, and thus enters the first annular oil passage 7. The cooling oil then enters the front end of the stator 5 in the oil cooling chamber 103 from the spray hole 14, cooling the winding ends. The cooling oil then enters the oil outlet chamber 104 from the oil passage hole 105, and finally exits from the oil outlet hole 13, thus achieving the cooling of the motor stator 5.

[0036] Because the high-speed motor rotates at very high speeds, if cooling oil enters the rotor 4, the liquid cooling oil will atomize, increasing the rotor 4's losses and hindering the motor's heat dissipation. In this embodiment, an isolation cylinder 6 is provided to separate the stator 5 and the rotor 4 cavity, thus avoiding increased losses caused by oil churning.

[0037] like Figure 4 As shown, the oil passage design of stator 5 includes:

[0038] 1) The outer circumferential surface of the stator 5 is provided with a first axial groove in the axial direction, so that when the stator 5 is assembled in the housing, the outer circumferential surface of the stator 5 and the inner circumferential surface of the housing form the aforementioned closed first axial oil passage 10. Through the design that the first axial oil passage 10 is connected to the first annular oil passage 7 and the second annular oil passage 8 respectively, the cooling oil can flow from the second annular oil passage 8 to the first annular oil passage 7.

[0039] 2) A second annular groove is provided on the outer circumferential surface of the stator 5 near the oil outlet cavity 104. The purpose is to form a closed second annular oil passage 8 between the outer shell and the stator 5. This second annular oil passage 8 is located at the front and rear of the stator, respectively, to increase the flow path of the cooling oil.

[0040] like Figure 3 As shown, the oil passage design of the casing includes:

[0041] 1) On the side near the oil cooling cavity 103, a first annular groove is formed on the inner circumferential surface of the outer shell. This first annular groove and the outer circumferential surface of the stator 5 form a closed first annular oil passage 7, which is connected to the first axial oil passage 10 and the spray hole 14.

[0042] 2) The second axial groove on the inner circumferential surface of the housing mates with the outer circumferential surface of the stator 5 to form a closed second axial oil passage 11. The design of this second axial oil passage 11 allows cooling oil to flow in the axial direction of the motor, thereby achieving more efficient heat dissipation.

[0043] 3) On the side near the oil outlet cavity 104, a third annular groove is formed on the inner circumferential surface of the outer casing. This third annular groove and the outer circumferential surface of the stator 5 form a closed third annular oil passage 9. The third annular oil passage 9 and the second annular oil passage 8 are in the same position in the axial direction and are connected to each other, so that the cooling oil can enter the second annular oil passage 8 after entering the third annular oil passage 9.

[0044] The multiple annular grooves and axial grooves designed above together form a complex oil circuit system, which can continuously cool the stator 5 and rotor 4 during motor operation. The oil flow in each oil passage can effectively carry away the heat generated by the stator 5 and finally discharge it from the oil outlet 13, ensuring that its operating temperature is within a safe range.

[0045] The optimized flow path design in this implementation optimizes the distribution and flow of the cooling oil in the cooling oil system, ensuring effective cooling of the entire stator 5, especially the heat-sensitive winding ends. Starting from the oil inlet 12, the cooling oil forms a comprehensive flow circulation within the stator 5 through the designed axial and annular oil channels, flowing from the front end to the rear end and back to the front end. This flow path not only increases the surface area of ​​contact between the oil and the stator 5, improving heat exchange efficiency, but also provides targeted cooling to the winding ends directly through the spray holes 14, reducing the motor's operating temperature, enhancing its performance stability, and extending its service life. Furthermore, the design of the rectangular oil channel holes 105 promotes better oil penetration into the core teeth of the stator 5, ensuring comprehensive heat dissipation from the inside to the outside. Finally, the heated oil is effectively discharged through the oil outlet holes 13, maintaining the system's cooling efficiency.

[0046] like Figure 1 As shown, an annular protrusion 18 is provided on the inner circumferential surface of the outer casing. The side of the protrusion 18 forms a reference surface for mounting the end of the stator 5 there, so that the installation of the stator 5 is effectively positioned. At the same time, a spray hole 14 is provided on the protrusion 18. One end of the spray hole 14 is connected to the first annular oil channel 7, and the other end is connected to the oil cooling cavity 103. The flow direction of the spray hole 14 is inclined towards the front end of the stator 5 to achieve targeted cooling of the winding end.

[0047] In this embodiment, the isolation cylinder 6 is made of carbon fiber, which has excellent strength and corrosion resistance. The oil passage 105 is a rectangular hole opened in the axial direction of the iron core teeth of the stator 5 to optimize oil flow.

[0048] like Figure 4As shown, the stator 5 includes multiple stator slots 15 and multiple stator teeth 16, with the multiple stator teeth 16 alternating with the multiple stator slots 15. Oil passage holes 105 are located on each stator tooth 16, which can achieve more effective distribution of cooling oil, allowing the coolant to penetrate evenly around each stator tooth 16, thereby improving the cooling effect and preventing local overheating.

[0049] In this embodiment, the rotor 4 is mounted on the front cover 1 and the rear cover 3 at both ends via bearings, providing stable rotational support. The base 2 is fixed to the front cover 1 and the rear cover 3 at both ends, and sealing rings 17 are provided at the connection points to prevent oil leakage and ensure the system's airtightness. In addition, sealing rings 17 are also provided on the contact surfaces where the isolation cylinder 6 connects to the front cover 1 and the rear cover 3, sealing all mating joints.

[0050] The oil circuit designed in this embodiment includes three oil inlet holes 12, three oil outlet holes 13, thirty-six spray holes 14, three second axial oil passages 11, and fifteen first axial oil passages 10. Of course, the scope of protection of this invention is not limited to this. More or fewer numbers can be set as needed to ensure uniform cooling of the entire motor, reduce hot spot generation, and extend the service life of the motor.

[0051] The above description is only a preferred embodiment of the present invention. It should be noted that those skilled in the art can make several modifications and improvements without departing from the inventive concept of the present invention, and these all fall within the protection scope of the present invention.

Claims

1. An oil-cooled permanent magnet motor, comprising a housing, a rotor (4), and a stator (5), characterized in that, An isolation cylinder (6) is provided inside the outer shell, which divides the interior of the outer shell into a first mounting cavity (101) and a second mounting cavity (102), wherein: The rotor (4) is disposed in the second mounting cavity (102); The stator (5) is disposed in the first mounting cavity (101) and divides the first mounting cavity (101) into an oil cooling cavity (103) and an oil outlet cavity (104). The stator (5) is provided with an oil passage hole (105) that connects the oil cooling cavity (103) and the oil outlet cavity (104). The stator (5) and the outer shell cooperate to form a closed first annular oil passage (7), a second annular oil passage (8), a third annular oil passage (9), a first axial oil passage (10), and a second axial oil passage (11) between the outer circumferential surface of the stator (5) and the inner circumferential surface of the outer shell. The first annular oil passage (7) is close to the oil cooling cavity (103), the second annular oil passage (8) and the third annular oil passage (9) are connected and close to the oil outlet cavity (104); the first axial oil passage (10) is connected to the first annular oil passage (7) and the second annular oil passage (8), the third annular oil passage (9) is close to the oil outlet cavity (104), and the third annular oil passage (9) is connected to the second axial oil passage (11). The second axial oil passage (11) is offset from the first axial oil passage (10). The outer casing is provided with an oil inlet (12) and an oil outlet (13). The oil inlet (12) is located on the side close to the oil cooling cavity (103) and is connected to the second axial oil passage (11). The oil outlet (13) is connected to the oil outlet cavity (104). The inner circumferential surface of the outer casing is also provided with a spray hole (14), which is connected to the first annular oil passage (7) and the oil cooling cavity (103).

2. The oil-cooled permanent magnet motor as described in claim 1, characterized in that, The stator (5) has a second annular groove on its outer circumferential surface near the oil outlet cavity (104), and the stator (5) has a first axial groove on its outer circumferential surface along the axial direction. The outer circumferential surface of the stator (5) and the inner circumferential surface of the outer shell close the second annular groove and the first axial groove to form the second annular oil passage (8) and the first axial oil passage (10), respectively. The inner circumferential surface of the outer casing is provided with a first annular groove on the side near the oil cooling cavity (103) and a third annular groove on the side near the oil outlet cavity (104). The outer circumferential surface of the stator (5) and the inner circumferential surface of the outer casing enclose the first annular groove and the third annular groove to form the first annular oil passage (7) and the third annular oil passage (9). The inner circumferential surface of the outer casing is provided with a second axial groove in the axial direction. The outer circumferential surface of the stator (5) and the inner circumferential surface of the outer casing enclose the second axial groove to form the second axial oil passage (11).

3. The oil-cooled permanent magnet motor as described in claim 1, characterized in that, The spray hole (14) is inclined toward the winding end side of the stator (5).

4. The oil-cooled permanent magnet motor as described in claim 1, characterized in that, The oil passage hole (105) is a rectangular hole opened in the axial direction of the iron core teeth of the stator (5).

5. The oil-cooled permanent magnet motor as described in claim 1, characterized in that, The isolation cylinder (6) is a carbon fiber cylinder.

6. The oil-cooled permanent magnet motor as described in claim 1, characterized in that, The stator (5) includes a plurality of stator slots (15) and a plurality of stator teeth (16), the plurality of stator teeth (16) alternating with the plurality of stator slots (15), and the oil passage hole (105) is located on each of the stator teeth (16).

7. The oil-cooled permanent magnet motor as described in claim 1, characterized in that, The outer casing includes a base (2), a front cover (1) and a rear cover (3). The two ends of the rotor (4) are respectively mounted on the front cover (1) and the rear cover (3) by a bearing. The two ends of the base (2) are respectively fixed on the front cover (1) and the rear cover (3).

8. The oil-cooled permanent magnet motor as described in claim 7, characterized in that, A sealing ring (17) is provided on the contact surface where the base (2) is connected to the front end cover (1) and the rear end cover (3).

9. The oil-cooled permanent magnet motor as described in claim 7, characterized in that, A sealing ring (17) is provided on the contact surface where the isolation cylinder (6) is connected to the front end cover (1) and the rear end cover (3).

10. The oil-cooled permanent magnet motor as described in claim 1, characterized in that, The number of oil inlet holes (12) and oil outlet holes (13) is three, the number of spray holes (14) is thirty-six, the number of second axial oil passages (11) is three, and the number of first axial oil passages (10) is fifteen.

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