Rotor assembly and motor having the same

Abstract

The present application provides a rotor assembly and a motor having the same, comprising a rotating shaft, a first bearing portion, a second bearing portion, and an oil circuit, wherein the first bearing portion and the second bearing portion are both arranged on the rotating shaft; the oil circuit is used to transfer the heat generated by the first bearing portion and / or the second bearing portion to the rotating shaft between the first bearing portion and the second bearing portion. According to the rotor assembly and the motor having the same of the present application, the heat on the bearing can be prevented from being transferred to the end of the rotating shaft.

Description

Technical Field

[0001] The present application belongs to the technical field of motors, and in particular relates to a rotor assembly and a motor having the same. Background Art

[0002] At present, when the feed servo motor for machine tools is working, the friction loss caused by the high-speed rotation of the front and rear bearings is often transferred to the encoder end and the shaft extension end in the form of heat: when the heat is transferred to the encoder, its accuracy will decrease with the increase of temperature. When the temperature rise is seriously exceeded, it may even cause irreversible damage to the encoder electrical components, directly affecting the processing accuracy of the machine tool feed servo system; and when the heat of the bearing is transferred to the motor shaft extension end, the reverse backlash of the transmission structure will increase with the increase of temperature, resulting in a decrease in processing accuracy. The continuous increase in temperature will also cause the grease of the bearing itself to evaporate, and the lubrication will be reduced and the wear will increase. The above problems will become more serious, forming a dead cycle. Therefore, when the heat on the bearing is transferred to the end of the rotating shaft, it will affect the performance of the motor.

[0003] Therefore, how to provide a rotor assembly and a motor having the same that can prevent the heat on the bearing from being transferred to the end of the rotating shaft has become a problem that those skilled in the art urgently need to solve. Summary of the invention

[0004] Therefore, the technical problem to be solved by the present application is to provide a rotor assembly and a motor having the same, which can prevent the heat on the bearing from being transferred to the end of the rotating shaft.

[0005] In order to solve the above problems, the present application provides a rotor assembly, comprising:

[0006] Rotating shaft;

[0007] A first bearing portion and a second bearing portion, wherein the first bearing portion and the second bearing portion are both arranged on the rotating shaft;

[0008] The oil circuit is arranged on the rotating shaft, and the lubricating oil can flow in the oil circuit to transfer the heat generated by the first bearing part and / or the second bearing part to the rotating shaft between the first bearing part and the second bearing part.

[0009] Furthermore, the oil circuit is a circulating oil circuit connecting the first bearing portion and the second bearing portion.

[0010] Furthermore, the oil circuit has a guide portion, and the guide portion is used to guide the lubricating oil to flow in the oil circuit.

[0011] Furthermore, the guide portion comprises a guide channel, and the guide channel extends along the axial direction of the rotating shaft; in the flow direction of the lubricating oil, the cross section of the guide channel gradually increases.

[0012] Furthermore, the guide portion also includes a guide thread, and the guide channel has a guide surface; on the longitudinal section of the rotating shaft, the guide surface is inclined relative to the extension direction of the rotating shaft so that the cross-section of the guide channel gradually increases in the flow direction of the lubricating oil; the guide thread is arranged on the guide surface.

[0013] Furthermore, the oil circuit includes a first oil outlet hole; the first oil outlet hole is arranged on the inner ring of the first bearing part, and the position of the first oil outlet hole corresponds to the position of the ball of the first bearing part.

[0014] Furthermore, the oil circuit includes an oil inlet circuit, which extends from the first bearing portion to the second bearing portion, and the lubricating oil can flow from the first bearing portion to the second bearing portion through the oil inlet circuit.

[0015] Furthermore, the oil circuit also includes an oil return circuit, which extends from the second bearing portion to the first bearing portion, and the lubricating oil can flow from the second bearing portion to the first bearing portion through the oil return circuit.

[0016] Further, when the oil circuit has a guide portion, the guide portion includes a guide channel and a guide thread, and the oil circuit includes an oil inlet, the oil inlet includes a first guide section, the first guide section forms a first guide channel, and on the longitudinal section of the shaft, the inner wall of the first guide channel forms an angle a, wherein, n is the rotational speed of the rotor assembly; r is the radius of the oil path.

[0017] Further, when the oil circuit has a guide portion, the guide portion includes a guide channel and a guide thread, the inner wall of the guide channel includes a guide surface, and the oil circuit includes an oil return channel and an oil inlet channel, the oil return channel includes a second guide section, and the second guide section forms a second guide channel; the inner wall of the second guide channel includes a second guide surface, and the second guide surface is inclined relative to the extension direction of the rotating shaft, and the inclination angle of the second guide surface relative to the extension direction of the rotating shaft is b, n is the rotational speed of the rotor assembly; m is the total mass of the lubricating oil in the oil circuit; g is the acceleration of gravity; and r is the cross-sectional radius of the oil inlet circuit.

[0018] Furthermore, the thread inclination angle of the guide thread is greater than or equal to the inclination angle of the second guide wire surface relative to the extension direction of the rotating shaft.

[0019] Furthermore, an oil level detector is provided on the first bearing portion, and the oil level detector is used to detect the amount of lubricating oil in the first bearing portion.

[0020] According to another aspect of the present application, a motor is provided, including a rotor assembly, which is the above-mentioned rotor assembly.

[0021] The rotor assembly and the motor having the same provided in the present application transfer the heat generated by the first bearing part and / or the second bearing part to the rotating shaft therebetween through the oil circuit, thereby preventing the heat on the bearing from being transferred to the end of the rotating shaft. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 is a cross-sectional view of a rotor assembly according to an embodiment of the present application;

[0023] Figure 2 This is a schematic structural diagram of a rotor assembly according to an embodiment of the present application;

[0024] Figure 3 It is a cross-sectional view of the motor according to an embodiment of the present application.

[0025] The reference numerals are as follows:

[0026] 1. Rotating shaft; 2. First bearing part; 21. First oil outlet hole; 22. Oil level monitoring hole; 23. Oil return hole; 3. Second bearing part; 31. Oil inlet hole; 32. Second oil outlet hole; 4. Oil circuit; 41. Oil inlet circuit; 411. First guide channel; 412. First guide surface; 42. Oil return circuit; 421. Second guide channel; 422. Second guide surface; 5. Guide thread; 6. Oil quantity detector. DETAILED DESCRIPTION

[0027] See also Figure 1-3 As shown, a rotor assembly includes: a rotating shaft 1, a first bearing part 2, a second bearing part 3 and an oil circuit 4, wherein the first bearing part 2 and the second bearing part 3 are both arranged on the rotating shaft 1; the oil circuit 4 is used to transfer the heat generated by the first bearing part 2 and / or the second bearing part 3 to the rotating shaft 1 between the first bearing part 2 and the second bearing part 3, and disperse the heat generated by the first bearing part 2 and / or the second bearing part 3 through the continuous flow of grease in the oil circuit 4; and can prevent the heat on the bearing from being transferred to the end of the rotating shaft 1. The first bearing part 2 is a rear bearing; the second bearing part 3 is a front bearing. When the oil circuit 4 transfers the heat generated by the first bearing part 2 to the rotating shaft 1 between the first bearing part 2 and the second bearing part 3, the problem that the heat is transferred to the encoder part under the influence of the friction loss of the rear bearing and affects the absolute accuracy of the encoder can be solved. When the oil circuit 4 transfers the heat generated by the second bearing part 3 to the rotating shaft 1 between the first bearing part 2 and the second bearing part 3, it can solve the problem that under the influence of the friction loss of the front bearing, the heat generated by the second bearing part 3 is transferred to the shaft extension part, and the transmission structure connected to the shaft extension part is heat-conducted, causing the reverse backlash to increase and affecting the transmission accuracy of the system. On the rotor assembly, the actual heat source is the first bearing part 2 and the second bearing part 3. When rotating, the friction loss and heat generated by the friction of the balls in the bearings will cause the deformation of the rotating shaft 1. At the same time, the loss increases, the invalid power increases, and the motor efficiency decreases. The present application reduces the friction loss and transfers the heat to the shaft body evenly by lubricating the bearings with lubricating oil, thereby reducing the local heat on the rotating shaft 1, making the heat more evenly distributed on the rotating shaft 1, and preventing the deformation of the rotating shaft 1.

[0028] The present application also discloses some embodiments, in which the oil circuit 4 is a circulating oil circuit 4 connecting the first bearing part 2 and the second bearing part 3. That is, after the lubricating oil is lubricated in the first bearing part 2, it enters the oil circuit 4 and then enters the second bearing part 3 to play a lubricating role, and then returns to the first bearing part 2 to circulate, so that not only can the heat generated by the first bearing part 2 and / or the second bearing part 3 be evenly transferred to the rotating shaft 1 between the two, but also the amount of lubricating oil in the first bearing part 2 and the second bearing part 3 can be guaranteed in real time, the first bearing part 2 and the second bearing part 3 are fully lubricated, and the friction loss of the first bearing part 2 and the second bearing part 3 is reduced; the problem that the first bearing part 2 and the second bearing part 3 will cause the internal grease to volatilize under long-term operation, so that the friction loss continues to increase, causing the traditional servo motor to be affected by the friction loss of the bearing, and the loss will increase due to the volatilization of the bearing grease, and the bearing life will be reduced. The problem that the heat caused by the friction loss of the first bearing part 2 and the second bearing part 3 is more serious and is transmitted to the end of the rotating shaft 1 is also prevented. It can effectively improve the working environment of the motor, effectively ensure the accuracy of the machine tool feed system and the service life of the motor bearings, and thus better ensure the motor operation reliability and the machining accuracy of the machine tool.

[0029] The present application also discloses some embodiments, in which the oil circuit 4 has a guide portion, which is used to guide the lubricating oil to flow in the oil circuit 4. When the oil circuit 4 is a circulating oil circuit 4, the guide portion can guide the lubricating oil to flow from the first bearing portion 2 to the second bearing portion 3, and then from the second bearing portion 3 to the first bearing portion 2 to form a circulating flow. The lubricating oil circuit 4 matched with the bearing is designed inside the rotating shaft 1, and the heat generated by the friction loss in the bearing is consumed by the continuous flow of grease in the oil circuit 4, the volatilization of grease in the bearing is reduced, and the service life of the bearing is better extended. At the same time, by controlling the temperature of the bearing during operation, the temperature rise of the encoder part and the shaft extension part is indirectly reduced, the encoder accuracy and transmission accuracy are guaranteed, and the accuracy of the machine tool feed system is effectively guaranteed, thereby better ensuring the processing accuracy of the machine tool.

[0030] The present application also discloses some embodiments, wherein the guide portion includes a guide channel, and the guide channel extends along the axial direction of the rotating shaft 1; in the flow direction of the lubricating oil, the cross section of the guide channel gradually increases. That is, in the flow direction of the lubricating oil, the centrifugal force of the lubricating oil in the guide channel becomes larger and larger, which will generate an attraction force to make the lubricating oil flow into the guide channel.

[0031] The present application also discloses some embodiments, wherein the guide portion further comprises a guide thread 5, and the guide channel has a guide surface; on the longitudinal section of the shaft 1, the guide surface is arranged obliquely relative to the extension direction of the shaft 1, so that the cross section of the guide channel gradually increases in the flow direction of the lubricating oil; the guide thread 5 is arranged on the guide surface. The lubricating oil can rotate and flow along the spiral structure of the thread, so as to guide the lubricating oil.

[0032] The present application also discloses some embodiments, in which the oil circuit 4 includes a first oil outlet hole 21; the first oil outlet hole 21 is arranged on the inner ring of the first bearing part 2; the position of the first oil outlet hole 21 corresponds to the position of the ball of the first bearing part 2, and when the shaft 1 rotates, the ball approaches the position close to the outer ring of the first bearing part 2 under the action of centrifugal force, so that the lubricating oil in the first bearing part 2 flows out from the first oil outlet hole 21.

[0033] The present application also discloses some embodiments, the oil circuit 4 includes an oil inlet circuit 41, the oil inlet circuit 41 extends from the first bearing part 2 to the second bearing part 3, and the lubricating oil can flow from the first bearing part 2 to the second bearing part 3 through the oil inlet circuit 41. The first oil outlet hole 21 belongs to the oil inlet circuit 41, and the oil inlet circuit 41 is arranged inside the rotating shaft 1. The oil inlet circuit 41 also includes an oil inlet hole 31, the first oil outlet hole 21 is arranged on the first bearing part 2, and is located on the inner ring of the first bearing part 2, and is used to guide the lubricating oil in the first bearing part 2 to flow out; the oil inlet hole 31 is arranged on the second bearing part 3, and is located on the inner ring of the second bearing part 3, and is used to guide the lubricating oil in the oil inlet circuit 41 to flow into the second bearing part 3, so as to complete the process of the lubricating oil flowing from the first bearing part 2 to the second bearing part 3.

[0034] The present application also discloses some embodiments, the oil circuit 4 also includes an oil return circuit 42, the oil return circuit 42 extends from the second bearing part 3 to the first bearing part 2, and the lubricating oil can flow from the second bearing part 3 to the first bearing part 2 through the oil return circuit 42. The oil return circuit 42 is arranged inside the rotating shaft 1 and is located on the outer peripheral side of the oil inlet circuit 41. The oil return circuit 42 includes a second oil outlet hole 32 and an oil return hole 23. The second oil outlet hole 32 is arranged on the second bearing part 3 and is opened on the inner ring of the second bearing part 3; the oil return hole 23 is arranged on the first bearing part 2 and is opened on the inner ring of the first bearing part 2. The oil inlet end of the oil return circuit 42 is the second oil inlet hole 31, which is used to guide the lubricating oil in the second bearing part 3 to flow out, and the oil outlet end of the oil return circuit 42 is the oil return hole 23, which is used to guide the lubricating oil in the oil return circuit 42 to flow into the first bearing part 2 to form an oil return process from the second bearing to the first bearing.

[0035] The present application also discloses some embodiments, when the oil circuit 4 has a guide portion, the guide portion includes a guide channel and a guide thread 5, and the oil circuit 4 includes an oil inlet 41, the oil inlet 41 includes a first guide section, the first guide section forms a first guide channel 411, and on the longitudinal section of the shaft 1, the inner wall of the first guide channel 411 forms an angle a, wherein, n is the rotation speed of the rotor assembly; r is the radius of the oil path 4. Regardless of the direction of rotation of the guide thread, the oil guiding effect can be achieved.

[0036] The oil inlet passage 41 includes a first oil outlet hole 21, a first radial channel, an axial channel, a second radial channel and an oil inlet hole 31 which are connected in sequence; the first radial channel, the axial channel and the second radial channel are all arranged inside the rotating shaft 1, and the first radial channel and the second radial channel are both extended along the radial direction of the rotating shaft 1, and the number of the first radial channel and the second radial channel is at least one, the first radial channel is connected to the first oil outlet hole 21 and the oil inlet end of the axial channel, the oil outlet end of the axial channel is connected to the second radial channel, and the second radial channel is connected to the oil inlet hole 31 arranged on the inner ring of the second bearing part 3. The first guide channel 411 is arranged on the axial channel to form the first guide channel 411, the first guide channel 411 is located inside the rotating shaft 1, and is a tapered channel, that is, in the flow direction of the lubricating oil, the cross-sectional area of ​​the first guide channel 411 gradually increases, that is, the first end of the first guide channel 411 with a smaller diameter is close to the first bearing part 2; the inner wall of the first guide channel 411 is a tapered surface to form a first guide surface 412, and the first guide surface 412 is provided with a guide thread 5.

[0037] When the rotor rotates, the roller of the first bearing part 2 moves to a position away from the center of the rotating shaft 1 under the action of centrifugal force to expose the first oil outlet hole 21 set on the inner ring of the first bearing part 2. The lubricating oil in the first bearing part 2 enters the first radial channel through the first oil outlet hole 21. When the lubricating oil becomes larger and larger, it enters the axial channel. Since the cross-sectional area of ​​the first guide channel 411 becomes larger and larger in the direction away from the first bearing part 2, the centrifugal force on the lubricating oil in the first guide channel 411 is also increasing, which attracts the lubricating oil in the axial channel into the first guide channel 411, and flows out from the first guide channel 411 to the second radial channel, and then enters the second bearing part 3 through the oil inlet hole 31. The number of the first oil outlet hole 21 is set to at least one, and each oil outlet hole is corresponding to a first radial channel.

[0038] The present application also discloses some embodiments, when the oil circuit 4 has a guide portion, the guide portion includes a guide channel and a guide thread 5, the inner wall of the guide channel includes a guide surface, and the oil circuit 4 includes an oil return path 42 and an oil inlet path 41, the oil return path 42 includes a second guide section, and the second guide section forms a second guide channel 421; the inner wall of the second guide channel 421 includes a second guide surface 422, and the second guide surface 422 is inclined relative to the extension direction of the rotating shaft 1, and the inclination angle of the second guide surface 422 relative to the extension direction of the rotating shaft 1 is b, n is the rotation speed of the rotor assembly; m is the total mass of the lubricating oil in the oil circuit 4; g is the acceleration of gravity; r is the cross-sectional radius of the oil inlet circuit 41. That is, b is the angle formed by the shaft extension line and the guide surface. The oil inlet circuit 41 includes a main circuit, which extends along the axial direction of the rotating shaft 1, and r is the cross-sectional radius of the main circuit; the first end of the main circuit is connected to the second oil outlet hole 32, and the second end is connected to the oil return hole 23; a second guide section is provided on the main circuit to form a second guide channel 421, and the cross-sectional area of ​​the second guide channel 421 gradually increases in the direction close to the second end of the main circuit. The second guide channel 421 is an annular channel, including an outer peripheral wall and an inner peripheral wall, the extension direction of the outer peripheral wall is consistent with the extension direction of the rotating shaft 1, and the inner peripheral wall gradually tilts in the direction close to the center of the rotating shaft 1 in the direction close to the second end of the main circuit to form a second guide surface 422, and a guide thread 5 is provided on the inner peripheral wall. Because the cross-sectional area of ​​the second guide channel 421 gradually increases in the direction close to the second end of the main path, the centrifugal force in the second guide channel 421 also gradually increases, which can attract the lubricating oil in the second bearing part 3 to flow into the second guide channel 421, and flow out along the thread rotation, and then flow back to the first bearing part 2. The number of return oil paths 42 is set to at least one; for example, when the return first guide channel 411 is full of grease / oil, the second guide channel 421 must be full of grease. When the grease / oil in the second guide channel 421 moves toward the rear bearing, the movement path formed by the second guide channel 4 will gradually become larger. At this time, the centrifugal force on the lubricating oil becomes larger, which can attract the grease / oil to continue to flow. In general, the combined force becomes larger, and the radial path of the second guide channel 422 from the front bearing direction to the rear bearing defense line gradually increases. The centrifugal force is equivalent to the integral process of the radial path, so the larger the radial path (space), the greater the combined centrifugal force generated.

[0039] The present application also discloses some embodiments, wherein the thread inclination angle of the guide thread 5 is greater than or equal to the inclination angle of the second guide wire surface relative to the extension direction of the rotating shaft 1. The number of threads of the guide thread 5 is not limited. This can better guide the oil and prevent the lubricating oil from flowing back.

[0040] The present application also discloses some embodiments, in which an oil level detector 6 is provided on the first bearing part 2, and the oil level detector 6 is used to detect the amount of lubricating oil in the first bearing part 2. The bearing is provided with a sealing cover, and the running loss of the lubricating oil is not large. At the same time, the rotor assembly structure of the present application can be supplemented with lubricating oil, and it is only necessary to disassemble the encoder assembly and inject lubricating grease through the rear bearing, that is, the first bearing part 2. The oil level detection hole 22 is provided on the outer ring of the first bearing part 2 and is located at the upper end of the first bearing part 2. Because the outer end of the first bearing part 2 is fixed, the oil level detector 6 is provided in the oil level detection hole 22 at the upper end of the first bearing part 2, and the amount of lubricating oil in the first bearing part 2 can be accurately detected. The bearing oil level can be monitored in real time, and the lubricating grease can be regularly supplemented according to the amount of oil in the first bearing part 2, thereby improving the service life of the motor bearing, thereby improving the service life of the motor, effectively ensuring the accuracy of the machine tool feed system, and thereby better ensuring the processing accuracy of the machine tool; the present application continuously conducts the heat of the bearing under high-speed rotation while ensuring sufficient lubrication of the bearing and reducing friction loss, and avoids heat transfer to the encoder part and the shaft extension part. At the same time, the oil level monitoring hole 22 on the rear bearing is equipped with an oil level sensor, which can be monitored in real time by the controller and oil can be added regularly. This reduces the friction loss of the motor bearing, improves the bearing service life and motor reliability, and further ensures the encoder accuracy and transmission accuracy of the motor. The oil level detector 6 can be an oil level sensor.

[0041] According to an embodiment of the present application, a motor is provided, including a rotor assembly, the rotor assembly being the above-mentioned rotor assembly. The motor includes a rear end cover, the oil level monitoring hole 22 on the rear bearing needs to correspond to the oil level sensor installation hole on the rear end cover, and during the installation process, the oil passage 4 holes on the bearing need to correspond one-to-one with the oil passage 4 holes on the rotating shaft 1.

[0042] After the motor of the present application rotates, the bearing balls of the first bearing part 2 move away from the rotating shaft 1 due to the centrifugal force, and the lubricating grease in the bearing is squeezed into the oil outlet channel of the rear bearing. At the same time, it is immediately driven by the heat of the friction loss of the rear bearing and enters the oil inlet channel of the main oil circuit 4. Under the action of the guide thread 5 and the inclination angle of the main oil circuit 4, the centrifugal force component is greater than the grease friction force, and the grease is pushed along the rotating shaft 1 toward the front bearing. After reaching the plane end of the main oil circuit 4, it enters the auxiliary oil circuit of the rotating shaft through pressure; the auxiliary oil circuit refers to the oil circuit between the main oil circuit 4 and the front bearing, and the grease flows in the main oil circuit 4 by pressure. The rear bearing return oil circuit enters the main oil circuit by pressure; at this time, the force pushing the grease into the main oil circuit = the pressure of the auxiliary oil circuit - the centrifugal force, and the front bearing oil circuit enters the auxiliary oil circuit by pressure, and at this time, the force pushing the grease into the auxiliary oil circuit = the pressure of the main oil circuit + the centrifugal force. Then, under the action of centrifugal force, it is divided into two flows and enters the front bearing, and under the action of the ball squeezing of the front bearing and the friction loss of the front bearing, it enters the upper and lower return oil circuits 42 respectively. Similarly, in the upper and lower oil return paths 42, under the action of the guide thread 5 and the inclination of the oil return path 42, the grease is accelerated to move back to the rear bearing, thereby realizing the operation of the entire oil path 4.

[0043] It is easy for those skilled in the art to understand that the above-mentioned advantageous methods can be freely combined and superimposed without conflict.

[0044] The above are only preferred embodiments of the present application and are not intended to limit the present application. Any modifications, equivalent replacements and improvements made within the spirit and principles of the present application shall be included in the protection scope of the present application. The above are only preferred implementations of the present application. It should be pointed out that for ordinary technicians in this technical field, several improvements and variations can be made without departing from the technical principles of the present application, and these improvements and variations should also be regarded as the protection scope of the present application.

Claims

1. A rotor assembly, characterized in that: include: A rotating shaft (1); A first bearing portion (2) and a second bearing portion (3), wherein the first bearing portion (2) and the second bearing portion (3) are both arranged on the rotating shaft (1); an oil circuit (4), the oil circuit (4) being arranged on the rotating shaft (1), and lubricating oil being able to flow in the oil circuit (4) to transfer heat generated by the first bearing portion (2) and / or the second bearing portion (3) to the rotating shaft (1) between the first bearing portion (2) and the second bearing portion (3); The oil circuit (4) has a guide portion, the guide portion is used to guide the lubricating oil to flow in the oil circuit (4), the guide portion comprises a guide channel, the guide channel extends along the axial direction of the rotating shaft (1); in the flow direction of the lubricating oil, the cross section of the guide channel gradually increases; The guide portion further comprises a guide thread (5), and the guide channel has a guide surface; on the longitudinal section of the shaft, the guide surface is arranged obliquely relative to the extension direction of the shaft (1), so that the cross section of the guide channel gradually increases in the flow direction of the lubricating oil; the guide thread (5) is arranged on the guide surface; The oil circuit (4) comprises an oil inlet circuit (41), wherein the oil inlet circuit (41) extends from the first bearing portion (2) to the second bearing portion (3), and lubricating oil can flow from the first bearing portion (2) to the second bearing portion (3) through the oil inlet circuit (41); The oil inlet passage (41) comprises a first guide section, the first guide section forms a first guide channel (411), and on the longitudinal section of the rotating shaft (1), the inner wall of the first guide channel (411) forms an angle a, wherein: n is the rotation speed of the rotor assembly; r is the radius of the oil circuit (4).

2. The rotor assembly according to claim 1, characterized in that: The oil passage (4) is a circulating oil passage (4) connecting the first bearing portion (2) and the second bearing portion (3).

3. The rotor assembly according to claim 1, characterized in that: The oil circuit (4) comprises a first oil outlet hole (21); the first oil outlet hole (21) is arranged on the inner ring of the first bearing portion (2), and the first oil outlet hole (21) is connected to the oil circuit (4); the position of the first oil outlet hole (21) corresponds to the position of the ball of the first bearing portion (2).

4. The rotor assembly according to claim 1, characterized in that: The oil circuit (4) further comprises an oil return circuit (42), wherein the oil return circuit (42) extends from the second bearing portion (3) to the first bearing portion (2), and lubricating oil can flow from the second bearing portion (3) to the first bearing portion (2) through the oil return circuit (42).

5. The rotor assembly according to any one of claims 1 to 4, characterized in that: When the oil circuit (4) has a guide portion, the guide portion includes a guide channel and a guide thread (5), the inner wall of the guide channel includes a guide surface, and the oil circuit (4) includes an oil return channel (42) and an oil inlet channel (41), the oil return channel (42) includes a second guide section, and the second guide section forms a second guide channel (421); the inner wall of the second guide channel (421) includes a second guide surface (422), and the second guide surface (422) is inclined relative to the extension direction of the rotating shaft (1), and the inclination angle of the second guide surface (422) relative to the extension direction of the rotating shaft (1) is b, n is the rotation speed of the rotor assembly; m is the total mass of the lubricating oil in the oil circuit (4); g is the acceleration due to gravity; and r is the cross-sectional radius of the oil inlet circuit (41).

6. The rotor assembly according to claim 5, characterized in that: The thread inclination angle of the guide thread (5) is greater than or equal to the inclination angle of the second guide surface relative to the extension direction of the rotating shaft (1).

7. The rotor assembly according to claim 1, characterized in that: An oil quantity detector (6) is provided on the first bearing portion (2), and the oil quantity detector (6) is used to detect the amount of lubricating oil in the first bearing portion (2).

8. An electric motor, comprising a rotor assembly, characterized in that: The rotor assembly is the rotor assembly according to any one of claims 1 to 7.

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