CN113700745A

CN113700745A - Magnetic suspension bearing protection device, motor, compressor and air conditioner

Info

Publication number: CN113700745A
Application number: CN202111116710.7A
Authority: CN
Inventors: 梁豪; 龚高; 张芳; 李欣; 王建辉
Original assignee: Gree Electric Appliances Inc of Zhuhai
Current assignee: Gree Electric Appliances Inc of Zhuhai
Priority date: 2021-09-23
Filing date: 2021-09-23
Publication date: 2021-11-26

Abstract

The application provides a magnetic suspension bearing protection device, a motor, a compressor and an air conditioner. The magnetic suspension bearing protection device comprises a rotor, a thrust disc, a front axial iron core, a rear axial iron core, a bearing seat, a protection bearing, a positioning ring and an axial limiting part, wherein the positioning ring is provided with external threads and an inner retaining ring, the positioning ring is in threaded fit with the bearing seat, the protection bearing sleeve is arranged in the positioning ring, the inner retaining ring is located on the axial inner side of the protection bearing, the axial limiting part is located on the axial outer side of the protection bearing, a stopping step and a rear retaining shoulder are arranged on the rotor, the stopping step and the rear retaining shoulder form a limiting groove, and the inner ring of the protection bearing is located in the limiting groove. According to the magnetic suspension bearing protection device, when the rotor is unstable in the axial direction, the collision between the thrust disc and the magnetic suspension bearing can be effectively avoided, and the operation reliability of the magnetic suspension bearing is improved.

Description

Magnetic suspension bearing protection device, motor, compressor and air conditioner

Technical Field

The application relates to the technical field of bearings, in particular to a magnetic suspension bearing protection device, a motor, a compressor and an air conditioner.

Background

The related art discloses a method for adjusting the assembly clearance of a magnetic suspension bearing, an auxiliary bearing and a rotor, wherein a compression block is used for applying load to a compressible and deformable spring lamination, and the axial position of a protective bearing in a bearing seat is adjusted, so that the projection position on the rotor is changed, but the rigidity of the spring lamination is smaller, and the impact resistance is poorer; when the rotor is axially unstably collided, the risk exists that the spring lamination fails or is greatly deformed to cause the collision of the thrust disc and the magnetic suspension bearing.

Disclosure of Invention

Therefore, the technical problem to be solved by the application is to provide a magnetic suspension bearing protection device, a motor, a compressor and an air conditioner, so that the collision between a thrust disc and a magnetic suspension bearing can be effectively avoided when the axial instability of a rotor occurs, and the operation reliability of the magnetic suspension bearing is improved.

In order to solve the problems, the application provides a magnetic suspension bearing protection device, which comprises a rotor, a thrust disc, a front axial iron core, a rear axial iron core, a bearing seat, a protection bearing, a positioning ring and an axial limiting piece, wherein the thrust disc is arranged on the rotor, the front axial iron core and the rear axial iron core are arranged at two ends of the thrust disc, the bearing seat is fixedly arranged relative to the rear axial iron core, the inner peripheral wall of the bearing seat is provided with internal threads, the positioning ring is provided with external threads and an inner retaining ring, the positioning ring is sleeved in the bearing seat and is in threaded fit with the bearing seat, the protection bearing is sleeved in the positioning ring, the inner retaining ring is arranged at the axial inner side of the protection bearing, the axial limiting piece is arranged at the axial outer side of the protection bearing, the inner retaining ring is matched with the axial limiting piece to form axial limiting on the outer ring of the protection bearing, a retaining step and a rear retaining shoulder are arranged on the rotor, and a limiting groove is formed by the retaining step and the rear retaining shoulder, the inner ring of the protection bearing is positioned in the limiting groove, the gap between the inner ring and the stopping step is d1, the gap between the inner ring and the rear stopping shoulder is d2, the gap between the thrust disc and the front axial iron core is b1, and the gap between the thrust disc and the rear axial iron core is b2, wherein b1 is greater than d2, and b2 is greater than d 1.

Preferably, a radial stator core is further sleeved outside the rotor, a radial gap between the radial stator core and the rotor is a, and a radial gap between the protective bearing and the rotor is c, where a > c.

Preferably, the protection bearing axially extends out of the positioning ring towards one end of the axial limiting member, and the extending length is l1, and l1 is more than 0.

Preferably, the internal perisporium of bearing frame still includes the radial positioning section, and the radial positioning section is located the axial inboard of internal thread, and the location lasso still includes smooth shaft part, and smooth shaft part cup joints with the radial positioning section.

Preferably, the inner peripheral wall of the bearing seat comprises a sunken groove section, a step is formed between the sunken groove section and the radial positioning section, the internal thread is positioned on the side wall of the sunken groove section, the positioning ferrule comprises a convex ring section, the external thread is positioned on the convex ring section, and the convex ring section is positioned in the sunken groove section.

Preferably, the axial limiting piece is arranged on the end face of the bearing seat and connected with the bearing seat through a bolt, and the bolt can adjust the distance between the axial limiting piece and the protection bearing.

Preferably, the axial limiting member has an external thread, and the external thread of the axial limiting member is matched with the internal thread of the bearing seat to adjust the distance between the axial limiting member and the protection bearing.

Preferably, the axial stopper is provided with a flange projecting toward the outer ring of the protection bearing.

Preferably, the axial limiting part and the positioning collar are provided with pin holes, the axial limiting part is provided with an arc connecting hole for being connected with the bearing seat, and the arc connecting hole and the positioning collar are coaxially arranged.

Preferably, a rotary clamping groove is formed in the end face, facing the axial outer side, of the positioning ferrule.

Preferably, the part of the rotor, which is positioned at the axial outer side of the protective bearing, is provided with a positioning step, and the rear retaining shoulder is axially limited on the positioning step.

Preferably, the rotor is provided with external threads, the rear retaining shoulder is provided with internal threads, and the rear retaining shoulder is in threaded fit with the rotor.

Preferably, the rotor is provided with external threads, the axial outer side of the rear retaining shoulder is provided with a locking nut, the locking nut is in threaded fit with the rotor, and the locking nut is locked on the axial outer side of the rear retaining shoulder.

Preferably, the positioning collar and the bearing seat are in fine thread fit.

Preferably, the protective bearing is a deep groove ball bearing or an angular contact ball bearing.

Preferably, the protective bearing is a ceramic ball bearing.

According to another aspect of the present application, there is provided an electric machine comprising a magnetic bearing protection device, the magnetic bearing protection device being the magnetic bearing protection device described above.

According to another aspect of the present application, there is provided a compressor comprising a magnetic bearing protection device, wherein the magnetic bearing protection device is the magnetic bearing protection device described above.

According to another aspect of the present application, there is provided an air conditioner comprising a magnetic bearing protection device, wherein the magnetic bearing protection device is the magnetic bearing protection device described above.

The utility model provides a magnetic suspension bearing protection device, including the rotor, the thrust disc, preceding axial iron core, back axial iron core, the bearing frame, the protection bearing, location lasso and axial locating part, the thrust disc is installed on the rotor, preceding axial iron core and back axial iron core are located the both ends of thrust disc, the bearing frame is fixed to be set up for back axial iron core, the internal perisporium of bearing frame is provided with the internal thread, the location lasso has external screw thread and interior fender ring, the location lasso cover is established in the bearing frame, and with bearing frame screw-thread fit, the protection bearing cover is established in the location lasso, interior fender ring is located the axial inboard of protection bearing, axial locating part is located the axial outside of protection bearing, interior fender ring and axial locating part cooperate, form axial spacing to the outer lane of protection bearing, be provided with backstop step and back fender shoulder on the rotor, backstop step and back fender shoulder form the spacing groove, the inner circle of protection bearing is located the spacing groove, the clearance between the inner ring and the stopping step is d1, the clearance between the inner ring and the rear stopping step is d2, the clearance between the thrust disc and the front axial iron core is b1, and the clearance between the thrust disc and the rear axial iron core is b2, wherein b1 is more than d2, and b2 is more than d 1. This magnetic suspension bearing protection device will protect the bearing to install in the position collar to adjust the axial mounted position of protection bearing through the spiral pair that forms between position collar and the bearing frame, can conveniently realize the regulation of protection bearing axial position, make magnetic suspension bearing protection device's commonality stronger, simplify assembly process, can utilize the axial regulation that the spiral pair formed to guarantee protection bearing's shock resistance simultaneously, can be when rotor axial unstability, effectively avoid thrust disc and magnetic suspension bearing collision, improve magnetic suspension bearing operational reliability.

Drawings

FIG. 1 is a schematic structural diagram of a magnetic bearing protection device according to an embodiment of the present application;

FIG. 2 is an enlarged schematic view of FIG. 1 at I;

FIG. 3 is a schematic structural diagram of an axial stop of a magnetic bearing protection device according to an embodiment of the present application;

fig. 4 is a schematic structural diagram of a positioning ring of a magnetic bearing protection device according to an embodiment of the present application.

The reference numerals are represented as:

1. a rotor; 2. a radial stator core; 3. a front axial core; 4. a rear axial core; 5. a bearing seat; 6. positioning a ferrule; 61. rotating the clamping groove; 62. an inner baffle ring; 7. an axial stop; 71. an arc-shaped connecting hole; 72. a pin hole; 73. a flange; 8. a pin; 9. a rear shoulder; 10. locking the nut; 11. a thrust disc; 12. protecting the bearing; 13. a stopping step; 14. and positioning the step.

Detailed Description

Referring to fig. 1 to 4 in combination, according to an embodiment of the present application, a magnetic suspension bearing protection apparatus includes a rotor 1, a thrust disc 11, a front axial core 3, a rear axial core 4, a bearing seat 5, a protection bearing 12, a positioning collar 6 and an axial limiting member 7, the thrust disc 11 is mounted on the rotor 1, the front axial core 3 and the rear axial core 4 are located at two ends of the thrust disc 11, the bearing seat 5 is fixedly disposed relative to the rear axial core 4, an inner circumferential wall of the bearing seat 5 is provided with an internal thread, the positioning collar 6 has an external thread and an inner stop ring 62, the positioning collar 6 is sleeved in the bearing seat 5 and is in threaded fit with the bearing seat 5, the protection bearing 12 is sleeved in the positioning collar 6, the inner stop ring 62 is located at an axially inner side of the protection bearing 12, the axial limiting member 7 is located at an axially outer side of the protection bearing 12, the inner stop ring 62 is in fit with the axial limiting member 7 to form an axial limiting to an outer ring of the protection bearing 12, the rotor 1 is provided with a stopping step 13 and a rear stopping shoulder 9, the stopping step 13 and the rear stopping shoulder 9 form a limiting groove, an inner ring of the protection bearing 12 is located in the limiting groove, an axial gap between the inner ring and the stopping step 13 is d1, an axial gap between the inner ring and the rear stopping shoulder 9 is d2, an axial gap between the thrust disc 11 and the front axial iron core 3 is b1, an axial gap between the thrust disc 11 and the rear axial iron core 4 is b2, wherein b1 is greater than d2, and b2 is greater than d 1.

This magnetic suspension bearing protection device will protect bearing 12 to install in position ring 6, and adjust the axial mounted position of protection bearing 12 through the spiral pair that forms between position ring 6 and the bearing frame 5, can conveniently realize the regulation of protection bearing axial position, make magnetic suspension bearing protection device's commonality stronger, simplify assembly process, can utilize the axial regulation that the spiral pair formed to guarantee protection bearing 12's shock resistance simultaneously, can be when rotor axial unstability, effectively avoid thrust disc 11 and magnetic suspension bearing collision, improve magnetic suspension bearing operational reliability.

In this embodiment, because the positioning collar 6 and the bearing seat 5 are in a thread fit relationship, the axial position of the positioning collar 6 can be adjusted by utilizing thread fit, so that different axial gaps between the stop step 13 of the protection bearing and the rotor and the rear stop shoulder 9 can be adjusted according to different magnetic suspension bearings and rotors, the thread fit structure of the positioning collar 6 and the bearing seat 5 can be suitable for setting of different types of protection bearings, the adaptability is better, and the assembly requirement is simpler.

In this embodiment, when the rotor 1 is unstable, if the rotor 1 moves forward, since the axial gap between the thrust disk 11 and the front axial core 3 is b1, the axial gap between the inner ring and the rear retaining shoulder 9 is d2, and b1 > d2, at this time, the rotor 1 drives the rear retaining shoulder 9 to move forward, and the rear retaining shoulder 9 contacts the protection bearing 12 first, so that the thrust disk 11 can be prevented from impacting the front axial core 3, and effective axial protection is formed on the front axial core 3.

Similarly, if rotor 1 moves backward, because the axial clearance between thrust disc 11 and back axial core 4 is b2, the axial clearance between inner circle and backstop step 13 is d1, b2 > d1, therefore rotor 1 can drive backstop step 13 and move backward this moment, backstop step 13 can contact protection bearing 12 earlier, consequently can block thrust disc 11 striking back axial core 4, forms effectual axial protection to back axial core 4.

In one embodiment, b1+ b2 is greater than d1+ d2, b1 is b2, and d1 is d2, so that the centering performance of the protection bearing 12 on the magnetic suspension bearing can be ensured, and the protection performance of the protection bearing 12 on the magnetic suspension bearing can be improved.

In one embodiment, the rotor 1 is further sleeved with a radial stator core 2, a radial gap between the radial stator core 2 and the rotor 1 is a, and a radial gap between the protective bearing 12 and the rotor 1 is c, where a > c.

In the embodiment, since a > c, when the rotor 1 is unstable and moves in the radial direction, the rotor 1 first contacts the inner ring of the protection bearing 12 and is stopped by the inner ring of the protection bearing 12, so that the rotor 1 does not contact the radial stator core 2, the radial stator core 2 can be effectively protected, and the rotor 1 and the radial stator core 2 are prevented from colliding to damage the radial stator core 2.

The protection bearing 12 of the embodiment can perform axial protection on the magnetic suspension bearing and radial protection on the magnetic suspension bearing, so that the radial protection and the axial protection of the magnetic suspension bearing can be integrated, the structure of a magnetic suspension protection system is simplified, accessories are reduced, and the cost is effectively reduced.

In one embodiment, one end of the protection bearing 12 facing the axial limiting member 7 axially extends out of the positioning ring 6, the extending length is l1, and l1 is greater than 0, so that the protection bearing 12 can be ensured to axially protrude out of the positioning ring 6 facing the axial limiting member 7, the axial limiting fit between the axial limiting member 7 and the protection bearing 12 can be conveniently realized, and the axial limiting between the axial limiting member 7 and the protection bearing 12 is prevented from being influenced by the structure of the positioning ring 6.

In one embodiment, the inner circumferential wall of the bearing seat 5 further includes a radial positioning section located axially inward of the internal thread, and the positioning collar 6 further includes a smooth shaft section sleeved with the radial positioning section. In this embodiment, the radial positioning section is arranged on the inner peripheral wall of the bearing seat 5, the smooth shaft section is arranged at the corresponding position of the positioning ring 6, the radial positioning and bearing effects of the protection bearing 12 can be realized by the cooperation of the radial positioning section and the smooth shaft section, the radial position accuracy of the protection bearing 12 is ensured, and the effective radial protection effect can be achieved on the magnetic suspension bearing through the protection bearing 12.

In one embodiment, the inner circumferential wall of the bearing seat 5 comprises a counter sink section, a step is formed between the counter sink section and the radial positioning section, the inner thread is located on the side wall of the counter sink section, the positioning collar 6 comprises a male ring section, the outer thread is located on the male ring section, and the male ring section is located in the counter sink section. In this embodiment, through setting up the counter sink section, can carry out segmentation design to bearing frame 5 for the radial positioning section is in different radial height with including internal screw thread threaded connection section, when not influencing the internal screw thread setting, can guarantee the machining precision of radial positioning section, conveniently carries out radial positioning through radial positioning section and 6 cooperations of position collar to protection bearing 12. In a similar way, by arranging the convex ring section and the light ring shaft section, the connection and the positioning between the bearing seat 5 are conveniently realized, and the axial displacement of the positioning ring 6 can be limited by utilizing the step formed between the sink groove section and the radial positioning section, so that the stability and the reliability of the matching structure of the bearing seat 5 and the positioning ring 6 are improved.

In one embodiment, the axial limiting member 7 is disposed on an end surface of the bearing seat 5 and is connected with the bearing seat 5 through a bolt, and the bolt can adjust the distance between the axial limiting member 7 and the protective bearing 12. In this embodiment, along with the axial position adjustment of the positioning collar 6, the circumferential position of the protection bearing 12 is also correspondingly adjusted, and in order to ensure the axial limit of the protection bearing 12, the axial position of the axial limiting member 7 also needs to be correspondingly adjusted. In the present embodiment, the axial limiting member 7 is connected to the bearing seat 5 by a bolt, when the axial limiting member 7 abuts against the protection bearing 12, the axial limiting member 7 is fixed to the protection bearing 12 by a bolt, and at the same time, the bolt is fixedly connected to the bearing seat 5, so that the axial limiting member 7 can also be fixedly connected to the bearing seat 5. In the present embodiment, the axial limiting member 7 is, for example, a bearing end cover.

In one embodiment, the axial limiting member 7 has an external thread, and the external thread of the axial limiting member 7 is matched with the internal thread of the bearing seat 5 to adjust the distance between the axial limiting member 7 and the protective bearing 12. In the process of adjusting the axial position of the positioning ring 6, the axial position-limiting piece 7 is also adjusted along with the displacement of the positioning ring 6, and the axial position of the axial position-limiting piece 7 in the bearing seat 5 can be conveniently adjusted due to the thread fit relationship between the axial position-limiting piece 7 and the bearing seat 5, so that the axial positioning of the protection bearing 12 can be realized by being matched with the positioning ring 6 all the time.

In one embodiment, the axial limiting piece 7 is provided with a flange 73 protruding towards the outer ring of the protection bearing 12, so that the part of the axial limiting piece 7 corresponding to the outer ring of the protection bearing 12 protrudes towards the outer ring of the protection bearing 12 in the axial direction, and the outer ring of the protection bearing 12 is tightly pressed against, thereby more conveniently realizing the axial positioning and pre-tightening of the protection bearing 12 and the positioning ring 6.

In one embodiment, the axial limiting member 7 and the positioning collar 6 are provided with pin holes 72, pins 8 for circumferentially limiting the positioning collar 6 are provided in the pin holes 72, the axial limiting member 7 is provided with arc-shaped connecting holes 71 for connecting with the bearing seat 5, and the arc-shaped connecting holes 71 are coaxially arranged with the positioning collar 6. In this embodiment, the arc-shaped connection hole 71 can adjust the circumferential position of the axial limiting member 7 relative to the positioning collar 6, so that the pin hole 72 on the axial limiting member 7 can be aligned with the pin hole 72 on the positioning collar 6, the situation that the positioning collar 6 and the pin hole 72 of the axial limiting member 7 cannot be aligned is effectively avoided, and the adaptability of the pin connection between the positioning collar 6 and the axial limiting member 7 is improved.

Through the pin fit between the positioning ring 6 and the axial limiting part 7, the positioning ring 6 can be circumferentially positioned, so that the positioning ring 6 is prevented from axial displacement, and the structural stability and reliability of the magnetic suspension bearing protection device are improved.

In one embodiment, the axially outer end face of the positioning collar 6 is provided with a rotational catch 61. In this embodiment, this rotation slot 61 can supply moment to operate, consequently conveniently exerts moment to the position collar 6 at the in-process of adjusting axial position, reduces the regulation degree of difficulty. The number of the rotary locking grooves 61 is, for example, two, and is arranged symmetrically along the center of the end surface of the positioning collar 6.

In one embodiment, the portion of the rotor 1 axially outside the protective bearing 12 is provided with a positioning step 14, and the rear catch 9 is axially limited on the positioning step 14. In this embodiment, the positioning step 14 is matched with the rear retaining shoulder 9, so that the axial position of the rear retaining shoulder 9 can be accurately positioned, and the axial limiting precision of the rear retaining shoulder 9 on the protection bearing is ensured.

In one embodiment, the rotor 1 is provided with an external thread, the rear shoulder 9 is provided with an internal thread, and the rear shoulder 9 is in threaded engagement with the rotor 1. In the present embodiment, the rear shoulder 9 realizes both the axial position limitation of the protection bearing 12 and the axial positioning of itself by using the thread structure.

In this embodiment, the rotor 1 axially limits the protective bearing 12 and the rear catch 9 by providing a step shaft to form a step.

In one embodiment, the rotor 1 is provided with an external thread, the axial outside of the rear stop shoulder 9 is provided with a lock nut 10, the lock nut 10 is in threaded engagement with the rotor 1, and the lock nut 10 is locked to the axial outside of the rear stop shoulder 9. In this embodiment, the axial limit precision of the rear retaining shoulder 9 for the protection bearing 12 is realized by the self-processing precision of the rear retaining shoulder 9 and the matching precision of the rotor 1, the processing precision of the lock nut 10 does not need to be considered, and only the axial position of the rear retaining shoulder 9 needs to be locked, so that the processing precision requirement is reduced, the processing cost is lower, and the axial limit precision of the protection bearing 12 is also easier to guarantee.

In one embodiment, the locating collar 6 is a fine thread fit with the bearing seat 5. In the embodiment, the thread form of the screw pair is preferably a fine-thread triangular thread made of rice, and the thread form has good self-locking performance and can effectively improve the self-locking performance between the positioning ferrule 6 and the bearing seat 5.

In one embodiment, the protective bearing 12 is a deep groove ball bearing or an angular contact ball bearing, which may be a steel ball bearing or a ceramic ball bearing.

As a preferred embodiment, the protective bearing 12 is an angular contact ceramic ball bearing.

During the assembly process of the magnetic suspension bearing protection device, the axial limiting piece 7 and the pin 8 are not assembled, the positioning ring 6 is screwed to the foremost end, the rotor 1 is sucked to the front end, the thrust disc 11 is attached to the front axial iron core 3 at the moment, the positioning ring 6 is screwed out backwards, the protection bearing 12 is attached to the rear retaining shoulder 9, the backward movement amount of the rotor 1 is guaranteed to be (b1+ b2-d1-d2)/2, and the axial gap is adjusted in place. When the rotor 1 is suspended, the thrust disc 11 is positioned between the front axial iron core 3 and the rear axial iron core 4 under the action of the axial magnetic suspension force, the protective bearing 12 is positioned between the stopping step 13 and the rear stopping shoulder 9, and then the pin 8 is driven in and the axial limiting part 7 is assembled.

According to an embodiment of the application, the motor comprises a magnetic bearing protection device, and the magnetic bearing protection device is the magnetic bearing protection device.

According to an embodiment of the present application, the compressor includes a magnetic bearing protection device, which is the magnetic bearing protection device described above.

According to an embodiment of the application, the air conditioner comprises a magnetic suspension bearing protection device, and the magnetic suspension bearing protection device is the magnetic suspension bearing protection device.

It is readily understood by a person skilled in the art that the advantageous ways described above can be freely combined, superimposed without conflict.

The present invention is not intended to be limited to the particular embodiments shown and described, but is to be accorded the widest scope consistent with the principles and novel features herein disclosed. The foregoing is only a preferred embodiment of the present application, and it should be noted that, for those skilled in the art, several modifications and variations can be made without departing from the technical principle of the present application, and these modifications and variations should also be considered as the protection scope of the present application.

Claims

1. The magnetic suspension bearing protection device is characterized by comprising a rotor (1), a thrust disc (11), a front axial iron core (3), a rear axial iron core (4), a bearing seat (5), a protection bearing (12), a positioning ring (6) and an axial limiting part (7), wherein the thrust disc (11) is installed on the rotor (1), the front axial iron core (3) and the rear axial iron core (4) are positioned at two ends of the thrust disc (11), the bearing seat (5) is fixedly arranged relative to the rear axial iron core (4), an internal thread is arranged on the inner peripheral wall of the bearing seat (5), the positioning ring (6) is provided with an external thread and an internal retaining ring (62), the positioning ring (6) is sleeved in the bearing seat (5) and is in threaded fit with the bearing seat (5), the protection bearing (12) is sleeved in the positioning ring (6), the inner retaining ring (62) is located on the axial inner side of the protection bearing (12), the axial limiting part (7) is located on the axial outer side of the protection bearing (12), the inner retaining ring (62) is matched with the axial limiting part (7) to form axial limiting on the outer ring of the protection bearing (12), the rotor (1) is provided with a stopping step (13) and a rear retaining shoulder (9), the stopping step (13) and the rear retaining shoulder (9) form a limiting groove, the inner ring of the protection bearing (12) is located in the limiting groove, the gap between the inner ring and the stopping step (13) is d1, the gap between the inner ring and the rear retaining shoulder (9) is d2, the gap between the thrust disc (11) and the front axial iron core (3) is b1, and the gap between the thrust disc (11) and the rear axial iron core (4) is 2, wherein b1 > d2, b2 > d 1.

2. The magnetic bearing protection device according to claim 1, characterized in that a radial stator core (2) is further sleeved outside the rotor (1), a radial gap between the radial stator core (2) and the rotor (1) is a, and a radial gap between the protection bearing (12) and the rotor (1) is c, wherein a > c.

3. The magnetic bearing protection device according to claim 1, characterized in that the end of the protection bearing (12) facing the axial stop (7) extends axially beyond the positioning ring (6) by a length l1, l1 > 0.

4. The magnetic bearing protection device according to claim 1, characterized in that the inner circumferential wall of the bearing seat (5) further comprises a radial positioning section located axially inside the internal thread, and the positioning collar (6) further comprises a smooth shaft section sleeved with the radial positioning section.

5. The magnetic bearing protection device according to claim 4, characterized in that the inner circumferential wall of the bearing seat (5) comprises a counter sink section, a step is formed between the counter sink section and the radial positioning section, the internal thread is located on the side wall of the counter sink section, the positioning collar (6) comprises a male ring section, the external thread is located on the male ring section, and the male ring section is located in the counter sink section.

6. Magnetic bearing protection device according to claim 1, characterized in that the axial stop (7) is arranged on the end face of the bearing block (5) and is bolted to the bearing block (5), the bolt being able to adjust the distance between the axial stop (7) and the protection bearing (12).

7. Magnetic bearing protection device according to claim 1, characterized in that the axial stop (7) has an external thread, the external thread of the axial stop (7) cooperating with the internal thread of the bearing seat (5) for adjusting the distance between the axial stop (7) and the protection bearing (12).

8. Magnetic bearing protection device according to claim 6 or 7, characterized in that the axial stop (7) is provided with a flange (73) projecting towards the outer ring of the protection bearing (12).

9. The magnetic suspension bearing protection device according to claim 6, characterized in that the axial limiting piece (7) and the positioning ring (6) are provided with pin holes (72), a pin (8) for circumferentially limiting the positioning ring (6) is arranged in the pin hole (72), the axial limiting piece (7) is provided with an arc-shaped connecting hole (71) for connecting with the bearing seat (5), and the arc-shaped connecting hole (71) is coaxially arranged with the positioning ring (6).

10. Magnetic bearing protection device according to claim 1, characterized in that the positioning ring (6) is provided with a rotary catch (61) on its end face facing axially outwards.

11. The magnetic bearing protection device according to claim 1, characterized in that the rotor (1) is provided with a positioning step (14) at the axially outer side of the protection bearing (12), and the backstop shoulder (9) is axially limited on the positioning step (14).

12. Magnetic bearing protection device according to claim 11, characterized in that the rotor (1) is provided with an external thread and the back stop shoulder (9) is provided with an internal thread, the back stop shoulder (9) being in threaded engagement with the rotor (1).

13. Magnetic bearing protection device according to claim 11, characterized in that the rotor (1) is provided with an external thread, the axially outer side of the rear stop shoulder (9) is provided with a lock nut (10), the lock nut (10) is in threaded engagement with the rotor (1), and the lock nut (10) is locked axially outer side of the rear stop shoulder (9).

14. Magnetic bearing protection device according to claim 1, characterized in that the positioning collar (6) and the bearing seat (5) are in a fine thread fit.

15. Magnetic bearing protection device according to claim 1, characterized in that the protection bearing (12) is a deep groove ball bearing or an angular contact ball bearing.

16. Magnetic bearing protection device according to claim 15, characterized in that the protection bearing (12) is a ceramic ball bearing.

17. An electric machine comprising a magnetic bearing protection device, characterized in that the magnetic bearing protection device is a magnetic bearing protection device according to any one of claims 1 to 16.

18. A compressor comprising a magnetic bearing protection device, characterized in that the magnetic bearing protection device is a magnetic bearing protection device according to any one of claims 1 to 16.

19. An air conditioner comprising a magnetic bearing protection device, wherein the magnetic bearing protection device is the magnetic bearing protection device of any one of claims 1 to 16.