A magnetic bearing protection device based on coaxial magnetic coupling

Abstract

The present invention relates to a magnetic bearing protection device based on a coaxial magnetic coupling, belonging to the technical field of magnetic bearings. The device comprises a coaxial magnetic coupling and a protective sleeve. The protective sleeve is located in the gap between the protective bearing and the rotor, and is detachably fixedly connected to the rotor, with a gap provided between its outer ring and the inner ring of the protective bearing. The coaxial magnetic coupling comprises an outer magnetic cylinder, an outer cylinder magnetic block, an inner magnetic cylinder, and an inner cylinder magnetic block. The outer magnetic cylinder is a hollow shell with one end open, which is sleeved on the end of the rotor, and its open end is coaxially fixed to the inner ring of the protective bearing. The inner magnetic cylinder is coaxially arranged inside the outer magnetic cylinder, and an axial through hole is provided at the center of its end face so as to be sleeved on the rotor. The inner end face of the inner magnetic cylinder contacts the outer end face of the protective sleeve, and the outer end face of the inner magnetic cylinder is fixed to the end face of the rotor via a fastener. The inner wall of the outer magnetic cylinder and the outer wall of the inner magnetic cylinder are respectively mounted with an outer cylinder magnetic block and an inner cylinder magnetic block. The present invention avoids the generation of full-circle friction after the high-speed shaft system of the magnetic bearing falls.

Description

Technical Field

[0001] The present invention belongs to the technical field of magnetic suspension bearings, and in particular relates to a magnetic suspension bearing protection device based on a coaxial magnetic coupling. Background Art

[0002] Magnetic bearings are a sophisticated mechanical structure. They offer non-contact support, high speed, low loss, and low noise. Furthermore, their stiffness and damping can be adjusted, giving them promising applications in rotating machinery.

[0003] Since the rotation speed of magnetic bearings is generally very high, in order to ensure the reliability and safety of the system, a protective device needs to be installed. Existing protection measures usually install a set of protective bearings, also called auxiliary bearings, at both ends of the rotor of the magnetic bearing. The protective bearings are mostly rolling bearings with high reliability. The outer ring of the protective bearing is fixed to the magnetic bearing housing, and there is a certain gap between its inner ring and the rotor of the magnetic bearing. There are no other auxiliary components between the protective bearing and the rotor. It mainly plays the role of supporting the rotor to prevent direct contact and collision between the rotor and the magnetic bearing, thereby protecting the magnetic bearing system.

[0004] During the use of the magnetic bearing, if the high-speed shaft system of the magnetic bearing (including the rotor and the parts mounted thereon) falls, its rotor assembly will collide and rub against the inner ring of the protective bearing in the magnetic bearing. According to ISO14839, the trajectory response of the high-speed shaft system of the magnetic bearing after falling includes pendulum vibration, mixed friction and bouncing, and full-circumference friction. Different trajectory responses will cause the shaft system-protective bearing system to be damaged to varying degrees, among which full-circumference friction causes the greatest damage to the shaft system-protective bearing, causing damage to the rotor and protective bearing, and reducing the service life of the magnetic bearing. It can be seen that the existing technology only uses protective bearings as a protective device for magnetic bearings, and the protective effect is very limited. Therefore, a protective device is needed that can reduce or even avoid the generation of full-circumference friction after the high-speed shaft system of the magnetic bearing falls. Summary of the Invention

[0005] Technical issues to be solved:

[0006] To overcome the shortcomings of the prior art, the present invention provides a magnetic bearing protection device based on a coaxial magnetic coupling. The outer magnetic cylinder of the coaxial magnetic coupling is fixedly connected to the inner ring of the protective bearing; the inner magnetic cylinder is fixedly connected to the rotor of the magnetic bearing; the protective sleeve is fixedly mounted on the shaft neck at the end of the rotor, limiting the axial position of the inner magnetic cylinder; and the inner and outer walls of the outer and inner magnetic cylinders are respectively and one-to-one mounted with outer and inner magnetic blocks. When the magnetic bearing is operating normally, the outer and inner magnetic cylinders are located on the same axis and rotate coaxially and at the same speed, causing the inner ring of the protective bearing to have a certain rotational speed. This prevents the magnetic bearing shaft system from entering a full-circle friction state after falling, thereby protecting the magnetic bearing shaft system.

[0007] The present invention reduces or even avoids the generation of full-circumference friction after the high-speed shaft system of the magnetic suspension bearing falls, and solves the problem in the prior art that the shaft system-protection bearing is damaged due to the generation of full-circumference friction.

[0008] The technical solution of the present invention is: a magnetic bearing protection device based on a coaxial magnetic coupling, comprising a coaxial magnetic coupling and a protective sleeve 2; the protective sleeve 2 is located in the gap between a protective bearing 3 of the magnetic bearing and a rotor 1, the protective sleeve 2 is coaxially sleeved on the rotor 1 of the magnetic bearing, and is detachably fixedly connected to the rotor, with a first gap being defined between the outer ring of the protective sleeve and the inner ring of the protective bearing 3;

[0009] The coaxial magnetic coupling includes an outer magnetic tube 4, an outer tube magnetic block 5, an inner magnetic tube 6, and an inner tube magnetic block 7; the outer magnetic tube 4 is a cavity shell with one end open, which is sleeved on the end of the rotor 1, and its open end is coaxially fixedly connected to the inner ring of the protective bearing 3; the inner magnetic tube 6 is located inside the outer magnetic tube 4 and is coaxial with the outer magnetic tube 4. An axial through hole is provided at the center position of its end face and is coaxially sleeved on the rotor 1. The inner end face of the inner magnetic tube 6 contacts the outer end face of the protective sleeve 2 for axial positioning, and the outer end face of the inner magnetic tube 6 is fixed to the end face of the rotor 1 by a fastener; the inner wall of the outer magnetic tube 4 and the outer wall of the inner magnetic tube 6 are respectively installed with the outer tube magnetic block 5 and the inner tube magnetic block 7.

[0010] A further technical solution of the present invention is: the number and shape of the outer cylinder magnetic blocks 5 and the inner cylinder magnetic blocks 7 are the same, multiple outer cylinder magnetic blocks 5 are evenly distributed circumferentially and fixed to the inner wall of the outer magnetic cylinder 4, multiple inner cylinder magnetic blocks 7 are evenly distributed circumferentially and fixed to the outer wall of the inner magnetic cylinder 6, the outer cylinder magnetic blocks 5 and the inner cylinder magnetic blocks 7 correspond to each other one by one, are aligned and installed in parallel, and a second gap is provided between the corresponding outer cylinder magnetic blocks 5 and inner cylinder magnetic blocks 7.

[0011] A further technical solution of the present invention is that the inner wall of the outer magnetic cylinder 4 and the outer wall of the inner magnetic cylinder 6 are both circumferentially uniformly provided with corresponding mounting grooves, and the outer cylinder magnetic block 5 and the inner cylinder magnetic block 7 are embedded and installed in their respective mounting grooves.

[0012] A further technical solution of the present invention is that the outer magnetic cylinder 4 is a cylindrical cavity shell, and its open end is fixed to the inner ring of the protective bearing 3 by gluing.

[0013] A further technical solution of the present invention is: the inner magnetic cylinder 6 is cylindrical, and a recess is provided around the axial through hole on its outer end face; the rotor 1 of the magnetic bearing passes through the axial through hole of the inner magnetic cylinder 6, and its end face does not exceed the bottom face of the recess, and the bottom face of the recess of the inner magnetic cylinder 6 is fixedly connected to the end face of the rotor 1 by means of bolts 10 in conjunction with the shaft end retaining ring 8.

[0014] A further technical solution of the present invention is that the inner magnetic cylinder 6 and the rotor 1 are circumferentially limited by a flat key 9 .

[0015] A further technical solution of the present invention is that the protective sleeve 2 and the rotor 1 are interference fit.

[0016] A further technical solution of the present invention is that the material of the inner magnetic cylinder 6 and the outer magnetic cylinder 4 is engineering plastic.

[0017] An application of the magnetic bearing protection device based on the coaxial magnetic coupling, the magnetic bearing protection device based on the coaxial magnetic coupling is installed at both ends of the magnetic bearing, the rotor 1 end of the magnetic bearing is a stepped shaft head, including a large diameter section 11 and a small diameter section 12, and an axial threaded hole is provided at the center of the end face of the rotor 1; the protective sleeve 2 is coaxially sleeved on the large diameter section 11, and has an interference fit with the large diameter section 11, the inner end face of the protective sleeve 2 is pressed against the step of the large diameter section 11, and the outer end face extends to the small diameter section 12; the protective bearing 3 is coaxially sleeved on the protective sleeve The protective sleeve 2 has a first gap between its inner ring and the protective sleeve 2, and its outer ring is fixed to the outer shell of the magnetic levitation bearing 13; the open end of the outer magnetic cylinder 4 is coaxially fixedly connected to the inner ring of the protective bearing 3; the inner magnetic cylinder 6 is coaxially sleeved on the small diameter section 12, and the inner end face of the inner magnetic cylinder 6 contacts the outer end face of the protective sleeve 2 for axial positioning, and its outer end face is fixedly connected to the end face of the rotor 1 through the shaft end retaining ring 8 and the bolt 10, and the inner magnetic cylinder 6 and the small diameter section 12 of the rotor 1 are circumferentially limited by the flat key 9; the outer cylinder magnetic block 5 and the inner cylinder magnetic block 7 are made to correspond one to one, aligned and parallel.

[0018] The protective bearing 3 is a deep groove ball bearing or an angular contact ball bearing.

[0019] Beneficial effects

[0020] The beneficial effects of the present invention are as follows: a magnetic bearing protection device based on a coaxial magnetic coupling is installed at both ends of a magnetic bearing, wherein the outer magnetic cylinder of the coaxial magnetic coupling is fixedly connected to the inner ring of the protective bearing, the inner side of the inner magnetic cylinder is axially limited by a protective sleeve installed at the shaft neck of the rotor end, and the outer side is fixed to the end of the rotor by a shaft end retaining ring and bolts, and the inner wall of the outer magnetic cylinder and the outer wall of the inner magnetic cylinder are respectively provided with magnetic blocks, with a certain gap maintained between the corresponding magnetic blocks. When the magnetic bearing shaft system is operating normally, the inner magnetic cylinder rotates with the rotor, and the interaction between the inner cylinder magnetic blocks and the outer cylinder magnetic blocks causes the outer magnetic cylinder to drive the inner ring of the protective bearing to rotate, thereby preventing the magnetic bearing shaft system from falling onto the protective bearing and entering a full-circle friction state, thereby protecting the magnetic bearing shaft system.

[0021] The structure of the present invention maintains the suspended state of the rotor and has the advantages of less contact, less wear and less influence on the motion state of the rotor.

[0022] The protective sleeve of the present invention protects the rotor when it falls, and because the protective sleeve is detachable, it can be easily replaced, thereby improving the utilization rate of the entire protective device and correspondingly reducing the production cost of the protective device.

[0023] Through simulation, the present invention has a significant effect in suppressing the generation of full-circle friction: Figure 3 It can be seen that without using the protection device of the present invention, the rotor of the magnetic bearing enters the full-circle friction state after several bounces after falling, and the vortex speed of the rotor also tends to increase over time. Figure 3 and Figure 4 From the rotor motion trajectory, it can be seen that after the introduction of the protection device of the present invention, the rotor did not enter the full-circle friction state after falling, but remained in the bouncing state; at the same time, the rotor's bouncing height and vortex speed also decreased to a certain extent. It can be seen that at the initial speed of 9000r / min, the rotor linear velocity is about 1.959m / s. The use of the protection device of the present invention reduces the energy transferred to the vortex speed part after the rotor of the magnetic levitation bearing falls onto the protective bearing, and the vibration amplitude of the rotor is also significantly reduced; in the simulation experiment, the protection device of the present invention avoids the full-circle friction phenomenon after the rotor falls, reducing the damage to the magnetic levitation bearing system. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 This is a schematic structural diagram of a magnetic bearing protection device based on a coaxial magnetic coupling according to the present invention;

[0025] Figure 2 Schematic diagram of the present invention installed on a magnetic bearing;

[0026] Figure 3This is a simulation diagram of the falling motion of the magnetic bearing shaft system without the protection device of the present invention. Figure 3 As shown, the rotor falls at a speed of 9000 r / min and the simulation time is 0.2 s; Figure 3 (a) is the rotor drop trajectory diagram, (b) is the rotor displacement change diagram in the y direction, (c) is the linear velocity change diagram of the rotor and the inner ring of the protective bearing, and (d) is the rotor vortex velocity change diagram;

[0027] Figure 4 This is a simulation diagram of the falling motion of the magnetic bearing shaft system using the protection device of the present invention. During the simulation process, a certain initial rotation speed is applied to the inner ring of the protective bearing to simulate the effect that can be achieved by the protection device of the present invention. At this time, the speed applied to the inner ring of the protective bearing is the same as the initial linear speed of the rotor; the rotor falls at a rotation speed of 9000r / min, and the simulation time is 0.2s; Figure 4 As shown, Figure 4 (a) is the rotor drop trajectory diagram, (b) is the rotor displacement change diagram in the y direction, (c) is the linear velocity change diagram of the rotor and the inner ring of the protective bearing, and (d) is the rotor vortex velocity change diagram. Figure 4 In (c), the reason why the linear velocity of the inner ring of the protective bearing appears so chaotic may be due to the nonlinear effects of the collision force model between the rotor and the inner ring, the friction force calculation model, and the contact force model between the ball and the inner and outer rings in the simulation calculation.

[0028] Explanation of the reference numerals: 1. Rotor 2. Protective sleeve 3. Protective bearing 4. Outer magnetic cylinder 5. Outer cylinder magnetic block 6. Inner magnetic cylinder 7. Inner cylinder magnetic block 8. Shaft end retaining ring 9. Flat key 10. Bolt 11. Large diameter section 12. Small diameter section 13. Magnetic bearing DETAILED DESCRIPTION

[0029] The embodiments described below with reference to the accompanying drawings are exemplary and are intended to explain the present invention, but should not be construed as limiting the present invention.

[0030] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise" and the like to indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention.

[0031] See Figure 1 , Figure 2 The present invention provides a magnetic bearing protection device based on a coaxial magnetic coupling, comprising a coaxial magnetic coupling and a protective sleeve 2. The magnetic bearing protection device is installed at both ends of the magnetic bearing. The rotor 1 of the magnetic bearing has a stepped shaft head, with a large diameter section 11 and a small diameter section 12 at the step; the protective sleeve 2 is coaxially sleeved on the large diameter section 11, and the inner hole of the protective sleeve 2 is interference fit with the large diameter section 11. Through the interference fit, the protective sleeve can better withstand torque, axial force or the combined load of the two, and has a high load-bearing capacity; the inner end face of the protective sleeve 2 is pressed against the step formed by the large diameter section 11 and the rotor, and its outer end face extends to the small diameter section 12; the protective bearing 3 of the magnetic bearing is coaxially sleeved on the outer ring of the protective sleeve 2, and a first gap is provided between the inner ring of the protective bearing 3 and the protective sleeve 2. The outer ring of the protective bearing 3 is fixed to the outer shell of the magnetic bearing 13. The protective bearing 3 is a deep groove ball bearing or an angular contact ball bearing. The use of a deep groove ball bearing or an angular contact ball bearing can better withstand axial force.

[0032] See Figure 1 The coaxial magnetic coupling includes an outer magnetic tube 4, an outer tube magnetic block 5, an inner magnetic tube 6, and an inner tube magnetic block 7; the outer magnetic tube 4 is a cylindrical cavity shell with an open end, and its material is engineering plastic. The outer magnetic tube 4 is sleeved on the end of the rotor 1, and its open end is coaxial with the inner ring of the protective bearing 3 and is fixedly connected by gluing. The fixed connection is simple and fast; the inner magnetic tube 6 is located in the inner cavity of the outer magnetic tube 4 and is coaxial with the outer magnetic tube 4. The inner magnetic tube 6 is cylindrical and its material is engineering plastic. The inner magnetic tube 6 is provided with an axial through hole along the center axis. The inner magnetic tube 6 is coaxially sleeved on the small diameter section 12 of the rotor 1, and the inner end of the inner magnetic tube 6 The outer end surface of the inner magnetic tube 6 contacts the outer end surface of the protective sleeve 2 for axial positioning. The outer end surface of the inner magnetic tube 6 is fixed to the end surface of the rotor 1 via fasteners. Specifically, the outer end surface of the inner magnetic tube 6 is provided with a recessed portion coaxially with the axial through-hole. The axial through-hole of the inner magnetic tube 6 is fitted over the small-diameter section 12 of the rotor 1. After the protective sleeve 2 limits the inner end surface of the inner magnetic tube 6, the end surface of the rotor 1 approaches but does not exceed the bottom surface of the recessed portion of the inner magnetic tube 6. A threaded hole is provided axially at the center of the end surface of the rotor 1. Bolts 10 and axial end retaining rings 8 securely connect the bottom surface of the recessed portion of the inner magnetic tube 6 to the end surface of the rotor 1. The axial position of the inner magnetic tube 6 is determined by the protective sleeve 2 and axial end retaining rings 8. A keyway is provided circumferentially on the small-diameter section 12 of the rotor 1. A keyway matching the small-diameter section 12 is also provided in the axial through-hole of the inner magnetic tube 6. A flat key 9 is installed in the keyway to achieve circumferential positioning of the inner magnetic tube 6 and the small-diameter section 12.

[0033] The inner wall of the outer magnetic tube 4 is mounted with an outer magnetic block 5, and the outer wall of the inner magnetic tube 6 is mounted with an inner magnetic block 7. The outer magnetic blocks 5 and the inner magnetic blocks 7 are identical in number and shape. The axial inner wall of the outer magnetic tube 4 and the axial outer wall of the inner magnetic tube 6 are both circumferentially provided with corresponding mounting grooves. Multiple outer magnetic blocks 5 are fixed to the mounting grooves on the inner wall of the outer magnetic tube 4 by gluing. Similarly, multiple inner magnetic blocks 7 are fixed to the mounting grooves on the outer wall of the inner magnetic tube 6 by gluing. The outer magnetic blocks 5 and the inner magnetic blocks 7 are mounted in parallel and aligned one by one. A second gap is provided between the corresponding outer magnetic blocks 5 and the inner magnetic blocks 7. The first and second gaps in this embodiment can be set according to actual needs and are not limited thereto.

[0034] In the magnetic bearing protection device based on the coaxial magnetic coupling described in the present invention, when the magnetic bearing shaft system is operating normally, the inner magnetic cylinder 6 rotates with the rotor 1. Under the action of the inner cylinder magnetic block 7 and the outer cylinder magnetic block 5, the outer magnetic cylinder 4 and the inner magnetic cylinder 6 rotate coaxially, at the same speed, and in the same direction, thereby driving the inner ring of the protective bearing 3 to rotate. When the magnetic bearing shaft system falls, the speed of the protective bearing inner ring 3 is the same as the initial linear velocity of the rotor 1. Figure 4 , the rotor of magnetic suspension 1 did not enter the full-circle friction state after falling but remained in the bouncing state, and the bouncing height and vortex speed of rotor 1 also decreased to a certain extent. Figure 3 It can be seen that, through the protection device of the present invention, after the rotor 1 falls onto the protective bearing 3, the energy transmitted to the eddy speed part is reduced, and the vibration amplitude of the rotor is also significantly reduced. The protection device of the present invention avoids the occurrence of full-circle friction after the rotor 1 falls, and reduces the damage to the magnetic bearing system to a certain extent.

[0035] Although the embodiments of the present invention have been shown and described above, it will be understood that the above embodiments are illustrative and are not to be construed as limitations on the present invention. A person skilled in the art may change, modify, replace and modify the above embodiments within the scope of the present invention without departing from the principles and purpose of the present invention.

Claims

1. A magnetic bearing protection device based on a coaxial magnetic coupling, characterized by: The invention comprises a coaxial magnetic coupling and a protective sleeve (2); the protective sleeve (2) is located in the gap between the protective bearing (3) of the magnetic suspension bearing and the rotor (1); the protective sleeve (2) is coaxially sleeved on the rotor (1) of the magnetic suspension bearing and is detachably fixedly connected to the rotor; a first gap is provided between the outer ring of the protective sleeve and the inner ring of the protective bearing (3); The coaxial magnetic coupling comprises an outer magnetic cylinder (4), an outer cylinder magnetic block (5), an inner magnetic cylinder (6), and an inner cylinder magnetic block (7); the outer magnetic cylinder (4) is a cavity shell with an open end, which is sleeved on the end of the rotor (1), and its open end is coaxially fixedly connected to the inner ring of the protective bearing (3); the inner magnetic cylinder (6) is located inside the outer magnetic cylinder (4) and is coaxial with the outer magnetic cylinder (4), and an axial through hole is provided at the center position of its end face and is coaxially sleeved on the rotor (1), the inner end face of the inner magnetic cylinder (6) contacts the outer end face of the protective sleeve (2) for axial positioning, and the outer end face of the inner magnetic cylinder (6) is fixed to the end face of the rotor (1) by a fastener; the inner wall of the outer magnetic cylinder (4) and the outer wall of the inner magnetic cylinder (6) are respectively installed with the outer cylinder magnetic block (5) and the inner cylinder magnetic block (7); The outer cylinder magnetic blocks (5) and the inner cylinder magnetic blocks (7) are of the same number and shape; a plurality of outer cylinder magnetic blocks (5) are evenly distributed circumferentially and fixed to the inner wall of the outer magnetic cylinder (4); a plurality of inner cylinder magnetic blocks (7) are evenly distributed circumferentially and fixed to the outer wall of the inner magnetic cylinder (6); the outer cylinder magnetic blocks (5) and the inner cylinder magnetic blocks (7) correspond to each other one by one, are aligned and installed in parallel; and a second gap is provided between the corresponding outer cylinder magnetic blocks (5) and the corresponding inner cylinder magnetic blocks (7).

2. The magnetic bearing protection device based on a coaxial magnetic coupling according to claim 1 is characterized in that: The inner wall of the outer magnetic cylinder (4) and the outer wall of the inner magnetic cylinder (6) are both circumferentially evenly provided with corresponding installation grooves, and the outer cylinder magnetic block (5) and the inner cylinder magnetic block (7) are embedded and installed in their respective installation grooves.

3. The magnetic bearing protection device based on a coaxial magnetic coupling according to claim 1 is characterized in that: The outer magnetic cylinder (4) is a cylindrical cavity shell, and its open end is fixed to the inner ring of the protective bearing (3) by gluing.

4. The magnetic bearing protection device based on a coaxial magnetic coupling according to claim 1 is characterized in that: The inner magnetic cylinder (6) is cylindrical, and a recessed portion is provided around the axial through hole of its outer end surface; the rotor (1) of the magnetic suspension bearing passes through the axial through hole of the inner magnetic cylinder (6), and its end surface does not exceed the bottom surface of the recessed portion. The bottom surface of the recessed portion of the inner magnetic cylinder (6) is fixedly connected to the end surface of the rotor (1) by means of bolts (10) in conjunction with an axial end retaining ring (8).

5. The magnetic bearing protection device based on a coaxial magnetic coupling according to claim 1 is characterized in that: The inner magnetic cylinder (6) and the rotor (1) are circumferentially limited by a flat key (9).

6. The magnetic bearing protection device based on a coaxial magnetic coupling according to claim 1, characterized in that: The protective sleeve (2) and the rotor (1) are interference fit.

7. The magnetic bearing protection device based on a coaxial magnetic coupling according to claim 1, characterized in that: The inner magnetic cylinder (6) and the outer magnetic cylinder (4) are made of engineering plastics.

8. An application of the magnetic bearing protection device based on the coaxial magnetic coupling according to any one of claims 1 to 7, characterized in that: The magnetic suspension bearing protection device based on the coaxial magnetic coupling is installed at both ends of the magnetic suspension bearing. The rotor (1) end of the magnetic suspension bearing is a stepped shaft head, including a large diameter section (11) and a small diameter section (12). An axial threaded hole is provided at the center of the end face of the rotor (1); the protective sleeve (2) is coaxially sleeved on the large diameter section (11) and has an interference fit with the large diameter section (11). The inner end face of the protective sleeve (2) is pressed against the step of the large diameter section (11), and the outer end face extends to the small diameter section (12); the protective bearing (3) is coaxially sleeved on the protective sleeve (2), and a screw thread is provided between the inner ring of the protective sleeve and the protective sleeve (2). The first gap has an outer ring fixed to the outer shell of the magnetic suspension bearing (13); the open end of the outer magnetic cylinder (4) is coaxially fixedly connected to the inner ring of the protective bearing (3); the inner magnetic cylinder (6) is coaxially sleeved on the small diameter section (12), the inner end face of the inner magnetic cylinder (6) contacts the outer end face of the protective sleeve (2) for axial positioning, and the outer end face is fixedly connected to the end face of the rotor (1) through the shaft end retaining ring (8) and the bolt (10), and the inner magnetic cylinder (6) and the small diameter section (12) of the rotor (1) are circumferentially limited by a flat key (9); the outer cylinder magnetic block (5) and the inner cylinder magnetic block (7) are in one-to-one correspondence, aligned and parallel.

9. The application of the magnetic bearing protection device based on the coaxial magnetic coupling according to claim 8 is characterized in that: The protective bearing (3) is a deep groove ball bearing or an angular contact ball bearing.

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