Fully Suspended Low Vibration Reducer and Its Control Method

Abstract

This invention discloses a fully suspended low-vibration reducer, comprising two drive shafts and a pair of meshing gears on each drive shaft. The two drive shafts have identical structural layouts, each with a radial magnetic bearing arranged on the same axial side of the gears on each shaft, and an axial-radial hybrid magnetic bearing assembly arranged on the other axial side of the gears on the same shaft. The radial and axial displacements of the two drive shafts are detected, and the current signals of the magnetic bearing coils in the hybrid magnetic bearing assembly and the radial magnetic bearings are controlled based on the detected displacement signals to maintain stable suspension of the rotating shafts. This eliminates mechanical wear on the bearings and rotating shafts, reduces vibration and noise, and extends the service life of the reducer.

Description

Technical Field

[0001] This invention relates to the fields of magnetic levitation technology and speed reducers, and in particular to a speed reducer that uses a magnetic bearing to replace a mechanical bearing and its control method. Background Technology

[0002] A speed reducer is a typical basic mechanical component, commonly used as a speed reduction transmission device between a prime mover and a driven machine. It reduces speed, increases torque, improves accuracy, and lowers costs, and is widely used in various industries such as metallurgy, transportation, construction, automotive, and chemical industries. Due to the harsh operating environment and high speeds of speed reducers, the mechanical bearings within them are in direct contact with the rotating shaft. These bearings require lubrication, and overheating, noise, and wear can easily occur between the bearings and the rotating shaft, affecting the performance of the speed reducer and even the equipment itself.

[0003] Magnetic bearings use electromagnetic force to suspend the rotor in the air, so that there is no mechanical contact between the rotor and the stator. It is a new type of non-contact support method with advantages such as no mechanical friction, low noise, long service life, no need for lubrication, and controllable vibration.

[0004] In Chinese patent application CN106981970A, a magnetic coupler replaces the coupling between the motor and the load, forming a magnetic speed reducer. It transmits the motor's output torque through a magnetic field, eliminating the mechanical connection between the motor and the shaft. However, friction and wear still exist between the shaft and the bearings. The disadvantages of the magnetic coupler are that it is unsuitable for frequent start-stop operations and speed adjustments; it cannot resolve vibrations caused by load imbalance; and it is unsuitable for low-speed operation.

[0005] Since the magnetic coupler coexists with the original bearing lubrication system, oil leakage can easily cause contamination of the magnetic coupler, shorten the service life of the reducer, and also cause mechanical wear of the drive shaft, resulting in vibration and noise.

[0006] On the other hand, magnetic couplers achieve speed regulation by adjusting the air gap, which has certain limitations. When the shaft speed changes drastically, they cannot guarantee stable suspension of the rotating shaft and are prone to failure. Summary of the Invention

[0007] The main objective of this invention is to provide a fully suspended low-vibration reducer and its control method, which eliminates mechanical wear of bearings and rotating shafts, reduces vibration and noise, and extends the service life of the reducer.

[0008] Furthermore, the present invention can ensure the stable suspension of the rotating shaft and the stable operation of the fully suspended low-vibration reducer.

[0009] Furthermore, the present invention can also solve the problem of oil leakage when applied in clean environments.

[0010] The technical solution adopted in this invention is:

[0011] A fully suspended low-vibration reducer includes two drive shafts and a pair of meshing gears on each drive shaft; characterized in that:

[0012] The two drive shafts have the same structural layout, with a radial magnetic bearing arranged on the same side of the gear's axial direction on each shaft, and an axial-radial hybrid magnetic bearing assembly arranged on the other side of the gear's axial direction on each shaft.

[0013] The axial-radial hybrid magnetic bearing assembly includes a radial magnetic bearing and an axial magnetic bearing. The radial magnetic bearing and the axial magnetic bearing in the axial-radial hybrid magnetic bearing assembly form two magnetic flux loops through the same permanent magnet and a magnetic guide plate.

[0014] In the above technical solution, the axial and radial hybrid magnetic bearing assemblies and the radial magnetic bearings on each shaft are all provided with isolation components at the end facing the gear on that shaft.

[0015] In the above technical solution, both the radial magnetic bearing and the axial magnetic bearing include a rotor, a stator that maintains an air gap with the rotor, and a magnetic bearing coil disposed on the stator.

[0016] In the above technical solution, the radial magnetic bearing includes: a radial magnetic levitation rotor, a radial magnetic bearing stator disposed around the radial magnetic levitation rotor and maintaining a radial working air gap with the radial magnetic levitation rotor, an axial end cover with a central bearing, a magnetic guide ring, a permanent magnet, and a magnetic guide plate disposed between the radial magnetic bearing stator and the axial end cover, and a sensor measuring ring located inside the axial end cover and not in direct contact with the central bearing inside the axial end cover, wherein an on-shaft bushing is disposed axially between the sensor measuring ring and the radial magnetic levitation rotor; and radial magnetic bearing coils are wound around each radial magnetic bearing stator via pole posts.

[0017] In the above technical solution, the axial and radial hybrid magnetic bearing assembly includes a radial magnetic bearing, an axial magnetic bearing stator disposed between the axial end cover and the magnetic guide plate, and a stepped sleeve-type thrust disk axially disposed between the axial magnetic bearing stator and the magnetic guide plate; the axial magnetic bearing stator is fixedly connected to the magnetic guide plate and forms a hollow annular gap between the two and the thrust disk, and an axial magnetic bearing coil is disposed in the hollow annular gap.

[0018] In the above technical solution, the axial major diameter end of the thrust disk abuts against the axial magnetic bearing stator and the sensor measuring ring, while the axial minor diameter end of the thrust disk passes through the radial magnetic levitation rotor and is sleeved on the drive shaft.

[0019] In the above technical solution, the permanent magnet is supported and fixed by a permanent magnet positioning ring on the inner diameter of the permanent magnet.

[0020] In the above technical solution, there is an air gap between the central bearing and the sensor measuring ring in the radial direction to prevent them from contacting each other, and the thickness of the air gap is the same as that of the radial magnetic bearing stator and the radial magnetic levitation rotor.

[0021] In the above technical solutions, the central bearings do not include a bearing lubrication system.

[0022] In the above technical solution, each transmission shaft also includes a displacement sensor disposed at at least one end of the shaft, and the displacement sensor is electrically connected to the magnetic bearing coil.

[0023] A control method for the above-mentioned fully suspended low-vibration reducer is characterized by comprising the following steps:

[0024] The radial and axial displacements of the two drive shafts are detected, and the current signals of the magnetic bearing coils in the hybrid magnetic bearing assembly and the radial magnetic bearing are controlled based on the detected displacement signals to keep the rotating shaft stably suspended.

[0025] By adopting the above technical solution, this invention uses a magnetic bearing instead of a mechanical bearing, allowing the rotating shaft to levitate in the air without contact or friction with the bearing. Furthermore, the rotating shaft can be actively controlled via the magnetic bearing, and an algorithm ensures stable levitation of the rotating shaft.

[0026] Compared with the prior art, the present invention has the following technical advantages:

[0027] This invention proposes a fully suspended low-vibration reducer and its control technology. It replaces traditional mechanical bearings with radial magnetic bearings and axial-radial hybrid magnetic bearing assemblies to support the rotating shafts. The structural components on the high-speed and low-speed rotating shafts are uniformly distributed, and the two shafts are centrally symmetrical. Furthermore, through one radial support in each direction and one axial support on each shaft, a total of five degrees of freedom (radial magnetic bearings and axial-radial hybrid magnetic bearings) are achieved for the high-speed and low-speed shafts. A control algorithm ensures stable suspension of the rotating shafts. The structure is simple, and the control method is relatively stable.

[0028] In the axial-radial hybrid magnetic bearing assembly of the present invention, the magnetic flux circuits formed by the two magnetic bearings, the axial magnetic bearing and the radial magnetic bearing, both pass through the same permanent magnet and the same magnetic guide plate. There is no need to set up two sets of redundant magnetic system components. This design simplifies the structure of the magnetic bearing and reduces the volume of the entire structure.

[0029] This invention achieves this by setting the air gap thickness between the central bearing and the sensor measuring ring radially to be smaller than the air gap between the radial magnetic bearing stator and the radial magnetic levitation rotor. This allows the rotating shaft to levitate in the air, eliminating contact and frictional wear with the magnetic bearing. The bearing lubrication system can be eliminated, thus removing mechanical wear on the bearing and rotating shaft and extending the service life of the reducer. It also ensures a clean working environment.

[0030] In this invention, displacement sensors are used to measure the radial and axial displacements of the high-speed and low-speed shafts to detect the working state of the rotating shafts. After processing, the displacement signal is converted into a control current signal by the controller and power amplifier, which is applied to the coils of each magnetic bearing to generate corresponding control adjustment force. This achieves stable control of the rotor position of the magnetic bearing, reduces the vibration of the reducer, and prevents major failures of the reducer. Attached Figure Description

[0031] The present invention will be further described below with reference to the accompanying drawings and embodiments. In the accompanying drawings:

[0032] Figure 1 This is a schematic diagram of the overall structure of a fully suspended low-vibration reducer according to one embodiment of the present invention.

[0033] Figure 2 This is a cross-sectional view of the radial magnetic bearing in a fully suspended low-vibration reducer according to one embodiment of the present invention.

[0034] Figure 3 This is a cross-sectional view of the axial and radial hybrid magnetic bearing assembly in a fully suspended low-vibration reducer according to one embodiment of the present invention.

[0035] Figure 4 This is a schematic diagram of the fully suspended low-vibration reducer control method of the present invention.

[0036] In the diagram: 1. Low-speed shaft; 2. Housing; 3. Radial magnetic bearing; 4. Large gear; 5. Axial and radial hybrid magnetic bearing assembly; 6. Partition plate; 7. High-speed shaft; 8. Small gear; 9. Sleeve; 10. Displacement sensor; 11. Front radial magnetic bearing stator; 12. First magnetic guide ring; 13. First permanent magnet positioning ring; 14. First permanent magnet; 15. First magnetic guide plate; 16. First end cover; 17. First deep groove ball bearing; 18. First elastic retaining ring; 19. First sensor measuring ring; 20. Bushing; 21. Front radial magnetic bearing... 21. Suspended rotor; 22. First radial magnetic bearing coil; 23. Rear radial magnetic bearing stator; 24. Second magnetic ring; 25. Second permanent magnet positioning ring; 26. Second permanent magnet; 27. Second magnetic plate; 28. Axial magnetic bearing stator; 29. ​​Second end cover; 30. Second radial magnetic bearing coil; 31. Rear radial magnetic levitation rotor; 32. Thrust disc; 33. Axial thrust disc retaining ring; 34. Axial magnetic bearing coil; 35. Second sensor measuring ring; 36. Second deep groove ball bearing; 37. Second elastic retaining ring. Detailed Implementation

[0037] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0038] Example 1:

[0039] A fully suspended low-vibration reducer and its control method according to the present invention, such as Figure 1 As shown, the overall structure of the fully suspended low-vibration reducer of one embodiment of the present invention mainly includes a pair of transmission shafts (low-speed shaft 1 and high-speed shaft 7) arranged parallel to each other on the bottom base of the housing 2 and interacting with each other through meshing gears (large gear 4 and small gear 8). The structural parts on these two rotating shafts are distributed in the same position, and the two shafts are placed in a position that is symmetrical with respect to the center of the housing 2.

[0040] On each drive shaft, there are respectively set in the forward direction ( Figure 1 The radial magnetic bearing 3 (located on the left front side in the forward direction), the large gear 4 (or small gear 8), and the axial-radial hybrid magnetic bearing assembly 5 located behind the gear.

[0041] Displacement sensors 10 are provided at at least one end of each drive shaft to measure the radial and axial displacements of the drive shaft respectively. Each displacement sensor 10 is connected to a control system 100 including a controller and a power amplifier. The displacement signal enters the control system 100, is processed, and outputs a control current to the magnetic bearing coil to generate a certain control adjustment force, so as to control the radial magnetic bearing 3 and the axial-radial hybrid magnetic bearing assembly 5 on each shaft, thereby realizing stable suspension control of the rotating shaft.

[0042] One end of the high-speed shaft 7 is connected to a motor (not shown) to control the rotational degree of freedom and drive. Two radial magnetic bearings 3 (such as...) Figure 2 Two radial degrees of freedom are controlled to bear the radial load of the high-speed shaft 7 and ensure its suspension. An axial-radial hybrid magnetic bearing assembly 5 is located behind the gear to control the axial degree of freedom and bear the axial load generated by gear meshing. The rotation of the low-speed shaft 1 is achieved through the meshing transmission of the large gear 4 and the small gear 8. The control of the remaining degrees of freedom is consistent with the control method.

[0043] like Figure 1 The small gear 8 is mounted on the high-speed shaft 7, and the large gear 4 is mounted on the low-speed shaft 1. Both are circumferentially fixed using flat keys. One end of each gear is positioned by a shoulder on the respective drive shaft, and the other end by a sleeve 9, thus securing the gears. A partition 6 or similar isolator is installed between each gear and each radial magnetic bearing 3, as well as the axial-radial hybrid magnetic bearing assembly 5, to prevent gear lubricating oil from entering the radial magnetic bearing 3 and the axial-radial hybrid magnetic bearing assembly 5. Therefore, this device requires a total of four partitions. The partitions 6 are positioned by the shoulders on each rotating shaft and the radial magnetic bearing 3 and the axial-radial hybrid magnetic bearing assembly 5 themselves.

[0044] The partition 6 is axially positioned by the shoulders on each rotating shaft and the radial magnetic levitation rotors (each front radial magnetic levitation rotor 21 and rear radial magnetic levitation rotor 31).

[0045] like Figure 2 As shown, the radial magnetic bearing 3 is composed of a front radial magnetic bearing stator 11, a first radial magnetic bearing coil 22, a front radial magnetic levitation rotor 21, a first magnetic ring 12, a first permanent magnet positioning ring 13, a first permanent magnet 14, a first magnetic plate 15, a bushing 20, a first deep groove ball bearing 17, a first elastic retaining ring 18, a first sensor measuring ring 19, and a first end cap 16.

[0046] The front radial magnetic bearing stator 11 has 4 pole posts, and each pole post is wound with a set of radial magnetic bearing coils 22.

[0047] The front radial magnetic levitation rotor 21 is interference-fitted with the rotating shaft and fixed by the sleeve 9 and bushing 20. Its position corresponds to the front radial magnetic bearing stator 11. There is a certain working air gap between the front radial magnetic levitation rotor 21 and the front radial magnetic bearing stator 11, and there is no direct contact.

[0048] The first magnetic ring 12, the first permanent magnet 14, the first magnetic plate 15, and the front radial magnetic bearing stator 11 are axially connected, forming a complete magnetic flux loop together with the bushing 20 and the front radial magnetic levitation rotor 21. The first permanent magnet 14 is positioned by the first permanent magnet positioning ring 13. The first permanent magnet 14 can provide a bias magnetic field, which can reduce the number of turns of the magnetic levitation coil and reduce the loss generated by the bias current.

[0049] The first end cap 16 is embedded in the groove opened in the bottom foundation of the housing 2 to complete the axial fixation of the radial magnetic bearing.

[0050] The first deep groove ball bearing 17 is placed in the opening on the outer end face of the first end cover 16 and fixed with the first elastic retaining ring 18. The first deep groove ball bearing 17 does not directly contact the first sensor measuring ring 19. The thickness of the air gap between them should be half of the air gap between the front radial magnetic bearing stator 11 and the front radial magnetic levitation rotor 21, so as to prevent the rotating shaft from directly colliding with the magnetic bearing when the magnetic bearing fails, thus playing a protective role.

[0051] Figure 3 The structure of the axial-radial hybrid magnetic bearing assembly 5 is shown. The axial-radial hybrid magnetic bearing assembly 5 is an axial magnetic bearing and... Figure 2 The radial magnetic bearing 3 in the structure includes: a rear radial magnetic bearing stator 23, a radial magnetic bearing coil 30, a rear radial magnetic levitation rotor 31, a second magnetic ring 24, a second permanent magnet 26, a second permanent magnet positioning ring 25, a thrust disk 32, a second axial thrust disk retaining ring 33, a second magnetic plate 27, an axial magnetic bearing stator 28, an axial magnetic bearing coil 30, a second deep groove ball bearing 36, a second elastic retaining ring 37, a second sensor measuring ring 35, and a second end cap 29.

[0052] The rear radial magnetic bearing stator 23 also has 4 poles wound around the second radial magnetic bearing coil 30, and the axial magnetic bearing stator 28 has a set of axial magnetic bearing coils 34 wound around it.

[0053] The rear radial magnetic levitation rotor 31 is interference-fitted with the thrust plate 32, which is sleeved on the rotating shaft. The rear radial magnetic levitation rotor 31 and the rear radial magnetic bearing stator 23 are positioned to generate corresponding magnetic force and ensure the working air gap without direct contact.

[0054] The thrust disk 32 maintains an axial working air gap with the second magnetic ring 24 and the axial magnetic bearing stator 28, respectively, to provide axial force. The axial-radial hybrid magnetic bearing assembly 5 contains two magnetic flux loops: one consisting of the second magnetic ring 24, the second permanent magnet 26, the second magnetic plate 27, the thrust disk 32, and the rear radial magnetic levitation rotor 31, realizing the radial magnetic bearing function; the other consisting of the second magnetic plate 27, the axial magnetic bearing stator 28, and the thrust disk 32, realizing the axial magnetic bearing function.

[0055] The second magnetic plate 27 is bolted to the axial magnetic bearing stator 28 and is positioned by the axial magnetic bearing retaining ring 33.

[0056] Figure 3 The magnetic flux loops formed by the central axial magnetic bearing and the radial magnetic bearing both pass through the second permanent magnet 26 and the second magnetic guide plate 27. This design simplifies the structure of the magnetic bearing and reduces the overall size of the structure. The second deep groove ball bearing 36 functions and is installed in the same way as the first deep groove ball bearing 17 in the radial magnetic bearing.

[0057] like Figure 4 As shown, the reducer control method in this embodiment of the invention is as follows. The installed displacement sensor 10 measures the radial and axial displacement signals of the rotating shaft. The displacement signal is used as a feedback signal and the difference is calculated with the reference signal. Then, the difference is input to the controller. After the controller adjusts the signal, it is output to the power amplifier, which converts the voltage signal into a control current signal. This current signal is applied to the coils of each magnetic bearing in the axial and radial magnetic bearings to achieve stable control of the rotor position of the magnetic bearings.

[0058] Example 2:

[0059] In Example 2, the lubrication system for all bearings is removed, as in Example 1.

[0060] In the normal operating state of the reducer in this invention, the magnetic bearing has no mechanical contact with the rotating shaft, which eliminates the need for the bearing lubrication system, eliminates wear between the rotating shaft and the bearing, and extends the service life of the reducer. Moreover, it can reduce the vibration level of the reducer, and by observing the control current of the magnetic bearing, the operating state of the reducer can be analyzed to prevent major failures of the reducer.

[0061] It should be understood that those skilled in the art can make improvements or modifications based on the above description, and all such improvements and modifications should fall within the protection scope of the appended claims.

Claims

1. A fully suspended low-vibration reducer, comprising two fully suspended drive shafts and a pair of meshing gears mounted on each drive shaft; characterized in that: The two drive shafts have the same structure and component layout. A radial magnetic bearing is arranged on the same side of the gear axis on each shaft, and an axial-radial hybrid magnetic bearing assembly is arranged on the other side of the gear axis on each shaft, forming a total of 5 degrees of freedom for radial magnetic bearing and axial-radial hybrid magnetic bearing control; the two shafts are placed in a centrally symmetrical position. The axial-radial hybrid magnetic bearing assembly includes a combination structure of a radial magnetic bearing and an axial magnetic bearing. The radial magnetic bearing and the axial magnetic bearing in the axial-radial hybrid magnetic bearing assembly form two magnetic flux loops through the same permanent magnet and a magnetic guide plate. The radial magnetic bearing includes: a radial magnetic levitation rotor, a radial magnetic bearing stator disposed around the radial magnetic levitation rotor and maintaining a radial working air gap with the radial magnetic levitation rotor, an axial end cover with a central bearing, a magnetic guide ring, a permanent magnet, and a magnetic guide plate disposed between the radial magnetic bearing stator and the axial end cover, and a sensor measuring ring located inside the axial end cover and not in direct contact with the central bearing inside the axial end cover, with an on-shaft bushing disposed axially between the sensor measuring ring and the radial magnetic levitation rotor; and radial magnetic bearing coils wound around each radial magnetic bearing stator via pole posts. There is an air gap in the radial direction between the central bearing and the sensor measuring ring to prevent them from contacting each other, and the thickness of the air gap is the same as that of the radial magnetic bearing stator and the radial magnetic levitation rotor.

2. The fully suspended low-vibration speed reducer according to claim 1, characterized by: The axial and radial hybrid magnetic bearing assemblies and the radial magnetic bearings on each shaft are all equipped with isolation components at the end facing the gear on that shaft.

3. The fully suspended low-vibration speed reducer according to claim 1, characterized by: Both radial magnetic bearings and axial magnetic bearings include a rotor, a stator that maintains an air gap with the rotor, and magnetic bearing coils disposed on the stator.

4. The full-suspension low-vibration speed reducer according to claim 3, characterized by: Each drive shaft also includes a displacement sensor disposed at at least one end of the shaft, the displacement sensor being electrically connected to the magnetic bearing coil.

5. The fully suspended low-vibration reducer according to claim 1, characterized in that: The axial-radial hybrid magnetic bearing assembly includes a radial magnetic bearing, an axial magnetic bearing stator disposed between the axial end cover and the magnetic guide plate, and a stepped sleeve-type thrust disk axially disposed between the axial magnetic bearing stator and the magnetic guide plate; the axial magnetic bearing stator is fixedly connected to the magnetic guide plate and forms a hollow annular gap between the two and the thrust disk, and an axial magnetic bearing coil is disposed in the hollow annular gap.

6. The fully suspended low-vibration reducer according to claim 5, characterized in that: The thrust disk's axial major diameter end abuts against the axial magnetic bearing stator and sensor measuring ring, while the thrust disk's axial minor diameter end passes through the radial magnetic levitation rotor and is sleeved on the drive shaft.

7. The fully suspended low-vibration reducer according to claim 1, characterized in that: None of the central bearings mentioned include a bearing lubrication system.

8. A control method for the fully suspended low-vibration reducer according to any one of claims 1-7, characterized in that... Includes the following steps: The radial and axial displacements of the two drive shafts are detected, and the current signals of the magnetic bearing coils in the hybrid magnetic bearing assembly and the radial magnetic bearing are controlled based on the detected displacement signals to keep the rotating shaft stably suspended.

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