Hybrid bearing device, control method and centrifugal compressor

Abstract

The present disclosure provides a hybrid bearing device, a control method and a centrifugal compressor, wherein the hybrid bearing device comprises: a first bearing core, a thrust plate and a second bearing core are mounted on a rotating shaft; a hydrodynamic bearing is arranged between the bearing core and the thrust plate; a skeleton groove is arranged on the end surface of the bearing core facing the thrust plate, a coil skeleton is installed in the skeleton groove, and a coil is arranged in the coil skeleton. The hybrid bearing device disclosed in the present disclosure, through the cooperation of the hydrodynamic bearing and magnetic suspension, enables the centrifugal compressor to be in a complete suspension stage or a critical suspension state when starting and stopping, thereby avoiding and reducing friction, and solving the problem of wear of the hydrodynamic bearing during the start-stop process; when the compressor is operating normally, the hydrodynamic bearing can operate under the optimal design load under the design load.

Description

Technical Field

[0001] The present disclosure belongs to the technical field of compressors, and in particular relates to a hybrid bearing device, a control method and a centrifugal compressor. Background Art

[0002] Centrifugal refrigeration compressors are high-speed compressors. The compressor rotor rotates at high speed during operation and will bear different loads from the axial direction. Currently, the main environmentally friendly oil-free bearings are electromagnetic bearings and gas bearings.

[0003] Electromagnetic bearings achieve axial load-bearing through electromagnetic force and electronic control without mechanical contact, which avoids direct contact between the rotor and the bearing, does not require lubrication and sealing, and completely eliminates wear. However, due to the magnetic saturation of the material and electromagnetic heating, the load-bearing capacity of the electromagnetic bearing cannot be further improved.

[0004] The dynamic pressure air bearing mainly uses gas as the lubricating medium. Its rotor has a relatively low load-bearing capacity when running at a low speed, and its damping and stiffness are also relatively low, resulting in poor parking performance. Due to the low rotor speed of the dynamic pressure gas at startup, the air pressure in the shaft is insufficient and the supporting force is insufficient, which will cause the bearing to be in a dry friction state. Only when the bearing speed reaches a certain value can a dynamic pressure air film be formed and enter a stable gas lubrication state; at the same time, there is also a dry friction state during the stopping process. When the bearing speed drops to a certain value, the dynamic pressure air film disappears, and the bearing enters a dry friction state. Under the action of dry friction, the bearing speed drops to zero. This dry friction state of the bearing causes serious wear on the working surface of the bearing, reduces the working life, and even causes the starting torque to exceed the motor stall torque, so the motor cannot start. Every repeated start and stop will inevitably reduce a certain amount of service life, and at the same time cause a decrease in reliability. Summary of the invention

[0005] Therefore, the technical problem to be solved by the present disclosure is that the centrifugal compressor of the related art only includes electromagnetic bearings or hydrodynamic bearings, which have the problems of weak bearing capacity and severe wear during start-stop, thereby providing a hybrid bearing device, a control method and a centrifugal compressor.

[0006] In order to solve the above problems, the present disclosure provides a hybrid bearing device, comprising:

[0007] A rotating shaft, on which a first bearing core, a thrust plate, and a second bearing core are sequentially mounted along the axial direction;

[0008] A dynamic pressure bearing is provided between the first bearing iron core and the thrust plate, and between the second bearing iron core and the thrust plate;

[0009] The end surface of the first bearing iron core facing the thrust plate and the end surface of the second bearing iron core facing the thrust plate are respectively provided with skeleton grooves, coil skeletons are installed in the skeleton grooves, and coils are arranged in the coil skeletons.

[0010] In some embodiments, the outer diameter of the hydrodynamic bearing is smaller than the outer diameter of the skeleton groove.

[0011] In some embodiments, the coil frame is provided with a wire groove, which is opened on the outer peripheral surface of the coil frame and extends in the radial direction of the coil frame, and the coil is arranged in the wire groove.

[0012] In some embodiments, the coil skeleton is further provided with a skeleton fixing portion, and the skeleton fixing portion is configured to fix the coil skeleton on the first bearing core or the second bearing core.

[0013] In some embodiments, the skeleton fixing portion protrudes along the depth direction of the skeleton groove, and the end surfaces of the first bearing core and the second bearing core away from the thrust plate are provided with through holes, the through holes correspond to the positions of the skeleton fixing portions, and screws are inserted into the through holes, and the screws are spirally connected to the skeleton fixing portion to fix the skeleton fixing portion to the first bearing core or the second bearing core.

[0014] In some embodiments, a stress sensor is provided between the hydrodynamic bearing and the thrust plate, and the stress sensor is configured to detect changes in the axial force between the thrust plate and the hydrodynamic bearing and output an electrical signal.

[0015] In some embodiments, the stress sensor is connected to a proportional amplifier, and the electrical signal output by the stress sensor is passed through the proportional amplifier and then into the coil.

[0016] A control method using the hybrid bearing device comprises:

[0017] During the startup phase, the coil is energized to detect the position of the thrust plate;

[0018] If it is detected that the thrust plate is not within the preset position range, the magnitude of the current passed through the coil is adjusted to make the thrust plate within the preset position range between the two hydrodynamic bearings;

[0019] During the shutdown phase, the coil is energized to detect the position of the thrust plate;

[0020] If it is detected that the thrust plate is not within the preset position range, the current passed through the coil is adjusted to make the thrust plate within the preset position range between the two hydrodynamic bearings until the shaft stops rotating.

[0021] In some embodiments, the control method further comprises:

[0022] During the operation phase, the coil is energized to detect whether the axial force on the hydrodynamic bearing is within the preset pressure range;

[0023] If it is detected that the axial force on the hydrodynamic bearing exceeds or does not reach the preset pressure range, the magnitude of the current passed through the coil is adjusted to make the axial force on the hydrodynamic bearing within the preset pressure range.

[0024] A centrifugal compressor adopts the hybrid bearing device or the control method mentioned above.

[0025] The hybrid bearing device, control method and centrifugal compressor provided by the present disclosure have at least the following beneficial effects:

[0026] The hybrid bearing device disclosed in the present invention, through the cooperation of the hydrodynamic bearing and the magnetic suspension, can make the centrifugal compressor be in a complete suspension stage or a critical suspension state when starting and stopping, so as to avoid and reduce friction and solve the problem of bearing wear of the hydrodynamic bearing during the start-stop process; when the compressor is operating normally, the hydrodynamic bearing can work under the optimal design load under the design load; when the compressor is working under non-design conditions, the magnetic suspension bearing will adjust the load through electromagnetic force to move the thrust plate axially, so as to ensure that the hydrodynamic bearing can work under the optimal design. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 is a schematic structural diagram of a hybrid bearing device according to an embodiment of the present disclosure;

[0028] Figure 2 It is a schematic diagram of the structure of the bearing core in the embodiment of the present disclosure;

[0029] Figure 3 is a schematic structural diagram of a coil skeleton in an embodiment of the present disclosure;

[0030] Figure 4 It is a schematic diagram of the assembly of the bearing core, coil frame and coil in the embodiment of the present disclosure;

[0031] Figure 5 Schematic diagram of the connection of the hydrodynamic bearing, stress sensor, and coil in the embodiment of the present disclosure.

[0032] The reference numerals are as follows:

[0033] 1. Rotating shaft; 2. First bearing core; 3. Thrust plate; 4. Second bearing core; 5. Hydrodynamic bearing; 6. Skeleton groove; 7. Coil skeleton; 8. Coil; 9. Wire groove; 10. Skeleton fixing part; 11. Through hole; 12. Stress sensor; 13. Proportional amplifier. DETAILED DESCRIPTION

[0034] In order to make the purpose, technical solutions and advantages of the present disclosure clearer, the technical solutions of the present disclosure will be clearly and completely described below in combination with the specific embodiments of the present disclosure and the corresponding drawings. Obviously, the described embodiments are only part of the embodiments of the present disclosure, not all of the embodiments. Based on the embodiments in the present disclosure, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present disclosure.

[0035] Combination Figures 1 to 5 As shown, this embodiment provides a hybrid bearing device, including: a rotating shaft 1, on which a first bearing core 2, a thrust plate 3, and a second bearing core 4 are sequentially assembled along the axial direction; a hydrodynamic bearing 5 is respectively provided between the first bearing core 2 and the thrust plate 3, and between the second bearing core 4 and the thrust plate 3; a skeleton groove 6 is respectively provided on the end surface of the first bearing core 2 facing the thrust plate 3, and a skeleton groove 6 is respectively provided on the end surface of the second bearing core 4 facing the thrust plate 3, a coil skeleton 7 is installed in the skeleton groove 6, and a coil 8 is provided in the coil skeleton 7.

[0036] The hybrid bearing device of the disclosed embodiment, through the cooperation of the hydrodynamic bearing and the magnetic suspension, can put the centrifugal compressor in a complete suspension stage or a critical suspension state when starting and stopping, thereby avoiding and reducing friction and solving the problem of wear of the hydrodynamic bearing during the start-stop process; when the compressor is operating normally, the hydrodynamic bearing can operate under the optimal design load under the design load; when the compressor is operating under non-design conditions, the magnetic suspension bearing will adjust the load through electromagnetic force to move the thrust plate axially, thereby ensuring that the hydrodynamic bearing can operate under the optimal design.

[0037] In some embodiments, the outer diameter of the hydrodynamic bearing 5 is smaller than the outer diameter of the skeleton groove 6, and the hydrodynamic bearing 5 is arranged closer to the rotating shaft 1 than the coil 8, so that the thrust plate 3 can be made smaller. If the hydrodynamic bearing 5 is arranged farther away from the rotating shaft 1 than the coil 8, the inner diameter of the hydrodynamic bearing 5 will become larger, resulting in a smaller force area of ​​the hydrodynamic bearing 5. At this time, the outer diameters of the hydrodynamic bearing 5 and the thrust plate 3 can only be increased, which will cause the components to become larger and affect the critical speed and the strength of the thrust plate.

[0038] In some embodiments, the outer diameter of the hydrodynamic bearing 5 is smaller than the inner diameter of the framework groove 6 , so that the thrust plate 3 can be made smaller.

[0039] In some embodiments, the axial clearance between the hydrodynamic bearing 5 and the thrust plate 3 is smaller than the axial clearance between the first bearing core 2 and the thrust plate 3, and the axial clearance between the second bearing core 4 and the thrust plate 3, so as to ensure that the hydrodynamic bearing 5 plays a major supporting role for the thrust plate 3 when the compressor is running.

[0040] In some embodiments, the coil skeleton 7 is provided with a wire groove 9, which is opened on the outer peripheral surface of the coil skeleton 7 and extends radially along the coil skeleton 7, and the coil 8 is arranged in the wire groove 9. Therefore, the coil 8 is wound in the wire groove 9, and after the coil skeleton 7 is installed in the skeleton groove 6, the outer wall of the skeleton groove 6 closes the radially outward opening of the wire groove 9, preventing the coil 8 from interfering with other parts in the normal direction during assembly due to unevenness, and closing the side toward the thrust plate 3 through the coil skeleton 7, preventing the axial unevenness from causing friction and collision with the thrust plate 3 during operation.

[0041] In some embodiments, in order to ensure that the coil skeleton 7 is firmly embedded in the skeleton groove 6 to prevent it from falling off, the coil skeleton 7 is also provided with a skeleton fixing part 10, and the skeleton fixing part 10 is constructed to fix the coil skeleton 7 on the first bearing core 2 and the second bearing core 4.

[0042] In some embodiments, the skeleton fixing portion 10 protrudes along the depth direction of the skeleton groove 6, and the end faces of the first bearing core 2 and the second bearing core 4 away from the thrust plate 3 are provided with a through hole 11, and the through hole 11 is opposite to the skeleton fixing portion 10. Screws are inserted into the through holes 11, and the screws are spirally connected to the skeleton fixing portion 10 to fix the skeleton fixing portion 10 to the first bearing core 2 or the second bearing core 4, so that the coil skeleton 7 is installed from the inner end face of the bearing core (i.e., the end face facing the thrust plate 3), and it can be fixed by screws from the outer end face of the bearing core (i.e., the end face away from the thrust plate 3), which is easy to install and has reliable fixing performance.

[0043] In some embodiments, a stress sensor 12 is provided between the hydrodynamic bearing 5 and the thrust plate 3. The stress sensor 12 is configured to detect changes in the axial force between the thrust plate 3 and the hydrodynamic bearing 5 and output an electrical signal. The axial force of the hydrodynamic bearing 5 is detected by the stress sensor 12, and an electrical signal is fed back. Based on the signal, the compensation amount of the supporting force of the magnetic levitation bearing is controlled.

[0044] In some embodiments, the stress sensor 12 is connected to a proportional amplifier 13. The electrical signal output by the stress sensor 12 is passed through the proportional amplifier 13 and then into the coil 8, so that the electromagnetic thrust generated by the magnetic bearing and the hydrodynamic bearing 5 can achieve a better compensation effect, so that the thrust plate 3 is in a preset position.

[0045] This embodiment adds an auxiliary magnetic bearing to the centrifugal compressor structure to axially suspend the rotor during the start-up and stop process of the compressor, thereby avoiding dry friction of the hydrodynamic bearing with the compressor during the start-up and stop process. At the same time, when the compressor is operating normally, the axial force changes, and the stress sensor behind the hydrodynamic bearing will be subjected to greater pressure, which is fed back to the opposite electromagnetic bearing through current, causing the rotor to move in the opposite direction, ensuring that the gas bearing works under the designed load. The present disclosure can adjust the axial load of the compressor, thereby increasing the service life of the bearing and the operating stability of the compressor.

[0046] This embodiment also provides a control method using the above hybrid bearing device, including:

[0047] In the startup phase, the coil 8 is energized first, the magnetic bearing starts to work, and the position of the thrust plate 3 is detected by the stress sensor 12;

[0048] If it is detected that the thrust plate 3 is not within the preset position range, the magnitude of the current passed through the coil 8 is adjusted to make the thrust plate 3 within the preset position range between the two hydrodynamic bearings 5;

[0049] During the shutdown phase, the coil 8 is energized to detect the position of the thrust plate 3;

[0050] If it is detected that the thrust plate 3 is not within the preset position range, the current passed through the coil 8 is adjusted to make the thrust plate 3 within the preset position range between the two hydrodynamic bearings 5 ​​until the shaft 1 stops rotating.

[0051] This embodiment can ensure that the hydrodynamic bearing does not wear or reduce friction during the start-up and stop processes of the compressor, thereby increasing the life of the thrust bearing.

[0052] During the operation phase, the stress sensor 12 between the hydrodynamic bearing 5 and the bearing core will detect a large axial force, and the thrust plate 3 will move toward the side with the larger axial force, causing the hydrodynamic bearing to bear a large axial force. At this time, the stress sensor 12 needs to feed back the detected signal to the magnetic suspension bearing in the opposite direction, so that it increases the electromagnetic force in the opposite direction and returns the thrust plate 3 to the preset position.

[0053] Through this adjustment, it can be ensured that the thrust plate 3 always works in a better position. At the same time, the bearing capacity of the hydrodynamic bearing 5 can be increased. When the compressor is subjected to less axial force, the stress sensor 12 detects less and generates less current, which is not enough to drive any coil 8 to generate enough electromagnetic force to make the magnetic bearing work. The hydrodynamic bearing 5 plays the main role of bearing the axial force. Through this two-way adjustment structure, it can be ensured that the rotor works between the two hydrodynamic bearings. At the same time, when the working conditions change, the gap of the hydrodynamic bearing 5 can still be ensured to be in a reasonable range. Under excessive axial load, the corrugated foil of the hydrodynamic bearing 5 will not be deformed too much, causing the thrust plate 3 to collide.

[0054] A centrifugal compressor adopts the hybrid bearing device or the control method mentioned above.

[0055] It is easy for those skilled in the art to understand that, under the premise of no conflict, the above-mentioned advantageous methods can be freely combined and superimposed.

[0056] The above are only preferred embodiments of the present disclosure and are not intended to limit the present disclosure. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present disclosure shall be included in the protection scope of the present disclosure. The above are only preferred implementations of the present disclosure. It should be pointed out that for ordinary technicians in this technical field, several improvements and variations can be made without departing from the technical principles of the present disclosure, and these improvements and variations should also be regarded as the protection scope of the present disclosure.

Claims

1. A control method for a hybrid bearing device, characterized in that: The hybrid bearing device comprises: A rotating shaft (1), wherein a first bearing core (2), a thrust plate (3), and a second bearing core (4) are sequentially mounted on the rotating shaft (1) along the axial direction; a hydrodynamic bearing (5) is respectively arranged between the first bearing core (2) and the thrust plate (3), and between the second bearing core (4) and the thrust plate (3); a skeleton groove (6) is respectively arranged on the end surface of the first bearing core (2) facing the thrust plate (3), and a skeleton groove (7) is respectively arranged on the end surface of the second bearing core (4) facing the thrust plate (3); a coil skeleton (7) is installed in the skeleton groove (6), and a coil (8) is arranged in the coil skeleton (7); The control method comprises: During the start-up phase, the coil (8) is energized to detect the position of the thrust plate (3); If it is detected that the thrust plate (3) is not within the preset position range, the magnitude of the current passed through the coil (8) is adjusted so that the thrust plate (3) is within the preset position range between the two hydrodynamic bearings (5); During the shutdown phase, the coil (8) is energized to detect the position of the thrust plate (3); If it is detected that the thrust plate (3) is not within the preset position range, the magnitude of the current passed through the coil (8) is adjusted so that the thrust plate (3) is within the preset position range between the two hydrodynamic bearings (5) until the shaft (1) stops rotating; The control method further comprises: During the operation phase, the coil (8) is energized to detect whether the axial force applied to the hydrodynamic bearing (5) is within a preset pressure range; If it is detected that the axial force applied to the hydrodynamic bearing (5) exceeds or does not reach the preset pressure range, the magnitude of the current passed through the coil (8) is adjusted so that the axial force applied to the hydrodynamic bearing (5) is within the preset pressure range.

2. The control method of the hybrid bearing device according to claim 1, characterized in that: The outer diameter of the dynamic pressure bearing (5) is smaller than the outer diameter of the skeleton groove (6).

3. The control method of the hybrid bearing device according to claim 1, characterized in that: The coil frame (7) is provided with a wire groove (9), the wire groove (9) is opened on the outer peripheral surface of the coil frame (7) and extends in the radial direction of the coil frame (7), and the coil (8) is arranged in the wire groove (9).

4. The control method of the hybrid bearing device according to claim 1, characterized in that: The coil skeleton (7) is also provided with a skeleton fixing portion (10), and the skeleton fixing portion (10) is configured to fix the coil skeleton (7) on the first bearing core (2) or the second bearing core (4).

5. The control method of the hybrid bearing device according to claim 4, characterized in that: The frame fixing portion (10) protrudes in the depth direction of the frame groove (6); the end surfaces of the first bearing core (2) and the second bearing core (4) away from the thrust plate (3) are provided with through holes (11); the through holes (11) correspond to the positions of the frame fixing portion (10); screws are inserted into the through holes (11); the screws are spirally connected to the frame fixing portion (10) to fix the frame fixing portion (10) to the first bearing core (2) or the second bearing core (4).

6. The control method of the hybrid bearing device according to any one of claims 1 to 5, characterized in that: A stress sensor (12) is provided between the hydrodynamic bearing (5) and the thrust plate (3), and the stress sensor (12) is configured to detect changes in the axial force between the thrust plate (3) and the hydrodynamic bearing (5) and output an electrical signal.

7. The control method of the hybrid bearing device according to claim 6, characterized in that: The stress sensor (12) is connected to a proportional amplifier (13), and the electrical signal output by the stress sensor (12) is passed through the proportional amplifier (13) and then into the coil (8).

8. A centrifugal compressor, characterized in that: A control method for a hybrid bearing device according to any one of claims 1 to 7.

Images