A parallel bearing

Abstract

The present invention discloses a parallel bearing, comprising a rotating shaft bearing and a stator bearing; the rotating shaft bearing is a contact bearing; the stator bearing is a non-contact bearing, the stator bearing is sleeved on the rotating shaft bearing, and a gap is left between the inner wall of the stator bearing and the outer wall of the rotating shaft bearing. The parallel bearing of the present invention has low cost, the relative rotational speed of each stage of bearing is reduced, and the dependence on lubricating oil is low.

Description

Technical Field

[0001] The present invention relates to the technical field of bearings, and particularly relates to a parallel bearing. Background Art

[0002] The DN value is a reference value for selecting lubricating oil for rolling bearings. Among them, D is the bearing diameter and N is the relative rotational speed of the inner and outer rings of the bearing. Bearings with a high DN value have relatively high requirements for the adhesion, service life, and operating temperature of grease or lubricating oil, and the prices of such grease or lubricating oil are usually relatively high.

[0003] Theoretically speaking, the thicker the shaft diameter of the rotating shaft, the greater the load it can bear and the greater the critical speed it can withstand. However, this will increase the DN value of the bearing that mates with it, and higher-performance lubricating oil is required. Otherwise, faults such as bearing wear and shaft jamming will occur.

[0004] To solve the problem of bearing wear, a patent with the application number 201480053353.6 and the name "Bearing Device for Turbocharger and Manufacturing Method of Bearing Device for Turbocharger" provides a bearing device. This device nests a cylinder equivalent to an oil film bearing outside the ball bearing. However, the inner wall of this cylinder is fixed to the outer ring of the ball bearing, and there is relative rotation between the outer wall and the stator. It is equivalent to adding a protective sleeve outside the ball bearing, but it does not change the relative rotational speed of the bearing, and still requires high-performance grease or lubricating oil.

[0005] For non-contact bearings, such as radial air bearings, they rely on compressed air between the shaft and the inner ring of the bearing to achieve the supporting function. Usually, a rubber ring is installed between the outer diameter of the bearing and the bearing housing, and the bearing is fixed by relying on the frictional force between the rubber ring and the outer diameter of the bearing to prevent its circumferential rotation. However, in the actual operation process of the air bearing, when the rotational speed of the rotating shaft reaches about 100,000 revolutions per minute or more, there will be air friction between the compressed air film and the rotating shaft, and this friction also increases with the increase of the rotational speed of the rotating shaft. The torque generated by this frictional force makes the air bearing rotate more obviously and frequently with the rotating shaft. And with the further increase of the rotational speed of the rotating shaft or the increase of the shaft diameter of the rotating shaft, the frictional force between the air film and the inner diameter of the radial air bearing further increases, the rotational speed of the radial air bearing relative to the bearing housing increases, and the rubber ring is easily worn and damaged. Summary of the Invention

[0006] In order to overcome the above-mentioned defects of the prior art, the present invention provides a parallel bearing, which can solve the technical problems that existing contact bearings have a high dependence on lubricants and existing non-contact bearings have too large frictional forces with high-speed rotating shafts.

[0007] The definition of the parallel bearing involved in the present invention is as follows: It includes at least two bearings with different diameters, and the bearings are nested in sequence from outside to inside or from inside to outside. When working, the axes of the bearings in the parallel bearing are parallel to each other, and all or part of the bearings are nested with each other.

[0008] In order to achieve the above object, the present invention adopts the following technical solutions.

[0009] A parallel bearing includes a rotating shaft bearing and a stator bearing; the rotating shaft bearing is a contact bearing; the stator bearing is a non-contact bearing, the stator bearing is sleeved on the rotating shaft bearing, and there is a gap between the inner wall of the stator bearing and the outer wall of the rotating shaft bearing.

[0010] The rotating shaft bearing is sleeved on the rotating shaft and is in tight fit with the rotating shaft, and the stator bearing is fixed on the stator; the stator is fixed and the rotating shaft is driven to rotate by a driving device, or the rotating shaft is fixed and the stator is driven to rotate by a driving device.

[0011] The driving device is a motor.

[0012] The rotating shaft bearing is a ball bearing, and the stator bearing is an air bearing.

[0013] The air bearing is in a ring-shaped cylindrical shape, and at least one annular groove is provided on its outer wall parallel to the end face. A damper is nested in the annular groove. The damper is an annular rubber ring, and the top of the rubber ring protrudes from the outer wall of the air bearing.

[0014] A plurality of convex blocks are arranged in a circumferential and evenly distributed manner along the axial direction on the annular end face of the air bearing. An anti-rotation end cover is arranged at one end of the air bearing where the convex blocks are provided. Anti-rotation holes are correspondingly arranged on the anti-rotation end cover for the convex blocks. The convex blocks are embedded in the anti-rotation holes, and the anti-rotation end cover is fixed on the stator end face by screws.

[0015] A cross-shaped hole is arranged on the anti-rotation end cover, including four anti-rotation holes that are perpendicularly connected to each other. The convex blocks are correspondingly arranged in four. Each of the convex blocks is respectively embedded in each of the anti-rotation holes. A screw hole is arranged between two adjacent anti-rotation holes. A screw hole one is arranged on the stator end face. After the screw hole is aligned with the screw hole one, they are fastened with screws.

[0016] The rotating shaft bearing is a pair of angular contact ball bearings arranged oppositely, and a preload spring is arranged between the outer rings of the two angular contact ball bearings; both ends of the preload spring are respectively fixed at the ends of the outer rings of the two angular contact ball bearings.

[0017] The parallel bearing further includes at least one intermediate bearing. The intermediate bearing is a contact bearing. The intermediate bearing is sleeved between the rotating shaft bearing and the stator bearing, and there is a gap between the stator bearing and the intermediate bearing.

[0018] The intermediate bearing is a ball bearing.

[0019] The surface of the shaft section of the rotating shaft sleeved in the rotating shaft bearing is coated with a polytetrafluoroethylene anti-wear coating.

[0020] The stator bearing is fixed to the stator by one of key connection, pin connection, dowel connection, and bolt connection.

[0021] The rotating shaft bearing is a ball bearing, a roller bearing, a ceramic bearing, or a polytetrafluoroethylene bearing.

[0022] The ball bearing, roller bearing, ceramic bearing, or polytetrafluoroethylene bearing is single-row, double-row, or multi-row.

[0023] The ball bearing, roller bearing, ceramic bearing, or polytetrafluoroethylene bearing is single-layer, double-layer, or multi-layer.

[0024] The stator bearing is an air bearing, an oil film floating ring bearing, or a tilting pad bearing.

[0025] The parallel bearing of the present invention can be used in a rotor system, which includes two identical parallel bearings as described above, and the parallel bearings are sleeved on the rotating shaft in pairs.

[0026] A turbine is sleeved on the rotating shaft of the rotor system.

[0027] At least one thrust disk integrally formed with or fixed to the rotating shaft is provided on the rotating shaft, and a thrust bearing is provided on the thrust disk.

[0028] The thrust disk and the thrust bearing are arranged on the left side and / or the right side of a pair of parallel bearings.

[0029] The end face of the thrust disk in contact with the thrust bearing is coated with a polytetrafluoroethylene anti-wear coating.

[0030] An electric motor assembly is arranged in the middle, on the left side, or on the right side of a pair of parallel bearings; the electric motor assembly includes a stator magnetic pole and a coil sleeved on the rotating shaft, and a magnetic core is arranged on the shaft section of the rotating shaft located inside the stator magnetic pole and the coil.

[0031] The above rotor system of the present invention can be used in a gas turbine generator set.

[0032] The beneficial effects of the present invention are as follows:

[0033] (1) The parallel bearing of the present invention has low cost, the relative rotational speed of each stage of the bearing in the parallel bearing is reduced, it is not limited by the theoretical DN value, and it has low dependence on lubricating oil.

[0034] (2) In the prior art, an air film exists between the rotating shaft and the air bearing. As the rotational speed of the rotating shaft further increases or the shaft diameter of the rotating shaft increases, the frictional force further increases. After adopting the parallel bearing of the present invention, the air film exists between the outer ring of the ball bearing and the air bearing. Since the rotational speed of the outer ring of the ball bearing is relatively small, the relative rotational speed between the air film and the air bearing is relatively small, the frictional force is small, and the rotational speed relative to the bearing housing is also small. Therefore, the rubber ring between the air bearing and the bearing housing is not easily worn, and the service life is long.

[0035] (3) The rotational speeds of multiple parallel bearings on the same rotating shaft can be adaptively adjusted, without the need for manual setting or adjustment of the rotational speed, and the effect of synchronous rotation can be achieved.

[0036] (4) It can not only be used for low rotational speeds, but also be applicable to high rotational speed working conditions, and can be used for rotors with rotational speeds ranging from tens of thousands to hundreds of thousands of revolutions per minute. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 is a schematic diagram of the parallel bearing structure of Embodiment 1 of the present invention.

[0038] Figure 2 is a schematic diagram of the parallel bearing structure of Embodiment 2 of the present invention.

[0039] Figure 3 is a schematic diagram of the parallel bearing structure of Embodiment 3 of the present invention.

[0040] Figure 4 is a schematic diagram of the parallel bearing structure of Embodiment 4 of the present invention.

[0041] Figure 5 is a schematic diagram of the structure in which the parallel bearings of the present invention are arranged at both ends of the shaft.

[0042] Figure 6 is a schematic diagram of a fixing method of the parallel bearing of the present invention.

[0043] Figure 7 is a side view of the parallel bearing with bumps of the present invention.

[0044] Figure 8 is a schematic diagram of the structure of the anti-rotation end cover of the present invention.

[0045] Figure 9 is a side view of the air bearing with bumps of the present invention.

[0046] Figure 10 is a graph showing the relationship between the frictional torque of the air bearing of the present invention and time.

[0047] Figure 11 is a graph showing the relationship between the frictional torque of the ball bearing of the present invention and time.

[0048] Figures 12 - 19 It is a schematic layout diagram of the rotor system with parallel bearings of the present invention.

[0049] Figure 20 It is a schematic structural diagram of a gas turbine with parallel bearings of the present invention.

[0050] Reference numerals in the drawings: 1 - shaft bearing, 2 - stator bearing, 21 - rubber ring, 22 - convex block, 4 - stator, 41 - screw hole 1, 5 - anti-rotation end cover, 51 - anti-rotation hole, 52 - screw hole, 6 - intermediate bearing, 100 - shaft, 101 - magnetic core, 200 - thrust bearing, 210 - thrust disk, 300 - first parallel bearing, 400 - motor assembly, 500 - second parallel bearing, 600 - compressor, 700 - turbine. Detailed implementation manners

[0051] Next, the technical solutions of the present invention will be described clearly and completely in conjunction with the accompanying drawings. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all of the embodiments.

[0052] A parallel bearing provided by the present invention is used to be installed on the shaft 100 to radially support the shaft 100.

[0053] A parallel bearing includes a shaft bearing 1 and a stator bearing 2; the shaft bearing 1 is a contact bearing; the stator bearing 2 is a non-contact bearing, the stator bearing 2 is sleeved on the shaft bearing 1, and there is a gap between the inner wall of the stator bearing 2 and the outer wall of the shaft bearing 1.

[0054] The shaft bearing 1 is sleeved on the shaft 100 and is in tight fit with the shaft 100, and the stator bearing 2 is fixed to the stator 4; the stator 4 is fixed and the shaft 100 is driven to rotate by a driving device, or the shaft 100 is fixed and the stator 4 is driven to rotate by a driving device.

[0055] The driving device is a motor.

[0056] Embodiment 1

[0057] The shaft bearing 1 is a ball bearing, and the stator bearing 2 is an air bearing.

[0058] Refer to Figure 1 , in this embodiment, the parallel bearing includes a shaft bearing 1 and a stator bearing 2. The shaft bearing 1 is sleeved on the shaft 100, and the stator bearing 2 is sleeved outside the shaft bearing 1 and keeps a certain gap from the outer wall of the shaft bearing 1.

[0059] The air bearing is in a ring-shaped cylinder form, and at least one annular groove is arranged on its outer wall parallel to the end face. A damper is nested in the annular groove. The damper is an annular rubber ring 21, and the top of the rubber ring 21 protrudes from the outer wall of the air bearing.

[0060] See Figure 6 , 7 , 8, 9. A plurality of bumps 22 are arranged on the annular end face of the air bearing in an axially surrounding and evenly distributed manner. An anti-rotation end cover 5 is arranged at one end of the air bearing where the bumps 22 are provided. Anti-rotation holes 51 are arranged on the anti-rotation end cover 5 corresponding to the bumps 22. The bumps 22 are embedded in the anti-rotation holes 51, and the anti-rotation end cover 5 is fixed on the end face of the stator 4 by screws.

[0061] Further, a cross-shaped hole is arranged on the anti-rotation end cover 5, including four anti-rotation holes 51 that are perpendicularly connected to each other. The bumps 22 are correspondingly arranged as four, and each bump 22 is respectively embedded in each anti-rotation hole 51. A screw hole 52 is arranged between adjacent two anti-rotation holes 51. A screw hole one 41 is arranged on the end face of the stator 4. After the screw hole 52 and the screw hole one 41 are aligned, they are fastened with screws.

[0062] Embodiment 2

[0063] See Figure 2 . The parallel bearing further includes at least one intermediate bearing 6. The intermediate bearing 6 is a contact bearing. The intermediate bearing 6 is sleeved between the rotating shaft bearing 1 and the stator bearing 2, and there is a gap between the stator bearing 2 and the intermediate bearing 6.

[0064] The intermediate bearing 6 is a ball bearing.

[0065] Specifically, the parallel bearing includes a rotating shaft bearing 1, a stator bearing 2, and an intermediate bearing 6.

[0066] Based on Embodiment 1, in this embodiment, an intermediate bearing 6 (or multiple intermediate bearings 6 are sequentially sleeved outside and coaxial with each other) is sleeved on the rotating shaft bearing 1, and the stator bearing 2 is sleeved outside the outermost intermediate bearing 6 and keeps a certain gap from the outer wall of the outermost intermediate bearing 6.

[0067] Embodiment 3

[0068] Further, the ball bearing, roller bearing, ceramic bearing, or polytetrafluoroethylene bearing is single-layer, double-layer, or multi-layer. The ball bearing or roller bearing of the rotating shaft bearing 1 in Embodiment 1 and Embodiment 2 of the present invention can be an integral multi-layer bearing, and the ball layer or roller layer is arranged in multiple layers. See Figure 3 . The multi-layer ball bearing or roller bearing includes an inner ring, an intermediate ring, and an outer ring that are nested with each other. Ball bearings or roller bearings are respectively embedded between the inner ring and the intermediate ring, and between the intermediate ring and the outer ring.

[0069] Example 4

[0070] When the rotary shaft bearing 1 of the present invention is a angular contact ball bearing, since the inner ring of the bearing is fixed on the rotary shaft 100, relative displacement will occur between the outer ring, the cage and the balls. Generally speaking, it means that the balls inside the bearing are too loose and appropriate treatment measures need to be taken.

[0071] See Figure 4 , the rotary shaft bearing 1 is a pair of angular contact ball bearings arranged oppositely, and a preload spring is arranged between the outer rings of the two angular contact ball bearings; both ends of the preload spring are respectively fixed at the ends of the outer rings of the two angular contact ball bearings.

[0072] By adjusting the preload of the spring, the balls and the cage can be made to approach or separate, that is, the internal friction of the bearing can be increased or decreased, so as to achieve the purpose of the friction force applicable to the required working conditions.

[0073] Further, the surface of the shaft section of the rotary shaft 100 sleeved in the rotary shaft bearing is coated with a polytetrafluoroethylene anti-wear coating.

[0074] Further, the stator bearing 2 is fixed to the stator 4 by one of key connection, pin connection, dowel connection, and bolt connection.

[0075] Further, the rotary shaft bearing 1 is a ball bearing, a roller bearing, a ceramic bearing or a polytetrafluoroethylene bearing.

[0076] Further, the stator bearing 2 is an air bearing, an oil film floating ring bearing or a tilting pad bearing.

[0077] Further, the ball bearing, roller bearing, ceramic bearing or polytetrafluoroethylene bearing is single row, double row or multi row.

[0078] The starting process of the parallel bearings of the present invention is as follows:

[0079] When the rotary shaft 100 starts, the rotary shaft bearing 1 sleeved outside the rotary shaft 100 contacts the bottom of the stator bearing 2. As the rotary shaft 100 rotates, it drives the inner ring of the rotary shaft bearing 1 to rotate. At the same time, the stator bearing 2 and the outer ring of the rotary shaft bearing 1 are gradually separated due to the air film or oil film action. The rotary shaft bearing 1 rotates eccentrically in the stator bearing 2. When the rotary shaft 100 runs stably at high speed, the rotary shaft 100 and the rotary shaft bearing 1 are coaxial and rotate eccentrically around a circle in the stator bearing 2. At the same time, the outer ring of the rotary shaft bearing 1 rotates self.

[0080] Further, see Figure 1 , the present invention uses a ball bearing as the rotary shaft bearing 1 and an air bearing as the stator bearing 2. The following is the description of the working principle:

[0081] When the shaft diameter is fixed, for a traditional ball bearing, when the rotating shaft 100 rotates, assuming the inner ring speed of the ball bearing is V2 and the outer ring speed is V0, since the outer ring is fixed on the stator 4, V0 is approximately 0. Therefore, the relative speed n of the outer ring of the ball bearing is n = V2 - V0.

[0082] After adopting the parallel bearings of the present invention, when the rotating shaft 100 rotates, assuming the inner ring speed of the ball bearing is V2, the outer ring speed is V1, and the air bearing speed is V0. The air bearing is fixed on the stator 4, V0 is approximately 0. The speed difference a between the outer ring and the inner ring of the ball bearing is a = V2 - V1, and the speed difference b relative to the air bearing is b = V1 - V0. Both a and b are less than n. It can be seen that the relative speed of the inner and outer rings of the rolling bearing is reduced. That is, under the same conditions, the actual DN value is reduced, and the use of ordinary grease can meet the requirements.

[0083] By analogy, no matter how many ball bearings are successively sleeved in parallel on the rotating shaft bearing 1, the actual DN value will not become too large, and the decoupling between the shaft diameter D and the bearing speed N has been achieved. Therefore, the parallel bearings of the present invention are applicable to the working conditions of large shaft diameters and high speeds. Moreover, the damping and stiffness of the parallel bearings of the present invention are not lower than those of a single bearing. Specifically, the damping of the parallel bearing = the damping of the air bearing + the damping of each bearing rubber ring; the stiffness of the parallel bearing = the stiffness of the air bearing.

[0084] In specific applications, the parallel bearings of the present invention can be arranged in pairs on the rotating shaft 100. Refer to Figure 5 , when the rotating shaft 100 rotates, it drives the inner ring of the rotating shaft bearing 1 to rotate, and the outer ring of the rotating shaft bearing 1 or the outer ring of the outermost intermediate bearing 6 rotates under the action of the air bearing or the oil film floating ring bearing. Moreover, the speeds of multiple parallel bearings on the same rotating shaft will be adaptively adjusted according to the force to achieve the effect of synchronous rotation.

[0085] Refer to Figures 12 - 19 , the rotor system includes two identical parallel bearings, and the parallel bearings are sleeved in pairs on the rotating shaft 100.

[0086] Refer to Figures 13 - 15 , at least one thrust disk 210 integrally formed or fixed with the rotating shaft 100 is provided on the rotating shaft 100, and a thrust bearing 200 is provided on the thrust disk 210.

[0087] The thrust disk 210 and the thrust bearing 200 are provided on the left side and / or the right side of a pair of parallel bearings.

[0088] Refer to Figures 16 - 19 , a turbine 700 is sleeved on the rotating shaft 100 of the rotor system.

[0089] A motor assembly 400 is arranged in the middle, on the left side or on the right side of the pair of parallel bearings; the motor assembly 400 includes a stator magnetic pole and a coil sleeved on the rotating shaft 100, and a magnetic core 101 is arranged on the shaft section of the rotating shaft 100 located inside the stator magnetic pole and the coil.

[0090] In the above rotor system, the thrust bearing 200 is a non-contact bearing.

[0091] Furthermore, the thrust bearing 200 is a gas bearing, which can specifically be any one of a hydrodynamic bearing, a hydrostatic bearing or a hybrid hydrodynamic and hydrostatic bearing.

[0092] The rotor system of the present invention includes but is not limited to the above distribution cases.

[0093] Taking the rolling bearing for the rotating shaft bearing 1 and the air bearing for the stator bearing 2 as an example, the working process of the rotor system provided by the present invention is as follows:

[0094] (1) Start the starting device of the rotating shaft 100 to rotate the rotating shaft 100 to an initial predetermined speed; the inner ring of the rolling bearing is driven by the rotating shaft 100 and rotates synchronously with the rotating shaft 100;

[0095] (2) After the rotational speed of the rotating shaft 100 accelerates to the working speed, the outer ring of the rolling bearing starts to rotate under the action of the balls, and vortices appear in the air between the outer ring of the rolling bearing and the inner wall of the air bearing. When the outer ring of the rolling bearing rotates to a certain speed, the air film gradually stabilizes, and the rolling bearing is separated from the inner ring of the air bearing.

[0096] The following further explains its working principle in combination with the relationship diagram of frictional torque and time. See Figure 10 、 11 :

[0097] (1) In the time period from 0 to t1, that is, when the rotating shaft 100 just starts, the inner ring of the rolling bearing rotates while the outer ring has not rotated yet, the linear speed of the outer ring of the rolling bearing is 0, and due to the influence of the rotation of the balls, the frictional torque of the outer ring of the rolling bearing increases; the air bearing is not stressed at this time, so the frictional torque is 0, and before the moment t1, the air bearing is in contact with the outer ring of the rolling bearing.

[0098] (2) In the time period from t1 to t2, that is, before the rotating shaft 100 gradually rotates to a stable operation, due to the influence of the rotation of the balls, the frictional torque of its outer ring increases, and the outer ring of the balls gradually rotates but does not take off; the frictional torque between the air bearing and the rolling bearing gradually increases until the critical point;

[0099] (3) At time t2, the frictional torque between the air bearing and the ball bearing reaches the critical point, and the frictional torques borne by both reach the critical values. The outer ring of the ball bearing and the air bearing start to rotate relative to each other and gradually separate. The air film between the outer ring of the ball bearing and the inner wall of the air bearing gradually stabilizes. The frictional torque of the ball bearing decreases slightly and then slowly increases as the rotational speed rises. At the same time, the air bearing takes off, and the frictional torque of the air bearing also instantaneously decreases and then slowly increases as the rotational speed rises.

[0100] The present invention also provides a gas turbine generator set having the above rotor system described in the present invention. Refer to Figure 20 , the gas turbine generator set includes a rotating shaft 100, a turbine 700, a compressor 600, a motor 400, a first parallel bearing 300, a second parallel bearing 500, and a thrust bearing 200. The rotating shaft 100 passes through the thrust bearing 200, the first parallel bearing 300, the motor 400, the second parallel bearing 500, the compressor 600, and the turbine 700 arranged in sequence. The rotating shaft 100 rotates within the thrust bearing 200, the first parallel bearing 300, the motor assembly 400, and the second parallel bearing 500. The rotating shaft 100 is fixedly connected to the thrust disk 210 of the thrust bearing 200, the turbine 700, and the compressor 600.

[0101] The first parallel bearing 300 and the second parallel bearing 500 in the above gas turbine generator set use the parallel bearing of the present invention.

[0102] The application of the parallel bearing of the present invention is not limited to the occasions described in the present invention. It is easy for those skilled in the art to think of applying it to any high-speed rotation occasion. The embodiments described in the specification of the present invention are only examples for understanding the present invention and do not constitute a limitation on the application occasions of the present invention.

[0103] Although the specific embodiments of the present invention are described above in conjunction with the drawings, it is not a limitation on the protection scope of the present invention. Those skilled in the art should understand that various modifications or deformations that can be made without creative labor on the basis of the technical solution of the present invention are still within the protection scope of the present invention.

Claims

1. A parallel bearing, characterized in that, it includes a rotating shaft bearing and a stator bearing; the rotating shaft bearing is a contact bearing; the stator bearing is a non-contact bearing, the stator bearing is sleeved on the rotating shaft bearing, and there is a gap between the inner wall of the stator bearing and the outer wall of the rotating shaft bearing; the rotating shaft bearing is sleeved on the rotating shaft and is tightly fitted with the rotating shaft, and the stator bearing is fixed on the stator; the stator is fixed and the rotating shaft is driven to rotate by a driving device, or the rotating shaft is fixed and the stator is driven to rotate by a driving device; the driving device is a motor; the rotating shaft bearing is a ball bearing, and the stator bearing is an air bearing; the air bearing is in a ring-shaped cylindrical shape, and at least one annular groove is arranged parallel to the end face on its outer wall. A damper is nested in the annular groove. The damper is an annular rubber ring, and the top of the rubber ring protrudes from the outer wall of the air bearing; a plurality of bumps are arranged in a circumferential and evenly distributed manner along the axial direction on the annular end face of the air bearing. An anti-rotation end cover is arranged at one end of the air bearing where the bumps are provided. Anti-rotation holes are provided on the anti-rotation end cover corresponding to the bumps. The bumps are embedded in the anti-rotation holes, and the anti-rotation end cover is fixed on the stator end face by screws; a cross-shaped hole is arranged on the anti-rotation end cover, including four anti-rotation holes that are perpendicularly communicated with each other. The bumps are correspondingly arranged in four. Each of the bumps is respectively embedded in each of the anti-rotation holes. A screw hole is arranged between two adjacent anti-rotation holes. A screw hole one is arranged on the stator end face. After the screw hole is aligned with the screw hole one, they are fastened with screws; the rotating shaft bearing is a pair of angular contact ball bearings arranged oppositely, and a preload spring is arranged between the outer rings of the two angular contact ball bearings; both ends of the preload spring are respectively fixed at the ends of the outer rings of the two angular contact ball bearings; the parallel bearing further includes at least one intermediate bearing. The intermediate bearing is a contact bearing. The intermediate bearing is sleeved between the rotating shaft bearing and the stator bearing, and there is a gap between the stator bearing and the intermediate bearing; the intermediate bearing is a ball bearing; a polytetrafluoroethylene anti-wear coating is coated on the surface of the shaft section of the rotating shaft sleeved in the rotating shaft bearing; the way of fixing the stator bearing on the stator is one of key connection, pin connection, dowel connection, and bolt connection; the rotating shaft bearing is a ball bearing, a roller bearing, a ceramic bearing or a polytetrafluoroethylene bearing; the ball bearing, roller bearing, ceramic bearing or polytetrafluoroethylene bearing is single-row or multi-row; the ball bearing, roller bearing, ceramic bearing or polytetrafluoroethylene bearing is single-layer or multi-layer; the stator bearing is an air bearing, an oil film floating ring bearing or a tilting pad bearing.

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