Radial hydrodynamic bearing, centrifugal compressor, and control method

Abstract

A radial hydrodynamic bearing, a centrifugal compressor, and a control method. The radial hydrodynamic bearing comprises: a bearing seat (11); a bump foil (12) and a top foil (13); and a protective ring (14), the protective ring (14) being provided on one end of the bearing seat (11) in the axial direction, wherein in a same radial direction, the difference between the radial gap between the protective ring (14) and a rotor and the radial gap between the top foil (13) and the rotor is smaller than the thickness of the top foil (13).

Description

Radial dynamic pressure bearing, centrifugal compressor and control method

[0001] Cross-reference to related applications

[0002] The present application claims priority to the Chinese patent application No. 202410847342.0, filed on June 27, 2024, and entitled “Radial dynamic pressure bearing, centrifugal compressor and control method”, the entire content of which is incorporated herein by reference. TECHNICAL FIELD

[0003] The present application relates to the technical field of centrifugal compressor bearing, in particular to a radial dynamic pressure bearing, a centrifugal compressor and a control method. BACKGROUND

[0004] Gas dynamic pressure bearing is a form of sliding bearing, which has similar structure and working principle to liquid sliding bearing, but uses gas (mostly air) as lubricating medium, has extremely low friction, does not need lubricating liquid, has a wide range of use speed and temperature, and is widely used in high-speed rotating machinery field, for example, used in cooperation with the rotor in the centrifugal compressor. Foil gas dynamic pressure bearing is a kind of gas dynamic pressure bearing, due to its complex structural characteristics and working environment, foil gas dynamic pressure bearing has the problem of easy failure.

[0005] SUMMARY

[0006] The following is a summary of the subject matter of the detailed description herein. This summary is not intended to limit the scope of the claims.

[0007] One purpose of the present application is to provide a radial dynamic pressure bearing which can protect the top foil, wave foil and the like well and can identify in advance whether the top foil needs to be replaced.

[0008] Another purpose of the present application is to provide a centrifugal compressor having the above-mentioned radial dynamic pressure bearing.

[0009] Still another purpose of the present application is to provide a control method.

[0010] A radial dynamic pressure bearing is arranged on a rotor, and the radial dynamic pressure bearing comprises a bearing seat, a wave foil, a top foil and a protective ring, the wave foil is located between the top foil and the bearing seat and elastically pushes against the top foil, the protective ring is arranged at one axial end of the bearing seat, and in the same radial direction, the radial gap between the protective ring and the rotor minus the radial gap between the top foil and the rotor is less than the thickness of the top foil.

[0011] According to the radial dynamic pressure bearing of the embodiment of the present application, by setting the protection ring, and limiting the radial gap between the protection ring and the rotor, the radial gap between the top foil and the rotor, and the thickness size relationship of the top foil, the top foil, the wave foil and the like can be well protected when the rotor is impacted by instability, the reliability and the service life of the top foil and the wave foil can be improved, and the working stability of the rotor can be improved. Moreover, whether the top foil needs to be replaced can be identified in advance, and the radial dynamic pressure bearing with a life close to the end can be determined in time, so that the customer can predict and replace the radial dynamic pressure bearing in advance, and the downtime and the maintenance cost can be reduced.

[0012] According to some embodiments of the present application, the radial dynamic pressure bearing further comprises a lead wire bundle, one end of the lead wire bundle is connected with the protection ring, the lead wire bundle is wrapped with an insulating layer, the other end of the lead wire bundle is led out and formed into a detection circuit, and the detection circuit is adapted to be turned on when the rotor presses against the protection ring.

[0013] According to some embodiments of the present application, the protection ring is configured as a graphite ring.

[0014] According to some embodiments of the present application, a first potting layer is arranged between the protection ring and the bearing seat to provide buffer protection.

[0015] According to some embodiments of the present application, a first limiting portion is arranged on one side of the first potting layer facing the protection ring, and the protection ring has a second limiting portion matched with the first limiting portion in concave-convex.

[0016] According to some embodiments of the present application, when the top foil is in an extreme compression state or after wear, the radial gap between the protection ring and the rotor is less than or equal to the radial gap between the top foil and the rotor.

[0017] A centrifugal compressor comprises a shell, a stator, a rotor and a radial dynamic pressure bearing, the shell has a radial bearing chamber; the stator and the rotor are arranged in the shell; the radial dynamic pressure bearing is configured as the radial dynamic pressure bearing of any one of the above embodiments, the radial dynamic pressure bearing is arranged in the radial bearing chamber, and the top foil and the rotor are arranged opposite in the radial direction.

[0018] According to some embodiments of the present application, the centrifugal compressor further comprises an impeller arranged on the rotor, the shell further comprises a wheel cover, a wheel cover seal is arranged between the impeller and the wheel cover, a wheel back seal is arranged between the impeller and the radial bearing chamber, the radial gap between the protection ring and the rotor is less than the radial gap between the wheel cover seal and the impeller, and the radial gap between the protection ring and the rotor is also less than the radial gap between the wheel back seal and the rotor.

[0019] According to some embodiments of the present application, a second potting layer is arranged between the radial bearing chamber and the guard ring, and the second potting layer is integrally potted with the first potting layer.

[0020] According to some embodiments of the present application, a first positioning part is arranged on the side of the radial bearing chamber facing the guard ring, and the first potting layer is correspondingly arranged with a second positioning part matching the first positioning part.

[0021] According to some embodiments of the present application, the guard ring is arranged at the end of the bearing seat adjacent to the stator.

[0022] According to some embodiments of the present application, the rotor comprises a primary rotor and a secondary rotor, the radial bearing chamber comprises a primary bearing chamber corresponding to the primary rotor and a secondary bearing chamber corresponding to the secondary rotor, a primary bearing is arranged in the primary bearing chamber, and a secondary bearing is arranged in the secondary bearing chamber, at least one of the primary bearing and the secondary bearing is configured as the radial dynamic pressure bearing.

[0023] According to some embodiments of the present application, the primary bearing and the secondary bearing are both configured as the radial dynamic pressure bearing, and the centrifugal compressor further comprises a detection module having a detection circuit, the detection circuit comprises a first loop, a second loop and a third loop, the first loop is a loop formed by connecting the lead wire bundle of the primary bearing to the shell, the second loop is a loop formed by connecting the lead wire bundle of the secondary bearing to the shell, the third loop is a loop formed by connecting the lead wire bundles of the primary bearing and the secondary bearing, and the detection module issues an alarm when any loop is conducted.

[0024] A control method comprises: acquiring whether a first loop, a second loop and a third loop are conducted, the first loop is a loop formed by connecting the lead wire bundle of a primary bearing to a shell, the second loop is a loop formed by connecting the lead wire bundle of a secondary bearing to the shell, and the third loop is a loop formed by connecting the lead wire bundles of the primary bearing and the secondary bearing; if the first loop is conducted, a primary bearing damage alarm is reported; if the second loop is conducted, a secondary bearing damage alarm is reported; and if the third loop is conducted, a primary bearing and secondary bearing damage alarm is reported.

[0025] According to some embodiments of the present application, the control method further comprises: confirming whether the centrifugal compressor needs to be urgently started; if yes, inputting an emergency start number threshold; wherein the emergency start number threshold is set according to the field environment; and if no, replacing the bearings and performing maintenance.

[0026] According to some embodiments of the present application, the control method further comprises: if none of the first circuit, the second circuit and the third circuit is turned on, increasing the output frequency of the frequency converter to above the bearing working speed; obtaining the number of turned on circuits of the first circuit, the second circuit and the third circuit; if the number of turned on circuits is zero, running normally and continuously obtaining the number of turned on circuits of the first circuit, the second circuit and the third circuit; if the number of turned on circuits is greater than or equal to 1, obtaining the running speed of the centrifugal compressor.

[0027] According to some embodiments of the present application, the control method further comprises: if the running speed is less than the maximum speed, increasing the running speed by an increase threshold, and after a time threshold, obtaining again the number of turned on circuits of the first circuit, the second circuit and the third circuit, wherein the increase threshold is 2 Hz and the time threshold is 30 s; if the running speed is greater than or equal to the maximum speed, stopping protection.

[0028] Additional aspects and advantages of the present application will be in part apparent and in part pointed out hereinafter. BRIEF DESCRIPTION OF DRAWINGS

[0029] Fig. 1 is a schematic view of a centrifugal compressor according to some embodiments of the present application;

[0030] Fig. 2 is a cross-sectional view of A-A in Fig. 1;

[0031] Fig. 3 is an enlarged view of B in Fig. 2;

[0032] Fig. 4 is a schematic view of a radial dynamic pressure bearing according to some embodiments of the present application;

[0033] Fig. 5 is a cross-sectional view of C-C in Fig. 4;

[0034] Fig. 6 is a flow chart of a control method according to some embodiments of the present application. DETAILED DESCRIPTION

[0035] Embodiments of the present application are described in detail below with reference to the accompanying drawings, in which like or similar elements are denoted by the same or similar reference signs, and examples of the embodiments are described below by referring to the accompanying drawings, which are intended to explain the present application, and cannot be understood as a limitation of the present application.

[0036] A radial dynamic pressure bearing 1, a centrifugal compressor 2 and a control method according to embodiments of the present application are described below with reference to Figs. 1-6.

[0037] As shown in FIG. 4 and FIG. 5, the radial dynamic pressure bearing 1 according to the first aspect of the present application is arranged on a rotor, and the radial dynamic pressure bearing 1 comprises: a bearing seat 11, a wave foil 12, a top foil 13, and a protective ring 14.

[0038] The wave foil 12 is located between the top foil 13 and the bearing seat 11 and elastically pushes against the top foil 13; the protective ring 14 is arranged at an axial end of the bearing seat 11; in the same radial direction, the radial gap between the protective ring 14 and the rotor, minus the radial gap between the top foil 13 and the rotor, is less than the thickness of the top foil 13.

[0039] In the present application, the bearing seat 11 can provide mounting positions for some other components (such as the wave foil 12 and the top foil 13) in the radial dynamic pressure bearing 1, and can support, fix, and protect some other components in the radial dynamic pressure bearing 1; the wave foil 12 and the top foil 13 can be arranged on the radial inner side of the bearing seat 11, the top foil 13 is sleeved on the outer periphery of the rotor and is spaced apart from the rotor in the radial direction, supporting the rotor to be radially suspended, the wave foil 12 is arranged between the top foil 13 and the bearing seat 11, the wave foil 12 can have an elastic bellows structure and has good deformation performance, which can improve the carrying capacity and performance stability; the protective ring 14 can be located on the radial inner side of the bearing seat 11, the protective ring 14 is sleeved on the outer periphery of the rotor, and the protective ring 14 can be arranged in sequence with the top foil 13 in the axial direction. It can be understood that the protective ring 14 can be arranged at one end of the bearing seat 11 in the axial direction, but is not limited thereto. In some embodiments, the protective ring 14 can also be arranged in the middle region of the bearing seat 11 in the axial direction, so as to simplify the end assembly environment of the bearing seat 11. The arrangement of the protective ring 14 on the bearing seat 11 in the axial direction can be designed according to specific requirements.

[0040] The present inventors have noticed that in the related art, the radial dynamic pressure bearing 1 for supporting the rotor to be radially suspended will be hit by the rotor when the rotor loses stability due to sudden power failure or strong external impact, forcing the top foil 13 to deform outwardly, extruding the wave foil 12 located on the outer side of the top foil 13, and the wave foil 12 will be deformed greatly or even collapsed due to the impact of the rotor, resulting in failure of the radial dynamic pressure bearing 1.

[0041] For the above phenomenon, the present inventors have found that the position relationship between the top foil 13 and the wave foil 12 can be utilized, the top foil 13 is the component that first contacts the rotor among the top foil 13 and the wave foil 12, and therefore the protective ring 14 for protecting the top foil 13 can be added to avoid continuous deformation or damage of the top foil 13, thereby also protecting the wave foil 12.

[0042] Based on this, the present application further makes the radial gap between the protective ring 14 and the rotor, minus the radial gap between the top foil 13 and the rotor, less than the thickness of the top foil 13.

[0043] The protective ring 14 and the top foil 13 can be arranged in sequence in the axial direction in the application, and the rotor is located in the inner circumferences of the protective ring 14 and the top foil 13. The top foil 13 can have a certain wear after long-term operation, so that the radial gap between the top foil 13 and the rotor becomes longer. By arranging the protective ring 14 and the rotor in the same radial direction, the radial gap between the protective ring 14 and the rotor is subtracted from the radial gap between the top foil 13 and the rotor, which is less than the thickness of the top foil 13. Therefore, when the top foil 13 reaches a certain degree of wear after long-term operation, the protective ring 14 can contact the rotor, so that it can be identified in advance whether the top foil 13 needs to be replaced, and the top foil 13 can be prevented from continuing to wear and being seriously worn or even worn out, so as to ensure the normal and reliable operation of the top foil 13. In addition, when the rotor moves outward in the radial direction due to instability (such as sudden power failure or external impact), the rotor will first contact the protective ring 14, so that the protective ring 14 can play a supporting and buffering role between the rotor and the top foil 13 and the wave foil 12, and can protect the top foil 13 and the wave foil 12 from being deformed beyond the design range, and protect the wave foil 12 outside the top foil 13 from being deformed excessively and losing elasticity due to the impact of the rotor.

[0044] According to the radial dynamic pressure bearing 1 of the application, by arranging the protective ring 14 and limiting the size relationship between the radial gap between the protective ring 14 and the rotor, the radial gap between the top foil 13 and the rotor, and the thickness of the top foil 13, the top foil 13, the wave foil 12, etc. can be well protected when the rotor is impacted due to instability, and the reliability and service life of the top foil 13 and the wave foil 12 can be improved, and the stability of the rotor can be improved. In addition, it can be identified in advance whether the top foil 13 needs to be replaced, and the radial dynamic pressure bearing 1 with a life close to the end can be determined in time, so that the customer can predict and replace the radial dynamic pressure bearing 1 in advance, reduce downtime and maintenance costs.

[0045] As shown in FIG. 5, according to some embodiments of the application, the radial dynamic pressure bearing 1 further comprises a lead wire bundle 15, one end of the lead wire bundle 15 is connected with the protective ring 14, the lead wire bundle 15 is wrapped with an insulating layer 16, and the other end of the lead wire bundle 15 is led out and formed into a detection circuit, and the detection circuit is adapted to be turned on when the rotor presses against the protective ring 14.

[0046] The protective ring 14 can be configured of a material having electrical conductivity. One end of the lead-out wire bundle 15 is connected to the protective ring 14, and the other end is led out and formed into a detection circuit. When the rotor presses against the protective ring 14, the detection circuit is turned on, so that it can be determined whether the radial dynamic pressure bearing 1 is normally running, and the wear condition of the radial dynamic pressure bearing 1 after a long time of running, etc. For example, when sudden power failure, severe working conditions cause the impact foil 13 and the wave foil 12 to deform radially outward to dissipate energy, etc., the rotor can press against the protective ring 14 for a short time, and the detection circuit is turned on for a short time. When the impact foil 13 needs to be maintained and replaced due to severe wear, etc., the rotor can press against the protective ring 14 for a long time and continuously, and the detection circuit is continuously turned on. By arranging the lead-out wire bundle 15 in cooperation with the protective ring 14, the impact foil 13, the wave foil 12 and the protective ring 14 can be monitored and intelligently diagnosed, so as to realize predictive maintenance, avoid affecting use after the radial dynamic pressure bearing 1 is damaged, and improve working reliability and safety.

[0047] It should be noted that a wire bundle channel suitable for accommodating the lead-out wire bundle 15 can be formed in the bearing seat 11, so as to improve stability and working safety of the lead-out wire bundle 15.

[0048] Preferably, the wire bundle channel extends along the radial direction of the bearing seat 11, so that the length of the part of the lead-out wire bundle 15 in the bearing seat 11 is short, production time and cost are saved, and the arrangement of the lead-out wire bundle 15 can be avoided from the structures such as the impact foil 13 and the wave foil 12, so as to improve working reliability.

[0049] In addition, in some embodiments of the present application, the outer periphery of the lead-out wire is wrapped with an insulating layer 16, which can be a plastic piece (such as polyethylene) or a rubber piece, etc. The insulating layer 16 can ensure that the lead-out wire and the protective ring 14 have good insulation with other components, so as to improve working safety.

[0050] In some other embodiments of the present application, the other end of the lead-out wire bundle 15 is led out and provided with a through piece having a sealing function, so as to further improve insulation and sealing, and further improve working safety, on the basis of realizing that the lead-out wire can be formed into a detection circuit.

[0051] As shown in FIG. 5, according to some embodiments of the present application, the protective ring 14 is configured as a graphite ring.

[0052] The protective ring 14 can be configured as a graphite ring. The graphite material has good electrical conductivity, which can ensure that the protective ring 14 and the rotor can determine running failure and damage degree of the impact foil 13 through contact conduction function. At the same time, the graphite material has good lubrication effect and wear resistance, so that the rotor running at high speed will not be damaged greatly when falling on the graphite, thereby playing a good buffering and protection role, and helping to prolong the service life of the protective ring 14 and save maintenance cost.

[0053] It should be noted that the protective ring 14 can be but is not limited to a graphite ring, and in some embodiments, the protective ring 14 can also be replaced by other conductive and wear-resistant materials, such as graphene, conductive carbon black, and carbon fiber, etc.

[0054] As shown in FIGS. 3 and 5, according to some embodiments of the present application, a first potting layer 17 is arranged between the protective ring 14 and the bearing seat 11 to provide cushioning protection.

[0055] The first potting layer 17 can be an insulating potting glue, which can be specifically made of materials with good electrical insulation and sealing properties, such as epoxy resin, silicone rubber, polyurethane, etc. The first potting layer 17 is located between the protective ring 14 and the bearing seat 11, and can separate the protective ring 14 from the bearing seat 11. On the one hand, the first potting layer 17 can provide good cushioning effect, and when the protective ring 14 is impacted by the rotor during protection, the first potting layer 17 can appropriately cushion the impact to avoid serious damage to the protective ring 14. On the other hand, the first potting layer 17 can also provide good insulation and sealing protection, and can protect the lead wire bundle 15 connected to the protective ring 14 from damage, thereby improving the reliability and durability of the lead wire bundle 15.

[0056] It can be understood that the insulating potting glue is initially in a liquid state and begins to solidify after being filled, and thus can also function to fix the protective ring 14 and the lead wire bundle 15, and can also improve the installation stability of the protective ring 14 and the lead wire bundle 15.

[0057] In addition, in some specific embodiments of the present application, the first potting layer 17 includes a first ring segment and a second ring segment connected thereto, wherein the first ring segment is located in a radial region between the protective ring 14 and the bearing seat 11, and the second ring segment is located in an axial region between the protective ring 14 and the bearing seat 11. In this way, the regions opposite to the protective ring 14 and the bearing seat 11 can be filled with insulating potting glue to ensure complete insulation between the protective ring 14 and the bearing seat 11.

[0058] As shown in FIG. 5, according to some embodiments of the present application, the first potting layer 17 is provided with a first limiting portion 171 on a side facing the protective ring 14, and the protective ring 14 is provided with a second limiting portion 141 in concave-convex cooperation with the first limiting portion 171.

[0059] Specifically, the first potting layer 17 has a certain thickness, and a first limiting portion 171 can be arranged on one side of the first potting layer 17 in the thickness direction, and a second limiting portion 141 is formed on the protective ring 14, and the first limiting portion 171 and the second limiting portion 141 are adapted to be matched in concave-convex, for example, the second limiting portion 141 can be configured as a groove, and the first limiting portion 171 is formed as a protrusion adapted to extend into the groove, or the second limiting portion 141 can be configured as a protrusion, and the first limiting portion 171 is formed as a groove adapted to accommodate the protrusion, or the second limiting portion 141 can be configured as a structure having both a groove and a protrusion, and the first limiting portion 171 is formed as a structure also having both a protrusion and a groove. The first limiting portion 171 and the second limiting portion 141 can limit the relative movement of the first potting layer 17 and the protective ring 14, thereby improving the anti-disengagement performance of the first potting layer 17 and the protective ring 14 during subsequent processing and operation, and improving the connection stability and working reliability of the first potting layer 17 and the protective ring 14.

[0060] It can be understood that the number of the first limiting portion 171 and the second limiting portion 141 can be one-to-one corresponding multiple, so as to further improve the connection stability and working reliability of the first potting layer 17 and the protective ring 14.

[0061] It should be pointed out that the first limiting portion 171 does not need to be processed separately, by processing the second limiting portion 141 on the protective ring 14, filling the liquid insulation potting glue between the protective ring 14 and the bearing seat 11, and after the insulation potting glue is solidified, the part matched with the second limiting portion 141 can automatically form the first limiting portion 171, which can save the process.

[0062] As shown in FIG. 3, according to some embodiments of the present application, when the top foil 13 is in the limit compression state or after wearing, the radial gap between the protective ring 14 and the rotor is less than or equal to the radial gap between the top foil 13 and the rotor.

[0063] When the top foil 13 is not worn or slightly worn, the top foil 13 normally suspends the rotor, and the top foil 13, the wave foil 12, and the rotor are normally and safely operated. When the rotor suddenly loses stability due to power failure or external impact and causes the top foil 13 to be in an extreme compression state, and when the top foil 13 is worn after long-term operation, the radial distance between the rotor and the top foil 13 and the protective ring 14 is shortened, the radial gap between the protective ring 14 and the rotor is less than or equal to the radial gap between the top foil 13 and the rotor, the distance between the rotor and the protective ring 14 in the radial direction is equal to or shorter than the distance between the rotor and the top foil 13 in the radial direction, and the distance between the rotor and the protective ring 14 in the radial direction is also shorter than the distance between the rotor and the wave foil 12 in the radial direction. When the rotor moves outward in the radial direction, the rotor first contacts the protective ring 14 with a shorter distance, so that the protective ring 14 can support and buffer between the rotor and the top foil 13 and the wave foil 12, and can protect the top foil 13 and the wave foil 12 from being deformed beyond the design range, and can protect the wave foil 12 outside the top foil 13 from being excessively deformed and losing elasticity due to the impact of the rotor.

[0064] As shown in FIG. 1, FIG. 2, and FIG. 4, the centrifugal compressor 2 according to the second aspect of the present application comprises a casing 22, a stator 23, a rotor, and the radial dynamic pressure bearing 1.

[0065] The casing 22 has a radial bearing chamber 221; the stator 23 and the rotor are arranged in the casing 22; the radial dynamic pressure bearing 1 is configured as the radial dynamic pressure bearing 1 in any one of the above embodiments, and is arranged in the radial bearing chamber 221 of the casing 22, and the top foil 13 and the rotor are arranged opposite to each other in the radial direction.

[0066] The stator 23 and the rotor are arranged in the casing 22, and the stator 23 and the rotor can jointly realize the function of the centrifugal compressor 2 to compress gas. The radial dynamic pressure bearing 1 can be arranged in the radial bearing chamber 221 of the casing 22 to be fixedly installed at a predetermined position of the casing 22, and the radial dynamic pressure bearing 1 is sleeved on at least part of the outer periphery of the rotor, and the top foil 13 of the radial dynamic pressure bearing 1 and the rotor are arranged opposite to each other in the radial direction. Since the centrifugal compressor 2 according to the second aspect of the present application comprises the radial dynamic pressure bearing 1 in any one of the above embodiments, the first aspect is that the centrifugal compressor 2 can protect the top foil 13, the wave foil 12, and the like when the rotor loses stability and is impacted, can improve the reliability and service life of the top foil 13 and the wave foil 12, and can improve the stability of the rotor in operation; the second aspect is that the running fault can be judged by the contact conduction function, and the damage degree of the radial dynamic pressure bearing 1 can be determined to realize predictive maintenance, so that the use of the radial dynamic pressure bearing 1 can be avoided after damage, and the working reliability and safety can be improved.

[0067] As shown in FIG. 2, according to some embodiments of the present application, the centrifugal compressor 2 further comprises: the impeller 24 arranged on the rotor, the casing 22 further comprises: a shroud, the shroud seal 25 is arranged between the impeller 24 and the shroud, the back seal 26 is arranged between the impeller 24 and the radial bearing chamber 221, the radial gap between the guard ring 14 and the rotor is smaller than the radial gap between the shroud seal 25 and the impeller 24, and the radial gap between the guard ring 14 and the rotor is also smaller than the radial gap between the back seal 26 and the rotor.

[0068] The impeller 24 is arranged on the rotor, and the rotation of the rotor can drive the impeller 24 to rotate to realize gas flow guiding and compression; the shroud is used for supporting, connecting and sealing the impeller 24, and helps to maintain the balance of the rotor and reduce vibration caused by uneven mass distribution; wherein the shroud seal 25 is arranged between the impeller 24 and the shroud, and the back seal 26 is arranged between the impeller 24 and the radial bearing chamber 221, both the shroud seal 25 and the back seal 26 can improve the structural air tightness and enhance the gas and liquid leakage prevention effect, and can improve the compression efficiency of the centrifugal compressor 2.

[0069] When the radial gap between the shroud seal 25 and the impeller 24 and the radial gap between the back seal 26 and the rotor are smaller than or equal to the radial gap between the guard ring 14 and the rotor, it will cause poor gas and liquid leakage prevention performance and reduce the overall structural operation stability, therefore, by limiting the size relationship of the radial gap between the shroud seal 25 and the impeller 24, the radial gap between the back seal 26 and the rotor and the radial gap between the guard ring 14 and the rotor within the above range, the radial gap between the shroud seal 25 and the impeller 24 and the radial gap between the back seal 26 and the rotor are relatively small to adapt to the radial gap between the guard ring 14 and the rotor, which helps to optimize the sealing performance, improve the gas leakage prevention performance, improve the working efficiency and improve the rotor operation stability.

[0070] As shown in FIG. 4, according to some embodiments of the present application, the second filling layer 18 is arranged between the radial bearing chamber 221 and the guard ring 14, and the second filling layer 18 is integrally filled with the first filling layer 17.

[0071] The second potting layer 18 is located between the radial bearing chamber 221 and the guard ring 14 and is integrally potted with the first potting layer 17. Both the first potting layer 17 and the second potting layer 18 can be insulating potting glue. Similarly, the second potting layer 18 can separate the guard ring 14 from the radial bearing chamber 221. On the one hand, the second potting layer 18 can provide good buffering effect. When the guard ring 14 is impacted by the rotor during protection, the second potting layer 18 can appropriately buffer the impact to avoid serious damage to the guard ring 14. On the other hand, the second potting layer 18 can also provide good insulation and sealing protection, which can protect the lead wire bundle 15 connected to the guard ring 14 from damage and improve the reliability and durability of the lead wire bundle 15.

[0072] Similarly, in some embodiments of the present application, the second potting layer 18 includes a third ring segment and a fourth ring segment connected thereto, wherein the third ring segment is located in the radial area between the guard ring 14 and the radial bearing chamber 221, and the fourth ring segment is located in the axial area between the guard ring 14 and the radial bearing chamber 221. In this way, the areas opposite to the radial bearing chamber 221 of the guard ring 14 can be filled with insulating potting glue to ensure complete insulation between the guard ring 14 and the radial bearing chamber 221.

[0073] As shown in FIG. 5, according to some embodiments of the present application, the side of the radial bearing chamber 221 facing the guard ring 14 is provided with a first positioning part 2211, and the first potting layer 17 is correspondingly provided with a second positioning part 181 which is concave-convex matched with the first positioning part 2211.

[0074] The side of the radial bearing chamber 221 facing the guard ring 14 can be provided with a first positioning part 2211, and the second potting layer 18 has a certain thickness. The side of the second potting layer 18 away from the guard ring 14 in the thickness direction can be provided with a second positioning part 181 which is adapted to be concave-convex matched with the first positioning part 2211. Exemplarily, the first positioning part 2211 can be configured as a groove, and the second positioning part 181 is formed as a protrusion adapted to extend into the groove, or the first positioning part 2211 can be configured as a protrusion, and the second positioning part 181 is formed as a groove adapted to accommodate the protrusion, or the first positioning part 2211 can be configured as a structure having both a groove and a protrusion, and the second positioning part 181 is formed as a structure also having both a protrusion and a groove. By providing the first positioning part 2211 and the second positioning part 181, on the one hand, the assembly positioning effect can be achieved, and the assembly precision and reliability of the radial dynamic pressure bearing 1 can be improved. On the other hand, the first positioning part 2211 and the second positioning part 181 can limit the relative movement between the second potting layer 18 and the radial bearing chamber 221, thereby improving the anti-disengagement performance of the second potting layer 18 and the radial bearing chamber 221 during subsequent processing and operation, and improving the connection stability and working reliability of the second potting layer 18 and the radial bearing chamber 221.

[0075] It can be understood that the number of the first positioning part 2211 and the second positioning part 181 can be one-to-one corresponding multiple, so as to further improve the connection stability of the second potting layer 18 and the radial bearing chamber 221 and the working reliability.

[0076] It should be pointed out that the second positioning part 181 does not need to be processed separately. By processing the first positioning part 2211 in the radial bearing chamber 221, the liquid insulation potting glue is filled between the protective ring 14 and the radial bearing chamber 221, and after the insulation potting glue is solidified, the part cooperating with the first positioning part 2211 can automatically form the second positioning part 181, which can save the process.

[0077] As shown in FIG. 2, according to some embodiments of the present application, the protective ring 14 is located at one end of the bearing seat 11 adjacent to the stator 23.

[0078] The protective ring 14 can be arranged at one end of the bearing seat 11 in the axial direction close to the stator 23. When the protective ring 14 is in contact with the rotor, the surface of the protective ring 14 will wear and produce tiny particles and fall off. By arranging the protective ring 14 at one end of the bearing seat 11 in the axial direction close to the stator 23, the tiny particles falling off from the protective ring 14 can be brought into the motor cavity where the stator 23 is located by the airflow and enter the filter of the unit, without passing through the top foil 13 area of the radial dynamic pressure bearing 1, so as to not interfere with the top foil 13, thereby protecting the normal work of the top foil 13.

[0079] As shown in FIG. 2, according to some embodiments of the present application, the rotor includes a primary rotor 21a and a secondary rotor 21b, and the radial bearing chamber 221 includes a primary bearing chamber 221a corresponding to the primary rotor 21a and a secondary bearing chamber 221b corresponding to the secondary rotor 21b. The primary bearing chamber 221a is provided with a primary bearing, and the secondary bearing chamber 221b is provided with a secondary bearing. At least one of the primary bearing and the secondary bearing is configured as the radial dynamic pressure bearing 1.

[0080] The primary rotor 21a and the secondary rotor 21b can be coaxially arranged and connected. The primary bearing chamber 221a corresponds to the primary rotor 21a. The primary bearing can be arranged on the outer periphery of the primary rotor 21a through the primary bearing chamber 221a to cooperate with the primary rotor 21a. The secondary bearing chamber 221b corresponds to the secondary rotor 21b. The secondary bearing can be arranged on the outer periphery of the primary rotor 21a through the secondary bearing chamber 221b to cooperate with the secondary rotor 21b. In the embodiment, the primary bearing and the secondary bearing can be arranged as follows: the primary bearing is configured as a radial dynamic pressure bearing 1, and the secondary bearing is configured as another bearing (such as a ball bearing). In the embodiment, the primary bearing and the secondary bearing can also be arranged as follows: the secondary bearing is configured as a radial dynamic pressure bearing 1, and the primary bearing is configured as another bearing. In the embodiment, the primary bearing and the secondary bearing can also be arranged as follows: both the primary bearing and the secondary bearing are configured as radial dynamic pressure bearings 1. By configuring at least one of the primary bearing and the secondary bearing as a radial dynamic pressure bearing 1, at least one radial dynamic pressure bearing 1 is arranged on the outer periphery of the primary rotor 21a and the secondary rotor 21b, which can improve the working performance and the running stability of the rotor.

[0081] As shown in FIG. 2, according to some embodiments of the present application, the primary bearing and the secondary bearing are both configured as radial dynamic pressure bearings 1. The centrifugal compressor 2 further includes a detection module having a detection circuit. The detection circuit includes a first loop, a second loop, and a third loop. The first loop is a loop formed by connecting the lead bundle 15 of the primary bearing to the shell 22. The second loop is a loop formed by connecting the lead bundle 15 of the secondary bearing to the shell 22. The third loop is a loop formed by connecting the lead bundle 15 of the primary bearing to the lead bundle 15 of the secondary bearing. When any loop is conducted, the detection module sends an alarm.

[0082] The detection module has a detection circuit, a first loop in the detection circuit is a loop formed by connecting the lead wire bundle 15 of the primary bearing with the shell 22 of the centrifugal compressor 2, when the primary rotor 21a presses against the shield ring 14 of the primary bearing, the first loop is conducted, the detection module can issue an alarm to remind that the primary bearing needs to be maintained and replaced or abnormally operated, etc.; a second loop in the detection circuit is a loop formed by connecting the lead wire bundle 15 of the secondary bearing with the shell 22 of the centrifugal compressor 2, when the secondary rotor 21b presses against the shield ring 14 of the secondary bearing, the second loop is conducted, the detection module can issue an alarm to remind that the secondary bearing needs to be maintained and replaced or abnormally operated, etc.; a third loop in the detection circuit is a loop formed by connecting the lead wire bundle 15 of the primary bearing with the lead wire bundle 15 of the secondary bearing, when the primary rotor 21a presses against the shield ring 14 of the primary bearing, and the secondary rotor 21b presses against the shield ring 14 of the secondary bearing, the third loop is conducted, the detection module can issue an alarm to remind that the primary bearing and the secondary bearing both need to be maintained and replaced or abnormally operated, etc. By setting the first loop, the second loop and the third loop, the detection module can accurately remind which part of the primary bearing and the secondary bearing is abnormal, so as to accurately identify the fault and take preventive measures, which can improve the maintenance efficiency and convenience, reduce downtime and maintenance cost.

[0083] In addition, in some embodiments of the present application, the primary bearing and the secondary bearing are both configured as radial dynamic pressure bearings 1, wherein the primary bearing corresponds to a primary bearing seat 11a, a primary top foil 13a, a primary shield ring 14a, a primary lead wire bundle 15a and a primary insulation layer 16a, etc., and the secondary bearing corresponds to a secondary bearing seat 11b, a secondary top foil 13b, a secondary shield ring 14b, a secondary lead wire bundle 15b and a secondary insulation layer 16b, etc.

[0084] As shown in FIG. 6, according to the control method of the third embodiment of the present application, the control method comprises: acquiring whether the first loop, the second loop and the third loop are conducted, the first loop is a loop formed by connecting the lead wire bundle of the primary bearing with the shell 22, the second loop is a loop formed by connecting the lead wire bundle of the secondary bearing with the shell 22, and the third loop is a loop formed by connecting the lead wire bundle of the primary bearing with the lead wire bundle of the secondary bearing; if the first loop is conducted, a primary bearing damage alarm is reported; if the second loop is conducted, a secondary bearing damage alarm is reported; and if the third loop is conducted, a primary bearing and secondary bearing damage alarm is reported.

[0085] According to the control method of the third aspect of the embodiments of the present application, the specific conduction conditions of the first loop, the second loop and the third loop obtained can be used as the judgment criterion for whether to report the primary bearing damage alarm and the secondary bearing damage alarm. Specifically, when the first loop is conducted, the primary bearing damage alarm is reported, reminding the customer to replace the primary bearing in time; when the second loop is conducted, the secondary bearing damage alarm is reported, reminding the customer to replace the primary bearing in time; and when the third loop is conducted, the primary bearing and the secondary bearing damage alarms are reported, reminding the customer to replace the primary bearing and the secondary bearing in time. According to the conduction state of different loops, the specific part of the primary bearing and the secondary bearing that produces an anomaly can be accurately reminded, so as to accurately maintain and replace, and reduce the maintenance cost.

[0086] As shown in FIG. 6, according to some embodiments of the present application, the control method further comprises: confirming whether the centrifugal compressor 2 needs to be started urgently; if yes, inputting an emergency start threshold; wherein the emergency start threshold is set according to the field environment; and if no, replacing the bearing and maintaining.

[0087] When any one of the first loop, the second loop and the third loop is conducted and the corresponding bearing damage alarm is reported, different treatments can be performed according to the confirmation of whether the centrifugal compressor 2 needs to be started urgently, specifically: if it is confirmed that the centrifugal compressor 2 needs to be started urgently, the emergency start threshold is inputted, so that the centrifugal compressor 2 can be started urgently within a controllable range, so that the bearing can be started urgently for a certain number of times when the bearing reaches the replacement period, ensuring that maintenance can be performed during the idle period, which can avoid affecting the use of the customer due to maintenance; and if it is confirmed that the centrifugal compressor 2 does not need to be started urgently, the bearing reported in the damage alarm is replaced and maintained, so that the bearing after replacement and maintenance can have good working performance, thereby improving the working efficiency and safety of the centrifugal compressor 2.

[0088] It should be noted that the emergency start threshold is set according to the field environment, for example, when the working environment is good, the emergency start threshold can be set to 10 times, and when the working environment is poor, the emergency start threshold can be set to 5 times.

[0089] It can be understood that the emergency start number is less than or equal to the emergency start threshold, and in some embodiments, the emergency start number is n and the emergency start threshold is N, so 0≤n≤N.

[0090] As shown in FIG. 6, according to some embodiments of the present application, the control method further comprises: if the first loop, the second loop and the third loop are all not turned on, increasing the output frequency of the frequency converter to above the bearing working speed; obtaining the number of turns on of the first loop, the second loop and the third loop; if the number of turns on is zero, normally running and continuously obtaining the number of turns on of the first loop, the second loop and the third loop; if the number of turns on is greater than or equal to 1, obtaining the running speed of the centrifugal compressor.

[0091] In the control method according to the present embodiment, if the first loop, the second loop and the third loop are all not turned on, it indicates that the bearing has not reached the replacement period, and then the output frequency of the frequency converter can be increased to above the bearing working speed, so as to determine whether the bearing working environment is abnormal through the turning on of the first loop, the second loop and the third loop during the running process, and to improve the bearing carrying capacity by increasing the speed, thereby avoiding the bearing working under abnormal load for a long time. According to the number of turns on of the first loop, the second loop and the third loop, different treatments are adopted according to different specific conditions, which are: if the number of turns on of the first loop, the second loop and the third loop is zero, i.e. all the loops are not turned on, then normally running, and if the number of turns on of the first loop, the second loop and the third loop is greater than or equal to 1, i.e. at least one of the three groups of loops is turned on, then obtaining the running speed of the centrifugal compressor 2, so as to further determine whether the bearing working environment is abnormal.

[0092] It should be noted that the frequency converter can improve the control performance of the centrifugal compressor 2, and can accurately control the speed and torque to match the actual use needs.

[0093] As shown in FIG. 6, according to some embodiments of the present application, the control method further comprises: if the running speed is less than the maximum speed, increasing the running speed by the increase threshold, and after the time threshold, obtaining the number of turns on of the first loop, the second loop and the third loop again, wherein the increase threshold is 2 hz and the time threshold is 30 s; if the running speed is greater than or equal to the maximum speed, stopping the machine for protection.

[0094] If the running speed of the centrifugal compressor 2 is less than the maximum speed, it indicates that the bearing corresponding to the conduction loop is in the normal loss range, then the running speed is increased by the lifting threshold, and after the duration threshold, the number of conduction of the first loop, the second loop and the third loop is obtained again. If the number of conduction is zero, it is normal operation, if the number of conduction is greater than or equal to 1, the running speed of the centrifugal compressor 2 is obtained again, if the running speed of the centrifugal compressor 2 obtained again is still less than the maximum speed, the running speed is increased by the lifting threshold again, and the number of conduction of the first loop, the second loop and the third loop is obtained again after the duration threshold, and the cycle is repeated. The lifting threshold is 2hz and the time threshold is 30s, so as to ensure that the lifting threshold and the time threshold are appropriate, and the working safety of the centrifugal compressor and the accuracy of the detection result can be improved.

[0095] If the running speed of the centrifugal compressor 2 is greater than or equal to the maximum speed, it indicates that the rotor instability impact may occur in the centrifugal compressor 2, which causes abnormal high-speed operation of the bearing and the like, and then the machine is stopped to protect the safety.

[0096] In the description of the present specification, the description of the terms "one embodiment", "some embodiments", "exemplary embodiment", "example", "specific example" or "some examples" means that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present application. In the present specification, the exemplary description of the above terms does not necessarily mean the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0097] Although the embodiments of the present application have been shown and described, those skilled in the art can understand that various changes, modifications, replacements and variations can be made to the embodiments without departing from the principles and purposes of the present application, and the scope of the present application is defined by the claims and their equivalents.

Claims

1. A radial hydrodynamic bearing, disposed on a rotor, wherein, include: Bearing housing; A corrugated foil and a top foil, wherein the corrugated foil is located between the top foil and the bearing seat, and elastically pushes against the top foil; A protective ring is disposed at one axial end of the bearing housing; wherein, in the same radial direction, the radial gap between the protective ring and the rotor, minus the radial gap between the top foil and the rotor, is less than the thickness of the top foil.

2. The radial hydrodynamic bearing according to claim 1, wherein, It also includes: a lead wire harness, one end of which is connected to the protective ring, the lead wire harness is wrapped with an insulating layer, and the other end of which is led out and formed into a detection circuit, the detection circuit being adapted to conduct when the rotor presses against the protective ring.

3. The radial hydrodynamic bearing according to claim 1 or 2, wherein, The protective ring is constructed of graphite.

4. The radial hydrodynamic bearing according to claims 1-3, wherein, A first potting layer is provided between the protective ring and the bearing housing to provide cushioning protection.

5. The radial hydrodynamic bearing according to claim 4, wherein, The first potting layer has a first limiting part on the side facing the protective ring, and the protective ring has a second limiting part that convexly and concavely engages with the first limiting part.

6. The radial hydrodynamic bearing according to any one of claims 1-5, wherein, After the top foil is under extreme compression or wear, the radial gap between the protective ring and the rotor is less than or equal to the radial gap between the top foil and the rotor.

7. A centrifugal compressor, wherein, include: A housing having a radial bearing chamber; A stator and a rotor, both of which are disposed within the housing; The radial dynamic pressure bearing according to any one of claims 1-6, wherein the radial dynamic pressure bearing is disposed in the radial bearing chamber, and the top foil is disposed radially opposite to the rotor.

8. The centrifugal compressor according to claim 7, wherein, The centrifugal compressor further includes: an impeller disposed on the rotor, and the housing further includes: a wheel cover, a wheel cover seal is disposed between the impeller and the wheel cover, a wheel back seal is disposed between the impeller and the radial bearing chamber, the radial clearance between the protective ring and the rotor is smaller than the radial clearance between the wheel cover seal and the impeller, and the radial clearance between the protective ring and the rotor is also smaller than the radial clearance between the wheel back seal and the rotor.

9. The centrifugal compressor according to claim 7 or 8, wherein, A second potting layer is provided between the radial bearing chamber and the protective ring, and the second potting layer is integrally potted with the first potting layer.

10. The centrifugal compressor according to claim 9, wherein, The radial bearing chamber is provided with a first positioning part on the side facing the protective ring, and the first potting layer is provided with a second positioning part that is in concave-convex cooperation with the first positioning part.

11. The centrifugal compressor according to claims 7-10, wherein, The protective ring is located at one end of the bearing housing adjacent to the stator.

12. The centrifugal compressor according to any one of claims 8-11, wherein, The rotor includes a primary rotor and a secondary rotor. The radial bearing chamber includes a primary bearing chamber corresponding to the primary rotor and a secondary bearing chamber corresponding to the secondary rotor. A primary bearing is disposed in the primary bearing chamber, and a secondary bearing is disposed in the secondary bearing chamber. At least one of the primary bearing and the secondary bearing is configured as a radial dynamic pressure bearing.

13. The centrifugal compressor according to claim 12, wherein, Both the primary bearing and the secondary bearing are constructed as radial dynamic pressure bearings. The centrifugal compressor further includes a detection module with a detection circuit. The detection circuit includes a first circuit, a second circuit, and a third circuit. The first circuit is formed by connecting the lead wire harness of the primary bearing to the housing. The second circuit is formed by connecting the lead wire harness of the secondary bearing to the housing. The third circuit is formed by connecting the lead wire harnesses of the primary bearing and the secondary bearing. If any circuit is conducting, the detection module will issue an alarm.

14. A control method applicable to the centrifugal compressor according to any one of claims 7-13, wherein, include: To determine whether the first circuit, the second circuit, and the third circuit are conductive, the first circuit is the circuit formed by connecting the lead wire harness of the first-stage bearing to the housing, the second circuit is the circuit formed by connecting the lead wire harness of the second-stage bearing to the housing, and the third circuit is the circuit formed by connecting the lead wire harnesses of the first-stage bearing and the second-stage bearing. If the first circuit is open, a first-level bearing damage alarm will be issued; If the second circuit is active, a secondary bearing damage alarm will be reported; If the third circuit is activated, an alarm will be issued indicating damage to the primary and secondary bearings.

15. The control method according to claim 14, wherein, Also includes: Confirm whether the centrifugal compressor needs to be started immediately; Yes, then enter the emergency power-on count threshold; wherein the emergency power-on count threshold is set according to the site environment; If not, then the bearings should be replaced and maintained.

16. The control method according to claim 14 or 15, wherein, The control method further includes: If the first circuit, the second circuit, and the third circuit are all not conducting, then increase the output frequency of the inverter to above the bearing operating speed; Obtain the number of active circuits in the first, second, and third circuits; If the number of conductions is zero, the system operates normally and continuously acquires the number of conductions of the first circuit, the second circuit, and the third circuit. If the number of conductions is greater than or equal to 1, then the operating speed of the centrifugal compressor is obtained.

17. The control method according to claim 16, wherein, The control method further includes: If the operating speed is less than the maximum speed, the operating speed is increased according to the increase threshold, and after the duration threshold, the number of the first circuit, the second circuit and the third circuit are obtained again, wherein the increase threshold is 2 Hz and the time threshold is 30 s; If the operating speed is greater than or equal to the maximum speed, then the machine will be shut down for protection.

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