CN113107970A

CN113107970A - Rotor assembly and working method thereof, compressor and air conditioning equipment

Info

Publication number: CN113107970A
Application number: CN202010021881.0A
Authority: CN
Inventors: 刘华; 钟瑞兴; 陈玉辉; 张治平; 叶文腾
Original assignee: Gree Electric Appliances Inc of Zhuhai
Current assignee: Gree Electric Appliances Inc of Zhuhai
Priority date: 2020-01-09
Filing date: 2020-01-09
Publication date: 2021-07-13

Abstract

The invention relates to a rotor assembly and a working method thereof, a compressor and air conditioning equipment, wherein the rotor assembly comprises: a rotor (2); and a first bearing (5) and a second bearing (7) which are mounted on the rotor (2), wherein the first bearing (5) is a dynamic pressure gas bearing, and the radial dimension of an inner ring (71) of the second bearing (7) relative to the rotor (2) can be adjusted according to the working state of the first bearing (5). The rotor assembly can flexibly adjust the supporting state of the bearing to the rotor under different operation conditions of the rotor, so that the operation stability of the rotor and the bearing capacity of the bearing are improved, and the abrasion of the first bearing is reduced.

Description

Rotor assembly and working method thereof, compressor and air conditioning equipment

Technical Field

The invention relates to the technical field of air compression equipment, in particular to a rotor assembly and a working method thereof, a compressor and air conditioning equipment.

Background

The bearing is an essential basic component in the rotating machinery, and the functions of the bearing comprise: the support shaft and its parts on the shaft continue to rotate and reduce friction between the rotor and the support member.

In the current centrifugal compressor, rolling bearings, sliding bearings, magnetic suspension bearings, and the like are commonly used. The rolling bearing has the advantages of small friction resistance, sensitive starting, high efficiency and the like, is widely applied, but has the defects of poor impact resistance and unsuitability for high-rotating-speed environment; the traditional oil sliding bearing has good adaptability in the occasions of high precision, heavy load, belt impact and the like, but is limited by the structure, a lubricating system must be configured and correspondingly sealed, and the complexity of the system is increased; magnetic suspension bearings are widely applied to small and medium-sized compressors in recent years, have the advantages of high rotating speed, no oil, and the like, but have large bearing clearance, and the performance improvement is limited.

With the trend of miniaturization of centrifugal compressors, the industry puts higher and higher demands on bearings, which not only require the bearings to operate at higher rotation speed, but also require extremely high rotation precision. The air bearing has the advantages of small friction loss, almost no friction at extremely high rotating speed, good high-temperature stability, small vibration, no need of lubricating oil and the like, and is gradually applied to a centrifugal compressor.

The air bearings are classified into static pressure gas bearings and dynamic pressure gas bearings according to the difference in the mechanism of generation of a lubricating gas film. The static pressure gas bearing uses an external gas source to supply gas to the bearing to generate pressure bearing load, and the dynamic pressure gas bearing uses a pressure gas film generated by the gas in a wedge-shaped space between a shaft and the inner surface of the bearing to support the load. Compared with static pressure gas bearing, the dynamic pressure gas bearing does not need external gas source, simplifies the structure, and the dynamic pressure effect of the dynamic pressure gas bearing is more obvious along with the increase of the relative movement speed, thus being very suitable for high rotating speed environment.

However, after the dynamic pressure gas bearing is applied to a centrifuge compressor, in the using process, the stability of the rotor operation is found to be poor when the compressor is in the working conditions of starting, stopping or reversing and the like.

Disclosure of Invention

The invention aims to provide a rotor assembly, a working method of the rotor assembly, a compressor and air conditioning equipment, which can improve the stability of rotor support.

One aspect of the present invention provides a rotor assembly including:

a rotor; and

the first bearing and the second bearing are arranged on the rotor, the first bearing is a dynamic pressure gas bearing, and the radial size of the inner ring of the second bearing relative to the rotor can be adjusted according to the working state of the first bearing.

In some embodiments, the rotor assembly further comprises:

an adjusting member configured to couple the inner race with the rotor to support the rotor through the second bearing when the first bearing is in an unstable operating state; and when the first bearing is in a stable working state, the inner ring is disengaged from the rotor to support the rotor through the first bearing.

In some embodiments, the first bearing has a first clearance with the rotor, and the inner race has a second clearance with the rotor when the first bearing is in a steady state of operation, the second clearance being greater than the first clearance.

In some embodiments, the inner race comprises:

at least two inner ring sections arranged along the circumferential direction; and

at least two elastic elements connected between the ends of adjacent inner ring segments;

when the inner ring is combined with the rotor, the end parts of the adjacent inner ring sections are abutted; when the inner ring is disengaged from the rotor, a third gap is provided between the ends of adjacent inner ring segments.

In some embodiments, the inner ring is configured to receive a radial force exerted by an externally introduced high pressure gas;

the rotor assembly further includes an adjustment member for adjusting the pressure of the high pressure gas to adjust the radial dimension of the inner race.

In some embodiments, the rotor assembly further comprises:

a rotational speed detecting means for detecting a rotational speed of the rotor; and

the control component is used for enabling the adjusting component to increase the gas pressure to a first pressure value when the rotating speed of the rotor is in a first rotating speed range so as to enable the inner ring to be combined with the rotor; when the rotating speed of the rotor is in a second rotating speed interval, the gas pressure is reduced to a second pressure value by the adjusting component, so that the inner ring is separated from the rotor; wherein, the first rotating speed interval is less than the second rotating speed interval, and the first pressure value is greater than the second pressure value.

In some embodiments, the rotor assembly includes a support unit provided at least one end of the rotor, the support unit including a first bearing and a second bearing.

In some embodiments, the supporting unit includes:

the supporting unit includes:

a first bearing;

two second bearings which are arranged at intervals along the axial direction, wherein each second bearing is arranged at the same side of the first bearing;

the second bearing seats are used for supporting the rotor through the second bearings, and air-entraining channels are arranged on the second bearing seats and used for introducing external high-pressure air; and

and the spacing assembly is arranged between the adjacent second bearings and is fixed with the inner ring, a pressure cavity is arranged in the spacing assembly, and the pressure cavity is communicated with the air bleed channel and is configured to enable high-pressure air to apply radial force to the inner ring.

In some embodiments, the support unit includes two second bearings, inner rings of the two second bearings are integrally formed with the spacer assembly, and outer rings of the two second bearings are in contact with two side surfaces of the spacer assembly in the axial direction and are slidably disposed.

In some embodiments, the second bearing in the same support unit is axially outboard of the first bearing.

In some embodiments, the rotor comprises:

the first shaft section is provided with a first bearing;

the second shaft section is provided with a second bearing, and the diameter of the second shaft section is smaller than that of the first shaft section; and

and the guiding part is arranged at the joint of the first shaft section and the second shaft section and used for guiding the refrigerant on the first shaft section to the second shaft section.

In some embodiments, the outer profile of the guide is rounded, sloped or stepped in the longitudinal section of the rotor.

In some embodiments, the rotor assembly further comprises a housing, the support unit further comprising:

the first bearing seat is connected with the shell and used for supporting the rotor through a first bearing; and

and the second bearing seat is connected to the first bearing seat, is independent from the shell and is used for supporting the rotor through the second bearing.

In some embodiments, one end of the second bearing seat close to the first bearing seat is provided with a first spigot used for limiting the freedom degree of the first bearing seat moving towards the second bearing seat along the axial direction and carrying out thrust on the first bearing; and/or

And a second spigot is arranged on the inner side wall of the shell and used for limiting the freedom degree of the first bearing seat moving away from the second bearing seat along the axial direction.

In some embodiments, the second bearing comprises an angular contact rolling bearing.

Another aspect of the present invention provides a compressor including the rotor assembly of the above embodiment.

In another aspect, the present invention provides an air conditioning apparatus including the compressor of the above embodiment.

In another aspect, the present invention provides a working method of a rotor assembly based on the above embodiments, including:

determining the working state of the first bearing;

and adjusting the radial size of the inner ring according to the working state of the first bearing.

In some embodiments, the step of adjusting the radial dimension of the inner race according to the operating condition of the first bearing comprises:

when the first bearing is in an unstable working state, increasing the gas pressure to a first pressure value through the adjusting part, and combining the inner ring with the rotor to support the rotor through the second bearing;

when the first bearing is in a stable working state, the gas pressure is reduced to a second pressure value through the adjusting component, the inner ring is separated from the rotor, so that the rotor is supported through the first bearing, and the second pressure value is smaller than the first pressure value.

In some embodiments, the step of determining the operating condition of the first bearing comprises:

detecting the rotating speed of the rotor;

judging the interval of the rotating speed of the rotor, and determining that the first bearing is in an unstable working state when the rotating speed of the rotor is in a first rotating speed interval; and when the rotating speed of the rotor is in a second rotating speed interval, determining that the first bearing is in a stable working state, wherein the first rotating speed interval is smaller than the second rotating speed interval.

The rotor assembly comprises a first bearing and a second bearing, wherein the first bearing supports a rotor, the first bearing is a dynamic pressure gas bearing, the radial size of an inner ring of the second bearing relative to the rotor can be adjusted according to the working state of the first bearing when the rotor is in different working conditions, so that the supporting state of the bearing on the rotor can be flexibly adjusted under different working conditions of the rotor, the running stability of the rotor and the bearing capacity of the bearing are improved, and the first bearing is prevented from being abnormally abraded.

Drawings

The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this application, illustrate embodiment(s) of the invention and together with the description serve to explain the invention without limiting the invention. In the drawings:

FIG. 1 is a cross-sectional view of some embodiments of the compressor of the present invention;

FIG. 2 is a schematic view of a first bearing of the compressor of FIG. 1;

FIG. 3 is a schematic structural view of a second bearing of the compressor of FIG. 1;

FIG. 4 is a schematic structural view of some embodiments of the inner race of the second bearing shown in FIG. 3.

Description of the reference numerals

1. A housing; 2. a rotor; 3. a stator; 4. a first bearing housing; 5. a first bearing; 6. a second bearing housing; 7. a second bearing; 9. a spacer assembly; 9' and a spacer; 10. a bearing gland; 10', a locking nut;

11. a refrigerant outlet; 12. a guide groove; 13. a refrigerant inlet; 14. a second spigot; 21. a first shaft section; 22. a second shaft section; 23. a third shaft section; 24. a guide section; 31. an aperture; 41. a first mounting hole; 51. a bearing housing; 52. a bump foil; 53. a top foil; 61. a second mounting hole; 611. a first bore section; 612. a second bore section; 62. a first spigot; 71. an inner ring; 711. an inner ring section; 712. an elastic element; 713. mounting grooves; 72. an outer ring; 73. a rolling body; 74. a holder; 81. a bleed air passage; 82. a pressure chamber; 82', subcavities.

Detailed Description

The present invention is described in detail below. In the following paragraphs, different aspects of the embodiments are defined in more detail. Aspects so defined may be combined with any other aspect or aspects unless clearly indicated to the contrary. In particular, any feature considered to be preferred or advantageous may be combined with one or more other features considered to be preferred or advantageous.

The terms "first", "second", and the like in the present invention are merely for convenience of description to distinguish different constituent elements having the same name, and do not denote a sequential or primary-secondary relationship.

The present invention improves a rotor assembly for a centrifugal compressor. For the convenience of describing the improvement point of the present invention, the overall structure of the centrifugal compressor will be explained below.

As shown in fig. 1, the two-stage centrifugal compressor is exemplified and includes a housing 1, a rotor 2, and a stator 3. The rotor 2 and the stator 3 form a motor and are arranged in the shell 1, the stator 3 is a rotary part and is provided with a winding and fixed on the shell 1 through tight fit so as to enable the rotor 2 to rotate at a high speed through generating a magnetic field, the stator 3 is sleeved outside the rotor 2 and is positioned in the middle area of the rotor 2 along the axial direction, and the rotor 2 and the stator 3 are in clearance fit.

The two ends of the housing 1 along the axial direction are respectively connected with a first volute and a second volute to form a compressor housing together. The compressor housing is irregular in shape and can be formed by casting, and mainly plays a role in supporting and fixing the stator 3 and the bearing seat. Casing 1 can be cylindric structure, and stator 3 and casing 1 tight fit, rotor 2 establish the central point at casing 1 and put, and rotor 2's both ends set up an impeller respectively, and the inner of impeller sets up the diffuser, and when the impeller was rotatory at a high speed, gas was along with rotatory, and under the centrifugal force effect, the gas was thrown to the back diffuser and is carried out the diffusion, can turn into the pressure energy with the speed of impeller export medium, and the gas after the pressure improvement is discharged from the spiral case.

The working principle of the compressor is as follows: during the working process of the compressor, the rotor 2 rotates at a high speed, gas enters the diffuser through the left impeller, the gas enters the first volute after being compressed at the first stage, the exhaust passage on the first volute guides the compressed gas to the right impeller, the compressed gas enters the right diffuser after the centrifugal action of the right impeller, and the gas enters the second volute after being compressed at the second stage and is exhausted out of the compressor through the exhaust passage on the second volute.

In order to cool the stator 3 during the operation of the compressor, a refrigerant inlet 13 and a refrigerant outlet 11 are formed in the sidewall of the casing 1, and a spiral guide groove 12 is formed in the inner wall of the casing 1 to guide the refrigerant from the motor cavity on the first side of the stator 3 to the motor cavity on the second side, thereby cooling the stator 3 during the flowing process. The gaseous refrigerant formed by cooling the stator 3 returns from the gap between the stator 3 and the rotor 2 to cool the rotor 2. The liquid refrigerant that has not been completely gasified after cooling the stator 3 returns to the motor cavity on the first side through the hole 31 provided in the stator 3 in the axial direction, and is discharged out of the motor cavity through the refrigerant outlet 11.

In order to support the rotor 2, the two ends of the rotor 2 are respectively provided with a first bearing 5 for bearing the radial force applied when the rotor 2 works, and the first bearings 5 are radial bearings, and are dynamic pressure gas bearings and supported by a first bearing seat 4, the first bearing seat 4 can be fixed on the shell 1, and the stator 3 is axially positioned between the two first bearings 5.

As shown in fig. 2, the hydrodynamic gas bearing includes, from the outside to the inside: a bearing housing 51, a flexible bump foil 52 and a top foil 53. A dynamic pressure gas film is formed between the top foil 53 and the rotor 2, and when a wedge-shaped structure is formed between the top foil 53 and the rotor 2 rotating at a high speed, the rotor 2 drives gas to move due to gas viscosity, the gas is compressed in the wedge-shaped area, a gas film high pressure is formed, and the rotor 2 is supported to stably operate. When the dynamic pressure gas film is formed, the rotation direction of the rotor 2 is directed from the non-fixed ends of the bump foil 52 and the top foil 53 to the fixed ends so as to satisfy the condition that the gas flows from the large section into the small section, as indicated by the arrow θ.

When the discharge pressure recoils due to an abnormal compressor control program or an abnormal shutdown, there is a possibility that the rotor 2 rotates in the reverse direction, at which time it is difficult to form a stable gas film and the dynamic pressure gas bearing fails. Moreover, during the start-up and shutdown of the compressor, the inner surface of the top foil 53 is in dry frictional contact with the rotor 2 due to the absence of the formation of the film of the hydrodynamic gas bearing, which further increases the wear of the first bearing 5 during frequent start-up and shutdown, and reduces the life. In addition, the dynamic pressure gas bearing realizes oilless, which means that the lubricating oil medium is changed into refrigerant gas with oil, and the gas viscosity is only one thousandth of the oil viscosity, so that the dynamic pressure gas bearing has small support rigidity and low bearing capacity, and when the rotor 2 works at low speed, the gas film bearing capacity is low, so that the bearing capacity is low, and the shafting is unstable.

In order to improve the operational stability of the rotor 2 when the first bearing 5 is in the above-mentioned various unstable operating states, the rotor assembly of the present invention includes a first bearing 5 and a second bearing 7, both mounted to the rotor 2. The first bearing 5 is a gas dynamic pressure bearing, the second bearing 7 is a rolling bearing, and as shown in fig. 3, the rolling bearing includes an inner ring 71, an outer ring 72, and a rolling body 73 disposed between the inner ring 71 and the outer ring 72, a radial dimension of the inner ring 71 is adjustable, and specifically, the radial dimension is adjustable according to an operation condition of the rotor 2. As shown in fig. 3, the rolling bodies 73 may be provided on a cage 74. The rolling bearing belongs to a contact bearing, has sensitive starting, high bearing capacity, stable rigidity, simple arrangement and lower cost, and can ensure that a shaft system can stably run at low speed.

As shown in fig. 1, the rotor assembly may further include a second bearing housing 6, the second bearing housing 6 being fixedly disposed for supporting the rotor 2 through a second bearing 7. The outer ring 72 of the second bearing 7 and the second bearing seat 6 are tightly matched, for example, the interference is 40-60 μm.

The embodiment can flexibly adjust the supporting state of the bearing to the rotor under different operation conditions of the rotor, thereby improving the operation stability of the rotor and the bearing capacity of the bearing, preventing the first bearing from abnormal abrasion and avoiding dry friction between the inner surface of the top foil 53 of the dynamic pressure gas bearing and the rotor 2.

Further, the rotor assembly of the present invention may further include an adjusting component, which is configured to combine the inner ring 71 with the rotor 2 when the rotor 2 is in a working condition of starting, stopping, reversing or low rotation speed, etc., so that the first bearing 5 is in an unstable working state, for example, a tight fit is formed between the inner ring 71 and the rotor 2, so as to support the rotor 2 through the second bearing 7, and at this time, the instability phenomenon of the rotor 2 is prevented by using the characteristics of sensitive starting, high bearing capacity and stable rigidity of the rolling bearing; and when the rotor 2 is in a high-rotating-speed working condition and the first bearing 5 is in a stable working state, the inner ring 71 is separated from the rotor 2 so as to support the rotor 2 through the first bearing 5, and at the moment, the friction loss is small, the rotation precision is high, and the rotor stability is good.

The rotor assembly can flexibly adjust the supporting state of the bearing to the rotor 2 under different operation conditions of the rotor 2, so that the operation stability of the rotor 2 and the bearing capacity of the bearing are improved. The high rotation speed and the low rotation speed are distinguished by a rotation speed at which the first bearing 5 can establish a stable air film or a rotation speed at which the rotor 2 can be suspended.

When the first bearing 5 is in an unstable working state, for example, during the starting process of the compressor, a stable air film is not established before the first bearing 5 and the rotor 2, at this time, because the inner ring 71 of the second bearing 7 is connected with the rotor 2 and the outer ring 72 is in tight fit with the second bearing seat 6, the second bearing 7 preferentially and independently supports the rotor 2, and the problem that the bearing capacity of the dynamic pressure air bearing is low at a low rotating speed can be solved. When the first bearing 5 is in a stable working state, the inner ring 71 of the second bearing 7 is separated from the rotor 2, the first bearing 5 mainly supports the rotor 2, and the vibration amplitude of the rotor 2 is small due to the superiority of the dynamic pressure gas bearing in the positioning precision, so that the working stability of the rotor can be improved.

As shown in fig. 1, a first gap is formed between the first bearing 5 and the rotor 2, and a second gap is formed between the inner race 71 and the rotor 2 when the first bearing 5 is in a stable operating state, the second gap being larger than the first gap. Therefore, the rotor 2 can be independently supported by the first bearing 5 under the working condition of high rotating speed, the second bearing 7 is prevented from participating in supporting due to precision errors, and the advantages of small friction loss, high rotating precision and good rotor stability of the dynamic pressure gas bearing are fully utilized.

Alternatively, the second gap may be not larger than the first gap, and the amplitude of the rotor 2 is small due to the advantage of the dynamic pressure gas bearing in terms of positioning accuracy, and the amplitude is smaller than the internal gap of the rolling bearing, so that the rolling bearing is equivalently in a suspended state, and the first bearing 5 plays a main supporting role for the rotor 2.

As shown in fig. 4, the inner race 71 includes: at least two inner ring segments 711 and at least two elastic elements 712, such as springs, are circumferentially arranged, the elastic elements 712 being connected between the ends of adjacent inner ring segments 711. When the inner ring 71 is combined with the rotor 2, the end parts of the adjacent inner ring sections 711 are abutted, and the abutting surface is K, so that the inner ring 71 and the rotor 2 form tight fit, and the holding force of each inner ring section 711 to the rotor 2 is increased; when the inner ring 71 is disengaged from the rotor 2, a third gap is provided between the ends of the adjacent inner ring segments 711 to expand the inner ring segments 711 by an increased radial dimension, thereby providing a second gap between the inner ring 71 and the rotor 2.

For example, in fig. 4, the inner ring 71 includes two inner ring segments 711 and two elastic members 712, wherein mounting grooves 713 are provided on both end surfaces of each inner ring segment 711, and both ends of the elastic members 712 are respectively connected to bottom surfaces of the mounting grooves 713 where the two inner ring segments 711 are close to each other. When the inner ring 71 is coupled with the rotor 2, the elastic member 712 is in a compressed state, and when the inner ring 71 is decoupled from the rotor 2, the elastic member 712 is in a free state.

As shown in fig. 3, the inner ring 71 is configured to receive a radial force exerted by externally introduced high-pressure gas; such as high-pressure gas outside the second bearing housing 6 or outside the housing 1, and an adjustment member for adjusting the pressure of the high-pressure gas to adjust the radial dimension of the inner race 71. For example, the adjusting component may include a pressure adjusting valve, etc., and the adjusting component may receive a control signal from the control component to automatically adjust or may manually adjust.

This embodiment makes it easy to actively adjust the radial dimension of the inner ring 71 by controlling the air pressure, to realize precise adjustment, and to provide a stable coupling force in a state where the inner ring 71 is coupled with the rotor 2, to prevent a slip from occurring between the rotor 2 and the inner ring 71. Alternatively, the radial dimension of the inner ring 71 may also be adjusted by means of high-pressure oil or a mechanical adjustment mechanism.

Further, the rotor assembly of the present invention may further include: rotation speed detecting means for detecting the rotation speed of the rotor 2; and a control means for causing the regulating means to increase the gas pressure to a first pressure value to couple the inner ring 71 with the rotor 2 when the rotation speed of the rotor 2 is in a first rotation speed section; when the rotation speed of the rotor 2 is in the second rotation speed interval, reducing the gas pressure to a second pressure value by the adjusting component so as to enable the inner ring 71 to be disengaged from the rotor 2; wherein, the first rotating speed interval is less than the second rotating speed interval, and the first pressure value is greater than the second pressure value.

In this embodiment, the operating state of the first bearing 5 can be objectively reflected by detecting the rotational speed of the rotor 2, so that the timing of adjusting the radial dimension of the inner race 71 of the second bearing 7 can be accurately determined.

As shown in fig. 1, the rotor assembly comprises a support unit provided at least one end of the rotor 2, the support unit comprising a first bearing 5 and a second bearing 7, i.e. each first bearing 5 is provided with a corresponding second bearing 7.

This structure can make rotor 2 when rotating under the low-speed operating mode, keeps the original mode of support of rotor 2 as far as possible, can improve the stability of rotor when low-speed and high-speed operating mode transition. The structure that all sets up the supporting element to rotor 2 both ends can keep the support mode that rotor 2 both ends were supported all the time, improves the bearing capacity of the stability of rotor 2 work and bearing. Preferably, the supporting units at both ends may be symmetrically disposed to improve the operational stability of the rotor 2.

As shown in fig. 1 and 3, the supporting unit includes: a first bearing 5; two second bearings 7 are arranged at intervals along the axial direction, and each second bearing 7 is arranged at the same side of the first bearing 5; a second bearing housing 6 for supporting the rotor 2 through each second bearing 7, the second bearing housing 6 being provided with a bleed air passage 81 for introducing external high-pressure gas; and a spacer assembly 9 provided between adjacent second bearings 7 and fixed to the inner race 71, a pressure chamber 82 being provided in the spacer assembly 9, the pressure chamber 82 being in communication with the bleed air passage 81 and configured to cause the high-pressure gas to apply a radial force to the inner race 71.

In this configuration, the high-pressure gas introduced from outside the second bearing housing 6 can act on the spacer assembly 9 to simultaneously apply radial forces to the two second bearings 7 in the same support unit, simplifying the bleed air structure. Moreover, because the spacing component 9 is positioned in the middle position between the two second bearings 7, the gas acting forces acting on the two second bearings 7 of the same supporting unit can be consistent, so that the adjustment synchronism and size consistency of the inner rings 71 of the two second bearings 7 are ensured, and when the first bearing 5 is in an unstable working state, each second bearing 7 can simultaneously support the rotor 2, so that the stress on each part of the rotor 2 is balanced; when the first bearing 5 is in a stable operating state, the second bearings 7 can be simultaneously disengaged from the rotor 2 so as not to affect the operation of the first bearing 5.

As shown in fig. 3, the support unit includes two second bearings 7, inner rings 71 of the two second bearings 7 are integrally formed with the spacer assembly 9, and outer rings 72 of the two second bearings 7 are respectively in contact with and slidably disposed on both side surfaces of the spacer assembly 9 in the axial direction. Since the second bearing 7 operates at low rotational speeds of the rotor 2, wear between the outer race 72 and the spacer assembly 9 can be reduced. Since the spacer elements 9 rotate with the inner ring 71, the pressure chamber 82 can be designed as an annular groove and the bleed air duct 81 can be designed as a bore, so that air can be supplied from the stationary second bearing block 6 to the rotating spacer elements 9 in order to supply air into the pressure chamber 82.

Because the inner rings 71 of the two second bearings 7 and the spacing component 9 are integrally formed, the width of the inner ring 71 of the second bearing 7 is increased, so that the stress is balanced when the inner ring 71 is combined with the rotor 2, the inner ring 71 is not easy to deflect, the length section of the contact between the inner ring 71 and the rotor 2 can be increased, and the binding force between the inner ring 71 and the rotor 2 is improved. In addition, the inner rings 71 of the two second bearings 7 and the spacer assembly 9 form an integral structure, which can improve assembly efficiency. Alternatively, the inner ring section 71 and the spacer assembly 9 may be fixed by means of bonding or fastening.

In some embodiments, inner race 71 includes: at least two inner ring segments 711 and at least two elastic elements 712 are circumferentially arranged, the elastic elements 712 being connected between ends of adjacent inner ring segments 711. Correspondingly, the spacer assembly 9 comprises at least two circular arc-shaped spacers 9 ', the pressure chamber 82 comprises at least two sub-chambers 82 ', each spacer 9 ' is arranged corresponding to each inner ring segment 711 in the circumferential direction, and each spacer 9 ' is provided with one sub-chamber 82 '.

When the ends of adjacent inner ring segments 711 are in abutting contact, the sub-chambers 82' are integrally formed as annular grooves into which the gas introduced from the gas introduction passages 81 enters to apply a radial force to the inner ring segments 711 to press the inner ring 71 against the rotor 2. When the air pressure is reduced to have the second gap between the inner ring 71 and the rotor 2, the sub-chambers 82 'cannot form a continuous annular groove, and the gap between the sub-chambers 82' can also assist the air pressure reduction.

As shown in fig. 1, the supporting unit includes at least two second bearings 7 arranged at intervals along the axial direction, and each second bearing 7 in the same supporting unit is arranged on the same side of the first bearing 5. This structure simplifies the positioning and supporting structure of the second bearing 7, and also facilitates the assembly and lubrication of the second bearing 7.

As shown in fig. 1, the second bearing 7 in the same support unit is located axially outside the first bearing 5. In this configuration, the first bearing 5 is closer to the motor cooling system, and can be lubricated and cooled by using a suitable amount of liquid refrigerant as a dynamic pressure gas bearing. Further, when the rolling bearing is used as the second bearing 7, wear is likely to occur after long-term use, and the provision of the second bearing outside the first bearing 5 is advantageous for maintenance or replacement of the rolling bearing. Optionally, the second bearing 7 in the same support unit is located axially inside the first bearing 5.

As shown in fig. 1, the rotor 2 includes: a first shaft section 21, a second shaft section 22 and a guide 24. Wherein, be equipped with first bearing 5 on the first shaft section 21, be equipped with second bearing 7 on the second shaft section 22, the diameter of second shaft section 22 is less than first shaft section 21. The guiding portion 24 is disposed at a connection position between the first shaft segment 21 and the second shaft segment 22, and is used for guiding the refrigerant on the first shaft segment 21 to the second shaft segment 22.

When the motor is cooled unevenly, part of liquid refrigerant is not gasified, and is accumulated in the motor cavity on the second side, when the rotor 2 rotates at high speed, the dynamic pressure gas bearing sucks the surrounding refrigerant medium, and the liquid refrigerant is sucked into the gap between the first bearing 5 and the rotor 2 along with the gaseous refrigerant. A proper amount of liquid refrigerant is beneficial to lubricating the bearing and reducing the temperature of the bearing, but when the liquid refrigerant is too much, liquid can accumulate inside the bearing, the space is occupied, the formation of a dynamic pressure air film is influenced, and the vibration amplitude of a shafting is increased.

Through setting up guide portion 24, can make the liquid refrigerant guide to second bearing 7 between first bearing 5 and the rotor 2, not only can prevent that liquid refrigerant from amassing in first bearing 5, do benefit to and establish stable air film, but also can improve the lubricated effect of second bearing 7.

For example, as shown in fig. 1, the outer contour of the guide portion 24 is a circular arc in the longitudinal section of the rotor 2, the radius of the circular arc is not R, the circular arc may be concave inward or convex outward, the liquid refrigerant may flow to the second bearing 7 under the guidance of the circular arc surface, and the liquid refrigerant may be accelerated and thrown toward the second bearing 7 by a centrifugal force in conjunction with the high-speed rotation of the rotor 2 during operation. Alternatively, the guide portion 24 may be sloped or stepped.

When at least two second bearings 7 are provided in the axial direction on the second shaft section 22, the liquid refrigerant accumulated in the first bearing 5 can flow to the respective second bearings 7 in sequence. For example, the second bearing 7 is a rolling bearing, and the liquid refrigerant in the first bearing 5 is guided to the inner rolling bearing and then continuously flows to the outer rolling bearing through the play between the balls.

Still referring to fig. 1, the rotor assembly further includes a housing 1, and the supporting unit may further include: the first bearing seat 4 is connected to the shell 1 and used for supporting the rotor 2 through a first bearing 5, and the first bearing 5 is connected with the first bearing seat 4 through tight fit; and a second bearing housing 6 connected to the first bearing housing 4 and independent from the housing 1 for supporting the rotor 2 through a second bearing 7.

The structure directly connects the second bearing seat 6 to the first bearing seat 4, the original structural form of the shell 1 does not need to be changed, and the volume of the second bearing seat 6 can be reduced. Further, the liquid refrigerant accumulated in the first bearing 5 can enter the second bearing 7 more through the closed cavity formed between the second bearing housing 6 and the rotor 2, and the liquid refrigerant accumulated in the first bearing 5 is prevented from flowing to other regions in the housing 1, thereby improving the lubricating effect of the second bearing 7.

As shown in fig. 1, the second bearing 7 is disposed outside the first bearing 5, one end of the second bearing seat 6 close to the first bearing seat 4 is provided with a first spigot 62, and one end of the first bearing seat 4 is embedded in the first spigot 62 and abuts against a bottom surface of the first spigot 62, so as to limit the degree of freedom of the first bearing seat 4 moving toward the second bearing seat 6 in the axial direction and simultaneously prevent the first bearing 5 from being pushed. This kind of structure can make the rotor subassembly compacter, and second bearing frame 6 can also carry on spacingly to first bearing frame 4 when supporting second bearing 7. Further, the second bearing housing 6 may be fixed to the first bearing housing 4 by fasteners.

Further, a second spigot 14 is provided on the inner side wall of the housing 1 for limiting the freedom of movement of the first bearing seat 4 in the axial direction towards and away from the second bearing seat 6. Thereby, the degrees of freedom of the first bearing housing 4 in both axial directions are restricted.

The first bearing seat 4 and the second bearing seat 6 can adopt a split structure, and are easy to process. Or, the first bearing seat 4 and the second bearing seat 6 are integrally formed, so that the assembly is convenient, and the coaxiality of the corresponding mounting holes of the first bearing 5 and the second bearing 7 is easy to improve.

The first bearing seat 4 is provided with a first mounting hole 41 along the axial direction for mounting the first bearing 5, and the first bearing 5 and the first mounting hole 41 adopt a tight fit, such as a transition fit or an interference fit. When the bearing works, the first bearing 5 utilizes the dynamic pressure gas film to realize precise support on the rotor 2 and parts on the shaft, and the radial runout can be less than 5 mu m. The second bearing seat 6 is provided with a second mounting hole 61 along the axial direction for mounting each second bearing 7 in the same supporting unit, the outer diameter of the second bearing 7 is D2, the inner diameter is D1, and the outer ring 72 of the second bearing 7 is tightly matched with the second mounting hole 61.

When including two at least second bearings 7 in the support element, can make adjacent second bearing 7 interval setting through setting up spacing subassembly 9, make the location of second bearing 7 more accurate, optimize the support effect, prevent to influence each other between the adjacent second bearing 7.

As shown in fig. 1, the second bearing seat 6 is a rotary structure, and includes a main body portion and a flange portion connected to the main body portion along an axial direction, and a first spigot 62 is provided on an end surface of the flange portion. The second bearing seat 6 is provided with a second mounting hole 61, the second mounting hole 61 is a stepped hole and includes a first hole section 611 and a second hole section 612, and a stepped surface is formed at a connection position of the first hole section 611 and the second hole section 612. The outer race of the innermost second bearing 7 of the same support unit abuts against the stepped surface and the inner race abuts against the thrust surface formed by the second shaft section 22 and the guide portion 24.

The supporting unit further includes: the rotor 2 further comprises a third shaft section 23, the third shaft section 23 is connected to one end, far away from the first shaft section 21, of the second shaft section 22, the diameter of the third shaft section 23 is smaller than that of the second shaft section 22, the outer ring of the second bearing 7 located on the outermost side in the same supporting unit is limited through the bearing gland 10, and the inner ring of the second bearing is limited through the locking nut 10'. After the bearing gland 10 and the lock nut 10' are installed, the axial clearance s between the bearing gland and the second bearing 7 can be controlled to be 30-50 mu m.

Because the pressure of the air outlet is greater than the pressure of the air inlet when the impeller of the compressor does work on the refrigerant in the working process, the pressure difference can generate axial force and radial force, and in order to balance the axial force applied to the rotor 2, the second bearing 7 can adopt an angular contact rolling bearing. Therefore, a thrust disc and a gas thrust bearing can be omitted from the compressor, the structure can be simplified, the working reliability of the bearing is improved, and the cost is reduced.

When the exhaust pressure is backflushed due to abnormal program or abnormal shutdown, the rotor 2 can rotate reversely, the first bearing 5 cannot form an air film and fails, the second bearing 7 works, and the angular contact type rolling bearing can simultaneously bear the axial force and the radial force applied to the rotor 2.

The angular contact rolling bearing can adopt at least one of the following arrangement modes:

first, both ends of rotor 2 respectively are equipped with a supporting element, all include a first bearing 5 and a second bearing 7 in every supporting element, and second bearing 7 in the supporting element of both ends is the reverse installation. Since the axial force is related to the structure and the rotating speed of the rotor 2 and the working condition of the compressor, the direction of the axial force is uncertain, and the structure can balance the axial force applied to the rotor 2 in two directions simultaneously.

And secondly, two ends of the rotor 2 are respectively provided with a supporting unit, each supporting unit comprises a first bearing 5 and at least two second bearings 7, each second bearing 7 in the same supporting unit is installed in the same direction, and the second bearings 7 in the supporting units at the two ends are installed in opposite directions. The structure can balance the axial force of the rotor 2 in two directions and improve the bearing capacity by increasing the number of the second bearings 7.

And thirdly, two ends of the rotor 2 are respectively provided with a supporting unit, each supporting unit comprises a first bearing 5 and two second bearings 7, and the two second bearings 7 in the same supporting unit are reversely installed. The structure can balance the axial force of the rotor 2 in two directions through one supporting unit, can prevent the axial force received by one end of the rotor 2 from being transmitted to the other end, and can prolong the service life of each component in the shafting.

In order to improve the installation accuracy of the rotor assembly, in some embodiments, during the processing of the rotor assembly, the first bearing seat 4, the second bearing seat 6 and the housing 1 may be assembled into an assembly, the assembly is positioned and clamped on a processing device, and then the first installation hole 41 and the second installation hole 61 are processed to a preset size by one-time positioning and clamping.

Through processing under the state at first bearing frame 4, second bearing frame 6 and casing 1 location and formation assembly, the installation accuracy of bearing is guaranteed to the machining accuracy of accessible assembly, through a location clamping, can adopt unified processing benchmark moreover to guarantee the axiality of each first mounting hole 41 and second mounting hole 61, improve positioning accuracy, make rotor 2 work more stable.

For example, each of the first mounting holes 41 and each of the second mounting holes 61 may be machined in sequence to a preset size from one side of the housing 1 in the axial direction. Each first mounting hole 41 and each second mounting hole 61 can be processed by adopting a boring mode, and the processing cutter is sequentially processed from one side of the shell 1 by axial feeding, so that the processing efficiency can be improved, the coaxiality of each first mounting hole 41 and each second mounting hole 61 can be further improved, the positioning precision is improved, and the rotor 2 can work more stably.

The step of assembling the first bearing housing 4, the second bearing housing 6 and the housing 1 as a combination comprises: the first bearing seat 4 is matched with the second bearing seat 6 through the first spigot 62, and the first bearing seat 4 is matched with the shell 1 through the second spigot 14 to perform first repositioning, wherein the sequence of the two matching assembly links is not limited; fixing the first bearing seat 4 and the second bearing seat 6, and the first bearing seat 4 and the shell 1 through fasteners; after being fixed by the fasteners, pins are pinned between the first bearing block 4 and the second bearing block 6, and between the first bearing block 4 and the housing 1, for a second repositioning.

After the first spigot 62 and the second spigot 14 are initially positioned, the position relation of the first bearing seat 4, the second bearing seat 6 and the shell 1 is restrained through the fasteners, on the basis of the original pin holes, the pin holes are formed between the first bearing seat 4 and the second bearing seat 6 and between the first bearing seat 4 and the shell 1 in a matched mode, pins are inserted into the pin holes, the pins can be used for preventing position change of all parts caused by large cutting force in the machining process, and accurate positioning can also be provided for the subsequent product assembling process. By adopting double positioning, the mounting accuracy between the first bearing seat 4, the second bearing seat 6 and the housing 1 can be accurately ensured, thereby improving the coaxiality of the first bearing 5 and the second bearing 7.

After the completion of the processing, the combined body is disassembled to mount the first bearing 5 and the second bearing 7 in a state where the housing 1, the first bearing housing 4, and the second bearing housing 6 are separated. In the assembling process, the assembling precision of the first bearing 5 and the second bearing 7 can be ensured by the spigot and pin dual positioning mode, and the stability of the bearing rotor system is improved.

The rotor assembly of the invention adopts a multi-bearing cooperation working mode, and can realize high-precision operation of the compressor at both low rotating speed and high rotating speed stages. The characteristics of sensitive starting, high bearing capacity and stable rigidity of the rolling bearing are utilized, and the rolling bearing is tightly matched with the rotor 2, so that the rotor 2 can be supported by the rolling bearing at a low rotating speed, and the rotating precision of the rotor 2 is 10-30 mu m. Simultaneously, four angle contact bearings are unilateral in pairs use, both sides symmetrical arrangement, can improve bearing capacity on the one hand like this, and on the other hand also effectively balances the axial force that shafting and bearing self produced. When the rotating speed of the compressor is increased, the dynamic pressure effect is more obvious along with the increase of the speed, a dynamic pressure gas film is gradually formed, the dynamic pressure gas bearing gradually plays a supporting role, after the dynamic pressure gas film is completely formed, the vibration amplitude of the rotor is smaller than 5 micrometers due to the high stability of the gas film, the dynamic pressure gas bearing works independently, the rolling bearing does not work, and the high-precision operation at a high rotating speed is realized.

The invention also provides a compressor, such as a centrifugal compressor, comprising the rotor assembly of the above embodiment. The rotor assembly of the invention can improve the running stability of the rotor in each working state and the bearing capacity of the bearing, thereby optimizing the working performance of the centrifugal compressor and prolonging the service life, and moreover, the rotor can stably rotate and reduce the noise generated in the working process of the compressor. In addition, the rotor assembly of the present invention may also be used in an electric machine.

The specific working flow of the compressor is as follows:

when the compressor is at rest, the inner ring 71 of the second bearing 7 is tightly fitted with the rotor 2 due to the air pressure to ensure the compressor starting condition, at which time the rotor 2 is supported by the second bearing 7.

When the compressor is operated at a low rotation speed, the control gas pressure is increased to tightly fit the rotor 2 with the inner race 71 to support the rotor 2 to operate at the low rotation speed through the second bearing 7.

As the compressor is gradually accelerated, the center of gravity of the rotor 2 gradually rises, and then the inner ring 71 is driven to move together, at this time, the control air pressure is gradually reduced through the adjusting component, the inner ring 71 expands outwards under the action of the elastic element 713 and gradually loosens the rotor, and after the rotor 2 reaches a certain rotating speed, the rotor 2 is suspended in a self-adaptive manner due to the rigid air film formed between the rotor 2 and the first bearing 5, so that the rotor 2 is supported by the first bearing 5 to operate at a high rotating speed.

When the compressor is suddenly stopped or actively decelerated during high-speed operation, when the speed gradually approaches the rotor suspension speed, the control air pressure gradually increases, for example, linearly increases, so that the inner ring 71 gradually approaches the rotor 2 due to the gradual disappearance of the dynamic pressure effect, when the speed of the rotor 2 is in the first rotation speed range, that is, below the suspension speed, the inner ring 71 holds the rotor 2 tightly under the action of the air pressure, the dynamic pressure gas bearing loses the gas film supporting function, and the rotor 2 runs to the stop under the support of the second bearing 7. So far, the compressor is starting to stopping in the whole cycle, does not have direct contact between rotor 2 and the first bearing 5, does not have the friction risk, improves unit operational reliability and bearing life-span.

Furthermore, the compressor can be operated at high precision in both low and high rotation speed stages. The rolling bearing is used for supporting a shaft system at a low rotating speed by utilizing the characteristics of sensitive starting, high bearing capacity and stable rigidity of the rolling bearing, and the rotating precision is 10-30 mu m. Meanwhile, 4-angle contact bearings are adopted, a single side is used in pairs, and two sides are symmetrically arranged, so that bearing load can be improved on one hand, and axial force generated by a shaft system and the bearings can be effectively balanced on the other hand. When the rotating speed of the compressor is increased, the dynamic pressure effect is more obvious along with the increase of the speed, a dynamic pressure air film is gradually formed, the first bearing 5 gradually plays a supporting role, after the dynamic pressure air film is completely formed, the vibration amplitude of the rotor 2 is smaller than 5 micrometers due to the high stability of the air film, at the moment, the first bearing 5 works independently, the second bearing 7 does not work, and the high-precision operation at the high rotating speed is realized.

The invention also provides air conditioning equipment comprising the compressor of the embodiment. The air conditioning equipment has higher working stability and reliability.

The invention also provides a working method of the rotor assembly based on the above embodiments, and in some embodiments, the working method comprises the following steps:

step 101, determining the working state of the first bearing 5;

and 102, adjusting the radial size of the inner ring 71 according to the working state of the first bearing 5.

Wherein, step 101 can be executed by the control component, and step 102 can be executed by the control component controlling the air pressure regulating valve.

In some embodiments, the step of determining 101 the operating state of the first bearing 5 comprises:

step 101A, detecting the rotating speed of the rotor 2;

step 101B, judging the interval of the rotating speed of the rotor 2, and determining that the first bearing 5 is in an unstable working state when the rotating speed of the rotor 2 is in the first rotating speed interval; when the rotation speed of the rotor 2 is in the second rotation speed interval, it is determined that the first bearing 5 is in the stable operation state. Wherein the first rotation speed interval is smaller than the second rotation speed interval.

In some embodiments, the step 102 of adjusting the radial dimension of the inner ring 71 according to the operating condition of the first bearing 5 comprises:

102A, when the first bearing 5 is in an unstable working state, increasing the gas pressure to a first pressure value through an adjusting part, and combining the inner ring 71 with the rotor 2 to support the rotor 2 through the second bearing 7;

and 102B, reducing the gas pressure to a second pressure value through the adjusting part when the first bearing 5 is in a stable working state, so that the inner ring 71 is disengaged from the rotor 2 to support the rotor 2 through the first bearing 5. Wherein the first pressure value is greater than the second pressure value.

The present invention provides a rotor assembly, a method for operating the same, a compressor, and an air conditioner. The principles and embodiments of the present invention are explained herein using specific examples, which are presented only to aid in understanding the method and its core concepts. It should be noted that, for those skilled in the art, it is possible to make various improvements and modifications to the present invention without departing from the principle of the present invention, and those improvements and modifications also fall within the scope of the claims of the present invention.

Claims

1. A rotor assembly, comprising:

a rotor (2); and

the bearing comprises a first bearing (5) and a second bearing (7), wherein the first bearing (5) is a dynamic pressure gas bearing, and the radial size of an inner ring (71) of the second bearing (7) relative to the rotor (2) can be adjusted according to the working state of the first bearing (5).

2. The rotor assembly of claim 1, further comprising:

an adjustment member configured to couple the inner ring (71) with the rotor (2) to support the rotor (2) through the second bearing (7) when the first bearing (5) is in an unstable operating state; and disengaging the inner ring (71) from the rotor (2) when the first bearing (5) is in a stable operating state, to support the rotor (2) by the first bearing (5).

3. The rotor assembly according to claim 2, wherein the first bearing (5) has a first clearance with the rotor (2), and wherein the inner ring (71) has a second clearance with the rotor (2) when the first bearing (5) is in a steady state operation, the second clearance being greater than the first clearance.

4. The rotor assembly according to claim 1, wherein the inner ring (71) comprises:

at least two inner ring segments (711) arranged in the circumferential direction; and

at least two elastic elements (712), the elastic elements (712) being connected between ends of adjacent inner ring segments (711);

wherein, when the inner ring (71) is combined with the rotor (2), the end parts of the adjacent inner ring sections (711) are abutted; when the inner ring (71) is disengaged from the rotor (2), a third gap is formed between the ends of the adjacent inner ring segments (711).

5. The rotor assembly according to claim 1, wherein the inner ring (71) is configured to receive a radial force exerted by an externally introduced high pressure gas;

the rotor assembly further comprises an adjustment means for adjusting the pressure of the high pressure gas to adjust the radial dimension of the inner ring (71).

6. The rotor assembly of claim 5, further comprising:

a rotational speed detection means for detecting a rotational speed of the rotor (2); and

control means for causing adjustment means to increase a gas pressure to a first pressure value to engage the inner ring (71) with the rotor (2) when a rotation speed of the rotor (2) is in a first rotation speed zone; when the rotating speed of the rotor (2) is in a second rotating speed interval, reducing the gas pressure to a second pressure value by using an adjusting part so as to enable the inner ring (71) to be disengaged from the rotor (2); the first rotating speed interval is smaller than the second rotating speed interval, and the first pressure value is larger than the second pressure value.

7. The rotor assembly according to claim 1, characterized by comprising a support unit provided at least one end of the rotor (2), the support unit comprising the first bearing (5) and the second bearing (7).

8. The rotor assembly of claim 7, wherein the support unit comprises:

the first bearing (5);

the two second bearings (7) are arranged at intervals along the axial direction, and each second bearing (7) is arranged on the same side of the first bearing (5);

the second bearing block (6) is used for supporting the rotor (2) through the second bearings (7), and a gas introducing channel (81) is arranged on the second bearing block (6) and used for introducing external high-pressure gas; and

the spacing assembly (9) is arranged between the adjacent second bearings (7) and fixed with the inner ring (71), a pressure cavity (82) is arranged in the spacing assembly (9), the pressure cavity (82) is communicated with the air bleed channel (81), and the spacing assembly is configured to enable high-pressure air to exert radial force on the inner ring (71).

9. The rotor assembly according to claim 8, wherein the inner rings (71) of the two second bearings (7) are integrally formed with the spacer assembly (9), and the outer rings (72) of the two second bearings (7) are respectively in contact with and slidably disposed on both sides of the spacer assembly (9) in the axial direction.

10. The rotor assembly according to claim 7, characterized in that the second bearing (7) in the same support unit is located axially outside the first bearing (5).

11. The rotor assembly according to claim 1, wherein the rotor (2) comprises:

the first shaft section (21), the first bearing (5) is arranged on the first shaft section (21);

the second shaft section (22) is provided with the second bearing (7), and the diameter of the second shaft section (22) is smaller than that of the first shaft section (21); and

and a guide portion (24) which is arranged at the joint of the first shaft section (21) and the second shaft section (22) and is used for guiding the refrigerant on the first shaft section (21) to the second shaft section (22).

12. The rotor assembly according to claim 11, characterized in that the outer contour of the guide (24) is rounded, sloped or stepped in the longitudinal section of the rotor (2).

13. The rotor assembly according to claim 7, further comprising a housing (1), the support unit further comprising:

a first bearing housing (4) connected to the housing (1) for supporting the rotor (2) by means of the first bearing (5); and

a second bearing block (6) connected to the first bearing block (4) and independent from the housing (1) for supporting the rotor (2) through the second bearing (7).

14. The rotor assembly of claim 13,

one end, close to the first bearing seat (4), of the second bearing seat (6) is provided with a first spigot (62) used for limiting the freedom degree of the first bearing seat (4) moving towards the second bearing seat (6) along the axial direction and carrying out thrust on the first bearing (5); and/or

And a second spigot (14) is arranged on the inner side wall of the shell (1) and used for limiting the degree of freedom of the first bearing seat (4) moving towards the direction far away from the second bearing seat (6) along the axial direction.

15. The rotor assembly according to claim 1, characterized in that the second bearing (7) comprises an angular contact rolling bearing.

16. A compressor comprising a rotor assembly as claimed in any one of claims 1 to 15.

17. An air conditioning apparatus, characterized by comprising the compressor of claim 16.

18. A method of operating a rotor assembly as claimed in any one of claims 1 to 15, comprising:

-determining the working condition of the first bearing (5);

-adjusting the radial dimension of the inner ring (71) according to the operating condition of the first bearing (5).

19. Operating method according to claim 18, characterized in that the step of adjusting the radial dimension of the inner ring (71) according to the operating conditions of the first bearing (5) comprises:

when the first bearing (5) is in an unstable working state, increasing the gas pressure to a first pressure value through an adjusting component, and combining the inner ring (71) and the rotor (2) to support the rotor (2) through the second bearing (7);

when the first bearing (5) is in a stable working state, reducing the gas pressure to a second pressure value through the adjusting component, and disengaging the inner ring (71) from the rotor (2) so as to support the rotor (2) through the first bearing (5), wherein the second pressure value is smaller than the first pressure value.

20. Operating method according to claim 18, characterized in that the step of determining the operating condition of the first bearing (5) comprises:

detecting the rotational speed of the rotor (2);

judging the interval of the rotating speed of the rotor (2), and determining that the first bearing (5) is in an unstable working state when the rotating speed of the rotor (2) is in a first rotating speed interval; and when the rotating speed of the rotor (2) is in a second rotating speed interval, determining that the first bearing (5) is in a stable working state, wherein the first rotating speed interval is smaller than the second rotating speed interval.