Rotating machine

Abstract

To provide a rotating machine that can reduce a load to be received by an emergency bearing.SOLUTION: A rotating machine comprises: a rotating shaft extending in the direction of an axis; an electric motor for rotating and driving the rotating shaft around the axis; a radial magnetic bearing for supporting an outer peripheral surface of the rotating shaft in a non-contact state; an emergency bearing for supporting the rotating shaft when the radial magnetic bearing is not operated; and a lubricating layer provided in a circumferential direction on at least one of the outer peripheral surface of the rotating shaft and an inner peripheral surface of the emergency bearing, and including a solid lubricant.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present disclosure relates to rotary machines. [Background technology]

[0002] A known structure for rotating machines, such as turbo compressors used in turbo chillers, is to support the rotating shaft, to which the rotor of the electric motor is fixed, in a non-contact manner using radial magnetic bearings. The magnetic bearings are equipped with multiple electromagnetic coils, and the rotating shaft is supported by the attractive force of the electromagnetic coils. Rotating machines equipped with radial magnetic bearings generally have emergency bearings (auxiliary bearings, touchdown bearings) that support the rotating shaft when the radial magnetic bearing stops or experiences an abnormality.

[0003] For example, Patent Document 1 discloses a compressor that includes a magnetic bearing as the main bearing that supports the rotating shaft and uses a greaseless rolling bearing as the auxiliary bearing. By using a greaseless rolling bearing, the performance of the rolling bearing can be maintained even when a refrigerant that dissolves grease is used. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2021-161923 Summary of the Invention [Problem to be solved by the invention]

[0005] However, in the technology described in Patent Document 1, the impact load applied to the emergency bearing and the centrifugal force caused by whirling are large when touching down, so the load received by the emergency bearing is large.

[0006] The present disclosure has been made to solve the above-mentioned problems, and has an object to provide a rotating machine that can reduce the load that an emergency bearing receives. [Means for solving the problem]

[0007] In order to solve the above problems, the rotating machine of the present disclosure includes a rotating shaft extending in an axial direction, an electric motor that drives the rotating shaft to rotate around the axis, a radial magnetic bearing that supports the outer peripheral surface of the rotating shaft in a non-contact manner, an emergency bearing that supports the rotating shaft when the radial magnetic bearing is not operating, and a lubricating layer that contains a solid lubricant and is provided circumferentially on at least one of the outer peripheral surface of the rotating shaft and the inner peripheral surface of the emergency bearing. [Effects of the Invention]

[0008] According to the rotary machine of the present disclosure, the load on the emergency bearing can be reduced. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a vertical cross-sectional view showing an overall configuration of a turbo compressor as a rotary machine according to an embodiment of the present disclosure. [Figure 2] FIG. 2 is an enlarged view of a main part of FIG. [Figure 3] FIG. 2 is an enlarged longitudinal sectional view of a main portion showing an overall configuration of a turbo compressor as a rotary machine according to a first modified example of the first embodiment of the present disclosure. [Figure 4] FIG. 10 is an enlarged longitudinal sectional view of a main portion showing the overall configuration of a turbo compressor as a rotary machine according to a second modified example of the first embodiment of the present disclosure. [Figure 5] FIG. 4 is an enlarged longitudinal sectional view of a main portion showing the overall configuration of a turbo compressor as a rotary machine according to a second embodiment of the present disclosure. [Figure 6] FIG. 10 is an enlarged longitudinal sectional view of a main portion showing the overall configuration of a turbo compressor as a rotary machine according to a third embodiment of the present disclosure. [Figure 7] FIG. 10 is a cross-sectional view showing the configuration of an emergency bearing and a rotating shaft according to a fourth embodiment of the present disclosure, as viewed from the axial direction. DETAILED DESCRIPTION OF THE INVENTION

[0010] First Embodiment Hereinafter, a first embodiment of a turbo compressor as a rotary machine according to the present disclosure will be described in detail with reference to FIGS. 1 and 2. FIG.

[0011] <Overall configuration of turbo compressor> The turbo compressor shown in FIG. 1 is used in turbo chillers, turbo heat pumps, etc., and has the function of compressing low-pressure refrigerant gas into high-pressure refrigerant gas to circulate it within a refrigeration cycle. The turbo compressor includes a rotating shaft 10, a casing 20, an impeller 30, an electric motor 40, a main bearing device 70, an emergency bearing 80, a bearing-side lubricating layer 90, and a rotating-shaft-side lubricating layer 91.

[0012] <Rotation axis> The rotating shaft 10 is a cylindrical member that extends along an axis O that extends in the horizontal direction. The rotating shaft 10 is rotatable around the axis O.

[0013] <Casing> The casing 20 is a component that constitutes the outer shell of the turbo compressor. The casing 20 is provided to surround the rotating shaft 10 from the outer circumferential side and both sides in the direction of the axis O. An area on one side in the direction of the axis O of the space inside the casing 20 (the left side in FIG. 1) is an electric motor chamber 21 that is an enclosed space. An area on the other side in the direction of the axis O of the space inside the casing 20 (the right side in FIG. 1) is a compression chamber 22 that is separated from the electric motor chamber 21. An intake portion 23 that connects the inside and outside of the compression chamber 22 in the direction of the axis O is formed at the end of the casing 20 on one side in the direction of the axis O.

[0014] <Impeller> The impeller 30 is a member for compressing low-pressure refrigerant gas introduced from the space outside the casing 20 by the suction portion 23 into high-pressure refrigerant gas. The impeller 30 is provided inside the compression chamber 22 in the casing 20, at the end of the rotating shaft 10 on the other side in the direction of the axis O. An inlet vane 31 is provided on the other side in the direction of the axis O of the impeller 30.

[0015] <Electric motor> The electric motor 40 is a member for driving the rotary shaft 10 to rotate about the axis O. The electric motor 40 is provided in the electric motor chamber 21, and has a rotor 50 and a stator 60. The rotor 50 is a member that receives power for driving the rotating shaft 10 to rotate about the axis O, and rotates the rotating shaft 10. The rotor 50 has a rotor core 51 and a permanent magnet 52. The rotor 50 is fixed integrally to the outer peripheral surface of the rotary shaft 10. A plurality of permanent magnets 52 are provided inside the rotor 50 and spaced apart in the circumferential direction.

[0016] The stator 60 is a member for applying power to drive the rotating shaft 10 to rotate about the axis O. The stator 60 has a stator core 61 and a coil 62. The stator core 61 is provided radially outside the rotor 50 with a clearance therebetween so as to surround the rotor 50 from the outer periphery side. A plurality of coils 62 are provided on the stator core 61 at intervals in the circumferential direction.

[0017] <Main bearing unit> The main bearing device 70 is a member for rotatably supporting the rotating shaft 10 without contact. The main bearing device 70 is provided inside the motor chamber 21. The main bearing device 70 has a radial magnetic bearing 71, a thrust collar 72, and a thrust magnetic bearing 73.

[0018] The radial magnetic bearings 71 are members that magnetically levitate the rotating shaft 10 and rotatably support the rotating shaft 10 without contact. The radial magnetic bearings 71 are arranged concentrically with the rotating shaft 10 in the space inside the motor chamber 21, and are provided so as to cover the outer circumferential surface of the rotating shaft 10. A pair of radial magnetic bearings 71 is provided on both sides of the rotor 50 in the direction of the axis O.

[0019] The thrust collar 72 and thrust magnetic bearing 73 are members for supporting the rotating shaft 10 in the direction of the axis O so that the rotating shaft 10 can rotate without contact. The thrust collar 72 contains a magnetic material and is fixed to one end of the rotating shaft 10 in the direction of the axis O. The thrust magnetic bearing 73 is provided so as to sandwich the thrust collar 72 in the direction of the axis O.

[0020] <Emergency bearing> The emergency bearing 80 is a member for supporting the rotating shaft 10 when the radial magnetic bearing 71 is not in operation. The emergency bearings 80 are provided on the outer periphery of the rotating shaft 10 in the space inside the motor chamber 21. A pair of emergency bearings 80 are provided so as to sandwich the pair of radial magnetic bearings 71 from the direction of the axis O.

[0021] The emergency bearing 80 has an outer ring 81 , an inner ring 82 , a cage 83 , and rolling elements 84 . The outer ring 81 constitutes an outer peripheral portion of the emergency bearing 80. The outer ring 81 has an annular shape that surrounds the axis O on the outer peripheral side of the rotating shaft 10.

[0022] The inner ring 82 constitutes the inner peripheral portion of the emergency bearing 80. The inner ring 82 is annular and surrounds the rotating shaft 10 radially inward of the outer ring 81. The inner ring 82 is arranged coaxially with the outer ring 81. The inner ring 82 is arranged radially with a clearance from the rotating shaft 10 supported by the radial magnetic bearing 71. The dimension of the inner ring 82 in the direction of the axis O is the same as the dimension of the outer ring 81 in the direction of the axis O. The radial thickness of the inner ring 82 is the same as the thickness of the outer ring 81 in the direction of the axis O.

[0023] The inner diameter of the inner ring 82 is smaller than the inner diameter of the radial magnetic bearing 71. As a result, the radial dimension of the clearance between the emergency bearing 80 and the rotating shaft 10 is set smaller than the radial dimension of the clearance between the radial magnetic bearing 71 and the rotating shaft 10. Note that when the rotating shaft 10 is supported by the radial magnetic bearing 71, the rotating shaft 10 does not come into contact with the emergency bearing 80.

[0024] The cage 83 is an annular member disposed between the outer ring 81 and the inner ring 82. The cage 83 is disposed coaxially with the outer ring 81 and the inner ring 82. The cage 83 is provided with a receiving portion 83a that penetrates the cage 83 in the radial direction. A plurality of receiving portions 83a are provided at intervals in the radial direction. The receiving portion 83a is shaped like an elongated hole with the circumferential direction as the longitudinal direction.

[0025] The rolling elements 84 are provided between the outer ring 81 and the inner ring 82. A plurality of rolling elements 84 are provided at intervals in the circumferential direction. One rolling element 84 is accommodated in each of the accommodation portions 83a of the cage 83. The rolling elements 84 are able to roll in the circumferential direction while accommodated in the accommodation portions 83a between the outer ring 81 and the inner ring 82. The outer ring 81 and the inner ring 82 are able to rotate relative to each other in the circumferential direction via these rolling elements 84.

[0026] <Bearing side lubricant layer> The bearing-side lubricating layer 90 shown in Fig. 2 is a member for reducing the coefficient of friction at the contact surface between the rotating shaft 10 and the emergency bearing 80. The bearing-side lubricating layer 90 is provided circumferentially on the inner peripheral surface of the emergency bearing 80, i.e., the inner peripheral surface of the inner ring 82. The bearing-side lubricating layer 90 contains a solid lubricant.

[0027] <Lubrication layer on the rotating shaft side> The rotating shaft side lubricating layer 91 shown in Fig. 2 is a member for reducing the coefficient of friction at the contact surface between the rotating shaft 10 and the emergency bearing 80. The rotating shaft side lubricating layer 91 is provided circumferentially at a position on the outer peripheral surface of the rotating shaft 10 in the axial direction O that corresponds to the emergency bearing 80. Note that while the turbo compressor is in operation, the rotating shaft 10 moves relatively in the axial direction O. For this reason, the formation range of the rotating side lubricating layer in the axial direction O is larger than the dimension of the inner ring 82 in the axial direction O, and the rotating shaft side lubricating layer 91 contains a solid lubricant.

[0028] Examples of solid lubricants contained in the lubricating layer include DLC (diamond-like carbon), CNx (amorphous carbon nitride), and PTFE (polytetrafluoroethylene), although these materials are merely examples and other materials may also be used. Furthermore, it is not necessary for both the bearing-side lubricating layer 90 and the rotating shaft-side lubricating layer 91 to contain the same solid lubricant, and an appropriate combination of materials may be used.

[0029] <Action and effect> In the turbo compressor described above, the rotating shaft 10 is rotatably supported without contact by the radial magnetic bearing 71 and the thrust magnetic bearing 73. When a current is applied to the coil 62 of the stator 60, the rotor 50 and the rotating shaft 10 rotate about the axis O. As the impeller 30 provided on the rotating shaft 10 also rotates about the axis O, the low-pressure refrigerant gas that flows in through the inlet vane 31 is compressed by the impeller 30 to become high-pressure refrigerant gas.

[0030] Here, this embodiment is equipped with an emergency bearing 80. Therefore, even if the radial magnetic bearing 71 fails or stops unexpectedly due to a power outage, for example, the emergency bearing 80 supports the rotating shaft 10. Because the inner diameter of the emergency bearing 80 is smaller than the inner diameter of the radial magnetic bearing 71, even in such a case, the rotating shaft 10 does not touch down on the radial magnetic bearing 71, and it is possible to prevent a load from being applied to the radial magnetic bearing 71.

[0031] In particular, this embodiment is provided with a bearing-side lubricating layer 90 and a rotating shaft-side lubricating layer 91. This reduces the friction coefficient at the contact surface between the outer circumferential surface of the rotating shaft 10 and the inner circumferential surface of the emergency bearing 80, thereby reducing the frictional force that occurs. If the frictional force at the contact surface is large, the movement of the rotating shaft 10 after touchdown will be a whirling movement. By reducing the frictional force at the contact surface, the movement of the rotating shaft 10 after touchdown can be made a pendulum movement. Comparing the case where the movement of the rotating shaft 10 is a whirling movement with the case where it is a pendulum movement, the load that the emergency bearing 80 receives is smaller in the case where it is a pendulum movement. Therefore, by providing the bearing-side lubricating layer 90 and the rotating shaft-side lubricating layer 91, the load that the emergency bearing 80 receives when the radial magnetic bearing 71 is not in operation can be reduced.

[0032] The emergency bearing 80 in this embodiment is a rolling ball bearing including an outer ring 81, an inner ring 82, and rolling elements 84, and therefore can be provided without using a lubricant such as grease or lubricating oil. When bearings are installed in environments such as vacuums or refrigerants, if bearings that use lubricants such as grease or lubricating oil are used, the lubricant may volatilize or denature, causing deterioration. The lubricant may also be dissolved by the refrigerant, resulting in a decrease in bearing functionality. Therefore, the emergency bearing 80 in this embodiment can function as a bearing without using lubricants such as grease or lubricating oil, and can therefore be used in environments such as vacuums or refrigerants without reducing its functionality as an emergency bearing 80.

[0033] <First Modification of First Embodiment> As a first modification of the first embodiment, for example, the configuration shown in FIG. 3 may be used. That is, while in the first embodiment both the bearing-side lubricating layer 90 and the rotating shaft-side lubricating layer 91 are provided, it is also possible to provide only the bearing-side lubricating layer 90. Even in this case, the coefficient of friction at the contact surface between the outer circumferential surface of the rotating shaft 10 and the inner circumferential surface of the emergency bearing 80 is reduced, and so, as with the above, the load received by the emergency bearing 80 when the radial magnetic bearing 71 is not operating can be reduced.

[0034] <Second Modification of First Embodiment> As a second modification of the first embodiment, for example, the configuration shown in FIG. 4 may be used. That is, while in the first embodiment both the bearing-side lubricating layer 90 and the rotating-shaft-side lubricating layer 91 are provided, it is also possible to provide only the rotating-shaft-side lubricating layer 91. Even in this case, the coefficient of friction at the contact surface between the outer circumferential surface of the rotating shaft 10 and the inner circumferential surface of the emergency bearing 80 is reduced, and so, as with the above, the load received by the emergency bearing 80 when the radial magnetic bearing 71 is not operating can be reduced.

[0035] Second Embodiment Next, a second embodiment of the present disclosure will be described with reference to Fig. 5. In the second embodiment, the same components as those in the first embodiment are denoted by the same reference numerals, and detailed description thereof will be omitted. In the emergency bearing 80 of the second embodiment, the shape of the inner ring 82 is different from the shape of the inner ring 82 of the first embodiment. The width of the inner ring 82 of the emergency bearing 80 of this embodiment in the direction of the axis O is smaller than that of the outer ring 81.

[0036] <Action and effect> According to the emergency bearing 80 of this embodiment, the moment of inertia of the inner ring 82 can be made smaller than that of the outer ring 81, making it easier for the inner ring 82 to rotate when it comes into contact with the rotating shaft 10. This reduces the frictional force at the contact surface between the outer circumferential surface of the rotating shaft 10 and the inner circumferential surface of the emergency bearing 80. Therefore, similarly to the first embodiment, the load received by the emergency bearing 80 when the radial magnetic bearing 71 is not in operation can be reduced.

[0037] 5 shows both the bearing-side lubricating layer 90 and the rotating-shaft-side lubricating layer 91, but this is not limiting. That is, just one of the bearing-side lubricating layer 90 and the rotating-shaft-side lubricating layer 91 may be provided, as in the first and second modified examples of the first embodiment.

[0038] Third Embodiment Next, a third embodiment of the present disclosure will be described with reference to Fig. 6. In the third embodiment, the same components as those in the other embodiments are denoted by the same reference numerals, and detailed description thereof will be omitted. The emergency bearing 80 of the third embodiment differs from the first and second embodiments in the shape of the inner ring 82. The emergency bearing 80 of this embodiment has a smaller circumferential thickness than the outer ring 81.

[0039] <Action and effect> In the emergency bearing 80 of this embodiment, the moment of inertia of the inner ring 82 can be made smaller than that of the outer ring 81, so as in the second embodiment, the load received by the emergency bearing 80 when the radial magnetic bearing 71 is not operating can be reduced.

[0040] 6 shows both the bearing-side lubricating layer 90 and the rotating-shaft-side lubricating layer 91, but this is not limiting. That is, just one of the bearing-side lubricating layer 90 and the rotating-shaft-side lubricating layer 91 may be provided, as in the first and second modified examples of the first embodiment.

[0041] <Modifications of the second and third embodiments> As a modification of the second and third embodiments, for example, the specific gravity of the material making up the inner ring 82 of the emergency bearing 80 may be made the same as the specific gravity of the material making up the outer ring 81. This also makes it possible to make the moment of inertia of the inner ring 82 smaller than that of the outer ring 81, and therefore, similar to the second and third embodiments, it is possible to reduce the load that the emergency bearing 80 receives when the radial magnetic bearing 71 is not operating. The moment of inertia of the inner ring 82 may be made smaller than that of the outer ring 81 by appropriately combining this modified example with the second and third embodiments.

[0042] <Fourth embodiment> Next, a fourth embodiment of the present disclosure will be described with reference to Fig. 7. In the fourth embodiment, the same components as those in the other embodiments are denoted by the same reference numerals, and detailed description thereof will be omitted. The emergency bearing 80 of the fourth embodiment is characterized by the positional relationship between the inner ring 82, the outer ring 81, and the rolling elements 84. 7 shows a cross-sectional view of the emergency bearing 80 and rotating shaft 10 of this embodiment, viewed from the direction of axis O. In this embodiment, the rolling elements 84 abut against both the inner ring 82 and the outer ring 81. That is, in this embodiment, for example, by applying an external pressure to the inner ring 82 from the radially inside, the inner ring 82, the rolling elements 84, and the outer ring 81 are brought into contact with each other with a preload in the radial direction.

[0043] <Action and effect> The emergency bearing 80 of this embodiment can distribute the load that the emergency bearing 80 receives when the rotating shaft 10 touches down. Specifically, the load that the emergency bearing 80 receives is distributed to multiple rolling elements 84. This makes it possible to prevent the load from concentrating on only a portion of the rolling elements 84 and the cage 83.

[0044] When the rotating shaft 10 is rotated in the direction of the axis O by the electric motor 40, the inner ring 82 rotates due to the frictional force generated at touchdown. This then generates a frictional force at the point of contact between the inner ring 82 and the rolling elements 84, causing the rolling elements 84 to rotate and move within the housing portion 83a. When the rolling elements 84 move within the housing portion 83a, they collide with the cage 83, applying a load to the cage 83 as well.

[0045] For example, consider a situation in which the rotating shaft 10 touches down on the emergency bearing 80 under conditions in which the inner ring 82 of the emergency bearing 80 and the rolling elements 84 are not in contact. The load caused by the touchdown of the rotating shaft 10 causes the inner ring 82 to move radially outward and come into contact with the rolling elements 84. At this time, of the multiple rolling elements 84, the rolling element 84 closest to the touchdown point comes into contact with the inner ring 82 first.

[0046] In this case, the rolling element 84 closest to the touchdown point will be the first to start moving within the accommodation portion 83a, and a load may also be generated on the cage 83 in the insertion portion that contains that rolling element 84. In other words, the load caused by the touchdown of the rotating shaft 10 may be concentrated only on the rolling elements 84 and a portion of the cage 83. In this case, there is a risk that the cage 83 will be damaged, or that wear, seizure, etc. will occur inside the emergency bearing 80.

[0047] According to the configuration of the emergency bearing 80 of this embodiment, the rolling elements 84 come into contact with both the inner ring 82 and the outer ring 81, so that the load received when the rotating shaft 10 touches down can be distributed to the multiple rolling elements 84. This also distributes the load applied to the cage 83 due to the movement of the rolling elements 84, reducing the risk of damage to the cage 83 and the occurrence of wear, seizure, etc. inside the emergency bearing 80.

[0048] In FIG. 7, all of the rolling elements 84 shown are in contact with both the inner ring 82 and the outer ring 81, but it is not necessarily required that all of the rolling elements 84 are in contact with both the inner ring 82 and the outer ring 81.

[0049] <Other embodiments> Each embodiment of the present disclosure has been described above in detail with reference to the drawings, but the specific configuration is not limited to this embodiment, and design changes and the like are also included within the scope that does not deviate from the gist of the present disclosure.

[0050] For example, in the embodiment of the present disclosure, a turbo compressor is shown as a rotary machine, but the present disclosure is not limited to this and may be applied to an engine or the like. Furthermore, in the embodiment of the present disclosure, a two-stage compression turbo compressor has been shown, but the present invention is not limited to this and may be a single-stage or a multi-stage type having three or more stages.

[0051] For example, the axial widths of the bearing-side lubricating layer and the rotating-shaft-side lubricating layer may be adjusted as appropriate. In Figures 2 to 6, the axial width of the bearing-side lubricating layer is shown to be smaller than that of the rotating-shaft-side lubricating layer, but they may be the same width, or the width of the bearing-side lubricating layer may be larger. Furthermore, the circumferential thickness of the bearing-side lubricating layer 90 and the rotating shaft-side lubricating layer 91 may be adjusted as appropriate. The thicknesses of the respective lubricating layers may be the same or different.

[0052] For example, a buffer member may be provided between the outer ring 81 of the emergency bearing 80 and the casing 20. This can further reduce the load that the emergency bearing 80 receives when the rotating shaft 10 touches down. The buffer member is, for example, an O-ring, but is not limited to this and other members may also be used.

[0053] <Additional Notes> The rotating machine described in each embodiment can be understood, for example, as follows.

[0054] (1) A rotating machine according to a first aspect comprises a rotating shaft 10 extending in the direction of an axis O, an electric motor 40 that drives the rotating shaft 10 to rotate around the axis O, a radial magnetic bearing 71 that supports the outer peripheral surface of the rotating shaft 10 in a non-contact manner, an emergency bearing 80 that supports the rotating shaft 10 when the radial magnetic bearing 71 is not operating, and a lubricating layer containing a solid lubricant that is provided circumferentially on at least one of the outer peripheral surface of the rotating shaft 10 and the inner peripheral surface of the emergency bearing 80.

[0055] According to the above configuration, by reducing the frictional force at the contact surface between the outer peripheral surface of the rotating shaft 10 and the inner peripheral surface of the emergency bearing 80, the load received by the emergency bearing 80 when the radial magnetic bearing 71 is not operating can be reduced.

[0056] (2) A rotating machine according to a second aspect is a rotating machine according to (1), in which the emergency bearing 80 comprises an outer ring 81, an inner ring 82 arranged radially inside the outer ring 81, and a plurality of rolling elements 84 arranged circumferentially between the outer ring 81 and the inner ring 82.

[0057] According to the above configuration, the emergency bearing 80 can function without using lubricants such as grease or lubricating oil, and therefore can be used in environments such as vacuum or refrigerant without reducing its functionality as the emergency bearing 80.

[0058] (3) A rotary machine according to a third aspect is the rotary machine of (2), in which the width of the inner ring 82 in the direction of the axis O is smaller than the width of the outer ring 81 in the direction of the axis O.

[0059] According to the above configuration, the moment of inertia of the inner ring 82 of the emergency bearing 80 is reduced, making it easier for the inner ring 82 to rotate when it comes into contact with the rotating shaft 10. This reduces the frictional force at the contact surface between the outer circumferential surface of the rotating shaft 10 and the inner circumferential surface of the emergency bearing 80. This reduces the load that the emergency bearing 80 receives when the radial magnetic bearing 71 is not operating.

[0060] (4) A rotary machine according to a fourth aspect is the rotary machine according to (2) or (3), in which the thickness of the inner ring 82 in the circumferential direction is smaller than the thickness of the outer ring 81 in the circumferential direction.

[0061] As a result, similarly to the above, the load received by the emergency bearing 80 when the radial magnetic bearing 71 is not in operation can be reduced.

[0062] (5) A rotary machine according to a fifth aspect is the rotary machine according to any one of (2) to (4), in which the specific gravity of the material forming the inner ring 82 is smaller than the specific gravity of the material forming the outer ring 81.

[0063] This also reduces the load that the emergency bearing 80 receives when the radial magnetic bearing 71 is not in operation.

[0064] (6) A rotary machine according to a sixth aspect is a rotary machine of any one of (2) to (5), in which the emergency bearing 80 further includes a retainer 83 extending in the circumferential direction between the outer ring 81 and the inner ring 82 and having an accommodating portion 83a in which each of the rolling elements 84 is accommodated, and the rolling elements 84 abut against both the outer ring 81 and the inner ring 82.

[0065] According to the above configuration, the plurality of rolling elements 84 abuts against both the outer ring 81 and the inner ring 82, so that the load generated when the rotating shaft 10 comes into contact with the plurality of rolling elements 84 is distributed among the plurality of rolling elements 84. This also reduces the load received by the emergency bearing 80 when the radial magnetic bearing 71 is not operating, as described above.

[0066] (7) A rotating machine according to a seventh aspect is the rotating machine according to any one of (1) to (6), wherein the solid lubricant includes at least one of DLC, CNx, and PTFE.

[0067] According to the above-mentioned configuration, the lubricating layer containing these solid lubricants exhibits a low coefficient of friction, which also reduces the load received by the emergency bearing 80 when the radial magnetic bearing 71 is not in operation. [Explanation of symbols]

[0068] 1. Turbo compressor (rotating machine) 10 Rotation axis 20 Casing 21 Electric motor room 22 Compression chamber 23 Intake section 30 impeller 31 Inlet vane 40 Electric motor 50 rotors 51 rotor core 52 Permanent Magnets 60 Stator 61 Stator core 62 Coil 70 Main bearing unit 71 Radial magnetic bearing 72 Thrust Collar 73 Thrust magnetic bearing 80 Emergency bearings 81 outer ring 82 Inner circle 83 Retainer 83a Storage section 84 rolling elements 90 Bearing side lubrication layer 91 Rotating shaft side lubrication layer O axis

Claims

1. a rotation shaft extending in an axial direction; an electric motor that drives the rotary shaft to rotate about the axis; a radial magnetic bearing that supports the outer peripheral surface of the rotating shaft in a non-contact state; an emergency bearing that supports the rotating shaft when the radial magnetic bearing is not in operation; a lubricating layer including a solid lubricant and provided circumferentially on at least one of the outer circumferential surface of the rotating shaft and the inner circumferential surface of the emergency bearing; A rotating machine comprising:

2. The emergency bearing is The outer ring and an inner ring provided radially inside the outer ring; a plurality of rolling elements provided in a circumferential direction between the outer ring and the inner ring; The rotary machine of claim 1 .

3. The rotary machine according to claim 2 , wherein the width of the inner ring in the axial direction is smaller than the width of the outer ring in the axial direction.

4. The rotary machine according to claim 2 , wherein the thickness of the inner ring in the circumferential direction is smaller than the thickness of the outer ring in the circumferential direction.

5. The rotary machine according to claim 2 , wherein the specific gravity of the material constituting the inner ring is smaller than the specific gravity of the material constituting the outer ring.

6. The emergency bearing is the bearing further includes a cage extending in the circumferential direction between the outer ring and the inner ring and having accommodation portions in which the rolling elements are accommodated, The rotary machine according to claim 2 , wherein the rolling elements are in contact with both the outer ring and the inner ring.

7. The rotary machine according to claim 1 , wherein the solid lubricant includes at least one of DLC, CNx, and PTFE.

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