Rotating body, rotating electric machine, electric compressor, and method for manufacturing rotating body

Abstract

Provided are a rotor and a rotary electrical machine, wherein the rotor comprises: a rotating shaft made of a magnetic body; a rotating element fixed to the rotating shaft; and a pair of bearing sleeves for air bearing, that have a cylindrical shape, are mounted on one end and the other end of the rotating element in the axial direction, and are provided with an abrasion-resistant coating layer on the outer surface. The pair of bearing sleeves for air bearing is provided with an abrasion-resistant coating layer prior to assembly to the rotating shaft.

Description

[Technical Field]

[0001] The present disclosure relates to a rotating body, a rotating electric machine, an electric compressor, and a method for manufacturing a rotating body. [Background technology]

[0002] For example, fuel cells require high-pressure air, so two-stage compression electric compressors are used. To improve the efficiency of two-stage compression electric compressors, it is necessary to increase the speed. When the electric compressor is a centrifugal compression type, it becomes possible to design highly efficient blades, making it possible to reduce the size and weight of the electric motor. The electric motors used in electric compressors generally use air bearings to prevent lubricating oil from mixing into the compressed air, and the compressed air is supplied to the air bearings to operate them.

[0003] An example of such an electric compressor is described in Patent Document 1 below. The electric compressor described in Patent Document 1 has a magnet disposed in the axial middle of a rotating shaft, and a sleeve disposed on the outside of the magnet. The rotating shaft is rotatably supported by air bearings at one and the other axial ends of the sleeve relative to the housing. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 6845953 Summary of the Invention [Problem to be solved by the invention]

[0005] In an air bearing, the outer peripheral surface of the rotating shaft and the inner peripheral surface of the bearing are in contact with each other when compressed air is not supplied. When the rotating shaft rotates, compressed air is supplied to the air bearing, separating the outer peripheral surface of the rotating shaft from the inner peripheral surface of the bearing, and the air bearing rotatably supports the rotating shaft at a predetermined position. That is, when the rotating shaft starts to rotate, the outer peripheral surface of the rotating shaft and the inner peripheral surface of the bearing are in contact with each other, causing wear. For this reason, a wear-resistant coating is generally applied to the outer peripheral surface of the rotating shaft (sleeve) facing the air bearing. However, due to the structure of conventional electric compressors, a wear-resistant coating is applied to the outer peripheral surface of the sleeve, and then the sleeve is fixed to the outer peripheral surface of the rotating shaft by shrink fitting. In this case, if the heat treatment temperature for shrink fitting the sleeve exceeds the application temperature of the wear-resistant coating, the coating layer may deteriorate. Therefore, it is difficult to control the application temperature of the wear-resistant coating and the heat treatment temperature for shrink fitting.

[0006] The present disclosure is intended to solve the above-mentioned problems, and aims to provide a rotating body, a rotating electric machine, an electric compressor, and a method for manufacturing a rotating body that can appropriately ensure a wear-resistant coating for an air bearing. [Means for solving the problem]

[0007] In order to achieve the above object, the rotating body of the present disclosure comprises a rotating shaft made of a magnetic material, a rotor fixed to the rotating shaft, and a pair of cylindrical air bearing sleeves attached to one and the other axial ends of the rotor and having a wear-resistant coating layer on their outer surfaces, and the pair of air bearing sleeves are provided with the wear-resistant coating layer before being assembled to the rotating shaft.

[0008] The rotating electric machine of the present disclosure also comprises a hollow housing, a cylindrical stator fixed to the inner peripheral surface of the housing, a rotating body rotatably supported in the housing so that the rotor faces the inner peripheral surface of the stator with a gap therebetween, and a pair of air bearings provided in the housing so as to face the outer peripheral surfaces of the pair of air bearing sleeves with a gap therebetween.

[0009] The electric compressor of the present disclosure includes the rotating electric machine, a low-pressure wheel fixed to one axial end of the rotating shaft, and a high-pressure wheel fixed to the other axial end of the rotating shaft.

[0010] In addition, the manufacturing method of the rotating body disclosed herein includes the steps of placing an iron core on the outer periphery of a rotating shaft made of a magnetic material, fixing a retaining sleeve to the outer periphery of the iron core by shrink fitting, and attaching a pair of bearing sleeves for air bearings having a wear-resistant coating layer to one end and the other axial end of the rotating shaft. [Effects of the Invention]

[0011] According to the rotating body, rotating electric machine, electric compressor, and method for manufacturing a rotating body disclosed herein, it is possible to appropriately ensure a wear-resistant coating for an air bearing. [Brief explanation of the drawings]

[0012] [Figure 1] FIG. 1 is a vertical cross-sectional view showing the internal configuration of the electric compressor of this embodiment. [Figure 2] FIG. 2 is a vertical cross-sectional view showing the rotating body of this embodiment. [Figure 3] FIG. 3 is a cross-sectional view taken along the line III-III in FIG. 2, illustrating the relationship between the rotating shaft, the rotor core, and the retaining sleeve. [Figure 4] FIG. 4 is a cross-sectional view taken along line IV-IV in FIG. 2, illustrating the relationship between the rotating shaft and the retaining sleeve. [Figure 5] FIG. 5 is a cross-sectional view taken along line VV of FIG. 2, illustrating the relationship between the rotating shaft and the bearing sleeve. [Figure 6]FIG. 6 is an exploded cross-sectional view for explaining a method for assembling the rotor. DETAILED DESCRIPTION OF THE INVENTION

[0013] Preferred embodiments of the present disclosure will be described in detail below with reference to the drawings. Note that the present disclosure is not limited to these embodiments, and when there are multiple embodiments, the present disclosure also includes configurations that combine the embodiments. Furthermore, the components in the embodiments include those that can be easily imagined by a person skilled in the art, those that are substantially identical, and those that are within the so-called equivalent range.

[0014] In this embodiment, the rotating body is applied to a rotating electric machine, and the rotating electric machine (motor) is applied to an electric compressor. However, the present invention is not limited to this configuration, and the rotating body may be applied to a general electric motor as a rotating electric machine.

[0015] <Configuration of electric compressor> FIG. 1 is a vertical cross-sectional view showing the internal configuration of an electric compressor according to a first embodiment.

[0016] 1, the electric compressor 10 includes a housing 11, a rotating shaft 12, a stator 13, a rotor 14, a low-pressure wheel 15, and a high-pressure wheel 16. The rotating body is made up of the rotating shaft 12 and the rotor 14. The rotating electric machine is made up of the housing 11, the rotating shaft 12, the stator 13, and the rotor 14.

[0017] The housing 11 has a motor housing 21, a low-pressure side bearing housing 22, and a high-pressure side bearing housing 23. The motor housing 21 is cylindrical and has an expanded diameter at one axial end (the right side in FIG. 1). The low-pressure side bearing housing 22 is disk-shaped and is located on one axial end of the motor housing 21. The low-pressure side bearing housing 22 is detachably fastened to the one axial end of the motor housing 21 with a plurality of bolts. The high-pressure side bearing housing 23 is disk-shaped and is located on the other axial end of the motor housing 21. The high-pressure side bearing housing 23 is detachably fastened to the other axial end of the motor housing 21 with a plurality of bolts.

[0018] One axial opening of cylindrical motor housing 21 is closed by low-pressure side bearing housing 22, and the other axial opening is closed by high-pressure side bearing housing 23. Therefore, housing 11 has a hollow shape when low-pressure side bearing housing 22 and high-pressure side bearing housing 23 are fastened to motor housing 21.

[0019] The stator 13 is fixed to the inner periphery of the motor housing 21. The stator 13 is cylindrical. The stator 13 has a stator core 31 and a stator coil 32. The stator core 31 is cylindrical and is fixed so that its outer periphery is in close contact with the inner periphery of the motor housing 21. The stator coil 32 is housed inside the stator core 31.

[0020] The rotating shaft 12 is disposed inside the housing 11. The rotating shaft 12 is disposed along an axis O that is concentric with the housing 11, and is supported by the housing 11 so as to be rotatable about the axis O. A rotor 14 is fixed to the outer periphery of the rotating shaft 12 at a midpoint in the axial direction. The rotor 14 has a rotor core (permanent magnet) 33 and a retaining sleeve 34. The rotor core 33 is cylindrical and is disposed on the outer periphery of the rotating shaft 12. The retaining sleeve 34 is cylindrical and is disposed on the outside of the rotor core 33.

[0021] The inner and outer circumferential surfaces of the stator 13 and rotor 14 face each other in the radial direction. A gap is provided between the inner and outer circumferential surfaces of the stator 13 and rotor 14. Therefore, when a current flows through the stator coil 32 of the stator 13, the rotor 14 rotates due to the attractive and repulsive forces of the generated magnetic force, and the rotating shaft 12 outputs a rotational force.

[0022] Rotating shaft 12 is rotatably supported by low-pressure side air bearing 35 and high-pressure side air bearing 36. Rotating shaft 12 has low-pressure side shaft portion 12a on one axial side of rotor 14, and high-pressure side shaft portion 12b on the other axial side of rotor 14. Rotating shaft 12 has a low-pressure side bearing sleeve (bearing sleeve for air bearing) 37 attached to low-pressure side shaft portion 12a so as to be integrally rotatable, and a high-pressure side bearing sleeve (bearing sleeve for air bearing) 38 attached to high-pressure side shaft portion 12b so as to be integrally rotatable. Low-pressure side bearing sleeve 37 functions as the low-pressure side shaft portion, and high-pressure side bearing sleeve 38 functions as the high-pressure side shaft portion.

[0023] Low-pressure side air bearing 35 is provided integrally with low-pressure side bearing housing 22. Low-pressure side air bearing 35 is cylindrical and extends from the inner surface of low-pressure side bearing housing 22 towards rotor 14. Low-pressure side air bearing 35 is disposed outward of a low-pressure side bearing sleeve 37 attached to rotating shaft 12. When rotating shaft 12 rotates, a low-pressure side gap is secured between the inner circumferential surface of low-pressure side air bearing 35 and the outer circumferential surface of low-pressure side bearing sleeve 37.

[0024] The high-pressure side air bearing 36 is provided integrally with the high-pressure side bearing housing 23. The high-pressure side air bearing 36 is cylindrical and extends from the inner surface of the high-pressure side bearing housing 23 towards the rotor 14. The high-pressure side air bearing 36 is disposed outward of a high-pressure side bearing sleeve 38 attached to the rotating shaft 12. When the rotating shaft 12 rotates, a high-pressure side gap is secured between the inner circumferential surface of the high-pressure side air bearing 36 and the outer circumferential surface of the high-pressure side bearing sleeve 38.

[0025] The rotating shaft 12 has a thrust disk 39 fixed to one axial side thereof, which constitutes a thrust bearing, and a low-pressure-side thrust sleeve 40 disposed therein. The thrust disk 39 is fixed on the rotating shaft 12 between the low-pressure-side bearing sleeve 37 and the low-pressure wheel 15. The thrust disk 39 rotates integrally with the rotating shaft 12. The low-pressure-side bearing housing 22 has a low-pressure-side space 41 formed around the outer periphery of the axis O. The thrust disk 39 is disposed in the low-pressure-side space 41. The low-pressure-side space 41 communicates with a low-pressure gap between the inner circumferential surface of the low-pressure-side air bearing 35 and the outer circumferential surface of the low-pressure-side bearing sleeve 37. The low-pressure-side thrust sleeve 40 is disposed on the rotating shaft 12 between the low-pressure wheel 15 and the thrust disk 39. The low-pressure-side thrust sleeve 40 rotates integrally with the rotating shaft 12. A seal member (not shown) is provided on the outer periphery of the low-pressure-side thrust sleeve 40. The outer periphery of the seal member contacts the inner periphery of the low-pressure side bearing housing 22. The low-pressure side thrust sleeve 40 is rotatable relative to the low-pressure side bearing housing 22.

[0026] A high-pressure side thrust sleeve 42 is disposed on the other axial side of the rotating shaft 12. The high-pressure side thrust sleeve 42 is disposed on the rotating shaft 12 between the high-pressure wheel 16 and the high-pressure side bearing sleeve 38. The high-pressure side thrust sleeve 42 rotates integrally with the rotating shaft 12. A seal member (not shown) is provided on the outer periphery of the high-pressure side thrust sleeve 42. The outer periphery of the seal member contacts the inner circumferential surface of the high-pressure side bearing housing 23. The high-pressure side thrust sleeve 42 is rotatable relative to the high-pressure side bearing housing 23.

[0027] In housing 11, low-pressure compressor 51 is disposed on the low-pressure side bearing housing 22 side, and high-pressure compressor 61 is disposed on the high-pressure side bearing housing 23 side. Low-pressure compressor 51 has low-pressure side housing 52 and low-pressure wheel 15. High-pressure compressor 61 has high-pressure side housing 62 and high-pressure wheel 16.

[0028] The low-pressure side housing 52 is fastened to the outer surface of the low-pressure side bearing housing 22 with a plurality of bolts. The low-pressure wheel 15 is disposed inside the low-pressure side housing 52. The low-pressure wheel 15 is fixed to one axial end of the rotating shaft 12 with a nut 53 so as to be rotatable integrally therewith. The low-pressure compressor 51 is provided with a suction port 54, a diffuser 55, a scroll portion 56 having a spiral shape, and a discharge port (not shown) by the low-pressure side housing 52 and the low-pressure wheel 15.

[0029] The high-pressure side housing 62 is fastened to the outer surface of the high-pressure side bearing housing 23 with a plurality of bolts. The high-pressure wheel 16 is disposed inside the high-pressure side housing 62. The high-pressure wheel 16 is fixed to the other axial end of the rotating shaft 12 with a nut 63 so as to be rotatable together. The high-pressure compressor 61 is provided with a suction port 64, a diffuser 65, a scroll portion 66 having a spiral shape, and a discharge port (not shown) by the high-pressure side housing 62 and the high-pressure wheel 16.

[0030] Furthermore, the low-pressure compressor 51 and the high-pressure compressor 61 have their discharge ports (not shown) and suction ports 64 connected by a connecting flow path 71 .

[0031] When the low-pressure wheel 15 of the low-pressure compressor 51 rotates, external air is drawn in through the intake port 54 and accelerated by the centrifugal force of the low-pressure wheel 15. The accelerated air is decelerated and pressurized by the diffuser 55, then flows through the scroll section 56 and is discharged from the discharge port. The low-pressure air compressed by the low-pressure compressor 51 is supplied to the high-pressure compressor 61 through a connecting flow path 71. When the high-pressure wheel 16 of the high-pressure compressor 61 rotates, external air is drawn in through the intake port 64 and accelerated by the centrifugal force of the high-pressure wheel 16. The accelerated air is decelerated and pressurized by the diffuser 65, then flows through the scroll section 66 and is discharged from the discharge port.

[0032] The housing 11 is also provided with a low-pressure-side air flow path 72 and a high-pressure-side air flow path 73. The low-pressure-side air flow path 72 supplies compressed air from the housing 11 to the low-pressure-side air bearing 35. The low-pressure-side air flow path 72 branches off from the connecting flow path 71 and supplies a portion of the compressed air to the low-pressure-side space 41. The compressed air in the low-pressure-side space 41 is then supplied to a low-pressure gap between the inner circumferential surface of the low-pressure-side air bearing 35 and the outer circumferential surface of the low-pressure-side bearing sleeve 37, thereby supporting the rotating shaft 12 at a predetermined position in the radial direction. The compressed air supplied to the low-pressure-side air bearing 35 then flows into the gap between the stator 13 and the rotor 14.

[0033] The high-pressure-side air flow path 73 supplies compressed air from the housing 11 to the high-pressure-side air bearing 36. The high-pressure-side air flow path 73 branches off from the connecting flow path 71 and supplies a portion of the compressed air to the high-pressure-side air bearing 36. The compressed air is supplied to a high-pressure gap between the inner circumferential surface of the high-pressure-side air bearing 36 and the outer circumferential surface of the high-pressure-side bearing sleeve 38, thereby supporting the rotating shaft 12 at a predetermined position in the radial direction. The compressed air supplied to the high-pressure-side air bearing 36 then flows into the gap between the stator 13 and the rotor 14.

[0034] <Rotating body> FIG. 2 is a longitudinal cross-sectional view showing the rotating body of this embodiment, FIG. 3 is a cross-sectional view taken along line III-III in FIG. 2 showing the relationship between the rotating shaft, the rotor core, and the retaining sleeve, FIG. 4 is a cross-sectional view taken along line IV-IV in FIG. 2 showing the relationship between the rotating shaft and the retaining sleeve, and FIG. 5 is a cross-sectional view taken along line VV in FIG. 2 showing the relationship between the rotating shaft and the bearing sleeve.

[0035] As shown in Fig. 2, the rotating body 80 has a rotating shaft 12 and a rotor 14. The rotor 14 has a rotor core 33 and a retaining sleeve 34. The rotor core 33 is a cylindrical permanent magnet and is disposed on the outer circumferential surface of the rotating shaft 12. The retaining sleeve 34 is also cylindrical and is disposed on the outside of the rotor core 33.

[0036] The rotating shaft 12 is a magnetic body having an axial center O. The rotating shaft 12 has a low-pressure side shaft portion 12a, a high-pressure side shaft portion 12b, and an intermediate shaft portion 12c. The low-pressure side shaft portion 12a is located on one axial side of the rotating shaft 12. The high-pressure side shaft portion 12b is located on the other axial side of the rotating shaft 12. The intermediate shaft portion 12c is located in the intermediate portion of the rotating shaft 12 in the axial direction, between the low-pressure side shaft portion 12a and the high-pressure side shaft portion 12b. The rotating shaft 12 also has a low-pressure side flange portion 12d between the low-pressure side shaft portion 12a and the intermediate shaft portion 12c. The rotating shaft 12 also has a high-pressure side flange portion 12e between the high-pressure side shaft portion 12b and the intermediate shaft portion 12c. The low-pressure side flange portion 12d and the high-pressure side flange portion 12e are located at an interval in the axial direction of the rotating shaft 12. The low-pressure side flange portion 12d and the high-pressure side flange portion 12e have the same outer diameter.

[0037] Furthermore, an axial recess 12f is provided on the outer periphery of the intermediate shaft portion 12c of the rotating shaft 12. The axial recess 12f is formed between the low-pressure side flange portion 12d and the high-pressure side flange portion 12e along the circumferential direction and recessed toward the axis O.

[0038] As shown in FIGS. 2 and 3, the rotor core 33 is disposed on the outer side of the intermediate shaft portion 12c of the rotary shaft 12. The rotor core 33 has a plurality of (two in this embodiment) split core segments 33a, 33b split in the circumferential direction. The split core segments 33a, 33b may be integrally formed, or may be split into a plurality of segments in the axial direction. The split core segments 33a, 33b may be made of laminated steel plates. The split core segments 33a, 33b may be divided into three or more segments.

[0039] The split cores 33a and 33b are attached to the outer peripheral surface of the intermediate shaft portion 12c of the rotating shaft 12. At this time, the split cores 33a and 33b are positioned in the axial direction by fitting their inner peripheral portions into axial recesses 12f formed in the intermediate shaft portion 12c. At this time, the inner peripheral surfaces of the split cores 33a and 33b are bonded to the outer peripheral surfaces of the axial recesses 12f. Therefore, the split cores 33a and 33b are attached to the intermediate shaft portion 12c between the low-pressure side flange portion 12d and the high-pressure side flange portion 12e. The outer diameter of the rotor core 33 is the same as or slightly smaller than the outer diameters of the low-pressure side flange portion 12d and the high-pressure side flange portion 12e.

[0040] The retaining sleeve 34 is disposed outside the rotor core 33. The retaining sleeve 34 is located outside the rotor core 33, with one axial end fixed to the outer periphery of the low-pressure-side flange 12d and the other end fixed to the outer periphery of the high-pressure-side flange 12e. The retaining sleeve 34 is inserted into the outer peripheries of the low-pressure-side flange 12d and the high-pressure-side flange 12e from one axial side of the rotating shaft 12. The retaining sleeve 34 is fixed to the outer periphery of the low-pressure-side flange 12d, the rotor core 33, and the high-pressure-side flange 12e by shrink fitting. Therefore, the inner periphery of the retaining sleeve 34 is in close contact with the outer periphery of the low-pressure-side flange 12d, the outer periphery of the high-pressure-side flange 12e, and the outer periphery of the rotor core 33.

[0041] 2 and 4, each end of the rotor core 33 is disposed axially of the rotating shaft 12, spaced apart from the low-pressure-side flange 12d and the high-pressure-side flange 12e by a predetermined distance. Therefore, a low-pressure-side space 81 is provided between the rotor core 33 and the low-pressure-side flange 12d, and a high-pressure-side space 82 is provided between the rotor core 33 and the high-pressure-side flange 12e. The low-pressure-side space 81 is defined by one axial end face of the rotor core 33, the outer surface of the intermediate shaft 12c, one side face of the low-pressure-side flange 12d, and the inner surface of the retaining sleeve 34. The high-pressure-side space 82 is defined by the other axial end face of the rotor core 33, the outer surface of the intermediate shaft 12c, one side face of the high-pressure-side flange 12e, and the inner surface of the retaining sleeve 34.

[0042] The low-pressure side space 81 and the high-pressure side space 82 are made of a non-magnetic material. Therefore, the low-pressure side space 81 and the high-pressure side space 82 may be filled with a resin material, which is a non-magnetic material. By filling the low-pressure side space 81 and the high-pressure side space 82 with a resin material, the strength of the rotor core 33 can be increased.

[0043] 1 and 5, a low-pressure side bearing sleeve 37 is fixed to the low-pressure side shaft portion 12a of the rotating shaft 12. The low-pressure side bearing sleeve 37 is cylindrical and lightly press-fit (loose fit) into the low-pressure side shaft portion 12a. Lightly press-fitting means that when a predetermined axial stress acts on the low-pressure side bearing sleeve 37, the low-pressure side bearing sleeve 37 is press-fit with enough pressure to move axially relative to the rotating shaft 12. Therefore, the low-pressure side bearing sleeve 37 can rotate integrally with the rotating shaft 12.

[0044] A high-pressure side bearing sleeve 38 is fixed to the high-pressure side shaft portion 12b of the rotating shaft 12. The high-pressure side bearing sleeve 38 has a cylindrical shape and is lightly press-fit (loose fit) into the high-pressure side shaft portion 12b. Therefore, the high-pressure side bearing sleeve 38 can rotate integrally with the rotating shaft 12.

[0045] A wear-resistant coating is applied to the outer peripheral surface of low-pressure side bearing sleeve 37, thereby providing a wear-resistant coating layer 37a. A wear-resistant coating is applied to the outer peripheral surface of high-pressure side bearing sleeve 38, thereby providing a wear-resistant coating layer 38a. The wear-resistant coatings for low-pressure side bearing sleeve 37 and high-pressure side bearing sleeve 38 are applied before assembly onto rotating shaft 12.

[0046] A thrust disk 39 is inserted adjacent to the low-pressure side bearing sleeve 37 on one axial side of the rotating shaft 12, and a low-pressure side thrust sleeve 40 is also inserted. The low-pressure wheel 15 is attached to one axial end of the rotating shaft 12 and fastened together by a nut 53 so as to be rotatable as a unit. At this time, the fastening force of the nut 53 on the rotating shaft 12 presses the low-pressure wheel 15 towards the stator 13. The pressing force of the low-pressure wheel 15 is then transmitted to the low-pressure side bearing sleeve 37 via the low-pressure side thrust sleeve 40 and thrust disk 39, and the low-pressure side bearing sleeve 37 abuts against the low-pressure side flange portion 12d, positioning it.

[0047] The high-pressure-side thrust sleeve 42 is inserted adjacent to the high-pressure-side bearing sleeve 38 on the other axial side of the rotating shaft 12. The high-pressure wheel 16 is then attached to the other axial end of the rotating shaft 12 and fastened together by a nut 63 so as to be able to rotate integrally. At this time, the fastening force of the nut 63 on the rotating shaft 12 presses the high-pressure wheel 16 towards the stator 13. Then, the pressing force of the high-pressure wheel 16 is transmitted to the high-pressure-side bearing sleeve 38 via the high-pressure-side thrust sleeve 42, and the high-pressure-side bearing sleeve 38 abuts against the high-pressure-side flange portion 12e, positioning it.

[0048] <How to assemble the rotating body> FIG. 6 is an exploded cross-sectional view for explaining a method for assembling the rotor.

[0049] As shown in Fig. 6, the rotating shaft 12 has a low-pressure side flange portion 12d and a high-pressure side flange portion 12e. The rotor core 33 is composed of two split cores 33a and 33b. First, the split cores 33a and 33b are positioned radially outward from the intermediate shaft portion 12c of the rotating shaft 12, and then the split cores 33a and 33b are moved radially inward in the directions of arrows A1 and A2 of the rotating shaft 12, so that they are in close contact with the intermediate shaft portion 12c.

[0050] At this time, the inner peripheral portions of the split cores 33a and 33b are positioned in the axial recesses 12f of the intermediate shaft portion 12c, and the inner peripheral surfaces are bonded to the axial recesses 12f. Therefore, one axial end of the rotor core 33 is disposed at a predetermined distance from the low-pressure-side flange portion 12d, and the other axial end is disposed at a predetermined distance from the high-pressure-side flange portion 12e.

[0051] Next, the retaining sleeve 34 is positioned on one side of the axial direction of the rotating shaft 12, and then moved in the direction of arrow A3, which is the other side of the axial direction of the rotating shaft 12, to position it radially outward from the low-pressure side flange 12d, the rotor core 33, and the high-pressure side flange 12e. At this time, the retaining sleeve 34 is fixed to the low-pressure side flange 12d, the rotor core 33, and the high-pressure side flange 12e by shrink fitting. That is, the retaining sleeve 34 is heated to expand and widen its inner diameter, and in this state, it is positioned outward from the low-pressure side flange 12d, the rotor core 33, and the high-pressure side flange 12e. Thereafter, the retaining sleeve 34 is cooled to contract and narrow its inner diameter, and the inner circumferential surface of the retaining sleeve 34 presses against the outer circumferential surfaces of the low-pressure side flange 12d, the rotor core 33, and the high-pressure side flange 12e.

[0052] As a result, the retaining sleeve 34 is firmly joined to the low-pressure-side flange 12d, the rotor core 33, and the high-pressure-side flange 12e. In other words, the rotating shaft 12, the rotor core 33, and the retaining sleeve 34 are joined together. At this time, a low-pressure-side space 81 is formed between the rotor core 33 and the low-pressure-side flange 12d, and a high-pressure-side space 82 is formed between the rotor core 33 and the high-pressure-side flange 12e.

[0053] Next, low-pressure side bearing sleeve 37 is positioned on one axial side of rotating shaft 12, and low-pressure side bearing sleeve 37 is moved in the direction of arrow A4, which is the other axial direction of rotating shaft 12, to lightly press-fit into low-pressure side shaft portion 12a. Furthermore, high-pressure side bearing sleeve 38 is positioned on the other axial side of rotating shaft 12, and high-pressure side bearing sleeve 38 is moved in the direction of arrow A5, which is one axial direction of rotating shaft 12, to lightly press-fit into high-pressure side shaft portion 12b. In this case, wear-resistant coatings are applied to the outer peripheral surfaces of low-pressure side bearing sleeve 37 and high-pressure side bearing sleeve 38 before assembly, so that wear-resistant coating layers 37a, 38a are provided on the outer peripheral surfaces of low-pressure side bearing sleeve 37 and high-pressure side bearing sleeve 38, respectively.

[0054] 2, after inserting the thrust disc 39 and low-pressure side thrust sleeve 40 into one end of the rotating shaft 12, the low-pressure wheel 15 is attached and fastened with a nut 53. Furthermore, after inserting the high-pressure side thrust sleeve 42 into the other end of the rotating shaft 12, the high-pressure wheel 16 is attached and fastened with a nut 63.

[0055] <Electric compressor action> In the electric compressor 10, when a current (AC voltage) is applied to the stator coil 32 that constitutes the stator 13, a magnetic field is generated around the stator 13, generating a rotating magnetic field (magnetic force), and generating north and south poles around the stator 13. The rotor core 33 (rotor 14) is attracted to the rotating magnetic field of the stator 13 and rotates. At this time, the rotor core 33 is a magnetic material, and magnetic flux is generated along the circumferential direction. A low-pressure side space 81 is formed on one axial side of the rotor core 33, and a high-pressure side space 82 is formed on the other axial side. Because the low-pressure side space 81 and the high-pressure side space 82 are non-magnetic, leakage of magnetic flux in the axial direction from the rotor core 33 is prevented. If the low-pressure side space 81 and the high-pressure side space 82 are filled with a resin material, the strength of the rotor core 33 is increased.

[0056] The low-pressure side flange portion 12d and the high-pressure side flange portion 12e of the rotating shaft 12 have higher rigidity than the rotor core 33. Therefore, when the retaining sleeve 34 fixes the rotor core 33 to the rotating shaft 12 by shrink fitting, the axial middle portion of the retaining sleeve 34 deforms toward the axis O and presses the rotor core 33, increasing the contact area between the rotating shaft 12, the rotor core 33, and the retaining sleeve 34 and increasing strength against centrifugal force.

[0057] Furthermore, rotating shaft 12 is a magnetic body, and magnetic flux from rotor core 33 flows through rotating shaft 12. The rotational force of rotor core 33 is transmitted to retaining sleeve 34 via the surface contact portion on the outer periphery, and is further transmitted to rotating shaft 12 via the surface contact between retaining sleeve 34 and low-pressure side flange portion 12d and high-pressure side flange portion 12e. When rotating shaft 12 rotates, low-pressure wheel 15 and high-pressure wheel 16 connected to each end rotate, compressing the air.

[0058] [Effects of this embodiment] The rotating body of the first embodiment comprises a rotating shaft 12 made of a magnetic material, a rotor 14 fixed to the rotating shaft 12, and a pair of cylindrical bearing sleeves (air bearing sleeves) 37, 38 attached to one and the other axial ends of the rotor 14 and having wear-resistant coating layers 37a, 38a on their outer surfaces, and the pair of bearing sleeves 37, 38 are provided with wear-resistant coating layers 37a, 37b before being assembled to the rotating shaft 12.

[0059] According to the rotating body of the first aspect, the bearing sleeves 37, 38 supported by the air bearings 35, 36 are manufactured separately from the rotating shaft 12, and wear-resistant coating layers 37a, 38a are applied thereto before the rotating shaft 12 is assembled, thereby suppressing deterioration of the wear-resistant coating layers 37a, 38a and ensuring proper wear-resistant coating layers 37a, 38a.

[0060] In the rotating body according to the second aspect, rotor 14 has rotor core 33 that is cylindrical and divided into multiple segments in the circumferential direction and made up of magnets arranged radially outside rotating shaft 12. This allows divided cores 33a and 33b to be attached to rotating shaft 12 by moving them radially from the outside, improving the ease of assembly of rotor core 33.

[0061] In the rotating body according to the third aspect, the rotating shaft 12 has a pair of flange portions 12d, 12e spaced apart in the axial direction, the rotor core 33 is disposed between the pair of flange portions 12d, 12e, and one end and the other end in the axial direction of the cylindrical retaining sleeve 34 are fixed to the outer peripheries of the pair of flange portions 12d, 12e, thereby being fixed integrally to the rotating shaft 12. As a result, since the pair of flange portions 12d, 12e are provided on the rotating shaft 12, Rotor iron core 33 on rotating shaft 12 After assembling the retaining sleeve 34, the retaining sleeve 34 is disposed on the outside of the rotor core 33 and fixed to the pair of flanges 12d, 12e, thereby facilitating assembly of the rotating body 80. In other words, there is no need to fix the pair of end plates (the pair of flanges 12d, 12e) for fixing the retaining sleeve 34 to the rotating shaft 12 by welding or the like. As a result, the number of parts can be reduced and the assembly process can be simplified.

[0062] In the rotating body according to the fourth aspect, the retaining sleeve 34 is fixed by shrink fitting to the outer peripheral surfaces of the pair of flange portions 12d, 12e and the outer peripheral surface of the rotor core 33. This allows the rotating shaft 12, the rotor core 33, and the retaining sleeve 34 to be integrally joined, simplifying the assembly process. In addition, a compressive load is applied to the rotor core 33 by the retaining sleeve 34, preventing damage to the rotor core 33 due to centrifugal force acting on it during rotation. Furthermore, the wear-resistant coating layers 37a, 38a can be prevented from deteriorating due to heat treatment for shrink fitting.

[0063] In a rotating body according to a fifth aspect, the rotor core 33 is cylindrical and disposed on the outer periphery of the rotating shaft 12, and the retaining sleeve 34 is fixed to the outer periphery of the rotor core 33 by shrink fitting. In other words, in the above-described embodiment, the rotor core 33 is formed by providing a pair of flanges 12d, 12e on the rotating shaft 12 and disposing the split cores 33a, 33b between the pair of flanges 12d, 12e. However, this configuration is not limited to this. The rotor core 33 may be formed as a single cylindrical unit, inserted into the rotating shaft 12 from one axial direction of the rotating shaft 12, and the retaining sleeve 34 fixed to the outer periphery of the rotor core 33 by shrink fitting. This simplifies the structure of the rotating shaft 12. Alternatively, the rotor core 33 may be fixed to the rotating shaft 12 by adhesive, or a pair of end plates (a pair of flanges 12d, 12e) may be fixed to the rotating shaft 12 by welding or the like.

[0064] In the rotating body according to the sixth aspect, the bearing sleeves 37, 38 are lightly press-fitted into one end and the other end in the axial direction of the rotating shaft 12. This allows the bearing sleeves 37, 38 to be provisionally positioned at predetermined positions relative to the rotating shaft 12, improving the ease of assembly of the bearing sleeves 37, 38.

[0065] The rotating electric machine according to the seventh aspect includes a hollow housing 11, a cylindrical stator 13 fixed to the inner circumferential surface of the housing 11, a rotating body 80 rotatably supported in the housing 11 so that a rotor 14 faces the inner circumferential surface of the stator 13 with a gap therebetween, and a pair of air bearings 35, 36 provided in the housing 11 so as to face the outer circumferential surfaces of a pair of bearing sleeves 37, 38 with a gap therebetween. This makes it possible to appropriately secure wear-resistant coating layers 37a, 38a.

[0066] The electric compressor according to the eighth aspect includes a rotating electric machine, a low-pressure wheel 15 fixed to one axial end of the rotating shaft 12, and a high-pressure wheel 16 fixed to the other axial end of the rotating shaft 12. This makes it possible to appropriately secure the wear-resistant coating layers 37a, 38a.

[0067] A manufacturing method of a rotating body according to the ninth aspect includes the steps of arranging a rotor core 33 on the outer periphery of a rotating shaft 12 made of a magnetic material, fixing a retaining sleeve 34 to the outer periphery of the rotor core 33 by shrink fitting, and attaching a pair of bearing sleeves 37, 38 having wear-resistant coating layers 37a, 38a to one end and the other axial end of the rotating shaft 12. This makes it possible to suppress deterioration of the wear-resistant coating layers 37a, 38a and ensure appropriate wear-resistant coating layers 37a, 38a. [Explanation of symbols]

[0068] 10 Electric compressor 11. Housing 12 Rotation axis 12a Low pressure side shaft 12b High-pressure side shaft 12c Intermediate shaft part 12d Low pressure side flange 12e High pressure side flange 12f Axial recess 13 Stator 14 rotor 15 Low pressure wheels 16 High-pressure wheels 21 Motor housing 22 Low pressure side bearing housing 23 High pressure side bearing housing 31 Stator core 32 stator coil 33 Rotor core 33a,33b split iron core 34 Retaining sleeve 35 Low-pressure air bearing 36 High-pressure side air bearing 37 Low-pressure side bearing sleeve (bearing sleeve for air bearing) 37a Wear-resistant coating layer 38 High-pressure side bearing sleeve (bearing sleeve for air bearing) 38a Wear-resistant coating layer 39 Thrust disc 40 Low pressure side thrust sleeve 41 Low pressure side space 42 High pressure side thrust sleeve 51 Low-pressure compressor 52 Low pressure side housing 53,63 Nut 54,64 Intake port 55,65 Diffuser 56,66 Scroll section 61 High-pressure compressor 62 High pressure side housing 71 Connecting Channel 72 Low pressure side air flow path 73 High pressure air flow path 80 Rotating Body 81 Low pressure side space 82 High pressure side space

Claims

1. a rotating shaft made of a magnetic material; a rotor fixed to the rotating shaft; a pair of cylindrical bearing sleeves for air bearings, the bearing sleeves being attached to one end and the other end of the rotary shaft in the axial direction and having a wear-resistant coating layer on the outer peripheral surface; Equipped with the pair of bearing sleeves for air bearings are provided with the wear-resistant coating layer before being assembled to the rotating shaft; the rotor has a cylindrical shape and an iron core made of magnets that are divided into a plurality of parts in the circumferential direction and arranged radially outward of the rotating shaft, the rotating shaft has a pair of flange portions spaced apart in the axial direction, the iron core is disposed between the pair of flange portions, and one end and the other end in the axial direction of a cylindrical retaining sleeve are fixed to outer peripheries of the pair of flange portions, thereby integrally fixing the iron core to the rotating shaft; the retaining sleeve is fixed to the outer peripheral surfaces of the pair of flange portions and the outer peripheral surface of the iron core by shrink fitting, so that the inner peripheral surface thereof is in close contact with the outer peripheral surfaces of the pair of flange portions and the outer peripheral surface of the iron core; Rotating body.

2. the pair of air bearing sleeves are lightly press-fitted onto one end and the other end of the rotating shaft in the axial direction, respectively; The rotating body according to claim 1 .

3. a hollow housing; a cylindrical stator fixed to an inner peripheral surface of the housing; a rotating body according to claim 1 or 2, wherein the rotor is rotatably supported by the housing so as to face an inner peripheral surface of the stator with a gap therebetween; a pair of air bearings provided in the housing so as to face each other across a gap from outer peripheral surfaces of the pair of air bearing sleeves; A rotating electric machine comprising:

4. A rotating electric machine according to claim 3, a low-pressure wheel fixed to one side of the rotation shaft in the axial direction; a high-pressure wheel fixed to the other axial end of the rotary shaft; An electric compressor comprising:

5. a step of disposing a cylindrical iron core, which constitutes a rotor and is made of magnets divided into a plurality of parts in the circumferential direction, between a pair of flanges provided at an axial distance on the outer periphery of a rotating shaft made of a magnetic material; a step of fixing a cylindrical retaining sleeve to the outer peripheral surfaces of the pair of flange portions and the outer peripheral surface of the iron core by shrink fitting, thereby bringing the inner peripheral surface of the retaining sleeve into close contact with the outer peripheral surfaces of the pair of flange portions and the outer peripheral surface of the iron core; a step of attaching a pair of bearing sleeves for air bearings, each having a wear-resistant coating layer, to one end and the other end of the rotating shaft in the axial direction; A manufacturing method of a rotating body having the above structure.

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