Rotor, rotary electric machine, electric compressor, and method for assembling rotor

Abstract

Provided are a rotor, a rotary electric machine, an electric compressor, and a method for assembling the rotor, comprising: an iron core comprising a cylindrical magnet; a first end plate fixed to one axial-direction end part of the iron core, and a second end plate fixed to the other axial-direction end part of the iron core; a first hollow shaft of which one axial-direction end part is fitted to the end part of the first end plate, and a second hollow shaft of which one axial-direction end part is fitted to the end part of the second end plate; and an outer sleeve disposed outside of the iron core, the first end plate, the second end plate, the one end part of the first hollow shaft, and the one end part of the second hollow shaft.

Description

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

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

[0002] Fuel cells require high-pressure air, and therefore employ two-stage compression electric compressors. To improve the efficiency of two-stage compression electric compressors, they must operate at high speeds. When the electric compressor is a centrifugal compression type, it becomes possible to design highly efficient blades, enabling the motor to be made smaller and lighter. Electric motors (motors) used in electric compressors generally employ permanent magnets in the rotor, and transmit the rotational torque generated by the permanent magnets to the rotating shaft. To reduce the rotor weight, a hollow rotor may be employed. An example of such an electric motor rotor is described in Patent Document 1 below.

[0003] Utility Model Registration No. 3243375

[0004] The rotor of a conventional electric compressor is composed of three parts: a magnet (permanent magnet), a pair of hollow shafts, and an outer sleeve, all of which are joined by welding. When the outer sleeve and hollow shaft are thin components, there is a risk of thermal deformation due to welding. Since thermal deformation after welding affects the rotational balance of the rotor, the rotor surface must be finished after welding, which increases the number of work steps. However, because the rotor is an axially long component, finishing is a difficult task, which also increases the number of work steps.

[0005] 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 rotor assembly method that achieve weight reduction while improving workability in assembly work.

[0006] In order to achieve the above-mentioned object, the rotating body of the present disclosure comprises an iron core made of a cylindrical magnet, a first end plate fixed to one axial end of the iron core and a second end plate fixed to the other axial end of the iron core, a first hollow shaft having one axial end that fits into the end of the first end plate and a second hollow shaft having one axial end that fits into the end of the second end plate, and an outer sleeve arranged outside the iron core, the first end plate, the second end plate, one end of the first hollow shaft, and one end of the second hollow shaft.

[0007] In addition, the rotating electric machine of the present disclosure comprises a hollow housing, a cylindrical stator fixed to the inner surface of the housing, and the rotating body applied as a rotor rotatably supported on the housing so as to face the inner surface of the stator with a gap therebetween.

[0008] The electric compressor according to the present disclosure includes the rotating electric machine and a compressor wheel fixed to one side of the rotor in the axial direction.

[0009] Furthermore, the method for assembling a rotating body disclosed herein includes the steps of press-fitting a first opening on one axial side of a first hollow shaft into an end of a first end plate and press-fitting a second opening on one axial side of a second hollow shaft into an end of a second end plate; adhering the first end plate to one axial end of a cylindrical iron core and adhering the second end plate to the other axial end of the iron core; machining at least the outer peripheral surfaces of the first opening, the second opening, and the iron core to the same outer diameter; and arranging an outer sleeve around the iron core, the first end plate, the second end plate, the first opening, and the second opening, and fixing them by shrink fitting.

[0010] According to the rotating body, rotating electric machine, electric compressor, and method of assembling the rotating body of the present disclosure, it is possible to reduce the weight while improving the workability in the assembly work.

[0011] Fig. 1 is a longitudinal sectional view showing the internal configuration of an electric compressor of a first embodiment. Fig. 2 is a longitudinal sectional view showing a rotating body of the first embodiment. Fig. 3 is a schematic view for explaining a method for assembling the rotating body. Fig. 4 is a longitudinal sectional view showing a rotating body of a second embodiment. Fig. 5 is a longitudinal sectional view showing a rotating body of a third embodiment. Fig. 6 is a longitudinal sectional view showing a rotating body of a fourth embodiment. Fig. 7 is a longitudinal sectional view showing a rotating body of a fifth embodiment.

[0012] 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.

[0013] First Embodiment <Configuration of Electric Compressor> FIG. 1 is a cross-sectional view showing the internal configuration of an electric compressor according to a first embodiment.

[0014] As shown in Fig. 1, the electric compressor 10 is a two-stage compression type electric compressor. The electric compressor 10 includes a housing 11, a stator 12, a rotor (rotating body) 13, a low-pressure wheel 14, and a high-pressure wheel 15. The housing 11, the stator 12, and the rotor 13 constitute a rotating electric machine.

[0015] 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. The low-pressure side bearing housing 22 is disk-shaped and is located on one axial side of the motor housing 21 (the right side in FIG. 1 ). The low-pressure side bearing housing 22 is detachably fastened to one axial end of the motor housing 21 with a plurality of bolts (not shown). The high-pressure side bearing housing 23 is disk-shaped and is located on the other axial side of the motor housing 21 (the left side in FIG. 1 ). 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 (not shown).

[0016] One axial opening of the motor housing 21 is closed by the low-pressure side bearing housing 22, and the other axial opening is closed by the high-pressure side bearing housing 23. Therefore, the housing 11 has a hollow shape when the low-pressure side bearing housing 22 and the high-pressure side bearing housing 23 are fastened to the motor housing 21.

[0017] The stator 12 is fixed to the inner periphery of the motor housing 21. The stator 12 is cylindrical. The stator 12 has a stator core 31 and a stator coil 32. The stator core 31 is cylindrical and fixed so that its outer periphery is in close contact with the inner periphery of the motor housing 21. The stator coil 32 is wound around the stator core 31 and partially housed inside the stator core 31, with the low-voltage side end and high-voltage side end of the coil end exposed from the stator core 31.

[0018] The rotor 13 is disposed inside the housing 11. The rotor 13 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. The rotor 13 has a rotor core (permanent magnet) 33. The rotor core 33 has a cylindrical shape.

[0019] The inner and outer circumferential surfaces of the stator 12 and rotor 13 face each other in the radial direction. A gap is provided between the inner and outer circumferential surfaces of the stator 12 and rotor 13. Therefore, when a current flows through the stator coil 32 of the stator 12, the rotor 13 rotates due to the attractive and repulsive forces of the generated magnetic force, and outputs a rotational force.

[0020] The rotor 13 is rotatably supported at one axial end thereof via a low-pressure side bearing 34 relative to the housing 11 , and at the other axial end thereof via a high-pressure side bearing 35 .

[0021] Low-pressure side bearing housing 22 has a circular hole formed at the position of axis O, and low-pressure side bearing 34 is disposed in the circular hole. High-pressure side bearing housing 23 has a circular hole formed at the position of axis O, and high-pressure side bearing 35 is disposed in the circular hole. Low-pressure side bearing 34 and high-pressure side bearing 35 are cylindrical. Rotor 13 is inserted through low-pressure side bearing 34 and high-pressure side bearing 35, and is rotatably supported relative to housing 11 via low-pressure side bearing 34 and high-pressure side bearing 35.

[0022] The low-pressure side bearing 34 is a journal bearing, such as an air bearing. The high-pressure side bearing 35 is also a journal bearing, such as an air bearing. However, the low-pressure side bearing 34 and the high-pressure side bearing 35 are not limited to air bearings.

[0023] A thrust disk 38 constituting a thrust bearing is fixed to one axial side (low-pressure side) of the rotor 13. The thrust disk 38 is rotatable integrally with the rotor 13. The thrust disk 38 is housed in a space in the low-pressure side bearing housing 22.

[0024] The housing 11 has a low-pressure compressor 41 disposed on the low-pressure side bearing housing 22 side, and a high-pressure compressor 42 disposed on the high-pressure side bearing housing 23 side. The low-pressure compressor 41 has a low-pressure side housing 43 and a low-pressure wheel 14. The high-pressure compressor 42 has a high-pressure side housing 44 and a high-pressure wheel 15.

[0025] The low-pressure side housing 43 is fastened to the outer surface of the low-pressure side bearing housing 22 by a plurality of bolts. The low-pressure wheel 14 functions as a compressor wheel and is disposed inside the low-pressure side housing 43. The low-pressure wheel 14 is fitted onto one axial end of the rotor 13 so as to be rotatable together with the rotor 13, and fastened with a nut 45. The low-pressure compressor 41 is provided with an intake port 46, a diffuser portion 47, a scroll portion 48 having a spiral shape, and a discharge port (not shown) by the low-pressure side housing 43 and the low-pressure wheel 14.

[0026] The high-pressure side housing 44 is fastened to the outer surface of the high-pressure side bearing housing 23 with a plurality of bolts. The high-pressure wheel 15 functions as a compressor wheel and is disposed inside the high-pressure side housing 44. The high-pressure wheel 15 is fitted onto one axial end of the rotor 13 so as to be rotatable together with the rotor 13, and fastened with a nut 49. The high-pressure compressor 42 is provided with a suction port 50, a diffuser portion 51, a scroll portion 52 having a spiral shape, and a discharge port (not shown) by the high-pressure side housing 44 and the high-pressure wheel 15.

[0027] The low-pressure compressor 41 and the high-pressure compressor 42 have their discharge ports (not shown) and suction ports 50 connected by a connecting flow path 53 .

[0028] The low-pressure wheel 14 is fitted with a piston ring 55 and is rotatably supported relative to the low-pressure side bearing housing 22. The high-pressure wheel 15 is fitted with a piston ring 56 and is rotatably supported relative to the high-pressure side bearing housing 23. The piston rings 55, 56 prevent compressed air from leaking from the inside of the housing 11 to the outside.

[0029] When the low-pressure wheel 14 rotates, the low-pressure compressor 41 draws in external air through an inlet 46 and accelerates and pressurizes it by the centrifugal force of the low-pressure wheel 14. The accelerated and pressurized air is decelerated by a diffuser section 47, flows through a scroll section 48, and is discharged from a discharge port. The low-pressure air compressed by the low-pressure compressor 41 is supplied to the high-pressure compressor 42 through a connecting flow path 53. When the high-pressure wheel 15 rotates, the high-pressure compressor 42 draws in external air through an inlet 50 and accelerates and pressurizes it by the centrifugal force of the high-pressure wheel 15. The accelerated and pressurized air is decelerated by a diffuser section 51, flows through a scroll section 52, and is discharged from a discharge port.

[0030] <Cooling Water Flow Passage> The cooling water flow passage 61 is provided radially outward of the stator 12 in the housing 11. The cooling water flow passage 61 has a low-pressure side cooling water flow passage 62, a first high-pressure side cooling water flow passage 63, and a second high-pressure side cooling water flow passage 64.

[0031] The low-pressure side cooling water passage 62 is provided on the low-pressure wheel 14 side, radially outward of the stator core 31 in the motor housing 21. The first high-pressure side cooling water passage 63 is provided on the high-pressure wheel 15 side, radially outward of the stator core 31 in the motor housing 21. The second high-pressure side cooling water passage 64 is provided on the high-pressure wheel 15 side of the stator core 31 in the high-pressure side bearing housing 23.

[0032] The low-pressure side cooling water flow path 62, the first high-pressure side cooling water flow path 63, and the second high-pressure side cooling water flow path 64 are provided at intervals in the axial direction of the stator 12. The low-pressure side cooling water flow path 62, the first high-pressure side cooling water flow path 63, and the second high-pressure side cooling water flow path 64 are provided along the circumferential direction of the stator 12. The low-pressure side cooling water flow path 62, the first high-pressure side cooling water flow path 63, and the second high-pressure side cooling water flow path 64 are communicated by a communication flow path (not shown). The low-pressure side cooling water flow path 62, the first high-pressure side cooling water flow path 63, and the second high-pressure side cooling water flow path 64 are provided with a cooling water inlet portion (not shown) and a cooling water outlet portion (not shown).

[0033] Therefore, the cooling water is supplied from the cooling water inlet to the low-pressure side cooling water flow path 62, the first high-pressure side cooling water flow path 63, and the second high-pressure side cooling water flow path 64, and cools the stator 12. The cooling water that has cooled the stator 12 is discharged from the cooling water outlet.

[0034] <Air Cooling Passage> The air cooling passage 71 is provided radially outward of the stator 12 in the housing 11. The air cooling passage 71 has an air supply passage 72 and an air discharge passage (not shown). The air supply passage 72 is provided on the low-pressure side bearing housing 22 side of the motor housing 21. The air supply passage 72 is connected to the connecting passage 53. The air supply passage 72 supplies a portion of the air compressed by rotation of the low-pressure wheel 14 from the connecting passage 53 to the inside of the housing 11. The compressed air supplied to the inside of the housing 11 cools the stator 12.

[0035] The air exhaust flow path exhausts the air that has been supplied to the inside of the housing 11 to cool the stator 12 to the outside.

[0036] <Rotor> FIG. 2 is a vertical cross-sectional view showing the rotor of the first embodiment.

[0037] As shown in FIG. 2 , the rotor (rotating body) 13 includes a rotor core 33 , a first end plate 101 and a second end plate 102 , a first hollow shaft 103 and a second hollow shaft 104 , and an outer sleeve 105 .

[0038] The rotor core 33 is made of a permanent magnet and has a cylindrical shape with a predetermined length, and the outer diameter along the axis O is substantially the same.

[0039] The first end plate 101 has a disk shape. The first end plate 101 has a first plate body 111 and a first fitting portion 112. The first plate body 111 has a disk shape. The first fitting portion 112 also has a disk shape and has an outer diameter smaller than that of the first plate body 111. The outer diameter of the first end plate 101 is approximately the same as the outer diameter of the rotor core 33.

[0040] The second end plate 102 has a disk shape. The second end plate 102 has a second plate body 121 and a second fitting portion 122. The second plate body 121 has a disk shape. The second fitting portion 122 also has a disk shape and has an outer diameter smaller than that of the second plate body 121. In the second end plate 102, the outer diameter of the second plate body 121 is approximately the same as the outer diameter of the rotor core 33.

[0041] The first hollow shaft 103 has a first shaft portion 131, a first support portion 132, and a first fitting portion 133. The first shaft portion 131, the first support portion 132, and the first fitting portion 133 are integrally formed. The first support portion 132 is cylindrical, with the first shaft portion 131 provided on one side in the direction of the axis O and the first fitting portion 133 provided on the other side in the direction of the axis O. The first support portion 132 has an outer diameter larger than that of the first shaft portion 131 and is provided with a first hollow portion 134 therein. The first fitting portion 133 is cylindrical, with an outer diameter larger than that of the first support portion 132 and is provided with a first opening 135 therein. The first opening 135 has an inner diameter larger than that of the first hollow portion 134. The first hollow shaft 103 has a first fitting portion 133 whose outer diameter is approximately the same as the outer diameter of the rotor core 33 .

[0042] The second hollow shaft 104 has a second shaft portion 141, a second support portion 142, and a second fitting portion 143. The second shaft portion 141, the second support portion 142, and the second fitting portion 143 are integrally formed. The second support portion 142 has a cylindrical shape, with the second shaft portion 141 provided on one side in the direction of the axis O and the second fitting portion 143 provided on the other side in the direction of the axis O. The second support portion 142 has an outer diameter larger than that of the second shaft portion 141 and is provided with a second hollow portion 144 therein. The second fitting portion 143 has a cylindrical shape, an outer diameter larger than that of the second support portion 142, and is provided with a second opening 145 therein. The second opening 145 has an inner diameter larger than that of the second hollow portion 144. The second hollow shaft 104 has a second fitting portion 143 with an outer diameter that is substantially the same as the outer diameter of the rotor core 33 .

[0043] One end of the first hollow shaft 103 in the direction of the axis O is fitted into the end of the first end plate 101. The first opening 135 of the first fitting portion 133 of the first hollow shaft 103 is press-fitted into the first fitting portion 112 of the first end plate 101, thereby fixing the first hollow shaft 103 and the first end plate 101 together. At this time, the first hollow portion 134 is in a substantially sealed state.

[0044] One end of the second hollow shaft 104 in the direction of the axis O is fitted into the end of the second end plate 102. The second opening 145 of the second fitting portion 143 of the second hollow shaft 104 is press-fitted into the second fitting portion 122 of the second end plate 102, thereby fixing the second hollow shaft 104 and the second end plate 102 together. At this time, the second hollow portion 144 is in a substantially sealed state.

[0045] The rotor core 33 has a first end plate 101 fixed to an end face 33a on one side in the direction of the axis O, and a second end plate 102 fixed to an end face 33b on the other side in the direction of the axis O. The first end plate 101 has an end face 111a of a first plate body 111 bonded to an end face 33a of the rotor core 33 with an adhesive. The second end plate 102 has an end face 121a of a second plate body 121 bonded to an end face 33b of the rotor core 33 with an adhesive. This fixes the rotor core 33, first end plate 101, and first hollow shaft 103 together, and also fixes the rotor core 33, second end plate 102, and second hollow shaft 104 together.

[0046] The outer sleeve 105 has a cylindrical shape of a predetermined length and is arranged outside the rotor core 33, the first end plate 101, the second end plate 102, one end of the first hollow shaft 103, and one end of the second hollow shaft 104. The outer sleeve 105 is arranged outside the rotor core 33, the first end plate 101, the second end plate 102, the first fitting portion 133, and the second fitting portion 143.

[0047] In this case, with the first hollow shaft 103, first end plate 101, rotor core 33, second end plate 102, and second hollow shaft 104 fixed together, the outer diameters of the first fitting portion 133, first end plate 101, rotor core 33, second end plate 102, and second fitting portion 143 are machined so that the outer diameters become approximately the same in the axial direction. The outer sleeve 105 is inserted around the first fitting portion 133, first end plate 101, rotor core 33, second end plate 102, and second fitting portion 143, and is fixed by shrink fitting.

[0048] Therefore, welding for assembling the rotor 13 is not required, thermal deformation due to welding is also eliminated, the area of ​​the rotor 13 that needs to be finished on the surface is reduced, and the number of work steps is reduced.

[0049] The first end plate 101 has a first plate body 111 and a first fitting portion 112, and the second end plate 102 has a second plate body 121 and a second fitting portion 122. The tightening force of the outer sleeve 105 is received by the first plate body 111 of the first end plate 101, the second plate body 121 of the second end plate 102, and the first fitting portion 133 of the first hollow shaft 103 and the second fitting portion 143 of the second hollow shaft 104. Although the first fitting portion 133 and the second fitting portion 143 are hollow, because they are located in the first end plate 101 and the second end plate 102, deformation of the first hollow shaft 103 and the second hollow shaft 104 is suppressed.

[0050] <Method of Assembling Rotor> FIG. 3 is a schematic diagram for explaining a method of assembling the rotor.

[0051] 2 and 3 , first, the first opening 135 of the first hollow shaft 103 is press-fitted into the first fitting portion 112 of the first end plate 101. Then, the second opening 145 of the second hollow shaft 104 is press-fitted into the second fitting portion 122 of the second end plate 102.

[0052] Next, the first plate body 111 of the first end plate 101 is bonded to the end face 33a of the rotor core 33. Furthermore, the second plate body 121 of the second end plate 102 is bonded to the end face 33b of the rotor core 33. This fixes the first hollow shaft 103, the first end plate 101, the rotor core 33, the second end plate 102, and the second hollow shaft 104 together.

[0053] Next, the outer diameters of the first fitting portion 133 of the first hollow shaft 103, the first plate body 111 of the first end plate 101, the rotor core 33, the second plate body 121 of the second end plate 102, and the second fitting portion 143 of the second hollow shaft 104 are cut to make the outer diameters approximately the same in the axial direction.

[0054] Then, the outer sleeve 105 is inserted around the first fitting portion 133 of the first hollow shaft 103, the first plate body 111 of the first end plate 101, the rotor core 33, the second plate body 121 of the second end plate 102, and the second fitting portion 143 of the second hollow shaft 104, and fixed by shrink fitting. Here, a coating process is applied to the outer peripheral surface of the first support portion 132 of the first hollow shaft 103 and the outer peripheral surface of the second support portion 142 of the second hollow shaft 104.

[0055] 1, first, low-pressure side bearing 34 and high-pressure side bearing 35 are assembled to motor housing 21 to which stator 12 has been assembled, and rotor 13 is inserted and assembled inside. Next, low-pressure side bearing housing 22 and high-pressure side bearing housing 23 are fastened to motor housing 21. Next, low-pressure wheel 14 and high-pressure wheel 15 are attached to rotor 13, and low-pressure side housing 43 and high-pressure side housing 44 are fastened.

[0056] 4 is a longitudinal sectional view showing a rotating body of a second embodiment. Note that members having the same functions as those in the second embodiment described above are given the same reference numerals, and detailed description thereof will be omitted.

[0057] As shown in FIG. 4, the rotor (rotating body) 13A includes a rotor core 33, a first end plate 101, a second end plate 102, a first hollow shaft 103, a second hollow shaft 104, and an outer sleeve 105.

[0058] In the rotor 13A, a first gap S1 is provided between the first end plate 101 and the outer sleeve 105, and a second gap S2 is provided between the second end plate 102 and the outer sleeve 105.

[0059] The first end plate 101 has a first plate body 111 and a first fitting portion 112. The outer diameter of the first plate body 111 of the first end plate 101 is slightly smaller than the outer diameter of the rotor core 33 and the outer diameter of the first fitting portion 133 of the first hollow shaft 103. Therefore, a first radial gap S1 is formed between the outer peripheral surface of the first plate body 111 of the first end plate 101 and the inner peripheral surface of the outer sleeve 105.

[0060] The second end plate 102 has a second plate body 121 and a second fitting portion 122. The outer diameter of the second plate body 121 of the second end plate 102 is slightly smaller than the outer diameter of the rotor core 33 and the outer diameter of the second fitting portion 143 of the second hollow shaft 104. Therefore, a second radial gap S2 is formed between the outer peripheral surface of the second plate body 121 of the second end plate 102 and the inner peripheral surface of the outer sleeve 105. The radial dimensions of the first gap S1 and the second gap S2 are preferably in the range of 0.05 μm to 1.00 mm, for example.

[0061] The shrink fitting process generates a tightening force in the outer sleeve 105, which presses against the first fitting portion 133 of the first hollow shaft 103, the first plate body 111 of the first end plate 101, the rotor core 33, the second plate body 121 of the second end plate 102, and the second fitting portion 143 of the second hollow shaft 104. At this time, the first gap S1 and the second gap S2 allow the outer sleeve 105 to press against the first fitting portion 133 of the first hollow shaft 103, the rotor core 33, and the second fitting portion 143 of the second hollow shaft 104, and by appropriately pressing against the rotor core 33, tensile stress generated at the axial end portions is reduced.

[0062] In the rotor 13A, the first end plate 101, the second end plate 102, and the outer sleeve 105 are made of Inconel, and the first hollow shaft 103 and the second hollow shaft 104 are made of carbon steel. Inconel and carbon steel have different linear expansion coefficients. Due to the difference in linear expansion coefficients between the first hollow shaft 103, the second hollow shaft 104, and the outer sleeve 105, the pressing force on the rotor core 33 is reduced, and tensile stress generated at the end of the rotor core 33 increases. As a result, the increased tensile stress can be canceled out by this gap, allowing the first hollow shaft 103 to be made of low-cost carbon steel.

[0063] Furthermore, the relationship between the press-fit length L1 of the first fitting portion 112 of the first end plate 101 relative to the first opening 135 of the first hollow shaft 103 and the fitting length L2 between the first fitting portion 133 of the first hollow shaft 103 and the outer sleeve 105 is important in the assembly process. If the press-fit length L1 is too long, the press-fit process becomes difficult, but if it is too short, there is a risk of it falling off. Therefore, the relationship between the press-fit length L1 and the fitting length L2 is preferably as follows: In this case, the press-fit length L1 can be adjusted by adjusting the press-fit allowance: 0.3L2<L1<0.8L2

[0064] 5 is a longitudinal sectional view showing a rotating body of a third embodiment. Note that members having the same functions as those in the second embodiment described above are given the same reference numerals, and detailed description thereof will be omitted.

[0065] As shown in FIG. 5, the rotor (rotating body) 13B includes a rotor core 33, a first end plate 101, a second end plate 102, a first hollow shaft 103, a second hollow shaft 104, and an outer sleeve 105.

[0066] The outer sleeve 105 is fixed to the rotor core 33 and the first mating portion 133 of the first hollow shaft 103 and the second mating portion 143 of the second hollow shaft 104 by shrink fitting, and the interference caused by the shrink fitting between the rotor core 33 and the outer sleeve 105 increases from the first end plate 101 side toward the second end plate 102 side.

[0067] As shown in Figures 1 and 5, when the electric compressor 10 is driven, a rotor 13 rotates relative to a stator 12 fixed to a housing 11, and air is compressed by a low-pressure wheel 14 and a high-pressure wheel 15. Although the interior of the housing 11 is air-cooled, a temperature difference occurs between one end and the other end of the rotor 13 in the direction of the axis O. For example, the rotor 13 has a higher temperature on the low-pressure side (right side in Figures 1 and 5) than on the high-pressure side (left side in Figures 1 and 5).

[0068] The shrink-fitting process generates a tightening force in the outer sleeve 105, which presses against the first fitting portion 133 of the first hollow shaft 103, the first plate body 111 of the first end plate 101, the rotor core 33, the second plate body 121 of the second end plate 102, and the second fitting portion 143 of the second hollow shaft 104. At this time, the outer sleeve 105 is fitted in an axially stretched state, so residual tensile strain is generated in the outer sleeve 105 from the center to the ends in the axial direction. When the electric compressor 10 is running, the rotor 13 heats up and the residual strain is released, causing the outer sleeve 105, the first hollow shaft 103, and the second hollow shaft 104 to shift axially. This could cause the first hollow shaft 103 and the second hollow shaft 104 to be re-fixed in a bent state with respect to the axis O, potentially resulting in imbalance in the rotor 13.

[0069] For example, as shown in A of Fig. 5, the inner diameter of the outer sleeve 105 is gradually reduced from the first end plate 101 side (high-pressure side) toward the second end plate 102 side (low-voltage side). Also, as shown in B of Fig. 5, the outer diameter of the rotor core 33 is gradually increased from the first end plate 101 side (high-pressure side) toward the second end plate 102 side (low-voltage side). By adjusting the inner diameter of the outer sleeve 105 and the outer diameter of the rotor core 33, the interference caused by the shrink fit between the outer sleeve 105 and the rotor core 33 can be changed within the dimensional tolerances of the outer sleeve 105 and the rotor core 33.

[0070] 5A and 5B, a gap is shown between the rotor core 33 and the outer sleeve 105 to explain the changes in interference, but this gap is within the dimensional tolerance range, and in reality, there is no gap between the rotor core 33 and the outer sleeve 105. In other words, the interference caused by the shrink fit between the rotor core 33 and the outer sleeve 105 increases from the first end plate 101 side toward the second end plate 102 side. As a result, because the shrink fit is performed from one side, residual tensile strain in the axial direction is less likely to occur.

[0071] As a result, the occurrence of residual tensile strain in the outer sleeve 105 from the center toward the end in the axial direction is suppressed, and when the electric compressor 10 is operating, the outer sleeve 105, the first hollow shaft 103, and the second hollow shaft 104 shift axially when the residual strain is released, which prevents the first hollow shaft 103 and the second hollow shaft 104 from bending relative to the axis O, and suppresses imbalance that occurs in the rotor 13.

[0072] 6 is a longitudinal sectional view showing a rotating body of a fourth embodiment. Note that members having the same functions as those in the second embodiment described above are given the same reference numerals, and detailed description thereof will be omitted.

[0073] As shown in FIG. 6, the rotor (rotating body) 13C includes a rotor core 33, a first end plate 101, a second end plate 102, a first hollow shaft 103, a second hollow shaft 104, and an outer sleeve 105.

[0074] The rotor 13C has a first communication portion 151 in the first end plate 101 that connects the first hollow portion 134 to the outside, and a second communication portion 152 in the second end plate 102 that connects the second hollow portion 144 to the outside.

[0075] The first fitting portion 112 of the first end plate 101 and the first opening 135 of the first hollow shaft 103 are connected by press-fitting. At this time, the first hollow portion 134 is almost sealed. Therefore, a large reaction force acts when the first fitting portion 112 is pressed into the first opening 135. Also, the second fitting portion 122 of the second end plate 102 and the second opening 145 of the second hollow shaft 104 are connected by press-fitting. At this time, the second hollow portion 144 is almost sealed. Therefore, a large reaction force acts when the second fitting portion 122 is pressed into the second opening 145.

[0076] As shown in A of FIG. 6 , the first end plate 101 has a first communicating portion 151 formed as a first communicating hole at the position of the axis O. Therefore, when the first fitting portion 112 of the first end plate 101 is press-fitted into the first opening 135 of the first hollow shaft 103, air in the first hollow portion 134 is discharged to the outside through the first communicating portion 151, thereby reducing the pushing reaction force. Furthermore, the second end plate 102 has a second communicating portion 152 formed as a second communicating hole at the position of the axis O. Therefore, when the second fitting portion 122 of the second end plate 102 is press-fitted into the second opening 145 of the second hollow shaft 104, air in the second hollow portion 144 is discharged to the outside through the second communicating portion 152, thereby reducing the pushing reaction force. As a result, the first fitting portion 112 of the first end plate 101 can be press-fitted a predetermined length into the first opening 135 of the first hollow shaft 103. Also, the second fitting portion 122 of the second end plate 102 can be press-fitted a predetermined length into the second opening 145 of the second hollow shaft 104. This facilitates assembly of the first end plate 101 and the first hollow shaft 103, and also facilitates assembly of the second end plate 102 and the second hollow shaft 104.

[0077] However, the first communicating portion 151 and the second communicating portion 152 are not limited to communicating holes. As shown in FIG. 6B , the first end plate 101 has a first slit serving as a first communicating portion 153 formed on its outer periphery. The first communicating portion (first slit) 153 is formed continuously between the end face of the first plate body 111 and the outer periphery of the first fitting portion 112. Therefore, when the first fitting portion 112 of the first end plate 101 is press-fitted into the first opening 135 of the first hollow shaft 103, air in the first hollow portion 134 is discharged to the outside through the first communicating portion 153, reducing the pushing reaction force and facilitating the assembly of the first end plate 101 and the first hollow shaft 103. Although not shown, the second end plate 102 also has a second slit serving as a second communicating portion formed on its outer periphery.

[0078] It is preferable that the first communicating portion 151 and the second communicating portion 152 are provided at the position of the axis O of the first end plate 101, but they may be offset from the position of the axis O. Furthermore, a plurality of first communicating portions 151, 153 and a plurality of second communicating portions 152 may be provided.

[0079] 7 is a longitudinal sectional view showing a rotating body of a fifth embodiment. Note that members having the same functions as those in the second embodiment described above are given the same reference numerals, and detailed description thereof will be omitted.

[0080] As shown in FIG. 7, the rotor (rotating body) 13D includes a rotor core 33, a first end plate 101, a second end plate 102, a first hollow shaft 103, a second hollow shaft 104, and an outer sleeve 105.

[0081] The rotor 13D has a first through-hole 161 and a second through-hole 162 formed in the outer sleeve 105. The first through-hole 161 is a first through-hole that passes radially through the outer sleeve 105. The first through-hole 161 is provided on the first hollow shaft 103 side of the contact portion (adhesion portion) between the rotor core 33 and the first end plate 101. The second through-hole 162 is a second through-hole that passes radially through the outer sleeve 105. The second through-hole 162 is provided on the second hollow shaft 104 side of the contact portion (adhesion portion) between the rotor core 33 and the second end plate 102.

[0082] An end face 111a of the first plate body 111 in the first end plate 101 is bonded to an end face 33a of the rotor core 33 with an adhesive. An end face 121a of the second plate body 121 in the second end plate 102 is bonded to an end face 33b of the rotor core 33 with an adhesive. The adhesive is, for example, an acrylic or epoxy resin, but is not limited to these adhesives.

[0083] Furthermore, after the rotor core 33, the first end plate 101, the second end plate 102, the first hollow shaft 103, the second hollow shaft 104, and the outer sleeve 105 are assembled, a coating process is applied to the outer peripheral surface of the first support portion 132 of the first hollow shaft 103 and the outer peripheral surface of the second support portion 142 of the second hollow shaft 104. The high-pressure side bearing 35 is attached to the outer peripheral portion of the first support portion 132, and the low-pressure side bearing 34 is attached to the outer peripheral surface of the second support portion 142, so each needs to be coated.

[0084] The coating process is performed on the first hollow shaft 103 and the second hollow shaft 104 at a high temperature of, for example, 500°C in a vacuum atmosphere, and during this process, the adhesive on the bonding surfaces between the first end plate 101 and the rotor core 33 and the second end plate 102 and the rotor core 33 vaporizes and leaks out from the end of the outer sleeve 105. The gas from the vaporized adhesive flows onto the outer peripheral surface of the first support portion 132 of the first hollow shaft 103 and the outer peripheral surface of the second support portion 142 of the second hollow shaft 104, making the coating process difficult.

[0085] The outer sleeve 105 has a first through-portion 161 provided at a position radially opposing the first end plate 101, and a second through-portion 162 provided at a position radially opposing the second end plate 102. Therefore, during the coating process, gas generated by evaporation of the adhesive on the bonding surfaces between the first end plate 101 and the rotor core 33 is discharged to the outside through the first through-portion 161, preventing the gas from flowing onto the outer peripheral surface of the first support portion 132 of the first hollow shaft 103. Furthermore, gas generated by evaporation of the adhesive on the bonding surfaces between the second end plate 102 and the rotor core 33 is discharged to the outside through the second through-portion 162, preventing the gas from flowing onto the outer peripheral surface of the second support portion 142 of the second hollow shaft 104.

[0086] Furthermore, when the rotor 13D is assembled inside the housing 11 (see FIG. 1), the balance of the rotational phase of the rotor 13D is adjusted. At this time, the detector detects the first through-hole 161 and the second through-hole 162 as reference positions, which facilitates the balance adjustment of the rotational phase of the rotor 13D.

[0087] Since the first through-hole 161 is provided at a position radially opposite the first end plate 101 and the second through-hole 162 is provided at a position radially opposite the second end plate 102, it is preferable to provide a first gap S1 (see Figure 4) between the first end plate 101 and the outer sleeve 105 and a second gap S2 (see Figure 4) between the second end plate 102 and the outer sleeve 105, as in the second embodiment.

[0088] However, the first through portion 161 and the second through portion 162 are not limited to being provided at positions that face each other in the radial direction of the first end plate 101 and the second end plate 102. The first through portion 161 only needs to be provided closer to the first hollow shaft 103 than the adhesive portion between the rotor core 33 and the first end plate 101, and the second through portion 162 only needs to be provided closer to the second hollow shaft 104 than the contact portion (adhesive portion) between the rotor core 33 and the second end plate 102.

[0089] Furthermore, although one first through-portion 161 and one second through-portion 162 are provided in the outer sleeve 105, a plurality of them may be provided at positions offset in the circumferential direction or the axial direction.

[0090] [Effects and effects of this embodiment] The rotating body of the first aspect comprises a rotor core 33 consisting of a cylindrical magnet, a first end plate 101 fixed to one axial end of the rotor core 33 and a second end plate 102 fixed to the other axial end of the rotor core 33, a first hollow shaft 103 having one axial end that fits into the end of the first end plate 101 and a second hollow shaft 104 having one axial end that fits into the end of the second end plate 102, and an outer sleeve 105 arranged outside the rotor core 33, the first end plate 101, the second end plate 102, one end of the first hollow shaft 103 and one end of the second hollow shaft 104.

[0091] According to the rotating body of the first aspect, the outer sleeve 105 is fixed to the outside of the first fitting portion 133, the first end plate 101, the rotor core 33, the second end plate 102, and the second fitting portion 143. This allows for a reduction in weight while improving the workability of the assembly work.

[0092] The rotating body according to the second aspect is the rotating body according to the first aspect, and further, the outer sleeve 105 is fixed by shrink fitting to the outside of at least one end of the first hollow shaft 103 and one end of the second hollow shaft 104. This eliminates the need for welding to assemble the rotor 13, eliminates thermal deformation due to welding, reduces the area of ​​the rotor 13 that needs to be finished on the surface, and reduces the number of work steps.

[0093] A rotating body according to a third aspect is the rotating body according to the first or second aspect, further comprising: a first opening 135 formed at one axial end of the first hollow portion 134 of the first hollow shaft 103, the first opening 135 fitting into an end of the first end plate 101; and a second opening 145 formed at one axial end of the second hollow portion 144 of the second hollow shaft 104, the second opening 145 fitting into an end of the second end plate 102. By making the first hollow shaft 103 and the second hollow shaft 104 hollow, the weight can be reduced, and by fitting the ends of the first hollow shaft 103 and the second hollow shaft 104 into the ends of the first end plate 101 and the second end plate 102, the strength of the first hollow shaft 103 and the second hollow shaft 104 can be increased to suppress deformation.

[0094] The rotating body of the fourth aspect is the rotating body of the third aspect, and furthermore, the first end plate 101 has a first plate body 111 having a disk shape and a first fitting portion 112 having a diameter smaller than the outer diameter of the first plate body 111, and the first opening 135 fits onto the outside of the first fitting portion 112, the second end plate 102 has a second plate body 121 having a disk shape and a second fitting portion 122 having a diameter smaller than the outer diameter of the second plate body 121, and the second opening 145 fits onto the outside of the second fitting portion 122, and the outer sleeve 105 fits onto the outside of the first opening 135 and the outside of the second opening 145. As a result, the tightening force of the outer sleeve 105 is received by the first plate body 111 of the first end plate 101 and the second plate body 121 of the second end plate 102, thereby suppressing deformation of the first hollow shaft 103 and the second hollow shaft 104 due to the tightening force of the outer sleeve 105.

[0095] The rotating body according to the fifth aspect is the rotating body according to any one of the first to fourth aspects, further comprising a first gap S1 between the first end plate 101 and the outer sleeve 105, and a second gap S2 between the second end plate 102 and the outer sleeve 105. This prevents the outer sleeve 105 from applying a large clamping force to the first end plate 101 and the second end plate 102, and by appropriately pressing the outer peripheral surface of the rotor core 33, tensile stress generated at the ends in the axial direction is reduced, making it possible to suppress damage to the rotor core 33.

[0096] A rotating body according to a sixth aspect is the rotating body according to any one of the first to fifth aspects, further comprising: a shrink-fitted outer sleeve 105 fixed to at least the rotor core 33, one end of the first hollow shaft 103, and one end of the second hollow shaft 104; and an interference between the rotor core 33 and the outer sleeve 105 due to the shrink-fitting increases from the first end plate 101 toward the second end plate 102. As a result, when the electric compressor 10 is operating, residual strain is released and the outer sleeve 105, the first hollow shaft 103, and the second hollow shaft 104 are displaced in the axial direction, which prevents the first hollow shaft 103 and the second hollow shaft 104 from bending relative to the axis O, thereby suppressing imbalance in the rotor 13.

[0097] A rotating body according to a seventh aspect is the rotating body according to any one of the first to sixth aspects, further comprising: first end plate (101) having first communication portions (151, 153) communicating first hollow portion (134) with the outside; and second end plate (102) having second communication portion (152) communicating second hollow portion (144) with the outside. Thus, when first fitting portion (112) of first end plate (101) is press-fitted into first opening (135) of first hollow shaft (103), air in first hollow portion (134) is discharged to the outside through first communication portion (151), thereby reducing the pushing reaction force. Furthermore, when second fitting portion (122) of second end plate (102) is press-fitted into second opening (145) of second hollow shaft (104), air in second hollow portion (144) is discharged to the outside through second communication portion (152), thereby reducing the pushing reaction force. As a result, it is possible to ensure an appropriate fitting length between the first end plate 101 and the first hollow shaft 103 and between the second end plate 102 and the second hollow shaft 104. This also improves the ease of assembly between the first end plate 101 and the first hollow shaft 103 and between the second end plate 102 and the second hollow shaft 104.

[0098] A rotating body according to an eighth aspect is the rotating body according to any one of the first to seventh aspects, and further, the outer sleeve 105 is provided with a first through portion 161 that penetrates radially from the contact portion (bonding portion) between the rotor core 33 and the first end plate 101 toward the first hollow shaft 103, and a second through portion 162 that penetrates radially from the contact portion (bonding portion) between the rotor core 33 and the second end plate 102 toward the second hollow shaft 104. As a result, gas generated by evaporation of the adhesive on the bonding surfaces between the first end plate 101 and the rotor core 33 during the coating process is discharged to the outside through the first through portion 161, and is prevented from flowing onto the outer peripheral surface of the first support portion 132 of the first hollow shaft 103. Furthermore, gas generated by vaporization of the adhesive on the bonding surface between the second end plate 102 and the rotor core 33 is discharged to the outside through the second through-hole 162, and is prevented from flowing onto the outer circumferential surface of the second support part 142 of the second hollow shaft 104. As a result, the coating process can be carried out satisfactorily.

[0099] A rotating electric machine according to a ninth aspect includes a hollow housing 11, a cylindrical stator 12 fixed to the inner circumferential surface of the housing 11, and the rotating body according to claim 1 applied as rotor 13 rotatably supported by the housing 11 so as to face the inner circumferential surface of the stator 12 with a gap therebetween. This makes it possible to reduce the weight of the rotors 13, 13A, 13B, 13C, 13D while improving the workability of assembly work.

[0100] The electric compressor according to the tenth aspect includes a rotating electric machine and a low-pressure wheel (compressor wheel) 14 fixed to one axial end of the rotor 13. This allows the rotors 13, 13A, 13B, 13C, and 13D to be lighter in weight, while improving the workability of assembly work.

[0101] The method for assembling a rotating body according to the eleventh aspect includes the steps of press-fitting a first opening 135 on one axial side of a first hollow shaft 103 into the end of a first end plate 101 and press-fitting a second opening 145 on one axial side of a second hollow shaft 104 into the end of a second end plate 102; adhering the first end plate 101 to one axial end of a cylindrical rotor core 33 and adhering the second end plate 102 to the other axial end of the rotor core; machining at least the outer surfaces of the first opening 135, the second opening 145, and the outer surface of the rotor core 33 to the same outer diameter; and arranging an outer sleeve 105 on the outside of the rotor core 33, the first end plate 101, the second end plate 102, the first opening 135, and the second opening 145, and fixing them by shrink fitting. This allows the rotors 13, 13A, 13B, 13C, and 13D to be lighter in weight, while improving the workability in assembly work.

[0102] In the above embodiment, the electric compressor 10 is described as being applied to a two-stage compression type electric compressor, but is not limited to this configuration. That is, the electric compressor may be a single-stage compression type electric compressor in which the low-pressure wheel 14 constituting the low-pressure compressor 41 is attached to one axial side of the rotors 13, 13A, 13B, 13C, and 13D, and the high-pressure wheel 15 constituting the high-pressure compressor 42 is not attached to the other axial side of the rotors 13, 13A, 13B, 13C, and 13D.

[0103] Furthermore, in the above-described embodiment, the electric compressor 10 has been described as being applied to a two-stage compression type electric compressor, but, for example, the configuration may be such that the low-pressure wheel 14 constituting the low-pressure compressor 41 is attached to one axial side of the rotors 13, 13A, 13B, 13C, and 13D, and the turbine wheel constituting the turbine is attached to the other axial side of the rotors 13, 13A, 13B, 13C, and 13D.

[0104] In the above-described embodiment, the rotating body or the rotating electric machine is applied to the electric compressor 10, but it may be applied to other rotating electric machines or electric compressors.

[0105] REFERENCE SIGNS LIST 10 Electric compressor 11 Housing 12 Stator 13, 13A, 13B, 13C, 13D Rotor (rotating body) 14 Low-pressure wheel 15 High-pressure wheel 21 Motor housing 22 Low-pressure side bearing housing 23 High-pressure side bearing housing 31 Stator iron core 32 Stator coil 33 Rotor iron core 34 Low-pressure side bearing 35 High-pressure side bearing 38 Thrust disk 41 Low-pressure compressor 42 High-pressure compressor 43 Low-pressure side housing 44 High-pressure side housing 45, 49 Nut 46, 50 Intake port 47, 51 Diffuser section 48, 52 Scroll section 53 Connecting passage 55, 56 Piston ring 61 Cooling water passage 62 Low-pressure side cooling water passage 63 First high-pressure side cooling water passage 64 Second high-pressure side cooling water passage 71 Air cooling flow path 72 Air supply flow path 101 First end plate 102 Second end plate 103 First hollow shaft 104 Second hollow shaft 105 Outer sleeve 111 First plate body 112 First fitting portion 121 Second plate body 122 Second fitting portion 131 First shaft portion 132 First support portion 133 First fitting portion 134 First hollow portion 135 First opening 141 Second shaft portion 142 Second support portion 143 Second fitting portion 144 Second hollow portion 145 Second opening 151, 153 First communication portion 152 Second communication portion 161 First penetration portion 162 Second penetration portion S1 First gap S2 Second gap

Claims

1. A rotating body comprising: an iron core made of a cylindrical magnet; a first end plate fixed to one axial end of the iron core and a second end plate fixed to the other axial end of the iron core; a first hollow shaft having one axial end that fits into the end of the first end plate and a second hollow shaft having one axial end that fits into the end of the second end plate; and an outer sleeve arranged outside the iron core, the first end plate, the second end plate, one end of the first hollow shaft, and one end of the second hollow shaft.

2. The rotating body according to claim 1, wherein the outer sleeve is fixed to the outside of at least one end of the first hollow shaft and one end of the second hollow shaft by shrink fitting.

3. A rotating body as described in claim 1 or claim 2, wherein the first hollow shaft has a first opening formed at one axial end of the first hollow section, the first opening fitting into the end of the first end plate, and the second hollow shaft has a second opening formed at one axial end of the second hollow section, the second opening fitting into the end of the second end plate.

4. A rotating body as described in claim 3, wherein the first end plate has a first plate body having a disk shape and a first fitting portion having a diameter smaller than the outer diameter of the first plate body, and the first opening fits onto the outside of the first fitting portion, the second end plate has a second plate body having a disk shape and a second fitting portion having a diameter smaller than the outer diameter of the second plate body, and the second opening fits onto the outside of the second fitting portion, and the outer sleeve fits onto the outside of the second opening and the outside of the second opening.

5. The rotating body according to claim 1, wherein a first gap is provided between the first end plate and the outer sleeve, and a second gap is provided between the second end plate and the outer sleeve.

6. A rotating body as described in claim 1, wherein the outer sleeve is fixed by shrink fitting to at least the iron core, one end of the first hollow shaft, and one end of the second hollow shaft, and the interference caused by the shrink fitting between the iron core and the outer sleeve increases from the first end plate side toward the second end plate side.

7. A rotating body as described in claim 3, wherein the first end plate is provided with a first communication portion that connects the first hollow portion with the outside, and the second end plate is provided with a second communication portion that connects the second hollow portion with the outside.

8. A rotating body as described in claim 1, wherein the outer sleeve is provided with a first through-portion that penetrates radially from the contact point between the iron core and the first end plate toward the first hollow shaft, and a second through-portion that penetrates radially from the contact point between the iron core and the second end plate toward the second hollow shaft.

9. A rotating electric machine comprising: a hollow housing; a cylindrical stator fixed to the inner peripheral surface of said housing; and the rotating body according to claim 1, which is used as a rotor rotatably supported by said housing so as to face the inner peripheral surface of said stator with a gap therebetween.

10. An electric compressor comprising: the rotating electric machine according to claim 9; and a compressor wheel fixed to one side of the rotor in the axial direction.

11. A method for assembling a rotating body, comprising the steps of: press-fitting a first opening on one axial side of a first hollow shaft into an end of a first end plate, and press-fitting a second opening on one axial side of a second hollow shaft into an end of a second end plate; bonding the first end plate to one axial end of a cylindrical iron core, and bonding the second end plate to the other axial end of the iron core; machining at least the outer peripheral surfaces of the first opening, the second opening, and the iron core to the same outer diameter; and arranging an outer sleeve around the iron core, the first end plate, the second end plate, the first opening, and the second opening, and fixing them together by shrink fitting.

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