Rotating electrical machine, electric compressor, and method for assembling stator

Abstract

In this rotating electrical machine, electric compressor, and method for assembling a stator, a housing with a hollow shape, a stator with a cylindrical shape and secured to an inner circumferential surface of the housing, and a rotor rotatably supported by the housing so as to face an inner circumferential surface of the stator across a gap are provided, wherein the stator has a stator core with a cylindrical shape, a stator coil which passes through a plurality of slots formed between a plurality of circumferentially adjacent teeth in the stator core and which is wound around the teeth, and an insulating portion that covers at least an end portion of the stator coil in the axial direction of the stator and also covers the stator coil disposed between the plurality of teeth.

Description

Rotating electric machine, electric compressor, and stator assembly method

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

[0002] Fuel cells require high-pressure air, so two-stage compression electric compressors are used. 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 have a cylindrical stator fixed to a housing, and a rotor positioned inside the stator and supported for free rotation. An example of such an electric motor is described in Patent Document 1 below.

[0003] JP 2015-116113 A

[0004] A conventional electric motor has a stator core, a stator coil formed by winding a wire around the stator core, and a resin molded portion covering the end of the stator coil, with spiral grooves formed on the surface of the resin molded portion through which a coolant flows. In this configuration, the coolant flowing through the grooves in the resin molded portion may leak into the stator coil, causing a short circuit. In addition, forming the spiral grooves on the surface of the resin molded portion results in a complex stator shape, which makes it difficult to manufacture.

[0005] The present disclosure is intended to solve the above-mentioned problems, and aims to provide a rotating electric machine, an electric compressor, and an assembly method for a stator that are miniaturized while improving reliability.

[0006] In order to achieve the above-mentioned object, the rotating electric machine of the present disclosure comprises a hollow housing, a cylindrical stator fixed to the inner surface of the housing, and a rotor rotatably supported on the housing so as to face the inner surface of the stator with a gap therebetween, the stator having a cylindrical stator core, a stator coil wound around the teeth through a plurality of slots formed between a plurality of circumferentially adjacent teeth in the stator core, and an insulating portion that covers at least the axial end of the stator coil and covers the stator coil arranged between the plurality of teeth.

[0007] 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.

[0008] In addition, the stator assembly method of the present disclosure includes the steps of positioning a cylindrical stator in the axial and circumferential directions on the inner periphery of a hollow housing, arranging the housing with the stator positioned so that the axial direction is vertical and placing a cylindrical jig below and inside the stator, and filling a molding material between the housing and the jig from above the housing.

[0009] According to the method of assembling a rotating electric machine, an electric compressor, and a stator disclosed herein, it is possible to achieve miniaturization while improving reliability.

[0010] FIG. 1 is a longitudinal sectional view showing the internal configuration of an electric compressor according to a first embodiment. FIG. 2 is a sectional view taken along line II-II of FIG. 1 showing the internal configuration of the electric compressor. FIG. 3 is a schematic view for explaining a method of assembling a stator. FIG. 4 is a longitudinal sectional view showing the internal configuration of an electric compressor according to a second embodiment. FIG. 5 is a longitudinal sectional view showing the internal configuration of an electric compressor according to a third embodiment. FIG. 6 is a sectional view taken along line VI-VI of FIG. 5 showing the internal configuration of the electric compressor. FIG. 7 is a longitudinal sectional view showing the internal configuration of an electric compressor according to a modified example of the third embodiment.

[0011] 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.

[0012] 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.

[0013] 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 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.

[0014] The housing 11 has a motor housing 21, a low-pressure side bearing housing 22, and a high-pressure side bearing housing 23. In this embodiment, the motor housing 21 and the high-pressure side bearing housing 23 are integrally formed. However, the motor housing 21 and the high-pressure side bearing housing 23 may also be formed separately and fastened together with bolts.

[0015] The motor housing 21 is cylindrical. The low-pressure side bearing housing 22 is disk-shaped and is located on one axial side (the right side in FIG. 1 ) of the motor housing 21. The low-pressure side bearing housing 22 is detachably fastened to 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 left side in FIG. 1 ). The high-pressure side bearing housing 23 is integral with the other axial end of the motor housing 21.

[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, consisting of the motor housing 21, the low-pressure side bearing housing 22, and the high-pressure side bearing housing 23, forms a hollow shape.

[0017] A 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 has a yoke 101 and multiple teeth 102. The yoke 101 is cylindrical and fixed so that its outer periphery is in close contact with the inner periphery of the motor housing 21. The multiple teeth 102 are arranged at equal intervals circumferentially on the inner periphery of the yoke 101. The stator coil 32 has multiple coil windings 103. The coil windings 103 are wound around the multiple teeth 102, with a portion of the coil windings 103 housed inside the stator core 31 and a portion exposed from the stator core 31 as low-voltage side coil ends 103a and high-voltage side coil ends 103b.

[0018] The yoke 101 is formed, for example, in a ring shape by laminating a plurality of electromagnetic steel sheets as magnetic members. The laminated electromagnetic steel sheets are fixed together, for example, by crimping or adhesive. The plurality of (12 in this embodiment) teeth 102 are formed, like the yoke 101, in a rod shape by laminating a plurality of electromagnetic steel sheets as magnetic members. The laminated electromagnetic steel sheets are fixed together, for example, by crimping. The plurality of teeth 102 extend from the inner peripheral surface of the yoke 101 toward the center (axis center O) of the yoke 101. One radial end of each of the plurality of teeth 102 is provided integrally or detachably on the inner peripheral surface of the yoke 101. The number of teeth 102 is not limited to 12.

[0019] The multiple coil windings 103 are formed by winding coils around the multiple teeth 102 from the radial outside of the yoke 101. The stator core 31 has multiple slots 104 formed by the yoke 101 and the multiple teeth 102. The multiple slots 104 are provided inside the yoke 101 and between the multiple teeth 102 that are adjacent in the circumferential direction. The multiple coil windings 103 are arranged in the multiple slots 104.

[0020] The motor housing 21 has an attachment portion 21a provided on a portion of the periphery in the circumferential direction on the low-voltage side. The connection terminal 105 is attached to the attachment portion 21a of the motor housing 21, and an end of the coil winding 103 is connected to the connection terminal 105. The connection terminal 105 is a three-phase (U, V, W) connection terminal. Power is supplied from the power supply device through the connection terminal 105 so that three types of AC currents with phases that differ from each other by 120 degrees flow through the three pairs of coils, respectively.

[0021] 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.

[0022] The inner and outer circumferential surfaces of the stator 12 and the 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 the rotor 13. Therefore, when 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. In other words, when power is supplied to the coil windings 103 of the stator 12, a rotating magnetic field that rotates circumferentially at a predetermined period is generated, and a magnetic force is generated between the magnetic poles of the rotating magnetic field and the rotor 13. Therefore, the rotor 13 rotates to follow the rotating magnetic field.

[0023] 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 .

[0024] 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.

[0025] 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.

[0026] 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.

[0027] 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.

[0028] 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.

[0029] 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.

[0030] 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 .

[0031] 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.

[0032] 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.

[0033] <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 high-pressure side cooling water flow passage 63, and a central cooling water flow passage 64.

[0034] The low-pressure side cooling water passage 62 is provided on the low-pressure wheel 14 side, radially outward from the low-pressure side coil end 103a in the motor housing 21. The high-pressure side cooling water passage 63 is provided on the high-pressure wheel 15 side, radially outward from the high-pressure side coil end 103b in the motor housing 21. The central cooling water passage 64 is provided on the radially outward from the stator core 31.

[0035] The low-pressure side cooling water flow passage 62, the high-pressure side cooling water flow passage 63, and the central cooling water flow passage 64 are provided at intervals in the axial direction of the stator 12. The low-pressure side cooling water flow passage 62, the high-pressure side cooling water flow passage 63, and the central cooling water flow passage 64 are provided along the circumferential direction of the stator 12. The low-pressure side cooling water flow passage 62, the high-pressure side cooling water flow passage 63, and the central cooling water flow passage 64 are communicated by a communication passage (not shown), and a cooling water inlet portion (not shown) and a cooling water outlet portion (not shown) are provided.

[0036] Therefore, the cooling water is supplied from the cooling water inlet to the low-pressure side cooling water flow path 62, the high-pressure side cooling water flow path 63, and the central 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.

[0037] <Stator> As described above, the stator 12 has a stator core 31 and a stator coil 32. The stator core 31 has a yoke 101 and a plurality of teeth 102, and the stator coil 32 has a plurality of coil windings 103. The coil windings 103 are wound around the plurality of teeth 102, with a portion of the coil windings 103 housed inside the stator core 31 and a portion exposed from the stator core 31 as low-voltage side coil ends 103a and high-voltage side coil ends 103b.

[0038] The stator 12 also has an insulating portion 110. The insulating portion 110 is formed by molding, in which molten resin is filled into a main portion of the stator 12 and hardened.

[0039] The insulating portion 110 covers at least the ends (low voltage side coil end 103a and high voltage side coil end 103b) of the stator coil 32 in the direction of the axis O of the stator 12, and also covers the stator coil 32 (coil winding 103) arranged in each slot 104 between the multiple teeth 102.

[0040] Specifically, the insulating portion 110 has a pair of coil end covering portions 111 a and 111 b , a coil covering portion 112 , a terminal covering portion 113 , and a connecting portion 114 .

[0041] The coil end covering portions 111a, 111b cover each end of the stator coil 32 in the direction of the axis O of the stator 12, i.e., the low-voltage side coil end 103a and the high-voltage side coil end 103b. The coil end covering portions 111a, 111b cover at least the outer circumferential portion and the inner circumferential portion of the low-voltage side coil end 103a and the high-voltage side coil end 103b, and the end in the direction of the axis O and the contact portion between the stator core 31 and the stator core 31.

[0042] The coil covering portion 112 covers the coil winding 103 of the stator coil 32 arranged in each slot 104 between the multiple teeth 102. In this case, the coil covering portion 112 is formed by filling the slot 104 with molten resin and hardening it, and therefore penetrates into the inside of the coil winding 103.

[0043] The terminal covering portion 113 covers the connection terminal 105 connected to the stator coil 32. The connection terminal 105 is attached to the mounting portion 21a of the motor housing 21, with a portion exposed to the outside of the motor housing 21 and a portion located inside the motor housing 21. An end of the coil winding 103 is connected to the portion of the connection terminal 105 located inside the motor housing 21. The terminal covering portion 113 covers the coil winding 103 extending from the low-voltage side coil end 103a and the connection terminal 105 connected to the coil winding 103.

[0044] The connecting portions 114 are arranged on the outer periphery of the stator core 31 so as to connect the pair of coil end covering portions 111 a, 111 b. A plurality of connecting portions 114 are provided between the inner periphery of the motor housing 21 and the outer periphery of the stator core 31 along the axial direction and at intervals (preferably equal intervals) in the circumferential direction.

[0045] The connecting portions 114 are arranged in a plurality of grooves 106 that are provided axially on the outer periphery of the stator core 31 and spaced apart (preferably equally spaced) in the circumferential direction. The stator core 31 has a yoke 101 and a plurality of teeth 102, and the plurality of grooves 106 are provided on the outer periphery of the yoke 101. In this case, the plurality of grooves 106 are provided at positions radially opposite each tooth 102 on the outer periphery surface of the yoke 101. The connecting portions 114 are arranged in the plurality of grooves 106 that are provided on the outer periphery of the yoke 101. Note that although the plurality of grooves 106 are provided on the outer periphery of the stator core 31, they may also be provided on the inner periphery of the motor housing 21.

[0046] <Method of Assembling the Stator> FIG. 3 is a schematic diagram for explaining a method of assembling the stator.

[0047] 1 and 3, housing 11 is formed by integrating motor housing 21 and high-pressure side bearing housing 23. Stator 12 has coil winding 103 of stator coil 32 wound around stator core 31 composed of yoke 101 and multiple teeth 102, with low-voltage side coil end 103a and high-voltage side coil end 103b exposed. Stator 12 also has multiple grooves 106 formed on the outer periphery of stator core 31 (yoke 101).

[0048] First, the cylindrical stator 12 is positioned axially and circumferentially on the inner periphery of the hollow housing 11 (the motor housing 21 and the high-pressure side bearing housing 23). In this case, it is preferable to place the stator 12 on the inner periphery of the housing 11 (the motor housing 21 and the high-pressure side bearing housing 23) and then position and fix the stator 12 axially and circumferentially by shrink fitting. At this time, the outer periphery of the stator 12 is in close contact with the inner periphery of the housing 11, and the multiple grooves 106 provide gaps along the axial direction between the inner periphery of the housing 11 and the outer periphery of the stator 12 at intervals in the circumferential direction. Note that by varying the shape of one of the multiple grooves 106, the differently shaped groove 106 may be used as a reference position when assembling the stator 12 to the housing 11, thereby defining the assembly position of the stator 12 relative to the housing 11.

[0049] Next, as shown in FIG. 3 , a jig 120 is prepared. The jig 120 has a cylindrical shape and includes a base 121, an intermediate jig 122, an upper jig 123, and a lower jig 124. The base 121, the intermediate jig 122, the upper jig 123, and the lower jig 124 are configured as separate members of the jig 120 and can be connected together with bolts. In this case, the base 121 is placed in a predetermined position, and the lower jig 124, the intermediate jig 122, and the upper jig 123 are assembled on the base 121 in this order. It is preferable that the base 121, the upper jig 123, and the lower jig 124 are made of metal, and the intermediate jig 122 is made of synthetic resin. It is preferable that the outer diameter of the intermediate jig 122 is the same as or smaller than the outer diameter of the upper jig 123. It is also preferable that the outer diameter of the lower jig 124 be the same as or smaller than the outer diameter of the intermediate jig 122 .

[0050] The jig 120 is separated into a base 121, an intermediate jig 122, an upper jig 123, and a lower jig 124. First, the lower jig 124 is inserted into the housing 11 (motor housing 21 and high-pressure side bearing housing 23) with the stator 12 positioned therein from one side in the direction of the axis O (the upper side in FIG. 3 ). At this time, the lower jig 124 is assembled so as to be positioned inside the high-pressure side coil end 103b. Next, the intermediate jig 122 is inserted into the housing 11 from one side in the direction of the axis O (the upper side in FIG. 3 ) and is brought into close contact with the lower jig 124. At this time, the intermediate jig 122 is assembled so as to be positioned inside the stator core 31. Next, the upper jig 123 is inserted into the housing 11 from one side in the direction of the axis O (the upper side in FIG. 3 ), is brought into close contact with the intermediate jig 122, and is then bolted together. At this time, the upper jig 123 is assembled so as to be positioned inside the low-voltage side coil end 103 a. Finally, the base 121 is inserted into the housing 11 from the other side in the direction of the axis O (the bottom side in FIG. 3 ), and is brought into close contact with the lower jig 124 and bolted. At this time, the base 121 is assembled so as to be positioned inside the high-voltage side coil end 103 b.

[0051] When the jig 120 is assembled to the housing 11 in which the stator 12 is positioned, the cylindrical base 121 fits into the high-pressure side bearing housing 23 of the housing 11. That is, by making the inner diameter of the circular hole in the high-pressure side bearing housing 23 the same as the outer diameter of the base 121, the base 121 fits snugly into the circular hole in the high-pressure side bearing housing 23. Also, by making the inner diameter of the stator core 31 the same as the outer diameter of the cylindrical intermediate jig 122, the outer peripheral surface of the intermediate jig 122 fits snugly into the inner peripheral surface of the stator 12. However, by making the outer diameter of the cylindrical lower jig 124 slightly smaller than the inner diameter of the high-pressure side coil end 103b, a ring-shaped gap is secured between the inner peripheral surface of the high-pressure side coil end 103b and the outer peripheral surface of the lower jig 124. Furthermore, by making the outer diameter of cylindrical upper jig 123 slightly smaller than the inner diameter of low-voltage side coil end 103a, a ring-shaped gap is secured between the inner circumferential surface of low-voltage side coil end 103a and the outer circumferential surface of upper jig 123. The upper end of upper jig 123 has a curved surface and an expanded diameter to match the shape of the inner circumferential portion of low-voltage side coil end 103a.

[0052] The housing 11 with the jig 120 attached is positioned so that the axis O is aligned vertically. Molding material (molten resin) is then filled between the housing 11 and the jig 120 from above the housing 11. The molding material filled between the housing 11 and the jig 120 then flows down due to its own weight between the motor housing 21 and the stator 12 and between the stator 12 and the upper jig 123, covering the connection terminals 105 and the low-voltage side coil ends 103a. The molding material that has flowed between the motor housing 21 and the stator 12 and between the stator 12 and the upper jig 123 then flows into the stator core 31 and covers the coil windings 103 (see FIG. 2 ) in each slot 104. In addition, the molding material that flows into the gap between the motor housing 21 and the stator 12 descends through multiple grooves 106 and covers the high-voltage side coil end 103b. Note that the molding material filling operation may be carried out in a vacuum state to make it easier for the molding material to enter the gap between the housing 11, the stator 12, and the jig 120.

[0053] That is, the molding material filled between the housing 11 and the jig 120 from above the housing 11 fills the gaps between the housing 11 (the motor housing 21 and the high-pressure side bearing housing 23), the stator 12, and the jig 120. Then, as the filled molding material hardens, the pair of coil end covering portions 111 a, 111 b, the coil covering portion 112, the terminal covering portion 113, and the connecting portion 114 are formed as the insulating portion 110.

[0054] [Second embodiment] Fig. 4 is a vertical cross-sectional view showing the internal configuration of an electric compressor according to a second embodiment. Members having the same functions as those in the first embodiment described above are denoted by the same reference numerals, and detailed description thereof will be omitted.

[0055] 4, the electric compressor 10A includes a housing 11, a stator 12, a rotor 13, a low-pressure wheel 14, and a high-pressure wheel 15. The basic configurations of the housing 11, the stator 12, the rotor 13, the low-pressure wheel 14, and the high-pressure wheel 15 are the same as those of the first embodiment.

[0056] The electric compressor 10A has an air cooling passage 71. The air cooling passage 71 cools the stator 12 with cooling air. The air cooling passage 71 has an air supply passage 72, an axial cooling passage 73, and an air discharge passage 74. The air supply passage 72 is provided along the radial direction on the side of the high-pressure side bearing housing 23. One end of the air supply passage 72 is connected to the connecting passage 53 (see FIG. 1 ). The air supply passage 72 takes in a portion of the air compressed by rotation of the low-pressure wheel 14 from the connecting passage 53 into the interior of the high-pressure side bearing housing 23 and supplies it to the high-pressure side bearing 35.

[0057] The axial cooling passage 73 is provided between the stator 12 and the rotor 13. The axial cooling passage 73 is ring-shaped, and one end thereof in the direction of the axis O communicates with the other end of the air supply passage 72 via the high-pressure-side bearing 35. The axial cooling passage 73 cools the stator 12 by causing air supplied from the air supply passage 72 to flow between the stator 12 and the rotor 13 along the direction of the axis O. The axial cooling passage 73 supplies the air that has cooled the stator 12 to the low-pressure-side bearing 34 and the thrust disk 38.

[0058] The air discharge passage 74 is provided along the radial direction on the side of the low-pressure side bearing housing 22. One end of the air discharge passage 74 communicates with the low-pressure side bearing 34 and the thrust disk 38, and the other end opens to the outside. The air discharge passage 74 discharges air that is supplied to the inside of the housing 11 and has cooled the stator 12 to the outside.

[0059] In the air cooling flow path 71, the air supply flow path 72 and the air exhaust flow path 74 are formed in the high-pressure side bearing housing 23 and the low-pressure side bearing housing 22 by, for example, machining, and the axial cooling flow path 73 is formed during molding. That is, as shown in Fig. 3, the jig 120 has a stand 121, an intermediate jig 122, an upper jig 123, and a lower jig 124. The intermediate jig 122 is made of synthetic resin, and has an outer diameter dimension that is the same as the inner diameter dimension of the stator 12, but the linear expansion coefficient of the material is made larger than the linear expansion coefficient of the material of the stator 12 (stator core 31).

[0060] The housing 11 (motor housing 21 and high-pressure side bearing housing 23) with the stator 12 positioned relative to the jig 120 is then placed, and molding material (molten resin) is filled between the housing 11 and the jig 120 from above the housing 11. The molding material filled between the housing 11 and the jig 120 flows due to its own weight between the motor housing 21, the stator 12, and the jig 120, covering the connection terminals 105, the low-voltage side coil ends 103a, the coil windings 103 in each slot 104, and the high-voltage side coil ends 103b. At this time, the jig 120 and the housing 11 into which the molding material (molten resin) is filled are maintained at a high temperature and are thermally expanding. Because the linear expansion coefficient of the material of the intermediate jig 122 is greater than the linear expansion coefficient of the material of the stator 12 (stator core 31), the intermediate jig 122 thermally expands and adheres tightly to the inner circumferential surface of the stator 12.

[0061] The filled molding material is then cooled and hardened, forming the pair of coil end covering portions 111a, 111b, the coil covering portion 112, the terminal covering portion 113, and the connecting portion 114 as the insulating portion 110. At this time, because the linear expansion coefficient of the material of the intermediate jig 122 is greater than that of the material of the stator 12 (the stator core 31), the jig 120 and the housing 11 cool and contract. Because the linear expansion coefficient of the material of the intermediate jig 122 is greater than that of the material of the stator 12 (the stator core 31), the amount of contraction of the intermediate jig 122 becomes greater than that of the stator 12, and a gap is formed between the inner circumferential surface of the intermediate jig 122 and the outer circumferential surface of the stator 12. This gap becomes the axial cooling channel 73 of the air-cooling channel 71, as shown in FIG. 4 . The molding material may also be filled with a cylindrical jig inserted between the intermediate jig 122 and the stator 12.

[0062] [Third embodiment] Fig. 5 is a longitudinal sectional view showing the internal configuration of an electric compressor according to a third embodiment, and Fig. 6 is a sectional view showing the internal configuration of the electric compressor taken along line VI-VI in Fig. 5. Note that members having the same functions as those in the first embodiment described above are given the same reference numerals, and detailed descriptions thereof will be omitted.

[0063] 5 and 6, the electric compressor 10B includes a housing 11, a stator 12, a rotor 13, a low-pressure wheel 14, and a high-pressure wheel 15. The basic configurations of the housing 11, the stator 12, the rotor 13, the low-pressure wheel 14, and the high-pressure wheel 15 are the same as those of the first embodiment.

[0064] The electric compressor 10B has an air cooling passage (refrigerant passage) 71B. The air cooling passage 71B cools the stator 12 with cooling air (refrigerant). The air cooling passage 71B has an air supply passage 72, an axial cooling passage 73B, and an air discharge passage 74. The air supply passage 72 and the air discharge passage 74 are similar to those in the second embodiment.

[0065] The axial cooling passages 73B are provided in the stator 12. The axial cooling passages 73B are provided along the axial direction of the stator 12 and at predetermined intervals (preferably equal intervals) in the circumferential direction. A plurality of axial cooling passages 73B are provided by arranging them radially inside a plurality of slots 104 of the stator core 31 that constitutes the stator 12. One end of the axial cooling passage 73B in the direction of the axis O communicates with the other end of the air supply passage 72 via the high-pressure-side bearing 35, and the other end of the axial cooling passage 73B in the direction of the axis O communicates with one end of the air discharge passage 74 via the low-pressure-side bearing 34.

[0066] The air supplied from the air supply passage 72 cools the stator 12 by flowing through the multiple axial cooling passages 73B. The air that has cooled the stator 12 is discharged to the outside through the air discharge passage 74. Note that although the multiple axial cooling passages 73B cool the stator 12 by allowing air to flow from the high-pressure side to the low-pressure side, the stator 12 may also be cooled by allowing air to flow from the low-pressure side to the high-pressure side. Furthermore, although all of the axial cooling passages 73B cool the stator 12 by allowing air to flow from the high-pressure side to the low-pressure side, the multiple axial cooling passages 73B may be connected in series by connecting adjacent ends of the multiple axial cooling passages 73B on the high-pressure side and connecting adjacent ends of the multiple axial cooling passages 73B on the low-pressure side, and the air may flow from the high-pressure side to the low-pressure side and then reverse and flow from the low-pressure side to the high-pressure side to cool the stator 12.

[0067] The axial cooling channels 73B are formed during molding. A rod or tube having the same length as the axial length of the stator 12 is placed at a predetermined position in the multiple slots 104 that make up the stator core 31, and a molding material is then filled between the housing 11 and a jig 120 (see FIG. 3). After the molding material hardens, the rod or tube is pulled out, thereby forming the axial cooling channels 73B.

[0068] [Modification] FIG. 7 is a vertical cross-sectional view showing the internal configuration of an electric compressor according to a modification of the third embodiment.

[0069] 7, the electric compressor 10C includes a housing 11, a stator 12, a rotor 13, a low-pressure wheel 14, and a high-pressure wheel 15. The basic configurations of the housing 11, the stator 12, the rotor 13, the low-pressure wheel 14, and the high-pressure wheel 15 are the same as those of the first embodiment.

[0070] The electric compressor 10C has a cooling water passage (refrigerant passage) 71C. The cooling water passage 71C uses cooling air (refrigerant) to cool the stator 12. The cooling water passage 71C has a cooling water supply passage 72C, an axial cooling passage 73C, and a cooling water discharge passage 74C.

[0071] The cooling water supply passage 72C is provided along the radial direction on the high-pressure side bearing housing 23 side. One end of the cooling water supply passage 72C communicates with the high-pressure side cooling water passage 63. The axial cooling passage 73C is provided in the stator 12. The axial cooling passages 73C are provided along the axial direction of the stator 12 and at predetermined intervals (preferably equal intervals) in the circumferential direction. A plurality of axial cooling passages 73C are provided by being arranged radially inside a plurality of slots 104 of the stator core 31 that constitutes the stator 12. One end of the axial cooling passage 73C in the direction of the axis O communicates with the other end of the cooling water supply passage 72C.

[0072] The cooling water discharge passage 74C is provided along the radial direction on the side of the low-pressure side bearing housing 22. One end of the cooling water discharge passage 74C communicates with the other end of the axial cooling passage 73C, and the other end communicates with the low-pressure side cooling water passage 62.

[0073] The cooling water in the high-pressure side cooling water flow path 63 branches from a cooling water supply flow path 72C into a plurality of axial cooling flow paths 73C and flows to cool the stator 12. The air that has cooled the stator 12 is discharged to the outside through a cooling water discharge flow path 74C.

[0074] In the cooling water flow path 71C, the manufacturing method of the axial cooling flow path 73C is the same as that of the axial cooling flow path 73B of the air cooling flow path 71B. Also, the modified method of flowing the cooling water in the cooling water flow path 71C is the same as that of the air cooling flow path 71B.

[0075] [Effects and effects of this embodiment] The rotating electric machine of the first aspect comprises a hollow housing 11, a cylindrical stator 12 fixed to the inner surface of the housing 11, and a rotor 13 rotatably supported on the housing 11 so as to face the inner surface of the stator 12 with a gap therebetween. The stator 12 has a cylindrical stator core 31, a stator coil 32 wound around the teeth 102 after passing through a plurality of slots 104 formed between a plurality of circumferentially adjacent teeth 102 in the stator core 31, and an insulating portion 110 that covers at least the end of the stator coil 32 in the direction of the axis O of the stator 12 and also covers the stator coil 32 arranged between the plurality of teeth 102.

[0076] In the rotating electric machine according to the first aspect, the low-voltage side coil end 103a, the high-voltage side coil end 103b, and the coil winding 103 in the slot 104 are covered with the insulating portion 110, which enables a design that does not require significant consideration of creepage distance and insulation distance, thereby enabling miniaturization. Furthermore, the occurrence of short circuits due to moisture can be suppressed, improving reliability. Furthermore, dimensional changes and fraying due to springback after forming of the low-voltage side coil end 103a and the high-voltage side coil end 103b and vibration during operation can be suppressed, improving manufacturability.

[0077] The rotating electric machine according to the second aspect is the rotating electric machine according to the first aspect, further comprising an insulating portion 110 having a pair of coil end covering portions 111 a, 111 b that cover each end of the stator coil 32 in the direction of the axis O of the stator 12, a coil covering portion 112 that covers the stator coil 32 disposed between the plurality of teeth 102, and a terminal covering portion 113 that covers the connection terminal 105 that is connected to the stator coil 32. This allows for miniaturization while improving reliability.

[0078] The rotating electric machine according to the third aspect is the rotating electric machine according to the first or second aspect, further comprising an insulating part 110 having a pair of coil end covering parts 111 a, 111 b that cover each end of the stator coil 32 in the direction of the axis O of the stator 12, a coil covering part 112 that covers the stator coil 32 that is disposed between the plurality of teeth 102, and a connecting part 114 that is disposed on the outer periphery of the stator core 31 so as to connect the pair of coil end covering parts 111 a, 111 b. This allows for miniaturization while improving reliability.

[0079] The rotating electric machine according to the fourth aspect is the rotating electric machine according to the third aspect, further comprising: connecting portions 114 disposed in a plurality of grooves 106 that are axially provided on the outer periphery of stator core 31 and spaced apart circumferentially. This allows for miniaturization while improving reliability. By flowing molding material from low-voltage side coil end 103a through grooves 16 to high-voltage side coil end 103b, coil end coating portions 111a, 111b can be properly formed. Furthermore, molding material with high viscosity can be used, improving ease of construction and shortening construction time.

[0080] The rotating electric machine according to the fifth aspect is the rotating electric machine according to the fourth aspect, further comprising: a stator core 31 having a cylindrical yoke 101 and a plurality of teeth 102 extending radially inward from the inner periphery of the yoke 101 and spaced apart in the circumferential direction, and grooves 106 being provided on the outer periphery of the yoke 101 radially opposing the teeth 102. This allows the grooves 106 to be formed without affecting the rotating magnetic field that rotates in the circumferential direction of the yoke 101.

[0081] A rotating electric machine according to a sixth aspect is the rotating electric machine according to any one of the first to fifth aspects, and further, the insulating part 110 is formed by molding, in which molten resin is filled into a main part of the stator 12 and hardened. This allows the insulating part 110 to be formed appropriately.

[0082] The rotating electric machine according to a seventh aspect is the rotating electric machine according to any one of the first to sixth aspects, and further includes axial cooling passages 73, 73b, 73c that supply coolant to the radially inner sides of the plurality of slots 104. This allows the inside of the stator core 31, which has a high temperature, to be efficiently cooled, thereby improving cooling performance and performance.

[0083] The electric compressor according to the eighth aspect includes a rotating electric machine and a low-pressure wheel (compressor wheel) 14 fixed to one axial end of a rotor 13. This allows for miniaturization while improving reliability.

[0084] The stator assembly method according to the ninth aspect includes the steps of positioning cylindrical stator 12 axially and circumferentially on the inner periphery of hollow housing 11, placing housing 11 with stator 12 positioned therein so that the axial direction is vertical and placing cylindrical jig 120 below and inside stator 12, and filling molding material from above housing 11 between housing 11 and jig 120. This allows for miniaturization while improving reliability.

[0085] A stator assembly method according to a tenth aspect is the stator assembly method according to the ninth aspect, further comprising: a plurality of axially extending grooves 106 spaced circumferentially on at least one of the inner periphery of the housing 11 and the outer periphery of the stator 12; the stator 12 is positioned on the inner periphery of the housing 11 by shrink fitting; and the molding material filled between the housing 11 and the jig 120 covers the low-voltage coil end 103a of the stator 12 and descends through the grooves 106 to cover the high-voltage coil end 103b of the stator. This allows the coil end coatings 111a and 111b to be properly formed. Furthermore, a molding material with high viscosity can be used, improving ease of construction and shortening construction time.

[0086] A stator assembling method according to an eleventh aspect is the stator assembling method according to the ninth or tenth aspect, further comprising the steps of: setting the inner diameter of the stator 12 and the outer diameter of the jig 120 to be approximately the same diameter; and setting the linear expansion coefficient of the jig 120 to be larger than the linear expansion coefficient of the stator 12. This allows the axial cooling flow passage 73 to be appropriately formed between the stator 12 and the rotor 13.

[0087] In the above-described embodiment, the electric compressors 10, 10A, 10B, and 10C are described as being applied to two-stage compression electric compressors, but the present invention is not limited to this configuration. That is, the electric compressors 10, 10A, 10B, and 10C may be single-stage compression electric compressors in which the low-pressure wheel 14 constituting the low-pressure compressor 41 is attached to one axial side of the rotor 13, and the high-pressure wheel 15 constituting the high-pressure compressor 42 is not attached to the other axial side of the rotor 13.

[0088] Furthermore, in the above-described embodiment, the electric compressors 10, 10A, 10B, and 10C are 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 rotor 13, and the turbine wheel constituting the turbine is attached to the other axial side of the rotor 13.

[0089] Furthermore, in the above-described embodiment, the rotating electric machine is applied to the electric compressors 10, 10A, 10B, and 10C, but it may be applied to other rotating electric machines or electric compressors.

[0090] REFERENCE SIGNS LIST 10, 10A, 10C Electric compressor 11 Housing 12 Stator 13 Rotor 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 core 32 Stator coil 33 Rotor 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 High-pressure side cooling water passage 64 Central cooling water passage 71, 71B Air cooling passage 72 Air supply passage 73, 73B Axial cooling passage 74 Air discharge passage 71C Cooling water passage 72C Cooling water supply passage 73C Axial cooling passage 74C Cooling water discharge passage 101 Yoke 102 Teeth 103 Coil winding 103a Low-voltage side coil end 103b High-voltage side coil end 104 Slot 105 Connection terminal 106 Groove portion

Claims

1. A rotating electric machine comprising: a hollow housing; a cylindrical stator fixed to the inner peripheral surface of the housing; and a rotor rotatably supported by the housing so as to face the inner peripheral surface of the stator with a gap therebetween, wherein the stator has: a cylindrical stator core; stator coils wound around the teeth and passing through a plurality of slots formed between a plurality of circumferentially adjacent teeth on the stator core; and an insulating portion covering at least the end of the stator coil in the axial direction of the stator and covering the stator coil arranged between the plurality of teeth.

2. A rotating electric machine according to claim 1, wherein the insulating portion comprises a pair of coil end covering portions that cover each end of the stator coil in the axial direction of the stator, a coil covering portion that covers the stator coil arranged between the plurality of teeth, and a terminal covering portion that covers a connection terminal connected to the stator coil.

3. A rotating electric machine as described in claim 1, wherein the insulating portion has a pair of coil end covering portions that cover each end of the stator coil in the axial direction of the stator, a coil covering portion that covers the stator coil arranged between the plurality of teeth, and a connecting portion that is arranged on the outer periphery of the stator core so as to connect the pair of coil end covering portions.

4. A rotating electric machine according to claim 3, wherein the connecting portions are arranged in a plurality of grooves provided axially on the outer periphery of the stator core and spaced apart in the circumferential direction.

5. A rotating electric machine according to claim 4, wherein the stator core has a cylindrical yoke and a plurality of teeth extending radially inward from the inner periphery of the yoke and spaced apart circumferentially, and the grooves are provided on the outer periphery of the yoke radially opposite the teeth.

6. The rotating electric machine according to claim 1, wherein the insulating portion is formed by molding, in which molten resin is filled into a main portion of the stator and hardened.

7. A rotating electric machine according to claim 1, wherein a coolant passage is provided to supply coolant to the radially inner sides of the plurality of slots.

8. An electric compressor comprising: the rotating electric machine according to claim 1; and a compressor wheel fixed to one side of the rotor in the axial direction.

9. A method for assembling a stator, comprising the steps of: positioning a cylindrical stator in the axial and circumferential directions on the inner periphery of a hollow housing; arranging the housing with the stator positioned so that its axial direction is vertical, and placing a cylindrical jig below and inside the stator; and filling a molding material between the housing and the jig from above the housing.

10. A method for assembling a stator as set forth in claim 9, wherein at least one of the inner periphery of the housing and the outer periphery of the stator has a plurality of axial grooves spaced apart in the circumferential direction, the stator is positioned on the inner periphery of the housing by shrink fitting, and the molding material filled between the housing and the jig covers one axial coil end of the stator and passes down through the grooves to cover the other axial coil end of the stator.

11. A method for assembling a stator according to claim 9 or 10, wherein the inner diameter of the stator and the outer diameter of the jig are set to be approximately the same diameter, and the linear expansion coefficient of the jig is set to be larger than the linear expansion coefficient of the stator.

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