METHOD FOR MANUFACTURING A STATOR

Abstract

A method for manufacturing a stator comprises a first and a second process. The first process includes: coating the stator windings with a first electrical insulating resin; and curing the first electrical insulating resin at a temperature (temperatures) higher than the glass transition temperature of the first electrical insulating resin. The second process comprises: after the first process, coating the windings with a second electrical insulating resin and curing the second electrical insulating resin at a temperature (temperatures) higher than the glass transition temperature of the second electrical insulating resin. The glass transition temperature of the first electrical insulating resin is higher than the glass transition temperature of the second electrical insulating resin.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to a method for manufacturing a stator. BACKGROUND

[0002] In the past, a technique for forming an insulating layer of an electrically insulating resin on a surface of the respective stator windings of a stator for a rotating electric machine has been proposed. Specifically, a method for forming the insulating layer from a varnish, which is an electrically insulating resin, has been proposed to increase the bonding strength of the stator windings relative to a stator core of the stator. Furthermore, a technique for forming the insulating layer from a powder resin, which is an electrically insulating resin, has been proposed to electrically insulate, for example, welded portions of the stator windings.

[0003] At the time of forming the insulating layer from the electrical insulating resin, the electrical insulating resin is applied to the stator windings or the stator windings are coated with the electrical insulating resin, and the electrical insulating resin is cured in a state of a predetermined high temperature. For example, according to the technology described in JP 5 728 981 B2, first, an insulating layer is formed by a powder resin in portions of the stator windings (specifically, in portions of conductor segments that are connected to each other by welding), and then another insulating layer is formed by a varnish in portions of the stator windings that are fixed to the stator core. At the time of forming each of these insulating layers, each of the above-described resin materials is cured in a high-temperature state. SUMMARY

[0004] In the case where the insulating layers on the stator windings are formed using different electrical insulating resins, each with a different glass transition temperature, the following problem arises. Specifically, assume that one of the insulating layers is formed with the electrical insulating resin having a relatively low glass transition temperature in a pre-process, and then the other of the insulating layers is formed with the electrical insulating resin having a relatively high glass transition temperature in a post-process. In this case, at the time of forming the other insulating layer in the post-process, the resin material used in the pre-process is excessively heated, which may damage the insulating layer.For example, if the glass transition temperature of the varnish used in the post-process is higher than the glass transition temperature of the powder resin used in the pre-process, excessive heating of the powder resin will occur in the post-process, causing the temperature of the powder resin to become high after the powder resin has cured. This can increase the stress after cooling and lead to cracks and / or flaking in the insulating layer.

[0005] The present disclosure addresses the above-described disadvantage, and it is an object of the present disclosure to provide a method for manufacturing a stator that can properly form various kinds of insulating layers when these insulating layers are respectively formed by various kinds of electrical insulating resins each having different glass transition temperatures.

[0006] According to a first aspect of the present disclosure, there is provided a method of manufacturing a stator including a plurality of conductor wires wound to form a plurality of windings, the method comprising: a first process that includes the following steps: Coating the majority of the windings with a first electrical insulating resin subsequently curing the first electrical insulating resin at a temperature or temperatures higher than the glass transition temperature of the first electrical insulating resin; and thereby forming a first insulating layer of the first electrical insulating resin on each of the plurality of windings; and a second process that includes the following steps: after the first process, coating the majority of the windings with a second electrical insulating resin; subsequently curing the second electrical insulating resin at a temperature or temperatures higher than the glass transition temperature of the second electrical insulating resin; and thereby forming a second insulating layer of the second electrical insulating resin on each of the plurality of windings, wherein the glass transition temperature of the first electrical insulating resin is higher than the glass transition temperature of the second electrical insulating resin.

[0007] During the manufacture of the stator, in the first process, the majority of the windings are coated with the first electrical insulating resin having the higher glass transition temperature and then cured at one or more temperatures (hereinafter also referred to as temperature(s)) higher than the glass transition temperature of the first electrical insulating resin. In this way, the first insulating layer is formed. Furthermore, in the second process, the majority of the windings are coated with the second electrical insulating resin having the lower glass transition temperature and then cured at the temperature(s) higher than the glass transition temperature of the second electrical insulating resin. In this way, the second insulating layer is formed.In this case, at the time of curing the second electrical insulating resin in the post-process (the second process), it is not necessary to set the temperature(s) to excessively high temperatures that are excessively higher than the temperature(s) at the time of curing the first electrical insulating resin in the pre-process (the first process), and thereby it is possible to limit the occurrence of disadvantages such as damage to the first insulating layer. Therefore, in the case where the insulating layers are formed on each of the plurality of windings using different electrical insulating resins each having different glass transition temperatures, the insulating layers can be properly formed.

[0008] According to a second aspect, the method according to the first aspect is provided, wherein: The first process step includes heating the plurality of windings; and after performing the heating of the plurality of windings and coating the plurality of windings with the first electrical insulating resin in the first process, coating the plurality of windings with the second electrical insulating resin is performed in the second process in a state where a temperature of the plurality of windings is maintained higher than the glass transition temperature of the second electrical insulating resin, thereby enabling the second electrical insulating resin to cure.

[0009] After heating the stator windings and coating the stator windings with the first electrical insulating resin, the temperature of the stator windings gradually decreases. However, in the case where the glass transition temperature of the first electrical insulating resin is higher than the glass transition temperature of the second electrical insulating resin, it is conceivable that the temperature of the stator windings during or after curing the first electrical insulating resin is higher than the curing temperature(s) required to cure the second electrical insulating resin. Therefore, the second insulating layer can be formed with the second electrical insulating resin without reheating the stator windings at the time of coating the stator windings with the second electrical insulating resin. In this case, reheating of the stator windings in the second process is not required.Therefore, the time required to form the insulating layers can be shortened and the costs can be reduced.

[0010] According to a third aspect, there is provided the method for manufacturing a stator according to the first or second aspect, wherein the plurality of windings are brought into a state in which a decrease in temperature of the plurality of windings is limited by a heat-retaining member after coating the plurality of windings with the first electrical insulating resin in the first process step.

[0011] During the heating and curing of the first electrical insulating resin, which has a relatively high glass transition temperature, in the first process, the heat of the stator windings is stored by the heat storage element. In this case, the temperature decrease of the stator windings is slowed after the heating of the stator windings is completed. Therefore, it is possible to reduce the heating temperature of the stator windings in the first process and shorten the curing time of the first electrical insulating resin.

[0012] Furthermore, in the case where the coating and curing of the second electrical insulating resin are carried out without reheating the stator windings in the second process, the occurrence of the disadvantage that the temperature of the stator windings inadvertently decreases below the desired temperature and thereby the second electrical insulating resin is not properly cured can be limited.

[0013] According to a fourth aspect, a method of manufacturing according to any one of the first to third aspects is provided, wherein in the first process, the coating of the plurality of windings with the first electrical insulating resin is carried out while heating the plurality of windings.

[0014] In the first process, the stator windings are coated with the first electrical insulating resin while heating the stator windings. This limits the temperature decrease of the stator windings during the coating of the plurality of windings with the first electrical insulating resin, which in turn shortens the curing time of the first electrical insulating resin. By shortening the curing time of the first electrical insulating resin, unwanted flow of the first electrical insulating resin into an unintended area can be limited, thereby limiting the influence on the coating of the second electrical insulating resin in the second process. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] The drawings described herein are intended to illustrate only selected embodiments and not all possible implementations and should therefore not be interpreted as limiting the scope of the present invention to the pictorial disclosure. Fig. 1 is an axial cross-sectional view of a rotating electric machine according to an embodiment. Fig. 2 is an overall perspective view of a stator. Fig. Figure 3 is an explanatory diagram showing the insertion of conductor segments into a stator core. Fig. 4 is an enlarged partial view of the front of the stator. Fig. 5 is a flowchart showing the process steps for forming the cover portions of the stator windings. Fig. 6 is a time chart showing the transition or the course of the winding temperature at the time of formation of the cover sections. Fig. 7 is an explanatory diagram illustrating the process of forming a first cover portion. Fig. 8 is an explanatory diagram explaining the process of forming a second cover portion. Fig. Figure 9 is a diagram showing the state of heat retention of the stator by a heat retention element. Fig. 10 is a time chart showing the winding temperature variation at the time of formation of the cover portions. Fig. 11 is a time chart showing the winding temperature variation at the time of formation of the cover portions. Fig. 12 is a time chart showing the winding temperature variation at the time of forming the cover portions. Fig. 13 is a time chart showing the winding temperature variation at the time of formation of the cover portions. DETAILED DESCRIPTION

[0016] Hereinafter, embodiments of a rotating electric machine according to the present disclosure will be described with reference to the drawings. In the present embodiment, an electric motor serving as a rotating electric machine is used as an electric motor for a vehicle or an electric motor for an aircraft. The rotating electric machine of the present embodiment may be, for example, a permanent magnet synchronous motor, a wound field motor, or an induction machine, and the rotating electric machine of the present embodiment has three-phase windings. Among the following embodiments and modifications, portions that are the same as or equivalent to each other are denoted by the same reference numerals, and redundant description of these portions is omitted for simplicity.

[0017] As in Fig. 1, the rotating electric machine 10 includes: a rotor 12 fixed to a rotating shaft 11; a stator 13 installed to surround the rotor 12; and a casing 14 enclosing the rotor 12 and the stator 13. The rotating electric machine 10 is an inner-rotor type rotating electric machine, and the rotor 12 is rotatably disposed on a radially inner side of the stator 13. In the present embodiment, an axial direction refers to an axial direction of a rotational axis of the rotating shaft 11, and a radial direction refers to a direction perpendicular to the rotational axis of the rotating shaft 11. Furthermore, a circumferential direction refers to a circumferential direction around the rotational axis of the rotating shaft 11.

[0018] The housing 14 includes a pair of casing members 14a, 14b, each formed in a bottomed tubular shape. The casing members 14a, 14b are fixed by bolts 15 in a state where openings of the casing members 14a, 14b are adjacent to each other. Two bearings 16, 17 are installed in the housing 14, and the rotatable shaft 11 and the rotor 12 are rotatably supported by the bearings 16, 17. The rotor 12 is arranged on the radially inner side of the stator 13 and includes a plurality of magnetic poles arranged at predetermined intervals circumferentially on an outer periphery of the rotor 12 so that the polarities of the magnetic poles are alternately changed in the circumferential direction. These magnetic poles are formed by a plurality of permanent magnets embedded on the rotor 12 at respective predetermined positions.

[0019] Next, the stator 13 is described. As shown in the Fig. 2 and Fig. As shown in Figure 3, the stator 13 includes: a stator core 20 formed in a circular ring shape and having a plurality of slots 21 arranged in the circumferential direction; and a plurality of stator windings 30 wound around the slots 21 of the stator core 20. The stator windings 30 include a U-phase winding, a V-phase winding, and a W-phase winding as phase windings, each provided for a corresponding one of the phases. A portion of the respective stator windings 30 that overlaps with the stator core 20 in the axial direction is referred to as a coil-side portion CS.Further, a portion of the respective stator windings 30 that protrudes axially outward from the stator core 20 on one axial side is referred to as a first coil end portion CE1, and another portion of the respective stator windings 30 that protrudes axially outward from the stator core 20 on the other axial side is referred to as a second coil end portion CE2.

[0020] The stator core 20 includes: a rear yoke 23 formed in a circular ring shape; and a plurality of teeth 24 projecting radially inward from the rear yoke 23 and arranged at predetermined intervals in the circumferential direction. Each of the slots 21 is formed between two corresponding adjacent teeth 24. Each of the slots 21 is shaped such that an opening of the slot is elongated in the radial direction, and the slots 21 are arranged at equal intervals in the circumferential direction on the stator core 20. The stator windings 30 are installed in a state where the stator windings 30 are wound around the slots 21. The stator core 20 is formed as a core-sheet laminated body including a plurality of core sheets made of electrical steel sheets made of a magnetic material and stacked in the axial direction.

[0021] The stator windings 30 are configured such that the three phase windings are connected in a Y-connection (star connection). When electric power (alternating current) from a power supply is supplied to the stator windings 30 through an inverter (not shown), a magnetic flux is generated. The stator windings 30 are formed using a plurality of conductor segments 40. Each of the conductor segments 40 is in the form of a segment conductor formed by processing an electrical conductor with a generally rectangular cross-section (planar rectangular cross-section) into a U-shape. The conductor segments 40 serve as conductor wires. The construction of the stator windings 30 will be described in detail below.

[0022] As in Fig. 3, each of the conductor segments 40 is generally U-shaped and includes: a pair of straight portions 41, each of which is straight; and a bent portion 42 bent to connect the two straight portions 41 together. The two straight portions 41 each have a length greater than the axial thickness of the stator core 20. The conductor segment 40 is formed by a flat, rectangular conductor wire formed by covering a conductor 51 having a rectangular cross section with an insulating coating 52. The insulating coating 52 is removed at an end portion 43, which is a distal end portion of each straight portion 41, to form an exposed conductor portion where the conductor 51 is exposed.

[0023] The corresponding conductor segments 40 are inserted into each of the slots 21 of the stator core 20 such that these conductor segments 40 are arranged straight in the radial direction in the slot 21. In the present embodiment, the corresponding conductor segments 40 are accommodated in each slot 21 in a stacked state in which the corresponding straight portions 41 of the conductor segments 40 form eight layers in the slot 21. The pair of straight portions 41 of each conductor segment 40 are each accommodated in two corresponding slots 21 spaced from each other by a predetermined coil pitch. A part of each straight portion 41 accommodated in the corresponding slot 21 is the coil-side portion CS. An insulating layer 26 is inserted into each of the slots 21 to electrically insulate the stator core 20 and the stator windings 30 (the conductor segments 40) from each other.The insulating layer 26 is folded to collectively surround the conductor segments 40 inserted into the slot 21, and the insulating layer 26 is held between an inner peripheral surface (inner wall surface) of the stator core 20 and the conductor segments 40 in the slot 21.

[0024] The two straight sections 41 of each conductor segment 40 are each received in the corresponding two slots 21, such that a radial position of one of the straight sections 41 is radially offset from a radial position of the other straight section 41. For example, if one of the straight sections 41 is received at an nth position from a radially outermost position (back of the yoke) in one slot 21, the other of the straight sections 41 is received at a position n+1 from the radially outermost position in the other slot 21.

[0025] At the time of inserting each conductor segment 40 into the corresponding slots 21 of the stator core 20, the straight portions 41 of each conductor segment 40 are inserted from a first end of the stator core 20 under the first and second ends of the stator core 20, and the end portions 43 of the straight portions 41 protrude from the second end of the stator core 20. In this case, the wound portion 42 of the conductor segment 40 forms the first end portion CE1 of the coil at the first end of the stator core 20. Furthermore, at the second end of the stator core 20, a part of each straight portion 41 opposite the winding portion 42 is bent in the circumferential direction, and the end portions 43 (more precisely, the welding portions of the end portions 43) of the various conductor segments 40 are connected by welding to form the second end portion CE2 of the coil.

[0026] On the stator 13, an insulation cover is applied to the stator windings 30, and this construction is described below. Specifically, the insulation cover is applied to each coil end portion CE1, CE2 and the coil side portion CS of the respective stator windings 30, and Fig. 4 shows an overview of this configuration. Fig. 4 is a front view of the stator 13.

[0027] In Fig. 4, among the two opposite axial sides of the stator core 20, the winding portion 42 of the conductor segments 40 is the first coil end portion CE1, and the end portion 43 of the conductor segments 40 is the second coil end portion CE2. Furthermore, an overlap area of ​​the conductor segments 40 that overlaps with the stator core 20 is the coil side portion CS. On the stator windings 30, a first cover portion 61 is formed on each conductor segment 40 except for the welding portion of the end portion 43, and a second cover portion 62 is formed on a portion of the conductor segment 40 corresponding to the welding portion of the end portion 43. In other words, the first cover portion 61 is formed to cover the entire area of ​​the first coil end portion CE1 and the entire area of ​​the coil side portion CS and the part of the second coil end portion CE2 other than the welding portion of the end part 43.Here, the first cover portion 61 may be formed in an area including at least the first coil end portion CE1 and the coil side portion CS. Furthermore, the second cover portion 62 is formed to cover the welding portion of the end part 43 at the second coil end portion CE2.

[0028] The first cover portion 61 is formed, for example, to fix the stator windings 30 to the stator core 20 to increase mechanical strength and provide water and corrosion resistance to the stator windings 30. A first resin material (a first electrical insulating resin) used for the first cover portion 61 is a resin material generally referred to as varnish. Any synthetic resin, such as an epoxy resin-based synthetic resin, a phenolic resin-based synthetic resin, a polyester resin-based synthetic resin, or a silicone resin-based synthetic resin, can be used as the first resin material.

[0029] The second cover portion 62 is formed to protect the weld portion of the end portion 43 of the conductor segment 40 and to provide insulation for the exposed portion of the conductor end portion 43. A second resin material (a second electrically insulating resin) used for the second cover portion 62 may be, for example, a powder resin. Specifically, the powder resin may contain an epoxy- or polyester-based resin component as the main component of the powder resin.

[0030] The first cover portion 61 and the second cover portion 62 are formed as two insulating cover layers, each composed of respective resin materials having different glass transition temperatures. In the present embodiment, the first resin material used for the first cover portion 61 is the resin material having a relatively higher glass transition temperature, and the second resin material used for the second cover portion 62 is the resin material having a relatively lower glass transition temperature. In other words, the glass transition temperature Tg1 of the first resin material and the glass transition temperature Tg2 of the second resin material have a relationship of Tg1 > Tg2. For example, the glass transition temperature Tg1 of the varnish serving as the first resin material is 170°C, and the glass transition temperature Tg2 of the powder resin serving as the second resin material is 130°C.The first cover portion 61 serves as a first insulating layer and the second cover portion 62 serves as a second insulating layer.

[0031] A manufacturing method of the stator 13 is described below. Fig. 5 is a flowchart showing the processes for forming the respective cover portions 61, 62 of the stator windings 30 according to a manufacturing method of the stator 13 in the present embodiment. Fig. 6 is a timing chart showing the temperature transition of the stator windings 30 at the time of forming the respective cover portions 61, 62. Here, a process after the completion of the assembly of the conductor segments 40 to the stator core 20 and after the completion of the welding of the end portions 43 of the conductor segments 40 to the stator 13 is described.

[0032] In Fig. 5, the first cover portion 61 is first formed by the first resin material on the stator windings 30, and then the second cover portion 62 is formed by the second resin material on the stator windings 30. In Fig. 5, the process steps S1-S3 serve to form the first cover portion 61 on the respective stator windings 30, and the process steps S4-S5 serve to form the second cover portion 62 on the respective stator winding 30. Here, the process steps S1-S3 together serve as the first process (also collectively referred to as the forming process or pre-process) and the process steps S4-S5 together serve as the second process (also collectively referred to as the forming process or post-process).

[0033] During the formation (S1-S3) of the first cover section 61, the stator 13 is mounted on a Fig. 7 is installed, and the first cover portion 61 is formed in this state by the first resin material supplied from a dispenser 72. The first resin material is, for example, the paint. Fig. 7, the stator 13 is installed in the jig 71 such that the first end portion CE1 of the coil faces the top, the second end portion CE2 of the coil faces the bottom, and the central axis of the stator 13 is inclined relative to the direction of gravity.

[0034] In the first process step S1, the stator windings 30 are heated to a predetermined temperature higher than the glass transition temperature Tg1 of the first resin material (heating process). At this time, the stator windings 30 are energized under a predetermined energization condition, thereby heating the stator windings 30 to the predetermined temperature. The magnitude of the electric current for energization and the duration of the energization can be predetermined as the energization condition. It is also possible to detect the temperature of the stator windings 30 using a temperature sensor or the like, and the heating of the stator windings 30 by energizing the stator windings 30 can be maintained until the detected temperature of the stator windings 30 reaches the predetermined target temperature.

[0035] In the second process step S2, the first resin material in a liquid state is applied from the dispenser 72 to the first end portion CE1 of the respective stator winding 30 (first coating process). At this time, the first resin material is dripped from the dispenser 72 in a predetermined amount per unit time while the stator 13 is rotated together with the chuck 71, wherein the chuck 71 is rotated about a rotation axis of a rotatable shaft 73 of the chuck 71. Therefore, the first resin material is applied circumferentially to the first end portion CE1 of the respective stator winding 30.When the first resin material is applied to the first coil end portion CE1 of the respective stator windings 30, the first resin material flows along the conductor segments 40 into the slots 21 (the coil-side portion CS) and then flows to the second coil end portion CE2 side, which is on the opposite side to the first coil end portion CE1. In other words, a thin layer of the first resin material is formed on the respective stator windings 30 in an axial region from the first coil end portion CE1 to the second coil end portion CE2 in the axial direction. The first resin material can be applied to the region extending at least from the first coil end portion CE1 to the coil-side portion CS.At this time, the stator 13 may be oriented horizontally with the second coil end portion CE2 facing the bottom, and in this state, the first resin material may flow from the first coil end portion CE1 side to the second coil end portion CE2 side.

[0036] Then, in the third process step S3, the first resin material is cured under the condition that the temperature of the stator windings 30 is maintained within a predetermined curing temperature range (first curing process). In other words, the first resin material is cured to form the first cover portion 61 in the state where the surface of the respective stator windings 30 is covered with the first resin material. More specifically, after coating, the first resin material is cured as the temperature of the stator windings 30 gradually decreases to form the first cover portion 61.

[0037] In the time diagram of Fig. During the time period T1 shown in Figure 6, the stator windings 30 are heated to a predetermined heating temperature Th, which is higher than the glass transition temperature Tg1 of the first resin material. Next, during a period T2, the first end portion CE1 of each coil 30 is coated with the first electrically insulating resin, and then, during a period T3, the first resin material is cured in a high-temperature environment, maintaining the temperature at the predetermined curing temperature range (predetermined curing temperatures or a predetermined curing temperature) higher than the glass transition temperature Tg1 of the first resin material. Thus, the first cover portion 61 is formed.

[0038] In Fig. 5, after the formation of the first cover portion 61, the process of forming the second cover portion 62 with the second resin material continues. During the formation (S4-S5) of the second cover portion 62, the second cover portion 62 is formed using the second resin material having a glass transition temperature lower than the glass transition temperature of the first resin material, and the second resin material is cured using the residual heat of the stator windings 30 remaining after the formation of the first cover portion 61. In other words, in this embodiment, the stator windings 30 are not reheated during the formation of the second cover portion 62.

[0039] In process step S4, the axial distal end portion (welding portion) of the second coil end portion CE2 of the respective stator windings 30 is coated with the second resin material (second coating process). The second resin material is, for example, the powder resin. As shown in Fig. As shown in Figure 8, the second resin material in a liquid state is filled into a dipping tank 74, and the weld portion of the second end portion of the coil CE2 of the respective stator windings 30 is immersed in the dipping tank 74 to adhere the second resin material to a surface of the weld portion. In process step S4, after forming the first cover portion 61 with the first resin material having the relatively high glass transition temperature, the stator windings 30 are coated with the second resin material before the winding temperature (i.e., the temperature of the stator windings 30) decreases below the glass transition temperature of the second resin material having the relatively low glass transition temperature.

[0040] Then, in process step S5, the second end portion CE2 of the respective stator windings 30 is pulled upward from the dipping tank 74, and the second resin material is cured in a predetermined temperature range (predetermined curing temperatures or a predetermined curing temperature) higher than the glass transition temperature Tg2 of the second resin material (second curing process). Therefore, the second cover portion 62 is formed by the second resin material at the welding portion of the second coil end portion CE2 of the respective stator windings 30.

[0041] In the time diagram of Fig. 6, during the period T4, the welded portion of the second end portion CE2 of the respective coil windings 30 is coated with the second resin material in the state where the coil windings 30 are at the predetermined temperature(s) higher than the glass transition temperature Tg2 of the second resin material due to the residual heat of the stator windings 30 remaining after the formation (S1-S3) of the first cover portion 61. Then, during the period T5, the second cover portion 62 is formed by curing the second resin material. The second resin material can be applied either during the curing of the first resin material or after the curing of the first resin material.

[0042] Here, an imaginary case is assumed in which the second cover portion 62 is first formed with the second resin material having the low Tg (i.e., the low glass transition temperature), and thereafter the first cover portion 61 is formed with the first resin material having the high Tg (i.e., the high glass transition temperature). In such a case, the second cover portion 62 (the second resin material) is excessively reheated at the time of forming the first cover portion 61. Therefore, the stress after cooling in the second cover portion 62 is increased, and there is a risk of damage such as cracks. In contrast, in the present embodiment, the first cover portion 61 is first formed with the first resin material having the high Tg, and thereafter the second cover portion 62 is formed with the second resin material having the low Tg.Therefore, the second cover portion 62 (the second resin material) is not excessively heated, and the stress after cooling of the second cover portion 62 (the second resin material) is reduced.

[0043] During the formation (S1-S3) of the first cover portion 61, the heating temperature Th at the time of heating the stator windings 30 may be determined based on the glass transition temperature Tg1 of the first resin material (the varnish), the temperature (the amount of temperature reduction per unit time) of the stator windings 30 in the environment after heating the stator windings 30; and the curing time required to cure the first resin material at the curing temperature(s) higher than the glass transition temperature Tg1. The decrease in temperature (the temperature decreasing environment) of the stator windings 30 after heating the stator windings 30 may be determined based on the heating temperature Th at the time of heating the stator windings 30 and the curing time of the first resin material.

[0044] Furthermore, during the formation (S4-S5) of the second cover portion 62, the timing of coating the second resin material can be determined based on the glass transition temperature Tg2 of the second resin material (the powder resin), the temperature decrease of the stator windings 30, and the curing time required to cure the second resin material at the curing temperature(s) higher than the glass transition temperature Tg2. In this way, the processing condition at the time of forming each of the cover portions 61, 62 can be adjusted accordingly.

[0045] When forming (S1-S3) the first cover portion 61, a heat-retaining member may be used to limit a decrease in the temperature of the stator windings 30. In particular, as shown in Fig. 9, the stator 13 is covered with a heat-retaining cover 75 as a heat-retaining element. In this, as shown in Fig. 10, the decrease in the temperature of the stator windings 30 after heating the stator windings 30 in process step S1 is limited. In Fig. In FIG. 10, a dashed line shows a change in the temperature of the stator windings 30 when the heat-retaining cover 75 is not used. When the heat-retaining cover 75 is not used, the stator windings 30 are heated to the heating temperature Th. In contrast, when the heat-retaining cover 75 is used, the stator windings 30 are heated to a heating temperature Tha.

[0046] In Fig. 10, after heating the stator windings 30 to the heating temperature Tha during the time period T1, the temperature of the stator windings 30 is reduced comparatively slowly. Therefore, it is possible to reduce the heating temperature of the stator windings 30. In Fig. 10, the heating temperature is set to the heating temperature Tha, which is lower than the heating temperature Th, in anticipation of the slower decrease in the temperature of the stator windings 30. However, in the case where the heating temperature is set to the heating temperature Th, the temperature of the stator windings 30 is maintained at the higher temperature. Therefore, in such a case, the time required for curing the first resin material can be shortened.

[0047] However, the heat-retaining member may be something other than the heat-retaining cover 75; for example, a heat-retaining box that houses the stator 13 in a closed environment may be used as the heat-retaining member.

[0048] As in Fig. Furthermore, as shown in Figure 11, the heating of the stator windings 30 can be maintained during the period T2 (first coating process) in which the stator windings 30 are coated with the first resin material. In other words, the heating period of the stator windings 30 and the coating period with the first resin material can partially overlap. In this way, the decrease in the temperature of the stator windings 30 at the time of coating the stator windings 30 with the first resin material is limited, which in turn shortens the curing time of the first resin material.

[0049] The embodiment described above can achieve the following advantages.

[0050] At the time of manufacturing the stator 13, in the pre-process (S1 to S3), the stator windings 30 are coated with the first resin material having the high glass transition temperature and then cured at temperatures (or the temperature) higher than the glass transition temperature Tg1 of the first resin material. This forms the first cover portion 61. Furthermore, in the post-process (S4 to S5), the stator windings 30 are coated with the second resin material having the low glass transition temperature and then cured at temperatures (or the temperature) higher than the glass transition temperature Tg2 of the second resin material. This forms the second cover portion 62.In this case, at the time of curing the second resin material, it is not necessary to set the temperature to a very high temperature that is much higher than the temperature(s) at the time of curing the first resin material in the preliminary process, and thereby it is possible to limit the occurrence of disadvantages such as damage to the first cover portion 61. Therefore, in the case where the insulating layers (cover portions 61, 62) are formed on the respective stator windings 30 by using the different resin materials each having different glass transition temperatures, the insulating layers can be formed properly.

[0051] The temperature of the stator windings 30 gradually decreases after heating the stator windings 30 and coating the respective stator windings 30 with the first resin material. However, in the case where the glass transition temperature Tg1 of the first resin material is higher than the glass transition temperature Tg2 of the second resin material, it is conceivable that the temperature of the stator windings 30 during or after curing the first resin material is higher than the curing temperature(s) required to cure the second resin material. Therefore, the second cover portion 62 can be formed with the second resin material without requiring reheating of the stator windings 30 at the time of coating the stator windings 30 with the second resin material.In view of this, the stator windings 30 are coated with the second resin material in a state where the temperature of the stator windings 30 is maintained at a temperature higher than the glass transition temperature Tg2 of the second resin material, thus enabling the curing of the second resin material at the time of decreasing the temperature of the stator windings 30 after coating the stator windings 30 with the first resin material (see . Fig. 6). In this case, reheating of the stator windings 30 in the post-process is not necessary. This shortens the time required to form the insulating layers and reduces costs.

[0052] At the time of heating and curing the first resin material, which has a relatively high glass transition temperature, in the preliminary process (S1 to S3), the heat of the stator windings 30 is retained by using the heat-retaining cover 75 (see Fig. 9 and Fig. 10). In this case, the decrease in the temperature of the stator windings 30 after the heating of the stator windings 30 is slowed down. Therefore, it is possible to reduce the heating temperature of the stator windings 30 in the first process and shorten the time required for curing the first resin material.

[0053] Furthermore, in the case where the coating and curing of the second resin material is performed without reheating the stator windings 30 in the post-process (S4 to S5), the use of the heat-retaining cover 75 can limit the occurrence of the disadvantage that the temperature of the stator windings 30 inadvertently decreases below the desired temperature and thereby the second resin material does not cure properly.

[0054] In the pre-process (S1 to S3), the stator windings 30 are coated with the first resin material 30 during their heating (see Fig. 11). In this way, the decrease in temperature of the stator windings 30 at the time of coating the first resin material onto the stator windings 30 is limited, which in turn shortens the curing time of the first resin material. By shortening the curing time of the first resin material, the occurrence of the disadvantage of the first resin material flowing into an unintended area can be limited, thereby limiting the influence on the coating of the second resin material in the post-process. (Other embodiments)

[0055] The above embodiment can be modified, for example, as follows.

[0056] As in Fig. As shown in Figure 12, the temperature decrease of the stator windings 30 can be limited by using the heat-retaining cover 75 in the pre-process (S1 to S3), and the temperature decrease of the stator windings 30 can be unrestricted by omitting the heat-retaining cover 75 in the post-process (S4 to S5). In this case, the temperature decrease rate of the stator windings 30 in the pre-process is different from the temperature decrease rate of the stator windings 30 in the post-process. The temperature decrease rate of the stator windings 30 in the post-process is steeper than the temperature decrease rate of the stator windings 30 in the pre-process. Therefore, the heat radiation of the stator windings 30 in the pre-process can be limited in anticipation of the heat required for curing the second resin material in the post-process, and the temperature of the stator windings 30 can be quickly lowered to room temperature after the second resin material is cured in the post-process.In this way, the time required to form the cover sections can be reduced.

[0057] As in Fig. 13, heating of the stator windings 30 may be performed in each of the processes for forming the first cover portion 61 and the second cover portion 62.

[0058] In Fig. 13, the stator windings 30 are heated for a period of time T11 to a predetermined heating temperature Th1 higher than the glass transition temperature Tg1 of the first resin material (the varnish). Next, the stator windings 30 are coated with the first resin material for a period of time T12, and the first resin material is cured at an ambient temperature at which the temperature of the stator windings 30 is higher than the glass transition temperature Tg1 of the first resin material, for a period of time T13. Thus, the first cover portion 61 is formed.

[0059] Then, the stator windings 30 are reheated for a period of time T14 to a predetermined heating temperature Th2 higher than the glass transition temperature Tg2 of the second resin material (the powder resin). Next, the stator windings 30 are coated with the second resin material for a period of time T15, and the second resin material is cured at an ambient temperature where the temperature of the stator windings 30 is higher than the glass transition temperature Tg2 of the second resin material for a period of time T16. Thus, the second cover portion 62 is formed.

[0060] When forming (periods T4 to T6) the second cover portion 62, the heating temperature Th2 at the time of heating the stator windings 30 may be determined based on the glass transition temperature Tg2 of the second resin material, a decreasing rate of temperature (the amount of temperature reduction per unit time) of the stator windings 30 in the environment after heating the stator windings 30; and the curing time required to heat the second resin material at the curing temperature(s) higher than the glass transition temperature Tg2.

[0061] In the embodiment described above, the stator windings 30 are heated by applying current to the stator windings 30. However, this can also be done differently. For example, the stator windings 30 can be heated in a device (hot air oven), or the stator windings 30 can be heated by electromagnetic heating.

[0062] In the above-described embodiment, the paint with the relatively high glass transition temperature and the powder resin with the relatively low glass transition temperature are used, and the paint is used as the first resin material (the first electrically insulating resin) and the powder resin as the second resin material (the second electrically insulating resin). However, this can be changed. In the case of using another powder paint resin with a relatively high glass transition temperature and another paint with a relatively low glass transition temperature, the powder paint resin can be used as the first resin material (the first electrically insulating resin) and the paint as the second resin material (the second electrically insulating resin). In this case, the first insulating layer (corresponding to, for example, the second cover portion 62 in Fig. 4) with the powder resin, which is the first electrical insulating resin, formed in the pre-process, and the second insulating layer (corresponding, for example, to the first cover portion 61 in Fig. 4) can be formed with the varnish, which is the second electrical insulating resin, in the post-process.

[0063] The combination of the two electrical insulating resins is not limited to varnish and powder resin. For example, two types of varnishes with different glass transition temperatures can be used as the two electrical insulating resins, or two types of powder resins with different glass transition temperatures can be used as the two electrical insulating resins.

[0064] The insulating layers can be formed on the stator 13 using three types of electrical insulating resins. In this case, at least two types of electrical insulating resins among the three types of electrical insulating resins can have different glass transition temperatures. Even in this case, as in the case described above, after forming one insulating layer with the electrical insulating resin having the higher glass transition temperature, the other insulating layer can be formed with the electrical insulating resin having the lower glass transition temperature.

[0065] In the embodiment described above, the stator windings 30 having the segment structure are used on the stator 13. However, the present disclosure is not limited thereto. For example, stator windings having a construction other than the segment structure may be used on the stator 13.

[0066] In addition, the temperature of the stator windings 30 can be Fig. 5, the stator windings 30 can be kept at a constant temperature higher than the glass transition temperature of the first resin material by maintaining the current supply to the stator windings 30 in the process step S3 to cure the first resin material at the constant temperature higher than the glass transition temperature of the first resin material. Likewise, the temperature of the stator windings 30 can be kept at a constant temperature higher than the glass transition temperature of the first resin material in the process step S3 shown in Fig. 5, the second resin material may be kept at a constant temperature higher than the glass transition temperature of the second resin material to cure the second resin material at the constant temperature higher than the glass transition temperature of the second resin material. QUOTES CONTAINED IN THE DESCRIPTION

[0000] This list of documents submitted by the applicant was generated automatically and is included solely for the convenience of the reader. This list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions. Cited patent literature

[0000] JP 5 728 981 B2

[0003]

Claims

[1] A method of manufacturing a stator (13) including a plurality of conductor wires (40) wound to form a plurality of windings (30), the method comprising: a first process that includes the following steps: Coating the plurality of windings (30) with a first electrical insulating resin; subsequently curing the first electrical insulating resin at a temperature or temperatures higher than the glass transition temperature of the first electrical insulating resin; and thereby forming a first insulating layer (61) of the first electrical insulating resin on each of the plurality of windings (30); and a second process that includes the following steps: Coating the plurality of windings (30) with a second electrical insulating resin after the first process; subsequently curing the second electrical insulating resin at a temperature or temperatures higher than the glass transition temperature of the second electrical insulating resin; and thereby forming a second insulating layer (62) of the second electrical insulating resin on each of the plurality of windings (30), wherein the glass transition temperature of the first electrical insulating resin is higher than the glass transition temperature of the second electrical insulating resin. [2] A method according to claim 1, wherein: the first process includes heating the plurality of windings (30); and after performing the heating of the plurality of windings (30) and coating the plurality of windings (30) with the first electrical insulating resin in the first process, coating the plurality of windings (30) with the second electrical insulating resin (30) is performed in the second process in a state where a temperature of the plurality of windings (30) is kept higher than the glass transition temperature of the second electrical insulating resin and enables the second electrical insulating resin to cure. [3] The method according to claim 1 or 2, wherein the plurality of windings (30) are brought into a state in which a decrease in temperature of the plurality of windings (30) after coating the first electrical insulating resin on the plurality of windings (30) in the first process is limited by a heat-retaining member (75). [4] The method according to any one of claims 1 to 3, wherein in the first process, the coating of the plurality of windings (30) with the first electrical insulating resin is performed while heating the plurality of windings (30).

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