Method for manufacturing stator for rotating electrical machine, and stator for rotating electrical machine

Abstract

The invention relates to a method for manufacturing a stator for a rotary electric machine and the stator for the rotary electric machine. And the electrical insulating property of the end part of the coil is effectively improved. A stator for a rotating electrical machine is provided with: a stator core; a stator coil attached to the stator core and having coil ends at both axial ends; and an insulating material part which is provided at the coil end part and is formed of a foam varnish, and which has, on the surface thereof, a concave-convex part caused by foaming.

Description

Technical Field

[0001] This disclosure relates to a method for manufacturing a stator for a rotating electric machine and a stator for a rotating electric machine. Background Technology

[0002] It is known that there is a technique in which a resin composition containing a microcapsule-type foaming agent is pre-coated onto a slot liner in order to fix the stator coil of a rotating motor. After the slot liner and coil wire are inserted into the slot of the stator core, the foaming agent is foamed.

[0003] Patent Document 1: Japanese Patent Application Publication No. 2020-033433

[0004] However, the aforementioned existing technology aims to fix the coil wire in the slot, which does not easily improve the electrical insulation of the coil ends. Summary of the Invention

[0005] Therefore, in one respect, the object of this disclosure is to effectively improve the electrical insulation of the coil ends.

[0006] In one aspect, a stator for a rotating electric motor is provided, comprising: a stator core; a stator coil assembled to the stator core and having coil ends at both axial ends; and an insulating material portion disposed at the coil ends and formed of a foamed varnish, the insulating material portion having unevenness caused by foaming on its surface.

[0007] In one respect, according to this disclosure, the electrical insulation of the coil ends can be effectively improved. Attached Figure Description

[0008] Figure 1 This is a cross-sectional view that schematically illustrates the cross-sectional structure of a motor according to one embodiment.

[0009] Figure 2 This is a top view of the stator core in its individual state.

[0010] Figure 3 It is a schematic diagram showing a pair of coil plates assembled on a stator core.

[0011] Figure 4 This is a rough front view of a coil sheet.

[0012] Figure 5 It is along Figure 4 A sectional view of line AA.

[0013] Figure 6 This is a schematic cross-sectional view showing the insulating material portion disposed at the end of the coil in this embodiment.

[0014] Figure 7It is a cross-sectional view showing the portion of the insulating material located between two adjacent transition sections.

[0015] Figure 8 This is an explanatory diagram (1) showing the parts suitable for forming the first part and the second part.

[0016] Figure 9 This is an explanatory diagram (Figure 2) showing the parts suitable for forming the first and second parts.

[0017] Figure 10 This is a graph showing the test results of the partial discharge initiation voltage.

[0018] Figure 11 This is a schematic flowchart of the main parts of the stator manufacturing method in this embodiment.

[0019] Explanation of reference numerals in the attached figures

[0020] 21...Stator (stator for rotating electrical machines); 22...Stator core; 24...Stator coil; 240A, 240B...Coil ends; 70...Insulation material section; 71...Part 1; 72...Part 2. Detailed Implementation

[0021] Hereinafter, each embodiment will be described in detail with reference to the accompanying drawings. However, the dimensions and proportions in the drawings are merely examples and are not limiting; furthermore, shapes and other details in the drawings are sometimes exaggerated for ease of explanation. Additionally, in the drawings, for ease of observation, sometimes only a portion of parts with the same attribute that exist in multiple locations are labeled with reference to the accompanying drawings.

[0022] Figure 1 This is a cross-sectional view that schematically shows the cross-sectional structure of a motor 1 according to one embodiment.

[0023] Figure 1 The figure shows the rotating shaft 12 of the motor 1. In the following description, axial direction refers to the direction in which the rotating shaft (center of rotation) 12 of the motor 1 extends, and radial direction refers to the radial direction centered on the rotating shaft 12. Therefore, radial outer side refers to the side away from the rotating shaft 12, and radial inner side refers to the side towards the rotating shaft 12. Furthermore, circumferential direction corresponds to the direction of rotation about the rotating shaft 12.

[0024] Motor 1 can be, for example, a vehicle drive motor used in hybrid vehicles or electric vehicles. However, motor 1 can also be a motor used for any other purpose.

[0025] Motor 1 is an internal rotor type, with stator 21 arranged radially outside rotor 30. The radially outside stator 21 is fixed to motor housing 10.

[0026] The rotor 30 is disposed radially inside the stator 21. The rotor 30 includes a rotor core 32 and a rotor shaft 34. The rotor core 32 is fixed radially outside the rotor shaft 34 and rotates integrally with the rotor shaft 34. The rotor shaft 34 is supported by the motor housing 10 via bearings 14a and 14b to enable rotation. In addition, the rotor shaft 34 divides the rotation axis 12 of the motor 1.

[0027] The rotor core 32 is formed, for example, from a stack of steel plates containing annular magnetic material. Permanent magnets 321 are inserted into the magnet holes 320 of the rotor core 32. The number and arrangement of the permanent magnets 321 are arbitrary. In a modified example, the rotor core 32 may also be formed from a compressed powder body formed by compressing and solidifying magnetic powder.

[0028] like Figure 1 As shown, the rotor shaft 34 has a hollow portion 34A. The hollow portion 34A extends along the entire axial length of the rotor shaft 34. Alternatively, the hollow portion 34A may function as an oil passage. For example, as... Figure 1 As indicated by arrow R1, oil is supplied to the hollow portion 34A from one axial end. The oil flows along the radially inner surface of the rotor shaft 34, thereby cooling the rotor core 32 from the radially inner side. Alternatively, the oil along the radially inner surface of the rotor shaft 34 can be ejected radially outward through oil holes 341 and 342 formed at both ends of the rotor shaft 34 (arrows R5 and R6) to cool the coil ends 240A and 240B.

[0029] in addition, Figure 1 The diagram shows a motor 1 with a specific construction, but the construction of motor 1 is arbitrary as long as it has stator coils 24 joined by welding (described later). Therefore, for example, the rotor shaft 34 may or may not have a hollow portion 34A, or it may have a hollow portion with an inner diameter significantly smaller than that of the hollow portion 34A. Furthermore, Figure 1 The present invention discloses a specific cooling method, but the cooling method of the motor 1 is arbitrary. For example, an oil inlet pipe inserted into the hollow part 34A may be provided, or oil may drip from the oil passage inside the motor housing 10 radially outward toward the coil ends 240A and 240B.

[0030] also, Figure 1 Although this is an inner rotor type motor 1 with the rotor 30 disposed inside the stator 21, it can also be applied to other types of motors. For example, it can also be applied to an outer rotor type motor with the rotor 30 concentrically disposed outside the stator 21, or a dual rotor type motor with the rotor 30 disposed on both the outside and inside of the stator 21. Furthermore, the method of supplying oil (cooling oil for motor 1) to the motor housing 10 is arbitrary, and it can be supplied using an electric oil pump, a mechanical oil pump, or gear splashing, etc.

[0031] Next, refer to Figure 2 The following diagrams will detail the structure related to stator 21.

[0032] Figure 2 This is a top view of the stator core 22 in its individual state. Figure 3 This is a schematic diagram showing a pair of coil plates 52 assembled on the stator core 22. Figure 4 This is a schematic front view of a coil piece 52. Figure 5 It is along Figure 4 The sectional view along line AA is a sectional view of the slot insertion part 56. Additionally, Figure 3 In the image, with the stator core 22 extended radially inward, the relationship between a pair of coil plates 52 and the slot 220 is shown. Furthermore, Figure 3 In the diagram, the stator core 22 is shown by dashed lines, and a portion of the slot 220 is omitted from the illustration.

[0033] Stator 21 includes stator core 22 and stator coil 24 (see reference). Figure 1 ).

[0034] The stator core 22 is, for example, composed of a stack of steel plates with annular magnetic material; however, in a modified example, the stator core 22 may also be formed from a pressed powder body formed by compressing and solidifying magnetic powder. Furthermore, the stator core 22 may be formed from a segmented core divided in the circumferential direction, or it may be undivided in the circumferential direction. Multiple slots 220 for winding the stator coil 24 are formed on the radially inner side of the stator core 22. Specifically, as... Figure 2 As shown, the stator core 22 includes an annular back yoke 22A and a plurality of teeth 22B extending radially inward from the back yoke 22A, with grooves 220 formed between the plurality of teeth 22B in the circumferential direction. The number of grooves 220 is arbitrary, but in this embodiment, 48 are provided as an example.

[0035] The stator coils 24 form the stator coils 24 for each of the U, V, and W phases. The base of each phase stator coil 24 is connected to the input terminal (not shown), and the end of each phase stator coil 24 is connected to the end of the stator coils 24 of other phases to form the neutral point of the motor 1. That is, the stator coils 24 are star-connected. However, the connection method of the stator coils 24 can be appropriately changed according to the required motor characteristics, for example, the stator coils 24 can be connected in a delta configuration instead of a star connection.

[0036] The stator coils 24 of each phase are constructed by joining multiple coil segments 52. The coil segments 52 are segmented coils that divide the stator coils 24 of each phase into easily assembled units (e.g., units inserted into two slots 220). Figure 5As shown, the coil sheet 52 is covered by an insulating film 62 with a rectangular cross-section linear conductor (flat wire) 60. In this embodiment, as an example, the linear conductor 60 is formed of copper. However, in variations, the linear conductor 60 may also be formed of other conductor materials such as iron or aluminum. Furthermore, the cross-sectional shape of the linear conductor 60 may also be a shape other than rectangular.

[0037] Before the coil sheet 52 is assembled into the stator core 22, it can be formed into a generally U-shape having a pair of straight portions 50 and a connecting portion 54 connecting the pair of straight portions 50. When assembling the coil sheet 52 into the stator core 22, the pair of straight portions 50 are respectively inserted into slots 220 (see reference). Figure 3 Therefore, as Figure 3 As shown, the connecting portion 54 extends circumferentially across a plurality of teeth 22B (and the associated plurality of slots 220) on the other axial end side of the stator core 22. The number of slots 220 crossed by the connecting portion 54 is arbitrary, but... Figure 3 There are 3 in the middle. Furthermore, after the straight section 50 is inserted into the slot 220, in... Figure 4 As shown by the double-dotted line, it bends circumferentially along its middle section. Thus, the straight section 50 becomes a slot insertion section 56 extending axially within the slot 220 and a transition section 58 extending circumferentially at one axial end of the stator core 22. In this case, the connecting section 54 forms one of the coil ends 240A and 240B, and the transition section 58 forms the other coil end 240A and 240B.

[0038] in addition, Figure 4 In this configuration, the pair of straight sections 50 bend in a direction that separates them from each other, but this is not a limitation. For example, the pair of straight sections 50 may also bend in a direction that brings them closer together. In addition, sometimes the stator coil 24 may also have a neutral point coil leaf or the like for connecting the ends of the stator coils 24 of each phase to form a neutral point.

[0039] In a slot 220, multiple [items] are arranged radially and inserted [into the slot]. Figure 4 The slot insertion portion 56 of the coil lamination 52 is shown. Therefore, on one axial end side of the stator core 22, a plurality of circumferentially extending transition portions 58 are arranged radially. Figure 3 As shown, the transition portion 58 of a coil piece 52 protruding from one slot 220 and extending circumferentially to the first side (e.g., clockwise) and the transition portion 58 of another coil piece 52 protruding from another slot 220 and extending circumferentially to the second side (e.g., counterclockwise) are at the engagement portion 40 (see reference). Figure 4 They connect with each other.

[0040] In addition, in this embodiment, as an example, a coil sheet 52 with two slot insertion portions 56 is used, but it can also be applied to other forms of coil sheets such as coil sheets with four or more slot insertion portions 56.

[0041] Next, refer to Figure 6 The following figures illustrate the feature structure of this embodiment.

[0042] Figure 6 This is a schematic cross-sectional view showing the insulating material portion 70 provided at the coil end 240A in this embodiment. Figure 6 In the diagram, only one side of the section that is rotationally symmetric about the axis of rotation 12 is shown. Figure 6 In this context, the Z direction is axial, and the Z1 side is axially outward. Furthermore, the Y direction is radial, and the Y1 side is radially outward. Additionally, the following description primarily focuses on the insulating material portion 70 provided at the coil end 240A, but the same insulating material portion may also be provided at the coil end 240B.

[0043] In this embodiment, an insulating material portion 70 is provided at the coil end 240A. The insulating material portion 70 is formed of a foamed varnish. The material of the foamed varnish is arbitrary, but for example, it may be a resin material containing a foaming body, in which case the foaming body is foamed in such a way that it forms unevenness caused by foaming on the surface of the resin material.

[0044] The insulating material portion 70 may also be configured to cover the entire coil end 240A. That is, the insulating material portion 70 may also be configured to prevent any coil sheet 52 forming the coil end 240A from being exposed.

[0045] Figure 7 This is a cross-sectional view showing the portion of the insulating material section 70 located between two adjacent transition sections 58. Furthermore, the two adjacent transition sections 58 are the transition sections 58 between the two coil pieces 52 forming the coil end 240A.

[0046] like Figure 7 As shown, the insulating material portion 70 of this embodiment has unevenness 77 on its surface caused by foaming. The unevenness 77 is formed substantially throughout the entire surface. (See reference...) Figure 1 As described above, in this embodiment, cooling oil for motor cooling is supplied to the coil end 240A. If oil is supplied to the insulating material portion 70 of the coil end 240A, the oil enters the uneven portion 77 of the insulating material portion 70 and is easily retained by the uneven portion 77. Furthermore, the oil can also easily penetrate the internal gaps (pores) of the insulating material portion 70.

[0047] In this embodiment, the insulating material portion 70 has a first portion 71 and a second portion 72 at the coil end 240A.

[0048] The first part 71 is formed in the gap between two adjacent transition parts 58. The first part 71 can be formed by introducing (impregnating) foaming varnish into the gap between two adjacent transition parts 58 and foaming the foam.

[0049] The second portion 72 is continuous from the first portion 71 and protrudes in a convex shape between two adjacent transition portions 58. The second portion 72 can be formed by introducing a sufficient amount of foaming varnish into the gap between the two adjacent transition portions 58 and foaming the foam. That is, if a sufficient amount of foaming varnish is introduced into the gap and the foam is foamed, the second portion 72 is formed by expanding to a volume greater than the volume of the gap.

[0050] The second part 72 is a raised section that emerges from the gap between two adjacent transition sections 58, thus facilitating direct supply of oil to its surface. For example, oil is supplied to the surface of the second part 72 substantially continuously when the motor 1 is operating. Therefore, the second part 72 is essentially able to retain oil substantially continuously when the motor 1 is operating.

[0051] Such a first part 71 and a second part 72 can be formed in the gap between each transition part 58 at the coil end 240A.

[0052] Figure 8 as well as Figure 9 This is an explanatory diagram showing the parts suitable for forming the first part 71 and the second part 72. Additionally, Figure 8 as well as Figure 9 For ease of observation, the illustration of the insulating material part 70 is omitted.

[0053] In the following description, a coil end 240 of a phase refers to the portion of the coil end 240A formed by the three-phase stator coils 24 in which the coil end of that phase is formed.

[0054] Figures 8-9 This is a diagram illustrating the positional relationship of the stator coils 24 of each phase at coil end 240A. Figure 8 A portion of coil end 240A is shown in a side view (viewed perpendicular to the axis). Figure 9 A portion of coil end 240A is shown in a top view (view viewed along the axis). Figure 8 as well as Figure 9 For ease of understanding, the coil ends 240 of each phase are labeled with different cross-sectional lines for each phase. The coil end 240 of phase U is labeled with reference numeral 240 (U), the coil end 240 of phase V is labeled with reference numeral 240 (V), and the coil end 240 of phase W is labeled with reference numeral 240 (W). Furthermore, Figure 9In the diagram, the L direction is defined as parallel to the radial direction, with the L1 side corresponding to the inner radial direction and the L2 side corresponding to the outer radial direction.

[0055] In this embodiment, the insulating material portion 70 is formed integrally within the coil end 240A, including the gap between two adjacent transition portions 58. Therefore, in Figure 8 Insulating material portions 70 are also formed in the gaps Δ1 to Δ3 between the shown locations Q1 to Q3. Furthermore, regarding the insulating material portions 70 formed at locations Q1 and Q2, along... Figure 8 The cross section of line BB shown can also be... Figure 7 The cross sections shown are identical. Parts Q1 and Q2 contain gaps Δ1 and Δ2 between surfaces of different phases that are axially opposed to each other (surfaces of two adjacent transition portions 58), and part Q3 contains gap Δ3 between surfaces of the same phase that are axially opposed to each other (surfaces of two adjacent transition portions 58).

[0056] Furthermore, similarly, in Figure 9 The gaps Δ4 and Δ5 at the locations Q4 and Q5 shown are also formed with insulating material portions 70. Location Q4 includes a gap Δ4 between radially opposed surfaces of opposite phases (the surfaces of two adjacent transition portions 58), and location Q5 includes a gap Δ5 between radially opposed surfaces of the same phase (the surfaces of two adjacent transition portions 58). Furthermore, regarding the insulating material portions 70 formed at locations Q4 and Q5, along... Figure 9 The cross section of line CC shown can also be... Figure 7 The cross-sections shown are the same.

[0057] Figure 10 This is a graph showing the test results for the Partial Discharge Inception Voltage (PDIV). Figure 10 The test results 101 are shown in the state before the foaming varnish is applied, 102 are shown in the state after the foaming varnish is applied and after foaming, and 103 are shown in this embodiment. Furthermore, the test result 103 in this embodiment corresponds to the test results in the state after the foaming varnish is applied and after foaming, and in the state where oil is applied to the foaming varnish. The vertical axis represents the partial discharge initiation voltage, and the text "UV" on the horizontal axis represents the partial discharge initiation voltage between the U phase and the V phase, and "VW" represents the partial discharge initiation voltage between the V phase and the W phase, and so on.

[0058] According to Figure 10As can be seen from comparing test result 103 with other test results 101 and 102, according to this embodiment, the partial discharge initiation voltage can be significantly increased. In particular, it is a novel insight that the partial discharge initiation voltage can be significantly increased when the oil is coated with foaming varnish (insulating material part 70) compared to the state without oil coating (test result 102). Moreover, in this embodiment, the insulating material part 70 has an uneven surface, which can be presumed to enhance this effect. In addition, the oil coated with foaming varnish (insulating material part 70) can also be of the same composition as the cooling oil used in the motor 1.

[0059] Thus, according to this embodiment, the electrical insulation between different phases can be effectively improved in the coil end 240A (i.e., the partial discharge initiation voltage can be effectively improved).

[0060] Next, refer to Figure 11 The manufacturing method of the stator 21 in this embodiment will be summarized.

[0061] Figure 11 This is a schematic flowchart of the main parts of the manufacturing method of stator 21 in this embodiment.

[0062] This manufacturing method includes the following steps (step S1100): assembling stator coils 24 on stator core 22 to form an assembly (not shown) having coil ends 240A and 240B at both axial ends.

[0063] Next, the manufacturing method includes a step (step S1102) of impregnating the coil ends 240A and 240B with foamed varnish. This step can also be performed by dripping foamed varnish onto the coil ends 240A and 240B, or by impregnating the coil ends 240A and 240B in a tank containing foamed varnish.

[0064] Next, the manufacturing method includes a step of heating and curing the foamed varnish impregnated on the coil ends 240A and 240B (step S1104). In this step, the foamed varnish foams to form an insulating material portion 70. That is, an insulating material portion 70 with unevenness is formed on the surface (especially the surface of the second portion 72).

[0065] Next, this manufacturing method includes subsequent processes such as a cooling process (step S1106), a finishing process (step S1108), and a shape inspection process (step S1110), as well as an oil coating process (step S1112). The oil coating process includes applying oil to the coil ends 240A and 240B to retain the oil in the insulating material portion 70. Furthermore, the oil coating method is arbitrary and can include dripping, impregnation, etc.

[0066] Next, the manufacturing method includes an electrical inspection step (step S1114). The electrical inspection step may also include a step of checking whether the required electrical insulation is ensured at the coil ends 240A, 240B. For example, the electrical inspection step may also include a step of checking whether the measured value of the partial discharge initiation voltage exceeds a reference value.

[0067] If the required electrical insulation is confirmed in the electrical inspection process (step S1114), the stator 21 is completed and transferred to the factory process (or the assembly process of the gearbox, etc.).

[0068] According to this manufacturing method, it is possible to manufacture a stator 21 that effectively improves the electrical insulation of the coil ends 240A and 240B.

[0069] The embodiments have been described in detail above, but are not limited to specific embodiments. Various modifications and alterations can be made within the scope of the claims. Furthermore, all or more of the structural elements of the foregoing embodiments can be combined.

Claims

1. A stator for a rotary electric motor, characterized in that, have: Stator core; A stator coil, which is assembled into the stator core and has coil ends at both axial ends; and An insulating material portion, disposed at the end of the coil, is formed of foamed varnish. The insulating material portion has unevenness on its surface caused by foaming.

2. The stator for a rotary electric motor according to claim 1, characterized in that, The insulating material portion has the following characteristics at the coil end: The first part is formed in the gap between the coil lines involved in the stator coil; and The second part is continuous from the first part and bulges out between the coil lines.

3. The stator for a rotary electric motor according to claim 1 or 2, characterized in that, The insulating material portion retains the oil used for cooling the rotating motor in the recessed and convex portions.

4. A method for manufacturing a stator for a rotary electric machine, characterized in that, include: The assembly process involves assembling the stator coils onto the stator core to form an assembly with coil ends at both axial ends. In the forming process, after the assembly process, a foaming varnish is applied to the end of the coil, and the foaming varnish is foamed to form an insulating material portion at the end of the coil; as well as The process of applying oil to the insulating material portion after the forming process. The forming process includes: creating unevenness on the surface of the insulating material portion caused by foaming.

5. A rotary electric motor, characterized in that, have: The housing, which forms a containment space for the oil used to cool the rotating motor; and The rotor and stator are housed in the housing. The stator comprises: Stator core; Stator coils, which are assembled on the stator core and have coil ends at both axial ends; An insulating material portion, disposed at the end of the coil, is formed of foamed varnish. The insulating material portion has uneven portions on its surface that retain the oil, the uneven portions being caused by foaming.

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