Stator core manufacturing method

Abstract

To provide a stator core manufacturing method by which a stator core of a rotary electric machine having a cooling medium flow path can be manufactured with high efficiency.SOLUTION: A stator core manufacturing method includes: a first step S1 of, regarding a magnetic steel sheet, performing a push back-planning cut process on a core formation planned part 11a to be formed as a core part 11 in a slot corresponding area of a stator core; a second step S2 of forming the core part 11 by pushing back the core formation planned part 11a having undergone the cut process at the first step S1 to return to a position before the first step S1; a third step S3 of forming a layered body 10a by layering magnetic steel sheets 10 having the core parts 11 formed in the second step S2; a fourth step S4 of molding a part (stator inner circumference cover 9) that is to be integrated with a stator core 1 with respect to the layered body 10a formed in the third step S3; and a fifth step S5 of removing the core parts 11 from the layered body 10a after the fourth step S4.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a method for manufacturing a stator core. [Background technology]

[0002] A stator core of a rotating electric machine is constructed by laminating electromagnetic steel sheets processed into a shape corresponding to the stator core. A cooling method is sometimes adopted in which a coolant is circulated within the slots of such a stator core. In this method, an annular stator inner cover is provided along the inner circumferential surface of the stator core to seal the inner opening of each slot, preventing the coolant flowing axially through the slots while cooling the coil conductors from leaking into the gap with the rotor.

[0003] On the other hand, a method for manufacturing a stator core has been proposed in which the stator core of a rotating electric machine is divided into multiple blocks circumferentially at predetermined angles, these multiple blocks are fastened together in an annular shape via dummy crimping blocks, and then the dummy crimping blocks are removed (see Patent Document 1).

[0004] On the other hand, in recent years, as part of efforts to realize a low-carbon or carbon-free society, development of electrification technologies has become active in the field of vehicles. The electrification of vehicles requires rotating electric machines with high energy efficiency. To commercialize such rotating electric machines, a manufacturing method for stator cores that has a high yield and ultimately leads to power savings is required. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2016-111865 Summary of the Invention [Problem to be solved by the invention]

[0006] However, the method disclosed in Patent Document 1 cannot be directly applied as a method for molding a stator inner cover that seals the openings on the inner periphery of each slot to prevent the cooling medium of the stator core from leaking into the gap with the rotor.

[0007] The present invention has been made in consideration of the above-mentioned circumstances, and aims to provide a method for manufacturing a stator core that can manufacture a stator core for a rotating electric machine equipped with a cooling medium flow path with high efficiency, and ultimately contribute to improving energy efficiency. [Means for solving the problem]

[0008] (1) A first step (for example, a first step S1 described later) of applying a cutout intended for push-back to a core formation portion (for example, a core formation portion 11a described later) in a portion corresponding to the slot of an electromagnetic steel sheet (for example, an electromagnetic steel sheet 10 described later) which is a material of a stator core (for example, a stator core 1 described later) in which a plurality of slots (for example, a slot 3 described later) are formed, the core formation portion (for example, a core formation portion 11a described later) being formed later; and a second step (for example, a first step S1 described later) of applying a cutout intended for push-back to the core formation portion that has been subjected to the cutout in the first step, by pushing back the core formation portion to its position before the first step. a third step (e.g., third step S3 described later) of stacking the electromagnetic steel sheets on which the core portion has been formed in the second step to form a laminate (e.g., laminate 10a described later); a fourth step (e.g., fourth step S4 described later) of molding a part to be integrated with the stator core (e.g., stator inner cover 9 described later) onto the laminate formed in the third step; and a fifth step (e.g., fifth step S5 described later) of removing the core portion from the laminate following the fourth step.

[0009] (2) In the first step, the electromagnetic steel sheet is subjected to a notch process intended for push-back in the portion where the core is to be formed, while the outer contour portion of the stator core is punched out. This is a method for manufacturing a stator core according to (1).

[0010] (3) A method for manufacturing a stator core according to (1) or (2), wherein the core portion formed in the second step has a closed shape portion (e.g., the closed shape portion 11b described later) that covers the opening of the slot facing the inner circumference of the stator core.

[0011] (4) The method for manufacturing a stator core according to (3), wherein the core portion formed in the second step has a planar projection outer diameter smaller than the planar projection outer diameter of the slot.

[0012] (5) The method for manufacturing a stator core according to (4), wherein the core portion formed in the second step has a void (for example, void 11c described later) formed within its own planar projection outline.

[0013] (6) The part formed in the fourth step is a stator inner cover that covers the inner surface of the stator core and forms a cooling medium flow path (e.g., the in-slot cooling medium flow path 8 described later) of a rotating electric machine having the stator core. [Effects of the Invention]

[0014] In the manufacturing method of the stator core described above in (1), the portion intended to become the core portion, which is subjected to cutout processing for push-back in the first step, is pushed back to its position before the first step in the second step to form the core portion. As a result, the dimensions of the inner circumferential opening of the corresponding slot and the dimensions of the corresponding portion of the core portion match with high precision. Therefore, by molding using this core portion, the portion that closes the inner circumferential opening of the slot in the part that will be integrated with the stator core can be formed with sufficient precision.

[0015] In the manufacturing method of the stator core described above in (2), in the first step, the magnetic steel sheet is notched at the portion where the core is to be formed, with the push-back intended, and the outer contour of the stator core is punched out, which allows for highly efficient manufacturing of the stator core.

[0016] In the manufacturing method of the stator core described above in (3), the core formed in the second step has a closing shape portion that covers the opening of the slot facing the inner circumference of the stator core. Therefore, by using a mold that uses the closing shape portion of the core, whose dimensions match the dimensions of the slot opening with high precision, it is possible to form with sufficient precision the portion that closes the opening on the inner circumference side of the slot in the part that is integrated with the stator core.

[0017] In the manufacturing method of the stator core described above in (4), the core portion formed in the second step has a smaller planar projection outline than the planar projection outline of the slot, and therefore, after the molding in the fourth step is completed, the core portion can be easily removed.

[0018] In the manufacturing method of the stator core described above in (5), the core portion formed in the second step has a void formed within its own planar projection outline, so that the core portion can be easily removed after the molding in the fourth step is completed.

[0019] In the manufacturing method of the stator core described in (6) above, the part formed in the fourth step is a stator inner cover that covers the inner peripheral surface of the stator core and constitutes a coolant flow path for a rotating electric machine having this stator core. Therefore, the dimensional accuracy of the part of the stator inner cover that closes the openings on the inner peripheral side of the slots is high, and a rotating electric machine can be realized in which there is no risk of coolant leaking into the gap between the stator core and the corresponding rotor.

[0020] Taking the above points (1) to (6) into consideration, the method for manufacturing a stator core according to the present disclosure makes it possible to manufacture a stator core for a rotating electrical machine with high efficiency, which in turn contributes to improving energy efficiency. [Brief explanation of the drawings]

[0021] [Figure 1] 1 is an exploded schematic view of a rotating electric machine including a stator core manufactured by a method for manufacturing a stator core according to an example of the present disclosure; [Figure 2] 5A to 5C are process diagrams illustrating a method for manufacturing a stator core according to an example of the present disclosure. [Figure 3] FIG. 3 is a diagram illustrating each stage from the first step to the fourth step in FIG. 2. [Figure 4] FIG. 3 is a diagram showing a core formed in the second step in FIG. 2. [Figure 5] 3 is a diagram showing the relationship between the core formed in the second step in FIG. 2 and the stator inner circumferential cover molded in the fourth step. FIG. [Figure 6] 3 is a diagram illustrating each stage in the fifth step in FIG. 2. FIG. [Figure 7] FIG. 3 is a view showing the core removal operation in the fifth step in FIG. 2. [Figure 8] 3 is a diagram showing the slot and the stator inner circumferential cover in a state where the fifth step in FIG. 2 has been completed. [Figure 9] 3 is a diagram showing a state in which a stator coil is arranged in a slot after the fifth step in FIG. 2 is completed. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0022] The manufacturing method of the stator core according to the present disclosure will be described below with reference to the drawings. In the following drawings, corresponding parts are designated by the same reference numerals.

[0023] 1 is an exploded schematic diagram of a rotating electric machine 2 including a stator core 1 manufactured by a stator core manufacturing method according to one example of the present disclosure. The stator core 1 has an annular cross section perpendicular to the axis of the rotating electric machine 2, and is provided with a plurality of slots 3 arranged at equal intervals in the circumferential direction. A plurality of rectangular conductors 4 are disposed in each of the slots 3. The rectangular conductors 4 (square conductors) have rectangular cross sections, and their ends are electrically connected to form a stator coil 5.

[0024] Annular front cover member 6 and rear cover member 7 that cover the front and rear ends of stator coil 5 are attached to the axial front end (near side in FIG. 1) and rear end (far side in FIG. 1) of stator core 1. Front cover member 6 and rear cover member 7 house connecting conductor portions of the front and rear ends of stator coil 5 therein and also form part of the flow path for coolant CL.

[0025] In other words, the cooling medium introduced into the front cover member 6 from the discharge side of a cooling medium pump (not shown) circulates in a circular pattern within the front cover member 62 and reaches the rear cover member 7 through the in-slot cooling medium flow paths 8 formed between the flat square conductors 4 within the slot 3 or between the flat square conductors 4 and the inner wall of the slot 3, thereby forming a cooling medium circulation system in which the cooling medium circulates through a cooling medium circulation path (not shown).

[0026] In the in-slot coolant flow passages 8, an annular stator inner cover 9 is provided along the inner peripheral surface of the stator core 1 to prevent the coolant flowing axially through the slots 3 while cooling the rectangular conductors 4 from leaking into the gap with the rotor (not shown). As will be described later, the stator inner cover 9 is molded along the inner peripheral surface of the stator core 1. In FIG. 1, the stator inner cover 9 is shown schematically in a position pulled out axially forward from the stator core 1 for the convenience of illustrating its external shape.

[0027] Fig. 2 is a process diagram showing a manufacturing method of a stator core 1 according to one example of the present disclosure. Fig. 3 is a diagram illustrating each step from a first step S1 to a fourth step S4 in Fig. 2. Fig. 4 is a diagram illustrating a core formed in a second step S2 in Fig. 2. Each step from the first step S1 to the fourth step S4 will be described with reference to Figs. 2, 3, and 4. In the first step S1, an electromagnetic steel sheet 10, which is the material of the stator core 1, is punched out along the contours of the outer and inner peripheries of the planar projection shape of the stator core 1, and a cutout is made in a core formation portion 11a, which will later become the core portion 11, with the push-back intended.

[0028] That is, as shown in part (a) of Figure 3, a core formation portion 11a, which will later become the core portion 11, in a slot-corresponding portion 3a of an electromagnetic steel sheet 10, which is the material of the stator core 1 in which a plurality of slots 3 are formed, is cut with a push-back intended for the core formation portion 11a. This type of cut is a special form of so-called stamping, but is itself a known processing method for metal plates. The portion of the slot 3 other than the core formation portion 11a is punched out to the shape of the slot 3.

[0029] In the second step S2 following the first step S1, the core portion 11 is formed by push-back, whereby the main surface of the core portion 11 becomes flush with the electromagnetic steel sheet 10 before processing.

[0030] 4, the core portion 11 is formed so that its outer contour is spaced inward from the inner contour of the slot 3 of the stator core 1. However, in the slot 3, an opening 3b that opens toward the gap between the inner periphery of the stator core 1 and the outer periphery of the rotor (not shown) and a closed shape portion 11b where the core portion 11 closes this opening 3b are connected without any gaps by a cutting process that involves push-back.

[0031] In the present example, the core portion 11 has a void 11c formed in a portion located radially outward of the closed portion 11b of the stator core 1. The void 11c is formed by punching out the electromagnetic steel sheet 10. Portions adjacent to both sides of the slot 3 formed in the electromagnetic steel sheet 10 in the circumferential direction constitute the teeth 17 of the rotating electric machine 2. In addition, the stator core 1 in the present example has a portion of its inner peripheral surface corresponding to the opening 3b of the slot 3 that forms a recessed portion 17c that is recessed in the radial direction.

[0032] Next, in a third step S3, as shown in part (b) of FIG. 3, the electromagnetic steel sheets 10 on which the core portions 11 have been formed in the second step S2 are stacked to form a laminate 10a that will become the stator core 1.

[0033] Furthermore, in a fourth step S4, as shown in part (c) of FIG. 3, a stator inner circumferential cover 9, which is a component to be integrated with the stator core 1, is molded onto the laminate 10a formed in the third step S3.

[0034] Molding is performed as follows: An inner diameter die 12, which is slightly larger in diameter than the rotor (not shown) of the rotating electrical machine 2 and longer in the axial direction than the rotor, is placed inside the laminate 10a coaxially with the laminate 10a (coaxial with the stator core 1). A front split die 13 and a rear split die 14 are placed at both ends of the inner diameter die 12 so as to face each other in the axial direction. In this arrangement, the ends of the inner diameter die 12 are fitted into the opposing recesses of the front split die 13 and the rear split die 14 to sandwich them together, and a load is applied so as to compress the laminate 10a in the axial direction (the vertical direction in part (c) of Figure 3).

[0035] As shown in part (c) of Figure 3, a cavity 15 corresponding to the stator inner circumferential cover 9 is formed between the outer periphery of the inner diameter die 12 and the inner periphery of the laminate 10a. The front end side (the lower end side in part (c) of Figure 3) of the cavity 15 is formed in the front split die 13. The rear end side (the upper end side in part (c) of Figure 3) of the cavity 15 is formed in the rear split die 14. Furthermore, a runner 16 that communicates with the cavity 15 is formed in the rear split die 14. Molten resin 9a is injected from this runner 16 into the cavity 15 to mold the stator inner circumferential cover 9.

[0036] FIG. 5 is a diagram showing the relationship between the core portion 11 formed in the second step in FIG. 2 and the stator inner cover 9 molded in the fourth step S4. As described above, when an axial compressive load is applied to the laminate 10a sandwiched between the front split mold 13 and the rear split mold 14, a load of sufficient magnitude is applied so that the core portion 11 does not move radially outward due to the injection pressure of the molten resin 9a. As a result, even if the boundary between the closed portion 11b of the core portion 11 and the opening 3b of the slot 3 in FIG. 5 is gradually weakened by half-blanking, the core portion 11 (closed portion 11b) maintains its position against the injection pressure of the molten resin 9a. This prevents the molten resin 9a from penetrating into the slot 3, and a stator inner cover 9 having the correct shape is molded.

[0037] When molding of the stator inner cover 9 is completed in the fourth step S4 in Fig. 2, the core portion 11 is removed from the laminate 10a in the next fifth step S5. Next, the fifth step S5 will be described with reference to Figs. 6, 7, and 8. Fig. 6 is a diagram illustrating each stage in the fifth step S5. Fig. 7 is a diagram showing the removal operation of the core portion 11 in the fifth step S5. Fig. 8 is a diagram showing the slot 3 and the stator inner cover 9 after the fifth step S5 is completed.

[0038] In the fifth step S5, first, as shown in part (a) of FIG. 6, the inner diameter die 12, the front split die 13, and the rear split die 14 are removed. This results in a stator inner circumferential cover 9 formed along the inner circumferential surface of the laminate 10a that will become the stator core 1. At this stage, the core portion 11 remains in the slot 3 (FIG. 5). Next, when the core portion 11 is pulled so as to move radially outward within the slot 3, the gradually weakened portion at the boundary between the closed shape portion 11b of the core portion 11 and the opening 3b of the slot 3 is easily torn as shown in FIG. 7. The core portion 11 is then released from the opening 3b and the stator inner circumferential cover 9 and moves relatively outward as shown in part (b) of FIG. 6. When pulling the core portion 11 outward as described above, the working end of a tool may be inserted into the void 11c to hook and move it.

[0039] As shown in FIG. 7 and FIG. 6(b), the core portion 11 moves toward the outer periphery of the slot 3 and separates from the opening 3b and the stator inner cover 9. Then, as shown in FIG. 6(c), it is moved axially and removed. At this time, the core portion 11, which was compressed into a block shape in the fourth step S4 as shown in FIG. 5, moves and is removed as a single unit. Once the core portion 11 is removed, the stator core 1 reaches its completed shape as shown in FIG. 6(d). In this state, the slot 3 of the stator core 1, which is made of the laminated body 10a, becomes empty as shown in FIG. 8, and the opening 3b is sealed by the protruding portion 9p formed on the outer periphery of the stator inner cover 9. In this example, the protruding portion 9p of the stator inner cover 9 fits snugly into the recessed portions 17c of the teeth 17 on both sides of the opening 3b of the slot 3. This prevents unnecessary relative movement between the inner periphery of the stator core 1 and the stator inner cover 9.

[0040] 9 is a diagram showing the state in which stator coils 5 made of rectangular conductors 4 are placed in the slots 3 of the stator core 1 after the above-mentioned fifth step S5 is completed. In this state, a coolant flows axially through the in-slot coolant flow paths 8 formed between the rectangular conductors 4 in the slots 3, which are closed by the stator inner cover 9, and between the rectangular conductors 4 and the inner wall of the slots 3. This flowing coolant promotes cooling of the stator coils 5 and the stator core 1.

[0041] The method for manufacturing the stator core in the present disclosure described above can be summarized as follows.

[0042] (1) A manufacturing method of a stator core 1 according to one embodiment of the present disclosure includes a first step S1 in which a cut-out process is performed on a core-forming portion 11a, which will later become a core portion 11, in a slot-corresponding portion 3a of an electromagnetic steel sheet 10, which is the material of the stator core 1 in which a plurality of slots 3 are formed, with the cut-out process being scheduled for push-back; a second step S2 in which the core-forming portion 11a, which has been cut-out in the first step S1, is pushed back to its position before the first step S1 to form the core portion 11; a third step S3 in which the electromagnetic steel sheets 10 having the core portions 11 formed in the second step S2 are stacked to form a laminate 10a; a fourth step S4 in which a part (stator inner cover 9) to be integrated with the stator core 1 is molded onto the laminate 10a formed in the third step S3; and a fifth step S5 in which the core portion 11 is removed from the laminate 10a following the fourth step S5.

[0043] In the manufacturing method of the stator core 1 described above in (1), the core-forming portion 11a, which is the portion intended to become the core portion and which is half-punched in the first step S1, is returned in the second step S2 to its original position before being half-punched in the first step S1, to form the core portion 11. As a result, the dimensions of the corresponding openings 3b on the inner periphery of the slots 3 and the dimensions of the corresponding portion of the core portion 11 match with high precision. Therefore, by molding using this core portion 11, it is possible to form with sufficient precision the portion (closing portion 11b) that closes the openings 3b on the inner periphery of the slots 3 in the part (stator inner periphery cover 9) that is to be integrated with the stator core 1.

[0044] (2) In the manufacturing method of the stator core 1 according to one aspect of the present disclosure, in the first step S1, the core formation portion 11a is half-punched from the electromagnetic steel sheet 10, and the outer contour portion of the stator core 1 is punched. This allows for highly efficient manufacturing of the stator core.

[0045] (3) In one embodiment of the manufacturing method of the stator core 1 of the present disclosure, the core portion 11 formed in the second step S2 has a closed portion 11b that covers the openings 3b of the slots 3 facing the inner circumference of the stator core 1. Therefore, by molding using the closed portion 11b of the core portion 11, whose dimensions match the dimensions of the openings 3b of the slots 3 with high precision, it is possible to form with sufficient precision the portion of the component (stator inner cover 9) that closes the openings 3b on the inner circumference side of the slots 3.

[0046] (4) In the manufacturing method of the stator core 1 according to one embodiment of the present disclosure, the core portion 11 formed in the second step S2 has a smaller planar projection outline than the planar projection outline of the slot 3. This makes it easy to remove the core portion 11 after the molding in the fourth step S4 is completed.

[0047] (5) In the manufacturing method of the stator core 1 according to one embodiment of the present disclosure, the core portion 11 formed in the second step S2 has a void 11c formed within its own planar projection outline. Therefore, after the molding in the fourth step S4 is completed, removing the core portion 11 can be easily performed by inserting the working end of a tool into the void 11c.

[0048] (6) In one embodiment of the method for manufacturing the stator core 1 according to the present disclosure, the component (stator inner cover 9) formed in the fourth step S4 is the stator inner cover 9 that covers the inner surface of the stator core 1 and constitutes a coolant flow path for the rotating electric machine 2 that includes this stator core 1. Therefore, the dimensional accuracy of the portion of the stator inner cover 9 that closes the opening 3b on the inner periphery side of the slot 3 is high, and a rotating electric machine 2 can be realized that is free from the risk of coolant leaking into the gap between the stator core 1 and the corresponding rotor.

[0049] While one embodiment of the stator core manufacturing method of the present disclosure has been described above, the technical concept of the present disclosure is not limited thereto. Detailed configurations may be modified as appropriate within the scope of the technical concept of the present disclosure. For example, instead of using a core part having a void, a core part having no void and a concave or convex portion in its planar projection shape that is easy for the working end of a tool to engage may be used. [Explanation of symbols]

[0050] 1... Stator core 2...Rotating electric machine 3. Slot 3a...Slot compatible part 3b…Opening 4...Rectangular conductor 5...Stator coil 6...Front cover member 7...Rear cover member 8...Coolant flow path in slot 9... Stator inner cover 9a...Molten resin 9p…Protruding shape part 10...Electromagnetic steel plate 10a...Laminate 11…Middle part 11a... Core formation area 11b...Closed shape part 11c...blank space 12...Inner diameter type 13...Front split type 14...Rear side split type 15...cavity 16...Runner 17...Teeth 17c…Concave shape part

Claims

1. a first step of performing a cut-out process for push-back on a portion of an electromagnetic steel sheet, which is a material of a stator core in which a plurality of slots are formed, in a portion corresponding to the slot, the portion being a core portion to be formed later; a second step of pushing back the core-forming portion that has been cut in the first step to return it to its position before the first step, thereby forming the core portion; a third step of laminating the electromagnetic steel sheets on which the core portions have been formed in the second step to form a laminate; and a fourth step of molding a component to be integrated with the stator core onto the laminate formed in the third step; a fifth step of removing the core part from the laminate following the fourth step; A method for manufacturing a stator core, comprising:

2. 2. The method for manufacturing a stator core according to claim 1, wherein in the first step, a cut processing intended for push-back is performed on the electromagnetic steel sheet in the portion where the core is to be formed, while a punching processing is performed on the outer contour portion of the stator core.

3. 3. The method for manufacturing a stator core according to claim 1, wherein the core portion formed in the second step has a closed shape portion that covers an opening of the slot facing the inner periphery of the stator core.

4. 4. The method for manufacturing a stator core according to claim 3, wherein the core portion formed in the second step has a smaller planar projection outer diameter than the slot.

5. 5. The method for manufacturing a stator core according to claim 4, wherein the core portion formed in the second step has a void formed within its own outer shape projected on a plane.

6. 2. The method for manufacturing a stator core according to claim 1, wherein the part formed in the fourth step is a stator inner cover that covers the inner surface of the stator core and forms a cooling medium flow path for a rotating electric machine having the stator core.

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