JP2023004768A - Manufacturing method of stator for rotary electric machine - Google Patents

Abstract

To stabilize quality of a stator by fixing a stator core and a segment coil in a stable state.SOLUTION: After forming a stator core 6 by arranging a plurality of split cores 61 in an axial direction, a segment coil 71 is inserted into a slot 6c of the stator core 6. The plurality of split cores 61 are relatively rotated, and the split cores 61 are pressed to the segment coil 71 inserted into the slot 6c from a circumferential direction. A relative rotational amount of the plurality of split cores 61 at this time is managed by torque.SELECTED DRAWING: Figure 7

Description

The present invention relates to a method for manufacturing a stator for a rotating electric machine.

2. Description of the Related Art As a stator for a rotating electric machine, a stator using a large number of U-shaped segment coils is known. For example, the method of manufacturing a stator disclosed in Patent Document 1 below includes a step of inserting segment coils into slots provided in a stator core; A step of twisting the projecting portion in the circumferential direction, a step of welding the ends of the segment coil twisted in the circumferential direction, and a step of impregnating and hardening the gap between the segment coil and the stator core with varnish. and

Further, in a rotating electrical machine disclosed in Patent Document 2 below, a stator core (stator core) has three coaxially arranged split cores (split cores). After inserting the segment coils into the slots of the stator, the split core at the center in the axial direction is rotated relative to the split cores at both ends in the axial direction to bring the split cores into contact with the segment coils. It is said that this makes it possible to ensure good thermal conductivity between the stator core and the segment coils.

JP 2019-169993 A Japanese Patent No. 6843272

By the way, in the stator manufacturing method disclosed in Patent Document 1, after inserting the segment coils into the slots of the stator core, until the gap between the segment coils and the stator core is impregnated with varnish and hardened, the segment The coil is not fixed to the stator core. Therefore, it is necessary to hold the segment coil and stator core with a jig or the like in the process (for example, the process of twisting the segment coil in the circumferential direction) that is performed after the segment coil is inserted and before the varnish is impregnated and hardened. It is time consuming because

For example, as shown in Patent Document 2, the segment coil can be fixed to the stator core by forming the stator core from a plurality of split cores, rotating them relative to each other, and pressing them against the segment coil in the circumferential direction. . However, in the method described in the document, each split core is rotated by a predetermined amount in the circumferential direction by inserting a connecting member into a connecting portion (through hole or recess) provided in each split core. In this case, since the amount of rotation of the split cores is determined by the dimensions of the connected parts and the connecting member, the amount of rotation of each split core changes due to variations in the dimensions of the connected parts and the connecting member. For this reason, the force for pressing each split core against the segment coil differs from product to product, and the fixing force between the stator core and the segment coil becomes unstable, resulting in variations in the quality of the stator.

Accordingly, an object of the present invention is to stabilize the quality of the stator by fixing the stator core and the segment coils in a stable state.

In order to achieve the above objects, the present invention provides a step of arranging a plurality of split cores in an axial direction to form a stator core having a plurality of teeth and a plurality of slots formed between the teeth in the circumferential direction; and a step of relatively rotating a plurality of split cores to press the split cores against the segment coils inserted in the slots from the circumferential direction, the method comprising: It is characterized by managing the amount of relative rotation of the plurality of split cores by means of torque.

Thus, in the present invention, the amount of relative rotation of a plurality of split cores is managed by torque. That is, the plurality of split cores are relatively rotated and pressed against the segment coil, and when the torque at this time reaches a predetermined value, the relative rotation of the plurality of split cores is stopped. As a result, each split core can be pressed against the segment coil with a constant force regardless of the dimensional accuracy of each part.

In the above method, by crimping one axial end face of the tooth of the stator core, one axial end of the tooth can be protruded in the circumferential direction to press the segment coil. Thereby, the segment coil can be reliably fixed to one axial end of the stator core.

As described above, according to the manufacturing method of the present invention, the split cores can be pressed against the segment coils with a constant force, so that they can be stably fixed and the quality of the stator can be stabilized.

1 is a cross-sectional view of a rotating electrical machine; FIG. It is the front view which looked at the stator core from the axial direction. It is a side view of a stator core. FIG. 3 is a cross-sectional view taken along line XX of FIG. 2; It is a side view of a segment coil. FIG. 4 is a cross-sectional view showing a state in which segment coils are inserted into slots of a stator core; FIG. 4 is a cross-sectional view showing a state in which adjacent split cores are relatively rotated; FIG. 10 is a cross-sectional view showing a state in which adjacent split cores are relatively rotated in another embodiment. FIG. 8 is a cross-sectional view of the vicinity of the axial end of a stator core according to still another embodiment; FIG. 11 is a cross-sectional view showing a state in which adjacent split cores are relatively rotated in another embodiment. FIG. 11 is a cross-sectional view showing a state in which adjacent split cores are relatively rotated in another embodiment.

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described with reference to the drawings.

A rotary electric machine 1 shown in FIG. 1 is used, for example, as an electric motor or generator for an electric vehicle (including a hybrid vehicle). A rotating electric machine 1 is a three-phase brushless motor and includes a stator 2 , a rotor 3 , a rotating shaft 4 and a case 5 . The stator 2 has a stator core 6 and coils 7 and is fixed to the inner circumference of the case 5 . The rotor 3 has a rotor core 8 and magnets 9 and is fixed to the outer circumference of the rotating shaft 4 . The outer peripheral surface of the rotor 3 (in the illustrated example, the outer peripheral surface of the magnet 9) and the inner peripheral surface of the stator 2 (in the illustrated example, the inner peripheral surface of the teeth 6b of the stator core 6) are separated by a small radial gap. facing each other. The rotary shaft 4 is attached to the case 5 via bearings 10 . By energizing the coil 7 of the stator 2, the rotor 3 and the rotary shaft 4 rotate together.

The stator core 6, as shown in FIG. 2, has a cylindrical portion 6a and a plurality of teeth 6b projecting radially inwardly from the cylindrical portion 6a. Slots 6c are provided between adjacent teeth 6b. The stator core 6 has a plurality of split cores 61 coaxially arranged side by side in the axial direction, preferably three or more split cores 61 . The stator core 6 of this embodiment has three split cores 61 as shown in FIG. Each split core 61 is formed of, for example, a laminated steel plate obtained by laminating a plurality of electromagnetic steel plates in the axial direction. Alternatively, each split core 61 may be formed of a dust core. Each split core 61 has a cylindrical portion 61a, teeth 61b, and slots 61c. The cylindrical portion 61a, the teeth 61b and the slots 61c of the three split cores 61 form the cylindrical portion 6a, the teeth 6b and the slots 6c of the stator core 6, respectively.

A method of manufacturing the stator 2 according to one embodiment of the present invention will be described below.

First, a plurality of blanks are formed by punching a steel plate into a predetermined shape, and the split cores 61 are formed by laminating the plurality of blanks. In this embodiment, since the plurality of split cores 61 have the same shape, each split core 61 is formed by laminating the same number of blanks having the same shape. In this case, since only one type of blank punching die is required, the manufacturing cost can be reduced as compared with the case where a plurality of types of dies are used.

By the way, the steel plate, which is the material of the blank material, is not completely uniform in thickness, and often has a slight inclination in thickness from lot to lot. Therefore, when blank members are laminated to form the split core 61 , the thickness gradients of the blank members are accumulated, and the thickness (axial dimension) of the split core 61 is inclined. In the present embodiment, since the blanks forming the plurality of split cores 61 are formed from the same lot of steel plates using the same mold, the inclination of the thickness of each split core 61 is the same. Therefore, by shifting the phases of the plurality of split cores 61 and stacking them, more specifically, by shifting the phases of the three split cores 61 by 120° each, the inclination of the thickness of each split core 61 can be offset. can be done.

In addition, burrs projecting in the axial direction (direction perpendicular to the thickness direction of the blank) are generated at the ends of the blank that is punched from the steel plate. In this embodiment, the blanks are stacked with the direction (front and back) aligned so that the burrs protrude in the same direction (for example, the burrs of all the blanks protrude downward). As a result, interference between burrs of adjacent blanks can be avoided, and the blanks can be uniformly laminated.

Next, the stator core 6 is formed by arranging the three split cores 61 in the axial direction. At this time, the adjacent split cores 61 are brought into contact with each other, and the circumferential positions of the teeth 61b of the split cores 61 are aligned (see FIG. 4). Cylindrical portions 61a, teeth 61b, and slots 61c of three split cores 61 arranged in the axial direction form cylindrical portions 6a, teeth 6b, and slots 6c of stator core 6, respectively. At this time, the three split cores 61 are held so as to be relatively rotatable in the circumferential direction. One or more of the three split cores 61 are fixed, and the other split cores 61 are connected to the driving means. In this embodiment, the upper split core 61 (hereinafter referred to as the first split core 61A) and the lower split core 61 (hereinafter referred to as the third split core 61C) in FIG. , second split core 61B) are attached to the driving means.

Next, the segment coils 71 are inserted into the slots 6 c of the stator core 6 . As shown in FIG. 5, the segment coil 71 has a substantially U-shape having a pair of parallel straight leg portions 71a and a connecting portion 71b connecting the ends of the pair of leg portions 71a. there is The segment coil 71 is formed of, for example, a rectangular wire made of a conductor whose surface is covered with an insulating film. An end portion of the segment coil 71 is provided with an exposed portion 71c where the conductor is exposed by removing the insulating coating. A pair of leg portions 71a of the segment coil 71 are inserted into different slots 6c of the stator core 6, and the tip of each leg portion 71a is axially protruded from the slot 6c (see FIG. 6).

After inserting all the segment coils 71 into the slots 6c of the stator core 6, the adjacent split cores 61 are relatively rotated around the axis. When the stator core 6 has three or more split cores 61, one of the split cores 61 and the pair of split cores 61 arranged on both sides in the axial direction are relatively rotated. In this embodiment, the first split core 61A and the third split core 61C are fixed, and the second split core 61B is rotated in one circumferential direction (left side in the drawing). As a result, as shown in FIG. 7, the segment coil 71 is pushed to one side in the circumferential direction by the teeth 61b of the second split core 61B and comes into contact with the teeth 61b of the first split core 61A and the third split core 61C.

Further, by rotationally driving the second split core 61B, the teeth 61b of the second split core 61B are pressed against the segment coil 71 from the other side in the circumferential direction (the right side in the figure) by the driving force (torque) of the driving means. The teeth 61b of the first split core 61A and the third split core 61C are pressed against the segment coil 71 from one circumferential side (left side in the figure). Then, when the torque of the driving means for rotationally driving the second split core 61B reaches a predetermined value, the rotation of the second split core 61B is stopped and the second split core 61B is held at that position. 6 and 7, the circumferential gap between the segment coil 71 and the tooth 61b of each split core 61 and the amount of rotation of each split core 61 are exaggerated for easy understanding (described later). The same applies to FIGS. 8 to 11).

As described above, the amount of relative rotation of the split cores 61A, 61B, and 61C, and in the present embodiment, the amount of rotation of the second split core 61B, is controlled by the torque of the driving means, so that each of the split cores 61A, 61B, and 61C can rotate. Teeth 61b are pressed against segment coil 71 with a constant force (torque). As a result, the segment coils 71 are fixed to the stator core 6 with a stable force, so the quality of the stator 2 can be stabilized.

Thus, the plurality of split cores 61A, 61B, 61C are fixed to each other while each split core 61A, 61B, 61C is pressed against the segment coil 71 with a predetermined force. The fixing method is not particularly limited, and welding, adhesion, mechanical means, etc., can be employed, for example. When fixing by welding, for example, the boundary between the adjacent split cores 61 on the outer peripheral surface of the stator core 6 is welded. When fixing by adhesion, for example, the end faces of adjacent split cores 61 are fixed by adhesion. When fixing by mechanical means, for example, the entire stator core 6 made up of a plurality of split cores 61 is sandwiched from both sides in the axial direction by bolts and nuts.

After that, the portion of the leg portion 71a of the segment coil 71 protruding from the slot 6c of the stator core 6 in one axial direction (upward in FIG. 7) is twisted so as to be inclined in one or the other circumferential direction (forming step). As a result, the exposed portion 71c of the leg portion 71a twisted in one circumferential direction and the exposed portion 71c of the leg portion 71a twisted in the other circumferential direction are radially adjacent to each other. Thereafter, the exposed portions 71c of the leg portions 71a adjacent in the radial direction are welded together to form U-phase, V-phase, and W-phase coils (welding step). In performing these forming processes and welding processes, the segment coils 71 are supported by fixing the segment coils 71 and the stator core 6 by pressing the teeth 61b of each split core 61 against the segment coils 71 from the circumferential direction. Since no jig or the like is required, the process is simplified.

After that, the coil 7 is impregnated with varnish and hardened. In conventional stators, the slots of the stator coils are impregnated with varnish in order to fix the stator core and the coils. In this case, it is necessary to sufficiently heat the inside of the stator coil in order to harden the varnish, so a large-sized heating furnace such as a batch furnace is required. In contrast, in the present invention, as described above, the segment coils 71 and the stator core 6 are fixed by pressing the teeth 61b of each split core 61 against the segment coils 71 in the circumferential direction. Varnish impregnation can be omitted. Therefore, for example, only the portions of the coil 7 protruding from the slots 6c, that is, the portions arranged on both sides of the stator core 6 in the axial direction need to be impregnated with varnish. In this case, since only the portion of the coil 7 exposed to the outside from the stator core 6 needs to be heated, simple heating equipment using radiant heat or the like is sufficient, and energy and space can be saved. If the coil 7 in the slot 6c is also impregnated with varnish, the fixing force between the coil 7 and the stator core 6 can be further enhanced. Moreover, if there is no need to impregnate the coil 7 with varnish, the varnish impregnation step may be omitted.

The invention is not limited to the above embodiments. Other embodiments of the present invention will be described below, but descriptions of the same points as those of the above-described embodiments will be omitted.

The procedure for relatively rotating the plurality of split cores 61 is not limited to the above embodiment. For example, after inserting the segment coil 71 into the slot 6c of the stator core 6 as shown in FIG. 7, each of the split cores 61A, 61B, and 61C may be pressed against the segment coil 71 by rotating to the middle right). At this time, if the first and third split cores 61A and 61C are rotated at the same time, they can be rotated by a common drive means, thereby simplifying the device.

Alternatively, the plurality of split cores 61 may be rotated one by one. For example, after inserting the segment coil 71 into the slot 6c of the stator core 6 as shown in FIG. do. Then, while the first split core 61A is stopped, the third split core 61C is rotated to the other side in the circumferential direction (right side in the drawing). As a result, as shown in FIG. 8, the segment coil 71 is pushed to the other side in the circumferential direction by the teeth 61b of the third split core 61C and comes into contact with the teeth 61b of the second split core 61B. Then, when the torque of the drive means for rotationally driving the third split core 61C reaches a predetermined value, the rotation of the third split core 61C is stopped and the third split core 61C is held at that position.

Next, while the third split core 61C is stopped, the first split core 61A is rotated to the other side in the circumferential direction (right side in the drawing). As a result, the teeth 61b of the first split core 61A are pressed against the segment coil 71, as shown in FIG. Then, when the torque of the drive means for rotationally driving the first split core 61A reaches a predetermined value, the rotation of the first split core 61A is stopped and the first split core 61A is held at that position.

As described above, the first and third split cores 61A and 61C connected to the drive means are rotated one by one and the respective torques are controlled, so that the teeth 61b of the split cores 61A and 61C are rotated by the segment coil 71. The pressing force can be managed with high precision.

By the way, in the state shown in FIG. 7, the side surface (the right side surface in the figure) on the other side in the circumferential direction of each tooth 61b of the first split core 61A is pressed against the segment coil 71, but the one side in the circumferential direction of each tooth 61b is pressed. There is a gap in the circumferential direction between the side surface of (left side surface in the figure) and the segment coil 71 . Therefore, as shown in FIG. 9, the end face of the stator core 6 may be crimped to fill the gap between each tooth 61b and the segment coil 71. FIG. In the illustrated example, a crimping portion 61d is formed in the vicinity of one end in the circumferential direction (left side in the drawing) of the upper surface of each tooth 61b of the first split core 61A. As a result, protrusions 61e that protrude to one side in the circumferential direction are formed at the upper ends of the teeth 61b of the first split core 61A. By pressing the projecting portion 61e against the segment coil 71, the segment coil 71 can be fixed more firmly. Furthermore, if the caulking portion 61d is also formed near the end on the other side in the circumferential direction of the upper surface of the tooth 61b of the first split core 61A, the fixing force of the segment coil 71 is further increased (not shown).

In the above embodiment, the case where the axial dimensions of the plurality of split cores 61 are equal has been shown, but this is not the only option, and the axial dimensions of the split cores 61 may be made different. For example, in the embodiment shown in FIG. 10, the axial dimension of the central second split core 61B is made larger than the axial dimensions of the first and third split cores 61A and 61C on both sides in the axial direction. In the vicinity of the boundary between adjacent split cores 61, the segment coil 71 is sandwiched between the teeth 61b on both sides in the circumferential direction, so the fixing force is greater than in other axial regions. As shown in FIG. 10, if the axial dimension of the central split core 61B is increased, the boundary between the adjacent split cores 61, that is, the portion where the fixing force is increased, is spaced apart in the axial direction. The stator core 6 is less likely to rattle.

Further, as shown in FIG. 11, the axial dimension of the upper split core 61A may be larger than the axial dimensions of the other split cores 61B and 61C. In this case, the boundary between the adjacent split cores 61, that is, the portion where the fixing force is large, is arranged at a position biased downward, so the fixation between the segment coil 71 and the upper end of the stator core 6 may become unstable. be. Therefore, as shown in FIG. 11, a crimping portion 61d is provided on the upper surface of each tooth 6b of the stator core 6 to form a circumferential protrusion 61e at the upper end of each tooth 6b, and the protrusion 61e is used as the segment coil. It is preferably pressed against 71 .

By the way, when the plurality of split cores 61 are rotationally driven by separate driving means, the magnitude of the torque that presses each split core 61 against the segment coil 71 may be the same or different. For example, when the axial dimensions of the plurality of split cores 61 are different as in the embodiment shown in FIGS. can be increased.

In the above embodiment, the case where the teeth 61b of the split core 61 are directly pressed against the segment coil 71 has been shown, but the present invention is not limited to this, and they may be pressed via insulating paper or the like.

In the above embodiment, the plurality of split cores 61 are relatively rotated and then fixed by welding or the like. However, the present invention is not limited to this. may be rotated relative to each other. Specifically, for example, a plurality of split cores 61 are arranged in the axial direction and fixed by welding or the like in a state in which the circumferential positions of the teeth 61b are aligned. By inserting the segment coil 71 into the slot 6c in a state in which the plurality of split cores 61 are integrated in this way, the insertion of the segment coil 71 is facilitated. Thereafter, the plurality of split cores 61 are relatively rotated while plastically deforming the fixed portions (for example, welded portions) of the plurality of split cores 61 . After that, if necessary, the plurality of split cores 61 may be further fixed by welding or the like.

The configuration of the stator core 6 is not limited to the above. For example, the number of split cores 61 may be two, or four or more.

1 Rotary electric machine 2 Stator 3 Rotor 4 Rotating shaft 5 Case 6 Stator core 6a Cylindrical portion 6b Teeth 6c Slot 7 Coil 8 Rotor core 9 Magnets 61, 61A, 61B, 61C Split core 61a Cylindrical portion 61b Teeth 61c Slot 61d Crimp portion 61e Protruding portion 71 segment coil

Claims (2)

A step of arranging a plurality of split cores in the axial direction to form a stator core having a plurality of teeth and a plurality of slots formed between the teeth in the circumferential direction;
inserting a segment coil into the slot;
A stator manufacturing method comprising a step of relatively rotating a plurality of split cores to press the split cores against the segment coils inserted in the slots in the circumferential direction,
A method of manufacturing a stator for a rotary electric machine, wherein the amount of relative rotation of the plurality of split cores is controlled by torque. 2. The method of manufacturing a stator for a rotary electric machine according to claim 1, wherein the one axial end of the tooth of the stator core is crimped so that the one axial end of the tooth protrudes in the circumferential direction and is pressed against the segment coil. .

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