JP2022128068A - Rotor manufacturing method - Google Patents

Abstract

A technique for firmly fixing a magnet to a rotor core is disclosed.
A method of manufacturing a rotor includes steps of placing a magnet and an expansion sheet interposed between the inner surface of the magnet hole and the magnet in a magnet hole of a rotor core in which a plurality of steel plates are laminated; Among these, the step of heating the expansion sheet in a state where the lamination surface, which is located outside the magnet hole and exposes the plurality of steel plates, is placed under a reduced pressure atmosphere. An expansive sheet is a sheet whose volume increases when heated.
[Selection drawing] Fig. 3

Description

The technology disclosed in this specification relates to a rotor manufacturing method.

Patent Literature 1 discloses a method for manufacturing a rotor. In this manufacturing method, a magnet with an expansion sheet whose volume increases when heated is affixed to the side surface is inserted into a magnet hole of a rotor core in which a plurality of steel plates are laminated, and then the rotor core is heated to expand the expansion sheet. . As a result, the space between the side surface of the magnet and the inner surface of the magnet hole of the rotor core is filled with the expansion sheet, and the magnet is fixed to the rotor core via the expansion sheet.

JP 2015-35888 A

In recent years, attempts have been made to increase the speed of rotation of motors. Along with this, it is required to fix the magnets more firmly to the rotor core. This specification discloses a technique for firmly fixing a magnet to a rotor core.

A method for manufacturing a rotor disclosed in the present specification includes steps of placing a magnet and an expansion sheet interposed between the inner surface of the magnet hole and the magnet in a magnet hole of a rotor core in which a plurality of steel plates are laminated; and heating the expansion sheet in a state in which the lamination surface of the surfaces of the is positioned outside the magnet hole and where the plurality of steel plates are exposed is placed in a reduced pressure atmosphere.

In a rotor core in which a plurality of steel plates are laminated, the plurality of steel plates are exposed on the inner surface of the magnet hole along the lamination direction. is formed. The technology disclosed in the present specification utilizes the unique structure of this lamination surface to fill the space between the inner surface of the magnet hole and the magnet with the expansion sheet, and further fill the concave portion existing on the inner surface of the magnet hole. to fix the magnets to the rotor core more firmly. For this purpose, it is preferable to heat the expansion sheet while placing the laminated surface (surface other than the inner surface of the magnet hole) of the rotor core surface where the plurality of steel plates are exposed under a reduced pressure atmosphere. As a result, the space between the inner surface of the magnet hole and the magnet is decompressed through the space between the laminated steel plates, and the expansion sheet, which expands due to heating, is formed into minute particles existing on the inner surface of the magnet hole. Even the concave portion is filled. As a result, the contact area between the expansion sheet and the inner surface of the magnet hole is increased, and the expansion sheet that has entered the recess exerts an anchoring effect, whereby the magnet and the rotor core are more firmly fixed.

It is a cross-sectional view of the rotor of the first embodiment. FIG. 2 is a longitudinal sectional view taken along line II-II of FIG. 1; It is a schematic diagram of the heating process of the first embodiment. 4 is an enlarged cross-sectional view of the vicinity of the inner surface 36a of the magnet hole 36 of the rotor core 30 of the first embodiment; FIG. FIG. 5 is a cross-sectional view of the rotor of the second embodiment;

(First embodiment)
In this embodiment, the rotor 10 will be described with reference to FIGS. 1 to 4. FIG. The rotor 10 is used, for example, by being incorporated in a motor (not shown) mounted on an automobile such as an electric automobile or a hybrid automobile. The rotor 10 rotates around the axis of rotation AX shown in FIG. 1 when power is supplied to the motor. Below, the direction parallel to the rotation axis AX may be referred to as the vertical direction.

As shown in FIG. 1, the rotor 10 includes a shaft 20, a rotor core 30, a plurality of (20 in this embodiment) magnets 40, a first end plate 50 (see FIG. 2), and a second end plate. 52 (see FIG. 2) and an expansion sheet 60 . In FIG. 1, cross-sectional hatches of the shaft 20 and the rotor core 30 are omitted in order to facilitate understanding of the drawing. The shaft 20 is made of metal material (for example, carbon steel, special steel, non-magnetic aluminum or stainless steel). The shaft 20 has a cylindrical shape extending vertically. Two fixing grooves 22 are formed on the outer peripheral surface of the shaft 20 . The two fixed grooves 22 are recessed radially inward from the outer peripheral surface of the shaft 20 . The two fixed grooves 22 are arranged around the rotation axis AX with an interval of 180 degrees from each other.

As shown in FIG. 2, a flange 24 protrudes from the outer peripheral surface of shaft 20 . The flange 24 extends in a direction perpendicular to the vertical direction. A resolver 26 is attached to the outer peripheral surface of the shaft 20 . The resolver 26 is arranged above the lower end of the flange 24 . A resolver 26 detects the rotation angle of the rotor 10 .

Rotor core 30 has a cylindrical shape extending in the vertical direction. As shown in FIG. 1, the rotor core 30 has a positioning hole 31 extending vertically. Two protrusions 32 are formed on the inner surface of the positioning hole 31 . The two protrusions 32 are arranged around the rotation axis AX with an interval of 180 degrees from each other. Projection 32 extends radially inward of rotor core 30 from the inner surface of positioning hole 31 . The protrusions 32 engage with the fixed grooves 22 when the shaft 20 is inserted into the rotor core 30 . This suppresses rotation of the shaft 20 relative to the rotor core 30 .

Further, as shown in FIG. 2, the rotor core 30 is a laminate in which a plurality of electromagnetic steel sheets 34 are stacked vertically. The electromagnetic steel sheet 34 has an annular shape. In FIG. 2, cross-sectional hatches of the shaft 20 and the plurality of electromagnetic steel plates 34 are omitted in order to facilitate understanding of the drawing. Moreover, below, the up-down direction may be called a lamination direction. As shown in FIG. 1, the rotor core 30 has a plurality of (20 in this embodiment) magnet holes 36 . The magnet holes 36 are arranged side by side in the direction along the outer peripheral surface of the rotor core 30 . As shown in FIG. 2, the magnet hole 36 penetrates the rotor core 30 from the upper end surface 30a of the rotor core 30 toward the lower end surface 30b. The magnet hole 36 extends vertically.

The rotor core 30 has an inner lamination surface 30c, an outer lamination surface 30d, and a first lamination surface 30e. The inner lamination surface 30 c is arranged radially inward of the rotor core 30 relative to the magnet hole 36 . The inner lamination surface 30c is exposed in the lamination direction within the positioning hole 31 . The outer lamination surface 30 d is arranged radially outside of the rotor core 30 relative to the magnet holes 36 . The outer lamination surface 30 d corresponds to the outer peripheral surface of the rotor core 30 . The outer lamination surface 30d corresponds to the outer peripheral surface of the rotor core 30 and is exposed along the lamination direction. The first lamination surface 30e is exposed on the inner surface 36a of the magnet hole 36 along the lamination direction.

Magnet 40 is a permanent magnet. Magnet 40 is, for example, a neodymium magnet, an alnico magnet, a ferrite magnet, a samarium cobalt magnet, a praseodymium magnet, a samarium nitrogen iron magnet, a platinum magnet, or a cerium cobalt magnet, and in this embodiment magnet 40 is a neodymium magnet. .

A magnet 40 is arranged in the magnet hole 36 . The magnet 40 has a longitudinal direction in the vertical direction. The upper end surface of the magnet 40 is arranged below the upper end surface 30 a of the rotor core 30 . The lower end surface of the magnet 40 is arranged above the lower end surface 30 b of the rotor core 30 . The corners of the upper end surface and the lower end surface of the magnet 40 are chamfered. Also, the side surface 40a of the magnet 40 is arranged apart from the inner surface 36a of the magnet hole 36 .

The first end plate 50 is made of a metal material (for example, non-magnetic aluminum or stainless steel). The first end plate 50 is welded and fixed to the upper end surface 30 a of the rotor core 30 . The first end plate 50 covers the upper openings of the magnet holes 36 . The lower surface of the first end plate 50 is arranged apart from the upper end surface of the magnet 40 . The first end plate 50 contacts the flange 24 from below.

The second end plate 52 is made of a metal material (for example, non-magnetic aluminum or stainless steel). The second end plate 52 is welded and fixed to the lower end surface 30 b of the rotor core 30 . A second end plate 52 covers the lower opening of the magnet hole 36 . The upper surface of the second end plate 52 is arranged apart from the lower end surface of the magnet 40 . A washer 27 and a nut 28 are arranged below the second end plate 52 . The first end plate 50 , the rotor core 30 and the second end plate 52 are sandwiched between the flange 24 and the nut 28 via the washer 27 in the vertical direction. Thereby, the first end plate 50 , the rotor core 30 and the second end plate 52 are fixed to the shaft 20 .

The expansion sheet 60 is non-magnetic. In addition, the expandable sheet 60 has a property of increasing its volume by heating in a non-pressurized state. In this embodiment, the expansion sheet 60 is made of a foamable resin material that foams when heated. This type of resin material contains, for example, capsules that evaporate when heated, and the volume increases as the capsules evaporate. The resin material may be at least one of a thermoplastic resin and a thermosetting resin. In this embodiment, the resin material is epoxy resin. Also, the resin material is made of, for example, polyetherimide, polyamideimide, polyphenylene oxide, polyethersulfone, or polysulfone. In addition, the expansion sheet 60 may contain glass fiber. In the manufacturing process of a sheet containing a resin material and glass fibers, the resin material is heated under pressure to soften the resin material, and then cooled to harden the resin material, thereby accumulating residual stress in the glass fibers. can be done. The expansion sheet 60 containing such glass fibers can expand due to the deformation associated with restoration of the glass fibers when heated in a non-pressurized state to soften the resin material.

The expansion sheet 60 is arranged between the inner surface 36a of the magnet hole 36 and the side surface 40a of the magnet 40 in the direction perpendicular to the vertical direction. The expansion sheet 60 is in close contact with both the inner surface 36 a of the magnet hole 36 and the side surface 40 a of the magnet 40 .

Next, a method for manufacturing the rotor 10 will be described. The manufacturing method of the rotor 10 includes a stacking process, an affixing process, an inserting process, a depressurizing process, a heating process, an assembling process, and a fixing process. The stacking process, the attaching process, the inserting process, the depressurizing process, the heating process, the assembling process, and the fixing process are performed in this order.

The stacking step stacks a plurality of electromagnetic steel sheets 34 . In the lamination process, first, the electromagnetic steel sheets 34 are produced by punching out a metal plate using a press machine. The inner lamination surface 30c, the outer lamination surface 30d, and the first lamination surface 30e of the manufactured electromagnetic steel sheet 34 are formed with minute irregularities such as sagging, fractured surfaces, and burrs. Next, a plurality of electromagnetic steel sheets 34 are stacked in the stacking direction. Thus, the rotor core 30 is manufactured. On the inner lamination surface 30c, the outer lamination surface 30d, and the first lamination surface 30e of the manufactured rotor core 30, minute recesses 38 (see FIG. 4) are formed at the boundaries between the electromagnetic steel plates 34 adjacent to each other. there is

The sticking step sticks the expansion sheet 60 to the side surface 40 a of the magnet 40 . In the attaching step, the expansion sheet 60 is attached to the side surface 40a of the magnet 40 using an adhesive. The attached expansion sheet 60 is a sheet in which the glass fibers have accumulated residual stress, that is, a sheet before expansion.

The inserting step inserts the magnet 40 and the expansion sheet 60 into the magnet hole 36 . In the inserting step, first, the lower electrode 90 is inserted from below the magnet hole 36 , and the upper surface of the lower electrode 90 is positioned slightly above the lower surface of the magnet hole 36 . Next, the magnet 40 to which the expansion sheet 60 before expansion is attached is held by an arm device (not shown). Next, by moving the arm device toward the magnet hole 36 of the rotor core 30 , the magnet 40 is inserted into the magnet hole 36 until the lower surface of the magnet 40 contacts the lower electrode 90 . This can prevent the magnet 40 from coming out of the magnet hole 36 . When the magnet 40 is inserted into the magnet hole 36 , the expansion sheet 60 is interposed between the inner surface 36 a of the magnet hole 36 and the side surface 40 a of the magnet 40 . Also, the expansion sheet 60 is arranged away from the inner surface 36 a of the magnet hole 36 . After that, similar processing is repeated to insert all the magnets 40 into all the remaining magnet holes 36 of the rotor core 30 .

In the decompression step, the inner lamination surface 30c and the outer lamination surface 30d of the rotor core 30 are arranged in a reduced pressure atmosphere. As shown in FIG. 3 , in the pressure reducing step, first, the first pressure reducing device 70 is attached to the rotor core 30 so as to cover the positioning hole 31 of the rotor core 30 . This defines a first space 72 between the rotor core 30 and the first pressure reducing device 70 . When the first decompression device 70 is attached to the rotor core 30, the seal member 74 contacts the upper end surface 30a and the lower end surface 30b of the rotor core 30, thereby suppressing leakage of the air in the first space 72 to the outside. Next, the second decompression device 80 is attached to the rotor core 30 so as to cover the outer lamination surface 30d of the rotor core 30 . A second space 82 is thereby defined between the rotor core 30 and the second pressure reducing device 80 . When the second decompression device 80 is attached to the rotor core 30, the sealing member 84 contacts the upper end surface 30a and the lower end surface 30b of the rotor core 30, thereby suppressing leakage of the air in the second space 82 to the outside. Next, the pump of the first decompression device 70 and the pump of the second decompression device 80 are driven, and the first space 72 and the second space 72 are decompressed until the degree of vacuum of the first space 72 and the degree of vacuum of the second space 82 become the same. The space 82 is decompressed. As a result, the inner stacking surface 30c and the outer stacking surface 30d are placed under a reduced pressure atmosphere.

In the heating step, the expansion sheet 60 is heated and expanded while the first space 72 and the second space 82 are decompressed. In the heating process, first, the upper electrode 92 is inserted into the magnet hole 36 from above until it contacts the upper surface of the magnet 40 . Thereby, the magnet 40 is sandwiched between the lower electrode 90 and the upper electrode 92, and the position of the magnet 40 is fixed. Next, the expansion sheet 60 is heated together with the magnet 40 in a non-pressurized state by heating the magnet 40 with electricity through the lower electrode 90 and the upper electrode 92 . When the temperature of the expansion sheet 60 rises and exceeds the glass transition temperature of the resin material forming the expansion sheet 60, the resin material softens. At the same time, the capsules contained in the resin material are vaporized and the resin material is foamed, thereby expanding the expandable sheet 60 . At this time, if the expansion sheet 60 contains glass fibers, the glass fibers are deformed so that the residual stress is eliminated, and the expansion sheet 60 expands further. In this way, the expansion sheet 60 expands while forming a void inside. The expansion sheet 60 expands toward the inner surface 36a of the magnet hole 36 of the rotor core 30 and contacts the inner surface 36a of the magnet hole 36 (that is, the first lamination surface 30e). Even after the expansion sheet 60 abuts against the first lamination surface 30e, the expansion sheet 60 is pressed against the first lamination surface 30e when the resin material contained in the expansion sheet 60 is foamed and the glass fibers are deformed. At this time, since the first space 72 and the second space 82 are decompressed and the inner lamination surface 30c and the outer lamination surface 30d are arranged in a reduced pressure atmosphere, the magnet holes 36 are separated from each other by the adjacent laminated electromagnetic steel plates 34. The pressure is reduced throughout the As a result, as shown in FIG. 4, the expansion sheet 60 that expands due to heating fills even the minute recesses 38 formed in the first lamination surface 30e. As a result, the contact area between the inflatable sheet 60 and the first lamination surface 30e increases, and the inflatable sheet 60 comes into close contact with the first lamination surface 30e. Next, when the energization and heating of the magnet 40 is stopped, the temperature of the expansion sheet 60 drops below the glass transition temperature of the resin material forming the expansion sheet 60, and the resin material hardens. As a result, the expansion sheet 60 is solidified while maintaining the porous structure inside the sheet. The expansion sheet 60 that has entered the recess 38 exerts an anchor effect, and the magnet 40 and the rotor core 30 are fixed more firmly. After the expansion sheet 60 is solidified, the lower electrode 90 and the upper electrode 92 are pulled out from the magnet hole 36 .

The assembling process assembles the first end plate 50 and the second end plate 52 to the rotor core 30 . In the assembling process, the first end plate 50 is first pressed against the upper end surface 30a of the rotor core 30 from above and then welded. Next, the second end plate 52 is pressed against the lower end surface 30b of the rotor core 30 from below and then welded.

The fixing step fixes the rotor core 30 to the shaft 20 . In the fixing step, as shown in FIG. 2, the shaft 20 is first inserted into the positioning hole 31 of the rotor core 30 while engaging the fixing groove 22 (see FIG. 1) with the protrusion 32 (see FIG. 1) of the rotor core 30. After insertion, the flange 24 abuts the upper surface of the first end plate 50 . Next, washer 27 and nut 28 are inserted from the lower end of shaft 20, and nut 28 is tightened upward. As a result, rotor core 30 , first end plate 50 and second end plate 52 are fixed to shaft 20 . Thus, the rotor 10 is manufactured.

(effect)
In this embodiment, the manufacturing method of the rotor 10 includes: a magnet 40 in a magnet hole 36 of a rotor core 30 in which a plurality of electromagnetic steel plates 34 are laminated; 60, and, of the surfaces of the rotor core 30, the inner lamination surface 30c and the outer lamination surface 30d, which coincide with the outside of the magnet hole 36 and expose the plurality of electromagnetic steel plates 34, are arranged in a reduced pressure atmosphere. , and heating the expansion sheet 60 . The expandable sheet 60 is a sheet whose volume is increased by heating.

In the rotor core 30 in which a plurality of electromagnetic steel sheets 34 are laminated, the plurality of electromagnetic steel sheets 34 are exposed along the lamination direction on the inner surface 36a of the magnet hole 36. Such a lamination surface, for example, the first lamination surface 30e , a minute concave portion 38 is formed at the boundary between the electromagnetic steel plates 34 adjacent to each other. The technique disclosed in the present specification utilizes a structure unique to the first lamination surface 30 e , and further expands the expansion sheet 60 filling the space between the inner surface 36 a of the magnet hole 36 and the magnet 40 on the inner surface 36 a of the magnet hole 36 . By filling even the existing recesses 38 , the magnets 40 are more firmly fixed to the rotor core 30 . For this purpose, the expansion sheet 60 may be heated while the inner lamination surface 30c and the outer lamination surface 30d of the surfaces of the rotor core 30 where the plurality of electromagnetic steel sheets 34 are exposed are placed under a reduced pressure atmosphere. As a result, the space between the inner surface 36a of the magnet hole 36 and the magnet 40 is decompressed through the space between the plurality of laminated electromagnetic steel plates 34, so that the expansion sheet 60, which expands due to heating, is compressed into the magnet hole 36. It is filled even into minute recesses 38 present on the inner surface 36a of the . As a result, the contact area between the expansion sheet 60 and the inner surface 36a of the magnet hole 36 increases, and the expansion sheet 60 entering the recess 38 exerts an anchor effect, thereby making the magnet 40 and the rotor core 30 more rigid. fixed to

(correspondence relationship)
The electromagnetic steel sheet 34 is an example of the "steel plate", the upper end surface 30a, the lower end surface 30b, the inner laminated surface 30c, the outer laminated surface 30d, and the first laminated surface 30e are examples of the "surface", The inner lamination surface 30c and the outer lamination surface 30d are examples of "lamination surfaces".

(Second embodiment)
A second embodiment will be described with reference to FIG. In the second embodiment, only the points different from the first embodiment will be explained, and the same reference numerals will be given to the same points as in the first embodiment, and the explanation will be omitted.

As shown in FIG. 5, the rotor core 30 has a plurality of (10 in this embodiment) elongated holes 136 . Long holes 136 are arranged side by side in a direction along the outer peripheral surface of rotor core 30 . Although not shown, the long hole 136 penetrates the rotor core 30 from the upper end surface 30a of the rotor core 30 toward the lower end surface 30b. The long hole 136 extends vertically.

Further, the rotor core 30 has a second lamination surface 131 . The second lamination surface 131 is arranged radially inside the rotor core 30 relative to the magnet hole 36 . The second lamination surface 131 is exposed to the slot 136 along the lamination direction.

In the pressure reducing process of the second embodiment, the first pressure reducing device 70 is attached to the rotor core 30 so as to block the long hole 136 of the rotor core 30 . When the first decompression device 70 is driven, the space defined between the first decompression device 70 and the rotor core 30 is decompressed, and the second lamination surface 131 is placed under a decompressed atmosphere.

Although specific examples of the present invention have been described in detail above, these are merely examples and do not limit the scope of the claims. The technology described in the claims includes various modifications and changes of the specific examples illustrated above.

In a modified example, the expandable sheet 60 is not limited to the foamable sheet material described above or the sheet material containing a fiber material, and may be a sheet that expands by a chemical reaction such as a neutralization reaction, for example. The expansion sheet 60 may be any material as long as it increases in at least the dimension in the thickness direction when heated and can fill the gap between the magnet holes 36 of the rotor core 30 and the magnets 40 . It is not particularly limited.

In a modification, the first space 72 and the second space 82 may be decompressed using one decompression device in the decompression step.

In a modified example, the degree of vacuum in the first space 72 may be higher or lower than the degree of vacuum in the second space 82 in the decompression step.

In a modification, the expansion sheet 60 may be heated by heating the rotor core 30 in the heating step.

The technical elements described in this specification or in the drawings exhibit technical usefulness alone or in various combinations, and are not limited to the combinations described in the claims as of the filing. In addition, the techniques exemplified in this specification or drawings can simultaneously achieve a plurality of purposes, and achieving one of them has technical utility in itself.

10: Rotor 20 : Shaft 22 : Fixed groove 24 : Flange 26 : Resolver 27 : Washer 28 : Nut 30 : Rotor core 30a : Upper end surface 30b : Lower end surface 30c : Inner lamination surface 30d : Outer lamination surface 30e : First lamination surface 31 : Positioning hole 32 : Protrusion 34 : Electromagnetic steel plate 36 : Magnet hole 36a : Inner surface 38 : Recess 40 : Magnet 40a : Side surface 50 : First end plate 52 : Second end plate 60 : Expansion sheet 70 : First decompression device 72 : First spaces 74, 84 : Seal member 80 : Second decompression device 82 : Second space 131 : Second stacking surface 136 : Long hole AX : Rotating shaft

Claims (1)

A method for manufacturing a rotor, comprising:
disposing a magnet and an expansion sheet interposed between the inner surface of the magnet hole and the magnet in a magnet hole of a rotor core in which a plurality of steel plates are laminated;
a step of heating the expansion sheet in a state in which a laminated surface of the surface of the rotor core, which is located outside the magnet hole and exposes the plurality of steel plates, is placed under a reduced pressure atmosphere;
A manufacturing method comprising:

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