JP2014064422A - Rotor core and method manufacturing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a rotor core that reduces magnetic flux passing through bridges thereof and also prevents core sheets from becoming short-circuited to each other, and to provide a method for manufacturing the same.SOLUTION: A rotor core 10 is formed by laminating core sheets 12. Each core sheet 12 has bridges 22a and 22b between ends of magnet holes 14a and 14b and an outer periphery of the core sheet 12 so as to be prevented from being segmented into a plurality of portions. Each of the bridges 22a and 22b has a first depressed portion 16a, a second depressed portion 16b, and a non-depressed portion 24. In the rotor core 10, the first depressed portions 16a and the non-depressed portions 24 are alternately laminated. The non-depressed portions 24 are demagnetized by heat treatment.

Description

  The present invention relates to a rotor core used in a rotating electrical machine and a method for manufacturing the same.

  Conventionally, various rotating electrical machines having an annular stator around a cylindrical rotor have been developed. When the rotating electrical machine 100 is applied to the compressor 102 as shown in FIG. 12, a stator 106 is disposed in a cylindrical pipe 104, and a rotor 108 is disposed therein. The compressor 102 is provided with a pipe 110 for supplying a refrigerant, a pipe 112 for discharging the refrigerant, a terminal 114 connected to the winding, and a compression mechanism (not shown). When the rotor 108 rotates, the refrigerant is sucked into the compression mechanism, compressed, and discharged.

  The rotor 108 includes a rotor core 118 in which the disk-shaped core sheets 116 shown in FIG. 13 are stacked, a magnet embedded in the magnet hole 120 formed in the rotor core 118, and a rotating shaft 122 attached to the center of the rotor core 118. The core sheet 116 is formed by stamping a magnetic steel sheet made of soft magnetic material.

  The surface of the core sheet 116 is coated with an insulating material to prevent eddy currents between the core sheets 116. Both ends of the magnet hole 120 do not reach the outer periphery of the core sheet 116, and a bridge 124 is formed between both ends of the magnet hole 120 and the outer periphery of the core sheet 116. The bridge 124 connects the inner part and the outer part of the core sheet 116 with respect to the magnet hole 120.

  The magnetic flux from the magnet includes not only effective magnetic flux to the stator 106 but also magnetic flux that adversely affects the rotation of the rotor 108. The magnetic flux that has this adverse effect becomes prominent at the bridge 124. It is necessary to reduce the magnetic flux passing through the bridge 124.

  Patent Document 1 below discloses a technique in which a non-magnetic paint containing a non-magnetic substance is applied to the bridge 124 of the rotor core 118 and heated. By this technique, the bridge 124 is demagnetized, and the magnetic flux passing through the bridge 124 can be reduced. Patent Document 2 also discloses that the rotor core 118 is heated to become non-magnetic, as in Patent Document 1.

  However, when heating is performed, the insulating material coated on the surface of the core sheet 116 is melted. The core sheets 116 are short-circuited, eddy current increases, and loss due to heat generation occurs.

JP 2003-304670 A JP 2010-93972 A

  An object of this invention is to provide the rotor core which can reduce the magnetic flux which passes through the bridge | bridging of a rotor core, and can also prevent the short circuit of core sheets, and its manufacturing method.

  The rotor core of the present invention is a rotor core made of an electromagnetic steel plate and laminated with a core sheet in which magnet holes are formed. The core sheet includes a bridge formed between an end of the magnet hole and the outer periphery of the core sheet, and a recess formed in the bridge. In the stacking direction of the core sheets, the positions of the recesses with respect to the magnet holes differ between adjacent core sheets, and the bridge is demagnetized by heat treatment.

  Since the bridge is demagnetized by heat treatment, it is difficult for magnetic flux to pass through. Since the positions of the recesses are different, insulation between the core sheets is maintained even if the insulating coating on the surface of the core sheet is melted.

  The position of the recess differs at both ends of each magnet hole. Since the position of the concave portion is shifted, positions other than the concave portion of the bridge do not overlap.

  Two recesses are formed in each bridge, and the recesses of each bridge are formed asymmetrically with respect to the center of the bridge. Since the shape of the recess is different and asymmetrical, portions other than the bridge do not overlap.

  In the stacking direction of the core sheets, a portion overlaps at a portion other than the concave portion of the bridge of the adjacent core sheet. Or the structure which does not overlap parts other than the recessed part of the bridge | bridging of an adjacent core sheet | seat in the lamination direction of the said core sheet | seat may be sufficient. There may be a portion that overlaps with a portion other than the concave portion, or there may be a portion that does not exist.

  The method for manufacturing a rotor core includes a step of preparing an electromagnetic steel plate, a step of forming a core sheet having magnet holes from the electromagnetic steel plate, and a step of laminating the core sheet. In the step of forming the core sheet, a bridge between the end portion of the magnet hole and the outer periphery of the core sheet and a recess are formed in the bridge, and in the step of laminating, adjacent core sheets in the stacking direction of the core sheets The position of the recess with respect to the magnet hole is made different. After the laminating step, there is provided a step of demagnetizing the bridge by performing a heat treatment with a heating means having distance attenuation.

  Lamination is performed so that the positions of the concave portions of the bridge are different, and the bridge is heat-treated. The bridge is demagnetized by the heat treatment. Even if the positions of the recesses are different and the coating of the core sheet is melted, there is no short circuit between the core sheets. Since a distance attenuating heating means is used, the heating is local.

  The heat treatment is a laser heat treatment. The laser is focused on the outer periphery of the bridge, and as it moves away from the focus, heating becomes impossible. Local heating.

  The irradiation direction of the laser is oblique with respect to the stacking direction of the core sheets. Laser irradiation from an oblique direction makes it difficult for the laser to reach the back of the recess. Depending on the angle of the laser, it is possible not to irradiate the laser into the back of the recess.

  In the step of forming the core sheet, the positions of the recesses are made different at both ends of the magnet hole, and in the step of stacking the core sheet, the core sheet is stacked while rotating at the magnetic pole pitch. By rotating the core sheet, the positions of the recesses are made different.

  In the step of forming the core sheet, two recesses are formed in each bridge, and the recesses of each bridge form a recess asymmetrically with respect to the center of the bridge, and in the step of laminating the core sheets, one surface of the core sheet You may laminate | stack so that each other and other surfaces may contact | connect. By turning the core sheet upside down, the positions of the recesses are made different.

  In the present invention, the core sheet is not short-circuited when the bridge is made nonmagnetic by heat treatment by stacking the recesses and the non-recesses in the bridge in order. Does not increase the eddy current and does not adversely affect the rotation of the rotor core.

  By using a distance attenuating heating means, only the bridge can be heated locally. The coatings at locations other than the bridge are not melted, and the insulation between the core sheets is maintained.

  Since the core sheet is laminated by rotating or turning it over, the core sheet to be manufactured is the same. Manufacturing is not complicated.

It is a figure which shows the rotor core in the case of rotating and laminating | stacking the core sheet | seat of this invention, (a) is a top surface end view, (b) is a side view. It is a figure which shows the lamination order of a core sheet. It is a figure which shows the relationship between a non-recessed part and the focus of a laser, (a) is a figure without a clearance gap between non-recessed parts, (b) is a figure which has a clearance gap between non-recessed parts. It is a figure which shows the laser irradiation position of a core sheet. It is a figure which shows the rotor core in the case of turning over and laminating | stacking the core sheet | seat of this invention, (a) is an upper surface end view, (b) is a side view. It is a figure which shows the lamination order of a core sheet. It is a figure which shows the core sheet | seat with which the magnet hole became linear form, (a) shows the core sheet | seat laminated | stacked by rotating, (b) is a figure which shows the core sheet | seat laminated | stacked inside out. It is the figure which irradiated the laser to the non-recessed part from the diagonal direction, (a) is a figure without a gap between non-recessed parts, (b) is a figure with a gap between non-recessed parts, (c) It is a figure which shows the relationship between the angle with respect to a center and a lamination direction. It is a figure which uses electromagnetic heating, (a) is a figure which shows the positional relationship of the core sheet | seat and heating means seen from upper direction, (b) is a figure which shows a heating position. It is a figure of the core sheet which forms one magnetic pole with a plurality of magnet holes. It is a figure which shows a 6 pole core sheet. It is a figure which shows the conventional compressor. It is a figure which shows the core sheet | seat of the conventional rotor core.

  The rotor core and the manufacturing method thereof according to the present invention will be described with reference to the drawings. The rotor core is used for a rotating electrical machine. The rotating electrical machine can be applied to a compressor or the like, as in the past. In the description of a plurality of embodiments, the same content as that described in one embodiment may be omitted in other embodiments.

  The rotor core 10 of the present invention shown in FIG. 1 is a laminate of core sheets 12. The core sheet 12 is a plate formed of a soft magnetic electromagnetic steel plate. Examples of the material of the electrical steel sheet include those in which about 4% of silicon is added to the weight of iron, and the amount of silicon added is appropriately changed. The thickness of the electrical steel sheet is about 0.2 to 1 mm, preferably about 0.35 to 0.5 mm.

  A core sheet 12 having a desired shape is formed by punching the electromagnetic steel sheet. By punching, the magnet holes 14a and 14b, the recesses 16a and 16b, the hole 18 for the rotating shaft, and the hole 20 for the shaft portion of the fixing member are also formed. The shape of the core sheet 12 is a shape in which each of the above portions is formed in a disk shape. The magnet holes 14a and 14b and the recess 16b are preferably formed simultaneously.

  The surface of the core sheet 12 is coated with an insulating material (not shown). When the core sheets 12 are stacked, the core sheets 12 are not short-circuited to prevent an increase in eddy current. In addition, an insulating material having various characteristics such as corrosion resistance, heat resistance, slipperiness, adhesion to the core sheet 12, punchability, weldability, and film flexibility is preferable. Examples of the insulating material include insulating materials such as organic materials and inorganic materials. As an example, a forsterite base layer having a phosphate layer laminated thereon may be mentioned.

  Magnet holes 14 a and 14 b are formed in the core sheet 12. Magnetic poles are formed in the rotor core 10 by the number of the magnet holes 14a and 14b. In FIG. 1, since four magnet holes 14a and 14b are formed, four magnetic poles are formed.

  The shape of the magnet holes 14a and 14b in FIG. 1 is a belt-like belt shape. The magnet holes 14a and 14b are formed at positions symmetrical with respect to the center of the hole 18 for the rotation shaft. Moreover, the shape of the magnet holes 14a and 14b formed in the core sheet 12 is the same. Even if the core sheet 12 is rotated and laminated, the magnet holes 14a and 14b can be matched. When the core sheet 12 is laminated, the positions of the magnet holes 14a and 14b are matched. The rotor core 10 is penetrated by the magnet holes 14 a and 14 b in the stacking direction of the core sheet 12.

  Magnets embedded in the magnet holes 14a and 14b are embedded in the magnet holes 14a and 14b by injection molding and magnetizing the magnet material. Further, permanent magnets having the same shape as the magnet holes 14a and 14b may be embedded in the magnet holes, and end plates may be disposed above and below the rotor core 10 so that the magnets do not come off. Instead of a permanent magnet, a magnet material may be injection molded into a mold and magnetized bonded magnet or sintered magnet may be manufactured separately.

  A magnet may not be embedded in the magnet holes 14a and 14b, but may be a rotor core that rotates with reluctance torque caused by magnetic flux generated in the stator core.

  Bridges 22a and 22b are formed between the ends of the magnet holes 14a and 14b and the outer periphery of the core sheet 12 so that the core sheet 12 is not divided into a plurality of parts. By the bridges 22a and 22b, the outer portion and the inner portion are connected to each other than the magnet holes 14a and 14b in the core sheet 12, and the core sheet 12 is integrated.

  Each bridge 22a, 22b includes a recess 16a, 16b. Each bridge 22a, 22b is provided with two recesses 16a, 16b, which are defined as a first recess 16a and a second recess 16b. The first recess 16a and the second recess 16b are arranged in the circumferential direction, but the positions of the openings are different. The 1st recessed part 16a has an opening in the outer peripheral part of the core sheet 12, and the 2nd recessed part 16b has an opening in the edge part of magnet hole 14a, 14b. Portions other than the recesses 16a and 16b in the bridges 22a and 22b are defined as non-recesses 24. The width of the non-recessed portion 24 is set to be approximately the same as the thickness of the core sheet 12 (magnetic steel plate) to ensure the strength of the non-recessed portion 24. Each of the recesses 16a and 16b has a square shape, but may have other shapes.

  There are two types of positional relationships between the first recess 16a and the second recess 16b in each bridge 22a, 22b. This is a case where the first concave portion 16a and the second concave portion 16b are arranged in the order of the first concave portion 16a and the second concave portion 16b in the clockwise direction on the outer periphery of the rotor core 12. A bridge disposed in the order of the first recess 16a and the second recess 16b is referred to as a first bridge 22a, and a bridge disposed in the order of the second recess 16b and the first recess 16a is referred to as a second bridge 22b.

  The positional relationship between the first recess 16a and the second recess 16b is different at the ends of the magnet holes 14a and 14b. In the core sheet 12 of FIG. 1, one end of the magnet holes 14a and 14b is a first bridge 22a, and the other end is a second bridge 22b. Further, in the clockwise direction on the outer periphery of the rotor core 12, the magnet holes provided in the order of the first bridge 22a and the second bridge 22b are provided in the order of the first magnet hole 14a, the second bridge 22b, and the first bridge 22a. Let the magnet hole be the second magnet hole 14b. In the core sheet 12 of FIG. 1, the first magnet holes 14 a and the second magnet holes 14 b are alternately arranged clockwise around the outer periphery of the rotor core 12.

  When the core sheet 12 is laminated and the rotor core 10 is formed by combining the positional relationship between the first recess 16a and the second recess 16b, the first recess 16a and the non-recess 24 are sequentially stacked. For example, FIGS. 2B and 2D show a state in which the core sheet 12 of FIG. 2A is rotated. The core sheets 12 in the states of (a), (b), (c), and (d) of FIG. 2 are laminated in that order.

  Further, in the outer peripheral portion of the rotor core 12, the non-concave portions 24 are not overlapped and stacked. Therefore, the circumferential length of the opening of the first recess 16a is set to be half or more in the circumferential direction of the bridges 22a and 22b. The first recess 16a and the second recess 16b have different sizes and are asymmetric with respect to the centers of the bridges 22a and 22b. The opening of the first recess 16a is larger than the opening of the second recess 16b. The second recess 16b and the non-recess 24 are also laminated in order.

  As shown in FIG. 3, in the back 26 of the first recess 16a, the non-recesses 24 may or may not be overlapped. When a part of the non-recesses 24 is overlapped, the magnet material does not leak when the magnet material is injection molded. Even if there is a gap, it does not leak due to the viscosity of the magnet material. When the magnet material is injection molded, depending on the viscosity of the magnet material, the size of the second recess 16b, etc., the magnet material may flow into the second recess 16b to form a magnet.

  The non-recessed portions 24 of the bridges 22a and 22b are made nonmagnetic by heat treatment. The non-recessed portion 24 in the outer peripheral portion of the core sheet 12 is made non-magnetic. Demagnetization from the outer periphery of the core sheet 12 to the second recess 16b is equivalent to forming a flux barrier from the outer periphery of the core sheet 12 to the magnet holes 14a and 14b. That is, the bridges 22a and 22b are equivalent to the flux barrier, and the magnetic flux is difficult to pass.

  For demagnetization, a heating means having distance attenuation is used. For example, a laser irradiation device 28 is used. The focal point of the laser 30 is set to the outer peripheral portion of the bridges 22a and 22b. As the distance from the outer peripheral portions of the bridges 22a and 22b increases, heating becomes difficult. By demagnetizing the bridges 22a and 22b, the magnetic flux passing through the bridges 22a and 22b can be reduced.

  In the rotor core 10, the rotation shaft is fitted into the hole 18 for the rotation shaft and fixed. Since the circular rotation shaft hole 18 is formed at the center of the core sheet 12, the position of the rotation shaft hole 18 does not change even when the core sheet 12 is rotated and stacked. Since the rotation shaft hole 18 penetrates the rotor core 10 in a straight line, the rotation shaft can be fitted and fixed.

  The shaft portion of the fixing member is disposed in the hole 20 for the shaft portion of the fixing member. The fixing member is a fastening member having a shaft portion such as a rivet, a bolt and a nut, and a head portion. When the core sheets 12 are laminated, the positions of the shaft hole 20 match. The core sheets 12 are fixed to each other by the fixing member. Further, caulking is formed on the core sheet 12, and the core sheets 12 are also fixed by caulking.

  A rotor is formed by embedding a magnet in the rotor core 10 and attaching a rotating shaft and a fixed member. A rotor is arrange | positioned inside the cyclic | annular stator provided with the coil, and a rotary electric machine is comprised by a rotor and a stator.

  Next, a method for manufacturing the rotor core 10 will be described. (1) An electromagnetic steel sheet of soft magnetic material is prepared. The surface of the electrical steel sheet is coated with an insulating material.

  (2) The magnetic steel sheet is punched with a mold to form a core sheet 12 having a predetermined shape. The order of forming the outer shape of the core sheet 12 including the first recess 16a, the magnet holes 14a and 14b, the second recess 16b, the hole 18 for the rotation shaft, the hole 20 for the shaft portion of the fixing member, and the like is arbitrary. A plurality of portions may be formed at the same time. By punching, the cross section of the core sheet 12 is not coated with an insulating material. When the core sheet 12 is formed, caulking is also formed on the core sheet 12.

  (3) A predetermined number of core sheets 12 are laminated. When stacking, the magnet holes 14a and 14b, the hole 18 for the rotating shaft, and the hole 20 for the shaft portion of the fixing member are made to coincide. Further, the first recesses 16a and the non-recesses 24 are alternately arranged in the stacking direction. Therefore, the core sheet 12 is laminated by rotating in the circumferential direction.

  For example, in the case of the core sheet 10 of FIGS. 1 and 2, the first magnet holes 14a and the second magnet holes 14b are alternately formed in the circumferential direction. When all the core sheets 12 face the same direction, the core sheets 12 are rotated and stacked. The first bridges 22a and the second bridges 22b are alternately stacked, and the first recesses 14a and the non-recesses 24 are alternately stacked.

  In order to laminate as described above, it is assumed that all core sheets 10 before lamination are oriented in the direction of FIG. When the core sheet 12 is rotated by 90 ° as shown in FIGS. 2B and 2D when stacking in the order of FIGS. 2A to 2D, the first recesses 16a and the non-recesses 24 are alternately formed. Laminated to line up. That is, all the core sheets 12 face the same direction before lamination, and the core sheets 12 are laminated by alternately rotating and non-rotating the core sheets 12. When rotated, a certain magnet hole 14a, 14b is made to come to the position of magnet hole 14a, 14b adjacent in the circumferential direction.

  (4) The non-recessed portions 24 of the bridges 22a and 22b of the laminated core sheet 12 are heat-treated with a distance attenuating heating device, and the non-recessed portions 24 of the bridges 22a and 22b are made nonmagnetic. As shown in FIG. 3, the heat treatment is performed using a laser irradiation device 28. A lens or the like is used so that the focal point of the laser 30 becomes the non-recessed portion 24 on the outer periphery of the core sheet 12. The surface of the non-recessed portion 24 of the core sheet 12 is heated and heat is transmitted. The temperature of the non-recessed portion 24 for demagnetization is, for example, about 800 ° C. or higher, preferably about 1200 ° C. or higher.

  Parts other than the first recess 16a are not focused by the laser 30. As the distance from the focal point of the laser 30 increases, the energy for heating is also attenuated.

  The laser irradiation device 28 is moved in the stacking direction of the core sheet 12. Since the relative position of the laser irradiation device 28 and the laminated core sheet 12 only needs to move, the laminated core sheet 12 may move, or both may move. The number of times of laser irradiation to each bridge 22a, 22b is not limited. The laser irradiation device 28 may be reciprocated multiple times.

  When laser irradiation is completed with respect to one row of bridges 22a and 22b arranged in the stacking direction, the core sheet 12 stacked with respect to the laser irradiation device 28 is rotated relative to the other bridges 22a and 22b. Irradiate. For example, as shown in FIG. 4, the focal point of the laser 30 moves in a linear position 32 and is made non-magnetic.

  The number of laser irradiation devices 28 is not limited to one, and a plurality of non-concave portions 24 may be irradiated with laser from a plurality of laser irradiation devices 28 simultaneously.

  Since the 1st recessed part 16a and the non-recessed part 24 are piled up in order, even if the insulating material which coats the surface of the non-recessed part 24 fuse | melts, between the core sheets 12 is not short-circuited. An increase in eddy current can be prevented. Further, even if the laser 30 reaches the back 26 of the first recess 16a, the laser beam 30 is not in focus, so the back 26 of the first recess 16a is not heated. Accordingly, a part of the bridges 22a and 22b is made non-magnetic so that the magnetic flux does not easily pass, and the magnetic flux that adversely affects the rotation of the rotor can be reduced.

  Before the magnets are embedded in the magnet holes 14a and 14b, the heat treatment (4) is completed. This is to prevent the magnet from being deteriorated by heat.

  As described above, according to the present invention, the bridges 22a and 22b can be made non-magnetic without short-circuiting between the core sheets 12. The bridges 22a and 22b are constituted by recesses 16a and 16b and non-recessed non-recesses 24, and are the same as forming a flux barrier from the ends of the magnet holes 14a and 14b to the outer periphery of the core sheet 12. The magnetic flux between the bridges 22a and 22b is reduced, and the magnetic flux between the core sheets 12 is not generated. The rotational performance of the rotor in the rotating electrical machine can be enhanced.

  Further, when the non-recesses 24 of the bridges 22a and 22b are made non-magnetic, the non-recesses 24 and the first recesses 16a are arranged in order, so that even if the insulating material melts, no short circuit occurs between the core sheets 12. Although the temperature of the outer peripheral part of bridge | bridging 22a, 22b becomes the highest, temperature becomes small as it leaves | separates. It is difficult to melt the insulating material other than the non-concave portions 24 of the bridges 22a and 22b. The insulation between the core sheets 12 can be maintained even in portions other than the bridges 22a and 22b.

  Furthermore, the core sheets 12 to be laminated all have the same shape, and electromagnetic steel sheets can be punched with the same mold. Therefore, the manufacture of the core sheet 12 is the same as the conventional one and does not become complicated. When the core sheets 12 are laminated, the number of steps for rotating the core sheets 12 is increased, and the process is not so complicated as compared with the conventional case.

  In Example 1, although there was the presence or absence of rotation of the core sheet 12, in order for the 1st recessed part 16a and the non-recessed part 24 to become an order, it is not limited to the method. Instead of grasping and rotating the core sheet 12 as in the first embodiment, there is a method of rotating a pedestal of the core sheet 12 during lamination. Assume that all the core sheets 12 face the direction of FIG. Each time the core sheets 12 are stacked, the cradle is rotated. The core sheet 12 to be laminated and the laminated core sheet 12 are relatively rotated and laminated as shown in FIG.

  In addition, it is assumed that the core sheets 12 before lamination are all directed in the same direction, but may be in the direction in which they are laminated. For example, when the core sheet 12 is formed from an electromagnetic steel sheet, the mold is rotated each time one core sheet 12 is punched with the mold. When the core sheet 12 is punched, the core sheet 12 is rotated as shown in FIG. There is no need to rotate the core sheet 12 during lamination.

  As described above, until the core sheet 12 is laminated, the core sheet 12 to be laminated next is rotated relative to the last laminated core sheet 12 in the circumferential direction. The 1st recessed part 16a and the non-recessed part 24 can be arranged in order in the lamination direction like FIG.1 (b). In addition, in order to rotate the remaining core sheets 12, the first core sheet 12 is disposed at a predetermined position in a reference direction.

  In Example 1, the same core sheet 12 is rotated and laminated, but the core sheet 12 may be turned over and laminated. For example, as in the core sheet 12 of the rotor core 10 in FIG. 5, it is assumed that the positional relationship between the first recess 16 a and the second recess 16 b is the same in each bridge 22 b. In the core sheet 12 of FIG. 5, the second bridge 22b of FIG. 1 is formed at the end of each magnet hole 14c, but only the first bridge 22a may be used.

  Similarly to Example 1, when the core sheet 12 is laminated, the first concave portions 16a and the non-concave portions 24 of the bridge 22b are laminated so as to be alternated. Therefore, the core sheet 12 before lamination is directed in the same direction, and the case where the core sheet 12 is laminated as it is and the case where the core sheet 12 is turned over and laminated are alternately performed. In addition, it is the same as Example 1 to laminate | stack so that the magnet hole 14c etc. may correspond.

  For example, it is assumed that the core sheets 12 are laminated in the order of FIGS. 6 (a), (b), (c), and (d). If FIG. 6A is a table of the core sheet 12, the core sheet 12 is turned upside down and laminated in FIGS. 6B and 6D. The core sheet 12 is laminated so that one surface and the other surface thereof are in contact with each other.

  Similar to the first embodiment, the first recess 16a and the non-recess 24 are sequentially stacked in the stacking direction. When heat treatment is performed on the non-concave portion 24 of the bridge 22b, no short circuit occurs between the adjacent core sheets 12, and no eddy current occurs between the core sheets 12. Since all the core sheets 12 have the same shape, they can be manufactured with the same mold, and manufacturing is not complicated as compared with the conventional case.

  In each of the above-described embodiments, the magnet holes 14a, 14b, and 14c are in the shape of a circular arc, but are not limited to the core sheet 12 having the circular arc-shaped magnet holes 14a, 14b, and 14c. The linear magnet hole 14d may be used as shown in FIG. A flux barrier 34 is formed from both ends of the magnet hole toward the outer periphery of the core sheet 12. A bridge 22 is formed between the end of the flux barrier 34 and the outer periphery of the core sheet 12. The bridge 22 is provided with a first recess 16a and a second recess 16b similar to those in the above embodiment.

  The lamination of the core sheet 12 may be performed while rotating the core sheet 12 as in the above-described embodiment, or may be turned over. By any method, the 1st recessed part 16a and the non-recessed part 24 are laminated | stacked alternately.

  Laser irradiation is not limited to the case where the irradiation is performed from a direction perpendicular to the stacking direction. As shown in FIG. 8, the laser 30 is irradiated from an oblique direction with respect to the stacking direction. The laser 30 is focused on the non-recessed portion 24 on the outer periphery of the core sheet 12. As the direction of the laser 30 approaches the stacking direction, the laser 30 becomes difficult to reach the back 26 of the first recess 16a.

  For example, as shown in FIG. 8C, the thickness of the core sheet 12 is t, the length from the opening of the first recess 16a to the back 26 is d, and the angle of the laser 30 is θ. When determining the angle of the laser 30, assuming that the laser 30 is irradiated obliquely from above in the laminating direction, the angle of the lower portion 30 a of the laser 30 with respect to the vertical direction in the laminating direction is set at the outer portion of the core sheet 12. The angle is 30. If tan θ> t / d, the laser 30 is shielded by the non-recessed portion 24 and does not reach the depth 26 of the first recessed portion 16a. It is difficult to heat the non-recessed portion 24 that forms the back 26 of the first recessed portion 16a. As described above, it is preferable that the direction of the laser 30 is inclined and light is shielded by the non-concave portion 24 to be focused. When the laser 30 is irradiated from obliquely below in the stacking direction, the lower portion 30a of the laser 30 is changed to the upper portion 30b.

  Although the laser irradiation device 28 is used as a distance attenuating heating device, other devices may be used. For example, a device that performs electromagnetic heating using the coil 36 as shown in FIG. By passing a current through the coil 36, a magnetic flux is generated around the coil 36. This magnetic flux causes an eddy current to flow through the core sheet 12 to heat the core sheet 12. At this time, the magnetic flux attenuates as the distance from the coil 12 increases. Therefore, by making the coil 12 face the non-recessed portion 24, it is possible to heat only the non-recessed portion 24 and suppress the temperature rise of other portions. As shown in FIG. 9B, the coil 12 moves through the linear position 38, and only the non-recessed portion 24 is heated.

  Furthermore, heating using TIG (Tungsten Inert Gas) welding, plasma arc welding, electron beam, or the like may be used as a heating device.

  Although the core sheet 12 having one magnet hole 14a, 14b for one magnetic pole is used, the core sheet 12 may form one magnetic pole by the plurality of magnet holes 14a, 14b. For example, the core sheet 12 of FIG. 10 forms one magnetic pole by three magnet holes 14a and 14b. Recesses 16a and 16b are provided for the respective magnet holes 14a and 14b.

  Further, the number of magnet holes 14a, 14b, 14c in one core sheet 12 is not limited to four, but may be other numbers. In order to make the number of N poles and S poles equal, the magnet holes 14a, 14b, 14c are even numbers. For example, a core sheet 12 having six magnet holes 14e and 14f as shown in FIG. Even in the six magnet holes 14e and 14f, the bridges 22a and 22b have the first recess 16a and the second recess 16b. When the core sheets 12 are stacked, the core sheets 12 are rotated or turned over so that the first recesses 16a and the non-recesses 24 are stacked in order.

  When the core sheet 12 before lamination is rotated relative to the last laminated core sheet 12, the rotation angle when the six magnet holes 14e and 14f of FIG. 11 are provided is 60 °. Moreover, the relative rotation angle of the core sheet 12 in the case where the number of the magnet holes 14a, 14b, 14c is four as in the first embodiment is 90 °. Considering that one magnetic pole is formed by a plurality of magnet holes 14a and 14b as shown in FIG. 10, in general, a value obtained by dividing 360 ° by the number of magnetic poles when the rotor is formed is a relative rotation angle. Since this angle coincides with the magnetic pole pitch, when the core sheet 12 is relatively rotated, the core sheet 12 is relatively rotated at the magnetic pole pitch.

  Although the rotor core 10 of the inner rotor has been described, the present invention can be applied to the rotor core of the outer rotor. A flux barrier is formed from the end of the magnet hole of the rotor core toward the inner peripheral surface. A bridge is formed between the end of the flux barrier and the inner peripheral surface of the rotor core, and a first recess and a second recess are formed in the bridge. As in the other embodiments, the first recess and the non-recess are stacked in order.

  In each of the above embodiments, the first recesses 16a and the non-recesses 24 are alternately arranged in the stacking direction. However, a plurality of the first recesses 16a may be arranged, or a plurality of the non-recesses 24 may be arranged. By arranging a plurality of non-recesses 24, an eddy current flows in the core sheet 12 therebetween, but the eddy current does not become too large because of the first recess 16a in the middle.

  In addition, the present invention can be carried out in a mode in which various improvements, modifications, and changes are added based on the knowledge of those skilled in the art without departing from the spirit of the present invention. Each embodiment is not an independent or exclusive embodiment, and may be implemented by appropriately combining all or a part of various embodiments.

10: Rotor core 12: Core sheets 14a, 14b, 14c, 14e, 14f: Magnet holes 16a, 16b: Recess 18: Hole for rotating shaft 20: Hole 22a, 22b for shaft portion of fixing member: Bridge 24: Non-recess 26: depth of first recess 28: laser irradiation device 30: laser 32: position where the laser irradiation device moves 34: flux barrier 36: coil 38: position where the coil moves

Claims (13)

A rotor core made of an electromagnetic steel plate and laminated with a core sheet in which magnet holes are formed,
In the core sheet, a bridge formed between the end of the magnet hole and the outer periphery of the core sheet,
A recess formed in the bridge;
With
In the stacking direction of the core sheet, the position of the recess with respect to the magnet hole is different,
A rotor core in which the bridge is demagnetized by heat treatment. The rotor core according to claim 1, wherein a concave portion and a non-concave portion of the bridge are arranged in order in the stacking direction of the core sheets. The rotor core according to claim 1 or 2, wherein the position of the recess is different at both ends of each magnet hole. The rotor core according to claim 1 or 2, wherein two recesses are formed in each bridge, and the recesses of each bridge are formed asymmetrically with respect to the center of the bridge. The rotor core according to any one of claims 1 to 4, wherein a part of the core sheet overlaps with a portion other than a concave portion of a bridge of adjacent core sheets in the stacking direction of the core sheets. 5. The rotor core according to claim 1, wherein portions other than the concave portions of the bridges of adjacent core sheets do not overlap in the stacking direction of the core sheets. Preparing a magnetic steel sheet;
Forming a core sheet having magnet holes from the electromagnetic steel sheet;
Laminating the core sheet;
A rotor core manufacturing method comprising:
In the step of forming the core sheet, a bridge between the end of the magnet hole and the outer periphery of the core sheet and a recess in the bridge are formed,
In the laminating step, in the laminating direction of the core sheet, the position of the recess with respect to the magnet hole is changed,
A method for manufacturing a rotor core, comprising a step of demagnetizing the bridge by performing a heat treatment with a heating unit having distance attenuation on the bridge after the laminating step. The method of manufacturing a rotor core according to claim 7, wherein the laminating step and the non-recessing portion of the bridge are sequentially arranged in the laminating direction of the core sheet by the laminating step. The method for manufacturing a rotor core according to claim 7 or 8, wherein the heat treatment is a heat treatment by laser. The method for manufacturing a rotor core according to claim 9, wherein an irradiation direction of the laser is an oblique direction with respect to a stacking direction of the core sheets. The method for manufacturing a rotor core according to claim 10, wherein the laser is irradiated at an angle that does not allow the laser to reach the back of the recess. The method for manufacturing a rotor core according to any one of claims 7 to 11, wherein in the step of laminating the core sheets, the core sheets oriented in the same direction are laminated while rotating at a magnetic pole pitch. The manufacturing of a rotor core according to any one of claims 7 to 11, wherein, in the step of laminating the core sheets, the core sheets facing in the same direction are laminated so that one side and the other side of the core sheets are in contact with each other depending on whether the core sheets are turned over. Method.

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