Stator core, method of manufacturing rotor core, method of manufacturing stator core, stator, and motor

Abstract

To provide a method of manufacturing a stator core and a rotor core, a method of manufacturing a stator core, a stator, a stator, and a motor, capable of improving yield and suppressing reduction in average torque output from the motor.SOLUTION: In a method for manufacturing a stator core and a rotor core, an electromagnetic steel sheet 5 is punched into a shape of a first portion 2 6 and a rotor core 3 1 which does not include at least each tip portion 2 5 of a plurality of teeth 2 4 of the stator core 2 1, the first portion 2 6 and the rotor core 3 1 are formed, and a second portion 2 7 which does not include the first portion 2 6 of the stator core 2 1 is joined to the first portion 2 6. The stator core 21 is formed of an electromagnetic steel sheet, and includes a first portion 26 that does not include at least the tip portion 25 of each of the plurality of teeth 24 of the stator core 21, and a second portion 27 that is joined to the first portion 26 and does not include the first portion 26 of the stator core 21.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to a method for manufacturing a stator core and a rotor core, a method for manufacturing a stator core, a stator, and a motor. [Background technology]

[0002] Conventionally, stator cores and rotor cores for motors made of laminated electromagnetic steel sheets have been known (see, for example, Patent Document 1). Stator cores and rotor cores made of laminated electromagnetic steel sheets are manufactured by punching laminated steel sheets into the shape of the stator core and rotor core, and then stacking the punched laminated steel sheets. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2022-069087 Summary of the Invention [Problem to be solved by the invention]

[0004] In the manufacture of stator cores and rotor cores, punching a single electromagnetic steel sheet into the shape of the stator core and rotor core increases yield. If the gap between the stator core and rotor core is small, it is not possible to punch a single electromagnetic steel sheet into the shape of the stator core and rotor core. For this reason, when punching a single electromagnetic steel sheet into the shape of the stator core and rotor core, it is necessary to increase the gap between the stator core and rotor core. However, if the gap between the stator core and rotor core is large, a problem occurs in that the average torque output from the motor decreases.

[0005] The present disclosure aims to provide a method for manufacturing a stator core and a rotor core that can increase yield and suppress a decrease in average torque output from a motor, a method for manufacturing a stator core, a stator, and a motor. [Means for solving the problem]

[0006] [1] The manufacturing method of a stator core and a rotor core according to the present disclosure is a manufacturing method of a stator core and a rotor core in which a plurality of teeth extend from a back yoke toward the inside of the back yoke, and includes a forming process of punching an electromagnetic steel sheet into the shape of a first portion of the stator core and the rotor core that does not include the tip portions of at least a plurality of teeth, to form the first portion and the rotor core, and a joining process of joining a second portion of the stator core that does not include the first portion to the first portion.

[0007] In this method for manufacturing a stator core and a rotor core, an electromagnetic steel sheet is punched into the shape of a first portion of the stator core and a rotor core that does not include the tip portions of at least a plurality of teeth of the stator core, and a second portion of the stator core that does not include the first portion is joined to the first portion. Therefore, even if the gap between the first portion and the rotor core is increased when the electromagnetic steel sheet is punched into the shape of the first portion and the rotor core, the gap between the stator core and the rotor core can be reduced by joining the second portion to the formed first portion. This increases yield and prevents a decrease in the average torque output from the motor.

[0008] [2] In the manufacturing method of the stator core and the rotor core described in [1], the second portion may be formed from a green compact obtained by pressing soft magnetic powder coated with an insulating material. In this manufacturing method of the stator core and the rotor core, since the second portion is formed from a green compact obtained by pressing soft magnetic powder coated with an insulating material, the motor characteristics can be changed more easily than when the entire stator core is made of electromagnetic steel sheets, and the second portion can be manufactured more easily.

[0009] [3] In the manufacturing method of the stator core and the rotor core according to [1] or [2], the forming step may include a punching step of punching an electromagnetic steel sheet into the shape of the first portion and the rotor core, a first lamination step of laminating a plurality of electromagnetic steel sheets punched from the electromagnetic steel sheet and corresponding to the shape of the first portion to form the first portion, and a second lamination step of laminating a plurality of electromagnetic steel sheets punched from the electromagnetic steel sheet and corresponding to the shape of the rotor core to form the rotor core. In this manufacturing method of the stator core and the rotor core, the electromagnetic steel sheet is punched into the shape of the first portion and the rotor core, the first portion is formed by laminating a plurality of electromagnetic steel sheets punched from the electromagnetic steel sheet and corresponding to the shape of the first portion, and the rotor core is formed by laminating a plurality of electromagnetic steel sheets punched from the electromagnetic steel sheet and corresponding to the shape of the rotor core. Therefore, even if the thickness of the electromagnetic steel sheet is thinner than the thickness of the first portion and the rotor core, the first portion and the rotor core can be formed.

[0010] [4] The method for manufacturing a stator core according to the present disclosure is a method for manufacturing a stator core having a plurality of teeth extending from a back yoke toward the inside of the back yoke, and includes a forming process for forming the first portion by punching an electromagnetic steel sheet into the shape of a first portion that does not include the tip portions of at least a plurality of teeth of the stator core, and a joining process for joining a second portion of the stator core that does not include the first portion to the first portion.

[0011] In this method of manufacturing a stator core, an electromagnetic steel sheet is punched into the shape of a first portion of the stator core that does not include the tip portions of at least a plurality of teeth to form the first portion, and a second portion of the stator core that does not include the first portion is joined to the first portion. Therefore, even if the gap between the first portion and the rotor core is increased when the electromagnetic steel sheet is punched into the shape of the first portion and the rotor core, the gap between the stator core and the rotor core can be reduced by joining the second portion to the formed first portion. This increases yield and prevents a decrease in the average torque output from the motor.

[0012] [5] In the method for manufacturing a stator core described in [4], the second portion may be formed from a green compact obtained by pressing soft magnetic powder coated with an insulating material. In this method for manufacturing a stator core, the second portion is formed from a green compact obtained by pressing soft magnetic powder coated with an insulating material. This makes it possible to change the motor characteristics more easily than when the entire stator core is made of electromagnetic steel sheets, and also makes it easier to manufacture the second portion.

[0013] [6] In the method for manufacturing a stator core according to [4] or [5], the forming step may include a punching step of punching an electromagnetic steel sheet into the shape of the first portion, and a lamination step of forming the first portion by stacking a plurality of electromagnetic steel sheets punched from the electromagnetic steel sheet and corresponding to the shape of the first portion. In this method for manufacturing a stator core, the electromagnetic steel sheet is punched into the shape of the first portion and the rotor core, and the first portion is formed by stacking a plurality of electromagnetic steel sheets punched from the electromagnetic steel sheet and corresponding to the shape of the first portion. Therefore, even if the thickness of the electromagnetic steel sheet is thinner than the thickness of the first portion, the first portion can be formed.

[0014] [7] The stator core according to the present disclosure is a stator core having a plurality of teeth extending from a back yoke toward the inside of the back yoke, and is formed from electromagnetic steel sheets and includes a first portion that does not include the tip portions of at least the plurality of teeth of the stator core, and a second portion that is joined to the first portion and does not include the first portion of the stator core.

[0015] In this stator core, a first portion formed from an electromagnetic steel sheet and not including the tip portions of at least a plurality of teeth of the stator core is joined to a second portion of the stator core that does not include the first portion. Therefore, during manufacturing of the stator core, the electromagnetic steel sheet is punched into the shape of the first portion, which is a portion of the stator core, rather than the shape of the entire stator core. Therefore, even if the electromagnetic steel sheet is punched into the shape of the first portion and the rotor core with a large gap between the first portion and the rotor core, the gap between the stator core and the rotor core can be narrowed by joining the second portion to the formed first portion. This increases manufacturing yield and prevents a decrease in the average torque output from the motor.

[0016] [8] In the stator core described in [7], the second portion may be formed from a green compact obtained by pressing soft magnetic powder coated with an insulating material. In this stator core, the second portion is formed from a green compact obtained by pressing soft magnetic powder coated with an insulating material. Because the second portion is formed from a green compact obtained by pressing soft magnetic powder coated with an insulating material, the motor characteristics can be changed and the second portion can be manufactured more easily than when the entire stator core is formed from electromagnetic steel sheets.

[0017] [9] In the stator core described in [8], the second portion may not include a back yoke. In this stator core, since the second portion does not include a back yoke, a decrease in the average torque output from the motor can be suppressed.

[0018]

[10] In the stator core described in [9], the plurality of teeth may be separated from one another, and the second portion may be divided into a plurality of segments provided corresponding to the tip ends of the plurality of teeth. In this stator core, the plurality of teeth are separated from one another, and the second portion is divided into a plurality of segments provided corresponding to the tip ends of the plurality of teeth, making it easy to manufacture the second portion.

[0019]

[11] In the stator core described in [9], tip portions of each of the plurality of teeth may be connected to each other, and the second portion may be formed into a ring shape by the tip portions of each of the plurality of connected teeth. In this stator core, tip portions of each of the plurality of teeth may be connected to each other, and the second portion may be formed into a ring shape by the tip portions of each of the plurality of connected teeth, which makes it possible to reduce the number of parts during manufacturing and to suppress rattle during operation.

[0020]

[12] In the stator core according to any one of [8] to

[11] , the ratio of the area of ​​the second portion to the area of ​​the first portion when viewed in the thickness direction of the stator core may be 8% or less. In this stator core, the ratio of the area of ​​the second portion to the area of ​​the first portion when viewed in the thickness direction of the stator core is 8% or less, so that a sufficient average torque can be output from the motor.

[0021]

[13] In the stator core according to any one of [8] to

[11] , the ratio of the area of ​​the second portion to the area of ​​the first portion when viewed in the thickness direction of the stator core may be 2% or more. In this stator core, the ratio of the area of ​​the second portion to the area of ​​the first portion when viewed in the thickness direction of the stator core is 2% or more, which can reduce iron loss of the motor and improve motor efficiency.

[0022]

[14] A stator according to the present disclosure is a stator for a motor, comprising the stator core according to any one of [7] to

[13] and a winding wound around each of a plurality of teeth of the stator core. Because this stator comprises the stator core described above, it is possible to increase the yield during manufacturing and suppress a decrease in the average torque output from the motor.

[0023]

[15] A motor according to the present disclosure includes the stator described in

[14] and a rotor disposed inside the stator so as to be rotatable relative to the stator. Because this motor includes the stator described above, it is possible to increase the manufacturing yield and suppress a decrease in the average torque output from the motor. [Effects of the Invention]

[0024] According to the present disclosure, it is possible to increase yield and suppress a decrease in the average torque output from the motor. [Brief explanation of the drawings]

[0025] [Figure 1] FIG. 1 is a schematic cross-sectional view showing a motor according to a first embodiment. [Figure 2] FIG. 2 is a schematic diagram showing a stator core according to the first embodiment. [Figure 3] FIG. 3 is a plan view illustrating the method of manufacturing the stator core and the motor core according to the first embodiment. [Figure 4] FIG. 4 is a plan view illustrating a method for manufacturing the stator core and the motor core according to the first embodiment. [Figure 5] FIG. 5 is a plan view illustrating a method for manufacturing the stator core and the motor core according to the first embodiment. [Figure 6] FIG. 6 is a schematic cross-sectional view showing a motor according to the second embodiment. [Figure 7] FIG. 7 is a schematic diagram showing a stator core according to the second embodiment. [Figure 8] FIG. 8 is a plan view illustrating a method for manufacturing a stator core and a motor core according to the second embodiment. [Figure 9] FIG. 9 is a plan view illustrating a method for manufacturing a stator core and a motor core according to the second embodiment. [Figure 10] FIG. 10 is a plan view for explaining a manufacturing method of a stator core and a motor core according to the second embodiment. [Figure 11]FIG. 6 is a graph showing the average torque of Comparative Example 1, Example 1, and Comparative Example 2. [Figure 12] FIG. 12 is a graph showing the yields of Comparative Example 1, Example 1, and Comparative Example 2. [Figure 13] FIG. 13 is a graph showing the relationship between the area ratio of the second portion and the average torque in the stator core according to the first embodiment. [Figure 14] FIG. 14 is a graph showing the relationship between the area ratio of the second portion and iron loss in the stator core according to the first embodiment. [Figure 15] FIG. 15 is a graph showing the relationship between the area ratio of the second portion and the efficiency in the stator core according to the first embodiment. [Figure 16] FIG. 16 is a graph showing the relationship between the area ratio of the second portion and the average torque in the stator core according to the second embodiment. [Figure 17] FIG. 17 is a graph showing the relationship between the area ratio of the second portion and iron loss in the stator core according to the second embodiment. [Figure 18] FIG. 18 is a graph showing the relationship between the area ratio of the second portion and the efficiency in the stator core according to the second embodiment. [Figure 19] FIG. 19 is a graph showing the relationship between time and average torque in the motor according to the first embodiment and the motor according to the second embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0026] Preferred embodiments of the present disclosure will be described in detail below with reference to the drawings. In the drawings, identical or corresponding parts are designated by the same reference numerals, and duplicate explanations will be omitted. Also, in the drawings, dimensional proportions and the like have been appropriately changed to make the explanation easier to understand.

[0027] (First embodiment) [Motor] Fig. 1 is a schematic cross-sectional view showing a motor according to a first embodiment. As shown in Fig. 1, the motor 1 according to the first embodiment is a radial gap motor, and includes a stator 2, a rotor 3 arranged rotatably relative to the stator 2, and a shaft 4 fixed to the rotor 3. The stator 2 is arranged outside the rotor 3 and spaced apart from the rotor 3 in the radial direction of the shaft 4. The shaft 4 is inserted into a shaft hole formed in the center of the rotor 3.

[0028] [Stator] The stator 2 according to the first embodiment is a stator of the motor 1. The stator 2 includes a stator core 21 and windings 22 wound around the stator core 21. The stator core 21 is the portion of the stator 2 excluding the windings 22, and is also called a motor core or a core.

[0029] [Stator core] FIG. 2 is a schematic diagram showing a stator core according to the first embodiment. As shown in FIGS. 1 and 2, the stator core 21 according to the first embodiment includes an annular back yoke 23 and a plurality of teeth 24 extending from the back yoke 23. The drawings show, as an example, a case in which the stator core 21 includes 24 teeth 24. The drawings also show imaginary boundaries between the back yoke 23 and the plurality of teeth 24 with dashed lines. The back yoke 23 is also referred to as a yoke or the like. Here, the radial direction of the back yoke 23 is referred to as the radial direction D. The radial direction D is also the radial direction of the annulus formed by the back yoke 23 (the radial direction of the rotor 3 in the motor 1).

[0030] Each of the teeth 24 extends radially inward from the back yoke 23 in the radial direction D. The portion of each of the teeth 24 located at the inner tip of the tooth 24 in the radial direction D is called a tip portion 25. The teeth 24 are separated from one another. The winding 22 is wound around each of the teeth 24.

[0031] The stator core 21 is formed by joining a first portion 26 and a second portion 27 together.

[0032] The first portion 26 is a portion of the stator core 21 that does not include tip portions 25 of at least the plurality of teeth 24. The second portion 27 is a portion of the stator core 21 that does not include the first portion 26. In other words, the second portion 27 is a portion of the stator core 21 that includes tip portions 25 of at least the plurality of teeth 24, but does not include the first portion 26.

[0033] The second portion 27 may include, for example, only the tip portion 25 of each of the plurality of teeth 24, or may be a portion of each of the plurality of teeth 24 including the tip portion 25 of each of the plurality of teeth 24, or may be the entirety of each of the plurality of teeth 24, or may include the entirety of the plurality of teeth 24 and a portion of the back yoke 23. Note that except in the case where the second portion 27 includes the entirety of the plurality of teeth 24 and a portion of the back yoke 23, the second portion 27 does not include a portion of the back yoke 23.

[0034] In the first embodiment, since the multiple teeth 24 are separated from one another, when the second portion 27 does not include a part of the back yoke 23, the second portion 27 is divided into multiple divided bodies 28 provided corresponding to the tip portions 25 of the multiple teeth 24. In other words, the second portion 27 is made up of the multiple divided bodies 28. The drawings show a case where the second portion 27 is a part of each of the multiple teeth 24 including the tip portions 25 of the multiple teeth 24, and the second portion 27 is made up of the multiple divided bodies 28.

[0035] The first portion 26 is formed of an electromagnetic steel plate. More specifically, the first portion 26 is formed of a plurality of electromagnetic steel plates stacked in the thickness direction of the stator core 21. That is, the first portion 26 is formed of a laminated steel plate in which a plurality of electromagnetic steel plates are stacked. The thickness direction of the stator core 21 is the direction of the central axis of the stator core 21 and also the direction of the rotational axis of the rotor 3 and the shaft 4. The second portion 27 is formed of a green compact obtained by pressing soft magnetic powder coated with an insulating material. The second portion 27 can be molded, for example, using a commercially available powder compacting device. The soft magnetic powder material is, for example, pure iron, iron-silicon, or iron-cobalt. The average particle size of the soft magnetic powder is, for example, 3 μm to 300 μm, 30 μm to 200 μm, or 50 μm to 150 μm. The insulating material is, for example, an insulating coating containing phosphoric acid, silicone, or the like. The average particle size of the soft magnetic powder is measured using a robot shifter (model number: RPS-205) manufactured by Seishin Enterprise Co., Ltd.

[0036] [Rotor] The rotor 3 according to the first embodiment is a rotor of the motor 1. The rotor 3 includes a rotor core 31 and permanent magnets 32 fixed to the rotor core 31. The rotor core 31 is formed of electromagnetic steel plates. More specifically, the rotor core 31 is formed of a plurality of electromagnetic steel plates stacked in the thickness direction of the rotor core 31. In other words, the rotor core 31 is formed of a laminated steel plate in which a plurality of electromagnetic steel plates are stacked. The thickness direction of the rotor core 31 is the direction of the central axis of the rotor core 31 and also the direction of the rotational axis of the rotor 3 and the shaft 4.

[0037] [Method for manufacturing stator core and rotor core (method for manufacturing stator core)] Next, a method for manufacturing the stator core and rotor core according to the first embodiment (a method for manufacturing the stator core) will be described with reference to Figures 3 to 5. This manufacturing method is a method for manufacturing the above-described stator core 21 and rotor core 31. Figures 3 to 5 are plan views for explaining the method for manufacturing the stator core and motor core according to the first embodiment.

[0038] The manufacturing method of the stator core and the rotor core includes an electromagnetic steel sheet preparation step, a forming step, a second portion preparation step, and a joining step.

[0039] As shown in FIG. 3, in the electromagnetic steel sheet preparation step, an electromagnetic steel sheet 5 larger than the outer shape of the stator core 21 when viewed in the thickness direction of the stator core 21 is prepared.

[0040] 3 and 4, in the forming process, the electromagnetic steel sheet 5 is punched into the shape of the first portion 26 and the rotor core 31 to form the first portion 26 and the rotor core 31. The forming process is performed after the electromagnetic steel sheet preparation process. The forming process includes a punching process, a first lamination process, and a second lamination process.

[0041] In the punching process, the electromagnetic steel sheet 5 is punched out into the shapes of the first portion 26 and the rotor core 31. In the punching process, the electromagnetic steel sheet 5 is punched out so that the position for punching out the shape of the rotor core 31 is inside the position for punching out the shape of the first portion 26. In this way, by punching out the electromagnetic steel sheet 5 once, the electromagnetic steel sheet 51 corresponding to the shape of the first portion 26 and the electromagnetic steel sheet 52 corresponding to the shape of the rotor core 31 are obtained.

[0042] In the first lamination process, a first portion 26 having a predetermined thickness is formed by stacking a plurality of electromagnetic steel sheets 51. The first lamination process is performed after the punching process. In the first lamination process, a plurality of electromagnetic steel sheets 51 are stacked so that the thickness of the stacked plurality of electromagnetic steel sheets 51 is the same as the thickness of the first portion 26. This results in the first portion 26 having a predetermined thickness, formed from a laminated steel sheet in which a plurality of electromagnetic steel sheets are stacked. Note that if the thickness of the electromagnetic steel sheets 5 is the same as the thickness of the first portion 26, the first lamination process does not need to be performed. If the thickness of the electromagnetic steel sheets 5 is the same as the thickness of the first portion 26, the first portion 26 is formed by punching the electromagnetic steel sheets 5 into the shape of the first portion 26 in the punching process. In other words, the electromagnetic steel sheets 51 obtained by punching the electromagnetic steel sheets 5 in the punching process become the first portion 26.

[0043] In the second lamination process, a rotor core 31 having a predetermined thickness is formed by stacking multiple electromagnetic steel sheets 52. The second lamination process is performed after the punching process. The second lamination process may be performed before the first lamination process, after the first lamination process, or simultaneously with the first lamination process. In the second lamination process, multiple electromagnetic steel sheets 52 are stacked so that the thickness of the stacked multiple electromagnetic steel sheets 52 is the same as the thickness of the rotor core 31. This results in a rotor core 31 having a predetermined thickness formed from a laminated steel sheet in which multiple electromagnetic steel sheets are stacked. Note that if the thickness of the electromagnetic steel sheets 5 is the same as the thickness of the rotor core 31, the second lamination process does not need to be performed. If the thickness of the electromagnetic steel sheets 5 is the same as the thickness of the rotor core 31, the rotor core 31 is formed by punching the electromagnetic steel sheets 5 into the shape of the rotor core 31 in the punching process. In other words, the electromagnetic steel sheets 52 obtained by punching the electromagnetic steel sheets 5 in the punching process become the rotor core 31.

[0044] As shown in FIG. 5 , in the second portion preparation step, the second portion 27 is prepared. The second portion preparation step is performed before the joining step. The second portion preparation step may be performed, for example, after the forming step, before the forming step, before the electromagnetic steel sheet preparation step, or simultaneously with any of these steps. In the second portion preparation step, the soft magnetic powder coated with an insulating material is pressed to form the second portion 27 of a green compact. This results in the second portion 27 formed from the green compact. Note that the second portion preparation step may simply involve preparing the second portion 27 formed from a green compact that has been manufactured in advance.

[0045] 5 and 2, in the joining process, the second portion 27 is joined to the first portion 26. The joining process is performed after all of the above processes, and in the joining process, the second portion 27 is joined to the first portion 26 by, for example, welding, bonding, fitting, press fitting, shrink fitting, or the like. In this way, the stator core 21 is obtained.

[0046] As described above, in the manufacturing method of the stator core and rotor core according to the first embodiment, the electromagnetic steel sheet 5 is punched into the shape of the first portion 26 and the rotor core 31, which do not include the tip portions 25 of at least the plurality of teeth 24 of the stator core 21, to form the first portion 26 and the rotor core 31, and the second portion 27 of the stator core 21, which does not include the first portion 26, is joined to the first portion 26. Therefore, even if the gap between the first portion 26 and the rotor core 31 is increased when the electromagnetic steel sheet 5 is punched into the shape of the first portion 26 and the rotor core 31, the gap between the stator core 21 and the rotor core 31 can be reduced by joining the second portion 27 to the formed first portion 26. This increases the yield and suppresses a decrease in the average torque output from the motor 1.

[0047] Furthermore, in this manufacturing method of the stator core and rotor core, the second portion 27 is formed from a compact obtained by pressing soft magnetic powder coated with an insulating material, so that the characteristics of the motor 1 can be changed and the second portion 27 can be manufactured easily compared to when the entire stator core is formed from an electromagnetic steel plate.

[0048] Furthermore, in this method of manufacturing a stator core and a rotor core, electromagnetic steel sheet 5 is punched out to the shape of first portion 26 and rotor core 31, multiple electromagnetic steel sheets 51 punched out from electromagnetic steel sheet 5 and corresponding to the shape of first portion 26 are stacked to form first portion 26, and multiple electromagnetic steel sheets 52 punched out from electromagnetic steel sheet 5 and corresponding to the shape of rotor core 31 are stacked to form rotor core 31.Therefore, even if the thickness of electromagnetic steel sheet 5 is thinner than the thickness of first portion 26 and rotor core 31, first portion 26 and rotor core 31 can be formed.

[0049] In the method for manufacturing a stator core according to the first embodiment, electromagnetic steel sheets 5 are punched into the shape of a first portion 26 that does not include tip portions 25 of at least a plurality of teeth 24 of stator core 21 to form first portion 26, and a second portion 27 of stator core 21 that does not include first portion 26 is joined to first portion 26. Therefore, even if the gap between first portion 26 and rotor core 31 is increased when electromagnetic steel sheets 5 are punched into the shapes of first portion 26 and rotor core 31, joining second portion 27 to the formed first portion 26 makes it possible to reduce the gap between stator core 21 and rotor core 31. This increases yield and suppresses a decrease in the average torque output from motor 1.

[0050] Furthermore, in this method of manufacturing the stator core, the second portion 27 is formed from a compact obtained by pressing soft magnetic powder coated with an insulating material, so that the characteristics of the motor 1 can be changed and the second portion 27 can be manufactured more easily than when the entire stator core is formed from an electromagnetic steel plate.

[0051] Furthermore, in this method of manufacturing a stator core, electromagnetic steel sheet 5 is punched out into the shape of first portion 26 and rotor core 31, and multiple electromagnetic steel sheets 51 punched out from electromagnetic steel sheet 5 and corresponding to the shape of first portion 26 are stacked to form first portion 26, so that first portion 26 can be formed even when the thickness of electromagnetic steel sheet 5 is thinner than the thickness of first portion 26.

[0052] In the stator core 21 according to the first embodiment, a first portion 26 formed from an electromagnetic steel sheet and not including tip portions 25 of at least a plurality of teeth 24 of the stator core 21 is joined to a second portion 27 of the stator core 21 not including the first portion 26. Therefore, during manufacturing of the stator core 21, the electromagnetic steel sheet 5 is punched into the shape of the first portion 26, which is a part of the stator core 21, rather than the shape of the entire stator core 21. Therefore, even if the gap between the first portion 26 and the rotor core 31 is increased and the electromagnetic steel sheet 5 is punched into the shape of the first portion 26 and the rotor core 31, the gap between the stator core 21 and the rotor core 31 can be reduced by joining the second portion 27 to the formed first portion 26. This increases the yield during manufacturing and suppresses a decrease in the average torque output from the motor 1.

[0053] Furthermore, in this stator core 21, the second portion 27 is formed from a compact obtained by pressing soft magnetic powder coated with an insulating material, so that the characteristics of the motor 1 can be changed and the second portion 27 can be manufactured more easily than when the entire stator core is formed from an electromagnetic steel plate.

[0054] Furthermore, in this stator core 21, the second portion 27 does not include a back yoke, so that a decrease in the average torque output from the motor 1 can be suppressed.

[0055] Furthermore, in this stator core 21, the multiple teeth 24 are separated from one another, and the second portion 27 is divided into multiple segments 28 that correspond to the respective tip portions 25 of the multiple teeth 24, so that the second portion 27 can be easily manufactured.

[0056] The stator 2 according to the first embodiment includes the above-described stator core 21, and therefore, the yield rate during manufacturing can be increased and the decrease in the average torque output from the motor 1 can be suppressed.

[0057] The motor 1 according to the first embodiment includes the stator 2 described above, and therefore the yield during manufacturing can be increased and the decrease in the average torque output from the motor 1 can be suppressed.

[0058] Second Embodiment Next, a second embodiment will be described. The second embodiment is basically the same as the first embodiment, but differs from the first embodiment in that the tip portions of the multiple teeth are connected to each other. Therefore, only the differences from the first embodiment will be described below, and a description of the similarities between the first embodiment and the second embodiment will be omitted.

[0059] [Motor] Fig. 6 is a schematic cross-sectional view showing a motor according to a second embodiment. As shown in Fig. 6, the motor 1A according to the second embodiment differs from the motor 1A according to the first embodiment only in that the stator core 21 of the first embodiment is replaced with a stator core 21A.

[0060] [Stator core] Fig. 7 is a schematic diagram showing a stator core according to the second embodiment. As shown in Fig. 6 and Fig. 7, the stator core 21A according to the second embodiment differs from the stator core 21A according to the first embodiment only in that the plurality of teeth 24 of the stator 2 according to the first embodiment are replaced by the plurality of teeth 24A of the stator 2A, and the first portion 26 and the second portion 27 according to the first embodiment are replaced by the first portion 26A and the second portion 27A.

[0061] Each of the teeth 24A extends radially inward from the back yoke 23 in the radial direction D. The tip end portion of each of the teeth 24A on the inner side in the radial direction D is referred to as a tip end portion 25A. The tip end portions 25A of the teeth 24A are connected to one another. In other words, the teeth 24A are not separated from one another and are connected to one another at the tip end portions 25.

[0062] The first portion 26A is a portion of the stator core 21A that does not include tip portions 25 of at least the plurality of teeth 24. The second portion 27A is a portion of the stator core 21A that does not include the first portion 26A. In other words, the second portion 27A is a portion of the stator core 21A that includes tip portions 25 of at least the plurality of teeth 24, but does not include the first portion 26A. In the second embodiment, the tip portions 25 of the plurality of teeth 24A are connected to each other, and therefore the second portion 27A is formed into a ring shape by the tip portions 25A of the plurality of connected teeth 24A.

[0063] The first portion 26A is formed of an electromagnetic steel plate, similar to the first portion 26 of the first embodiment. The second portion 27A is formed of a green compact obtained by pressing soft magnetic powder coated with an insulating material, similar to the second portion 27 of the first embodiment.

[0064] [Method for manufacturing stator core and rotor core (method for manufacturing stator core)] Next, a method for manufacturing a stator core and a rotor core according to the second embodiment (a method for manufacturing a stator core) will be described with reference to Figures 8 to 10. This manufacturing method is a method for manufacturing the above-described stator core 21A and rotor core 31 or stator core 21A. Figures 8 to 10 are plan views for explaining the method for manufacturing a stator core and a motor core according to the second embodiment.

[0065] The manufacturing method of the stator core and the rotor core includes an electromagnetic steel sheet preparation step, a forming step, a second portion preparation step, and a joining step.

[0066] As shown in FIG. 8, in the electromagnetic steel sheet preparing step, electromagnetic steel sheets 5 larger than the outer shape of stator core 21A when viewed in the thickness direction A of stator core 21 are prepared.

[0067] 8 and 9, in the forming process, the electromagnetic steel sheet 5 is punched into the shape of the first portion 26A and the rotor core 31 to form the first portion 26A and the rotor core 31. The forming process is performed after the electromagnetic steel sheet preparation process. The forming process includes a punching process, a first lamination process, and a second lamination process.

[0068] In the punching process, electromagnetic steel sheet 5 is punched out into the shapes of first portion 26A and rotor core 31. In the punching process, electromagnetic steel sheet 5 is punched out so that the position for punching out the shape of rotor core 31 is inside the position for punching out the shape of first portion 26A. In this way, by punching electromagnetic steel sheet 5 once, electromagnetic steel sheet 51A corresponding to the shape of first portion 26A and electromagnetic steel sheet 52 corresponding to the shape of rotor core 31 are obtained.

[0069] In the first lamination step, a plurality of electromagnetic steel sheets 51A are stacked to form a first portion 26 having a predetermined thickness. The first lamination step is performed after the punching step. In the first lamination step, a plurality of electromagnetic steel sheets 51A are stacked so that the thickness of the stacked plurality of electromagnetic steel sheets 51A is the same as the thickness of first portion 26A. This results in a first portion 26A having a predetermined thickness formed from a laminated steel sheet in which a plurality of electromagnetic steel sheets are stacked. Note that if the thickness of electromagnetic steel sheet 51A is the same as the thickness of first portion 26A, the first lamination step does not need to be performed.

[0070] In the second lamination step, similar to the first embodiment, a rotor core 31 of a predetermined thickness is formed by stacking a plurality of electromagnetic steel sheets 52. The second lamination step is performed after the punching step. This results in a rotor core 31 of a predetermined thickness formed from a laminated steel sheet in which a plurality of electromagnetic steel sheets are stacked. Note that if the thickness of the electromagnetic steel sheets 52 is the same as the thickness of the rotor core 31, the second lamination step does not need to be performed.

[0071] As shown in FIG. 10 , in the second portion preparation step, the second portion 27A is prepared. The second portion preparation step is performed before the joining step. In the second portion preparation step, the soft magnetic powder coated with an insulating material is pressed to form the second portion 27A of the green compact. In this way, the second portion 27A formed from the green compact is obtained. Note that the second portion preparation step may simply involve preparing the second portion 27A formed from a green compact that has been manufactured in advance.

[0072] 10 and 7, in the joining step, the second portion 27A is joined to the first portion 26A, thereby obtaining the stator core 21A.

[0073] As described above, in the stator core 21A according to the second embodiment, the tip portions 25A of the multiple teeth 24A are connected to each other, and the second portion 27A is formed in a ring shape by the tip portions 25A of the multiple teeth 24A that are connected to each other, thereby reducing the number of parts used during manufacturing and suppressing rattling during operation.

[0074] Here, the average torque output and the yield rate during production were analyzed using the motors of Comparative Example 1, Example 1, and Comparative Example 2 as models. The analysis results are shown in FIGS.

[0075] As shown in Table 1, the motor of Comparative Example 1 had 4 poles, 24 slots, a stator core thickness of 60 mm, 35 turns of winding, a current of 4 A, an outer diameter of the stator of φ176 mm, an inner diameter of the rotor of φ86.4 mm, an air gap between the stator core and rotor core of 0.5 mm, a stator core made of a laminated steel plate consisting of multiple layers of electromagnetic steel sheets (non-oriented electromagnetic steel strip, 35JN210, manufactured by JFE Steel Corporation), a rotor made of a laminated steel plate consisting of multiple layers of electromagnetic steel sheets (non-oriented electromagnetic steel strip, 35JN210, manufactured by JFE Steel Corporation), and a neodymium magnet (NdFeB, 1.4T) as a permanent magnet.

[0076] [Table 1]

[0077] As shown in Table 1, the motor of Example 1 was configured under the same conditions as the motor of Comparative Example 1, with a first portion of the stator core, excluding at least the tip portions of the plurality of teeth, being a laminated steel plate made of a plurality of electromagnetic steel sheets (non-oriented electromagnetic steel strip, 35JN210, manufactured by JFE Steel Corporation), a second portion of the stator core, excluding the first portion, being a powder magnetic core (REC4X, manufactured by Resonac Corporation), and the back yoke and the plurality of teeth being joined. The second portion was a portion of each of the plurality of teeth.

[0078] As shown in Table 1, the motor of Comparative Example 2 was made under the same conditions as the motor of Comparative Example 1, except that the air gap between the stator core and the rotor core was set to 1.0 mm.

[0079] FIG. 11 is a graph showing the average torque of Comparative Example 1, Example 1, and Comparative Example 2. FIG. 12 is a graph showing the yield of Comparative Example 1, Example 1, and Comparative Example 2. As shown in FIGS. 11 and 12, Example 1, in which the air gap between the stator core and the rotor core was 0.5 mm, had a significantly higher average torque output from the motor than Comparative Example 2, in which the air gap between the stator core and the rotor core was 1.0 mm. Furthermore, Example 1, in which the air gap between the stator core and the rotor core was 0.5 mm, had a similar average torque output from the motor to Comparative Example 1, in which the air gap between the stator core and the rotor core was 0.5 mm, but the yield was significantly higher than Comparative Example 2, in which the air gap between the stator core and the rotor core was 1.0 mm. These results demonstrate that by using powder magnetic cores for multiple teeth, the yield can be significantly increased while maintaining the average torque.

[0080] Next, in the motor 1 according to the first embodiment and the motor 1A according to the second embodiment, the ratio of the area of ​​the second portion 27 to the area of ​​the first portion 26 as viewed in the thickness direction of the stator core 21 was changed, and the average torque, efficiency, and iron loss were analyzed. The ratio of the area of ​​the second portion 27 to the area of ​​the first portion 26 is referred to as the area ratio of the second portion. The analysis results for the motor 1 according to the first embodiment are shown in Figs. 13 to 15, and the analysis results for the motor 1A according to the second embodiment are shown in Figs. 16 to 18.

[0081] Fig. 13 is a graph showing the relationship between the area ratio of the second portion and the average torque in the stator core according to the first embodiment. In Fig. 13, the standard value is indicated by a dashed line. The standard value is set to 97%, which is 3% less than the average torque when the stator core is made entirely of electromagnetic steel sheets, which is 100%.

[0082] Fig. 14 is a graph showing the relationship between the area ratio of the second portion and iron loss in the stator core according to the first embodiment. Fig. 15 is a graph showing the relationship between the area ratio of the second portion and efficiency in the stator core according to the first embodiment. As shown in Figs. 14 and 15, when the area ratio of the second portion was 8% or less, the iron loss of the motor 1 was reduced and the efficiency of the motor 1 was improved.

[0083] Fig. 16 is a graph showing the relationship between the area ratio of the second portion and the average torque in the stator core according to the second embodiment. In Fig. 16, the standard value is indicated by a dashed line. As shown in Fig. 16, when the area ratio of the second portion 27A was 2% or more, the efficiency of the motor 1A exceeded the standard value.

[0084] Fig. 17 is a graph showing the relationship between the area ratio of the second portion and iron loss in the stator core according to the second embodiment. Fig. 18 is a graph showing the relationship between the area ratio of the second portion and efficiency in the stator core according to the second embodiment. As shown in Figs. 17 and 18, when the area ratio of the second portion 27A was 8% or less, the iron loss of the motor 1A was reduced and the efficiency of the motor 1A was improved.

[0085] In light of this result, from the viewpoint of outputting sufficient average torque from the motor 1, 1A, the ratio of the area of ​​the second portions 27, 27A to the area of ​​the first portions 26, 26A, as viewed in the thickness direction of the stator core 21, 21A, may be 8% or less. Furthermore, from the viewpoint of reducing iron loss in the motor 1, 1A and improving the efficiency of the motor 1, 1A, the ratio of the area of ​​the second portions 27, 27A to the area of ​​the first portions 26, 26A, as viewed in the thickness direction of the stator core 21, 21A, may be 2% or more. Furthermore, from these viewpoints, the ratio of the area of ​​the second portions 27, 27A to the area of ​​the first portions 26, 26A, as viewed in the thickness direction of the stator core 21, 21A, may be 2% or more and 8% or less.

[0086] Next, the relationship between time and average torque when the motor 1 according to the first embodiment and the motor 1A according to the second embodiment were operated at 960 Hz was analyzed.

[0087] 19 is a graph showing the relationship between time and average torque in the motor according to the first embodiment and the motor according to the second embodiment. As shown in FIG. 19, the motor 1A according to the second embodiment exhibits significantly reduced fluctuations (wobble) in average torque over time compared to the motor 1 according to the first embodiment. From this result, it can be inferred that the tip portions of the multiple teeth are connected to each other, and the second portion is formed into a ring shape by the tip portions of the multiple connected teeth, thereby suppressing wobble during operation. [Explanation of symbols]

[0088] 1...motor, 1A...motor, 2...stator, 2A...stator, 3...rotor, 4...shaft, 5...electromagnetic steel sheet, 21...stator core, 21A...stator core, 22...winding, 23...back yoke, 24...teeth, 24A...teeth, 25...tip portion, 25A...tip portion, 26...first portion, 26A...first portion, 27...second portion, 27A...second portion, 28...segment, 31...rotor core, 32...permanent magnet, 51...electromagnetic steel sheet, 51A...electromagnetic steel sheet, 52...electromagnetic steel sheet, D...radial direction

Claims

1. A method for manufacturing a stator core and a rotor core, in which a plurality of teeth extend from a back yoke toward an inside of the back yoke, the method comprising: a forming step of punching out an electromagnetic steel sheet into the shape of a first portion of the stator core that does not include tip portions of each of the plurality of teeth and the rotor core, thereby forming the first portion and the rotor core; a joining step of joining a second portion of the stator core, which does not include the first portion, to the first portion. A method for manufacturing a stator core and a rotor core.

2. the second portion is formed of a green compact obtained by pressing soft magnetic powder coated with an insulating material, The method for manufacturing the stator core and rotor core according to claim 1 .

3. The forming step includes: a punching process of punching the electromagnetic steel sheet into the shape of the first portion and the rotor core; a first lamination step of laminating a plurality of electromagnetic steel sheets punched out from the electromagnetic steel sheet and corresponding to the shape of the first portion to form the first portion; a second lamination step of laminating a plurality of magnetic steel sheets punched out from the magnetic steel sheets and corresponding to the shape of the rotor core to form the rotor core, The method for manufacturing a stator core and a rotor core according to claim 1 or 2.

4. A method for manufacturing a stator core in which a plurality of teeth extend from a back yoke toward an inside of the back yoke, a forming step of punching an electromagnetic steel sheet into a shape of a first portion of the stator core that does not include tip portions of at least the plurality of teeth of the stator core, thereby forming the first portion; a joining step of joining a second portion of the stator core, which does not include the first portion, to the first portion. A method for manufacturing a stator core.

5. the second portion is formed of a green compact obtained by pressing soft magnetic powder coated with an insulating material, The method for manufacturing a stator core according to claim 4 .

6. The forming step includes: a punching step of punching the electromagnetic steel sheet into the shape of the first portion; and a lamination step of laminating a plurality of electromagnetic steel sheets punched out from the electromagnetic steel sheet and corresponding to the shape of the first portion to form the first portion. The method for manufacturing a stator core according to claim 4 or 5.

7. A stator core having a plurality of teeth extending from a back yoke toward the inside of the back yoke, a first portion of the stator core formed of an electromagnetic steel plate and excluding at least tip portions of the plurality of teeth; a second portion of the stator core that is joined to the first portion and does not include the first portion, Stator core.

8. the second portion is formed of a green compact obtained by pressing soft magnetic powder coated with an insulating material, The stator core according to claim 7 .

9. The second portion does not include the back yoke. The stator core according to claim 8 .

10. The plurality of teeth are separated from one another, The second portion is divided into a plurality of segments provided corresponding to the tip portions of the plurality of teeth, The stator core according to claim 9 .

11. The tip portions of the plurality of teeth are connected to each other, The second portion is formed in a ring shape by the tip portions of the plurality of teeth connected to each other. The stator core according to claim 9 .

12. a ratio of an area of ​​the second portion to an area of ​​the first portion when viewed in a thickness direction of the stator core is 8% or less; The stator core according to claim 8 .

13. a ratio of an area of ​​the second portion to an area of ​​the first portion when viewed in a thickness direction of the stator core is 2% or more; The stator core according to claim 8 .

14. A stator of a motor, A stator core according to any one of claims 7 to 13; a winding wound around each of the plurality of teeth of the stator core, Stator.

15. A stator according to claim 14; a rotor disposed inside the stator and rotatable relative to the stator, Motor.

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