Stacked core and method for manufacturing a stacked core

Abstract

To improve magnetic properties in a laminated core.SOLUTION: In a laminated core formed by laminating a plurality of electrical steel sheets 40 having an insulating coating 3, at least one of the plurality of electrical steel sheets 40, which includes an electrical steel sheet 40 located at the end of the first side D1 in the stacking direction, or one of the plurality of electrical steel sheets 40, which includes an electrical steel sheet 40 located at the end of the second side D2 in the stacking direction, forms a first laminated steel sheet 51 in which the tooth portions of the electromagnetic steel sheets 40 adjacent to each other in the stacking direction are bonded to each other, and in the tooth portions of the first laminated steel sheet 51, insulating coatings 3 of the electrical steel sheets 40 are adhered to each other.SELECTED DRAWING: Figure 2

Description

Technical Field

[0004]

[0001] The present invention relates to a laminated core and a method for manufacturing the laminated core.

Background Art

[0002] Conventionally, it has been known to form a laminated core by laminating and fixing two or more electromagnetic steel sheets by adhesion. Generally, when two adjacent electromagnetic steel sheets in the lamination direction are adhered with an adhesive, the adhesive shrinks during curing, and compressive stress is applied to the electromagnetic steel sheet. When compressive stress is applied, distortion occurs in the electromagnetic steel sheet. In this case, depending on the position where the adhesion is performed, there is a risk that the magnetic characteristics of the laminated core may deteriorate. In the technique of adhering and laminating electromagnetic steel sheets using an adhesive, considering the adverse effects of the above compressive stress, the techniques described in Patent Documents 1 and 2 below, in which the adhesive is applied and adhered only to specific parts, are known. In addition, insulated electromagnetic steel sheets described in Patent Documents 3 and 4 below, which are provided with an insulating film that can be adhered (has adhesion ability) by heating and / or pressurization, are known.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Patent Document 3

Patent Document 4

Summary of the Invention

Problems to be Solved by the Invention

[0004] As described above, while limiting the bonding area by applying adhesive only to specific parts is effective in avoiding unintended distortion, its effectiveness in laminated cores formed by bonding electrical steel sheets with adhesive insulating coatings by heating and / or pressurizing remains unclear. When using electrical steel sheets with insulating coatings that can be bonded by heating and / or pressurizing (having adhesive properties), there is a need to provide an optimal coating configuration and manufacturing method that improves the characteristics of the laminated core. The inventors of this application have found that when this type of insulating coated electrical steel sheet is applied to a laminated core having a core back portion (yoke portion) and a teeth portion, the magnetic properties of the laminated core can be improved.

[0005] This invention has been made in view of the circumstances described above, and aims to improve the magnetic properties of a laminated core. [Means for solving the problem]

[0006] To solve the aforementioned problems, the present invention proposes the following means. (1) A laminated core according to one aspect of the present invention is a laminated core formed by laminating a plurality of electromagnetic steel sheets having an insulating coating, wherein each of the plurality of electromagnetic steel sheets comprises an annular core back portion and a plurality of teeth portions that protrude radially from the core back portion and are spaced apart in the circumferential direction of the core back portion, and at least one of the plurality of electromagnetic steel sheets, including an electromagnetic steel sheet located at the furthest end on the first side in the lamination direction and an electromagnetic steel sheet located at the furthest end on the second side in the lamination direction, forms a first laminated steel sheet in which the teeth portions of adjacent electromagnetic steel sheets in the lamination direction are bonded to each other, and the insulating coatings of each electromagnetic steel sheet are bonded to each other at the teeth portions of the first laminated steel sheet.

[0007] If the teeth of an electrical steel sheet located at the end of the lamination direction are not bonded, the teeth may lift up. In this case, the teeth of adjacent electrical steel sheets in the lamination direction may separate, potentially degrading the magnetic properties of the laminated core. In the laminated core according to this embodiment, at least one of the electromagnetic steel sheets, including the electromagnetic steel sheet located at the furthest end on the first side in the lamination direction, and the electromagnetic steel sheet, including the electromagnetic steel sheet located at the furthest end on the second side in the lamination direction, forms the first laminated steel sheet. In other words, the teeth portions of the electromagnetic steel sheets, including the electromagnetic steel sheet located at the furthest end on the first side in the lamination direction, and the electromagnetic steel sheet, including the electromagnetic steel sheet located at the furthest end on the second side in the lamination direction, are bonded together. Therefore, the lifting of the teeth portions can be suppressed at at least one of the first side end and the second side end in the lamination direction of the laminated core. Thus, the effect of the decrease in magnetic properties due to the lifting of the teeth portions can be suppressed. Furthermore, the lifting of the teeth is controlled by adhesive bonding rather than crimping or welding. In the case of crimping, mechanical stress is generated, and in the case of welding, thermal stress is generated. These mechanical and thermal stresses affect the magnetic properties more than the effects of strain. In addition, in both the case of crimping and welding, there is a risk that the magnetic properties of the electromagnetic steel sheet will deteriorate due to interlayer short circuits. Therefore, by controlling the lifting of the teeth through adhesive bonding, the impact of the deterioration of magnetic properties can be suppressed. Furthermore, in the laminated core according to this embodiment, the electromagnetic steel sheets forming the first laminated steel sheet are bonded together by the integration and homogenization of the insulating coatings covering the surfaces of adjacent electromagnetic steel sheets in the lamination direction. In other words, the electromagnetic steel sheets are not bonded together by an adhesive provided separately from the electromagnetic steel sheets. When electromagnetic steel sheets are bonded together by an adhesive, the adhesive is placed between adjacent electromagnetic steel sheets, causing them to be separated by the thickness of the adhesive. This reduces the space factor in the laminated core. Moreover, if the adhesive is not applied to the entire surface of adjacent electromagnetic steel sheets but is only partially bonded, the contact between adjacent electromagnetic steel sheets in the non-bonded area weakens. As a result, when the laminated core is assembled to a rotating electric machine and operates, the unintended vibrations in the non-bonded area increase, making the rotor rotation unstable and reducing the overall magnetic properties of the rotating electric machine. In contrast, as in the laminated core according to this embodiment, when adjacent electrical steel sheets in the lamination direction are bonded together by an insulating coating on the electrical steel sheets, the adjacent electrical steel sheets do not separate due to the adhesive as described above. Therefore, even when adjacent electrical steel sheets are partially bonded and non-bonded areas exist, a strong contact state between adjacent electrical steel sheets is achieved. As a result, the effect of reduced magnetic properties can be suppressed. Based on the above, it is possible to suppress both the effect of tooth lifting on the magnetic properties and the effect of adhesive placement on the magnetic properties. As a result, the magnetic properties of the laminated core can be improved.

[0008] (2) In the laminated core according to (1) above, a configuration may be adopted in which some of the plurality of electrical steel sheets form the first laminated steel sheet, and the remaining electrical steel sheets that do not form the first laminated steel sheet form a second laminated steel sheet in which the teeth portions of adjacent electrical steel sheets in the lamination direction are not bonded to each other.

[0009] In a laminated core, when adjacent electrical steel sheets are bonded together in the lamination direction, strain occurs in the bonded portion of the electrical steel sheet (base steel sheet). When strain occurs in the electrical steel sheet, the iron loss of the laminated core increases, and the magnetic properties of the laminated core deteriorate. In particular, the magnetic flux density in the teeth portion is higher than that in the core back portion. Therefore, the impact of the deterioration of magnetic properties due to strain is greater in the teeth portion. For this reason, it is preferable that the electrical steel sheets are not bonded together as much as possible in the teeth portion of the laminated core, to the extent that lifting can be suppressed. In the laminated core according to this embodiment, the teeth of the second laminated steel sheet are not bonded to each other. Therefore, the effect of the deterioration of magnetic properties due to the generation of strain in the second laminated steel sheet can be suppressed. Based on the above, it is possible to suppress both the effects of tooth lifting on magnetic properties and the effects of adhesive placement on magnetic properties, as well as the effects of strain on magnetic properties. As a result, the magnetic properties of the laminated core can be further improved.

[0010] (3) In the laminated core according to (2) above, a configuration may be adopted in which some of the plurality of electrical steel sheets, including the electrical steel sheet located at the furthest end on the first side in the lamination direction, and some of the electrical steel sheets, including the electrical steel sheet located at the furthest end on the second side in the lamination direction, both form the first laminated steel sheet, and the remaining electrical steel sheets located in the center of the plurality of electrical steel sheets in the lamination direction form the second laminated steel sheet.

[0011] In both a portion of the electrical steel sheets, including the one located at the furthest end on the first side in the lamination direction, and a portion of the electrical steel sheets, including the one located at the furthest end on the second side in the lamination direction, the teeth portions of adjacent electrical steel sheets in the lamination direction are bonded together. Therefore, lifting of the teeth portions can be suppressed at both the first end and the second end in the lamination direction of the laminated core. Thus, the effect of the decrease in magnetic properties due to the lifting of the teeth portions can be effectively suppressed.

[0012] (4) In the laminated core according to (3) above, a configuration may be adopted in which the number of electromagnetic steel sheets forming the second laminated steel sheet in the center in the lamination direction is equal to or greater than the number of electromagnetic steel sheets forming the first laminated steel sheet on the first side in the lamination direction, and equal to or greater than the number of electromagnetic steel sheets forming the first laminated steel sheet on the second side in the lamination direction.

[0013] The number of electromagnetic steel sheets forming the second laminated steel sheet in the center of the lamination direction (hereinafter referred to as number N3) is equal to or greater than the number of electromagnetic steel sheets forming the first laminated steel sheet on the first side of the lamination direction (hereinafter referred to as number N1), and also equal to or greater than the number of electromagnetic steel sheets forming the first laminated steel sheet on the second side of the lamination direction (hereinafter referred to as number N2). Therefore, the ratio of electromagnetic steel sheets to which the teeth are bonded can be reduced throughout the entire laminated core. As a result, the effect of the deterioration of the magnetic properties of the laminated core due to the generation of strain can be further suppressed.

[0014] (5) In the laminated core according to (3) or (4) above, a configuration may be adopted in which the number of electromagnetic steel sheets forming the first laminated steel sheet on the first side in the lamination direction, and the number of electromagnetic steel sheets forming the first laminated steel sheet on the second side in the lamination direction, are both 1 / 3 or less of the total number of the plurality of electromagnetic steel sheets.

[0015] The number of sheets N1 and N2 are both less than or equal to 1 / 3 of the total number of electrical steel sheets (hereinafter referred to as number N0). Therefore, the ratio of electrical steel sheets to which the teeth are bonded can be reduced in the entire laminated core. As a result, the effect of the deterioration of the magnetic properties of the laminated core due to the generation of strain can be further suppressed.

[0016] (6) In a laminated core relating to any one of the above items (3) to (5), a configuration may be adopted in which the number of electromagnetic steel sheets forming the first laminated steel sheet on the first side in the lamination direction is equal to the number of electromagnetic steel sheets forming the first laminated steel sheet on the second side in the lamination direction.

[0017] The number N1 and the number N2 are equal. Therefore, in the laminated core, it is possible to suppress the occurrence of a difference between the magnetic properties on the first side in the lamination direction and the magnetic properties on the second side. As a result, the handling property of the laminated core can be improved.

[0018] (7) In the laminated core according to (6) above, the number of electromagnetic steel sheets forming the first laminated steel sheet on the first side in the lamination direction and the number of electromagnetic steel sheets forming the first laminated steel sheet on the second side in the lamination direction may adopt a configuration in which they are equal to the number of electromagnetic steel sheets forming the second laminated steel sheet in the center in the lamination direction.

[0019] The number N1 and the number N2 are equal to the number N3. Therefore, in the process of manufacturing any part of the first laminated steel sheet on the first side, the first laminated steel sheet on the second side, and the second laminated steel sheet in the center, the same number of electromagnetic steel sheets may be stacked. As a result, further simplification of the manufacture of the laminated core can be achieved.

[0020] (8) In the laminated core according to (1) above, a configuration may be adopted in which all of the plurality of electromagnetic steel sheets form the first laminated steel sheet.

[0021] In all of the plurality of electromagnetic steel sheets, the teeth portions of the electromagnetic steel sheets adjacent to each other in the lamination direction are adhered to each other. Therefore, the influence of the decrease in magnetic properties due to the lifting of the teeth portion can be effectively suppressed.

[0022] (9) In the laminated core according to any one of (1) to (8) above, in the first laminated steel sheet, a configuration may be adopted in which the teeth portions of the electromagnetic steel sheets adjacent to each other in the lamination direction are not caulked to each other and are not welded.

[0023] In the first laminated steel sheet, the teeth portions of the electromagnetic steel sheets adjacent to each other in the lamination direction are not caulked to each other and are not welded. That is, instead of using caulking or welding in combination with adhesion, the lifting of the teeth portion is restricted only by adhesion. As a result, the influence of the decrease in magnetic properties due to the lifting of the teeth portion can be effectively suppressed.

[0024] (10) In a laminated core according to any one of the above items (1) to (9), a configuration may be adopted in which the teeth portions of the first laminated steel sheet are bonded together, with at least the portions of the teeth portions including the radial tip being bonded together.

[0025] Generally, at the ends of a laminated core in the stacking direction, the tips of the teeth are particularly prone to lifting. The radial tip of the teeth refers to the end of the teeth located radially opposite the core back. In the laminated core according to this embodiment, in the first laminated steel sheet, at least the tip portions of the teeth of adjacent electrical steel sheets in the lamination direction are bonded together. Therefore, the lifting of the teeth can be effectively suppressed. Moreover, by effectively suppressing lifting, the bonding area required to suppress lifting can be kept small. As a result, the effect of the deterioration of the magnetic properties of the laminated core due to the generation of strain can be further suppressed.

[0026] (11) In a laminated core relating to any one of the above items (1) to (10), a configuration may be adopted in which the core back portions of adjacent electrical steel sheets in the lamination direction are not bonded to each other in the first laminated steel sheet.

[0027] In the first laminated steel sheet, the core back portions of adjacent electrical steel sheets in the lamination direction are not bonded to each other. Therefore, the effect of strain on the magnetic properties of the laminated core can be further suppressed.

[0028] (12) In a laminated core relating to any one of the above items (1) to (11), the first laminated steel sheet may adopt a configuration in which some of the multiple sets of teeth in adjacent electrical steel sheets in the lamination direction are bonded to each other, while the remaining teeth are not bonded to each other.

[0029] In the first laminated steel sheet, some of the multiple sets of teeth in adjacent electrical steel sheets in the lamination direction are bonded to each other, while the remaining teeth are not bonded to each other. Therefore, it is possible to suppress lifting in some of the teeth while suppressing the generation of distortion in the remaining teeth.

[0030] (13) In the laminated core relating to any one of the above items (1) to (12), a configuration may be adopted in which the thickness of each of the plurality of electrical steel sheets is 0.10 mm or more and 0.30 mm or less.

[0031] Each of the multiple electrical steel sheets has a thickness of 0.10 mm to 0.30 mm. This allows for reduced iron loss while ensuring the manufacturing efficiency of the laminated core. In other words, when punching out electrical steel sheets from a base material, the thickness of the electrical steel sheet depends on the thickness of the base material, and the thickness of the base material is equal to the thickness of the electrical steel sheet. If the thickness of the electrical steel sheet is less than 0.10 mm, the thickness of the base material will also be less than 0.10 mm. In this case, when punching out electrical steel sheets from the base material, the number of punches required to achieve a predetermined stacking thickness increases, reducing the production efficiency of the laminated core. In addition, the packing factor, which is the proportion of electrical steel sheets (base steel sheets) in the laminated core, decreases, which may reduce the magnetic properties of the laminated core. On the other hand, if the thickness of the electrical steel sheet exceeds 0.30 mm, the sheet may be too thick, potentially increasing the iron loss in the laminated core. It is preferable that the thickness of the electrical steel sheet be 0.27 mm or less.

[0032] (14) A method for manufacturing a laminated core according to one aspect of the present invention is a method for manufacturing a laminated core according to any one of (1) to (13) above, comprising a first step of forming the first laminated steel sheet by heating the teeth portion of the laminated electromagnetic steel sheet to exhibit adhesive properties to the insulating coating.

[0033] In the first step, the teeth of the laminated electrical steel sheets are heated to allow the insulating coating to adhere, thereby bonding the teeth of adjacent electrical steel sheets in the lamination direction to form the first laminated steel sheet. Therefore, compared to, for example, applying an adhesive to the electrical steel sheets and bonding them together with the adhesive, the laminated core can be manufactured more easily.

[0034] (15) A method for manufacturing a laminated core according to one aspect of the present invention is a method for manufacturing a laminated core according to any one of the above items (2) to (7), comprising: a first step of forming a first laminated steel sheet by heating the teeth portion of the laminated electromagnetic steel sheet to exhibit adhesive properties to the insulating coating; a second step of forming a second laminated steel sheet by laminating the electromagnetic steel sheets in a state unaffected by the heating in the first step; and a third step of stacking the first laminated steel sheet and the second laminated steel sheet after the first and second steps.

[0035] In this process, the electrical steel sheets are laminated in a state unaffected by the heating in the first step to form a second laminated steel sheet. Therefore, it is possible to suppress the unintentional bonding between the electrical steel sheets forming the second laminated steel sheet. [Effects of the Invention]

[0036] According to the present invention, the magnetic properties of a laminated core can be improved. [Brief explanation of the drawing]

[0037] [Figure 1] This is a cross-sectional view of a rotating electric machine equipped with a laminated core according to the first embodiment of the present invention. [Figure 2] This is a side view of the same stacked core. [Figure 3] This is a cross-sectional view AA in Figure 2. [Figure 4] This is a plan view of the material forming the laminated core. [Figure 5] Figure 4 is a cross-sectional view of BB. [Figure 6] This is an enlarged view of section C in Figure 5. [Figure 7]This is a side view of the manufacturing equipment used to produce the laminated core. [Figure 8] This is a plan view of an electromagnetic steel sheet constituting a laminated core according to a first modified example of the present invention. [Figure 9] This is a plan view of an electromagnetic steel sheet constituting a laminated core according to a second modified example of the present invention. [Figure 10] This is a plan view of an electromagnetic steel sheet constituting a laminated core according to a third modified example of the present invention. [Figure 11] This is a plan view of an electromagnetic steel sheet constituting a laminated core according to a fourth modified example of the present invention. [Figure 12] This is a plan view of an electrical steel sheet constituting a laminated core according to a fifth modified example of the present invention. [Figure 13] This is a side view of a laminated core according to a sixth modified example of the present invention. [Modes for carrying out the invention]

[0038] The following describes, with reference to the drawings, a laminated core according to one embodiment of the present invention, a rotating electric machine equipped with this laminated core, and the material forming this laminated core. In this embodiment, an electric motor, specifically an AC motor, more specifically a synchronous motor, and even more specifically a permanent magnet field motor, will be used as an example of the rotating electric machine. This type of electric motor is suitably used, for example, in electric vehicles.

[0039] (Rotating electric machine 10) As shown in Figure 1, the rotating electric machine 10 comprises a stator 20, a rotor 30, a case 50, and a rotating shaft 60. The stator 20 and rotor 30 are housed within the case 50. The stator 20 is fixed within the case 50. In this embodiment, the rotating electric machine 10 is an inner rotor type in which the rotor 30 is located radially inward of the stator 20. However, the rotating electric machine 10 may also be an outer rotor type in which the rotor 30 is located outside of the stator 20. Furthermore, in this embodiment, the rotating electric machine 10 is a 12-pole, 18-slot three-phase AC motor. However, the number of poles, the number of slots, the number of phases, etc., can be changed as appropriate. The rotating electric machine 10 can rotate at a rotational speed of 1000 rpm by applying an excitation current with an effective value of 10 A and a frequency of 100 Hz to each phase, for example.

[0040] The stator 20 comprises a stator adhesive laminated core (hereinafter referred to as the stator core) 21 and windings (not shown). The stator core 21 comprises an annular core back portion 22 and a plurality of teeth portions 23. Hereinafter, the direction of the central axis O of the stator core 21 (or core back portion 22) will be referred to as the axial direction, the radial direction (direction perpendicular to the central axis O) of the stator core 21 (or core back portion 22) will be referred to as the radial direction, and the circumferential direction (direction around the central axis O) of the stator core 21 (or core back portion 22) will be referred to as the circumferential direction.

[0041] The core back portion 22 is formed in an annular shape in a plan view of the stator 20 as seen from the axial direction. Multiple teeth portions 23 protrude radially inward from the inner circumference of the core back portion 22 (towards the central axis O of the core back portion 22 along the radial direction). The multiple teeth portions 23 are arranged at equal angular intervals in the circumferential direction. In this embodiment, 18 teeth portions 23 are provided at central angle intervals of 20 degrees around the central axis O. The multiple teeth portions 23 are formed to be of the same shape and size as each other. Therefore, the multiple teeth portions 23 have the same thickness dimension as each other. The winding is wound around the teeth portion 23. The winding may be a concentrated winding or a distributed winding.

[0042] The rotor 30 is positioned radially inward relative to the stator 20 (stator core 21). The rotor 30 comprises a rotor core 31 and a plurality of permanent magnets 32. The rotor core 31 is formed in an annular (ring-shaped) form and is arranged coaxially with the stator 20. The rotating shaft 60 is located inside the rotor core 31. The rotating shaft 60 is fixed to the rotor core 31. Multiple permanent magnets 32 are fixed to the rotor core 31. In this embodiment, pairs of permanent magnets 32 form one magnetic pole. Multiple pairs of permanent magnets 32 are arranged at equal angular intervals in the circumferential direction. In this embodiment, 12 pairs (24 in total) of permanent magnets 32 are provided at 30-degree intervals around the central axis O.

[0043] In this embodiment, an embedded magnet type motor is used as the permanent magnet field motor. The rotor core 31 has a plurality of through holes 33 that penetrate the rotor core 31 in the axial direction. The plurality of through holes 33 are provided corresponding to the arrangement of the plurality of permanent magnets 32. Each permanent magnet 32 ​​is fixed to the rotor core 31 while positioned within the corresponding through hole 33. Fixing each permanent magnet 32 ​​to the rotor core 31 can be achieved, for example, by bonding the outer surface of the permanent magnet 32 ​​to the inner surface of the through hole 33 with an adhesive. Note that a surface magnet type motor may be used instead of the embedded magnet type as the permanent magnet field motor.

[0044] Both the stator core 21 and the rotor core 31 are laminated cores. For example, as shown in Figure 2, the stator core 21 is formed by laminating multiple electromagnetic steel sheets 40 in the lamination direction. The stacking thickness (total length along the central axis O) of the stator core 21 and rotor core 31 is, for example, 50.0 mm to 200.0 mm, preferably 60.0 mm to 170.00 mm. The outer diameter of the stator core 21 is 200.0 mm to 300.0 mm, for example 250.0 mm. The inner diameter of the stator core 21 is 130.0 mm to 180.0 mm, for example 165.0 mm. The outer diameter of the rotor core 31 is, for example 163.0 mm. The inner diameter of the rotor core 31 is, for example 30.0 mm. However, these values ​​are just examples, and the stacking thickness, outer diameter and inner diameter of the stator core 21, and the stacking thickness, outer diameter and inner diameter of the rotor core 31 are not limited to these values. Here, the inner diameter of the stator core 21 is based on the tip of the teeth portion 23 in the stator core 21. In other words, the inner diameter of the stator core 21 is the diameter of a virtual circle that is inscribed in the tips of all the teeth 23.

[0045] Each electrical steel sheet 40 forming the stator core 21 and rotor core 31 is formed, for example, by punching out material 1 as shown in Figures 4 to 6. Material 1 is a steel sheet (electrical steel sheet) that serves as the base material for the electrical steel sheets 40. Examples of material 1 include strip-shaped steel sheets and cut sheets. Although the explanation of the laminated core is still in progress, the following will describe Material 1. In this specification, the strip-shaped steel sheet that serves as the base material for the electrical steel sheet 40 may be referred to as Material 1. The steel sheet that has been punched out to form the shape used for the laminated core may be referred to as the electrical steel sheet 40.

[0046] (Material 1) Material 1 is handled, for example, in a state wound onto coil 1A. In this embodiment, non-oriented electrical steel sheet is used as material 1. As the non-oriented electrical steel sheet, non-oriented electrical steel strip of JIS C 2552:2014 can be used. However, grain-oriented electrical steel sheet may be used as material 1 instead of non-oriented electrical steel sheet. In this case, grain-oriented electrical steel strip of JIS C 2553:2019 can be used as the grain-oriented electrical steel sheet. Alternatively, non-oriented thin electrical steel strip or grain-oriented thin electrical steel strip of JIS C 2558:2015 can be used.

[0047] The upper and lower limits of the average plate thickness t0 of material 1 are set, for example, as follows, taking into consideration the case where material 1 is used as electrical steel sheet 40. As material 1 becomes thinner, the manufacturing cost of material 1 increases. Therefore, considering the manufacturing cost, the lower limit of the average plate thickness t0 of material 1 is 0.10 mm, preferably 0.15 mm, and more preferably 0.18 mm. On the other hand, if material 1 is too thick, the manufacturing cost will be good, but when material 1 is used as electrical steel sheet 40, eddy current loss will increase and core iron loss will deteriorate. Therefore, considering core iron loss and manufacturing cost, the upper limit of the average sheet thickness t0 of material 1 is 0.65 mm, preferably 0.35 mm, and more preferably 0.30 mm. As an example of an average plate thickness t0 of material 1 that satisfies the above range, 0.20 mm can be used.

[0048] Note that the average plate thickness t0 of material 1 includes not only the thickness of the base steel plate 2 described later, but also the thickness of the insulating coating 3. Furthermore, the method for measuring the average plate thickness t0 of material 1 is, for example, the following method. For example, if material 1 is wound into the shape of a coil 1A, at least a portion of material 1 is unwound into a flat plate shape. On the flat plate shape of material 1, a predetermined position in the longitudinal direction of material 1 is selected (for example, a position 10% of the total length of material 1 from the longitudinal edge of material 1). At this selected position, material 1 is divided into five regions along its width direction. The plate thickness of material 1 is measured at four locations that form the boundaries of these five regions. The average value of the plate thicknesses at these four locations can be taken as the average plate thickness t0 of material 1.

[0049] The upper and lower limits for the average plate thickness t0 of material 1 can naturally be used as the upper and lower limits for the average plate thickness t0 of the electrical steel sheet 40. The method for measuring the average plate thickness t0 of the electrical steel sheet 40 is, for example, the following method: For example, the stacked thickness of the laminated core is measured at four locations with equal spacing in the circumferential direction (i.e., at 90-degree intervals around the central axis O). The thickness per sheet is calculated by dividing each of the four measured stacked thicknesses by the number of laminated electrical steel sheets 40. The average value of the four thicknesses can be taken as the average plate thickness t0 of the electrical steel sheet 40.

[0050] As shown in Figures 5 and 6, the material 1 comprises a base steel sheet 2 and an insulating coating 3. The material 1 is formed by covering both sides of a strip-shaped base steel sheet 2 with the insulating coating 3. In this embodiment, the majority of the material 1 is formed from the base steel sheet 2, and an insulating coating 3 thinner than the base steel sheet 2 is laminated on the surface of the base steel sheet 2.

[0051] The chemical composition of the base steel sheet 2 contains 2.5% to 4.5% Si by mass, as shown below in mass percent. By setting the chemical composition within this range, the yield strength of material 1 (electrical steel sheet 40) can be set to, for example, 380 MPa to 540 MPa.

[0052] Si: 2.5%~4.5% Al: 0.001%~3.0% Mn: 0.05%~5.0% Remainder: Fe and impurities

[0053] When material 1 is used as an electrical steel sheet 40, the insulating coating 3 provides insulation between adjacent electrical steel sheets 40 in the lamination direction. In this embodiment, the insulating coating 3 also has adhesive properties and adheres adjacent electrical steel sheets 40 in the lamination direction. The insulating coating 3 may be a single layer or a multi-layer structure. More specifically, for example, the insulating coating 3 may be a single layer structure that combines insulating properties and adhesive properties, or it may be a multi-layer structure including a base insulating coating with excellent insulating properties and a top insulating coating with excellent adhesive properties.

[0054] In this embodiment, the insulating coating 3 completely covers both sides of the base steel plate 2 without any gaps. However, within the range in which the aforementioned insulating performance and adhesive performance are ensured, some layers of the insulating coating 3 do not need to completely cover both sides of the base steel plate 2 without any gaps. In other words, some layers of the insulating coating 3 may be intermittently provided on the surface of the base steel plate 2. However, in order to ensure insulating performance, both sides of the base steel plate 2 must be covered by the insulating coating 3 so that the entire surface is not exposed. Specifically, if the insulating coating 3 does not have an underlying insulating coating with excellent insulating performance and is a single-layer structure that combines insulating performance and adhesive performance, then the insulating coating 3 needs to be formed completely over the entire surface of the base steel plate 2 without any gaps. In contrast, if the insulating coating 3 has a multi-layer structure including a base insulating coating with excellent insulating performance and a top insulating coating with excellent adhesive properties, it is possible to achieve both insulating performance and adhesive properties by forming both the base insulating coating and the top insulating coating seamlessly across the entire surface of the base steel plate 2, or by forming the base insulating coating seamlessly across the entire surface of the base steel plate and providing the top insulating coating intermittently.

[0055] The coating composition for forming the underlying insulating film is not particularly limited, and general treatment agents such as chromic acid-containing treatment agents and phosphate-containing treatment agents can be used.

[0056] An insulating coating with adhesive properties is formed by applying the coating composition for electrical steel sheets described later onto a base steel sheet. An insulating coating with adhesive properties is, for example, a single-layer insulating coating that combines insulating performance and adhesive properties, or a top insulating coating provided on a base insulating coating. Before heat bonding during the manufacturing of laminated cores, the insulating coating with adhesive properties is in an uncured or semi-cured state (Stage B), and the curing reaction proceeds due to heating during heat bonding, resulting in the development of adhesive properties.

[0057] The coating composition for electrical steel sheets is not particularly limited, and examples include compositions containing an epoxy resin and an epoxy resin curing agent. That is, an example of an insulating film with adhesive properties is a film containing an epoxy resin and an epoxy resin curing agent.

[0058] As the epoxy resin, any general epoxy resin can be used, and specifically, any epoxy resin having two or more epoxy groups in one molecule can be used without particular restriction. Examples of such epoxy resins include bisphenol A type epoxy resin, bisphenol F type epoxy resin, phenol novolac type epoxy resin, cresol novolac type epoxy resin, alicyclic epoxy resin, glycidyl ester type epoxy resin, glycidylamine type epoxy resin, hydantoin type epoxy resin, isocyanurate type epoxy resin, acrylic acid modified epoxy resin (epoxy acrylate), phosphorus-containing epoxy resin, and halogens thereof (brominated epoxy resin, etc.) and hydrogenated products. As the epoxy resin, one type may be used alone, or two or more types may be used in combination.

[0059] The coating composition for electrical steel sheets may also contain acrylic resin. The acrylic resin is not particularly limited. Examples of monomers used in the acrylic resin include unsaturated carboxylic acids such as acrylic acid and methacrylic acid, and (meth)acrylates such as methyl (meth)acrylate, ethyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, cyclohexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, and hydroxypropyl (meth)acrylate. Note that (meth)acrylate means acrylate or methacrylate. The acrylic resin may be used alone or in combination of two or more types.

[0060] Acrylic resins may have constituent units derived from monomers other than acrylic monomers. Examples of other monomers include ethylene, propylene, and styrene. These other monomers may be used individually or in combination of two or more.

[0061] When using acrylic resin, it may be used as an acrylic-modified epoxy resin obtained by grafting acrylic resin onto an epoxy resin. In coating compositions for electrical steel sheets, it may be included as a monomer that forms the acrylic resin.

[0062] As epoxy resin curing agents, latent, heat-curing types can be used, such as aromatic polyamines, acid anhydrides, phenolic curing agents, dicyandiamides, boron trifluoride-amine complexes, and organic acid hydrazides. Examples of aromatic polyamines include metaphenylenediamine, diaminodiphenylmethane, and diaminodiphenylsulfone. Examples of phenolic curing agents include phenol novolac resins, cresol novolac resins, bisphenol novolac resins, triazine-modified phenol novolac resins, and phenol resol resins. Among these, phenolic curing agents are preferred as epoxy resin curing agents, and phenol resol resins are more preferred. As epoxy resin curing agents, one type may be used alone, or two or more types may be used in combination.

[0063] The amount of epoxy resin curing agent in the coating composition for electrical steel sheets is preferably 5 to 35 parts by mass, and more preferably 10 to 30 parts by mass, per 100 parts by mass of epoxy resin.

[0064] The coating composition for electrical steel sheets may contain additives such as curing accelerators (curing catalysts), emulsifiers, and defoamers. Only one additive may be used, or two or more may be used in combination.

[0065] The upper and lower limits of the average thickness t1 of the insulating coating 3 are set, for example, as follows, taking into consideration the case where material 1 is used as an electrical steel sheet 40. When material 1 is used as an electrical steel sheet 40, the average thickness t1 of the insulating coating 3 (thickness per side of the electrical steel sheet 40 (material 1)) is adjusted to ensure insulation performance and adhesive properties between the electrical steel sheets 40 that are laminated together.

[0066] In the case of a single-layer insulating coating 3, the average thickness t1 of the insulating coating 3 (thickness per side of the electromagnetic steel sheet 40 (material 1)) can be, for example, 1.5 μm or more and 8.0 μm or less. In the case of a multi-layered insulating coating 3, the average thickness of the base insulating coating can be, for example, 0.3 μm or more and 1.2 μm or less, and preferably 0.7 μm or more and 0.9 μm or less. The average thickness of the top insulating coating can be, for example, 1.5 μm or more and 8.0 μm or less. Furthermore, the method for measuring the average thickness t1 of the insulating coating 3 in material 1 is the same as for the average plate thickness t0 of material 1; the thickness of the insulating coating 3 at multiple locations is determined, and the average of these thicknesses is used to determine the average thickness.

[0067] The upper and lower limits for the average thickness t1 of the insulating coating 3 in material 1 can naturally be used as the upper and lower limits for the average thickness t1 of the insulating coating 3 in the electrical steel sheet 40. The method for measuring the average thickness t1 of the insulating coating 3 in the electrical steel sheet 40 can be, for example, the following method. For example, among the multiple electrical steel sheets forming the laminated core, select the electrical steel sheet 40 located on the outermost side in the lamination direction (the electrical steel sheet 40 whose surface is exposed in the lamination direction). On the surface of the selected electrical steel sheet 40, select a predetermined position in the radial direction (for example, the position exactly midway (center) between the inner and outer edges of the electrical steel sheet 40). At the selected position, measure the thickness of the insulating coating 3 of the electrical steel sheet 40 at four locations with equal spacing in the circumferential direction (i.e., at 90-degree intervals around the central axis O). The average value of the thicknesses measured at the four locations can be taken as the average thickness t1 of the insulating coating 3. The reason why the average thickness t1 of the insulating film 3 was measured on the outermost electrical steel sheet 40 in the lamination direction is that the insulating film 3 is manufactured in such a way that its thickness hardly changes at the lamination position along the lamination direction of the electrical steel sheet 40.

[0068] By punching out material 1 as described above, electrical steel sheets 40 are manufactured, and laminated cores (stator core 21 and rotor core 31) are manufactured from the electrical steel sheets 40.

[0069] (Layer stacking method for stacked cores) The following is a description of the laminated core. The multiple electromagnetic steel sheets 40 that form the stator core 21 are laminated with an insulating coating 3 in between, as shown in Figure 3.

[0070] As shown in Figure 2, in this embodiment, some of the multiple electrical steel sheets 40 form a first laminated steel sheet 51, and the remaining electrical steel sheets 40 that do not form the first laminated steel sheet 51 form a second laminated steel sheet 52. As shown in Figure 3, in the first laminated steel sheet 51, the teeth portions 23 of adjacent electrical steel sheets 40 in the lamination direction are bonded to each other. In the case of the teeth portions 23 of the first laminated steel sheet 51, at least the portions including the radial tip 23a of the teeth portion 23 are bonded to each other.

[0071] Here, the radial tip 23a of the tooth portion 23 refers to the end of the tooth portion 23 located radially opposite to the core back portion 22. In this embodiment, the radial tip 23a of the tooth portion 23 is the innermost part of the tooth portion 23 in the radial direction. In the illustrated example, the tooth portion 23 is formed in a radially elongated rectangular shape in plan view. The radial tip 23a of the tooth portion 23 corresponds to the side located radially inward in plan view. Note that, unlike this embodiment, if the tooth portion 23 protrudes radially outward from the core back portion 22, the radial tip 23a of the tooth portion 23 is the outermost part of the tooth portion 23 in the radial direction.

[0072] In the illustrated example, all of the multiple teeth 23 are bonded together, and there are no teeth 23 that are not bonded. Furthermore, of each tooth 23, half of the portion closer to the tip 23a than the center along the radial direction is bonded. The bonding area ratio of each tooth 23 is 50%. At the teeth portions 23 of the first laminated steel sheet 51, the insulating coatings 3 of each electrical steel sheet 40 are bonded together. In other words, although no adhesive is placed between adjacent electrical steel sheets 40 in the lamination direction, the electrical steel sheets 40 are bonded together. As mentioned above, the insulating coating 3 covers both sides of the base steel sheet 2 completely, but only a portion of the insulating coating 3 is bonded, not the entire surface.

[0073] In other words, adjacent electrical steel sheets 40 in the lamination direction are locally bonded by the insulating coating 3. To put it another way, on the surface of the electrical steel sheet 40 facing the lamination direction (hereinafter referred to as the first surface), bonded areas 41a and non-bonded areas 41b are mixed together. The adhesive region 41a refers to the region on the first surface of the electrical steel sheet 40 where the insulating coating 3 is integrally bonded to the insulating coating 3 of an adjacent electrical steel sheet 40 without any interface. The non-adhesive region 41b refers to the region on the first surface of the electrical steel sheet 40 where the insulating coating 3 is not bonded to the insulating coating 3 of an adjacent electrical steel sheet 40. In other words, in the non-adhesive region 41b, the surfaces of the insulating coatings 3 of adjacent electrical steel sheets 40 in the lamination direction are only in contact with each other and are not bonded.

[0074] The method for determining the adhesive region 41a and the non-adhesive region 41b on the first surface of the electrical steel sheet 40 is, for example, the following method. Specifically, two electrical steel sheets 40 that are bonded together via the insulating coating 3 are peeled apart. The first surface of the peeled-away electrical steel sheets 40 is observed, and the area where adhesive residue of the insulating coating 3 remains due to the peeling of the adhesive region 41a is determined to be the adhesive region 41a, and the area where no adhesive residue remains is determined to be the non-adhesive region 41b (as mentioned above, no adhesive residue remains in areas that are fixed by tackiness). Image processing using a computer or artificial intelligence may be used for this determination.

[0075] Furthermore, in the first laminated steel sheet 51, the teeth portions 23 of adjacent electromagnetic steel sheets 40 in the lamination direction are not joined by any joining method other than adhesive (for example, crimping or welding). That is, the teeth portions 23 are not bonded to each other, nor are they crimped to each other, nor are they welded to each other. In other words, the teeth portions 23 do not have recesses or protrusions for crimping that are fitted together, nor are weld metals formed.

[0076] In this embodiment, as shown in Figure 2, at least one of the plurality of electromagnetic steel sheets 40, including the electromagnetic steel sheet 40 located at the furthest end of the first side D1 in the lamination direction, and the plurality of electromagnetic steel sheets 40, including the electromagnetic steel sheet 40 located at the furthest end of the second side D2 in the lamination direction, forms the first laminated steel sheet 51.

[0077] In the second laminated steel sheet 52, the teeth portions 23 of adjacent electrical steel sheets 40 in the lamination direction are not bonded to each other. These teeth portions 23 are not joined by any joining method other than bonding (for example, crimping or welding). That is, the teeth portions 23 are not bonded to each other, are not crimped to each other, and are not welded to each other. In this embodiment, the remaining electrical steel sheets 40 located in the center of the lamination direction out of a plurality of electrical steel sheets 40 form the second laminated steel sheet 52. No bonding region 41a is formed in the electrical steel sheets 40 that form the second laminated steel sheet 52.

[0078] Furthermore, in the first laminated steel sheet 51 and the second laminated steel sheet 52, the core back portions 22 of adjacent electrical steel sheets 40 in the lamination direction are not bonded to each other. Also, in the first laminated steel sheet 51 and the second laminated steel sheet 52, the electrical steel sheets 40 are not joined by any joining method other than adhesive (for example, crimping or welding). Moreover, the first laminated steel sheet 51 and the second laminated steel sheet 52 are not bonded to each other, nor are they joined by any joining method other than adhesive.

[0079] Here, let N1 be the number of electromagnetic steel sheets 40 forming the first laminated steel sheet 51 (hereinafter also referred to as the first laminated steel sheet 51a) on the first side D1 in the lamination direction. Let N2 be the number of electromagnetic steel sheets 40 forming the first laminated steel sheet 51 (hereinafter also referred to as the first laminated steel sheet 51b) on the second side D2 in the lamination direction. Let N3 be the number of electromagnetic steel sheets 40 forming the second laminated steel sheet 52 in the center in the lamination direction. Let N0 be the total number of electromagnetic steel sheets 40.

[0080] In this embodiment, the number of sheets N1 and the number of sheets N2 are equal (i.e., N1=N2). The number of sheets N3 is greater than or equal to the number of sheets N1 and greater than or equal to the number of sheets N2 (i.e., N3≧N1 and N3≧N2). Furthermore, the number of sheets N1 and the number of sheets N2 are equal to the number of sheets N3 (i.e., N1=N2=N3). The number of sheets N1 and the number of sheets N2 are less than or equal to 1 / 3 of the number of sheets N0 (i.e., N1≦((N0) / 3) and N2≦((N0) / 3)), and more specifically, they are 1 / 3 of the number of sheets N0 (i.e., N1=((N0) / 3) and N2=((N0) / 3)).

[0081] In this embodiment, the multiple electromagnetic steel sheets forming the rotor core 31 are fixed to each other by crimping 42 (dowels) as shown in Figure 1. However, the multiple electromagnetic steel sheets forming the rotor core 31 may also have a laminated structure fixed by an insulating coating 3, similar to the stator core 21. Furthermore, laminated cores such as the stator core 21 and rotor core 31 may be formed by a so-called spiral stacking method.

[0082] (Method of manufacturing a laminated core) The stator core 21 is manufactured, for example, using the manufacturing apparatus 100 shown in Figure 7. In describing the manufacturing method below, we will first describe the laminated core manufacturing apparatus 100 (hereinafter simply referred to as the manufacturing apparatus 100). In the manufacturing apparatus 100, the material 1 is fed from the coil 1A (hoop) in the direction of arrow F, and is gradually formed into the shape of the electromagnetic steel sheet 40 by punching multiple times using dies placed at each stage. Then, the punched electromagnetic steel sheets 40 are stacked and pressurized while the temperature is raised. As a result, adjacent electromagnetic steel sheets 40 in the stacking direction are bonded together by the insulating coating 3 (that is, the portion of the insulating coating 3 located in the bonding region 41a exhibits adhesive properties), and bonding is completed.

[0083] As shown in Figure 7, the manufacturing apparatus 100 is equipped with multiple punching stations 110. The punching stations 110 may have two stages, or three or more stages. Each punching station 110 is equipped with a female die 111 positioned below the material 1 and a male die 112 positioned above the material 1.

[0084] The manufacturing apparatus 100 further includes a stacking station 140 located downstream of the furthest downstream punching station 110. This stacking station 140 comprises a first heating device 141a (see Figure 3), an outer peripheral punching female die 142, an outer peripheral punching male die 144, and a spring 145. The first heating device 141a, the outer peripheral punching female die 142, and the heat insulating member 143 are positioned below the material 1. On the other hand, the outer peripheral punching male die 144 and the spring 145 are positioned above the material 1.

[0085] In the manufacturing apparatus 100 having the configuration described above, first, material 1 is sequentially fed from coil 1A in the direction of arrow F in Figure 7. Then, punching is sequentially performed on this material 1 by multiple punching stations 110. Through these punching processes, the material 1 is given the shape of an electromagnetic steel sheet 40 having a core back portion 22 and multiple teeth portions 23 as shown in Figure 3. However, since it is not completely punched at this point, the process proceeds to the next step along the direction of arrow F.

[0086] Finally, material 1 is sent to the lamination station 140, where it is punched out by the outer peripheral punching die 144 and laminated with precision. During this lamination, the electromagnetic steel sheet 40 is subjected to a constant pressure by the spring 145. By sequentially repeating the punching process and the lamination process as described above, a predetermined number of electromagnetic steel sheets 40 can be stacked.

[0087] In this embodiment, the method for manufacturing the stator core 21 further includes the following steps 1 to 3. In the first step, the teeth portion 23 of the laminated electrical steel sheet 40 is heated to allow the insulating coating 3 to exhibit adhesive (fusion) ability, thereby forming the first laminated steel sheet 51. This first step is performed twice to form the first laminated steel sheet 51a on the first side D1 and the first laminated steel sheet 51b on the second side D2. In the second step, the electrical steel sheets 40 are laminated in a state unaffected by the heating in the first step to form a second laminated steel sheet 52. In the third step, after the first and second steps, the first laminated steel sheet 51 and the second laminated steel sheet 52 are stacked on top of each other.

[0088] Specifically, in the first step, the punching and lamination processes described above are repeated to laminate a predetermined number (N1 or N2) of electromagnetic steel sheets 40. At this time, the electromagnetic steel sheets 40 are laminated in the outer peripheral punching die 142. After that, a first heating device 141a, as shown by the dashed line in Figure 3, is placed inside the laminated electromagnetic steel sheets 40 in the radial direction. Note that the first heating device 141a may be placed inside the laminated electromagnetic steel sheets 40 while the laminated electromagnetic steel sheets 40 are still in the outer peripheral punching die 142, or it may be placed inside the laminated electromagnetic steel sheets 40 after the laminated electromagnetic steel sheets 40 have been removed from the outer peripheral punching die 142.

[0089] The first heating device 141a faces the tip 23a of the tooth portion 23 from the radially inner side. The first heating device 141a heats the tooth portion 23 from the tip 23a of the tooth portion 23. The first heating device 141a is formed by, for example, a heating element or a coil. The first heating device 141a heats the tooth portion 23 by heat conduction, thermal radiation, induction heating, etc. As the tooth portion 23 is heated, the insulating coatings 3 of the tooth portions 23 in adjacent electromagnetic steel sheets 40 in the lamination direction adhere (fuse) to each other.

[0090] The first heating device 141a can, for example, heat the tip 23a of the tooth portion 23 to a temperature of 200°C to 800°C for 30 seconds to 600 seconds. By rapidly heating the tip 23a of the tooth portion 23 in this way, the tooth portion 23 can be partially bonded without being affected by unnecessary thermal distortion. As a result, the first laminated steel plate 51 is formed.

[0091] In the second step, the electromagnetic steel sheets 40 are laminated in a state unaffected by the heating in the first step to form the second laminated steel sheet 52. At this time, the electromagnetic steel sheets 40 are laminated inside the outer peripheral punching die 142, similar to when the first laminated steel sheet 51 is formed. However, the aforementioned first heating device 141a is not used. The second laminated steel sheet 52 formed by carrying out the second step is transported out of the outer peripheral punching die 142 to the outside.

[0092] In the third step, for example, the first laminated steel sheet 51 and the second laminated steel sheet 52 are stacked at another station located outside the outer perimeter punching die 142. At this time, the first laminated steel sheet 51 and the second laminated steel sheet 52 may be stacked in rotations, for example, every 120°.

[0093] The stator core 21 is completed through the above steps. Furthermore, it is preferable to securely hold the completed stator core 21 by, for example, using a jig (not shown) to sandwich the core back portion 22 from both sides in the stacking direction. When winding is applied to the stator core 21 whose shape is maintained by the jig, the stator 20 is manufactured. Even after the jig is removed from the stator 20 after winding, the shape of the stator core 21 is maintained by the winding.

[0094] Here, such a jig can be applied not only to the completed stator core 21, but also to laminated electromagnetic steel sheets 40 that have not yet been bonded. That is, the electromagnetic steel sheets 40 that form the first laminated steel sheet 51, which have been laminated but not yet bonded, may be held by the jig. Also, the second laminated steel sheet 52, which have been laminated but not yet combined with the first laminated steel sheet 51, may be held by the jig.

[0095] However, the above manufacturing method is merely an example, and it is possible to manufacture the stator core 21 by other methods. For example, some of the teeth portions 23 of the laminated electromagnetic steel sheets 40 may be locally heated to allow the insulating coating 3 on those parts of the electromagnetic steel sheets 40 to exhibit adhesive properties (fusion properties). In this case, the teeth portions 23 of those parts of the electromagnetic steel sheets 40 are bonded to each other to form a first laminated steel sheet 51, and the remaining electromagnetic steel sheets 40 become a second laminated steel sheet 52. In such a manufacturing method, all of the teeth portions 23 of the laminated electromagnetic steel sheets 40 may be heated to bond all of the teeth portions 23 of the electromagnetic steel sheets 40, forming a first laminated steel sheet 51 from all of the electromagnetic steel sheets 40, and forming the stator core 21 of the stator 20A (see Figure 13) according to the sixth modified example described later. In either of these cases, the laminated electromagnetic steel sheets 40 before heating may be held by the jig.

[0096] By the way, in the stator core 21, when adjacent electrical steel sheets 40 in the lamination direction are bonded together, strain occurs in the bonded portion of the electrical steel sheet 40 (base steel sheet 2). When strain occurs in the electrical steel sheet 40, the iron loss of the stator core 21 increases, and the magnetic properties of the stator core 21 deteriorate. In particular, the magnetic flux density of the teeth portion 23 is higher than that of the core back portion 22. Therefore, the deterioration of magnetic properties due to strain is more significant in the teeth portion 23. For this reason, it is preferable that the electrical steel sheets 40 are not bonded together as much as possible in the teeth portion 23 of the stator core 21. In the stator core 21 according to this embodiment, the teeth 23 are not bonded together in the second laminated steel sheet 52. Therefore, the effect of deterioration in magnetic properties due to strain generation in the second laminated steel sheet 52 can be suppressed.

[0097] On the other hand, if the teeth portion 23 of the electromagnetic steel sheet 40 located at the end in the lamination direction is not bonded, there is a risk that the teeth portion 23 may lift up. In this case, the teeth portions 23 of adjacent electromagnetic steel sheets 40 in the lamination direction will separate from each other. As a result, the magnetic properties of the stator core 21 may deteriorate more than the effect of strain. In the stator core 21 according to this embodiment, at least one of the electromagnetic steel sheets 40, including the electromagnetic steel sheet 40 located at the furthest end of the first side D1 in the lamination direction, and the electromagnetic steel sheet 40, including the electromagnetic steel sheet 40 located at the furthest end of the second side D2 in the lamination direction, forms the first laminated steel sheet 51. In other words, the teeth portions 23 are bonded together in the electromagnetic steel sheets 40, including the electromagnetic steel sheet 40 located at the furthest end of the first side D1 in the lamination direction, and the electromagnetic steel sheet 40, including the electromagnetic steel sheet 40 located at the furthest end of the second side D2 in the lamination direction. Therefore, the lifting of the teeth portions 23 can be suppressed at at least one of the ends of the stator core 21, including the end of the first side D1 in the lamination direction, and the end of the second side D2 in the lamination direction. Thus, the effect of the decrease in magnetic properties due to the lifting of the teeth portions 23 can be suppressed. Furthermore, the lifting of the teeth portion 23 is restricted by adhesion, not by riveting or welding. In this embodiment, the lifting of the teeth portion 23 is restricted by adhesion alone, rather than by using adhesion in combination with riveting or welding. Here, mechanical stress is generated in the case of riveting, and thermal stress is generated in the case of welding. These mechanical and thermal stresses affect the magnetic properties more than the effects of strain. Also, in both the case of riveting and welding, there is a risk that the magnetic properties of the electromagnetic steel sheet 40 will deteriorate due to interlayer short circuits. Therefore, by restricting the lifting of the teeth portion 23 by adhesion, the effect of the deterioration of magnetic properties can be suppressed.

[0098] Furthermore, according to the stator core 21 of this embodiment, the electromagnetic steel sheets 40 forming the first laminated steel sheet 51 are bonded together by the insulating coating 3 of the electromagnetic steel sheets 40. In other words, the electromagnetic steel sheets 40 are not bonded together by an adhesive provided separately from the electromagnetic steel sheets 40. When the electromagnetic steel sheets 40 are bonded together by an adhesive, the adhesive is placed between adjacent electromagnetic steel sheets 40, causing them to separate by the thickness of the adhesive. In contrast, as in the stator core 21 of this embodiment, when adjacent electromagnetic steel sheets 40 in the lamination direction are bonded together by the insulating coating 3 of the electromagnetic steel sheets 40, the adjacent electromagnetic steel sheets 40 do not separate due to the adhesive as described above. Therefore, not only can a decrease in the packing factor of the stator core 21 be avoided, but unintended vibrations in the non-bonded areas when the stator core 21 is assembled to a rotating electric machine and operates can be suppressed, and the impact of a decrease in the overall magnetic properties of the rotating electric machine can be reduced.

[0099] As described above, the effects of the decrease in magnetic properties due to strain, the decrease in magnetic properties due to the lifting of the teeth portion 23, and the decrease in magnetic properties due to the placement of the adhesive can all be suppressed. As a result, the magnetic properties of the stator core 21 can be improved.

[0100] In both a portion of the electromagnetic steel sheets 40, including the one located at the very end of the first side D1 in the lamination direction, and a portion of the electromagnetic steel sheets 40, including the one located at the very end of the second side D2 in the lamination direction, the teeth portions 23 of adjacent electromagnetic steel sheets 40 in the lamination direction are bonded together. Therefore, the lifting of the teeth portions 23 can be suppressed at both the end of the first side D1 in the lamination direction and the end of the second side D2 in the lamination direction of the stator core 21. Thus, the effect of the decrease in magnetic properties due to the lifting of the teeth portions 23 can be effectively suppressed.

[0101] The number of sheets N3 is greater than or equal to the number of sheets N1, and also greater than or equal to the number of sheets N2. Therefore, the ratio of the number of electromagnetic steel sheets 40 to which the teeth portion 23 is bonded can be reduced in the entire stator core 21. As a result, the effect of the deterioration of the magnetic properties of the stator core 21 due to the generation of strain can be further suppressed. The number of sheets N1 and N2 are both less than or equal to 1 / 3 of the total number of electromagnetic steel sheets 40 (hereinafter referred to as number N0). Therefore, the ratio of the number of electromagnetic steel sheets 40 to which the teeth portion 23 is bonded can be reduced in the entire stator core 21. As a result, the effect of the deterioration of the magnetic properties of the stator core 21 due to the generation of strain can be further suppressed. The number of layers N1 and the number of layers N2 are equal. Therefore, it is possible to suppress the occurrence of differences between the magnetic properties on the first side D1 and the magnetic properties on the second side D2 in the stacking direction of the stator core 21. This improves the handling of the stator core 21. The number of sheets N1 and N2 are equal to the number of sheets N3. Therefore, in the manufacturing process of any part of the first laminated steel sheet 51 on the first side D1, the first laminated steel sheet 51 on the second side D2, or the second laminated steel sheet 52 in the center, the same number of electromagnetic steel sheets 40 should be stacked. As a result, the manufacturing of the stator core 21 can be further simplified.

[0102] Generally, at the ends of the stator core 21 in the stacking direction, the tip 23a of the teeth portion 23 is particularly prone to lifting. According to the stator core 21 of this embodiment, in the first laminated steel sheet 51, at least the portion of the teeth 23 of adjacent electromagnetic steel sheets 40 in the lamination direction, including the tip 23a, is bonded together. Therefore, the lifting of the teeth 23 can be effectively suppressed. Moreover, by effectively suppressing lifting, the bonding area required to suppress lifting can be kept small. As a result, the effect of the deterioration of the magnetic properties of the stator core 21 due to the generation of strain can be further suppressed. In the first laminated steel sheet 51 and the second laminated steel sheet 52, the core back portions 22 of adjacent electrical steel sheets 40 in the lamination direction are not bonded to each other. Therefore, the effect of the deterioration of the magnetic properties of the stator core 21 due to the generation of strain can be further suppressed.

[0103] Each of the multiple electrical steel sheets 40 has a thickness of 0.10 mm or more and 0.30 mm or less. This makes it possible to reduce iron loss while ensuring the manufacturing efficiency of the stator core 21. In other words, when punching out the electromagnetic steel sheet 40 from material 1, the thickness of the electromagnetic steel sheet 40 depends on the thickness of material 1, and the thickness of material 1 is equal to the thickness of the electromagnetic steel sheet 40. If the thickness of the electromagnetic steel sheet 40 is less than 0.10 mm, the thickness of material 1 will also be less than 0.10 mm. In this case, when punching out the electromagnetic steel sheet 40 from material 1, the number of punches required to achieve a predetermined stacking thickness will increase, reducing the production efficiency of the stator core 21. In addition, the packing factor, which is the proportion of the electromagnetic steel sheet 40 (base steel sheet 2) in the stator core 21, will decrease, which may reduce the magnetic properties of the stator core 21. On the other hand, if the thickness of the electrical steel sheet 40 exceeds 0.30 mm, the electrical steel sheet 40 may be too thick, potentially increasing the iron loss of the stator core 21. It is preferable that the thickness of the electrical steel sheet 40 be 0.27 mm or less.

[0104] In the first step, the teeth portions 23 of the laminated electrical steel sheets 40 are heated to exhibit adhesive properties to the insulating coating 3, thereby bonding the teeth portions 23 of adjacent electrical steel sheets 40 in the lamination direction to form the first laminated steel sheet 51. Therefore, the stator core 21 can be manufactured more easily than, for example, when an adhesive is applied to the electrical steel sheets 40 and the electrical steel sheets 40 are bonded together with the adhesive. The electrical steel sheets 40 are laminated in a state unaffected by the heating in the first step to form the second laminated steel sheet 52. Therefore, it is possible to suppress the unintentional bonding between the electrical steel sheets 40 that form the second laminated steel sheet 52.

[0105] An embodiment of the present invention and its examples have been described above. However, the technical scope of the present invention is not limited to the embodiments and examples described above, and various modifications can be made without departing from the spirit of the invention.

[0106] The adhesive region 41a of the electromagnetic steel sheet 40 forming the first laminated steel sheet 51 is not limited to the form shown in the above embodiment. For example, it may be configured as the adhesive region 41a of the electromagnetic steel sheets 40A to 40D according to the various modifications shown in Figures 8 to 11. In the first modified electromagnetic steel sheet 40A shown in Figure 8, the adhesive region 41a extends towards the base end of the teeth portion 23 compared to the adhesive region 41a of the electromagnetic steel sheet 40 shown in Figure 3. In the adhesive region 41a, the boundary line located on the radially outer side forms a curve that protrudes radially outward. In the second modified electromagnetic steel sheet 40B shown in Figure 9, the entire area of ​​the teeth portion 23 is an adhesive region 41a. In the adhesive region 41a, the boundary line located radially outward is located on the boundary line between the teeth portion 23 and the core back portion 22. In the third modified electromagnetic steel sheet 40C shown in Figure 10, adhesive regions 41a are provided not only at the tip 23a of the tooth portion 23 but also at the side edge 23b. Here, the radial tip 23a of the tooth portion 23 refers to the circumferential edge of the tooth portion 23. In the illustrated example, the tooth portion 23 is formed in a rectangular shape that is elongated in the radial direction when viewed from above. The side edge 23b of the tooth portion 23 refers to the part corresponding to the side located in the circumferential direction when viewed from above. In the illustrated example, the adhesive region 41a is located on the side edge 23b of the tooth portion 23, closer to the tip 23a than to the radial center. In a plan view, the adhesive region 41a is formed in a U-shape that is continuous with the tip 23a and the side edge 23b of the tooth portion 23. In the fourth modified electromagnetic steel sheet 40D shown in Figure 11, similar to the third modified electromagnetic steel sheet 40C shown in Figure 10, adhesive areas 41a are provided not only at the tip 23a of the teeth portion 23 but also at the side edge 23b. However, in the electromagnetic steel sheet 40D shown in Figure 11, the adhesive area 41a is wider than that of the electromagnetic steel sheet 40C shown in Figure 10. Furthermore, the electromagnetic steel sheets 40C and 40D shown in Figures 10 and 11 can be realized in the process of creating the first laminated steel sheet 51 by using a second heating device 141b in addition to the first heating device 141a, as shown by the dashed line in Figure 10. The second heating device 141b is positioned between adjacent teeth portions 23 in the circumferential direction (slots). The second heating device 141b can employ heating elements, coils, etc., similar to the first heating device 141a.

[0107] In the embodiments and modifications described above, all teeth portions 23 within each plane of the electromagnetic steel sheet 40 of the first laminated steel sheet 51 are bonded together, but the present invention is not limited thereto. For example, as in the electromagnetic steel sheet 40E of the fifth modification shown in Figure 12, only some of the teeth portions 23 within the plane are bonded together. In other words, in the first laminated steel sheet 51, some of the multiple sets of teeth portions 23 in adjacent electromagnetic steel sheets 40E in the lamination direction may be bonded together, while the remaining teeth portions 23 are not bonded together. This makes it possible to suppress lifting in some of the teeth portions 23 while suppressing the generation of distortion in the remaining teeth portions 23. In this case, for example, as in the illustrated example, bonded teeth portions 23 and unbonded teeth portions 23 may be arranged alternately in the circumferential direction.

[0108] When forming the first laminated steel sheet 51, the electrical steel sheet 40 may be bonded by applying pressure instead of heating. In the first laminated steel sheet 51, the base ends of the teeth 23 are bonded together, but the tips 23a of the teeth 23 do not need to be bonded together.

[0109] The relationship between the number of sheets N0, N1, N2, and N3 is not limited to the relationship shown in the above embodiment. For example, N1 ≠ ((N0) / 3), N2 ≠ ((N0) / 3), N1 > ((N0) / 3), N2 > ((N0) / 3), N1 ≠ N2, N1 ≠ N3, N2 ≠ N3, N3 <N1であったり、N3<N2であったりしてもよい。

[0110] Of the multiple electrical steel sheets 40, only one of the electrical steel sheets 40, including the electrical steel sheet 40 located at the furthest end of the first side D1 in the lamination direction, and the electrical steel sheet 40 located at the furthest end of the second side D2 in the lamination direction, may form the first laminated steel sheet 51. In other words, the aforementioned N1 and N2 may be 0. In this case, instead of forming two first laminated steel sheets 51, only one first laminated steel sheet 51 needs to be formed, and the first step only needs to be performed once. Since the first step requires time to heat the teeth portion 23, this modified example offers superior productivity because the number of times the first step is performed is reduced.

[0111] As shown in the sixth modified example stator 20A in Figure 13, the stator core 21 can be formed solely from the first laminated steel sheet 51, or in other words, the first laminated steel sheet 51 can be formed from all of the multiple electromagnetic steel sheets 40. That is, the second laminated steel sheet 52 may be omitted, and N3 may be 0. In this case, the effect of the decrease in magnetic properties due to the lifting of the teeth portion 23 can be effectively suppressed.

[0112] For example, the shape of the stator core 21 is not limited to the form shown in the above embodiment. Specifically, the outer and inner diameters of the stator core 21, the stacking thickness, the number of slots, the circumferential and radial dimensional ratios of the teeth portion 23, and the radial dimensional ratio between the teeth portion 23 and the core back portion 22 can be arbitrarily designed according to the desired characteristics of the rotating electric machine. In the rotor 30 of the above embodiment, a pair of permanent magnets 32 form one magnetic pole, but the present invention is not limited to this form. For example, one permanent magnet 32 ​​may form one magnetic pole, or three or more permanent magnets 32 may form one magnetic pole.

[0113] In the above embodiment, a permanent magnet field type electric motor was described as an example of a rotating electric machine 10. However, the structure of the rotating electric machine 10 is not limited to this, as illustrated below, and various other known structures not illustrated below can also be used. In the above embodiment, a permanent magnet field type motor was used as an example to describe the rotating electric machine 10, but the present invention is not limited to this. For example, the rotating electric machine 10 may be a reluctance type motor or an electromagnet field type motor (wound field type motor). In the above embodiment, a synchronous motor was used as an example of an AC motor, but the present invention is not limited thereto. For example, the rotating electric machine 10 may be an induction motor. In the above embodiment, an AC motor was used as an example of the rotating electric machine 10, but the present invention is not limited thereto. For example, the rotating electric machine 10 may be a DC motor. In the above embodiment, an electric motor was used as an example of the rotating electric machine 10, but the present invention is not limited thereto. For example, the rotating electric machine 10 may be a generator.

[0114] Furthermore, without departing from the spirit of the present invention, the components in the above embodiments may be replaced with well-known components as appropriate, and the above-described modifications may be combined as appropriate.

[0115] Next, verification tests were conducted to verify the effects described above. In these verification tests, stators were manufactured, and the energy loss in a rotating magnetic field was measured for these stators based on the method described in Japanese Patent No. 2740553 (method for measuring iron loss in a rotating magnetic field). This energy loss was then evaluated as the loss of the stator core (hereinafter also referred to as the laminated core). As verification tests, we conducted the first verification test and the second verification test.

[0116] (First verification test) In the first verification test, we verified the effects based on (1) all electrical steel sheets in the lamination direction being bonded, (2) electrical steel sheets on both sides in the lamination direction being bonded, while the central electrical steel sheet is not bonded, and (3) electrical steel sheets on both sides in the lamination direction being bonded by an insulating coating with adhesive properties. In this verification test, the losses of the laminated cores were evaluated for the stators of Comparative Examples 1, 2, and 3, and the stators of Examples 1, 2, and 3.

[0117] In all of the stators of Comparative Examples 1, 2, and 3, and the stators of Examples 1, 2, and 3, the stator 20 according to the embodiment shown in Figures 1 to 6 above is used as the basic structure, and the following points were modified from this stator 20. Specifically, the thickness of the electrical steel sheet was set to 0.25 mm, and the number of electrical steel sheets in the laminated core was set to 99.

[0118] Furthermore, in the stator of Comparative Example 1, all 99 electromagnetic steel sheets were left unbonded. In the stator of Comparative Example 2, all 99 electromagnetic steel sheets were bonded together using adhesive applied to the surface of the electromagnetic steel sheets during the lamination process. In the stator of Comparative Example 3, of the 99 electromagnetic steel sheets, 33 sheets on each side of the lamination direction (1 / 3 of the total) were bonded together using adhesive applied to the surface of the electromagnetic steel sheets during the lamination process, while the 33 sheets in the center of the lamination direction (1 / 3 of the total) were not bonded. In the stator of Example 1, all 99 electromagnetic steel sheets were bonded together. In the stator of Example 2, of the 99 electromagnetic steel sheets, 33 sheets on each side of the lamination direction (1 / 3 of the total) were bonded together, while the 33 sheets in the center of the lamination direction (1 / 3 of the total) were not bonded. In the stator of Example 3, of the 99 electrical steel sheets, 33 sheets (1 / 3 of the total) were bonded from one end in the lamination direction, and the remaining 66 sheets (2 / 3 of the total) were not bonded.

[0119] For each of the stators in Comparative Examples 1, 2, and 3, and Examples 1, 2, and 3, we checked the iron loss of the laminated core and whether or not there was any lifting of the teeth. Iron loss is based on the energy loss generated within the laminated core. The energy loss value used to calculate iron loss was determined by applying search coils to four different locations circumferentially on the back of the core and magnetizing them to an average of 1.0T. The iron loss (W / kg) was then calculated from this energy loss and the weight of each laminated core. The above energy loss was calculated from the difference in induced torque between when an excitation current was applied to an excitation yoke located in the center of the laminated core while the core was rotating at 300 rpm, and when the excitation current was cut off. In other words, the energy loss was determined by utilizing the relationship that the product of the induced torque and the rotational speed is equal to the energy generated within the laminated core. The lifting of the teeth was evaluated by the ratio of the tooth thickness T2 in the unloaded state to the tooth thickness T1 in the tooth state with a pressure of 1.0 MPa applied (i.e., T2 / T1). Both thicknesses T1 and T2 were measured with calipers, and the tooth thickness T2 in the unloaded state was measured when the caliper was in contact with the steel plate of the teeth. A ratio T2 / T1 of 1.06 or less was judged as ◎, greater than 1.06 to 1.15 as ○, and greater than 1.15 as ×, with ◎ and ○ being judged as good.

[0120] The results are shown in Table 1 below.

[0121] [Table 1]

[0122] From the above, Examples 1, 2, and 3 showed improved iron loss compared to Comparative Example 1 and comparative examples with the same bonding range (Comparative Example 2 compared to Example 1, and Comparative Example 3 compared to Example 2). In Example 3, although the ratio T2 / T1 was within the good range, lifting was observed on the teeth on the unbonded side. Therefore, Example 2 showed improved iron loss compared to Example 3. Furthermore, the improvement in iron loss in the case of bonding on both sides (Example 2, Comparative Example 3) compared to the case of bonding on the entire layer (Example 1, Comparative Example 2) was more pronounced in the case of bonding with an insulating coating having adhesive properties (Example 1: 1.57 W / kg, Example 2: 1.10 W / kg) than in the case of bonding with adhesive application (Comparative Example 2: 1.73 W / kg, Comparative Example 3: 1.53 W / kg). This is thought to be related to the decrease in the packing factor due to the applied adhesive and the increase in vibration in the non-adhered region mentioned above.

[0123] (Second verification test) In the second verification test, we examined the differences in effectiveness based on the number of sheets that were bonded together. In this verification test, the loss of the stacked core was evaluated for the stators of Examples 11 to 15.

[0124] In all of the stators of Examples 11 to 15, the stator 20 according to the embodiment shown in Figures 1 to 6 above is used as the basic structure, and the following changes were made to this stator 20. Specifically, the thickness of the electromagnetic steel sheet was set to 0.25 mm, and the number of electromagnetic steel sheets in the laminated core was set to 99.

[0125] Based on this, the stators for each of the 11 to 15 embodiments were set as follows. In the stator of Example 11, of the 99 electrical steel sheets, 10 sheets on each side of the lamination direction (10.1% of the total number of sheets) were bonded, while the 79 sheets located in the center of the lamination direction (79.8% of the total number of sheets) were not bonded. In the stator of Example 12, of the 99 electrical steel sheets, 20 sheets on each side of the lamination direction (20.2% of the total number of sheets) were bonded, while 59 sheets located in the center of the lamination direction (59.6% of the total number of sheets) were not bonded. In the stator of Example 13, of the 99 electrical steel sheets, 30 sheets on each side of the lamination direction (30.3% of the total) were bonded, while 39 sheets located in the center of the lamination direction (39.4% of the total) were not bonded. In the stator of Example 14, of the 99 electrical steel sheets, 33 sheets on each side of the lamination direction (1 / 3 of the total number of sheets) were bonded, while 33 sheets located in the center of the lamination direction (1 / 3 of the total number of sheets) were not bonded. In the stator of Example 15, of the 99 electrical steel sheets, 40 sheets on each side of the lamination direction (40.4% of the total number of sheets) were bonded, while 19 sheets located in the center of the lamination direction (19.2% of the total number of sheets) were not bonded. The iron loss of the laminated core was evaluated for each of the stators in Examples 11 to 15. The evaluation method was the same as that used in the first verification test.

[0126] The results are shown in Table 2 below.

[0127] [Table 2]

[0128] From the above, it was confirmed that the iron loss improved from Example 11 to Example 14, and that the iron loss in Example 14 was even better than in Example 15. From these results, it was confirmed that it is more preferable for the number of sheets N1, N2, and N3 to all be equal. [Explanation of Symbols]

[0129] 3. Insulating coating 21 Stator Core 22 Core back section 23 Teeth Department 23a tip 40, 40A, 40B, 40C, 40D, 40E electrical steel sheet 51 1st laminated steel plate 52 2nd laminated steel plate D1 First side D2 2nd side

Claims

1. A laminated core formed by stacking multiple electromagnetic steel sheets having an insulating coating, Each of the aforementioned plurality of electrical steel sheets comprises an annular core back portion and a plurality of teeth portions that protrude radially from the core back portion and are spaced apart in the circumferential direction of the core back portion. Of the plurality of electrical steel sheets, at least one of a portion of the electrical steel sheets, including the electrical steel sheet located at the furthest end on the first side in the lamination direction, and a portion of the electrical steel sheets, including the electrical steel sheet located at the furthest end on the second side in the lamination direction, forms a first laminated steel sheet in which, in some of the multiple teeth portions arranged at intervals in the circumferential direction of the core back portion, the teeth portions of adjacent electrical steel sheets in the lamination direction are bonded to each other, and in the remaining teeth portions, the teeth portions of adjacent electrical steel sheets in the lamination direction are not bonded to each other; and the remaining electrical steel sheets that do not form the first laminated steel sheet form a second laminated steel sheet in which the teeth portions of adjacent electrical steel sheets in the lamination direction are not bonded to each other. A laminated core in which the insulating coatings of each electrical steel sheet are bonded together in the teeth portion of the first laminated steel sheet.

2. Among the plurality of electrical steel sheets, a portion of the electrical steel sheets, including the electrical steel sheet located at the furthest end on the first side in the lamination direction, and a portion of the electrical steel sheets, including the electrical steel sheet located at the furthest end on the second side in the lamination direction, all form the first laminated steel sheet. The laminated core according to claim 1, wherein the remaining electrical steel sheet located in the center of the lamination direction among the plurality of electrical steel sheets forms the second laminated steel sheet.

3. The laminated core according to claim 2, wherein the number of electromagnetic steel sheets forming the second laminated steel sheet in the center of the lamination direction is equal to or greater than the number of electromagnetic steel sheets forming the first laminated steel sheet on the first side of the lamination direction, and equal to or greater than the number of electromagnetic steel sheets forming the first laminated steel sheet on the second side of the lamination direction.

4. The laminated core according to claim 2 or 3, wherein the number of electromagnetic steel sheets forming the first laminated steel sheet on the first side in the lamination direction, and the number of electromagnetic steel sheets forming the first laminated steel sheet on the second side in the lamination direction, are both 1 / 3 or less of the total number of the plurality of electromagnetic steel sheets.

5. A laminated core according to any one of claims 2 to 4, wherein the number of electromagnetic steel sheets forming the first laminated steel sheet on the first side in the lamination direction is equal to the number of electromagnetic steel sheets forming the first laminated steel sheet on the second side in the lamination direction.

6. The laminated core according to claim 5, wherein the number of electromagnetic steel sheets forming the first laminated steel sheet on the first side in the lamination direction, and the number of electromagnetic steel sheets forming the first laminated steel sheet on the second side in the lamination direction, are equal to the number of electromagnetic steel sheets forming the second laminated steel sheet in the center in the lamination direction.

7. The laminated core according to any one of claims 1 to 6, wherein in the first laminated steel sheet, the teeth portions of adjacent electrical steel sheets in the lamination direction are not crimped to each other and are not welded to each other.

8. The laminated core according to any one of claims 1 to 7, wherein at least the portions of the teeth of the first laminated steel sheet that include the radial tip are bonded together.

9. The laminated core according to any one of claims 1 to 8, wherein in the first laminated steel sheet, the core back portions of adjacent electrical steel sheets in the lamination direction are not bonded to each other.

10. The laminated core according to any one of claims 1 to 9, wherein the thickness of each of the plurality of electrical steel sheets is 0.10 mm or more and 0.30 mm or less.

11. A method for manufacturing a laminated core according to any one of claims 1 to 10, A method for manufacturing a laminated core, comprising a first step of forming the first laminated steel sheet by heating a portion of the teeth of the laminated electromagnetic steel sheet to allow it to adhere to the insulating coating.

12. A method for manufacturing a laminated core according to any one of claims 1 to 10, A first step is to form the first laminated steel sheet by heating a portion of the teeth of the laminated electrical steel sheet to allow it to adhere to the insulating coating, A second step involves stacking the electrical steel sheets in a state unaffected by the heating in the first step to form the second stacked steel sheet, A method for manufacturing a laminated core, comprising a third step of stacking the first laminated steel sheet and the second laminated steel sheet after the first and second steps.

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