JP7595407B2 - Laminated core and rotating electrical machine - Google Patents

Description

The present invention relates to a laminated core and a rotating electric machine.

Conventionally, laminated cores such as those described in the following Patent Document 1 have been known. In this laminated core, adjacent electromagnetic steel sheets in the lamination direction are bonded together.

JP 2011-023523 A

The conventional laminated core has room for improvement in terms of improving the laminate fixing strength without degrading the magnetic properties.

The present invention was made in consideration of the above-mentioned circumstances, and aims to improve the laminate fixing strength without degrading the magnetic properties of the laminated core.

In order to solve the above problems, the present invention proposes the following means.
[1] A laminated core comprising: a plurality of electromagnetic steel sheets stacked on top of each other and coated on both sides with an insulating coating; adhesive portions provided between adjacent electromagnetic steel sheets in the stacking direction and bonding the electromagnetic steel sheets together; and welded portions at which the electromagnetic steel sheets are welded together, wherein the electromagnetic steel sheets comprise an annular core back portion and a plurality of teeth portions protruding radially from the core back portion and arranged at intervals in the circumferential direction of the core back portion, wherein the adhesive portions are provided on the teeth portions and the welded portions are provided on the core back portion by welding, the welded portions are provided along the outer circumferential edge of the core back portion , and the teeth portions are joined only by the adhesive portions .
[2] A laminated core as described in [1], having only the adhesive portion formed by adhesive on the teeth portion and the weld portion formed by welding on the core back portion.
[3] The laminated core according to [1] or [2], wherein the adhesive portions are dot-shaped with an average diameter of 3 to 7 mm.
[4] The laminated core according to any one of [1] to [3], wherein the adhesive area ratio of the electromagnetic steel sheets by the adhesive joint is 1 to 40%.
[5] The laminated core according to any one of [1] to [4], wherein the aluminum content of the electromagnetic steel sheets is 0.001 to 2.0 mass %.
[6] A rotating electric machine comprising the laminated core according to any one of [1] to [5].

According to the present invention, it is possible to improve the laminate fixing strength without degrading the magnetic properties of the laminated core.

1 is a plan view of a rotating electrical machine including a laminated core according to an embodiment of the present invention; FIG. 2 is a side view of the laminated core shown in FIG. FIG. 2 is a partial plan view of a first surface of an electromagnetic steel sheet in a laminated core according to an embodiment of the present invention. FIG. 4 is a partial plan view of a first surface of an electromagnetic steel sheet in a laminated core according to another embodiment of the present invention.

The following describes a laminated core according to one embodiment of the present invention and a rotating electric machine equipped with this laminated core, with reference to the drawings. In this embodiment, the rotating electric machine is described using an electric motor, specifically an AC motor, more specifically a synchronous motor, and even more specifically a permanent magnet field type electric motor, as an example. This type of electric motor is suitable for use in electric vehicles, for example.

1 , the rotating electric machine 10 includes a stator 20, a rotor 30, a case 50, and a rotating shaft 60. The stator 20 and the rotor 30 are housed in the case 50. The stator 20 is fixed to the case 50.
In this embodiment, an inner rotor type rotating electric machine 10 is used in which the rotor 30 is located inside the stator 20. However, an outer rotor type rotating electric machine 10 in which the rotor 30 is located outside the stator 20 may also be used. Also, in this embodiment, the rotating electric machine 10 is a three-phase AC motor with 12 poles and 18 slots. 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 rotation speed of 1000 rpm by applying an excitation current of, for example, 10 A effective value and a frequency of 100 Hz to each phase.

The stator 20 includes a stator core 21 and a winding (not shown).
The stator core 21 includes an annular core back portion 22 and a plurality of teeth portions 23. The core back portion 22 is an area surrounded by an outer peripheral edge 22a of the core back portion and an inner peripheral edge 22b of the core back portion (indicated by a broken line in FIG. 3). Hereinafter, the direction of the central axis O of the stator core 21 (or the core back portion 22) is referred to as the axial direction, the radial direction of the stator core 21 (or the core back portion 22) (the direction perpendicular to the central axis O) is referred to as the radial direction, and the circumferential direction of the stator core 21 (or the core back portion 22) (the direction going around the central axis O) is referred to as the circumferential direction.

The core back portion 22 is formed in an annular shape when viewed in a plan view of the stator 20 in the axial direction.
The multiple teeth portions 23 protrude radially inward from the core back portion 22 (toward the central axis O of the core back portion 22 along the radial direction). The multiple teeth portions 23 are arranged at equal 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 have the same shape and size as one another. Eighteen approximately trapezoidal slots 24 are formed radially between the multiple teeth portions 23.
The winding is wound around the teeth portion 23. The winding may be a concentrated winding or a distributed winding.

The rotor 30 is disposed radially inward of the stator 20 (the stator core 21). The rotor 30 includes a rotor core 31 and a plurality of permanent magnets 32.
The rotor core 31 is formed in an annular (circular) shape and is disposed coaxially with the stator 20. The rotating shaft 60 is disposed within the rotor core 31. The rotating shaft 60 is fixed to the rotor core 31.
The permanent magnets 32 are fixed to the rotor core 31. In this embodiment, a pair of the permanent magnets 32 form one magnetic pole. The pairs of the permanent magnets 32 are arranged at equal intervals in the circumferential direction. In this embodiment, 12 pairs of the permanent magnets 32 (total of 24 magnets) are provided at central angle intervals of 30 degrees around the central axis O.

In this embodiment, an embedded magnet motor is used as the permanent magnet field type motor. The rotor core 31 is formed with a plurality of through holes 33 that pass through the rotor core 31 in the axial direction. The plurality of through holes 33 are provided corresponding to a plurality of permanent magnets 32. Each permanent magnet 32 is fixed to the rotor core 31 while being disposed in the corresponding through hole 33. Each permanent magnet 32 can be fixed to the rotor core 31, 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 motor may be used as the permanent magnet field type motor instead of the embedded magnet motor.

Both the stator core 21 and the rotor core 31 are laminated cores. As shown in Fig. 2, the stator 20 is formed by laminating a plurality of electromagnetic steel sheets 40. Welded portions 42 are formed on the outer circumferential surface of the stator 20. The welded portions 42 join the electromagnetic steel sheets 40 adjacent to each other in the lamination direction.
The lamination thickness of each of the stator core 21 and the rotor core 31 is, for example, 50.0 mm. The outer diameter of the stator core 21 is, for example, 250.0 mm. The inner diameter of the stator core 21 is, 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 merely examples, and the lamination thickness, outer diameter, and inner diameter of the stator core 21 and the lamination 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 portions of the teeth portions 23 of the stator core 21. The inner diameter of the stator core 21 is the diameter of an imaginary circle inscribed in the tips of all the teeth portions 23.

Each of the electromagnetic steel sheets 40 forming the stator core 21 and the rotor core 31 is formed, for example, by punching an electromagnetic steel sheet as a base material.
The electrical steel sheet 40 contains the elements carbon (C), silicon (Si), manganese (Mn), aluminum (Al), phosphorus (P), sulfur (S), nitrogen (N), and tin (Sn), with the remainder being iron (Fe) and impurities. The impurities refer to components contained in raw materials or components mixed in during the manufacturing process, but not intentionally contained in the steel sheet.

The carbon content (also referred to as C content) of the electromagnetic steel sheet 40 is preferably more than 0 and 0.01 mass % or less with respect to the mass of the electromagnetic steel sheet 40 .
The silicon content (also referred to as the Si content) of the electromagnetic steel sheet 40 is preferably 2.0 to 4.0 mass % relative to the mass of the electromagnetic steel sheet 40 .
The manganese content (also referred to as Mn content) of the electromagnetic steel sheet 40 is preferably 0.1 to 4.0 mass % relative to the mass of the electromagnetic steel sheet 40 .
The aluminum content (also referred to as the Al content) of the electromagnetic steel sheets 40 will be described later.
The phosphorus content (also referred to as the P content) of the electromagnetic steel sheet 40 is preferably more than 0 and 0.2 mass % or less, relative to the mass of the electromagnetic steel sheet 40 .
The sulfur content (also referred to as S content) of the electrical steel sheet 40 is preferably more than 0 and 0.006 mass % or less, relative to the mass of the electrical steel sheet 40 .
The nitrogen content (also referred to as N content) of the electromagnetic steel sheet 40 is preferably more than 0 and 0.005 mass % or less, relative to the mass of the electromagnetic steel sheet 40 .
The tin content (also referred to as Sn content) of the electromagnetic steel sheet 40 is preferably more than 0 and 0.10 mass % or less, relative to the mass of the electromagnetic steel sheet 40 .

The Al content of the electromagnetic steel sheet 40 is preferably 0.001 to 2.0 mass%, more preferably 0.01 to 2.0 mass%, and even more preferably 0.03 to 2.0 mass%, relative to the mass of the electromagnetic steel sheet 40. If the Al content of the electromagnetic steel sheet 40 is equal to or greater than the above lower limit, it promotes deoxidation of the molten pool when welding the electromagnetic steel sheet 40, and makes it easier to suppress the occurrence of welding blowholes. This allows the weld bead width to be widened, making it easier to suppress the occurrence of welding defects. If the Al content of the electromagnetic steel sheet 40 is equal to or less than the above upper limit, it makes it easier to improve the mechanical strength of the electromagnetic steel sheet 40.

The content of elements contained in the electrical steel sheet 40 can be measured by common analytical methods. For example, it can be measured using ICP-AES (Inductively Coupled Plasma-Atomic Emission Spectrometry). The C content and S content can be measured using the combustion-infrared absorption method. The N content can be measured using the inert gas fusion-thermal conductivity method.

In order to improve the workability of the electromagnetic steel sheet and the iron loss of the laminated core, both sides of the electromagnetic steel sheet 40 are covered with an insulating coating. Examples of the material constituting the insulating coating include (1) an inorganic compound, (2) an organic resin, and (3) a mixture of an inorganic compound and an organic resin. Examples of the inorganic compound include (1) a complex of dichromate and boric acid, and (2) a complex of phosphate and silica. Examples of the organic resin include epoxy resin, acrylic resin, acrylic styrene resin, polyester resin, silicone resin, and fluororesin.
The organic resin may be the same as or different from the organic resin contained in the adhesive described below.

In order to ensure the insulating performance between the stacked magnetic steel sheets 40, the thickness of the insulating coating (thickness per one side of the magnetic steel sheets 40) is preferably 0.1 μm or more.
On the other hand, as the insulating coating becomes thicker, the insulating effect becomes saturated. Also, as the insulating coating becomes thicker, the space factor decreases, and the performance as a laminated core decreases. Therefore, it is better for the insulating coating to be thin as long as the insulating performance can be ensured. The thickness of the insulating coating (thickness per one side of the magnetic steel sheet 40) is preferably 0.1 μm or more and 5 μm or less, and more preferably 0.1 μm or more and 2 μm or less.
The thickness of the insulating coating can be measured, for example, by observing a cross section obtained by cutting the electromagnetic steel sheet 40 in the thickness direction using a microscope or the like.

As the electromagnetic steel sheet 40 becomes thinner, the iron loss improvement effect gradually saturates. Furthermore, as the electromagnetic steel sheet 40 becomes thinner, the manufacturing cost of the electromagnetic steel sheet 40 increases. Therefore, in consideration of the iron loss improvement effect and the manufacturing cost, it is preferable that the thickness of the electromagnetic steel sheet 40 be 0.10 mm or more.
On the other hand, if the electromagnetic steel sheet 40 is too thick, it becomes difficult to perform the press punching operation on the electromagnetic steel sheet 40. Therefore, in consideration of the press punching operation on the electromagnetic steel sheet 40, it is preferable that the thickness of the electromagnetic steel sheet 40 be 0.65 mm or less.
Furthermore, the iron loss increases as the thickness of the electromagnetic steel sheet 40 increases. Therefore, in consideration of the iron loss characteristics of the electromagnetic steel sheet 40, the thickness of the electromagnetic steel sheet 40 is preferably 0.35 mm or less, more preferably 0.25 mm or less, and even more preferably 0.20 mm or less.
In consideration of the above, the thickness of each of the electromagnetic steel sheets 40 is, for example, preferably 0.10 mm to 0.65 mm, more preferably 0.10 mm to 0.35 mm, even more preferably 0.10 mm to 0.25 mm, and particularly preferably 0.10 mm to 0.20 mm. The thickness of the electromagnetic steel sheet 40 also includes the thickness of the insulating coating.
The thickness of the electromagnetic steel sheet 40 can be measured using, for example, a micrometer.

The electromagnetic steel sheets 40 of the present embodiment are not provided with any grooves for injecting adhesive to form the adhesive portions 41. This reduces the complexity involved in punching the electromagnetic steel sheets 40 and stacking and adhering the electromagnetic steel sheets 40 when manufacturing a laminated core.
From the viewpoint of applying a large tension between the electromagnetic steel sheets 40 to reduce iron loss, the arithmetic mean roughness (Ra) of the electromagnetic steel sheets 40 is preferably 0.5 μm or less, and more preferably 0.3 μm or less. The lower limit of Ra of the electromagnetic steel sheets 40 is not particularly limited, but is preferably 0.1 μm, for example.
The Ra of the electromagnetic steel sheet 40 can be measured in accordance with the method described in JIS B0601:2013.

As shown in FIG. 2, the multiple electromagnetic steel sheets 40 that form the stator core 21 are stacked in the thickness direction. The thickness direction is the thickness direction of the electromagnetic steel sheets 40, which corresponds to the stacking direction of the electromagnetic steel sheets 40.

As shown in FIG. 3, the multiple electromagnetic steel sheets 40 that form the stator core 21 are fixed together by adhesive portions 41 and welded portions 42 provided on the surface (first surface) 40a of the electromagnetic steel sheets 40. FIG. 3 shows approximately half of a plan view of the stator 20.

The adhesive portion 41 is a series of adhesive that is provided between the electromagnetic steel sheets 40 adjacent to each other in the stacking direction and hardens without being separated. As the adhesive, for example, a thermosetting adhesive that uses polymerization bonding or the like is used.
As the adhesive composition, (1) an acrylic resin, (2) an epoxy resin, (3) a composition containing an acrylic resin and an epoxy resin, and the like can be used.

The tensile modulus of the adhesive is preferably 2500 MPa to 5000 MPa, and more preferably 3000 MPa to 4000 MPa. If the tensile modulus of the adhesive is equal to or greater than the lower limit, it is easy to prevent a decrease in the rigidity of the laminated core. If the tensile modulus of the adhesive is equal to or less than the upper limit, it is easy to prevent the stress strain applied to the electromagnetic steel sheet 40 from increasing, and to prevent a deterioration in the magnetic properties of the laminated core.

The tensile modulus of the cured adhesive, i.e., the adhesive joint 41, is measured by a resonance method. Specifically, the tensile modulus is measured in accordance with JIS R1602:1995.
The tensile modulus of elasticity of the cured adhesive can be adjusted by the type, physical properties, molecular weight, amount added, etc. of the resin contained in the adhesive. For example, when the molecular weight of the resin contained in the adhesive is reduced, the tensile modulus of elasticity tends to increase.

As an adhesion method, for example, a method in which an adhesive is applied to the electromagnetic steel sheet 40 and then the electromagnetic steel sheet 40 is adhered by either or both of heating and compression bonding can be adopted.
The heating means may be any means, such as heating in a high-temperature bath or electric furnace, or direct application of electricity.

In order to obtain a stable and sufficient adhesive strength, the thickness of the adhesive portion 41 is preferably 1 μm or more.
On the other hand, when the thickness of the adhesive portion 41 exceeds 100 μm, the adhesive strength is saturated. Also, as the adhesive portion 41 becomes thicker, the space factor decreases, and the magnetic properties such as the core loss of the laminated core deteriorate. Therefore, the thickness of the adhesive portion 41 is preferably 1 μm or more and 100 μm or less, and more preferably 1 μm or more and 10 μm or less.
The thickness of the adhesive portion 41 can be measured in the same manner as the thickness of the insulating coating.
The thickness of the adhesive portion 41 can be adjusted by changing the type and amount of adhesive applied to the electromagnetic steel sheet 40 .

3, the adhesive portion 41 is formed in the form of a plurality of circular dots. More specifically, the adhesive portion 41 is formed in the form of dots having an average diameter of 5 mm on each of the teeth 23.
The average diameter shown here is an example. The average diameter of the dot-like adhesive portions 41 is preferably 3 to 7 mm. When the average diameter is equal to or greater than the lower limit, the magnetic steel sheets 40 can be easily bonded together sufficiently. When the average diameter is equal to or less than the upper limit, the iron loss of the laminated core can be easily suppressed.
The average diameter is obtained by using a ruler to measure the diameter of the adhesive trace in the adhesive joint 41 after peeling the electromagnetic steel sheets 40 from each other. If the shape of the adhesive trace in plan view is not a perfect circle, the diameter is the diameter of the circumscribing circle (perfect circle) of the adhesive trace in plan view.
The formation pattern of the adhesive portions 41 in FIG. 3 is one example, and the number, shape, and arrangement of the adhesive portions 41 provided between the electromagnetic steel sheets 40 can be appropriately changed as necessary.

Generally, when an adhesive is cured, curing shrinkage occurs. This curing shrinkage applies compressive stress and tensile stress to the electromagnetic steel sheet 40. When these stresses are applied to the electromagnetic steel sheet 40, distortion occurs. In particular, in the case of a thermosetting adhesive, the applied stress becomes large due to the difference in the thermal expansion coefficient between the electromagnetic steel sheet 40 and the adhesive portion. Distortion of the electromagnetic steel sheet 40 increases the iron loss of the rotating electric machine 10.
The influence of the distortion of the electromagnetic steel sheets 40 constituting the stator core 21 on the iron loss is greater than the influence of the distortion of the steel sheets constituting the rotor core 31 .
In this embodiment, since the adhesive portion 41 is provided partially, the stress applied to the electromagnetic steel sheet 40 due to hardening shrinkage is reduced compared to when the adhesive portion 41 is provided over the entire surface.

The adhesive area ratio of the adhesive portion 41 to the electromagnetic steel sheet 40 is preferably 1 to 40%, more preferably 1 to 30%, and even more preferably 1 to 20%. When the adhesive area ratio is equal to or greater than the lower limit, the mechanical strength of the laminated core is ensured. When the adhesive area ratio is equal to or less than the upper limit, the iron loss suppression effect is more excellent.
The adhesive area ratio of the electromagnetic steel sheet 40 by the adhesive portion 41 is the ratio of the area of the region (adhesive region) on the first surface where the adhesive portion 41 is provided to the area of the first surface of the electromagnetic steel sheet 40. The region where the adhesive portion 41 is provided is a region (adhesive region) on the first surface of the electromagnetic steel sheet 40 where a continuous, hardened adhesive is provided without being separated. The area of the region where the adhesive portion 41 is provided can be found, for example, by photographing the first surface of the electromagnetic steel sheet 40 after peeling and performing image analysis on the photographed result.
The area of the first surface of the electromagnetic steel sheet 40 also includes the area of the welded portion 42 described below.

As shown in FIG. 3, a welded portion 42 is provided along the outer peripheral edge 22a of the core back portion 22 of the electromagnetic steel sheet 40. That is, the electromagnetic steel sheets 40 are joined together by using both the adhesive portion 41 and the welded portion 42. By using both the adhesive portion 41 and the welded portion 42, the laminated fixing strength of the stator 20 can be improved compared to fixing the same area by adhesion alone. In addition, by using both the adhesive portion 41 and the welded portion 42, the electromagnetic steel sheets 40 can be laminated together with high precision. This can further improve the magnetic properties of the laminated core.

The welded portion 42 is formed of a weld metal. Here, the weld metal means a metal in which the electromagnetic steel sheet 40 and the welding wire are melted and mixed together.
The welded portion 42 is formed, for example, by arc welding the electromagnetic steel sheets 40 together using a welding wire. As the welding wire, solid wires of various component systems can be used.

In the present embodiment, the welded portion 42 is formed on the outer circumferential edge 22 a of the core back portion 22 of the first surface 40 a of the electromagnetic steel sheet 40 .
3, welded portions 42 are provided intermittently along the outer peripheral edge 22a on the outside of the outer peripheral edge 22a of the core back portion 22. A portion of the welded portion 42 is embedded into the inner side of the outer peripheral edge 22a of the core back portion 22.
3, the welded portions 42 are formed at six locations along the circumferential direction. The welded portions 42 are formed at positions corresponding to the teeth portions 23. The welded portions 42 are formed at every third location on the teeth portions 23. In other words, six welded portions 42 are provided at central angle intervals of 60 degrees around the central axis O.
The circumferential width (bead width) of the welded portion 42 is, for example, preferably 1 to 10 mm, more preferably 2 to 8 mm, and even more preferably 3 to 6 mm. When the bead width of the welded portion 42 is equal to or greater than the above-mentioned lower limit, the lamination fixing strength of the stator 20 can be further improved. When the bead width of the welded portion 42 is equal to or less than the above-mentioned upper limit, the magnetic characteristics of the stator 20 are easily maintained. The bead width of the welded portion 42 in FIG. 3 is 4 mm. The bead width of the welded portion 42 can be measured, for example, with a ruler.
When the welded portion 42 is provided as shown in Figure 3, the ratio of the size (bead width) of the welded portion 42 to 100% of the length of the outer peripheral edge 22a of the core back portion 22 of the first surface 40a of the electromagnetic steel sheet 40 is, for example, 3%.
The length of the outer peripheral edge 22 a is determined from the outer diameter of the stator core 21 , for example.

As shown in Fig. 4, the welded portion 42 is provided at 18 positions at 20 degree intervals around the central axis O along the outer peripheral edge 22a of the core back portion 22 on the outside of the outer peripheral edge 22a. Fig. 4 shows approximately half of a plan view of the stator 20A. A part of the welded portion 42 is embedded in the inner side of the outer peripheral edge 22a of the core back portion 22. In the example shown in Fig. 4, the welded portion 42 is shifted from the tooth portion 23 in the circumferential direction. The welded portion 42 is provided at a position corresponding to the slot 24 on the outer peripheral edge 22a of the core back portion 22. That is, the welded portion 42 is not provided on the portion of the outer peripheral edge 22a of the core back portion 22 located radially outside the tooth portion 23.
By providing the welded portions 42 at 18 locations along the outer peripheral edge 22 a of the core back portion 22 , the lamination fixing strength of the stator 20</b>A can be further improved compared to the stator 20 .
When the welded portion 42 is provided as shown in Figure 4, the ratio of the size (bead width) of the welded portion 42 to 100% of the length of the outer peripheral edge 22a of the core back portion 22 of the first surface 40a of the electromagnetic steel sheet 40 is, for example, 9%.

The formation pattern of the welds 42 in Figures 3 and 4 is one example, and the number, shape, and arrangement of the welds 42 provided between the electromagnetic steel sheets 40 can be changed as necessary.

As a welding method, for example, a method can be adopted in which the electromagnetic steel sheets 40 are fixed with an adhesive, a welding wire is placed on the outer peripheral edge 22a of the core back portion 22 along the stacking direction of the electromagnetic steel sheets 40, and welding is performed by arc welding.
The welding method may be, for example, a method in which an adhesive is applied to the electromagnetic steel sheet 40, a welding wire is placed on the outer peripheral edge 22a of the core back portion 22 of the electromagnetic steel sheet 40, and the sheets are bonded by either or both of heating and crimping, and then welded by arc welding.
Another welding method is laser welding.

In this embodiment, the multiple electromagnetic steel sheets 40 that form the rotor core 31 are fixed to each other by crimping C (dowels). However, the multiple electromagnetic steel sheets that form the rotor core may be bonded to each other by either or both of adhesive joints and welded joints.
Incidentally, the laminated cores such as the stator core 21 and the rotor core 31 may be formed by so-called rotational lamination.

As described above, the stator core 21 (laminated core) according to this embodiment has a plurality of adhesive portions 41 provided on the teeth portion 23, and welded portions 42 provided intermittently along the outer peripheral edge 22a of the core back portion 22.
This configuration can further improve the lamination fixing strength of the stator 20. In addition, by using the adhesive parts 41 and the welded parts 42 in combination, the electromagnetic steel sheets 40 can be laminated with high precision. This can suppress deterioration of the magnetic properties of the laminated core.

The technical scope of the present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the spirit of the present invention.

The shape of the stator core is not limited to the shape shown in the above embodiment. Specifically, the outer and inner diameters of the stator core, the lamination thickness, the number of slots, the circumferential and radial dimensional ratios of the teeth portion 23, and the radial dimensional ratios of the teeth portion 23 and the core back portion 22 can be designed as desired according to the characteristics of the rotating electric machine.

In the rotor of the above embodiment, a pair of permanent magnets 32 form one magnetic pole, but the present invention is not limited to this. For example, one permanent magnet 32 may form one magnetic pole, or three or more permanent magnets 32 may form one magnetic pole.

In the above embodiment, a permanent magnet field type electric motor has been used as an example of a rotating electric motor, but the structure of the rotating electric motor is not limited to this, as exemplified below, and various known structures not exemplified below can also be adopted.
In the above embodiment, a permanent magnet field motor is used as an example of a synchronous motor, but the present invention is not limited to this. For example, the rotating electric machine may be a reluctance motor or an electromagnetic field motor (wound field motor).
In the above embodiment, a synchronous motor is used as an example of an AC motor, but the present invention is not limited to this. For example, the rotating electric machine may be an induction motor.
In the above embodiment, an AC motor is used as an example of the electric motor, but the present invention is not limited to this. For example, the rotating electric machine may be a DC motor.
In the above embodiment, an electric motor is used as an example of a rotating electric machine, but the present invention is not limited to this. For example, the rotating electric machine may be a generator.

In the above embodiment, the laminated core according to the present invention is applied to a stator core, but it can also be applied to a rotor core.

In addition, the components in the above embodiment may be replaced with well-known components as appropriate without departing from the spirit of the present invention, and the above-mentioned modifications may be combined as appropriate.

The present invention will be explained in more detail below with reference to examples and comparative examples, but the present invention is not limited to the following examples.

[Example 1]
As shown in Fig. 3, adhesive was applied in dots to the teeth portions on the first surfaces of the electromagnetic steel sheets, and a plurality of electromagnetic steel sheets were stacked and pressed together to obtain a laminate. Welding wire was placed at six locations on the outer periphery of the core back portion along the stacking direction of the obtained laminate, and welds were formed by arc welding to obtain a laminated core.
The bonding area ratio to the area of the first surface of the electromagnetic steel sheet was set to 1%.
The ratio of the size of the welded portion (bead width) to the outer circumferential length of the core-back portion of the first surface of the electromagnetic steel sheet (100%) was set to 3%.
The laminated core was obtained using an electromagnetic steel sheet having the following chemical composition and a thickness of 0.20 mm.
<Chemical composition of electrical steel sheet>
C content: 0.002 mass% relative to the mass of the electrical steel sheet.
Si content: 3.2 mass% relative to the mass of the electrical steel sheet.
Mn content: 0.5 mass% based on the mass of the electrical steel sheet.
Al content: 0.5 mass% based on the mass of the electrical steel sheet.
P content: 0.01 mass% based on the mass of the electrical steel sheet.
S content: 0.0015 mass% based on the mass of the electrical steel sheet.
N content: 0.002 mass% relative to the mass of the electrical steel sheet.
Sn content: 0.03 mass% based on the mass of the electrical steel sheet.

[Example 2]
A laminated core was obtained in the same manner as in Example 1, except that the bonding area ratio to the area of the first surface of the electromagnetic steel sheet was 20%.

[Example 3]
A laminated core was fabricated in the same manner as in Example 2, except that the electromagnetic steel sheets used had a Si content of 3.5 mass % and an Al content of 0.001 mass % relative to the mass of the electromagnetic steel sheets.

[Example 4]
A laminated core was fabricated in the same manner as in Example 2, except that the electromagnetic steel sheets used had a Si content of 1.7 mass % and an Al content of 2.0 mass % relative to the mass of the electromagnetic steel sheets.

[Comparative Example 1]
A laminated core was fabricated in the same manner as in Example 2, except that the adhesive area ratio to the area of the first surface of the electromagnetic steel sheet was 0%, i.e., no adhesive portion was provided.

[Comparative Example 2]
A laminated core was constructed in the same manner as in Example 2, except that the ratio of the size of the weld (bead width) to the outer circumferential length of the core back portion of the first surface of the electromagnetic steel sheet (100%) was 0%, i.e., no weld was provided.

<Evaluation of rigidity>
A rectangular steel plate (width 25 mm × length 100 mm) was cut out from the electromagnetic steel plate used in each example, and two steel plates were overlapped to form an overlapping portion with an overlap length of 12.5 mm. An adhesive was applied to the overlapping portion so as to achieve the adhesive area ratio and welded portion size ratio of the laminated core obtained in each example, a welding wire was placed, and arc welding was performed while crimping to obtain a test piece.
For each test piece, a tensile shear adhesive strength test was performed in accordance with JIS K6850:1999 to measure the breaking stress (MPa). The tensile test environment was room temperature (25°C). The test speed was 3 mm/min. The number of test pieces was 3. The average value of the breaking stress of the three test pieces was calculated, and the rigidity was evaluated based on the following evaluation criteria. The results are shown in Table 1.
Evaluation Criteria
A: The average breaking stress is 10 MPa or more.
B: The average breaking stress is 5 MPa or more and less than 10 MPa.
C: The average breaking stress is less than 5 MPa.

<Evaluation of magnetic properties>
Next, a verification test was carried out to verify the above-mentioned effects. Note that this verification test was carried out by evaluation using an actual motor.
The motor used for the actual machine evaluation had the shape shown in Fig. 1, and the lamination thickness of each of the stator core 21 and the rotor core 31 was 50.0 mm. The outer diameter of the stator core 21 was 250.0 mm. The inner diameter of the stator core 21 was 165.0 mm. The outer diameter of the rotor core 31 was 163.0 mm. The inner diameter of the rotor core 31 was 30.0 mm. The winding of the stator core 21 was concentrated winding with 10 turns in the slots 24. An excitation current with an effective value of 10 A and a frequency of 100 Hz was applied to each phase to rotate the motor at a rotation speed of 1000 rpm, and the iron loss was calculated by subtracting the output from the input power at that time and the copper loss due to the winding of the stator core.

The iron loss of the laminated core of each example was determined by the above test.
For comparison, the iron loss of a laminated core in which multiple electromagnetic steel sheets were all crimped was also calculated. The iron loss of each example of the laminated core was divided by the iron loss of the laminated core for comparison (iron loss ratio). When the iron loss of each example of the laminated core is equal to the iron loss of the laminated core for comparison, the iron loss ratio is 100%. The smaller the iron loss ratio, the smaller the iron loss of the laminated core for each example, and the better the magnetic properties of the laminated core.
The iron loss ratio of each example of the laminated core was calculated, and the magnetic properties of each example of the laminated core were evaluated based on the following evaluation criteria. The results are shown in Table 1.
Evaluation Criteria
A: The iron loss ratio is less than 100%.
C: Iron loss ratio is 100% or more.

As shown in Table 1, in Examples 1 to 4 in which the present invention was applied, the average breaking stress was 10 MPa or more and the iron loss ratio was less than 100%, and the laminate fixing strength was improved without deteriorating the magnetic properties.
On the other hand, in Comparative Example 1, which does not have an adhesive portion, the iron loss ratio was 100% or more.
In Comparative Example 2, which had no welded portion, the average breaking stress was less than 5 MPa.

The above results show that the laminated core of the present invention improves the laminated fixing strength while suppressing iron loss, and that the laminated fixing strength can be improved without degrading the magnetic properties of the laminated core.

20 Stator 21 Stator core (laminated core)
22 Core back portion 22a Outer peripheral edge of core back portion 22b Inner peripheral edge of core back portion 23 Teeth portion 24 Slot 40 Electromagnetic steel sheet 40a Surface (first surface) of electromagnetic steel sheet
41 adhesive joint 42 welded joint

Claims (6)

A plurality of electromagnetic steel sheets stacked on top of each other and coated on both sides with insulating films;
Adhesive portions provided between the electromagnetic steel sheets adjacent to each other in a stacking direction and adhering the electromagnetic steel sheets to each other;
and a welded portion at which the electromagnetic steel sheets are welded to each other,
the electromagnetic steel sheet includes an annular core back portion and a plurality of teeth portions protruding radially from the core back portion and arranged at intervals in a circumferential direction of the core back portion,
The adhesive portion is provided on the teeth portion,
The welded portion is provided on the core back portion by welding,
The welded portion is provided along an outer circumferential edge of the core back portion ,
The teeth portion are joined only by the adhesive portion . The adhesive portion is formed on the teeth portion by an adhesive;
The laminated core according to claim 1 , wherein the core back portion has only the welded portion formed by welding. The laminated core according to claim 1 or 2, wherein the adhesive portion is in the form of dots with an average diameter of 3 to 7 mm. The laminated core according to any one of claims 1 to 3, wherein the adhesive area ratio of the electromagnetic steel sheet by the adhesive portion is 1 to 40%. The laminated core according to any one of claims 1 to 4, wherein the aluminum content of the electromagnetic steel sheet is 0.001 to 2.0 mass%. A rotating electric machine equipped with a laminated core according to any one of claims 1 to 5.

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