Rotor core, rotor, rotary electrical machine, and pressurizing jig

Abstract

A rotor core (31) comprises: a plurality of electrical steel sheets (10) that are stacked; a fixing part (11) that fixes electrical steel sheets (10) which are adjacent in the stacking direction; and a first adhesion part (12A) that has a different fixing strength than the fixing part (11) and that is provided partially to a different region from the fixing part (11) between the electrical steel sheets (10). The electrical steel sheets (10) have a first portion (13) at which a greater strength is required as compared to other portions. The first portion (13) includes a bridge part (14). The first adhesion part (12A) is provided so as to cover the first portion (13) of the electrical steel sheets (10).

Description

Rotor core, rotor, rotating electric machine, and pressure jig

[0001] This application claims priority to Japanese Patent Application No. 2024-063432, filed on April 10, 2024, the contents of which are incorporated herein by reference.

[0002] As the electrification of automobiles progresses, motors are desired to be smaller and have higher output. To achieve higher output, for example, increasing the rotation speed is being considered. As the rotation speed increases, greater centrifugal force is generated in the motor's rotor core, making it necessary to improve centrifugal force resistance by, for example, using high-strength electromagnetic steel sheets. For example, Patent Document 1 discloses a technology in which slits formed at both ends of a permanent magnet are filled with resin to alleviate stress concentration caused by contact between the permanent magnet and the slit, thereby improving centrifugal force resistance. Patent Document 2 also discloses a technology in which a magnet and a rotor core are bonded using an adhesive directly coated on the magnet. Patent Document 3 discloses a technology in which stress concentration areas are strengthened by work hardening and thinned areas are filled with an adhesive to improve workability and heat dissipation.

[0003] Japanese Patent Application Laid-Open No. 2002-359942 Japanese Patent Application Laid-Open No. 2003-199303 Japanese Patent Application Laid-Open No. 2005-94940

[0004] There is a trade-off between the strength and magnetic properties of the electromagnetic steel sheets that make up the rotor core. Therefore, if the strength of the electromagnetic steel sheets themselves is increased to improve the centrifugal force resistance of the bridge sections that support the magnets, the strength of the sections other than the bridge sections will also be unnecessarily high, resulting in degraded magnetic properties. While it is possible to improve centrifugal force resistance by simply widening the bridge sections, this would allow an increase in the amount of magnetic flux that circulates through the bridge sections. This reduces the amount of magnetic flux between the rotor and stator, which contributes to torque improvement, resulting in degraded motor performance.

[0005] The present disclosure has been made in consideration of the above-mentioned problems, and aims to provide a rotor core, a rotor, and a rotating electric machine that are capable of improving resistance to centrifugal force and characteristics.

[0006] <1> A rotor core according to one embodiment of the present disclosure includes a plurality of stacked electromagnetic steel sheets, a fixing portion fixing adjacent electromagnetic steel sheets together in the stacking direction, and a first adhesive portion provided between the electromagnetic steel sheets in a region different from the fixing portion and having a fixing strength different from that of the fixing portion, the electromagnetic steel sheets having a first portion required to be stronger than other portions, the first portion including a bridge portion, and the first adhesive portion provided to cover the first portion of the electromagnetic steel sheets. <2> In the rotor core described in <1> above, each of the electromagnetic steel sheets may have one or more through holes for installing permanent magnets that respectively constitute a plurality of magnetic poles, and the first portion may include a first bridge portion formed between an outer periphery of the electromagnetic steel sheet and the through hole. <3> In the rotor core described in <1> or <2> above, each of the electromagnetic steel sheets may have a plurality of through holes for installing permanent magnets that respectively constitute a plurality of magnetic poles, and the first portion may include a second bridge portion formed between two adjacent through holes in each of the magnetic poles. <4> In the rotor core described in any one of <1> to <3> above, the fixing portion may be a second adhesive portion provided between adjacent electromagnetic steel sheets in the stacking direction and bonding the electromagnetic steel sheets together, and the compressive stress remaining in the first portion where the first adhesive portion is provided may be greater than the compressive stress remaining in the second adhesive portion. <5> In the rotor core described in <4> above, the second adhesive portion may be provided between adjacent electromagnetic steel sheets so as to cover the remaining area where the first adhesive portion is not provided. <6> In the rotor core described in <5> above, the fixing portion may be the second adhesive portion formed by solidifying a second adhesive different from the first adhesive that becomes the first adhesive portion upon solidification, and may be partially provided between the electromagnetic steel sheets. <7> In the rotor core described in any one of <1> to <4> above, the fixing portion may be a crimped portion. <8> A rotor according to one embodiment of the present disclosure includes the rotor core described in any one of <1> to <7> above, a permanent magnet installed in the rotor core, and a rotating shaft fixed to the rotor core. <9> A rotating electric machine according to an embodiment of the present disclosure includes the rotor according to <8> above and a stator.<10> A pressure jig according to one embodiment of the present disclosure is a pressure jig used in manufacturing a laminated core having a first adhesive portion and a second adhesive portion, and is provided with a pressing surface that presses the first adhesive portion and the second adhesive portion, and the pressing surface has a first pressing portion corresponding to the first adhesive portion that protrudes more than a second pressing portion corresponding to the second adhesive portion.

[0007] According to the present disclosure, a rotor core, a rotor, and a rotating electric machine that can improve resistance to centrifugal force and characteristics are provided.

[0008] Fig. 1 is a cross-sectional view showing a rotor core according to an embodiment of the present disclosure. Fig. 2 is an enlarged cross-sectional view of the rotor core shown in Fig. 1. Fig. 3 is a diagram showing calculation results of stress generated in a second bridge portion. Fig. 4 is a graph showing calculation results of rotation speed and maximum principal stress. Fig. 5 is a diagram showing the relationship between the width of the second bridge portion and the average torque in one period. Fig. 6 is a graph showing calculation results of rotation speed and maximum principal stress. Fig. 7 is a diagram showing the relationship between the width of a first bridge portion and the maximum principal stress. Fig. 8 is a diagram showing the relationship between the width of a first bridge portion and the average torque in one period. Fig. 9 is a cross-sectional view showing a pressing jig according to an embodiment of the present disclosure.

[0009] A rotor core, a rotor, and a rotating electric machine according to an embodiment of the present disclosure will now be described with reference to the drawings. A rotating electric machine 100 according to the present disclosure is, for example, an electric motor (motor) or a generator. The electric motor may be, for example, an AC electric motor, more specifically, a synchronous electric motor, or even more specifically, a permanent magnet field electric motor such as an interior permanent magnet type. This type of electric motor is suitable for use in, for example, electric vehicles.

[0010] FIG. 1 is a cross-sectional view showing a rotating electric machine 100 according to this embodiment. As shown in FIG. 1, the rotating electric machine 100 includes a stator 20 and a rotor 30. The rotor 30 includes a rotor core 31, a permanent magnet 32, and a rotating shaft 60. The stator 20 includes a stator core 21 and windings (not shown). The rotor 30 is arranged coaxially with the stator 20 (stator core 21), for example, radially inside. The rotating electric machine 100 of the embodiment shown in FIG. 1 is an inner rotor type in which the rotor 30 is arranged inside the stator 20, but may also be an outer rotor type in which the rotor 30 is arranged outside the stator 20.

[0011] Hereinafter, the direction in which the central axis O of the rotating shaft 60 extends (the stacking direction of the laminated core 1 described below) will be referred to as the axial direction, the direction perpendicular to the central axis O (the radial direction of the laminated core 1) will be referred to as the radial direction, and the direction circumferentially around the central axis O (the circumferential direction of the laminated core 1) will be referred to as the circumferential direction.

[0012] More specifically, the stator core 21 includes an annular (circular ring) core back portion 22 and a plurality of teeth 23. The core back portion 22 is formed in a circular ring shape when viewed in a plan view ( FIG. 1 ) of the stator core 21 from the axial direction. The plurality of teeth 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 plurality of teeth 23 are arranged at equal intervals in the circumferential direction. In this embodiment, 48 teeth 23 are provided at central angle intervals of 7.5 degrees around the central axis O. The plurality of teeth 23 are formed to have the same shape and size. The stator 20 is formed by winding a winding (not shown) around each tooth 23. The winding may be concentrated winding or distributed winding.

[0013] Meanwhile, the rotor 30 includes a rotor core 31, a plurality of permanent magnets 32 mounted on the rotor core 31, and a rotating shaft 60 fixed to the rotor core 31. The rotor core 31 is formed in an annular (circular ring) shape, with the rotating shaft 60 fixed to the center of the ring. In the rotor core 31, a set of multiple permanent magnets 32, such as one or a pair of permanent magnets 32, forms one magnetic pole, and the multiple magnetic poles are arranged at equal intervals in the circumferential direction. The number of poles, slots, and phases of the motor core can be changed as appropriate. In the embodiment shown in FIG. 1 , the two permanent magnets 32 forming each magnetic pole are arranged in a V-shape that protrudes radially inward in a plan view.

[0014] The permanent magnets 32 are respectively installed in a plurality of through holes 33 formed in the rotor core 31 and passing through the rotor core 31 in the axial direction. Each permanent magnet 32 ​​is fixed to the rotor core 31 while being disposed in 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.

[0015] To describe the through holes 33 in more detail, as shown in FIG. 1 , each through hole 33 may include an installation area for a permanent magnet 32 ​​and a flux barrier 34. The flux barrier 34 is a magnetic gap that passes through the rotor core 31 in the axial direction and reduces the magnetic flux from the permanent magnet 32 ​​that circulates within the rotor 30 (hereinafter also referred to as circulating magnetic flux) and changes the path of magnetic flux flowing from the permanent magnet 32 ​​to the stator 20. In FIG. 1 , the flux barriers 34 are provided on both sides of the installation area for the permanent magnet 32 ​​in the through holes 33. This allows the magnetic flux from the permanent magnet 32 ​​(hereinafter also simply referred to as magnetic flux) to be effectively transmitted to the stator 20, resulting in high torque output. It can also be said that the flux barriers 34 guide the magnetic flux to the stator 20.

[0016] At least one of the rotor core 31 and the stator core 21 described above is a laminated core 1 made up of a plurality of stacked electromagnetic steel sheets 10. Various holes are formed in each of the electromagnetic steel sheets 10 forming the laminated core 1, and stacking the plurality of electromagnetic steel sheets 10 causes the various holes to connect with each other in the axial direction, thereby forming the aforementioned through holes 33 and the like.

[0017] The thickness of each electromagnetic steel sheet 10 forming the laminated core 1 is determined appropriately taking into consideration factors such as the iron loss improvement effect, manufacturing costs, and ease of press punching. Each electromagnetic steel sheet 10 forming the laminated core 1 is formed, for example, by punching an electromagnetic steel sheet serving as a base material. Known electromagnetic steel sheets can be used as the electromagnetic steel sheets 10. The chemical composition of the electromagnetic steel sheets 10 is not particularly limited. In this embodiment, non-oriented electromagnetic steel sheets (e.g., JIS C 2552:2014) are used as the electromagnetic steel sheets 10, but oriented electromagnetic steel sheets (e.g., JIS C 2553:2019) may also be used. To improve the workability of the electromagnetic steel sheets and the iron loss of the laminated core, an insulating coating is provided on both sides of the electromagnetic steel sheets 10. The material and thickness (thickness per side of the electromagnetic steel sheets 10) of the insulating coating are determined appropriately taking into consideration factors such as the insulation performance and space factor of the laminated electromagnetic steel sheets 10.

[0018] Next, the present invention will be described in detail using an example in which the laminated core 1 is a rotor core 31. As shown in Fig. 1, the rotor core 31 includes a fixing portion 11 and a first adhesive portion 12A.

[0019] The fixing portions 11 fix adjacent electromagnetic steel sheets 10 to each other in the stacking direction. For example, the fixing portions 11 may be crimps or adhesive portions formed by solidifying (hardening) an adhesive. The adhesive portions bond and fix the electromagnetic steel sheets 10 to each other. Alternatively, they may be something other than these. When the fixing portions 11 are crimps, multiple crimps may be provided at intervals along the circumferential direction of the laminated core 1. When the fixing portions 11 are adhesive portions, examples of the type of adhesive that can be used include a thermosetting adhesive that uses polymerization bonding, an acrylic adhesive that cures at room temperature, an anaerobic adhesive, an instant adhesive, and an elastomer-containing acrylic adhesive.

[0020] The first adhesive portion 12A is formed by solidifying (hardening) an adhesive, and is partially provided between the magnetic steel sheets 10 in an area different from the fixed portion 11. The type of adhesive forming the first adhesive portion 12A may be different from the adhesive used when the fixed portion 11 is the adhesive portion. In other words, the first adhesive 12Ag forming the first adhesive portion 12A and the second adhesive 12Bg forming the fixed portion 11 may be different adhesives. Alternatively, the same type of adhesive may be used by using an adhesive that exhibits adhesive strength according to the amount of pressure applied during bonding. In other words, the first adhesive 12Ag forming the first adhesive portion 12A and the second adhesive 12Bg forming the fixed portion 11 may be the same adhesive.

[0021] The first adhesive portion 12A and the fixing portion 11 have different fixing strengths. The fixing strength here refers to the strength (fixing force) that fixes the electromagnetic steel sheets 10 together, and differs depending on the type of fixing means. For example, the fixing strength obtained by caulking is different from the fixing strength (adhesion strength) obtained by an adhesive. If the adhesive strength differs between adhesives due to differences in the type of adhesive or the pressure applied during bonding, the compressive stress (described below) applied to the electromagnetic steel sheets 10 is also thought to be different, resulting in different fixing strengths. On the other hand, if the adhesive strength is the same, the fixing strength is the same. Furthermore, the first adhesive portion 12A is formed by solidifying (hardening) the adhesive, but it may also bond and fix adjacent electromagnetic steel sheets 10 together. Alternatively, the first adhesive portion 12A may be solidified without bonding adjacent electromagnetic steel sheets 10 together, in which case the fixing strength may be zero.

[0022] Here, the electromagnetic steel sheets 10 constituting the rotor core 31 have a portion (hereinafter, referred to as the first portion 13) that requires a relatively higher strength than the other portions. The portion that requires a higher strength than the other portions is, for example, a portion that supports the permanent magnets 32 from the stress generated in the bridge portions 14 that support the permanent magnets 32 when the laminated core 1 rotates, due to centrifugal force acting on the permanent magnets 32 with a magnitude corresponding to the rotation speed. An example of such a portion is the bridge portions 14. Therefore, the first portion 13 may include the bridge portions 14. The thickness (plate thickness) of the electromagnetic steel sheets 10 that form the bridge portions 14 is the same as that of the other portions of the electromagnetic steel sheets 10, and work hardening in the plate thickness direction is not required.

[0023] The first adhesive portion 12A is provided so as to cover the first portion 13 of the electromagnetic steel sheet 10. The first adhesive portion 12A may be provided continuously throughout the first portion 13 without being divided, thereby covering the first portion 13. Alternatively, the first adhesive portion 12A may be divided into a plurality of portions in the first portion 13. That is, it is sufficient that the first adhesive portion 12A is provided over the entire first portion 13. In other words, it is sufficient that the first adhesive portion 12A is provided so as to cover most of the first portion 13. Alternatively, it is sufficient that the first adhesive portion 12A is provided so as to cover the entire first portion 13. As long as the first adhesive portion 12A is provided over the entire first portion 13, the first adhesive portion 12A may be divided into a plurality of solidified portions spaced apart from each other, where the adhesive has solidified. The plurality of solidified portions may be provided regularly, for example, in a dotted, staggered, dashed, or inclined pattern, or may be provided irregularly.

[0024] When the laminated core 1 rotates, centrifugal force corresponding to the rotation speed acts on the permanent magnets, generating large stress in the bridge portions 14 supporting the permanent magnets 32. The first adhesive portions 12A provided on the first portions 13 of the electromagnetic steel sheets 10 impart compressive stress to the first portions 13 when the applied adhesive solidifies, thereby improving the strength of the first portions 13. This increases the strength of the bridge portions 14, ensuring the necessary strength even when the width of the bridge portions 14 is narrowed. Therefore, by narrowing the width of the bridge portions 14, the return magnetic flux through the bridge portions 14 can be reduced accordingly, thereby improving the characteristics of the rotating electric machine 100 equipped with this rotor core 31.

[0025] In the embodiment shown in Fig. 1, the fixing portion 11 is formed by an adhesive portion (hereinafter, the adhesive portion that becomes the fixing portion 11 will be referred to as a second adhesive portion 12B), and is provided in the entire portion (region) of the electromagnetic steel sheet 10 other than the first portion 13 in a plan view. In addition, the first adhesive portion 12A is a bridge portion 14. The thickness (sheet thickness) of the electromagnetic steel sheet 10 that forms the bridge portion 14 is the same as the other portions of the electromagnetic steel sheet 10.

[0026] At this time, the adhesive strength of the first adhesive portion 12A is greater than the adhesive strength of the second adhesive portion 12B. In other words, the compressive stress remaining in the first portion 13 where the first adhesive portion 12A is provided is greater than the compressive stress remaining in the second adhesive portion 12B. The compressive stress can be measured, for example, by X-ray diffraction (XRD). Details of X-ray diffraction are described in the following literature: [X-Ray Stress Measurement Standard (2002 Edition) Iron and Steel Edition (JSMS SD-5-02:2002), published by the Japan Society for Materials Science]. If the compressive residual stress in the laminated core 1 is greater than or equal to a predetermined threshold value (e.g., 3 MPa or 5 MPa) compared to other regions, the region (first adhesive portion 12A) can be identified as having a high adhesive strength. This threshold value may be set to a value greater than the range of variation in measurement values ​​due to measurement error or other factors.

[0027] The region with high adhesive strength (first adhesive portion 12A) is pressurized by the convex portion of the pressing jig 200 described below. This may result in a depression compared to other regions. That is, in the region with high adhesive strength, the first adhesive portion 12A may be thinner than the second adhesive portion 12B due to the strong pressure. Therefore, a method for confirming and identifying the region with high adhesive strength (first adhesive portion 12A) can be considered by observing the surface or cross section of the laminated core 1. Furthermore, this method can also confirm and identify the region (first adhesive portion 12A) where adhesive strength is changed by partial pressure application.

[0028] For example, a possible method is to confirm that the adhesive strength of the first adhesive portion 12A is greater than the adhesive strength of the second adhesive portion 12B using a JIS adhesive strength test, such as a peel strength test. Alternatively, the adhesive strength of the first adhesive portion 12A or the second adhesive portion 12B may be measured using a shear strength measurement method. For the shear strength measurement method, an Autograph AGS-10kNX (Shimadzu Corporation) is used as a tensile tester. The test conditions are as follows: tensile mode: shear tensile test, tensile temperature: 25°C, tensile speed: 50 mm / min. For shear strength measurement, the tensile test is performed until the test piece (the first adhesive portion 12A or the second adhesive portion 12B) breaks. If multiple test pieces can be obtained, the average of the maximum strengths measured until breakage for each test piece is taken as the shear adhesive strength. The obtained shear adhesive strength value is then divided by the adhesive area to determine the room temperature adhesive strength. This also makes it possible to confirm that the adhesive strength of the first adhesive portion 12A is greater than the adhesive strength of the second adhesive portion 12B.

[0029] Such a compressive stress distribution on the electromagnetic steel sheets 10 in a plan view can be formed, for example, during the manufacturing of the laminated core 1, by applying a type of adhesive, whose adhesive strength corresponds to the magnitude of the pressure applied during bonding, to at least a portion between the two electromagnetic steel sheets 10, and then solidifying (hardening) the adhesive while applying different pressure in the lamination direction to the first portion 13 of the electromagnetic steel sheets 10 and the other regions. For example, a pressure jig 200 (described later) or the like may be used to form a compressive stress distribution on the electromagnetic steel sheets 10 (pressure distribution on the surfaces of the electromagnetic steel sheets 10 applied during manufacturing). This allows the laminated core 1 to be appropriately bonded and fixed by the second adhesive portions 12B (fixing portions 11), while the first adhesive portions 12A apply compressive stress, thereby increasing the strength of the bridge portions 14.

[0030] However, the present invention is not limited to the above-described embodiment. The second adhesive portion 12B constituting the fixing portion 11 may adhere and fix at least a portion of the region other than the first adhesive portion 12A. In this case, the adhesive strength (compressive stress applied to the first portion 13) of the first adhesive portion 12A and the second adhesive portion 12B may be the same or different. The adhesives used for both may be the same or different. That is, the fixing portion 11 may be formed of the second adhesive portion 12B solidified with the same adhesive as the first adhesive 12Ag that solidifies into the first adhesive portion 12A. Alternatively, the fixing portion 11 may be formed of the second adhesive portion 12B solidified with a second adhesive agent 12Bg that is different from the first adhesive 12Ag that solidifies into the first adhesive portion 12A.

[0031] Furthermore, in this embodiment, the first adhesive portion 12A bonds adjacent electromagnetic steel sheets 10 together, but the first adhesive portion 12A is intended to partially increase the strength of the bridge portion 14, and it is not necessary for adjacent electromagnetic steel sheets 10 to be bonded together.

[0032] According to the above-described configuration, the first adhesive portions 12A are provided to cover the bridge portions 14 (first portions 13), which are portions of the rotor core 31 that require relatively higher strength than other portions. The first adhesive portions 12A provided on the first portions 13 of the electromagnetic steel sheets 10 impart compressive stress to the first portions 13 when the applied adhesive solidifies, thereby improving the strength of the first portions 13. This increases the strength of the bridge portions 14, allowing the width of the bridge portions 14 to be narrower within a range that ensures the centrifugal force resistance required during rotation, thereby more effectively reducing the return magnetic flux through the bridge portions 14. Therefore, by using such a rotor core 31, the centrifugal force resistance and characteristics of the rotating electric machine 100 can be improved.

[0033] Specific examples of the bridge portions 14 in the first portion 13 will be described below. (First bridge portion 14A) The first portion 13 may include a first bridge portion 14A formed between the outer peripheral edge 16 of the electromagnetic steel sheet 10 and the through hole 33 (see FIGS. 1 and 2). The first bridge portion 14A includes a portion of the electromagnetic steel sheet 10 that is sandwiched between the outer peripheral edge 16 of the electromagnetic steel sheet 10 and the through hole 33, and the portions of the electromagnetic steel sheet 10 on both sides are connected via the first bridge portion 14A on the outer peripheral edge 16 side of the electromagnetic steel sheet 10. The above-mentioned first adhesive portion 12A is provided so as to cover the first bridge portion 14A.

[0034] When the laminated core 1 rotates, a large centrifugal force is generated on the permanent magnets 32. However, the strength of the first bridge portions 14A is improved by the provision of the first adhesive portions 12A. The width (radial length) of the first bridge portions 14A is determined based on the strength of the first bridge portions 14A, which is improved by the provision of the first adhesive portions 12A. In other words, compared to when the first bridge portions 14A do not have the first adhesive portions 12A, the increased strength allows the first bridge portions 14A to withstand stronger centrifugal forces. Therefore, the width of the first bridge portions 14A with the first adhesive portions 12A is narrower than when the first adhesive portions 12A are not provided. This allows for more effective reduction of the return magnetic flux through the first bridge portions 14A.

[0035] According to the above configuration, the first bridge portion 14A is provided with the first adhesive portion 12A, which can improve the centrifugal force resistance of the rotor core 31. Furthermore, by making the width of the first bridge portion 14A provided with the first adhesive portion 12A smaller than when the first adhesive portion 12A is not provided, the characteristics of the rotating electric machine 100 and the like can be improved.

[0036] (Second Bridge Portion 14B) The first portion 13 may include a second bridge portion 14B formed between two adjacent through holes 33 in each magnetic pole (see FIGS. 1 to 3). As shown in FIGS. 1 to 3, the multiple through holes 33 in each magnetic pole are arranged adjacent to each other with their closest portions in contact with each other. The second bridge portion 14B includes a portion of the electromagnetic steel sheet 10 that is narrowed by being sandwiched between the pair of most adjacent through holes 33, and the portions of the electromagnetic steel sheet 10 in the radial direction of the through holes 33 are connected via the second bridge portion 14B. In FIGS. 1 to 3, the second bridge portion 14B is formed along the radial direction at the tip end side of the V-shape of the pair of through holes 33. The first adhesive portion 12A described above is provided on the second bridge portion 14B so as to cover the second bridge portion 14B.

[0037] According to the above configuration, the second bridge portion 14B is provided with the first adhesive portion 12A. As a result, as already explained above, the strength of the second bridge portion 14B can be increased compared to when the second bridge portion 14B does not have the first adhesive portion 12A. Therefore, the width of the second bridge portion 14B provided with the first adhesive portion 12A can be made narrower compared to when the second bridge portion 14B does not have the first adhesive portion 12A, thereby improving the characteristics of the rotating electric machine 100.

[0038] In the embodiment shown in Figures 1 to 3, the first adhesive portion 12A is provided on both the first bridge portion 14A and the second bridge portion 14B, but the present invention is not limited to this embodiment, and the first adhesive portion 12A may be provided only on the first bridge portion 14A or only on the second bridge portion 14B.

[0039] [Example] The stress generated in the second bridge portion 14B was calculated. Figure 3 shows the calculation results of the stress generated around the second bridge portion 14B. In Figure 3, the darker colored areas represent areas where the generated stress is small, and the lighter colored areas represent areas where the generated stress is large. The maximum value was found on both radial ends 33a of the second bridge portion 14B.

[0040] FIG. 4 shows the calculation results of the relationship between the rotation speed and the maximum principal stress when the width w of the second bridge portion 14B is changed. The horizontal axis of FIG. 4 represents the rotation speed (rpm), and the vertical axis represents the maximum principal stress (MPa). Note that in FIG. 4, the reference value of the width w of the second bridge portion 14B is set to "1." The width w of the second bridge portion 14B is represented as "w1" when it is 1 times the reference value "1," as "w0.57" when it is 0.57 times the reference value "1," and as "w0.35" when it is 0.35 times the reference value "1." For example, comparing the results for w1 and w0.57, at the motor's predetermined maximum rotation speed (the rotation speed at which yield stress occurs as the maximum principal stress when w1 is used), a 43% decrease in the width w of the second bridge portion 14B resulted in an approximately 50% increase in the generated stress.

[0041] Figure 5 shows the relationship between the width w of the second bridge portion 14B and the average torque (N m) per cycle. The horizontal axis of Figure 5, "bridge width," represents the width w of the second bridge portion 14B, and the vertical axis represents the average torque (N m) per cycle. For example, a comparison of the results for w1 and w0.83 shows that narrowing the width w of the second bridge portion 14B by 17% can be expected to increase torque by approximately 1%.

[0042] Figure 6 shows the calculation results of the rotation speed and maximum principal stress when the width w of the second bridge portion 14B (see Figures 2 and 3) is fixed and the radial width b of the first bridge portion 14A is changed. The horizontal axis of Figure 7 represents the rotation speed (rpm), and the vertical axis represents the maximum principal stress (MPa). In Figure 6, the width b of the first bridge portion 14A (see Figure 2) has a reference value of "1," and when the width b is 1 time the reference value, it is represented as "b1," when it is 0.5 times the reference value, it is represented as "b0.5," and when it is 1.5 times the reference value, it is represented as "b1.5."

[0043] FIG. 7 shows the relationship between the width b of the first bridge portion and the maximum principal stress. The horizontal axis of FIG. 7 indicates the width of the first bridge portion 14A, while the vertical axis indicates the maximum principal stress (MPa). FIG. 8 shows the relationship between the width b of the first bridge portion 14A and the average torque per cycle. The horizontal axis of FIG. 8 indicates the width b of the first bridge portion 14A, while the vertical axis indicates the average torque (N·m) per cycle. For example, comparing the results for b1 and b0.3 shown in FIG. 7 reveals that the width can be narrowed by approximately 70% while expecting an approximately 20% strength improvement through bonding. In this case, comparing the results for b1 and b0.3 shown in FIG. 8 reveals that the torque increases from the reference condition, resulting in an improvement of approximately 5%.

[0044] The width of the bridge portion (the width b of the first bridge portion 14A and the width w of the second bridge portion 14B) is determined based on the strength of the bridge portion 14 provided with the first adhesive portion 12A. The strength of this bridge portion 14 can be determined in advance by calculation or experiment, taking into account, for example, the pressure conditions of the adhesive. The required strength of the bridge portion 14 is determined based on the rotation speed specifications of the rotating electric machine. The width of the bridge portion 14 is then determined by changing the width of the bridge portion 14 and selecting, for example, the narrowest width within a range that satisfies the required strength.

[0045] In this embodiment, first, the upper limit of the stress generated in the bridge portions 14 was determined based on the rotation specifications, such as the maximum rotation speed, of the rotating electric machine 100 to be designed. The strength improvement of the electromagnetic steel sheets 10 due to the provision of the first adhesive portions 12A, such as adhesive fixation, was experimentally determined. Next, the generated stress (maximum rotation speed condition) was calculated for each of multiple width W candidates for the bridge portions 14. The width of the bridge portions was then determined so that the sum of the upper limit of the generated stress and the strength improvement value determined through experiments was equal to or less than the upper limit of the generated stress. In other words, the manufacturing method of the rotor core 31 (laminated core 1) includes the steps of: determining the maximum generated stress applied to the bridge portions 14 (first portions 13) of the laminated core 1 of the rotating electric machine 100 due to centrifugal force based on the specifications of the rotating electric machine 100 to be designed, and determining the width W of the bridge portions 14, including the strength improvement value of the electromagnetic steel sheets 10 (bridge portions 14) due to the first adhesive portions 12A, based on the upper limit so as not to exceed the upper limit. The manufacturing method may then further include a step of manufacturing a laminated core 1 provided with first adhesive portions 12A having bridge portions 14 with the determined width W.

[0046] A pressing jig 200 that can be used to manufacture the laminated core 1 according to the above-described embodiment will now be described. Fig. 9 is a schematic diagram showing an example of use of the pressing jig 200. The pressing jig 200 is used when pressure needs to be applied for bonding, for example, when an adhesive coating is primarily provided on the electromagnetic steel sheets 10.

[0047] The pressing jig 200 is a jig used to press a stack of at least some of the multiple electromagnetic steel sheets 10 constituting the laminated core 1 with an adhesive sandwiched therebetween (hereinafter referred to as the core portion P) for adhesive fixation during the manufacture of the laminated core 1. As shown in Fig. 9 , the pressing jig 200 includes a first member 210 having an uneven pressing surface 211 that presses the core portion P while contacting it. The core portion P is bonded by applying pressure to it via the first member 210 using a pressing unit 201 of a pressing device. The core portion P may be heated to a predetermined temperature before pressure is applied.

[0048] More specifically, the pressing surface 211 of the first member 210 has a surface (region) corresponding to the region where the first adhesive portion 12A is formed in the first portion 13 of the electromagnetic steel sheet 10, which protrudes more than a surface (region) corresponding to the region where the second adhesive portion 12B is formed in the stacking direction of the laminated core 1. In other words, the surface (region) corresponding to the first adhesive portion 12A has a convex shape in the stacking direction of the laminated core 1, and the surface (region) corresponding to the second adhesive portion 12B has a concave shape in the stacking direction of the laminated core 1. In this way, the pressing surface 211 has a first pressing portion 211A (convex portion) configured to press the region corresponding to the first adhesive portion 12A relatively strongly, and a second pressing portion 211B (concave portion) configured to press the region corresponding to the second adhesive portion 12B relatively weakly.

[0049] In other words, the pressing jig 200 has an uneven pressing surface 211 so that the pressure applied to the desired region of the core portion P is higher than that applied to other regions during bonding. The uneven shape of the pressing surface 211 in a plan view of the laminated core 1 from the stacking direction is designed according to the shape and position of the region of the first portion 13 of the electromagnetic steel sheet 10. As a result, the region corresponding to the convex portion (first pressing portion 211A) receives a higher pressing pressure than the region corresponding to the concave portion (second pressing portion 211B). Therefore, if the adhesive used to bond and fix the laminated core 1 is of a type that exhibits adhesive strength according to the magnitude of pressure applied during bonding, the first adhesive portion 12A and the second adhesive portion 12B can be formed by applying pressure to the core portion P once.

[0050] 9 , the pressing jig 200 (first member 210) is a plate-like member with concaves and convexes formed thereon, such as a die in which concaves and convexes are formed in the thickness direction of a metal plate having a predetermined thickness. When pressed by the pressing portion 201, the first pressing portion 211A of the first member 210 presses the first portion 13 (first adhesive portion 12A) of the electromagnetic steel sheet 10, and the second pressing portion 211B presses the region other than the first portion 13 (second adhesive portion 12B).

[0051] The pressing surface 211 also includes a tapered portion 212 that connects the first pressing portion 211A and the second pressing portion 211B. That is, the first pressing portion 211A and the second pressing portion 211B are smoothly connected and are formed so that the pressure applied thereto changes gradually. As a configuration in which the pressure applied thereto changes gradually, for example, the tapered portion 212 may be gradually inclined at a constant rate or may change in a quadratic curve.

[0052] 9, a first member 210 is disposed above the core portion P with its pressing surface 211 facing downward. In addition, the core portion P is supported from below by being disposed on the upper surface of a second member 220 fixedly disposed below the core portion P, and the pressing portion 201 of the pressing device presses the first member 210 in the direction of arrow F (downward in the stacking direction), thereby applying pressure to the core portion P and adhesively fixing it.

[0053] However, the present invention is not limited to the above-described embodiment. For example, the first member 210 may be disposed below and the second member 220 may be disposed above. Furthermore, in addition to the first member 210, the support surface of the core portion P of the second member 220 may also be formed with concaves and convexes that match the concaves and convexes of the pressing surface 211 of the first member 210. Furthermore, the first pressing portion 211A and the second pressing portion 211B of the first member 210 do not have to include the tapered portion 212, and may be connected by, for example, a single staircase-like step portion.

[0054] 9 is a schematic representation of the shape of the pressing jig 200 for ease of understanding, and the dimensions of the actual pressing jig 200 may differ. For example, in the view indicated by the arrow in FIG. 9 (side view of the laminated core 1), a difference H (μm) in the unevenness of the pressing surface 211 is provided. The difference H may be determined based on the relationship between the pressure conditions of the adhesive determined in advance by experiment or calculation and the improvement in strength of the electromagnetic steel sheet 10 due to the provision of the first adhesive portion 12A.

[0055] According to the above-described pressing jig 200, the unevenness formed on the pressing surface 211 makes it possible to create a pressure distribution on the surface of the electromagnetic steel sheet 10 with a single application of pressure. Therefore, when bonding and fixing, a higher pressure can be applied to the area of ​​the electromagnetic steel sheet 10 where the first adhesive portion 12A is to be formed than to the area where the second adhesive portion 12B is to be formed with a single application of pressure. Therefore, the first adhesive portion 12A and the second adhesive portion 12B can be formed efficiently, thereby reducing the manufacturing cost of the laminated core 1.

[0056] Although the preferred embodiments of the present invention have been described in detail above with reference to the accompanying drawings, the present invention is not limited to these examples. It is clear that a person skilled in the art to which the present invention pertains can conceive of various modifications and alterations within the scope of the technical ideas set forth in the claims, and it is understood that these also naturally fall within the technical scope of the present invention.

[0057] The shape of the laminated core 1 is not limited to the form shown in the above embodiment. The outer and inner diameters of the laminated core 1, the lamination thickness, and other dimensions can be designed as desired according to the characteristics of the laminated core 1. The number of slots in the stator core, the circumferential and radial dimensional ratio of the teeth portions 23, and the radial dimensional ratio of the teeth portions 23 and the core back portion 22 can also be designed as desired according to the characteristics of the laminated core 1. In the above description, the bridge portions 14 of the rotor core 31 are used as an example, but if necessary, adhesives may be used to locally strengthen other portions of the rotor core 31 other than the bridge portions 14 or the stator core 21.

[0058] The laminated core according to the present disclosure can provide a rotor core, a rotor, and a rotating electrical machine that can improve resistance to centrifugal force and other characteristics, and thus has great industrial applicability.

[0059] REFERENCE SIGNS LIST 1 Laminated core 10 Electromagnetic steel sheet 11 Fixing portion 12 Adhesive portion 12A First adhesive portion 12Ag First adhesive 12B Second adhesive portion 12Bg Second adhesive 13 First portion 14 Bridge portion 14A First bridge portion 14B Second bridge portion 16 Outer periphery 20 Stator 21 Stator core 22 Core back portion 23 Teeth portion 30 Rotor 31 Rotor core 32 Permanent magnet 33 Through hole 34 Flux barrier 100 Rotating electric machine 200 Pressing jig 201 Pressing portion 210 First member 220 Second member 211 Pressing surface 211A First pressing portion 211B Second pressing portion 212 Tapered portion

Claims

1. Multiple laminated electrical steel sheets, A fixing portion for fixing adjacent electrical steel sheets in the stacking direction, The electrical steel sheets are further provided with a first adhesive portion which is partially located in a region different from the fixing portion and has a different fixing strength than the fixing portion, The electrical steel sheet has a first portion which is required to have higher strength than other parts of the electrical steel sheet, and the first portion includes a bridge portion. The first adhesive portion is a rotor core provided so as to cover the first portion of the electromagnetic steel sheet.

2. Each of the aforementioned electromagnetic steel sheets has one or more through holes for installing permanent magnets that each constitute a plurality of magnetic poles. The rotor core according to claim 1, wherein the first portion includes a first bridge portion formed between the outer peripheral edge of the electrical steel sheet and the through hole.

3. Each of the aforementioned electromagnetic steel sheets has multiple through holes for installing multiple permanent magnets, each constituting a multiple magnetic pole. The rotor core according to claim 1, wherein the first portion includes a second bridge portion formed between two adjacent through holes in each of the magnetic poles.

4. The aforementioned fixing portion is a second bonding portion provided between adjacent electrical steel sheets in the stacking direction, which bonds the electrical steel sheets together. The rotor core according to claim 1, wherein the compressive stress remaining in the first portion provided with the first adhesive portion is greater than the compressive stress remaining in the second adhesive portion.

5. The rotor core according to claim 4, wherein the second adhesive portion is provided between adjacent electromagnetic steel sheets so as to cover the remaining area where the first adhesive portion is not present.

6. The rotor core according to claim 5, wherein the fixing portion is a second adhesive portion formed by the solidification of a second adhesive different from the first adhesive which becomes the first adhesive portion when solidified, and is partially provided between the electromagnetic steel sheets.

7. The rotor core according to claim 1, wherein the fixing portion is a crimped portion.

8. A rotor core according to any one of claims 1 to 7, A permanent magnet installed in the rotor core, A rotating shaft fixed to the rotor core, A rotor equipped with a rotor.

9. The rotor according to claim 8, A rotating electric machine equipped with a stator.

10. A pressurizing jig used in the manufacture of a rotor core having a first adhesive portion and a second adhesive portion as described in any one of claims 4 to 7, The device comprises a pressing surface that presses against the first adhesive portion and the second adhesive portion, The pressing surface is a pressurizing jig in which the first pressing portion corresponding to the first adhesive portion protrudes more than the second pressing portion corresponding to the second adhesive portion.