Invention title: Rotor, rotor design method and rotor manufacturing method
Technical field
[0001]
　The present invention relates to a rotor, a method for designing a rotor, and a method for manufacturing a rotor. The present application claims priority based on Japanese Patent Application No. 2019-185110 filed in Japan on October 8, 2019, the contents of which are incorporated herein by reference.
Background technology
[0002]
　The rotor is a core used as a rotating body in a motor. Rotors have so far been manufactured primarily by caulking structures. However, in recent years, for the purpose of thinning electrical steel sheets and improving production efficiency, a manufacturing method using (1) an adhesive structure and (2) a combined structure of caulking and adhesive has been proposed (see, for example, Patent Document 1). ..
Prior art literature
Patent documents
[0003]
Patent Document 1: Japanese Patent Application Laid-Open No. 2014-197981
Outline of the invention
Problems to be solved by the invention
[0004]
　With the advent of hybrid vehicles and electric vehicles, motor rotors are required to rotate at a high speed of 14,000 rpm or more. IPM motors are the mainstream motors used in automobiles. In IPM motors, magnets are embedded in the rotor. From the viewpoint of motor efficiency, it is required to install a magnet at a position closer to the outermost circumference. Therefore, stress is concentrated on a narrow steel plate width called a bridge on the outside of the magnet, and the bridge is about to expand and the rotor is deformed. Deformation of the rotor means that it becomes impossible to maintain a narrow gap with the stator, which leads to damage to the motor.
[0005]
　An object of the present invention is to provide a rotor in which damage at high speed rotation is suppressed.
Means to solve problems
[0006]
　In order to solve the above problems, the present invention proposes the following means.
　The rotor according to the present invention is a magnet-embedded rotor incorporated in a motor for traveling an automobile, and has a laminated core having a steel plate laminated to each other and an adhesive layer for adhering the steel plates adjacent to each other in the laminating direction. A magnet embedded in the laminated core is provided, and when the rotor rotates at 11000 rpm, the maximum displacement amount of the outer edge of the laminated core in the radial direction of the rotor is 0.1 mm or less.
[0007]
　When the rotor rotates at 11000 rpm, the maximum displacement of the outer edge of the laminated core in the radial direction of the rotor is 0.1 mm or less. Therefore, even when the rotor rotates at the maximum rotation speed (for example, a rotation speed exceeding 11000 rpm) when the automobile is running, deformation of the outer shape of the rotor is suppressed, for example, the rotor comes into contact with the stator, and the like. Can be prevented. As a result, damage to the motor can be suppressed.
　The maximum amount of displacement of the outer edge of the laminated core in the radial direction can be obtained, for example, by the following methods (1) and (2).
(1) At the outer edge of the laminated core, the amount of change in the radial position before and after rotation is obtained for each position along the circumferential direction of the rotor, and the amount of change is added to the elastic deformation during rotation. The maximum value is defined as the maximum displacement amount.
(2) When the part of the outer edge of the laminated core that is most displaced before and after rotation is known in advance (for example, when it is theoretically clear or when it is grasped by simulation or empirical rule), about that part. The amount of change in the radial position before and after rotation is obtained, and the value obtained by adding the elastic deformation during rotation to the amount of change is defined as the maximum displacement amount.
[0008]

　The yield stress YPR of the steel sheet may be 150 MPa or more and 580 MPa or less.
[0009]
　When the yield stress of the steel sheet is YPR ( MPa), the yield stress of the adhesive layer is YP B (MPa), and the maximum rotation speed during traveling of the automobile is ω (rpm), the following equation (1) is used. May be satisfied. [Number 1] 　Here, A = 0.105, B = 17,000, C = 17,000, D = 410, E = 30.

[0010]
　The following equation (2) may be further satisfied.
0.1 × YP R ≦ YP B ≦ 10 × YP R　　・ ・ ・ (2)
[0011]
　The magnet is arranged in a through hole penetrating the laminated core in the laminating direction, and a sealing resin for sealing between the outer surface of the magnet and the inner surface of the through hole is provided in the through hole. It may have been magnetized.
[0012]
　The method for designing a rotor according to the present invention is a method for designing a magnet-embedded rotor incorporated in a motor for traveling an automobile. A laminated core having an adhesive layer and a magnet embedded in the laminated core are provided, and in the design method, when the rotor rotates at the maximum rotation speed during traveling of the automobile, the radial direction of the rotor is provided. The yield stress of the steel sheet and the yield stress of the adhesive layer are set so that the maximum displacement of the outer edge of the laminated core toward the surface is 0.1 mm or less.
[0013]
　According to the rotor designed by this design method, when the rotor rotates at the maximum rotation speed during traveling of the automobile, the maximum displacement amount of the outer edge of the laminated core in the radial direction of the rotor is 0.1 mm or less. .. Therefore, even when the rotor rotates at the maximum rotation speed during traveling of the automobile, it is possible to suppress deformation of the outer shape of the rotor and prevent, for example, the rotor from coming into contact with the stator. As a result, damage to the motor can be suppressed.
[0014]
　By the way, for the adhesive layer, evaluation based on the adhesive strength (adhesive force with the steel sheet under conditions such as tension, compression, shearing, and 90 degree peeling) has been emphasized. Against this background, there was no technical idea to regulate the deformation of the steel sheet based on the yield stress of the adhesive layer. The only way to regulate the deformation of the steel sheet was to use a high-strength steel sheet. As a result, the cost of the rotor becomes high, and it becomes difficult to manufacture the rotor. In particular, when an electromagnetic steel sheet is used as the steel sheet, it is necessary to satisfy the requirements for high strength in addition to the basic characteristics (low iron loss, high magnetic flux density). Therefore, not only the component design becomes difficult, but also the manufacturing conditions are restricted in each process such as rolling and annealing, which makes manufacturing difficult.
　Therefore, in this design method, (1) the yield stress of the steel sheet and (2) the yield stress of the adhesive layer are set so that the deformation of the steel sheet is regulated when the rotor rotates at the maximum rotation speed when the automobile is running. do. That is, not only the yield stress of the steel sheet but also the yield stress of the adhesive layer is taken into consideration. As a result, even when the yield stress of the steel sheet is low to some extent, the deformation of the steel sheet can be regulated by increasing the yield stress of the adhesive layer. This is because the adhesive layer can suppress the deformation of the steel sheet by partially guaranteeing the function of suppressing the deformation carried by the steel sheet.
　Mises stress ・ In particular, the force generated in the thickness direction increases and the thickness of the steel sheet decreases, causing the steel sheet to deform. As a result of diligent studies by the present inventors, it has been found that it is effective to use an adhesive layer having a high yield stress in order to suppress a decrease in the thickness of the steel sheet. By using a bond layer having a high yield stress, deformation of the steel sheet in the plastic region can be suppressed. As a result, the minimum amount of deformation of the steel sheet becomes the amount of deformation in the elastic region, and the upper limit of the deformation of the steel sheet, which is the limit of use, can be suppressed.
　Generally, the higher the strength of a steel sheet, the more limited the supply suppliers and the higher the cost. On the other hand, the strength of the adhesive has a positive correlation with the cost, and the higher the strength of the adhesive, the higher the curing temperature is required.
　In this design method, by considering not only the yield stress of the steel sheet but also the yield stress of the adhesive layer as described above, the optimum combination of the steel sheet and the adhesive is selected according to not only the cost but also the regional characteristics and marketability. be able to. Therefore, it is possible to manufacture a rotor that meets not only quality requirements but also manufacturing requirements. That is, if the invention of the present application is used, the above-mentioned manufacturing is difficult, the supply suppliers are limited, high-strength steel sheets that are costly are not used, and special steel sheet hardening treatment or heat treatment is performed on the fine parts of the rotor. Deformation of the steel sheet can be suppressed without increasing the number of steps for strengthening the steel sheet.
[0015]
　When the yield stress of the steel plate is YPR ( MPa), the yield stress of the adhesive layer is YP B (MPa), and the maximum rotation speed is ω (rpm), the equation (1) below is satisfied. The yield stress YP R of the steel plate and the yield stress YP B of the adhesive layer may be set. [Number 2] 　Here, A = 0.105, B = 17,000, C = 17,000, D = 410, E = 30.

[0016]
The yield stress YP R of the steel sheet and the yield stress YP B of the adhesive layer may be set 　so as to further satisfy the following equation (2) .
0.1 × YP R ≦ YP B ≦ 10 × YP R　　・ ・ ・ (2)
[0017]
　As the method for manufacturing the rotor according to the present invention, the method for designing the rotor is used.
Effect of the invention
[0018]
　According to the present invention, it is possible to provide a rotor in which damage at high speed rotation is suppressed.
A brief description of the drawing
[0019]
FIG. 1 is a plan view showing a part of a rotor according to an embodiment of the present invention.
FIG. 2 is a cross-sectional view taken along the line AA shown in FIG.
FIG. 3 is a cross-sectional view taken along the line BB shown in FIG.
[Fig. 4] Fig. 4 is a graph showing the relationship between the number of rotations of the rotor and the amount of displacement of the outer edge of the laminated core.
FIG. 5 is a plan view showing an analysis result of Mises stress distribution of a steel sheet when the rotation speed of the rotor is 14000 rpm.
FIG. 6 is a perspective view showing an analysis result of Mises stress distribution of a steel sheet when the rotation speed of the rotor is 14000 rpm.
FIG. 7 is a plan view showing an analysis result of Mises stress distribution of a steel plate when the rotation speed of the rotor is 15,000 rpm.
FIG. 8 is a perspective view showing an analysis result of Mises stress distribution of a steel sheet when the rotation speed of the rotor is 15,000 rpm.
FIG. 9 is a plan view showing an analysis result of Mises stress distribution of a steel sheet when the rotation speed of the rotor is 16000 rpm.
FIG. 10 is a perspective view showing an analysis result of Mises stress distribution of a steel sheet when the rotation speed of the rotor is 16000 rpm.
FIG. 11 is a diagram for explaining the displacement of the outer edge of the laminated core, and is a cross-sectional view including the outer edge of the laminated core in a state where the rotor is not rotating.
FIG. 12 is a diagram for explaining the displacement of the outer edge of the laminated core, and is a cross-sectional view including the outer edge of the laminated core in a state where the rotor is rotating at high speed.
[Fig. 13] Fig. 13 is a graph showing the relationship between the number of rotations of the rotor and the magnitude of stress generated in the adhesive layer.
FIG. 14 is a graph showing the relationship between the strength of a steel plate that can withstand a predetermined rotation speed and the strength of an adhesive layer.
Embodiment for carrying out the invention
[0020]
　Hereinafter, a rotor for a motor according to an embodiment of the present invention will be described with reference to FIGS. 1 to 14.
[0021]

　As shown in FIGS. 1 to 3, the rotor 10 is incorporated in a motor for traveling an automobile (for example, a hybrid automobile or an electric automobile). The motor is an inner rotor type IPM motor (embedded magnet 30 type motor). The rotor 10 is a magnet-embedded type. The maximum rotation speed of the motor is determined according to the performance characteristics required for the automobile, and tends to be high when the maximum speed, acceleration, or miniaturization of the motor is emphasized. The maximum rotation speed is, for example, 11000 rpm or more, and more specifically, 12000 rpm or more and 20000 rpm or less.
[0022]
　In the following, the axial direction of the rotor 10 (the direction of the central axis O of the rotor 10) is referred to as the axial direction, and the radial direction of the rotor 10 (the direction orthogonal to the central axis O of the rotor 10) is referred to as the radial direction. The direction (the direction that orbits around the central axis O of the rotor 10) is called the circumferential direction.
[0023]
　The rotor 10 includes a laminated core 20, a magnet 30, and a sealing resin 40.
　The laminated core 20 includes a steel plate 21 laminated to each other and an adhesive layer 22 for adhering the adjacent steel plates 21 in the stacking direction Z. The stacking direction Z coincides with the axial direction. Further, in the present embodiment, the steel plates 21 adjacent to each other in the stacking direction Z are not fixed by means different from the adhesive layer 22 (for example, caulking). These steel plates 21 are fixed only by the adhesive layer 22.
[0024]
　The steel plate 21 is an electromagnetic steel plate. The steel plate 21 is formed, for example, by punching an electromagnetic steel plate. As the electromagnetic steel sheet, a known electrical steel sheet can be used. The chemical composition of the electrical steel sheet is not particularly limited. In this embodiment, non-oriented electrical steel sheets are used as the electrical steel sheets. As the non-oriented electrical steel sheet, for example, a non-oriented electrical steel strip of JISC2552: 2014 can be adopted.
[0025]
　The adhesive layer 22 is an adhesive cured between the steel plates 21 adjacent to each other in the stacking direction Z. As the adhesive, for example, a thermosetting adhesive by polymerization bonding is used. As the composition of the adhesive, (1) an acrylic resin, (2) an epoxy resin, (3) a composition containing an acrylic resin and an epoxy resin, and the like can be applied. If the strength (yield stress) of the adhesive layer 22 exceeding 80 MPa is required, a resin called super engineering plastic may be used as the adhesive.
[0026]
　The adhesive layer 22 adheres a portion of the steel plate 21 including at least the bridge 23. The bridge 23 is a portion of the steel plate 21 located outside the magnet 30 in the radial direction. In the illustrated example, the adhesive layer 22 adheres the steel plates 21 adjacent to each other in the stacking direction Z over the entire surface. If the thickness of the adhesive layer 22 is less than 1 μm, adhesion is poor, and if it exceeds 10 μm, the motor efficiency is lowered. Therefore, the thickness of the adhesive layer 22 is preferably 1 to 10 μm.
[0027]
　The magnet 30 is a permanent magnet. The magnet 30 is embedded in the laminated core 20. In this embodiment, a set of two magnets 30 form one magnetic pole. The plurality of sets of magnets 30 are arranged at equal intervals in the circumferential direction (every 45 ° in the illustrated example). The two magnets 30 forming the same magnetic pole are formed line-symmetrically in the circumferential direction with reference to the virtual line L extending in the radial direction.
[0028]
　A through hole 24 is formed in the laminated core 20. The through hole 24 penetrates the laminated core 20 in the laminating direction Z. The through hole 24 is provided corresponding to the magnet 30. Each magnet 30 is fixed to the laminated core 20 in a state of being arranged in the corresponding through hole 24. Each magnet 30 is fixed to the laminated core 20 by an adhesive provided between the outer surface of the magnet 30 and the inner surface of the through hole 24. The adhesive may be of the same type as the adhesive forming the adhesive layer 22.
[0029]
　In the present embodiment, gaps 25 and 26 in which the magnet 30 is not arranged are provided in each through hole 24. The gaps 25 and 26 are provided one on each side in the circumferential direction with respect to the magnet 30. As the gaps 25 and 26, a first gap 25 and a second gap 26 are provided. The first gap 25 is located on the virtual line L side along the circumferential direction with respect to the magnet 30. The second gap 26 is located on the opposite side of the virtual line L along the circumferential direction with respect to the magnet 30.
[0030]
　The sealing resin 40 is arranged in the through hole 24. The sealing resin 40 seals between the outer surface of the magnet 30 and the inner surface of the through hole 24. For the sealing resin 40, for example, the same adhesive as the adhesive forming the adhesive layer 22 can be adopted. As the sealing resin 40, a composition containing (1) an acrylic resin, (2) an epoxy resin, (3) an acrylic resin and an epoxy resin can be applied. The adhesive of the adhesive layer 22 and the adhesive of the sealing resin 40 may be the same or different. The sealing resin 40 seals the second gap 26. As a result, the two magnets 30 forming the same magnetic pole are sandwiched in the circumferential direction by the two sealing resins 40. The yield stress of the sealing resin 40 is preferably 10 MPa or more and 200 MPa or less. When the yield stress of the sealing resin 40 is within this range, the stress generated in the adhesive layer 22 can be reduced.
[0031]
　As the various dimensions of the rotor 10, for example, the dimensions shown below are preferable.
(1) Diameter of rotor 10 (laminated core 20, steel plate 21): 50 mm or more and 200 mm or less
(2) Thickness of steel plate 21 T1: 0.1 mm or more and 2.0 mm or less
(3) Thickness of adhesive layer 22 T2: 2 μm 4 μm or more
(4) Stack thickness of laminated core 20: 30 mm or more and 300 mm or less
[0032]
　In the present embodiment, when the rotor 10 rotates at 11000 rpm for 30 seconds or more, the maximum amount of radial displacement of the outer edge 20a of the laminated core 20 is 0.1 mm or less. In the illustrated example, when the rotor 10 rotates at a rotation speed of 14000 rpm or less, the maximum displacement amount is 0.1 mm or less.
[0033]
　The maximum amount of displacement of the outer edge 20a of the laminated core 20 in the radial direction can be obtained, for example, by the following methods (1) and (2).
(1) At the outer edge 20a of the laminated core 20, the amount of change in the radial position before or after rotation for each position along the circumferential direction of the rotor 10 (for example, every 11.25 ° or every 15 °) (for example, every 11.25 ° or every 15 °). The dimension D) shown in FIG. 12 is obtained, and the maximum value among the values ​​obtained by adding the elastic deformation during rotation to the change amount (hereinafter, also referred to as the external displacement amount) is defined as the maximum displacement amount. The displacement amount can be measured using, for example, a laser displacement meter.
(2) In the outer edge 20a of the laminated core 20, when the portion most displaced before and after rotation is known in advance (for example, when it is theoretically clear or grasped by simulation or empirical rule), that portion. The amount of change in the radial position before and after rotation is obtained, and the amount of change is defined as the maximum displacement amount.
[0034]
　Further, in the present embodiment, the yield stress (yield point, strength) of the steel plate 21 is YPR ( MPa), and the yield stress (yield point, strength) of the adhesive layer 22 is YP B (MPa). When the maximum rotation speed is ω (rpm), each value of YPR and YP B satisfies the following equations (1) and (2).
[0035]
[Number 3]

　Here, A = 0.105, B = 17,000, C = 17,000, D = 410, E = 30.
[0036]
0.1 × YP R ≦ YP B ≦ 10 × YP R　　・ ・ ・ (2)
[0037]
By satisfying the above equation (1) for each value of YPR and YP 　B , it is regulated that the bridge 23 of the steel plate 21 is deformed and plastically deformed in the elastic region when the rotor 10 is rotated at the maximum rotation speed. To. In other words, the bridge 23 is elastically deformed and not plastically deformed. Further, when the rotor 10 rotates at 11000 rpm, the maximum amount of displacement of the outer edge 20a of the laminated core 20 in the radial direction is 0.1 mm or less. When the rotor 10 rotates at 11000 rpm, the bridge 23 is deformed within the elastic region, so that at least the outer edge 20a of the laminated core 20 is deformed by about 0.020 μm in the radial direction. The maximum amount of radial displacement of the outer edge 20a of the laminated core 20 may be 30 μm or more.
[0038]
When each value of YPR and YP 　B satisfies the above equation (2), the yield stress YP B of the adhesive layer 22 can be kept in the optimum range. That is, when the yield stress YP B of the adhesive layer 22 is less than 0.1 times the yield stress YP R of the steel sheet 21, the yield stress YP B of the adhesive layer 22 is too low and may be deformed at low rotation. When the yield stress YP B of the adhesive layer 22 is more than 10 times the yield stress YP R of the steel sheet 21, the yield stress YP B of the adhesive layer 22 is too high and the effect is saturated, and economic efficiency is not established.
[0039]
　The yield stress YPR of the steel sheet 21 is preferably 150 MPa or more and 580 MPa or less. The yield stress YP B of the adhesive layer 22 is preferably 10 MPa or more and 200 MPa or less.
[0040]
As an example of the method for measuring 　the yield stress YPR of the steel sheet 21 , the following method can be mentioned.
　That is, the steel plate 21 used for the laminated core 20 is cut into a test piece having a predetermined shape (for example, a rectangular shape of 35 mm × 250 mm). Then, using this test piece, a tensile test conforming to JIS Z 2241: 2011 is carried out. When the test piece of the steel plate 21 is cut out from the laminated core 20 and the yield stress is measured, for example, there is a method of converting the test piece into tensile strength based on the result of the hardness measurement. Specifically, the hardness of the steel sheet 21 is measured, and the hardness is converted into tensile strength using a hardness conversion table (JIS handbook) based on the obtained hardness. Since the general yield ratio of the steel material is 0.73 (0.69 to 0.75), the yield stress of the steel sheet 21 can be calculated from the converted tensile strength.
[0041]
An example of a method for measuring the yield stress YP B of 　the adhesive layer 22 is the method shown below.
　That is, the adhesive layer 22 used for the laminated core 20 is cut into a test piece having a predetermined shape (for example, a rectangular shape of 10 mm × 110 mm). Then, using this test piece, a tensile test conforming to JIS K 7161-1 (2014) is carried out.
[0042]
　If the material used for the steel plate 21 and the adhesive layer 22 is known, it is possible to independently prepare a test piece using the material instead of preparing the test piece from the rotor 10. As an example of the method for measuring the yield stress of the adhesive layer 22 in such a case, a method of solidifying the adhesive into strips to prepare a sample piece of the adhesive layer 22 and performing a tensile test is recommended. In the case of an adhesive having a poor filling rate, a thin filter paper may be attached to the back surface to prepare a sample piece. As the shape of the test piece, a shape conforming to JIS K 7161-2: 2014 may be adopted. When the adhesive layer 22 is taken out from the laminated core 20, an adhesive layer 22 is obtained by preparing an approximately 30% by mass hydrochloric acid aqueous solution, immersing the laminated core 20 in the hydrochloric acid aqueous solution, and dissolving the steel plate 21. You may. The immersion time can be appropriately adjusted according to the amount and size of the steel sheet 21. Further, especially when the laminated core 20 is large, the hydrochloric acid aqueous solution may be replaced in the middle in order to promote the dissolution reaction. After all the steel plates 21 are melted, the adhesive layer 22 is taken out and washed. After cleaning, the test piece is processed into a test piece conforming to JIS K 7161-2: 2014, and the yield stress of the adhesive layer 22 is evaluated. The composition of the adhesive layer 22 may be analyzed by infrared spectroscopy (FT-IR) or the like, and a test piece may be prepared from the same material using the analysis result.
[0043]

　A motor was prepared in order to confirm the relationship between the rotation speed of the rotor 10 and the external displacement amount. A rotor 10 having a diameter of 162 mm was incorporated in this motor. The rotor 10 has a laminated core 20 in which a steel plate 21 having a yield stress YPR of 400 MPa and a plate thickness of 0.25 mm and an adhesive layer 22 having a yield stress YP B of 12 MPa and a thickness of 2.5 μm are laminated. In each of the tests shown below, a rotor 10 of the same size is assumed.
[0044]
　In this motor, the rotation speed of the rotor 10 was changed from 0 rpm to 17,000 rpm, and the amount of external displacement of the rotor 10 was measured. This external displacement amount is the external displacement amount with respect to the specific measurement point P as shown in FIG. 1 in the outer edge 20a of the laminated core 20. The measurement point P is a position (a part of the bridge 23) of the outer edge 20a of the rotor 10 that intersects the virtual line L.
[0045]
　The results are shown in FIG. The horizontal axis of FIG. 4 indicates the rotation speed of the rotor 10. The vertical axis of FIG. 4 shows the amount of external displacement at the measurement point. As shown in FIG. 4, as the rotation speed of the rotor 10 increases, the centrifugal force in the radial direction of the rotor 10 increases, and the external displacement amount of the rotor 10 increases. Then, when the specific rotation speed (14000 rpm) is exceeded, the external displacement amount of the rotor 10 suddenly increases.
[0046]

　Here, in order to examine the cause of the rapid increase in the amount of external displacement, the inventor of the present application quantified the stress generated in the bridge 23 during high-speed rotation by FEM analysis.
　The analysis results of the Mises stress distribution in the bridge 23 of the steel plate 21 are shown in FIGS. 5 to 10. 5 and 6 show a case where the rotation speed of the rotor 10 is 14000 rpm. 7 and 8 show the case where the rotation speed of the rotor 10 is 15,000 rpm. 9 and 10 show a case where the rotation speed of the rotor 10 is 16000 rpm.
[0047]
　In FIGS. 5 to 10, the shade of the hatch indicates the magnitude of the Mises stress (note that the magnet 30 and the sealing resin 40 are also hatched, but the Mises stress in the magnet 30 and the sealing resin 40 is , Less than the lower limit of contour display). Mises stress refers to the equivalent stress used to indicate the stress state generated inside an object with a single value.
　For example, in FIGS. 5 and 6, two types of hatches, a thin hatch and a dark hatch, are shown on the steel plate 21. In these figures, a thin hatch means that the Mises stress is less than 380 MPa. A dark hatch means that the Mises stress is 380 MPa to 430 MPa. In this rotor 10, the yield stress YPR of the steel sheet 21 is 356 MPa, and it is considered that the steel sheet 21 is surely plastically deformed in the region of the dark hatch.
[0048]
　Comparing the analysis results of FIGS. 5 and 6 (14000 rpm), the analysis results of FIGS. 7 and 8 (15000 rpm), and the analysis results of FIGS. 9 and 10 (16000 rpm), as the number of revolutions increases, the number of revolutions increases. It can be seen that the region where the hatch is dark, that is, the region where the Mises stress is large and the plastic deformation is performed, is rapidly increasing.
[0049]
　From the above analysis results, it was confirmed that in this rotor 10, when the rotor 10 was rotated at a rotation speed exceeding 14000 rpm, plastic deformation occurred in the bridge 23. It is considered that this result leads to a rapid increase in the amount of external displacement when rotating at a rotation speed exceeding 14000 rpm as shown in FIG.
[0050]

　In order to examine the factors of stress increase as described above, the shape of the steel plate 21 before and after the rotation of the rotor 10 will be considered.
　As shown in FIG. 11, when the rotor 10 is not rotating, centrifugal force is not acting and the steel sheet 21 is not stretched.
　On the other hand, as shown in FIG. 12, when the rotor 10 rotates at high speed, the centrifugal force in the radial direction of the rotor 10 increases, so that the steel plate 21 is stretched in the radial direction of the rotor 10 (broken line in FIG. 12). When the steel sheet 21 is stretched in this way, the thickness of the outer peripheral portion of the steel sheet 21 is reduced. As a result, it is considered that stress concentration is caused and the above-mentioned rapid increase in Mises stress occurs.
[0051]
　From the above, it is considered that the amount of external displacement of the rotor 10 can be reduced by suppressing the radial stretching of the laminated steel plates 21 when the rotation speed of the rotor 10 is increased.
　Then, the inventor of the present application can consider a measure for suppressing the stretching of the steel sheet 21 by the adhesive layer 22.
[0052]
　The strength of the adhesive used for the adhesive layer 22 usually indicates the strength (adhesion force, peel strength) when the object to be adhered is peeled off, but in the present embodiment, the adhesive layer 22 is pulled in the stacking direction Z. Although stress is generated, the shearing force is extremely small, so the strength of the adhesive layer 22 itself (tensile strength), that is, the yield stress YP B that suppresses the internal deformation of the adhesive layer 22, is more important than the adhesion force. The higher the yield stress YP B
　that suppresses the internal deformation of the adhesive layer 22, the greater the effect of suppressing the stretching of the laminated steel sheet 21. That is, when a tensile stress is generated in the radial direction of the rotor 10, the adhesive layer 22 suppresses the deformation of the steel plate 21. This makes it possible to reduce the amount of external displacement of the rotor 10 even if the rotation speed of the rotor 10 increases.
[0053]
　FIG. 13 is a graph showing the relationship between the rotation speed of the rotor 10 and the stress generated in the adhesive layer 22 in the stacking direction Z. The horizontal axis of FIG. 13 indicates the rotation speed of the rotor 10. The vertical axis of FIG. 13 shows the stress generated in the adhesive layer 22. Of the graph lines shown in FIG. 13, the solid line indicates the case where the sealing resin 40 is not present, and the broken line indicates the case where the sealing resin 40 (yield stress: 12 MPa) is present.
[0054]
　As shown in FIG. 13, as the rotation speed of the rotor 10 increases, the stress generated in the adhesive layer 22 in the stacking direction Z increases. By forming the laminated core 20 having the adhesive layer 22 that can withstand the stress in the laminated direction Z, the radial stretching of the rotor 10 of the laminated steel plate 21 is suppressed, and even if the rotation speed of the rotor 10 is increased. , It is possible to reduce the amount of external displacement of the rotor 10. It can also be seen from FIG. 13 that when the sealing resin 40 is present, the stress generated in the adhesive layer 22 is reduced in the range where the rotation speed is 16000 rpm or less.
[0055]
The reference value of the yield stress of the adhesive layer 22 is calculated based on the following equation (3) when
　the rotation speed of the rotor 10 is ω and the yield stress of the steel plate 21 is YPR . The inventor has found that it can be done. Equation (3) is the right-hand side of equation (1) above. The strength of the adhesive layer 22 needs to satisfy the condition of the above equation (1).
[0056]
[Number 4]

　Here, A = 0.105, B = 17,000, C = 17,000, D = 410, E = 30.
[0057]
　For example, when the rotation speed is 17,000 rpm, the diameter of the rotor 10 is 162 mm, the plate thickness of the steel plate 21 is 0.25 mm, and the thickness of the adhesive layer 22 is 0.002 mm, each value of YPR and YP B is given by the formula (1). It was confirmed by verification using an actual machine that the maximum displacement amount of the laminated core 20 was 0.1 mm or less of the target value by satisfying the above.
[0058]
First, the relationship between the rotation speed of the rotor 10 and the yield stress YP R of the steel plate 21 and the yield stress YP B of the adhesive layer 22
　where plastic deformation does not occur is determined by using FEM analysis. rice field. The results are shown in Table 1 below.
[0059]
[table 1]

[0060]
　In Table 1, the heading column (first column) shows the YPR (MPa) of the yield stress of the steel sheet 21 . The heading line (first line) indicates the rotation speed (rpm) of the rotor 10. The value in each cell is when the rotor 10 rotates at the rotation speed of the heading row of the column to which the cell belongs, and the yield stress YPR of the steel plate 21 of the heading column of the row to which the cell belongs is assumed. , The value of the yield stress YP B (MPa) of the adhesive layer 22 required for the steel sheet 21 not to be plastically deformed is shown. The blank cell means that the yield stress YP B of the adhesive layer 22 under the conditions corresponding to the cell is not obtained.
[0061]
　Next, the above relationship obtained from the above equation (1) is shown in Table 2 below. The view of Table 2 is the same as that of Table 1. Each value in the table in Table 2 is a value obtained by rounding off the value obtained from the right side of the above equation (1) to the first decimal place. In Table 2, the yield stress YP B of the adhesive layer 22 is obtained in more cases than in Table 1 .
[0062]
[Table 2]

[0063]
　As a result of comparing the values ​​in Tables 1 and 2 above, it was confirmed that the difference between the two values ​​was small and the result of the FEM analysis could be approximated by the equation (1).
[0064]
　As described above, the rapid increase in the amount of external displacement can be realized by adjusting the yield stress of the adhesive layer 22 and adjusting the yield stress of the steel sheet 21.
[0065]
When designing
　the rotor 10, the yield stress of the steel plate 21 and the yield stress of the adhesive layer 22 are set as follows. That is, when the rotor 10 rotates at the maximum rotation speed and the centrifugal force is transmitted from the magnet 30 to the laminated core 20, the deformation of the steel plate 21 is restricted (the stress generated in the steel plate 21 yields to the steel plate 21). Set each yield stress (so as not to reach the stress YPR ). Specifically, each yield stress is set so that each yield stress satisfies the above equations (1) and (2).
[0066]
　Here, the graph of FIG. 14 shows the boundary line obtained by the above equation (1). The horizontal axis of the graph in FIG. 14 shows the YPR of the yield stress of the steel sheet 21 . Of the graph lines in FIG. 14, the solid graph line shows the value ((3)) on the right side of the equation (1) when the rotation speed is 16000 rpm. The broken line graph line shows the value on the right side of Eq. (1) (Equation (3)) when the rotation speed is 17,000 rpm. The graph line of the chain line shows the value on the right side of Eq. (1) (Equation (3)) when the rotation speed is 18000 rpm.
[0067]
　In order to obtain a laminated core 20 that can withstand each rotation speed, the combination of the yield stress YPR of the steel plate 21 and the yield stress YP B of the adhesive layer 22 is set on the upper right of the graph line of each rotation speed shown in FIG. Must be a combination included in the area. In other words, in the combination of the strength of the adhesive layer 22 and the strength of the steel plate 21 included in the upper right region of the graph line shown in FIG. 14, all the combinations can withstand each rotation speed. However, when the combination of the yield stress YPR of the steel plate 21 and the yield stress YP B of the adhesive layer 22 is included in the lower left region of the graph line of each rotation speed shown in FIG. 14, the rotor 10 rotates. This is not preferable because the maximum displacement of the outer edge of the laminated core in the radial direction of the rotor 10 exceeds 0.1 mm. In addition, although the deformation strength can be increased in the upper right region, unnecessary high-strength steel sheets are used, which causes problems with punching accuracy and production inhibition due to die wear. It is important to design it so that it is on the line.
[0068]
　For example, when creating a rotor 10 that can withstand 17,000 rpm, a combination of a steel plate 21 with a strength of 360 MPa and a strength of the adhesive layer 22 of 142 MPa or a combination of a steel plate 21 with a strength of 400 MPa and a strength of the adhesive layer 22 of 52 MPa is selected.
[0069]
The rotor 10
　designed by using the above design method can be manufactured by a known manufacturing method. For example, the method for manufacturing the rotor 10 using an adhesive includes a method of applying an adhesive to each of the steel plates 21, an impregnation immersion method, a method of using an adhesive processed into a tape shape, and an in-mold adhesive. Methods etc. have been proposed. In the present embodiment, any manufacturing method can be used, and the manufacturing method is not limited.
[0070]
　As described above, according to the rotor 10 according to the present embodiment, when the rotor 10 rotates at 11000 rpm, the maximum displacement amount of the outer edge 20a of the laminated core 20 in the radial direction of the rotor 10 is 0.1 mm or less. Is. Therefore, even when the rotor 10 rotates at the maximum rotation speed (for example, a rotation speed exceeding 11000 rpm) during traveling of the automobile, deformation of the outer shape of the rotor 10 is suppressed, and for example, the rotor 10 comes into contact with the stator. It is possible to prevent such things as doing. As a result, damage to the motor can be suppressed.
[0071]
　Further, according to the rotor 10 designed by the design method according to the present embodiment, when the rotor 10 rotates at the maximum rotation speed during traveling of the automobile and the centrifugal force is transmitted from the magnet 30 to the laminated core 20. The adhesive layer 22 suppresses the deformation of the steel plate 21 in the radial direction, and the deformation of the steel plate 21 is restricted. Therefore, even when the rotor 10 rotates at the maximum rotation speed during traveling of the automobile, it is possible to suppress the deformation of the outer shape of the rotor 10 and prevent the rotor 10 from coming into contact with the stator, for example. As a result, damage to the motor can be suppressed.
[0072]
　By the way, for the adhesive layer 22, evaluation based on the adhesive strength (adhesive force with the steel plate 21 under conditions such as tension, compression, shearing, and 90 degree peeling) has been emphasized. Against this background, there was no technical idea to regulate the deformation of the steel sheet 21 based on the yield stress of the adhesive layer 22. In order to regulate the deformation of the steel plate 21, there was essentially no choice but to use a high-strength steel plate 21. As a result, the cost of the rotor 10 becomes high, and it becomes difficult to manufacture the rotor 10. In particular, when the electromagnetic steel sheet 21 is adopted as the steel sheet 21, it is necessary to satisfy the requirements for high strength in addition to the basic characteristics (low iron loss, high magnetic flux density). Therefore, not only the component design becomes difficult, but also the manufacturing conditions are restricted in each process such as rolling and annealing, which makes manufacturing difficult.
[0073]
　Therefore, in this design method, the rotor 10 rotates at the maximum rotation speed during traveling of the automobile, and when the centrifugal force is transmitted from the magnet 30 to the laminated core 20, the steel plate 21 is deformed in the radial direction of the rotor 10. (1) The yield stress of the steel plate 21 and (2) the yield stress of the adhesive layer 22 are set so that the adhesive layer 22 is suppressed and the deformation of the steel plate 21 is regulated. That is, not only the yield stress of the steel plate 21 but also the yield stress of the adhesive layer 22 is taken into consideration. As a result, even when the yield stress of the steel plate 21 is low to some extent, the deformation of the steel plate 21 can be regulated by increasing the yield stress of the adhesive layer 22.
[0074]
　Here, the higher the strength of the steel sheet 21, the more limited the supply suppliers and the higher the cost. On the other hand, the strength of the adhesive has a positive correlation with the cost, and the higher the strength of the adhesive, the higher the curing temperature is required.
　In this design method, by considering not only the yield stress of the steel sheet 21 but also the yield stress of the adhesive layer 22 as described above, the optimum combination of the steel sheet 21 and the adhesive according to not only the cost but also the regionality and marketability. Can be selected. Therefore, it is possible to manufacture the rotor 10 that satisfies the requirements not only in terms of quality but also in terms of manufacturing.
[0075]
　As described above, the relationship between the strength of the adhesive layer 22 and the strength of the steel plate 21 has been defined by using a specific mathematical formula, but the present invention is not limited to this example. Any person who has ordinary knowledge in the field of the art to which the present invention belongs may come up with various modifications or modifications, including modifications of mathematical formulas, within the scope of the technical ideas described in the claims. It is clear that these are also naturally understood to belong to the technical scope of the present invention.
[0076]
　For example, in the rotor 10 in the embodiment, a pair of magnets 30 form one magnetic pole, but the present invention is not limited to this. One magnet 30 may form one magnetic pole, or three or more magnets 30 may form one magnetic pole.
　Equations (1) and (2) may not be satisfied.
　The sealing resin 40 may be omitted. The first gap 25 and the second gap 26 may be omitted.
Code description
[0077]
10 Rotor
20 Laminated core
20a Outer edge
21 Steel plate
22 Adhesive layer
23 Bridge
24 Through hole
30 Magnet
40 Encapsulating resin
The scope of the claims
[Claim 1]
　A magnet-embedded rotor incorporated in a motor for traveling an automobile, which
　is a laminated core having a steel plate laminated to each other and an adhesive layer for adhering the steel plates adjacent to each other in the laminated direction, and
　a magnet embedded in the laminated core. And,
　when the rotor rotates at 11000 rpm, the maximum displacement amount of the outer edge of the laminated core in the radial direction of the rotor is 0.1 mm or less.
[Claim 2]
The rotor according to claim 1, 　wherein the yield stress YPR of the steel sheet is 150 MPa or more and 580 MPa or less.
[Claim 3]
　When the yield stress of the steel sheet is YPR ( MPa), the yield stress of the adhesive layer is YP B (MPa), and the maximum rotation speed during traveling of the automobile is ω (rpm), the following 　equation (1) is used. The rotor according to claim 1 or 2, which satisfies the above conditions. [Number 1] 　Here, A = 0.105, B = 17,000, C = 17,000, D = 410, E = 30.

[Claim 4]
　The rotor according to claim 3, which further satisfies the following equation (2).
0.1 × YP R ≦ YP B ≦ 10 × YP R　　・ ・ ・ (2)
[Claim 5]
　The magnet is arranged in a through hole penetrating the laminated core in the laminating direction,
　and a sealing resin for sealing between the outer surface of the magnet and the inner surface of the through hole is provided in the through hole. The rotor according to any one of claims 1 to 4.
[Claim 6]
　A method for designing a magnet-embedded rotor incorporated in a motor for traveling an automobile, 　wherein the
　rotor includes
　a laminated core having a steel plate laminated to each other and an adhesive layer for adhering the steel plates adjacent to each other in the laminating direction. It comprises
a magnet embedded in the laminated core, and in the
　design method, the maximum outer edge of the laminated core directed in the radial direction of the rotor when the rotor rotates at the maximum rotation speed during traveling of the automobile. A method for designing a rotor that sets the yield stress of the steel sheet and the yield stress of the adhesive layer so that the displacement amount is 0.1 mm or less.
[Claim 7]
　When the yield stress of the steel plate is YPR ( MPa), the yield stress of the adhesive layer is YP B (MPa), and the maximum rotation speed is ω (rpm), the 　equation (1) below is satisfied. The rotor design method according to claim 6, wherein the yield stress YP R of the steel plate and the yield stress YP B of the adhesive layer are set. [Number 2] 　Here, A = 0.105, B = 17,000, C = 17,000, D = 410, E = 30.

[Claim 8]
The rotor design method according to claim 7, wherein the yield stress YPR of the steel sheet and the yield stress YP B of the adhesive layer are set 　so as to further satisfy the following equation (2) . 0.1 × YP R ≦ YP B ≦ 10 × YP R　　・ ・ ・ (2)
[Claim 9]
　A method for manufacturing a rotor using the method for designing a rotor according to any one of claims 6 to 8.