Double-layered embedded magnet rotor, double-layered embedded magnet rotating electric machine, and method for manufacturing double-layered embedded magnet rotor

Abstract

According to embodiments, a two-layer magnet-embedded rotor (100) comprises: a rotor shaft (110); a rotor core (120) that includes first and second outer side accommodation holes (121, 122) and first and second inner side accommodation holes (124, 125); first and second outer side magnets (131, 132); and first and second inner side magnets (133, 134). The accommodation holes (121, 122) that are to the outer side in the radial direction are not in communication with the outer side of the outer circumference of the rotor core (120). The first inner side accommodation hole (124) and the second inner side accommodation hole (125) are in communication with the outer side of the outer circumference. The value of the inside open angle Θb1 at which radial-direction outer side walls (124a) and (125a) of the inner side accommodation holes open toward the outer side in the radial direction is equal to or higher than a prescribed value and is equal to or lower than the value of the outside open angle Θa at which radial-direction outer side walls (121a, 122a) of the outer side accommodation holes open toward the outer side in the radial direction.

Description

[Technical field]

[0001] An embodiment of the present invention relates to a double-layered embedded magnet rotor, a double-layered embedded magnet rotating electric machine, and a method for manufacturing a double-layered embedded magnet rotor. [Background technology]

[0002] In an IPM (Interior Permanent Magnet) type rotating electric machine in which permanent magnets are embedded inside the rotor, a shape has been proposed in which the bridge on the outer periphery is not connected and is open to the outside of the rotor core in order to reduce leakage flux. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2020-014322 A Summary of the Invention [Problem to be solved by the invention]

[0004] In a configuration in which two magnets are arranged in pairs in the circumferential direction on each pole of a rotor, and are arranged in two layers in the radial direction, if the bridges on the outer periphery of both layers are opened, the centrifugal stress generated at high rotation speeds will easily cause deformation beyond the mechanical strength of the iron part between the layers, resulting in breakage. Here, there are many examples in which the two paired magnets are arranged symmetrically with respect to the d-axis, which is the center of the magnetic pole (V-shaped arrangement).

[0005] To suppress deformation, it is necessary to increase the distance between the magnets in the layers and make the bridge in the circumferential center thicker. One way to achieve this is to make the angle between the paired magnets in the second layer smaller and more acute. However, this method means that the inner ends of the magnets in the second layer are positioned further inward in the radial direction. As a result, it is not possible to hollow out the core on the inner diameter side, which has less effect on torque characteristics, making it difficult to reduce the weight of the rotor.

[0006] Furthermore, in a rotor with a two-layer magnet pair arrangement, if the two-layer outer bridges are cut or removed, there will be parts where the centrifugal stress generated in the rotor exceeds the strength standard value. In order to keep the centrifugal stress below the standard value, there is a shape that reduces the opening angle of the two paired magnets in the second layer on the radial outside, but if the opening angle of the second layer is made too small, the torque will decrease in the medium to high speed range.

[0007] The object of the present invention is to provide a two-layer embedded magnet rotor and a two-layer embedded magnet rotating electric machine that can achieve both torque performance and strength in a configuration in which two paired magnets are arranged in two layers at each magnetic pole. [Means for solving the problem]

[0008] In order to achieve the above-mentioned object, a two-layer type embedded magnet rotor according to an embodiment of the present invention includes a rotor shaft extending in a rotation axis direction, a rotor core attached to the rotor shaft and having a first outer storage hole and a second outer storage hole formed to form a pair with each other on the radially outer side of each magnetic pole, and a first inner storage hole and a second inner storage hole formed to form a pair with each other on the radially inner side of the first outer storage hole and the second outer storage hole, and a rotor core stored in each of the first outer storage hole and the second outer storage hole. a first outer magnet and a second outer magnet housed in the first inner storage hole and a first inner magnet and a second inner magnet housed in the second inner storage hole, respectively; wherein the first outer storage hole and the second outer storage hole do not communicate with the outside of the outer circumference of the rotor core, and the first inner storage hole and the second inner storage hole have openings formed therein that communicate with the outside of the outer circumference of the rotor core, and a first inner storage hole radially outer wall of the first inner storage hole and a second inner storage hole radially outer wall of the second inner storage hole are formed in the first outer storage hole and the second inner storage hole. Wall anda value of an inner opening angle at which the first outer storage hole radially outer wall of the first outer storage hole and the second outer storage hole radially outer wall of the second outer storage hole open radially outward is equal to or greater than a predetermined value, and is equal to or less than a value obtained by adding 10 degrees to a value of an outer opening angle at which the first outer storage hole radially outer wall of the first outer storage hole and the second outer storage hole radially outer wall of the second outer storage hole open radially outward. It is characterized by: [Brief description of the drawings]

[0009] [Figure 1] 1 is a vertical cross-sectional view showing a configuration example of a double-layered embedded magnet rotating electric machine according to an embodiment; [Diagram 2] FIG. 2 is a partial cross-sectional view showing a configuration example of a two-layer embedded magnet rotor according to an embodiment. [Diagram 3] FIG. 2 is a flow diagram showing the steps of a method for manufacturing a two-layer embedded magnet rotor according to an embodiment. [Figure 4] FIG. 1 is a partial cross-sectional view showing an example that serves as a base for comparison with a two-layer embedded magnet rotor according to an embodiment. [Diagram 5] FIG. 2 is a partial cross-sectional view showing a two-layer embedded magnet rotor according to an embodiment. [Figure 6] 11 is a graph showing torque and stress in the case of a two-layer cut as a comparative example for explaining the effect of the two-layer embedded magnet rotor according to the embodiment. [Figure 7] 10 is a graph showing torque and stress in the case of a single cut layer according to the embodiment, for illustrating the effect of the two-layer embedded magnet rotor according to the embodiment. [Figure 8] 1 is a first graph showing the influence of the angular difference of the opening angle on the generated stress in a two-layer embedded magnet rotor according to an embodiment. [Figure 9] 11 is a second graph showing the influence of the angular difference of the opening angle on the generated stress in the two-layer embedded magnet rotor according to the embodiment. [Figure 10] 13 is a third graph showing the influence of the angular difference of the opening angle on the generated stress in the two-layer embedded magnet rotor according to the embodiment. [Figure 11]13 is a fourth graph showing the influence of the angular difference of the opening angle on the generated stress in the two-layer embedded magnet rotor according to the embodiment. [Figure 12] 13 is a fifth graph showing the influence of the angular difference of the opening angle on the generated stress in the two-layer embedded magnet rotor according to the embodiment. [Figure 13] 1 is a graph showing trends regarding opening angles and angle differences in a two-layer embedded magnet rotor according to an embodiment. [Figure 14] 1 is a graph showing a range of effective inward opening angles relative to outward opening angles in a two-layer embedded magnet rotor according to an embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Hereinafter, a double-layered magnet embedded rotor, a double-layered magnet embedded rotating electric machine, and a method for manufacturing a double-layered magnet embedded rotor according to an embodiment of the present invention will be described with reference to the drawings. Hereinafter, the same or similar parts will be denoted by the same reference numerals, and duplicated explanations will be omitted.

[0011] FIG. 1 is a vertical cross-sectional view showing a configuration example of a double-layered embedded magnet rotating electric machine 1 according to an embodiment.

[0012] The double-layered embedded magnet rotating electric machine 1 has a double-layered embedded magnet rotor 100, a stator 10, two bearings 20, two bearing brackets 30, and a frame 40.

[0013] The double-layered embedded magnet rotor 100 has a rotor shaft 110 extending in the direction of the rotation axis, a rotor core 120 attached to the radial outside of the rotor shaft 110, and permanent magnets 130 embedded in the rotor core 120. Of the permanent magnets 130, a first outer magnet 131 and a first inner magnet 133 are shown in Fig. 1, but details will be described later with reference to Fig. 2.

[0014] The stator 10 has a cylindrical stator core 11 disposed radially outside the rotor core 120 , and a stator winding 12 wound around the stator core 11 .

[0015] The two bearings 20 rotatably support the rotor shaft 110. Each of the two bearing brackets 30 statically supports each of the two bearings 20. The frame 40 is cylindrical, houses the stator 10, and has both ends connected to each of the two bearing brackets 30 to support them.

[0016] 2 is a partial cross-sectional view showing an example of the configuration of a two-layered embedded magnet rotor 100 according to an embodiment. The two-layered embedded magnet rotor 100 has an even number of magnetic poles 139, and magnetic poles 139 of opposite polarity, i.e., magnetic poles 139 with magnetic field lines in opposite directions, are alternately arranged adjacent to each other in the circumferential direction. FIG. 2 shows one of these magnetic poles 139.

[0017] Here, for convenience of explanation, directions will be defined. The direction parallel to the direction in which the axis CL of the rotor shaft 110 extends, i.e., the direction perpendicular to Fig. 2 (the front-to-back direction on the paper surface of Fig. 2), is called the axial direction. The direction away from the axis CL of the rotor shaft 110 is called the radial direction. Also, the direction in which the double-layered embedded magnet rotor 100 rotates is called the circumferential direction.

[0018] The two-layer embedded magnet rotor 100 according to this embodiment has a first outer magnet 131, a second outer magnet 132, a first inner magnet 133, and a second inner magnet 134 in each magnetic pole 139.

[0019] The first outer magnet 131 and the second outer magnet 132 of the first layer are arranged side by side with a gap in the circumferential direction, and are located opposite each other at the center in the circumferential direction. Similarly, the first inner magnet 133 and the second inner magnet 134 of the second layer are arranged side by side with a gap in the circumferential direction, and are located opposite each other at the center in the circumferential direction. The first inner magnet 133 and the second inner magnet 134 of the second layer are disposed radially inside the first outer magnet 131 and the second outer magnet 132 of the first layer, respectively.

[0020] 2 shows an example in which the first outer magnet 131 and the second outer magnet 132 are symmetrical to each other and the first inner magnet 133 and the second inner magnet 134 are symmetrical to each other with respect to the central axis (d-axis) of the magnetic pole 139 in a cross section perpendicular to the axial direction, that is, a so-called V-shaped arrangement, but is not limited to this. In other words, the first outer magnet 131 and the second outer magnet 132 may be different in size and may not be symmetrical in direction. Similarly, the first inner magnet 133 and the second inner magnet 134 may be different in size and may not be symmetrical in direction.

[0021] A plurality of storage holes are formed in the rotor core 120. That is, a first outer storage hole 121, a second outer storage hole 122, a first inner storage hole 124, and a second inner storage hole 125 are formed for respectively storing a first outer magnet 131 and a second outer magnet 132 of the first layer, and a first inner magnet 133 and a second inner magnet 134 of the second layer. The first outer storage hole 121, the second outer storage hole 122, the first inner storage hole 124, and the second inner storage hole 125 are regions with large magnetic resistance and each function as a flux barrier.

[0022] Rotor core 120 has a plurality of electromagnetic steel sheets 120a stacked in the axial direction. The housing holes formed in rotor core 120 and the shape of rotor core 120 are formed to have a cross section in the shape of electromagnetic steel sheets 120a by stacking electromagnetic steel sheets 120a.

[0023] The first outer storage hole 121 and the second outer storage hole 122 are adjacent to each other on the radially inner side, sandwiching one outer center bridge 123. Furthermore, the radially outer parts of each of the first outer storage hole 121 and the second outer storage hole 122 do not communicate with the radially outer side of the rotor core 120, and each outer bridge exists therein.

[0024] The first inner storage hole 124 and the second inner storage hole 125 are adjacent to each other on the radially inner side, sandwiching two inner center bridges 126. Furthermore, the radially outer parts of each of the first inner storage hole 124 and the second inner storage hole 125 communicate with the radially outer side of the rotor core 120. In other words, there are no outer bridges.

[0025] Here, the angle formed between the first outer storage hole radially outer wall 121a of the first outer storage hole 121 and the second outer storage hole radially outer wall 122a of the second outer storage hole 122, i.e., the angle at which they open outward in the radial direction, is referred to as the outer opening angle Θa. Similarly, the angle formed between the first inner storage hole radially outer wall 124a of the first inner storage hole 124 and the second inner storage hole radially outer wall 125a of the second inner storage hole 125, i.e., the angle at which they open outward in the radial direction, is referred to as the inner opening angle Θb.

[0026] FIG. 3 is a flow diagram showing the steps of a method for manufacturing the double-layered embedded magnet rotor 100 according to the embodiment.

[0027] The manufacturing method of the double-layered embedded magnet rotor 100 includes a manufacturing condition determination step S10 and a manufacturing step S20.

[0028] First, the manufacturing condition determination step S10 will be described. In the manufacturing condition determination step S10, first, the overall specifications of the two-layer embedded magnet rotor 100 are determined (step S11). At this stage, the shape and dimensions of the rotor shaft 110 and the fitting shape and dimensions of the rotor core 120 etc. attached to the rotor shaft 110 and the rotor shaft 110 are determined.

[0029] Next, the specifications of the permanent magnets 130 and the rotor core 120 are determined (step S12). The detailed procedure of step S12 is as follows.

[0030] First, the specifications of the permanent magnet 130 are determined (step S12a). Specifically, the specifications of the material, shape, dimensions, etc. of the first outer magnet 131 and the second outer magnet 132 arranged in the outer layer, and the first inner magnet 133 and the second inner magnet 134 arranged in the inner layer are determined.

[0031] Next, based on the determined shape and dimensions of the permanent magnet 130, the shape of the storage hole is determined by a conventional method (step S12b). That is, based on the shape and dimensions of each of the permanent magnets 130, the shape and dimensions of each of the storage holes, i.e., the first outer storage hole 121, the second outer storage hole 122, the first inner storage hole 124, and the second inner storage hole 125, are determined.

[0032] Next, a reference value of the outer opening angle Θa is determined (step S12c). That is, the value of the outer opening angle Θa, which is the angle between the first outer storage hole radially outer wall 121a of the first outer storage hole 121 and the second outer storage hole radially outer wall 122a of the second outer storage hole 122, is determined as a reference value. Here, if the first outer storage hole 121 and the second outer storage hole 122 have the same shape, they are arranged symmetrically about the central axis (d-axis) of the magnetic pole 139. Hereinafter, this is referred to as the reference shape.

[0033] Next, the range of the outer opening angle Θa is determined (step S12d). The range of the value of the outer opening angle Θa is set to a range including the reference value of the outer opening angle Θa. Note that it is preferable to set the range to a range that is considered to be achievable or a range that is desired to be realized, but the range may be set wider in order to grasp the tendency including the range outside the range.

[0034] Next, the ranges of the opening angle difference ΔΘ and the inner opening angle Θb are determined (step S12e). That is, the opening angle difference ΔΘ is changed based on the range of the outer opening angle Θa, and the torque and the tensile stress (hereinafter, "stress") in the inner center bridge 126 caused by the centrifugal force are calculated, and an appropriate range of the outer opening angle Θa, the opening angle difference ΔΘ, and the inner opening angle Θb are determined. As a result, the shape of the rotor core 120 is determined. Here, the opening angle difference ΔΘ is a value obtained by subtracting the inner opening angle Θb from the outer opening angle Θa.

[0035] Next, the manufacturing step S20 will be described. The manufacturing step S20 is sequentially carried out in accordance with the progress of the manufacturing condition determination step S10.

[0036] First, after the basic specifications are determined in step S11 of determining manufacturing conditions in step S10, the rotor shaft 110 is manufactured (step S21).

[0037] Next, after the permanent magnet specification determination step S12a is performed in the manufacturing condition determination step S10, the material is secured (step S22a) in the manufacturing of the permanent magnet 130 (step S22). If the shape of the permanent magnet 130 is fixed at this stage and there is no change, the permanent magnet processing step S22b described later may be performed at this point. Alternatively, if there is no problem with the period for arranging the material for the permanent magnet 130 in terms of delivery time, and if the shape of the permanent magnet 130 is to be finalized by the end of the manufacturing condition determination step S10, this step S22a and the permanent magnet processing step S22b may be performed together at an appropriate time before the end of the manufacturing condition determination step S10. The following shows an example in which the material for the permanent magnet 130 is secured in advance and the permanent magnet processing step S22b is performed after the end of the manufacturing condition determination step S10. That is, the case in which the shape of the permanent magnet 130 is finalized based on the determination results of the outer opening angle Θa and the inner opening angle Θb by the end of the manufacturing condition determination step S10 is shown.

[0038] Next, after the steps up to step S12e of determining the range of the opening angle difference ΔΘ and the inner opening angle Θb in the manufacturing condition determination step S10 are performed, the permanent magnet processing (step S22b) is performed as part of the manufacturing (step S22) of the permanent magnet 130. As described above, the manufacturing (step S22) of the permanent magnet 130 may be performed including the securing of materials in step S22a.

[0039] After steps up to step S12e are performed, the electromagnetic steel sheets 120a are produced by punching or the like (step S23). Next, the produced electromagnetic steel sheets 120a are stacked in the axial direction to assemble the rotor core 120 having a laminated structure (step S24).

[0040] After steps S21, S22, and S24 are completed, these are assembled (step S25). That is, the rotor core 120 is attached to the rotor shaft 110, and the permanent magnets 130 are housed in each housing hole of the rotor core 120. Next, other accessories are attached to the assembly of step S25 (step S26). This completes the assembly of the two-layered magnet-embedded rotor 100. Next, a post-assembly inspection of the two-layered magnet-embedded rotor 100 is performed (step S27).

[0041] Next, the main steps in the manufacturing condition determination step S10 will be described using an embodiment.

[0042] FIG. 4 is a partial cross-sectional view showing a base example 200, that is, a reference example for comparison with the two-layer embedded magnet rotor 100 according to the embodiment.

[0043] In this reference example, the shapes and dimensions of the first outer storage hole 121, the second outer storage hole 122, the first inner storage hole 124, and the second inner storage hole 125 are obtained in step S12b, and the outer opening angle Θa is obtained as a result of step S12c. In the reference example 200, the opening angle difference ΔΘ0 (=Θa-Θb0) may be set to any value, such as 10 degrees.

[0044] FIG. 5 is a partial cross-sectional view showing a double-layered embedded magnet rotor 100 according to an embodiment.

[0045] The dashed lines indicate the inner storage holes in the case of the reference example 200. The solid lines indicate the target model for determining the range of the outer opening angle Θa in step S12d for determining the two-layer type embedded magnet rotor 100, and for determining the range of the opening angle difference ΔΘ and the inner opening angle Θb in step S12e.

[0046] Regarding the determination of the range of the outward opening angle Θa in step S12d, in the following example, it is set to 100 degrees to 140 degrees.

[0047] In determining the opening angle difference ΔΘ in step S12e, i.e., in determining the inner opening angle Θb, the position of point P1 where the radial outermost part of the first inner magnet 133 contacts the first inner storage hole radial outer wall 124a is fixed to change the inclination of the first inner storage hole radial outer wall 124a. Similarly, the position of point P2 where the radial outermost part of the second inner magnet 134 contacts the second inner storage hole radial outer wall 125a is fixed to change the inclination of the second inner storage hole radial outer wall 125a. At this time, the lengths of the first inner magnet 133 and the second inner magnet 134 are not changed.

[0048] The method for changing the inner opening angle Θb is to ensure the circumferential distance between the magnetic poles 139 (FIG. 1). Therefore, this is only one example, and the present invention is not limited to this. For example, the tips of the openings 124c and 125c may be fixed. Alternatively, the fixing points may be opening tip 127a, opening tip 127b, or a part of the magnet holding protrusion 127c. The lengths of the first inner magnet 133 and the second inner magnet 134 may also be adjusted.

[0049] The evaluation results in step S12e of determining the range of the opening angle difference ΔΘ and the inner opening angle Θb are shown below.

[0050] FIG. 6 is a graph showing torque and stress in the case of a two-layer cut as a comparative example for explaining the effect of the two-layer embedded magnet rotor 100 according to the embodiment.

[0051] Here, the case of two-layer cut refers not only to a case where there is no outer bridge radially outside the inner storage hole and the inner storage hole is connected to the outside of the outer peripheral surface of rotor core 120, but also to a case where there is no outer bridge radially outside the outer storage hole and the inner storage hole is connected to the outside of the outer peripheral surface of rotor core 120.

[0052] The horizontal axis in Figure 6 represents the case, and shows the cases where the inner opening angle Θb is wider, smaller than the outer opening angle Θa but closer to the outer opening angle, and where it is narrower than that, with and without weight reduction on the radially inner side of the inner storage hole. The first vertical axis represents torque, and the second vertical axis represents stress. The bars, from light to dark, represent the maximum torque at low speed, maximum torque at medium speed, and maximum torque at high speed, respectively. The mottled bars on the right end of each represent stress. The stress is a relative value to the stress standard.

[0053] When the inside opening angle Θb shown in "wide angle" is widened, there is almost no effect of having the material cut out. Also, when the inside opening angle Θb is widened, the stress is about 1.9 times the standard stress value, which is not structurally viable.

[0054] When the inner opening angle Θb shown in "narrow angle" is narrowed, the stress decreases regardless of whether or not there is a cutout. In other words, in the case without cutouts, the stress decreases to 0.98 times the standard stress value. On the other hand, in the case with cutouts, the stress decreases to only 1.03 times the standard stress value, which is not structurally viable.

[0055] Furthermore, when the inward opening angle Θb is narrowed, in the case without the cutout, the maximum torque at low speed increases slightly, but the maximum torque at medium speed and high speed decreases by about 2% and 4%, respectively. Furthermore, in the case with the cutout, the maximum torque at low speed, medium speed and high speed decreases further.

[0056] Thus, in the case of the two-layer cut as a comparative example, narrowing the inner opening angle to suppress the stress below the standard value reduces the torque, especially in the medium and high speed ranges. Also, when trying to perform lightening on the inner diameter side of the permanent magnet to reduce weight, if a lightening hole shape that does not affect the torque when the opening angle is wide is applied to one with a narrow opening angle, the torque decreases. This causes a problem that it is difficult to reduce the weight.

[0057] 7 is a graph showing torque and stress in the case of one layer cut according to the embodiment, for explaining the effect of the two-layer embedded magnet rotor 100 according to the embodiment. Here, the case of one layer cut refers to a case where there is no outer bridge on the radial outside of the inner storage hole, the inner storage hole only communicates with the outside of the outer peripheral surface of the rotor core 120, and there is an outer bridge on the radial outside of the outer storage hole.

[0058] The horizontal and vertical axes in Fig. 7 are the same as those in Fig. 6. Also, each bar is the same as in Fig. 6.

[0059] In Fig. 7, the case where the inner opening angle Θb is narrowed, as shown by "narrow angle", is a case that differs from the case shown by "narrow angle" in Fig. 6 only in that there is an outer bridge on the radially outer side of the outer storage hole. This case also has the same tendency as the case where the inner opening angle Θb is narrowed, as shown by "narrow angle" in Fig. 6.

[0060] That is, in the case of a single-layer cut and a "narrow angle," the stress standard value is less than the case without cutouts, but the stress standard value is not met in the case with cutouts. Furthermore, in the case without cutouts, the maximum torque at medium and high speeds is lower than the maximum torque at low speeds. Furthermore, in the case with cutouts, the maximum torque at low and medium speeds is even lower. Thus, narrowing the inner opening angle to keep the stress below the standard value reduces the torque, especially in the medium and high speed ranges.

[0061] On the other hand, in the case of a single-layer cut with a wide inner opening angle Θb, shown by "wide angle," the maximum torque in the medium and high speed ranges increases to the same extent as or greater than the maximum torque in the low speed range, regardless of whether or not there is a cutout, as shown in Figure 7. On the other hand, in terms of stress, unlike the case of a two-layer cut, the single-layer cut does not increase even when the inner opening angle Θb, shown by "wide angle," is widened, and the stress satisfies the stress standard value regardless of whether or not there is a cutout.

[0062] Furthermore, by making the inner opening angle Θb wider, the space on the radially inner side of the inner center bridge 126 is expanded (see FIG. 5). As a result, it becomes easier to form a lightening hole for weight reduction.

[0063] The above is the reason why rotor core 120 is cut in one layer instead of two layers in this embodiment, and this result is reflected in step S12b of determining the reference shape of the receiving hole.

[0064] As described above, the method of decreasing the inner opening angle Θb is to ensure the circumferential distance between the magnetic poles 139 (FIG. 1). Therefore, this is only one example, and the present invention is not limited to this. For example, the tips of the openings 124c and 125c may be fixed. Alternatively, the fixing points may be opening tip 127a, opening tip 127b, or a part of the magnet holding protrusion 127c. The lengths of the first inner magnet 133 and the second inner magnet 134 may also be adjusted.

[0065] Next, the evaluation results in step S12e of determining the ranges of the opening angle difference ΔΘ and the inner opening angle Θb will be shown.

[0066] Fig. 8 is a first graph showing the influence of the opening angle difference on the generated stress in the two-layered embedded magnet rotor 100 according to the embodiment. The horizontal axis is the opening angle difference ΔΘ, i.e., the value obtained by subtracting the inner opening angle Θb from the outer opening angle Θa. The vertical axis is the generated stress, i.e., the stress (tensile stress) generated in the inner center bridge 126 due to centrifugal force. The same applies to Figs. 9 and 10.

[0067] Figure 8 shows an example where the outer opening angle Θa is 100 degrees. As shown in Figure 8, in the region where the opening angle difference ΔΘ, i.e., the positive absolute value, is large (right side of Figure 8), the generated stress in the case of the single-layer cut and the double-layer cut is about the same or slightly larger in the case of the single-layer cut. As the opening angle difference ΔΘ becomes smaller, i.e., as the inner opening angle Θb becomes larger, the stress increases in the case of the double-layer cut, whereas the stress gradually decreases in the case of the single-layer cut.

[0068] Looking at the decreasing value of the opening angle difference ΔΘ, the branching opening angle difference ΔΘb, which is the value of the opening angle difference ΔΘ where the stress trend in the case of the single-layer cut diverges from the stress trend in the case of the double-layer cut, is about 10.4 degrees on the graph. In other words, when the opening angle difference ΔΘ is about 10 degrees or less, the single-layer cut generates less stress than the double-layer cut, and the effect of the single-layer cut is realized. In other words, when the value of the inner opening angle Θb is increased beyond (Θa-ΔΘ), i.e. 90 (=100-10), the effect of the single-layer cut is realized.

[0069] FIG. 9 is a second graph showing the influence of the angular difference of the opening angle on the generated stress in the two-layer embedded magnet rotor 100 according to this embodiment.

[0070] Figure 9 shows an example where the outer opening angle Θa is 112 degrees. In this case, the branch opening angle difference ΔΘb is about 17 degrees on the graph. In other words, when the opening angle difference ΔΘ is about 17 degrees or less, the stress generated is smaller in the single-layer cut than in the double-layer cut, and the effect of the single-layer cut is realized. In other words, when the value of the inner opening angle Θb is increased beyond 95 (=112-17) degrees, the effect of the single-layer cut is realized.

[0071] FIG. 10 is a third graph showing the influence of the angle difference of the opening angle on the generated stress in the two-layer embedded magnet rotor 100 according to this embodiment.

[0072] Figure 10 shows an example where the outer opening angle Θa is 120 degrees. In this case, the branch opening angle difference ΔΘb is about 29 degrees on the graph. In other words, when the opening angle difference ΔΘ is about 29 degrees or less, the stress generated by the single-layer cut is smaller than that of the two-layer cut, and the effect of the single-layer cut is realized. In other words, when the value of the inner opening angle Θb is increased beyond 91 (= 120 - 29) degrees, the effect of the single-layer cut is realized.

[0073] FIG. 11 is a fourth graph showing the influence of the angular difference of the opening angle on the generated stress in the two-layer embedded magnet rotor according to the embodiment.

[0074] Figure 11 shows an example where the outer opening angle Θa is 130 degrees. In this case, the branch opening angle difference ΔΘb is about 36 degrees on the graph. In other words, when the opening angle difference ΔΘ is about 36 degrees or less, the stress generated by the single-layer cut is smaller than that of the two-layer cut, and the effect of the single-layer cut is realized. In other words, when the value of the inner opening angle Θb is increased beyond 94 (= 130 - 36) degrees, the effect of the single-layer cut is realized.

[0075] Figure 12 shows an example where the outer opening angle Θa is 140 degrees. In this case, the branch opening angle difference ΔΘb is about 34 degrees on the graph. In other words, when the opening angle difference ΔΘ is about 34 degrees or less, the stress generated by the single-layer cut is smaller than that of the two-layer cut, and the effect of the single-layer cut is realized. In other words, when the value of the inner opening angle Θb is increased beyond 106 (= 140 - 34) degrees, the effect of the single-layer cut is realized.

[0076] Fig. 13 is a graph showing the tendency of the opening angle and the angle difference in the two-layered embedded magnet rotor 100 according to the embodiment, and summarizes the results shown in Figs. 8 to 12. The horizontal axis is the outer opening angle Θa (degrees), the first vertical axis is the opening angle difference ΔΘ (degrees), and the second vertical axis is the inner opening angle (degrees). The solid line shows the branch opening angle difference ΔΘb, and the dashed line shows the branch inner opening angle Θbb. In other words, if the inner opening angle Θb is larger than the branch inner opening angle Θbb shown in Fig. 13, the generated stress is smaller in the case of the one-layer cut than in the case of the two-layer cut, and the effect of the one-layer cut is obtained.

[0077] 14 is a graph showing the range of effective inner opening angles relative to the outer opening angles in a two-layer embedded magnet rotor according to an embodiment. The horizontal axis is the outer opening angle Θa (degrees), and the vertical axis is the inner opening angle Θb (degrees).

[0078] First, the upper limit Θbmax of the range of the effective inner opening angle Θb will be described. As is clear from Fig. 8 to Fig. 12, as the absolute value of the opening angle difference ΔΘ becomes larger on the negative side, the degree to which the generated stress is smaller in the one-layer cut than in the two-layer cut increases monotonically. Now, when the opening angle difference ΔΘ, which is the minimum value of the horizontal axis shown in Fig. 8 to Fig. 12, is minus 10 degrees, the upper limit of the inner opening angle Θb is (outer opening angle Θa plus 10 degrees). For example, when the outer opening angle Θa is 100 degrees, the upper limit of the inner opening angle Θb is 110 degrees, and when the outer opening angle Θa is 140 degrees, the upper limit of the inner opening angle Θb is 150 degrees.

[0079] If the inner opening angle Θb becomes larger than the outer opening angle Θa plus 10 degrees, the difference in the amount of iron between the first outer magnet 131 and the second outer magnet 132 and the first inner magnet 133 and the second inner magnet 134 decreases, and the reluctance torque decreases, resulting in a negative effect. Therefore, Θbmax where the inner opening angle Θb becomes the outer opening angle Θa plus 10 degrees is set as the upper boundary line and is shown by a thick line in FIG.

[0080] Next, the branch open angle Θbb shown in FIG. 13 is indicated by a bold line in FIG. 14 as a lower limit line X.

[0081] As described above, when the angle range from 100 degrees to 140 degrees is selected as the region of the outer open angle Θa, within this region of the outer open angle Θa, the region where the inner open angle Θb is larger than the branch open angle Θbb shown by the thick line as the lower limit line X and is equal to or smaller than the straight line value of Θmax shown by the thick line as the upper boundary line is the effective region where the effect of one-layer cutting is produced.

[0082] Here, since it is not practical to use the broken line lower limit line X as shown in Fig. 14 as the lower boundary, it is effective to use a straight boundary line. From this point of view, a new lower boundary line is set, and the area above the value of the lower boundary line and below the value of the above-mentioned upper boundary line (based on Θbmax) is set as the effective area where the effect of cutting one layer is produced. As such a new lower boundary line, lines A, B, and C are shown in Fig. 14.

[0083] The straight line A is a straight line having a constant value. As shown in Fig. 13, when the outer opening angle Θa is in the range of 100 degrees to 130 degrees, the branch inner opening angle Θbb is 90 to 95 degrees. Therefore, the outer opening angle Θa is in the range of 100 degrees to 130 degrees, and the lower limit line X is commonly set to 96 degrees (>95).

[0084] Line B is a line where Θb = Θa - 10 (degrees). When Θa is 100 degrees, Θbb is 89.6 degrees, and the value of line A is 90 degrees. Therefore, line A is above the lower limit line X in Figure 14. In this case, the inner opening angle Θb is the outer opening angle Θa ± 10 degrees, and the inner opening angle Θb is defined as being in a range close to the outer opening angle Θa.

[0085] Line C is a line obtained by moving upward a line that envelops the lower limit line X. Specifically, in FIG. 14, line C is moved upward so as to provide a margin to the line (Θb=0.393·Θa+51.0) that connects the value of the lower limit line X when the outer opening angle Θa is 112 degrees and the value of the lower limit line X when the outer opening angle Θa is 140 degrees, and is given by, for example, the following formula (1). Θb=0.393Θa·x+52.0 …(1)

[0086] As described above, in the two-layer embedded magnet rotor 100 having a configuration in which two paired magnets are arranged in two layers at each magnetic pole, a single layer cut is made in which openings 124c, 125c are provided only for the storage holes in the inner layer, and by determining the range of the outer opening angle Θa and the ranges of the opening angle difference ΔΘ and the inner opening angle Θb, a two-layer embedded magnet rotor can be manufactured that can ensure both torque performance and structural strength.

[0087] The above is merely an example, and conditions such as the shape, dimensions, and position of the storage hole for the permanent magnet, and the circumferential width of the magnetic pole 139 may be appropriately selected and determined according to the above-mentioned procedure.

[0088] According to the embodiment described above, in a configuration in which two paired magnets are arranged in two layers at each magnetic pole, by cutting one layer, it is possible to achieve both torque performance and strength.

[0089] [Other embodiments] Although the embodiments of the present invention have been described above, the embodiments are presented as examples and are not intended to limit the scope of the invention. In addition, the features of each embodiment may be combined. Furthermore, the embodiments can be implemented in various other forms, and various omissions, substitutions, and modifications can be made without departing from the gist of the invention. The embodiments and their modifications are included in the scope of the invention and its equivalents as described in the claims, as well as in the scope and gist of the invention. [Explanation of symbols]

[0090] 1...two-layered magnet embedded rotating electric machine, 10...stator, 11...stator core, 12...stator winding, 20...bearing, 30...bearing bracket, 40...frame, 100...two-layered magnet embedded rotor, 110...rotor shaft, 120...rotor core, 120a...electromagnetic steel plate, 121...first outer storage hole, 121a...diametric outer wall of first outer storage hole, 121b...circumferential inner wall of first outer storage hole, 122...second outer storage hole, 122a...diametric outer wall of second outer storage hole, 122b...circumferential inner wall of first outer storage hole, 123...outer center bridge, 12 4...first inner storage hole, 124a...diametric outer wall of first inner storage hole, 124b...circumferential inner wall of first inner storage hole, 124c...opening, 125...second inner storage hole, 125a...diametric outer wall of second inner storage hole, 125b...circumferential inner wall of first inner storage hole, 125c...opening, 126...inner center bridge, 127a, 127b...opening tip, 127c...magnet holding protrusion, 130...permanent magnet, 131...first outer magnet, 132...second outer magnet, 133...first inner magnet, 134...second inner magnet, 139...magnetic pole, 200...reference example

Claims

1. A rotor shaft extending in a rotation axis direction; a rotor core attached to the rotor shaft, the rotor core having a first outer storage hole and a second outer storage hole formed to form a pair with each other on the radially outer side of each magnetic pole, and a first inner storage hole and a second inner storage hole formed to form a pair with each other on the radially inner side of the first outer storage hole and the second outer storage hole; a first outer magnet and a second outer magnet housed in the first outer housing hole and the second outer housing hole, respectively; a first inner magnet and a second inner magnet housed in the first inner housing hole and the second inner housing hole, respectively; A two-layer embedded magnet rotor comprising: the first outer housing hole and the second outer housing hole do not communicate with the outside of an outer periphery of the rotor core, the first inner housing hole and the second inner housing hole have openings formed therein that communicate with the outside of an outer periphery of the rotor core, a value of an inner opening angle at which a first inner storage hole radially outer wall of the first inner storage hole and a second inner storage hole radially outer wall of the second inner storage hole open outward in the radial direction is equal to or greater than a predetermined value, and is equal to or less than a value obtained by adding 10 degrees to a value of an outer opening angle at which a first outer storage hole radially outer wall of the first outer storage hole and a second outer storage hole radially outer wall of the second outer storage hole open outward in the radial direction. A two-layer embedded magnet rotor.

2. The outward opening angle is greater than or equal to 100 degrees and less than or equal to 130 degrees, The predetermined value of the inward opening angle is 96 degrees.

2. The two-layer embedded magnet rotor according to claim 1 .

3. The outward opening angle is greater than or equal to 100 degrees and less than or equal to 140 degrees, The predetermined value of the inner opening angle is the value of the outer opening angle minus 10 degrees.

2. The two-layer embedded magnet rotor according to claim 1 .

4. The outward opening angle is greater than or equal to 100 degrees and less than or equal to 140 degrees, The predetermined value of the inner opening angle is the value of the outer opening angle multiplied by 0.393 and then added to 51.

0.

2. The two-layer embedded magnet rotor according to claim 1 .

5. a bridge portion that separates the first outer housing hole and the second outer housing hole in the circumferential direction is one bridge portion; There are two bridge portions separating the first inner storage hole and the second inner storage hole in the circumferential direction.

2. The two-layer embedded magnet rotor according to claim 1 .

6. A two-layer embedded magnet rotor according to any one of claims 1 to 3, a stator including a cylindrical stator core disposed radially outside the rotor core and a stator winding wound around the stator core; two bearings that rotatably support the rotor shaft on both sides in the rotation axis direction; Two bearing brackets that statically support the two bearings, respectively; a frame that is disposed so as to cover the radial outside of the stator and supports the two bearing brackets; A magnet embedded type rotating electric machine comprising:

7. a rotor core attached to the rotor shaft, the rotor core having a first outer storage hole and a second outer storage hole formed at each magnetic pole to form a pair with each other on the radially outer side, each having no opening formed on the radially outer side, and a first inner storage hole and a second inner storage hole formed to form a pair with each other on the radially inner side of the first outer storage hole and the second outer storage hole, each having an opening formed on the radially outer side, a first outer magnet and a second outer magnet stored in the first outer storage hole and the second outer storage hole, respectively, the manufacturing method comprising: determining basic specifications of the two-layer embedded magnet rotor; manufacturing the rotor shaft based on the basic specifications; determining permanent magnet specifications of the first outer magnet, the second outer magnet, the first inner magnet, and the second inner magnet based on the basic specifications; determining a reference shape of each of the first outer storage hole, the second outer storage hole, the first inner storage hole, and the second inner storage hole; determining a value of an outer opening angle at which a first outer storage hole radially outer wall of the first outer storage hole and a second outer storage hole radially outer wall of the second outer storage hole open outward in a radial direction; a step of deriving an inner opening angle at which a first inner storage hole radially outer wall of the first inner storage hole and a second inner storage hole radially outer wall of the second inner storage hole open radially outward from the value of the outer opening angle, the inner opening angle being effective in reducing stress compared to a comparative example in which openings are formed radially outwardly of the first outer storage hole and the second outer storage hole; fabricating the first outer magnet, the second outer magnet, the first inner magnet, and the second inner magnet based on the permanent magnet specifications; manufacturing a plurality of electromagnetic steel sheets based on the reference shape of the storage hole, the outer opening angle, and the inner opening angle; assembling the plurality of electromagnetic steel sheets into a laminated structure; assembling the rotor shaft, the laminations, and the first outer magnet, the second outer magnet, the first inner magnet, and the second inner magnet; A method for manufacturing a two-layer embedded magnet rotor, comprising:

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