Embedded magnet type rotary motor and electric motor device
The embedded magnet type rotating electric machine improves torque responsiveness by using weight-reducing holes and inclined wall surfaces in the rotor core, ensuring stable torque transmission and reduced energy consumption.
Patent Information
- Authority / Receiving Office
- JP · JP
- Patent Type
- Patents
- Current Assignee / Owner
- HITACHI IND EQUIP SYST CO LTD
- Filing Date
- 2022-08-04
- Publication Date
- 2026-06-26
AI Technical Summary
Existing embedded magnet type rotating electric machines face challenges in improving the responsiveness of torque changes without causing torque reduction.
The design incorporates a rotor core with weight-reducing holes and inclined wall surfaces that position permanent magnets to enhance torque responsiveness while minimizing torque reduction, achieved by strategically arranging these holes to maintain magnetic force transmission and reduce moment of inertia.
The solution effectively suppresses torque reduction while enhancing the responsiveness of torque changes, leading to more efficient and energy-efficient operation of the electric machine.
Smart Images
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Abstract
Description
Technical Field
[0001] The present invention relates to an embedded magnet type rotating electric machine and an electric device using the same, and particularly to a stator having stator coils, a rotor core in which a plurality of permanent magnets are embedded, and a rotor that is rotatably held around the rotation axis inside the stator. The present invention relates to an embedded magnet type rotating electric machine including the above components and an electric device equipped with the embedded magnet type rotating electric machine.
Background Art
[0002] There are various techniques for improving an embedded magnet type rotating electric machine (IPM motor) including a stator having stator coils, a rotor core in which a plurality of permanent magnets are embedded, and a rotor that is rotatably held around the rotation axis inside the stator. For example, Patent Document 1 describes a technique of providing a plurality of laminated thin plate-like high magnetic permeability members having a higher magnetic permeability than the material of the rotor core in a substantially radial direction at an outer peripheral side portion in the circumferential direction end of the permanent magnet embedded in the rotor core of the rotor. Patent Document 1 describes that with the above-described configuration, it is possible to suppress the generation of eddy currents at the end of the permanent magnet and avoid damage to structural reliability. Further, Patent Document 1 describes forming a hollow recess in the rotor core in order to reduce the weight of the rotor core. The hollow recess can reduce the weight of the rotor core.
Prior Art Documents
Patent Documents
[0003]
Patent Document 1
Summary of the Invention
Problems to be Solved by the Invention
[0004] However, Patent Document 1 does not describe a method for improving the responsiveness of torque changes. If the responsiveness of the torque changes of the embedded magnet type rotating electric machine is high, the rotational force of the embedded magnet type rotating electric machine can be controlled more precisely. Therefore, even if the technology described in Patent Document 1 is used, there is a challenge in that it is not easy to improve the responsiveness of the torque changes of the embedded magnet type rotating electric machine.
[0005] The present invention aims to provide an embedded magnet type rotating electric machine and an electric motor equipped with the embedded magnet type rotating electric machine, which can suppress torque reduction while improving responsiveness to torque changes. [Means for solving the problem]
[0006] To solve the above problems, one embodiment of the embedded magnet type rotary motor of the present invention comprises a stator having a stator coil, and a rotor having a rotor core in which a plurality of permanent magnets are embedded and which is held rotatably around a rotation axis inside the stator, wherein the plurality of permanent magnets are held on the outer circumference of the rotor core at intervals from each other in the circumferential direction and have magnetic poles at both ends in the circumferential direction, the rotor core has a plurality of weight-reducing holes arranged at intervals from each other in the circumferential direction on the rotation axis side of the plurality of permanent magnets, each of the plurality of weight-reducing holes has a bottom wall surface portion extending in the circumferential direction on the rotation axis side, an outer circumferential wall surface portion on the outer circumference side, and a side wall surface portion connecting the bottom wall surface portion and the outer circumferential wall surface portion, and the outer circumferential wall surface portion has an inclined wall surface portion that approaches the rotation axis as it moves from the center of one of the plurality of permanent magnets toward the magnetic pole side. [Effects of the Invention]
[0007] According to the present invention, in an embedded magnet type rotating electric machine, it is possible to suppress the decrease in torque while improving the responsiveness of torque changes.
[0008] Other issues, configurations, and effects not mentioned above will be clarified by the following description of embodiments for carrying out the invention. [Brief explanation of the drawing]
[0009] [Figure 1] Figure 1 is a schematic side view of an example of an electric motor according to the embodiment. [Figure 2] Figure 2 is a schematic cross-sectional view of an embedded magnet type rotating electric machine. [Figure 3] Figure 3 is a schematic cross-sectional view of the rotor 100 of an embedded magnet type rotating electric machine. [Figure 4] Figure 4 is a schematic cross-sectional view of the rotor 100 of an embedded magnet type rotating electric machine. [Figure 5] This is an example of a graph showing the relative magnitude of the rotor's moment of inertia with respect to an angle α [deg]. [Figure 6] Figure 6 is an example of a graph showing the relative magnitude of torque with respect to angle α [deg]. [Figure 7] Figure 7 is a schematic cross-sectional view of the rotor 100 of an embedded magnet type rotating electric machine. [Figure 8] Figure 8 is a schematic cross-sectional view of the rotor 100 of an embedded magnet type rotating electric machine. [Modes for carrying out the invention]
[0010] The embodiments will be described below with reference to the drawings. In Figures 2-4, 7, and 8, hatching for cross-sectional indications has been omitted for clarity. Although the same parts are denoted by the same reference numerals in the figures and descriptions of the embodiments, the present invention is not limited to these embodiments, and any application that aligns with the spirit of the invention is included within the technical scope of the present invention. Furthermore, the positions, sizes, shapes, ranges, and numbers of each element shown in the drawings are merely examples to facilitate understanding of the invention, and the positions, sizes, shapes, ranges, and numbers of each element are not limited to those disclosed in this specification and drawings. <<Overall Structure>> <Configuration of the electric motor 500> Figure 1 is a schematic side view of an example of the electric motor 500 of this embodiment. The electric motor 500 shown in Figure 1 is a robot arm that includes a main body 510, a joint 520, an arm 530, and a power supply unit 540, as an example of an electric motor equipped with an embedded magnet type rotating electric machine 1. The electric motor 500 can bend at the joint 520 between the main body 510 and the arm 530. Inside the joint 520 is an embedded magnet type rotating electric machine 1 that controls the bending of the arm 530 at the joint 520. The power supply unit 540 supplies electricity to the embedded magnet type rotating electric machine 1.
[0011] The electric motor 500 shown in Figure 1 is an example of an electric motor equipped with an embedded magnet type rotating electric motor 1. The electric motor 500 only needs to be a device that uses the embedded magnet type rotating electric motor 1 as a drive source. The electric motor 500 may be, for example, a vehicle such as a hybrid car, electric vehicle, or railway car, an industrial robot, a bending machine, or a servo press.
[0012] <Configuration of Embedded Magnet Type Rotating Electric Machine 1> Figure 2 is a schematic cross-sectional view of the embedded magnet type rotating electric machine 1. As shown in Figure 2, the embedded magnet type rotating electric machine 1 comprises a rotor 100, a shaft 200, and a stator 300. Note that the rotor 100 shown in Figure 2 is just one example of the rotor 100, and rotor 100a, which will be described later, is shown in Figure 2. In the following, rotors 100a to 100d will be described as examples of embodiments. "Rotor 100" is a general term for rotors 100a to 100d.
[0013] The rotor 100 is held on the shaft 200 inside the stator 300. The shaft 200 is rotatably held in the embedded magnet type rotating electric machine 1. Therefore, the rotor 100 is rotatably held inside the stator 300, around the rotation axis of the shaft 200. As will be described in detail later, the rotor 100 has a rotor core 110 in which 10 permanent magnets 130 are embedded. Note that the number of permanent magnets 130 can be 2 or more, and may be a number other than 10. The rotor core 110 is also provided with through holes, which are weight-reducing holes 120.
[0014] The stator 300 has a cylindrical yoke 311 and teeth 312 that project inward from the yoke 311 and around which the stator coil 320 is wound. Ten teeth 312 and stator coils 320 are provided, respectively, the same number as the number of permanent magnets 130.
[0015] Due to the magnetic force of the stator coil 320 of the stator 300 and the magnetic force of the permanent magnet 140 of the rotor 100, the rotor 100 can rotate with respect to the stator 300. Note that the number of teeth 312 and stator coils 320 may be two or more, and may be a number other than 12.
[0016] <<Configuration of Rotor 100>> The rotor 100a, rotor 100b, rotor 100c, and rotor 100d described below are examples of the rotor 100. The shapes of the relief holes 120 are different among these rotors 100a to 100d. As described below, the rotor 100a (see FIG. 3) has a relief hole 120a. The rotor 100b (see FIG. 4) has a relief hole 120b with a different arrangement from the relief hole 120a. The rotor 100c (see FIG. 7) has a relief hole 120c formed with rounded corners. The rotor 100d (see FIG.) has relief holes 120d1 and 120d2 obtained by dividing the relief hole 120a into two.
[0017] <Configuration of Rotor 100a> FIG. 3 is a schematic cross-sectional view of the rotor 100a of the embedded magnet type rotating electrical machine 1. As shown in FIG. 3, the rotor 100a has a rotor core 110. (It should be noted that in the original text, there is no specific figure number in the sentence "図参照", so it is translated as "see FIG." for now. If there is a specific figure number in the original text, it needs to be filled in accurately.)
[0018] The rotor core 110 is made by laminating thin sheets of electromagnetic steel (e.g., 0.25-0.35 mm thick), which are punched out by a press and coated with a thin insulator, in the axial direction. The rotor core 110 is formed in a cylindrical shape. The rotor core 110 is held by the shaft 200 at its center. As mentioned above, the shaft 200 is rotatably held by the embedded magnet type rotating electric machine 1. Therefore, the rotor 100a is held inside the stator 300 so as to be rotatable around the axis of rotation of the shaft 200.
[0019] The rotor core 110a has magnet housing holes 111 for holding permanent magnets 130, weight-reducing holes 120a which are holes that penetrate the thin sheet-shaped electromagnetic steel plate of the rotor core 110, and bridge portions 112 between adjacent weight-reducing holes 120 in the circumferential direction.
[0020] The number of magnet storage holes 111 is 10. The 10 or more magnet storage holes 111 are provided on the outer circumference of the rotor core 110, spaced apart from each other in the circumferential direction. As a result, the 10 or more permanent magnets 130 are held on the outer circumference of the rotor core 110, spaced apart from each other in the circumferential direction.
[0021] The permanent magnet 130 is formed in a rectangular cross-section. The permanent magnet 130 is held in the magnet housing hole 111 such that the longer side of the rectangular cross-section faces radially outward from the rotor core 110. The permanent magnet 130 has magnetic poles 131a and 131b at both ends in the circumferential direction of the rotor core 110. The material of the permanent magnet 130 is a ferromagnetic material. The permanent magnet 130 may be formed from a ferromagnetic material such as ferrite, neodymium, or samarium-cobalt.
[0022] The weight-reducing holes 120a are through-holes that penetrate the aforementioned thin sheet-like electrical steel plate of the rotor core 110. The 10 weight-reducing holes 120a are arranged on the rotation axis Ar side of the rotor core 110 of the permanent magnet 130, spaced apart from each other in the circumferential direction. The weight-reducing holes 120a are located in positions that avoid the d-axis. In other words, the weight-reducing holes 120a are located between two adjacent d-axis.
[0023] Furthermore, of the lines that divide the weight-reducing hole 120a into two, the center line Ac extending radially outward from the rotation axis Ar of the rotor 100a is located at a position that coincides with the d-axis. Here, the d-axis is the line connecting the midpoint between the magnetic poles 131a and 131b of one permanent magnet 130 and the rotation axis Ar of the rotor 100. The q-axis is the line connecting the midpoint between the adjacent magnetic poles 131a and 131b of two circumferentially adjacent permanent magnets 130 and the rotation axis Ar of the rotor 100.
[0024] Each of the 10 weight-reducing holes 120a has a bottom wall portion 121 that extends circumferentially on the rotation axis Ar side of the rotor core 110, an outer circumferential wall portion 122 on the outer circumference side of the rotor core 110, and two side wall portions 123 that connect the bottom wall portion 121 and the outer circumferential wall portion 122 and extend radially across the rotor 100.
[0025] The outer periphery wall portion 122 has two inclined wall portions 122a. The two inclined wall portions 122a are connected on the q-axis. In addition, each of the two inclined wall portions 122a has a flat portion formed by a plane.
[0026] The angle α [deg] between the inclined wall surface 122a and the inter-pole axis Ap connecting the magnetic poles 131a and 131b at both ends of the permanent magnet 130 is greater than or equal to the angle θa [deg] obtained by dividing 180 degrees by the number of permanent magnets in Nm, and less than or equal to the angle 2θa [deg] obtained by dividing 360 degrees by the number of permanent magnets in Nm (θa ≤ α ≤ 2θa). In rotor 100a, the number of permanent magnets in Nm is 10, and θa = 18 [deg] (θa = 18 ≤ α ≤ 2θa = 36). As will be described in detail later, by setting the angle α in this way (θa ≤ α ≤ 2θa), it is possible to suppress the reduction of the magnetic force around the magnetic poles 131a and 131b of the permanent magnet 130 due to the weight-reducing holes 120a, and to reduce the moment of inertia of rotor 100. The effects of other rotors 100a will be described later.
[0027] <Configuration of Rotor 100b (Figure 4)> Figure 4 is a schematic cross-sectional view of the rotor 100b of the embedded magnet type rotating electric machine 1. In the following description of rotors 100b to 100d, components similar to those of rotor 100a are denoted by the same reference numerals, and their descriptions are omitted. As shown in Figure 4, rotor 100b has a weight-reducing hole 120b that is located in a different position from the weight-reducing hole 120a of rotor 100a shown in Figure 3. As shown in Figure 4, the weight-reducing hole 120b of rotor 100b is rotated by an angle θa [deg] (θa = 180 / Nm [deg]) around the rotation axis Ac of rotor 100a, where 180 degrees is divided by the number of permanent magnets Nm. As a result, the weight-reducing hole 120b of rotor 100b shown in Figure 4 is located where the center line Ac extending radially outward from the rotation axis Ac of rotor 100a coincides with the d-axis. Furthermore, the weight-reducing holes 120a in the rotor 100a shown in Figure 3 are located where the center line Ac, which extends radially outward from the rotation axis Ac of the rotor 100a, coincides with the q-axis.
[0028] <Effects of the invention in rotors 100a and 100b, Figures 5 and 6> The embedded magnet type rotating electric machine 1 can reduce the weight of the rotor core 110 and decrease the moment of inertia of the rotor core 110 by using the weight-reducing holes 120 (120a, 120b). Therefore, the embedded magnet type rotating electric machine 1 can improve the responsiveness of torque changes by using the weight-reducing holes 120.
[0029] Furthermore, the weight-reducing hole 120 has an inclined wall surface 122a on its outer circumferential wall surface 122a that approaches the rotation axis Ar as it moves from the center of the permanent magnet 130 toward the magnetic pole 131a or magnetic pole 131b. As a result, the magnetic poles 131a and 131b of the permanent magnet 130 are spaced apart from the inclined wall surface 122a on the permanent magnet 130 side of the weight-reducing hole 120, thus suppressing the reduction of the magnetic force of the magnetic poles 131a and 131b of the permanent magnet 130 by the weight-reducing hole 120. With the reduction of the magnetic force of the permanent magnet 130 suppressed by the weight-reducing hole 120, the magnetic force of the permanent magnet 130 can be transmitted to the rotor core 110 and act with the magnetic force of the stator coil 320 of the stator 300. Therefore, the embedded magnet type rotating electric machine 1 can suppress the reduction in torque due to the weight-reducing hole 120.
[0030] Based on the above, the embedded magnet type rotating electric machine 1 can suppress the decrease in torque while improving the responsiveness to torque changes.
[0031] Furthermore, the weight-reducing holes 120a and 120b are positioned such that the center line Ac extending radially outward from the rotation axis Ar of the rotors 100a and 100b coincides with the d-axis or q-axis of the permanent magnet 130. As a result, the weight-reducing holes 120a and 120b are positioned with a high degree of symmetry with respect to the permanent magnet 130. Consequently, the magnetic force of the stator coil 320 of the stator 300 does not act unevenly with respect to the magnetic force of the permanent magnet 130 due to the weight-reducing holes 120, allowing the rotors 100a and 100b to rotate more reliably and stably.
[0032] In the weight-reducing hole 120a (see Figure 3), the outer peripheral wall portion 122 has two inclined wall portions 122a that approach the rotation axis Ar as they move from the center of the permanent magnet 130 toward the magnetic pole 131a or magnetic pole 131b, and these portions are connected on the q-axis. That is, the portion of the outer peripheral wall portion 122 on the q-axis is reliably spaced away from the magnetic poles 131a and 131b of the permanent magnet 130. As a result, the magnetic poles 131a and 131b of the permanent magnet 130 are reliably spaced away from the weight-reducing hole 120a, and the reduction of the magnetic force of the magnetic poles 131a and 131b of the permanent magnet 130 by the weight-reducing hole 120a is suppressed. Therefore, the embedded magnet type rotating electric machine 1 can more reliably suppress the reduction in torque due to the weight-reducing hole 120a.
[0033] Furthermore, in the weight-reducing holes 120a and 120b, the inclined wall portion 122a, which approaches the rotation axis Ar of the rotor core 110 as it moves from the center of the permanent magnet 130 toward the magnetic pole 131a or magnetic pole 131b, has a flat portion formed from a plane. As a result, the peripheral portion of the outer peripheral wall portion 122 on the q-axis is more reliably separated from the magnetic poles 131a and 131b of the permanent magnet 130. This ensures that the magnetic poles 131a and 131b of the permanent magnet 130 are reliably separated from the weight-reducing holes 120, and the reduction of the magnetic force of the magnetic poles 131a and 131b of the permanent magnet 130 due to the weight-reducing holes 120 is more reliably suppressed. Therefore, the embedded magnet type rotating electric machine 1 can more reliably suppress the reduction in torque due to the weight-reducing holes 120.
[0034] Next, using Figures 5 and 6, we will explain a comparison between a weight-reducing hole 120a (see Figure 3) where the center line Ac coincides with the q-axis, and a weight-reducing hole 120b (see Figure 4) where the center line Ac coincides with the d-axis.
[0035] Figure 5 is an example of a graph showing the relative magnitude of the rotor's moment of inertia with respect to an angle α [deg]. In the graph of Figure 5, the relative magnitude of the rotor's moment of inertia represents the magnitude of the moment of inertia of the rotor 100 with the weight-reducing holes 120 relative to the moment of inertia of the rotor 100 without the weight-reducing holes 120. In other words, the relative magnitude of the rotor's moment of inertia represents the magnitude of the moment of inertia of the rotor 100 with the weight-reducing holes 120, when the magnitude of the moment of inertia of the rotor 100 without the weight-reducing holes 120 is set to 1.
[0036] As shown in the graph in Figure 5, the relative magnitude of the moment of inertia of the rotor 100 decreases as the angle α [deg] decreases for the weight-reducing holes 120a and 120b. Here, the difference between weight-reducing holes 120a and 120b is small.
[0037] Figure 6 is an example of a graph showing the relative magnitude of torque with respect to angle α [deg]. In the graph of Figure 6, the relative magnitude of torque represents the magnitude of torque of the rotor 100 with the weight-reducing holes 120 compared to the magnitude of torque of the rotor 100 without the weight-reducing holes 120. In other words, the relative magnitude of torque represents the magnitude of torque of the rotor 100 with the weight-reducing holes 120, when the magnitude of torque of the rotor 100 without the weight-reducing holes 120 is set to 1.
[0038] The moment of inertia is proportional to the square of the radius. Therefore, the moment of inertia of the rotor 100 decreases as the angle α [deg] decreases. However, as the angle α decreases, the rotor core 110 no longer exists around the magnetic poles 131a and 131b of the permanent magnet 130, and the magnetic force around the magnetic poles 131a and 131b of the permanent magnet 130 is reduced by the weight-reducing holes 120. As a result, the relative magnitude of the torque of the rotor 100 decreases as the angle α [deg] decreases.
[0039] As shown in the graph in Figure 6, the relative magnitude of the torque of the rotor 100 decreases little when the angle α[deg] is between 2θa[deg] and θa[deg] (θa = 180 / (number of Nm of permanent magnet 130)). On the other hand, when the angle α[deg] is between θa[deg] and 0, the decrease in the relative magnitude of the torque of the rotor 100 increases as the angle α[deg] approaches 0. From the above, it is suggested that the decrease in torque can be suppressed by setting the angle α[deg] between 2θa and θa[deg] (θa ≤ α ≤ 2θa). Therefore, based on the above, in the weight-reducing holes 120a to 120d of the embodiment, the angle α[deg] is set between 2θa and θa[deg] (θa ≤ α ≤ 2θa).
[0040] Thus, the angle α [deg] between the inclined wall surface 122a and the inter-pole axis Ap connecting the magnetic poles 131a and 131b at both ends of the permanent magnet 130 is greater than or equal to the angle θa [deg] obtained by dividing 180 degrees by the number of permanent magnets in Nm, and less than or equal to the angle 2θa [deg] obtained by dividing 360 degrees by the number of permanent magnets in Nm (θa ≤ α ≤ 2θa). As a result, the embedded magnet type rotating electric machine 1 can more reliably suppress the torque reduction caused by the weight-reducing holes 120. Consequently, the embedded magnet type rotating electric machine 1 can more reliably suppress the torque reduction while improving the responsiveness to torque changes.
[0041] Furthermore, as shown in the graph in Figure 6, when the angle α[deg] is between θa[deg] and 0, the relative magnitude of the torque of the rotor 100 is greater for the weight-reducing hole 120a with its centerline on the q-axis than for the weight-reducing hole 120b with its centerline on the d-axis.
[0042] In this case, for a weight-reducing hole 120a with its centerline on the q-axis, there is no weight-reducing hole 120 on the d-axis, but a bridge portion 112 exists. As magnetic flux flows through the bridge portion 112 formed between adjacent weight-reducing holes 120 in the circumferential direction, the magnetic force can act more effectively to rotate the rotor 100. As a result, the embedded magnet type rotating electric machine 1 can more reliably suppress the decrease in torque.
[0043] Furthermore, the electric motor 500 is equipped with an embedded magnet type rotating electric motor 1. The embedded magnet type rotating electric motor 1 is made lighter by the use of weight-reducing holes 120, which suppresses torque reduction while improving responsiveness to torque changes. Therefore, the electric motor 500 can be driven with less energy due to the lighter weight of the embedded magnet type rotating electric motor 1, and can be driven more efficiently due to the high responsiveness to torque changes of the embedded magnet type rotating electric motor 1. By driving efficiently, the electric motor 500 can reduce the energy required for operation and the amount of carbon dioxide emissions generated during operation, thereby mitigating global warming.
[0044] <Configuration of Rotor 100c> Figure 7 is a schematic cross-sectional view of the rotor 100c of the embedded magnet type rotating electric machine 1. As shown in Figure 7, the rotor 100c has weight-reducing holes 120c in which the corners of the weight-reducing holes 120a of the rotor 100a shown in Figure 3 have been changed to curved surfaces 120r.
[0045] Here, in the weight-reducing hole 120c, the closest point to the magnet storage hole 111 that holds the permanent magnet 130 is the corner of the inclined wall surface 122. The closer the corner of the outer peripheral wall surface 122 is to the magnet storage hole 111, the weaker the strength of the magnet storage hole 111 becomes in this close proximity.
[0046] On the other hand, in the embedded magnet type rotating electric machine 1, the corners of the outer peripheral wall portion 122 are formed with a curved surface 120r, causing the tips of the corners to recede inward. As a result, there is a gap between the magnet storage hole 111 and the corners of the outer peripheral wall portion 122. In this way, the weight-reducing holes 120c are separated from the magnet storage hole 111, ensuring the strength of the magnet storage hole 111.
[0047] Furthermore, because the corners of the weight-reducing holes 120c are formed with curved surfaces 120r, stress concentration at a portion of the corners of the weight-reducing holes 120c can be prevented from damaging the weight-reducing holes 120c. As described above, the embedded magnet type rotating electric machine 1 ensures the strength of the magnet housing holes 111 and the weight-reducing holes 120c because the corners of the weight-reducing holes 120c are formed with curved surfaces 120r.
[0048] <Configuration of Rotor 100d> Figure 8 is a schematic cross-sectional view of the rotor 100d of the embedded magnet type rotating electric machine 1. As shown in Figure 8, the rotor 100d has weight-reducing holes 120d1 and 120d2, which are obtained by dividing the weight-reducing holes 120a of the rotor 100a shown in Figure 3 along the q-axis.
[0049] The embedded magnet type rotating electric machine 1 can reduce the weight of the rotor core 110 and the moment of inertia of the rotor core 110 by using the weight-reducing holes 120d1 and 120d2. Therefore, the embedded magnet type rotating electric machine 1 can improve the responsiveness of torque changes by using the weight-reducing holes 120d1 and 120d2.
[0050] Furthermore, the weight-reducing holes 120d1 and 120d2 have an inclined wall surface 122a on the outer peripheral wall surface 122a that approaches the rotation axis Ar as it moves from the center of the permanent magnet 130 toward the magnetic pole 131a or magnetic pole 131b. As a result, the magnetic poles 131a and 131b of the permanent magnet 130 are spaced apart from the inclined wall surface 122a on the permanent magnet 130 side of the weight-reducing holes 120d1 and 120d2, thus suppressing the reduction of the magnetic force of the magnetic poles 131a and 131b of the permanent magnet 130 by the weight-reducing holes 120d1 and 120d2. With the reduction of the magnetic force of the permanent magnet 130 suppressed by the weight-reducing holes 120d1 and 120d2, the magnetic force of the permanent magnet 130 can be transmitted to the rotor core 110 and act with the magnetic force of the stator coil 320 of the stator 300. Therefore, the embedded magnet type rotating electric machine 1 can suppress the reduction in torque caused by the weight-reducing holes 120d1 and 120d2.
[0051] Based on the above, the embedded magnet type rotating electric machine 1 can suppress the decrease in torque while improving the responsiveness to torque changes.
[0052] Furthermore, since there are no weight-reducing holes 120d1 and 120d2 on the d-axis, magnetic flux flows through the bridge portion 112 formed between adjacent weight-reducing holes 120d1 and 120d2 in the circumferential direction, allowing the magnetic force to act more effectively to rotate the rotor 100. As a result, the embedded magnet type rotating electric machine 1 can more reliably suppress the decrease in torque.
[0053] Furthermore, the angle α[deg] between the inclined wall portion 122a and the inter-pole axis Ap connecting the magnetic poles 131a and 131b at both ends of the permanent magnet 130 is greater than or equal to the angle θa[deg] obtained by dividing 180 degrees by the number of permanent magnets in Nm, and less than or equal to the angle 2θa[deg] obtained by dividing 360 degrees by the number of permanent magnets in Nm (θa≦α≦2θa). As a result, the embedded magnet type rotating electric machine 1 can more reliably suppress the torque reduction caused by the weight-reducing holes 120. Consequently, the embedded magnet type rotating electric machine 1 can more reliably suppress the torque reduction while improving the responsiveness to torque changes.
[0054] It should be noted that the present invention is not limited to the embodiments described above, and various modifications are possible within the scope of its essence. [Explanation of Symbols]
[0055] 1: Embedded magnet type rotating electric machine 100, 100a~100d: Rotor 110: Rotor core 111: Magnetic storage hole 112: Bridge section 120, 120a~120d: Weight reduction holes 121:Bottom wall part 122: Outer wall surface 122a: Inclined wall section 122a1: Flat part 123: Side wall part 124: Curved surface 130: Permanent magnet 131a, 131b: Magnetic pole 200: Shaft 300: Status 310: Stator core 311: York 312: Teeth 320: Stator coil 500: Electric equipment 510: Main body 520: Joint 530: Arm section 540: Power supply unit Ar: Rotation axis Ac: Center line Ap: axis between magnetic poles d:d axis q:q axis Nm: Number of permanent magnets θa: Angle α: Angle
Claims
1. An embedded magnet type rotary motor comprising a stator having a stator coil, and a rotor having a rotor core with a plurality of permanent magnets embedded inside, and being held rotatably around a rotation axis inside the stator, The plurality of permanent magnets are held on the outer circumference of the rotor core at intervals from each other in the circumferential direction, and have magnetic poles at both ends in the circumferential direction. The rotor core has a plurality of weight-reducing holes arranged at intervals from each other in the circumferential direction on the rotation axis side of the plurality of permanent magnets, Each of the aforementioned plurality of weight-reducing holes has a bottom wall portion extending in the circumferential direction on the rotation axis side, an outer circumferential wall portion on the outer circumferential side, and a side wall portion connecting the bottom wall portion and the outer circumferential wall portion. The outer peripheral wall portion has an inclined wall portion that approaches the rotation axis as it moves from the center of one of the multiple permanent magnets toward the magnetic pole side, The aforementioned weight-reducing holes are located at a position where the center line extending radially outward from the rotation axis of the rotor coincides with the q-axis of the permanent magnet. The q-axis is a line connecting the midpoint between two adjacent magnetic poles of two adjacent permanent magnets in the circumferential direction and the axis of rotation. The outer peripheral wall portion has two of the inclined wall portions, The two aforementioned inclined wall surfaces are connected on the q-axis. Embedded magnet type rotary motor.
2. The embedded magnet type rotary motor according to claim 1, The aforementioned weight-reducing holes are provided at positions that avoid the d-axis of the permanent magnet. The d-axis is a line connecting the midpoint between the two magnetic poles at both ends in the circumferential direction of one permanent magnet and the axis of rotation. Embedded magnet type rotary motor.
3. The embedded magnet type rotary motor according to claim 1, The angle α [deg] between the inclined wall surface and the inter-pole axis connecting the magnetic poles at both ends of the permanent magnet is greater than or equal to θa [deg], which is obtained by dividing 180 degrees by the number of permanent magnets in Nm, and less than or equal to 2θa [deg], which is obtained by dividing 360 degrees by the number of permanent magnets in Nm. Embedded magnet type rotary motor.
4. The embedded magnet type rotary motor according to claim 1, The inclined wall portion has a flat portion formed by a plane, Embedded magnet type rotary motor.
5. The embedded magnet type rotary motor according to claim 1, The aforementioned weight-reducing holes have curved corners. Embedded magnet type rotary motor.
6. An electric motor device equipped with the embedded magnet type rotary motor described in claim 1.