Rotary electrical machine and mobile body

Abstract

The present technology relates to a rotary electrical machine and a mobile body that make it possible to improve the quality of the rotary electrical machine. The rotary electrical machine comprises a stator and a rotor that rotates around the stator. The rotor is provided with: a rotary shaft; a yoke that is provided with a cylindrical portion that surrounds the periphery of the rotary shaft; a resin case that is integrally molded with the rotary shaft and the yoke and covers the outer peripheral surface of the cylindrical portion; and an anchor that protrudes from one of the outer peripheral surface of the cylindrical portion and the inner peripheral surface of the case that covers the outer peripheral surface of the cylindrical portion toward the other. The present technology can be applied, for example, to a drone.

Description

Rotating Electrical Machine and Moving Body

[0001] The present technology relates to a rotating electrical machine and a moving body, and particularly to a rotating electrical machine and a moving body with improved quality.

[0002] Conventionally, an outer-rotor type rotating electrical machine in which a permanent magnet and a yoke are integrally molded with a synthetic resin has been proposed (see, for example, Patent Document 1).

[0003] Japanese Patent Application Laid-Open No. 2008-86142

[0004] However, in an outer-rotor type rotating electrical machine, for example, due to variations in the coaxiality between the shaft and the yoke that occur during assembly, the center of gravity of the entire rotor deviates from the rotation center, resulting in variations in the amount of vibration during rotation of the rotor.

[0005] This technology has been made in view of such a situation, and aims to improve the quality of the rotating electrical machine. Further, this technology aims to improve the quality of the moving body using the rotating electrical machine by improving the quality of the rotating electrical machine.

[0006] The rotating electrical machine according to the first aspect of the present technology includes a stator and a rotor that rotates around the stator. The rotor includes a rotating shaft, a yoke having a cylindrical portion surrounding the rotating shaft, a resin case integrally formed with the rotating shaft and the yoke and covering the outer peripheral surface of the cylindrical portion, and a first anchor protruding from one of the outer peripheral surface of the cylindrical portion and the inner peripheral surface of the case covering the outer peripheral surface of the cylindrical portion in the direction of the other.

[0007] The moving body according to the second aspect of the present technology includes a stator and a rotor that rotates around the stator. The rotor includes a rotating shaft, a yoke having a cylindrical portion surrounding the rotating shaft, a resin case integrally formed with the rotating shaft and the yoke and covering the outer peripheral surface of the cylindrical portion, and an anchor protruding from one of the outer peripheral surface of the cylindrical portion and the inner peripheral surface of the case covering the outer peripheral surface of the cylindrical portion in the direction of the other, and includes a rotating electrical machine.

[0008] In the first or second aspect of this technology, the case and the yoke are fixed together by anchors.

[0009] This diagram schematically shows an example of the external configuration of a drone to which this technology is applied. This is a perspective view of the drone's motor. This is a cross-sectional view of the drone's motor. This is a perspective view of the motor's rotor. This is a cross-sectional view of the motor's rotor. This diagram explains the cause of variations in the coaxiality of the rotor shaft and yoke. This diagram schematically shows the air gap between the stator and the rotor. This diagram explains why variations in the cylindricity of the yoke are reduced. This diagram explains why the rotor is lighter. This is a cross-sectional view showing a first example of the rotor case anchor. This is an exploded view showing a first example of the rotor case anchor. This is a cross-sectional view showing a second example of the rotor case anchor. This is a cross-sectional view showing a third example of the rotor case anchor. This is a cross-sectional view showing a fourth example of the rotor case anchor. This is a cross-sectional view showing a fifth example of the rotor case anchor. This is an exploded view showing a first modified example of the shape of the rotor yoke groove. This is an exploded view showing a second modified example of the shape of the rotor yoke groove. This is a cross-sectional view showing a sixth example of the rotor case anchor. This is a cross-sectional view showing an example of the rotor yoke anchor. This is a cross-sectional view showing an example of the case anchor relative to the shaft. This figure shows a modified example of the groove in the shaft. It is a diagram intended to illustrate the effect of exposing the surface of the magnet without covering it with a case.

[0010] The following describes the embodiments for implementing this technology. The explanation will proceed in the following order: 1. Embodiments 2. Modified Examples 3. Others

[0011] <<1. Embodiments>> Embodiments of this technology will be described with reference to Figures 1 to 22.

[0012] <Example Configuration of Drone 1> Figure 1 schematically shows an example of the external configuration of Drone 1 to which this technology is applied. Note that the propellers are not shown in this figure.

[0013] Drone 1 comprises a main body 11, arms 12FL to 12RR, and motors 13FL to 13RR.

[0014] Arm 12FL extends diagonally forward to the left from near the front left of the main body 11. Arm 12FR extends diagonally forward to the right from near the front right of the main body 11. Arm 12RL extends diagonally backward to the left from near the rear left of the main body 11. Arm 12RR extends diagonally backward to the right from near the rear right of the main body 11.

[0015] A motor 13FL is provided at the tip of the arm 12FL. The rotation axis of the motor 13FL is oriented vertically (up and down), and the motor 13FL rotates the propeller horizontally.

[0016] A motor 13FR is provided at the tip of the arm 12FR. The rotation axis of the motor 13FR is oriented vertically (up and down), and the motor 13FR rotates the propeller horizontally.

[0017] A motor 13FL is provided at the tip of the arm 12RL. The rotation axis of the motor 13RL is oriented vertically (up and down), and the motor 13RL rotates the propeller horizontally.

[0018] A motor 13FR is provided at the tip of the arm 12RR. The rotation axis of the motor 13RR is oriented vertically (up and down), and the motor 13RR rotates the propeller horizontally.

[0019] Hereafter, unless it is necessary to distinguish between motors 13FL to 13RR individually, they will simply be referred to as motor 13.

[0020] <Example Configuration of Motor 13> Next, an example configuration of the motor 13 in Figure 1 will be explained with reference to Figures 2 to 5.

[0021] Figure 2 is a perspective view of the motor 13. Figure 3 is a cross-sectional view of the motor 13. Figure 4 is a perspective view of the rotor 102 of the motor 13. Figure 5 is a cross-sectional view of the rotor 102.

[0022] Motor 13 is an outer rotor type rotating electric machine. Specifically, motor 13 comprises a rotor 102, a stator 101, and a cable 103. Power supplied via the cable 103 causes the rotor 102 to rotate around (outside) the stator 101.

[0023] The stator 101 comprises a base 131, bearings 132, a core 133, and a coil 134. The rotor 102 comprises a case 151, a shaft 152, a yoke 153, and a plurality of magnets 154.

[0024] The base 131 is a component in which a cylindrical metal component (cylindrical component) is integrally molded in the center of a round tray-shaped component (round tray component) made of resin, which has a circular bottom surface and cylindrical sides.

[0025] The bearings 132 are positioned above and below the hollow portion of the central cylindrical part of the base 131.

[0026] The core 133 is a metal (for example, made of iron) member having a cylindrical inner circumference, a cylindrical outer circumference arranged concentrically with the inner circumference, and a plurality of teeth arranged radially between the inner and outer circumferences. The core 133 is attached to the base 131 such that the inner circumference surrounds the cylindrical portion of the base 131.

[0027] The coil 134 is wound around each tooth of the core 133.

[0028] Case 151 is a hollow, cylindrical, lid-shaped resin component having a circular top surface and cylindrical sides.

[0029] The shaft 152 is the axis of rotation of the metal rotor 102 and passes through the center of the top surface of the case 151.

[0030] The yoke 153 is a metal (e.g., made of iron) member having a cylindrical portion that surrounds the shaft 152, and is joined to the inner circumferential surface of the side surface of the case 151, as shown in Figure 5. That is, the yoke 153 is positioned along the inner circumferential surface of the side surface of the case 151, and the outer circumferential surface of the yoke 153 is covered by the inner circumferential surface of the case 151. The shaft 152 is positioned approximately in the center of the cylindrical portion of the yoke 153.

[0031] Each magnet 154 is plate-shaped and, as shown in Figure 5, is arranged on the inner circumferential surface of the yoke 153 so as to be aligned circumferentially at predetermined intervals. For example, each magnet 154 is fitted into a comb-shaped mounting portion formed near the boundary between the lid and cylindrical portion of the case 151, and fixed to the rotor 102 by pouring adhesive between it and the yoke 153. The surface of each magnet 154 (the surface facing the core 133) is exposed and not covered by the case 151 (resin).

[0032] The rotor 102 is placed over the stator 101 so as to surround the outer circumference of the core 133, and the shaft 152 is rotatably supported by the bearing 132. The rotor 102 then rotates around the outer circumference of the core 133, with the shaft 152 acting as the axis of rotation.

[0033] Hereinafter, the direction parallel to the shaft 152 (up and down direction) will be referred to as the axial direction, the direction of rotation of the rotor 102 will be referred to as the circumferential direction, and the direction perpendicular to the axial direction with the shaft 152 as the center will be referred to as the radial direction.

[0034] <Manufacturing Method and Effects of Rotor 102> Next, the manufacturing method and effects of rotor 102 will be explained with reference to Figures 6 to 9.

[0035] First, with reference to Figures 6 and 7, the problems with the conventional rotor 102 will be explained.

[0036] Figures 6A and 6B are cross-sectional views of the rotor 102 when the case 151 is made of metal. Figure 7 is a schematic plan view showing the area near the boundary between the stator 101 and the rotor 102.

[0037] For example, if the case 151 is made of metal, variations in the degree of coaxiality between the shaft 152 and the yoke 153 will occur when assembling the shaft 152 and the yoke 153 to the case 151.

[0038] For example, as shown in A of FIG. 6, when the shaft 152 is press-fitted into the case 151, the posture of the shaft 152 may be disturbed, or jamming may occur near the insertion port of the case 151. Further, if the shaft 152 is inserted into the case 151 with the disturbed posture, for example, in regions A1 and A2 in B of FIG. 6, uneven load distribution occurs, and the case 151 is deformed unevenly. Then, due to the disturbance of the posture of the shaft 152 after press-fitting, variation occurs in the coaxiality between the shaft 152 and the yoke 153.

[0039] When variation occurs in the coaxiality between the shaft 152 and the yoke 153, variation occurs in the amount of deviation of the center of gravity of the entire rotor 102 from the rotation center. When variation occurs in the amount of deviation between the center of gravity and the rotation center of the entire rotor 102, variation occurs in the amount of vibration generated during rotation of the rotor 102.

[0040] When the coaxiality between the shaft 152 and the yoke 153 varies, the variation in the air gap G1 between the outer peripheral portion of the stator 101 and the inner peripheral portion of the rotor 102 increases. When the variation in the air gap G1 increases, the fluctuation of the magnetic force acting on the rotor 102 becomes large, and the variation in the amount of vibration during rotation of the rotor 102 increases.

[0041] Thus, due to the variation in the coaxiality between the shaft 152 and the yoke 153, variation occurs in the amount of vibration during rotation of the rotor 102, and as a result, variation occurs in the quality of the motor 13.

[0042] In order to reduce this variation in the coaxiality between the shaft 152 and the yoke 153, for example, measures such as making the dimensions of the parts highly accurate, complicating the manufacturing jigs, and increasing the frequency of process management are required. Thereby, the manufacturing process and manufacturing cost of the motor 13 increase.

[0043] Next, referring to FIGS. 8 and 9, the manufacturing method and effects of the rotor 102 in the present technology will be described.

[0044] FIGS. 8 and 9 are partial cross-sectional views of the rotor 102. However, in FIGS. 8 and FIG. 9, the illustration of the magnet 154 is omitted.

[0045] In the following, similar to FIGS. 8 and 9, in the cross-sectional view of the rotor 102, the illustration of the magnet 154 may be omitted in order to make the figure easier to understand.

[0046] In the present technology, the case 151 is made of resin, and the shaft 152 and the yoke 153 are integrally formed (insert molding) with the case 151 as insert parts. Thereby, the variation in the coaxiality between the shaft 152 and the yoke 153 is reduced. That is, the coaxiality between the shaft 152 and the yoke 153 is suppressed within a predetermined range. Thereby, the amount of vibration during rotation of the rotor 102 and the variation in the air gap G1 between the outer peripheral portion of the stator 101 and the inner peripheral portion of the rotor 102 are suppressed, and the quality of the motor 13 is improved.

[0047] In addition, the cylindrical shape of the yoke 153 is likely to vary in the manufacturing process. For example, when manufacturing the yoke 153 by deep drawing, the cylindrical shape is likely to be disturbed in the cutting process of the drawn upper surface after deep drawing. For example, the outer periphery of the yoke 153 is likely to become elliptical.

[0048] When the cylindrical shape of the yoke 153 varies, the center of gravity of the yoke 153 deviates from the rotation center, and the rotational symmetry of the magnetic circuit is broken. As a result, the amount of vibration of the rotor 102 when the motor 13 is driven increases.

[0049] On the other hand, when the yoke 153 and the case 151 are integrally formed, as shown in FIG. 8, during the injection molding of the case

[0050] 151, the molding pressure on the case 151 is applied to the outer peripheral surface of the yoke 153. This molding pressure reduces the variation in the cylindrical shape generated in the manufacturing process of the yoke

[0051] 153. For example, the outer periphery of the yoke 153 becomes closer to a perfect circle.

[0050] Thereby, the deviation between the center of gravity of the yoke 153 and the rotation center is reduced, and the amount of vibration of the rotor 102 when the motor 13 is driven is reduced.

[0051] Furthermore, conventionally, when assembling the yoke 153 to the metal case 151, for example, the interface A11 between the case 151 and the yoke 153, as shown in Figure 9, is bonded with adhesive. This adhesive increases the weight of the rotor 102. When the weight of the rotor 102 increases, the variation in vibration increases when the center of gravity of the rotor 102 is shifted from the center of rotation. Also, when the weight of the rotor 102 increases, the inertia of the rotor 102 increases, and the control responsiveness of the motor 13 decreases.

[0052] In contrast, by changing the case 151 from metal to resin and insert-molding the yoke 153, bonding between the case 151 and the yoke 153 becomes unnecessary, and the rotor 102 is made lighter. Furthermore, by making the case 151 from resin, the case 151 is made lighter, and as a result, the rotor 102 is made lighter.

[0053] This reduces variations in the vibration of the rotor 102 and improves the control responsiveness of the motor 13.

[0054] Furthermore, it is conceivable that the case 151 could be made of aluminum to reduce weight. However, in this case, there is a concern that eddy currents will be more likely to be generated on the outer surface of the case 151 due to leakage flux, which may reduce the efficiency of the motor 13.

[0055] <Method to prevent the yoke 153 from coming off> As described above, by integrally molding the yoke 153 with the case 151, it becomes unnecessary to bond the contact surfaces between the case 151 and the yoke 153.

[0056] On the other hand, compared to the case where the case 151 and the yoke 153 are bonded together, the bonding strength between the case 151 and the yoke 153 may decrease. If the bonding strength between the case 151 and the yoke 153 decreases, for example, if an external force is applied to the motor 13 and a strong axial force is applied between the case 151 and the yoke 153 that pulls them apart, the yoke 153 may detach from the case 151.

[0057] In contrast, an example of a method to prevent the yoke 153 from detaching from the case 151 will be described with reference to Figures 10 to 17.

[0058] Figure 10 is a partial cross-sectional view of the rotor 102. Figure 11 is an unfolded view of the outer surface of the yoke 153.

[0059] In this example, a ring-shaped groove 153A with an axially symmetrical shape is formed so as to surround the outer surface of the yoke 153 360° in the circumferential direction, with the reference plane P1 as the center.

[0060] The reference plane P1 is a plane that passes through the axial center of the yoke 153 and is perpendicular to the axial direction.

[0061] Then, when the case 151 is integrally molded with the yoke 153, the resin of the case 151 fills the groove 153A. As a result, a ring-shaped and protruding anchor 151A with an axially symmetrical shape is formed on the inner circumferential surface of the cylindrical portion of the case 151, in accordance with the groove 153A. The anchor 151A protrudes from the inner circumferential surface of the cylindrical portion of the case 151 toward the outer circumferential surface of the yoke 153, is inserted into the groove 153A, and overlaps with the yoke 153 (and its groove 153A) in the axial direction.

[0062] As a result, even if an axial force is applied between the case 151 and the yoke 153, the anchor 151A will catch in the groove 153A, preventing the yoke 153 from coming off the case 151.

[0063] Next, with reference to Figures 12 to 14, we will describe modified configurations of the groove 153A and anchor 151A.

[0064] Figures 12 to 14 show a portion of the cross-sectional view of the rotor 102, similar to Figure 10.

[0065] For example, anchors 151A may be provided at multiple locations in the axial direction of the case 151.

[0066] In the example shown in Figure 12, two grooves 153A are formed on the outer circumferential surface of the yoke 153 at positions symmetrical in the axial direction, that is, positions symmetrical with respect to the reference plane P1. In addition, two anchors 151A are formed on the inner circumferential surface of the cylindrical portion of the case 151 at positions symmetrical in the axial direction, in accordance with the grooves 153A.

[0067] Note that the groove 153A and the anchor 151A do not necessarily have to be positioned symmetrically in the axial direction.

[0068] For example, in the example shown in Figure 13, one groove 153A is formed on the outer circumferential surface of the yoke 153 below the reference surface P1. Also, one anchor 151A is formed on the inner circumferential surface of the cylindrical portion of the case 151, aligned with the groove 153A of the yoke 153.

[0069] For example, in the example shown in Figure 14, two grooves 153A are formed on the outer circumferential surface of the yoke 153 below the reference surface P1. In addition, two anchors 151A are formed on the inner circumferential surface of the cylindrical portion of the case 151, aligned with the grooves 153A of the yoke 153.

[0070] Furthermore, grooves 153A and anchors 151A may be arranged in three or more locations in the axial direction. Also, grooves 153A and anchors 151A may be arranged above the reference plane P1, or they may be arranged in asymmetrical positions above and below the reference plane P1.

[0071] Next, with reference to Figures 15 to 17, modified shapes of groove 153A and anchor 151A will be described.

[0072] Figure 15, like Figure 10, shows a portion of the cross-sectional view of the rotor 102.

[0073] In this example, the groove 153A of the yoke 153 and the anchor 151A of the case 151 are positioned in approximately the same locations as in the example in Figure 10.

[0074] On the other hand, the shapes of the groove 153A of the yoke 153 and the anchor 151A of the case 151 are asymmetrical in the axial direction.

[0075] Thus, the shapes of the groove 153A and the anchor 151A do not necessarily have to be symmetrical in the axial direction.

[0076] Figures 16 and 17, like Figure 11, show unfolded views of the outer surface of the yoke 153.

[0077] The groove 153A does not necessarily have to be continuous in the circumferential direction on the outer surface of the yoke 153. That is, the groove 153A may enclose only a portion of the outer surface of the yoke 153 in the circumferential direction.

[0078] For example, in the example shown in Figure 16, the groove 153A is interrupted at one point in the circumferential direction, resulting in a discontinuous, arc-shaped groove in the circumferential direction.

[0079] Although not shown in the diagram, the anchor 151A of the yoke 153 also forms a discontinuous arc-shaped projection in the circumferential direction, in line with the groove 153A.

[0080] Furthermore, there may be two or more places where the groove 153A and anchor 151A are interrupted.

[0081] Furthermore, the groove 153A does not have to be shaped parallel to the circumferential direction of the yoke 153 (for example, ring-shaped or arc-shaped).

[0082] For example, as shown in Figure 17, the groove 153A may be inclined with respect to the circumferential direction of the yoke 153 (with respect to the reference plane P1).

[0083] Although not shown in the diagram, the anchor 151A of the yoke 153 is also inclined with respect to the circumferential direction of the yoke 153 (with respect to the reference plane P1) to match the groove 153A.

[0084] For example, the groove 153A and the anchor 151A may be wavy (for example, a sine wave or a triangular wave).

[0085] Alternatively, for example, an anchor may be formed in the case 151 by forming a hole that penetrates the yoke 153 instead of the groove 153A and filling the hole with resin.

[0086] Furthermore, considering the magnetic properties of the motor 13, it is desirable that the groove 153A and the anchor 151A have a shape that is symmetrical with respect to the reference plane P1 as a whole.

[0087] Alternatively, for example, an anchor may be provided along the end of the yoke 153.

[0088] Figure 18 is a cross-sectional view of the rotor 102.

[0089] In this example, a plurality of arc-shaped notches 153B are formed at predetermined intervals at the lower end of the yoke 153.

[0090] Then, when the case 151 is integrally molded with the yoke 153, the resin of the case 151 is filled into the notch 153B. As a result, an arc-shaped and protruding anchor 151B is formed at the lower end of the cylindrical portion of the case 151, along the lower end of the yoke 153, in accordance with the notch 153B. The anchor 151B protrudes from the inner circumferential surface of the cylindrical portion of the case 151 toward the outer circumferential surface of the yoke 153, is inserted into the notch 153B, and overlaps with the yoke 153 (or its notch 153B) in the axial direction.

[0091] As a result, even if an axial force is applied between the case 151 and the yoke 153, the lower end of the yoke 153 will catch on the anchor 151B, preventing the yoke 153 from detaching from the case 151.

[0092] For example, the shape of the anchor 151B may be a continuous ring-shaped projection along the lower end of the yoke 153.

[0093] Alternatively, for example, an anchor may be provided on the outer surface of the yoke 153.

[0094] Figure 19, like Figure 10, shows a portion of the cross-sectional view of the rotor 102.

[0095] In this example, a projection-shaped anchor 153C, which is symmetrical in the axial direction, is formed so as to surround the outer surface of the yoke 153 360° in the circumferential direction, with the reference plane P1 as the center.

[0096] Then, when the case 151 is integrally molded with the yoke 153, the resin of the case 151 is filled around the anchor 153C. As a result, a ring-shaped groove 151C with an axially symmetrical shape is formed on the inner circumferential surface of the cylindrical portion of the case 151 to match the anchor 153C. The anchor 153C protrudes from the outer circumferential surface of the yoke 153 toward the inner circumferential surface of the cylindrical portion of the case 151, is inserted into the groove 151C, and becomes aligned with the case 151 (and its groove 151C) in the groove axis direction.

[0097] As a result, even if an axial force is applied between the case 151 and the yoke 153, the anchor 153C will catch in the groove 151C, preventing the yoke 153 from coming off the case 151.

[0098] Furthermore, the anchors 153C and grooves 151C may be provided in two or more locations in the axial direction, similar to the anchors 151A and grooves 153A described above, or they may be arranged asymmetrically in the axial direction. Also, the anchors 153C and grooves 151C do not necessarily have to be continuous in the circumferential direction, nor do they have to be symmetrical in the axial direction, similar to the anchors 151A and grooves 153A described above.

[0099] However, considering the magnetic properties of the motor 13, it is desirable that the anchor 153C and groove 151C have a shape that is symmetrical with respect to the reference plane P1 as a whole.

[0100] For example, two or more of the anchors 151A of case 151, 151B of case 151, and 153C of yoke 153 may be combined.

[0101] <Method to prevent misalignment of case 151 relative to shaft 152> Since the motor 13 directly drives the propeller, the case 151 receives thrust from the propeller, which may cause it to shift relative to the shaft 152 in both the rotational and axial directions.

[0102] In contrast, by fixing the case 151 to the shaft 152 using a mechanism such as a screw, it is possible to prevent the case 151 from shifting relative to the shaft 152.

[0103] However, this mechanism to prevent misalignment leads to an increase in the size and weight of the motor 13. In addition, fastening with screws may cause variations in the weight of the rotor and misalignment of the center of gravity of the shaft 152 and the rotor 102.

[0104] In contrast, an example of a method for preventing misalignment of the case 151 relative to the shaft 152 will be described with reference to Figures 20 and 21.

[0105] Figure 20 is a cross-sectional view of the area near the joint between the case 151 and the shaft 152.

[0106] In this example, a pair of D-cut grooves 152A are formed on the side surface of the shaft 152, symmetrically with respect to the central axis of the shaft 152.

[0107] Then, when the case 151 is integrally molded with the shaft 152, the resin of the case 151 fills the groove 152A. As a result, a protruding anchor 151D is formed at the joint between the case 151 and the shaft 152, aligned with the groove 152A. The anchor 151D protrudes from the case 151 toward the shaft 152 and is inserted into the groove 152A.

[0108] As a result, the anchor 151D catches in the groove 152A, fixing the position of the case 151 relative to the shaft 152 and preventing rotational and axial displacement of the case 151 relative to the shaft 152.

[0109] Furthermore, the mechanism for preventing the case 151 from shifting relative to the shaft 152 can be omitted, resulting in a smaller motor 13 and a reduction in weight.

[0110] Next, a modified example of the groove 152A of the shaft 152 will be described with reference to Figure 21.

[0111] Figures 21A to C are enlarged views of the area near the joint between the shaft 152 and the case 151.

[0112] For example, as shown in Figure 21A, the groove 152A may be provided in only one location.

[0113] For example, as shown in Figure 21B, grooves 152A may be provided in three or more locations at the same position (same height) in the axial direction.

[0114] For example, as shown in Figure 21C, the grooves 152A may be provided at different positions (different heights) in the axial direction.

[0115] Furthermore, groove 152A does not necessarily have to be a D-cut groove.

[0116] <Effect of exposing the surface of the magnet 154> Next, with reference to Figure 22, the effect of exposing the surface of the magnet 154 (the surface facing the core 133) without covering it with the case 151 (resin) will be explained.

[0117] Figure 22A is a partial cross-sectional view of the motor 13 when the surface of the magnet 154 is not covered by the case 151. Figure 22B is a partial cross-sectional view of the motor 13 when the surface of the magnet 154 is covered by the case 151.

[0118] In the case of A in Figure 22, a gap G12 of a predetermined distance must be provided between the outer surface of the core 133 and the surface of the magnet 154 so that the stator 101 and the rotor 102 do not interfere with each other.

[0119] In this case, the air gap G11, which is the gap between the magnetic circuit components of the stator 101 and rotor 102 (between the core 133 and the magnet 154), becomes equal to the gap G12.

[0120] On the other hand, in the case of B in Figure 22, a gap G22 of a predetermined distance is required between the outer circumferential surface of the core 133 and the inner circumferential surface of the case 151 so that the stator 101 and the rotor 102 do not interfere with each other.

[0121] In this case, the air gap G21, which is the gap between the magnetic circuit components of the stator 101 and rotor 102 (between the core 133 and the magnet 154), is wider than the air gap G11 in Figure 22A. That is, the air gap G21 is wider than the air gap G11 by the thickness of the resin on the surface of the magnet 154.

[0122] When the air gap widens, the resistance of the magnetic circuit of the motor 13 increases, and its performance deteriorates. Conversely, when the air gap narrows, the resistance of the magnetic circuit of the motor 13 decreases, and its performance improves.

[0123] Therefore, by exposing the surface of the magnet 154 without covering it with the case 151 (resin), the air gap G11 is narrowed, and the performance of the motor 13 is improved.

[0124] As described above, by making the case 151 out of resin and integrally molding it with the shaft 152 and yoke 153, the quality of the motor 13 is improved. Furthermore, the motor 13 is made lighter and smaller. In addition, the quality of the motor 13 is further improved by providing anchors between the case 151 and the yoke 153, and between the case 151 and the shaft 152. Furthermore, the quality of the motor 13 is further improved by exposing the surface of the magnet 154 of the rotor 102.

[0125] Furthermore, the quality of the drone 1 using the motor 13 will improve as the quality of the motor 13 is enhanced.

[0126] <<2. Modified Examples>> Below, we will describe modified examples of the embodiments of the present technology described above.

[0127] For example, the yoke 153 may be provided with parts other than the cylindrical portion, such as a ring-shaped top surface or bottom surface.

[0128] For example, the case 151 does not necessarily have to cover the entire outer surface of the cylindrical portion of the yoke 153. That is, a portion of the outer surface of the cylindrical portion of the yoke 153 may be exposed from the case 151.

[0129] <Examples of application of this technology> This technology is not limited to the embodiments described above, but can be applied to outrodler-type rotating electrical machines in general, and to equipment that uses outrodler-type rotating electrical machines in general.

[0130] For example, this technology can be applied to mobile devices that use outrodial-type rotating electromechanisms, such as robots other than drones, and vehicles.

[0131] <<3. Others>> The embodiments of this technology are not limited to those described above, and various modifications are possible without departing from the gist of this technology.

[0132] <Examples of configuration combinations> This technology can also be configured as follows:

[0133] (1) A rotating electric machine comprising a stator and a rotor that rotates around the stator, wherein the rotor comprises a rotating shaft, a yoke having a cylindrical portion surrounding the rotating shaft, a resin case integrally molded with the rotating shaft and the yoke and covering the outer circumferential surface of the cylindrical portion, and a first anchor projecting from one of the outer circumferential surface of the cylindrical portion and the inner circumferential surface of the case covering the outer circumferential surface of the cylindrical portion in the direction of the other. (2) The rotating electric machine according to (1), wherein the first anchor overlaps in the axial direction with the yoke and the case on the side where the first anchor is not formed. (3) The rotating electric machine according to (2), wherein the yoke has a groove surrounding at least a portion of the outer circumferential surface of the cylindrical portion, and the first anchor projecting from the inner circumferential surface of the case in accordance with the groove. (4) The rotating electric machine according to (2), wherein the first anchor projecting from the inner circumferential surface of the case along the end of the cylindrical portion. (5) The rotating electric machine according to (2), wherein the first anchor protrudes from the outer circumferential surface of the cylindrical portion and surrounds at least a portion of the outer circumferential surface of the cylindrical portion. (6) The rotating electric machine according to any one of (1) to (5), wherein the shape of the first anchor passes through the axial center of the cylindrical portion and is symmetrical with respect to a plane perpendicular to the axial direction. (7) The rotating electric machine according to any one of (1) to (6), wherein the rotating shaft has a groove in the portion of its side surface that contacts the case, and the case has a second anchor that protrudes in accordance with the groove. (8) The rotating electric machine according to (7), wherein the groove is a D-cut groove. (9) The rotating electric machine according to (7) or (8), wherein the rotating shaft has a pair of grooves arranged symmetrically with respect to the center of the rotating shaft. (10) The rotating electric machine according to any one of (1) to (9), wherein the rotor further comprises a plurality of magnets arranged at circumferential intervals on the inner circumferential surface of the yoke. (11) The rotating electric machine according to (10), wherein the surface of the magnet facing the core of the stator is exposed and not covered by the case.(12) A mobile body comprising a stator and a rotor that rotates around the stator, wherein the rotor comprises a rotating shaft, a yoke having a cylindrical portion surrounding the rotating shaft, a resin case integrally molded with the rotating shaft and the yoke and covering the outer surface of the cylindrical portion, and an anchor projecting from one of the outer surface of the cylindrical portion and the inner surface of the case covering the outer surface of the cylindrical portion in the direction of the other. (13) The mobile body according to (12), wherein the mobile body is a drone, and the rotating electric machine rotates the propeller of the drone.

[0134] Furthermore, the effects described herein are merely illustrative and not limiting; other effects may also occur.

[0135] 1. Drone, 13, 13FL-13RR motor, 101 stator, 102 rotor, 131 base, 132 bearing, 133 core, 134 coil, 151 case, 151A groove, 151B anchor, 151C notch, 151D anchor, 152 shaft, 152A groove, 153 yoke, 153A anchor, 153B groove, 153C anchor, 154 magnet

Claims

1. A rotating electric machine comprising a stator and a rotor that rotates around the stator, wherein the rotor comprises a rotating shaft, a yoke having a cylindrical portion surrounding the rotating shaft, a resin case integrally molded with the rotating shaft and the yoke and covering the outer surface of the cylindrical portion, and a first anchor projecting from one of the outer surface of the cylindrical portion and the inner surface of the case covering the outer surface of the cylindrical portion toward the other.

2. The rotating electric machine according to claim 1, wherein the first anchor overlaps in the axial direction with the yoke and the case on which the first anchor is not formed.

3. The rotating electric machine according to claim 2, wherein the yoke has a groove that surrounds at least a portion of the outer surface of the cylindrical portion in the circumferential direction, and the first anchor protrudes from the inner surface of the case in accordance with the groove.

4. The rotating electric machine according to claim 2, wherein the first anchor protrudes from the inner circumferential surface of the case along the end of the cylindrical portion.

5. The rotating electric machine according to claim 2, wherein the first anchor protrudes from the outer circumferential surface of the cylindrical portion and surrounds at least a portion of the outer circumferential surface of the cylindrical portion.

6. The rotating electric machine according to claim 1, wherein the shape of the first anchor passes through the axial center of the cylindrical portion and is symmetrical with respect to a plane perpendicular to the axial direction.

7. The rotating electric machine according to claim 1, wherein the rotating shaft has a groove in the portion of its side surface that contacts the case, and the case has a second anchor that protrudes in accordance with the groove.

8. The rotating electric machine according to claim 7, wherein the groove is a D-cut groove.

9. The rotating electric machine according to claim 7, wherein the rotating shaft comprises a pair of grooves positioned symmetrically with respect to the center of the rotating shaft.

10. The rotary electric machine according to claim 1, further comprising a plurality of magnets arranged at circumferential intervals on the inner circumferential surface of the yoke.

11. The rotating electric machine according to claim 10, wherein the surface of the magnet facing the core of the stator is exposed and not covered by the case.

12. A mobile body comprising a rotating electric machine, the rotor comprising a stator and a rotor that rotates around the stator, wherein the rotor comprises a rotating shaft, a yoke having a cylindrical portion surrounding the rotating shaft, a resin case integrally molded with the rotating shaft and the yoke and covering the outer circumferential surface of the cylindrical portion, and an anchor projecting from one of the outer circumferential surface of the cylindrical portion and the inner circumferential surface of the case covering the outer circumferential surface of the cylindrical portion in the direction of the other.

13. The mobile body according to claim 12, wherein the mobile body is a drone, and the rotating electric machine rotates the propeller of the drone.

Images