rotor and electric motor

Abstract

To provide a rotor and a motor that can operate more stably.SOLUTION: A rotor includes a shaft having a cylindrical shaft body extending in an axial direction and a plurality of spokes extending radially from the shaft body and provided in a circumferential direction, and a magnet structure provided to cover the outer peripheral side of the shaft, and the magnet structure includes a permanent magnet, and a covering material that is made of a material stronger than the permanent magnet and covers the entire outer surface of the permanent magnet.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present disclosure relates to a rotor and an electric motor. [Background technology]

[0002] One example of an electric motor is known, as described in Patent Document 1 below. This motor includes a rotor and a stator that covers the rotor from its outer periphery and has a coil. The rotor includes a shaft extending along its axis, a magnet housing provided on the outer periphery of the shaft, permanent magnets fitted into the magnet housing, and a retaining sleeve that covers the permanent magnets from the outside. The retaining sleeve is provided to prevent the permanent magnets from being damaged or scattered by centrifugal force generated when the rotor rotates. The retaining sleeve applies a preload to the permanent magnets from their outer periphery. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2015-119628 Summary of the Invention [Problem to be solved by the invention]

[0004] However, if preload is applied to the permanent magnet as described above, and if the strength of the preload is too great, the permanent magnet may crack or chip, resulting in the motor being unable to operate stably.

[0005] The present disclosure has been made to solve the above-mentioned problems, and has an object to provide a rotor and an electric motor that can be operated more stably. [Means for solving the problem]

[0006] In order to solve the above problems, the rotor according to the present disclosure includes a shaft having a shaft body extending in an axial direction, a shaft extending radially from the shaft body and having a plurality of spokes provided in a circumferential direction, and a rotor that covers an outer peripheral side of the shaft. attached a magnet structure, the magnet structure including a permanent magnet and a coating material made of a material stronger than the permanent magnet and covering the entire outer surface of the permanent magnet. The system further includes a first wheel that connects the radially outer ends of the spokes circumferentially and has a cylindrical shape centered on the axis, and the magnetic structure is formed in the shape of a flexible wire and wound around the outer peripheral surface of the first wheel. [Effects of the Invention]

[0007] According to the present disclosure, it is possible to provide a rotor and an electric motor that can be operated more stably. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a cross-sectional view showing a configuration of an electric motor according to a first embodiment of the present disclosure. [Figure 2] FIG. 2 is a side view showing the configuration of a rotor according to the first embodiment of the present disclosure. [Figure 3] 1 is a perspective view showing the configuration of a magnetic structure according to a first embodiment of the present disclosure. FIG. [Figure 4] FIG. 2 is an enlarged cross-sectional view showing the magnetization direction of the magnetic structure according to the first embodiment of the present disclosure. [Figure 5] FIG. 4 is a cross-sectional view showing the configuration of a rotor according to a second embodiment of the present disclosure. [Figure 6] FIG. 10 is a cross-sectional view showing the configuration of a rotor according to a third embodiment of the present disclosure. [Figure 7] FIG. 10 is an enlarged cross-sectional view of a main portion of a rotor according to a third embodiment of the present disclosure. [Figure 8] FIG. 10 is a cross-sectional view showing a first modified example of a rotor according to each embodiment of the present disclosure. [Figure 9] FIG. 10 is a cross-sectional view showing a second modified example of a rotor according to each embodiment of the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0009] First Embodiment (Motor configuration) An electric motor 100 according to a first embodiment of the present disclosure will be described below with reference to FIGS. 1 to 3. As shown in FIG. 1, the electric motor 100 includes a rotor 1 and a stator 2. The rotor 1 extends along an axis O and is rotatable about the axis O. The stator 2 covers the rotor 1 from the outer periphery and has a cylindrical shape centered on the axis O. The stator 2 has coils (not shown). As will be described in more detail below, when current is applied to these coils, an electromagnetic force is generated between the coils and the permanent magnets of the rotor 1, causing the rotor 1 to rotate about the axis O.

[0010] (Rotor configuration) Next, a description will be given of the configuration of the rotor 1. The rotor 1 has a shaft 10 and a magnetic structure 11.

[0011] The shaft 10 has a shaft body 10a, a plurality of spokes 10b, and a wheel 10c (first wheel). The shaft body 10a has a cylindrical shape extending in the direction of the axis O. The spokes 10b extend radially outward from the outer circumferential surface of the shaft body 10a. The plurality of spokes 10b are arranged at intervals in the circumferential direction. The plurality of spokes 10b are also arranged at intervals in the direction of the axis O.

[0012] The radially inner end of each spoke 10b extends from the outer peripheral surface of the shaft body 10a in a direction tangential to the circular cross section of the shaft body 10a. Although Fig. 1 shows a configuration having eight spokes 10b as an example, the number of spokes 10b is not limited to this and may be six or less or nine or more.

[0013] The radially outer ends of the spokes 10b are connected to a wheel 10c. The wheel 10c has a cylindrical shape centered on the axis O. The spokes 10b are connected to the inner circumferential surface of the wheel 10c. As shown in FIG. 2, a plurality of the wheels 10c are arranged at intervals in the direction of the axis O.

[0014] The magnetic structure 11 is attached to cover the outer peripheral surface of the wheel 10c. As shown in FIG. 3, the magnetic structure 11 includes a permanent magnet 11a and a covering material 11b. The covering material 11b is made of a non-magnetic material that is stronger than the permanent magnet 11a. The covering material 11b covers the entire outer surface of the permanent magnet 11a, which has been formed into a desired shape. In the example of FIG. 3, the magnetic structure 11 is formed in a wire shape as an example. Furthermore, this magnetic structure 11 can be freely bent while covered with the covering material 11b (it has flexibility). A specific example of such a magnetic structure 11 is described in WOUS2017025212W.

[0015] As shown in Fig. 2, in this embodiment, the wire-shaped magnetic structure 11 is wound spirally around the outer circumferential surface of the wheel 10c. The magnetic structure 11 is preferably fixed to the wheel 10c by welding. As described above, the wheels 10c are arranged at intervals in the axial direction O, so that a tool can be inserted through the intervals to perform welding work as needed. Note that, in order to ensure the strength of the wheel 10c, a plurality of slits extending partially in the circumferential direction may be formed in one cylindrical wheel 10c that is continuous in the axial direction O.

[0016] Here, the magnetization direction of the magnetic structure 11 will be described with reference to FIG. 4. As shown in the figure, the magnetic structure 11 is configured so that the magnetization direction changes in the circumferential direction when wound around the wheel 10c. In other words, portions where the N pole side is located radially outward are formed periodically in the circumferential direction. In FIG. 4, the direction indicated by the arrow indicates the N pole side as an example. It is known that a magnetic structure 11 magnetized in this manner generates a particularly large electromagnetic force in the portion where the N pole is located. Therefore, in this embodiment, the spokes 10b are arranged in the portions where these N poles face radially outward.

[0017] (Action and effect) Next, the operation of the electric motor 100 will be described. To operate the electric motor 100, a current is supplied to the coil of the stator 2. This generates an electromagnetic force between the coil and the permanent magnet 11a of the rotor 1, causing the rotor 1 to rotate around the axis O. The rotational energy of the rotor 1 is extracted from the axial end of the shaft 10 and is put to various uses.

[0018] In recent years, electric motors have been increasing in rotation speed. As a result, a large centrifugal force is applied to the rotating magnetic structure 11 in addition to the electromagnetic force. To resist this centrifugal force, it is conceivable to adopt a method of attaching a cylindrical sleeve or the like to the outer periphery of the permanent magnet and applying a preload to the permanent magnet from the outer periphery.

[0019] However, if preload is applied to the permanent magnet from the outer periphery as described above, the permanent magnet may not be able to withstand the preload and may crack or chip. Therefore, the present embodiment employs the above-described configuration.

[0020] According to the above configuration, the magnetic structure 11 is formed by covering the entire outer surface of the permanent magnet 11a with the covering material 11b. Therefore, without providing any other components on the outer periphery of the magnetic structure 11, it is possible to prevent the permanent magnet 11a from scattering due to centrifugal force or electromagnetic force. In addition, since there is no need to apply preload to the permanent magnet 11a from the outer periphery, cracking or chipping of the permanent magnet 11a due to the application of preload can also be suppressed. Furthermore, since the magnetic structure 11 is supported by multiple spokes 10b, it is possible to reduce the weight of the rotor 1 compared to when the shaft 10 is formed from a solid member. In addition, the spokes 10b support the wheel 10c and the magnetic structure 11 by pulling the wheel 10c radially inward. This allows for more stable resistance to centrifugal force and electromagnetic force.

[0021] Furthermore, with the above configuration, the magnetic structure 11 is formed in the shape of a flexible wire, and can be wound around the outer circumferential surface of the wheel 10c. This allows for easier and cheaper manufacturing of the rotor. In particular, since the magnetic structure 11 is available with the covering material 11b already attached, the manufacturing process and costs can be reduced.

[0022] According to the above configuration, the spokes 10b extend tangentially from the outer peripheral surface of the shaft body 10a, which increases the rigidity against torque about the axis O when the rotor 1 rotates, compared to when the spokes 10b extend radially, for example. This allows the electric motor 100 to operate more stably.

[0023] The first embodiment of the present disclosure has been described above. It should be noted that various changes and modifications can be made to the above configuration without departing from the spirit and scope of the present disclosure. For example, in the first embodiment, an example was described in which the shaft 10 has a wheel 10c and the wire-shaped magnetic structure 11 is wound around the outer circumferential surface of the wheel 10c. However, it is also possible to adopt a configuration in which the wheel 10c is not provided and the inner circumferential surface of the magnetic structure 11, which is pre-formed into a cylindrical shape, is directly supported by the spokes 10b. It is also possible to provide the wheel 10c and fix the cylindrical magnetic structure 11 to the wheel 10c by interference fit. Furthermore, it is also possible to adopt a configuration in which multiple magnetic structures 11 extending in the axial direction O are arranged without gaps in the circumferential direction.

[0024] Second Embodiment Next, a rotor 1b according to a second embodiment of the present disclosure will be described with reference to Fig. 5. Note that the same components as those in the first embodiment are denoted by the same reference numerals, and detailed description thereof will be omitted. As shown in Fig. 5, the rotor 1b according to this embodiment further includes a second wheel 10d and a connecting portion 10e in addition to the wheel 10c (first wheel 10c) described above.

[0025] The first wheel 10c has a cylindrical shape extending in the direction of the axis O. The inner peripheral surface of the first wheel 10c is supported by spokes 10b arranged at intervals in the direction of the axis O. The second wheel 10d covers the first wheel 10c from the outer periphery and has a cylindrical shape centered on the axis O. A space extending in the radial direction and the direction of the axis O is formed between the first wheel 10c and the second wheel 10d. A magnetic structure 11 is housed in this space. In the example of FIG. 5, a magnetic structure 11 that is integrally molded into a cylindrical shape is used. It is also possible to use an annular magnetic structure 11 divided into multiple pieces in the direction of the axis O.

[0026] The first wheel 10c and the second wheel 10d are connected in the radial direction by a connecting portion 10e on one side in the direction of the axis O. In other words, the connecting portion 10e has an annular shape when viewed in the direction of the axis O. The ends of the first wheel 10c and the second wheel 10d on the other side in the direction of the axis O are open in an annular shape. This opening is formed for inserting the above-mentioned magnetic structure 11. As a result, the first wheel 10c, the second wheel 10d, and the connecting portion 10e form a C-shape in a cross section including the axis O.

[0027] According to the above configuration, the magnetic structure 11 is covered from the outer periphery by the second wheel 10d, so that the magnetic structure 11 can more stably resist centrifugal force and electromagnetic force acting thereon. Furthermore, as described above, the first wheel 10c, the second wheel 10d, and the connecting portion 10e are C-shaped in a cross section including the axis O, so that the magnetic structure 11 can be easily inserted through an opening on the other side in the direction of the axis O. Furthermore, because the magnetic structure 11 is sandwiched between the first wheel 10c and the second wheel 10d from both radial sides, the magnetic structure 11 can be stably held to the first wheel 10c or the second wheel 10d without welding or the like. This allows for reductions in manufacturing man-hours and costs.

[0028] The second embodiment of the present disclosure has been described above. Note that various changes and modifications can be made to the above configuration without departing from the gist of the present disclosure.

[0029] Third Embodiment Next, a third embodiment of the present disclosure will be described with reference to FIGS. 6 and 7. Note that the same components as those in the above embodiments are denoted by the same reference numerals, and detailed description thereof will be omitted. As shown in FIG. 6, in a rotor 1c according to this embodiment, a plurality of circumferentially extending storage grooves 10f are formed at intervals in the axial direction O on the outer peripheral surface of a wheel 10c (first wheel 10c). The magnetic structures 11 are housed in these storage grooves 10f. It is desirable that the storage grooves 10f are formed at the same positions as the spokes 10b in the axial direction O. On the other hand, it is also possible to adopt a configuration in which the storage grooves 10f are spirally shaped so that their positions in the axial direction O change continuously. In this case, the positions of the storage grooves 10f and the spokes 10b do not necessarily have to coincide.

[0030] As shown in FIG. 7, the storage groove 10f is recessed radially inward from the outer peripheral surface of the wheel 10c and has a trapezoidal shape in a cross section including the axis O. More specifically, the storage groove 10f is formed so that the dimension in the direction of the axis O gradually decreases from the radially inner side to the radially outer side in a cross section including the axis O. The magnetic structure 11 has a trapezoidal cross section corresponding to this storage groove 10f. In other words, the magnetic structure 11 is engaged with the side surfaces of the storage groove 10f (a pair of surfaces facing the axis O) within the storage groove 10f. Note that the angle θ formed between the side surfaces of the storage groove 10f and the radial direction is preferably within a range of 5° to 20°.

[0031] According to the above configuration, the magnetic structure 11 is accommodated in the accommodation groove 10f while being engaged with the magnetic structure 11, which further reduces the possibility that the magnetic structure 11 will fly off due to centrifugal force or electromagnetic force, thereby enabling the electric motor 100 to be operated more stably.

[0032] The third embodiment of the present disclosure has been described above. It should be noted that various changes and modifications can be made to the above configuration without departing from the spirit and scope of the present disclosure. For example, in the third embodiment, an example has been described in which the magnetic structure 11 has a trapezoidal cross-sectional shape. However, as another example, a magnetic structure 11 having a triangular cross-sectional shape can also be used.

[0033] Furthermore, as a modified example common to all of the above-described embodiments, the configuration shown in FIG. 8 can also be employed. In the example shown in FIG. 8, the spokes 10g extend radially rather than tangentially to the outer peripheral surface of the shaft body 10a. While this configuration is less durable against torque, it is possible to more strongly resist radial loads. Also, as shown in FIG. 9, a rotor 1d can be employed in which multiple ring-shaped magnetic structures 11 divided in the axial direction O are stacked and fitted into a wheel 10c in the axial direction O.

[0034] <Additional Notes> The rotor 1 and the electric motor 100 described in each embodiment can be understood, for example, as follows.

[0035] (1) The rotor 1 according to the first aspect comprises a shaft 10 having a shaft body 10a extending in the direction of an axis O and spokes 10b extending radially from the shaft body 10a and arranged in a circumferential direction, and a magnetic structure 11 arranged to cover the outer periphery of the shaft 10, wherein the magnetic structure 11 has a permanent magnet 11a and a covering material 11b made of a material stronger than the permanent magnet 11a and covering the entire outer surface of the permanent magnet 11a.

[0036] According to the above configuration, the magnetic structure 11 is formed by covering the entire outer surface of the permanent magnet 11a with the covering material 11b. Therefore, it is possible to prevent the permanent magnet 11a from scattering without providing any other member on the outer periphery of the magnetic structure 11. Furthermore, since it is not necessary to apply preload to the permanent magnet 11a from the outer periphery, it is also possible to prevent cracking or chipping of the permanent magnet 11a due to the application of preload.

[0037] (2) The rotor 1 according to the second aspect further includes a first wheel 10c that connects the radially outer ends of the spokes 10b in the circumferential direction and has a cylindrical shape centered on the axis O, and the magnetic structure 11 is formed in the shape of a flexible wire and wound around the outer peripheral surface of the first wheel 10c.

[0038] According to the above configuration, the magnetic structure 11 is formed in the shape of a flexible wire, and therefore can be wound around the outer circumferential surface of the first wheel 10c, which makes it possible to manufacture the rotor 1 more simply and inexpensively.

[0039] (3) In the rotor 1 according to the third aspect, the shaft 10 further has a second wheel 10d that covers the first wheel 10c from the outer periphery and an annular connecting portion 10e that radially connects the first wheel 10c and the second wheel 10d, and the magnetic structure 11 is provided between the first wheel 10c and the second wheel 10d.

[0040] According to the above configuration, the magnetic structure 11 is covered from the outer periphery side by the second wheel 10d, and therefore the magnetic structure 11 can resist centrifugal force and electromagnetic force acting on the magnetic structure 11 more stably.

[0041] (4) In the rotor 1 according to the fourth aspect, an accommodating groove 10f is formed on the outer peripheral surface of the first wheel 10c, the accommodating groove 10f having a cross-sectional shape that is recessed radially inward and extends circumferentially, and whose dimension in the direction of the axis O gradually decreases as it moves from the radially inner side to the radially outer side when viewed circumferentially. The magnetic structure 11 has a cross-sectional shape corresponding to the accommodating groove 10f and is accommodated in a state engaged with the accommodating groove 10f.

[0042] According to the above configuration, the magnetic structure 11 is accommodated in an engaged state in the accommodation groove 10f, which further reduces the possibility that the magnetic structure 11 will fly off due to centrifugal force or electromagnetic force.

[0043] (5) In the rotor according to the fifth aspect, the spokes 10b extend tangentially from the outer circumferential surface of the shaft body 10a.

[0044] According to the above configuration, the spokes 10b extend tangentially from the outer peripheral surface of the shaft body 10a, thereby increasing the rigidity against torque when the rotor 1 rotates compared to, for example, when the spokes 10b extend radially.

[0045] (6) An electric motor 100 according to a sixth aspect includes the rotor 1 according to any one of the above aspects, and a stator 2 that covers the rotor 1 from the outer periphery side and has a plurality of coils.

[0046] According to the above configuration, it is possible to provide the electric motor 100 that can be operated more stably. [Explanation of symbols]

[0047] 100 Electric motor 1, 1b, 1c, 1d rotors 2 stator 10 shaft 10a shaft body 10b spokes 10c First Wheel (Wheel) 10d second wheel 10e connection 10f Storage Groove 10g spokes 11 Magnet structure 11a permanent magnet 11b Covering material O axis

Claims

1. a shaft having a shaft body extending in an axial direction and a plurality of spokes extending radially from the shaft body and provided in a circumferential direction; a magnetic structure attached to cover an outer circumferential side of the shaft; Equipped with The magnetic structure includes: A permanent magnet and a coating material that covers the entire outer surface of the permanent magnet; and The vehicle further includes a first wheel that connects radially outer ends of the spokes in a circumferential direction and has a cylindrical shape centered on the axis line, The magnetic structure is a rotor formed in the shape of a flexible wire and wound around the outer circumferential surface of the first wheel.

2. 2. The rotor according to claim 1, wherein the shaft further has a second wheel that covers the first wheel from the outer periphery and an annular connecting portion that radially connects the first wheel and the second wheel, and the magnetic structure is provided between the first wheel and the second wheel.

3. An outer peripheral surface of the first wheel is formed with an accommodation groove having a cross-sectional shape that is recessed radially inward and extends circumferentially, and whose dimension in the axial direction gradually decreases from the radially inner side toward the radially outer side as viewed in the circumferential direction, 3. The rotor according to claim 1, wherein the magnetic structure has a cross-sectional shape corresponding to the accommodation groove and is accommodated in the accommodation groove in a state of being engaged with the accommodation groove.

4. The rotor according to claim 1 , wherein the spokes extend tangentially from the outer circumferential surface of the shaft body.

5. A rotor according to any one of claims 1 to 4; a stator that covers the rotor from the outer periphery side and has a plurality of coils; An electric motor comprising:

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