Dynamo-electric motor and manufacturing method of the dynamo-electric motor

Abstract

To provide a dynamo-electric motor that can be easily manufactured and has a high performance, and provide a manufacturing method of a dynamo-electric motor.SOLUTION: In a pole piece in which a magnetized direction is directed to a radial direction to a shaft line from a plurality of magnets, an acute included angles an angle formed by a pair of straight lines extended toward an inner peripheral side along an end surface of both sides of a circumferential direction of the pole piece in view of an axial direction is set so as to be larger than an angle formed by the pair of straight lines extended over an end surface of both sides of the circumferential direction from the shaft line. A radial direction position of a virtual circle of which a dimension of the circumferential direction of the pole piece is equal to a magnetic width as a value obtained by dividing the circumferential length with the number of the magnets to be arranged to the circumferential direction is positioned in an inner side of the radial direction from a center part in the radial direction of the magnet.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present disclosure relates to an electric motor and a method for manufacturing the electric motor.

Background Art

[0002] As a type of electric motor, a type called an outer rotor type is known. This type of electric motor mainly includes a stator disposed on the inner peripheral side and an outer rotor that covers the stator from the outer peripheral side. A coil is built into the stator, and magnets are built into the inner peripheral side of the rotor body of the outer rotor. The outer rotor is rotatably supported around the axis of the stator. When current is supplied to the coil, an electromagnetic force is generated between the coil and the magnets, and the outer rotor is rotationally driven around the axis.

[0003] Here, as an arrangement of the magnets used in the outer rotor, an arrangement called a Halbach array has been put into practical use. In this arrangement, when viewed from the axial direction, the magnetization directions of a plurality of magnets arranged in the circumferential direction change gradually so as to rotate from the magnets on one side in the circumferential direction to the magnets on the other side (see, for example, Patent Document 1 below). In this arrangement, a magnet whose magnetization direction faces the radial direction with respect to the axis is called a pole piece, and a magnet disposed between a pair of adjacent pole pieces may be called a transition piece. In order to arrange these fan-shaped magnets (pole pieces and transition pieces) having a certain radial width in an annular shape with a sufficiently narrow gap between the magnets on the inner peripheral surface of the rotor body, due to its geometric constraints, it is necessary to manufacture the outer rotor by inserting part or all of the magnets in the axial direction.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, since the already magnetized magnets are affected by the magnetic force of other surrounding magnets, as described above, there is room for improvement in the array method involving the process of inserting some or all of the magnets in the axial direction.

[0006] The present disclosure has been made to solve the above problems, and an object thereof is to provide an electric motor that can be manufactured more easily and has high performance, and a method for manufacturing the electric motor.

Means for Solving the Problems

[0007] In order to solve the above problems, an electric motor according to the present disclosure includes a stator having a circular cross section centered on an axis and having a built-in coil, and an outer rotor having a cylindrical shape centered on the axis and covering the stator from the outer peripheral side. The outer rotor has a rotor body and a plurality of magnets arranged in a Halbach array in the circumferential direction on the inner peripheral side of the rotor body. Among the plurality of magnets, in a pole piece whose magnetization direction faces the radial direction with respect to the axis, as viewed from the axial direction, the angle formed by a pair of straight lines extending inward in the circumferential direction along the end faces on both circumferential sides of the pole piece is set to be larger than the angle formed by a pair of straight lines extending from the axis to the outer peripheral ends of the end faces on both circumferential sides. The radial position of a virtual circle whose diameter is equal to the circumferential dimension of the pole piece divided by the number of magnets arranged in the circumferential direction (magnet width) is located radially inward of the central portion in the radial direction of the magnet.

[0008] The motor according to the present disclosure has a circular cross-section centered on an axis, and includes a stator having a built-in coil, and an outer rotor that has a cylindrical shape centered on the axis and covers the stator from the outer peripheral side. The outer rotor includes a rotor body, and a plurality of magnets arranged in a Halbach array in the circumferential direction on the inner peripheral side of the rotor body. The plurality of magnets include pole pieces whose magnetization directions face the radial direction with respect to the axis, and transition pieces arranged between a pair of adjacent pole pieces in the circumferential direction. The outer peripheral surface of the pole piece and the inner peripheral surface of the rotor body are joined by a first adhesive layer. The outer peripheral surface of the pole piece and the inner peripheral surface of the rotor body are joined by a first adhesive layer, and a second adhesive layer is provided on the circumferentially facing end surfaces of the transition pieces or between the transition piece and the pole piece, and joins the transition pieces or the transition piece and the pole piece in the circumferential direction. The second adhesive for forming the second adhesive layer has a greater elongation rate than the first adhesive for forming the first adhesive layer.

[0009] The manufacturing method of the motor according to the present disclosure is the manufacturing method of the above motor, and includes a step of preparing the rotor body, a step of attaching the pole pieces at intervals in the circumferential direction on the inner peripheral surface of the rotor body, a step of forming a transition piece assembly by joining the transition pieces in the circumferential direction, and a step of fitting the transition piece assembly into the space between the pole pieces on the inner peripheral surface of the rotor body from the inner peripheral side.

Effect of the Invention

[0010] According to the present disclosure, it is possible to provide a motor that can be manufactured more easily and has high performance, and a method for manufacturing the motor.

Brief Description of the Drawings

[0011]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Embodiments for Carrying Out the Invention

[0012] (Configuration of the electric motor) Hereinafter, an electric motor 1 according to an embodiment of the present disclosure and a method for manufacturing the electric motor 1 will be described with reference to FIGS. 1 to 7.

[0013] As shown in FIG. 1, the electric motor 1 includes a stator 10, an outer rotor 20, and a casing (not shown). The stator 10 has a stator body 11 and a plurality of coils 12. The stator body 11 has a cylindrical or tubular shape centered on the axis X. A plurality of coils 12 are arranged on the outer peripheral side of the stator body 11. The coils 12, as an example, extend in the radial direction with respect to the axis X and are arranged in a plurality of circumferential directions at equal intervals.

[0014] (Configuration of the outer rotor) The outer rotor 20 is supported so as to be relatively rotatable about the axis X with respect to the stator 10 which is a stationary body. The outer rotor 20 has a rotor body 21 and a plurality of magnets 22. The rotor body 21 has a cylindrical shape centered on the axis X and covers the stator 10 with a gap from the outer peripheral side. A plurality of magnets 22 are arranged on the inner peripheral surface of the rotor body 21. These magnets 22 form a rectangle when viewed from the axis X direction and are arranged in the circumferential direction.

[0015] When a current is supplied to the coil 12 of the stator 10, an electromagnetic force is generated between the coil 12 and the magnet 22. Due to this electromagnetic force, the outer rotor 20 is rotationally driven about the axis X.

[0016] (Magnet arrangement) As shown in FIG. 2, the plurality of magnets 22 are arranged according to an array method called a so-called Halbach array. In the magnets 22 arranged by the Halbach array, when viewed from the direction of the axis X, the magnetization direction of the magnets 22 changes clockwise or counterclockwise as it goes from the magnets 22 on one side in the circumferential direction to the magnets 22 on the other side. In the example of FIG. 2, a mode in which the magnetization direction changes by 45° each time is shown. The tip of the arrow in the figure indicates the S pole side, and the base end indicates the N pole side. By adopting the Halbach array, it is possible to improve the torque of the motor 1 having the outer rotor 20.

[0017] Among the plurality of magnets 22, the magnet 22 whose magnetization direction faces the radial direction with respect to the axis X is called a pole piece 31. In the example of FIG. 2, since the magnetization direction changes by 45° each time, three other magnets 22 are arranged between the pole piece 31 and the pole piece 31. These three magnets 22 are each called a transition piece 32. The magnetization direction of the magnet 22 constituting the transition piece 32 is not the radial direction, but the circumferential direction or a direction inclined by 45° with respect to the radial direction. Note that a set of three transition pieces 32 may be hereinafter referred to as a transition piece assembly 40.

[0018] The pole piece 31 and the transition piece 32 are both joined to each other by an adhesive and are also fixed to the inner peripheral surface of the rotor body 21 by the same adhesive. A first adhesive layer 51 is interposed between the outer peripheral surface of the pole piece 31 and the inner peripheral surface of the rotor body 21. The first adhesive layer 51 is a layer formed by curing the first adhesive. On the other hand, a second adhesive layer 52 is interposed between the magnets 22, that is, between the transition pieces 32 or between the transition piece 32 and the pole piece 31. The second adhesive layer 52 is a layer formed by curing the second adhesive. The second adhesive has the characteristics that its elongation rate is larger and its elastic modulus is lower than those of the first adhesive. As the second adhesive realizing such characteristics, a silicone-based elastic adhesive is suitable. This type of adhesive exhibits an elongation rate of, for example, 100% or more. As the first adhesive, an acrylic-based adhesive is preferably used. In this type of adhesive, the elongation rate is generally as small as about several percent, while the strength and elastic modulus are known to be higher than those of the second adhesive.

[0019] (Shape of the magnet) Next, with reference to FIG. 3, the detailed shape of each magnet 22 will be described. As shown in the figure, the pole piece 31 and the transition piece 32 have different shapes when viewed in the axial direction of the axis X. Here, the angle formed by a pair of straight lines extending toward the inner peripheral side along the end faces on both circumferential sides of the pole piece 31 is defined as the "scissors angle θ1". Also, the angle formed by a pair of straight lines extending from the axis X to the outer peripheral side ends of the end faces on both circumferential sides of the pole piece 31 is called the "axial angle θ2". At this time, the scissors angle θ1 is set to be larger than the axial angle θ2. Therefore, between the pole pieces 31 adjacent to each other, the circumferential end faces are parallel to each other or spread apart from each other toward the inner peripheral side. Also, the scissors angle θ1 is equal to the value of 360° / number of poles.

[0020] In addition, a pair of corner portions on the outer peripheral side of the pole piece 31 are each chamfered to form a notch portion 60 (see FIG. 2). As the notch portion 60, in addition to the curved chamfer shown in FIG. 2, so-called C-chamfer can be adopted. By forming this notch portion 60, a triangular gap is formed between the pole piece 31 and the inner peripheral surface of the rotor body 21. This gap is filled with the adhesive layer described above. On the other hand, notch portions 60 are not formed at a pair of corner portions on the inner peripheral side.

[0021] Of the three transition pieces 32 that make up the transition piece assembly 40, a pair of transition pieces 32 arranged on both sides in the circumferential direction have a different shape from the remaining one transition piece 32. These transition pieces 32 located on both sides in the circumferential direction are referred to as "end pieces 41". Of the two circumferential surfaces of the end piece 41, the surface facing the pole piece 31 is parallel to the circumferential end surface of the pole piece 31 when viewed from the axial direction X. Here, the "parallel" mentioned here refers to substantial parallelism, and a slight error is allowed. The piece (central piece 42) located at the center in the circumferential direction, excluding the end piece 41, has a rectangular shape. In addition, notch portions 60 are also formed at a pair of corner portions on the outer peripheral side of these transition pieces 32 (see FIG. 2). On the other hand, notch portions 60 are not formed at a pair of corner portions on the inner peripheral side, or notches smaller than the notch portions 60 on the outer peripheral side are formed. It is desirable that the notch portion 60 is arc-shaped.

[0022] Here, a value obtained by dividing the total value of the circumferential dimensions of the plurality of magnets 22 by the number of magnets 22 is defined as the "magnet width W". A virtual circle when this magnet width W is equal among the plurality of magnets 22 is defined as the "virtual circle A". As shown in FIG. 3, the radial position through which the virtual circle A passes is located radially inside the central portion of the magnet 22 in the radial direction.

[0023] (Method for manufacturing an electric motor) Next, a method for manufacturing the above-described electric motor 1, particularly a method for manufacturing the outer rotor 20, will be described with reference to FIGS. 4 to 6. As shown in FIG. 4, this manufacturing method includes a step S1 of preparing a rotor body 21, a step S2 of arranging pole pieces 31, a step S3 of constructing a transition piece assembly 40, and a step S4 of attaching the pole piece 31 assembly to the rotor body 21.

[0024] In step S1, the pre-fabricated rotor body 21 is placed on, for example, a workbench or the like. In this state, it is desirable that marks, guides, or the like for positioning the pole pieces 31 are formed on the inner peripheral surface of the rotor body 21. Such marks may include, for example, ridges protruding toward the inner peripheral side. Subsequently, in step S2, the pole pieces 31 are arranged on the inner peripheral surface of the rotor body 21 (see FIG. 5). The pole pieces 31 are arranged at intervals in the circumferential direction according to the above marks and guides. Next, in step S3, the transition piece assembly 40 is assembled. Specifically, the transition piece assembly 40 is constructed by joining the pair of end pieces 41 and one central piece 42 described above. In step S4, this transition piece assembly 40 is fitted into the space between a pair of pole pieces 31 (see FIG. 6). Thus, the outer rotor 20 is completed. Thereafter, the outer rotor 20 and the stator 10 are housed in a casing, and other accessories are attached to complete the electric motor 1.

[0025] (Function and Effect) Here, conventionally, when manufacturing the outer rotor 20 in which magnets 22 (pole pieces 31 and transition pieces 32) having a fan shape and a constant radial thickness are arranged circumferentially with a sufficiently narrow gap interval, a process of inserting part or all of the magnets 22 into the rotor body in the rotor axis direction is required. However, since the already magnetized magnets 22 are affected by the magnetic force of other surrounding magnets 22, when arranging a plurality of magnets 22 by inserting them in the rotor axis direction as described above, it is difficult to uniformly maintain the thickness of the adhesive interposed in the gap between the magnet and the rotor body or between the magnets and to maintain the adhesive fixing strength. That is, there was room for improvement in the conventional method. To solve this problem, in the present embodiment, the above-described respective configurations and manufacturing methods are adopted.

[0026] According to the above configuration, the scissor angle, which is the angle formed by a pair of straight lines extending toward the inner peripheral side along the end faces on both circumferential sides of the pole piece 31, is set larger than the angle formed by a pair of straight lines extending from the axis X to the end faces on both circumferential sides of the pole piece 31. As a result, the circumferential end faces of the adjacent pair of pole pieces 31 extend parallel to each other toward the inner peripheral side or extend so as to be separated from each other toward the inner peripheral side. Therefore, when arranging other magnets 22 between the pole pieces 31, the possibility that these other magnets 22 and the pole pieces 31 physically interfere with each other can be reduced. Thus, it is possible to first arrange only the pole pieces 31 and then easily arrange other magnets 22 afterwards. Thereby, the outer rotor 20 can be manufactured more easily and in a shorter period of time.

[0027] In addition, since the nip angle of the pole piece 31 is relatively large, if the pole piece 31 is about to fall off from the rotor body 21 due to the magnetic field formed by the Halbach array magnets, the other magnets 22 arranged between these pole pieces 31 will sandwich the pole piece 31 from both circumferential sides toward the outer circumferential side. Therefore, it is possible to avoid the event of the pole piece 31 falling off. As a result, the motor 1 can continue to be operated more stably. Or, by setting the rotational speed of the rotor higher, it is possible to increase the output of the motor 1, that is, to reduce the weight of the motor 1 at the same output.

[0028] Furthermore, the radial position of the virtual circle whose circumferential length of the pole piece 31 is equal to the length obtained by dividing the circumferential length by the number of magnets arranged in the circumferential direction is located radially inside the central portion of the magnet 22 in the radial direction. As a result, an effect of optimizing the circumferential distribution of the magnetic flux density on the inner circumferential side of the rotor magnet formed by the Halbach array magnets with different shapes occurs, so that it is possible to suppress torque fluctuations (torque ripple) when the outer rotor 20 is rotationally driven (see the solid line graph in FIG. 7: the broken line graph shows the conventional torque fluctuations). Therefore, it is possible to provide a motor 1 that can stably generate a high torque regardless of the rotational speed.

[0029] According to the above configuration, the end faces on both circumferential sides of the transition piece 32 are parallel to the circumferential end faces of the pole piece 31 when viewed from the direction of the axis X, and the pole piece 31 and the transition piece 32 are made as close as possible. On the other hand, if there are gaps or voids between the magnets 22, the magnetic force will decrease accordingly, which may affect the performance of the motor 1. According to the above configuration, such a possibility can be reduced, and it is possible to provide a motor 1 with higher performance.

[0030] Here, since the magnetization direction of the pole piece 31 is in the radial direction, a radial load is mainly applied during the operation of the motor 1. Therefore, it is desirable that the first adhesive layer 51 that bonds the pole piece 31 to the outer rotor 20 has a considerable adhesive strength. On the other hand, when the outer rotor 20 rotates, the rotor body 21 is slightly deformed so as to expand in both circumferential directions due to the centrifugal force. For this reason, the magnet 22 is affected by the circumferential tensile force accompanying the deformation of the rotor body 21 more than by the magnetic force.

[0031] However, according to the above configuration, the first adhesive for forming the first adhesive layer 51 that bonds the pole piece 31 and the rotor body 21 has a high elastic modulus, a small elongation rate, and a high adhesive strength. Therefore, even when a radial load is applied to the pole piece 31, it does not lift off from the rotor body 21 and does not peel off. Further, the second adhesive layer 52 that bonds the magnets 22 to each other in the circumferential direction has a larger elongation rate and a smaller elastic modulus than the first adhesive. Therefore, it can extend and follow as an adhesive intervening in this gap to the expansion of the circumferential gap between the magnets 22 caused by the expansion of the rotor body 21 in the circumferential direction. Thus, regardless of startup, operation, or stop, the possibility of causing a deviation in the arrangement structure of the magnets 22 of the outer rotor 20 or causing a defect in the adhesive layer fixing the magnets 22 is reduced, and the motor 1 can be operated more stably over a long period. Furthermore, by setting the rotational speed of the rotor higher, it becomes possible to increase the output of the motor 1, that is, to reduce the weight of the motor 1 at the same output.

[0032] According to the above configuration, notch portions 60 larger than the remaining two corner portions facing the inner peripheral side are formed at two corner portions facing the outer peripheral side of the magnet 22. Thereby, when the magnet 22 is arranged on the rotor main body 21, it is possible to reduce the possibility that the magnet 22 to be arranged interferes with the other magnets 22 that have already been arranged. Further, at the time of assembly, since the surplus adhesive flows into the notch portion 60, the thickness of the adhesive layer intervening between the circumferential end faces of the magnet 22 and between the magnet 22 and the rotor main body 21 can be adjusted to the intended thickness. Therefore, the adhesion quality of the magnet 22 is improved, and it becomes possible to further increase the adhesive fixing strength of the magnet. As a result, it becomes possible to continuously operate the electric motor 1 stably at a higher rotational speed and torque.

[0033] Here, conventionally, a method has been adopted in which while sliding a part or all of the magnets 22 on the inner peripheral surface of the rotor main body 21, the adhesive intervening in the gap is spread. However, in this method, the magnet 22 and the inner peripheral surface of the rotor main body 21 are rubbed against each other, and in particular, it is impossible to maintain the adhesive thickness in the gap between the magnet 22 and the rotor main body 21 uniformly, and there is a risk of insufficient adhesive strength.

[0034] However, according to the above method, a step of first attaching the pole piece 31 to the rotor main body 21 and then fitting the transition piece assembly 40 between the pole pieces 31 is executed. For this reason, the Halbach array can be completed only by inserting the transition piece assembly 40 from the radially inner side between the pole pieces 31 that have been previously positioned. For this reason, the possibility that the magnet 22 and the inner peripheral surface of the rotor main body 21 are rubbed against each other is reduced. Therefore, it becomes possible to minimize the risk of insufficient adhesive strength of the magnet 22.

[0035] (Other Embodiments) As described above, the embodiments of the present disclosure have been described in detail with reference to the drawings, but the specific configuration is not limited to this embodiment, and design changes and the like within the scope not departing from the gist of the present disclosure are also included.

[0036] In addition, the number of magnets 22, the number of coils 12, and the rate of change of the magnetization direction (i.e., the number of poles) described in the above embodiments are merely examples and can be appropriately changed according to the design and specifications. In any case, the same operational effects as those described above can be obtained.

[0037] Also, the materials of the first adhesive and the second adhesive are merely examples, and any adhesive material with a significant difference in elongation rate can be adopted.

[0038] <Appendix> The motor 1 described in each embodiment and the method for manufacturing the motor 1 are understood as follows, for example.

[0039] (1) The motor 1 according to the first aspect has a circular cross-section centered on the axis X, a stator 10 with a built-in coil 12, and an outer rotor 20 that forms a cylindrical shape centered on the axis X and covers the stator 10 from the outer peripheral side. The outer rotor 20 has a rotor body 21 and a plurality of magnets 22 arranged in a Halbach array in the circumferential direction on the inner peripheral side of the rotor body 21. Among the plurality of magnets 22, in the pole piece 31 whose magnetization direction faces the radial direction with respect to the axis X, the scissor angle, which is the angle formed by a pair of straight lines extending inward along the end faces on both circumferential sides of the pole piece 31 when viewed from the direction of the axis X, is set to be larger than the angle formed by a pair of straight lines extending from the axis X to the outer peripheral ends of the end faces on both circumferential sides. The radial position of the virtual circle whose circumferential length of the pole piece 31 is equal to the length obtained by dividing the circumferential length by the number of magnets arranged in the circumferential direction is located radially inside the central portion of the magnet 22 in the radial direction.

[0040] According to the above configuration, the scissors angle, which is the angle formed by a pair of straight lines extending inward along the end faces on both circumferential sides of the pole piece 31, is set to be larger than the angle formed by a pair of straight lines extending from the axis X to the end faces on both circumferential sides of the pole piece 31. Therefore, when arranging other magnets 22 between the pole pieces 31, the possibility of physical interference between these other magnets 22 and the pole piece 31 can be reduced.

[0041] (2) The electric motor 1 according to the second aspect is the electric motor 1 in (1), wherein the plurality of magnets 22 further have a transition piece 32 arranged between a pair of the pole pieces 31 adjacent to each other in the circumferential direction, and the circumferential end face of the pole piece 31 adjacent to the transition piece 32 and the circumferential end face of the transition piece 32 are parallel when viewed in the direction of the axis X.

[0042] According to the above configuration, the circumferential end face of the transition piece 32 is parallel to the circumferential end face of the pole piece 31 when viewed in the direction of the axis X, and the pole piece 31 and the transition piece 32 are brought as close as possible.

[0043] (3) The electric motor 1 according to the third aspect is the electric motor 1 in (2), further comprising a first adhesive layer 51 that bonds the outer peripheral surface of the pole piece 31 and the inner peripheral surface of the rotor body 21, and a second adhesive layer 52 that is provided on the end faces facing the circumferential direction of the transition pieces 32 or the transition piece and the pole piece and bonds the magnets 22 to each other or the transition piece and the pole piece in the circumferential direction. The second adhesive forming the second adhesive layer 52 has a larger elongation rate than the first adhesive forming the first adhesive layer 51.

[0044] According to the above configuration, the first adhesive that forms the first adhesive layer 51 bonding the pole piece 31 and the rotor body 21 has a smaller elongation rate, a higher elastic modulus, and a higher adhesive strength than the second adhesive that forms the second adhesive layer 52 bonding the transition pieces 32 to each other and bonding the transition piece 32 and the pole piece 31 in the circumferential direction. Therefore, even when a radial load is applied to the pole piece 31, it does not lift off from the rotor body 21 and does not peel off. Further, the second adhesive layer 52 that bonds the magnets 22 to each other in the circumferential direction has a larger elongation rate and a smaller elastic modulus than the first adhesive. Therefore, it can extend and follow as an adhesive intervening in the gap as the circumferential gap between the magnets 22 generated in response to the circumferential expansion of the rotor body 21 expands.

[0045] (4) The motor 1 according to the fourth aspect is the motor 1 according to any one of the aspects (1) to (3), and at two corner portions facing the outer peripheral side of the magnet 22, notch portions 60 larger than the remaining two corner portions facing the inner peripheral side are formed.

[0046] According to the above configuration, notch portions 60 larger than the remaining two corner portions facing the inner peripheral side are formed at two corner portions facing the outer peripheral side of the magnet 22. Thereby, when the magnet 22 is arranged on the rotor body 21, the possibility that the magnet 22 to be arranged interferes with other already arranged magnets 22 can be reduced.

[0047] (5) The motor 1 according to the fifth aspect has a circular cross-section centered on the axis X, and includes a stator 10 having a built-in coil 12, and an outer rotor 20 having a cylindrical shape centered on the axis X and covering the stator 10 from the outer peripheral side. The outer rotor 20 has a rotor body 21 and a plurality of magnets 22 arranged in a Halbach array in the circumferential direction on the inner peripheral side of the rotor body 21. The plurality of magnets 22 have a pole piece 31 whose magnetization direction faces the radial direction with respect to the axis X, and a transition piece 32 arranged between a pair of adjacent pole pieces 31 in the circumferential direction. The outer peripheral surface of the pole piece 31 and the inner peripheral surface of the rotor body 21 are connected by a first adhesive layer 51, and the transition pieces 32 are provided on the end surfaces facing the circumferential direction of the transition pieces 32 or the pole pieces 31. A second adhesive layer 52 that circumferentially connects the transition pieces 32 or the transition piece 32 and the pole piece 31 is further provided. The second adhesive forming the second adhesive layer 52 has a greater elongation rate than the first adhesive forming the first adhesive layer 51.

[0048] According to the above configuration, the first adhesive forming the first adhesive layer 51 that connects the pole piece 31 and the rotor body 21 has a smaller elongation rate, a higher elastic modulus, and a higher adhesive strength than the second adhesive forming the second adhesive layer 52 that circumferentially connects the magnets 22. Therefore, even when a radial load is applied to the pole piece 31, it does not lift off from the rotor body 21 and does not peel off. Further, the second adhesive layer 52 that circumferentially connects the magnets 22 has a greater elongation rate and a smaller elastic modulus than the first adhesive. Therefore, it can extend and follow as an adhesive intervening in the circumferential gap between the magnets 22 that occurs in response to the circumferential expansion of the rotor body 21.

[0049] (6) The motor 1 according to the sixth aspect is the motor 1 according to (1), and the scissors angle is a value of 360° / number of poles.

[0050] According to the above configuration, when arranging other magnets 22 between the pole pieces 31, the possibility that these other magnets 22 and the pole pieces 31 physically interfere with each other can be further reduced.

[0051] (6) The motor 1 according to the sixth aspect is the manufacturing method of the motor 1 described in (2), including the steps of preparing the rotor body 21, attaching the pole pieces 31 at intervals in the circumferential direction on the inner circumferential surface of the rotor body 21, forming a transition piece assembly 40 by coupling the transition pieces 32 to each other in the circumferential direction, and fitting the transition piece assembly 40 into the space between the pole pieces 31 on the inner circumferential surface of the rotor body 21 from the inner circumferential side.

[0052] According to the above method, the steps of first attaching the pole pieces 31 to the rotor body 21 and then fitting the transition piece assembly 40 between the pole pieces 31 are executed. Therefore, the Halbach array can be completed only by inserting the transition piece assembly 40 from the radially inner side between the pole pieces 31 that have been previously positioned.

Explanation of Reference Numerals

[0053] 1... motor 10... stator 11... stator body 12... coil 20... outer rotor 21... rotor body 22... magnet 31... pole piece 32... transition piece 40... transition piece assembly 41... end piece 42... central piece 51... first adhesive layer 52... second adhesive layer 60... notch X... axis

Claims

1. A stator having a circular cross-section centered on an axis and incorporating a coil, An outer rotor having a cylindrical shape centered on the axis and covering the stator from the outer peripheral side, A motor comprising: The outer rotor, A rotor body, A plurality of magnets Halbach-arrayed in the circumferential direction on the inner peripheral side of the rotor body, And having, Among the plurality of magnets, in the pole pieces whose magnetization directions face the radial direction with respect to the axis, when viewed from the axial direction, the angle formed by a pair of straight lines extending inward in the circumferential direction along the end faces on both circumferential sides of the pole piece is the scissor angle, which is set larger than the angle formed by a pair of straight lines extending from the axis to the outer peripheral ends of the end faces on both circumferential sides, A motor in which the radial position of a virtual circle whose circumferential dimension of the pole piece is equal to the magnet width, which is a value obtained by dividing the circumferential length by the number of magnets arranged in the circumferential direction, is located radially inside the central portion in the radial direction of the magnet.

2. The plurality of magnets further have a transition piece arranged between a pair of adjacent pole pieces in the circumferential direction, and the circumferential end faces of the transition piece and the adjacent pole pieces and the circumferential end face of the transition piece are parallel when viewed from the axial direction X. The motor according to claim 1.

3. A first adhesive layer that bonds the outer peripheral surface of the pole piece and the inner peripheral surface of the rotor body, A second adhesive layer provided on the end faces facing the circumferential direction of the transition pieces or between the transition piece and the pole piece, which circumferentially bonds the transition pieces or the transition piece and the pole piece, And further comprising, The motor according to claim 2, wherein the second adhesive for forming the second adhesive layer has a larger elongation rate than the first adhesive for forming the first adhesive layer.

4. The motor according to any one of claims 1 to 3, wherein larger cutout portions are formed at two corner portions facing the outer peripheral side of the magnet than at the remaining two corner portions facing the inner peripheral side.

5. A stator having a circular cross-section centered on an axis and incorporating a coil, An outer rotor having a cylindrical shape centered on the axis and covering the stator from the outer peripheral side, A motor comprising: The outer rotor, A rotor body, And having a plurality of magnets Halbach-arrayed in the circumferential direction on the inner peripheral side of the rotor body, The plurality of magnets includes a pole piece whose magnetization direction faces the radial direction with respect to the axis, and a transition piece arranged between a pair of adjacent pole pieces in the circumferential direction. A first adhesive layer that bonds the outer peripheral surface of the pole piece and the inner peripheral surface of the rotor body. A second adhesive layer that is provided on the end faces of the transition pieces facing the circumferential direction or on the end faces of the transition piece and the pole piece facing the circumferential direction, and that bonds the transition pieces to each other or the transition piece and the pole piece in the circumferential direction. The motor further includes: The second adhesive that forms the second adhesive layer has a greater elongation rate than the first adhesive that forms the first adhesive layer. **Claim 6** The motor according to claim 1, wherein the scissor angle is a value of 360° / number of poles. **Claim 7** A method for manufacturing the motor according to claim 2, comprising: Preparing the rotor body; Attaching the pole pieces at intervals in the circumferential direction on the inner peripheral surface of the rotor body; Forming a transition piece assembly by bonding the transition pieces to each other in the circumferential direction; Inserting the transition piece assembly from the inner peripheral side between the pole pieces on the inner peripheral surface of the rotor body; A method for manufacturing a motor including the above steps.

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