JP2013102604A - Motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a motor enabling increase in a motor torque, reduction in torque fluctuation, and smooth rotation.SOLUTION: A motor includes: a rotor which has a rotor yoke and a plurality of magnets installed on the outer periphery or the inner periphery of the rotor yoke and aligned toward the circumferential direction of the rotor yoke; and a stator which has a stator core annularly arranged leaving a gap relative to the rotor yoke and an exciting coil exciting the stator core. The center of a circular arc of an outer peripheral portion of the magnet corresponds to the center of a circular arc of an inner peripheral portion of the magnet, and the center of the circular arc of the outer peripheral portion of the magnet or the inner peripheral portion of the magnet does not correspond to the rotating center of the rotor.

Description

  The present invention relates to a motor.

  Patent Document 1 describes a technique for reducing the cogging torque and torque ripple of a permanent magnet motor by setting the eccentricity of the center of the arc radius of the outer peripheral surface of the permanent magnet within an optimal range.

JP 2001-275285 A

  However, in the motor described in Patent Document 1, since the arc of the magnet outer peripheral surface is different from the arc of the magnet inner peripheral surface, the total volume of the magnet is reduced. For this reason, the magnet of patent document 1 exists in the tendency for the total magnetic flux of a magnet to reduce, and when it is set as a motor, there exists a possibility that motor torque may fall. Further, since the arc radius center of the magnet outer peripheral surface is different from the arc radius center of the magnet inner peripheral surface, the magnet has a thin portion in the radial thickness, and this thin portion may be weak against the demagnetizing field. . For this reason, there is a possibility that the electric load of the stator cannot be increased and the motor torque cannot be increased so that the magnet is not demagnetized.

  The present invention has been made in view of the above, and it is an object of the present invention to provide a motor capable of increasing motor torque and reducing torque fluctuation and capable of smooth rotation.

  In order to solve the above-described problems and achieve the object, a motor includes a rotor yoke and a rotor including a plurality of magnets arranged on an outer periphery or an inner periphery of the rotor yoke and arranged in a circumferential direction of the rotor yoke; A stator core that is annularly arranged with a gap between the rotor yoke and a stator that includes an exciting coil that excites the stator core, and the center of the arc of the outer periphery of the magnet and the inner periphery of the magnet The center of the arc coincides, and the center of the arc of the outer peripheral part of the magnet or the inner peripheral part of the magnet does not coincide with the rotation center of the rotor.

  With this configuration, the thickness between the inner peripheral portion and the outer peripheral portion of the magnet becomes constant, and a reduction in the total magnetic flux amount due to a decrease in magnet volume can be suppressed. In addition, the motor can increase the demagnetization resistance of the magnet. For this reason, the electric load of the exciting coil of the stator can be increased, and the motor can increase the motor torque.

  In addition, with the above configuration, the center of the arc on the outer periphery of the magnet or the center of the arc on the inner periphery of the magnet does not coincide with the rotation center of the rotor. can do. For this reason, the motor can reduce torque fluctuation and can rotate smoothly. The motor can suppress the cogging torque and torque ripple that accompany the sudden increase or decrease in the magnetic flux linked from the magnet to the stator core.

  As a desirable mode of the present invention, it is preferable that the rotor yoke has a close contact surface that forms an arc having the same radius as the radius of the arc of the outer peripheral portion of the magnet or the radius of the arc of the inner peripheral portion of the magnet.

  With this configuration, the outer peripheral portion or inner peripheral portion of the magnet is in close contact with the rotor yoke, and the risk of magnetic flux leakage due to a gap can be reduced. As a result, the motor can suppress a decrease in motor torque by effectively using the magnetic flux of the magnet. In addition, since the magnet and the rotor yoke are aligned, the motor can stabilize the fixing of the magnet.

  As a desirable mode of the present invention, it is preferable that the shortest distance from the corner portion of the magnet protruding to the stator side to the rotor yoke is equal to or greater than the distance of the gap.

  With this configuration, the magnetic resistance of the magnetic flux interlinking from the corner of the magnet to the stator core can be made equal to or less than the magnetic resistance of the magnetic flux interlinking from the corner of the magnet to the rotor yoke. Thereby, the motor can suppress a decrease in motor torque.

  As a desirable mode of the present invention, it is preferable that a rotating shaft that rotates in conjunction with the rotor is further provided, and the rotating shaft is directly connected to a load body that rotates.

  With this configuration, the motor becomes a so-called direct drive motor and can directly rotate the load body. Further, the motor can reduce torque fluctuation and can rotate smoothly. And since a motor can reduce a cogging torque and a torque ripple while raising a motor torque, it can suppress the lifetime deterioration of the bearing which supports a rotary body.

  ADVANTAGE OF THE INVENTION According to this invention, while raising a motor torque, a torque fluctuation can be reduced and the motor which can be rotated smoothly can be provided.

FIG. 1 is a cross-sectional view schematically showing the configuration of the motor of Embodiment 1 on a virtual plane including a rotation center. FIG. 2 is a partial cross-sectional view schematically showing the rotor by cutting the configuration of the motor of Embodiment 1 along a virtual plane orthogonal to the rotation center. FIG. 3 is an explanatory diagram schematically illustrating the relationship between the rotor and the stator according to the first embodiment. FIG. 4 is a partial cross-sectional view schematically showing the rotor by cutting the configuration of the motor according to the second embodiment along a virtual plane orthogonal to the rotation center. FIG. 5 is an explanatory diagram schematically illustrating the relationship between the rotor and the stator according to the second embodiment.

  DESCRIPTION OF EMBODIMENTS Embodiments (embodiments) for carrying out the present invention will be described in detail with reference to the drawings. The present invention is not limited by the contents described in the following embodiments. The constituent elements described below include those that can be easily assumed by those skilled in the art and those that are substantially the same. Furthermore, the constituent elements described below can be appropriately combined.

(Embodiment 1)
FIG. 1 is a cross-sectional view schematically showing the configuration of the motor of Embodiment 1 on a virtual plane including a rotation center. The motor 1 can transmit the rotational force directly to the load body 52 without interposing a transmission mechanism such as a gear, a belt, or a roller, and can rotate the load body 52. The motor 1 is a direct drive motor in which a so-called motor rotating shaft 10 and a load body 52 are directly connected.

  The motor 1 includes a stator (hereinafter referred to as a stator) 30 that is maintained in a stationary state, a rotor (hereinafter referred to as a rotor) 40 that is rotatably arranged with respect to the stator 30, and a stator 30 that is fixedly supported. The base member 20 attached to the member 51, the motor rotating shaft 10 fixed to the rotor 40 and rotatable together with the rotor 40, and the motor rotating shaft 10 interposed between the base member 20 and the motor rotating shaft 10 20 and a bearing 14 rotatably supported with respect to 20.

  The base member 20, the motor rotating shaft 10, the rotor 40, and the stator 30 are all annular structures. The motor rotating shaft 10, the rotor 40, and the stator 30 are arranged concentrically around the rotation center Zr. Further, the motor 1 is disposed in order of the rotor 40 and the stator 30 from the rotation center Zr to the outside. Such a motor 1 is called an inner rotor type, and the rotor 40 is closer to the rotation center Zr than the stator 30. In the motor 1, the motor rotating shaft 10, the rotor 40, and the stator 30 are disposed on the base member 20.

  The base member 20 includes a substantially disk-shaped housing base 21 and a housing inner 22 that is a shaft center projecting from the housing base 21 so as to surround the hollow portion 11 through the hollow portion 11. The housing inner 22 is fastened and fixed to the housing base 21 via a fixing member 27 such as a bolt. The base member 20 includes a housing flange 23 that fixes the inner ring of the bearing 14 to the housing base 21 via a fixing member 26 such as a bolt.

  A stator 30 is fastened to the outer peripheral edge of the housing base 21 by a fixing member 28 such as a bolt. Thereby, the stator 30 is positioned and fixed with respect to the housing base 21. The center axis of the stator 30 coincides with the rotation center Zr of the rotor 40.

  The stator 30 includes a cylindrical stator core 31 and an excitation coil 32. In the stator 30, an exciting coil 32 is wound around a stator core 31. The stator 30 is connected to wiring (not shown) for supplying power from the power source, and power is supplied to the exciting coil 32 through this wiring.

  The rotor 40 has a cylindrical shape in which the outer diameter of the rotor 40 is smaller than the inner diameter of the stator 30. The rotor 40 includes a rotor yoke 41 and a magnet 42 attached to the outer periphery of the rotor yoke 41. The magnet 42 will be described later.

  The motor rotating shaft 10 includes an annular rotating shaft 12 and a rotor flange 13 that fixes an outer ring of the bearing 14 to the rotating shaft 12 via a fixing member 16 such as a bolt. The rotor 40 is integrally fixed to the rotating shaft 12 of the cylindrical motor rotating shaft 10. The rotor 40 may be fixed to the rotating shaft 12 of the cylindrical motor rotating shaft 10 by a fixing member. The rotation shaft 12 is formed such that the center axis of the ring is coaxial with the rotation center Zr of the motor 1.

  The bearing 14 has an outer ring fixed to the rotor flange 13 and an inner ring fixed to the housing flange 23. Thereby, the bearing 14 can rotatably support the rotating shaft 12 and the rotor 40 with respect to the housing base 21. For this reason, the motor 1 can rotate the rotating shaft 12 and the rotor 40 with respect to the housing base 21 and the stator 30.

  In addition, the bearing 14 is good also as a cross roller bearing which used the rolling element as the cross roller. The bearing 14 is not limited to a cross roller bearing, and may be, for example, a ball bearing or a roller bearing in which rolling elements are balls or rollers (cylindrical rollers, tapered rollers, spherical rollers, etc.). These rolling elements may be arranged at predetermined intervals, for example, at regular intervals, one by one in a pocket of the annular cage, and may be incorporated between the raceway surfaces while being rotatably held in the pocket. As a result, the rolling elements can roll between the raceway surfaces in a state where a predetermined interval is maintained without the rolling surfaces contacting each other. Moreover, each rolling element can prevent an increase in rotational resistance or seizure due to friction caused by contact with each other.

  For example, when the rolling element is a ball, the bearing 14 can be a corrugated type or a crown type. Alternatively, when the rolling element is made of various types of rollers, the bearing 14 can have a cage shape, a comb shape, a cage shape, or the like.

  The motor 1 preferably includes rotation detectors 24A and 24B. The rotation detectors 24A and 24B are resolvers, for example, and can detect the rotational positions of the rotor 40 and the motor rotating shaft 10 with high accuracy.

  The rotation detectors 24A and 24B are the resolver stators 25A and 25B maintained in a stationary state, the resolver stators 25A and 25B are arranged to face the resolver stators 25A and 25B with a predetermined gap therebetween, and are rotatable with respect to the resolver stators 25A and 25B. 15A and 15B are provided above the bearing 14.

  The resolver stators 25A and 25B have an annular laminated core in which a plurality of stator magnetic poles are formed at equal intervals in the circumferential direction, and a resolver coil is wound around each stator magnetic pole. In the motor 1 of the present embodiment, the resolver stators 25 </ b> A and 25 </ b> B are fixed to the housing inner 22.

  The resolver rotors 15 </ b> A and 15 </ b> B are constituted by a hollow annular laminated iron core, and are fixed inside the motor rotation shaft 10. Arrangement positions of the rotation detectors 24A and 24B are not particularly limited as long as the rotation of the rotor 40 (the motor rotation shaft 10) can be detected, and are arbitrary according to the shapes of the motor rotation shaft 10 and the base member 20. It can arrange | position to this position.

  When the rotor 40 rotates, the motor rotating shaft 10 rotates together with the rotor 40, and the resolver rotors 15A and 15B also rotate in conjunction with the rotation. Thereby, the reluctance between resolver rotor 15A, 15B and resolver stator 25A, 25B changes continuously. Resolver stators 25A and 25B detect changes in reluctance and convert them into electrical signals (digital signals) by a resolver control circuit. The control device that controls the motor 1 can calculate the positions and rotation angles of the motor rotation shaft 10 and the rotor 40 that are linked to the resolver rotors 15A and 15B per unit time based on the electrical signal of the resolver control circuit. . As a result, the control device that controls the motor 1 can measure the rotation state (for example, the rotation speed, the rotation direction, or the rotation angle) of the motor rotation shaft 10.

  The resolver rotor 15 </ b> A described above has an annular shape having an inner periphery that is eccentric with respect to the hollow portion 11. Therefore, when the resolver rotor 15A rotates with the rotation of the rotor 40, the distance between the resolver stator 25A and the resolver stator 25A is continuously changed in the circumferential direction, and the reluctance between the two is continuously changed depending on the position of the resolver rotor 15A. To change. For each rotation of the resolver rotor 15A, a monopolar resolver signal is output in which the fundamental wave component of the reluctance change is one cycle, and the rotation detector 24A is a so-called monopolar resolver.

  The resolver rotor 15B has a plurality of salient pole-like teeth formed at equal intervals in the circumferential direction. Therefore, when the resolver rotor 15B rotates with the rotation of the rotor 40, the distance between the resolver stator 25B is periodically changed in the circumferential direction, and the reluctance between the two depends on the position of the teeth of the resolver rotor 15B. It changes continuously. For each rotation of the resolver rotor 15B, a multipolar resolver signal in which the fundamental wave component of the reluctance change has a multi-cycle is output, and the rotation detector 24B becomes a so-called multipolar resolver.

  As described above, the motor 1 includes the rotation detector 24A and the rotation detector 24B having different periods of the fundamental wave component of the reluctance change for each rotation of the rotor 40, thereby grasping the absolute position of the motor rotation shaft 10. In addition, the accuracy of measuring the rotation state (for example, the rotation speed, the rotation direction, or the rotation angle) of the motor rotating shaft 10 can be improved.

  The motor 1 is positioned and fixed with respect to the support member 51 by attaching the housing base 21 to the support member 51. When the housing base 21 is attached to the support member 51, the housing base 21 has at least one series of continuous surfaces in contact with the attachment surface of the support member 51. This continuous surface can act by dispersing the weight of the motor 1 and vibration during rotation on the support member 51. For this reason, the possibility that distortion (deflection) occurs in the housing base 21 can be prevented.

  In the motor 1, the load body 52 is directly fixed to the rotating shaft 12 by a fixing member 17 such as a bolt. When the mass of the load body 52 is large, the motor 1 needs to have sufficient motor torque. Further, when the motor 1 includes cogging torque and torque ripple in the rotation of the rotor 40, there is a risk of causing vibration of the rotating shaft 12. The vibration of the rotating shaft 12 is transmitted to the load body 52. Thereby, when a moment is applied so that the center of gravity of the load body 52 swings, the life of the bearing 14 of the motor 1 may be shortened.

  As described above, the motor 1 can directly transmit the rotational force to the load body 52 without interposing a transmission mechanism. For this reason, when rotating the load body 52, the motor 1 is required to increase the motor torque and reduce the cogging torque and the torque ripple.

  FIG. 2 is a partial cross-sectional view schematically showing the rotor by cutting the configuration of the motor of Embodiment 1 along a virtual plane orthogonal to the rotation center. FIG. 2 is a cross-sectional view taken along the line II-II of FIG. As shown in FIG. 2, the rotor 40 includes a rotor yoke 41 and a magnet 42. The rotor yoke 41 is formed in a cylindrical shape. The rotor yoke 41 is manufactured by laminating thin plates such as electromagnetic steel plates and cold rolled steel plates by means of adhesion, boss, caulking or the like. For example, the rotor yoke 41 is sequentially stacked in a mold and discharged from the mold.

  A plurality of magnets 42 are attached along the outer peripheral surface of the rotor yoke 41, and a plurality of magnets 42 are provided. The magnet 42 is a permanent magnet, and S poles and N poles are alternately arranged at equal intervals in the circumferential direction of the rotor yoke 41. Accordingly, the number of poles of the rotor 40 shown in FIG. 2 is 28 poles in which the N poles and the S poles are alternately arranged in the circumferential direction of the rotor yoke 41 on the outer peripheral side of the rotor yoke 41. The number of poles of the rotor 40 is not limited to 28 poles, and may be 20 poles or 36 poles, for example, and can be changed as needed. For example, an Nd—Fe—B magnet can be used as the permanent magnet.

  On the outer periphery of the rotor yoke 41, a plurality of positioning protrusions 41b for positioning the magnet 42 are provided in the circumferential direction. A space between the positioning convex portions 41 b is a concave portion that accommodates the magnet 42, and is a groove formed in the outer periphery of the rotor yoke 41. The magnet 42 is affixed to the contact surface 41 a of the recess that accommodates the magnet 42. The magnet 42 is accommodated between the positioning convex portions 41b of the rotor yoke 41, and is attached to the contact surface 41a with an adhesive, for example. In the present embodiment, the magnet 42 is a segment magnet having a segmented shape (segment structure) that is affixed along the contact surface 41 a on the outer peripheral surface of the rotor yoke 41.

  In FIG. 2, the rotation radius R1 of the rotor 40 is a distance from the rotation center Zr to the outermost peripheral surface of the magnet 42 that is the farthest distance in the radial direction. The radius (curvature radius) of the arc in the rotation direction at the outer peripheral portion (outer peripheral surface) in the radial direction of the magnet 42 is defined as r1. The virtual curve Q <b> 1 is a curve obtained by extending an arc on the outer periphery of the magnet 42. The arc of the outer peripheral portion (outer peripheral surface) in the radial direction of the magnet 42 is set to a radius r1 from the center Mr of the arc of the virtual curve Q1. The radius (curvature radius) of the circular arc in the rotation direction at the inner peripheral portion (inner peripheral surface) in the radial direction of the magnet 42 is defined as r2. The virtual curve Q <b> 2 is a curve obtained by extending an arc on the inner periphery of the magnet 42. The arc of the inner peripheral portion (inner peripheral surface) in the radial direction of the magnet 42 is set to a radius r2 from the center Mr of the arc of the virtual curve Q2.

  In the magnet 42 of the first embodiment, the center of the arc of the virtual curve Q1 and the center of the arc of the virtual curve Q2 are the same center Mr and coincide. Further, the radius r1 of the arc of the virtual curve Q1 and the radius r2 of the arc of the virtual curve Q2 have a relationship of r1> r2. The outer peripheral portion of the magnet 42 refers to the surface far from the rotation center Zr of the magnet 42, and the inner peripheral portion of the magnet 42 refers to the surface closer to the rotation center Zr of the magnet 42. The fact that the center of the arc of the virtual curve Q1 matches the center of the arc of the virtual curve Q2 includes a certain allowable range (error, tolerance, etc.).

  With this structure, the thickness d of the magnet 42 between the outer peripheral portion and the inner peripheral portion of the magnet 42 is constant, and a thin portion is partially reduced. Therefore, a necessary magnetic flux can be generated with a limited magnet amount. Can be secured. Here, the thickness d is the distance between the position where the straight line connecting the starting position of the outer peripheral portion of the magnet 42 and the center Mr of the arc intersects the inner peripheral portion (inner peripheral surface) of the magnet 42 and the starting position of the outer peripheral portion. is there. That is, the difference between the radius r1 of the arc at the outer periphery and the radius r2 of the arc at the inner periphery is the thickness d.

  Further, the arc center Mr of the virtual curve Q1 and the rotation center Zr of the rotor 40 do not overlap. For example, the center Mr of the arc of the virtual curve Q1 is shifted by the shift amount A closer to the radial direction than the rotation center Zr when viewed from the magnet 42. The ratio of the shift amount A to the rotation radius R1 of the rotor 40 is, for example, 30% as a percentage. Thereby, the curvature of the virtual curve Q1 becomes larger than the curvature of the circular arc drawn from the rotation center Zr of the rotor 40 with the rotation radius R1.

  In order to provide the magnet 42 on the outer periphery of the rotor yoke 41, the rotor yoke 41 has a contact surface 41a that forms an arc having the same radius as the radius r2 of the arc of the inner peripheral portion of the magnet 42. That is, the close contact surface 41a of the magnet 42 has the same curvature as the curvature of the virtual curve Q2. With this structure, the inner peripheral portion of the magnet 42 is in close contact with the rotor yoke 41, and the risk of magnetic flux leakage due to a gap can be reduced. As a result, the motor 1 can suppress a decrease in motor torque by effectively using the magnetic flux of the magnet 42. In addition, since the magnet 42 and the rotor yoke 41 are aligned, the motor 1 can stabilize the fixing of the magnet 42. The same radius or the same curvature includes a certain allowable range (error, tolerance, etc.).

  FIG. 3 is an explanatory diagram schematically illustrating the relationship between the rotor and the stator according to the first embodiment. As shown in FIG. 3, the magnet 42 is accommodated between the positioning convex portions 41 b, but protrudes more toward the stator 30 than the rotor yoke 41. In the corner portion 42a on the outer peripheral side of the magnet 42, the gap length that is the distance between the stator core 31 and the magnet 42 is Lg1.

  The stator 30 is provided in a cylindrical shape so as to surround the rotor 40 on the rotation center Zr side. As shown in FIG. 3, the stator 30 has a stator yoke 31 in which teeth 31 a are arranged at equal intervals in the circumferential direction around the rotation center Zr described above, and a back yoke 31 b is integrally arranged. The stator 30 is not limited to such an integral core, and may be a divided core in which a plurality of divided stator cores 31 are arranged at equal intervals in the circumferential direction around the rotation center Zr described above. The stator core 31 is fixed to the housing base 21.

  The stator core 31 is formed by laminating and bundling a plurality of teeth 31a formed in substantially the same shape in the direction of the rotation center Zr. The stator core 31 is made of a magnetic material such as an electromagnetic steel plate. When the plurality of stator cores 31 are combined, the stator 30 forms an annular shape.

  The exciting coil 32 shown in FIG. 3 is a linear electric wire. The exciting coil 32 is concentratedly wound around the teeth 31a of the stator core 31 via an insulator. With this configuration, the number of magnetic poles can be reduced, and the coil amount can be reduced because the coil ends are shortened compared to distributed winding. As a result, the cost can be reduced and the motor 1 can be made compact. The insulator is a member for insulating the exciting coil 32 and the stator core 31 and is formed of a heat resistant member.

  The exciting coil 32 may be distributedly wound around a plurality of teeth 31 a of the stator core 31. With this configuration, the number of magnetic poles is increased and the distribution of magnetic flux is stabilized, so that torque ripple can be suppressed. The exciting coil 32 may be toroidally wound around the outer periphery of the back yoke 31b. With this configuration, a magnetic flux distribution equivalent to distributed winding can be generated. As a result, torque ripple can be suppressed.

  By combining a plurality of stator cores 31 thus configured as shown in FIG. 3, the stator 30 has a shape that can surround the rotor 40. That is, the stator core 31 is annularly arranged with a gap on the outer side of the rotor yoke 41 (the side far from the rotation center Zr).

  As described above, the motor 1 according to the first embodiment includes the rotor 40 including the rotor yoke 41 and a plurality of magnets 42 arranged on the outer periphery of the rotor yoke 41 and arranged in the circumferential direction of the rotor yoke 41. And a stator 30 including an exciting coil 32 that excites the stator core 31 and a stator core 31 that is annularly arranged with a gap Lg1 therebetween. In the magnet 42, the arc center Mr of the outer circumference of the magnet 42 and the arc center Mr of the inner circumference of the magnet 42 coincide with each other, and the arc center Mr of the outer circumference or inner circumference of the magnet 42 and the rotor 40. The rotation center Zr does not match.

  In the motor 1 of the first embodiment, the arc center Mr of the outer peripheral portion of the magnet 42 and the arc center Mr of the inner peripheral portion of the magnet 42 coincide with each other. d is maintained, and the reduction of the total magnetic flux amount due to the decrease in the magnet volume of the magnet 42 can be suppressed. For this reason, since the magnet volume of the corner | angular part 42a of the magnet 42 can be ensured, the demagnetization proof stress of the magnet 42 can be improved. Further, since demagnetization of the magnet 42 can be suppressed, the electric load of the exciting coil 32 of the stator 30 can be increased, and the motor 1 can also increase the motor torque.

  The magnet 42 can ensure the angle θ of the corner portion 42a even if the curvature of the virtual curve Q1 increases. For this reason, in the manufacturing process of the motor 1, the possibility of cracking of the corner portion 42a can be reduced. When the angle θ is an angle formed by the virtual curve Q1 of the magnet 42 and the radial direction from the corner portion 42a toward the rotation center Zr, the manufacturing apparatus can easily form the positioning convex portion 41b of the rotor yoke 41. Further, when the angle θ is an angle formed by the virtual curve Q1 of the magnet 42 and the radial direction from the corner portion 42a toward the rotation center Zr, the manufacturing apparatus accurately arranges the magnets 42 along the outer peripheral surface of the rotor yoke 41. Can be increased.

  Further, since the center Mr of the arc of the outer peripheral portion or inner peripheral portion of the magnet 42 and the rotation center Zr of the rotor 40 do not coincide with each other, the change in magnetic flux linked from the magnet 42 to the stator core 31 can be made smooth. . For this reason, the motor 1 can reduce torque fluctuations and can rotate smoothly. The motor 1 can suppress the cogging torque and the torque ripple that accompany the sudden increase or decrease in the magnetic flux linked from the magnet 42 to the stator core 31.

  In the motor 1 of the first embodiment, the shortest distance h1 from the corner portion 42a of the magnet 42 to the rotor yoke 41 is set to the gap length Lg1 or more. With this structure, the magnetic resistance of the magnetic flux interlinking from the corner 42a of the magnet 42 to the stator core 31 can be made equal to or less than the magnetic resistance of the magnetic flux linking from the corner 42a of the magnet 42 to the positioning convex portion 41b of the rotor yoke 41. it can. Thereby, the motor 1 can suppress the fall of a motor torque.

  The motor 1 of the first embodiment described above is a direct drive motor that directly connects the load body 52 and the rotary shaft 12 without interposing a transmission mechanism. As described above, the motor 1 can reduce torque fluctuations and can rotate smoothly. For this reason, even if the motor 1 transmits the rotational force of the rotating shaft 12 rotating together with the rotor 40 directly to the load body 52 and rotates the load body 52, the life of the bearing 14 can be prevented from deteriorating.

(Embodiment 2)
FIG. 4 is a partial cross-sectional view schematically showing the rotor by cutting the configuration of the motor according to the second embodiment along a virtual plane orthogonal to the rotation center. FIG. 5 is an explanatory diagram schematically illustrating the relationship between the rotor and the stator according to the second embodiment. Note that the same components as those described in the above-described embodiment are denoted by the same reference numerals, and redundant description is omitted.

  The motor 1 of the second embodiment is called an outer rotor type, and the stator 30 is arranged closer to the rotation center Zr than the rotor 40.

  A plurality of magnets 42 are attached along the inner peripheral surface of the rotor yoke 41, and a plurality of magnets 42 are provided. The magnet 42 is a permanent magnet, and S poles and N poles are alternately arranged at equal intervals in the circumferential direction of the rotor yoke 41. As a result, the number of poles of the rotor 40 shown in FIG. 4 is 28 poles in which the N pole and the S pole are alternately arranged in the circumferential direction of the rotor yoke 41 on the inner peripheral side of the rotor yoke 41. The number of poles of the rotor 40 is not limited to 28 poles, and may be, for example, 20 poles or 36 poles, and can be changed as needed.

  On the inner periphery of the rotor yoke 41, a plurality of positioning protrusions 41d for positioning the magnet 42 are provided in the circumferential direction. Between the positioning convex portions 41 d is a concave portion that accommodates the magnet 42, and becomes a groove formed in the inner periphery of the rotor yoke 41. The magnet 42 is affixed to the contact surface 41 c of the recess that accommodates the magnet 42. The magnet 42 is accommodated between the positioning convex portions 41d of the rotor yoke 41, and is attached to the contact surface 41c with an adhesive, for example. In the present embodiment, the magnet 42 is a segment magnet having a segmented shape (segment structure) that is affixed along the contact surface 41 c on the inner peripheral surface of the rotor yoke 41.

  In FIG. 4, the rotation radius R2 of the rotor 40 is a distance from the rotation center Zr to the innermost peripheral surface of the magnet 42, which is the closest distance in the radial direction. The radius of the circular arc in the rotation direction at the outer peripheral portion in the radial direction of the magnet 42 is defined as r1. The virtual curve Q <b> 1 is a curve obtained by extending an arc on the outer periphery of the magnet 42. The arc of the outer peripheral portion (outer peripheral surface) in the radial direction of the magnet 42 is set to a radius r1 from the center Mr of the arc of the virtual curve Q1. The radius (curvature radius) of the circular arc in the rotation direction at the inner peripheral portion (inner peripheral surface) in the radial direction of the magnet 42 is defined as r2. The virtual curve Q <b> 2 is a curve obtained by extending an arc on the inner periphery of the magnet 42. The arc of the inner peripheral portion (inner peripheral surface) in the radial direction of the magnet 42 is set to a radius r2 from the center Mr of the arc of the virtual curve Q2.

  In the magnet 42 of the second embodiment, the center of the arc of the virtual curve Q1 and the center of the arc of the virtual curve Q2 are the same center Mr and coincide. The radius of the arc of the virtual curve Q1 and the radius of the arc of the virtual curve Q2 are r1> r2. The fact that the center of the arc of the virtual curve Q1 matches the center of the arc of the virtual curve Q2 includes a certain allowable range (error, tolerance, etc.).

  With this structure, the thickness d of the magnet 42 between the outer peripheral portion and the inner peripheral portion of the magnet 42 is constant, and a thin portion is partially reduced. Therefore, a necessary magnetic flux can be generated with a limited magnet amount. Can be secured. Here, the thickness d is the distance between the position where the straight line connecting the starting position of the outer peripheral portion of the magnet 42 and the center Mr of the arc intersects the inner peripheral portion (inner peripheral surface) of the magnet 42 and the starting position of the outer peripheral portion. is there. That is, the difference between the radius r1 of the arc at the outer periphery and the radius r2 of the arc at the inner periphery is the thickness d.

  Further, the arc center Mr of the virtual curve Q1 and the rotation center Zr of the rotor 40 do not overlap. For example, the center Mr of the arc of the virtual curve Q1 is shifted by a shift amount A on the side farther in the radial direction than the rotation center Zr when viewed from the magnet 42. The ratio of the shift amount A to the rotation radius R2 of the rotor 40 is, for example, 30% as a percentage. Thereby, the curvature of the virtual curve Q1 becomes smaller than the curvature of the circular arc drawn from the rotation center Zr of the rotor 40 by the rotation radius R2.

  In order to provide the magnet 42 on the inner periphery of the rotor yoke 41, the rotor yoke 41 has a contact surface 41 c that forms an arc having the same radius as the arc of the outer periphery of the magnet 42. That is, the close contact surface 41c of the magnet 42 has the same curvature as the curvature of the virtual curve Q1. With this structure, the outer peripheral portion of the magnet 42 is in close contact with the rotor yoke 41, and the risk of magnetic flux leakage due to a gap can be reduced. As a result, the motor 1 can suppress a decrease in motor torque by effectively using the magnetic flux of the magnet 42. In addition, since the magnet 42 and the rotor yoke 41 are aligned, the motor 1 can stabilize the fixing of the magnet 42. The same radius or the same curvature includes a certain allowable range (error, tolerance, etc.).

  As shown in FIG. 5, the magnet 42 is accommodated between the positioning convex portions 41 d, but protrudes more toward the stator 30 than the rotor yoke 41. In the corner 42c on the inner peripheral side of the magnet 42, the gap length, which is the distance between the stator core 31 and the magnet 42, is Lg2. The stator core 31 is annularly arranged with a gap on the inner side (rotation center Zr side) of the rotor yoke 41, and the rotor 40 has a shape that can surround the stator 30.

  As described above, the motor 1 according to the second embodiment includes the rotor yoke 41 and the rotor 40 including the plurality of magnets 42 arranged on the inner periphery of the rotor yoke 41 and arranged in the circumferential direction of the rotor yoke 41. And a stator 30 including an exciting coil 32 that excites the stator core 31 and a stator core 31 that is annularly disposed with a gap Lg2 therebetween. In the magnet 42, the arc center Mr of the outer circumference of the magnet 42 and the arc center Mr of the inner circumference of the magnet 42 coincide with each other, and the arc center Mr of the outer circumference or inner circumference of the magnet 42 and the rotor 40. The rotation center Zr does not match.

  In the motor 1 according to the second embodiment, the arc center Mr of the outer peripheral portion of the magnet 42 and the arc center Mr of the inner peripheral portion of the magnet 42 coincide with each other, and therefore the thickness between the outer peripheral portion and the inner peripheral portion of the magnet 42. d is maintained, and the reduction of the total magnetic flux amount due to the decrease in the magnet volume of the magnet 42 can be suppressed. For this reason, since the magnet volume of the corner | angular part 42c of the magnet 42 can be ensured, the demagnetization proof stress of the magnet 42 can be improved. Further, since demagnetization of the magnet 42 can be suppressed, the electric load of the exciting coil 32 of the stator 30 can be increased, and the motor 1 can also increase the motor torque.

  Further, since the center Mr of the arc of the outer peripheral portion or the inner peripheral portion of the magnet 42 and the rotation center Zr of the rotor 40 do not coincide with each other, when the rotor yoke 41 rotates, the change in magnetic flux interlinked from the magnet 42 to the stator core 31 is changed. Can be smoothed. For this reason, the motor 1 can reduce torque fluctuations and can rotate smoothly. The motor 1 can suppress the cogging torque and the torque ripple that accompany the sudden increase or decrease in the magnetic flux linked from the magnet 42 to the stator core 31.

  In the motor 1 according to the second embodiment, the shortest distance h2 from the corner portion 42c of the magnet 42 to the positioning convex portion 41d of the rotor yoke 41 is set to the gap length Lg2 or more. With this structure, the magnetic resistance of the magnetic flux interlinked from the corner 42c of the magnet 42 to the stator core 31 can be made equal to or less than the magnetic resistance of the magnetic flux interlinked from the corner 42c of the magnet 42 to the rotor yoke 41. Thereby, the motor 1 can suppress the fall of a motor torque.

  The motor 1 of the second embodiment described above is a direct drive motor that directly connects the load body 52 and the rotary shaft 12 without interposing a transmission mechanism. As described above, the motor 1 can reduce torque fluctuations and can rotate smoothly. For this reason, even if the motor 1 transmits the rotational force of the rotating shaft 12 rotating together with the rotor 40 directly to the load body 52 and rotates the load body 52, the life of the bearing 14 can be prevented from deteriorating.

DESCRIPTION OF SYMBOLS 1 Motor 10 Motor rotating shaft 11 Hollow part 12 Rotary shaft 13 Rotor flange 14 Bearing 15A, 15B Resolver rotor 16, 17, 26, 27, 28 Fixed member 20 Base member 21 Housing base 22 Housing inner 23 Housing flange 24A, 24B Rotation detection 25A, 25B Resolver stator 30 Stator 31 Stator core 31a Teeth 31b Back yoke 32 Exciting coil 40 Rotor 41 Rotor yoke 41a Adhering surface 42 Magnet 42a, 42c Corner portion 51 Support member 52 Load body Mr Center of outer peripheral portion (center of inner peripheral portion)
R1, R2 Rotation radius Zr Rotation center

Claims (4)

A rotor including a rotor yoke and a plurality of magnets provided on an outer periphery or an inner periphery of the rotor yoke and arranged in a circumferential direction of the rotor yoke;
A stator core including a stator core that is annularly arranged with a gap between the rotor yoke and an excitation coil that excites the stator core;
Including
The center of the arc of the outer periphery of the magnet coincides with the center of the arc of the inner periphery of the magnet, and the center of the arc of the outer periphery of the magnet or the inner periphery of the magnet and the rotation center of the rotor A motor characterized by a mismatch.   2. The motor according to claim 1, wherein the rotor yoke has a contact surface that forms an arc having the same radius as the radius of the arc of the outer peripheral portion of the magnet or the radius of the arc of the inner peripheral portion of the magnet.   3. The motor according to claim 1, wherein a shortest distance from a corner portion of the magnet projecting toward the stator to the rotor yoke is equal to or greater than a distance of the gap. A rotating shaft that rotates in conjunction with the rotor;
The motor according to any one of claims 1 to 3, wherein the rotating shaft and the load body to be rotated are directly connected.

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