JP2011135735A - Rotor for brushless motor, brushless motor, electric power steering device, and method of manufacturing rotor for brushless motor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reliably fix a magnet to be mounted to a periphery of a rotor core at low cost. <P>SOLUTION: A rotor 10 includes at least one rotor unit 10U. The rotor unit 10U includes a rotor core 6, a plurality of magnets 5 provided at a periphery of the rotor core 6 and arranged toward a peripheral direction of the rotor core 6, and a magnet holding unit 25 that is disposed on both edges of the rotor core 6 and holds the magnets 5. The magnet holding unit 25 includes a circular base 20, a bent unit 21 approaching a side of the rotor core 6 for bending while stretching from each arc on which the magnet 5 does not abut in a periphery of the base 20, and a pressing unit 22 that is provided in the bent unit 21 continuously and presses the magnet 5 to a side of the rotor core 6. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a structure for fixing a magnet to a rotor core of a brushless motor.

  The brushless motor has a structure in which a plurality of magnets are arranged on the outer peripheral portion of the rotor core, and it is necessary to fix the magnets to the rotor core. For example, Patent Document 1 discloses a rotor in which a magnet is disposed on a spacer and fixed by covering with a resin molding material. Patent Document 2 discloses a rotor in which a magnet is fixed by fitting a dovetail groove of a boss member and a dovetail of a magnet holding member. Patent Document 3 discloses a rotor in which a magnet is fixed by fitting a magnet into a protector and sandwiching an engaging claw of the protector between a core protrusion and a cover flange. Further, in Patent Document 4, a claw-shaped protrusion is provided on the core, and after each magnet is placed between the claw-shaped protrusions, each claw-shaped protrusion of the core is rotated to A configuration for fixing a magnet is disclosed.

JP 2001-61244 A (0016, FIG. 1) JP-A-11-243654 (0043, FIG. 3) Japanese Utility Model Publication No. 6-21346 (Claim 1, FIG. 1) JP 2008-109726 A (0021-0023, FIG. 5)

  The technique disclosed in Patent Document 1 requires a mold for providing a resin mold layer on the outer peripheral surface of the rotor core, which increases the manufacturing costs of the rotor and the motor. In addition, the techniques disclosed in Patent Document 2 and Patent Document 3 require that a member for holding a magnet be processed with high accuracy, which increases the manufacturing costs of the rotor and the motor. In the technique disclosed in Patent Document 4, the rotor core is rotated and the magnet is sandwiched and fixed. However, the cost of the production equipment increases, and at the same time, the parts require high accuracy, and the manufacturing cost of the rotor and the motor is low. Get higher.

  The present invention has been made in view of the above, and an object of the present invention is to reliably fix a magnet attached to the outer peripheral portion of a rotor core at low cost.

  Therefore, the rotor for a brushless motor according to the present invention is provided on the rotor core, a plurality of magnets arranged on the outer periphery of the rotor core, arranged in the circumferential direction of the rotor core, and both end faces of the rotor core, And at least one rotor unit that includes the magnet holding portion. The magnet holding portion includes a circular base portion that is overlaid on an end surface of the rotor core, and a plurality of the outer circumferences of the base portion. A plurality of curved portions that are bent from approaching the side surface of the rotor core while extending from each of the arcs that are not in contact with the magnet, and continuously provided in each of the plurality of curved portions, than each of the plurality of curved portions. A pressing portion configured to be wide in the circumferential direction of the base and pressing the plurality of magnets against a side surface of the rotor core. And wherein the Rukoto.

  In the brushless motor rotor according to the present invention, the pressing portion presses the magnet against the side surface of the rotor core according to the above configuration, so that when the rotor rotates, the magnet is prevented from being separated from the side surface of the rotor core by centrifugal force. It can be securely fixed to the rotor core.

  In the brushless motor rotor according to the present invention, the magnet holding portion is provided from the base so that the magnet holding portion protrudes radially outward from the outer periphery of the rotor core, and a plurality of protruding portions in contact with end surfaces of the plurality of magnets. Is further included.

  The brushless motor rotor according to the present invention is configured to further include a protrusion, so that when the center of the base overlaps the center of the end surface of the rotor core, the tip of the protrusion is more than the outer periphery of the end surface of the rotor core. Is also located radially outward. Thereby, when a magnet is arrange | positioned on the side surface of a rotor core, the end surface of a magnet contacts a protrusion part. Therefore, the movement of the magnet in the central axis direction is restricted by the protruding portion, and the magnet can be fixed securely. Further, since the movement of the magnet in the central axis direction is restricted, it is easy to manufacture the rotor core.

  The brushless motor rotor according to the present invention is characterized in that the pressing portion is joined to at least a side surface of the rotor core. Thereby, a magnet can be more reliably fixed to a rotor core.

  In the brushless motor rotor according to the present invention, an opening is provided in each of the plurality of curved portions. Since the opening is provided in the curved portion, the rigidity of the curved portion is reduced as compared with the case where the opening is not provided, and it is easy to bend the curved portion close to the side surface of the rotor core. Become.

  In the brushless motor rotor according to the present invention, each of the plurality of curved portions is provided with a notch from both ends in the width direction toward the center in the width direction. By providing the notch in the curved part, the rigidity of the curved part becomes smaller compared to the case where the notch is not provided, and it is easy to bend the curved part close to the side surface of the rotor core. Become.

  The rotor for a brushless motor according to the present invention includes a plurality of the rotor units, and the rotor units are stacked such that the plurality of magnets are arranged stepwise in a direction parallel to a central axis of the rotor core. It is characterized by being. Thereby, the magnet of a skew arrangement | sequence can be fixed to a rotor core reliably.

  The brushless motor according to the present invention includes the brushless motor rotor, a stator disposed in an annular shape with a predetermined interval outside the brushless motor rotor, and a housing that holds the stator. It is characterized by that. Since the rotor of the brushless motor according to the present invention is low-cost and small, the present invention provides a low-cost and small-sized brushless motor.

  The electric power steering apparatus of the present invention is characterized in that an auxiliary steering torque is obtained by the brushless motor. Since the rotor of the electric power steering apparatus according to the present invention is low cost and small, the present invention provides a low cost and small electric power steering apparatus.

  The method for manufacturing a brushless motor rotor according to the present invention includes a circular base portion, a plurality of extending portions extending from an arc of the base portion, and a plurality of extending portions continuously provided on both end faces of the rotor core. A magnet holding portion having a pressing portion that is wider in the circumferential direction of the base than each of the plurality of extending portions, and on the outer circumferential portion of the rotor core toward the circumferential direction of the rotor core A procedure for arranging a plurality of magnets, a procedure for forming a plurality of curved portions by bending the extending portion close to the side surface of the rotor core, and a deformation of the pressing portion along the outer circumference of the plurality of magnets And a step of pressing the plurality of magnets against a side surface of the rotor core by the pressing portion. This provides a small brushless motor rotor in which the magnet is securely fixed at low cost.

  Therefore, the method for manufacturing a brushless motor rotor according to the present invention includes a procedure in which a plurality of magnets are arranged on the outer periphery of the rotor core in the circumferential direction of the rotor core, a circular base, and an arc of the base The magnet holding portion includes a plurality of curved portions that are bent while approaching a side surface of a cylinder having the base portion as a bottom surface while being stretched, and a pressing portion that is continuously provided in each of the plurality of curved portions. A step of combining the rotor cores so that each of the shape portions fits between the plurality of adjacent magnets, and the pressing portion is deformed along the outer periphery of each of the plurality of magnets, and the plurality of magnets are deformed by the pressing portion. And pressing each against the side surface of the rotor core. This provides a small brushless motor rotor in which the magnet is securely fixed at low cost.

  According to the present invention, the magnet attached to the outer peripheral portion of the rotor core can be reliably fixed at low cost.

FIG. 1 is a configuration diagram of an electric power steering including a brushless motor according to the first embodiment. FIG. 2 is a front view for explaining an example of a reduction gear provided in the electric power steering apparatus according to the first embodiment. FIG. 3 is a cross-sectional view illustrating a configuration of the motor according to the first embodiment. 4 is a cross-sectional view taken along line XX in FIG. FIG. 5 is a perspective view illustrating a configuration of the rotor according to the first embodiment. FIG. 6 is a front view and a side view showing the configuration of the rotor according to the first embodiment. FIG. 7 is an explanatory diagram for explaining a method of manufacturing a rotor according to the first embodiment. FIG. 8 is a perspective view showing the configuration of the rotor according to the first modification. FIG. 9 is a perspective view showing a partial configuration of a rotor according to a second modification. FIG. 10 is a perspective view showing a partial configuration of a rotor according to a third modification. FIG. 11 is a front view illustrating the configuration of the rotor according to the second embodiment.

  Hereinafter, the present invention will be described in detail with reference to the drawings. It should be noted that the present invention is not limited by the modes for carrying out the invention (hereinafter referred to as embodiments). In addition, constituent elements in the following embodiments include those that can be easily assumed by those skilled in the art and those that are substantially the same. In the present embodiment, an example in which the brushless motor according to the present invention is applied to an electric power steering device (EPS) will be described, but the application target of the present invention is not limited to the electric power steering device. Even when the present invention is applied to an electric power steering apparatus, the method is not limited.

(Embodiment 1)
FIG. 1 is a configuration diagram of an electric power steering including a brushless motor according to the first embodiment. First, an outline of an electric power steering apparatus including a brushless motor according to the present embodiment will be described with reference to FIG. As shown in FIG. 1, the electric power steering apparatus 100 detects a steering torque generated in the steering shaft 102 by the operation of the steering wheel 101 with a torque sensor 110 that is a torque detection means, and based on the detection signal, the ECU ( The Electroic Control Unit) 50 drives and controls a brushless motor (hereinafter referred to as a motor if necessary) 1 to generate an auxiliary steering torque to assist the steering force of the steering wheel 101.

  A steering shaft 102 connected to the steering wheel 101 has an input shaft 102a to which a driver's steering force is input and an output shaft 102b to output the input steering force. In the present embodiment, the input shaft 102a and the output shaft 102b are made of a magnetic material such as iron. A torque sensor 110 and a speed reducer 111 are provided between the input shaft 102a and the output shaft 102b.

  The driver's steering force transmitted to the output shaft 102b of the steering shaft 102 is transmitted to the steering mechanism. Specifically, the driver's steering force transmitted to the output shaft 102 b is transmitted to the lower shaft 105 via the universal joint 104 and further transmitted to the pinion shaft 107 via the universal joint 106. The steering force transmitted to the pinion shaft 107 is transmitted to the tie rod 109 via the steering gear 108 to steer the steered wheels.

  The steering gear 108 is configured as a rack and pinion type having a pinion 108a connected to the pinion shaft 107 and a rack 108b meshing with the pinion 108a. By such a steering gear 108, the rotational motion transmitted to the pinion 108a is converted into a straight motion by the rack 108b.

  An auxiliary steering mechanism 103 that transmits auxiliary steering torque to the output shaft 102b is connected to the output shaft 102b of the steering shaft 102. The auxiliary steering mechanism 103 includes a reduction gear 111 connected to the output shaft 102b and a motor 1 connected to the reduction gear 111 and generating auxiliary steering torque. A steering column is constituted by the steering shaft 102, the torque sensor 110, and the speed reducer 111, and the motor 1 applies auxiliary steering torque to the output shaft 102b of the steering column. That is, the electric power steering apparatus 100 in this embodiment is a column assist system.

  The torque sensor 110 detects a driver's steering force transmitted to the input shaft 102a via the steering wheel 101 as a steering torque. Electric power is supplied from an electric power source (for example, a vehicle-mounted battery) 115 to the ECU 50 that controls driving of the motor 1. Note that power is supplied from the power supply 115 to the ECU 50 with the ignition switch 114 being on. The ECU 50 calculates an assist steering command value of the assist command based on the steering torque T detected by the torque sensor 110 and the traveling speed V detected by the vehicle speed sensor 116, and the motor based on the calculated assist steering command value. The supply current value to 1 is controlled.

  FIG. 2 is a front view for explaining an example of a reduction gear provided in the electric power steering apparatus according to the present embodiment. FIG. 2 shows a part in cross section. The speed reducer 111 is a worm speed reducer. The worm 121 spline-coupled to the rotating shaft 1 </ b> S of the motor 1 is held by the speed reducer housing 120 so as to be rotatable by a ball bearing 122 and a ball bearing 123 held by a holder 125. Worm teeth 121 a formed on a part of the worm 121 mesh with worm wheel teeth 124 a formed on a worm wheel 124 that is rotatably held by the speed reducer housing 120. The rotational force of the motor 1 is transmitted to the worm wheel 124 via the worm 121 to rotate the worm wheel 124. The torque of the motor 1 is increased by the worm 121 and the worm wheel 124, and an auxiliary steering torque is applied to the output shaft 102b of the steering column shown in FIG. Next, the configuration of the motor 1 will be described.

  FIG. 3 is a cross-sectional view showing the configuration of the motor according to the present embodiment. 4 is a cross-sectional view taken along line XX in FIG. As shown in FIG. 3, the motor 1 includes a substantially cylindrical housing 2A and a substantially disc-shaped front bracket 2B that closes one open end of the housing 2A. At the end of the housing 2A opposite to the side where the front bracket 2B is provided, a bottom 2Ab is formed integrally with the housing 2A so as to close the end. As the magnetic material forming the housing 2A, for example, a general steel material such as SPCC (Steel Plate Cold Commercial), electromagnetic soft iron, or the like can be applied. The front bracket 2B serves as a flange when the brushless motor 1 is attached to a desired device.

  Inside the housing 2A, a bearing 3 is provided at a substantially central portion of the front bracket 2B, and a bearing 4 is provided at a substantially central portion of the bottom 2Ab. The bearing 3 rotatably supports one end of a rotating shaft 1S disposed inside the housing 2A, and the bearing 4 rotatably supports the other end of the rotating shaft 1S. The rotation center of the rotation shaft 1S is Zr shown in FIG. 3, and corresponds to the center axis of the rotation shaft 1S. Hereinafter, the rotation center and the center axis of the rotation shaft 1S are represented by Zr. Since the rotating shaft 1S is supported by the bearings 3 and 4, the rotation center of the bearings 3 and 4 is also Zr.

  A cylindrical rotor core 6 is arranged around the rotation shaft 1S. The rotor core 6 is not limited to a complete cylinder, and may have a groove for arranging the magnet 5. Further, a surface for allowing the side surface of the magnet 5 to run along the side surface of the rotor core 6 may be formed, and the bottom surface of the rotor core 6 may be polygonal.

  The rotor core 6 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. The rotor core 6 is stacked in a progressive die and discharged from the die. The rotating shaft 1S may be molded integrally with the rotor core 6, or the rotating shaft 1S may be press-fitted into the rotor core 6. A plurality of (5 × n, n is an integer) magnets 5 for driving the motor are provided on the outer periphery of the rotor core 6. The magnet 5 is a permanent magnet that is attached to the outer peripheral portion of the rotor core 6 and has S and N poles alternately magnetized in the circumferential direction of the rotor core 6 at equal intervals, as shown in FIG. In the present embodiment, the magnet 5 has a divided shape (segment structure).

  The magnet 5 is a column having a substantially semicircular bottom surface that is generated when a cylinder is cut along a plane parallel to a plane including its axial direction, but is not limited thereto. For example, the magnet 5 may be a curved plate generated when a circular tube is cut along a plane including its axial direction. The longitudinal direction of the magnet 5 is parallel to the central axis Zr direction of the rotor core 6. In the present embodiment, eight magnets 5 are arranged at equal intervals on the outer periphery of the rotor core 6. A side surface of the rotor core 6 appears between the adjacent magnets 5. The side surface of the rotor core 6 is a surface where the columnar rotor core 6 faces the core 7 of the stator 9.

  As shown in FIG. 4, the core 7 is fixed to the inner peripheral surface of the housing 2 </ b> A in a state where the core 7 is entirely surrounded. In the core 7, for example, a three-phase exciting coil 8 is concentrated and wound via an insulator 11 so as to surround the magnets 5 arranged in the circumferential direction of the rotor core 6. These core 7 and exciting coil 8 constitute a stator 9 of the motor 1. The stator 9 is annularly arranged at a predetermined interval outside the rotor (rotor for brushless motor) 10 (or the rotors 10a, 10b, 10c, and 10d).

  The core 7 is composed of, for example, a plurality of (12 in this embodiment) divided cores 7A that are equally divided. Each of the divided cores 7A has an arc-shaped divided yoke 17 that becomes a cylindrical yoke portion when assembled to form the core 7, and one piece that extends from the inner peripheral surface of the divided yoke 17 toward the rotor 10. The teeth 18 are provided. The exciting coils 8 are concentratedly wound around the teeth 18 of each divided core 7A. Then, the plurality of divided cores 7A are combined and press-fitted into the housing 2A to constitute the annular core 7. In this way, the split core 7A is press-fitted into the housing 2A and fastened to the housing 2A to constitute the core 7. The core 7 and the housing 2A may be fixed by adhesion, shrink fitting, or the like in addition to press-fitting.

  In the present embodiment, the core 7 is configured by combining the split core 7A, but is not limited thereto. For example, the core 7 may be configured integrally or by sintering. The exciting coil 8 is wound around the core 7 to which the insulator 11 is attached after the insulator 11 is attached to the core 7. A terminal block is provided at one end of the stator 9. The bus bar (which may be a power harness) inserted into or inserted into the terminal block and the exciting coil 8 in each layer are electrically connected by fusing, resistance welding, or the like.

  The end of the rotary shaft 1S on the front bracket 2B side protrudes to the outside, and the rotation output of the motor 1 can be taken out by connecting a desired shaft or the like to the end protruding to the outside. In the present embodiment, the end of the rotating shaft 1S that protrudes toward the front bracket 2B is splined to the worm 121 of the speed reducer 111 shown in FIG. The rotating shaft 1S and the worm 121 may be elastic couplings. A resolver 14 that detects the rotational position of the rotor 10 and a terminal block 15 that supports the resolver 14 are provided on the front bracket 2B side of the rotating shaft 1S. The resolver 14 includes a resolver rotor 12 that is attached to the circumferential surface of the rotating shaft 1S by press-fitting or the like, and a resolver stator 13 that is opposed to the resolver rotor 12 with a predetermined gap therebetween. Next, the rotor 10 that constitutes the motor 1, the modified example of the rotor 10, and other embodiments (rotors 10a, 10b, 10c, and 10d) will be described in more detail.

  FIG. 5 is a perspective view of a rotor constituting the motor according to the first embodiment. FIG. 6 is a front view and a side view of the rotor that constitutes the motor according to the first embodiment. The rotor 10 includes a rotor unit 10U, and the rotor unit 10U includes a rotor core 6, a magnet 5, and a magnet holding unit 25. A plurality of magnets 5 are arranged in the circumferential direction of the rotor core 6 on the side surface that is the outer peripheral portion of the rotor core 6.

  The rotor core 6 is provided with magnet holding portions 25 on both end faces thereof. The magnet holding portion 25 bends toward the side surface of the rotor core 6 while extending from each of the circular base portion 20 having substantially the same shape as the end surface of the rotor core 6 and the arc of the outer periphery of the base portion 20 where the magnet 5 is not in contact. The curved portion 21 is configured to be wider in the circumferential direction 23 of the base portion 20 than the curved portions 21, and includes a pressing portion 22 that presses the magnet 5 against the side surface of the rotor core 6. The end surface of the rotor core 6 is a surface from which the rotating shaft 1S of the rotor core 6 protrudes.

  The base 20 of the magnet holder 25 does not have to be a perfect circle, but may be a substantially circular polygon. In this case, the arc not in contact with the magnet 5 corresponds to a polygonal side precisely.

  The magnet holding part 25 may be made of a thin plate such as an electromagnetic steel plate and a cold-rolled steel plate similar to the rotor core 6, or may be made of a thin plate of a nonmagnetic material such as stainless steel. When the magnet holding part 25 is made of a nonmagnetic material, the magnet holding part 25 has little influence on the magnetic flux of the rotor 10. When the magnet holding part 25 is comprised with the thin plate, when the magnet holding part 25 is piled up on the end surface of the rotor core 6, the dimension increase of the rotor 10 in the axial direction can be suppressed. The magnet holding part 25 may be formed in the same thickness in all the places, or the thickness may be changed depending on the places. For example, the curved portion 21 (the extending portion 29: see FIG. 7) may be formed thinner than other places. In this case, the rigidity of the curved portion 21 is smaller than other portions. The magnet holding part 25 can be easily and inexpensively manufactured by pressing a thin plate.

  The magnet holding part 25 may be a part of the rotor core 6 or may be configured as a separate member. In order to configure the magnet holding portion 25 as a part of the rotor core 6, for example, a thin plate such as an electromagnetic steel plate is laminated and the magnet holding portion 25 is laminated on the end surface, and the thin plates are bonded to each other or fixed by a boss, caulking or the like. Thus, a method of manufacturing the rotor core 6 can be employed. If the magnet holding part 25 is configured as a part of the rotor core 6, the number of parts constituting the rotor 10 can be reduced, so that manufacturing costs can be reduced and manufacturing management can be facilitated.

  If the magnet holding part 25 is configured as a separate member from the rotor core 6, the magnet holding part 25 can be detached from the rotor core 6, and the magnet holding part 25 or the magnet 5 can be easily repaired or replaced. In addition, when the rotor 10 is configured on the assumption that the parts of the rotor 10 are attached and detached, it is desirable that each part to be attached / detached is screwed instead of interference fit or adhesion. When it is assumed that the magnet holding part 25 is detached from the rotor core 6, the magnet holding part 25 is preferably screwed to the rotor core 6. This is because, when screwed, the magnet holding portion 25 can be easily detached from the rotor core 6 and attached to the rotor core 6.

  When the magnet 5 is disposed on the outer periphery of the rotor core 6, a gap is generated between the adjacent magnets 5. A curved portion 21 extends from the base portion 20 of the magnet holding portion 25 from the position of a gap formed between the magnets 5. That is, in the outer periphery of the base portion 20, the position of the arc where the magnet 5 is not in contact is the position of the gap generated between the adjacent magnets 5. The width of the curved portion 21 in the circumferential direction 23 of the base 20, that is, the width dimension in the direction orthogonal to the radial direction of the base 20 is desirably the same as or narrower than the width of the gap between the adjacent magnets 5. That is, it is desirable that the curved portion 21 extends continuously from all of the arcs that are not in contact with the magnet 5 in the outer periphery of the base 20 or continuously extends from a part of the arc. When the width of the curved portion 21 is the same as or narrower than the width of the gap between the adjacent magnets 5, when the curved portion 21 is formed by bending the extended portion 29 (see FIG. 7, described in detail later), This is because the deformation of the portion 29 is not easily disturbed by the magnet 5 and it is easy to form the curved portion 21.

  The curved portion 21 is bent toward the side surface of the rotor core 6. The curved portion 21 may be bent in a direction parallel to the central axis Zr of the rotor core 6, or may be bent in a direction toward the inside of the rotor core 6 rather than a direction parallel to the central axis Zr of the rotor core 6. When the curved portion 21 is bent in the direction toward the inside of the rotor core 6 rather than the direction parallel to the central axis Zr of the rotor core 6, the pressing portion 22 continuing to the curved portion 21 causes the magnet 5 to move the rotor core with a stronger force. Since it presses against the side surface of 6, the magnet 5 can be more securely fixed to the rotor core 6.

  A pressing portion 22 that extends from the curved portion 21 to the radially outer side of the base portion 20 is provided. The width of the pressing portion 22 in the circumferential direction of the base portion 20 is configured to be wider than the width of the extending portion 29, that is, the width of the curved portion 21. The pressing part 22 is wider than the width of the gap generated between the adjacent magnets 5. That is, the width of the outer periphery of the base 20 is larger than the length of the line segment that connects both ends of the arc not in contact with the magnet 5. Therefore, the pressing part 22 covers a part of the outer periphery of the magnet 5. Accordingly, the pressing portion 22 restricts the magnet 5 from moving outward in the radial direction of the rotor core 6.

  The pressing portion 22 has a shape along the outer periphery of the magnet 5, but the pressing portion 22 may not be in contact with the magnet 5 on all surfaces thereof. However, it is necessary that at least a part of the pressing portion 22 presses the magnet 5 against the side surface of the rotor core 6, that is, gives the magnet 5 a force toward the radially inner side of the rotor core 6. Thereby, when the rotor 10 rotates, it can suppress that the magnet 5 leaves | separates from the side surface of the rotor core 6 with a centrifugal force, and can fix the magnet 5 to the rotor core 6 reliably.

  With such a configuration, the magnet 5 can be reliably fixed to the rotor core 6, so there is no need to provide a rotor cover that covers the rotor core 6, and the rotor 10 can be applied even when the space in the motor is narrow. . Therefore, the motor can be reduced in size. Of course, when the magnet 5 is cracked or chipped, a rotor cover for covering the rotor core 6 may be provided in order to prevent this scattering.

  The pressing portion 22 and the side surface of the rotor core 6 appearing in the gap between the adjacent magnets 5 may be joined at the joining portion 24 by welding such as TIG welding or spot welding, or by bonding with various adhesives. . Thereby, the magnet 5 can be more reliably fixed to the rotor core 6. The pressing part 22 may be fixed to the outer periphery of the magnet 5. When the area where the pressing portion 22 is joined is large, the magnet 5 can be more securely fixed to the rotor core 6.

  Next, a method for manufacturing the rotor according to the first embodiment will be described with reference to FIG. The base portion 20 of the magnet holding portion 25 is overlaid on the end surface of the rotor core 6. Here, the curved portion 21 is not yet formed. Here, the curved portion 21 before being bent is referred to as an extended portion 29. The extending portion 29 extending continuously from the base portion 20 and the pressing portion 22 continuing to the extending portion 29 are on the same plane as the base portion 20. Next, the rotary shaft 1 </ b> S is press-fitted into the magnet holding unit 25 and the rotor core 6. Next, the magnet 5 is arranged on the outer periphery of the rotor core 6. The magnet 5 is disposed between adjacent extending portions 29 (upper side in FIG. 7). If the magnet 5 is arranged on the rotor core 6 after the base 20 of the magnet holding part 25 is overlaid on the end face of the rotor core 6, the movement of the position of the magnet 5 due to the arrangement work of the magnet holding part 25 or the press-fitting work of the rotating shaft 1S is suppressed. can do.

  Next, the extended portion 29 is bent in a direction parallel to the direction of the central axis Zr of the rotor core 6 to form the curved portion 21 (in FIG. 7). Here, the extending portion 29 is bent in a direction parallel to the central axis Zr direction, but is not limited to this direction, and if the extending portion 29 is bent so as to approach the side surface of the rotor core 6, the curved portion 21 is formed. Good. Next, the pressing part 22 continuing to the formed curved part 21 is deformed along the outer periphery of the magnet 5 and brought into contact with the magnet 5 (lower side in FIG. 7). Note that the procedure for deforming the pressing portion 22 may be performed simultaneously with the procedure for forming the curved portion 21. According to this manufacturing method, an expensive manufacturing facility is not required, and the magnet 5 can be fixed to the rotor core 6 reliably at low cost.

  Before the base portion 20 of the magnet holding portion 25 is overlaid on the end face of the rotor core 6, the magnet 5 may be disposed on the outer peripheral portion of the rotor core 6. From this method, the following manufacturing method can be grasped. A procedure in which a plurality of magnets 5 are arranged in the outer circumferential portion of the rotor core 6 in the circumferential direction of the rotor core 6, and a circular base portion 20 is extended from both ends of the rotor core 6 from the arc of the base portion 20. A magnet having a plurality of extending portions 29 and a pressing portion 22 that is provided continuously to each of the plurality of extending portions 29 and is wider in the circumferential direction of the base 20 than each of the plurality of extending portions 29. A procedure for arranging the holding portion 25, a procedure for forming the plurality of curved portions 21 by bending the extending portion 29 close to the side surface of the rotor core 6, and the pressing portion 22 on the outer periphery of the plurality of magnets 5. And a step of pressing the plurality of magnets 5 against the side surface of the rotor core 6 by the pressing portion 22. The production method is grasped. Thereby, the operation | work which arrange | positions the magnet 5 to the outer peripheral part of the rotor core 6 becomes easy.

  After the pressing portion 22 is brought into contact with the magnet 5, the pressing portion 22 and the side surface of the rotor core 6 may be bonded at the bonding portion 24.

  The rotor according to the first embodiment can also be manufactured by the following procedure. The extending portion 29 of the magnet holding portion 25 is bent before the magnet holding portion 25 is stacked on the end face of the rotor core 6 to form the curved portion 21. The curved portion 21 is formed so as to approach the side surface of the cylinder, assuming a cylinder having the base 20 as a bottom surface. Therefore, when the base portion 20 of the magnet holding portion 25 is overlapped on the end surface of the rotor core 6, the curved portion 21 is a cylindrical side surface having the end surface of the rotor core 6 having substantially the same shape as the base portion 20, that is, the side surface of the rotor core 6. It is formed so that it approaches. A magnet 5 is disposed on the outer periphery of the rotor core 6. Note that either the procedure for forming the curved portion 21 or the procedure for arranging the magnet 5 may be performed first, or both procedures may be performed simultaneously.

  Thus, the rotor core 6 is combined with the magnet holding part 25 which formed the curved part 21 so that each curved part 21 fits between the adjacent magnets 5. In order to combine the rotor core 6 with the magnet holding part 25, the magnet holding part 25 may be brought close to the rotor core 6, or the rotor core 6 may be brought close to the magnet holding part 25. According to this manufacturing method, an expensive manufacturing facility is not required, and the magnet 5 can be fixed to the rotor core 6 reliably at low cost.

(First modification)
FIG. 8 is a perspective view showing the configuration of the rotor according to the first modification. In the rotor 10a, the magnet 5 is fixed to the side surface of the rotor core 6 by a magnet holding portion 25a. The magnet holding portion 25 a is formed with a protruding portion 26 that is provided from the base portion 20 so as to protrude radially outward from the outer periphery of the rotor core 6 and that contacts the end surfaces 31 of the plurality of magnets 5. The protruding portion 26 protrudes from the middle of the position where the adjacent curved portion 21 extends on the circumference of the base portion 20, specifically, on the circumference of the base portion 20. In the present modification, the protruding portion 26 is formed as a rectangular tongue-shaped piece extending outward in the radial direction of the base portion 20. The protruding portion 26 is not limited to a rectangular shape, and may be, for example, a semicircular shape, a wedge shape, or a polygonal shape.

  The length of the protruding portion 26 in the radial direction is such that the tip of the protruding portion 26 is positioned radially outside the outer periphery of the end surface of the rotor core 6 when the center of the base portion 20 is overlapped with the center of the end surface of the rotor core 6. Is set. Thereby, when the magnet 5 is disposed on the side surface of the rotor core 6, the end surface 31 of the magnet 5 is in contact with the protruding portion 26. Therefore, the movement of the magnet 5 in the direction of the central axis Zr is restricted by the protruding portion 26. Further, since the movement of the magnet 5 in the direction of the central axis Zr is restricted, the rotor core 6 can be easily manufactured.

  The protruding portion 26 is formed to be on the same plane as the base portion 20. In this case, the magnet holding part 25a including the protruding part 26 can be easily manufactured by pressing a thin plate. Further, the protruding portion 26 may be formed in a shape that is bent from the base 20 toward the end face of the magnet 5 instead of being flush with the base 20. In this case, the protruding portion 26 functions as a leaf spring, and the protruding portion 26 can apply a force toward the other end surface of the magnet 5 to the end surface of the magnet 5. As a result, the magnet 5 is sandwiched between the protrusions 26 present at both ends of the rotor core 6, and the movement in the direction of the central axis Zr is further suppressed. Further, it is possible to absorb the variation in component accuracy between the magnet 5 and the rotor core 6 and to hold the magnet 5 with certainty.

  Since the rotor 10a has the same configuration as the rotor 10 except that the protrusion 26 is provided on the magnet holding portion 25a, the description thereof is omitted. The rotor unit 10Ua includes the magnet 5, the rotor core 6, and the magnet holding portion 25a.

(Second modification)
FIG. 9 is a perspective view showing a partial configuration of a rotor according to a second modification. In the rotor 10b, the magnet 5 is fixed to the side surface of the rotor core 6 by the magnet holding portion 25b. An opening 27 is provided in the curved portion 21b of the magnet holding portion 25b. The openings 27 are provided in all the curved portions 21b not shown in FIG. Since the curved portion 21 b is provided with the opening 27, the rigidity of the curved portion 21 b is smaller than when the opening 27 is not provided, and the curved portion 21 b is brought closer to the side surface of the rotor core 6. It becomes easy to bend.

  The opening 27 opens from the place where the curved portion 21b extends from the base 20 to the front of the pressing portion 22 formed wider than the curved portion 21b. The width of the substantially curved portion 21b obtained by subtracting the width in the circumferential direction of the base portion 20 of the opening 27 from the width of the curved portion 21b in the circumferential direction of the base portion 20 is the same length over the entire curved portion 21b. The opening 27 has a square shape. However, the width of the substantial curved portion 21b is changed by the curvature of the curved portion 21b, and the width of the opening portion 27 is increased in a place where the curvature is larger, so that the substantial width of the curved portion 21b is further increased. It may be narrowed. Further, the opening 27 is not limited to a square, and may be a circle or the like.

  Since the rotor 10b has the same configuration as the rotor 10a except that the curved portion 21b is provided with the opening 27, the other description is omitted. The rotor unit 10Ub includes the rotor core 6, the magnet holding portion 25b, and the magnet 5.

(Third Modification)
FIG. 10 is a perspective view showing a partial structure of a rotor according to a third modification. In the rotor 10c, the magnet 5 is fixed to the side surface of the rotor core 6 by the magnet holding portion 25c. The curved portion 21c of the magnet holding portion 25c is provided with a notch 28 from both ends in the width direction toward the center in the width direction. Note that the notches 28 are provided in all the curved portions 21c not shown in FIG. Here, the width direction of the curved portion 21c is the circumferential direction of the base portion 20 (arrow 30). The cutout 28 is cut out in a symmetrical shape with respect to a plane passing through the center in the width direction of the curved portion 21c. By providing the cutout 28 in the curved portion 21 c, the rigidity of the curved portion 21 c is smaller than in the case where the cutout 28 is not provided, and the curved portion 21 c is brought closer to the side surface of the rotor core 6. It becomes easy to bend.

  Since the rotor 10c has the same configuration as the rotor 10a except that the notch 28 is provided in the curved portion 21c, the other description is omitted. The rotor unit 10Uc includes the rotor core 6, the magnet holding portion 25c, and the magnet 5.

(Embodiment 2)
The configuration of the rotor according to the second embodiment will be described with reference to FIG. The rotor 10d is configured by stacking the rotor units 10UA, 10UB, and 10UC in the central axis direction so that the central axes of the rotor units coincide with each other. The rotor units 10UA, 10UB, and 10UC all have the same structure, and include a magnet 5, a rotor core 6, and a magnet holding portion 25. In a figure defined by the surface where the magnet 5 and each rotor unit are in contact, the symmetry axis parallel to the central axis direction of the rotor core 6 is shifted little by little in a predetermined direction in the circumferential direction of the rotor core 6. Rotor units are stacked. That is, the plurality of magnets 5 are arranged stepwise on the outer periphery of the rotor core 6 in a direction parallel to the central axis of the rotor core 6. Such an arrangement of magnets is called a skew arrangement. By arranging the magnets 5 in a skew arrangement, torque fluctuation can be reduced. In the rotor 10d, the skew-arranged magnets 5 are securely fixed to the rotor core 6 at a low cost.

  Since the configuration of each rotor unit 10UA, 10UB, 10UC is the same as that of the rotor unit 10U, description thereof is omitted.

  The configuration of the rotor units 10UA, 10UB, and 10UC may be the same as that of the rotor units 10Ua, 10Ub, and 10Uc in addition to the same configuration as that of the rotor unit 10U. Further, the configurations of the rotor units 10UA, 10UB, and 10UC may not be the same, but may be different. The rotor 10d is configured by stacking three rotor units 10UA, 10UB, and 10UC. However, the number of rotor units to be stacked is not limited to three, and may be two or three or more, for example.

  Next, a method for manufacturing the rotor 10d will be described. In order to manufacture the rotor 10d, the rotor units 10UA, 10UB, and 10UC are manufactured in the same manner as the rotor unit 10U of the first embodiment, for example. When the rotor units 10UA, 10UB, and 10UC are manufactured, the rotor units 10UA, 10UB, and 10UC are stacked so that the magnets 5 are in a skew arrangement, and the rotary shaft 1S is press-fitted into the center of the rotor units 10UA, 10UB, and 10UC. Then, the rotor 10d including the rotating shaft 1S and the rotor units 10UA, 10UB, 10UC is manufactured. Moreover, the dimensional variation of the magnet 5 and the rotor core 6 is absorbed, and the magnet 5 can be hold | maintained reliably.

  According to this manufacturing method, an expensive manufacturing facility is not required, and the skew-arranged magnets 5 can be fixed to the rotor core 6 reliably at low cost.

  As described above, the brushless motor rotor, the brushless motor and the electric power steering device, and the method for manufacturing the brushless motor rotor according to the present invention are useful for a brushless motor in which a magnet is fixed to a rotor core.

1 Motor (brushless motor)
1S Rotating shaft 2A Housing 2Ab Bottom 2B Front bracket 3, 4 Bearing 5 Magnet 6 Rotor core 7 Core 7A Split core 8 Exciting coil 9 Stator 10, 10a, 10b, 10c, 10d Rotor 10U, 10Ua, 10Ub, 10Uc, 10UA, 10UB, 10UC rotor unit 11 insulator 17 split yoke 18 teeth 20 base 21, 21b, 21c curved portion 22 pressing portion 24 joint portion 25, 25a, 25b, 25c magnet holding portion 26 projection portion 27 opening portion 28 notch 29 extending portion 100 electric Power steering device 111 Reduction gear

Claims (10)

Rotor core,
A plurality of magnets provided on an outer peripheral portion of the rotor core and arranged in a circumferential direction of the rotor core;
A magnet holding part that is disposed on both end faces of the rotor core and holds the magnet, and includes at least one rotor unit;
The magnet holding part is
A circular base overlapped with an end face of the rotor core;
A plurality of curved portions that bend toward the side surface of the rotor core while extending from each of the arcs that are not in contact with the plurality of magnets of the outer periphery of the base portion;
A pressing portion that is provided continuously to each of the plurality of curved portions, is configured to be wider in the circumferential direction of the base than each of the plurality of curved portions, and presses the plurality of magnets against a side surface of the rotor core; A brushless motor rotor characterized by comprising:   The magnet holding part further includes a plurality of projecting parts provided from the base part so as to project radially outward from an outer periphery of the rotor core and in contact with end surfaces of the plurality of magnets. The rotor for a brushless motor according to 1.   The brushless motor rotor according to claim 1, wherein the pressing portion is joined to at least a side surface of the rotor core.   The rotor for a brushless motor according to any one of claims 1 to 3, wherein an opening is provided in each of the plurality of curved portions.   5. The brushless motor rotor according to claim 1, wherein each of the plurality of curved portions is provided with a cutout from both ends in the width direction toward the center in the width direction.   The rotor unit is a plurality, and the rotor units are stacked so that the plurality of magnets are arranged stepwise in a direction parallel to a central axis of the rotor core. The rotor for brushless motors of any one of 1-5. The brushless motor rotor according to any one of claims 1 to 6,
A stator that is annularly arranged at a predetermined interval outside the brushless motor rotor;
A housing for holding the stator;
A brushless motor comprising:   An electric power steering apparatus characterized in that an auxiliary steering torque is obtained by the brushless motor according to claim 7. Provided on both end faces of the rotor core are a circular base, a plurality of extending portions extending from the arc of the base, and each of the plurality of extending portions, and the periphery of the base is more than each of the plurality of extending portions. A procedure for disposing a magnet holding portion having a pressing portion configured to be wide in the direction;
On the outer periphery of the rotor core, a procedure for arranging a plurality of magnets in the circumferential direction of the rotor core; and
A procedure for forming a plurality of curved portions by bending the extending portion close to the side surface of the rotor core;
A step of deforming the pressing portion along the outer circumference of the plurality of magnets, and pressing the plurality of magnets against a side surface of the rotor core by the pressing portion;
The manufacturing method of the rotor for brushless motors characterized by including these. A procedure for arranging and arranging a plurality of magnets on the outer periphery of the rotor core in the circumferential direction of the rotor core;
A circular base portion, a plurality of curved portions extending from a circular arc of the base portion and bending toward a side surface of a cylinder having the base portion as a bottom surface, and a pressing portion provided continuously to each of the plurality of curved portions. A step of combining the rotor core so that each of the plurality of curved portions fits between the plurality of adjacent magnets;
Deforming the pressing portion along the outer circumference of each of the plurality of magnets, and pressing the plurality of magnets against the side surface of the rotor core by the pressing portion;
The manufacturing method of the rotor for brushless motors characterized by including these.

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