JP2016086591A - Outer rotor type axial gap brushless motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an outer rotor type axial gap brushless motor (OR type AG motor) capable of further reducing vibrations by suppressing distortion that occurs in a rotor.SOLUTION: An OR type AG motor Ma of the present invention comprises: a stator 1 including a plurality of coils 13-1 and 13-2 which are disposed in a circumferential direction; a first rotor 2-1 including a disc-shaped first rotor body 21-1 and a plurality of first magnets 22-1 disposed circumferentially in the first rotor body 21-1; and a second rotor 2-2 including a disc-shaped second rotor body 21-2 and a plurality of second magnets 22-2 disposed circumferentially in the second rotor body 21-2. The first and second rotors 2-1 and 2-2 are disposed at both sides of the stator 1 at a predetermined interval interposed therebetween in a direction of rotation axes while matching the rotation axes with each other and further include coupling parts 3a for mechanically coupling an outer peripheral edge part of the first rotor body 21-2 and an outer peripheral edge part of the second rotor body 21-2.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an axial gap type brushless motor, and more particularly, to an outer rotor type axial gap brushless motor.

  BACKGROUND ART Motors (electric motors) that convert electrical energy into mechanical energy are used for various applications. In general, a rotor (rotor) that has an axis and rotates about the axis is relatively relative to the rotor. A stator (stator) that is stationary and magnetically interacts with the rotor is provided, and the rotor is rotated by a rotating magnetic field (rotating magnetic field). From the viewpoint of structure, such a motor is abbreviated as a radial gap type brushless motor (hereinafter, abbreviated as “RG type motor” as appropriate) and an axial gap type brushless motor (hereinafter, abbreviated as “AG type motor” as appropriate). ). The RG type motor has a structure in which the stator and the rotor are arranged with a gap in the radial direction, and the AG type motor has a structure in which the stator and the rotor are arranged with a gap in the axial direction. In general, the torque generated by the RG motor is proportional to the product of the rotor radius and the axial length, while the torque generated by the AG motor is proportional to the square of the rotor radius. For this reason, the AG type motor has an advantage that a larger torque can be obtained with a smaller diameter than the RG type motor, and is expected, for example, for vehicle use.

  Such AG type motors are roughly classified into an inner rotor type (hereinafter abbreviated as “IR type” where appropriate) and an outer rotor type (hereinafter abbreviated as “OR type” where appropriate). The IR type AG motor is a motor having a structure in which a coil is arranged in a stator, a magnet is arranged in a rotor, and the rotor is arranged inside the stator. An OR type AG type motor is a motor having a structure in which a coil is arranged on a stator, a magnet is arranged on a rotor, and the rotor is arranged outside the stator (for example, see Patent Document 1). A characteristic difference between the IR type and the OR type is that the IR type has twice as many coils as the OR type, whereas the OR type has twice as many magnets as the IR type. Both the IR type and the OR type have a magnetic back yoke outside the stator. The IR type back yoke functions as a return yoke in a part of the magnetic circuit. Therefore, since the IR type back yoke receives an AC magnetic field generated by the coil, the IR type back yoke has a magnetic body that is difficult to flow eddy current, such as a laminated steel plate or an iron powder molded body, in order to suppress iron loss caused by the coil. Etc. need to be used. On the other hand, since the OR type back yoke basically receives the DC magnetic field of the magnet, it is sufficient to realize simple magnetic shielding. For the OR type back yoke, it is sufficient to use a pure iron-based bulk iron material. For this reason, the OR type AG motor, which has a relatively small number of coils as assembly parts and does not require a relatively expensive magnetic material for the back yoke, is more advantageous for industrial use than the IR type. To be judged.

JP 2010-246171 A

  By the way, the motor rotates the rotor by the rotating magnetic field as described above. In order to generate this rotating magnetic field, the plurality of coils arranged in the circumferential direction on the stator are not energized and excited at the same time, but a predetermined coil among the plurality of coils is energized and excited. Thus, the magnetic field generated in the coil interacts with the magnetic fields of a plurality of magnets arranged in the circumferential direction on the rotor, and generates a rotational force (torque). In other words, vibrations that cause the outer peripheral edge of the rotor, which is the free end, to bend due to the attraction and repulsion of the magnetic force between the magnetic field of the coil and the magnetic field of the magnet are generated at the location where this torque is generated. For example, in a 12-slot 8 pole (12 coils and 8 magnets) excited by a three-phase alternating current, the coils of 4 slots are excited, and torque is generated at 4 locations equally spaced in the circumferential direction. Vibrations that cause the rotor to bend occur at these four locations. For example, in a 12-slot 10-pole (12 coils and 10 magnets) excited by three-phase alternating current, the coils of 4 slots are excited and torque is generated at two equally spaced locations in the circumferential direction. These two vibrations cause the rotor to bend. Such vibration is not preferable because it becomes a noise source and also causes fatigue. In particular, when the frequency of the vibration matches the mechanical resonance frequency of the rotor, the vibration has a large amplitude. As a result, a large noise is generated and the mechanical vibration limit is exceeded, resulting in destruction.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide an outer rotor type axial gap type brushless motor capable of suppressing flexure generated in a rotor and further reducing vibration. .

  As a result of various studies, the present inventor has found that the above object is achieved by the present invention described below. That is, an outer rotor type axial gap brushless motor according to an aspect of the present invention includes a stator having a plurality of coils arranged in a circumferential direction, a disk-shaped first rotor body, and the first rotation. A first rotor including a plurality of first magnets arranged in the circumferential direction on the rotor body; a disk-shaped second rotor body; and a plurality of second magnets arranged in the circumferential direction on the second rotor body. A second rotor having two magnets, and the first and second rotors are arranged on both sides of the stator with a predetermined interval in the rotation axis direction so that the rotation axes coincide with each other. The connecting portion for mechanically connecting the outer peripheral edge portion of the first rotor body and the outer peripheral edge portion of the second rotor body is further provided.

  Such an outer rotor type axial gap type brushless motor (OR type AG type motor) further includes a connecting portion, and the connecting portion allows the pair of first and second rotors to be arranged at the outer peripheral edge portions thereof. Connected to each other. For this reason, when vibration is generated in the first rotor, since the first rotor is connected to the second rotor via the connecting portion, the generation of the vibration is inhibited, and the second rotor When vibration is generated in the rotor, the second rotor is connected to the first rotor via the connecting portion, so that generation of the vibration is inhibited. Therefore, such an OR type AG type motor can suppress the bending generated in the rotor and can further reduce the vibration.

  According to another aspect, in the above-described OR type AG motor, the connecting portion is a cylindrical first member. Preferably, the first member includes through openings formed at predetermined intervals in the circumferential direction.

  According to this, the OR type AG type motor provided with the connection part which consists of a cylindrical 1st member is provided.

  According to another aspect, in the OR-type AG motor described above, the connecting portions are a plurality of columnar second members disposed at equal intervals in the circumferential direction. Preferably, the second member has a cylindrical shape.

  According to this, an OR type AG type motor provided with a connecting portion composed of a plurality of columnar second members is provided.

  The outer rotor type axial gap type brushless motor according to the present invention can suppress the bending generated in the rotor and can further reduce the vibration.

1 is an exploded perspective view showing a configuration of an outer rotor type axial gap brushless motor (OR type AG type motor) in an embodiment. FIG. It is a perspective view which shows the stator in OR type AG type motor of embodiment. It is a perspective view which shows the rotor and connection part in OR type AG type motor of embodiment. It is a figure which shows the simulation result of the surface magnetic flux density in the case of 12 slots 8 poles. It is a figure which shows the simulation result of the surface magnetic flux density in the case of 12 slots 10 poles. It is a figure for demonstrating the deformation | transformation form of the connection part in OR type AG type | mold motor of embodiment.

  Hereinafter, an embodiment according to the present invention will be described with reference to the drawings. In addition, the structure which attached | subjected the same code | symbol in each figure shows that it is the same structure, The description is abbreviate | omitted suitably. Further, in this specification, when referring generically, it is indicated by a reference symbol without a suffix, and when referring to an individual configuration, it is indicated by a reference symbol with a suffix.

  FIG. 1 is an exploded perspective view showing a configuration of an outer rotor type axial gap brushless motor (OR type AG type motor) in the embodiment. FIG. 1A is an overall perspective view, and FIG. 1B is an exploded perspective view around a coil. FIG. 2 is a perspective view showing a stator in the OR type AG motor of the embodiment. FIG. 3 is a perspective view showing a rotor and a connecting portion in the OR type AG type motor of the embodiment.

  As shown in FIGS. 1 to 3, an outer rotor type axial gap brushless motor (OR type AG motor) Ma according to the embodiment includes a stator 1 and a pair of rotors 2 (2-1, 2- 2) and a connecting portion 3a.

  The stator (stator) 1 is a non-rotating portion, and is a device that includes a plurality of coils 3 arranged in the circumferential direction, and obtains a magnetic force from electric energy by energizing the plurality of coils 3. More specifically, the stator 1 includes, for example, a stator body 11, a plurality of fixing pieces 12, a plurality of coils 13, a plurality of iron cores 14, and a plurality of cooling units 15.

  The stator body 11 is formed with a through-opening through which the rotary shaft 4 can be inserted at a central position, and a plurality of notches (recesses) 111 that are notched for fitting the iron core (motor core, teeth) 14 are arranged in the circumferential direction. It is a disk-shaped member formed at equal intervals. The number of the plurality of notches 111 is the same as the number of the plurality of iron cores 14, that is, the number of the plurality of coils 13. As the stator main body 11, for example, a laminate in which plates made of a magnetic material such as iron or steel are laminated, a powder of the magnetic material, or a coating powder in which an insulating coating is formed on the surface of the powder is used. It is formed of a green compact, a combination of these laminate and green compact.

  Each of the plurality of fixed pieces 12 is inserted into each cutout portion 111 after each iron core 14 is fitted into each cutout portion 111 of the stator main body 11. 14 is a member for fixing 14 to the stator main body 11, respectively. By fitting each iron core 14 and each fixing piece into each notch 111 of the stator body 11, the outer contour becomes circular.

  Each of the plurality of coils 13 is a winding formed by winding a long conductor member. Each of the plurality of coils 13 may have a structure formed by winding a long conductor member having a round cross section or a square cross section that is insulated and coated. However, each of the plurality of coils 13 in the present embodiment has a cross section. This is a flat-wise structure formed by winding a rectangular strip-shaped conductor member through an insulating member so that the width direction of the conductor member is along the axial direction of the coil 13. That is, each of the plurality of coils 13 is wound in a coil shape so as to finish winding on the outer peripheral side for the first time from the inner peripheral side, and is a long strip-shaped conductor whose width in the coil axial direction is longer than the thickness in the coil radial direction A member and an insulating member disposed between the turns of the strip-shaped conductor member wound in the coil shape. Each of the plurality of coils 13 may have a single-layer single pancake structure, but each of the plurality of coils 13 in the present embodiment includes first and second subcoils 13-1 stacked in the axial direction. It is a double pancake structure with 13-2. The first and second subcoils 13-1 and 13-2 are electrically connected to each other at each inner peripheral portion. The strip-shaped conductor member may be, for example, a superconductive material, or a metal material having a relatively high thermal conductivity with a relatively low resistivity, such as pure copper (Cu) and aluminum (Al). Good.

  Each of the plurality of iron cores 14 is also called a motor core or a tooth, and serves as a core of each of the plurality of coils 13. Each of the plurality of iron cores 14 is formed of a magnetic material in a cylindrical shape.

  Each of the plurality of cooling units 15 is a member for cooling each of the plurality of coils 13. In the present embodiment, since each of the plurality of coils 13 includes the first and second subcoils 13-1 and 13-2, the plurality of cooling units 15 also correspond to the first and second cooling units 15-. 1 and 15-2. Each of the plurality of first cooling portions 15-1 is a member formed in a cylindrical shape surrounding each of the plurality of first subcoils 13-1 from the outer peripheral side, and fluid is contained therein via a communication path (not shown). Refrigerant is distributed. Each of the plurality of second cooling parts 15-2 is a member formed in a cylindrical shape surrounding each of the plurality of second subcoils 13-2 from the outer peripheral side, and fluid is contained therein via a communication path (not shown). Refrigerant is distributed.

  In such a stator 1, first, each of the plurality of iron cores 14 is fitted into each notch 111 of the stator body 11 at the center position, and then each of the plurality of fixed pieces is fitted into each notch 111. For example, it is fixed by an adhesive or the like. Next, a plurality of first and second subcoils 13-1 and 13-2 are fitted into each of the plurality of iron cores 14 from both sides thereof. Therefore, each of the plurality of coils 13 (first and second subcoils 13-1 and 13-2) is a cored coil. The first cooling unit 15-1 is fitted on the plurality of first subcoils 13-1 on the outer peripheral side, and the first cooling unit 15-2 is fitted on the plurality of second subcoils 13-2 on the outer peripheral side. Thereby, the stator 1 is formed.

  The rotor (rotor) 2 is a device that obtains the magnetomotive force of the stator 1 and converts it into torque. In the present embodiment, the rotor (rotor) 2 includes a pair of first and second rotors 2-1 and 2-2. Composed. The pair of first and second rotors 2-1 and 2-2 are arranged on both sides of the stator 1 so that the rotation axes coincide with each other at a predetermined interval in the rotation axis direction. The first rotor 2-1 rotates first so as to face the disk-shaped first rotor body 21-1 having a through-opening through which the rotating shaft 4 can be inserted and the coil 3 of the stator 1. A plurality of first magnets (for example, permanent magnets) 22-1 are provided on the inner side surface of the child main body 21-1 and arranged at equal intervals in the circumferential direction. The first rotor body 21-1 is formed of a ferromagnetic bulk material such as carbon steel. The plurality of first magnets 22-1 are arranged so that the magnetic poles are staggered like SNSN... Between the first magnets 22-1 adjacent to each other in the circumferential direction. That is, the plurality of first magnets 22-1 are arranged so that the direction of the magnetic field coincides with every other circumferential direction. The second rotor 2-2 is rotated second so as to face the disc-shaped second rotor body 21-2 having a through-opening through which the rotation shaft 4 can be inserted and the coil 3 of the stator 1. A plurality of second magnets (for example, permanent magnets) 22-2 are provided on the inner side surface of the child main body 21-2 and arranged at equal intervals in the circumferential direction. The second rotor body 21-2 is also formed from a ferromagnetic bulk material such as carbon steel. Similarly to the plurality of first magnets 22-1, the plurality of first magnets 22-1 are also arranged such that the magnetic poles are staggered between the magnets 22-2 adjacent to each other in the circumferential direction. The first and second rotors 2-1 and 2-2 have the same shape.

  The number of coils 3 and the first and second magnets 21-1 and 21-2 may be arbitrary. For example, the number of coils 3 may be eight and the number of magnets 21-1 and 21-2 may be twelve (12 slots and eight poles). -2 may be 10 (12 slots and 10 poles), and for example, the coil 3 may be 12 and each of the magnets 21-1 and 21-2 may be 16 (12 slots and 16 poles). For example, the number of coils 3 may be nine, and the number of magnets 21-1 and 21-2 may be eight (9 slots and 8 poles). Thus, various aspects are possible.

  The connecting portion 3a is a bridge structure that mechanically connects the outer peripheral edge portion of the first rotor main body 21-1 and the outer peripheral edge portion of the second rotor main body 21-2. In the present embodiment, the connecting portion 3a has the same outer diameter as that of the first and second rotor bodies 21-1 and 21-2, and does not interfere (contact) with the stator 1. A cylindrical first member having an inner diameter longer than the outer diameter of the stator 1. In the example shown in FIG. 1 and FIG. 3, the connecting portions 3a made of the cylindrical first member are formed at predetermined intervals (for example, equal intervals) in the circumferential direction in order to reduce weight and improve heat dissipation. In addition, a rectangular through-opening 31 is provided in plan view. The connection part 3a should just be a material with the rigidity more than equivalent to the rigidity of the 1st and 2nd rotor main bodies 21-1 and 21-2. For example, the connecting portion 3a is formed of a structural steel material such as carbon steel. In addition, for example, the connecting portion 3a may be a non-magnetic material, and a fiber reinforced plastic material or the like can be selected. Since it is lighter than a metal material, it is effective when it is desired to reduce the moment of inertia of the rotating body. .

  In the stator 1, the pair of first and second rotors 2-1 and 2-2, and the connecting portion 3a having such a configuration, first, as shown in FIG. A cylindrical or cylindrical rotary shaft 4 is inserted into the through opening formed through the central position of 11, and the rotary shaft 4 is fixed to the stator 1. Next, on one side of the stator 1, the rotary shaft 4 is inserted through a bearing into the through-opening formed in the first rotor 2-1 at the center position of the first rotor body 21-1. The first rotor 2-1 is rotatably arranged at a predetermined interval from the stator 1 on one side of the stator 1. Next, the connection part 3 is arrange | positioned so that the stator 1 may be accommodated, The axial direction one end surface is the outer peripheral part of the inner surface of the 1st rotor main body 21-1 in the 1st rotor 2-1. Abut. Next, the first rotor body 21-1 of the first rotor 2-1 and the connecting portion 3a are fixed and connected relatively firmly by fastening means such as screwing or bolting. Next, on the other side of the stator 1, the rotating shaft 4 is inserted through the through opening formed in the second rotor 2-2 at the center position of the second rotor body 21-1 through a bearing. The second rotor 2-2 is rotatably arranged at a predetermined interval from the stator 1 on the other side of the stator 1. At this time, the outer peripheral edge portion of the inner surface of the second rotor main body 21-2 in the second rotor 2-2 is brought into contact with the other end surface in the axial direction of the connecting portion 3a. Next, the 2nd rotor main body 21-2 and the connection part 3a of the 2nd rotor 2-2 are fixed and connected comparatively firmly by fastening means, such as screwing and bolting, for example. Thus, an OR type AG type motor Ma is configured.

  Here, in the OR type AG type motor, as described above, vibration can occur. FIG. 4 is a diagram showing a simulation result of the surface magnetic flux density in the case of 12 slots and 8 poles. In FIG. 4, portions that are excited and have a relatively strong magnetic field are indicated by symbols Sa-1 to Sa-4. FIG. 5 is a diagram showing a simulation result of the surface magnetic flux density in the case of 12 slots and 10 poles. In FIG. 5, portions that are excited and have a relatively strong magnetic field are denoted by reference numerals Sb-1 and Sb-2. For example, in a 12-slot 8 pole (12 coils and 8 magnets) excited by a three-phase alternating current, as shown in FIG. Portions Sa-1 to Sa-4 having a relatively strong magnetic field are generated at these locations, torque is generated at these four locations, and vibrations that deflect the rotor at these four locations can occur. Further, for example, in a 12-slot 10 pole (12 coils and 10 magnets) excited by three-phase alternating current, as shown in FIG. 5, the coils of 4 slots are excited and are equally spaced in the circumferential direction. The portions Sb-1 and Sb-2 having relatively strong magnetic fields are generated at two locations, torque is generated at these two locations, and vibrations that bend the rotor at these two locations can occur.

  The OR type AG motor Ma according to the present embodiment further includes a connecting portion 3a, and the connecting portion 3a causes the pair of first and second rotors 2-1 and 2-2 to be arranged at their outer peripheral edge portions. Are connected to each other. For this reason, when vibration is generated in the first rotor 2-1, the first rotor 2-1 is connected to the second rotor 2-2 via the connecting portion 3a. And the second rotor 2-2 is connected to the first rotor 2-1 via the connecting portion 3a. Therefore, the generation of the vibration is inhibited. In the first and second rotors 2-1 and 2-2, the outer peripheral edge portions of the first and second stator main bodies 21-1 and 21-2 are not free ends, but become one rigid body. Therefore, the OR type AG motor Ma according to the present embodiment can suppress the bending that occurs in the first and second rotors 2-1 and 2-2, and can further reduce the vibration. The OR-type AG motor Ma in the present embodiment rotates relatively quietly and smoothly.

  FIG. 6 is a view for explaining a modified form of the connecting portion in the OR type AG type motor of the embodiment.

  In addition, although the OR type AG motor Ma in the above-described embodiment includes the connecting portion 3a formed of the cylindrical first member, the invention is not limited thereto. For example, as shown in FIG. 6, the OR type AG motor Mb may include a connecting portion 3 b instead of the connecting portion 3 a. An OR-type AG motor Mb of a modified form shown in FIG. 6 is an in-wheel motor that is directly driven by mounting a motor inside a rotating object. The OR-type AG motor Mb is a pair of first and first stators. Two rotors 2-1 and 2-2 and a connecting portion 3 b are provided. The stator 1 and the first and second rotors 2-1 and 2-2 in the OR type AG type motor Mb are the same as the stator 1 and the first and second rotors in the OR type AG type motor Ma described above. Since it is the same as 2-1, 2-2, the description is omitted.

  The connecting portion 3b is a bridge structure that mechanically connects the outer peripheral edge of the first rotor main body 21-1 and the outer peripheral edge of the second rotor main body 21-2. In the example shown in FIG. These are a plurality of columnar second members arranged at equal intervals in the circumferential direction. More specifically, the connection part 3b consists of six column-shaped 2nd members formed, for example with structural steel materials, such as carbon steel, and is arrange | positioned by the 60 degree space | interval in the circumferential direction. Each of the six columnar second members is connected to one end of the first rotor main body 21-1 by being bolted at the outer peripheral edge of the first rotor main body 21-1 to be relatively firmly fixed. Each other end of the second rotor body 21-2 is relatively firmly fixed and connected to the second rotor body 21-2 by bolting at the outer peripheral edge of the second rotor body 21-2. In the example shown in FIG. 6, the connecting portion 3 b is composed of six second members, but may be two or more, and preferably three or more.

  In the example shown in FIG. 6, the stator 1 is fixedly supported by the fixed support member 7 via the rotation shaft 4, and the first and second rotors 2-1 and 2-2 are the first rotor 2. -1 is connected to the axle 6 via a bearing block 5 disposed on the outer surface side.

  Since the in-wheel motor directly transmits the rotational torque to the object to be rotated, suppression of vibration and noise is required, and the OR-type AG motor Mb in the present embodiment can be suitably used for the in-wheel motor. .

  In order to express the present invention, the present invention has been properly and fully described through the embodiments with reference to the drawings. However, those skilled in the art can easily change and / or improve the above-described embodiments. It should be recognized that this is possible. Therefore, unless the modifications or improvements implemented by those skilled in the art are at a level that departs from the scope of the claims recited in the claims, the modifications or improvements are not covered by the claims. To be construed as inclusive.

Ma, Mb Outer rotor type axial gap type brushless motor 1 Stator 2 Rotor 2-1 First rotor 2-2 Second rotor 3a, 3b Connecting portion 21-1 First rotor main body 21-2 Second Rotor body

Claims (3)

A stator comprising a plurality of coils arranged in the circumferential direction;
A first rotor comprising a disk-shaped first rotor body and a plurality of first magnets arranged in the circumferential direction on the first rotor body;
A second rotor including a disk-shaped second rotor main body and a plurality of second magnets arranged in the circumferential direction on the second rotor main body;
The first and second rotors are arranged on both sides of the stator with the rotation axes aligned with each other at a predetermined interval in the rotation axis direction,
An outer rotor type axial gap type brushless motor, further comprising a connecting portion that mechanically connects the outer peripheral edge portion of the first rotor body and the outer peripheral edge portion of the second rotor body. The outer rotor type axial gap type brushless motor according to claim 1, wherein the connecting portion is a cylindrical first member. 2. The outer rotor type axial gap brushless motor according to claim 1, wherein the connecting portions are a plurality of columnar second members disposed at equal intervals in the circumferential direction.