JP2014090541A - Inner rotor type motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an inner rotor type motor which comprises a stator adopting an angular stator core and is capable of implementing torque increase without being enlarged in size.SOLUTION: The inner rotor type motor comprises: a stator including a stator core in which a plurality of main electrodes are projected inside of an annular core back part, and a coil wound around each of the main electrodes via an insulator; and a rotor which is disposed inside of the stator in a rotatable manner so as to oppose distal ends of the main electrodes and includes a rotary shaft around an axis. The core back part of the stator core is configured, such that the outline is substantially square-shaped with four corners cut away, and side faces of four sides of the square form a motor outer surface, respectively. The main electrodes of the stator core are disposed at position tilted at a predetermined angle circumferentially from the center of four pieces of the core back part around the axial center and in the stator core, a ratio of a maximum inner diameter with respect to a minimum outer diameter is set to 0.65 to 0.75.

Description

  The present invention relates to an inner rotor type motor such as a stepping motor including a stator in which a coil is wound around a plurality of main poles that are winding poles, and a rotor disposed inside the stator.

  2. Description of the Related Art Conventionally, stepping motors have been widely used in driving parts including information equipment fields such as printers, facsimiles, and copying machines, and industrial equipment fields such as FA equipment. As this kind of stepping motor, for example, in the case of a hybrid type using a magnetic body and a permanent magnet as a rotor, an inner rotor type shown in, for example, Japanese Patent Application Laid-Open No. 2012-044826 is often used.

  FIG. 8 shows a part of a hybrid stepping motor which is an example of this type of inner rotor type motor. That is, a plurality of (eight) main poles 2 are provided radially on the back yoke 1 that is an annular magnetic body frame so as to protrude inward to form a stator core 3, and each main core of the stator core 3 is formed. A stator (4) is formed by winding a coil (not shown) with an insulating member (not shown) interposed between the poles (2), and a pair of magnetic bodies is formed inside the stator (4) via an air gap. Further, a hybrid rotor 5 configured by sandwiching a permanent magnet magnetized in the axial direction is disposed. Cover members (not shown) are fixed to both sides of the stator 4 in the axial direction, and the rotor shaft 6 of the rotor 5 is supported by bearings respectively held at the center of the cover member.

  In the inner rotor type stepping motor described above, the outer peripheral surface of the stator core 3, that is, the outer peripheral surface of the back yoke 1, constitutes a part of the outer surface of the motor, so that heat generated in the motor is generated in the stator core. 3 can be effectively dissipated, and there is no need to cover the outer peripheral surface of the stator core with a motor cover or the like, and there is an advantage that the material cost of the motor cover or the like can be reduced. In addition, since the cover members provided on both sides in the axial direction of the stator core 3 are configured to comprehensively cover the coil protruding from the axial end surface of the stator core 3 and the entire insulating member, the dust-proof against the inside of the motor Is secured.

JP 2012-044826 A

  Incidentally, in Patent Document 1 described above, the torque of the stator core in the inner rotor type stepping motor having a round outer shape is lower than the square type as shown in FIG. 8 due to the restriction of the magnetic path area. In order to obtain the same torque as that of the square type, there is a description that the outer shape is increased and the motor becomes large. Therefore, the stepping motor using the rectangular stator core shown in FIG. 8 can be expected to have a higher torque than that using the round stator core.

  However, in recent years, there has been a tendency for higher torque to be required depending on the application. In such a case, even if a square stator core is used, there is a problem that the size must be increased. As a means for increasing the torque with the same size as that of the existing motor, a countermeasure such as changing the magnet of the rotor to neodymium having a high magnetic flux density is performed, but this results in an increase in cost.

  The present invention has been made in order to solve the above-described problems, and the object of the present invention is to have a stator employing a square stator core and realize torque increase without causing an increase in size. It is an object of the present invention to provide an inner rotor type motor.

In order to achieve the above object, in the inner rotor type motor of the present invention, a stator core having a plurality of main poles projecting radially inside the annular core back portion, and each of the stator cores A stator having a coil wound around the main pole via an insulator, and a rotor that is rotatably arranged inside the stator so as to face the tip of each main pole, and has a rotation shaft at the center of the axis And an inner rotor type motor comprising two cover members that are provided so as to cover both sides of the stator in the axial direction and each support a bearing that supports the rotor shaft.
The core back portion of the stator core has a substantially square shape with the four corners cut off, and the side surfaces of the four sides of the square form the outer surface of the motor, respectively. It is arranged at a position inclined at a predetermined angle in the circumferential direction from the center of the four pieces around the axis center, and the ratio of the maximum inner diameter to the minimum outer diameter in the stator core is set to 0.65 to 0.75. .

  In the above-described configuration, the stator is constituted by eight main poles in the stator core, and a two-phase coil is wound around the stator, and the main poles are arranged at equal intervals of 45 °. The position of the pole is preferably set at an angle inclined by 22.5 ° in the circumferential direction from the center of each of the four square pieces in the stator core. In addition, the insulator is composed of two insulating members attached to the stator core from both sides in the axial direction, and each of the insulating members covers a plurality of slot insulating portions and the slot insulating portions are connected to the stator core. And four outer surface portions that are substantially flush with the motor outer surface on the four sides of the core back portion. Each of the two cover members includes an end plate portion that constitutes a motor end surface and has a bearing holding portion in the center portion, and a side wall portion that extends in the axial direction from the peripheral edge of the end plate portion and whose tip abuts against the end surface of the stator core It is preferable that the outer surface portions of the four sides of the frame portion are fitted in the openings formed in the center portions of the four sides of the side wall portions of both cover members.

  In this case, on the frame portion of the insulating member, four outer surface portions having the same shape as the outer surface portion are formed at the positions of the four corners of the square, respectively. An opening into which the outer surface portion fits can be formed. Furthermore, it is desirable to provide a relay protrusion on the inner diameter side of the outer surface portion of the frame portion to be engaged with the crossover portion of the coil wound around the main pole.

  In addition, the inner surface on the core back side of the plurality of slots formed between the main poles of the stator core may be an arc surface centered on the axial center, and the core in the slot with respect to the minimum outer diameter of the stator core. The ratio of the inner diameter of the arc surface on the back side is preferably set larger than 0.9. Further, each of the two cover members is formed into an end plate portion that constitutes a motor end surface and has a bearing holding portion at the center portion, and a shape that extends in the axial direction from the peripheral edge of the end plate portion and conforms to the outer peripheral shape of the core back portion. And at the end plate portion of at least one of the cover members, the corner portions corresponding to the cut portions of the four corners of the stator core are integrally provided. It can be set as the structure which forms the screw hole for motor attachment in this corner | angular part.

  On the other hand, the rotor can be configured using a unit rotor composed of a pair of magnetic poles having magnetism and a permanent magnet sandwiched between the rotor magnetic poles and magnetized in the axial direction. A plurality of magnetic teeth are formed at an equal pitch on the outer peripheral surface of the rotor magnetic pole, and each magnetic tooth of the pair of rotor magnetic poles is arranged by being shifted by 1/2 pitch in the circumferential direction. Or you may comprise a rotor by making a unit rotor adjoin 2 sets of axial directions. In this case, both unit rotors are arranged so that the magnetization directions of the respective permanent magnets are opposite to each other, and the tooth positions of the adjacent rotor magnetic poles coincide.

  In the inner rotor type motor configured as described above, in the rectangular stator core, each main pole is arranged at a position inclined at a predetermined angle in the circumferential direction from the center of the four sides of the core back portion, and then fixed. By setting the ratio of the maximum inner diameter to the minimum outer diameter of the child core to 0.65 to 0.75, while ensuring a predetermined number of turns and volume of the coil in each main pole, the ratio of the inner diameter from the conventional one The outer diameter of the rotor can be increased and the torque can be increased. In other words, since the outer diameter of the rotor can be increased, even if a lower-grade magnet is used for the rotor, a torque equivalent to or higher than that of the conventional magnet can be secured, which greatly contributes to cost reduction. It will be possible.

  In addition, when the stator has an 8-main pole configuration and a two-phase coil is used, each main pole is set at an angle inclined by 22.5 ° from the center of the four sides of the square, so that the above-described effects can be obtained. In addition, the stator core can be 90 ° rotationally symmetrical, and when the stator core is formed by laminating a predetermined number of silicon steel plates, the silicon steel plates are punched into a predetermined shape by 90 ° one after another. A method of rotating and stacking can be adopted, and a permeance vector variation suppressing effect can be obtained.

1 is a plan view showing an inner rotor type stepping motor according to an embodiment of the present invention. FIG. 2 is a cross-sectional view of the stepping motor of FIG. 1 taken along the line XY. It is a perspective view of the stepping motor of FIG. It is a top view which shows the stator core and rotor core which are a part of stepping motor of FIG. It is a top view which shows the state which mounted | wore the insulating member to the stator core of FIG. It is a top view which shows the upper side insulation member in FIG. It is a bottom view of the upper cover in the stepping motor of FIG. It is a top view which shows the stator core and rotor core in the conventional inner rotor type | mold stepping motor.

An embodiment of an inner rotor type motor according to the present invention will be described below with reference to the drawings.
1 to 3 show an overall configuration of a two-phase hybrid (HB) type stepping motor 1 which is an example of the present invention, FIG. 1 is a plan view, FIG. 2 is a cross-sectional view, FIG. 3 is a perspective view, 4 shows a stator core 12 of a stator 10 having a main pole number of 8 and an HB type rotor 20 arranged on the inside thereof, and FIG. 5 shows that insulating members 16 and (18) are mounted. The stator core 12 in the state is shown, and FIG. The stator 10 is an example of adopting an 8-main pole structure that does not generate an unbalanced electromagnetic force and is excellent in high-speed performance. Each of the necks that are the winding poles of the 8 main poles is wound with windings. The coils wound around the four main poles are connected to form one phase, and the remaining four main poles are used to form the other one phase, resulting in a two-phase coil configuration as a whole.

  The stator 10 is provided with an annular core back portion 12a whose outer shape is formed in a substantially regular quadrilateral shape with four corners cut off and whose inner periphery is formed on a circumferential surface, and is provided so as to protrude radially inward from the core back portion 12a. A stator core 12 composed of eight main poles 12b arranged at equal intervals in the direction, a two-phase coil 14 (shown in FIG. 2) wound around each main pole 12b, and each main pole 12b It consists of upper and lower insulating members 16, 18 interposed between the coils 14. For example, six inductor teeth protrude from the tip of each main pole 12 b that is a wound pole. The eight main poles 12b are arranged at equal intervals in the circumferential direction every 45 °, and as shown in FIG. 4, at a position shifted in the circumferential direction by θ = 22.5 ° from the center of one side of the core back portion 12a. The main poles 12b are arranged so as to be inclined by θ in the circumferential direction as compared with the conventional one shown in FIG. 8 so that the main poles 12b are arranged. In each main pole 12b, the six inductor teeth are arranged at equal intervals, and are arranged at symmetrical positions with respect to the center line of the main pole 12b. The six inductor teeth can be arranged at unequal pitches for the purpose of improving harmonic components, in addition to being arranged at equal pitches.

  The stator core 12 is configured by laminating a plurality of silicon steel plates. In FIG. 4, for example, four main poles 12b arranged every 90 ° constitute one phase (A phase / C phase), and the remaining four mechanical angles are separated from each other by 90 ° and for one phase. Two phases (B phase and D phase) are formed by the main pole 12b disposed at a mechanical angle of 45 degrees from the main pole. In each phase, the four main poles 12b every 90 ° are excited and driven so as to have different polarities alternately when the coil 14 is energized.

  As shown in FIG. 4, in the stator core 12, the radial thickness at each side of the core back portion 12a is set to the minimum value within the range allowed for magnetic characteristics, and the inner diameter is maximized accordingly. That is, for example, in JP-A-5-168214, in order to generate the maximum torque from the rotor, the ratio of the inner diameter to the outer diameter of the stator is set to 0.62 to 0.64 in the case of two phases. In the conventional configuration shown in FIG. 8, the ratio of the inner diameter Di to the minimum outer diameter Do of the stator core 3 is 0.625. However, as in this embodiment, the core back portion 12a As a result of verification by experiments and various analyzes on the case where is approximately square, the ratio of the inner diameter Di to the minimum outer diameter Do of the stator core 12 corresponding to the length of one side of the square is set to about 0.66 due to characteristics. It has been confirmed that this is possible, and the inner diameter Di is set to be several percent or more larger than the conventional one.

  Here, increasing the inner diameter of the stator core 12 can increase the outer diameter of the rotor and increase the output torque accordingly. However, in the case of the conventional configuration shown in FIG. 8, simply increasing the inner diameter of the stator core shortens the protrusion length of the main pole, thereby reducing the number of turns and the line factor of the coil, and conversely the generated torque. As a result, a decrease is caused. On the other hand, as described in FIG. 4, the position of each main pole 12b is inclined by a predetermined angle θ in the circumferential direction, 22.5 ° in the embodiment, compared to that in FIG. It is possible to increase the inner diameter of the stator core while ensuring a predetermined length, which can greatly contribute to torque increase. Specifically, the stator core 12 shown in FIG. 4 is an example of a size of 56 mm × 56 mm, but the protrusion length similar to the protrusion length of the main pole of the conventional one in FIG. If the radial thickness of the core back portion 12a is set to the minimum value in the allowable range in terms of magnetic characteristics while securing at 12, the ratio of the inner diameter of the core back portion 12a to the minimum outer diameter Do becomes about 0.91. The maximum inner diameter Di (including the main pole 12b) of the stator core 12 at this time is about 0.66 as described above.

  A pair of insulating members 16 and 18 are attached to the stator core 12 from both axial sides (referred to as upper and lower sides for convenience). These are insulators that insulate the coil 14 from the stator core 12, and are formed of a molded body of insulating resin. The upper insulating member 16 mounted from the upper side and the lower insulating member 18 mounted from the lower side respectively have a slot insulating portion 16a covering the upper surface and both side surfaces of each main pole 12b and the lower surface and both side surfaces of each main electrode 12b. The slot insulation part 18a to cover and the frame parts 16b and 18b which connect each slot insulation part 16a and 18a by the upper and lower outer part are each provided. The slot insulating portions 16a and 18a have radially outer edges extending along the inner peripheral surface of the core back portion 12a to connect the adjacent slot insulating portions 16a and 18a to each other. It is configured to cover. At the inner peripheral edges of the upper and lower surfaces of the slot insulating portions 16a and 18a, tongue pieces are provided so as to protrude upward corresponding to the tip portions of the main poles 12b, thereby preventing the coil 14 from protruding to the inner peripheral side. doing.

  As shown in FIGS. 5 and 6, the frame portions 16b and 18b are formed in a substantially circular outer shape, and the outer surface portions 16c and 18c are radially outward at the positions of the slots on the outer peripheral side of the frame portions 16b and 18b. In addition, relay projections 16d and 18d are provided on the inner sides of the outer surface portions 16c and 18c, respectively, for locking the connecting wires of the coils 14. Of the outer surface portions 16c and 18c of the frame portions 16b and 18b, those located on the four sides of the stator core 12 are such that the outer surfaces of the outer surface portions 16c and 18c are positioned on the stator core, as is apparent from FIG. 12 is arranged so as to be substantially flush with the outer surfaces of the four sides. Actually, the frame portion 18b of the lower insulating member 18 is not provided with an outer surface portion at a portion corresponding to a connector to be described later in the four sides of the square, and a connector holding portion is formed.

  When the insulating members 16 and 18 are attached to the stator core 12 from above and below, the tips of the slot insulating portions 16a and 18a face each other through a slight gap in the slots of the stator core 12, thereby The peripheral surface of each main pole 12b and the inner surface of the core back portion 12a are covered with insulating members 16 and 18, and the coil 14 is wound around each main pole 12b in this state. The slot insulating portion 16 a of the upper insulating member 16 has a longer axial length than the slot insulating portion 18 a of the lower insulating member 18. Of course, the axial lengths of the slot insulating portions 16a and 18a of the both insulating members 16 and 18 may be the same length, and the lower side may be formed longer than the upper side.

  On the other hand, as shown in FIG. 2, the rotor 20 disposed inside the stator core 12 includes a pair of rotor magnetic poles 24 </ b> A and 24 </ b> B that are fixed to the rotor shaft 22 and are opposed to each other in the axial direction. It is composed of a cylindrical permanent magnet 26 sandwiched between the child magnetic poles 24A and 24B and magnetized in the axial direction. These rotor magnetic poles 24A and 24B are each formed by laminating silicon steel plates and the like, and a plurality of (for example, 50) magnetic teeth are provided on the outer periphery of each of the rotor magnetic poles 24A and 24B. The two permanent magnets 26 are arranged so as to be offset from each other and the permanent magnet 26 is sandwiched between them. The magnetic teeth of the rotor magnetic poles 24A and 24B of the rotor 20 are opposed to the inductor teeth of the main magnetic poles 12b of the stator 10 in the radial direction through an air gap of, for example, 0.05 mm. As the permanent magnet 26, for example, an FCC magnet is used.

  Here, as described above, the inner diameter of the stator 10 is set to be several percent or more larger than that of the conventional one. In accordance with this, the outer diameter of the rotor 20 is about several percent of that of the conventional one. It is set large. For this reason, even if an FCC magnet substantially equivalent to an alnico magnet is used as the permanent magnet 26, the torque obtained is large at each stage. Of course, as the permanent magnet 26, a ferrite type having a low residual magnetic flux density may be used.

  In FIG. 2, an upper cover member 30 and a lower cover member 32 are disposed on both sides in the axial direction of the stator 10, and constitute an outer surface of the motor together with the outer peripheral surface of the stator 10. Both the cover members 30 and 32 are each made of a metal material, and the outer sides thereof are formed in a substantially regular quadrilateral shape like the stator core 12.

  The upper cover member 30 includes a substantially square end plate portion 30a constituting the upper end surface of the motor, and a cylindrical bearing holding portion 30b formed so as to protrude downward at the center portion of the end plate portion 30a. And a side wall portion 30c that is formed in a peripheral edge portion of the end plate portion 30a so as to protrude downward, and has a substantially square shape with the outer peripheral surface being substantially flush with the outer peripheral surface of the stator core 12. It becomes. Four corners 30d of the end plate 30a protrude from the four corners of the side wall 30c, and screw holes 30d 'are formed at these positions.

  The lower cover member 32 includes a substantially square end plate portion 32a with four corners forming the lower end surface of the motor, and a cylindrical bearing formed so as to protrude upward at the center portion of the end plate portion 32a. The holding part 32b and the peripheral wall part 32c formed so that it might protrude upward from the periphery of the end plate part 32a are provided. One side of the square four sides of the lower cover member 32 has a large opening by extending one side of the end plate 32a outward and extending the peripheral wall 32c along both sides. A lead portion 32d is formed, in which the connector holding portion of the frame portion 18b is accommodated, and the connector 34 held by the connector holding portion is housed. Each terminal of the two-phase coil 14 is connected to a terminal pin of the connector 34.

  As shown in FIG. 2, the bearing holding portions 30b and 32b of the upper cover member 30 and the lower cover member 32 hold bearings 36 and 38 formed of ball bearings, and the rotor shaft 22 of the rotor 20 is a double bearing. 36 and 38 are rotatably supported. Further, as shown in FIG. 7, four screw insertion holes 30 e are formed in the vicinity of the screw holes 30 d at the four corners of the end plate portion 30 a of the upper cover member 30. The axial insertion holes 12c communicate with each other, and screw holes (not shown) are formed in the lower cover member 32 in accordance therewith. Then, the fixing screws 40 are inserted through the screw insertion holes 30e of the end plate portion 30a, and are fastened to the screw holes in the lower cover member 32 through the screw insertion holes 12c of the stator core 12, whereby both the upper and lower sides of the stator 10 are fixed. The upper and lower cover members 30 and 32 can be integrally fixed to each other.

  Here, as is apparent from FIGS. 3 and 7, the side wall 30c of the upper cover member 30 is formed with openings 30f that form windows at the center of the four sides of the square and the center of the four corners. The outer surface 16c of the frame 16b of the upper insulating member 16 is fitted to the outer surface 16c, and the outer surface of each outer surface 16c is continuous with the outer surface of the side wall 30c of the upper cover member 30. It is supposed to constitute a part of. Moreover, as shown in FIG. 3, the side wall part 32c in the lower cover member 32 is an opening that forms windows in the central part of the three sides excluding the lead part 32d and the central part of the four corner parts among the four sides of the square. 32 f is formed, and each outer surface portion 18 c in the frame portion 18 b of the lower insulating member 18 is fitted therein, and the outer surface of each outer surface portion 18 c is the side wall portion 32 c of the lower cover member 32 as described above. Part of the outer surface of the motor that is continuous with the outer surface of the motor.

  Insulating covers 42 and 44 are arranged above and below the stator 12 so as to cover the upper and lower surfaces of the coil 14 wound around each main pole 12 b, and coils for the end plate portions 30 a and 32 a of the upper and lower cover members 30 and 32. 14 insulation is secured. The insulating covers 42 and 44 are formed of an insulating resin and cover the upper and lower sides of the main poles 12b, that is, slot insulation corresponding to the frame portions 16b and 18b of the insulating members 16 and 18 and the tips of the main poles 12b. It is formed in an annular shape so as to cover the space between the tongues of the portions 16a and 18a. These insulating covers 42 and 44 are formed with auxiliary projections 42a and 44a respectively corresponding to the outer surface portions 16c and 18c of the frame portions 16b and 18b on the outer peripheral edges thereof. Along with 18c, the cover members 30 and 32 are fitted into the openings 30f and 32f of the side walls 30c and 32c. As a result, the insulating covers 42 and 44 are prevented from rotating and pressed against the cover members 30 and 32 to be securely fixed. In addition, the openings 30f and 32f are hermetically closed. A dustproof effect for the inside of 30 and 32 is obtained.

  In the stepping motor configured as described above, the frame portions 16b and 18b of the upper and lower insulating members 16 and 18 used to insulate the coil 14 from the stator core 12 are accommodated inside the upper and lower cover members 30 and 32. Instead, the outer surface portions 16c and 18c are partly exposed on the motor surface, so that the inner diameter of the stator core 12 can be maximized, and each main pole of the stator core 12 can be maximized. Since 12b is set at an angle inclined by 22.5 ° in the circumferential direction compared to the conventional one, it becomes possible to secure a predetermined number of turns of the coil 14 in each main pole 12b, and the rotor 20 has a larger diameter. The output can be greatly increased. For this reason, even if a low-grade ferrite permanent magnet is used as the permanent magnet 26 of the rotor 20, it is possible to increase the output as compared with the conventional one, and an inexpensive motor can be provided.

As mentioned above, although preferable embodiment of this invention was described, this invention is not limited to the said embodiment, A various deformation | transformation is possible in the range described in the claim.
The configuration of the present invention can be similarly applied to motors of different sizes. For example, when applied to an HB type stepping motor having an outer shape of 42 mm × 42 mm and 8 main poles and 2 phases, experiments and various analyzes are performed. As a result of the verification, it is confirmed that the ratio of the inner diameter Di to the minimum outer diameter Do of the stator core can be set to about 0.75, and the inner diameter Di can be set larger by more than 10% compared to the conventional case. .

  In the above-described embodiment, the case of a two-phase stepping motor has been described. However, the present invention is not limited to this, and may be applied to other inner rotor type motors, or may be a case of a three-phase motor. Further, the rotor of the motor is not limited to the hybrid type, and a permanent magnet type rotor in which different magnetic poles are alternately arranged in the circumferential direction may be used. In addition, the bearings 36 and 38 that rotatably support the rotor 20 are not limited to ball bearings, and sliding bearings can also be used.

  Further, as the rotor, an HB type rotor is used in which a permanent magnet magnetized in the axial direction is sandwiched between a pair of magnetic poles having magnetism, but a rotor adopting a plurality of the rotor configurations is used. You can also. That is, the rotor can be configured by adjoining, for example, two sets of unit rotors each composed of a pair of rotor magnetic poles and permanent magnets. In this case, both unit rotors are preferably arranged so that the magnetization directions of the respective permanent magnets are opposite to each other and the tooth positions of the adjacent rotor magnetic poles coincide with each other. Alternatively, when the rotor is constituted by adjoining two unit rotors in the axial direction, the permanent magnets are magnetized in the same direction, while a nonmagnetic insulator is interposed between the unit rotors. You may do it.

  The inner rotor type motor according to the present invention can increase the torque and reduce the cost, and as a stepping motor, it can be rotated at low cost, high speed, high torque and low vibration for use in a copying machine or printer as an OA device. Electricity can be provided and a significant industrial contribution is expected. In addition, application to medical equipment, FA equipment, robots, amusement machines, and housing equipment is also highly expected.

10: Stator 12: Stator core 12a: Core back part 12b: Main pole 14: Coils 16, 18: Insulating members 16a, 18a: Slot insulating parts 16b, 18b: Frame parts 16c, 18c: Outer surface part 20: Rotation Child 24A / 24B: Rotor magnetic pole 22: Rotor shaft 26: Permanent magnet 30/32: Cover member 30a / 32a: End plate 30c / 32c: Side wall 30f / 32f: Opening

Claims (10)

A stator core having a plurality of main poles projecting radially inside the annular core back portion, and a stator having a coil wound around each main pole of the stator core via an insulator; and A rotor that is rotatably arranged inside the stator so as to face the tip of each main pole, and that has a rotation shaft at the center of the shaft, and is provided so as to cover both axial sides of the stator. In an inner rotor type motor composed of two cover members holding a bearing that supports a shaft,
The core back portion of the stator core has a substantially square shape with four corners cut off, and the sides of the four sides of the square form a motor outer surface,
Each of the main poles of the stator core is disposed at a position inclined at a predetermined angle in the circumferential direction from the center of the four pieces of the core back portion around the axis center
A ratio of a maximum inner diameter to a minimum outer diameter in the stator core is set to 0.65 to 0.75.   The stator is composed of eight main poles in the stator core, and a two-phase coil is wound around the stator poles, and the main poles are arranged at equal intervals of 45 °. The inner rotor type motor according to claim 1, wherein the position is set at an angle inclined by 22.5 ° in the circumferential direction from the center of each of the four square pieces in the stator core. The insulator is composed of two insulating members attached to the stator core from both sides in the axial direction, and each of the slot insulating portions covers the main pole and the slot insulating portions are axial end faces of the stator core. And four outer surface portions that are substantially flush with the outer surface of the motor on the four sides of the core back portion.
Each of the two cover members includes an end plate portion that constitutes a motor end surface and has a bearing holding portion in the center portion, and a side wall portion that extends in the axial direction from the periphery of the end plate portion and has a tip abutting against the end surface of the stator core. The opening which the outer surface part of four sides in the said frame part fits in is formed in the center part of the four sides of the said side wall part in the said both cover members. Inner rotor type motor.   Four outer surface portions having the same shape as the outer surface portion are formed at the four corners of the square in the frame portion of the insulating member, respectively, at the positions of the square four corners of the side wall portions of the two cover members, The inner rotor type motor according to claim 3, wherein an opening into which an outer surface portion of the frame portion is fitted is formed.   The relay protrusion which the crossover part of the coil wound around the said main pole latches is provided in the internal diameter side of the outer surface part in the said frame part, The Claim 3 or 4 characterized by the above-mentioned. Inner rotor type motor.   2. The inner surface on the core back side of a plurality of slots respectively formed between the main poles of the stator core is an arc surface centered on the axis center. The described inner rotor type motor.   The inner rotor type motor according to claim 6, wherein a ratio of an inner diameter of a circular arc surface on the core back side in the slot to a minimum outer diameter of the stator core is set to be larger than 0.9.   Each of the two cover members is formed into an end plate portion that constitutes a motor end surface and has a bearing holding portion in the center portion, and a shape that extends in the axial direction from the peripheral edge of the end plate portion and follows the outer peripheral shape of the core back portion. And a side wall portion that abuts against the end face of the stator core, and the end plate portion of at least one cover member has corner portions corresponding to the cut portions of the four corners of the stator core. 2. The inner rotor type motor according to claim 1, wherein the inner rotor type motor is integrally formed, and a screw hole for mounting the motor is formed at the corner portion.   The rotor is configured using a unit rotor including a pair of magnetic rotor poles and a permanent magnet sandwiched between the rotor magnetic poles and magnetized in the axial direction. 2. The inner rotor type according to claim 1, wherein a plurality of magnetic teeth are formed on the surface at equal pitches, and the pair of rotor magnetic poles are arranged with each magnetic tooth being shifted by ½ pitch in the circumferential direction. motor.   The rotor is configured by adjoining the unit rotors in the direction of two sets of axes, and the unit rotors have directions in which the magnetization directions of the permanent magnets are opposite to each other, and adjacent rotor magnetic poles. The inner rotor type motor according to claim 9, which is arranged so that the tooth positions thereof coincide with each other.

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