JP2007267565A - Coreless motor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a coreless motor where a plurality of hollow core coils are surely positioned, even if they are arranged, in a state where a part of them is overlapped in the circumferential direction and deterioration of motor efficiency and of motor characteristics can be prevented. <P>SOLUTION: The motor is provided with a permanent magnet 17, which is fitted to a motor axis 20 and whose peripheral face is multi-electrode-polarized, a yoke 14 confronted with the peripheral face of the permanent magnet 17 via a gap, and a plurality of the hollow core coils 15 which are arranged in the circumferential face of the yoke 14 and in which a part is overlapped in the circumferential direction. A positioning part (tapered-like recess 14a) for positioning the hollow core coils 15 in the circumferential direction is formed in the yoke 14. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a coreless motor used as a power source of, for example, precision equipment, and more particularly to a coreless motor that prevents deterioration of motor characteristics.

  Conventionally, for example, a small motor used as a power source for precision equipment or the like, a coreless motor in which an air-core coil is disposed on the inner surface of a cylindrical yoke and a multi-pole magnetized permanent magnet rotates inside the yoke ( There is a so-called inner rotor motor. This coreless motor has various advantages such as no reluctance torque, such as a cored motor (motor with iron core), less commutation sparks, less electrical noise, and less rotor inertia and better responsiveness. Yes.

  For example, the coreless motor disclosed in Patent Document 1 has a plurality of flat fan-shaped winding coils provided on the inner peripheral surface of the bearing portion, and a coma-type rotor to which a permanent magnet is attached. Here, the plurality of flat fan-shaped winding coils are arranged on the inner peripheral surface of the bearing portion in a state in which the phases are shifted and partially overlapped. Thereby, many flat fan-shaped winding coils can be arrange | positioned and by extension, high torque can be obtained now.

  Further, for example, a coreless motor disclosed in Patent Document 2 includes a cylindrical permanent magnet magnetized with multiple poles, a yoke facing the outer peripheral surface of the permanent magnet via a gap, and an inner peripheral surface of the yoke. A plurality of air-core coils. The plurality of air-core coils are arranged in a state where the phases are not overlapped by shifting the phase by 120 ° in electrical angle (with some gaps between the air-core coils).

JP 04-58747 A (FIG. 1) Japanese Patent No. 2646319 (FIG. 1)

  However, the coreless motor disclosed in Patent Document 2 cannot exhibit sufficient motor characteristics.

  That is, since a plurality of air-core coils are arranged so as not to overlap at all, that is, the width of the air-core coil is smaller than the width of the pole of the permanent magnet, and the magnetic flux of the permanent magnet is not sufficiently used. The characteristics deteriorate (magnetic flux not used for motor rotation increases and the motor characteristics deteriorate). In addition, if a plurality of air-core coils are not overlapped at all, many air-core coils cannot be arranged unlike the coreless motor disclosed in Patent Document 1, and high torque cannot be obtained. .

  On the other hand, in the case of the coreless motor disclosed in Patent Document 1, since the air-core coil (flat fan-shaped winding coil) is arranged in a state where a part thereof overlaps, the width of the pole of the permanent magnet The widths of the air-core coils can be matched, and many air-core coils can be arranged, and the above-described adverse effects can be prevented to some extent. However, if a plurality of air-core coils are arranged in a partially overlapping state, there arises a problem that positioning becomes difficult. If the air-core coil is misaligned, the phase difference of the induced current in each air-core coil varies. As a result, the rotational torque becomes smaller or the torque ripple (the sudden and temporary The reduction in the motor efficiency and motor characteristics will be caused.

  The present invention has been made in view of the above points, and its purpose is to ensure positioning even when a plurality of air-core coils are arranged in a state of being partially overlapped in the circumferential direction. The object is to provide a coreless motor capable of preventing deterioration of motor efficiency and motor characteristics.

  In order to solve the above problems, the present invention provides the following.

  (1) A plurality of permanent magnets whose peripheral surfaces are magnetized, a yoke facing the peripheral surface of the permanent magnet via a gap, and a plurality of portions arranged on the peripheral surface of the yoke and partially overlapping in the circumferential direction A coreless motor, wherein a positioning portion for positioning the air core coil in a circumferential direction is formed on the yoke.

  According to the present invention, a yoke that is opposed to the peripheral surface of the permanent magnet via a gap, and a plurality of air-core coils that are disposed on the peripheral surface of the yoke and partially overlap in the circumferential direction are provided. Since the positioning portion for positioning the air-core coil in the circumferential direction is formed, the plurality of air-core coils are firmly positioned by this positioning portion, and the misalignment of the air-core coil can be prevented. .

  Therefore, it is possible to prevent variations in the phase difference of the induction current in each air-core coil, and thus prevent a reduction in rotational torque and an increase in torque ripple, thereby preventing deterioration of motor efficiency and motor characteristics.

  Here, the “positioning portion” may be any shape as long as it can position the air-core coil in the circumferential direction. For example, a concave groove may be provided on the yoke, or a convex protrusion may be provided on the yoke. In addition, the “positioning portion” may be formed on the outer peripheral surface of the yoke, or may be formed on the inner peripheral surface of the yoke. Furthermore, the “coreless motor” according to the present invention is sometimes called a “slotless motor”, and any name can be used without departing from the spirit of the present invention.

  (2) The coreless motor according to (1), wherein the positioning portion is a plurality of tapered concave portions whose depth changes at least partially in a radial direction of the motor shaft.

  According to the present invention, since the positioning portion described above is a plurality of tapered recesses whose depth changes at least partially in the radial direction of the motor shaft, the plurality of air-core coils are arranged along the tapered recesses. Positioning can be performed smoothly, and the manufacturing process can be facilitated.

  (3) The air-core coil is formed to have a width of approximately 180 ° in electrical direction in the circumferential direction, and the adjacent air-core coils are approximately 120 ° in electrical direction in the circumferential direction by the positioning portion. The coreless motor according to (1) or (2), wherein the coreless motor is positioned in a shifted state.

  According to the present invention, the air core coil described above is formed to have a width of about 180 ° in the electrical direction in the circumferential direction, and adjacent air core coils are electrically angled in the circumferential direction by the positioning portion. Therefore, even if six air-core coils are considered in a three-phase coreless motor, the position of one air-core coil and the next air-core coil are the same. The phase difference does not vary and the motor efficiency and motor characteristics are not deteriorated. In addition, for example, in the case of a structure of 4 pole magnetizing-six coils, the magnetization can be 90 ° / 1 pole with 4 poles of NS—N—S, and the corresponding coil has a mechanical angle of 90 ° range / 1 piece. Further, for example, when considering the structure of 8 pole magnetized-12 coils, the magnetization can be 60 ° / 1 pole, and the coil can be wound in the mechanical angle range of 60 °.

  (4) A part of the air-core coil is arranged on the inner side in the radial direction of the motor shaft than one air-core coil among the air-core coils adjacent in the circumferential direction, and more than other air-core coils. The coreless motor according to any one of (1) to (3), wherein a part of the coreless motor is disposed radially outside the motor shaft.

  According to the present invention, the air-core coil described above is, for example, partly arranged on the inner side in the radial direction of the motor shaft and compared to the right-hand air core coil in the circumferential direction, and the left-hand air core coil in the circumferential direction. As compared with the above, a part of the air-core coil is disposed on the outer side in the radial direction of the motor shaft, so that the individual air-core coils can be positioned more reliably.

  That is, for example, when a specific air-core coil is compared with the air core coil adjacent to the right in the circumferential direction, a part is disposed radially inward of the motor shaft and compared with the air core coil adjacent to the left in the circumferential direction. However, if a part of the air-core coil is disposed radially inward of the motor shaft, both ends in the circumferential direction do not contact the yoke, and positioning by the yoke is difficult. On the other hand, according to the present invention, since it is configured as described above, an arbitrary air-core coil will surely contact one end of both ends in the circumferential direction with the yoke, and consequently positioning by the yoke. Can be performed reliably.

  (5) The coreless motor further includes a circuit board having a magnetic sensor for detecting a magnetic pole of the permanent magnet, and the circuit board is positioned in the circumferential direction by the positioning unit (1). The coreless motor according to any one of (4) to (4).

  According to the present invention, the above-described coreless motor is provided with a circuit board having a magnetic sensor for detecting the magnetic pole of the permanent magnet, and this circuit board is positioned in the circumferential direction by the positioning unit described above. Along with the air-core coil, displacement of the circuit board can be prevented. As a result, the air-core coil and the magnetic sensor can be arranged with high accuracy, and as a result, motor efficiency and motor characteristics can be improved.

  According to the coreless motor according to the present invention, the plurality of air-core coils can be more reliably positioned by the positioning portion formed on the yoke, so that the rotational torque is reduced or the torque ripple is increased. This can prevent the deterioration of motor efficiency and motor characteristics.

  The best mode for carrying out the present invention will be described below with reference to the drawings.

[Machine configuration]
FIG. 1 is a side sectional view showing a mechanical configuration of a coreless motor 1 according to an embodiment of the present invention.

  In FIG. 1, the coreless motor 1 is disposed on the outer peripheral surface of the permanent magnet 17, the yoke 14 facing the outer peripheral surface of the permanent magnet 17 through a gap, and the inner peripheral surface of the yoke 14. An air-core coil 15, a holder 21 that supports the motor shaft 20 and the yoke 14, and a rotor hub 11 that can be rotated around the motor shaft 20 by a bearing (sleeve) 12.

  That is, a motor shaft 20 is attached to the central portion of the holder 21, and the permanent magnet 17 is attached to the bearing 12 disposed through a slight space with the motor shaft 20 via the rotor hub 11 and the back yoke 16. The rotor is configured by being attached. On the other hand, an air core coil 15 is incorporated in the yoke holder 13 via the yoke 14, and the air core coil 15 is disposed to face the permanent magnet 17. The Hall element 18 for detecting the magnetic poles of the permanent magnet 17 is mounted on a sensor substrate 19 fixed to the holder 21 and is disposed in the vicinity of the permanent magnet 17. In the present embodiment, a three-phase inner rotor motor is considered in which the number of poles of the permanent magnet 17 is 4 (NSNS is magnetized on the outer peripheral surface) and the number of air-core coils 15 is 6 in total. ing.

  An outline of the assembly method of the coreless motor 1 will be described. First, the yoke 14 is assembled in the yoke holder 13 while being laminated, and six air-core coils 15 are assembled therein and fixed by bonding or the like. Note that the coreless motor 1 according to this embodiment is characterized by the manner in which the air-core coil 15 is fixed to the yoke 14, which will be described later. When the air-core coil 15 is fixed, the sensor substrate 19 on which the magnetic pole detection Hall element 18 is mounted is attached thereto. The sensor substrate 19 is provided with a pattern for wiring the six air-core coils 15, and the coil wires are soldered. When the stator assembly is completed in this way, the stator assembly is attached to the holder 21. Finally, the motor shaft 20 is fixed to the holder 21, and a rotor set including the rotor hub 11, the bearing 12, the back yoke 16 and the permanent magnet 17 is attached to the stator set. In this way, the coreless motor 1 is completed.

  Here, the fixation aspect of the air-core coil 15 mentioned above is explained in full detail. FIG. 2 is an explanatory diagram for explaining a fixing mode of the air-core coil 15. In particular, FIGS. 2A and 2B are plan sectional views for explaining a fixing mode of the air-core coil 15, and the air-core coil 15, the yoke 14 and the holder of the coreless motor 1 shown in FIG. Focusing on 21 etc. FIG. 2C shows the external configuration of one air-core coil 15.

  According to FIG. 2A, a total of six curved air-core coils 15 (see FIG. 2C) are fixed to the yoke 14. When attention is paid to an arbitrary air core coil 15, it is compared with the air core coil 15 adjacent to the right in the circumferential direction (in FIG. 2A, the air core coil 15 adjacent in the counterclockwise direction). A part of the air core coil 15 is disposed radially inward of the motor shaft 20 and is adjacent to the left side in the circumferential direction (in FIG. 2A, the air core coil 15 adjacent in the clockwise direction). ) Is partially disposed on the outer side in the radial direction of the motor shaft 20.

  FIG. 3 is a diagram illustrating a state in which parts other than the yoke 14 are removed from FIG. In particular, FIG. 3A is a cross-sectional plan view of the semiconductor device when parts other than the yoke 14 are removed from FIG. 2A, and FIG. 3B shows the yoke 14 shown in FIG. It is a perspective view when seen.

  As shown in FIGS. 3A and 3B, a plurality of tapered recesses 14 a whose depths change in the radial direction of the motor shaft 20 are formed on the inner peripheral surface of the yoke 14. Accordingly, the six air-core coils 15 are positioned in the circumferential direction by the tapered recess 14a. Moreover, each air-core coil 15 is formed to have a mechanical angle of about 90 ° in the circumferential direction (see FIG. 2A), and adjacent air-core coils 15 are connected to each other in FIG. ) In the state where the mechanical angle is shifted by about 60 ° in the circumferential direction (that is, in a state where a part thereof is overlapped in the circumferential direction as shown in FIG. 2A). Become.

  On the other hand, the outer periphery of the sensor substrate 19 (see FIG. 2B) on which the Hall element 18 is mounted has a shape along the shape of the yoke 14 (processed along the shape of the yoke 14). ). As a result, the sensor substrate 19 is also positioned in the circumferential direction by the tapered recess 14 a of the yoke 14.

[Effect of the embodiment]
As described above, according to the coreless motor 1, since the positional deviation of the air core coil 15 can be prevented by the tapered recess 14 as described above, the phase difference of the induced current in each air core coil 15 varies. As a result, it is possible to prevent a reduction in rotational torque and an increase in torque ripple, thereby preventing deterioration of motor efficiency and motor characteristics. Further, as the means for positioning the air-core coil 15, a plurality of tapered recesses 14a whose depths change in the radial direction of the motor shaft 20 are employed. The air-core coil 15 can be positioned smoothly. In addition, the manufacturing process can be simplified.

  On the other hand, in the coreless motor 1, as described above, the six air-core coils 15 formed to have an electrical angle of 180 ° (in the case of FIG. 1, a mechanical angle of 90 °) are arranged in the circumferential direction. Since the positioning is performed with the electrical angle shifted by 120 ° (mechanical angle 60 ° in the case of FIG. 1), the phase difference does not vary, and the motor efficiency and motor characteristics are not deteriorated. Further, when focusing on the portion where each air-core coil 15 overlaps, among the air-core coils 15 adjacent to each other in the circumferential direction, the air-core coil 15 is disposed radially inward compared to one, and is disposed radially outward compared to the other. Therefore (see FIG. 2A), all the six air-core coils 15 are surely in contact with the yoke 14 at one of the circumferential ends. Therefore, positioning by the yoke 14 can be performed reliably.

  Furthermore, as described above, the sensor substrate 19 on which the Hall element 18 is mounted is also positioned in the circumferential direction by the tapered recess 14 a of the yoke 14. Therefore, as a result of being able to prevent the positional deviation of the sensor substrate 19 together with the air-core coil 15, the air-core coil 15 and the hall element 18 can be arranged with high accuracy, and as a result, motor efficiency and motor characteristics can be improved. .

  In this embodiment, a three-phase interrotor motor having a structure of 4 (poles) -6 (the number of air-core coils) is considered. However, for example, a two-phase motor or an outer rotor motor may be used. For example, even if it is a motor of 8-12 structure, the kind is not ask | required. Alternatively, the yoke 14 may be fixed to the holder 21 by laminating. By configuring the yoke 14 with a laminated yoke (also called a laminated core), iron loss due to eddy current can be reduced.

  FIG. 4 is a view showing a state in which the tapered recess 14b having a shape different from the tapered recess 14a is formed in the yoke 14. As shown in FIG. As shown in FIG. 4, the tapered recess 14 b has a shape slightly inclined with respect to the axial direction of the motor shaft 20. As a result, the shape of the air-core coil is not shown in FIG. 2C, but can be a hexagonal shape, for example. The depth of the tapered recesses 14a and 14b is preferably set to an optimum value in consideration of the generation of cogging torque. More specifically, a general coreless motor does not generate magnetic attraction unlike a cored motor, and therefore has an advantage of low vibration and noise. However, if the depths of the tapered recesses 14a and 14b are too deep, this advantage may be impaired. Therefore, it is preferable to set this depth to an optimum value. In the coreless motor 1 shown in FIG. 1, since the air gap is sufficiently large and the depth of the tapered concave portion 14a is shallow, there is little possibility of impairing the superiority of the coreless motor.

[Modification]
FIG. 5 is a side sectional view showing a mechanical configuration of a coreless motor 1A according to another embodiment of the present invention. 6 is a cross-sectional plan view of the coreless motor 1A shown in FIG. 5 when focusing only on the yoke 14 and the air-core coil 15. FIG.

  If the present invention is applied to an outer rotor motor, it will be as shown in FIGS. In this case, a plurality of tapered convex portions 14c whose depths change in the radial direction of the motor shaft 20 are formed on the outer peripheral surface of the yoke 14 fixed to the bearing 12, and by the tapered convex portions 14c, Six air-core coils 15 are positioned (see FIG. 6).

  The coreless motor according to the present invention is useful as a device capable of easily and reliably positioning an air-core coil and preventing deterioration of motor efficiency and motor characteristics.

It is side surface sectional drawing which shows the machine structure of the coreless motor which concerns on embodiment of this invention. It is explanatory drawing for demonstrating the fixed aspect of an air-core coil. It is a figure which shows a mode when things other than a yoke are removed from Fig.2 (a). It is a figure which shows a mode that the taper-shaped recessed part of a shape different from a taper-shaped recessed part is formed in the yoke. It is side surface sectional drawing which shows the machine structure of the coreless motor which concerns on other embodiment of this invention. It is a figure which shows a mode when things other than a yoke are removed from FIG.

Explanation of symbols

1, 1A Coreless motor 11 Rotor hub 12 Bearing 13 Yoke holder 14 Yoke 15 Air core coil 16 Back yoke 17 Permanent magnet 18 Hall element 19 Sensor substrate 20 Motor shaft 21 Holder

Claims (5)

A permanent magnet having a multi-pole magnetized circumferential surface;
A yoke opposed to the peripheral surface of the permanent magnet via a gap;
A plurality of air-core coils disposed on the circumferential surface of the yoke and partially overlapping in the circumferential direction,
A coreless motor characterized in that a positioning portion for positioning the air-core coil in the circumferential direction is formed on the yoke.   The coreless motor according to claim 1, wherein the positioning portion is a plurality of tapered concave portions whose depth changes at least partially in a radial direction of the motor shaft. The air-core coil is formed to have a width of approximately 180 ° in electrical direction in the circumferential direction,
The coreless motor according to claim 1, wherein the adjacent air-core coils are positioned by the positioning portion in a state where the air-core coils are shifted by about 120 ° in electrical direction in the circumferential direction.   A part of the air-core coil is disposed radially inward of the motor shaft, and part of the air-core coil is adjacent to the other air-core coil. 4. The coreless motor according to claim 1, wherein the coreless motor is disposed on a radially outer side of the motor shaft. 5. The coreless motor further includes a circuit board having a magnetic sensor for detecting a magnetic pole of the permanent magnet,
The coreless motor according to claim 1, wherein the circuit board is positioned in the circumferential direction by the positioning portion.

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