JP6053634B2 - Coreless motor - Google Patents

Description

  The present invention relates to a coreless motor that is used as a drive source in various devices or as a vibrator in a portable device.

  As a method of reducing the size of the coreless motor, there is a method of removing an unnecessary portion where the magnetic flux does not pass so much in the outer shape of the housing formed of a magnetic material.

  For example, Patent Document 1 discloses a coreless motor in which a thin wall portion is formed by cutting a part of the outer surface of a housing that originally has a cylindrical shape with a uniform thickness into a flat shape. In this coreless motor, the permanent magnet is magnetized in the direction perpendicular to the thin wall portion, thereby reducing the size while maintaining the output.

Japanese Patent Laid-Open No. 06-217505

  However, in the coreless motor disclosed in Patent Document 1, although the size can be reduced, from the viewpoint of weight reduction, only the weight of a small portion of the housing removed by cutting is reduced. However, it is hard to say that the weight is effectively reduced. In order to reduce the size and weight of a device equipped with a coreless motor, the coreless motor is required not only to be reduced in size but also to be further reduced in weight.

  The present invention provides a coreless motor that can be effectively reduced in weight and a device equipped with the same.

A coreless motor according to one aspect of the present invention includes an outer yoke, a magnet disposed inside the outer yoke, an output shaft disposed rotatably between the outer yoke and the magnet, and an output shaft disposed inside the magnet. And a cup-shaped coil that rotates integrally. The outer yoke includes a housing that accommodates the magnet and the cup-type coil, and an auxiliary yoke that is formed to have a thickness larger than the thickness of the housing and is provided inside the housing so as to face the magnet. configured closest member to the auxiliary yoke inside than the auxiliary yoke is characterized Oh Rukoto cup coils.

  According to the present invention, the thickness necessary for the magnetic circuit of the outer yoke is ensured by the total thickness of the auxiliary yoke and the housing, but most of the thickness is the thickness of the auxiliary yoke. The housing including many portions that do not contribute to the thickness can be formed as thin as possible. Therefore, the coreless motor can be effectively reduced in weight.

BRIEF DESCRIPTION OF THE DRAWINGS (a) Sectional drawing along axial direction of coreless motor which is Example 1 of this invention, (b) Sectional drawing along radial direction, and (c) Magnetic flux diagram. (A) Sectional drawing along axial direction of coreless motor which is Example 2 of this invention, (b) Sectional drawing along radial direction, and (c) Magnetic flux diagram. Sectional drawing along the radial direction of the coreless motor which is Example 3 of this invention. (A) Sectional drawing along the axial direction of the conventional coreless motor, (b) Sectional drawing along radial direction, and (c) Magnetic flux diagram. (A) Sectional drawing along axial direction of coreless motor which is Example 4 of this invention, (b) Sectional drawing along radial direction, and (c) Magnetic flux diagram.

  Embodiments of the present invention will be described below with reference to the drawings. However, prior to the description of the embodiment, the configuration of a conventional coreless motor will be described with reference to FIGS. 4 (a) and 4 (b). FIG. 4A shows a cross section when the coreless motor is cut along the axial direction, and FIG. 4B shows a cross section when the coreless motor is cut along the radial direction. In FIG. 4A, the magnetic lines of force acting between the magnet 103 and the housing 101 serving also as the outer yoke are indicated by arrows.

  Of the housing 101, a portion indicated by 101a is a portion constituting a magnetic circuit, and portions indicated by 101b and 101c are portions that do not contribute to the magnetic circuit. In other words, the portion 101a of the housing 101 corresponds to the outer yoke constituting the magnetic circuit, the portion 101b is a simple front structural portion, and 101c is a simple rear structural portion. FIG. 4C shows a magnetization direction of the magnet 103 and a magnetic circuit (lines of magnetic force) in a cross section along the axial direction.

  Reference numeral 104 denotes a cup-shaped coil, and reference numeral 105 denotes an inner yoke.

  In conventional coreless motors, from the viewpoint of cost reduction, the housing 101 is often manufactured by pressing, with the thickness required for the outer yoke portion 101a constituting the magnetic circuit as the basic thickness. However, it is difficult to finish only the portion 101a constituting the magnetic circuit that requires a thick thickness, and the portions 101b and 101c that do not contribute to the magnetic circuit are also formed to be thicker than necessary. For this reason, the weight of the housing 101 increases, and as a result, it is difficult to reduce the weight of the coreless motor.

  Next, the configuration of the coreless motor that is Embodiment 1 of the present invention will be described with reference to FIGS. FIG. 1A shows a cross section when the coreless motor is cut along the axial direction, and FIG. 1B shows a cross section when the coreless motor is cut along the radial direction.

  In these drawings, reference numeral 1 denotes a housing constituting a part of an outer yoke formed of a magnetic material. The housing 1 has a shape that accommodates each member (magnet 3, cup-type coil 4, inner yoke 5 and the like) described later, and is different from each other orthogonal to the output shaft 11 as shown in FIG. Two curved surface portions 1a arranged on both sides of the output shaft 11 in one of the two directions, and two plane portions arranged on both sides of the output shaft 11 in the other of the two directions 1b. By forming the housing 1 in such a shape, the coreless motor can be reduced in size as compared with the case where the housing is formed in a cylindrical shape as shown in FIGS. .

  Reference numeral 2 denotes an auxiliary yoke constituting another part of the outer yoke formed of a magnetic material. In other words, in this embodiment, the outer yoke is constituted by the housing 1 and the auxiliary yoke 2 formed as a separate member from the housing 1.

  Each auxiliary yoke 2 is formed in a semi-cylindrical shape so as to have a thickness larger than the thickness of the housing 1 (in particular, the thickness of each curved surface portion 1a and each flat surface portion 1b). Further, it is fixed so as to face the outer surface of a cup-shaped coil 4 to be described later. More specifically, as shown in FIG. 1 (b), two auxiliary yokes 2 are arranged on both sides of the output shaft 11, and each is inside (inner surface) of each curved surface portion 1a. And the inner side (inner surface) of the two flat portions 1b is fixed to a region excluding the central region 1c where the cup-shaped coil 4 is close.

  The magnet 3 is formed in a cylindrical shape and is disposed inside the outer yoke (auxiliary yoke 2). FIG. 1C shows the magnetization direction of the magnet 3 and the magnetic circuit (lines of magnetic force) in a cross section orthogonal to the axial direction. The magnetizing direction of the magnet 3 is a direction orthogonal to each planar portion 1 b of the housing 1.

  In this embodiment, the housing 1 has a shape including two curved surface portions 1a and two flat surface portions 1b. The housing 1 is combined with two semi-cylindrical auxiliary yokes 2 to form an outer yoke. For this reason, the surface of the outer yoke that faces the magnet 3 can be formed in a substantially circular shape. For this reason, as shown in FIG. 1 (c), the magnetic field lines are almost the same as the magnetic flux lines generated in the conventional coreless motor in which the outer yoke (housing 101) shown in FIG. 4 (c) is formed in a cylindrical shape. Can be generated.

  The cup-type coil 4 is rotatably disposed between the outer yoke (auxiliary yoke 2) and the magnet 3, and rotates integrally with the output shaft 11 disposed inside the magnet 3.

  The inner yoke 5 is disposed between the cup-type coil 4 and the output shaft 11 and is held by the housing 1 and a holding plate 7 fixed to the housing 1. Reference numeral 6 denotes two bearings, which rotatably hold the output shaft 11 (cup type coil 4). Reference numeral 10 denotes a commutator for supplying power to the coil 4, and reference numeral 8 denotes a brush holder. The brush holder 8 holds a terminal having a brush 9 that contacts the commutator 10.

  In the coreless motor configured as described above, power is supplied to the cup-type coil 4 through the terminals and the brush 9 and the commutator 10 held by the brush holder 8 in the magnetic circuit shown in FIG. Thus, the cup type coil 4 and the output shaft 11 rotate.

  The coreless motor is used as a drive source in various devices or as a vibrator in a portable device. FIG. 1A shows a case where a coreless motor mounted as a drive source in an apparatus including the driven member 40 drives the driven member 40 by the output (rotation) extracted from the output shaft 11. Yes.

  In this embodiment, the outer yoke is divided into the housing 1 and the auxiliary yoke 2 as described above. The thickness of the housing 1 including many parts that do not contribute to the magnetic circuit is set as thin as possible so as to obtain a thickness necessary for strength, while the auxiliary yoke 2 has a thickness larger than the thickness of the housing 1. In addition, the total thickness of the auxiliary yoke 2 and the housing 1 ensures the necessary thickness for the magnetic circuit. Thereby, compared with the past, the thickness of the part which does not contribute to a magnetic circuit can be reduced significantly, and the coreless motor can be effectively reduced in weight. Therefore, it is possible to further reduce the weight of the device equipped with the coreless motor.

  The auxiliary yoke 2 can be manufactured by cutting a magnetic material. However, when the inner surface and the outer surface of the auxiliary yoke 2 are concentric circular arc surfaces, the thickness is constant. Therefore, the auxiliary yoke 2 can be manufactured by pressing the sheet metal and cutting the sheet metal.

  In the present embodiment, the case where the housing 1 and the auxiliary yoke 2 are configured as separate members has been described. However, an integral member having a portion corresponding to the housing 1 and a portion corresponding to the auxiliary yoke 2 by sintering. It is also possible to produce an outer yoke. Also in this case, it can be said that the outer yoke is constituted by the housing and the auxiliary yoke.

  The configuration of the coreless motor that is Embodiment 2 of the present invention will be described with reference to FIGS. 2A shows a cross section when the coreless motor is cut along the axial direction, and FIG. 2B shows a cross section when the coreless motor is cut along the radial direction. FIG. 2C shows the magnetization direction of the magnet 3 and the magnetic circuit (lines of magnetic force) in a cross section along the axial direction. In the present embodiment, the same components as those in the first embodiment are denoted by the same reference numerals as those in the first embodiment, and the description is omitted.

  In this embodiment, the magnet 23 is formed in a cylindrical shape that is not hollow. Reference numeral 20 denotes a housing holder for holding the magnet 23 and fixing it to the housing 1. In this embodiment, the inner yoke 5 used in the first embodiment is not used.

  In the present embodiment, a bearing 26 a that rotatably holds the cup-type coil 4 is included in the magnet 23, and another bearing 26 b is installed in the brush holder 8. Thus, as shown in FIG. 2C, even if the magnet 23 is formed in a columnar shape, the outer yoke shown in FIG. 4C is cylindrical as in the first embodiment (FIG. 1C). It is possible to generate magnetic lines of force that are almost the same as magnetic flux lines generated in a conventional coreless motor formed into a shape.

  The configuration of a coreless motor that is Embodiment 3 of the present invention will be described with reference to FIG. FIG. 3 shows a cross section when the coreless motor is cut along the radial direction. In the present embodiment, the same components as those in the first embodiment are denoted by the same reference numerals as those in the first embodiment, and the description is omitted.

  In the present embodiment, a bent portion 1d which is bent in an arc shape so as to protrude inwardly is formed on two plane portions 31b of a housing 31 having basically the same shape as the housing 1 of the first embodiment. By forming the bent portion 1d, the auxiliary yoke 2 can be prevented from falling off the housing 1, and the surface of the outer yoke that faces the magnet 3 can be made more circular. For this reason, the magnetic flux density in the vicinity of the bending portion 1d is improved, leading to an increase in motor torque.

  In the above embodiment, the case where the number of poles of the magnet is two has been described, but the number of poles of the magnet may be four. As a fourth embodiment of the present invention, a coreless motor having four magnet poles will be described with reference to FIGS.

  FIG. 5A shows a cross section when the coreless motor is cut along the axial direction, and FIG. 5B shows a cross section when the coreless motor is cut along the radial direction.

  In these drawings, reference numeral 51 denotes a housing that constitutes a part of an outer yoke made of a magnetic material. The housing 51 has a shape for housing each member (magnet 53, cup-type coil 54, inner yoke 55, etc.) described later, and is different from each other orthogonal to the output shaft 61 as shown in FIG. And four curved surface portions 51a disposed on both sides of the output shaft 61 in each of the first two directions. The housing 51 has two different directions (orthogonal) orthogonal to the output shaft 61, and the output shaft 61 in each of the second two directions that are 45 ° out of phase with the first two directions. It has four flat portions 51b arranged on both sides of the sandwiched portion. By forming the housing 51 in such a shape, the coreless motor can be reduced in size compared to the case where the housing is formed in a cylindrical shape as shown in FIGS. 4 (a) and 4 (b). .

  An auxiliary yoke 52 constitutes another part of the outer yoke made of a magnetic material. In other words, in this embodiment, the outer yoke is constituted by the housing 51 and the auxiliary yoke 52 formed as a separate member from the housing 51.

  Each auxiliary yoke 52 is formed in a 1/4 cylindrical shape so as to have a thickness larger than the thickness of the housing 51 (particularly, the thickness of each curved surface portion 51 a and each flat surface portion 51 b). The inner surface is fixed so as to face the outer surface of a cup-shaped coil 54 described later. More specifically, as shown in FIG. 5B, the four auxiliary yokes 52 are disposed on both sides of the output shaft 61 in the first two directions, and each of the curved surfaces is a curved surface. The inner side (inner surface) of the portion 51a and the inner side (inner surface) of the four flat portions 51b are fixed to a region excluding the central region 51c where the cup-shaped coil 54 is close.

  The magnet 53 is formed in a cylindrical shape and is disposed inside the outer yoke (auxiliary yoke 52). FIG. 5C shows the magnetization direction of the magnet 53 and the magnetic circuit (lines of magnetic force) in a cross section orthogonal to the axial direction. The magnetizing direction of the magnet 53 is a direction orthogonal to each planar portion 51 b of the housing 51.

  In this embodiment, the housing 51 has a shape including four curved surface portions 51a and four flat surface portions 51b. The housing 51 is combined with four auxiliary yokes 52 having a 1/4 cylindrical shape to form an outer yoke. For this reason, the surface of the outer yoke that faces the magnet 53 can be formed in a substantially circular shape. For this reason, as shown in FIG. 5 (c), the magnetic field lines are not much different from the magnetic flux lines generated in the conventional coreless motor in which the outer yoke (housing 101) shown in FIG. 4 (c) is formed in a cylindrical shape. Can be generated.

  The cup-type coil 54 is rotatably disposed between the outer yoke (auxiliary yoke 52) and the magnet 53, and rotates integrally with the output shaft 61 disposed inside the magnet 53.

  The inner yoke 55 is disposed between the cup-shaped coil 54 and the output shaft 61 and is held by a housing 51 and a holding plate 57 fixed to the housing 51. Reference numeral 56 denotes two bearings, which rotatably hold the output shaft 61 (cup type coil 54). 60 is a commutator for supplying power to the coil 54, and 58 is a brush holder. The brush holder 58 holds a terminal provided with a brush 59 that contacts the commutator 60.

  In the coreless motor configured as described above, power is supplied to the cup-type coil 54 via the terminals and brush 59 held by the brush holder 58 and the commutator 60 in the magnetic circuit shown in FIG. Thus, the cup type coil 54 and the output shaft 61 rotate.

  The coreless motor is used as a drive source for a driven member in various devices (see FIG. 1A) or used as a vibrator in a portable device.

  In this embodiment, the outer yoke is divided into the housing 51 and the auxiliary yoke 52 as described above. The thickness of the housing 51 including many portions that do not contribute to the magnetic circuit is set as thin as possible so as to obtain a thickness necessary for strength, while the auxiliary yoke 52 has a thickness larger than the thickness of the housing 51. In addition, the total thickness of the auxiliary yoke 52 and the housing 51 ensures the necessary thickness for the magnetic circuit. Thereby, compared with the past, the thickness of the part which does not contribute to a magnetic circuit can be reduced significantly, and the coreless motor can be effectively reduced in weight. Therefore, it is possible to further reduce the weight of the device equipped with the coreless motor.

  The auxiliary yoke 52 can be manufactured by cutting a magnetic material. However, when the inner surface and the outer surface of the auxiliary yoke 52 are concentric circular arc surfaces, the thickness is constant, so that the sheet metal can be manufactured by pressing and cutting from the sheet metal.

  In the present embodiment, the case where the housing 51 and the auxiliary yoke 52 are configured as separate members has been described. However, an integral member having a portion corresponding to the housing 51 and a portion corresponding to the auxiliary yoke 52 by sintering. It is also possible to produce an outer yoke. Also in this case, it can be said that the outer yoke is constituted by the housing and the auxiliary yoke.

  Each embodiment described above is only a representative example, and various modifications and changes can be made to each embodiment in carrying out the present invention.

  A small and lightweight coreless motor can be provided.

1, 31, 51 Housing 2, 52 Auxiliary yoke 3, 23, 53 Magnet 4, 54 Coil 5, 55 Inner yoke 6, 26a, 26b, 56 Bearing 11, 61 Output shaft

Claims (6)

The outer yoke,
A magnet disposed inside the outer yoke;
A coreless motor having a cup-shaped coil that is rotatably arranged between the outer yoke and the magnet, and that rotates integrally with an output shaft disposed inside the magnet;
The outer yoke is
A housing for housing the magnet and the cup-shaped coil;
It is formed to have a thickness larger than the thickness of the housing, and is constituted by an auxiliary yoke provided inside the housing so as to face the magnet ,
The closest member to the auxiliary yoke inside than the auxiliary yoke, coreless motors, characterized in Oh Rukoto in the cup-shaped coil. The housing has two curved surface portions disposed on both sides of the output shaft in one of two different directions orthogonal to the output shaft, and on both sides of the output shaft in the other of the two directions. Two planar portions arranged,
Each of the two auxiliary yokes disposed on both sides of the output shaft excludes the inner region of each curved surface portion and the inner region of the two flat surface portions where the cup-shaped coil is close. The coreless motor according to claim 1, wherein the coreless motor is provided in a region. The housing includes four curved surface portions arranged on both sides of the output shaft in each of the first two different directions orthogonal to the output shaft, and two different directions orthogonal to the output shaft. Four plane portions arranged on both sides sandwiching the output shaft in each of the second two directions different in phase from the first two directions,
Each of the four auxiliary yokes disposed on both sides of the output shaft in each of the first two directions is an inner region of each curved surface portion and an inner side of the four flat surface portions , and the cup The coreless motor according to claim 1, wherein the mold coil is provided in an area excluding an adjacent area. 4. The coreless motor according to claim 2 , wherein a magnetizing direction of the magnet is a direction orthogonal to the flat portions of the housing. 5.   The coreless motor according to any one of claims 1 to 4, wherein the auxiliary yoke is formed as a separate member from the housing and is fixed to an inner surface of the housing. An apparatus comprising the coreless motor according to any one of claims 1 to 5 .