JP2012005222A - Coreless motor, coreless vibrating motor, and mobile terminal device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a coreless motor that prevents reduction in density of a magnetic flux acting on a coil body even when the height of the coreless motor fixed to a substrate is small, and to provide a coreless vibrating motor and a mobile terminal device.SOLUTION: A coreless motor 3 according to the invention includes: a cylindrical coil body 11 that rotates integrally with a rotating shaft 5; and a cylindrical magnet 15 that is provided between the coil body 11 and the rotating shaft 5 and has circumferentially arranged magnetic poles. A housing 9 has a flat surface portion 27 on an outer peripheral surface and a cylindrical inner peripheral surface. In the magnet 15, regions 39 with a highest magnetic flux density are arranged so as to face portions of the housing 9 excluding the flat surface portion 27. A wall thickness M2 of the flat surface portion 27 of the housing 9 is smaller than a wall thickness M1 of each of portions 25a and 25b which the regions 39 with the highest magnetic flux density respectively face.

Description

  The present invention relates to a coreless motor, and relates to a coreless motor having a magnet as a stator, a coreless vibration motor, and a mobile terminal device.

In general, in a coreless motor used for a coreless vibration motor, a cylindrical coil body arranged in a housing is fixed to a rotating shaft as a rotor, and a cylindrical magnet is arranged as a stator on the inner peripheral side of the coil body. The housing is made of a magnetic material and functions as a yoke for the magnet.
On the other hand, a coreless vibration motor mounted on a cellular phone or the like is mainly a cylindrical motor with a cylindrical outer peripheral surface of the housing, and when it is fixed to the substrate, it does not sit as it is, so it is fixed to the substrate via a bracket. It was.
On the other hand, Patent Document 1 discloses that the outer peripheral surface of the motor housing has a substantially rectangular tube shape, and the flat portion of the outer peripheral surface is placed on the substrate to improve the sitting and is fixed by reflow or the like. Has been.

JP 2006-304491 A

However, in the technique of Patent Document 1, the substantially rectangular tube-shaped housing is formed of a plate material having a constant thickness. Therefore, if the rectangular tube-shaped housing is used instead of the cylindrical magnet, the cylindrical magnet is used. Since the distance to the corner of the housing is far, the magnetic flux density acting on the coil body is low and the torque is small.
Further, when the cylindrical coreless vibration motor is fixed to the substrate, there is a disadvantage that the height is increased by the amount of the bracket.

  Therefore, an object of the present invention is to provide a coreless motor, a coreless vibration motor, and a mobile terminal device that can prevent a decrease in magnetic flux density acting on a coil body even when the height when fixed to a substrate is small.

  The invention according to claim 1 is a cylindrical magnetic housing, a rotary shaft provided on the inner periphery of the housing, and a cylindrical shape fixed to the rotary shaft on the inner peripheral side of the housing and rotating integrally with the rotary shaft. A coil body, and a cylindrical magnet provided between the coil body and the rotating shaft and having different magnetic poles in the circumferential direction, the housing has a flat portion on the outer peripheral surface and the inner peripheral surface is cylindrical, The magnet has a region where the magnetic flux density is highest facing the portion excluding the flat portion of the housing, and the thickness of the flat portion of the housing is the thickness of the portion where the magnetic flux density region of the magnet is facing. It is characterized by being made thinner.

  According to a second aspect of the present invention, in the first aspect of the invention, the housing has an outer peripheral surface having a substantially rectangular tube shape, and the thickness of the flat portion is made thinner than the thickness of the corner portion. Features.

  According to a third aspect of the present invention, in the second aspect of the present invention, the magnet has a region where the magnetic flux density in the circumferential direction is the highest in each of the magnetic poles of the N pole and the S pole, and is opposed to the corner of the housing. It is characterized by being.

  According to a fourth aspect of the present invention, in the third aspect of the present invention, the outer peripheral surface of the housing is characterized in that corners are circular arcs.

  The invention according to claim 5 is the coreless vibration motor according to any one of claims 1 to 3, wherein an eccentric weight is attached to the tip of the rotating shaft.

According to a sixth aspect of the present invention, there is provided a mobile terminal device including the coreless vibration motor according to the fifth aspect.
The mobile terminal device refers to a mobile phone, a personal digital assistant (PDA), a notebook computer, and the like.

  According to the first aspect of the present invention, since the flat portion is provided on the outer peripheral surface of the housing, when the flat portion of the outer peripheral surface of the housing is fixed to the flat surface of the substrate or the like, the sitting is good and when fixing to the substrate or the like The brackets used in the past can be eliminated. Therefore, the height when the coreless motor is fixed to the substrate can be reduced.

  Further, the inner peripheral surface of the housing is cylindrical, and the distance to the cylindrical coil body between the outer peripheral surface of the cylindrical magnet and the inner peripheral surface of the housing can be reduced to a minimum, and the magnet The distance between the outer peripheral surface and the inner peripheral surface of the housing can be made substantially constant. For this reason, since it is possible to prevent a decrease in magnetic flux density acting on the coil body, a decrease in torque and torque spots acting on the coil body can be reduced.

  Since the thickness of the flat portion of the outer peripheral surface of the housing is made thinner than the thickness of the region where the magnetic flux density of the magnet is the highest, the height of the coreless motor can be reduced when the flat portion is fixed to the substrate. . Furthermore, even if the thickness of the flat surface portion on the outer peripheral surface of the housing is reduced, the region where the magnetic flux density of the magnet is the highest is opposed to the portion excluding the flat surface portion, so that a decrease in the magnetic flux density acting on the coil body can be prevented. .

  According to the second aspect of the present invention, the housing has the function and effect of the first aspect, and the housing is provided with four flat surfaces, so that any of the four surfaces can be fixed to the substrate, and the degree of freedom of installation. In addition, the height of the coreless motor when the flat portion is fixed to the substrate can be further reduced.

  According to the third aspect of the present invention, the region having the highest magnetic flux density in the magnetic pole is generally the central part of the magnetic pole, so that the central part of the magnet in the circumferential direction is provided. Assembly can be facilitated by matching the corners of the housing.

  According to the fourth aspect of the present invention, the effects described in the third aspect can be achieved, the outer peripheral surface is made circular at the corner of the housing, and the thickness can be made substantially constant at the arc portion. Therefore, the magnetic flux density at the corners can be made substantially uniform over the arc region, and torque spots can be reduced.

  According to invention of Claim 5, the coreless vibration motor which has the effect as described in any one of Claims 1-4 can be provided.

  According to the invention described in claim 6, it is possible to provide a mobile terminal device having the function and effect described in claim 5.

It is a longitudinal cross-sectional view of the motor main body of the coreless vibration motor concerning 1st Embodiment. It is AA sectional drawing of FIG. It is BB sectional drawing of FIG. It is the perspective view which looked at the housing of the coreless vibration motor concerning a 1st embodiment from the bottom side. It is a perspective view of the coreless vibration motor concerning a 1st embodiment. It is a longitudinal cross-sectional view of the motor main body of the coreless vibration motor concerning 2nd Embodiment. It is the schematic which extracts and shows a housing and a magnet in the longitudinal cross-section of the motor main body of the coreless vibration motor concerning 3rd Embodiment.

  Hereinafter, a first embodiment of the present invention will be described in detail with reference to FIGS. A coreless vibration motor 1 according to the present embodiment is a vibration motor that is fixed to a substrate of a mobile phone. As shown in FIGS. 2 and 3, an eccentric weight 7 is fixed to the tip of a rotating shaft 5 of the coreless motor 3. Has been.

  1 to 3, the coreless motor 3 includes a housing 9, a rotating shaft 5, a coil body 11 fixed to the rotating shaft 5, and a magnet holder 13 attached to the housing 9 as shown in FIG. And a magnet 15 fixed thereto.

As shown in FIGS. 2 and 3, the housing 9 is composed of a main body portion 17 and a head portion 19 continuous to the main body portion 17, and a bottom opening 21 of the main body portion 17 is formed in the bottom opening 21 of the main body portion 17. The bottom cap 23 is fitted and fixed.
The housing 9 is integrally formed by press molding, and as shown in FIGS. 1 and 4, the outer peripheral surface 9 a of the main body portion 17 has a quadrangular cylindrical shape, and the inner peripheral surface 9 b has a cylindrical shape.

In the main body portion 17 of the housing 9, the thickness M2 of the flat portion 27 shown in FIG. 2 is thinner than the thickness M1 of each corner portion 25a, 25b shown in FIG. In the first embodiment, the outer peripheral surfaces of the corner portions 25a and 25b are chamfered.
The head portion 19 of the housing 9 has a cylindrical shape with substantially the same thickness and is narrower in diameter than the main body portion 17.
A bearing 29 and a magnet holder 13 are provided on the inner peripheral side of the head portion 19, and the bearing 29 and the magnet holder 13 are fixed to the head portion 19.

  The coil body 11 has a cylindrical shape and is rotatably provided between the magnet 15 and the main body portion 17 of the housing 9.

  The magnet 15 has a cylindrical shape. As shown in FIG. 1, in this embodiment, the magnet 15 is magnetized in two poles with one N pole and one S pole in the circumferential direction. The magnetic pole boundary 31, 31 between the N pole and the S pole is located at the circumferential center position T of the corner 25a, and is the central portion of the magnetic flux that is the highest magnetic flux density region between the N pole and the S pole. 39 is located at the corner 25b. In general, the central portion 39 of the magnetic flux is located farthest from the magnetic pole boundaries 31 and 31 between the N pole and the S pole, and is positioned at the approximate center between the magnetic flux boundaries 31 and 31 in the circumferential direction.

  As shown in FIGS. 2 and 3, the bottom cap 23 rotatably supports the rear end of the rotating shaft 5, and is provided with a brush 35 that presses against the commutator 33 of the coil body 11. Is connected to a power supply terminal 37 shown in FIG.

Next, the effect of the coreless motor 3 in the coreless vibration motor 1 according to the embodiment of the present invention will be described.
According to the present embodiment, since the outer peripheral surface of the main body portion 17 of the housing 9 has a substantially rectangular tube shape, the flat portion 27 of the main body portion 17 is mounted on the substrate when it is fixed to the substrate (not shown). Because it can be placed and fixed, it is easy to sit on, and can be glued or soldered (reflowed) as it is, eliminating the need for brackets that have been used in the past.

Further, the inner peripheral surface 9b of the housing 9 is cylindrical, and the interval with respect to the cylindrical coil body 11 between the outer peripheral surface of the cylindrical magnet 15 and the inner peripheral surface 9b of the housing 9 is minimized. The distance between the outer peripheral surface 15a of the magnet 15 and the inner peripheral surface 9b of the housing 9 can be made constant. Therefore, a decrease in magnetic flux density acting on the coil body 11 can be prevented and uniform, and a decrease in torque and torque spots acting on the coil body 11 can be reduced.
By making the thickness of the flat portion 27 of the housing 9 thinner than the corner portions 25a and 25b, the height of the motor main body portion 17 when the flat portion 27 is attached to the substrate can be reduced.

In the case of a two-pole magnet, the central portion 39 of the magnetic pole, which is the region where the magnetic flux density of each of the N-pole and S-pole is the highest, is disposed so as to face the corner portion 25b that is thicker than the flat portion 27. Therefore, even if the thickness of the flat portion 27 of the housing 9 is reduced to reduce the mounting height to the substrate, the magnetic flux density acting on the coil body 11 disposed between the housing 9 and the magnet 15 is reduced. Can be prevented.
In other words, the magnetic flux density of the magnet 15 is smaller at the magnetic pole boundary 31, and the magnetic flux density is higher at the magnetic pole center portion 39 located farthest from the magnetic pole boundary 31. Therefore, in the case of a two-pole magnet, the magnetic pole central portion 39 in the circumferential direction of the N-pole and the S-pole is positioned to face the corner 25b of the housing 9 as shown by the broken line in FIG. Thus, the portion having a high magnetic flux density can be disposed in the thick corner 25b of the housing 9. Therefore, even if the thickness of the flat portion 27 is thin, the decrease in the magnetic flux density acting on the coil body 11 can be prevented, so that the decrease in torque and the torque spots of the coreless motor 3 can be reduced.
Further, since the housing 9 is provided with the flat portion 27 on four sides, any of the four sides can be fixed to the substrate, and the height of the coreless motor 3 when the flat portion 27 is fixed to the substrate is high. Can be further reduced.
Since the region having the highest magnetic flux density in the magnetic pole is generally the central portion, it can be easily assembled by aligning the central portion of the magnet in the circumferential direction with the corner portion 25 b of the housing 9.

Other embodiments of the present invention will be described below. In the embodiment described below, parts having the same operational effects as those of the first embodiment described above are denoted by the same reference numerals, and the description thereof is omitted. In the following description, the first embodiment is omitted. Differences from the embodiment will be mainly described.
In the second embodiment, as shown in FIG. 6, the corners 25a and 25b of the housing 9 each have an arcuate outer periphery, and the thickness M1 of the corners 25a and 25b is set in the region of the corners 25a and 25b. It is almost constant. Also in this second embodiment, the thickness M2 of the flat portion 27 is thinner than the thickness M1 of each corner portion 25a, 25b, and M2 is at least half the dimension of M1.

  According to the second embodiment, the outer peripheral surfaces of the corner portions 25a and 25b of the housing 9 are circular, and the thickness M1 can be made substantially constant at the arc portion. Therefore, the magnetic flux density in the corners 25a and 25b can be made substantially uniform over the arc region of the corners, and torque spots can be reduced.

  A third embodiment of the present invention will be described with reference to FIG. FIG. 7 shows the shape and arrangement relationship between the housing 9 and the magnet 15.

  In this third embodiment, the magnet 15 has four north poles and two south poles, and the central portion 39 of each magnetic pole in the circumferential direction is located at each corner 25a, 25b. . In addition, the boundary 31 of each magnetic pole exists in the position facing the substantially intermediate position P between each corner | angular part 25a, 25b.

  In the third embodiment, in the four-pole magnet 15, the central portion 39 of the magnetic pole having a high magnetic flux density is positioned so as to face the corner portions 25 a and 25 b of the housing 9. Therefore, a decrease in torque and torque spots of the coreless motor 3 can be reduced.

The present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the scope of the present invention. For example, the outer peripheral surface 9a of the housing 9 is not limited to a quadrangular cross section orthogonal to the rotation axis 5, but may be a part of a circle made flat or a part of an ellipse made flat. That is, the plane part 27 may be one surface or two surfaces parallel to each other.
In the third embodiment, the corners 25a and 25b may be arcuate as in the second embodiment.

DESCRIPTION OF SYMBOLS 1 Coreless vibration motor 3 Coreless motor 5 Rotating shaft 7 Eccentric weight 9 Housing 11 Coil body 15 Magnet 25a, 25b Corner | angular part 27 Flat part 39 Center part of magnetic pole M1 Thickness of corner | angular part M2 Thickness between corner | angular part T Center position P Nearly intermediate position between corners G Magnetic flux

Claims (6)

  A cylindrical magnetic body housing, a rotary shaft provided on the inner periphery of the housing, a cylindrical coil body fixed to the rotary shaft on the inner peripheral side of the housing and rotating integrally with the rotary shaft, the coil body and the rotary shaft And a cylindrical magnet having different magnetic poles in the circumferential direction, the housing has a flat portion on the outer peripheral surface and the inner peripheral surface is cylindrical, and the magnet has a region with the highest magnetic flux density. It is arranged to face the part excluding the flat part of the housing, and the thickness of the flat part of the housing is thinner than the thickness of the part where the highest magnetic flux density of the magnet is facing. Coreless motor.   2. The coreless motor according to claim 1, wherein the housing has a substantially rectangular tube shape on an outer peripheral surface, and a thickness of the flat portion is made thinner than a thickness of the corner portion.   The coreless motor according to claim 2, wherein the magnet has a region where the magnetic flux density in the circumferential direction is the highest in each of the magnetic poles of the N pole and the S pole, and is opposed to the corner portion of the housing.   The coreless motor according to claim 3, wherein the outer peripheral surface of the housing has an arcuate corner.   The coreless vibration motor according to any one of claims 1 to 4, wherein an eccentric weight is attached to a tip of the rotating shaft.   A mobile terminal apparatus, comprising the coreless vibration motor according to claim 5.

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