JP3894368B2 - Motor armature, axial gap motor with the same armature - Google Patents

Description

  The present invention relates to an armature for a motor that is suitable for use as a silent notification means of a mobile communication device and the like, and relates to an axial gap type motor provided with the armature.

Armatures used for motor armatures, especially thin axial gap type motors used for silence notification means of mobile communication devices, etc., both brushless and coreless types are extremely thin with a thickness of 0.8 mm or less. In many cases, the armature itself is integrally molded with a resin so that it can withstand such impacts, that is, the armature coil is integrally molded with a printed wiring board together with a resin to obtain strength.
Moreover, as the armature, regardless of the rotor or stator, the smaller the armature, the more the gap loss must be avoided, and as much as possible, one surface of the armature coil is exposed without being covered with resin. Yes.
As a stator of a brushless motor constituting such an armature, a drive circuit in place of a commutator is an indispensable requirement, but none of the conventional structures has a built-in drive circuit. There is a problem that more terminals are required and it cannot be handled like a normal two-terminal DC motor.
Moreover, in a normal brushless motor, the stator has a plurality of armature coils arranged uniformly around the entire circumference, and the drive circuit device also requires other electronic components such as an IC. So it couldn't be built in.
As a flat axial gap type brushless vibration motor, the present applicant has previously proposed a coreless slotless type motor that does not incorporate a drive circuit member. (See Patent Document 1 and Patent Document 2) The brushless vibration motor with a drive circuit is a cored type, and a drive circuit member is a cored type in which armature coils are wound around a plurality of salient poles arranged equally. A non-circular one arranged on the side of the stator is known. (See Patent Document 3)
However, such a product has a large size in the lateral direction, and the set is not mounted on the printed wiring board with the SMD method, and the cored type has a large thickness. There is no.
Therefore, the applicant of the present invention previously includes a cored, slotless coreless type, a part of a plurality of armature coils is deleted, a space is provided, and a drive circuit member is disposed in this space. is suggesting. (See Patent Document 4)
Further, when such a vibration motor is mounted on a mobile communication device such as a cellular phone, the size is extremely thin and the size reduction is required, and the shaft constituting the eccentric rotor must be 0.6 mm or less. Therefore, it is necessary to give sufficient consideration to impact resistance.
Further, in order to realize a reduction in thickness, the axial gap type brushless needs to be a coreless slotless type. However, unless the magnetic force of the magnet is controlled, a loss that is attracted to the stator side is large and startup is difficult. In particular, when the diameter is driven to about 10 mm, the starting torque decreases, and in an eccentric rotor with an eccentric weight, the minimum starting torque includes the torque that increases the weight of the weight when the axial direction is horizontal. It is necessary to consider.

In addition, a brushless motor with a built-in drive circuit usually has a stator in which a single hall sensor and a drive integrated circuit member (IC) are housed between axial air-core armature coils connected in a single phase. Adopted from the size. Since the single-phase brushless motor cannot be started unless the stop position is a specific position, detent torque generating means for specifying the position of the magnetic pole of the magnet to be combined is required.
In the axial gap type slotless type, unless this detent torque is controlled, there is a problem that the holding force by the magnet becomes relatively large with respect to the starting torque and it is difficult to start unless the starting voltage is raised. Furthermore, if there is a Hall sensor on this detent torque generating member, it is better to stop so that the magnetic pole of this magnet comes to this part, but if it stops so that the neutral part comes, there will be no sensor output and it will be impossible to start Become.
When the air gap between the magnet and the detent torque generating member is reduced, the effective magnetic flux density in the air gap increases, and the neutral part in addition to the center of the magnetic pole is affected by the adjacent N and S poles to generate detent torque. It tends to stop on the member.
In addition, it is desirable that such a stator is integrally molded with resin so that each member can serve as a skeleton so that it can withstand impacts such as dropping, and the axial gap type armature coil has a gap loss. Is molded so that the air gap surface is exposed.

  On the other hand, the armature configured as a coreless rotor is also placed on a commutator made of a printed wiring board and integrally molded with resin. One surface of the child coil is exposed.

As such an armature, the armature coil itself becomes small regardless of the rotor or the stator. Therefore, it is difficult to connect the winding start terminal at the inner diameter of the coil, and the coil end is linked to the coil side. Thus, it must be derived from between the printed wiring boards.
When pressing with an injection mold so that one surface of the armature coil is exposed, the winding start terminal is crushed by the coil side, and problems such as short circuit and disconnection occur.

As a means for preventing problems such as short circuit and disconnection of the coil terminal, the rotor is connected to the metal frame through the terminal in a recess provided below the coil side of the metal frame on which the air-core coil is mounted. There is something. (See Patent Document 5)
However, this product is not molded with resin and has a metal frame, so it cannot be expected to be thin.
Japanese Utility Model Publication No. 4-137463 JP 2002-143767 A JP 2000-245103 A JP 2002-142427 A JP-A-9-322503

Further, when such a vibration motor is mounted on a mobile communication device such as a cellular phone, the size is extremely thin and the size reduction is required, and the shaft constituting the eccentric rotor must be 0.6 mm or less. Therefore, it is necessary to give sufficient consideration to impact resistance.
Further, in order to realize a reduction in thickness, the axial gap type brushless needs to be a coreless slotless type. However, unless the magnetic force of the magnet is controlled, a loss that is attracted to the stator side is large and startup is difficult. In particular, when the diameter is driven to about 10 mm, the starting torque decreases, and in an eccentric rotor with an eccentric weight, the minimum starting torque includes the torque that increases the weight of the weight when the axial direction is horizontal. It is necessary to consider.

  Further, it is desirable that such a stator is integrally molded with a resin so that each member can serve as a skeleton so that it can withstand an impact such as dropping. The axial gap-type armature coil is molded so that the gap surface is exposed in order to minimize gap loss.

  On the other hand, the armature configured as a coreless rotor is also placed on a commutator made of a printed wiring board and integrally molded with resin. One surface of the child coil is exposed.

In such an armature, the armature coil itself is small regardless of the rotor or the stator. Therefore, it is difficult to connect the winding start terminal at the inner diameter of the coil, and the coil side is linked to the coil side. As such, it must be led out from between the printed wiring boards.
When pressing with an injection mold so that one surface of the armature coil is exposed, the winding start terminal is crushed by the coil side, and problems such as short circuit and disconnection occur.
The object of the present invention is to prevent problems such as short-circuiting and disconnection with a simple configuration when processing the winding start terminal of the armature coil, and to obtain a strong stator and rotor so that these armatures can be obtained. In combination, it realizes an extremely thin configuration of the axial gap motor.

In order to solve the above problem, as shown in claim 1, a plurality of axial gap air-core armature coils,
First the surface in plan view has an area for mounting at least a portion of the axial air gap-type air-core armature coil plane, printed circuit board, wherein the axial gap-type air-core armature coil in this region is placed Doo is provided further terminal lead through-section transverse to the portion of the sides of the axial gap-type air-core armature coils with in this printed wiring board wherein the first surface to the terminal connection lands are formed in which is provided, through the winding start terminal is the terminal derivation through portion of the inner diameter side of the axial air gap-type air-core armature coils, connected to the terminal connection lands are again guided to the first surface And
Can be achieved in that one side of the axial air gap-type armature coil is integrally together with the printed wiring board with the resin to be exposed.
Specifically, as in the invention described in claim 2, the printed wiring board is formed as a stator base (3) made of a flexible substrate, and the terminal lead-out through portion is formed by a through hole (1h). is a feature to be used for the brushless motor in those additionally provided to one of the drive circuits member driven by the output of the Hall sensor (H) (D) and is mounted yoke bracket (1) good to you.
As another specific means, as in the invention shown in claim 3, the yoke bracket (1) is formed of magnetic stainless steel having a thickness of 0.2 mm or less, and a shaft support portion (1a) provided at the center. And a plurality of support portions (1b) protruding in a radial direction integrally from the shaft support portion, and a ring-shaped holding portion (1c) in which the tips of these support portions are integrally closed, Is preferably an integral multiple of the magnetic pole opening angle of the magnet to be combined in a plan view, and at least a part of the Hall sensor constituting the drive circuit member is superimposed on the support in a plan view. .
In order to make a brushless motor using such a motor armature, the motor armature according to any one of claims 1 to 3 and a gap are provided as in the invention shown in claim 4. A rotor desired by the armature via an axial gap, the rotor comprising an axial gap type magnet having a plurality of magnetic poles, an eccentric weight arranged outside the magnet, and a front magnet A thin yoke plate that receives a magnetic field is provided, and this thin yoke plate has a flat part that serves as a return path for the magnet and an inner diameter part that supports the shaft, and is provided with a cover that covers the rotor and features a brushless type. Can be achieved.

On the other hand, in order to make a coreless rotor as an armature, as shown in claim 5, the printed wiring board (11, 111) has at least a part of the terminal lead-out through portion (55a, 55b, 11a, 111a) as the shaft. A commutator (SC) comprising a plurality of commutator segments is arranged on the second surface and concentrically with the center of rotation on the inner diameter of the directional air gap type armature coil (55A, 55B, 555). 11b and 111b) are formed so as not to overlap with the axial gap type air-core armature coil and can be achieved by being used for a coreless type motor .
In order to apply such an armature to a vibration motor, as shown in claim 6, it is disposed on the opposite side of the axial gap type air-core armature coil via a rotation center, and is used as an axial retaining means. and the eccentric weight of the specific gravity of more than 15 made of tungsten alloy is provided, the printed wiring board, the shaft is integral with a direction gap type coreless armature coil gravity 2 in the following resins, the one to the center of rotation This can be achieved with a sintered oil-impregnated bearing .
In order to make the motor thinner, as shown in claim 7 , the motor armature according to claim 5 or 6 and the motor armature are housed therein, each having a thickness of 0.2 mm or less. A housing comprising a case and a bracket, and a shaft for supporting the armature is at least one end fixed to the bracket, and a brush base (33) attached to the bracket around the shaft is a flexible substrate. the thickness including the adhesive layer is composed of the following 0.18 mm, further the bracket hole across a part of the portion Ma Gunetto is arranged (13a) is provided in said through this hole This can be achieved by a part of the brush base being led out as a feeding electrode on the side of the housing.

According to the first aspect of the present invention, even if the air-core armature coil has a small inner diameter, the terminal lead-out penetrating portion can easily process the terminal without problems such as crushing disconnection or short-circuiting, and includes the printed wiring board. Therefore strength be integrated with the resin may be configured.
According to the second and third aspects of the invention, the armature stator is suitable for use in a thin brushless motor.
According to the invention of claim 4, a thin brushless motor that is both a fixed shaft type and a shaft rotating type can be easily obtained by a combined rotor.
According to the fifth aspect of the invention, the present invention can be applied to a normal rotation type coreless armature.
According to the sixth aspect of the present invention, since the printed wiring board can be made small, the number of connection increases, which is suitable for use in a coreless motor that is advantageous in terms of cost .
According to the seventh aspect of the present invention, the thickness of the brush base can be ignored when the brush base is led out to the side of the housing, and an extremely thin axial gap type coreless motor can be obtained.

  A resin-molded armature, which is used to process the winding end of an axial gap type air-core armature coil placed on a printed wiring board, uses the penetration part to prevent problems such as disconnection and short circuit. .

FIG. 1 is a plan view showing a stator side of a brassless motor using a stator which is a motor armature of the present invention. (Example 1)
FIG. 2 is a longitudinal sectional view of a shaft-fixed axial gap type 1-hole sensor type coreless slotless brushless motor storing the stator of FIG.
FIG. 3 is a plan view showing a rotor side of a coreless motor using a rotor which is a motor armature of the present invention. (Example 2)
FIG. 4 is a longitudinal sectional view of a shaft rotation type axial gap type coreless vibration motor storing the rotor of FIG.
FIG. 5 is a plan view of an armature applied to a normal rotary axial gap type coreless motor. Example 3

1 and 2, the yoke bracket 1 is a stainless steel plate having a weaker magnetic property than an iron plate and is thin with a thickness of 0.1 mm to 0.2 mm, and has a shaft support portion 1a protruding in a burring shape at the center. The support portion 1b that functions to generate detent torque composed of a magnetic material that receives magnetic fields of three axial field magnets described later, which are integrally extended from the shaft support portion 1a at an opening angle of about 120 degrees in the radial direction. Further, this support portion is further extended in the radial direction from 1b, and has a ring-shaped holding portion 1c that closes the tip of the support portion, and a part of this holding portion is further protruded in the radial direction to mount the power supply terminal. It is a placement part 1d. The yoke bracket 1 constitutes a non-magnetic space 1e between the support portions 1b in order to stop magnetic poles of an axial field magnet described later at a specific position. In the figure, reference numeral 1f is an attachment leg protruding further outward from the holding portion 1c so that reflow soldering can be directly performed on a printed wiring board on the device side.
On the upper surface of the yoke bracket 1 configured in this manner, a thin shaft 2 of about 0.5 mm to 0.6 mm is press-fitted into the shaft support portion 1a at the base end, and a flexible printed wiring board stator is disposed around the shaft 2. A base 3 is placed. Here, when the strength cannot be ensured only by press-fitting, it is preferable to perform laser welding Y from the outside.
On the stator base 3, two winding type air-core armature coils 5A and 5B having a small inner diameter are placed facing each other and connected in series so as to be a single phase. Since the winding start terminals of the axial gap type air-core armature coil are each led out across the coil side, an elongated through hole 1h is provided as a through portion for leading out the terminal. Solder connected to a terminal connection land provided on the printed wiring board 1.
Between these winding type air-core armature coils 5A and 5B, a drive circuit device comprising a single hall sensor H and a drive circuit member D formed as an IC is disposed on the stator base.
Here, the Hall sensor H is arranged so that a part of the Hall sensor H is on the support portion 1b in a plan view, and the drive circuit member D is positioned in the space 1e in the plan view.
The positional relationship between the support 1b as the detent torque generating member and the single-phase air-core armature coil is set so that the effective conductor portion of the air-core armature coil is set according to the magnetic pole of the magnet described later and is stopped by the magnetic force of the magnet. It is preferable that the minimum starting torque is obtained in the posture.
The stator composed of each of these stator members can be made thin because the air-core armature coil or the like does not overlap in plan view.
Here, the position where the drive circuit member of the stator base 3 is placed is set not in the support portion 1b which is a detent torque generating member but in the space 1e, so that the stator base 3 made of a flexible printed wiring board is in this space. Since it is bent into 1e, the thickness of the stator base 3 in this portion can be ignored.
The yoke bracket 1 configured as described above is integrally formed with the resin 4 together with other stator members so that the surface of the air-core armature coil is exposed. Therefore, even if the yoke bracket 1 is thin, each of the integrated members serves as a skeleton, the strength is reinforced by the interaction, and the entire stator can be reinforced.
The terminal of the air-core electric coil is stored in the thickness of the flexible base and led out again by the through-hole 1h, so that it is protected from the injection mold.
That is, in this way, it is possible to prevent a short circuit, disconnection, or the like between the coil winding start terminal and the coil side due to the pressing of the injection mold.

The rotor combined with such a yoke bracket is composed of an eccentric rotor R as shown in FIG. 2, and a rare earth magnet powder is made of polyamide resin on a thin yoke plate 6 which is a member constituting the eccentric rotor R. An axial gap type resin magnet 8 that is integrated with is attached. The thin yoke plate 6 has a flat portion 6h that receives the magnetic field of the axial gap type resin magnet 8, and an outer diameter side hanging portion 6a and an inner diameter side hanging portion 6b that are integral with the flat portion 6h. Since the air gap type resin magnet 8 is surrounded, the magnet 8 has a strong adhesive force. The outer diameter side hanging portion 6a for fixing the arc-shaped eccentric weight 9 has two tongue pieces 6c. The flange 6d protrudes horizontally outward in the normal direction integrally with the outer diameter side drooping portion 6a, and protrudes inward from the inner diameter side drooping portion 6b. The recess 9a is formed in the tongue piece 6c. And an eccentric weight 9 is arranged, and a flanged sintered oil-impregnated bearing 7 is attached to the inner diameter side flange 6d as the metal member by caulking L2.
In this way, the arc-shaped eccentric weight 9 is fixed to the recess 9a and the tongue piece 6c by brazing or bonding, and when the magnet is a bonded or rare earth-sintering metal magnet, 2 is attached to the tongue piece 6c. By attaching by spot welding or the like, the eccentric rotor R can be easily configured.

The eccentric rotor R is rotatably mounted on the shaft 2 that has been press-fitted into the center shaft support portion of the yoke bracket 1 and laser-welded Y. At the time of storage, at least in order to reduce brake loss. It is rotatably mounted on the shaft 2 via a thrust washer S1 laminated on two sheets. Thereafter, a shallow cap-shaped cover member 10 made of a thin nonmagnetic stainless material is covered, and the tip of the shaft is fitted into a shaft mounting hole 10a formed in the center of the cover member 10 via a thrust washer S2. Here, the tip of the shaft mounting hole 10a is further narrower than the shaft diameter so that the tip of the shaft 2 does not protrude, and this tip portion is provided with a laser on the cover member 10 to prevent deformation upon impact. In addition to spot welding Y, the opening edge of the cover member 10 is assembled to the holding portion 1c of the yoke bracket 1 by laser spot welding Y.
Therefore, since the monocoque structure is assembled by welding as described above, sufficient strength can be obtained even if a thin member is used.
By storing a stator made up of wound type air-core armature coils 5A, 5B, a hall sensor H, a drive circuit member D, and the like provided on the stator base 3 in the cover member 10, the feed terminal mounting portion 1d is provided outside the motor. Since it is only necessary to derive a pair of power supply terminals from, the brushless motor can be handled in the same manner as a normal motor.
If the cover member 10 is made of nonmagnetic austenitic stainless steel, it has a heat insulating effect and can withstand reflow.

3 and 4 show a motor armature configuration applied to a rotor and its motor configuration. The printed wiring board 11 has a mounting area for an axial gap type armature coil on the first surface side. Is slightly smaller, that is, a part of the outer diameter is applied to the inner diameter of the axial gap type armature coils 55A and 55B, and the outer diameter of the printed wiring board 11 is used as the terminal lead-out through portions 55a and 55b. The arrangement of the axial gap type armature coils 55A and 55B is decentered at an opening angle of 170 degrees and placed on the first surface side. Printed circuit board 11, with the shaft insertion hole 11a is provided in the rotational center, the commutator S C comprising a plurality of commutator segments around the shaft insertion hole in the second surface is formed, the terminal connection lands 11b Is formed on the narrower 170 degree side so as not to overlap the air-core armature coils 55A, 55B. A winding start terminal of the axial gap type armature coil is led out to the second surface side through the penetrating portion, and soldered to the terminal connection land on the first surface side again through the outer diameter of the printed wiring board 11. Connected.
The printed wiring board 11 has a non-circular butterfly shape in which the wider side opposite to the air-core armature coil is removed through a rotation center, and a shaft with a specific gravity of 15 or more is formed in the removed portion. An eccentric weight 99 made of tungsten alloy provided with first and second step portions 9a and 9b is arranged as a direction slip-off preventing means, and is made of resin 44 having a specific gravity of 2 or less together with the printed wiring board and the axial air-core armature coil. It is an integrated unit, and one sintered oil-impregnated bearing 77 is provided at the center of rotation.
If it does in this way, since the winding start terminal of air-core armature coils 55A and 55B will be protected from an injection mold by a penetration part, the problem of a disconnection and a short circuit can be avoided.
The rotor R1 thus configured is rotatably mounted on the shaft 22 whose base end is press-fitted and fixed to the bracket 13 via the sintered oil-impregnated bearing 77, and is stored in the case 12.
Such eccentric rotor R1 is field by the axial air gap-type magnet 88 disposed in the bracket 13, a pair of brushes B arranged on the brush base 33 by the inner diameter portion of the magnet, the commutator S C by B It is supposed to receive power through.
The bracket is provided with a through hole 13a in a portion where the magnet 88 is placed, and a part of the brush base is led out sideways through the through hole as a feeding electrode.
The thickness of the brush base can be ignored by this through hole.

FIG. 5 shows an application to the normal rotation type, that is, the air-core armature coil 555 is equally placed on the first surface of the printed wiring board 111. The printed wiring board 111 has a part of the outer diameter that is retracted to the inner diameter of the air-core armature coil 555, and a through-hole 111a is provided here. The air-core armature coil terminal connection land 111b extends substantially in the direction of the cut line from the penetration portion 111a and is provided between the air-core armature coils 555. Therefore, the printed wiring board has a substantially triangular shape in plan view. The winding start terminal S of the air-core armature coil 555 is pulled out to the back side through the through-hole 111a, and is soldered to the air-core armature coil terminal connection lands 111b again on the first surface side.
Here, the case of delta connection is shown, and the winding end terminal F of the adjacent air-core armature coil is also wired here.
Then, these are integrally molded with resin.
Even if it does in this way, since the winding start terminal of the air-core armature coil 555 is protected from the injection mold by the penetration part, the problem of a disconnection and a short circuit can be avoided.

As described above, the motor armature according to the present invention can be formed into a stator and a rotor so as to be thin without sacrificing strength. Therefore, the motor armature can be employed in an axial gap type brushless or coreless vibration motor and can be formed extremely thin. This is an industrially significant technical means as a silent notification means for portable devices such as mobile communication devices.
The motor armature need not be limited to a vibration motor. That is, if it is a shaft rotation type, it can be developed in a spindle motor having an output shaft, or in a cooling fan motor with a fan attached to the output shaft.
In the above embodiment, the axial gap type magnet is made of resin. However, it may be a rare earth sintered type, and the number of magnetic poles is 4 poles or 2 poles. The yoke bracket and the rotor, which are the stator members, can be set in accordance with the magnetic poles of the magnets to be combined.

It is a top view which shows the stator side of the brassless motor using the stator which is the armature for motors of this invention. Example 1 FIG. 2 is a longitudinal sectional view of a shaft-fixed axial gap type 1-hole sensor type coreless slotless type brushless motor storing the stator of FIG. 1. It is a top view which shows the rotor side of the coreless motor which uses the rotor which is an armature for motors of this invention. (Example 2) It is a longitudinal cross-sectional view of the axial rotation type | formula space | gap type coreless vibration motor which stored the rotor of FIG. (Example 2) It is a top view of the armature applied to the normal rotation type axial gap type coreless motor. (Example 3)

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Yoke bracket 10 Cover member 11, 111 Printed wiring board 12 Case 13 Bracket 2, 22 Axis 3 Stator base 33 Brush base 4, 44 Resin 5A, 5B, 55A, 55B, 555 Axial direction gap type air-core armature coil 6 Yoke board R, R1 Eccentric rotor H Hall sensor D Drive circuit member 7, 77 Sintered oil-impregnated bearing 8, 88 Axial gap type magnet 9, 99 Eccentric weight

Claims (7)

A plurality of axial gap air-core armature coils;
First the surface in plan view has an area for mounting at least a portion of the axial air gap-type air-core armature coil plane, printed circuit board, wherein the axial gap-type air-core armature coil in this region is placed Doo is provided further terminal lead through-section transverse to the portion of the sides of the axial gap-type air-core armature coils with in this printed wiring board wherein the first surface to the terminal connection lands are formed in which is provided, through the winding start terminal is the terminal derivation through portion of the inner diameter side of the axial air gap-type air-core armature coils, connected to the terminal connection lands are again guided to the first surface And
The axial air gap-type armature integrated with been armature motor together with the printed circuit board with a resin as a surface of the coil is exposed. The printed wiring board is formed as a stator base (3) made of a flexible substrate, and the terminal lead-out through portion is formed by a through hole (1h) and is driven by the output of one Hall sensor (H). motor armature according to claim 1 driving circuits member (D) is placed you characterized in that it is used in brushless motor that is additionally provided to the yoke bracket (1) that. The yoke bracket (1) is formed of magnetic stainless steel having a thickness of 0.2 mm or less, and a shaft support portion (1a) provided at the center, and a plurality of protrusions integrally projecting radially from the shaft support portion. A supporting part (1b) and a ring-shaped holding part (1c) in which the ends of these supporting parts are integrally closed are formed, and at least a part of the supporting part is an integral multiple of the magnetic pole opening angle of the magnet combined in plan view. The motor armature according to claim 2, wherein at least a part of the hall sensor is disposed on the support in plan view. A motor armature according to any one of claims 1 to 3, and a rotor that faces the armature through an air gap through an air gap, the rotor having a plurality of magnetic poles. An axial gap type magnet, an eccentric weight arranged outside the magnet, and a thin yoke plate that receives the magnetic field of the front magnet are provided, and the thin yoke plate is a flat portion serving as a return path of the magnet, An axial gap type motor characterized by a brushless type having an inner diameter portion for supporting a shaft and having a cover for covering the rotor. In the printed wiring board (11, 111), at least a part of the terminal lead-out penetrating part (55a, 55b, 11a, 111a) is applied to the inner diameter of the axial gap type armature coil (55A, 55B, 555). A commutator (SC) composed of a plurality of commutator segments is arranged concentrically with the center of rotation on the surface 2, so that the terminal connection lands (11b, 111b) do not overlap the axial gap air-core armature coil. 2. The motor armature according to claim 1, wherein the motor armature is used for a coreless motor . An eccentric weight made of a tungsten alloy having a specific gravity of 15 or more and disposed on the opposite side of the axial gap type air-core armature coil through a rotation center and provided with an axial direction retaining means, the printed wiring board, the axial direction together with the air-gap type coreless armature coils are integrated with a specific gravity of 2 or less resin, the motor armature according to claim 5 in which one of the oil-impregnated sintered bearings provided in the rotational center. A motor armature according to claim 5 or 6, a housing comprising a case and a bracket for housing the motor armature, each having a thickness of 0.2 mm or less, and a shaft for supporting the armature are at least One end is fixed to the bracket, and the brush base (33) attached to the bracket around the shaft is a flexible substrate having a thickness including an adhesive layer of 0.18 mm or less. hole (13a) is provided so as crosses a part of the portion Ma Gunetto is arranged, axially void portion of the brush base through the hole is derived as a feeding electrode on the housing side Type motor.

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