JP4590522B2 - Coreless motor and coreless motor rotor manufacturing method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
INDUSTRIAL APPLICABILITY The present invention can be applied to small vibration motors for mobile phone terminals and small and medium-sized cylindrical coreless motors for driving devices. In particular, a rotor end is formed by winding a coil end directly on a rotor hub mold. The present invention relates to a method for manufacturing a rotor part of a coreless motor that reduces assembly man-hours and structurally improves magnetic efficiency.
[0002]
[Prior art]
Conventionally, a coreless motor includes a shaft of a rotary output shaft supported by a bearing, a commutator, and the like in a cylindrical and iron (magnetic material) motor case, that is, an arrangement facing a magnet in the center of a stator portion. The cup-shaped rotor part is included. Hereinafter, the process of processing the cup-shaped rotor will be described with reference to FIGS.
[0003]
FIG. 8 is an explanatory view showing a completed state of assembly of a conventional cylindrical coil, in which (a) is a side view seen from the axial direction, and (b) is a front view of the same coil.
In the figure, reference numeral 70 denotes a coil assembly (winding coil) in which a magnet wire 30 which is a coil wire (thin wire material) is wound in a cylindrical shape, and reference numeral 71 denotes a twist process for conducting connection with a commutator terminal portion described later. A coil terminal (tap line) that has been subjected to a process of matching both ends of the two wires according to a twisted shape, 72 is a pre-solder part (connection part) pre-processed for solder welding on the coil terminal part.
[0004]
In this coil assembly 70 of winding, first, a small-diameter magnet wire 30 whose surface is coated with an insulating layer and a fusion layer is applied to a surface of a copper wire, and a jig of a cylindrical winding frame 21 is provided for each segment (one coil terminal). To the next coil end) is wound at an oblique angle in FIG. 8 (b).
[0005]
However, the bundle of winding coils wound in a cylindrical shape on the winding frame is deformed as it is, and the outer diameter dimension shape is slightly swelled and deformed. A heat-sealing press molding is performed so as to obtain the shape and dimensions, and a cylindrical coil assembly 70 as shown in FIG. 8 is completed. That is, conventionally, a single coil assembly 70 as shown in the figure in which coil terminals (tap wires) 71 are provided at various places has been individually manufactured.
[0006]
FIG. 9 is an explanatory view showing a shape configuration of a hub mold for incorporating the coil assembly 70, (a) is a side view on the commutator side, and (b) is a front view thereof.
The hub mold 80 has a structure in which a commutator 82, a commutator terminal 83 integrated with the commutator 82, and a shaft 84 of a rotating shaft are both formed by insert molding when the flange 81 is resin-molded. The coil assembly 70 is set on the hub mold 80 configured as described above using a positioning jig. That is, position adjustment in the thrust direction and alignment of the coil terminal 71 portion and the commutator terminal 83 in the radial direction are performed.
[0007]
After confirming the fixed position of positioning, the pre-solder 72 portion at the tip of the coil terminal 71 and the commutator terminal 83 portion where a part of the flange surface provided in the hub mold 80 is exposed are electrically connected to each other. Connected with welding spot (or soldering), and bonded using ultraviolet (UV) curable adhesive filler B, etc., and fixed to the inner diameter side of coil assembly 70 on the disk peripheral surface of flange 81, and cured To complete the rotor unit. The completed state of this rotor is shown in FIG. Similarly to the above, (a) is a side view on the commutator side, and (b) is a front sectional view.
[0008]
[Problems to be solved by the invention]
However, in the process of manufacturing the rotor portion of the conventional coreless motor as described above, the first is to divide the coil assembly 70 as shown in FIG. A second step of positioning the coil assembly 70 produced in the first step at a predetermined position in the axial direction of the hub mold 80 (FIG. 9B) using a dedicated jig, and a coil terminal after positioning Since the cup-shaped rotor is assembled and manufactured by the third process of bonding and fixing the parts and the cylindrical winding coil and the hub mold, the coil assembly 70 is manufactured and assembled to the hub mold 80. Since complicated processes such as work are always required, the work efficiency is not improved, and in particular, as the coil wire diameter becomes thinner due to miniaturization, the stage of manufacturing the coil assembly 70 is reduced. At the stage of setting the hub mold 80 fine next step, there is a problem that the coil wire breakage is likely to occur.
[0009]
Further, in the conventional coil winding angle, as shown in FIG. 11 (b), the winding angle is obtained by winding the magnet wire 30 on the diagonal line of the dotted line when the cylindrical winding coil is viewed in the front direction. Since A becomes large, there is a problem that magnetic efficiency (torque efficiency) is not improved.
[0010]
That is, in FIG. 7 (a), when looking at the direction of torque (Torque) generation in the cylindrical winding coil, the current I flows in the direction of the arrow, and the magnetic flux P escapes from the coil inner diameter side to the outside (N pole). This force is generated in the direction F perpendicular to the coil wire. Therefore, as the torque of the motor, the rotation axis vertical component in FIG. 7 is effective, so it is Ft that contributes to the rotation torque of the motor, and the force in the rotation direction does not increase so much, so the efficiency of the torque does not improve much. There was a problem.
[0011]
The present invention has been made in view of the above, and it is a first object of the present invention to reduce the man-hours for manufacturing a rotor of a coreless motor and to reduce the defect rate due to disconnection during operation.
A second object is to improve the magnetic efficiency (torque efficiency) by reducing the winding angle of the coil wire with respect to the rotating shaft (an angle approaching parallel to the rotating shaft).
[0012]
[Means for Solving the Problems]
In order to achieve the above object, in the method of manufacturing a coreless motor rotor according to claim 1, at least a winding coil wound in a cylindrical shape and a cylindrical central axis on one side surface of the winding coil. Cup-shaped rotor comprising: a commutator and a commutator terminal that are coaxially inserted with each other; and a hub mold that integrally supports a rotating shaft and has a protrusion formed between the commutator terminals on one end surface of the flange. A coreless motor rotor manufacturing method for manufacturing a coreless motor, wherein the hub mold one end flange surface is fitted with a winding frame having the same diameter as the inner diameter of the winding coil on a rotating shaft, and the hub mold step portion and the hub mold step portion on the winding frame, one segment of the coil wire at a predetermined coil winding angle, wound a plurality of times the step portion of the cylindrical diagonal positions and the hub mold, after which the coil winding angle of the hub mold flange Shifting the tap winding angle such that the surface side, the flange surface projections of the hub mold (guide pin) to attach one round winding Hook the coil wire, a substantially cylindrical shape of this series of operations is repeated a predetermined segment content A first step of producing a wound coil; a second step of twisting a winding end terminal of the first step together with a winding start terminal; and after the second step, the substantially cylindrical winding A third step of forming a coil into a predetermined outer shape, and a fourth step of connecting and connecting the commutator terminal and a coil wire intermediate point including the coil terminal twisted in the second step; And a fifth step of removing the winding frame from the rotor portion.
[0013]
According to the present invention, the coil winding frame having the same diameter as the coil inner diameter is inserted into the hub mold in which the commutator, the commutator terminal, and the rotation shaft are molded integrally with the resin, with the rotation shaft shaft as the center reference position. In the meantime, the coil wire (magnet wire) is wound with the hub mold stepped part to form a cylindrical winding coil, and the inner and outer diameters are predetermined after the final coil terminal portion is twisted. Then, the rotor can be manufactured by connecting the commutator terminal, the twisted terminal, and each coil wire middle point portion and fusing them to each other by hot press molding.
Furthermore, according to the present invention, by winding the coil wire from the side surface side of the hub mold to form the rotor, the winding angle of the coil wire with respect to the rotating shaft can be reduced as compared with the conventional case. High output torque can be obtained with respect to the winding method.
[0014]
Before the rotor part is completed, the components of the rotor are individually divided and manufactured, and then the components are not combined again. The work process of fitting and assembling is eliminated, and man-hours can be reduced while reducing the occurrence of coil disconnection and short-circuiting during removal and assembly.
[0017]
Further, in the rotor part structure of the coreless motor according to claim 3 , the coil part is wound, and the rotor part hub mold commutator side end part of each rotor part is connected to the hub mold protrusion or hub mold diameter. A winding fixing part provided with a stop hole part to be press-fitted into a part of the flange surface is incorporated into a part of the rotor part.
[0018]
This simplifies the bonding and fixing work of the winding coil to the hub mold side, and press-fits the winding fixing part from the axial direction to a part of the flange surface of the hub mold end, thereby Is sandwiched between the hub mold and the winding fixing part and can be firmly held and fixed as a part of the rotor portion.
[0019]
In addition, as claimed in claim 4 , by attaching a substantially half-moon eccentric weight to the rotor part output shaft of the cylindrical coreless motor obtained by claim 2 or claim 3 , A cylindrical coreless vibration motor having a function as a vibration generator to be used is obtained.
[0020]
DETAILED DESCRIPTION OF THE INVENTION
Preferred embodiments of a method for manufacturing a rotor part of a coreless motor according to the present invention will be described below in detail with reference to the accompanying drawings. The present invention is not necessarily limited to this embodiment.
[0021]
A method of processing a cup-shaped rotor of a coreless motor and its structure in this embodiment will be described below with reference to FIGS.
[0022]
FIG. 1 is an explanatory view showing a configuration example of a hub mold according to an embodiment of the present invention, in which (a) is a side view from the axial direction, and (b) is a front view. In the figure, reference numeral 10 denotes a hub mold in which each part is integrally molded as will be described later, and reference numeral 11 denotes a rotor in which a stator-side brush is slidably contacted and the current supplied through the brush is successively switched. A commutator (commutator) having a function of rotating in a certain direction even if it is a position, reference numeral 12 is connected to a coil terminal (including a coil wire middle point), which will be described later, and is arranged radially at five locations from the axis center A commutator terminal, reference numeral 13 is a guide pin of a projection for hooking a magnet wire (coil wire), and reference numeral 14 is a shaft that is located at the center of the hub mold 10 and serves as an output shaft of the rotor part. .
[0023]
The hub mold 10 is insert-molded with a rotary shaft 14 serving as a motor output shaft at the center and a commutator terminal 12 integrated with a commutator 11 piece, and a protruding magnet wire 30 is provided for each segment turn. Several guide pins 13 for hooking are formed at a part of the side end of the hub mold 10. Further, as shown in the figure, the outer shape is provided with a flange 10a and a step portion 10b around which the coil side surface portion is wound. Further, five grooves 10c are provided on the outer peripheral portion of the flange 10a to hook the coil wire at the beginning of winding. The groove 10c is not particularly required if it does not interfere with the winding work process.
[0024]
Next, a procedure for winding the cup-shaped rotor winding (winding coil portion) directly with the hub mold 10 using the hub mold 10 described above will be described.
FIG. 2 is an explanatory view showing a form in which a cup-shaped rotor is formed using the hub mold 10, and FIG. 3 is an explanatory view showing an embodiment in which a magnet wire 30 (coil wire) is wound around the hub mold 10. (A) of the figure is a schematic perspective view of winding from the commutator side, and (b) is a schematic side view of the completed rotor section from the commutator side.
[0025]
In FIG. 2, first, the reel 20 is fitted and inserted from the distal end direction of the shaft 14 at the center of the hub mold 10 toward the flange surface side end of the hub mold 10 with the shaft 14 as a reference center position. Set according to. Next, as shown in FIG. 2 and FIG. 3 (a), the magnet wire 30 at the beginning of winding is hooked in the groove 10c, and the magnet wire 30 is wound around the winding frame 20 while being rotated by minute feed in order. It winds around the level | step-difference part 10b of the hub mold 10 by winding angle (theta) c. Here, after winding one segment, the inclination of the shaft angle is adjusted so that the winding angle θt shown in FIG. 2 is obtained, and one turn is wound so that the magnet wire 30 is caught on the guide pin 13.
[0026]
That is, if the coil wire (magnet wire 30) is wound once by winding it one segment around the reel 20 and then tilting it to the tap wire angle θt, the slip (slip) of the coil wire (magnet wire 30) occurs. Take it. Thereby, the position of the coil terminal (the middle point of the coil wire similar to the tap wire) can be matched with each position of the commutator terminal 12, and the subsequent connection processing can be easily performed.
[0027]
For details of winding the coil wire, as shown in FIG. 4, the magnet wire 30 of the coil wire is hung on the stepped portion 10b of the hub mold 10, and the other is pressed and brought into contact with the outer peripheral surface of the winding frame 20 with a predetermined pressure. Hook it on the blade-shaped guide 50 and wind it. For example, if the diameter of the magnet wire 30 is φ0.16 mm, it may be repeatedly wound while sequentially rotating and moving at a pitch of 0.16 mm. The magnet wire 30 is a wire in which an insulating layer is coated on the surface of a copper wire, and a heat fusion layer that is fused at a predetermined temperature is coated thereon.
[0028]
Thereafter, the coil winding angle θc shown in FIG. 2 is restored, and the magnet wires 30 for the next segment are sequentially wound by the same method as described above. Thus, the same winding is repeated for each segment (a total of five segments in this embodiment). Then, the coil terminal T at the beginning and end of winding is finally twisted (both ends are twisted), and the winding production process is completed.
[0029]
Thereafter, the winding coil shape is formed using the winding frame 20 as it is. That is, immediately after winding the coil, there are some irregularities in the outer shape (variation), so from the outer diameter side of the coil, the winding frame 20 is used as an inner pedestal mold, and the inner mold is hot press-molded with a cylindrical mold, Processing into a desired perfect circular cylindrical winding coil. Further, as shown in FIG. 3 (b), the coil terminal T and the coil wire intermediate point S (the magnet wire 30 bridged to the guide pin 13) on the commutator terminal 12 are soldered or spot welded to the commutator terminal 12. Then, bonding (part B in FIG. 3 (b)) is performed with an ultraviolet curable adhesive filler and removed from the winding frame 20, thereby completing the cup-shaped rotor section 60.
[0030]
Further, in the rotor part structure of the coreless motor, for example, as shown in FIG. 12, a coil wire is wound, and a terminal of the hub mold is projected to one end of the commutator side flange surface of the rotor part hub mold 10 in which each terminal connection is completed. The winding fixing component 15 on the cap provided with a stop hole portion that is press-fitted into the portion 13 or a part of the diameter of the hub mold 10 may be incorporated into a part of the rotor portion.
[0031]
As a result, the work of fixing the winding coil 100 to the hub mold 10 can be simplified, and the winding fixing part 15 is press-fitted and fitted into a part of the flange surface at the end of the hub mold 10 from the axial direction F. The end portion of the wire coil 100 is mechanically sandwiched between the hub mold 10 and the winding fixing part 15, and the winding coil portion can be firmly fixed as a part of the rotor portion 60 without using an adhesive. FIG. 13 shows a cross-sectional view of the structure of a coreless motor incorporating this rotor portion.
[0032]
Therefore, by producing the rotor portion 60 as described above, a series of work steps from coil winding to terminal connection and winding coil fixing can be performed from a jig (hub mold 10 + reel 20) integrated with the hub mold 10. As the rotor 60 is completed without removing the winding coil 100 even once, operations such as alignment of the conventional coil terminal and commutator terminal and alignment of the winding coil with the hub mold in the thrust direction The number of man-hours is reduced, and the twisting process of the coil terminal becomes one place only for the final terminal, so that the occurrence rate of defects such as coil disconnection due to handling can be reduced.
[0033]
Next, it will be described that the magnetic efficiency is improved by the winding method and configuration of the winding coil 100 as described above.
FIG. 5 is an explanatory view showing the winding angle (winding angle) of the coil wire according to the embodiment of the present invention, where (a) is a side view and (b) is a schematic front view, as in the above. is there.
[0034]
As shown by the thick black line D in FIG. 5, the magnet wire 30 of the coil wire material starts from the groove 10c of the flange portion of the hub mold 10 and hangs on the step portion 10b, and further, the groove 10c of the outer diameter portion of the other flange portion 10a. Further, the winding frame (omitted by dotted lines) is hooked on a blade-shaped guide (see FIG. 4) that is in contact with the outer peripheral surface of the cylinder at a predetermined pressure, and wound to the start position of the next turn. Therefore, the winding angle wound around the winding frame is B in FIG. 5 (b). That is, the angle B is smaller than the winding angle A in FIG.
[0035]
The effect of making the winding angle B smaller than the conventional one will be described with reference to FIG. 6 and FIG. 6A and 6B are explanatory views showing the configuration of a general coreless motor and the direction of magnetic flux. FIG. 6A is a side sectional view in the axial direction, and FIG. 6B is a schematic front sectional view thereof.
In the figure, reference numeral 40 denotes a motor case made of iron (magnetic material), reference numeral 41 denotes a conventional general winding coil formed by the above-described method, reference numeral 42 denotes an N-S 2-pole magnet, reference numeral 43 denotes a shaft 14. A bearing 44 that supports the shaft is a bearing house that contains the bearing 43 and holds and fixes the magnet 42. In addition, the thick line arrow of illustration shows the direction of magnetic flux.
[0036]
FIG. 7 is an explanatory diagram showing a comparison of the magnetic efficiency due to the difference in the winding angle of the magnet wire 30, where (a) in the figure is the magnetic efficiency by conventional coil winding, and (b) is the coil of the present invention. The magnetic efficiency by winding is shown schematically.
[0037]
As shown in FIG. 6, generally, a cylindrical coreless motor has an N-S two-pole cylindrical magnet 42 inside, and the magnetic flux (arrow) diverges from the N-pole so that the motor case 40 can be used as a magnetic circuit. And converge to the S pole. The flow of magnetic flux in the circumferential direction of the motor contributes to the generation of torque of the motor. That is, the magnetic flux passes through the winding coil 41 so as to be perpendicular to the outer periphery from the center.
[0038]
Here, when the generation direction of the torque (Torque) at the conventional winding angle A shown in FIG. 7 (a) is seen, the current I flows in the direction of the arrow and the magnetic flux P escapes from the inside of the winding coil to the outside (N Pole), Fleming's left hand rule (F for thumb, magnetic flux P for index finger, and I for middle finger), the force is generated in the direction F perpendicular to the coil wire. As the motor torque, the component perpendicular to the rotation axis in the drawing is effective, so it is natural that Ft contributes to the motor torque.
[0039]
On the other hand, when compared with the winding coil of the same shape and dimension, the winding angle B of the winding coil wound by the method according to the present invention is such that A> B and the central axis of the winding angle A of the conventional winding angle A Since the angle is small with respect to the shaft 14, when the same magnetic flux and the same current are used, the rotational direction component is Ft <Ft ′. That is, as apparent from the figure, a high output torque (kinetic energy) can be obtained under the same conditions as in the conventional winding shape, and the magnetic efficiency is improved.
[0040]
The coreless motor in this embodiment uses an outer diameter of 17 mm, a rotor diameter of 12 mm, and a coil wire diameter of 0.16 mm as an example of the shape of the component structure, but the present invention is not limited to these design numerical values or specifications. In addition, the present invention can be applied to a very small motor with a similar structure.
[0041]
【The invention's effect】
As explained above, according to the rotor manufacturing method of the coreless motor according to the present invention, the outer diameter of the coil winding diameter is formed on the flange surface of the hub mold at one end where the commutator, the commutator terminal, and the rotation shaft are molded integrally with the resin. A winding frame with a hook is inserted into the rotation axis at the center of the hub mold and applied, and the coil wire is directly wound around the entire winding frame mold of the hub mold step portion and the winding frame, and is cylindrical with the hub mold. After winding the coil terminal part of the final end and twisting with the coil terminal, the outer shape was press-molded by heat fusion to a predetermined dimension, and the commutator terminal and the flange surface on the hub mold A part of the coil wire that is bridged to the guide pin (intermediate point) is connected to the commutator terminal so that a cylindrical winding coil is produced independently as before, and a jig is used later. Complicated combinations work steps such attachment to the hub mold portion is not required, it is assembly work in bulk.
[0042]
That is, a part of the winding coil winding frame itself is used as a hub mold part of the rotor, and the work process is completed without removing the winding coil from the winding frame until the rotor part is finally completed. The number of man-hours can be greatly reduced, and a winding process that is safe and reliable and requires less twisting can be realized, so that a defect rate such as coil disconnection can be reduced.
[0043]
Also, according to the rotor manufacturing method of the coreless motor according to the present invention, the winding angle of the coil wire with respect to the rotation center axis is formed by winding the coil wire from the step portion on the side flange surface of the hub mold. Therefore, the magnetic efficiency of the motor itself can be improved with respect to the conventional winding coil, and the rotor portion of the coreless motor that can obtain a high output torque can be provided.
[0044]
Further, according to the rotor portion of the coreless motor according to the present invention, in the fixed structure of the winding coil, the coil wire is wound, and the projecting portion, Or, by attaching a winding fixing part on the cap with a stop hole part that fits into a part of the hub mold diameter into a part of the rotor part, the work of bonding and fixing the winding coil to the hub mold is simplified. Or, the winding coil end can be clamped between the hub mold and the winding fixing part by press-fitting the winding fixing part into the hub mold end or part of the flange surface from the axial direction. And can be firmly fixed as a part of the rotor part easily.
[Brief description of the drawings]
FIG. 1 is an explanatory view showing a configuration example of a rotor part hub mold according to an embodiment of the present invention.
FIG. 2 is an explanatory view showing a state in which a cup-shaped rotor is formed using the hub mold of the present invention.
FIG. 3 is an explanatory view showing a state in which a magnet wire is wound around the hub mold of the present invention.
FIG. 4 is an explanatory view showing a hooked state of a blade-shaped guide when a magnet wire is wound.
FIG. 5 is an explanatory diagram showing a winding angle of a magnet wire according to an embodiment of the present invention.
FIG. 6 is an explanatory diagram showing the configuration of a coreless motor and the direction of magnetic flux.
FIG. 7 is an explanatory diagram showing a difference in magnetic efficiency due to a difference in winding angle of a magnet wire.
FIG. 8 is an explanatory view showing a conventional winding coil assembly state.
FIG. 9 is an explanatory view showing a configuration of a conventional hub mold.
FIG. 10 is a side view and a cross-sectional view showing a completed state of a conventional rotor.
FIG. 11 is an explanatory view showing a winding state of a magnet wire in a conventional example.
FIG. 12 is an explanatory view showing a state of a rotor in which a winding coil is held and fixed to a hub mold using the winding fixing part of the present invention.
FIG. 13 is a schematic cross-sectional view of a cylindrical coreless motor using the rotor configuration according to the embodiment of the present invention. [Description of symbols] of the present invention
10 Bab mold
10a flange
10b Stepped part
10c groove
11 Commutator
12 Commutator terminal
13 Guide pin
14 Shaft
15 Winding fixing parts
20 reel
21 reel
30 Magnet wire
40 Motor case
41 Winding coil
42 Magnet
43 Bearing
44 Bearing House
50 Guide
60 rotor
70 Coil assembly
71 coil terminal
72 Spare solder part
80 Hub mold
81 Flange
82 Commutator
83 Commutator terminal
84 Shaft
90 rotor
100 winding coil

Claims (4)

At least a winding coil wound in a cylindrical shape, a commutator / commutator terminal inserted coaxially with the central axis of the cylinder, and a rotating shaft at one end of the winding coil are integrally supported. And a rotor manufacturing method of a coreless motor for producing a cup-shaped rotor comprising a hub mold in which a protrusion is formed between the commutator terminals on the flange surface,
A winding frame having the same diameter as the inner diameter of the winding coil is fitted on the flange surface at one end of the hub mold so as to be fitted on a rotating shaft at the center of the hub mold, and a predetermined coil winding is applied to the hub mold step portion and the winding frame . Coil the coil wire for one segment at a line angle, winding it around the cylindrical diagonal position and the step part of the hub mold multiple times, and then shifting the coil winding angle to the tap winding angle so as to be on the flange side of the hub mold. A first step of hooking a coil wire to the protrusion of the hub mold and winding it for one turn, and repeating this series of operations for a predetermined segment to produce a substantially cylindrical winding coil;
A second step of twisting the winding end terminal of the first step together with the winding start terminal;
After the second step, a third step of forming the substantially cylindrical winding coil into a predetermined outer diameter shape dimension;
A fourth step of connecting and connecting the commutator terminal and a part of the coil wire including the coil terminal twisted in the second step;
A fifth step of removing the reel from the rotor portion;
A method for manufacturing a rotor part of a coreless motor, comprising: A cylindrical coreless motor, wherein the rotor portion obtained by claim 1 is incorporated in a part of the motor. The rotor part structure of the coreless motor according to claim 2 , wherein a coil wire is wound and a projection or a hub for hooking a coil wire is formed on a flange part one end flange surface of a rotor part hub mold in which each connection is completed. A cylindrical coreless motor characterized in that a winding fixing part provided with a stop hole portion to be press-fitted into a part of a mold diameter is incorporated in a part of a rotor part hub mold. A cylindrical coreless vibration motor, wherein a substantially half-moon eccentric weight is attached to a rotor part output shaft of the cylindrical coreless motor obtained by claim 2 or claim 3 .

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