JP2000308285A - Small-sized motor and manufacture thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a small-sized motor which ensures uniformity of accuracy of a gap between the rotor part and a coil part accompanying downsizing, and enables the coil part to be attached with accuracy to the inside of a cylindrical frame at its manufacture, and suppresses the attraction working between a permanent magnet rotor and a magnetic inner yoke and a frame. SOLUTION: The gap between a rotor part 3 and a coil part 5 can be kept uniform, and a stator can be constituted by a method of fixing the coil part 5 to the peripheral flank of the inner yoke 4, so easy assembly in view of manufacture becomes possible, by arranging the constitution such that this motor is equipped with a rotor part 3 being equipped with a permanent magnet 2 on a shaft 11, a cylindrical inner yoke 4 for covering this rotor part 3, and a coil part 5 fixed to the peripheral flank of this inner yoke 4, and that brackets 7 for axially supporting the shaft 1 of the rotor part 3 are fixed to both ends of the inner yoke 4 and a cylindrical frame 6 for covering the coil part 6 is fixed by the brackets 7.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a small motor.

[0002]

2. Description of the Related Art A brushless motor will be described as an example of a conventional permanent magnet motor. The rotor part with the permanent magnet fixed to the shaft and the stator part formed by winding a copper wire around the yoke made of laminated electromagnetic steel sheets are covered with a frame, the shaft is supported by ball bearings, and the bracket is covered with a bracket. Are known. In addition, in the yoke around which the copper wire is wound, a laminated electromagnetic steel sheet is generally used to efficiently converge the magnetic flux generated from the coil on the surface of the permanent magnet.

[0003] In the structure of the brush motor, the positional relationship between the rotor section and the stator section is the same, and it is conventionally known to use an electromagnetic steel sheet laminated on a portion around which a copper wire is wound. In the case of a coreless motor, the cup-shaped rotor is formed of copper wire without winding the copper wire around the laminated steel plate serving as the yoke, but the frame (motor case) that covers the outside is made of, for example, a material obtained by deep drawing a plated steel plate are doing.

[0004] As described above, the conventional permanent magnet motor is generally made of a magnetic material using an electromagnetic steel plate or a plated steel plate to converge the magnetic flux and to cover the internal structure. In a motor using a permanent magnet, a coil is fixed inside a cylindrical frame, and a rotor is rotated inside the frame to which the coil is fixed.

[0005]

By the way, in the above-mentioned small motor, as the motor outer diameter becomes smaller,
The gap between the rotor and the coil fixed inside the frame has become narrow, and it has become difficult to maintain uniform gap accuracy. In addition, when manufacturing such a small motor, if the outer diameter of the motor becomes small, it is difficult in manufacturing to mount the coil accurately inside the cylindrical frame. On the other hand, the wire diameter of the coil part was made too thin to reduce the motor outer diameter, and the number of windings was reduced. The magnetic field generated from the coil part has been reduced.

Therefore, the attractive force acting between the permanent magnet rotor, the inner yoke and the frame cannot be ignored with respect to the force generated by the magnetic field generated from the coil portion to rotate the permanent magnet rotor. And the output of the motor is reduced as a result. Further, when the outer diameter of the motor is reduced to 3 mm or less, there is a problem that the small motor does not rotate due to the attractive force acting between the permanent magnet rotor, the inner yoke and the frame.

An object of the present invention is to ensure uniform gap accuracy between a rotor section and a coil section with downsizing, to accurately mount the coil section inside a cylindrical frame when manufacturing this small motor, An object of the present invention is to provide a small-diameter motor in which an attractive force acting between a magnet rotor and a magnetic inner yoke and a frame is suppressed.

[0008]

In order to solve the above-mentioned problems, a small motor according to the present invention comprises: a rotor having a permanent magnet on a shaft; a cylindrical inner yoke covering the rotor; A coil section for generating a rotating magnetic field for rotating a rotor section fixed to the outer peripheral side surface of the inner yoke; and a frame covering the rotor section, the inner yoke and the coil section, and a material of the inner yoke and the frame. Is made of a non-magnetic material, a bracket is fixed to both ends of the frame, and a shaft of the rotor section is supported.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention comprises a rotor section having a permanent magnet, a cylindrical inner yoke covering the rotor section, and a coil section fixed to the outer peripheral side surface of the inner yoke. Is a small motor which is a non-magnetic material, and can maintain a constant gap accuracy between the rotor and the coil.

Further, the compact motor of the present invention can be downsized by forming the inner yoke by integrally molding the coil portion with a resin in a cylindrical mold.

Further, in the small motor according to the present invention, the gap interval can be kept constant even if the motor outer diameter is not more than φ3 mm.

According to the manufacturing method of the present invention, after fixing a coil portion to an outer peripheral side surface of a cylindrical inner yoke made of a non-magnetic material, a bracket of a rotor portion having a permanent magnet is supported on a bracket, and This is a method for manufacturing a small motor in which the inner yoke is fixed at a position covering the rotor section. By providing the coil section outside the inner yoke, the coil section can be easily attached. Further, in the small motor according to the present invention, after the coil portion is fixed to the outer peripheral side surface of the inner yoke, a cylindrical frame may be fixed to the bracket at a position covering the coil portion. Further, in the manufacturing method of the present invention, after forming the inner yoke by integrally molding the coil portion in a cylindrical mold, a cylindrical frame may be fixed to the bracket at a position covering the inner yoke. .

Further, according to the manufacturing method of the present invention, the coil portion can be easily attached even to a small motor having an outer diameter of φ3 mm or less.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIG. As shown, a rotor 3 having a permanent magnet 2 on a shaft 1, a cylindrical inner yoke 4 covering the rotor 3, and a coil 5 for generating a rotating magnetic field for rotating the rotor 3. A frame 6 for covering the rotor section 3, the inner yoke 4, and the coil section 5; the inner yoke 4 and the frame 6 are made of a non-magnetic material; 7, the shaft 1 of the rotor unit 3 is supported. Further, as shown in FIG. 2, it is possible to use a stator portion 8 in which the coil portion and the inner yoke are integrated by insert molding.

Here, the permanent magnet 2 of the rotor section 3 is formed in a ring shape by compression molding or injection molding of magnet powder, or is formed integrally with the shaft 1 by molding. NdFeB, SmC
o, ferrite, and SmFeN. Further, by forming the shaft 1 with a permanent magnet such as MnAl or FeCrCo, the rotor section 3 can be processed with one part, so that the number of parts can be reduced.

The coil portion 5 uses a self-fused electric wire, and after winding and forming with a jig, the electric wire is fixed with ethanol. Thereafter, bending is performed according to the curvature of the outer peripheral side surface of the inner yoke 4. The coil part 5 thus manufactured is fixed to the outer peripheral side surface of the inner yoke 4 with an adhesive. Regarding the coil portion 5, the coil portion 5 is not limited to the self-fused electric wire, but is obtained by winding and forming an electric wire having no fusion layer with a jig, for example, a polyimide film with copper foil. It is also possible to use a film coil in which a coil pattern is formed.

Since the inner yoke 4 is configured to fix the coil portion 5 to the outer peripheral side surface, the coil portion 5 is bonded to an appropriate position using a jig to form a stator. When a jig is not used, the coil portion 5 can be fixed at an appropriate position by providing a groove and a projection for positioning the coil portion 5. The material of the inner yoke 4 for fixing the coil portion 5 and the frame 6 covering the coil portion 5 is not particularly limited to a metal material as long as it is a nonmagnetic material, and a resin material or a ceramic material may be used. It is possible. In particular, in the case of a resin material, the number of components and the number of assembly steps can be reduced by forming the stator portion 8 in which the coil portion is insert-molded and the inner yoke and the coil portion are integrated with each other.

Brackets 6 arranged at both ends of the frame 6
Since the shaft supports and slides the shaft 1, a material such as an ethylene tetrafluoride resin having particularly excellent self-lubricating properties is desired.

In the small-sized motor of the embodiment, by providing the cylindrical inner yoke 4 between the rotor section 3 and the coil section 5, it is easy to maintain uniform gap accuracy between the rotor section 3 and the coil section 5. In addition, it is possible to prevent uneven rotation due to uneven gap. Further, by adopting a configuration in which the coil portion 5 is bonded to the outer peripheral side surface of the inner yoke 4, mounting and positioning of the coil portion 5 during assembly can be facilitated.

Further, by forming the coil section 5 by insert molding to form a stator section in which the inner yoke 4 and the coil section 5 are integrated, it is possible to reduce the number of parts and the number of assembling steps. Further, since the inner yoke is made of a non-magnetic material, the rotor can be rotated by the magnetic field generated from the coil without receiving the attractive force from the permanent magnet.

The configuration of this embodiment is suitable for a small motor having an outer diameter of the motor (outer diameter of the frame 6) of 3 mm or less.

[0022]

As described above, according to the present invention, the structure in which the cylindrical inner yoke is interposed between the rotor portion and the coil portion enables the rotor portion and the coil portion to be mounted even when the motor is further downsized. The gap accuracy of the part can be kept constant.

Further, since the mounting of the coil portion is performed on the outer peripheral side surface of the inner yoke, the assembly can be easily performed as compared with the case where the coil portion is disposed inside the frame. By forming the stator unit with the coil unit integrated, it is possible to reduce the number of components and the number of assembly steps.

Further, since the inner yoke and the frame are made of a non-magnetic material, the rotor can be rotated by the magnetic field generated from the coil without receiving the attraction from the permanent magnet.

[Brief description of the drawings]

FIG. 1 is a perspective view of components constituting a small motor according to the present invention.

FIG. 2 is a perspective view of components constituting a small motor according to the present invention.

[Description of Signs] 1 Shaft 2 Permanent magnet 3 Rotor 4 Inner yoke 5 Coil 6 Frame 7 Bracket 8 Stator

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 5H002 AA07 5H604 AA08 BB01 BB14 BB17 CC01 CC04 CC05 5H615 AA01 BB01 BB14 PP01 PP02 PP17 PP24 PP25 PP28 QQ02 SS44 TT05 5H622 CA01 CA05 CB04 DD01 DD02 QA10

Claims (8)

[Claims] 1. A rotor comprising a permanent magnet, a cylindrical inner yoke covering the rotor, and a coil fixed to an outer peripheral side surface of the inner yoke, wherein the inner yoke is a non-magnetic material. Small motor. 2. A bracket is fixed to both ends of the inner yoke,
The small motor according to claim 1, wherein a shaft of a rotor portion is pivotally supported by the bracket, and a cylindrical frame that covers the coil portion is fixed by the bracket. 3. The small motor according to claim 1, wherein the coil portion is integrally molded with a resin in a cylindrical mold to form an inner yoke. 4. The small motor according to claim 2, wherein the outer diameter of the motor is φ3 mm or less. 5. A position in which a coil portion is fixed to an outer peripheral side surface of a cylindrical inner yoke made of a non-magnetic material, and a bracket supports a shaft of a rotor portion having a permanent magnet and covers the rotor portion. And a method for manufacturing a small motor for fixing the inner yoke. 6. The method for manufacturing a small motor according to claim 5, wherein after fixing the coil portion to the outer peripheral side surface of the inner yoke, a cylindrical frame is fixed to the bracket at a position covering the coil portion. 7. The small-sized compact device according to claim 5, wherein the coil portion is integrally resin-molded in a cylindrical mold to form an inner yoke, and a cylindrical frame is fixed to the bracket at a position covering the inner yoke. Motor manufacturing method. 8. The method for manufacturing a small motor according to claim 5, wherein the outer diameter of the motor is φ3 mm or less.