JP2004080969A - Permanent magnet commutator motor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a low-cost power tool, whose leakage flux can be reduced and whose motor can be miniaturized and turned more powerful, without enlarging stator yokes. <P>SOLUTION: This permanent magnet commutator motor is configured, to shut the leakage flux with metal members that are provided on both side-end-surfaces in the axial direction of a stator yoke 2 and magnets 12, 13. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a permanent magnet commutator motor capable of obtaining high efficiency at low cost, and more particularly to a structure of a permanent magnet commutator motor used for an electric tool.
[0002]
[Prior art]
In recent years, miniaturization and high power of electric tools have been progressing rapidly. Although the evolution of cordless tools using storage batteries is remarkable, the use of magnets with high energy has led to the miniaturization and high output of motors.
[0003]
Hereinafter, a description will be given with reference to FIGS. FIG. 7 shows the internal structure of the electric power tool. A rotor rotor 1 having a pinion 9 serving as an output part at the tip is housed in an outer part 5 while both ends are held by bearings 10. A stator yoke 2 is disposed outside the core of the rotor rotor 1. The stator yoke 2 is housed in an outer shell part 5 made of a plastic material in both the radial direction and the axial direction while fixing and holding two pole magnets 12 and 13 to a cylindrical iron ring 11.
[0004]
In order to improve the usability of the electric tool, the outer diameter of the stator yoke 2 is limited in order to make the tool body as compact as possible. Therefore, as shown in FIG. 9, the magnetic circuit design that maximizes the energy of the magnets 12, 13 by making the radial thickness of the magnets 12, 13 as thin as possible and increasing the radial direction of the iron rings 11 correspondingly. The method is used.
[0005]
However, if the outer diameter of the stator yoke 2 is limited, the path of the magnetic flux is limited. Therefore, the magnetic fluxes of the magnets 12 and 13 having high energy cannot be passed, and the outer diameter of the stator yoke 2 and the magnet 12 , 13 may leak a large amount of magnetic flux from the side end surfaces. For this reason, iron powder or the like is sucked and iron powder or the like may be adsorbed to the outer shell part 5 or may be caused to enter from the wind window of the outer shell part 5. If iron powder is adsorbed on the outer shell 5, the iron powder becomes awkward and painful when the tool is held, or iron powder enters the rotor rotor 1 and the stator yoke 2 due to the iron powder entering from the wind window. This causes problems such as
[0006]
Further, in order to increase the volume of the iron ring 11 to match the magnets 12 and 13 having high energy, the outer diameter of the stator yoke 2 is limited, so that the iron ring is extended in the axial direction as shown in FIG. Although a method is conceivable, the overall length of the power tool main body has become longer, which has affected the downsizing.
[0007]
[Problems to be solved by the invention]
When the conventional permanent magnet commutator motor is reduced in size and power, there is a problem that a large amount of magnetic flux leaks from the outer diameter of the stator yoke and from both end faces of the magnet.
[0008]
An object of the present invention is to provide an inexpensive electric tool that can solve the above-described problems and can reduce the size and power of a motor without increasing the size of a stator yoke.
[0009]
[Means for Solving the Problems]
The above object is achieved by disposing iron members on both end faces in the axial direction of the stator yoke and the magnet and blocking the leakage magnetic flux with iron.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
The electric tool which has a permanent magnet commutator motor in a present Example is demonstrated using FIGS. 1 and 2 show the internal structure of the motor part in the electric tool, and the power source accommodates the rotor rotor 1, the stator yoke 2, the carbon brush 3, and the carbon brush block 4 (hereinafter referred to as CB block). Therefore, the outer part 5 is made of plastic. The CB block 4 is a component necessary for making the carbon brush 3 exchangeable from the outside, and holds the CB tube 6, the CB cap 7 and the lead wire 8.
[0011]
The rotor rotor 1 has a pinion 9 serving as an output portion at the tip, and is housed in the outer shell part 5 while being held by bearings 10 at both ends. A stator yoke 2 is disposed outside the rotor rotor 1.
[0012]
In the stator yoke 2, arcuate dipole magnets 12 and 13 are fixedly held on a cylindrical iron ring 11. On the non-output side of the stator yoke 2, a metal member, that is, an iron member 15, which is a strong magnetic body keeping an appropriate distance from the coil end 14 of the rotor rotor 1, is provided. The iron member 15 has a cylindrical portion 16 in which an iron plate of about 0.5 mm is formed into a cup shape by drawing, and the cylindrical portion 16 is fitted in a hole of the CB block 4. Further, the opposite side of the cylindrical portion 16 is attracted and fixedly held by a magnetic force in accordance with the end face shapes of the iron ring 11 and the magnets 12 and 13. On the output side of the stator yoke, an iron member 17 which is a ferromagnetic body is provided. The iron member 17 is also fixed and held by being attracted by a magnetic force in accordance with the end face shapes of the iron ring 11 and the magnets 12 and 13. The iron members 15 and 17 are fixed and held in a state where they are sucked onto the stator yoke 2 and assembled into the outer shell part 5. The axial direction is regulated by the rib of the outer shell part 5, and the radial direction is held by the rib of the outer shell part 5. By matching the iron members 15 and 17 with the shapes of the iron wheel 11 and the magnets 12 and 13, air path resistance is not achieved, and cooling air is blown onto the iron members 15 and 17 to serve as a heat sink. , Heat dissipation can be improved. The iron members 15 and 17 described above are washers punched out by press working and have a shape that covers the stator yoke 2 and the magnets 12 and 13, and are manufactured at a low cost without reducing the cooling effect. It is something that can be done.
[0013]
Moreover, although the iron members 15 and 17 are adsorb | sucking with the iron ring 11 and the magnets 12 and 13, positioning is required. If there is no positioning, it will contact the rotor 1 and cause a failure. As shown in FIG. 4, the positioning can be performed by providing a protrusion 17 on an iron member and fitting it into the inner diameter 11 a of the stator yoke 2. Further, as another fixing method, as shown in FIG. 5, a convex portion (not shown) may be provided in the axial direction of the steel wheel 11, and a hole 19 a may be formed in the iron member 19 and fitted.
[0014]
Next, the operation will be described with reference to FIG. The magnet 12 is magnetized to the N pole, and the magnet 13 is magnetized to the S pole. The magnetic field lines 18 are directed from the magnet 12 (N pole) through the rotor rotor 1 to the magnet 13 (S pole). In the conventional method, as shown in FIG. 6A, when the magnetic force of the magnet having high energy cannot pass through the stator yoke 2, a large amount of leakage magnetic flux 18a is generated and passes through the air outside the yoke. I was sorry. However, in this embodiment, since the iron members 15 and 17 provided on the output side and the counter-output side of the stator yoke 2 extend to the immediate side surfaces of the magnets 12 and 13, as shown in FIG. By flowing a large amount of leakage magnetic flux from the magnet 12 to the iron members 15 and 17, the leakage magnetic flux 18a can be greatly reduced. Even if a magnet with higher energy is used for the tool, the thickness of the iron members 15 and 17 is changed in accordance with the amount of magnetic flux leakage, so that the length of the stator yoke 2 in the axial direction is suppressed. Magnetic flux can be reduced.
[0015]
【The invention's effect】
According to the present invention, the leakage flux can be significantly reduced by disposing the metal member on both end faces in the axial direction of the stator yoke and the magnet and passing the leakage flux through the metal member.
[Brief description of the drawings]
FIG. 1 is a partially omitted vertical side view showing the vicinity of a motor of an electric tool according to the present invention.
FIG. 2 is a partially omitted vertical side view showing the vicinity of the motor of the electric tool according to the present invention.
3 is a cross-sectional view taken along line AA of FIG. 1 according to the present invention.
4A and 4B show metal parts according to the present invention, in which FIG. 4A is a front view thereof, and FIG. 4B is a side view thereof.
5A and 5B show another metal part according to the present invention, in which FIG. 5A is a front view thereof, and FIG. 5B is a side view thereof.
FIG. 6 is a magnetic force diagram showing the flow of magnetic force of a permanent magnet commutator motor, (a) shows a magnetic force diagram of a conventional product, and (b) shows a magnetic force diagram according to the present invention.
FIG. 7 is a partially omitted vertical side view showing the vicinity of a motor of a conventional electric tool.
FIG. 8 is a schematic cross-sectional view showing the structural relationship between a conventional iron ring and a magnet.
FIG. 9 is a schematic cross-sectional view showing the structural relationship between a conventional iron ring and a magnet.
FIG. 10 is a schematic cross-sectional view showing another structural relationship between a conventional iron ring and magnet.
[Explanation of symbols]
1 is a rotor rotor, 2 is a stator yoke, 3 is a carbon brush, 4 is a CB block, 5 is an outer part, 6 is a CB tube, 7 is a CB cap, 8 is a lead wire, 9 is a pinion, 10 is a bearing, 11 is an iron ring, 12 is a magnet, 13 is a magnet, 14 is a coil end, 15 is an iron member, 16 is a cylindrical portion, 17 is an iron member, 17a is raised, 18 is a magnetic field line, and 18a is a magnetic flux leaking to the outer circumference of the yoke , 18b is a magnetic flux flowing into the iron member, 19 is an iron member, and 19a is a hole.

Claims (3)

A stator that forms a field magnetic pole by a permanent magnet, a core having a plurality of slots in a shaft that is rotatably supported by a bearing portion provided in a housing, and a commutator. A coil is wound around the core. In a permanent magnet commutator motor in which a coil connected to the commutator is energized through a brush by a rotor configured to be connected to the rotated commutator and generates rotational torque in the rotor, the stator yoke and the magnet in the axial direction A permanent magnet commutator motor characterized in that metal members are provided on both end faces. The permanent magnet commutator motor according to claim 1, further comprising a protrusion for fitting the metal member made of iron with the stator yoke. The permanent magnet commutator motor according to claim 1, wherein a hole is provided in the metal member, and a convex portion is provided in the stator yoke.

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