JP3948371B2 - Electric tool - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an electric tool using a commutator motor and the motor capable of obtaining high efficiency at low cost.
[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 permanent magnets with high energy has led to miniaturization and higher 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 permanent 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 thickness of the permanent magnets 12 and 13 in the radial direction is made as thin as possible, and the diameter of the iron ring 11 is increased by that amount to maximize the energy of the permanent magnets 12 and 13. Circuit design techniques are used.
[0005]
However, the outer diameter of the stator yoke 2 is restricted, because the passage of the magnetic flux is limited, not completely through the magnetic flux of the permanent magnets 12, 13 having a high energy, the stator yoke 2 outer periphery and permanent A large amount of magnetic flux may leak from the side end surfaces of the magnets 12 and 13. 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 as commensurate with the permanent magnets 12, 13 having a high energy, since the outer diameter of the stator yoke 2 is limited, axially iron wheels 11, as shown in FIG. 10 Although it is conceivable to extend the length of the power tool body, the overall length of the power tool main body has become longer, affecting the downsizing.
[0007]
[Problems to be solved by the invention]
When a conventional permanent magnet commutator motor is reduced in size and power, there is a problem in that a large amount of magnetic flux leaks from the outer diameter of the stator yoke 2 and both end faces of the permanent magnets 12 and 13 .
[0008]
An object of the present invention is to provide an inexpensive permanent magnet commutator motor that can solve the above-described problems and can reduce the size and increase the power of the motor without increasing the size of the stator yoke, and an electric tool using the motor. That is.
[0009]
[Means for Solving the Problems]
The above object is achieved by arranged a strong magnet body at least on one end face in the axial direction of the stator yoke and the permanent magnet, to reduce the leakage magnetic flux by passing a magnetic flux of the permanent magnets in strong magnet body.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
The electric power tool using a commutator motor of this embodiment will be described with reference to 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 two-pole permanent 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 permanent magnets 12 and 13. On the output side of the stator yoke 2 , an iron member 17 which is a ferromagnetic body is provided. The iron member 17 is also attracted and fixedly held by a magnetic force in accordance with the end face shapes of the iron ring 11 and the permanent 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. Axially is restricted by the ribs of the outer part 5, the radial direction is nipped at the ribs of the outer part 5. By matching the iron members 15 and 17 with the shapes of the iron ring 11 and the permanent 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. In fact, 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 permanent magnets 12 and 13, so that the cooling effect is not reduced and the manufacturing is performed at low cost. it is Ru can be.
[0013]
The iron members 15 and 17 are attracted to the iron ring 11 and the permanent magnets 12 and 13 , but need to be positioned. 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 a on the iron member 17 and fitting it to the inner periphery 11 a of the stator yoke 2. As another fixing method, a convex portion (not shown) may be provided in the axial direction of the iron ring 11, and the convex portion may be fitted into a hole 19a formed in the iron member 19 shown in FIG. .
[0014]
Next, the operation will be described with reference to FIG. The permanent magnet 12 is magnetized to the N pole, and the permanent magnet 13 is magnetized to the S pole. The magnetic field lines 18 are directed from the permanent magnet 12 (N pole) through the rotor rotor 1 to the permanent magnet 13 (S pole). As in the conventional system shown in FIG. 6 (a), a high flux of the permanent magnet having energy, when not completely through the iron ring 11, the air outside of the stator yoke 2 massive leakage flux 18a is generated I was passing through. However, in this embodiment , 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 permanent magnets 12 and 13, and therefore, as shown in FIG. by pouring a large amount of magnetic flux 18b from the permanent magnet 12 to the iron member 15 and 17 so that it is possible to significantly reduce the leakage magnetic flux 18a. Even if a permanent magnet having higher energy is used, the leakage flux can be reduced while suppressing the axial length of the stator yoke 2 by changing the thickness of the iron members 15 and 17 according to the leakage flux amount. Can be reduced. As a result, the possibility of iron powder or the like adsorbing to the outer shell part 5 is reduced.
[0015]
【The invention's effect】
According to the present invention, the magnetic flux leakage can be significantly reduced by disposing the ferromagnetic material on at least one side end face in the axial direction of the stator yoke and the permanent magnet and passing the magnetic flux through the ferromagnetic material. .
[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.
6 is a force diagram illustrating the flow of magnetic flux of the permanent magnet commutator motor, shows (a) shows a magnetic force diagram of a conventional, (b) 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 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, 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 (4)

A stator yoke composed of at least a pair of permanent magnets and a cylindrical iron ring provided on the outer periphery of the permanent magnet, a core having a coil wound around a shaft rotatably supported in the stator yoke, and a commutator A permanent magnet commutator motor having a rotor rotor configured to be mounted ;
A split outer frame part for housing the permanent magnet commutator motor;
In the electric tool with
A plate-like member made of a ferromagnetic material is fixed and held on both side end surfaces in the axial direction of the stator yoke by a magnetic force,
The plate-like member is provided on a side surface of the permanent magnet,
The power tool, wherein the stator yoke and the plate-like member are restricted from moving in an axial direction and a radial direction by ribs provided on the outer frame part . 2. The electric tool according to claim 1, wherein a protrusion for fitting a stator yoke to the ferromagnetic body is provided. The holes and protrusions provided in each of the strong magnetized member and the stator yoke, in any one of claims 1 or claim 2, characterized in that fitted with strong magnet body through the holes and projections on the stator yoke The electric tool described . The power tool according to any one of claims 1 to 3, wherein the shape of the plate-like member is configured to match the shape of the iron ring and the permanent magnet.

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