JP2000050537A - Direct current motor and power tool provided with direct current motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To simplify manufacture and assembly a DC motor. SOLUTION: A direct current motor 1 comprises a yoke unit 2 having permanent magnets 4, 4 fitted to the internal periphery of a yoke 5, and an armature 3 to be fitted to the yoke unit 2. The yoke 5 is divided equally into two semicylindrical split yokes 6, 6, and two-step holes 7, 7, etc., are bored in them. As permanent magnets 4, plastic magnets injection-molded using resin as a binder are used. Each magnet body 8 is united with a split yoke 6 into a body through the use of a uniting element 9, 9, etc., formed inside the two-step holes 7, 7, by performing injection molding under its fitted condition to the split yoke 6.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a DC motor comprising a yoke unit, an armature loosely inserted into the yoke unit, and a power tool provided with the DC motor.

[0002]

2. Description of the Related Art In a DC motor, a yoke unit is provided with a plurality of two-pole or four-pole permanent magnets (but before magnetizing treatment) along the inner peripheral surface of a cylindrical yoke.
Spacers such as leaf springs are provided between the permanent magnets and fixed in the yoke, and then an adhesive is applied along the boundary between the permanent magnet and the inner periphery of the yoke, cured by heating, and finally magnetized. To form a permanent magnet. Also, the power tool provided with the DC motor is usually formed of a divided housing divided into two in the axial direction of the DC motor,
When assembling the DC motor, the armature is loosely inserted into the yoke unit, and is set at a predetermined position on one of the divided housings. Storage is possible.

[0003]

In the above-mentioned DC motor, when the armature is inserted into the yoke unit at the time of assembly, the armature is likely to come into contact with the permanent magnet, which may cause the permanent magnet to be chipped or cracked. or,
When the yoke unit is manufactured, both the application step of the adhesive and the heating step are required, so that the manufacturing cost is increased. On the other hand, in the case of a power tool, the procedure of inserting an amateur into a yoke unit and setting it in a divided housing is troublesome, and it is necessary to carefully perform it so as not to cause chipping or cracking of a permanent magnet, so that workability is good. Absent.

Accordingly, an object of the present invention is to provide a DC motor in which an armature can be easily assembled and there is no danger of a permanent magnet being chipped.

[0005]

In order to achieve the above object, according to the present invention, the yoke is divided in the axial direction according to the number of the permanent magnets, and the yoke is divided for each of the divided yokes. It is characterized in that a permanent magnet is attached to each. In addition to the object of the first aspect, the invention according to the second aspect is intended to simplify the manufacturing process and the number of parts by simplifying the attachment of the permanent magnet to the split yoke, thereby achieving cost reduction. The permanent magnet is formed integrally with the divided yoke with the plastic magnet attached. In addition to the object of the first aspect, the invention according to the third aspect is to easily attach a permanent magnet to the divided yoke, thereby simplifying the manufacturing process and achieving cost reduction. A stopper is provided at each of the front and rear ends in the axial direction to restrict the movement of the permanent magnet in the axial direction, and between the permanent magnets, the movement of the permanent magnet in the circumferential direction is restricted when the yoke is assembled. A spacer is provided.

A fourth aspect of the present invention is directed to a power tool having such a DC motor, in which the DC motor can be easily assembled to improve the assembling workability, so that the yoke in each divided housing is provided. A locking portion capable of supporting a divided yoke is protruded from a set portion of the unit, so that the yoke unit can be mounted simultaneously with the mounting of the divided housing supporting the divided yoke. It is.

[0007]

Embodiments of the present invention will be described below with reference to the drawings. << Embodiment 1 >> In FIG. 1, the DC motor 1 includes a yoke unit 2 having permanent magnets 4 attached to the inner periphery of a cylindrical yoke 5 and an armature 3 into which the yoke unit 2 is loosely inserted. The yoke 5 here is bisected into half cylindrical divided yokes 6, 6 vertically divided in the axial direction, and each divided yoke 6 has a two-stage hole 7, 7,. However, three rows are formed in each of the axial direction and the circumferential direction. The permanent magnet 4 is made of a plastic magnet (rare-earth bonded permanent magnet) that is injection-molded using a resin as a binder. Since the plastic magnets flowing into the step holes 7, 7,... Are connected to the magnet main body 8 as connecting portions 9, 9,..., The magnet main body 8 is directly attached to the divided yoke 6. The split yokes 6, 6
Assembling is performed by forming insertion projections 10 and 10 on one of the end faces facing each other and insertion holes 11 and 11 on the other, respectively.
This is performed by inserting and press-fitting each other.

Therefore, in the DC motor 1 configured as described above, since the yoke 5 is divided, the armature 3 does not need to be inserted into the yoke 5, and the divided yokes 6, 6 can be assembled with the armature 3 therebetween. Therefore, there is no possibility that the permanent magnet 4 may be chipped or broken due to the insertion of the amateur 3. Further, since the permanent magnets 4 are directly injection-molded with the plastic magnets for each of the divided yokes 6 in a state of being attached, the conventional permanent magnet bonding step, heating step, parts for positioning the permanent magnets, and the like are unnecessary. Become. Therefore,
The manufacturing process and the number of parts are simplified, and cost reduction is possible.

On the other hand, in the electric tool to which the DC motor 1 is assembled, the DC motor 1 is held and fixed by a split housing divided in the axial direction of the DC motor 1. Specifically, as shown in FIG.
In the set portion of the DC motor 1 in FIGS. 1 and 21, locking claws 22, 22 as locking portions that can be elastically locked to the divided yoke 6 from the front and rear ends in the axial direction, respectively, Are protruded from the housings 21 and 21 at the time of assembly.
The split yokes 6, 6 with the permanent magnets 4 attached thereto are respectively locked by using locking claws 22, 22, and the armature 3 is set thereon with one split housing 21 facing down.
Finally, if the other split housing 21 is assembled from above, the split yokes 6 and 6 of the yoke unit 2 are assembled together with the split housings 21 and 21 as shown in FIGS. Thus, in the power tool 20,
The split yokes 6 and 6 are attached to the split housings 21 and 21 using the locking claws 22 and 22 respectively, and the armature 3 is set and the split housings 21 and 21 can be assembled by a simple procedure. The performance is improved. Of course, there is no fear of the permanent magnet 4 being damaged by the amateur 3. In particular, since the simplification of this procedure makes it easy to assemble the apparatus easily, an improvement in mass productivity can be expected.

<Embodiment 2> Next, an embodiment in which a ready-made permanent magnet that does not use a plastic magnet can be easily assembled will be described. Note that the same reference numerals as in the first embodiment denote the same parts, and a description thereof will be omitted. In FIG. 5, protrusions 1 are provided on the inner peripheral surfaces of the divided yokes 6, 6 of the yoke unit 2a at the front and rear ends in the axial direction at substantially the same intervals as the width of the permanent magnets 4a, 4a.
The permanent magnet 4a is restricted from moving in the axial direction between the protrusions 12 and 12, respectively.
An elliptical spacer 1 made of synthetic resin and having elasticity in the circumferential direction of the divided yoke 6 is provided between the permanent magnets 4a.
The positioning pieces 14, 14 projecting above and below each spacer 13 can be fitted into notches 15, 15 formed on the end face of the permanent magnet 4 a. Therefore, assembling the DC motor 1a together with the assembling to the electric tool 20 will be described with reference to FIG. One of the divided yokes 6 is fixed, one of the permanent magnets 4a is placed on the inner periphery of the divided yoke 6, and spacers 13 and 13 are used at both ends of the permanent magnet 4a, and a positioning piece 14 and a notch 15 are used, respectively. Set. In this state, the amateur 3 is set, and the other permanent magnet 4 is placed thereon.
a is assembled using the spacers 13 and 13 and finally the split housing 21 to which the other split yoke 6 is mounted is assembled from above, as shown in FIG. , 4a are spacers 13, 1
3 is fixed at the position by the elasticity.

As described above, the DC motor 1a of the second embodiment
Also, by dividing the yoke 5, the amateur 3
Need not be inserted into the yoke 5, and the permanent magnets 4a, 4a and the split yokes 6, 6 may be assembled in such a manner that the armature 3 is sandwiched therebetween. . In addition, since the permanent magnets 4a are set for each of the divided yokes 6 using the projections 12, 12 and the spacers 13, 13, the conventional permanent magnet bonding step and heating step are not required. Therefore, the manufacturing process can be simplified and the cost can be reduced.
Similarly, in the power tool 20, the split housing 2
The split yokes 6 and 6 are attached to the magnets 1 and 21 respectively using the locking claws 22 and 22, and the permanent magnets 4a and 4a and the amateur 3 are attached.
Can be assembled in a simple procedure of assembling the divided housings 21 and 21 with the ease of operation. Therefore, the workability is improved, and there is no possibility that the armature 3 may damage the permanent magnet 4a. Further, the automation of the assembly by the simplification of the procedure becomes easy.

In the first embodiment, injection molding is employed, but the same effect can be obtained by press molding. In the second embodiment, the design can be changed as appropriate, such as increasing the number of the projections 12 or using the spacer 13 as another component such as a leaf spring. In the first and second embodiments, the connecting of the divided yokes 6, 6 may be performed by other connecting means such as bonding of the end faces, other than by the insertion projection 10 and the insertion hole 11. Depending on the shape of the housing, the housing may be integrated by press-fitting the yoke without using the connecting means. Similarly, the number and shape of the locking claws 22 and the ribs 23 can be appropriately changed, and the ribs 23 may be omitted as long as they can be stably supported by the locking claws 22. However, when the rib is not provided, an elastic body such as rubber, a leaf spring, or urethane is interposed between the inner surface of the split housing 21 and the outer surface of the split yoke 6 in order to adhere and stabilize the split yokes 6, 6. It is desirable to make it.
Further, in both embodiments 1 and 2, the yoke 5 is divided into two parts as a two-pole DC motor 1 or 1a in which a permanent magnet is divided into two parts. Can be adopted.

[0013]

According to the first aspect of the present invention, the armature is divided in the axial direction in accordance with the number of permanent magnets, and the permanent magnet is attached to each of the divided yokes, so that the armature is attached to the yoke. It is not necessary to insert the armature, and the split yoke may be assembled so as to sandwich the amateur. Therefore, there is no possibility that the permanent magnet may be chipped or broken due to the insertion of the amateur. According to the second aspect of the present invention, in addition to the effect of the first aspect, the permanent magnet is formed integrally with the divided yoke with the plastic magnet attached thereto.
Attachment of the permanent magnet to the split yoke becomes simpler, and the manufacturing process and the number of parts can be simplified to achieve cost reduction. According to the invention set forth in claim 3, claim 1 is provided.
In addition to the above effects, the stopper is provided on the divided yoke, and the spacer is provided between the permanent magnets, so that the permanent magnet can be more easily attached to the divided yoke, thereby simplifying the manufacturing process and achieving cost reduction. be able to.

According to the fourth aspect of the present invention, the split housing is configured to support the split yoke by projecting a locking portion capable of supporting the split yoke at a set portion of the yoke unit in each split housing. 4. The power tool having the DC motor according to claim 1, wherein the yoke unit can be mounted at the same time as the mounting of the armature. Since it is possible to assemble the divided housing by a simple procedure of assembling, the workability is improved, and there is no fear of the permanent magnet being damaged by the amateur. In addition, the simplification of the procedure makes it easy to automate the assembling, and is expected to improve the mass productivity.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of a DC motor according to a first embodiment.

FIG. 2 is an explanatory diagram of a state of being assembled to a power tool according to a first embodiment.

FIG. 3 is an explanatory cross-sectional view of a power tool to which the DC motor according to the first embodiment is assembled.

FIG. 4 is an explanatory longitudinal sectional view of an electric tool to which the DC motor according to the first embodiment is assembled.

FIG. 5 is an explanatory diagram of a DC motor according to a second embodiment.

FIG. 6 is an explanatory diagram of an assembled state of the power tool according to the second embodiment.

FIG. 7 is an explanatory cross-sectional view of a power tool to which the DC motor according to the second embodiment is assembled.

[Explanation of symbols]

1, 1a DC motor, 2, 2a yoke unit, 3 amateur, 4, 4a permanent magnet, 5
Yoke, 6 split yoke, 12 protrusion, 13 spacer, 20 power tool, 21 split housing,
22 ··· Locking claw.

Claims (4)

[Claims] 1. A DC motor comprising: a yoke unit having a plurality of permanent magnets attached to an inner peripheral surface of a cylindrical yoke; and an armature loosely inserted into the yoke unit. Wherein the permanent magnet is attached to each of the divided yokes. 2. The direct-current motor according to claim 1, wherein the permanent magnet is formed integrally with a divided yoke with a plastic magnet attached thereto. 3. An axial front and rear end of the divided yoke,
2. A stopper according to claim 1, wherein stoppers for restricting movement of the permanent magnet in the axial direction are provided, and spacers for restricting movement of the permanent magnet in a circumferential direction in a state where the yoke is assembled are provided between the permanent magnets. DC motor as described. 4. A power tool provided with a DC motor according to claim 1, wherein a split housing vertically split in an axial direction of the DC motor is assembled, and the yoke in each of the split housings is provided. A locking portion capable of supporting a divided yoke is projected from a set portion of the unit, so that the yoke unit can be mounted simultaneously with mounting of the split housing supporting the split yoke. A power tool with a motor.