JPH07336951A - Armature of compact dc motor and its manufacture - Google Patents

Abstract

PURPOSE:To prevent a coil from interfering with an arc-extinguishing element when shaping a coil and to prevent the coil from being disconnected or the arc-extinguishing element from being cracked by providing a wall which is raised in an axial direction at a commutator holder. CONSTITUTION:A plurality of walls 3d are raised and formed nearly in an axial direction at the outer-periphery edge part of a frame part 3b and a clearance is formed between the walls 3d. A commutator unit 3 is tentatively pressed into the upper edge of a shaft 1 which is less affected by a coil 4 when rotating the coil 4 for the protrusion pole of an armature core 2 and a wall 3d for protecting an arc-extinguishing element 5 can be placed at a higher position than the coil 4, thus completely preventing the interference between the coil 4 to be wound and the arc-extinguishing element 5. Also, the coil 4 and the arc-extinguishing element 5 can be completely cut off even after the commutator unit 3 is actually press-fit from the state where the commutator unit 3 is tentatively press-fit, thus eliminating the problems as the crack of the arc- extinguishing element 5 and the disconnection of the coil 4.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an armature for a small DC motor used in a headphone stereo, a portable CD player, etc., and a method for manufacturing the same.

[0002]

2. Description of the Related Art An example of a small DC motor armature used in a headphone stereo, a portable CD player or the like will be described with reference to the drawings. 6 and 7, an armature core 22 is attached to the shaft 21. The armature core 22 is configured by laminating a plurality of core bodies, and a plurality of salient poles are formed on the outer circumference. The upper end surface and the lower end surface of the armature core 22 are covered with an insulator 26.
2 is sandwiched. A coil 24 is wound from above the insulator 26 on each salient pole of the armature core 22 whose upper and lower surfaces are covered with the insulator 26. In addition, a wall 26a, which is perpendicular to the upper surface of the insulator 26, is integrally formed in a portion of the insulator 26, which is inside the coiled portion of the coil 24.

A commutator unit 23 is mounted above the armature core 22 of the shaft 21. The commutator unit 23 is composed of a commutator holder 23a and a commutator 23c attached to the surface of the commutator holder 23a. The commutator holder 23a has a shaft 21
And a flange portion 23b formed at the lower end of the cylindrical portion.

A plurality of partially cylindrical commutators 23c are attached to the outer peripheral surface of the cylindrical portion of the commutator holder 23a. A slit for switching current is formed between each commutator 23c. In addition, each commutator 2
The lower end of 3c is bent outward at a right angle and extends to the outer peripheral side along the upper surface of the flange 23b. A part of the commutator 23c on the collar portion 23b is pulled out to the outside of the wall 26 formed in the insulator 26 to form a riser 28. The riser 28 has a tip end portion of the coil 24. Is wrapped around.

Further, the commutator 23 mounted on the collar portion 23b
A ring-shaped arc extinguishing element 25 is attached to the upper surface of c on the outer peripheral side of the collar portion 23b and on the inner side of the wall portion 26a. The arc extinguishing element 25 plays a role of suppressing generation of sparks when a brush (not shown) slides on the commutator 23c to switch the energization to the coil 24.

The shaft 21 and the armature core 2 as described above
2. The armature of the small DC motor including the commutator unit 23 has a cup-shaped rotor case 29 as shown in FIG.
It is attached so that it can rotate freely inside the. A ring-shaped drive magnet 30 is attached to the inner peripheral surface of the rotor case 29. The inner peripheral surface of the drive magnet 30 faces the salient poles of the armature core 22 with a certain gap. Therefore, from the brush not shown, the commutator 23
By supplying a current to the coil 24 via the c and riser 28, the armature core 22 is urged and the shaft 21 is rotationally driven. When the shaft 21 rotates, the commutator 23c that comes into sliding contact with a brush (not shown) moves to the next commutator 2
3c is sequentially switched, the current supplied to the coil 24 is switched, and the shaft 21 is continuously rotated.

[0007]

When the coil 24 is wound around the salient pole of the armature core 22 as described above, a part of the coil 24 is attached to the commutator unit 23 so as to be closer to the inner peripheral side. Interference with the arc extinguishing element 25 may cause cracking of the arc extinguishing element 25 and disconnection of the coil 24. Therefore, a wall 26a is formed on the insulator 26 on the commutator unit 23 side in order to prevent the coil 24 from approaching the inner circumference side. However, the height dimension of the wall 26a is set to the height of the coil 24 in order to flatten the motor. Can't be bigger than the dimensions,
It was not possible to exert sufficient effect.

Further, since the salient pole around which the coil 24 is wound has the wall portion 26a formed in advance, the wound coil 24 is affected by the shape of the outer peripheral surface of the wall 26a and is seen from the axial direction. The coil 24 is wound in an arc shape and becomes fan-shaped as a whole, which causes various problems such as an increase in stress on the commutator holder 26 of the coil 24 and an increase in the resistance value of the coil 24 itself.

The present invention has been made in order to solve the above-mentioned problems, and there is no interference between the coil and the arc extinguishing element during coil shaping, and it is possible to prevent disconnection of the coil and cracking of the arc extinguishing element. An object of the present invention is to provide an armature for a small DC motor and a method for manufacturing the same.

[0010]

The invention according to claim 1 is
An armature core and a commutator unit are axially arranged and fixed to a shaft, a coil is wound around a salient pole of the armature core, and an arc extinguishing element is fixed to the commutator unit. In the armature, the commutator unit includes a commutator holder having a cylindrical portion fitted to a shaft and a collar portion, and a commutator fixed to the outer peripheral surface of the cylindrical portion of the commutator holder, and the commutator holder is provided. The outer edge portion of the collar portion has a wall portion that is erected in a substantially axial direction.

According to a second aspect of the present invention, the armature core is fitted and fixed to the shaft, and a commutator holder having a wall portion axially erected on the outer edge portion and the outer periphery of the commutator holder are fixed. The step of temporarily press-fitting the commutator unit including the commutator to the shaft, the step of winding the coil around the salient pole of the armature core fitted and fixed to the shaft, and the commutator unit temporarily press-fitted to the shaft Press-fitting process,
At least a step of shaping the coil wound around the salient pole of the armature core is provided.

[0012]

The axially standing wall of the commutator holder prevents interference between the coil wound around the armature core and the arc extinguishing element of the commutator unit. The coil is wound around the armature core while the commutator unit is temporarily press-fitted onto the shaft. Due to the provisionally press-fitting of the commutator unit, the wall erected at the outer edge of the flange of the commutator holder is at a position sufficiently higher than the coil, so that the arc extinguishing element and the coil are prevented from interfering with each other during winding. After that, since the commutator unit is press-fitted into the shaft, interference between the arc extinguishing element and the coil after the main press-fitting is also prevented.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of an armature for a small direct current motor and a method of manufacturing the same according to the present invention will be described below with reference to the drawings. In FIGS. 1 and 2, an armature core 2 is fitted and fixed to a shaft 1. The armature core 2 is configured by laminating a plurality of core bodies, and a plurality of salient poles are formed on the outer circumference. The insulator 6 is in contact with the upper surface and the lower surface of the armature core 2, and the armature core 2 is sandwiched by the insulator 6. Armature core 2
A coil 4 is wound around each salient pole from above the insulator 6.

A commutator unit 3 is press-fitted into the shaft 1 from the upper end side in FIG. Commutator unit 3
Is composed of a commutator holder 3a and a commutator 3c. The commutator holder 3a has a cylindrical portion fitted and fixed to the shaft 1, and a flange portion 3b formed below the cylindrical portion. Further, a plurality of walls 3d are formed upright in the axial direction on the outer peripheral edge of the collar 3b.
A gap 3f is formed between d.

A plurality of partially cylindrical commutators 3c are attached to the outer peripheral surface of the cylindrical portion of the commutator holder 3a. A slit for switching current is formed between each commutator 3c. The lower end portion of each commutator 3c is bent at a right angle to the outer peripheral side and fitted into the gap 3f, and the tip portion further extends outward from the gap 3f and riser 3 is formed.
It is e. The tip of the coil 4 is wound around the tip of the riser 3e. A ring-shaped arc extinguishing element 5 is attached to the inside of the wall 3d of the commutator holder 3a. The lower surface of the arc extinguishing element 5 is in contact with the upper surface of the portion of the commutator 3c that is bent at a right angle. The arc extinguishing element 5 plays a role of suppressing generation of sparks when a brush (not shown) is brought into sliding contact with the commutator 3c to switch energization to the coil 4.

The armature having the above-described structure is rotatably attached to the motor case of the small DC motor. A brush connected to a power source (not shown) is in contact with the specific commutator 3c of the commutator unit 3. The salient poles of the armature core 2 around which the coil 4 is wound face a drive magnet mounted on the inner peripheral surface of a motor case (not shown) with a certain gap.
Therefore, when current is supplied to the coil 4 from a power source (not shown) via the brush, the commutator 3c, and the riser 3e, the armature core 2 is urged by the magnetic force of the drive magnet (not shown), and the shaft 1 is rotationally driven. It As the shaft 1 rotates, the commutator 3c with which the brush comes into contact is sequentially switched to the next commutator 3c, and the coil 4
The electric current supplied to the shaft 1 is switched and the shaft 1 is continuously rotated.

Next, an embodiment of the method for manufacturing the armature of the small DC motor will be described. First, as shown in FIG. 3, after the armature core 2 is fitted and fixed to the shaft 1, the commutator unit 3 is temporarily press-fitted into the upper end portion of the shaft 1, and the coil 4 is inserted into the salient pole of the armature core 2. Wrap around. Next, the commutator unit 3 is pushed downward and is fully press-fitted into the shaft 1 to bring the coil 4 into close contact with the outer peripheral surface of the collar portion 3b. next,
The coil 4 wound around the salient poles of the armature core 2 is shaped while being compressed from both sides in the axial direction to reduce the height dimension of the coil 4 in the axial direction. In this way, the armature of the small DC motor as shown in FIGS. 1 and 2 is manufactured.

In the armature of the small DC motor having the above-described structure, the commutator unit 3 has the shaft 1 which is not easily affected by the coil 4 when the coil 4 is wound around the salient pole of the armature core 2. Temporarily press fit into the upper end of the arc extinguishing element 5
Since the wall 3d for protecting the coil can be placed at a position sufficiently higher than the coil 4, the interference between the wound coil 4 and the arc extinguishing element 5 can be completely prevented. Also,
Even after the commutator unit 3 is fully press-fitted from the state where the commutator unit 3 is temporarily press-fitted, the coil 4 and the arc extinguishing element 5 are completely partitioned by the wall 3d, so that they do not interfere with each other.
Therefore, it is possible to solve problems such as breakage of the arc extinguishing element 5 and disconnection of the coil 4. Since the coil 4 is wound while the commutator unit 3 is temporarily press-fitted, and then the commutator unit 3 is fully press-fitted, the height of the wall 3d for protecting the arc extinguishing element 5 may be low, The axial dimension of the motor can be reduced.

Further, since the wall 3d is formed on the outer edge portion of the flange portion 3b of the commutator holder 3a which is temporarily press-fitted, when the coil 4 is wound around the salient pole of the armature core 2, there is a winding obstacle. The coil 4 can be wound around the salient poles in a state where there is nothing on the armature core 2. For this reason,
The coil 4 can be wound in a direction substantially orthogonal to the extending direction of the salient poles, the total length of the coil 4 is shortened, the winding resistance thereof is reduced, and the characteristics of the small DC motor can be improved. However, the stress on the commutator holder 3a of the coil 4 can be relieved.

Next, a modified embodiment of the present invention will be described. In the embodiment shown in FIGS. 4 and 5, the flange portion 3b, which is a part of the commutator holder 3a, is cut out at the outer peripheral side bottom surface portion to form the winding escape portion 3g. By forming the winding escape portion 3g, part of the coil 4 enters the winding escape portion 3g when the coil 4 is shaped, so that the stress on the commutator holder 3a of the coil 4 can be further reduced.

[0021]

According to the first aspect of the present invention, the commutator unit is fixed to the commutator holder having the cylindrical portion and the collar portion fitted to the shaft, and the outer peripheral surface of the cylindrical portion of the commutator holder. With a commutator, the outer edge of the collar of the commutator holder has a wall that stands up in a substantially axial direction, so the wall can separate the coil side and the arc extinguishing element side.
Not only can the coil be prevented from interfering with the arc-extinguishing element when the coil is shaped, but the wall position can be closer to the center of rotation compared to the conventional case where a wall is provided on the insulator with an armature core. Since the coil can be wound around the center of rotation, the diameter of the motor can be reduced. ,

According to the second aspect of the invention, in the armature of the small direct current motor, at least the armature core is fitted and fixed to the shaft, the commutator unit is temporarily press-fitted into the shaft, and the armature core is fitted into the shaft. The process of winding the coil around the salient pole of the fixed armature core, the process of press-fitting the commutator unit temporarily press-fitted onto the shaft, and the process of shaping the coil wound around the salient pole of the armature core. Since the wall of the commutator unit is located sufficiently higher than the coil during winding, the coil does not interfere with the arc-extinguishing element, and therefore disconnection of the coil and cracking of the arc-extinguishing element are eliminated. It becomes possible to do. Also, when the coil is wound, there is no obstacle to the winding on the armature core, so the coil can be wound with high precision, and the resistance value of the coil and the stress on the commutator holder can be kept low. Is possible. Furthermore, after shaping the coil,
Since the commutator unit is press-fitted into the shaft, the height of the wall provided in the commutator unit to protect the arc extinguishing element can be reduced, and the axial dimension of the motor can be reduced. Even after the commutator unit is press-fitted, interference between the coil and the arc extinguishing element can be reliably prevented.

[Brief description of drawings]

FIG. 1 is a sectional view showing an embodiment of an armature of a small DC motor according to the present invention.

FIG. 2 is a plan view of the same.

FIG. 3 is a cross-sectional view showing a part of the manufacturing process of the armature of the small DC motor of the above.

FIG. 4 is an exploded cross-sectional view showing still another embodiment of the armature of the small DC motor according to the present invention.

FIG. 5 is a cross-sectional view of the armature of the above small DC motor.

FIG. 6 is a cross-sectional view showing an example of an armature of a conventional small DC motor.

FIG. 7 is a plan sectional view showing an example of a small motor to which the armature is applied.

[Explanation of symbols]

 1 shaft 2 armature core 3 commutator unit 3a commutator holder 3b collar part 3c commutator 3d wall part 4 coil 5 arc extinguishing element

Claims (2)

[Claims] 1. An armature core and a commutator unit are axially arranged and fixed to a shaft, a coil is wound around a salient pole of the armature core, and an arc extinguishing element is fixed to the commutator unit. In a small direct current motor armature, the commutator unit includes a commutator holder having a cylindrical portion and a flange portion fitted to a shaft, and a commutator fixed to an outer peripheral surface of the cylindrical portion of the commutator holder. A small direct current motor comprising a commutator holder, and a wall that stands up in a substantially axial direction at an outer edge portion of the flange portion of the commutator holder. 2. A method for manufacturing an armature for a small direct current motor, comprising: (a) fitting and fixing an armature core to a shaft; A step of temporarily press-fitting a commutator unit including a commutator holder having an upright wall and a commutator fixed to the outer periphery of the commutator holder onto a shaft, (b) of an armature core fitted and fixed to the shaft A step of winding a coil around a salient pole, (c) a step of permanently press-fitting a commutator unit temporarily press-fitted onto a shaft, and (d) a step of shaping a coil wound around a salient pole of an armature core.