JPH08308184A - Small-sized motor - Google Patents

Abstract

PURPOSE: To prevent the service life of a motor from becoming shorter by preventing a brush from cutting a commutator with a simple structure. CONSTITUTION: A small-sized motor is incorporated with a rotor 3 which is rotated on the inside of permanent magnets 9 fixed to the internal surface of a frame 1. A plurality of sets of iron cores 10 wound with windings 8 and commutators 5 insulated from a rotating shaft 4 are fixed to the rotor 3. A brush 6 is electrically connected to the commutators 5 in slidable states to energize the windings 8. Each commutator is constituted in such a way that its riser 5a side which is connected to the winding 8 is made thicker than the other side. Since the riser 5a side of the piece 5 is thick, the riser 5a side of the commutator 5 is not cut even when the commutator 5 is unevenly worn and the service life of the motor can be prevented from becoming shorter. In addition, it is not required to manufacture the sliding surface of the brush with high accuracy and the brush can be manufactured easily.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a small motor used for, for example, an electric razor, and more particularly to a small motor having a commutator fixed to a rotor as a special structure.

[0002]

2. Description of the Related Art FIG. 1 shows a sectional view of a small motor disclosed in Japanese Utility Model Laid-Open No. 1-150465. In the motor shown in this figure, the permanent magnet 9 is fixed to the inner surface of the frame 1,
The rotor 3 is arranged inside the permanent magnet 9 so as to be rotatable. The rotor 3 has a rotating shaft 4 attached to the center of the bracket 2 so as to be rotatable. The rotor 3 has a winding 8 fixed to a rotating shaft 4. A commutator 5 is fixed to the rotating shaft 4 to energize the winding 8. The commutator 5 is insulated and fixed to the outer circumference of the rotary shaft 4. Rotor 3
Has a plurality of sets of windings 8. In order to energize the respective windings 8, the commutator 5 is divided into the same number as the number of the windings 8 and fixed to the rotating shaft 4. FIG. 2 shows a structure in which the commutator is insulated and fixed to the rotating shaft. In the commutator 5 shown in this figure, an insulating cylinder 7 is inserted into a rotating shaft (not shown), and the commutator 5 is fixed to the outer peripheral surface of the insulating cylinder 7.

A brush 6 is elastically pressed against the commutator 5. The brush 6 is energized to the winding 8 via the commutator 5.
The brush 6 is mounted on the bracket 2 insulatively.

[0004]

In the small motor shown in FIG. 1, the brush 6 and the commutator 5 are energized to the winding 8 while the brush 6 and the commutator 5 slide. Wear out. The brush 6 is made of a conductive powder such as carbon and formed into an elongated shape so that the brush 6 is pressed against the commutator 5 with a predetermined pressure even if it is worn to some extent. The commutator 5 is formed by forming a copper plate into a cylindrical shape and vertically dividing it into, for example, three parts. The small motor shown in FIG. 1 divides the brush 6 into three parts in order to connect the brush 6 to the commutator 5 more reliably. The brush 6 having this structure has a feature that any one of the three divided parts contacts the commutator 5 and energizes the winding 8, so that the winding 8 can be energized reliably.

However, in the small motor having this structure, the commutator 5 may be unevenly worn and the life thereof may be significantly shortened. As shown in the enlarged sectional view of FIG.
If the brush 6 on the side of the riser 5a that is connected to is protruded, the commutator 5 that is pressed and slid by the protruding portion may be extremely worn and cut. Riser 5
If the commutator 5 is cut at a portion near the a side, even if a part of the commutator 5 that is not worn contacts the brush 6, the winding 8 is not energized. This is because the unevenly worn cutting portion electrically disconnects the commutator 5 sliding on the brush 6 from the riser 5a side.

The same problem occurs in a small motor that presses the commutator 5 with the brush 6 that is not divided into a plurality of parts. This is because, as shown in FIG. 4, if the sliding surface of the brush 6 projects on the riser 5a side, the projecting portion will partially wear the commutator 5 and cut it. In this state, although most parts of the commutator 5 are normally in contact with the brush, the winding 8 cannot be energized, and the life of the motor is significantly shortened.

The present invention was developed for the purpose of solving this drawback. An important object of the present invention is to provide a small motor that can effectively prevent the brush from locally protruding to cut the commutator 5 and shorten the life of the motor.

[0008]

[MEANS FOR SOLVING THE PROBLEMS] The small motor of the present invention has the following constitution in order to achieve the above-mentioned object.
The small motor has a brush 6 that energizes the winding 8, and a commutator 5 that is electrically connected to the brush 6 in a sliding state and is itself fixed to the rotor 3. Winding 8 of rotating rotor 3 via brush 6 and commutator 5.
Is configured to be energized.

Further, in the small motor of the present invention, the thickness of the commutator 5 which is insulated and fixed to the rotating shaft 4 of the rotor 3 is made thicker on the riser 5a side connecting the winding 8 than the other end. It has a unique structure.

[0010]

In the small motor of the present invention, as shown in FIGS. 5 and 6, the commutator 5 is thickened on the riser 5a side. As shown in the cross-sectional view of FIG. 6, in the motor of this structure, even if the brush 6 on the riser 5a side is protruding, this portion is thickened, so the commutator 5 is cut by the protruding brush 6. There is no. The thick commutator 5 on the riser 5a side is not cut even if the brush 6 is considerably worn, and the commutator 5 is reliably electrically connected to the brush 6. Therefore, there is a feature that the failure of the motor due to the uneven wear of the commutator 5 can be very effectively prevented.

[0011]

Embodiments of the present invention will be described below with reference to the drawings. However, the examples shown below exemplify a small motor for embodying the technical idea of the present invention, the small motor of the present invention, the material, shape of the components,
The structure and layout are not specified below. The small motor of the present invention can be modified without departing from the scope of the claims.

Further, in this specification, for easy understanding of the claims, the numbers corresponding to the members shown in the embodiments are referred to as "claim column", "action column", and "action column". It is added to the members shown in the section of "Means for Solving the Problems". However, the members shown in the claims are
It is by no means specific to the members of the examples.

The small motor shown in FIG. 7 has a plastic frame bracket 2 fixed to both ends of a metal frame 1 to form a casing. A permanent magnet 9 is fixed to the inner surface of the frame 1. The bracket 2 is provided around a through hole through which the rotary shaft 4 of the rotor 3 is rotatable so as to be rotatable. A pair of brushes 6 is attached to one bracket 2. The brush 6 has a structure similar to that of a small motor currently on the market, and is mounted on the bracket 2 so as to be elastically pushed out in the axial direction via a spring (not shown). Further, the brush 6 is connected to a terminal 11 fixed to the bracket 2 via a lead wire (not shown).

The brush 6 shown in FIGS. 6 and 7 has its tip divided into three parts in the direction of the center of the rotary shaft 4 in order to electrically connect the commutator 5 more stably. However, in the small motor of the present invention, the brush does not necessarily have to be divided into a plurality of pieces, and the entire tip surface of the brush can be slid on the commutator.

A rotor 3 is rotatably supported on the bracket 2. The rotor 3 fixes a plurality of sets of windings 8 and a commutator 5 to a rotating shaft 4. The winding wire 8 is wound around a laminated iron core 10 fixed to the rotating shaft 4. Three sets of windings 8 are radially wound around the rotor 3. However,
There may be two windings or more than three windings. The tip of the winding 8 is connected to the riser 5 a of the commutator 5. The winding 8 is energized via the commutator 5 and the brush 6.

The commutator 5 is fixed to the rotating shaft 4 via an insulating cylinder 7. The insulating cylinder 7 is made of plastic, and the commutator 5 is formed into a cylindrical shape along the surface of the cylindrical insulating cylinder 7, and has a riser 5a at one end as shown in FIG. The commutator 5 shown in FIG. 5 is divided into three in order to connect to three sets of windings. Further, in the commutator 5 shown in FIG. 5, the wall thickness on the riser 5a side for connecting the winding is made thicker than the other end. In the commutator 5 shown in the figure, the outer diameter is the same, the inner diameter of the upper end on the riser 5a side is smaller, the inner diameter of the lower end is larger than the upper end, and the wall thickness on the riser 5a side is thicker than the lower end. ing. That is, the inner diameter of the commutator 5 is set to the riser 5
The thickness on the riser 5a side is made thicker by making the taper shape smaller on the a side. The commutator 5 having a tapered inner surface and a thicker wall on the riser 5a side can have the same outer shape. Therefore, the tip of the brush 6 can contact the commutator 5 with the same protrusion amount.

In order to fix the commutator 5 whose inner surface is tapered, the insulating cylinder 7 is formed such that the outer peripheral surface is tapered so as to be in close contact with the inner surface of the commutator 5. Further, the insulating cylinder 7 shown in FIG. 5 has a collar 7a integrally formed at the lower end. For the collar 7a,
A ring-shaped fitting groove 1 for fitting and fixing the tip of the commutator 5.
3 are provided. Further, the rotating shaft 4 is located at the center of the insulating cylinder 7.
Through the central hole 14 through which the The inner diameter of the central hole 14 is approximately equal to the outer diameter of the rotary shaft 4, or is slightly smaller than the outer diameter of the rotary shaft 4 so that the rotary shaft 4 can be inserted without rotating. .

In the commutator 5 shown in FIG. 5, the inner diameter of the commutator 5 is reduced on the riser 5a side to increase the wall thickness on the riser 5a side. Make the inner diameter the same and increase the outer diameter on the riser 5a side,
The wall thickness on the riser 5a side can be increased. In the small-sized motor having this structure, in order to bring the brush 6 into surface contact with the commutator 5, it is necessary to reduce the protrusion amount of the brush 6 in contact with the commutator 5 on the riser 5a side. Further, the commutator 5 can be fixed by making the outer diameter of the insulating cylinder 7 the same.

The rotor 3 shown in FIGS. 6 and 7 has a rotary shaft 4
The iron core 10 is fixed to the wire, the winding 8 is applied, the insulating cylinder 7 is passed through the rotating shaft 4, and the commutators 5 are fixed on the surface of the rotating shaft 4 at equal intervals. Is produced. In order to fix the commutator 5 to the outer circumference of the insulating cylinder 7, the fixing ring 12 is inserted through the commutator 5, and the tip of the commutator 5 is inserted into the fitting groove 13 of the insulating cylinder 7.

[0020]

The small motor of the present invention has a feature that it can effectively prevent the problem that the brush 6 cuts the local part of the commutator and the life of the motor is significantly shortened. This is because the miniature motor of the present invention has a thicker wall on the riser side of the commutator than other portions. When the commutator is worn and cut off on the riser side, the winding cannot be energized even if the other parts normally contact the brush. Since the small motor of the present invention has a thicker wall on the riser side of the commutator, even if the commutator is unevenly worn and the riser side is worn more than other portions, this portion is thickened. , There is no disconnection near the riser side. For this reason, it is possible to effectively prevent the commutator from being unevenly worn and significantly shortening the life of the motor. In addition, even if the riser side of the brush protrudes slightly and wears the commutator unevenly,
Since the life of the brush is not shortened, it is not necessary to manufacture the sliding surface of the brush with high precision, and the brush can be easily manufactured.

[Brief description of drawings]

FIG. 1 is a sectional view of a conventional small motor

FIG. 2 is an exploded perspective view of a commutator of the small motor shown in FIG.

FIG. 3 is an enlarged cross-sectional view showing a state in which a commutator of a conventional small motor is unevenly worn.

FIG. 4 is an enlarged cross-sectional view showing a state in which a commutator of a conventional small motor is unevenly worn.

FIG. 5 is an exploded perspective view of a commutator of a small motor according to an embodiment of the present invention.

FIG. 6 is an enlarged cross-sectional view showing a state in which the commutator of the small-sized motor of the embodiment of the present invention is unevenly worn.

FIG. 7 is a sectional view showing a small motor according to an embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Frame 2 ... Bracket 3 ... Rotor 4 ... Rotating shaft 5 ... Commutator 5a ... Riser 6 ... Brush 7 ... Insulation cylinder 7a ... Collar 8 ... Winding 9 ... Permanent magnet 10 ... Iron core 11 ... Terminal 12 ... Fixing ring 13 … Fit groove 14… Center hole

Claims (1)

[Claims] 1. A brush having a brush (6) and a commutator (5) electrically connected to the brush (6) in a sliding state and fixed to the rotor (3) by itself. (6) is a commutator
In a small motor configured to energize the winding (8) of the rotating rotor (3) via (5), it is insulated and fixed to the rotating shaft (4) of the rotor (3) The commutator (5) has the wall thickness on the riser (5a) side connecting the winding (8),
A small motor that is thicker than the other end.