JP2660642B2 - 4 pole small DC motor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a DC motor, and more particularly to a DC motor having an armature in which coils are wound around six salient poles opposed to four field poles.

[0002]

2. Description of the Related Art FIG. 3 is a cross-sectional view showing the structure of a small DC motor having four field poles and an armature in which coils are wound around six salient poles opposed to each other. 4
3 is a developed view showing the relationship between the field poles, armature windings, commutator pieces and brushes of the small DC motor shown in FIG.
No. -11894. FIG. 3 is described in detail in the above publication of the prior art, and its description is omitted.
The development shown in FIG. 4 will be described. In FIG.
Is a permanent magnet that forms a field pole and is magnetized to four poles.
Numeral 2 denotes an armature coil, and the coil wound around one magnetic pole is represented as a single-turn coil for convenience. The coils 2 of the armature are A, A at 180 ° symmetrical positions, respectively.
, B, B and C, C are connected in series, respectively, and 3 is a commutator having six commutator pieces, and commutator pieces 3-1 and 3-4,3-
2 and 3-5 and 3-3 and 3-6 are connected to each other at 180 degrees symmetrical positions, respectively. One end of the coil A + A is connected to the commutator piece 3-1 and the other end is connected to the other end. Is commutator piece 3
-5, one end of the coil B + B is on the commutator segment 3-3, the other end is on the commutator segment 3-1 and one end of the coil C + C is on the commutator segment 3
-3, and the other end is connected to a commutator piece 3-5, respectively.
The two brushes 4 contact the commutator piece at a position of 45 degrees from the neutral line of the field pole 1 at an opening angle of 90 degrees as shown in FIG.
Connected to the negative terminal. And the symbol shown,
,,, indicate the position numbers of the coil sides, and the arrows in the coils indicate the direction of the current at the positions shown in the figure.

[0003] The torque generated by a DC motor is determined by the product of the magnetic flux of a field pole perpendicular to the coil and the coil current, and it is known that this value is proportional to the back electromotive force of the coil at this time. When the rough calculation of the back electromotive force generated on the coil side is shown, the rough calculation of the generated torque at this time can be known. Assuming that the magnetic flux distribution in the gap of the field pole is substantially sinusoidal, the magnitude of the back electromotive force varies from 0 (small), (medium), and (large) depending on the position of the coil side with respect to the field pole. It shall be. In the position of FIG. 4, two routes of C + C and A + A + B + B exist between + and-of the brush 4. The back electromotive force of the route of the coil C + C is (medium) + (medium) +
(Medium) + (Medium) The back EMF of the route of coil A + A + B + B is (Medium) +
(Medium) + (medium) + (medium), and at this position, the back electromotive force is almost equal in any of the routes, but the number of coils on the other hand is two,
On the other hand, it is unbalanced with four pieces.

[0004]

Next, when the armature rotates slightly from the position shown in FIG. 4 to the position shown in FIG. 5, two routes C + C and B + B exist between + and-of the brush 4. ,
A + A is short-circuited by a brush. Considering the calculation of the back electromotive force of the coil at this time, the back electromotive force of the route of the coil C + C is (small) + (large) +
(Small) + (Large) The back EMF of the route of coil A + A is zero and the back EMF is zero. The back EMF of the route of coil B + B is (Small) + (Large) +
(Small) + (Large), and the back electromotive force is substantially equal in the routes C + C and B + B effective for torque generation, and the number of connected coils is two each. As described above, the number of coils connected in series between the positive and negative brushes differs depending on the contact position of the brushes due to the rotation, so that the resistance changes. Therefore, there arises a problem that the current changes and the torque changes. It is an object of the present invention to provide a DC motor in which the number of series coils connected between brushes does not change regardless of the position of an armature, a stable current flows, and the generated torque does not vary much.

[0005]

SUMMARY OF THE INVENTION A DC motor according to the present invention has a 180-degree symmetry of coils wound around an armature having six salient poles opposed to field poles magnetized to four poles. Are connected in series, one end of which is connected to every other six commutator pieces internally connected to the commutator pieces located at 180 ° symmetrical positions, and the other end of the coil is connected to the other end of the coil. 3 are connected to each other, and the commutator strip has an opening angle of 90 degrees.
The object is achieved by a configuration in which the brushes are in sliding contact with each other.

[0006]

According to the structure of the present invention, the number of coils connected between the two brushes is always the same with the rotation of the armature, so that the resistance does not change and the same current flows. There is a smaller effect.

[0007]

FIG. 1 shows a field pole of a DC motor according to the present invention;
FIG. 2 is a developed view showing a relationship between the armature coil, the commutator piece and the brush, and FIG. 2 is a developed view showing a related position when the armature is slightly rotated to change the position in the developed view of FIG. In FIG. 1, 1 is a field pole magnetized to 4 poles, 2 is an armature coil, A and A, B and B, and C and C are respectively located at symmetrical positions of 180 degrees, and are respectively connected in series. The commutator 3 has six commutator pieces, and the commutator pieces 3-1 and 3-4, 3-2 and 3-5.
3-3 and 3-6 respectively have commutator pieces at 180-degree symmetrical positions connected internally, and one end of the series-connected coil A + A is connected to the commutator piece 3-1 and the coil B + B is connected to the other. One end is connected to the commutator piece 3-3, and one end of the coil C + C is connected to the commutator piece 3-5, and the coils A + A, B + B and C are connected.
The other three of + C are connected to each other. Two brushes 4 having an opening angle of 90 degrees are arranged on the commutator piece with reference to a position 30 degrees from the neutral line of the field pole 1 and slidably contacted and connected to + and-of the power supply.

In the position shown in FIG. 1, there are two routes C + C + A + A and C + C + B + B between the positive and negative brushes. C + C is common to both. If the rough calculation of the back electromotive force of each coil of the armature at this time is shown according to the above-mentioned method, the back electromotive force of the route C + A is (medium) + (medium) + (medium) +
(Medium) + (Medium) + (Medium) The back EMF of route C + B is (Medium) + (Medium) + (Medium) +
(Medium) + (Medium) + (Medium), and the two routes have substantially the same value. Also, the number of coils in each of the two routes is equal to four.

Next, at the position shown in FIG. 2 slightly rotated from the position shown in FIG. 1, one route of B + B + C + C exists between the positive and negative brushes, and the A + A route is open and no current flows. Considering the back EMF at this position, the back EMF of route B + C is (large) + (small) + (large) +
(Small) + (Large) + (Small) + (Large) + (Small) Route A + A is open In this case, only route B + C is valid, and four coils are connected between the positive and negative brushes.

In the DC motor coil according to the present invention shown in FIG. 1, two routes of C + A, C + B and B + C are always connected in series as shown in the study of the calculation of the back electromotive force. Assuming that the resistance of one coil is R, the resistance of each route is the same at 4R, so that the same current flows, so that almost the same torque is generated, and the variation of the torque is small.

[0011]

The DC motor according to the present invention has the above-described configuration, so that the number of coils of the armature connected between the positive and negative brushes is the same and the current supplied is substantially the same regardless of the change in the position of the rotor. Therefore, an electric motor with little torque ripple can be obtained. Further, if the wire diameter of the coil is made about 1.4 times and the number of turns is reduced to 1/2 without changing the structure and dimensions of the DC motor of the prior art shown in FIG. Has substantially the same resistance and voltage, and has the effect of obtaining a DC motor having the same average torque and little torque ripple.

[Brief description of the drawings]

FIG. 1 is a developed view showing a correlation among a field pole, an armature coil, a commutator piece, and a brush of a 4-pole miniature DC motor according to the present invention.

FIG. 2 is a development view of the four-pole miniature DC motor according to the present invention shown in FIG. 1 at a position where the armature is slightly rotated.

FIG. 3 is a cross-sectional view showing the structure of a small DC motor according to the related art.

FIG. 4 shows a field pole of a four-pole miniature DC motor according to the prior art;
It is a development view which shows the correlation with an armature coil, a commutator piece, and a brush.

5 is a development view of the prior art motor shown in FIG. 4 at a position where the armature is slightly rotated.

[Explanation of symbols]

1: field pole (permanent magnet) 2: armature coil (A, B, C) 3: commutator 3-1, 3-2, 3-3, 3-4, 3-5, 3-6: commutator Piece,,,,: Position number of armature coil side 4: Brush

Claims (1)

(57) [Claims] A field pole magnetized to four poles and a field pole opposed to six poles.
The coils wound around each magnetic pole of the armature having the salient poles are connected in series at 180-degree symmetric positions, and one end of each of the three sets of coils connected in series is connected to the 180-degree coil. The commutator segments at symmetrical positions are connected to every other six commutator segments connected internally, and the other three of the three sets of coils are connected to each other and connected to the commutator segments. A four-miniature DC motor, characterized in that two brushes having an opening angle of 90 degrees are brought into sliding contact with each other.