JPH0670521A - Small four-pole dc motor - Google Patents

Abstract

PURPOSE:To reduce the variation in torque generated in a four-pole DC motor, by serially connecting coils that are opposite at an angle of 180 degrees, connecting each end of the coils to every other commutator out of six commutators while the other three ends are connected together, and fitting two brushes having an opening angle of 90 degrees smoothly to a commutator member. CONSTITUTION:Each pair of armature coils 2 (A and A, B and B or C and C) put at an angle of 180 degrees are connected in series. A commutator 3 is made up of six commutator members. The commutator members (3-1 and 3-4, 3-2 and 3-5 or 3-3 and 3-6) put in an opposite pair at an angle of 180 degrees are connected inwardly. An end of the coils 2 (A and A) is connected to the armature member 3-1, an end of coils 2 (B and B) to the armature member 3-3, and an end of coils 2 (C and C) to the armature member 3-5 while the other ends of the coils (A, B, and C) are connected together. Two brushes 4 having an opening angle of 90 degrees are put at an angle of 30 degrees to a neutral line of a field pole 1 so that the brushes 4 are fitted smoothly to the commutator member. Then, the brushes 4 are connected to positive and negative electrodes of a power supply.

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 armatures in which coils are wound around six salient poles facing four poles.

[0002]

2. Description of the Related Art FIG. 3 is a cross-sectional view showing a structure of a conventional small-sized DC motor having four field poles and armatures in which coils are wound around six salient poles facing each other. Four
Is a development view showing the relationship among the field poles, armature windings, commutator pieces and brushes of the small DC motor shown in FIG.
No. 11894. Since FIG. 3 is described in detail in the above-mentioned publication, the description thereof will be omitted,
The development view shown in FIG. 4 will be described. 1 in FIG.
Is a permanent magnet forming a field pole and is magnetized to have four poles.
Reference numeral 2 denotes an armature coil, and for convenience sake, a coil wound around one magnetic pole is represented as a one-turn coil. The armature coils 2 are located at symmetrical positions of 180 degrees, A and A, respectively.
And B, B and C, C are respectively connected in series, and 3 is a commutator having six commutator pieces 3-1 and 3-4, 3-
2 and 3-5 and 3-3 and 3-6 are connected to each other internally at symmetrical positions of 180 degrees, and one end of the coil A + A is connected to the commutator piece 3-1 and the other end is connected. Is commutator piece 3
-5, one end of the coil B + B is a commutator piece 3-3, the other end is a commutator piece 3-1, and one end of the coil C + C is a commutator piece 3
-3, and the other end is connected to the commutator piece 3-5, respectively.
The two brushes 4 make contact with the commutator element 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 the figure, and the power source +,
It is connected to the-terminal. And the symbol shown,
,,, indicate the position number of the coil side, and the arrow in the coil indicates the direction of the current at the position shown in the figure.

The torque generated by the DC motor is determined by the product of the magnetic flux of the field poles orthogonal to the coil and the coil current, and it is well known that this value is proportional to the counter electromotive force of the coil at this time. By showing the rough estimation of the back electromotive force generated on the coil side, the rough estimation of the generated torque at this time can be known. If the magnetic flux distribution in the air gap of the field pole is approximately a sine wave, the magnitude of the back electromotive force changes from 0 (small), (medium), (large) depending on the position of the coil side with respect to the field pole. I will. At the position shown in FIG. 4, there are two routes C + C and A + A + B + B between + and − of the brush 4. The counter electromotive force of the route of coil C + C is (middle) + (middle) +
(Middle) + (Middle) The counter electromotive force of the route of coil A + A + B + B is (Middle) +
(Middle) + (Middle) + (Middle), and at this position the back electromotive force is almost equal on any route, but the number of coils is 2 on the one hand,
On the other hand, it is unbalanced with 4 pieces.

[0004]

Next, when the armature is slightly rotated from the position shown in FIG. 4 to the position shown in FIG. 5, there are two routes C + C and B + B between + and − of the brush 4. ,
A + A is short-circuited with a brush. Considering the rough 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 route of coil A + A has a short circuit with zero back electromotive force. The back electromotive force of the route of coil B + B is (small) + (large) +.
It becomes (small) + (large), and the back electromotive forces are substantially equal on routes C + C and B + B, which are effective for torque generation, and the number of connected coils is two. As described above, the number of coils connected in series between the positive and negative brushes varies depending on the contact position of the brush due to rotation, and accordingly the resistance changes, which causes a problem that the current changes and the torque changes. It is an object of the present invention to obtain a DC motor in which the number of series coils connected between the brushes does not change regardless of the position of the armature, a stable current flows, and the fluctuation of generated torque is small.

[0005]

The DC motor according to the present invention has a 180-degree symmetry of a coil wound around each armature having six salient poles facing a field pole magnetized to four poles. Connected in series, and one end of each of them is connected to every other six commutator pieces internally connected to the commutator pieces at symmetrical positions of 180 degrees, and the other end of the coil is connected. Two of the three commutator pieces are connected to each other and have an opening angle of 90 degrees.
The purpose is achieved by the configuration in which individual brushes are in sliding contact.

[0006]

With the configuration 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 working effect that decreases.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows field poles of a DC motor according to the present invention,
FIG. 2 is a development view showing the relationship between the armature coil, the commutator piece, and the brush, and FIG. 2 is a development view showing the relational position when the armature slightly rotates and the position changes in the development view of FIG. In FIG. 1, 1 is a field pole magnetized to have 4 poles, 2 is an armature coil, and A and A, B and B, and C and C are located at 180-degree symmetrical positions, respectively, and are connected in series. The commutator 3 has six commutator pieces, and commutator pieces 3-1 and 3-4, 3-2 and 3-5.
The commutator pieces 3-3 and 3-6 are respectively connected internally at symmetrical positions of 180 degrees, and one end of the coil A + A connected in series is connected to the commutator piece 3-1 and the other of the coils B + B is connected. One end of the coil C + C is connected to the commutator piece 3-5, and one end of the coil C + C is connected to the commutator piece 3-5, respectively, and the coils A + A, B + B, and C are connected.
The three other ends 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 the position of 30 degrees from the neutral line of the field pole 1 and are slidably contacted to be connected to + and-of the power source.

At 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. When the rough calculation of the back electromotive force of each coil of the armature at this time is shown according to the above method, the back electromotive force of root C + A is (middle) + (middle) + (middle) +
(Medium) + (Medium) + (Medium) The counter electromotive force of root C + B is (Medium) + (Medium) + (Medium) +
(Medium) + (Medium) + (Medium), and both routes have approximately the same value. In addition, the number of coils in each of the two routes is equal to four.

At the position of FIG. 2 slightly rotated from the position of FIG. 1, there is one route B + B + C + C between the positive and negative brushes, and the route A + A is open and no current flows. Considering the back electromotive force at this position, the back electromotive force 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 effective, and four coils are connected between the positive and negative brushes.

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

[0011]

The DC motor according to the present invention shown in FIG. 1 has a coil wire diameter of about 1.4 times that of the DC motor according to the prior art shown in FIG. 3 without changing the structural dimensions of the main parts. When the number of windings is halved, the resistance and voltage between the brushes are substantially the same, the average torque is the same, and there is an effect that an electric motor with a small torque ripple can be obtained.

[Brief description of drawings]

FIG. 1 is a development view showing a correlation between a field pole, an armature coil, a commutator piece, and a brush of a four-pole small DC motor according to the present invention.

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

FIG. 3 is a cross-sectional view showing the structure of a conventional small DC motor.

FIG. 4 is a field pole of a 4-pole small DC motor according to the related art;
It is a development view showing correlation with an armature coil, a commutator piece, and a brush.

5 is a development view of the conventional motor shown in FIG. 4 in which 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 One: ,,,,: Position number of armature coil side 4: Brush

Claims (1)

[Claims] 1. A magnetic field pole magnetized to have four poles and a magnetic pole 6 facing each other.
A coil wound around each magnetic pole of an armature having a plurality of salient poles is connected in series at 180-degree symmetrical positions, and one end of each of the three sets of coils connected in series is connected at 180 degrees. The commutator pieces at symmetrical positions are connected to every other six commutator pieces that are internally connected to each other, and the other three of the three coils are connected to each other, and the commutator pieces are connected to each other. A four-pole small DC motor characterized by sliding two brushes with an opening angle of 90 degrees.