JPH0716582U - DC motor spark extinguishing device - Google Patents

Abstract

(57) [Abstract] [Purpose] Preventing arcing and extending the life of the motor. [Structure] Between each commutator piece of the cylindrical commutator piece 11, a constant voltage diode 15, 15 having a threshold voltage of 10 V or less,
Connected with 15.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a spark extinguishing device for a DC motor.

[0002]

[Prior art]

 FIG. 2 shows the configuration of a conventional general DC motor. In FIG. 1, reference numeral 1 denotes a motor case, 5 denotes side plates that close the open end of the motor case 1, and an annular magnet 2 is fixed to the inner peripheral surface of the motor case 1. A motor main shaft 6 is arranged inside the motor case 1 and the side plate 5, and the motor main shaft 6 is rotatably supported by bearings 4, 4 fixed to the motor case 1 and the side plate 5, respectively. . A rotor portion 7 around which a coil 13 is wound is fixed to a position of the motor main shaft 6 facing the magnet 2, and a commutator 8 that contacts a brush 9 is fixed to a position on the side plate 5 side. . As shown in FIG. 3, a cylindrical commutator piece (comi-segment) 11 is provided on the outer periphery of the commutator 8, and the commutator piece 11 is formed by a slit 10 formed along the axial direction. , Are electrically insulated from each other.

Here, as shown in FIG. 4, the DC motor is provided with varistors 14, 14, 14 whose both terminals are connected to the commutator piece 11, respectively. This makes it possible to prevent contact destruction due to sparks (arcs) generated during rectification. In particular, the varistor 14 is a very effective means in terms of cost versus electrical noise. 2 and 3, reference numeral 3 is a terminal, and 12 is a damper.

[0004]

[Problems to be solved by the device]

 However, the spark extinguishing device for the DC motor has the following problems. That is, as shown in FIG. 5, the arc breakdown causes a high voltage Va between the brush 9 and the commutator 8 at the time of switching the rectification, and at the same time, the brush 9 and the commutator 8 (actually, the commutator piece 11) are discharged. Since the gap d between the two is very small, an arc electric path is formed and the arc is destroyed. However, the countermeasure by the varistor 14 is not sufficient and there is a problem that the motor life is shortened. . Here, a spark arc extinguishing device using a constant voltage diode in place of the varistor 14 is described in Japanese Patent Publication No. 60-52662, and in the device described in Japanese Patent Publication No. 60-52662. However, the effect was insufficient.

Therefore, an object of the present invention is to provide a spark extinguishing device for a DC motor, in which arc generation is prevented and a long life is realized.

[0006]

[Means for Solving the Problems]

 In order to achieve the above object, the spark extinguishing device for a DC motor according to the present invention is characterized in that a constant voltage diode having a threshold voltage of 10 V or less is connected between the commutator pieces of a tubular commutator piece. I am trying.

[0007]

[Action]

 According to the spark extinguishing device of the DC motor in such means, the minimum arcing voltage is 10 to 15 V, so that a constant voltage diode having a threshold voltage of 10 V or less should be connected between the commutator pieces. In this case, the voltage between the brush and the commutator can be suppressed, and the occurrence of arc can be prevented.

[0008]

【Example】

 Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a circuit diagram of a spark extinguishing device for a DC motor showing an embodiment of the present invention. The same parts as those described in the prior art are designated by the same reference numerals, and the description thereof is omitted here. Omit it. The spark arc extinguishing device of this embodiment is different from that of the prior art in that constant voltage diodes 15, 15 and 15 each having a threshold voltage of 10 V or less are respectively connected between the commutator pieces of the cylindrical commutator piece 11. That is the point.

The constant voltage diodes 15, 15, 15 are so-called star connections in which the anodes are connected to each other, and the coils 13, 13, 13 are so-called so-called connecting each terminal to each commutator piece 11. It has a delta connection.

Here, in the gap d between the brush 9 and the commutator 8 (actually, the commutator piece 11), friction of the atoms and molecules of the contact noble metal or contact coating film is caused by the sliding of the brush 9 and the commutator 8. A plasma state has been created. When a high electric field is generated by the brush 9 and the commutator 8 at the sand dust of this atom, the electron and the cation are directed to their respective electrodes, and other neutral atoms are ionized, and the electron is repeatedly avalanche by repeating the ionization. In this way, an arc electric path is formed toward the electrode, and it is clear that the mechanism of this arc generation is triggered by the ionization of neutral atoms.

Therefore, when electrons accelerated by the electric field due to the voltage between the brush 9 and the commutator 8 collide with the contact noble metal, which is the main component of the sand dust of the atoms, the energy of the accelerated electrons is collided. If the voltage between the brush 9 and the commutator 8 is suppressed so that the contact noble metal does not reach the ionization voltage (first ionization voltage) of about 7 to 9 eV, no arc is generated.

Here, it was confirmed by the experiment of the present inventor that the minimum arc generation voltage in the minute gap d is about 10 to 15 volts.

Therefore, if a constant voltage diode having a threshold voltage of 10 V or less is connected between the commutator pieces as in this embodiment, the voltage between the brush 9 and the commutator 8 is suppressed. Ionization of neutral atoms will be suppressed, and hence arc generation will be prevented.

Although the invention made by the present inventor has been specifically described based on the embodiments, the present invention is not limited to the above-mentioned embodiments, and various modifications can be made without departing from the gist of the invention. Needless to say, for example, in the above embodiment, the constant voltage diodes 15, 15, 15 are star-connected, but when a bidirectional element is used, the varistor 14 shown in FIG. 4 is used. It is necessary to connect both terminals to each commutator piece.

Further, in the above embodiment, the coils 13, 13, 13 are delta connected, but it is also possible to use star connection.

[0016]

[Effect of device]

 As described above, according to the spark extinguishing apparatus for the DC motor of the present invention, the minimum arc generation voltage is 10 to 15 V, and the constant voltage diode having the threshold voltage of 10 V or less is provided between the commutator pieces. Since the connection is made, the voltage between the brush and the commutator can be suppressed, so that arcing is prevented and the life of the motor can be extended.

[Submission date] January 27, 1994

[Procedure Amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0004

[Correction method] Change

[Correction content]

[0004]

However, the above spark extinguishing device for a DC motor has the following problems. That is, as shown in FIG. 5, the arc breakdown causes a high voltage Va between the brush 9 and the commutator 8 at the time of switching the rectification, and at the same time, the brush 9 and the commutator 8 (actually, the commutator piece 11) are discharged. The gap d between them is so small that an arc electric path is formed, which leads to arc destruction. However, the countermeasure by the varistor 14 is effective for electric noise but insufficient for contact destruction . There is a problem that the motor life will be shortened. Here, a spark arc extinguishing device using a constant voltage diode instead of the varistor 14 is described in Japanese Patent Publication No. 60-52662, and in the device described in Japanese Patent Publication No. 60-52662. However, the effect was insufficient.

[Procedure Amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0007

[Correction method] Change

[Correction content]

[0007]

Since the minimum arcing voltage of the DC motor is 10 to 15 volts, if a constant voltage diode with a threshold voltage of 10 volts or less is connected between the commutator pieces, the voltage between the brush and the commutator will be reduced. As a result, the occurrence of arc is prevented.

[Procedure 3]

[Document name to be amended] Statement

[Correction target item name] 0016

[Correction method] Change

[Correction content]

[0016]

As described above, the minimum arcing voltage of the DC motor is 10 to 15 V, and the constant voltage diode having a threshold voltage of 10 V or less according to the present invention is connected between the commutator pieces . The spark extinguishing device allows the voltage between the brush and the commutator to be suppressed, thus preventing arcing and increasing the life of the motor.

[Brief description of drawings]

FIG. 1 is a circuit diagram of a spark extinguishing apparatus for a DC motor showing an embodiment of the present invention.

FIG. 2 is a partially cutaway front view of a DC motor showing a conventional technique.

FIG. 3 is a side view of FIG. 2 showing an enlarged view of a brush and a commutator.

4 is a circuit diagram of a spark extinguishing device applied to the DC motor of FIG.

5 is an enlarged view of a main part of FIG. 4 for explaining an arc breakdown phenomenon.

[Explanation of symbols]

 11 Commutator piece 15 Constant voltage diode

Claims (1)

[Scope of utility model registration request] 1. A spark-arc extinguishing device for a DC motor, wherein a constant voltage diode having a threshold voltage of 10 V or less is connected between each commutator piece of a tubular commutator piece.