JPS5833782B2 - Kogatachi Yokuriyu Motor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention is a small DC motor that uses an extremely simple mechanism to eliminate sparks generated between the commutator and brushes while saving resources and labor, making it possible to extend the life of the motor and eliminate noise. It is related to.

A major weakness of conventional motors using commutators is wear and deterioration between the commutator and brush portions.

In these motors, as the rotor rotates, the commutator and brushes are opened and closed in an electrical circuit each time, and as a result, the inductive energy stored in the windings in the rotor is discharged. As a result, sparks are generated, which accelerates the abrasion and deterioration of the commutator and brush as described above.

Furthermore, this spark also causes electrical noise generation.

In order to prevent this spark phenomenon, a resistor 3, a capacitor 4, or a varistor 5 is connected between the commutators 1 and 1, respectively, as shown in FIGS. 1, 2, and 3. Methods have already been put into practical use to reduce the spark current generated in the 2 are connected in parallel, which has the disadvantage of increased current consumption.

Furthermore, when using a SiC varistor as the varistor 5, for example, the varistor itself has high resistance at low voltage;
Since it is an element whose resistance suddenly decreases as the voltage increases, it is possible to reduce sparks without almost increasing the current consumption, but as shown in Figure 3, it is similar to the case of the resistor and capacitor. For example, when connecting three elements to a commutator, it requires a lot of work such as soldering and gluing to attach each element to the winding part with adhesive, and it is also difficult to balance the weight of the three elements. The disadvantage is that it requires careful consideration.

In order to provide a varistor that has extremely stable characteristics and can be miniaturized, the present inventors have already developed a varistor that has negative resistance and has a specific resistance value R8KΩ at 273°K for the constant B0 of the thermistor. The product of is 10.0OOKΩ・
An electrode made of a metal or alloy having high corrosion resistance and high electrical conductivity is brought into contact with a disk-shaped oxide semiconductor having a diameter of 0 or less, and the surface of the oxide semiconductor is contacted at the contact surface between the oxide semiconductor and the electrode. He invented an oxide semiconductor-metal contact resistance element having a structure of creating a surface barrier, and disclosed this in the specification of % Application No. 47-62588 (Japanese Patent Publication No. 52-59 Sho.
No. 95).

With the above configuration, this element creates a surface barrier on the surface of the oxide semiconductor at the contact surface between the oxide semiconductor and the electrode, and the presence of this surface barrier provides a high resistance to low voltage. Thus, as the voltage increases, the current changes, making it possible to have an extremely stable voltage-current characteristic.

That is, this element utilizes the voltage dependence of the surface barrier, and its rising voltage is 10 to 20 V, and the index α representing nonlinearity is around 5, indicating excellent nonlinearity.

Therefore, this element shows suitability as a varistor and can be easily miniaturized.

The present invention attempts to apply the above-mentioned oxide semiconductor-metal contact resistance element to extinguishing sparks generated between a commutator and a brush of a small DC motor.

That is, the present invention is an applied invention of the invention described in the specification of Japanese Patent Application No. 47-62588. The product of the specific resistance R6KΩα at K is 10
,0OOKΩcrIL0 is formed into a ring shape with the following oxide sintered body, and the ring-shaped oxide sintered body is fitted onto the outer peripheral surface of a metal piece or an alloy piece constituting a commutator. A small DC motor is characterized in that the contact surface of the fitted oxide sintered body that comes into contact with the outer peripheral surface of the metal piece or alloy piece is configured to produce a barrier resistance.

As described above, the small DC motor of the present invention is formed into a ring shape, has a negative resistance, and has a product of the constant B0 of the thermistor and the specific resistance R8KΩ·α at 273°K of 1.
When attaching the following oxide sintered body to 0,0OOKΩ・α・0, as in the case of using a conventional general varistor, it is necessary to apply electrodes by thermal spraying metal, baking silver, etc., or attach lead wires. The oxide sintered body can be manufactured using an extremely simple structure in which the oxide sintered body is simply fitted onto and brought into contact with the outer peripheral surface of the metal piece or alloy piece that constitutes the commutator 1 without requiring soldering. A barrier resistance is generated on the contact surface of the oxide sintered body, and the development of this barrier resistance causes the oxide sintered body to exhibit varistor-like voltage-current characteristics as shown in FIG. This makes it possible to eliminate sparks generated between the commutator and the brushes.

Moreover, as mentioned above, the oxide sintered body can be miniaturized, and as shown in Fig. 7, it exhibits stable varistor-like characteristics at low voltages, so it can be used for small DC currents that normally operate at low voltages. Ideal for eliminating sparks between motor commutator and brush.

As described above, the manufacturing process of the oxide sintered body used in the present invention is extremely simple compared to conventional ones, and together with the low cost of raw materials, it is possible to significantly reduce the manufacturing cost.

In FIG. 5, 1 is a commutator, 2 is a winding, 6 is a ring-shaped oxide sintered body, 1 is a rotating shaft, 8 is an iron core, 9 is a brush, and 10 is a commutator fixing plastic.

With the above-described configuration, the small DC motor of the present invention can completely eliminate sparks generated between the commutator and the brushes.When the motor of the present invention is rotated, the current flowing through the motor of the present invention can be observed using an oscilloscope. This is clear from the current waveform shown in FIG. 6B.

In the current waveform of Figure 6B, the vertical straight line representing the generation of sparks is extremely short, which indicates that the spark has completely disappeared; The section is extremely long, indicating the generation of sparks.

273° to the constant B0 of the sinter of the above oxide sintered body
Product of specific resistance R6KΩ at K is 10.0OOK
If ΩcIrL0 has the following Tef, K, etlJ(27
If it is due to the specific resistance R6K, Qn at 3°Kl, it is essentially impossible to completely eliminate the spark, and if this R8 is high, the nonlinearity shown in Fig. 7 will worsen,
In addition, if the thermal stability is due to the constant B0K of the thermistor, the thermal stability will be significantly reduced, and if it is due to both Bo and R8KΩα, the above two drawbacks will be included, so the oxide sintered BXRo is 10,0
It is required that OOKΩCrl10 be as follows.

The oxide sintered element in the present invention utilizes only the barrier resistance generated on the contact surface when it comes into contact with the outer peripheral surface of the commutator;
Compared to C varistors, etc., as shown in FIG. 1, the rising voltage is stable at around 20V, and the variation is small, so the quality is extremely stable.

As described above, the present invention provides a small DC motor with an extremely simple configuration, which saves resources and labor, has far superior spark extinguishing performance than conventional motors, and is extremely inexpensive to manufacture. Its industrial value is extremely high.

Next, the present invention will be explained in more detail with reference to Examples, but the present invention is not limited to the following Examples unless it exceeds the gist thereof.

Example 0.5 mole of copper oxide was added to 1 mole of ferric oxide, thoroughly ground and mixed in a pot mill, dried in a drier, and then pressure-molded at a pressure of about It/m. 1,000
Firing was performed in air at a high temperature of .degree. C. or higher to obtain a thin ring-shaped oxide sintered body 6 as shown in FIGS. 4A and 4B.

Aluminum is vapor-deposited and baked on both sides of this oxide sintered body 6 to form ohmic electrodes.
When measured, R8 was 2. OKΩam, f3 is 4.
0000 and 1. RoXB=8,0OOKΩCrr
It was at L0.

When applying this oxide sintered body 6 to a small motor,
As shown in FIG. 5, it was fitted onto the outer peripheral surface of the commutator 1, brought into contact with it, and fixed.

Since this sintered body 6 has the same diameter as the outer circumference of the commutator 1, it can be fixed without using adhesive.

The circuit of the motor of this embodiment constructed in this manner is completely the same as that shown in FIG. 3.

When the motor of this embodiment was rotated, the sparks that had been generated between the brush 9 and commutator 1 of the conventional motor completely disappeared.

Furthermore, when the current flowing through the motor of this example was observed using an oscilloscope, a current waveform as shown in FIG. 6B was obtained.

However, the current waveform shown in FIG. 6A is the case where this element for the purpose of eliminating sparks was not used in the commutator.

As is clear from these, the spark phenomenon is completely eliminated in the small DC motor of the present invention.

[Brief explanation of drawings]

1 to 3 are equivalent connection circuits of a resistor, a capacitor, and a varistor, respectively; FIGS. 4A and B are a plan view and a sectional view of an example of the shape of the oxide sintered body of the present invention; and FIG. Figure 4 is an explanatory diagram of the small DC motor of the present invention in which the oxide sintered element is fitted and contacted with the outer circumferential surface of the commutator, and Figure 6 is the current flowing through the motor observed with an oscilloscope. In the waveform diagram, A is the case of a conventional motor that does not use the present oxide sintered body element, and B is the case where the present oxide sintered body element is used. FIG. 7 shows the voltage-current characteristics of the present oxide sintered body shown in FIG. 4 when metal is brought into contact with both surfaces of the present oxide sintered body. In addition, the horizontal axis of FIG. 6 shows time, the vertical axis shows current, and the horizontal axis of FIG. 7 shows voltage, and the vertical axis shows current. In the figure, 1... commutator, 2... winding, 3... resistor, 4... capacitor,
5...Barista, 600. ... Ring-shaped oxide sintered body, γ ... Rotating shaft, 8 ... 11. Iron core, 9... Brush, 10... Commutator fixing plastic.

Claims (1)

[Claims] 1 has a negative resistance and the constant B0 of the thermistor is 27
The product with the specific resistance R8KΩα at 3°K is 10.0O
The following oxide sintered body is formed into a ring shape in OKΩcIn0, and the ring-shaped oxide sintered body is fitted onto the outer circumferential surface of a metal piece or an alloy piece that constitutes a commutator, and the fitting is performed. A small DC motor characterized in that a contact surface of the oxide sintered body that contacts the outer peripheral surface of the metal piece or alloy piece generates barrier resistance.