JPH0754948Y2 - DC tacho generator - Google Patents

Description

[Detailed description of the device]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a DC tacho generator with a brush capable of accurately detecting the speed of a motor or the like.

[0002]

2. Description of the Related Art Conventionally, a DC tachogenerator with a brush has a structure in which one brush is connected to each of the "+" and "-" terminals and each brush is pressed against a commutator by a spring. It is common. In addition, when the brush of the tacho-generator splashes when the motor is running and the output momentarily drops to 0 V when the brush moves away from the commutator, connect multiple brushes to one terminal There is a device that stochastically suppresses the occurrence (for example, Japanese Utility Model Laid-Open No. Sho 63-90964).

[0003]

However, the above structure has a drawback that a resonance state may occur at a specific rotation speed and the contact state of the brush may be deteriorated, so that the obstacle cannot be completely prevented. . SUMMARY OF THE INVENTION An object of the present invention is to provide a DC tacho-generator capable of accurate speed detection without any output failure.

[0004]

This invention SUMMARY OF THE INVENTION are a plurality of brushes connected to one terminal, in the DC tachometer so as to slide said plurality of brushes commutator surface, at least one The brush material has high wear resistance
And the rest of the brush material is highly abrasive.
In addition, the one or more brushes should be replaced with high spring pressure springs.
Therefore, press it against the commutator and spring the remaining brush.
The spring is pressed against the commutator by a low pressure spring .

[0005]

Since the spring pressures of the compression springs of the two brushes connected to one terminal are different, the resonance frequencies of the brushes are also different, and one compression spring resonates due to vibration such as rotation of the rotor. Even if the brush floats from the commutator surface, the other compression spring does not resonate, so the other brush slides normally on the commutator surface. Therefore, at least one of the brushes is always in contact with the commutator, so that the output between the terminals does not momentarily drop to 0V. Also, the brush with the higher spring pressure is wear-resistant.
The material of the brush that has a lower spring pressure
As it is made of highly abrasive material, multiple brushes have a long service life.
Can keep the balance of.

[0006]

Embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a side sectional view showing an embodiment of the present invention, in which a rotor 3 facing a magnet 2 provided inside a stator 1 with a gap interposed between brackets 4 attached to both end surfaces of the stator 1.
Supported by bearings 5. The rotor 3 is provided with a commutator 6, the stator 1 is provided with two brush holders 7, and each brush holder 7 is fixed with a terminal 71 connected to "+" or "-". Groove 72,
A sliding hole 74 for accommodating the two brushes 8A and 8B connected to the terminal 71 through the lead wire 73 so as to be slidable toward the surface of the commutator 6 and arranged in the axial direction is provided. There is. Compression springs 9A and 9B are mounted between the brushes 8A and 8B and the terminal 71, respectively, and the brushes are pressed against the commutator surface by a force corresponding to the spring pressure of each compression spring. The brush 8A is made of a material having wear resistance, and the compression spring 9A has a relatively high spring pressure. The material of the brush 8B is a brush having low abrasion resistance but high abrasiveness, and the compression spring 9B is the compression spring 9A.
The spring pressure is set to be lower than that of, and the balance of the brush life is maintained. Therefore, since the spring pressures of the compression springs 9A and 9B are different, the resonance frequency of the brush is also different, and even if one compression spring resonates due to vibration such as rotation of the rotor and the brush floats above the commutator surface, the other compression Since the spring does not resonate, the brush slides normally on the commutator surface, and either brush always contacts the commutator, which may cause a failure such that the output between terminals momentarily drops to 0V. There is no such thing. It should be noted that the number of brushes connected to one terminal is not limited to two, and three or more brushes may be provided depending on the state of vibration occurrence.

[0007]

As described above, according to the present invention, a DC tachogenerator having a plurality of brushes connected to one terminal.
Balance the life of multiple brushes
I'm changing the resonance frequency of multiple brushes
And at least one during the life of the brush
Brush always comes into contact with the commutator surface to obtain stable output
There is an effect that can be.

[Brief description of drawings]

FIG. 1 is a side sectional view showing an embodiment of the present invention.

[Explanation of symbols]

 1 Stator 2 Magnet 3 Rotor 6 Commutator 7 Brush holder 71 Terminal 72 Fixing groove 73 Lead wire 8A, 8B Brush 9A, 9B Compression spring

Claims (1)

[Scope of utility model registration request] 1. A plurality of brushes are connected to one terminal,
The plurality of brushes slid on the commutator surface D
In the C tacho generator, at least one
Make the material of the brush high wear resistance and
The material is a highly abrasive material and one or more of the
Push the thrust to the commutator with a spring with high spring pressure
First, the remaining brush is configured to be pressed against the commutator by a spring having a low spring pressure.
C tacho generator.