JPS5924515B2 - small magnet motor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a compact magnet motor, in particular, which has a sufficiently small resistance for the supply of armature current, while at the same time resisting the spark-generating current generated between the commutator pieces via the brushes. In order to have a sufficiently large resistance, at least the sliding part of the brush has a multilayer structure with different conductivities, and the brush is used in contact with the motor commutator with a sufficiently small pressing force. This invention relates to a small magnet motor.

In general, the brushes of small magnet motors have elasticity of the brush itself or other external elastic body to prevent the brush sliding part from swinging undesirably at the point of contact with the motor commutator. The moving part is designed to apply a relatively large pressing force to the motor commutator.

However, as mentioned above, when the pressing force of the brush sliding part is increased, undesirable friction loss occurs on the motor commutator, and wear on the brush itself increases, and sparks are generated in this state. If this occurs, the above-mentioned wear will be further accelerated. Conventionally, it has been considered that it is an essential requirement to suppress undesired swinging of the brush, and the above-mentioned friction loss is considered to be unavoidable. It was considered that this would occur. For example, in the case of a motor with a large armature current, so-called carbon brushes are used to reduce the frictional resistance between the commutator and the commutator as much as possible, and to suppress the spark current due to the electrical resistance of the carbon brushes against spark generation. I try to do that. Also, depending on the specifications for small magnet motors,
As shown in Fig. 4, the claws 16-1, 1 are attached to the sliding part of the brush body.
6-2 and attaching the carbon piece IT, or as shown in FIG. 5, a mixture 18 of, for example, carbon powder hardened with an adhesive is applied to the sliding portion of the brush body. Needless to say, the configurations shown in FIGS. 4 and 5 can be considered as an extension of the conventional concept of reducing the frictional resistance with the commutator and suppressing the spark current. In the case of this type of small magnet motor, the concept of replacing the brush when it wears out is abandoned, and the wear of the brush is considered to be the end of the life of the motor. In this case, it means that the life of the brush itself is increased, thereby increasing the life of the motor. However, when trying to obtain a relatively high output with a small magnet, the armature current is suppressed due to the electrical resistance of the carbon pieces 17 and the mixture 18 in the configuration shown in FIGS. 4 and 5 above. This includes the problem of

From the above, ideally, the conventional idea of expecting wear on the brush side should be abandoned, considering that the wear of one brush immediately corresponds to the life of the motor.

That is, wear of the brushes and wear of the commutator are made as equal as possible. 2. For this purpose, the pressing force of the brush is made as small as possible to prevent frictional resistance from becoming undesirably large.

3. Also suppresses spark generation.

4 However, it is necessary to prevent the armature current from becoming undesirably small due to the resistance of the sliding parts.

It is hoped that The purpose of the present invention is to provide a motor that simultaneously solves the problems 1, 2, 3, and 4 mentioned above, which are mutually flexible. The above problem 3 is solved by adopting a multi-layered structure and providing a resistance layer on the brush sliding part, and the resistance layer has a thickness of several tens of micrometers or less, preferably 10 μm or less.
Problem 4 in -F is solved by setting the resistance to about several microns, and the above resistance is suppressed while keeping the resistance of the entire brush small and suppressing swinging such as undesired bounce of the brush even under a small pressing force. The above problem 2 is caused by the effect of suppressing spark generation due to the layer.
The purpose of this invention is to solve the following problems and thereby achieve the above-mentioned problem 1.

This will be explained below with reference to the drawings. 1A and 1B show an embodiment of the brush of a small magnet motor according to the present invention; FIG. 2 is an explanatory diagram for explaining the relationship between the brush shown in FIGS. 1A and 1B and the motor commutator; FIG. 3 shows an embodiment in which the brushes shown in FIGS. 1A and 1B have a so-called multi-brush structure.

FIG. 1A is a plan view of an embodiment of the brush according to the present invention;
FIG. B shows a cross-sectional view taken along the line XX shown in FIG. 1A.

In FIGS. 1A and B, 1 is a brush, 2 is a brush main body, which is made of a conductive material, such as a material mainly made of copper, and has a terminal portion 3 and a sliding portion 4; Reference numeral denotes a terminal portion to which a lead wire (not shown) is connected and is electrically connected to a battery terminal, 4 a sliding portion, 5 a resistance layer, and 6 a bent portion.

The brush body 2 has a thickness of, for example, about 0.1 mm. Further, the resistance layer 5 is baked onto the surface of the sliding portion 4 to a thickness of, for example, several tens of microns or less, preferably about 10-odd microns. In this case, the resistance layer 5 is made of any one of a fine powder of a conductive material, a fine powder of an oxide of a conductive material, a fine powder of a semiconductive material, a fine powder of a resistive material such as carbon, or a mixture thereof. It is suspended in a liquid adhesive and baked onto the surface of at least the portion of the brush body 2 that will become the sliding portion 4 to coat it with a desired resistance value. It goes without saying that the resistance layer 5 preferably has a coefficient of friction as small as possible with respect to the commutator pieces. What? The resistance layer 5 configured in this manner generally has a non-linear resistance characteristic, as seen in similar sintered bodies such as varistors, and has a small resistance value for relatively large currents such as armature currents. It has a large resistance value for a relatively small current such as a spark current. FIG. 2 is a perspective view for explaining the relationship between the brushes shown in FIGS. 1A and 1B and the commutator of the small magnet motor.

In the figure, 1 to 6 correspond to the numbers A and B in Figure 1, respectively, 7 is the rotor of a small magnet motor, 8 is a commutator (or commutator piece), 9 is an armature core, and 10 is a rotor of a small magnet motor. Coil connection terminals electrically connect each commutator piece 8 to an armature coil (not shown), and 11 represents a motor shaft. As shown in FIG.
is used after being bent at the bending portion 6, for example.

In this case, the terminal portion 3 is passed through, for example, a motor case (not shown) and taken out from the case. Further, as mentioned above, the brush 1 has a thickness of about 0.1 mm, has a weak elasticity, and is held fixedly to the motor case so that it is in contact with the commutator 8 with a relatively small pressing force. Although not shown, a separate brush 1 is provided at a commutator position shifted by 18 electrical degrees from the contact point between the brush 1 and the commutator 8 so as to obtain a similar contact state. The small magnet motor thus constructed is operated as follows during operation. (1) Armature current supplied to an unillustrated armature coil wound around the armature core 9 flows through the contact point between the brush 1 and the commutator 8.

In this case, the voltage drop with respect to the armature current near the contact point is considered to be approximately equal to the voltage drop due to the resistance layer 5, and the voltage drop due to the resistance layer 5 is equal to the voltage drop due to the resistance layer 5 in the normal direction as seen from the commutator 8. It is considered that it is proportional to the length, that is, the thickness of the resistance layer 5. In the case of the brush device according to this embodiment, as described above, the thickness of the resistance layer 5 is extremely thin, for example, several tens of microns or less, preferably about 10-odd microns. Therefore, the resistance of the entire brush 1 to the armature current is extremely small, and the armature current is not suppressed by the resistance, and a sufficiently large armature current can be supplied. (2) As described above, in the case of the brush 1 according to this embodiment, the thickness of the brush body 2 is, for example, about 0.1 mm, and the thickness of the resistance layer 5 is, for example, several tens of microns or less.

The capacity of the brush 1 is therefore sufficiently small to prevent the brush 1 from bouncing and undesirably swinging away from the commutator 8. (3) Furthermore, the spark-generating current generated between the commutator pieces 8 via the brush 1 is a pulsed current, and the skin effect is also used, so that the current mainly flows through the resistance layer 5.
It flows through the resistance layer 5 and is suppressed by the resistance of the resistance layer 5 in the tangential direction as viewed from the commutator 8, so that the resistance becomes relatively small.

Further, the current for spark generation is generally smaller than the armature current and can be suppressed to a small level even by the non-DC resistance provided by the resistance layer 5. In other words, the resistance of the entire brush 1 to the current that generates sparks is sufficiently large, and the generation of sparks can be sufficiently suppressed. (4) As described above, the brush 1 according to this embodiment is brought into contact with the commutator 8 with a small pressing force.

Furthermore, the resistance layer 5 that slides on the commutator 8 has a relatively small coefficient of friction. Therefore, friction loss at the sliding portion can be reduced, and wear can be reduced in combination with the above-mentioned effect of suppressing spark generation. The brush of the present invention is constructed as described above, and by adopting the multilayer structure of the conductor of the brush body 2 and the resistance layer 5, it is possible to prevent the armature current from being suppressed while preventing the generation of sparks. However, as mentioned above, since the pressing force on the brush sliding part 4 is kept as small as possible, for example, slight eccentricity of the motor rotor or a step difference between the commutator pieces may cause damage between the brush and the commutator. Small discontinuities are more likely to occur. For this reason, the brush itself has a so-called multi-brush structure, so that even if one brush becomes disconnected at a certain timing, it can be maintained in a connected state by other brushes, thereby preventing the brush from becoming disconnected as a whole. It is preferable to do so. Of course, at this time, 1
This does not preclude the possibility of preventing undesired breakage by dividing the sliding portion of each brush into so-called fork shapes, as is known in the art. Figure 3 is similar to Figure 1 A and B.
A diagram schematically showing a case where the illustrated brush 1 has a multi-brush structure.

In the figure, 1-1, 1-2, 1-3, and 1-4 are the brushes shown in FIG. 1, 8 is a motor commutator (or commutator piece), and 12
13 represents a battery, 13 and 13 represent lead wires, and 14 represents a motor case. In FIG. 3, brushes 1-1 and 1-2 are fixedly held in motor case 14 so as to be slightly shifted in electrical angle from commutator 8.

Further, the brush 1-3 and the brush 1-4 are similarly arranged with a slight electrical angle offset from the commutator 8, and the brush 1-3
18 in electrical angle for the contact point between 1, 1-2 and commutator 8
It is fixedly held on the motor case 14 so that it is arranged with a 02 offset. The terminal portion 3-1 of the brush 1-1 and the terminal portion 3-2 of the brush 1-2 are electrically connected to each other, and the terminal portion 3-3 of the brush 1-3 and the terminal portion 3-2 of the brush 1-2 are electrically connected to each other.
-4 and the terminal portion 3-4 are electrically connected to each other. If brush 1 has a multi-brush structure as described above, if brush 1-1 is
Even if the brushes 1-2 are disconnected, ie, undesirably separated from the commutator 8, armature current is supplied if the brushes 1-2 remain connected, ie, in contact with the commutator 8.

This eliminates one of the causes of spark generation and allows the motor to operate more favorably than the embodiment of FIG. As explained above, according to the present invention, the brush can be used under conditions where only the smallest possible pressing force is applied to the motor commutator, thereby reducing friction loss ε and wear at the contact point with the commutator. It can be fully prevented.

Further, even when used in this manner, spark generation can be sufficiently suppressed and a sufficiently large armature current can be caused to flow.

[Brief explanation of drawings]

FIGS. 1A and 1B show an embodiment of the brush of a small magnet motor according to the present invention, FIG. 2 is an explanatory diagram showing the relationship between the brush shown in FIGS. 1A and B and the motor commutator, and FIG. 1st
Use the brushes shown in Figures A and B! One embodiment of the multi-brush structure shown in FIGS. 4, 3 and 5 shows the main parts of the conventional brush, respectively. In the figure, 1 is a brush, 3 is a terminal part, 4 is a sliding part, and 5
8 represents a resistive layer, and 8 represents a motor commutator.

Claims (1)

[Scope of Claims] 1. A small magnet motor that is provided with a brush that is made of a conductive metal member and has a terminal portion and a sliding portion that contacts a motor commutator, and that is energized through the brush. A resistive layer, which is a non-metallic layer and has a higher resistance than the conductive metal member, is baked onto the surface of the sliding part of the brush to a thickness of several tens of microns or less, and the sliding part is combined with the conductive part and the resistive layer. A small magnet motor characterized by having a multi-layer structure. 2. The small magnet according to claim 1, wherein the brush has a multi-brush structure in which a plurality of sliding parts are arranged slightly shifted from each other in electrical angles. motor.