JP3354336B2 - Carbon brush for rotating equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a carbon brush used for rotating equipment such as a generator and an electric motor, and more particularly, to a carbon brush for rotating equipment having a small resistance loss and having excellent durability and life including commutation. It is about.

[0002]

2. Description of the Related Art In recent years, electric motors have tended to be smaller and have larger capacities, and the performance issues required for the carbon brushes used in the motors have also been reduced in size, reduced in resistance, reduced in wear and increased in temperature with the increase in capacity. The carbon brushes used for the brushes are required to have a small resistance loss and a small wear. Therefore,
Recently, in order to solve the above problems, except for the contact surface that contacts the rotating commutator, the peripheral surface of the carbon brush substrate, for example, gold, silver, by applying an electrically conductive metal coating such as copper, Even if the resistance of the carbon brush substrate is high, the apparent resistance is reduced by the effect of the metal coating provided on the peripheral surface of the carbon brush substrate, thereby reducing the overall electric resistance, and as a result,
It has become possible to suppress the rise in temperature of the carbon brush due to resistance heating.

FIG. 14 shows, for example, Japanese Patent Application Laid-Open No. 5-182733.
Perspective view showing a conventional carbon brush shown in
FIG. 15 is a top view showing a state where the carbon brush is pressed against the commutator, and FIG. 16 is a side view thereof. In the figure, 1
Is a carbon brush base material, 2 is a lead wire serving to guide an electric current to the carbon brush, 3 is a tip end surface of the carbon brush which is in sliding contact with a copper piece of the commutator 6, and 4 is a peripheral surface of the carbon brush base material 1. 5 is a coiled spring for the carbon brush to make good sliding contact with the commutator 6, 7 is a copper piece of the commutator, 8 is a rotating shaft of the commutator 6, and A is a commutator. It is an arrow showing the rotation direction of the child 6.

Next, the operation will be described. The carbon brush conducts current with the commutator 6 which is a rotating body. In a generator or a motor, when a current of a coil short-circuited by the carbon brush is electrically inverted by 180 ° C. during a contact period. To suppress the short-circuit current flowing through the

However, when a metal coating is applied to the entire surface of the carbon brush, rectification tends to be poor. This is because the load current is concentrated on the metal film with low resistance, and especially on the contact surface perpendicular to the rotation direction of the commutator, the delay in the change in magnetic flux due to the sudden concentration of short-circuit current is one of the factors that cause sparks. ing.

Normally, if the load current is appropriately dispersed between the carbon brush and the commutator, there is no chance of spark generation. However, as in the case of the contact state between the carbon brush and the commutator at the end of life, If the resistance of the carbon brush becomes extremely low (the resistance decreases as the length of the carbon brush decreases from the beginning to the end), the load current suddenly decreases due to the inductance of the armature coil. It is difficult to reduce, and the current density becomes extremely large. Then, the temperature of the carbon brush and commutator rises sharply,
Eventually, the commutator copper piece, which is the contact portion, reaches the melting point and begins to melt, and is pulled out of the contact portion to form a molten bridge. If this breakage of the molten bridge occurs continuously, its length will increase in the direction of rotation, and eventually it will not be able to support it and will evaporate, resulting in the end of contact with the carbon brush (Fig. Fifteen
(Around the arrow B shown in FIG. 5). This phenomenon is likely to occur when the difference between the resistance of the metal coating and the resistance of the carbon brush is 10,000Ω or more.

[0007]

Since the conventional carbon brush is configured as described above, stable commutation cannot be obtained due to generation of sparks, wear due to poor commutation, and the like.
There were problems such as a shortened life of the carbon brush.
The present invention has been made in order to solve the above-mentioned problems, and it is possible to take measures against high temperatures associated with a reduction in resistance and an increase in capacity of a carbon brush, and to reduce wear and wear associated with stable rectification.
The purpose is to obtain more accurate input stabilization.

[0008]

According to the present invention, there is provided a carbon brush, wherein a metal film having good electrical conductivity is formed on a peripheral surface of a carbon brush base material whose leading end surface is in contact with a rotating commutator, and the carbon brush is provided. The metal film formed on the surface of the substrate parallel to the rotation direction of the commutator is stripped from the front end surface to the rear end surface to expose the brush base.

In addition, a concave portion is formed on the surface of the carbon brush base material having the leading end surface in contact with the rotating commutator parallel to the rotational direction of the commutator, from the leading end side to the rear end side,
An electrically conductive metal is buried in the recess.

[0010]

The carbon brush according to the present invention is provided in parallel with the rotation direction of the commutator and removes the metal film formed on the surface thereof, thereby forming a low-resistance portion formed of a metal film having good electrical conductivity. And a high-resistance portion formed of a carbon base material to prevent the load current from being concentrated on the surface of the carbon brush.

In addition, a recess is formed on the surface parallel to the rotation direction of the commutator from the front end side to the rear end side, and a low-resistance portion and a high-resistance portion are formed by embedding an electrically conductive metal in the recess. In addition to preventing the load current from concentrating on the surface of the carbon brush, the resistance loss is small, the temperature rise is small, and the current density can be increased.

[0012]

【Example】

Embodiment 1 FIG. An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a perspective view of a carbon brush showing one embodiment of the present invention, FIG. 2 is a sectional view thereof, and FIG. 3 is a side sectional view showing a state in which the carbon brush is incorporated in, for example, an electric motor for a vacuum cleaner. FIG. 4 is a side view showing the configuration of the carbon brush holding portion, and FIG. 5 is a sectional view thereof. In the figure, 1 is a carbon brush base material, 2 is a lead wire for guiding a current to the carbon brush, 3 is a tip surface of the carbon brush which is in sliding contact with a commutator, 4 is a metal film having good electrical conductivity, and 9 is a commutator. An upper surface or a lower surface, which is provided in parallel with the rotation direction of the commutator 6 and is in contact with the plurality of metal pieces 7 of the commutator 6, is a side surface on the rotation direction side provided orthogonal to the rotation direction of the commutator 6. . Reference numeral 11 denotes grooves provided on the upper surface and the lower surface, respectively, which are provided in a band shape from the front end surface side to the rear end surface side. Reference numeral 12 denotes an armature which is a rotating body of the electric motor, and 13 denotes a carbon brush holder which pressurizes a carbon brush slidably in contact with the commutator 6 with a spring and transmits stable electric power between the stationary body and the rotating body. And is fixed to the frame of the electric motor by screws or the like. 14 is a convex portion provided at a connection portion of the carbon brush holder with the carbon brush, and is fitted with a carbon brush having a concave shape to prevent play and chattering of the carbon brush,
Further, a stable rectification environment can be secured.

Next, the operation will be described. The carbon brush conducts current between the commutator 6 of the armature, which is a rotating body, and in a generator or a motor, the current of the armature coil short-circuited by the carbon brush electrically changes during the contact period. The short-circuit current flowing when the take-out direction is reversed by 180 degrees is suppressed. This is because, for example, each coil of the armature is short-circuited twice with a carbon brush every one rotation, and each time the current in the coil changes from + I to -I
And then the direction is reversed from -I to + I. The time starts from the moment the armature coil is short-circuited by the carbon brush and ends when the short-circuit is released. It is.

In the carbon brush of this embodiment, the metal coating 4 applied to the upper and lower surfaces 9 of the carbon brush substrate 1 provided in parallel to the rotation direction of the commutator 6 is removed in a strip shape from the front end surface to the rear end surface. And the carbon brush base material is exposed. As a result, the upper and lower surfaces 9 are separated and stratified into a low-resistance portion and a high-resistance portion, to prevent a load current from concentrating in a rotational direction component, to reduce a short-circuit current, and not to delay a change in magnetic flux. And the rectifying action can be improved.

Further, the upper and lower surfaces are, for example, coated with a metal coating on the entire peripheral surface of the carbon brush, and then, in the next step, the coating is removed only on the tip end face by cutting or the like, and in the next step, the coating is made parallel to the rotation direction. There is a method in which the metal coating applied to the provided upper and lower surfaces is stripped from the front end surface to the end surface to form a strip, exposing the carbon brush base material. However, the present invention is not limited to this. By masking in advance the portion where the carbon brush base material is exposed and applying a metal coating,
The carbon brush substrate may be exposed. As for the deletion width, if the deletion is performed too much, the apparent resistance value of the metal film may be reduced and the motor efficiency may be reduced. For example, the deletion width may be set to １ ／ of the surface area of each of the upper and lower contact surfaces. The following is preferably verified experimentally from the graph of FIG. Further, the length of the metal coating to be removed does not have to be removed over the entire length from the front end to the rear end of the carbon brush, as long as the metal coating in the portion where the carbon brush is actually used is deleted.

Embodiment 2 FIG. FIG. 6 is a cross-sectional view showing the carbon brush of Example 2, FIG. 7 is a side view showing the configuration of the carbon brush holding section, and FIG. 8 is a cross-sectional view thereof. Reference numeral 15 denotes a cutout portion obtained by removing the metal coating applied to both ends of the upper and lower surfaces 9 of the carbon brush base material 1 from the front end surface toward the end surface. With this configuration, the same effect as that of the first embodiment can be obtained. Reference numeral 16 denotes a projection provided at a connection portion of the carbon brush holder 13 with the carbon brush 1, and
By fitting with the notch 15 of the upper and lower contact surfaces 9 of the upper and lower surfaces, play and chattering of the carbon brush 1 can be prevented, and a more stable rectifying environment can be secured. As in the first embodiment, it is desirable that the width of the cutout is approximately 略 or less of the entire upper and lower contact surfaces, including the cutouts at both ends.

Embodiment 3 FIG. FIG. 9 is a sectional view showing the carbon brush of the third embodiment. Reference numeral 17 denotes a cutout portion obtained by removing approximately 1/3 surface of the metal coating applied to the upper and lower contact surfaces 9 of the carbon brush base material 1 from the front end surface side to the rear end surface side, and has the same effect as the first and second embodiments. Obtainable. Further, regarding the shape of the carbon brush holder, the first and second embodiments are described.
Similarly, by providing a projection on the carbon brush retainer and fitting it into the notch 17 of the carbon brush, play and chattering of the carbon brush 1 can be prevented, and a more stable rectification environment can be secured. As in the first embodiment, it is desirable that the width of the cutout is approximately 略 or less of the entire upper and lower contact surfaces, including the cutouts at both ends.

Embodiment 4 FIG. FIG. 10 is a cross-sectional view illustrating the carbon brush of the fourth embodiment. FIG. 11 is a side view showing the structure of the carbon brush holder, and FIG. 12 is a sectional view thereof.
In the drawing, reference numeral 18 denotes a concave portion provided from the top end surface to the end surface side of the upper and lower surfaces of the carbon brush base material, and 19 denotes a metal having good electrical conductivity, and a metal 19 is buried in the concave portion 18 to form a carbon brush. I do. Thereby, the upper and lower surfaces are
By separating the low resistance part of the metal part and the high resistance part of the carbon brush base material, the rectifying action is improved, and further, the resistance loss is small, the temperature rise is small, and the carbon brush capable of increasing the current density is formed. be able to.

[0019]

As described above, according to the present invention, a metal film having good electrical conductivity is formed on the peripheral surface of a carbon brush base material whose tip surface is brought into contact with a rotating commutator, and the carbon brush base is formed. The metal film formed on the surface of the material parallel to the rotation direction of the commutator is stripped from the front end side to the rear end side in a band shape, and the brush base material is exposed, so that load current is prevented from being concentrated on the surface. Therefore, the rectifying action can be improved because the change in the magnetic flux can be prevented from being delayed. Therefore, there is an effect that the carbon brush is reduced in wear and durability is improved due to the stable rectification, and the input of the motor is more stabilized.

A concave portion is formed on the surface of the carbon brush base material having the leading end surface in contact with the rotating commutator parallel to the rotation direction of the commutator, from the leading end surface to the rear end surface. Since the electrically conductive metal is buried, the same effect as described above can be obtained, and a carbon brush that can reduce the resistance loss, reduce the temperature rise, and increase the current density can be formed.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a carbon brush according to Embodiment 1 of the present invention.

FIG. 2 is a sectional view showing a carbon brush according to Embodiment 1 of the present invention.

FIG. 3 is a side sectional view showing a state where the carbon brush according to the first embodiment of the present invention is incorporated.

FIG. 4 is a side view of the carbon brush holding portion according to the first embodiment of the present invention.

FIG. 5 is a sectional view of a carbon brush holding portion according to the first embodiment of the present invention.

FIG. 6 is a sectional view showing a carbon brush according to Embodiment 2 of the present invention.

FIG. 7 is a side view of a carbon brush holding unit according to Embodiment 2 of the present invention.

FIG. 8 is a sectional view of a carbon brush holding portion according to a second embodiment of the present invention.

FIG. 9 is a sectional view showing a carbon brush according to Embodiment 3 of the present invention.

FIG. 10 is a sectional view showing a carbon brush according to Embodiment 4 of the present invention.

FIG. 11 is a side view of a carbon brush holding unit according to Embodiment 4 of the present invention.

FIG. 12 is a sectional view of a carbon brush holding portion according to a fourth embodiment of the present invention.

FIG. 13 is a graph showing the efficiency of a carbon brush according to an embodiment of the present invention.

FIG. 14 is a perspective view of a carbon brush showing the prior art of the present invention.

FIG. 15 is a top view of a carbon brush and a commutator showing the prior art of the present invention.

FIG. 16 is a sectional view of a carbon brush and a commutator showing a conventional technique of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Carbon brush base material 2 Lead wire 3 Carbon brush tip surface 4 Metal coating 5 Spring 6 Commutator 7 Copper piece 8 Rotating shaft 9 Upper and lower surfaces 10 Side surface 11 Groove portion 12 Armature 13 Carbon brush retainer 14 Convex portion 15 Cut Notch 16 Protrusion 17 Notch 18 Recess 19 Metal

────────────────────────────────────────────────── (5) References JP-A-5-182733 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) H02K 13/00-13/14 H01R 39 / 00-39/64

Claims (2)

(57) [Claims] An electric conductive metal coating is formed on a peripheral surface of a carbon brush substrate having a tip end surface in contact with a rotating commutator, and the carbon brush substrate is parallel to a rotation direction of the commutator. A carbon brush for rotating equipment, wherein a metal film formed on a surface is removed in a band shape from a front end surface side to a rear end surface side to expose a brush base material. 2. A concave portion is formed on a surface of a carbon brush base material having a front end surface in contact with a rotating commutator parallel to a rotation direction of the commutator, from a front end surface side to a rear end surface side,
A carbon brush for rotating equipment, wherein an electric conductive metal is buried in the recess.