JPH09238450A - Brush of motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a brush from which a trouble caused by wear is eliminated by a method wherein the composition of cladding noble metal is changed in order to avoid the partial wear which is produced by the noble metal scattering caused by the spark of a brush which is rubbed against a commutator. SOLUTION: A noble metal material having a higher melting point than that of a noble metal material forming a cladding part 6 of a brush 20 on an electrically negative potential side is used as a cladding part 6 of a brush 19 on an electrically positive potential side is made. As a result, the wear of the noble metal part with the higher melting point is less than the wear of the noble metal part with the lower melting point. As a result, the wear of the positive potential side brush 19 and the wear of the negative potential side brush 20 are progressed with almost the same speed and, when both electrodes are worn out, both the noble metal claddings are consumed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a brush device for a DC motor having a commutator that is rotationally driven only in one direction, and more particularly to a structure of a noble metal of a clad material that constitutes the brush.

[0002]

2. Description of the Related Art FIG. 4 is a cross-sectional view showing an embodiment of a small direct current motor having a pair of brush devices made of a cladding material using a noble metal for a contact that makes sliding contact with a commutator. In the figure,
The electric motor 10 has an outer shell formed by a case 12 having a central portion closed by a bearing 11 and a body portion made of a cylindrical bowl-shaped container, and a side plate 14 that supports the bearing 13 at the central portion. A rotor main part is formed in a space constituted by an outer shell by a core 16 fixed to a rotating shaft 15 supported by bearings 11 and 13 and a coil 17 wound around the core. The outer peripheral surface is arranged to face the magnet 18 fixed to the inner surface of the case 12.

A commutator unit is provided coaxially with the rotor main portion to form a rotor. The commutator unit has a rotating shaft 1 in the center hole of a cylindrical holder 21 made of a resin material.
5, the commutator 22 is formed so as to surround the outer peripheral surface of the holder 21. The commutator 22 is configured as a commutator piece that is equally divided according to the number of poles of the electric motor, and a riser 23 is arranged on each commutator piece.

An electric current is passed between two brushes 19 and 20 arranged in the vertical direction of the rotary shaft 15 extending from the brush support 24 so as to make sliding contact with the outer periphery of the commutator 22, and the commutator 2
The coil 17 is energized from the two pieces via the riser 23, and a magnetic action is applied between the salient pole and the magnet 18 to rotate the electric motor. In the above figure, two brushes 1
Although 9 and 20 project toward the commutator from the core inner surface direction facing each other around the rotation axis, they may project from the same direction of the core inner surface part substantially parallel to the commutator. Therefore, in the following drawings, it is assumed that the protruding direction of the brush is irrelevant.

FIG. 5 is a view of a conventional example showing a state change of the clad in a sliding contact state between the commutator and the brush when the commutator in the above figure rotates clockwise, and FIG. 5 (a) shows an initial state. It is a figure which shows, and is a figure which shows the state after continuous use of FIG.5 (b). Further, in the figure, it is assumed that the brush 19 is applied with a positive potential and the brush 20 is applied with a negative potential.

In FIG. 5A, the brushes 19 and 20 are
For example, for base elastic materials such as nickel silver and phosphor bronze,
In the vicinity of sliding the noble metal 3 such as Ag-Pd, Ag-Pd-Cu, Pd-Ru, etc. with the commutator 22, the noble metal 3 is evenly distributed from the contact point 9 to both sides in the commutator direction with predetermined widths w and w. The materials of the clad are the same in composition, and the brush t to which a positive potential is applied and the thickness t of a clad to which a negative potential is applied are both substantially uniform in thickness.

The wear of the brush that is in sliding contact with the commutator is classified into wear due to sliding with the commutator and wear due to sparks generated when the potential changes with the rotation of the commutator. The wear due to sparks is more severe on the brush side to which a positive potential is applied than on the brush side to which a negative potential is applied, and the thickness balance is lost over time. Moreover, in FIG. 5B, when the commutator rotates in the direction of the arrow, the commutator violently occurs at the position α on the rotation advancing direction side.

As a result, when it is continuously used, abrasion progresses, and as shown in FIG. 5 (b), the position α on the rotation advancing direction side is scooped out, the vibration of the electric motor increases, and the brush breaks. This causes inconvenience such as the motor stopping. As a result, the reliability of the electric motor is significantly impaired. In addition, since the part that wears out is the α part, the β part, the γ part, or the δ part is hardly worn, and the electric motor itself must be discarded regardless of the presence of the noble metal in this state. The presence of precious metals in the parts that have not yet been worn was wasted, and the economy was low.

[0009]

SUMMARY OF THE INVENTION Therefore, the present invention is directed to deterioration of a brush slidingly in contact with a commutator due to aging, in particular, heat dissipation of a conductive elastic material or metal due to sparks, and the resulting conductive elastic material or metal portion. In order to prevent electrical wear, by changing the combination of conductive elastic materials and the composition of the noble metal of the clad that make up the brush device of the DC motor, the obstacles caused by the wear of the conductive elastic material and noble metal during long-term rotation are eliminated. It is an attempt to provide a brush device having high property.

[0010]

SUMMARY OF THE INVENTION Therefore, claim 1 of the present invention is provided.
In the brush device for an electric motor, which includes a commutator and a pair of brushes that are in sliding contact with the commutator, the commutator rotates in only one direction. The brush on the potential side has a higher melting point than the brush on the negative potential side.

According to a second aspect of the present invention, there is provided a brush device for an electric motor, which comprises a commutator and a pair of brushes made of a cladding material using a noble metal for a contact which is in sliding contact with the commutator. In a brush device of an electric motor that is driven to rotate only in, the noble metal in the clad portion of the brush on the positive potential side of the pair of brushes has a higher melting point than the precious metal in the clad portion of the brush on the negative potential side. To do.

A brush device for an electric motor according to claim 3 of the present invention is characterized in that the brush on the positive potential side is made of a noble metal and the brush on the negative potential side is made of a conductive elastic material having a melting point lower than that of the noble metal. .

In the brush device for an electric motor according to claim 4 of the present invention, the noble metal of the clad portion of the brush on the positive potential side is thicker than the noble metal of the clad portion of the brush on the negative potential side. .

In the brush device for an electric motor according to claim 5 of the present invention, the noble metal in the clad portion of the brush on the positive potential side has a longer dimension in the longitudinal direction than the noble metal in the clad portion of the brush on the negative potential side. And

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION In the present invention, a brush on the positive potential side of a pair of brushes on the positive potential side and the negative potential side is basically composed of a member having a higher melting point than the brush on the negative potential side. As a result, even if the brush on the positive potential side is severely worn due to heat scattering, the wear on the brush on the positive potential side and the wear on the brush on the negative potential side are almost in equilibrium until they are worn out. It is designed to improve the economical efficiency of the brush.

In addition to the above-described present invention, according to the present invention, the composition of the noble metal of the cladding material forming the brush on the positive potential side and the negative potential side is formed of materials having different melting points so that even if spark occurs, It is also possible to prevent heat dissipation and extend the life of the brush.

FIG. 1 is a view showing a processing method when a noble metal is clad on a base such as nickel silver in relation to the present invention described above.

In FIG. 1, the base nickel silver (Cu-
Ni-Zn), phosphor bronze (Cu-Sn-P), beryllium bronze (Cu-Be), etc. After the groove 2 is cut at a predetermined position of the long hoop material 1, the groove cross section and its cross section are the same. Insert the precious metal material 3 of the size. After that, the base and the noble metal are joined at the same time by rolling to a predetermined thickness using a rolling device such as rolls 4 and 4. The joined clad member is cut into a predetermined length in the vertical direction of the hoop material to form a brush 5 having a predetermined size. At this time, two types of brushes 5 are manufactured in which the melting point of the noble metal forming the clad portion of the brush which is electrically positive potential side and the melting point of the noble metal forming negative potential side are changed.

In addition to pressing the base and the noble metal, it is also possible to perform diffusion bonding by interposing a brazing material containing an active metal in a bonded body made of different materials. After cutting the groove 2 at a predetermined position of a long hoop material 1 such as base silver, after placing the brazing material along the groove portion, a noble metal having the same cross section as the groove cross section is inserted. . Then, the noble metal is joined by interposing a brazing material by using a heating means such as a high frequency induction heating method. As the heating means, various known means other than the above high frequency induction heating method can be adopted.

In the structure shown in FIG. 1, the noble metal having a melting point higher than that of the noble metal forming the clad of the brush on the negative potential side is made of the noble metal forming the clad portion of the brush on the electrically positive side. To use.

For example, as a combination of materials, a noble metal forming a positive potential brush, a noble metal forming a negative potential brush Ag-Pd ⁵⁰ (1290 ° C.) Ag-Pd-Cu (1150 ° C.) Ag-Pd ⁶⁰ (1320 ° C.) Ag -Pd ³⁰ (1225 ° C) Pd-Ru (1580 ° C) Ag-Pd ⁵⁰ (1290 ° C) can be set freely.

As a result, the wear of the noble metal part due to the spark is consumed less in the noble metal part having the higher melting point than in the noble metal part having the lower melting point, so that the brush side on which the positive potential is applied has a higher melting point. By making the lower side the brush side to which the negative potential is applied, the abrasion speed on the brush side to which the positive potential is applied and the brush side to which the negative potential is applied progresses at approximately the same speed, and when both electrodes are worn, whichever Since no precious metal exists, the precious metal can be used without waste. This means that the same amount of noble metal can be used to make long lasting brushes. On the contrary, if the lifespan is the same, the amount of precious metal can be reduced, which is highly economical.

In the present invention, of the pair of brushes on the positive potential side and the negative potential side, the brush on the positive potential side has a member clad with a noble metal having a high melting point, and the brush on the negative potential side is the above-mentioned nickel silver ( Cu-Ni-Zn), phosphor bronze (Cu-Sn)
-P), beryllium bronze (Cu-Be) or the like may be used to form the elastic body. Even in this case, even if a member clad with a noble metal having a high melting point is subjected to severe heat dissipation, it will be exhausted in an almost equilibrium state with the wear of the brush on the negative potential side, thus improving the economical efficiency of the pair of brushes. be able to.

FIG. 2 is a diagram showing a sliding contact state between the brush and the brush when the brush shown in FIG. 1 is applied to an electric motor capable of rotating in one direction and the commutator rotates clockwise. This is in contrast to the conventional example shown in FIG. The same members are designated by the same reference numerals, and the description overlapping with the above description will be omitted.

The noble metal 7 of the cladding material 6 of the brush 19 to which a positive potential that is easily worn by the spark is applied is thicker than the noble metal 8 of the cladding material 6 of the brush 20 to which a negative potential is applied.
By the _1> t _2, is obtained by the withstand long-term use.

In the above description, since the brush on the electrically positive potential side and the brush on the negative potential side, which are made of a clad material using a noble metal having a different melting point, are similar in appearance, they are misidentified during assembly. There is fear. In order to prevent this misidentification, the width of the noble metal of the brush 19 on the positive potential side is set to the brush 2 on the negative potential side.
It can also be wider than the width of a noble metal of zero. FIG. 3 is a diagram in the case of forming such a shape, in which the width m of the noble metal 7-1 of the brush 19 on the positive potential side is larger than the width n of the noble metal 8-1 of the brush 20 on the negative potential side. Is also wide.

As a result, the appearance of the brush on the positive potential side using the noble metal having a high melting point and the brush on the negative potential side using the noble metal having a relatively low melting point can be easily identified by the width of the precious metal. There is no risk of confusion.

[0028]

As described above, in the brush device for the DC motor of the present invention, the melting point of the clad portion of the brush, which is electrically positive potential side, is set higher than the melting point of the brush on the negative potential side. The wear of the brush on the positive potential side due to sparks during rectification and the wear of the brush on the negative potential side are kept in balance, and even if sparks occur, the wear of both brushes will progress at the same speed, and the service life will be relatively long. It is possible to make it longer than before. Therefore, vibration due to wear due to use over time,
Alternatively, it is possible to provide a reliable and inexpensive brush device for an electric motor that can reduce breakage.

[Brief description of drawings]

FIG. 1 is a view showing a processing method when a noble metal is clad on a base such as nickel silver in relation to the present invention.

FIG. 2 shows the sliding contact state of the commutator and the brush when the brush shown in FIG. 1 according to the present invention is applied to an electric motor capable of rotating in one direction and the commutator rotates clockwise. This is an example.

FIG. 3 shows a sliding contact state between the brush and the brush when the brush shown in FIG. 1 according to the present invention is applied to an electric motor capable of rotating in one direction and the commutator rotates clockwise. It is another embodiment.

FIG. 4 is a cross-sectional view showing an aspect of a small DC motor having a pair of brush devices, which is made of a cladding material using a noble metal for a contact that is in sliding contact with a commutator.

FIG. 5 is a diagram showing a state change of the clad in a sliding contact state between the commutator unit and the brush when the conventional commutator rotates clockwise.

[Explanation of symbols]

 6 Clad material 7 Noble metal 8 Noble metal 9 Contact point 19 Positive potential side brush 20 Negative potential side brush

Claims (5)

[Claims] 1. A brush device for an electric motor comprising a commutator and a pair of brushes in sliding contact with the commutator, wherein the commutator is rotationally driven in only one direction. A brush device for an electric motor, characterized in that the brush has a higher melting point than the brush on the negative potential side. 2. A commutator, and a pair of brushes made of a cladding material using a noble metal for a contact slidingly contacting the commutator,
In a brush device for an electric motor in which the commutator is driven to rotate only in one direction, in the pair of brushes, the noble metal in the clad portion of the brush on the positive potential side has a higher melting point than the noble metal in the clad portion of the brush on the negative potential side. Brush device for electric motors, which is characterized by high cost. 3. The brush device for an electric motor according to claim 1, wherein the brush on the positive potential side is made of a noble metal, and the brush on the negative potential side is made of a conductive elastic material having a melting point lower than that of the noble metal. 4. The brush device for an electric motor according to claim 2, wherein the noble metal in the clad portion of the brush on the positive potential side is thicker than the noble metal in the clad portion of the brush on the negative potential side. 5. The brush device for an electric motor according to claim 2, wherein the noble metal in the clad portion of the brush on the positive potential side has a longitudinal dimension longer than that of the noble metal in the clad portion of the brush on the negative potential side.