US1188635A - Carbon-brush connection. - Google Patents

Description

' H. B. EYNON.

CARBON BRUSH CONNECTION.

APPLICATION FILED MAY I, I9I4.-

1,188,635. Patented Jun@ 27,1916.

www @was cih/wanton l. 5)/1/0/1/ @gw futon/Ie A UNITED STATES PATENT OFFICE.

HOWARD B. EYNON, 0F EAST ST. LOUIS, ILLINOIS, ASSIGNOR TO AMERICAN CARBON & BATTERY CO., OF EAST ST. LOUIS, ILLINOIS, A CORPORATION OF ILLINOIS.

CARBON-BRUSH CONNECTION.

Specification of Letters Patent.

Patented J une 27, 1916.

To all whom it may concern Be it known that I, HOWARD B. EYNoN, a citizen of the United States, residing at East St. Louis, county of St.. Clair, State of Illinois, have invented certain new and useful Improvements in Carbon-Brush Connections; and I do hereby declare the following to be a full, clear, and exact description of the invention, Such as will enable others skilled in the art to which it appertains to make and use the same.

It is the object of the present invention to provide an improved connection between a flexible conductor, such as a stranded pigtail, and a carbon block, suitable for use as a brush in motors, dynamos and dynamo electric machines. To edect a connection between the stranded conductor and the carbon block, which shall have good electrical conductivity, satisfactory mechanical strength, cheapness, permanence and other desirable characteristics both electrical and mechanical, I make use of anv amalgam, such as a copper amalgam, by filling a cavity in the carbon brush with the amalgam and suitably attaching the stranded conductor to the cari bon by means of this amalgam filling.

One embodiment of the present invention is disclosed in the accompanying drawings, wherein- Figure l is a sectional elevation through the brush showing the amalgam lling in the cavity; Fig. 2 is a sectional plan on the line 2--2 of Fig. l; and Fig. 3 illustrates a modification in which the upper portion of the cavity is filled in with a carbonaceous material.

In the embodiment illustrated, the flexible conductor l is of ordinary construction, as of stranded copper wire, and the carbon block 2 may be of a usual composition of carbon held with a binder and admixing with graphite or other suitable materials in accordance with standard practice.

To effect the connection, a straight, cy-

lindrical hole is drilled through the top of the brush, preferably of a size to just receive the stranded conductor and of a depth depending on the size of the brush, as, for instance, one and one-half inch for motor brushes of the more usual sizes. In addition to this drilled hole or cavity a second smaller drilled hole where it lies along one,l

side directly in contact with the copper plating. A soft and plastic amalgam is then tamped in to fill the cavity and form a plug 3 holding the stranded conductor tightly against the copper plating and lilling up. all interstices with metal of good conductivity.

Various amalgams can be used but a copper amalgam or copper bronze amalgam has proved satisfactory. The preferred method of production consists in taking 100 parts by weight of copper bronze powder and wetting with water to a-paste and then adding 25 parts of mercury and rubbing thev material thoroughly. Some diluted sulfuric acid is then added and the mixture rubbed again until complete amalgamation results, after which the material is washed free of acid. The amalgam is then' in a quite porous or puffy condition and when tamped into the cavity felts together well and is in the right condition for establishing a connection of high electrical conductivity between the stranded conductor and the carbon. There is enough mercury present to insure superficial amalgamation with the copper lining and with the copper wires of the stranded conductor, so that goodadhesion is effected; but there is vnot enough free mercury resent to materially weaken the strands o the conductor by union therewith. After the amalgam has been tamped in, it is allowed to harden or set, and during this hardening operation it expands slightly, though not enough to crack or endanger the carbon block. This expansion tightens up the illing in the cavity.

The adhesion of the amalgam in the cavity and its intimate blending with the stranded conductor, into the irregularities of which it percolates, insures a strong mechanical connection of good electrical conductivity and well adapted to changes in temperature and to the other trying conditions to which motor brushes are in practice subjected.

In the modified form illustrated in Fig. 3, the amalgam plug 3 does not fill the entire cavity, but the upper portion of the cavity is filled with a mixture 4 of carbon dust and sodium silicate, which on hardening tightly grips the stranded conductor and assists in mechanically holding it in the carbon block. The carbon dust is made up into a thick paste with 280Baum sodium silicate. The amount of sodium silicate used depends upon the fineness of the carbon dust.,

With the constructions above described, the carbon block can wear away when in use without weakening the connection, and even though worn away until the amalgam touches the commutator, no harm will be done, for the amalgam is softer than the commutator bars and will not scratch. Other amalgams can be used but the composition above disclosed has many advantages, particularly when prepared as above set forth. If too little mercury is used the material is too dry, and will not pack or felt together well, and if too much mercury is used, there is danger of impairing the strength of the stranded conductor through amalgamation of the copper wires, while b keeping the proportions in about the relation ctl00 parts copper, or copper bronze powder, to 25 parts mercury, these disadvantages are obviated and the connection is mechanically satisfactory; also copper amalgam has relatively-.good electrical conductivity.

Various changes in mechanical detail and in arrangement of the parts may be made without departing from the spirit of my invention as defined by the appended claims.

I claim:

1. The combination with a carbon brush having a cavity therein, of an amalgam plug in said cavity and a conductor secured i in good electrical connection with said carbon brush by said amalgam plug.

2. The combination of a carbon brush having a cavity therein, .an amalgam plug in said cavity and a conductor permanently embedded in the'amalgam to establish electrical connection with the carbon of said brush.

3. The combination of a carbon brush having a cavity therein, an electro-plated lining for said cavity, a conductor projecting into said cavity and an amalgam filling establishing good mechanical and electrical connection between said conductor and the carbon.

4. The combination of a carbon brush drilled at the top to form a cavity, a lining of electro-plated copper for said cavity, a conductor projecting into said cavity and copper amalgam holding said conductor in good mechanical and electrical connection with the carbon of said brush.

5. The combination with a carbon brush having a cavity therein, of a flexible conductor contacting with one side of said cavity and an amalgam filling about said conductor holding it in place, said filling comprising copper and mercury in about the proportion by weight of 100 to 25.

6. The combination of a carbon brush having a cylindrical hole therein, a flexible stranded conductor fitting snugly in said hole, said carbon brush having a cylindrical cav-ity into which said hole merges along one side and an amalgam filling in said cavity holding said conductor in place.

7. The combination of a carbon brush having a straight cylindrical'hole therein, a. layer of electro-plated copper lining said hole, a flexible stranded conductor fitting snugly in said hole and against said electroplating, said carbon'brush having a cylindrical cavity into which said hole merges along one side and an amalgam filling in said cavity holding said conductor in place.

8. The combination of a carbon brush having a straight cylindrical hole therein, a layer of electro-plated copper lining said hole, a flexible stranded conductor fitting snugly in said hole and against said electroplating, said carbon brush having a cylindrical cavity into which said hole merges along one side and an amalgam filling in said cavity holding said conductor'in place, said amalgam comprising copper and mercury in about the proportions by Weight of 10() copper to 25 mercury.

9. The combination of a carbon brush having a hole therein, a layer of electro-plated copper lining said hole, a flexible stranded conductor fitting snugly in said hole and against said electro-plating, said carbon vbrush having 'a cylindrical cavity into which said hole merges along one side, an amalgam filling in said cavity holding said conductor in place, said amalgam comprising copper and mercury in about the roportions by weight of -100 to 25 and a solidilied paste covering said amalgam at the top of said, cavity.

10. The method of establishing a good electrical connection between a flexible stranded conductor and a carbon brush having a cavity,- which consists in lining the cavity with electro-plated copper, inserting a flexible stranded conductor therein, tamping an amalgam about the conductor and allowing the amalgam to harden and superficially amalgamate with said copper lining and thereby secure the stranded conductor to the brush.

11. The method of connecting a stranded conductor to a carbon brush having a cavity therein, which consists in electro-plating the 13 wall of the cavity with copper, inserting the end of the flexible conductor into the cavity in contact with one side thereof, tamping a copper amalgam about the flexible conductor and allowing said amalgam to harden and superficially amalgamate with said copper lining, and thereby establish good electrical and mechanical connection between the conductor and the carbon of the brush.

12. The method of attaching a flexible conductor to a carbon brush having a cavity in the top thereof, which consists in inserting a flexible conductor therein, tamping a copper amalgam about said conductor and allowing said amalgam to harden and expand and thereby establish a tight connection between the conductor and the brush.

13. The method of connecting a flexible stranded conductor to a carbon brush having a drilled hole in the top thereof, which consists in electro-plating the cavity with copper, inserting the flexible conductor into the cav-ity in contact with its electro-plated 1ining, tamping a per cent. copper amalgam about the stranded conductor and allowing said amalgam to harden Superficially and amalgamate with said lining and thereby establish good electrical connection between the stranded conductor and the carbon of the brush.

ll. The method of connecting a stranded flexible conductor to a carbon brush having in the top thereof two drilled holes offset with respect to one another and merging into one another, which consists in electroplating the cavity thus formed with a lining of copper, inserting a flexible conductor in one of the drilled holes and positioning it against the electro-plated lining, tamping a Q5 per cent. copper amalgam into the cavity and allowing said amalgam to harden and amalgamate with the copper lining to establish a permanentconnection of good conductivity between the stranded conductor and the carbon of the brush.

In testimony whereof I alix my signature, in presence of two witnesses.

HOWARD B. EYNON.

Witnesses CARL HAMBnUoI-rnn, OTTO NOLL.

Copies kof this patent may be obtained for tive cents each, by addressing` the Commissioner of Patents,

Washington, D. c.

Images