Method and Means for Increasing the Conductivity of Carbon to be Used in Electric Cells and Dynamo Electric" Generators, and Motors.
Year: 1899

page_text: Date of Application, 19th June, 1899
Complete Specification Lert, 16th Mar., 1900-Accepted, 5th May; 1900 ·
11 J
PROVISIONAL SPECIFICATION.
1.1
Method and Means for Increasing the Conductivity of Carbon to be
Used in Electric Cells and Dynamo Electric" Generators, and
Motors.
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ד'
1,. CARL. WILHELM HERTEL, of No. 27, Neue Grün, Strasse, Berlin, Germany,
Manufacturer, do hereby declare the nature of this invention to be as follows:-
Carbon is a substance which in its different forms is employed in electro-tech-
nology for many purposes.
This otherwise particularly suitable 'substance however suffers under the dis-
advantage that its conducting resistance is comparatively high."
It has been sought to obviate this drawback in various ways but hitherto with
little result.
The present invention obviates this drawback by providing the carbon to be
used with one or more insertions of metal. The form of the carbon and also that
of the insertions may be fixed according to the purpose for which they are
intended. By this process the resistance of the carbon is considerably reduced
so that it can be employed for the most various purposes.
For making. battery cells especially powerful and of great conducting power
the carbon is composed in the following manner :-
The electrode is made of zinc, carbon and copper preferably in a flat shape,
though it may take any other suitable form. In small cells the employment of a
cylindrical electrode is recommended, the hollow space having a copper lining.
The junction of the conductor takes place here in the centre of the electrode and.
can at the same time be used to fasten the same on the removable cover.
The positive electrode is formed of a block of retort carbon, which-is. provided
with a number of hollow spaces. These cavities receive a perforated copper lining
which immediately joins on to the carbon and makes the conducting connection
between it and the conductor placed in the hollow space of the electrode.
If the battery is to produce constant current, the copper-iconductors are
embedded in the depolarizing material which more or less fills the space between
the conductors and the inner wall of the copper lining. Copper-oxide, or granu-
lated peroxide of manganese appear to be specially suited for this purpose. The
hollow cavities in the retort carbon can preferably be supplied with the same.
The projecting, ends of the conductors are combined into a conducting cable.
The special form of the positive electrode on which the excellent conduction..of
current depends, consists of the manifold intimate union of the copper, with the
carbon and also that the conducting from the positive electrode is not effected
by one conductor only, but by a number of conductors (the number of which.corre-
sponds to the size of the cell) which are inserted in the cavity of the electrodes,
and, according to the purpose, are more or less embedded in depolarizing. mate-
rial. The copper lining of the cavity is intended to reduce the internal resistance
to a minimum. The electrolyte to be used must not dissolve the copper or only
very slightly so, as otherwise the conductors, on which the action of the cell
depends, would be destroyed. Caustic potash lye appears specially suited for this
purpose.
"
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Anodes of retort carbon have been tried to replace the expensive gold or
こ

page_text: In
platinum anodes. In consequence of the resistance of the retort carbon and the
resulting unequal division of current, they only very partially replace those of
the more expensive metals and are only applicable for certain purposes.
order to obviate this defect the carbon block is provided with a metal plate firmly
joined to it and pressed into the carbon plate. From this metal plate conductors
pass, serving as connecting wires.
These wires are protected from being attacked by the electrolyte or the current
by tubes of non-conducting material. The metal plate is also protected by means
of the covering of retort carbon.
Another kind of application for this invention is a piece of carbon made in this
manner specially adapted for collector brushes for dynamos and motors. Carbon
brushes have the advantage over metal brushes inasmuch as sparking occurs with
them in only a very slight degree and can even in some circumstances be entirely
avoided. Moreover the brushes can be placed vertically to the collector so that
the dynamo can revolve either way without alteration of the position of the
brushes.
On the other hand, however, the carbon brushes have the defect that they are not
such good conductors as the metal brushes, and consequently require to be con-
siderably larger, which again necessitates a larger size collector and causes a
greater frictional resistance.
These defects are obviated by the present invention, the conductibility of the
carbon brushes being so increased by the metal layer (especially if the latter.be
connected by means of a cable with the brush holder) that these current collector
brushes combine all the advantages of the metal brushes whilst avoiding the defects
of the latter.
D
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Datta ut om day one o
W. P. THOMPSON & Co.,
322, High Holborn, London, W.C., Patent Agents for the Applicant.
COMPLETE SPECIFICATION.
Method and Means for Increasing the Conductivity of Carbon to be
Used in Electric Cells and Dynamo Electric Generators and
Motors.
I, CARL WILHELM HERTEL, of 27, Neue Grün Strasse, Berlin, Germany, Manu-
facturer, do hereby declare the nature of my invention and in what manner the
same is to be performed, to be particularly described and ascertained in and by
the following statement:-
Carbon, as is well known, is a material wliich is employed, in various forms,
for a great variety of purposes by electrical engineers.. A serious drawback
attending its use, however, is the relatively high resistance it offers to the pas-
sage of the electrical current. Many attempts have been made to overcome this
inconvenience but for the most part with but little success.
According to the present invention the difficulty is got over in an extremely
simple manner by applying metal internally of the carbon. The precise form,
adopted for the carbon body, as also for the metal lining or core, naturally
depends upon the purpose for which the article is to be employed. By this means
the resistance of the carbon is essentially diminished so that it may be used to
better advantage for a great many purposes.
Thus carbon treated in this manner may be employed to form the positive plate
of a voltaic cell or battery, which is thus rendered extremely strong and effective
in its action.
The cell may with advantage be formed of zinc, carbon and copper in flat
form; any other suitable shape may however be adopted. In the case of small

page_text: cells, the electrode may be given a cylindrical form, the hollow space or chamber
being lined with copper. The conductors can be united in the centre of the
electrode and may serve at the same time for securing the latter to the removable
cover.
On Sheet 1 of the accompanying drawings a positive electrode constructed
according to the present invention is shown.
Fig. 1 is an elevation of the same, a part of the wall of the carbon body being
shown broken away to display the interior.
Fig. 2 is a sectional plan view of the arrangement.
a is the carbon body made of retort carbon and having a series of hollow spaces
or chambers formed in it. Each of these chambers is coated with a copper
lining c, which lies directly on the surface of the carbon and forms the conduct-
ing medium between the latter and the electrolyte or the conductor inserted
into each of the chambers. If the cell is to supply a constant current, the
chambers should be filled with a depolarising agent. Such depolariser may with
advantage consist of copper oxide or granulated manganese binoxide, packed in
the space between the conductor and the copper lining c¹. The chambers, as
also the carbon body itself, may be given any desirable shape. The various con-
ducting wires may be twisted together to form a stranded cable.
The high conductivity of such a positive electrode is due (1) to the multiple
and intimate connection between copper and carbon; and (2) to the current not
being conducted from the positive electrode by a single wire, but by a combina-
tion of conductors, the number depending upon the size of the cell, more or less
embedded in a depolarising agent in the electrode.
The purpose of the copper lining c¹ is to reduce the internal resistance to a
minimum. The electrolyte must be one that does not attack, or only slightly
attacks the copper, as otherwise the conductors, upon which the action of the cell
depends, will be interfered with. Potash lye will be found particularly suitable
for the purpose.
Attempts have also been made to employ retort carbon for anodes hitherto made
of precious metals.
By reason of the low conductivity of the carbon however and the consequent
irregularity of the current, such anodes have proved a poor substitute and can
only be successfully employed in certain cases.
According to the present invention such anodes may be constructed as shown
in Figs. 10-13 (Sheet 2) of the drawings.
Fig. 10 is an elevation of such an anode having a central plate as core.
Fig. 11 is a side view of the same.
Fig. 12 is a view, similar to Fig. 10, of an anode having a cylindrical core.
Fig. 13 is a plan of the latter, the conductor being shown in section.
The carbon body a has pressed into it and secured to it a metal filling or
core b, to which is attached the metallic conductor leading to the outside of the
anode, and which may serve for suspending or securing the latter, and for making
the connection with the conducting wire.
These conductors should be protected by non-conducting coverings to prevent
accidental contact and to guard against their being attacked by the electrolyte
employed for the bath. The metal core itself is prevented from being attacked
and its particles being dissolved by the carbon casing.
The invention may further be applied with great advantage in the manufacture
of brushes for dynamos and motors.
As is well known carbon brushes have the advantage over metal ones, inasmuch
as there is much less sparking at the commutator or collector where they are
employed. Carbon brushes moreover can be adjusted vertically to the commu-
tator so that the machine may be run in either direction without shifting the
brushes.
On the other hand carbon brushes have the disadvantage of being worse con-
ductors than metal brushes, wherefore a larger bearing surface is necessary and

page_text: consequently a greater collector or commutator surface, which causes increased
friction.
By means of the present invention these disadvantages can be overcome...
Figs. 3-9 (Sheet 2) show the invention applied to the construction of such
carbon brushes.
"
Fig. 3 shows an elevation of a carbon brush as having the metal core in the
form of a plate-b, running through its length.
***
"
Fig. 4 shows a cross section of this brush but they kn
The plate b is shown pressed into the center of the carbon body, but it may
equally well be located towards the side.
Fig. 5 shows a cross sectional view of a similar brush a; in which however in
place of a plate of solid copper or copper alloy, the core consists of a bundle. of
wires b.
Fig. 6 shows a similar view of a like brush having a lamellar core, there being
five separate plates. -
Fig. 7 is a corresponding view where, three plates are employed as core,
embedded separately in the carbon.
Fig. 8 shows a like view where the core is formed of four stout metal bars.
Fig. 9 is an elevation of a carbon brush similar to Fig. 3, where the flat metal
core is connected to the brush holder by a cable c. By this arrangement the
conductivity of the brush is still further, increased. Such metal-cored carbon
brushes possess all the advantages of metal brushes, whilst having none of the
disadvantages of ordinary solid carbon brushes.
Fig. 10 is a front view of a flat electrode a, the metal core,b of which is con-
nected with a cable c, which is surrounded by a nonconducting cover d.
Fig. 11 is a side view of this flat electrode.
Fig. 12 is a side elevation of a cylindrical electrode a, having a metal core b, a
cable c and a protecting, nonconducting cover d.
Fig. 13 is the top view of Fig. 12.
1
Having now particularly described and ascertained the nature of
my said
invention and in what manner the same is to be performed, I declare that what
I claim is
1 A body of carbon, having a metal core, filling or lining securely affixed to
it, for the purpose of increasing the conductivity of the carbon, substantially as
described.
2: A carbon as claimed in Claim 1 in combination with an insulated metallic
conductor secured to the said core and leading to the outside of the carbon body,
substantially as described with reference to Figs. 10-13.
3: A carbon electrode having one or more chambers lined with metal, sub
stantially as described with reference to Fig. 1 & 2.
4: A carbon electrode as claimed in Claim 3 in combination with a conductor
secured to said metal lining, substantially as set forth; with reference to
Fig. 1 & 2.
5: A carbon brush for electric generators and motors, having a metal core or
cores, substantially as described with reference to Figs. 3—8.
6: A carbon brush as claimed in Claim 5, in combination with a cable secured
to said core and conducting to the brush holder, substantially as described. with
reference to Fig: 9.
Dated this 8th day of March 1900.
W. REICHAU & P. E. SCHILLING,
Agents for the Applicant.
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