Improvements in Dynamo-electric and Electro-dynamic Machines.
Year: 1891

page_text: Date of Application, 15th Apr.. 1891
Complete Specification Left, 11th Dec.. 1891-Accepted, 14th Apr., 1892
PROVISIONAL SPECIFICATION.
Improvements in Dynamo-electric and Electro-dynamic Machines.
I, ALPHONSE ISIDORE GRAVIER, of 186, Boulevard Péreire, Paris, in the
Republic of France, Electrical Engineer, do hereby declare the nature of this
invention to be as follows:-
:-
This invention relates to dynamo-electric machines for generating constant,
undulatory or alternating currents, and to electro-dynamic engines for use as
motors; its objects being to increase the actual power of such machines, first, by
utilizing to better advantage the flow of magnetic force between the poles of the
electro-magnets, thereby enabling the resistance of the wire on the armature to be
diminished relatively to the potential energy produced; secondly, by reducing the
tendency (which is proportional to the number of turns between two brushes) of
the armature to react on the coils of the electromagnets, thus reducing the
hysteresis to a minimum; and, thirdly, by reducing the loss of energy from
overheating.
"
In a dynamo-electric machine for generating a constant current, I prefer to
employ a ring armature of the "Gramme type, the diameter of which is
relatively large compared with its transverse section. The ring is built up of a
series of very thin iron discs or strips cemented together; each disc or strip being
insulated from the adjoining discs or strips. The surface of the ring thus formed
is covered with insulating material and wound with a single layer of copper wire,
so as to form either a continuous or a divided circuit, as hereinafter explained.
An ordinary commutator is used. The pole-pieces of the electromagnets can be
placed anywhere in relation to the armature, according to the construction of the
machine. The pole-pieces are not expanded.
The flow of force from the poles at once enters the iron of the ring; acting
only on those parts of it which are directly opposite the pole-pieces, so that all
other parts of the ring are not acted upon by the electromagnets. There is,
consequently, no variation of flow in the greater part of the iron of the ring on
ench side between the poles, and consequently there is no induction in the wire
in these parts of the ring. The position of the brushes is varied accordingly.
Four brushes are employed when the poles are opposite one another; but, when
The brushes are so
they are near together, only three brushes are required.
placed as to always occupy the same position independently of wear, so that the
use of more than two brushes does not cause any complication in the construction.
The employment of four or three brushes may, however, be avoided, and two
only used, if, as in the multipolar machines, the ends of sections of the same
potential be joined to the same plate of the collector or commutator.
The
The wire in the armature, being only a single layer, presents a large cooling
surface. Between two brushes there is a minimum of turns, and consequently a
minimum of resistance, a minimum of loss by heat, and a minimum of ampère
turns (which cause reaction of the ring on the coils of the electromagnets).
heating of the ring is further diminished owing to any given part of the wire in
the armature working during a portion only of the time occupied in travelling from
pole to pole.
In the present system, I can use all known methods of excitation: in series or
in parallel, or partly in series and partly in parallel; or independent. And I can
employ more than one pair of poles, thus collecting more than one independent
induced current; the induced currents being joined either in series or in parallel,
a high mean electrical force or a large current resulting. Under such circum-
stances, I make as many sections of the wire in the armature as there are poles,

page_text: "
and couple them up thus:-Suppose, by way of example, that there are twenty
groups. I then join the exit end of "No. 1 to the entrance end of "No. 11," and
the entrance end of "No. 1 to the exit end of No. 11," and so on. Ten pairs
of brushes would he employed each current being collected independently.
"
:
A dynamo-electric machine for generating an undulatory current is constructed
in a similar manner, with the exception that the commutator has fewer plates. If
the total number of turns of wire be divided into twenty sections, employ
twenty plates in the commutator. These are used separately or joined either in
parallel or in series. The free ends of the wire in each group are connected
independently to two plates of the commutator. I thus obtain a number of
currents in the same direction; these being separate or joined in series or in
parallel one to another. The commutator may consist of insulatel plates or plates
connected in the usual manner. This arrangement enables the number of turns
between the brushes to be lessened as much as possible in order to diminish the
self-induction.
In a dynamo-electric machine for generating alternating currents, a fine wire
with few turns is used in order to preserve to the fullest extent the actual
resistance and diminish the self-induction. The armature is similar to the one
previously described in reference to the machine for generating a constant current.
The single layer of wire is divided into a number of sections, which are alternately
wound in different ways and connected in pairs either in parallel or in series. The
free ends are each joined to one of the brass plates in the commutator. The
brushes work against these plates. In this way, every section in turn supplies its
portion of electrical energy to the main current.
In the machines for generating undulatory or alternating currents, more than
one pair of poles may be employed, as in the constant current machine.
The continuous current machines above described can be employed as electro-
dynamic motors or receivers and as rotary transformers:-
As receivers, if the wire on the armature be increased in section until its
resistance is diminished by one half. Thus, if the machine acting as generator
have one circuit, the machine acting as receiver has two circuits joined in parallel.
In this manner, the maximum degree of efficiency is obtained.
As rotary transformers, when the generator and the receiver have independent
circuits; the former being discharged in series and the latter in parallel.
Dated this 15th day of April 1891.
G. G. M. HARDINGHAM,
191, Fleet Street, London, E.C., Agent for the Applicant.
COMPLETE SPECIFICATION.
Improvements in Dynamo-electric and Electro-dynamic Machines.
I, ALPHONSE ISIDORE GRAVIER, of 47, Broad Street Avenue, in the City of
London, Electrical Engineer, do hereby declare the nature of this invention and
in what mamer the same is to be performed to be particularly described and
ascertained in and by the following statement :-
This invention relates to dynamo-electric machines for generating constant,
undulatory or alternating currents, and to electro-dynamic engines for use as
motor its objects being to increase the actual power of such machines; first, by
utilizing to better advantage the flow of magnetic force between the poles of
the electromagnets, thereby enabling the resistance of the wire on the armature
to be diminished relatively to the potential energy produced; secondly, by
reducing the tendency (which is proportional to the number of turns between two
brushes) of the armature to react on the coils of the electromagnets, thus
reducing the hysteresis to a minimum and, thirdly, by reducing the loss of
energy from overheating.

page_text: In the accompanying drawing.
Fig. 1 is a diagram shewing ordinary expanded pole-pieces.
Fig. 2 represents the pole-piece arranged according to my invention: there
being one chief pole, which is not expanded.
Fig. 3 is a similar view shewing two chief poles.
Fig. 4 is an end elevation of an electro-dynamic single circuit machine
embodying the construction shewn in Fig. 2, with the pole-pieces arranged
laterally and not expanded.
Fig. is a correspon ling side elevation.
Fig. is a horizontal section on the lines 6-6 in Figs. 4 and 5.
Fig. 7, 8 and 9 are diagrams illustrating modifications.
In a dynamo-electric machine for generating a constant current, I prefer to
employ a ring armature A of the Gramme type, the diameter of which is
relatively large compared with its transverse section, which may be cylindrical,
square or polygonal. The ring is built up of a series of very thin soft iron
annular dises, strips or wires cemented together. The mass of iron thus formed is
insulated according to requirements; that is, according to the potential to be
produced. The surface of the ring thus formed is wound with a single layer of
copper wire, also insulated according to the potential to be produced, so as to
form one
or more continuous circuits, as hereinafter explained. An ordinary
commutator is used, with the plates or strips of which the circuit or circuits is or
are united in the ordinary way. The pole-pieces of the electromagnets and ("
can be placed anywhere in relation to the armature, according to the construction
of the machine. The chief pole-piece N or pole-pieces N and S are not expanded.
The surface of the pole-piece N or S is, at most, equivalent to that of the
section of the core of the armature, and is smaller than that of the section of the
body of the electromagnets. Its shape may, however, be varied. On each side
of the principal pole-piece, I arrange a secondary pole. In Fig. 2, the secondary
pole-pieces are marked and In Fig. 3, there are four secondary pole-
pieces, s. and n¹. The principal pole-piece N or S and its secondary pole-
pieces s and or a and a complete the electromagnetic system which closes on the
armature.
"
The secondary pole-pieces s and or, and are preferably not expanded,
as indicated in unbroken lines in Figs. 2 and 3. They may, however, be expanded
without inconvenience, as indicated in broken lines in those figures. In Fig. 2,
the secondary pole-pieces s and, as shewn by the broken lines, have been
expanded until they met. In Fig. 3, the secondary pole-pieces have been
expanded, as repre-ented by the broken lines, until the pole-piccess and shave
met the pole-pieces and n'
ก
The flow of force from the the pole N or poles N and S at once enters the iron of
the ring A; acting only on those parts of it which are directly opposite the pole-
piece or pole-pieces, so that all other parts of the ring are not acted upon by the
electromagnet. There is, consequently, no variation of flow in the greater part of
the iron of the ring, and consequently there is no induction in the wire therein. The
position of the current-collecting brushes is varied accordingly. In Fig. 2, the brushes
are placed between N and N; and, in Fig. 3, between Ns and Na and Sa
and
In Fig. 7 and 8, four brushes are used, two to each pole-piece these
being at and band and
It will thus be seen that four bru-hes are
employed when the pole-picces are opposite one another or some distance apa
When they are near together, as in Fig. 9, only three brushes are required; these
being at n', bs and . The brushes are so placed as to always occupy the saine
position independently of wear, so that the use of more than two brushes does not
cause any complication in the construction. In the arrangement shewn in Fig. 9,
where the pole-piece N is sufficiently near to the pole-piece S. the brush at ba
may be dispensed with.
Further, the employment of four or three brushes may be avoided, and two

page_text: only used, if, as in the multipolar machines, the ends of sections of the same
potential be joined to the same plate of the collector or commutator.
Two
brushes B and B' are shewn in Fig. 4.
The wire in the armature, being only a single layer, presents a large cooling
surface. Between two brushes there is a minimum of turns, and consequently a
minimum of resistance, a minimum of loss of heat, and a minimum of ampère
turns (which cause reaction of the ring on the coils of the electromagnets). The
heating of the ring is further diminished owing to any given part of the wire in
the armature working during a portion only of the time occupied in travelling
from pole to pole.
In the present system, I can use all known methods of excitation: in series
or in parallel, or partly in series and partly in parallel; or independent.
And, I can employ more than one pair of poles, thus collecting more than one
independent induced current; the induced currents being joined either in series or
in parallel, a high mean electrical force or a large current resulting. Under such
circumstances, make as many coils or sections of the wire in the armature as
there are poles, and couple them up thus --Suppose, by way of example, that
there are twenty groups.
I then join the exit end of No. 1" to the entrance
end of No. 11," and the entrance end of No. 1" to the exit end of "No. 11,"
and so on.
Ten pairs of brushes would be employed; each current being collected
independently.
Two pole-pieces reduced can be placed at the extremities of two arms, as
illustrated in Figs. 7 to 9. This arrangement is, however, not so good as the one
described above. The pole-picces may be in the same plane as the armature and
be placed near the exterior of the ring; or near its interior, if the size of the
armature permit. They may, moreover, be placed laterally.
66
22
In machines constructed as indicated in Fig. 1, the brushes are diametrically
opposite and, being the total number of turns in the armature, comprise turns.
which have a resistance denoted by the following equation, being the resistance
of a turn-

page_text: The two
In this machine, four brushes are used to collect the two current=.
currents may be utilized separately. Two of the four brushes may be dispensed
with; in which case, I dispose the several distinct circuits in such a
manner that
n
the brushes may be place 1 at and 6. The number of the circuits is equal to n;
#
771
representing the number of turns between the brushes.
ก
must be an even
number. Of the two brushes, he is at and the other at a; or, one at and
the other at ba.
To obtain independent current, the dimensions of the armature are increased,
and an inductive electromagnetic system, such as that described with reference to
Fig. 3, to each current required is employed; the electromagnetic systems being
preferably placed equidistantly round the armature. The currents being inde-
pendent, can be grouped in series or in parallel.
By winding the multiple circuits of the armature alternately first in one
direction and then in the other, multiple alternate currents, which can be grouped
in series or in parallel, are produced.
A dynamo-electric machine for generating an undulatory current is constructed
in a similar manner,
with the exception that the commutator has fewer plates. If
the total number of turns be divided into twenty sections, I employ twenty plates
in the commutator. These are used separately or joined either in parallel or in
series. The free ends of the wire in each group are connected independently to
two plates of the commutator. I thus obtain a number of currents in the same
direction; these being separate or joined in series or in parallel one to another.
The commutator may consist of insulated plates or of plates connected in the
usual manner. This arrangement enables the number of turns between the
brushes to be lessened as much as possible in order to diminish the self-induction.
In a dynamo-electric machine for generating alternating currents, a fine wire
with few turns is used in order to preserve to the fullest extent the actual
resistance and diminish the self-induction. The armature is similar to the one
previously described in reference to the machine for generating a constant current.
The single layer of wire is divided into a number of coils or sections, which are
alternately wound in different ways and connected in pairs either in parallel or in
series. The free ends are each joined to one of the brass plates in the commutator.
The brushes work against these plates. In this way, every section in turn
supplies its portion of electrical energy to the main current.
In the machines for generating undulatory or alternating currents, more than
one pair of poles may be employed, as in the constant current machine.
The continuous current machines above described can be employed as electro-
dynamic motors or receivers and as rotary transformers:-
As receivers, if the wire on the armature be increased in section until its
resistance is diminished by one half. Thus, if the machine acting as generator
have one circuit, the machine acting as receiver has two circuits joined in parallel.
In this manner, the maximum degree of efficiency is obtained.
As rotary transformers, when the generator and the receiver have independent
circuits; the former being discharged in series and the latter in parallel.
Having now particularly described and ascertained the nature of this inven-
tion and in what manner the same is to be performed, I claim
--
1. The improved dynaino-electric or electro-dynamic machine having a Gramme
armature with simple or multiple coils and electromagnets arranged as described,
whereby the resistance in the arinature is reduced as far as possible, the power of
the machine being correspondingly increased, substantially as herein st forth.
2. In a dynamo-electric or electro-dynamic machine having a Gramme armature
with multiple coils, the combination, with the armature, of electromagnets so

page_text: arranged as to dispense with two brushes, two brushes instead of four being
employed, substantially as set forth.
3. In a dynamo-electric or electro-dynamic machine having a Gramme armature
with multiple coils, the combination, with the armature, of a number of electro-
magnets equal in number to the coils of the armature and arranged as described so
as to obtain a corresponding number of multiple currents capable of being joined
in series or in parallel, substantially as set forth.
4. In a dynamo-electric or electro-dynamic machine having a Gramme armature
with multiple coils, the coils being wound in opposite directions alternately, the
combination, with the armature, of a number of electromagnets equal in number
to the coils of the armature and arranged as described so as to obtain alternate
currents capable of being joined and utilized in series or in parallel, substantially as
set forth.
Dated this 21st day of November 1891.
G. G. M. HARDINGHAM,
191, Fleet Street, London, E.C., Chartered Patent Agent.