Improvements in Dynamo-electric Machines.
Year: 1893

page_text: Date of Application, 13th July, 1893
Complete Specification Left, 13th Apr., 1894-Accepted, 13th Aug., 1894
PROVISIONAL SPECIFICATION.
Improvements in Dynamo-electric Machines.
I, ALPHONSE ISIDORE GRAVIER, of 36, Colby Road, Gipsy Hill, in the
County of Surrey, Electrical Engineer, do hereby declare the nature of this
invention to be as follows:-
This invention relates to the construction of dynamo-electric machines,
particularly such as are required to work under conditions involving considerable
variation in load, or duty to be performed.
In electrical traction and certain other applications of electricity, the necessity
arises for affording very considerable increase of power at certain periods; as, for
example, when a car is being set in motion. At such moments, several times the
normal power may be required. If the power of the dynamos employed be not
correspondingly increased, they suffer under the great stress of variation, the heat
is abnormal, and frequently the armature is burned.
The object of the present invention is to provide a machine having a wide
margin for the production, without heating, of energy to many times its normal
power.
In a machine constructed in accordance with this invention, the inductors are
bipolar or multipolar. The pole-pieces are extended in the direction of winding in
order to embrace as much as possible of the wire, so as to obtain the highest
electromotive force for a given length of wire. At right angles to that direction,
they are reduced so as to cover only three consecutive turns or coils of the armature,
in order to have the three consecutive sections of the same potential.
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The armature is of soft iron sheets indented, all of which are insulated to obviate
"Foucault currents. They are in the form of a flat ring with its surface disposed
in such a manner that it has the largest possible periphery for the section given, in
order to utilize as much wire as convenient. The induced copper wire is wound in
one or two layers having for each section induced, the necessary number of turns
to provide the desired electromotive force. The sections must be even in number,
sufficiently numerous, and in proportion to the working margin which it is desired
the machine shall have. Each section is electrically independent of the others.
Each end of a section is joined to a plate of the commutator, in order that the
sections working separately should bring current one after another to the brush ;
that is, if, for example, there are 100 sections, each one would work and heat only
during of a revolution, and would be cooled during the remainder (%) of the
revolution.
The commutator is made as usual of copper plates insulated from one another,
and is used in the ordinary way. Or, two commutators, one on the left and the
other on the right of the armature may be employed; the one receiving the
entrance wire and the other the opposite or exit wire. In the latter case, there is
the advantage of having two independent circuits.
The brushes are of the ordinary kind, normally touching the commutator, and
inclined with constant pressure regulated by adjustable springs. The thickness of
the brushes is such as to enable them to be constantly in contact with two
consecutive plates of the commutator.
This machine is self-excited or excited by an independent circuit provided for
the purpose.
Dated the 10th 1 T11000

page_text: Improvements in Dynamo-electric Machines.
I, ALPHONSE ISIDORE GRAVIER, of 36, Colby Road, Gipsy Hill, in the
County of Surrey, Electrical Engineer, do hereby declare the nature of this
invention and in what manner the same is to be performed to be particularly
described and ascertained in and by the following statement :-
This invention relates to the construction of dynamo-electric machines,
particularly such as are required to work under conditions involving considerable
variation in load, or duty to be performed.
In electrical traction and certain other applications of electricity, the necessity
arises for affording very considerable increase of power at certain periods; as, for
example, when a car is being set in motion. At such moments, several times the
normal power may be required. If the power of the dynamo employed be not
correspondingly increased, it suffers under the great stress of variation, the heat
becomes abnormal, and frequently the armature is burned.
a wide
The object of the present invention is to provide a machine having
margin for the production of energy, and adapted for enabling many times the
normal power to be developed without heating.
In the accompanying drawings,
Fig. 1 is a plan of a machine made in accordance with the present invention.
Fig. 2 is a vertical section on the line A B.
Fig. 3 is a vertical section on the line C D.
Fig. 4 is an end elevation.
Fig. 5 is a side elevation.
In this machine, the inductor is bipolar, but multipolar inductors may be
employed. a and b are electromagnetic cores projecting from a bed-plate d;
c being the wire coils of the inductor. The pole-pieces p are extended in the
direction of the winding of the armature (Figs. and 5)-that is, are extended on
each side of the armature so as to enclose three sides-in order to embrace as much
as possible of the wire, and to obtain the highest electromotive force for a given
length of wire. At right angles to that direction, they are comparatively narrow
and only cover three consecutive coils or sections of the armature, so as to have the
three consecutive coils or sections of the same potential.
The armature is of soft iron sheets indented, all of which are insulated to
obviate "Foucault" currents. They are in the form of a flat ring disposed in such
a manner that it has the largest possible surface opposite the pole-pieces in order
to utilize as much wire of the coils as convenient. The armature is mounted
through the medium of a ring on a spindle f rotating in bearings e.
The copper
wire pertaining thereto is wound in one or two layers having, for each section
induced, the necessary number of turns to provide the desired electromotive force.
The sections should be even in number, must be sufficiently numerous, and in
proportion to the working margin which it is desired the machine shall have. Each
section is electrically independent of the others. Each end of a section is jointed
to a plate of the commutator; in order that the sections working separately should
bring current one after another to the brush; that is, if, for example, in a
bipolar machine there be 100 sections, each one would work and heat only
during of a revolution, and would be cooled during the remainder (38) of the
revolution.
The commutator g is made as usual of copper plates insulated from one another,
and is employed in the ordinary way. Or, two commutators g and g¹, one on the
left and the other on the right of the armature, may be used. The one com-
mutator (9 or g¹) may receive the entrance ends of the wire of the sections of the
_armature, and the other (g' or g) the opposite or exit ends of the wire. With two
"

page_text: commutators, there is the advantage that two independent circuits
and these circuits can be joined in parallel or in series.
may be obtained,
The brushes are of the ordinary kind and their pressure against the commutator
or commutators is regulated by adjustable springs. The brushes are constantly in
contact with two consecutive plates of the commutator.
This machine is self-excited, or may be excited by an independent circuit.
To avoid injurious reactions of the armature upon the inductor, I employ a series
of convolutions or turns of wire m wound upon a frame n made of a substance
which is a bad conductor of electricity. There are sufficient convolutions of
wire m for the current traversing it to generate in the core of the armature a line
of force equal and of opposite polarity to that resulting from the induced current,
so as to counterbalance or destroy the same.
A dynamo-electric machine constructed as above described may be employed as
a motor for utilizing a current of electricity, instead of as a generator for producing
a current.
Having now particularly described and ascertained the nature of this invention
and in what manner the same is to be performed, I claim :-
1. The improved dynamo-electric machine or motor constructed substantially as
described with reference to the accompanying drawings and specially adapted for
working under great variations of load.
2. In a dynamo-electric machine, the employment of an armature comprising
numerous coils or sections of wire electrically independent of one another, and
arranged substantially as herein described; each end of each coil or section leading
to a plate of the commutator or commutators.
3. In a dynamo-electric machine, the employment of two commutators, substan-
tially as herein described, one end of the wire of one coil or section of the armature
leading to one plate of one of the commutators, while the other end leads to the
corresponding plate in the other commutator.
4. In a dynamo-electric machine, the employment of pole-pieces of such a size
that they cover three coils or sections of the armature, substantially as and for the
purpose herein set forth.
5. In a dynamo-electric machine, the employment of pole-pieces which are
extended in the direction of the winding of the coils or sections of the armature,
substantially as and for the purpose herein set forth.
Dated the 12th dow of Anvil 1901
G. G. M. HARDINGHAM,
191, Fleet Street, London, E.C., Chartered Patent Agent.