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

page_text: Date of Application, 23rd May, 1391
Complete Specification Left, 11th Dec., 1891-Accepted, 21st May, 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 refers to dynamo-electric and electro-dynamic machines; its
objects being to increase the relative potential energy evolved, to enable the wire in
the armature to be of less resistance proportionately to that potential energy,
to reduce the hysteresis, and to lessen the loss of energy arising from over-heating.
A bipolar machine constructed according to my invention comprises two electro-
magnets arranged in the same plane: the armature being between them. On each
side of the pole of each electromagnet, a supplementary pole is placed; the
supplementary poles pertaining to each electromagnet being of opposite sign to that
of the central pole. These supplementary poles are used instead of the ordinary
enlarged pole-pieces, and they should be placed close against the central pole.
They may be wound with wire, but it is not essential for them to be so wound.
There are four brushes arranged radially these brushes being directed toward
points between the central poles of the electromagnets and the supplementary poles
thereof.
In an ordinary machine, change of polarity in the coils of the armature takes
place in the period occupied by the armature in making half a revolution; but, in
a machine constructed according to my improved method, the time required for
change of polarity is only a fraction of that period. Another important result is
that the two circuits in the improved machine are independent, and can therefore
be joined either in series or parallel.
The bipolar machine hereinbefore described is given by way of example only.
Instead of three poles, four, five or a poles placed near together can be used; the
number of brushes being three, four or a-1.
Dated this 18th 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 manner the same is to be performed to be particularly described and
ascertained in and by the following statement:-
This invention refers to dynamo-electric and electro-dynamic machines; its
objects being to increase the relative potential energy evolved, to enable the wire
in the armature to be of less resistance proportionately to that potential energy, to
reduce the hysteresis, and to lessen the loss of energy arising from overheating.
The accompanying diagram represents a bipolar electromagnetic system em-
bodying my invention and comprising four supplementary poles.
A bipolar machine constructed according to my invention has two electromagnets
arranged in the same plane; the armature A being between them. On each side
of the pole N pertaining to one electromagnet a supplementary pole s or s' is
placed; a supplementary pole or a being located on each side of the pole S
Price 8d.

page_text: pertaining to the other electromagnet. The supplementary poles s and s¹ or »and »'
are of opposite sign to that of the central pole. These supplementary poles
and sorn and n are used instead of the ordinary enlarged pole-picces, and they
should be placed close against the central pole N or S. They may be wound with
wire, but it is not essential for them to he so wound. There are four brushes
arranged radially on the lines b₁a and a; that is, the brushes are directed
towards points between the central pole N or S of the electromagnet and the
supplementary poles and a¹ or n and »'.
In an ordinary machine, change of polarity in the coils of the armature A takes
place in the period occupied by the armature in making half a revolution; but, in a
machine constructed according to my improved method, the time required for
change of polarity is only a fraction of that period. Another important. result is
that the two circuits in the improved machine are independent, and can therefore
be joined together or worked separately.
The bipolar machine hereinbefore described is given by way of example only.
Instead of two electromagnets with three poles to each electromagnet, four, five or n
electromagnets with their respective poles placed near together can be used the
number of brushes being three, four or -1.
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. In a dynamo-electric or electro-dynamic machine, the employment of supple-
mentary poles s and s³ or n and n² arranged or operating substantially as described
with reference to the accompanying diagram.
2. In a dynamo-electric or electro-dynamic machine, the combination, with a
central pole N or S, of supplementary poles s and s'or n and n', substantially as
and for the purposes set forth.
3. In a dynamo-electric or electro-dynamic machine, the combination, with an
armature A, of a central pole N or S and the supplementary poles. s and s
or n and n¹, substantially as and for the purposes set forth.
Dated this 21st day of November 1891.
G. G. M. HARDINGHAM,
191, Fleet Street, London, E.C., Chartered Patent. Agent.