IMPROVEMENTS IN DYNAMO-ELECTRIC MACHINES OF PACINOTTI'S SORT
Year: 1883

page_text: LETTERS PATENT to Marcel Deprez of Boulevard Saint Denis 1 at Paris
Electrician Engineer for an Invention of IMPROVEMENTS IN DYNAMO-ELECTRIC
MACHINES OF PACINOTTI'S SORT
PROVISIONAL SPECIFICATION left by the said Marcel Deprez at the Office
of the Commissioners of Patents on the 6th April 1883.
MARCEL DEPREZ of Boulevard Saint Denis 1 at Paris, Electrical Engineer,
"IMPROVEMENTS IN DYNAMO ELECTRIC MACHINES OF PACINOTTI'S SORT
"
In dynamo electric machines of the Pacinotti type the placing of the coils on
the rings presents considerable difficulties in practice. The soft iron of these rings
being in a single piece it is necessary to place each coil or section separately.
Besides, in order to lodge as much wire as possible in the outer or upper part of
the ring it is necessary for that in the inner or lower part to overlap.
On the other hand I have verified theoretically and practically that in order to
increase the effect or result derived from these rings it is necessary to give to the
iron a thickness much greater than hitherto. But then the difficulties of manu-
facture above referred to increase so much as to make the work practically
impossible.
Now by means of my invention I overcome these objections.
My invention consists in making the iron of the ring in two parts and in manu-
facturing separately and apart by means of moulds the coils or sections of wire
which are to be placed on the ring. The coils having been made they are slipped
or passed upon the two parts of which the ring is composed and the two parts are
then connected so as to form a whole which presents no projection, no solution of
continuity in a magnetic point of view. Lastly I cover the gaps which remain at
the points of junction either by applying coils or sections thereto in the ordinary
way or by opening out a little the coils or sections already on the ring.
In order to make a half ring of soft iron, I take half circles of iron plate or sheet
of a thickness of from 1 to 5 centimetres and all alike. I superpose them in
sufficient quantity to make up the thickness I require in the ring. The half circles

page_text: are so placed that the odd ones 1, 3, 5 &c project beyond the even ones 2, 4, 6 &c
at one end of the half ring while the even ones project beyond the odd ones at the
other end of the half ring. The half circles being thus arranged they are fixed
together by rivets or like contrivances. The first half of the ring thus presents at
its two ends a series of teeth or projections between which the corresponding teeth
on the second half of the ring can enter. When the ring has thus been made up
connect the two parts by rivets and the ring will then be complete presenting no
projection and no solution of continuity in a magnetic point of view. Of course
before making the junctions I slip the coils or sections of wire on to the half rings;
then when the junctions have been made I open out the sections to cover the gaps
or I apply complementary coils or sections in the ordinary way.
It will be seen that as the coils are made apart the thickness of the rings does
not interfere with their manufacture. But when this thickness does not vary, a
part of the space where wire might be placed is lost at the outer part. To prevent
this I make two sets of coils different in their form but presenting the same electric
resistance and I place them on the ring alternately. The coils 1, 3, 5 &c are alike
and the coils 2, 4, 6 &c are also alike, but the outer dimensions of the latter
are increased so that the former may at their inner part lie to some extent
within them.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed
by the said Marcel Deprez in the Great Seal Patent Office on the
27th September 1883.
MARCEL DEPREZ of Boulevard Saint Denis 1 at Paris Electrician Engineer
"IMPROVEMENTS IN DYNAMO ELECTRIC MACHINES OF PACINOTTI'S SORT
"
In dynamo electric machines of the Pacinotti type the placing of the coils on the
rings presents considerable difficulties in practice. The soft iron of these rings
being in a single piece it is necessary to place each coil or section separately.
Besides, in order to lodge as much wire as possible in the outer or upper part of
the ring it is necessary for that in the inner or lower part to overlap.
On the other hand I have verified theoretically and practically that in order to
increase the effect or result derived from these rings it is necessary to give to
the iron a thickness much greater than hitherto. But then the difficulties of
manufacture above referred to increase so much as to make the work practically
impossible.
Now by means of my invention I overcome these objections.
My invention consists in making the iron of the ring in two parts and in manu-
facturing separately and apart by means of moulds the coils or sections of wire
which are to be placed on the ring. The coils having been made they are slipped
or passed upon the two parts of which the ring is composed and the two parts are
then connected so as to form a whole which presents no projection, no solution
of continuity in a magnetic point of view. Lastly I cover the gaps which remain
at the points of junction either by applying coils or sections thereto in the ordinary
way or by opening out a little the coils or sections already on the ring.
In order to make a half ring of soft iron I take half circles-see Figure 1 of the
annexed drawings of iron plate or sheet of a thickness of from 1 to 5 centimetres
and all alike. I superpose them-see Figure 2-in sufficient quantity to make up
the thickness I require in the ring-The half circles are so placed that the odd
ones, 1, 3, 5, &c., project beyond the even ones, 2, 4, 6, &c., at one end of the half
ring while the even ones project beyond the odd ones at the other end of the half
ring as clearly seen in Figure 2. The half circles being thus arranged they are
fixed together by rivets a a or like contrivances. The first half of the ring thus
presents at its two ends a series of teeth or projections between which the corre-
sponding teeth on the second half of the ring can enter. When the ring has thus
been made up see Figure 3-I connect the two parts by rivets Bẞ and the ring
will then be complete presenting no projection and no solution of continuity in a
magnetic point of view. Of course before making the junctions I slip the coils or
sections of wire on to the half rings; then when the junctions have been made I
open out the sections to cover the gaps or I apply complementary coils or sections
in the ordinary way,
It will be seen that as the coils are made apart the thickness of the ring does
not interfere with their manufacture. But when this thickness does not vary, a
part of the space where wire might be placed is lost at the outer part. To prevent
this I make two sets of coils different in their form but presenting the same electrio
resistance and I place them on the ring alternately-see Figure 4. The coils
1, 3, 5, &c., are alike and the coils 2, 4, 6, &c., are also alike, but the outer dimen-
sions of the latter are increased in the direction a b Figure 4 so that the former
may at their inner part lie to some extent within them.
Having now described the nature of my said invention and in what manner the
same is to be performed I declare that I claim :-
Constructing dynamo electric machines of the Pacinotti type in which the iron

page_text: of the ring is made in two parts so that the coils or sections of wire can be formed
separately by means of moulds and in which after these sections have been placed
on the ring the two parts of the latter are connected together whereby a ring is
obtained without any projection and without any solution of continuity in a
magnetic point of view, substantially as hereinbefore described.
In witness whereof I the said Marcel Deprez have hereunto set my hand and
seal this twenty fifth day of September One thousand eight hundred and eighty
three
Witness:
Albert Caben
Civil Engineer
of Boulevard Saint Denis 1
at Paris
MARCEL DEPREZ (L.S.)

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