Year: 1894

page_text: Date of Application, 1st Mar.. 1894
Complete Specification Left. 4th Sept. 1894-Accepted 19th Jan
1895
A communication from COMPAGNIE DE L'INDUSTRIE ELECTRIQUE, of Geneva,
Switzerland.
I, ALFRED JULIUS BOULT of 323 High Holborn, in the County of Middlesex,
Chartered Patent Agent, do hereby declare the nature of this invention to be as
follows:-
The first object of the invention is to increase the efficiency of electric current
generators and economize in prime and working cost. Moreover the construction
of these generators is simplified thus diminishing the chances of accidents.
To attain this object, the best way is to diminish as much as possible the loss
due to hysteresis in iron which is the most important to be dispensed with in
establishing good dynamo electric machinery and reduce to a negligible figure the
energy required for exciting the field magnets.
The intensity of the magnetic field in the air gap of the dynamo is varied without
varying the total induction generated by the exciting current, by having one of
the surfaces of pole pieces plain and the other in the shape of toothed wheels, one
being movable relatively to the other.
The total resistance of magnetic circuit and air gap is in this way kept constant
in spite of the movement of one of the surfaces and, by disposing an appropriate
winding close to the plain surface constituting one of the faces of air gap, a current
depending unon the admitted conditions of speed and magnetic field is obtained as
in ordinary dynamos. The loss due to hysteresis is concentrated on the plain
surface and only on a very thin film of it, in such a way that this loss becomes
practically negligible.
Moreover only one exciting coil is required as the poles keep their sign
throughout the complete revolution, the only change being in their intensity with
regard to the different element of the winding.
As to machines designed for generating alternating currents the induced winding
is advantageously wound on this inductor which does not revolve.
In this way, is obtained a machine dispensing with the use of commutators and
brushes as well as with movable electric connections. This point is a great
simplification since the armature is only formed by a kind of toothed wheel inade
of wrought or cast iron or steel without any winding on it.
This process or arrangement may be applied in the case of continuous current
generators, but the necessity of causing the brushes to revolve around the
commutator leads in practice to the placing of the induced winding on the plain
armature which is movable as in ordinary dynamos.

page_text: In a machine more specially intended for producing alternating currents the
inductor determines 2 poles N and S between which revolves an armature
approximately in the shape of a toothed wheel. Close to the S pole the induced
winding is arranged.
The wires pass opposite to the teeth and through intervals between them.
The wires opposite the teeth are subjected to an energetic induction, on account
of the concentration of the magnetic induction in these teeth due to the thinness of
air gap at these places.
The wires opposite the intervals are subjected to a very weak induction in the
same direction, that is to say, in the direction weakening the current generated.
But the difference being very large, the useful current is very strong and can be
advantageously utilized. In order to avoid the production of Foucault's currents
in the mass of S pole, it is made of thin iron sheets insulated one from the other.
The winding for continuous current is the well-known scheme of the multipolar
drum winding.
The ring or Gramme winding may also be utilized, in which case it is found an
advantage to utilize internal as well as external faces of the ring, by toothing
alternatively the two surfaces of the inductor, viz. by placing the teeth of one
surface opposite to the intervals of the other one.
The herein first described example represents the type of the machine with both
inductor and induced windings fixed and a massive movable armature in the shape
of a toothed wheel.
The armature is rigidly secured on a shaft receiving its motion from a pulley or
otherwise and presents nothing peculiar except its simplicity.
The inductor consists of a mass of wrought or cast iron or steel, and a yoke
supporting the foliated pole. These different parts are circular and can be
easily worked or produced upon the lathe. The exciting winding is placed in a
circular cavity. A frame supports the whole construction by means of say two
brackets.
In a machine more specially arranged for continuous currents with drum winding,
the movable armature has a plain surface whilst the fixed toothing is made on the
yoke or outer ring itself.
The currents, alternating or continuous are collected by a commutator.
The peripheral part of the movable armature is also foliated to avoid Foucault's
currents. However, it is not required to extend the foliation throughout the whole
mass as the variations of magnetic induction of field are only felt in the part
opposite to the teeth, whilst on the internal side this intensity is uniform, the
internal part of armature being only a prolongation of the N pole of the inductor.
The N pole may itself be toothed in order to utilize the wires internal to the
ring. Where two sets of teeth are provided they must alternate as otherwise the
induced electro-motive forces would annihilate one another.
The armature may be entirely external to the machine and cover both N and S
poles in which arrangement the movable armature is toothed and bears no winding.
The winding is divided into two parts one on each pole of the inductor. These
poles are foliated. The armature is mounted as a loose pulley and the supporting
shaft is fixed.
The wires are induced and inductive winding pass through the shaft to come
externally without commutator.
Another construction of the machine may have two fixed inductors formed each
of a ring shaped in cross-section in which is provided a coil, and of a bell or
cover fixed to a preferably vertical axis and enclosing the said inductors. The
pole-pieces of the latter are formed of laminated iron and the inner face of the bell
is provided with series of teeth or projections which rotate in front of the said
pole-pieces. The teeth of the bell may be disposed so as to have one set axially
displaced with regard to the other, this being done in view of producing biphased
currents. By means of increasing the number of the rings and of the series of
teeth one may also obtain multiphased currents.

page_text: This invention may be modified without departing from the spirit of the
invention.
Dated this 1st day of March 1801
W. P. THOMPSON & BOULT,
Agents for the Applicant.
A communication from COMPAGNIE DE L'INDUSTRIE ELECTRIQUE, of Geneva,
Switzerland.
ALFRED JULIUS BOULT of 323 High Holborn, in the County of Middlesex,
Chartered Patent Agent 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:--
The primary object of this invention is to increase the efficiency of electric
current generators in order to obtain economy either as regards prime cost or
working cost. My correspondents moreover simplify the 'construction of these
generators thus diminishing the chance of accident.
To obtain this object, the best way is to diminish as much as possible 'the loss
due to hysteresis in iron, which is the most important obstacle to be overcome in
establishing good dynamo electric machinery. My correspondents had also to
reduce to an insignificant figure the energy required for exciting' the field magnets,
My correspondents vary the 'intensity of the magnetic field in the air space of
the dynamo, without varying the total induction generated by the exciting current,
by having one of the surfaces or pole pieces plain and the other in the 'shape of a
toothed wheel, one of these being movable relatively to the other.
The total resistance of magnetic circuit and air space is in this way kept constant
in spite of the movement of one of the surfaces, and by disposing an appropriate
winding close to the plain surface constituting one of the faces of the air space, my
correspondents get a current depending upon the admitted conditions of speed and
magnetic field, as in ordinary dynamos. The loss due to hysteresis is concentrated
on the plain surface and only on a very thin film of it, in such a way that this lošs
becomes practically negligible.
Moreover only one exciting coil is required as the 'polės keep their sign
throughout the complete revolution, the only change being in their intensity
with regard to the different elements of the winding.
As to machines designed for generating alternating currents, the induced winding
is advantageously wound on this inductor which does not revolve.
In this way, my correspondents obtain a machine dispensing with the use of
commutators and brushes as well as with movable electric connections. This point
is a great simplification since the armature is only formed by a kind of toothed
wheel made of wrought iron, cast iron or steel without any winding on it.
This process may be applied in the case of continuous current generators, but the
necessity of causing the brushes to revolve around the commutator leads 'thy
correspondents in practice to place the induced winding on the plain 'armature
which is movable as in ordinary dynamos.
Figures 1 and 2 show two views in cross section through a machine more
especially intended for alternating currents; the inductor determines two
poles N and S between which revolves an armature A in the shape of a
oothed wheel; this shape is fully shown in Figure 2. Close to pole S, the
nduced winding e is fixed. This winding is diagrammatically represented in
Figure 3.

page_text: In view of having the action of the lines of magnetic force upon the induced
coils well understood my correspondents proceed to successively examine different
positions of the toothed wheel in respect of said induced coils.
The coils I, II, III (Figures 3A 3B 3C) are flat coils which have been formed on
a suitable mandrel and then applied and fixed upon the lamellated surface; those
coils are connected to one another in series. The Figures 1, 2 and 3 indicate the
Nos. of the wires of each coil. In their position as shown in Figure 34 the left
side of the coils II and IV and the right side of the coils I and III are crossed by
lines of magnetic force; an induction is therefore produced in the said wires and
the return of the current takes place on the other side of the coil, which is at that
time inactive. In the position shown in Figure 3A the right sides of the coils II
and III and the left sides of the coils II and IV are in action.
In the position shown in Figure 3B the lines of magnetic force emanating from
the teeth pass directly through the intervals left between the right and left part of
each coil. No other induction is produced than that one, caused by the expansion
of the lines of magnetic force; it is very feeble and neutralizes itself completely.
In the position shown in Figure 3° the right hand sides of the coils II and IV
are induced; the sense of the lines of magnetic force having not been changed, the
sense of the electromotive force remains the same; the current circulates in an
inverse sense, the side of the coil which is influenced being the opposite one with
regard to Figure 3A. The sinusoide of the ordinary alternating machines has
therefore been realised. The induction so produced is therefore the result of the
displacement of the lines of force along the induced coil, which displacement is
caused by the rotation of the toothed wheel, whilst the total flux remains absolutely
constant.
The device claimed is therefore quite different in its effect from that of the
dynamo-machines of Sawyer, Brace, Sohlman and others previously patented, in
which the induction is caused by the variation of the number of lines of force in
certain parts of the magnetic circuit. The latter are then the seat of hysteresis
and Foucault's currents which lower the effect of the dynamo; they must be
laminated and are therefore the more subject to violent vibrations which rapidly
disjoin them.
In the machine as claimed the toothed wheel has not to be laminated because, as
already stated, the flux is completely constant and the opposite surface of the air
space that is to say the surface upon which the induced coil is fixed is smooth.
It will be seen that the wire passes opposite to the teeth d and turns between the
teeth at the intervals i.
The wires opposite to the teeth are subjected to an energetic induction, on
account of the concentration of the magnetic induction in these teeth due to the
thinness of air space at these places.
The wires opposite to intervals are subjected to a very weak induction in the
same direction, that is to say, in the direction weakening the current generated.
But the difference being very large, the useful current is very strong and can be
advantageously utilized. In order to avoid the production of Foucault's currents
in the mass of pole S it is made of thin iron sheets insulated one from the other.
Figure 4 is a diagram of the winding for continuous current. It is the well-
known diagram of the multipolar drum winding which therefore needs not to be
described here.
The ring or Gramme winding may also be utilized as indicated in Figures 7
and 8. In this case it is found an advantage to utilize the internal as well as the
external faces of the ring, by toothing alternately the two surfaces of the
inductor viz. by placing the teeth of one surface opposite to the intervals of
the other one.
As already stated Figure 1 represents the type of machine with both inductor
and induced windings fixed and a massive movable armature in the shape of a
toothed wheel.

page_text: The armature A² is strongly bolted on a shaft receiving its motion from a
pulley P and presents nothing peculiar except its simplicity.
The inductor consists of a mass of wrought iron, cast iron or steel M and a yoke
or ring M supporting the foliated pole. These different parts are circular and
can be easily worked upon the lathe. The exciting winding is placed in a circular
cavity. A frame C supports the whole construction by means of two brackets.
fixed against plate M.
Figure shows a machine more specially arranged for continuous currents
with drum winding. As shown it is the movable armature which has a plain
surface whilst the fixed toothing is made on the yoke M' itself.
The currents, alternating or continuous are collected on commutator D.
The periphery of the inovable armature A³ is also foliated to avoid Foucault's.
currents. It is not however required to extend this foliation over the whole mass
as the variations of magnetic induction of field are only felt in the part opposite to
the teeth, whilst on the internal side this intensity is uniform, the internal part of
the armature being only a prolongation of the pole N of the inductor.
Figure 6 shows the disposition of toothing of the yoke of the inductor and the
position of the induced winding of the drum pattern.
Figures 7 and 8 represent the same disposition with the ring, with this difference
that the pole N is itself toothed in order to utilize the wires internal to the ring.
Figure 8 shows the alternation of the teeth, without which alternation the induced
electromotive forces would annihilate one another in each spire of the ring.
Figure 9 is a variation of disposition shown in Figure 1.
The armature is entirely external to the machine and covers both poles N and S.
As in Figure 1 the movable armature is toothed and bears no winding. The
winding is divided into two parts one on each pole of the inductor. These poles
are foliated. The armature is mounted as a loose pulley and the supporting shaft
is fixed.
The wires of induced and inductive windings pass through the shaft so as to come
externally without commutator. Figure 10 is a cross section of this machine
through one of the poles.
Figures 11 to 14 show a very simple and economical construction of such
machines especially adapted for large dynamos with vertical axes of rotation.
Fig. 11 is a vertical section of the whole machine. Fig. 12 is a top view of one
half of the non-rotating part of the machine shown in Fig. 1 and a horizontal
section of half of the revolving part of the same.
Figures 13 and 14 show two alternative dispositions which may be adapted for
the teeth d with which the inner wall of the revolving bell A² is provided.
B is a fixed base upon which bear the arms e of a stationary boss C in which is
located the bearing C for the shaft A.
Upon the base B there are mounted two superposed stationary rings M of cast
iron or steel of approximately U-shaped section, each of these rings containing an
induction coil and being provided with a circular, lamellated pole-piece e.
Upon each of the lamellated pole-pieces e, formed preferably of sheet-iron, there
is provided an induced coil e' disposed substantially as shown in the Figures 34 3º
13 and 14.
The shaft A carries the bell A2 (of cast iron or steel) which covers the above-
described fixed parts and the internal face of whose annular wall is provided with
two rows of teeth d, each of these rows being opposite one of the ring-shaped
poles e.
The teeth d of one row may be placed with respect to those of the other row
either in the position shown in Fig. 14 or in the position shown in Fig. 13
according as one desires to produce single-phased or double-phased currents.
According as either a tooth d or a depression i passes in front of the wires
of the fixed part when the bell A' is rotating the flux of the magnetic current
is caused to vary in one point of the intermediate space and induction is obtained
without varying the total flux created by the exciting current.

page_text: Having now particularly described and ascertained the nature of the said inven-
tion, and in what manner the same is to be performed I am aware that unipolar
machines have long been known, also unipolar machines in which. the field varied
in intensity with armature coils moving in relation thereto; for example they are
described by Mordey in his Specification No. 8262 of 1887, by Foucault, etc.;
I make no general claim to such machines and I am also aware of Atkinson's
Specification No. 6883/89 and make no claim to anything described and claimed
therein, but what I claim is ;-
A dynamo-electric machine substantially as described and illustrated in the
accompanying drawings characterised by the disposition of the walls or surfaces
which limit the air space one of which is smooth and the other one toothed and
the one of said surfaces being movable with regard to the other the induced
coil being placed on the smooth surface and the said disposition having for its
object to cause the intensity of the magnetic field to be made variable in the
air-gap without causing any variation in the total flux created by the exciting
current.
Dated this 4th day of September 1894.
W. P. THOMPSON & BOULT,
Agents for the Applicant.