Improvements in Dynamo Electric Machines.
Year: 1894

page_text: Date of Application, 21st Dec, 1894
Comp ete Specification Left, 17th Sept.. 1895-Accepted, 19th Oct., 1895
PROVISIONAL SPECIFICATION.
Improvements in Dynamo Electric Machines.
We, ALEXANDER BEWICKE BLACKBURN, of Bushbury Works, Wolverhampton
in the County of Stafford, Civil Engineer, and, WILLIAM BUCHANAN, of
Bushbury Works, aforesaid, Electrical Engineer, do hereby declare the nature of
this invention to be as follows.-
According to this invention we employ coils in which alternating curents are
produced and which constitute the armature coils and a coil through which a
continuous or rectified current is passed and which constitutes the exciting coil.
We also employ sets of lamuntions or plates shaped so that those of one set
embince the exciting coil and one of the amature coils and those of the next set
embince the exciting coil and the other of the armature coils and so on alternately.
These laminations or plates constitute one portion of the magnetic circuit which is
completed by a moving portion constituting the inductor portion consisting of
projecting portions of a width preferably about equal to the distance between the
mid imes of adjacent sets of laminations or plates. The said inductor portion is
caused to revolve in any convenient way such as by being fixed to a wheel driven
by a shaft
The projections of the inductor portion as they pass the several sets
of laminations or plates complete the magnetic circuit around the exciting coil and
alternately the one and the other of the armature coils the number of lines of
magnetic force through the armature coils being at a maximum when the pro-
jections of the inductor portion pass them the magnetic force diminishing as it
leaves them, and increasing in the next set and so on and as the sets of laminations
or plates are equal it follows that there is always the same or about the same
number of lines of magnetic force passing through the inductor portion and as these
are always in the same direction there can be no change of induction through the
exciting coil
It will be seen that alternating currents of equal period and (when
the number of tuins in the armature coils are the same) of equal electio-motive
force, but opposite phases, will be generated in the armature coils. Instead of the
armature coils and the series of sets of laminations or plates there may be a greater
number of each, say three or four arranged so that as the inductor portion revolves
it closes the magnetic circuit successively around each of the several amature
coils and the exciting coil at equal time intervals so that alternating curieuts
differing in phase in accordance with the number of amature coils and settes of
sets of Inminations or plates will be generated in the armature coils. The exciting
coil may be attached and revolve with the inductor portion or instead the armature
coils and the sets of laminations and plates can be made to revolve whilst the
other paits remain stationary. By means of a rectifier or commutator the machine
could be used to give continuous currents.
Dated this 21st day of December 1894.
JOHNSONS & WILLCOX,
47 Lincoln's Inn Fields, London, W.C., Agents.

page_text: Improvements in Dynamo Electric Maonines.
We, ALEXANDER BEWICKE BLACKBURN, of Bushbury Works, Wolverhampton,
in the County of Stafford, Civil Engineer, and WILLIAM BUCHANAN of Bushbury
Works aforesaid, 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 m and by the following statement:-
According to this invention we employ coils in which alternating curients are
produced, and which constitute the armature coils, and a coil through which a
continuous, o rectified curient is passed, and which constitutes the exciting coil.
We also employ sets of laminations, or plates, shaped so that those of one set
embrace the exciting coil and one of the aimature coils, and those of the next set
embrace the exciting coil and the other of the atmature coils, and so on alternately.
These laminations, or plates, constitute one portion of the magnetic circuit which
E completed by a moving portion, constituting the inductor portion, consisting of
projecting portions of a width preferably about equal to the distance between the
mid-lines of adjacent sets of laminations, or plates. The said inductor portion1 19
caused to revolve in any convenient way, such, for example, as by being fixed to
a wheel duiven by a shaft. The projections of the inductor portion as they pass
the several sets of laminations, or plates, complete the magnetic circuit around the
exciting coil and alternately the one and the other of the armaturo coils, the
number of lines of magnetic force through the armature coils being at a maximum
when the projections of the inductor portion pass them, the magnetic force
diminishing as it leaves them, and increasing in the next set, and so on, and as
the sets of laminations, or plates, are equal, it follows that there is always the
same, or about the same, number of lines of magnetic force passing through the
inductor portion and as these are always in the same duection there can be no
change of induction through the exciting coil. It will be seen that alternating
cuntents of equal period, and, (when the number of tuins in the armature coils are
the same), of equal electro-motive force, but opposite phase, will be generated in
the armature coils. Instead of two aimature coils, and two series of sets of
laminations, or plates, there may be a greater number of each; say three, or four,
arrauged so that as the inductor portion revolves it closes the magnetic encuit
successively around each of the several armature coils and the exciting coil at
equal time intervals, so that alternating curients differing in phase in accordanco
with the number of armature coils, and series of sets of laminations, or plates, will
be generated in the armature coils. The exciting coil may be attached to and
revolve with the inductor portion, or instead the armature coils and the sets of
laminations, or plates, can be made to evolve whilst the other parts remain
stationary. By means of a rectifier, or commutator, the machine can be used to
give continuous currents
To enable the invention and the manner in which it may be performed to be
readily understood the annexed drawings are given, in which
Figures 1 and 2 are a section and a side elevation of a dynamo for generating
single phase curents.
Figure 3 shews, separately, the form of the plates, laminations, or
stampings, A. B.
Figures 4 and 5 are sections, at right angles to each other, of part of a dyшamo,
shewing a modified arrangement for three phase currents.
Figure 6 shews the form of the plates, laminations, or stampings, A. B, and
Figure 7 shews the form of the plates, laminations, or stampings C.
118 the moving portion of the magnetic circuit constituting the inductor. It
is caused to evolve by being part of, or attached to, a wheel fixed on a shaft

page_text: which may be driven in the usual way.
alternating ourrents are produced and
continuous, o rectified current is passed
a, b, are the armature coils in which
is the exciting coil through which a
A, B, are lammations, plates, or stampings, of magnetic metal, forming, with the
inductor I, the magnetic cu euit by being arranged around the coils as herein befor
described, and as clearly shewn in the diawings. Each set is held in place by
clamps as at a.
When the inductor is in the position in which it completes the magnetic
cncunt round the coils and a, the number of lines through the coil a is at ab
maximum As the inductor I passes from the parts of the coil a surrounded by
the magnetic laminations, plates, or stampings A to the parts of the coil b
surrounded by the magnetic laminations, plates or stampings B the number of
lines through the coil a diminishes, while the number through the coil & increases
at the same rate, and, as the reluctances of the cncuits A, and B, are equal, it
follows that there is always the same number of lines passing through the
Inductor 1, and, as these are always in the samo direction, there can be no chauge
of induction through the exciting coil.
It will be seen that alternating currents of equal periodicity and, (when the
number of turns in the coils a and b are the same), of equal electro-inotive force,
but opposite phase, will be generated in the coils a and b
Figures 4 and 5 shew an arrangement suitable for generating three phase
currents, in which arrangement three arminture coils a be are formed into separato
magnetic circuits by the plates A, B, C. As the inductor 1 revolves it closes the
circuits A, B, C, cousecutively, and at equal time intervals, so that alternating
currents, dillering in phase by one third of a period, will be generated in the
coils a, b, and c, but, as before, there is no change of induction in the coil f Bv
employing four armature coils, and four magnetic circuits, currents, differing in
phase by one quarter period, can be gonorated in a similar manner. In carrying
out this design the exciting coil need not be fixed but can be attached to the
moving part I, or this can be fixed and the armature coils with the laminations,
plates or stampings of magnetic material be revolved.
As before stated, by means of a suitable rectifier, or commutator, the machine
can be used to give continuous currents, and by suitably proportioning the relative
uumber of turns in the field magnot and the armature coils, the machine can be
mado to give either a constant current, or constant potential, at the terminals.
Having now particularly described and ascertained the nature of our said inven-
tion, and in what manner the same is to be performed, we declare that what we
claim is
1. A dynamo-electric machine in which the coils have upon them magnetic
material so aanged, relatively to the projections of the magnetic inductor, that
there is no fluctuation, or but little fluctuation, in the number of lines through the
exciting coil, substantially as hereinbefore described.
2 In dynamo-clectic machines the combinations of coils, and laminations,
plate, or stampings, and a magnetic inductor, all arranged and combined according
to the several modifications herembefore described, and illustrated in the accom-
panying diawings
Dated this 17th dox of Sontember 1895
JOHNSONS & WILLCOX,
47 Lincoln's Inn Fields, London, W.C., Agents.