Improvements in Dynamo Electric Machines.
Year: 1894

page_text: The decision of the Chief Examiner, acting on behalf of the Comptroller, of the
5th day of September 1895, allowed, under Section 18 of the Patents, &c.
Act, 1883, an Amendment of this Specification.
Date of Application, 29th May, 1894
Complete Specification Left, 27th Feb., 1895-Accepted, 30th Mar., 1895
Improvements in Dynamo Electric Machines.
I, JOHN AUGUSTINE KINGDON of 29 Marlborough Hill, St. John's Wood
in the County of London, Electrical Engineer, do hereby declare the nature of
this invention to be as follows:-
This invention relates to an improved form of alternator or dynamo for generating
alternating currents.
In my improved alternator. I employ a single exciting coil wound round an iron
or steel magnet core. The ends of the magnet core are fixed to pole pieces of
laminated iron which are suitably shaped so as to partially surround the rotating
inductor. The inductor consists of a drum of laminated iron or steel mounted on
a spindle and having a number of iron or steel projections or teeth. The magnetic
flux set up by the exciting coil passes from one of the laminated pole pieces
across the air gap into the inductor and then across the second air gap into the
second laminated pole piece. A large proportion of the flux passes across into the
teeth of the inductor, so that as the inductor rotates its teeth carry round tufts
of magnetic flux. On the curved faces of the magnetic poles are fixed coils of
conductors. The magnetic tufts from the teeth of the inductor cross the coils
fixed on the pole pieces and induce electromotive force in them. In order to
obtain the aggregate electromotive force of the whole set of inducing coils the
pitch of the coils should be suitably related to the pitch of the inductor teeth.
In some cases the pitch of the teeth is twice the pitch of the coils.
As there is no reversal of magnetic polarity in the fixed laminated iron, but
merely a variation of induction as the inductor teeth revolve, the hysteresis loss is
comparatively small. The magnetic polarity of the inductor iron is reversed only
twice in each revolution, but as the reversals of electromotive force per revolution
are equal to twice the number of inductor teeth it is obvious that a high frequency
or periodicity may be obtained with only a small hysteresis less. Instead of only
two poles having coils on their faces, I may employ four or any higher even
number, with a corresponding increase in the number of exciting coils or magnets.
Instead of a single exciting coil for two poles, I may employ two exciting coils
arranged in any well known manner as at present employed in the construction of
continuous current dynamos.
Dated this 26th dow of Mar 1904
"

page_text: ашргоусщению ш дупаше месите масне.
I, JOHN AUGUSTINE KINGDON of 29 Marlborough Hill, St. John's Wood in
the County 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 relates to an improved form of alternator or dynamo for generating
alternating currents.
In my improved alternator I employ a single exciting coil wound round an iron
or steel magnet core. The ends of the magnet core are fixed to pole pieces of
Jaminated iron which are suitably shaped so as to partially surround the rotating
inductor. The inductor consists of a drum of laminated iron mounted on a spindle,
and having a number of iron projections or teeth. The magnetic flux set up by
the exciting coil passes from one of the laminated pole pieces across the air gap
into the inductor and then across the second air gap into the second laminated pole
piece. A large proportion of the flux passes across into the teeth of the inductor
so that as the inductor rotates, its teeth carry round tufts of magnetic flux. On
the curved faces of the magnet poles are fixed coils of conductors. The magnetic
tufts from the teeth of the inductor cross the conductors of the coils fixed on the
pole pieces and induce electromotive force in them. In order to obtain the
aggregate electromotive force of the whole set of inducing coils the pitch of
the coils should be suitably related to the pitch of the inductor teeth. In some
cases the pitch of the teeth is twice the pitch of the coils.
The same parts are indicated by the same letters in the different figures of the
accompanying drawings.
In Fig. 1. is illustrated an alternator constructed according to my invention,
and having one exciting coil E wound round the core of the iron or steel magnet M.
The ends or poles of the magnet M are bolted to the laminated pole pieces P
and Q, which are built up of iron or steel plates suitably secured together and
to any convenient frame. On the curved faces of the pole pieces P and Q are
fixed in any convenient manner the inducing coils C. The inductor I is built up
of a number of iron plates so as to form a laminated drum D having a number of
projecting teeth T.
The plates are suitably clamped together, and the inductor I
is supported by and keyed to the spindle S which is arranged to rotate in suitable
bearings. The pole pieces P and Q are secured to non magnetic supports N
which are fixed on the bed plate of the alternator. The magnet M is excited by
a continuous current passing through the coil E so as to magnetise the pole
pieces P and Q with opposite magnetic polarities. The inductor I and its teeth
complete the magnetic circuit between the pole pieces P and Q. Those teeth of
the inductor I which are opposite the pole piece P have one polarity and those
teeth which are opposite the other pole piece Q have the opposite polarity. As
the inductor rotates the magnetic flux passing from the teeth T to the pole pieces P
and induces an alternating electromotive force in the inducing coils C fixed on
the faces of the pole pieces P and Q.
The
Figure 2. is a sectional elevation of part of the same alternator, with the inductor
removed. M is the magnet and E the exciting coil wound round the core.
inducing coils C are shown fixed on the face of the laminated pole piece Q.
FF are cast iron or other frames which serve to support and rigidly secure the
plates of the laminated pole piece Q. N is the non magnetic support.
In Figures 1 and 2 the inductor has six teeth and there are eight inducing
coils C, four fixed to the pole piece P and four fixed to the pole piece Q. The
pitch of the coils is half the pitch of the teeth of the inductor. The coils C are
connected up in series or parallel as desired.

page_text: There is no reversal of magnetism in the pole pieces P and Q, but merely a
variation of induction as the inductor teeth revolve. The hysteresis loss due to
this variation of induction is small. The magnetic polarity of the teeth T and the
drum D is reversed twice in each revolution. The number of reversals of electro-
motive force in the inducing coils C per revolution is equal to twice the number of
inductor teeth. An electromotive force of high frequency may therefore be
obtained with a low number of reversals of magnetism and a small hysteresis loss
in the inductor.
In Figure 3. is illustrated an alternator which has two magnets M and M 1 with
two exciting coils E and E 1. The magnets M and M 1 have their lower ends
fixed to the laminated pole piece Q and their upper ends fixed to the laminated
pole piece P. The direction of the exciting current in the coils E and E1 is such
that the pole piece P has one polarity and the pole piece Q the opposite polarity.
The inductor I is similar to that of Figure 1 but has 8 teeth. Inducing coils C
are fixed on the pole pieces P and Q.
Other arrangements of magnets and pole pieces may be employed. For example
I may construct an alternator with four or any higher even number of pole pieces
of alternately opposite polarities and with any convenient number of inducing and
exciting coils.
Having now particularly described and ascertained the nature of my said inven-
tion aud in what manner the same is to be performed, I declare that what I
claim is :-
1. An alternator having a fixed magnet or magnets and fixed pole pieces
supporting inducing coils, and having a toothed inductor rotating between or in
proximity to the pole pieces and completing the magnetic circuit between them.
2. The combination in an alternator of a fixed exciting coil or coils, fixed pole
pieces-supporting inducing coils, with a rotating inductor completing-the-magnetie
eirenit between the pole pieces substantially as described
3. An alternator with fixed exciting and fixed inducing coils and having a
rotating inductor which has the polarity of its teeth reversed as the inductor
rotates.
4. In an alternator a laminated inductor consisting of a drum with projecting
teeth placed in a magnetic field between two poles of opposite-polarities, so that
the teeth-which are opposite one pole have one polarity and those which are
opposite the other pole have the opposite polarity, the polarity of-the-teeth-being
reversed as the inductor rotates.
5. In an alternator an inductor having some of its teeth magnetised with one
polarity and others of its teeth magnetised with the opposite-polarity, the polarity
of the teeth remaining the same as long as they are opposite a pole piece of one
polarity, but being reversed as the-inductor rotates so as to bring the teeth to a
position opposite a pole piece of the other polarity.
G. 2. A toothed laminated inductor rotating between and completing the magnetic
circuit of two or more fixed pole pieces of alternately opposite polarities, so as to
induce an alternating electromotive force in conducting coils fixed on the pole
pieces.
7.3. My improved alternators as herein before described and illustrated in
Figures 1, 2 and 3.