Improvements in Alternate Current Dynamos.
Year: 1896

page_text: Date of Application, 9th Feb., 1808
Complete Specification Left, 9th Nov., 1896-Accepted, 9th Jan., 1897
Complete Specification Left, 9th Nov., 1896-Accepted, 9th Jan., 1897
PROVISIONAL SPECIFICATION.
Improvements in Alternate Current Dynamos.
We, WALTER CLAUDE JOHNSON, of The Dignaries, Westcombe Park,
Blackheath in the County of Kent, LOUIS JOHN STEELE, of 14 Clarendon
Road, Holland Park in the County of London, and JOHN WILLIAM EWART
of 21 Inverine Road, Old Charlton, in the County of Kent, Electrical Engineers
do hereby declare the nature of this invention to be as follows:-
Our invention relates to improvements in alternate current dynamos whereby
special advantages in the construction of such machines are obtained as will be
hereinafter described.
The invention relates more particularly to that construction of such dynamis
in which the armature is of annular form surrounding the field magnets which
revolve.
We build up the armature of thin iron laminations insulated from one another,
and forming preferably as closed a magnetic circuit as possible, in which armature
the conductors are buried. According to one mode of construction we build up
such armature of a number of sections, of which there may be as many or half as
many as there are poles on the field magnets, the radial or side faces of these sections
butting close together, being if necessary tooled to produce as close a fit as possible.
The inner surface of the armature consequently presents a practically continuous
annular face to the field magnets.
According to another mode of construction we form the iron laminations so as
to be built up into a continuous ring instead of in sections. In either construction
these sections or the continuous ring have or has recesses which in the case of the
sections are formed along their meeting sides for the reception of the conductor
coils so that these shall be completely imbedded therein and one essential feature
of our invention consists in so constituting the said recesses, that the coils can be
built up on a former independently of the core sections and the sections or complete
ring can be built up independently of the coils, which are subsequently fixed in
position upon the sections or ring.
Another essential part of our invention consists in so attaching the armature.
sections (when these are used) to the framing of the machine that they are each
independently adjustable to or from the pole faces of the field magnets so
that the air cap between the two can be regulated with great accuracy, and
thus any inaccuracy in the construction or mounting of the machine be
compensated for.
Another essential feature of our invention relates to the mode of fixing laminated
pole pieces upon the poles of the field magnets, such as are sometimes used to
prevent losses due to eddy currents due to the surging of the magnetic field in the
pole tips.
We build up such pole pieces of iron laminæ presenting slightly tapering or
wedge shaped sides, the surface thereof which is to come in contact with the end
surface of the field magnet pole being tooled so as to insure an accurate fit, we
then fit over the sides of the pole piece a ring or frame the internal sides of which
are tapered to correspond with the taper of the pole piece and we secure the pole
piece firmly against the field magnet by means of screw bolts passing through
eyes on the ring or frame, and screwing into lugs formed on the sides of the field
nagnet.

page_text: On the accompanying drawings are shewn by way of example various modes of
carrying out our above described improvements.
Figures 1 to 5 shew constructions in which the annular armature of a dynamo is
built up of a number of sections A A' A' &c. formed of iron lamine secured
together by insulated bolts B, and having recesses formed between the sections
for the reception of the conductor coils. In Figure 1 the alternate sections A are
formed with parallel sides, having projecting shoulders a a at their inner ends,
while the other alternate sections have tapering or wedge shaped sides adapted
to fit cluse against the sides of A the inner ends being reduced in width, so as to
fit hetween the shoulders a of A, thus forming recessed shoulders at a'. By this
means spaces are formed between the two sections for containing the conductor
coils C C; these coils are built up separately upon a former, and are then placed,
either with or without the former, upon their respective sections, the coils C being
slid over the outer ends of the sections A until they rest upon the shoulders a
while the coils Care slid over the inner ends of A until they bear against the
shoulders a', Thus assuming that the sections A have been fixed in their places
on the framing D, with their coils C in position, then on fitting the coils on to
the sections A these can be slid in between the sections A and he secured in position,
the coils C being held securely in their place by the overlapping shoulders a of the
sections A. It will be seen that any section can at any time be withdrawn together
with its coil without interfering with the others.
At Figure 2 all the sections are made with tapering or radial sides; in this case
only the sections A' have coils fitted on their reduced inner ends, the sections A
having grooves into which the coil C partly project being held securely in position
by the overlapping inner shoulders a which meet the sides of the reduced part
of A. Here the sections A' are first fixed in position and the sections A' are
then slid with their coils between them. At Figure 3 the sections A have parallel
sides with reduced inner ends on which the formed coils C are slid, while the
sectious A have tapering sides with projecting shoulders a' which cover in and
support the coils on A. At Figure 4 the formed coils Caro fitted on the
sections A having parallel sides throughout the coils being held in position
by the grooves in the sections A' into which they project. At Figure 5 the
sections A are all identical in configuration, the inner ends being formed with a
projecting shoulder a on one side while on the other side they have such a shape,
that on placing one side of the formed coil C in position over the shoulder a,
its other side can be brought into position over the other side of the section.
It will be seen that on fitting the sections with their coils in position the
shoulder a of the one section will project over and hold the coil of the contiguous
section.
Figures 6 and 7 shew the invention applied to an armature formed of iron
laminæ built up so as to constitute a continuous ring.
At Figure 6 recesses are formed at e on the inner surface of the ring E and into
these recesses are fitted pieces F with shoulders f, on to which the formed coils C
have been previously fitted. In this case there is only one coil for every alternate
pole of the field magnet while at Figure 7 the parts E¹ of the ring between the
recesses also have previously formed coils fitted upon them, these being held in
their place by overlapping shoulders f of the pieces F carrying the other coils. In
this case the number of coils is equal to that of the poles of the field magnets.
The pieces F are fixed in position by means of bolts G, passing through them
and through the metal cheeks at the ends of the armature, which are secured to
the framing.
It is preferred to fit the coils on to the armature together with the formers H,
which are by preference constructed as will be presently described.
Figures 8 and 9 show a part front elevation and a cross section of a dynamo
the fixed armature of which is constructed of separate sections as above described,
these sections being adjustably secured to the framing according to a further part
of our invention.

page_text: For this purpose, the side cheeks Q of the sections are formed with lugs Qu
through which pass screw bolts P that screw into the framing or shell M, so that
by adjusting these screw bolts the air gap between each segment and the poles of
the field magnets can be accurately regulated so as to correct for any inaccuracies
in the construction of the machine as it is of importance for the efficient working
of the machine that the magnetic flux should be as equal as possible at every
position of the poles. The said adjustment also allows for wear of the bearings.
When adjusted in position the bolts P are fixed by lock nuts R.
Figures 8, 9 and 10 also shew the construction of the formers which are fitted
with the coils C upon the armature sections as above described. For this purpose
the former H is made of insulating material of a trough shaped section and of the
configuration shewn in the sectional plan at Figure 10. When fitted with the coil
in position on the armature section the outer ends are preferably closed in
by cover plates V suitably secured by screws; on these cover plates are formed
nozzles Vi through which pass the ends of the coils for connection to the coils of
the contiguous armature sections, the parts of the conductors passing across from
one coil to the other being covered by a protecting sheathing K.
Figures 8 and 9 also show our before described improved method of securing
the laminated pole pieces on the poles of the field magnets. L are the pole pieces
built up of iron lamine and secured together to form a solid block by a bolt
passing through them, the inner surfaces of these blocks are suitably curved to fit
closely upon the peripheral face of the field poles. The sides of the block are cut
with a slight taper being surrounded at the sides with a thin sheet of suitable
insulation N. The whole is then laid in position upon the polar face of the
maguet over which we slip a rectangular metal frame O the plan of which is shewn
on Figure 11, the inside surfaces of which have a corresponding taper to the lami-
nated block. At the ends of this frame are provided deep bosses through which
holding down bolts W pass, the whole is then firmly clamped down by these end
bolts into projecting bosses X and recesses on the field poles and are locked by
the two back nuts S. The metal frame is sometimes split so as to eliminate any
induced currents due to variations of the total field as shown at T, Figure 8.
Figures 8, 9 and 11 shew a metallic key plate U in the centre of the lamination
to which are given projecting lugs U fitting over the polar face. The object
being to get a positive driving power in the position where the magnetic drag is
greatest, we may use two or more of these key plates depending upon the width of
pole. This is a sound and satisfactory mechanical method of fixing the polar
faminations, there also being the distinct advantage over other methods of being
able to quickly detach and remedy any fault in the laminated system on the
magnets.
Dated this 8th day of February 1896.
13 IMDA V
ABEL & IMRAY,
Agents for the Applicants.
COMPLETE SPECIFICATION.
Improvements in Alternate Current Dynamos.
We, WALTER CLAUDE JOHNSON, of The Dignaries, Westcombe Park,
Blackheath, in the County of Kent, LOUIS JOHN STEELE, of 14 Clarendon Road,
Holland Park, in the County of London, and JOHN WILLIAM EWART, of
21 Inverine Road, Old Charlton, in the County of Kent, Electrical Engineers,
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:-
Our invention relates to improvements in alternate current dynamos whereby

page_text: special advantages in the construction of such machines are obtained as will be
hereinafter described.
The invention relates more particularly to that construction of such dynamos
in which the armature is of annular form surrounding the field magnets which
revolve.
We build up the armature of thin iron laminations insulated froin one another,
and forming preferably as closed a magnetic circuit as possible, in which armature
the conductors are buried. According to one mode of construction we build up
such armature of a number of sections, of which there may be as many or half as
many as there are poles on the field magnets, the radial or side faces of these
sections butting close together, being if necessary tooled to produce as close a fit
as possible. The inner surface of the armature consequently presents a practically
continuous annular face to the field magnets.
According to another mode of construction we form the iron laminations so as
to be built up into a continuous ring instead of in sections. In either construction
these sections or the continuous ring have or has recesses which in the case of the
sections are formed along their meeting sides for the reception of the conductor
coils so that these shall be completely imbedded therein and one essential feature
of our invention consists in so constituting the said recesses that the coils can be
built up on a former independently of the core sections and the sections or complete
ring can be built up independently of the coils, which are subsequently fixed in
position upon the sections or ring.
Another essential part of our invention consists in so attaching the armature
sections (when these are used) to the framing of the machine that they are each
independently adjustable to or from the pole faces of the field magnets so that the
air gap between the two can be regulated with great accuracy, and thus any
inaccuracy in the construction or mounting of the machine be compensated for.
Another essential feature of our invention relates to the mode of fixing laminated
pole pieces upon the poles of the field magnets, such as are sometimes used to
prevent lossca due to eddy currents due to the surging of the magnetic field in the
pole tips.
We build up such pole pieces of iron laminæ presenting slightly tapering or
wedge shaped sides, the surface thereof which is to come in contact with the end
surface of the field magnet pole being tooled so as to insure an accurate fit, we
then fit over the sides of the pole piece a ring or frame the internal sides of which
are tapered to correspond with the taper of the pole piece and we secure the pole
piece firmly against the field magnet by means of screw bolts passing through eyes
on the ring or frame, and screwing into lugs formed on the sides of the field
magnet.
On the drawings accompanying our Provisional Specification are shewn by way
of example various modes of carrying out our above described improvements..
Figures 1 to 5 shew constructions in which the annular armature of a dynamo
is built up of a number of sections A A' A² &c. formed of iron lamina secured
together by insulated bolts B and having recesses formed between the sections for
the reception of the conductor coils.
In Figure 1 the alternate séétions A are formed with parallel sides, having
projecting shoulders a a at their inner ends, while the other alternate sections have
tapering or wedge shaped sides adapted to fit close against the sides of A the
inner ends being reduced in width, so as to fit between the shoulders a of A thus
forming recessed shoulders at a'. By this means spaces are formed between the
two sections for containing the conductor coils CC; these coils are built up
separately upon a former, and are then placed, either with or without the former,
upon their respective sectious, the coils C, being slid over the outer ends of the
sections A until they rest upon the shoulders a, while the coils C are slid over
the inner ends of A¹ until they bear against the shoulders a'. Thus assuming that
the sections A have been fixed in their places on the framing D, with their coils C
in position, then on fitting the coils on to the sections A these can be slid in

page_text: between the sections A and be' secured in position, the coils C' being held securely
in their place by the overlapping shoulders a of the sections A. It will be seen
that any section can at any time be withdrawn together with its coil without
interfering with the others.
At Figure 2 all the sections are made with tapering or radial sides; in this case
only the sections A' have coils fitted on their reduced inner ends, the sections A
having grooves into which the coil C partly projects being held securely in position
by the overlapping inner shoulders a which meet the sides of the reduced part
of A. Here the sections A are first fixed in position and the sections A' are then
slid with their coils between them. At Figure 3 the soctions A have parallel
sides with reduced inner ends on which the formed coils C are slid while the
sections A have tapering sides with projecting shoulders a which cover in and
support the coils on A. At Figure 4 the formed coils C are fitted on the
sections A having parallel sides throughout, the coils being held in position by
the grooves in the sections A' into which they project. At Figure 5 the sections A
are all identical in configuration, the inner ends being formed with a projecting
shoulder as on one side while on the other side they have such a shape; that on
placing one side of the formed coil C in position over the shoulder a, its other
side can be brought into position over the other side of the section. It will be
seen that on fitting the sections with their coils in position the shoulder as of the
one section will project over and hold the coil of the contiguous section.
Figures 6 and 7 shew the invention applied to an armature formed of iron
lamine built up so as to constitute a continuous ring.
At Figure 6 recesses are formed at e on the inner surface of the ring E and into
these recesses are fitted pieces F with shoulders f, on to which the formed coils C
have been previously fitted. In this case there is only one coil for every alternate
pole of the field magnet while at Figure 7 the parts E of the ring between the
recesses also have previously formed coils fitted upon them, these being held in
their place by overlapping shoulders of the pieces F carrying the other coils.
In this case the number of coils is equal to that of the poles of the field magnets.
The pieces F are fixed in position by means of bolts G, passing through them and
through the metal cheeks at the ends of the armature, which are secured to the
framing.
It is preferred to fit the coils on to the armature together with the formers H,
which are by preference constructed as will be presently described.
Figures 8 and 9 shew a part front elevation and a cross section of a dynamo the
fixed armature of which is constructed of separate sections as above described,
these sections being adjustably secured to the framing according to a further part
of our invention.
For this purpose, the aide cheeks Q of the sections are formed with lugs Q'
through which pass screw bolts P that screw into the framing or shell M, so that
by adjusting these screw bolts the air gap between each segment and the poles of
the field magnets can be accurately regulated so as to correct for any inaccuracies
in the construction of the machine as it is of importance for the efficient working
of the machine that the magnetic flux should be as equal as possible at every
position of the poles the said adjustment also allows for wear of the bearings.
When adjusted in position the bolts P are fixed by the lock nuts R.
Figures 8, 9 and 10 also shew the construction of the formers which are fitted
with the coils C upon the armature sections as above described. For this purpose
the former H is made of insulating material of a trough shaped section and of the
configuration shewn in the sectional plan at Figure 10. When fitted with the coil
in position on the armature section the outer ends are preferably closed in by cover
plates V suitably secured by screws; on these cover plates are formed nozzles Vi
through which pass the ends of the coils for connection to the coils of the
contiguous armature sections, the parts of the conductors passing across from one
coil to the other being covered by a protecting sheathing K.,
Figures 8 and 9 also show our before described improved method of securing

page_text: the laminated pole pieces on the poles of the field magnets. Lare the pole pieces
built up of iron lamina and secured together to form a solid block by a bolt
passing through them, the inner surfaces of these blocks are suitably curved to fit
closely upon the peripheral face of the field poles. The sides of the block are cut
with a slight taper being, surrounded at the sides with a thin sheet of suitable
insulation N. The whole is then laid in position upon the polar face of the magnet.
over which we slip a rectangular metal frame O the plan of which is shewn on
Figure 11, the inside surfaces of which have a corresponding taper to the laminated
block. At the ends of this frame are provided deep bosses through which holding
down bolts W pass the whole is then firmly clamped down by these end bolts into
projecting bosses X and recesses X¹ on the field poles and are locked by the two
back nuts S. The metal frame is sometimes split so as to eliminate any induced
currents due to variations of the total field as shown at T Figure 8.
Figures 8, 9 and 11 shew a metallic key plate U in the centre of the lamination
to which are given projecting lugs U fitting over the polar face. The object
being to get a positive driving power in the position where the magnetic drag is
greatest, we may use two or more of these key plates depending upon the width of
pole. This is a sound and satisfactory mechanical method of fixing the polar
faminations, there also being the distinct advantage over other methods of being
able to quickly detach and remedy any fault in the laminated system on the
magnets.
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. In alternate current dynamos with external ring-shaped armatures and
internal field magnets, constructing the armature of a number of separate sections,
the radial or side faces of which butt close together and have recesses so formed
and arranged that the conductor coils can be fitted therein after having been
previously built upon a former, while at the same time the metal of the segmenta
presents a practically continuous or unbroken surface to the field magnets,
substantially as described.
2. In dynamos such as are referred to in the first claim, forming the alternate
sections A of the armature with parallel sides having projecting shoulders a while
the other alternate sections have tapering sides and have their inner ends formed
parallel and of reduced width, so as to fit between the shoulders of the sections A.
and thus leave spaces above the shoulders which contain the conductor coils
substantially as described with reference to Figure 1 of the drawings.
3. In alternate current dynamos such as are referred to in the first claim,
constructing all the sections with tapering or radial sides, the sections A having
coils fitted on their reduced inner ends which coils are held in position by
projecting shoulders a on the sections A, substantially as described with reference
to Figure 2 of the drawings.
4. In alternate current dynamos such as are referred to in the first claim,
constructing the alternate sections A with parallel sides and reduced inner ends
for receiving the coils, while the other intermediate coils A are formed with
tapering sides and projecting shoulders a³ which serve to secure the coils on the
other sections substantially as described with reference to Figure 3 of the
drawings.
5. In alternate current dynamos such as are referred to in the first claim,
constructing the alternate sections A with parallel sides, on the inner ends of
which are fitted the conductor coils while the other alternate sections A' have
tapering sides with grooves into which fit the coils on the first named sections
substantially as described with reference to Figure 4 of the drawings.
6. In alternate current dynamos such as are referred to in the first claim,
constructing all the sections of the ring shaped armature of identically the same
form, with a recessed portion on one side for receiving the coil and a shoulder on

page_text: the other side which is made to project underneath the coil on the contiguous
section substantially as described with reference to Figure 5 of the drawings.
7. In alternate current dynamos with external ring shaped armatures and internal
field magnets, constructing the armature as a continuous ring built up of thin,
plates, the inner surface of which is formed with recesses into which are fitted
pieces F with shoulders carrying the conductor coils substantially as described
with reference to Figure 6 of the drawings.
8. In a continuous ring shaped armature such as is referred to in the seventh
claim, so formning the recesses that conductor coils can also be fitted on the-
intermediate projecting parts between the recesses, the shoulders f of the pieces F
being made to project under such coils for holding them in position, substantially
as described with reference to Figure 7 of the drawings.
9. In dynamos with outer ring shaped armatures built up of separate sections,.
securing each section adjustably to the dynamo frame by means of screws such
as P serving to connect the side cheeks of the sections to the dynamo frame, so-
that each section can be accurately adjusted relatively to the field magnets
substantially as described with reference to Figures 8 and 9 of the drawings.
10. Constructing the formers for the armature coils of dynamos, such as are-
referred to in the preceding claims, of a trough shape closed at the outer ends by
covers V carrying nozzles V' through which pass the ends of the conductors for-
connecting the coils of the contiguous armature sections, substantially as described
with reference to Figures 8, 9, and 10 of the drawings.
11. Securing laminated pole pieces such as L on the poles of field maguets by
means of a rectangular frame such as O, fitting with a tapering surface over the-
tapering sides of the pole piece, with the interposition of insulating material, such
frame being provided with bosses or eyes through which pass screw-bolts securing-
the frame and pole pieces to the field magnets substantially as described with
reference to Figures 8, 9 and 11 of the drawings.
12. In combination with the arrangement for securing pole pieces referred to in.
the preceding claim, the use of one or more metal key plates U passing through.
the pole piece and having lugs U₁¹ extending over the pole face, so as to afford.
intermediate supports to the pole piece and frame O, substantially as described.
with reference to Figures 8, 9 and 11 of the drawings.
Dated this 9th day of November 1896.
ABEL & IMRAY,
Agents for the Applicants..