IMPROVEMENTS IN ELECTRIC GENERATORS
Year: 1883

page_text: LETTERS PATENT to Robert David Bowman of Leytonstone in the County of
Essex, Joseph, Edward Lord Clark of Brixton in the County of Surrey and
William John Kemp Clark, also of Brixton aforesaid for an Invention of
IMPROVEMENTS IN ELECTRIC GENERATORS
PROVISIONAL SPECIFICATION left by the said Robert David Bowman,
Joseph Edward Lord Clark, & William John Kemp Clark at the Office of the
Commissioners of Patents on the 1st March 1883.
ROBERT DAVID BOWMAN of Leytonstone in the County of Essex, JOSEPII
EDWARD LORD CLARK, of Brixton in the County of Surrey, and WILLIAM
JOHN KEMP CLARK also of Brixton aforesaid IMPROVEMENTS IN ELECTRIC
GENERATORS."
"
This invention relates firstly to improvements in the construction of the
armatures of electric generators, the object being to increase their efficiency and
enable them to be easily and conveniently put together or taken to pieces as
required.
In the case of armatures having iron cores wound longitudinally with coils of
insulated copper wire and adapted to rotate within a magnetic field extending
between the curved poles or pole pieces of two field magnets, the outermost lines
of force have hitherto not been utilized to the fullest extent; and with the view
of preventing the loss of efficiency in the armatures due to this cause, we propose
to construct the armature in separate detachable sections of peculiar form, each
section consisting of a coil of wire wound on an iron core of - shape in
cross section, the central part of the said core projecting slightly through the side
walls thereof. Some 8 or 10 of these separate sections are disposed lengthwise
around a metal hub keyed on the main axle of the electric generator. The iron
cores on their inner siles are formed in such a way as to fit into, or engage with,
suitably formed sockets in the hub, and the several sections of the armature are
held tightly in place around and against the hub by broad metal straps secured by
ID 1

page_text: lock nuts. Any one of the sections can thus be easily removed or replaced by
unscrewing one or two nuts.
The side walls of these iron cores, of
shape in cross section serve to
collect and utilize the outermost lines of magnetic force passing between the
extremities of the field magnets, and not only strengthen the magnetism of the
central portion of the core but by means of the lines of force passing between
the outermost edges of the side walls of the core, increase the current induced
in the outermost layers of wire in the coil around the said core, and more
completely and uniformly saturate the said coil with electricity.
The several removable sections of the armature are preferably so arranged around
the hub or axle, that the iron cores are slightly separated from each other, and the
wires of the several coils are coupled up and connected with the commutator, in
any desired manner.
The invention relates secondly to the construction of the field magnets with the
view of increasing their efficiency, and ensuring the passage of the lines of force
in a direction in which they can be utilized, thereby strengthening the magnetic
field.
#
To this end we form the extremities of the poles or pole pieces of the field-
magnets with rounded external surfaces to avoid the formation of sharp angles and
edges, from which lines of force can escape, and we form the curved inner surfaces
of the polo pieces with ridges or notches preferably running in planes parallel to
the direction of rotation of the armature.
The curved inner surfaces of the pole pieces are therefore of toothed, or notched
shape in cross section, and magnetic lines of force will tend to flow and arrange
themselves between the several opposing ridges of the pole pieces, and by affording
a readier passage for the magnetic lines will assist in preventing any of the
magnetism escaping from the outer surfaces of the pole pieces, and being wasted.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed
by the said Robert David Bowman, Joseph Edward Lord Clark, and William
John Kemp Clark in the Great Seal Patent Office on the 1st September
1883.
ROBERT DAVID BOWMAN of Leytonstone in the County of Essex JOSEPH
EDWARD LORD CLARK of Brixton in the County of Surrey and WILLIAM
JOHN KEMP CLARK also of Brixton aforesaid "IMPROVEMENTS IN ELECTRIC
GENERATORS
This invention relates firstly to improvements in the construction of the
armatures of electric generators, the object being, to increase their efficiency, and
enable them to be easily and conveniently. put together, or taken to pieces, as
required.
In the case of armatures having iron cores wound longitudinally with coils of
insulated copper wire, and adapted to rotate within a magnetic field extending
between the curved poles, or pole pieces, of two field magnets, the outermost lines
of force have hitherto not been utilized to their fullest extent, and with the view
of preventing the loss of efficiency in the armatures, due to this cause, we propose
to construct the armature in separate detachable sections, of the form shown at
Figure 1-in elevational section, and at Figure 2 shown connected to the gun metal
armature hub a. The cast iron bobbins shown at Figure 1 are provided with
core b. and end cheeks c. which are advantageously covered with a suitable insulating
material d.
The central part of the said core b extends through the side cheeks c., Some
eight or ten of these sections are disposed lengthwise round a metal hub a keyed on
the axis e. The iron core cheeks; on their inner sides are formed in such a
manner as to fit into or engage with suitably formed sockets in the hub a.
fis the said projection and g is the socket in the hub and the several sections of
the armature are held firmly in place around and against the hub a by broad metal
straps secured by lock nuts: Any one of these can easily be removed or replaced
by unscrewing any one of the nuts. This part of our invention will be more
clearly understood on reference to Figure 3 which is a part side elevation of an
electric generator constructed according to one modification. In this Figure the
series of coils as at Figure 1 are shown secured to the hub by the set screws or
bolts h and the extensions b' of the cores are shown clamped by a plate or metal
strap i. This part of our invention relates to that class of armature of the
Gramme type, but in the application of the said improvements to armatures of
the disc type I propose to mount them in the manner as shown at Figure 4 which
is a part plan of the armature. Figure 5 is a side elevation of the armature and
Figure 6 is a transverse section thereof. In this example it is necessary that the
extensions of the cores 6 should be radial as shown at Figure 5 the plan of these
cheeks are shown in the detached view Figure 4 constructed so as to be clipped
together side by side by means of bolts or other equivalent device so long
as one of the bobbins can be easily removed when desired.
"
This invention relates secondly to the construction of the field magnets with the
view of increasing their efficiency and ensuring the passage of the lines of force in
a direction in which they can be utilized; or allowing them to pass parallel through
the armature coils, and at right angles to the currents induced therein.
кас
To effect this object, the extremities of the poles, or pole pieces of the field
magnets, are formed with round extended surfaces, to avoid the sharp angles and
edges, from which lines of force can escape, and we form the inner surfaces of the

page_text: "
pole pieces with ridges or channels preferably running in a direction parallel to
and in line with the direction of rotation of the armature.
This construction of pole piece is shown at Figure 2 j is the pole piece. k. k. are
the grooves of any convenient number therein.
The several removeable sections of the armature are preferably so arranged
around the hub or axle, that the iron cores are slightly separated from each other
and the wires of the several coils are coupled up and connected to the commutator
in any suitable manner. The aforesaid coils may be connected to solid discs and
secured by a transverse bolt or bolts or in any other convenient manner.
We find it advantageous to wind the coils with insulated wire as by its
employment greater power is obtained in less space than with the ordinary round
wire.
Several of these armatures may be arranged on one spindle the field magnets
can be wound either in a shunt from the main or in series with the armature and
lamps.
·
Having thus described the nature of our Invention and in what manner, the
same is advantageously carried into effect we would have it understood that we
claim
First. The formation of the coils of electric generators wound transversely to
the ring, and capable of being detached or replaced without affecting the other
coils substantially as described and illustrated with reference to the accompanying
Drawings.
:
Second., In armatures of the ring type, the making of them up in series in the
manner described and illustrated whereby they can be wound by any suitable
means. without the passing of one end of the wire through the ring at each
convolution as heretofore.
'
Third. In disc armatures the extension of the cores to form cheeks whereby the
lines of force will strike the cheeks and pass parallel through the coils of wire
wound between them as herein set forth and illustrated with reference to all the
Figures of the accompanying Drawings.
Fourth. The construction of boss as hereinbefore described whereby the cheeks
of the coils can be connected' thereto as set forth.
Fifth. The construction of the pole pieces of the field magnets with grooves or
channels on their concavity in the direction of the line of rotation so that the lines
of force shall extend over the whole surface of the armature coils as set forth.
In witness whereof we the said Robert Davey. Bowman Joseph Edward Lord
Clark and William John Kemp Clark have hereunto set our hands and seals this
Thirty first day of August in the year of our Lord One thousand eight hundred
and eighty three.
ROBERT DAVEY, BOWMAN
JOSEPH EDWARD LORD CLARK
WILLIAM J. K. CLARK
(L.S
(LS
(L.S
Witness to the respective Signatures
JAS FREDK PHILLIPS
of the firm of
Phillips & Leigh
Patent Agents
22 Southampton Buildings. W.C.