IMPROVEMENTS IN MAGNETO ELECTRIC MACHINES PARTS OF WHICH ARE ALSO APPLICABLE TO DYNAMO ELECTRIC MACHINES AND ELECTRO MOTORS
Year: 1883

page_text: LETTERS PATENT to George Hookham of Birmingham in the County of
་
Warwick Manufacturer for an Invention of IMPROVEMENTS IN MAGNETO
ELECTRIC MACHINES PARTS OF WHICH ARE ALSO APPLICABLE TO DYNAMO
ELECTRIC MACHINES AND ELECTRO MOTORS.
PROVISIONAL SPECIFICATION left by the said George Hookham at the
Office of the Commissioners of Patents on the 21st April 1883.
GEORGE HOOKHAM of Birmingham in the County of Warwick Manufacturer
"IMPROVEMENTS IN MAGNETO ELECTRIC MACHINES PARTS OF WHICH ARE ALSO
APPLICABLE TO DYNAMO ELECTRIC MACHINES AND ELECTRO MOTORS 〃
My invention has reference principally to magneto electric machines in which
the permanent inducing magnets rotate while the armatures in the coils on which
electric currents are inducted are stationary. The improvements constituting my
invention may be in part applied to other kinds of magneto electric machines to
dynamo electric machines and to electro motors.
In constructing a magneto electric machine according to my invention I employ
permanent steel magnets having the figure of the letter V. I mount or connect
together a number of these magnets face to face after the well known method of
building up compound magnets. Each series of magnets thus mounted or
connected has the figure of a V shaped trough.
These compound magnets I fix on a shaft mounted so as to be capable of
rotation the magnets being connected to the shaft at their angles and arranged
round the shaft radially the north and south poles alternating and being
equidistant
The V shaped magnets may be fixed to the rotating shaft by clips passing over
the angular parts of the said magnets but for greater security and the prevention
of accident by the fracture of the magnets or otherwise I prefer in addition to fix
a guard over or on each end of the magnet. When I employ a guard extending
over the whole face of the end of the magnet I make the said guard of soft iron
but when the said guard covers only part of the end of the magnet engaging in a
sunken part or recess therein it may be made of brass or other non magnetic
metal.
Instead of making the magnets of a V shape straight or bar magnets may be
employed the said bar magnets being arranged radially on the shaft and having
beir poles equidistant and alternating.

page_text: .
The armatures I employ have. the figure of troughs the sides or edges of which
are at about the same distance apart as the ends of the V shaped magnets. I
employ a number of armatures equal to the number of V shaped magnets instead
of double the number as ordinarily. employed and I fix the said armatures around
the system of magnets carried by the shaft so that the ends of the magnets on the
rotation of the shaft may pass as closely as practicable to the ends of the
armatures. The armatures being stationary no commutator or collector is required
and when the machine is employed for working incandescent or arc electric lamps
a separate armature may be employed for each lamp or separate coils on the same
armature may be employed for each lamp thus permitting any number of the
series of lamps operated by the machine being thrown out of action without
materially affecting the remainder of the lamps.
In order to prevent or diminish the production of so called Foucault currents in
the armature I make in it a series of cuts or divisions parallel to the lines of
magnetic force or when I make the armatures of malleable cast iron I cast them
Or
with ridges for the same purpose. Or I build them up of plates of soft iron.
I build up the armature of a series of trough shaped plates of sheet iron fitting one
within the other and bolted or screwed together. The armature thus built up has
the slits or cuts hereinbefore referred to.
I prefer to make the middle part of the armature on which the wire is coiled
shorter than the outer portions that is the ends of the trough shaped armature
are not parallel but are inclined to one another from the mouth of the trough to
the bottom. Resistance is thereby diminished.
Instead of employing a number of arinatures equal to the number of V shaped
magnets double the number may be employed. In this case the armatures have a
figure somewhat resembling that of an ordinary horse shoe magnet and are so
fixed around the rotating system of permanent steel magnets that the arms of the
horse shoe armatures are parallel to the rotating shaft and consequently the said
arms are presented lengthwise and not endwise to the passing magnets. The arms
only of the horse shoe armatures are presented to the rotating system of magnets
the bent part of the horseshoe armatures on which the wire is coiled projecting
beyond the ends of the rotating system. In this form of my invention I arrange
the horse shoe armatures by preference so that their bent parts alternately
overhang the rotating magnets on opposite sides the legs of one armature being
respectively situated between the legs of the adjacent armatures. When the legs
of one armature are over two magnetic poles the legs of the next armature are
midway between a pair of magnetic poles. Thus the armatures are alternately
acted upon by the magnets. By 'thus doubling the number of armatures an
approximately double effect is produced. Instead of making the armature of a
bar or of plates of iron of horse shoe shape it may be made of two parallel bars
having a cross piece fixed between them at one end. In this case I prefer to
make the cross piece of a strip of sheet iron rolled up into a compact coil having in
its axis the bolt which secures it to the parallel bars. The strip of iron has cross
slits or incisions for the prevention of Foucault currents.
Although the V shaped magnets I employ may be made of plater or bars of the
same breadth throughout yet I prefer to make the said plates or bars broader at
their ends than at their middle parts. By giving additional breadth to the ends
of the magnets the strength of the magnetic field is increased and the armatures
are longer exposed to its action
Part of my improvements especially those relating to the construction of
armatures are applicable to magneto electric machines of different construction
from that herein described as well as to dynamo electric machines and electro
motors

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed
by the said George Hookham in the Great Seal Patent Office on the
17th October 1883.
"
GEORGE HOOKHAM of Birmingham in the County of Warwick, Manufacturer.
IMPROVEMENTS IN MAGNETO ELECTRIC MACHINES, PARTS OF WHICH ARE ALSO
APPLICABLE TO DYNAMO ELECTRIC MACHINES AND ELECTRO MOTORS"
My invention has reference principally to magneto-electric machines in which
the permanent inducing magnets rotate while the armatures in the coils in which
electric currents are inducted are stationary. The improvements constituting my
invention may be in part applied to other kinds of magneto-electric machines, to
dynamo electric machines and to electro motors.
In constructing a magneto electric machine according to my invention I employ
permanent steel magnets having the figure of the letter V. I mount or connect
together a number of these magnets face to face after the well known method of
building up compound magnets. Each series of magnets thus mounted or connected
has the figure of a V shaped trough. These compound magnets I fix on a shaft
mounted so as to be capable of rotation the magnets being connected to the shaft
at their angles and arranged round the shaft radially the north and south poles
alternating and being equidistant. The V shaped magnets may be fixed to the
rotating shaft by clips passing over the angular parts of the said magnets but for
greater security and the prevention of accident by the fracture of the magnets or
otherwise I prefer in addition to fix a guard over or on each end of the magnet.
When I employ a guard extending over the whole face of the end of the magnet I
make the said guard of soft iron but when the said guard covers only part of the
end of the magnet engaging in a sunken part or recess therein it may be made of
brass or other non magnetic metal.
Instead of making the magnets of a V shape, straight or bar magnets may be
employed, the said bar magnets being arranged radially on the shaft and having
their poles equi distant and alternating.
The armatures I employ have the figure of troughs the sides or edges of which
are at about the same distance apart as the ends of the V shaped magnets. I
employ a number of armatures equal to the number of the compound V shaped
magnets instead of double the number as ordinarily employed and I fix the said
armatures around the system of magnets carried by the shaft so that the ends of
the magnets on the rotation of the shaft may pass as closely as practicable to the
ends of the armatures. The armatures being stationary no commutator or
collector is required and when the machine is employed for working incandescent
or arc electric lamps a separate armature may be employed for each lanp, thus
permitting any number of the series of lamps operated by the machine being
thrown out of action without materially affecting the remainder of the lamps..
In order to prevent or diminish the production of so called Foucault currents in
the armature I make in it a series of cuts or divisions parallel to the lines of
magnetic force, or when I make the armatures of malleable cast iron I cast them
with ridges for the same purpose. Or I build them up of plates of soft iron. Or
I build up the armature of a series of trough shaped plates of sheet iron fitting
one within the other and bolted or screwed together. The armature thus built up
has the slits or cuts herein before referred to
I prefer to make the middle part of the armature on which the wire is coiled
shorter than the outer portions, that is, the ends of the trough shaped armature are
not parallel but are inclined to one another from the mouth of the trough to the
bottom. Resistance is thereby diminished.

page_text: one end.
Instead, of making the armature of a bar or of plates of iron of horse shoe shape
it may be made of two parallel bars having a cross piece fixed between them at
In this case the cross piece may be made of a strip of sheet iron
rolled up into a compact coil having in its axis the bolt which secures it to the
parallel bars. The strip of iron has cross slits or incisions for the prevention of
Foucault currents.
Although the V shaped maguets I employ may be made of plates or bars of the
same breadth throughout yet I prefer to make the said plates or bars broader at
their ends than at their middle parts. By giving additional breadth to the ends
of the magnets the strength of the magnetic field is increased and the armatures
are longer exposed to its action.
Part of my improvements especially those relating to the construction of
armatures are applicable to magneto-electric machines of different construction
from that hereindescribed as well as to dynamo-electric machines and electro
motors.
I will now proceed to describe with reference to the accompanying Drawings the
manner in which my invention is to be performed.
Figure 1 represents in elevation and edge view a V shaped magnet made
according to my invention. The ends or poles a, b are flattened out or made of
greater width than the other portions of the magnet. This flattening out of the
poles a, b while giving them breadth diminishes their thickness and when a number
of the magnets Figure 1 are packed and bound together so as to form a compound
magnet their poles a, b are not in contact. By giving additional breadth to the
ends or poles a, b of the magnets, the strength of the magnetic field is increased
and the armatures are longer exposed to its action. The diminished thickness of
the poles a, b promotes the retention of the magnetism in the said magnets.
These compound magnets are fixed on a shaft mounted so as to be capable of
rotation.
The arrangement of the permanent compound magnets the shaft on which they
are mounted and the armatures on which the said magnets during their rotation
induce magnetism and through the said magnetism electric currents in the coils
carried by the said armatures, will be understood generally by referring to the
diagrams Figures 2. 3 and 4; Figure 2 illustrating an end elevation of the shaft
magnets and armatures; Figure 3 illustrating the magnets and armatures in
perspective and Figure 4 illustrating the arrangement of magnets and shaft when
bar magnets are employed instead of V shaped magnets. The letters N and S
indicate respectively in Figures 2 and 4 the alternating north and south poles of
the magnets, whether consisting of V shaped magnets or of straight magnets.
The particular arrangement or combination of magnets, rotating shaft and
armatures is more particularly represented in Figures 5. 6. 7. 8. and 9 of the
Drawings, Figure 5 being a plan of a magneto electric machine constructed
according to my invention; Figure 6 is an end elevation of the same and Figure 7
is a side elevation of the same; Figure 8 represents a vertical section of the
machine and Figure 9 a horizontal section of the machine.
The same letters indicate the same parts in Figures 5. 6. 7. 8 and 9
The manner in which the V magnets are fixed to the rotating shaft of the
magneto electric machine is best seen in the vertical and horizontal sections
Figures 8 and 9, where the magnets are marked a b and the rotating shaft
carrying the said magnets is marked c; d, d are packing pieces of wood inserted
between the adjacent magnets and between the arms of each magnet. The said
packing pieces are secured in their places and to each other by side plates carried
by the shaft c to which side plates the packing pieces are screwed; e, e are the
clips or bars situated in the angles of the magnets. The said clips or bars e, e are
bound together at their ends by the metallic rings f. In order the more
effectually to secure the magnets in their places and for the prevention of accidents
by the fracture of the magnets or otherwise I employ metallic guards either
extending over the whole face of each pole of the compound magnet or extending

page_text: over a portion only of each pole of the compound magnet. These guards are
illustrated in Figure 10, where a, b is the V shaped magnet, a² a guard extending
over the pole of the compound magnet the said guard a being fixed down to the
wooden blocks between the magnets by means of screws a³. Or the guard may
extend over part only of the face of the pole of the compound magnet as
represented at 6* Figure 10 where the guard bi seats itself in a recess in the pole
of the magnet, the said guard being fixed down by screws 6³. Where the guard
extends over the whole face of the pole as at a², I make it of soft iron and where
the guard extends over only part of the pole as at 62 I make the said guard of
brass or other non magnetic metal. Or the magnets may be fixed down by means
of guards or clips of the kind represented in Figure 8, and marked a³. The said
guards or clips a³ may be secured in their places by rings enclosing their ends
similar to the way in which the bars e are secured by the rings f³. Or the said
guards or clips a³ may be fixed by their ends being screwed to circular side
plates.
The armatures I employ have the figure of an inverted trough and may be built
up either of arch shaped pieces packed and secured together side by side in the
manner represented in Figure 3 or of trough shaped sheets of iron inserted within
one another and secured together by rivetting or otherwise as represented in
Figure 3. Or the armatures may be built up of plates of sheet iron each armature
being made in three parts as illustrated in the machine Figures 5. 6. 7. 8 and 9.
Each of the armatures in the said machine consists of two side pieces ff connected
at their middle by a cross piece g. The side pieces f,f and cross piece gare
secured together by the straps or plates h h screwed to the said side pieces ff and
cross piece g.
Instead of making the cross pieces g of separate plates of sheet iron they may
be made of coils of sheet iron, that is, of sheet iron rolled or coiled into a
cylindrical form.
In all cases where I make armatures of sheet iron I insulate the different pieces
or coils from one another by means of tissue paper or varnish
In order to prevent the formation of Foucault currents in the armature I make
a series of oblique slits or cuts in the side pieces f, f as represented in Figures 5
and 7.
The wire p in which the electric current is induced is coiled upon the cross
piece g of the armature as represented. It will be seen that while the sides ff
of the armature are of a length sufficient to extend over the whole of the poles of
the compound V shaped magnets the cross piece or middle part g of the armature
is much shorter than the side pieces or outer portions ff
Where for any reason it is desired to make the armature of a series of arch
shaped plates packed and secured together side by side and to obtain the advantage
of the diminished length of the middle portion, I build it up in the manner illus-
trated in Figure 3B in which the arch shaped plates inay either be made of equal.
thickness throughout and connected together so that the ends of the plates are
separated from each other while their arched parts are in contact; or the said arch
shaped plates may be cut from sheet iron thicker at the part from which the base
of the plate is cut than at the part from which the arch is cut. A series of such
plates when packed together side by side and in contact with each other throughout
their whole surface produce an armature of the kind represented in Figure 3B.
When the trough shaped armature is made up in the way illustrated in Figure 34.
the ends of the trough are cut off obliquely so as to leave the ends of the armature
of greater length than the middle part.
The armatures are connected to the circular discs i i constituting the ends of the
fixed framing of the machine by means of sockets k in which the ends of the
armatures are inserted the said sockets being fixed to the discs i by screw bolts l.
I employ by preference eight compound V shaped magnets and an equal number
of armatures instead of a number of armatures double that of the magnets as is
sometimes employed.

page_text: I have illustrated the arrangement I employ in the diagram Figure 2 where the
number of V shaped magnets is equal to the number of the armatures. I have
indicated by dotted lines in the said Figure 2 intermediate armatures as commonly
employed thus making the number of armatures double that of the magnets instead
of using an equal number of magnets and armatures as in the arrangement
employed by me.
The machine, as will be seen by the drawings is provided with fast and loose
pulleys but these and other details of mechanical construction I do not think it
necessary to describe as they differ in no essential respects from the parts used for
like purposes in other machines.
As the armatures are stationary no commutators or collectors are required and
the electric currents from the coils p on the several armatures may either be
directed separately to the lamps they are intended to operate or to such other
purposes as it may be wished to apply the currents to; or the said electrical
currents may be collected either in one current or coupled or arranged as may be
desired.
My method of making V shaped magnets, that is, broadening the poles and
diminishing the thickness of the said poles may be applied to magneto-electric
machines of various constructions and my improvements in constructing armatures
may be applied to all kinds of magneto and dynaino electric machines as well as to
electro motors.
Having now described the nature of my invention and the manner in which the
same is to be performed I wish it to be understood that I claim as my invention of
Improvements in magneto electric machines, parts of which are also applicable to
dynamo electric machines and electro motors
66
"
First. Making the permanent steel magnets of magneto electric machines of a
V shape, the poles of the said magnets being of greater breadth and of less
thickness than the other parts substantially as herein before described and illustrated
in the accompanying Drawings.
Secondly Constructing the armatures of magneto and dynamo electric machines
and of electro motors of plates of sheet iron employed in the several ways herein
before described and illustrated in the accompanying Drawings.
↓
Thirdly-Fixing the V shaped magnets of magneto electric machines by means
of clips or bars situated in the angles of the V shaped magnets; also securing the
said V-shaped magnets by means of guards covering or partly covering the ends of
the poles of the magnets for the purpose and substantially as herein before described
and illustrated in the accompanying Drawings; also the application of the said
method of fixing the magnets by guards to magneto electric machines having
straight bar magnets as herein before described.
Lastly Combining into a magneto electric machine, a series of fixed or stationary
armatures and V shaped permanent magnets or straight permanent bar magnets
radially fixed on a rotating shaft substantially as herein before described and
illustrated in the accompanying Drawings.
In witness whereof I the said George Hookham have hereunto set my hand
and seal this Fifteenth-day of October in the year of our Lord one thousand
eight hundred and eighty three.
Witness,
RICHARD SKERRETT
37 Temple Street
Birmingham
GEORGE HOOKHAM (L.S.)