Improvements in Magneto-electric Machines.
Year: 1889

page_text: Date of Application, 22nd Mar., 1889
Complete Specification Left, 23rd Dec., 1889-Accepted, 25th Jan., 1890
PROVISIONAL SPECIFICATION.
Improvements in Magneto-electric Machines.
I, GEORGE BOWRON Electrican, of 97 Crawford Street London W. do hereby declare
the nature of this invention to be as follows :—
The principal parts of a magneto-electric machine are the permanent magnet, the
armature, and the commutator, or collector, with its brushes. My improvements
relate principally to the form of the permanent magnet, and also to the commutator,
or collector, and brushes.
In place of the usual horse-shoe permanent magnet I use a straight one, and conduct
the magnetism through the armature by means of two suitably shaped pole pieces
attached to the ends of this magnet.
The armature I use is the well known Siemens shuttle armature. It is wound with
a coil of insulated wire, and is mounted in the usual manner.
The shuttle armature, as is well known, delivers a current of electricity continually
varying in strength. This current attains a maximum value twice during each revolution
of the armature. I modify the commutator, or collector, and brushes in such a manner
that, when desired, the armature may be short circuited either just before, or just
after, the time when the armature is giving the maximum current. To accomplish
this I attach two projecting arms to the commutator, or colloctor, and I also add
another brush, which, periodically making contact with the projecting arins aforesaid,
short circuits the armature.
.
In order that this contact may short circuit the armature the additional brush must
necessarily be connected to one of the ordinary brushes. If however the armature, as
is often the case, has one end of the coil of wire connected to the metalwork of the
armature the additional brush must be connected to the framework of the machine.
I prefer to make the armature spindle of a piece of clockmakers pinion wire. The
armature can then be rotated by a toothed wheel the teeth of which engage in the
leaves of the pinion.
Dated the Twants cocond day of March 1980
COMPLETE SPECIFICATION.
Improvements in Magneto-electric Machines.
1, GEORGE BOWRON, of 97 Crawford Street, London, W., Electrician, 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, reference
being also had to the accompanying drawing wherein :-
Figure 1 is an elevation and Figure 2 a section on line A, B, Figure 1, of a
machine constructed in accordance with my said Invention, Figures 3 to 10 inclusive
illustrating details of same hereinafter more particularly referred to; like letters of
reference throughout the several views denote corresponding parts or members in each.
The principal parts of a magneto-electric machine are the permanent magnet, the
armature, and the commutator or collector with its brushes. My improvements relate
principally to the form of the permanent magnet, and also to the commutator or
collector and brushes.
In place of the usual horse shoe magnet I use a straight one, and conduct the
magnetism through the armature by means of two suitably shaped pole pieces attached
to the ends of this magnet.
The armature 1 use is the well known Siemens shuttle
armature. It is wound with a coil of insulated wire, and is mounted in the usual

page_text: шаппег. A commutator is used for un directional currents and a collector Tor
alternating currents.
The current in the armature, as is well known, attains a maximum value twice
during each revolution. I modify the collector and brushes in such. a manner that
when desired the armature may be short circuited just before the time when it reaches
the position shown in Figure 2, which, for low speeds of the armature is the position
when the maximum current is given. To accomplish this,, Lattach two projecting arms
to the cominutator or collector and I also add another brush, which, periodically making
contact with these projecting arms, short circuits the armature. In order that this contact.
may short circuit the armature the additional brush must necessarily he connected to
one of the ordinary brushes. If however; as is often the case, one end of the coil of
insulated wire is connected to the metal work of the armature, the additional brush ·
must be connected to the framework of the machine.
In Figures 1 and 2, which represent a machine adapted for giving alternating
currents; A is the permanent magnet; B, B, the pole pieces, the armature mounted
on the spindle, the latter being preferably formed of clockmakers pinion wire and
the ends turned down and carried in bearings formed for the purpose in the
crosspieces D. D. To allow of the rotation of the armature employ a toothed
wheel E, the teeth of which engage with the leaves of the armature spindle or pinion e;
said wheel being mounted on a spindle d carried within the socket or bearing e formed
by a projection cast on the pole piece B', or attached separately if so desired. When"
preferred, instead of employing a toothed wheel E I may form a groove in the
peripheral rim of the wheel, such groove being fitted with a suitable elastic material
such as-india rubber or the like so that the friction of such material against the leaves*
of the pinion or spindle is sufficient to secure rotation of the armature: The
collector F here shown,, which is mounted on the armature spindle c, consists of 'a
metallic disc having projecting arms or lugs a, a, said disc collector being suitably
insulated from the armature and spindle; the spaces between the projecting armsa, a¹,
being also provided with insulating material to present an even bearing surface.
The brushes bb, are secured to a block of insulating material by the terminal
screws g,g, said insulating block being attached to the framework of the machine.
The free ends of the brushes b; 6', bear respectively on the collector F and the projecting
arms a, a!.
Referring to Figures 3 to 10, these represent detached views of the commutators' or
collectors constructed in a slightly modified, formato that shown in Figuren 2, the
dotted line in each of the views showing the position of the commutators and collectors
relatively to the armatures.
Figure 3 is a disc commutator for giving currents in one direction, a, a¹, being the
projecting arms or lugs.
Figure 4 is a disc collector, for giving, alternating, currents, the width of the
projecting arms in this case being considerably increased. This is desirable for both
commutators and collectors when the armature is run at a high speed in order that
the current may attain its maximum value during the short circuit.
Figure 5 represents a cylindrical.commutator and Figure 6 a cylindrical collector
which I may sometimes employ although I prefer to use the disc forms as they are
more compact: The arrangements of the brushes for the cylindrical commutators-and
collectors are similar to those for the disc forms.
Figure 7 is a dise collector having projecting arms or lugs somewhat enlarged:
Figure 8 is a disc commutator having three brushes 6; 6 The ends of the
armature-coil are; in this case; connected to the two halves of the commutator: The
additional short circuiting brush is connected to the brush b: These two brushes
are connected to one terininal of the machine while the brush is connected to the
other terminal.
Here one end of 'the
Figure represents a collector having two brushes ;.
armature coil is connected to the metal work of the armature and the other end to the
collector. The brush is connected 'to one terminal of the machine while the brush 6 is
connected to the framework of the machine and also to the other terminal.

page_text: I sometimes use only one half of a commutator. This is shown in Figure 10. The
brush b is connected to one terminal of the machine, while the brush b' is connected to
the framework of the machine and also to the other terminal. The brushes touch the
commutators and collectors at or near their extremities only.
In each of these forms the short circuiting brush may be rendered inactive by
pushing it off the commutator or collector or by disconnecting the wire joining it to
the other parts of the machine.
Having now particularly described and ascertained the nature of my said Inven-
tion and in what manner the same is to be performed, I declare that what 1
claim is :-
The improvements in magneto electric machines substantially as herein described
and shown Figures 1 to 10 inclusive of the accompanying drawing.
Dated this 21st day of December 1889.
JAMES STEVENSON,
20, High Holborn, London, W.C., Agent for Applicant.
JAMES
STEVENSON,
20, High Holborn, London, W.C., Agent for Applicant.