IMPROVE- MENTS IN THE CONSTRUCTION OF ELECTRO MOTORS
Year: 1885

page_text: I, DESIRE THOMAS PIOT of 34 Bolsover Street Euston Road in the County of
Middlesex, Electrician, do hereby declare the nature of my invention for IMPROVE-
MENTS IN THE CONSTRUCTION OF ELECTRO MOTORS to be as follows:-
The object of my invention is to increase the power of electro motors and this
object I effect by enlarging the polar surfaces of the field magnets and the armature
and by so connecting the bobbins of the armature and the field magnets with the
battery that the exciting current may act equally upon each with the best effect.
To obtain these results the armature is composed of pairs of bar of soft iron
insulated by some diamagnetic material and surrounded in the usual way by
helices of insulated copper wire. These bars are connected at their ends to discs of
soft iron which are mounted upon an axle turning in bearings carried by the
field magnets, and they are provided at the middle of their length with radial
projections.
To these projections are attached by screws pairs of soft iron plates which extend
from end to end of the armature, and partially or entirely enclose the bobbins.
The field magnets are provided with polar extensions which correspond with the
outer plates of the armature and the terminals of the armature bobbins are
connected to a commutator of the usual construction.
Supposing two elements of a battery are used to operate this machine I connect
one terminal of the field magnets with the positive pole of one element, and the
other terminal of the field magnets with the negative pole of the other element,
the other two poles of the two elements I connect with the two brushes of the
commutator and thereby cause the current to traverse the helices of the armature,
or the apparatus may be coupled up in any other well known or convenient
manner.

page_text: Fig. 3 a plan view.
In these figures, A. A is the field magnet, which forms at the same time the frame
of the machine.--This magnet is provided with polar extensions a a and a¹ a', and
it is coiled with insulated copper wire in the usual way, the ends of the wire being
brought out to the terminals a² a³.
B is the armature formed of superimposed plates of soft iron bb, b¹ b¹, with
insulating material between. The armature, which it will be seen is of a somewhat
horse shoe form, is coiled with insulated copper wire, the ends of which are carried
to the plates of a commutator D mounted on the stud axle C.
The two outer plates bb of the armature are, as shewn in the drawing, turned
outwards at right angles; this is for the purpose of receiving the ends of two
curved polar extensions 62 62, the opposite ends of which are supported by
blocks 63 63 of some diamagnetic material such as brass.
The ends of the inner plates b₁ 61 of the armature are prolonged, and secured to
a block b of diamagnetic material, into which the stud axle C is screwed, and the
ends of the plates are rounded so as to be capable of rotating freely between the
extensions a¹ a¹ of the field magnet.-By these means it will be seen that a large
polar surface is secured both to the armature and field magnets, while the magnets
themselves are capable of being rapidly magnetized and demagnetized.
A corresponding stud axle C is rivetted to the opposite end of the armature, and
the armature is mounted in bearings carried by the bridge pieces E E, which aro
screwed to the field magnet.
The motor may be connected to a battery or other generator of electricity in any
well known or convenient manner, but the mode of connecting the motor with
a battery which I prefer, is illustrated by diagram in Fig. 1, F and G representing
two batteries. The negative pole of the battery F is connected to the terminal a
of the field magnet of the motor, and the positive pole of the battery G is connected
to the other terminal a³ of the motor.-The positive pole of the battery F, and the
negative pole of the battery G, are respectively connected to the brushes H and I
By this means the currents from the batteries F and G will be caused to traverse
the coils of the armature and the field magnets equally and simultaneously.

page_text: Having now particularly described and ascertained the nature of my said
invention and in what manner the same is to be performed, I declare that
what I claim is
1st The mode herein shewn and described of forming the armature and field
magnets of an electro motor, whereby large opposing polar surfaces are obtained,
which at the same time admit of being readily magnetized and demagnetized.
2nd The mode of connecting the motor with the battery as shewn and described
with reference to Fig. 1, whereby I am enabled to ensure the magnetization of the
field and of the armature equally and simultaneously.