IMPROVEMENTS IN ELECTRO-MOTORS;
Year: 1883

page_text: PROVISIONAL SPECIFICATION left by John Imray at the Office of the
Commissioners of Patents on the 4th June 1883. Communicated to him
from abroad by Hermann Theodor Hillischer of Vienna in the Austrian
Empire, Doctor of Medicine
me
JOHN IMRAY of N° 28 Southampton Buildings Chancery Lane in the County
of Middlesex "IMPROVEMENTS IN ELECTRO-MOTORS;" [communicated to
from abroad by Hermann Theodor Hillischer of Vienna in the Austrian Empire,
Doctor of Medicine]
The object of this invention is to improve the construction of electromotors so
that their dimensions and the space occupied by them may be as small, and yet the
power evolved by them as great as possible, and also to adapt them for driving
rotary hand-tools.
These improvements relate to that class of electromotors in which electromagnets
carried by a frame or standard are arranged around a shaft which they cause to
revolve by successively attracting armatures fastened to the said shaft.
Instead of making the electro-magnets as usual of cylindrical coils with
cylindrical cores, and thus leaving wide spaces between the magnets, the shape of
the coils and cores is made so that almost the entire space of the ring of electro-
magnets is filled up. This result is obtained by constructing each iron core as well
as its coil in the shape of a sector of a ring. The size of each sector may be such
that 6 or 8 such sectors will form a complete ring. Two or more such rings of
gradually increasing diameter may be arranged concentrically around the shaft and
two or more such sets of concentric rings may be arranged in a row side by side at
suitable distances apart. The number of the said concentric rings and the number
of the said rows will vary according to the power required. Opposite each of the
two sides of such ring or concentric rings of electro-magnets a wheel, disc or
spider fixed to the shaft is arranged, the arms or spokes of which carry armatures
corresponding in position and size to the position and size of the electromagnets.
The pole faces of the cores of the electromagnets are by preference slightly bevilled
so as to be inclined towards the plane of rotation of the armatures, in order that
the magnetic attraction exercised by an electromagnet may gradually increase
while the armature is passing it. A suitable commutator like those used in other
CD

page_text: known systems of electro-motors is provided for consecutively interrupting the
flow of electricity through the coils and for thus consecutively magnetising and
demagnetising the cores. The shaft may be provided with a flywheel for equalising
the motion.
Electromotors constructed according to the present invention may if required be
made of such a small size as to be adapted for imparting rotary motion to hand
For such purposes the
tools such as dental drills, engraving tools and the like.
electromotor is encased in an egg shaped shell of such a size that it can be con-
veniently held in the hand. Through one end of this shell the wires connected
with the source of electricity are passed, whilst the other end is provided with a
tube into which the rotary tool is inserted. A stud or button may be so arranged
in an opening in the shell that by moving it with the finger the motor can be
set in or out of action. The shell is preferably made of two halves connected by
a ring.