IMPROVEMENTS IN ELECTRIC MOTORS
Year: 1882

page_text: PROVISIONAL SPECIFICATION left by Stephen Henry Emmens at the
Office of the Commissioners of Patents on the 10th August 1882.
STEPHEN HENRY EMMENS of Argyll Street, in the County of Middlesex,
Actuary, "IMPROVEMENTS IN ELECTRIC MOTORS
"
My invention relates to certain improvements in solenoids employed as electric
motors, and further to the method of application thereof to various mechanical
requirements.
The main object of my said improvements is to construct a solenoid, any portion
of which may be brought into operation at pleasure, so that the plane of maximum
attraction may be made to advance or recede, thus rendering possible an equable
and continued action upon the moving core.
Around a hollow cylinder I lay insulated wire, alternately coiling it around the
cylinder a space, and laying it parallel thereto a space. This I do continuously,
layer upon layer, and at equal intervals, so that when complete, the cylinder is
enveloped by alternate coils and straight wires between same. From any convenient
portion of the straight wires I remove the insulating material, to enable me to make
electrical contact therewith at any points, and bring any portion of my solenoid
into operation. By a suitable contact device which may be conveniently and
automatically actuated from the moving core, I am enabled to bring coil after coil
into successive operation, thus always keeping the moving core in or near the
plane of maximum attraction. The contact device may be of any suitable form,
such as a hinged lever with contact pieces sliding on the exposed portions of the
wire, and making or breaking contact according to the movement communicated to
it; or it may consist of a bar with projections, each composed of alternate con-
ducting and non-conducting material, making or breaking contact with the exposed
portions of the wire, according to the movement communicated to it; as, however,
the desired object may be attained in many ways, I do not confine myself to these
particular devices, but employ any suitable mechanical arrangement.
The action of the moving core may be adapted to any suitable requirement, where
an electric motor is suitable; but in particular I employ it to actuate mine stamps,
forge hammers, pumps, percussive drills, and the needles of sewing machines.
In the case of mine stamps hammers, and percussive drills, I prefer to make
use of two or more solenoids or systems of solenoids, both connected to the working
SD 077

page_text: rod, the first to lift or withdraw the working rod and the second, automatically
brought into operation at the maximum lift of the first named, to act in a reverse
direction and deliver the stroke. I am thus enabled by alternately exciting the
two systems to secure a greater range of lift and a more forcible stroke than by
the employment of a single solenoid.
In the case of pumps I prefer to use a single solenoid with a reciprocating core
about one third its length, and connected by a brass or other non-magnetizable rod
with the plunger or bucket.
In the case of sewing machines I prefer to use one or more pairs of solenoids,
each pair vertical to one another, and with a single moving core extending into
each solenoid. To this moving core a reciprocating action is communicated by the
alternate excitement of the upper and lower coil or coils, and to it is fitted a cross
bar carrying the needle or needles, and moving in suitable guides.