Improvements in Electric Motors.
Year: 1889

page_text: Date of Application, 7th Oct., 1889-Accepted, 16th Nov., 1889
COMPLETE SPECIFICATION.
Improvements in Electric Motors.
1, HENRY GROSWITH, Electrician, of 5013, Master Street, in the City of Philadelphia,
county of Philadelphia, and State of Pennsylvania, United States of America, do
hereby declare the nature of my invention for IMPROVEMENTS IN ELECTRIC MOTORS
and in what manner the same is to be performed, to be particularly described and
ascertained in and by the following statement:-
My invention relates to electric motors of the "Gramme" type, in which the power
is furnished by a cylindrical armature revolving in a vertical plane between the poles
of a fixed field, and it consists in the improved construction and combination of parts
of the armature and commutators of an electric motor of that class as will be herein-
after more fully set forth.
Figure 1 is a side elevation of my improved electric motor.
Figure 2 is a perspective view of the revolving hub with its armatures.
Figure 3 is a sectional view through the axis of said hub with its armatures and
other appurtenances, showing the same as when constructed for a "single-header,” or
with contact plates and commutators on one side of the machine only.
Figure 4 is a similar view of the same parts as arranged when the machine is to be
run as a "double-header," or with contact plates on both sides of the machine.
Figure 5 is a transverse sectional view on line a- in figures 3 and 4.
Figure 6 is a side view of the revolving armature, with the box or bearing for the
contact plates removed; and
Figure 7 is a perspective detail view of the inner side (facing the armature) of the
said box or bearing.
Like letters of reference denote corresponding parts in all the figures.
My improved motor is constructed with the usual concaved polar extremities, A, A,
of cast iron or other suitable metal, and of sufficient size and weight for the con-
templated horse-power. Those polar pieces are provided, on top, with the usual coiled-
wire fields, B B, which are connected by a magnet or cross-plate, in the usual and
well-understood manner; these parts of the machine forming no part of my invention,
but being common, in a more or less modified form, to all electric motors of that
type.
The revolving armature, which, with its adjuncts, constitutes my improvement, is
built as follows: I first construct, by turning in a lathe, a wooden cylindrical hub or
core, D, of the proper dimensions, and adapted to be secured firmly upon a central
shaft, E. This core, D, is made in two parts or sections, D and D', both of which are
bored through centrally to receive the shaft, E, upon which they are suitably fastened,
the part of the section D' being fastened endwise upon the other part or section, D,
by means of ordinary wood-screws, F, the heads of which are countersunk in the outer
face of the part D', as shown in figures 3 and 4.
The complete wooden hub, D D is concaved or recessed aunularly to form a seat
for the coils or convolutions, 1, of insulated wire, each of which is covered by rings
or. bands, G, of suitable insulating material. These insulated wire rings or coils are
disposed equidistant from one another, around and upon the core or hub, D D', from
which, however, they are separated by the inner sides of the insulating bands, G, which
rest in the annular concave recess or seat in the hub.
The series of insulated coils, 1, is held together and fastened upon the hub by means
of a cylindrical core, forming a band which is built up of a series of soft iron rings, H,
alternating with rings, h, of paper or other suitable insulating material, thus forming,
so to speak, a compound annular core, H, for the series of coils, which core is
covered with insulating material and forms an insulated band around the wooden hub,
1037

page_text: clamping the inner sides of the coils, for which it forms the core, against the hub, as
will be seen more readily by reference to figure 5 of the drawings.
By constructing the wooden hub or core in two parts, as described, it will be
observed that the core-band, H, with the wife-coils lisposed upon and around it, may
readily be placed upon the part D, after which the other part or section, D¹, is placed
in position and fastened by means of, the screws, F. The two parts D and D' being
thus fastened together; they form a firm seat or support for the concentric core, H h,
and coils or bobbins, I
Upon one (or both) heads of the hub is fastened a series of equidistant radial metal
plates or sectors, K, corresponding in number to the number of insulated wire coils.
The terminal points, and, of the wire constituting each armature coil are connected
to these plates alternately, i.e., the bottom terminal,, of one of the coils being con-
nected to one of these plates or sectors, the other or upper terminal, i, of the same
coil is connected to the next adjacent sector-plate, to which, again, is connected the
bottom terminal, , of the coil next in order; and so on through the entire series of
plates and coils, thus completing the electric circuit in the armature through all the
actives composing it.
Fastened upon one or both heads or ends of the wooden hub is a shallow cylindrical
wooden box, L. forming a bearing for the radially disposed contact or commutator
plates, M, which are of copper or other suitable metal.
Each of these plates has, at its inner end, a right-angled elbow or projection, m,
which is inserted through and fits into a hole bored through the head of box, L. The
object of this elbow or projection, m, is twofold, riz.:
1st, it forms a means of attachment for its appropriate plate, M, upon the box or
bearing; and
2nd, it forms a contact between said plates M, and the corresponding or registering
plates or sectors, K, on the hub; the projections, m, being of sufficient length to press
against said plates with their inner ends, which are covered and protected by the rim, 7,
of the box or hearing . The plates, M, and K., should, of course, be properly
insulated from the heads or bearings into which they are inserted.
If it is desired to construct the machine as a ( double-header," and thereby double
its power or capacity, the fields with the polar pieces should, of course, he made of
sufficient size for the increased capacity of potential required. I also double the
number of coils on the armature, and duplicate the plates M and K, with their attach-
ments; that is to say, instead of providing only one side or head of the revolving
armature with these appurtenances (using a plain wooden disk only on the other side),
as in figure 3, I provide both sides with these attachments, as in figure 4, connecting
the radial sector-plates K on opposite sides alternately to alternating coils on the
armature. In other words, the termini of half the number of coils, alternating with
one another, are connected, in the manner described, to the insulated conduit plates or
sectors K, on one side of the machine, while the termini of the remaining half (alter-
nating with the others) are similarly connected to the conduit plates K on the opposite
side and thereby providing the armature with contact or commutator plates on both
sides, each side being of course, equipped with the usual fixed commutator brushes,
instead of having these on one side only, as in a "single-header" machine.
By arranging the commutator plates M radially in a vertical plane, the friction
between them and the brushes is reduced to a minimum, resulting in reducing the
wear both of brushes and contact plates.. The box, L, may be removed in a moment
of time simply by loosening the screws by which it is fastened upon the sides of the
wooden core, whenever it is desired to repair or replace their respective plates; and
by riveting the elbows, m, of the contact or commutator plate on the inside of the box
or bearing L, they will be held firmly in their appropriate position relative to the
brushes.
From the foregoing description, taken in connection with the drawings, it will be
observed that this motor may be constructed at a comparatively small expense, and
also that, simply by unscrewing screws F and removing the hub-section D¹, the coils

page_text: and the core-band connecting the same may be roadily removed, whenever desired,
for repair or for other purposes.
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 I
claim is:
1. An amature for an electric motor having a hub composed of two separable
sections connected end wise at right angles to the axis, and a removable disk or plate
provided with radial metallic conduit plates or sectors, substantially as described.
2. An armature for an electric motor having a hub or core made in two sections
adapted to be separated end wise from one another and a removable disk or plate
secured to said sections, provided with radial metallic conduit plates or sectors, said
hub sections having a concaved arm or flange whereby when the sections are united
upon the central shaft a seat will be formed for a series of elongated wire coils arranged
parallel to one another and to the axis of the hub, substantially as described.
3. An armature for an electric motor composed of separate coils of insulated wire
having a common annular core connecting them to one another, said coils being
arranged parallel to one another and to the axis of the notor shaft, a central bub or
core consisting of two separable parts or sections connected to each other endwise and
at right angles to the shaft and a removable disk or plate provided with radial metallic
conduit plates or sectors, substantially as described.
4. In an armature for an electric motor the combination with the hub or core made
in two separable sections united together at right angles to the axis and oach section
provided with a concaved rim or flange, of the removable plate or disk secured to the
hub sections provided with radial metallic conduit plates or sectors, and the armature
coils seated upon the peripheries of the hub section, and the terminals of said coils
being connected with the metallic conduit plates or sectors, substantially as
described.
5. An armature hub or core for an electric motor consisting of the sections Dand D',
each having a concaved rim or flange, the screws F, F, passing through section Di
and having their heads countersunk therein and connecting said sections together and
the removable disk or plate secured to the hub sections and provided with radial
metallic conduit plates or sectors, substantially as described.
6. The combination of the armature proper constructed substantially as described;
removable disk or plate provided with radial metallic conduit-plates or sectors adapted
to connect the termini of the wire-coils or actives" in the inanner described; and
the removable box or bearing carrying the radial contact or commutator plates
arranged in a vertical plane and connected at their inner ends to the corresponding
sector-plates; substantially as and for the purpose set forth.
7. The combination, in an electric motor, of an armature constructed substantially
as described; the radial connecting plates or sectors; and the radial commutator
plates arranged in a vertical plane and adapted to hear with their outer sides or faces
against commutator brushes adapted to press against them at right angles or in a
direction parallel to the axis of the motor, substantially as and for the purpose shown
and set forth.
H. D. FITZPATRICK,
70, Wellington Street, Glasgow, Applicant's Agent.