Improvements in the Arrangement and Regulation of Electric Motors for Traction, Marine Propulsion, and like Purposes.
Year: 1889

page_text: COMPLETE SPECIFICATION.
Improvements in the Arrangement and Regulation of Electric
Motors for Traction, Marine Propulsion, and like Purposes.
I, ALFRED JAMES JARMAN of 82 Kellett Road Brixton in the County of Surrey,
Electrical Engineer 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:-
-
My invention chiefly relates to the proper regulation of electric motors when these
are subjected to an intermittent load, which may vary considerably while said motors
are in action; and has for its object the. arrangement of two electric motors, herein-
after called a double or compound motor, in such a manner that the "torque" thereof
may be increased in inverse ratio to the speed rate, or the rate of speed may similarly
be increased in inverse ratio to the "torque," or the operative parts of said compound
motor may be so divided as to allow one part thereof to be electrically inactive while
the other part is performing mechanical work, and absorbing electrical energy; all
these several degrees of regulation being carried out by means of a single switch,
commutator, or other device.
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In overcoming the vis inertia of a dead load, whether in the application of electric
motors to tractive or other purposes; it has hitherto been a serious disadvantage in
that the motor when starting is practically shortcircuiting the source of the electric
current, thus absorbing the maximum of electric energy. when the torque is at
the minimum, and the full efficiency is not developed until said motor has attained
that rate of speed where the counter electromotive force diminishes the working
current to the degree of highest efficiency.
In order to overcome this and other disadvantages appertaining to systems of
electric power as hitherto adopted, various types of differential gearing have been
employed so as to mechanically regulate the power and speed, independently of the
electric motor, and consequently of the working current.
According to my invention 1 am enabled to dispense with any form of differential
gearing, or other method of varying or changing the speed ratio mechanically;
depending entirely upon the employment of a double or compound motor, with its
gearing for the transmission of power, consisting of two armatures of any suitable
type, mounted upon one spindle or axle, or if mounted upon separate spindles, these
may be so coupled or connected as to render the rotary motion thereof uniform, and
concentric. Said double or compound motor is electrically regulated by means of
varying the couplings or connections thereof, so as to alter the electrical conditions
relatively to the working current.
In order that my invention may be clearly understood, I have appended the
accompanying diagrams, shewing the various methods of altering the connections of
the double or compound motor aforesaid, for obtaining the perfect regulation thereof,
but I do not confine myself to, and have not shewn, any form or type of switch or
commutator for producing the variations shewn by Figures 1, 2, 3, and 4 preferring
however, to employ one with a simple movement, rotary or otherwise so that the
degrees thereof may correspond to the variations of the couplings or connections
before mentioned.
Figure shews the double or compound motor with both armatures and field
magnets connected in series with the source of the electric current, the terminals
thereof being indicated by the signs + and
Figure 2 is a diagram shewing one part A of the double or compound motor
actuated by the electric current, the ends of the conductors being marked + and
to shew connection with the main leads. The other part B of said double or compound
motor is electrically inoperative, although the armature may revolve idly the ends or

page_text: terminals ab of the conductors being disconnected from said main leads, and therefore
open. Thus, by means of a suitable switch or commutator, either A or B may be
connected to the leads, or main conductors, and become electrically operative, while
the other revolves idly.
The diagram Figure 3 shews both parts or sections of the double or compound
motor connected in parallel or multiple with the electric circuit, and Figure 4 is a
diagram shewing the arrangement of the connections when I desire the two parts or
sections A and B to be operated separately and alternately, so that one may, when
actuated by the current revolve in a given direction while the other is electrically
inert, and that the motion thereof may be reversed when the opposite section is
operated by the current, and that first mentioned rendered electrically inactive by the
movement of the switch or commutator hereinbefore referred to.
Figure 5 shews an arrangement of the double or compound motor according to
my invention, in which each armature is mounted upon a separate spindle, these
being placed concentrically, and a clutch or other device interposed to connect or
disconnect them mechanically when required: the electrical manipulation in this case
being identical with that hereinbefore described and shewn by the diagrams, Figures 1,
2, 3, and 4.
I may in order to obtain perfect regulation of the double or compound motor,
according to my invention either employ a coil, or length of wire of high resistance,
or a series of such coils or lengths of wire, which may be included in the external
circuit at will by means of a suitable switch, or I may wind the field magnets with
layers of wire of varying resistances, and cause these to be either cut out of, or
included in the circuit by means of a suitable switch, when it is requisite to increase
or reduce the current by varying the total resistance. The differential winding of the
field magnets above referred to may either be made with wires of different sectional
area or of different metal or alloy, the ends of each section, or layer thereof, or series
of sections or layers, are led to the switch so that each or all of them may be cut out
or included as aforesaid.
Although in the accompanying diagrams I have shewn a certain method of coupling
or connecting the coils of the field magnets of the double or compound motor, I do
not confine myself to this or any special method thereof, or means therefor or any
form or type of motor so that the connection or coupling of each section of the double
or compound motor may be varied in the manner shewn, by the switch or commutator
as aforesaid.
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,
First. The combination of two armatures upon one axle or spindle to form a double
or compound electric motor, with one set of transmission gearing for obtaining
variable speed, and reverse rotation, substantially as herein described and shewn by
the accompanying drawings.
Second. The combination of two armatures upon separate spindles, with corre-
sponding field magnets, and a clutch, or other suitable coupling device, to form a
double or compound electric motor, with one set of transmission gearing,
substantially as herein described, with reference to Figure 5 of the accompanying
drawings.
Third. In a double or compound motor, as referred to in the preceding claims, the
method of arranging the two parts or sections thereof, in series, parallel, or singly,
with the source of the electric current, by means of a switch or the like with or
without external or other resistances for the purpose of obtaining variable speed with
one set of transmission gearing, substantially as herein described with reference to the
accompanying drawings.
Fourth. In a double or compound motor, as referred to in the preceding claims.
the employment of two armatures, arranged concentrically, one being electrically

page_text: inoperative while the other is electrically operative, substantially as herein
described.
Fifth. In an electric motor, the employment of two armatures upon one spindle or
axle, one only of said armatures being operative at the same time.
Dated this 30th day of July 1889.
FREDK. WALKER & HYDE,
4, Little Moorfields, London, E.C.. Agents for the Applicant.