Improved Means for Regulating Electric Motors.
Year: 1896

page_text: Date of Application, 14th Apr., 1896-Accepted, 30th May, 1896
Improved Means for Regulating Electric Motors.
A communication from abroad by OTIS BROTHERS AND COMPANY, of 38 Park
Row, New York, in the United States of America, Manufacturers.
We, OTIS ELEVATOR COMPANY LIMITED, of 4 Queen Victoria Street in the
City of London 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 :-
This invention relates to electric motors, and more particularly to means for
regulating the starting of said motors, and it has for its object to provide improved
means for this purpose which shall operate automatically and magnetically to
control the electric current passing to the motor in starting, and the invention
consists in the various features of construction and arrangement of parts,
having the mode of operation substantially as herein after more particularly set
forth.
Referring to the accompanying drawings
Figure 1 is a diagrammatic representation of one embodiment of the
invention.
Figure 2 is a similar diagrammatic representation of a modified arrangement
of the invention and
Fig. 3 is a detail view, showing a modified arrangement of part of the apparatus
for carrying out the invention.
It is well known that in starting an electric motor, especially when used in
connection with a constant potential circuit, it is desirable to admit the current to
the armature of the motor gradually, and to do this it has been common to include
a certain amount of resistance in the armature circuit of the motor, which resistance
is gradually reduced or cut out as the speed of the motor increases and the counter-
electromotive force of the motor accumulates. A number of devices have been
suggested to accomplish this general purpose of automatically reducing the
auxilliary resistance of the armature circuit of a motor, and it has been
suggested to use in connection with such devices a mechanical dash-pot to
control their operation, and it is one of the objects of this invention to do
away with this mechanical dash-pot and accomplish the same purposes and
objects by electro-magnetic devices, and a portion of the invention may be said
to consist in an electro-magnetic dash pot, which is arranged and connected
with the other parts of the apparatus in such a way as to control or regulate the
motor.
While such apparatus is capable of many and various uses wherever electric
motors, and especially shunt or compound wound electric motors are used, the
invention is shown in the present instance as adapted to be used in connection with
electric elevators, for which purpose it is specially adapted, and the principles
thereof will be explained in that connection, without, of course, intending to limit
the invention to such uses.
It is not deemed necessary to show the entire electric elevator apparatus, as
such is well known and understood by those skilled in the art, and only the parts
necessary to a clear understanding of the present invention are displayed in the
drawings.
Referring more particularly to Figure 1 (although corresponding parts are
'similarly lettered in other figures) A, represents the usual wheel or pulley around

page_text: which the hand-rope A', passes, which hand-rope, as is usual, is under the control
of the operator in the car of the elevator, and this wheel is mechanically or
manually operated by the hand-rope or some equivalent device in order to
start and stop the electric motor, which may be connected in any of the usual
ways with the elevator car, or with other machinery which it may drive.
M, represents diagrammatically an electric motor, which may be of any desired
type or construction, but is shown in the present instance as being a shunt or com-
pound wound motor, in which a portion of the coils of the field-magnet are included
in a constantly closed branch circuit between the main line terminals plus and
minus.
Thus it will be seen that the conductor 1, is shown diagrammatically as forming
a portion of the field-magnet coils in a constantly closed shunt, although, of
course, if desired, the usual make-and-break switch may be applied to break
the shunt whenever the motor is stopped, and to close the shunt whenever it is
started.
a
The armature circuit of the motor includes a pole-changer or current-reverser, B,
which may be of any usual and well-known type, and which in the present instance
is illustrated as comprising plate or cylinder, having on its periphery certain
portions of conducting material and non-conducting material arranged in the well-
known manner, and this current-reverser is also shown as being operated
mechanically by a connecting bar or rod B', which in this instance is connected
positively to the wheel or pulley A, and directs the current through the armature
in one direction or the other, according as the wheel or pulley A, is rotated in one'
direction or the other.
Also included in the armature circuit of the motor is an auxiliary resistance
device C, composed in the present instance of a number of plates c, c', c².. c, c, c, co,
with intermediate resistance coils between the contact plates except at the
extremities, and between plates c, e. Connected to operate with this resistance
is a lever-arm D, carrying on its extremity a spring arm or contact piece d adapted
to sweep over the various contact plates c &c. as it is moved in the manner herein-
after set forth. In Figure 1, this lever-arm is shown as being mounted on an
axle E, so that it can rotate freely thereon, and mounted on the same axle or
shaft, E, is a gear wheel F, having a ratchet wheel F', with which a pawl D', on
the lever-arm engages, so that when the lever-arm D is moved in one direction, the
wheel F and ratchet wheel F1, will not rotate, but when they are moved in the
opposite direction, the pawl D', will engage the ratchet-wheel F, and rotate
the wheel F. This wheel F, is connected in the present instance through a
train of wheels F2, F3, with a metal disk G, which is mounted in such a relation
to the magnet or pole-piece H, as to be within the magnetic field thereof, so that
the movements of the disk will be influenced or controlled by such magnetic field,
thus acting as a magnetic brake or dash-pot.
This magnetic field may be produced in many and various ways, which will
readily suggest themselves to those skilled in the art, and may be used in
accordance with the requirements or wishes of any particular case. Thus, if it
is desired to make a uniform magnetic field, in which the disk shall operate, such
field may be readily produced by a shunt winding from the field-magnet circuit, as
is indicated in dotted lines 2, while a variable magnetic field may be produced by
winding the magnet or pole-piece H, in series with the armature circuit, and
consequently, the speed of rotation of the disk G, will vary in proportion to
the current passing through the armature circuit, and this is generally a more
desirable arrangement, as the less work the motor has to do, the quicker will
the lever-arm be allowed to cut out the auxilliary resistance in the armature
circuit. This winding indicated in Figure 1, will be explained more fully
'hereinafter.
So far, we have assumed that the weight of the lever-arm itself is sufficient to
operate it to cut out the resistance gradually, but if this is insufficient, a counter
'weight D', may be applied to the lever-arm, and this is preferable, and preferably

page_text: relation
is made adjustable, so that by properly adjusting the swicen
other parts of the apparatus, the resistance may be cut out of the armature circuit
in the most satisfactory manner.
This lever-arm D, is preferably arranged so that in cutting out the resistance it
can move under the control of the magnetic brake or dash-pot device, but when
the motor is stopped, it is generally desirable to cut in the resistance to the
armature circuit quickly and positively, so that accidents may be avoided, and
especially if the motor is again started immediately after being stopped, the
resistance shall all be included in the armature circuit without fail, and for this
purpose there is provided a cam, I, which in this instance is attached to the shaft
of the wheel, or pulley A, and is operated mechanically therewith, and is so arranged
that the lever-arm is positively moved upward or in such a directiou as to cut in
the resistance whenever the pulley A, is moved in a position to stop the motor.
Various forms and shapes of cams or other equivalent devices may be used, but
that shown in the drawing is simple and effective, and it will be observed that the
lever-arm D, is provided with a stop or stud d, which fits in the cam recess, and
when the parts are in their normal position, as shown in the drawing, the lever-arm
is raised to its upper position, but when the pulley or wheel A, is moved in either
direction, the cam-slot permits the lever-arm to move downward without being
positively controlled by the cam; but when the cam is restored to its normal
position, the lever-arm is positively lifted by the stud d', bearing on the cam-face,
so that the resistance in the armature circuit is positively included.
While, as above indicated, the motor may be variously wound, and various
arrangements of the contact pieces of the resistance may be made, there is
indicated in the drawing an arrangement, in which the contact piece c, is insulated
from the others, so that when the brush d, of the lever-arm D, is on the contact
plate c, the circuit of the armature is broken, but as soon as it moves onto contact
plate e, all the resistance between the adjacent plates are included in the armature
circuit.
There is also shown an arrangement whereby the series field-magnet coils are
arranged in sections and are included between some two of the various contact
plates. As for instance, connected to contact plate c, is a conductor 3, which
extends to the field-magnet coils of motor M, and returns to contact plate c².
Again contact plate c', is connected by a conductor 4, which in this instance, leads
to the coils h, of the electro-magnet or pole-piece H, and thence includes a portion
of the coils of the field-magnet of the motor M, and returning is connected to the
contact plate clo, and it will be observed that when the brush d, is on the contact
plate e, all the series field-magnet coils are short-circuited or cut-out, as well as
the coils of the electro-magnet, H.
From the contact plate e, leads a conductor 5, bearing on the pole-changer, B,
and from the pole-changer lead the conductors 6, 7, connected to the brushes
of the armature of the motor M, and a conductor 8, leads from the pole-changer
to the main conductor 1, while a conductor 9 connects with the conductor 1, and
with the lever-arm D which in this instance is shown as being of conducting
material, although, of course, it may be otherwise made, and the conductor 9, he
connected directly to the brush d, or otherwise, as most convenient.
In the position in which the parts are shown in Figure 1 it will be apparent
that while the main field-magnet coils of the motor M, are energized, the
armature circuit is broken between the brush d, and contact plate c, and is
shown as also being broken at the pole-changer B, which is the preferred
arrangement.
Assuming now that the pulley A, is turned to the right to start the motor,
the pole-changer will be rotated so as to connect conductors 5 and 6, and con-
ductors 7 and 8, and direct the current through the armature of the motor in a
certain direction, and at the same time cam I, has moved so that the stud d³, is
free to move in the cam-space, and the lever-arm (weighted or not as the case
may be) tends to fall to gradually cut out the resistance C, on the armature

page_text: circuit. As soon as this moves, however, so that the brush d, bears on the contact
plate c', the current passes through the various resistances and conductors connected
thereto, energizing the magnet H, and as the pawl D', engages the ratchet-wheel F',
and rotates the wheel F, and its train of gears connecting it to the disk G, this
disk will be rotated in the magnetic field of the magnet H, which field will tend
to retard or control the speed of rotation of said disk, thus regulating the move-
ments of the lever-arm D, the magnet H and disk G, acting as a brake or dash-pot
to the movements of the lever-arm.
As before intimated, as the lever-arm moves, cutting out the resistance, the series
field-magnet coils 3, when connected in the manner indicated are cut out, and
subsequently, the series field-magnet coils 4, are eat out, when the full current is
passing through the armature circuit and the motor is working at its normal speed
as a pure shunt motor, the series field-magnet coils being used preferably in starting
the motor, so as to more readily overcome the inertia of the motor and its load,
and to produce a relatively great torque at the moment of starting the motor.
When it is desired to stop the motor, the cam is restored to its normal position,
and the cam-face is such that it engages the stud d2, and positively moves the
lever-arm to the position indicated, and in doing so the pawl D', passes over the
ratchet-wheel F1, without moving the wheel F, or the disk G, connected thereto.
This arrangement embodies in one form the general principles of the invention
in a practically operating apparatus for many purposes, but it will be observed
that by this construction there is nothing to prevent the lever-arm from cutting
out all the auxiliary resistance whenever the cam is moved to release said arm, and
this results in increasing the current in the armature to the maximum amount and
while this is generally desirable, it may happen for some reason that the motor
does not start properly, and the internal resistance or counter-electro motive force
of the motor does not increase in the proper ratio, so that an undesirable excess of
current may pass through the armature circuit of the motor, and means are there-
fore provided, whereby this excessive current may be avoided, and the maximum
current passing through the armature coils may be limited to that which the motor
can properly take without danger.
One means of accomplishing this result is shown more particularly in Figure 2,
where most of the parts are the same and are similarly lettered as in Figure 1, and
need not be again described. In this instance, however, the lever-arm D, is
shown as formed or connected with a disk or armature of magnetic metal G,
which is arranged to move in the magnetic field produced by the magnets HH,
as before, but which magnets are energized somewhat differently, as will now be
explained. In this case the magnets H', are continuously energized and their
coils are not cut out of circuit when the lever-arm reaches its lowermost position,
and the brush d, is on the contact plate clo, but leading from said contact is a
conductor 5, which includes the coils of the magnets H', in series with the
armature circuit at all times, as is clearly indicated in the diagram, and this is true
whether the series field-magnet coils 3, 4, when used, are in or out of the series
circuit, and whether the motor is operating as a compound or simple shunt motor.
This magnet and the circuits thereof are so arranged and the magnetization
produced is such that the disk or armature G', tends to turn in a direction to cut
in the resistance C, while the weight Da, tends to move the lever-arm D, and
cousequently the disc or armature connected thereto in an opposite direction.
will readily be seen that by properly proportioning the strength of the magnetic
field and the disk or armature thereof with relation to the weight, such a torque
may be produced on the disk or armature G¹, as to just balance the weight of the
lever-arm for a predetermined current passing through the armature and the
magnets thereof, so that if an excessive amount of current passes through
.the motor M, and the magnets H', and disk or armature thereof, the lever arm will
be moved upward, to include more of the resistance, until the resistance of the
motor is increased to such an extent as to properly admit the entire current to pass
through it; and it will thus be seen that the parts may be so adjusted that under
It

page_text: normal conditions the resistance will be gradually and regularly cut out of circuit,.
but under abnormal conditions, the resistance will be cut in or out according to the
requirements of the case, so that all danger of injuring the motor or other parts is
avoided, the apparatus being self-regulating and positive in its operation.
It will be obvious that the lever-arm. may be attached directly to the disk or
armature G¹, as shown in Figure 2, or indirectly, as shown in Figure 3, wherein
the lever-arm D is connected to or mounted on a separate shaft D³, and connected
by gears to the armature G', or it may be arranged in any other equivalent.
manner, it being only necessary that it can be moved backward to cut in the
resistance C, by the armature or disc G. Furthermore, the revolving disk or
armature G¹, may be of any suitable construction, as for instance, a thin copper
disk when used in the manner shown in Figure 1, in connection with the magnet or
pole-piece H, or an iron disk or drun armature G', as shown in Figure 2, which
may be constructed in various shapes and proportions and wound with more or less-
armature coils 10, or it may be of nonmagnetic material, or it may be simply a
series of coils, or any other well-known equivalent structure.
Furthermore, it is not absolutely necessary to have the pole-pieces H', as
surrounding the disk or armature G', with magnetized coils of wire may be made
to answer the purpose, but it has not been deemed necessary to show all these
modifications, as they are well-known equivalents of the structure shown, which is
illustrated as typical, and not as limiting the invention to the precise construction
set forth.
It will further be understood that although the motor is shown as having a
compound winding, and the compound series field is divided into several parts and
connected thereto between different resistance contact-plates, other well-known
the circuits in the manner
arrangements may be provided, buteld is gradually reduced, the speed thereof
illustrated the strength of the motor
increasing steadily, and without fluctuations of the armature circuit.
Instead of the adjustable weight on the lever-arm heretofore described, I may
use a friction brake, such as is illustrated in Figure 3, in which there is a brake
piece K, secured to the side of the pole-pied or magnet H, and having one end
bearing on the disk or armature G¹. This brake piece is shown as mounted on a
stud k, having a spring k', which tends to hold it against the face of the pole-
piece, and an adjusting screw k³, for regulating the air-gap between the brake piece
and the pole-piece.
With this arrangement, it will be seen that the brake piece K, is pressed against
the disk with a pressure that varies as the magnetism in the pole piece and disk
varies, and this varies with the current, in the manner heretofore pointed out, and
the motion of the lever-arm is thereby regulated through the medium of the brake
piece in accordance with the current Howing through the motor.
It has been found advantageous sometimes to tip the brake piece K, with non-
magnetic material K', where it bears upon the disk or armature, to prevent the
parts sticking together.
It will be seen that by regulating the air-gap between the magnet and brake
piece the force or power of the brake can be accurately and delicately adjusted.
Having now particularly described and ascertained the nature of our said inven-
tion and in what manner the same is to be performed as communicated to us by our
foreign correspondents we declare that what we claim is :-
1. The combination with a motor and resistance device in the armature circuit
thereof, of a lever arm controlling said resistance device, and an armature connected
to said lever arm and controlling its movements in one direction, said armature
moving in a magnetic field controlled by the resistance device, substantially as
described.
2. The combination with a motor and resistance device in the armature circuit
thereof, of a lever arm mechanically operated to cut out said resistance from the

page_text: i
armature circuit, and an electro magnetic device connected to the arm to control its
movement in cutting out the resistance, the said electro-magnetic device comprising
an armature moving in a magnetic field controlled by the resistance device,
substantially as described.
3. The combination with a motor and resistance device included in the armature
circuit of the motor, of a lever arm mechanically operated to cut out said resistance
device and mechanically and positively operated to cut in said resistance device,
and an armature connected with said lever arm to control its movement in cutting
out the resistance, the armature moving in a magnetic field controlled by the
resistance device, substantially as described.
4. The combination with a motor and resistance device therefor, of a lever arm
mechanically operated to cut out said resistance, and a disk connected to said lever
arm, said disk rotating in a magnetic field to control the movements of said lever
arm in one direction, the magnetic field being controlled by the resistance device,
substantially as described.
5. The combination with a motor and resistance device included in the armature
circuit of the motor, of a lever arm mechanically operated in one direction and
controlled by an electro-magnetic device and positively and mechanically operated
in the other direction to cut in the resistance device, substantially as described.
6. The combination with a motor and resistance device included in the armature
circuit of the motor, of a shaft, means for moving the shaft, a lever arm controlling
the resistance device, connections on the shaft for positively moving the lever arm
in one direction, a pole-changer in the armature circuit connected to be moved
from the shaft, and a current breaking switch controlled from said shaft, substantially
as described.
7. The combination with a shunt motor and resistance device included in the
armature circuit, of series field-magnet coils connected to said resistance device at
different points thereof, means for controlling said resistance device and arranged
on starting the motor to include the series field-magnet coils, in the armature
circuit and to cut them out as the resistance is cut out of the armature circuit, and
electro-magnetic devices for controlling said means, substantially as described.
8. The combination with a shunt motor and resistance device included in the
armature circuit, of series field-magnet coils connected to the resistance device at
different points, a lever arm for cutting in and out said resistance device and
controlling the series field-magnet coils, an electro magnetic device controlling said-
lever arm in cutting out the resistance and included in the armature circuit, and
mechanical means for positively moving said lever arm to cut in the resistance,
substantially as described.
9. The combination with a motor and resistance device in circuit therewith, of
a lever-arm controlling said resistance, a disk rotating in a magnetic field, and a
pawl and ratchet connection between said disk and lever-arm, substantially as
described.
10. The combination with an electric motor and resistance device therefor, of
series field-magnet coils for the motor connected with said resistance device, a lever-
arm controlling said resistance device, a disk connected with said arm, and a magnet.
controlling said disk and included in the resistance circuit, substantially as
described.
11. The combination with a motor and resistance device in the circuit thereof, of
a lever arm controlling said resistance device, a cam for moving said lever-arm in
one direction, a disk controlling the movements of the lever arm in the other
direction, and a magnet controlling the said disk, substantially as described.
12. The combination with a field-magnet and a disk or armature, of a brake piece
connected to said field-magnet and bearing on the disk or armature and having a
piece of non-magnetic material on its armature bearing face, substantially as
described.
13. The combination with a field-magnet and a disk or armature, of a brake-piece-

page_text: connected to said field-magnet, and means for adjusting the air-space between the
brake piece and field-magnet, said brake-piece bearing on the armature and acting
as a brake therefor, substantially as described.
Dated this 14th day of April 1896.
PHILIP M. JUSTICE,
55 & 56 Chancery Lane, London, Chartered Patent Agent.