Improvements in Electric Controllers.
Year: 1897

page_text: Date of Application, 6th July, 1897-Accepted, 14th Aug.,
1897
COMPLETE SPECIFICATION.
Improvements in Electric Controllers.
We, THE BRITISH THOMSON-HOUSTON COMPANY, LIMITED, of 83, Cannon Street,
in the City of London, Electrical Engineers, do hereby declare the nature of
this invention (which has been communicated to us from abroad by Alexander
F. Macdonald, of Schenectady, County of Schenectady, State of New York,
United States of America) and in what manner the same is to be performed, to
be particularly described and ascertained in and by the following statement:→
The present invention relates to controllers for controlling electric motors.
have aimed to simplify the construction of the controllers by lessening the number
of necessary moving contacts; and in certain cases arranging the contacts on
the controller drum so as to economize space.
We
The improvements herein set forth may be embodied in controllers for a
number of different purposes. We show it applied to controllers used
for braking and regulating electric motors on electric tramways, and also
applied to controllers for low and high speed combinations, such as are used for
heavy traffic; since both of these types of controllers are now especially notable
instances in which simplification is desirable in order to keep down the size and
weight of the apparatus.
In a combined regulating and brake controller, we dispense with the extra
set of moving contacts, heretofore employed for establishing the brake circuit,
and we utilize in their stead the moving contacts normally employed in establish
ing and controlling the power circuit, thereby reducing the number of moving.
contacts and the cost of maintenance to a minimum. In carrying out this par-
ticular feature of the invention, a single set of contacts is mounted on a cylinder
in the usual manner; situated in such a position that they will make contact
with the moving cylinder are two sets of stationary brushes arranged in
alternation; the contacts on the cylinder bearing such a relation to the stationary
set of brushes that only one set can be in engagement with the cylinder at a given
time. To move the cylinder in a vertical direction so that the contacts thereon
may be opposite the desired set of brushes, a lever is provided, so arranged that a
movement in one direction will move the contacts on the cylinder to a point
where they will engage with one set of brushes, and when in the other direction
the contacts will be in a position to engage with the other set of brushes. One
set of stationary brushes is connected to the dynamo electric machines in such a
manner that when current is supplied thereto by moving the contact cylinder into
engagement with the brushes, the dynamo electric machines will act as motors
and propel the vehicle; the second set of brushes is so connected that when the
contacts on the cylinder are moved to a position opposite them and the circuit
closed, the dynamo electric machines, having been converted into generators by
suitable means, will supply current for braking purposes, and by varying the
position of the contact cylinder, the resistance of the circuit may be regulated.
In certain types of controllers with which we are familiar, particularly designed
for heavy work, a commutating switch is employed for establishing a series or

page_text: parallel relation of the motors, and a separate rheostatic switch or cylinder for
closing the circuit and regulating the motors when so connected.
:
By our present invention the commutating switch is dispensed with and a
double set of stationary brushes provided, so connected with, the motors that
when one set of brushes is in engagement with the contacts on the moving
cylinder, a series relation of the motors is established, and when with the second
set a parallel relation; the cylinder being so arranged that the resistance of the
circuit in either case may be varied as desired.
.
A further object of the invention is to reduce the height of the contact cylinder
(which in controllers designed for heavy work is an important advantage), at
the same time maintaining suitable insulation between contacts. The invention
also has for its object to utilize the inner periphery of the cylinder, which as
ordinarily constructed is unemployed.
In carrying out the last named feature of our invention, certain of the contacts
are placed on the inner periphery of the cylinder and preferably staggered with
respect to those on the outer periphery, thereby reducing the liability of short-
circuiting by the screws or bolts employed in securing the contacts to the
cylinder. Extending upward inside of the cylinder in a direction parallel to
the actuating shaft is a suitable insulating support to which are secured the
sets of brushes; the cables or connections therefrom being brought out in any
suitable manner which will permit the free operation of the cylinder; a second
set of brushes would also be mounted for engagement with the outer set of moving
contacts.
In the accompanying drawings, Fig. 1 is a diagrammatic view of our invention,
with the circuits arranged for propelling and braking purposes; Fig. 2 is a
diagrammatic view in which the circuits are arranged for high and low speed
combinations; Fig. 3 is a plan view of the contact cylinder; Fig. 4 is a sectional
view of the same, and Fig. 5 is a section on line 5-5 of Fig. 4.
1
The cylinder A is provided with contacts mounted thereon in any desired
manner, and adapted for rotary movement. Situated at one side of the cylinder
are two sets of stationary brushes arranged in alternation, those numbered. from
1 to 10 being employed when the motors M and M are employed for propelling
the vehicle, and those from 11 to 22, when the motors M and M' have been
converted into generators and are supplying current to the brakes S. A reversing
switch B is located in any convenient part of the controller casing, and is so
arranged that the direction of rotation of the motors may be reversed, and also
the relation of the field and armature of the motors at the time it is desired to
convert the motors into generators and supply current to the brakes S. We
prefer to employ for this purpose the switch mechanism shown in the patent to
H. H. Lake (E. A. Sperry) No. 18786, dated August 25, 1896. As howeven the
particular construction of the reversing switch forms no part of this invention,
we omit further reference to the operating mechanism.
In Figs. 3, 4 and 5 we have shown the mechanical construction of the switch.
A central shaft P is provided on which are mounted the spiders C, C, provided
with spokes and a flange which on its outer periphery is polygonal, thereby
furnishing a good bearing surface for the insulating pieces D which form the
barrel of the controller. Mounted on the insulating pieces I are the contacts E
which are divided in any suitable manner to give the desired electrical 'con-
nections. At the lower portion of the cylinder or barrel and on the inside are a
numoer of contacts E'; these are similar in construction to those on the outside,
and are preferably staggered with respect thereto; this reduces to a minimum the
liability of short-circuiting between the contacts, by the screws or bolts employed
in their construction. Engaging with the contacts E and E' are rows of brushes
mounted on insulating supports F, F; these brushes are provided with springs
permitting them to make good contact with the moving cylinder.
In order to raise the cylinder A vertically, when it is desired to establish new
circuit connections, a collar P¹ is mounted on the shaft P, and engaging there-