Improvements in Prepayment Electric Motors and Meters.
Year: 1898

page_text: Date of Application, 6th Oct., 1898-Accepted, 25th Mar., 1899
COMPLETE SPECIFICATION (AMENDED).
Improvements in Prepayment Electric Motors and Meters.
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 Frank P. Cox,
residing at Lynn, in the County of Essex, State of Massachusetts, United States of
America, Electrical Engineer,) and in what manner the same is to be performed to
be particularly described and ascertained in and by the following statement :--
The invention relates to that class of prepayment devices in which the insertion of
a suitable coin or token in a receptacle sets the parts of the apparatus in operative
relation to permit the passage of a prepaid amount of electric energy.
In prepay-
ment meters or other devices having motors to control, it is desirable to employ the
coin or token to complete the motor circuit, but in most instances the current which
is flowing through the motor is of sufficient quantity to burn the coin or token at
the time it interrupts the circuit.
The invention has for its object to overcome the objection above referred to, and
to this end a relay magnet is employed for controlling the main circuit, the circuit
of the relay being completed by the insertion of the proper coin or token. By this
arrangement current flowing in the relay circuit can be made as small as desired, so
that the arcing at the time the circuit is interrupted will not destroy the coin or
token, and the switch may be arranged to make and break the circuit of the motor
without regard to the amount of current flowing therein.
In the accompanying drawings is shown an embodiment of the invention applied
to an electric meter, in which Fig. 1 is a front elevation of a meter; Fig. 2 is an
enlarged section taken on the line 2-2 of Fig. 1, Fig. 3 is a detail view of the
device employed to prevent improper manipulation of the switch mechanism; Figs. 4
and 5 are details of the switch mechanism; and Fig. 6 is a diagram of the circuit
connections.
The invention bas been shown in connection with an electric meter, and it has
particular utility in this connection; but if desired it may be applied equally well
to other prepayment devices in which the coin or token is employed to complete an
electric circuit, as in prepayment fan motors, for example.
Mounted on the frame A are the operative parts of the meter, comprising stationary
field coils B, an armature C mounted for revolution within the influence of the field
coils, a damping disc D, mounted on the armature shaft and revolving between the
poles of permanent magnets E, and a train of gears F operatively connected to a
worm G on the upper end of the armature shaft.
Mounted on the frame A in front of the train of gears, is a plate H provided with
a coin chute H' adapted to receive one or more coins or tokens I for closing the

page_text: circuit of the meter. To prevent improper manipulation of the meter, as for
example, closing the circuit by means of a wire, a coin receiver J is mounted on the
upper end of the coin chute, into which all coins or tokens must be deposited before
they will be permitted to pass the meter. The coin receiver consists of a circular
plate J¹, that is greater in diameter than the coin chute, and is provided with
a pocket J2, as shown in Fig. 3, into which the coin is dropped by the person
desiring electric energy or its equivalent. The coin receiver is fitted closely into a
receptacle, formed on the upper end of the coin chute, and its edges ; being com-
paratively sharp and being arranged to pass in close proximity to the sides j¹ of the
chute when the receiver is rotated, any piece of string or similar material attached to
a coin in the chute for the purpose of holding a coin in a position to maintain the
circuit closed, will be severed, or if the string be of sufficient size, the coin receiver
To the
will be prevented from rotating, and the coin cannot complete the circuit.
coin receiver is secured a shaft K, and surrounding the shaft is a sleeve K¹, which
is keyed to the operating handle K². Between the handle and the shaft is a spiral
spring L which is connected at one end to the handle and at the other end to a
stationary part of the coin chute H¹. Secured to the front plate of the coin chute is
a pin M, adapted to be engaged by the projections and on the operating
handle, and limit its movement. As shown, the parts are in their normal position,
and in readiness to receive a coin. Upon the insertion of a suitable coin in the
receptacle J, the handle K2 is rotated manually against the action of spiral spring L
until projection k strikes against pin M and arrests further movement. At or about
the instant projection strikes the stop M, the coin in the receiver drops in to the
chute preparatory to closing the circuit of the meter. As soon as the operating
handle K2 is released, spring L returns to its normal position.
The con-
Situated at the end of the chute H¹ (Figs. 4 and 5), is a contact spring N and a
post N1, both of which are connected to one side of an electric circuit.
tact and post are so situated that each coin or token passing through the chute
will make contact therewith. Situated opposite the contact spring is a pivoted
coin-holder O normally retained in the position shown in Figure 4, by the spring 01.
The left-hand side of the coin-holder has a straight edge along which the coin or
token rolls, after it has been released, and continues to maintain the circuit which
has been established between the holder and the spring N; the coin-holder and its
support being connected to the opposite side of the circuit. The right-hand side of
the coin-holder is provided with a curved cam surface 02, and engaging therewith
are projections P¹ on the cam wheel P.
The cam wheel is mounted on shaft P³ of the registering train, and is geared by
any suitable form of reducing gearing to the armature shaft C.
A coin or token I, upon dropping down to the position shown in Fig. 2, will
complete the circuit of the meter in a manner hereinafter described, and the circuit
will remain closed until cam wheel P is rotated by the armature and gearing to a
position where the projections P¹ are out of engagement with the cam surface O2 of
the coin-holder. At the instant one of the projections P¹ leaves the cam surface 02,
the coin-holder O is forced against the stop Q, the coin or token released, and the
next succeeding coin, if there be one, caught and held in the same manner as the
first coin. By this arrangement, any desired number of coins or tokens may be inserted
in the coin chute, and the consumer will receive energy so long as any of the coins
remain in the chute.
In the majority of cases where the coin or token is employed to form a part of the
circuit of an electric meter or motor it will be more or less injured at the time it
interrupts the circuit. To attain the advantages of employing the coin to complete
the circuit, without burning the coin at the time it is released, a relay magnet R is
employed, which is mounted on the side of the frame A. Situated under the magnet
and controlled thereby is a switch S which opens and closes the circuit of the meter
or motor. The circuit of the relay is made and broken by the coin I as it passes
downward through the coin chute.
In Fig. 6 are illustrated the circuit connections of an electric meter. The field

page_text: coils B are connected in circuit with the main a, and main b is provided with a
switch S for opening and closing the load circuit of the consumer and also that of the
meter. The armature C is connected across the mains a and b, and provided with
the usual resistance T, for reducing the current flowing therein. One end of the
energizing coils of the relay magnet R is connected to terminal U, which also forms
one terminal for switch S, and the other end is connected to coin-holder O. The
spring contact N and post N¹ are connected to main a, which is the opposite side of
the circuit. The coin I completes the relay circuit, which energizes magnet R, and
switch S closes the meter and consumption circuits. After the consumer has used
the prepaid amount of energy, cam P will release the coin-holder O and the coin will
drop into a suitable receptacle in the meter.
Having now particularly described and ascertained the nature of our said inven-
tion (as communicated to us from abroad) and in what manner the same is to be
performed, we wish it to be understood that we are aware of Letters Patent
No. 2224 of 1896, granted to Charles Orme Bastian and Herbert Cecil Hodges, and
that we do not claim anything described and claimed therein, but, we declare that what
we claim is-
1. In a coin controlled mechanism for an electric meter or motor, the combination
of a field-magnet, an armature mounted for movement within the influence of the
field-coil, a relay magnet, terminals therefor arranged to be bridged by a coin or
other token to complete the circuit of the relay magnet, and a switch controlled by
the relay for closing the meter or motor circuit.
2. In a coin-controlled mechanism for an electric meter or motor, the combination
of a series field-magnet an armature connected in shunt to the mains, a relay
magnet, terminals therefor adapted to be bridged by a coin or token to complete
the circuit, and a switch controlled by the relay magnet for closing the circuit of
the meter or motor.
3. In-a-prepayment electric-meter-the-combination of a field magnet-which-is
influenced by changes-of-lond-in-the consumer's-circuit, an-armature--which-is
influenced by the potential of the system, n-switch-for-making-and--breaking the
consumer's circuit, and a-relay-magnet-which-controls-the-nction-of-the-switch.
3.-4. In a prepayment electric meter, the combination of a field-coil-which is
influenced by change of load in the consumer's circuit, an armature which is
influenced by the potential of the system, a switch for breaking and making the
consumer's circuit, a relay magnet which controls the action of the switch, and
terminals arranged to be bridged by the coin or token, which are connected to the
relay magnet.
4. In a device for preventing the improper manipulation of a coin controlled
mechanism, the combination of a coin chute, a rotary plate which is greater in.
diameter than the coin chute, a pocket formed in said plate, and a handle for
rotating the plate.
5.-6. In a device for preventing the improper manipulation of a coin-controlled
mechanism, the combination of a coin chute, a rotary plate which is greater in
diameter than the coin chute, a pocket formed in said plate cutting edges on the
plate which engage with similar edges on the coin chute, a handle for rotating the
plate, and a spring for returning the plate and handle to their normal position.
Dated this 4th day of October 1898.