IMPROVEMENTS RELATING TO THE OPERATION OF ELECTRICAL GENERATORS BY GAS ENGINES
Year: 1883

page_text: LETTERS PATENT to Thomas John Handford of 42 Southampton Buildings in
the County of Middlesex Patent Agent, for an Invention of "IMPROVEMENTS
RELATING TO THE OPERATION OF ELECTRICAL GENERATORS BY GAS ENGINES
"
Communicated to him from abroad by Thomas Alva Edison of Menlo Park in
the State of New Jersey United States of America
PROVISIONAL SPECIFICATION left by the said Thomas John Handford at
the Office of the Commissioners of Patents on the 24th February 1883..
"
THOMAS JOHN HANDFORD of 42 Southampton Buildings in the County of
Middlesex, Patent Agent "IMPROVEMENTS RELATING TO THE OPERATION OF
ELECTRICAL GENERATORS BY GAS ENGINES A communication to me from abroad
by Thomas Alva Edison of Menlo Park in the State of New Jersey, United States
of America,
All attempts which have hitherto been made to produce electricity for illuminating
and other purposes by employing engines actuated by explosions of gas, to drive
the rotating armature of electrical generators have been practically unsuccessful,
for the reason that when the explosion occurs the. speed of the engine, and con-
sequently that of the armature revolved thereby is increased, causing an increase
in the current generated; while between the explosions the speed gradually declines,
and the current is diminished This variation in current of course produces
improper effects in the translating devices supplied from the generator; And this is
especially the case when the current is employed for incandescent electric lamps,
the variations of current causing constant variations in the brilliancy of the lamps.
The object of this Invention is to successfully employ gas-engines in operating
electrical generators, which supply current to electric lamps, electro-motors or other
translating devices; and to this end, the Invention consists in employing in con-
nection with a gas engine and the generator or generators driven thereby, means
operated automatically by the movement of the apparatus, to compensate for the
increase of speed, by reducing the proportion of the entire current generated which
is transmitted to, the translating devices: such means being caused to operate at

page_text: the moment when the increase of speed commences, so that practically the same
current is supplied to the translating devices as before.
The Invention is more especially intended for use in connection with a multiple
are system of lighting by electrical incandescence; though it may be employed with
a series system, and with arc-lamps, or any kind of translating devices.
The generator which is preferably a dynamo electric machine, having its field
and armature coils in multiple-arc relation to each other, but which may have its
field energized from an external source is connected preferably by a belt with the
shaft of the gas-engine.
Lamps or other translating devices are placed in multiple arc across main
conductors leading from the machine.
When the "Otto" or other gas-engine is used, in which an explosion occurs at
every second revolution of the fly-wheel, a cam or eccentric is placed on the shaft
which operates the valves, which shaft revolves with one half the speed of the
main shaft so that the explosion occurs once during each of its revolutions. This
cam or eccentric works an arm whose movement causes a decrease in the proportion
of the current generated, which is supplied to the translating devices, at the
moment of the explosion. This diminution may be accomplished by throwing
resistance into the main circuit, but it is preferable to diminish the proportion of
current in the translating devices by closing other multiple are circuits (through
suitable resistance) and thus providing new paths for the current.
A number of such inultiple arc circuits all of the same resistance may be
simultaneously thrown into circuit, as soon as the increase of speed occurs, but in a
gas engine the speed gradually increases after the explosion up to a certain point
and then gradually declines; therefore it is preferred to close a circuit of high
resistance at the beginning of the increase, and then successively close circuits-of
gradually decreasing resistance, in the proper proportion until the maximum speed
is reached, when the resistances are gradually increased as the speed runs down.
In order to accomplish this it is preferred to employ as resistances a number of
incandescing electric lamps. One terminal of the multiple are circuit from the
main line is connected with the circuit controlling arm worked by the eccentric,
while the other terminal is divided into a number of branches each running to a
contact point. In each of these branches are placed one or more of the resistance
lamps, they being, if more than one is used, in multiple are relation to each other,
so that the branch containing most lamps is the one of least resistance.
The lamps are so arranged that at the first slight increase of speed a circuit
containing only one lamp will be closed by the movement of the circuit controlling
arm, while, as the speed increases circuits containing two, three or more lamps are
successively closed; as the speed again declines, circuits containing less numbers of
lamps are closed until near the end of the first revolution; during the second
revolution the decline in speed is so small and gradual that the generation of
current is practically unaffected by it.
It is preferred to use for opening and closing the multiple arc branches, a com-
mutator, which consists of a number of thin metal plates set near together but
separated by plates of insulation. Each metal plate is extended out beyond the
insulation, and bent so that the plates diverge into a fan shape. Wires, connected
one to each plate, run to binding posts, from which the wires run which form the
circuits including the resistance lamps
A contact point placed at the extremity of the circuit controlling arm slides
backward and forward over the edges of the commutator plates, during each
revolution of the valve shaft. And a thin metal plate is so placed that it will lie
between the contact point and the commutator plates, during that half of the
revolution of the valve shaft during which no explosion occurs, while during the
rest of the revolution, the contact point will pass under this plate, and be in contact
with the edges of the commutator plates
Thus, when the explosion occurs, the contact point passing over the edges of the
commutator plates will close the successive multiple are branches, while when the

page_text: eccentric draws such point back it will be separated from the commutator plates
by the flat plate mentioned and said branches are not affected
As stated it is preferable to vary the proportion of current supplied to the
translating devices gradually
Such variations may however be effected all at once, and this accomplishes the
regulation in a very satisfactory manner, although not so perfectly as that just
described In this case the arm attached to the eccentric merely serves to close a
circuit, which may be a multiple arc circuit of the desired resistance or may act as
a shunt around a wire resistance in the main line. The circuit controller may be
a point dipping into a mercury cup, and withdrawn therefrom as the arm is moved
back and forth; or the circuit may be made and broken at contact points in any
ordinary manner.
With all these arrangements, means are provided for adjusting the position of
the eccentric so that it can be set to act at the proper point.
It is evident that the eccentric may be placed on the main shaft of the engine,
on the shaft of the armature, or on any moving part of the apparatus, or on a
shaft connected with any moving part of the apparatus, proper adjustment of the
eccentric being made to insure its action at the proper point.
The eccentric may be adjusted by means of a set screw.
Or a sleeve carrying
the eccentric may be made adjustable on the shaft by means of a pivotted forked
arm attached to the said sleeve and moved by a traversing screw; a pin on the
shaft working in a slot so that the movement of the sleeve adjusts the eccentric;
a pointer moving over a scale, may also be attached to the arm, so as to admit of
the position of the eccentric being readily determined.
In some gas-engines the air and gas are admitted to the exploding chamber at
such times, and in such proportions that the explosions occur irregularly instead of
at every other revolution. With such engines, an arrangement different from
those described is necessary. Such arrangement consists of a spring-governor,
placed on or connected with the main shaft, or any rotating portion of the engine
or generator, and provided with an arm for varying a resistance placed preferably
in one of the main conductors.
The flat commutator plates described are preferably used with wires running
from them and including resistance coils. As the speed of the engine increases
upon the occurrence of an explosion, the movement of the governor throws the
resistance coils into circuit, while as the speed declines the contact arm is drawn
back and throws out resistance. Or the resistance may be in a multiple arc circuit
when the operation will be the reverse of that just described.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed
by the said Thomas John Handford in the Great Seal Patent Office on the
24th August 1883.
THOMAS JOHN HANDFORD of 42 Southampton Buildings in the County of
Middlesex Patent Agent "IMPROVEMENTS RELATING TO THE OPERATION OF
ELECTRICAL GENERATORS BY GAS ENGINES" a communication to me from abroad
by Thomas Alva Edison of Menlo Park, in the State of New Jersey United States
of America
In the production of electricity for illuminating and other purposes by the
employment of engines actuated by explosions of gas, to drive the rotating
armature of electrical generators, a difficulty is usually experienced arising from
the fact that when the explosion occurs, the speed of the engine, and consequently
that of the armature revolved thereby, is increased, causing an increase in the
current generated; whilst between the explosions, the speed gradually declines,
and the current is diminished This variation in current necessarily produces
improper effects in the translating devices supplied from the generator; and this is
especially the case when the current is employed for incandescent electric
lamps, the variations of current-causing constant variations in the brilliancy of
the lamps.
Now the present Invention has for its object successfully employing gas engines
in operating electrical generators, which supply current to electric lamps, electro-
_motors, or other translating devices; and to this end, the Invention consists in
employing in connection with a gas engine, and the generator or generators driven
thereby peculiar means operated automatically by the movement of the apparatus,
as hereinafter described, to compensate for the increase of speed by reducing the
proportion of the entire current generated, which is transmitted to the translating
devices; such means being caused to operate at the moment when the increase of
speed commences, so that practically the same current is supplied to the translating
devices as before.
The Invention is more especially intended for use in connection with a multiple
arc system of lighting by electrical incandescence; though it may be employed
with a series system, and with arc-lamps, or any kind of translating devices.
The generator, which is preferably a dynamo electric machine, having its field
and armature coils in multiple-arc relation to each other, but which may have its
field energized from an external source, is connected preferably by a belt with the
shaft of the gas engine. Lamps or other translating devices are placed in multiple
arc across main conductors leading from the machine.
When the "Otto" or other gas engine is used, in which an explosion occurs at
every second revolution of the fly wheel, a cam or eccentric is placed on the shaft
that operates the valves, which shaft revolves with one half the speed of the main
shaft so that the explosion occurs once during each revolution of such valve shaft.
This cam or eccentric works an arm whose movement causes a decrease in the
proportion of the current generated, which is supplied to the translating devices,
at the moment of the explosion. This diminution may be accomplished by
throwing resistance into the main circuit, but it is preferable to diminish the
proportion of current in the translating devices by closing other multiple arc
circuits (through suitable resistance) and thus providing new paths for the
current.
A number of such multiple arc circuits all of the same resistance may be
simultaneously thrown into circuit, as soon as the increase of speed occurs, but in

page_text: a gas engine, the speed gradually increases after the explosion, up to a certain
point, and then gradually declines; therefore it is preferred to close a circuit of
high resistance at the beginning of the increase, and then successively close circuits
of gradually decreasing resistance, in the proper proportion, until the maximum
speed is reached, when the resistances are gradually increased as the speed runs
down.
In order to accomplish this, it is preferred to employ as resistances, a number of
incandescing electric lamps. One terminal of the multiple arc circuit from the
main line is connected with the circuit controlling arm worked by the eccentric,
while the other terminal is divided into a number of branches each running to a
contact point.
In each of these branches are placed one or more of the resistance
lamps, they being, if more than one is used, in multiple are relation to each other,
so that the branch containing most lamps is the one of least resistance.
The lamps are so arranged that at the first slight increase of speed, a circuit
containing only one lamp will be closed by the movement of the circuit con-
trolling arm, while as the speed increases, circuits containing two, three, or more
lamps, are successively closed; as the speed again declines circuits containing less
numbers of lamps are closed until near the end of the first revolution; during the
second revolution the decline in speed is so small and gradual that the generation
of current is practically unaffected by it.
It is preferred to use for opening and closing the multiple arc branches. a com-
mutator, which consists of a number of thin metal plates set near together but
separated by plates of insulation. Each metal plate is extended out beyond the
insulation, and bent so that the plates diverge into a fan shape. Wires connected
one to each plate, run to binding posts, from which the wires run which form the
circuits including the resistance lainps. A contact point placed at the extremity
of the circuit controlling arm, slides backward and forward over the edges of the
commutator plates, during each revolution of the valve shaft, and a thin metal
plate is so placed that it will lie between the contact point and the commutator
plates during that half of the revolution of the valve shaft during which no
explosion occurs, while during the rest of the revolution, the contact point will
pass under this plate, and be in contact with the edges of the commutator plates.
Thus when the explosion occurs the contact point passing over the edges of the
commutator plates will close the successive multiple arc branches, while when the
eccentric draws such point back it will be separated from the commutator plates
by the flat plate mentioned, and the said branches are not affected.
As stated it is preferable to vary the proportion of current supplied to the
translating devices gradually; such variations may however be effected all at once,
and this accomplishes the regulation in a very satisfactory manner, although not
so perfectly as that just described. In this case the arm attached to the eccentric
merely serves to close a circuit, which may be a multiple arc circuit of the desired
resistance, or may act as a shunt around a wire resistance in the main line. The
circuit controller may be a point dipping into a mercury cup, and withdrawn
therefrom as the arm is moved back and forth; or the circuit may be made and
broken at contact points in any ordinary manner.
With all these arrangements, means are provided for adjusting the position of
the eccentric so that it can be set to act at the proper point.
It is evident that the eccentric may be placed on the main shaft of the engine,
on the shaft of the armature or on any moving part of the apparatus, or on a
shaft connected with any moving part of the apparatus, proper adjustment of the
eccentric being made to insure its action at the proper point.
And in order that the said Invention may be perfectly understood I shall now
proceed more particularly to describe the same, and for that purpose shall refer to
the several figures on the accompanying sheets of drawings, the same letters of
reference indicating corresponding parts in all the figures.
t
Figure 1 (Sheet 1) of the accompanying drawings is a plan of a portion of a
gas engine, the generator driven thereby, and the compensating devices;

page_text: Figure 2 is a plan drawn to a larger scale of the eccentric on the valve shaft,
and the resistance commutator;
Figure 3, an elevation illustrating the devices for adjusting the eccentric;
Figure 4, a detail view in perspective of the resistance commutator;
Figure 5, a diagram illustrating the variation in speed of the gas engine, and
the times at which the resistance lamps should be placed in circuit: and
Figures 6, and 7 (Sheet 2) are diagrams illustrating other forms of the
Invention.
Referring to figures 1, to 5 (Sheet 1) of the drawings, A, represents a portion of
a gas engine, B, the main shaft of the same, and C, the shaft which operates the
valve, and is revolved from shaft B, by bevel gearing a, a, the shaft C, making
half as many revolutions as the shaft B. A belt D runs from the shaft B, to the
armature shaft E of a dynamo electric machine F. From the generator F main
conductors 1, 2, extend, across which translating devices y, y, are placed in
multiple arc circuits. Upon a sleeve G on the shaft C is mounted an eccentric H.
From the eccentric H runs a rod I, which terminates in a contact point b.
Upon a suitable insulating base J are supported edgewise and side by side, the
sories of thin metal plates c. c. separated by plates d, d, of mica or other insulating
material, the whole being supported and held together by an insulated bolt e,
passing through the plates and the standards K, K. Supported also from the
base J, is the flat spring L, which terminates in an inclined plane f, located
immediately above the edges of the commutator plates c, c. The rod I, which is
attached to the eccentric is connected with a rod M, and to the rod M is attached
at right angles the contact arm N, which terminates in a point b, resting on the
commutator plates c, c.
Each commutator plate extends out beyond the insulating plates, and is bent out
from the rest, the whole forming a fan shape and to each is attached a wire g,
passing under the base J, each wire g, being connected with one of the binding
posts h. The wire 3, of a multiple are circuit 3, 4, from the main conductors 1, 2
is connected to a binding post h', on the base J, from which a wire 5, runs to the
arm N. The wire 4, is divided into a number of branches as seen in figure 1, each
connected with one of the binding posts h. Each of these branches contains one
or more resistance lamps i, in multiple are relation to each other as shewn.
These devices operate in the following manner, the explosion occurring as stated,
once during each revolution of the valve shaft C.
The eccentric is so adjusted that at the time of the explosion the contact point 6,
is in the position shown in figures, 1, 2, and 4. The motion of the eccentric draws
the contact point along the plates c, c, under the piece f, making successive contacts,
and throwing into circuit first one, then two, three, and four lamps as the speed
increases and then gradually reducing the number as the speed declines. This is
clearly illustrated in figure 5, wherein the curve x, x, shows the increase and
decrease of speed during two revolutions of the main shaft and fly wheel, or one
revolution of the valve shaft: the dotted line a¹, x', showing the end of the first
revolution. The full vertical lines represent the points at which lamps are thrown
in, the figures showing the number of lamps at each point. The decline in speed
during the second revolution is so small and gradual that it is not necessary to
compensate for it. It is evident that the circuit 3, 4, may be divided into many
more parts, and lamps thrown in with much greater frequency; that more lamps
may be used if necessary at points of greatest speed; and that at points of
less speed where a high compensating resistance is desired in the circuit, higher
resistance lamps may be used, or two or more lamps in series may be thrown in.
During the second half of the revolution of the valve shaft, the contact point b,
slides forward but now passes over the inclined plane f, and is thus kept from
contact with the commutator plates. It then drops into the position shown in
figures, 1, 2, and 4, in time for the explosion.
The sleeve G which carries the eccentric H is made adjustable on the shaft C, by
means of a forked arm k, attached to the said sleeve, pivotted at 1, and moved by

page_text: screwing in and out the rod m; a pin 8, on the shaft working in a slot t, so that the
movement of the sleeve adjusts the eccentric; a pointer n, moving over a scale o,
is attached to the arm k, so as to admit of the position of the eccentric being
readily determined. This adjustment is desirable in order that the eccentric may
be made to act at precisely the proper points.
In figure 6 (Sheet 2.) a number of resistance lamps i, or other resistances, are in
multiple arc across the circuit 3, 4. The arm I, terminates in a contact point b,
which enters a mercury cup q, and completes the circuit 3, 4, at the moment when
the explosion occurs, thus throwing the lamps i, i, into circuit, and reducing the
proportion of current supplied to the translating devices y. y.
It is evident that the eccentric which moves the rod I, may be attached to any
revolving part of the apparatus.
In figure 7, the motion of the arm I, opens and closes circuit at r, thus throwing
a resistance R into the main circuit when the speed increases and closing a shunt
around the resistance when the speed diminishes
In figures 6, and 7 the eccentric is adjusted by means of a set screw u.
With both these forms, an adjustable resistance R*, shown in figure 1, should be
placed in the field circuit of the generator, to regulate the generation of current
according to variations in the number of translating devices in circuit, or other
suitable form of regulating device should be provided for this purpose.
Having now described and particularly ascertained the nature of the said
Invention, and the manner in which the same is or may be used or carried into
effect, I would observe in conclusion that what I consider to be novel and original,
and therefore claim as the Invention secured to me by the hereinbefore in part
recited Letters Patent is :-
First: The employment for compensating for irregularities in the speed of
a gas engine operating an electrical generator, of means substantially as
herein before described with reference to figures 1, 2, 3, 4, and 5, of the
accompanying drawings
Second: The employment for compensating for irregularities in the speed of a
gas engine, operating an electrical generator of means substantially as herein before
described with reference respectively to figures 6 and 7 of the accompanying
drawings.
In witness whereof I the said Thomas John Handford have hereunto set
my hand and seal this twenty second day of August in the year of our Lord one
thousand eight hundred and eighty three.
TH J HANDFORD (LS)