Improvements in Gas and Oil Motor Engines.
Year: 1890

page_text: Date of Application, 22nd Apr., 1890
Complete Specification Lelt, 24th Dec., 1890-Accepted, 24th Jan., 1891
PROVISIONAL SPECIFICATION.
Improvements in Gas and Oil Motor Engines.
I, Dr. NICOLAUS AUGUST OTTO, of Cologne, in the German Empire, Engineer, do
hereby declare the nature of this invention to be as follows:-
This invention relates to gas and oil motor engines working with a cycle of four
strokes, and has for its object to dispense with the countershaft driven at half the speed
of the engine-shaft, such as is usually employed with such engines for working the
valve and other gear.
For this purpose the valve for admitting the combustible mixture of gas and air
is made automatic, that is to say, it is held closed by a spring of such strength as to
allow the valve to be opened by the pressure of the atmosphere when the piston
performs its suction outstroke; the discharge valve on the other hand is opened at
the end of the working outstroke by an apparatus such as a small cylinder with
piston that is subject to the pressure existing in the engine cylinder towards the end
of the working stroke, and the valve is held open during the expelling stroke and, is
then made to close, either hy maintaining the pressure in the small cylinder during
that time, and then allowing such pressure to escape, or by providing a locking
device which holds the valve in the open position and which is afterwards made to
release the valve; or again the valve may be connected to a cataract or other similar
device which controls the motion of the valve so that it does not close before the end
of the working stroke. In combination with these arrangements I also employ
devices whereby, when the engine runs too fast, either the igniting device is
prevented from effecting the ignition of the explosive charge at the end of the
compression stroke, so that the charge is allowed to expand again during the
following outstroke, and is then again compressed, and so on, until the speed of
the engine is again reduced to the normal. Or I actuate the locking device of the
discharge valve, by means of a reciprocating rod which frees the valve from the
locking device at the end of each expelling stroke, when the engine is running at
normal speed, but which is acted upon by a governor, so as to prevent it from
freeing the valve when the engine is running too fast, in which case the discharge
valve remains open during the following suction stroke and thus causes the expelled
combustion gases to be drawn back into the cylinder and be expelled again, until
the speed of the engine is reduced.
In carrying out the above described modes of operating 1, according to one arrange
ment, connect the before mentioned small cylinder and piston, or it might be a vessel
with flexible diaphragm, by a pipe or passage with a point of the engine cylinder,
which is just uncovered by the engine piston when this arrives at the end of its out-
stroke, so that when over-pressure exists in the cylinder at the end of the working
outstroke, such pressure will move the piston outwards against the action of a spring
or weight, and cause it to open the discharge valve, either by direct connection with
its stem or through the medium of a lever. As soon as the piston commences its
return stroke it closes the communication with the small cylinder, so that the pressure
is retained in this, causing the piston to keep the discharge valve open until near the
end of the expelling stroke, when a cavity in the engine piston is made to establish
a communication, between the passage leading to the small cylinder, and a passage
leading to the atmosphere, so that the pressure in the small cylinder will then
escape, and the discharge valve will close. Instead of establishing and closing the
communication between the engine cylinder and small cylinder by the engine piston
as described, this may be effected by a slide actuated by a crank or cam on the
engine shaft. With the above described arrangement may be employed an electric
igniting device the circuit of which is closed at the proper times by a revolving

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contact on the engine shaft and a stationary contact controlled by a governor so that
when the engine runs too fast, the governor raises the stationary contact from the
revolving contact, and thus, in breaking the circuit, prevents the compressed charge
in the cylinder from being ignited, whereupon the above described action of alternately
compressing and expanding one and the same charge, until the speed is sufficiently
reduced will take place.
According to another arrangement, where the small cylinder and piston act upon
the discharge valve through a lever, a spring catch is made to engage with and hold
this lever, when the valve is in the open position until the end of the expelling
stroke, when the catch is acted upon by a reciprocating rod from a crank, cam, or
eccentric on the engine shaft, so as to release the lever and allow the escape valve to
close, the lever being either acted upon by a spring or by gear on the engine shaft for
effecting the closing movement. The reciprocating rod is connected to a governor
which, when the engine runs too fast, moves the rod so as to prevent it from acting
on the catch, thus preventing the discharge valve from closing and causing the
combustion gases to be drawn back again at the following suction stroke.
With this arrangement, the rod of the small piston may be connected to a slide on
the gas supply valve, so arranged that when the small piston is moved so as to open
the discharge valve, the slide is made to cut off the gas supply.
The ignition of the charges may in this case be effected by a continuously heated
tube of well known arrangement.
Instead of the above described arrangement for keeping the discharge valve open
for a certain time, any device similar to a cataract may be employed, such as:
providing the small cylinder with an escape pipe of such small diameter, that after
the gases under pressure from the engine cylinder have moved the piston outwards,
they escape very slowly through such escape pipe, and thus only allow the complete
closing of the discharge valve to take place at the end of the expelling stroke.
Dated this 22nd day of April 1890.
ABEL & IMRAY,
Agents for the Applicant.
COMPLETE SPECIFICATION.
Improvements in Gas and Oil Motor Engines.
I, Dr. NICOLAUS AUGUST OTTO, of Cologne, in the German Empire, 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:
This invention relates to gas and oil motor engines working with a cycle of four
strokes, and has for its object to dispense with the countershaft driven at half the speed
of the engine shaft such as is usually employed with such engines for working the
valve and other gear.
For this purpose the valve for admitting the combustible mixture of gas and air is
made automatic, that is to say, it is held closed by a spring of such strength as to
allow the valve to be opened by the pressure of the atmosphere when the piston
performs its suction outstroke the discharge valve on the other hand is opened at he
end of the working outstroke by an apparatus such as a small cylinder with piston that
is subject to the pressure existing in the engine cylinder towards the end of the
working stroke, and tho valve is held open during the expelling stroke and is then
made to close, either by maintaining the pressure in the small cylinder during that
time, and then allowing such pressure to escape, or by providing a locking device
which holds the valve in the open position and which is afterwards made to release the
valve or again, the valve may be connected to a cataract or other similar device
which controls the motion of the valve so that it does not close before the end of the
working stroke. In combination with these arrangements I also employ devices
whereby, when the engine runs too fast, either the igniting device is controlled so as
to prevent the ignition of the explosive charge at the end of the compression stroke,

page_text: so that the charge is allowed to expand again during the following outstroke, and is
then again compressed, and so on, until the speed of the engine is again reduced to
the normal.
Or actuate the locking device of the discharge valve by means of a reciprocating
rol which frees the valve from the locking device at the end of each expelling stroke,
when the engine is running at normal speed, but which is acted upon by a governor
so as to prevent it from freeing the valve when the engine is running too fast, in
which case the discharge valve remains open during the following suction stroke, and
thus causes the expelled combustion gases to be drawn back into the cylinder and
expelled again, until the speed of the engine is reduced.
Fig. 1 of the accompanying drawings shews a side view partly in section of a gas
motor engine with one arrangement of my invention applied thereto. Fig. 2 shews a
part section of the cylinder, with the piston in a different position. Fig. 5 shews a
diagram of the action of the engine.
A small cylinder communicates by a pipe with the engine cylinder at a point
which is uncovered by the piston e when this arrives at the end of its outstroke, as
shewn in Fig. 1. A second passage & communicates with the atmosphere or exhaust,
and when the piston arrives at the end of its instroke, a cavity formed therein,
establishes a communication between i and k, and consequently between the cylinder h
and the atmosphere. The cylinder / contains a piston m which is pressed inwards by
a spring t and which is connected by a rod to a double ended lever the other end
of which acts on the stem of the discharge valve at f.
In the cylinder head is situated the gas and air admission valve n of known
construction as shown in section at Fig. 3 which opens automatically against the action
of a spring when the engine piston is performing its suction stroke, so as to admit a
charge of explosive mixture.
Fig. 3 shews a part sectional elevation of a modification in which the piston mis
connected directly with the discharge valve stem, the communication between the
cylinder and the engine cylinder being effected by the pipe i, and the piston m being
pressed inwards by a spring t as before.
In both the above arrangements, when, at the end of the working outstroke, the
piston e uncovers the passage i, the pressure existing in the cylinder is transmitted
through passage i to the cylinder h, thereby forcing piston moutward against the
action of the springs t, and moving lever 7 so as to open the discharge valve.
As soon as the piston e commences its expelling instroke, it closes the opening of
the passage, thus confining the gases under pressure in cylinder h, and consequently
keeping the piston m, lever and valve in the open position until at the end of the
instroke the cavity puts in communication with k, whereupon the pressure will
escape from h, allowing the springs to move the piston m and lever back into their
original position, and to close the discharge valve.
In the diagram at Fig. 5 the part of the circle between a and b indicates the time
during which the passage i remains uncovered by the piston e at the end of the out-
strokes and the part between c and d the time during which the passage is put in
communication with the exhaust & by the cavity g at the end of the instrokes.
In the modified arrangement shewn at Fig. 4, the return motion of the piston m,
lever and valve is prevented by a catch acted upon by a spring y so as to cause
it to catch on to the tail of lever when this has been moved so as to open the
discharge valve, and to hold the same in this position until the catch is acted upon by
a reciprocating rod u receiving motion from a crank or cam on the engine shaft, and
is thereby made to release lever so as to allow the discharge valve to be closed by
springs t.
The rod of piston m is in this case also made to actuate a piston slide X on the gas
supply pipe G, so as to cut off the gas supply while the discharge valve is open.
For igniting the explosive charges, an electrical igniting apparatus is shewn in
Figs. 1 and 3, the circuit of which is broken or closed by the action of a governor
according as the engine is running too fast, or at ordinary speed. The two poles are
fixed in an insulated manner opposite each other in a tube Z so that a spark passing

page_text: from the one to the other will ignite a charge after this has been compressed by the
compressing stroke. The spark will also pass at the commencement of the suction
stroke, but as the tube Z will then be filled with products of the previous combustion,
no ignition will occur.
The working of the engine arranged as at Figs. 1, 2 and 3 will take place as
follows:-
At the suction stroke of piston e, explosive mixture will be drawn into the cylinder
through the automatic mixing admission valve ; this will be compressed at the
return stroke, and will be fired by the igniter Z when the piston has arrived at the
dead centre at or about the completion of the ensuing working outstroke (at
point a in diagram Fig. 5) the piston will uncover the passage i so that the pressure
existing in the cylinder will be transmitted to cylinder, thereby effecting the
opening of the discharge valve as before described, the parts being kept in this
position during the expelling instroke by the closing of the passage i by piston e,
until the cavity y establishes a communication between i and k, at the end of the
stroke, and thus allows the discharge valve to close.
A fresh charge is then drawn in by the following outstroke.
is
p is a revolving contact piece on an insulating ring o on the engine shaft, and
a stationary contact spring by which the igniting circuit is closed once in every
revolution, which spring is connected by a lever to the sleeve of the governor "; on
the engine running too fast, the governor will raise q so that it cannot make contact
with P₂ and consequently there will be no electric spark in the tube Z at the time
when the charge in the cylinder has been compressel; consequently the said charge
will continue to be alternately expanded and compressed by the motion of the piston,
until the speed of the engine has become sufficiently reduced to cause the governor
to allow to make contact with p again at the end of a compressing stroke so that
the charge will then be fired.
With the arrangement at Fig. 4. where, as before described, the catch is made to
hold the discharge, valve open until it is acted upon by the rod u, the regulation is
effected by connecting the rod u to the sleeve of the governor ", so that when the
engine runs too fast, the governor draws u to one side and prevents it from acting
on v, so that it continues to hold the discharge valve open, and the gas slide closed,
and causes the combustion gases to be alternately drawn into the cylinder again and
expelled therefrom.until the speed of the engine is reduced to the normal again,
whereupon the rod u will again act on e, causing the discharge valve to close, and
the
gas slide X to open so as to admit a fresh combustible charge into the cylinder.
The igniting device in Fig. 4 is shewn as an externally heated tube of known
arrangement, but any other mode of ignition may be employed.
If it be desired with this construction to regulate the engine by alternately
compressing and expanding a confined and unignited explosive charge as at ffig. 1,
this can be effected by arranging the igniting device to be acted upon by the
governor so as to prevent it from acting when the engine runs too fast, the described
action of the governor on the discharge valve being done away with.
The communication between the cylinder and the interior of the working cylinder
on the one hand, and the atmosphere on the other hand, through passage i, instead of
being effected by the piston e as described might also be effected by separate slide or
other device actuated by an eccentric or cam on the engine shaft; also, instead of
the locking arrangement shewn at Fig. 4, any other locking device or cataract
motion might be employed whereby the piston h is held in the outward position
during the expelling stroke and is then allowed to move back.
Thus, the cylinder might be closed at its front end and made to communicate
through an opening governed by a slide either with the atmosphere or with a closed
chamber, so that when the piston is forced forward by the pressure, in the engine
cylinder, it expels air or liquid from the front end of the cylinder through the slide
into the chamber, and the slide being then moved so as to prevent the air or liquid
from passing back again, the piston will be prevented from moving inwards. until
the slide is a gain moved so as to allow the air or liquid to pass back again. Or the

page_text: small cylinder might be provided at the end where it receives the gases under
pressure, with a very small opening, through which such gases are permitted to
escape very slowly, so that the piston m will not permit the discharge valve to close
completely until the end of the expelling stroke.
Or again, in the arrangement described with reference to Fig. 1, the cavity g and
escape passage & might be dispensed with by providing the pipe or passage communi-
cating with the discharge valve with a check valve closed by a spring and opening
in the contrary direction to f when the combustion gases are being expelled, so that
such check valve will close at the commencement of the suction stroke, and will allow
of the discharge valve being kept open by the piston m until the piston e uncovers
the passage again during the suction stroke, and thus allow the pressure in h to
escape back into the engine cylinder.
i
Instead of effecting the return motion of the piston m, lever I and valve f by means
of springs t. such motion can be effected by suitable lever gear actuated by an
eccentric or cam on the engine shaft.
For starting the engine, the cylinder is provided with an escape pipe having a
cock H through which a portion of the combustible charge drawn in is allowed to
escape again during the return motion, until the proper proportions of gas and air
have been attained for producing the ignition of the charge.
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:-
1. For effecting the opening and closing of the discharge valve of a four-stroke-
cycle gas or oil motor engine, a small cylinder or chamber provided with a piston or
diaphragm connected to the discharge valve and made to communicate with the
engine cylinder at the end of the working stroke, so as to be then acted upon by
the combustion gases in the cylinder, in combination with means for confining the
said gases in the small cylinder or chamber till the end of the working stroke, and
for then allowing them to escape into the atmosphere, substantially as described.
2. For effecting the opening and closing of the discharge valve of a four stroke
cycle gas or oil motor engine, a small cylinder or chamber provided with a piston or
diaphragm connected to the discharge valve and made to communicate with the
engine cylinder at the end of the working stroke, so as to be then acted upon by the
combustion gases in the cylinder and be thereby made to open the discharge valve,
in combination with locking gear which holds the discharge valve open during the
expelling stroke and is then made to release the valve by means of a
actuated by the engine shaft substantially as described.
Dated this 23rd day of December 1890.
releasing device
ABEL & IMRAY,
Agents.