Year: 1886

page_text: I ARTHUR ROLLASON of 5 Maddox Street London in the county of Middlesex,
Engineer do hereby declare the nature of my invention and in what manner the
same is to be performed to be particularly described and ascertained in and by
the following statement :-
My invention relates to Gas Engines in which a combustible mixture of gas and
air is compressed in a chamber in connection with the cylinder, prior to ignition
in such chamber. The object of my invention is to utilize as far as possible the
energy developed by the ignition of the mixture. In all heat engines a certain loss
of heat is unavoidable, for instance, some heat escapes through the walls of the
working cylinder and some is lost in the exhaust. Moreover the temperature
produced in the cylinder of the gas engine is so high that the working of the
piston in the cylinder would rapidly abrade or destroy the wearing surfaces, if
special means were not provided for keeping such surfaces at a sufficiently low
temperature. Such special means usually consist of a water jacket which is
made to surround not only the wearing surfaces but also the ignition chamber, and
a further loss of heat is thus necessarily involved.
In the Otto Gas Engine a further large amount of energy is wasted by reason
that the combustion is not complete until nearly the end of the stroke, and indeed
in some cases the charge is exhausted before the complete combustion has been
effected. The result of this is that the full advantages of the expansive principle
of working are not obtained. Moreover in the Otto Engine when the speed of
working goes beyond a certain point premature explosions are produced, and the
rapidity which is essential for getting the best results in gas engines cannot be
obtained.
In the Lenoir Engine the combustion of the explosive charge is practically
complete at the moment of ignition, so that if the stroke is sufficiently long the
full expansion of the exploded charge is obtained and the economy which results
from expansive working is gained. But in this Engine there is the accompanying
disadvantage that the high initial temperature produced by the complete initial
combustion causes a considerably increased loss of heat by conduction from the
highly heated exploded charge through the walls of the cylinder at or about
the moment of explosion, and before expansion and the consequent reduction
of temperature have taken place. Moreover in the Lenoir Engine a considerable

page_text: hock is produced due to the fact that the piston just before the explosion is
drawing in gases and being pulled by the crank pin, whereas the explosion projects
the piston forward so as to make it push the crank pin so that the effect of the
explosion where there is (as their necessarily must be) a slight amount of play in
the brasses, is to produce a violent shock which damages the engine.
In the economical working of gas engines a further point to be kept in view
is to utilize as far as possible the waste heat of the exhaust. In the Otto Gas
Engine this is done by retaining a portion of the heated products of combustion of
a previous charge and mixing them with the fresh charge thereby utilizing a certain
amount of heat. This arrangement however presents many practical disadvantages.
In the arrangement which is the subject of my invention I endeavour to obviate
the disadvantages of existing gus engines before referred to and to carry out the
following principles the importance of which has been demonstrated by experience.
1. To obtain the most economical results in Gas Engines it is necessary that the
heated gases should be in contact with the walls of the cylinder for as short a
time as possible so as to minimise the loss of heat by conduction through the walls
and hence it follows that the greater the piston speed of the Engine, the less will
be the loss through the cylinder walls in proportion to the power developed.
2. In order to obtain rapid working it is necessary to provide against premature
explosions of the compressed charge.
3. In order to obtain the advantages of rapid working without loss in other
directions it is necessary that the combustion of the charge should be complete, as
near the commencement of the stroke as possible in order that the full advantages
of expansive working may be obtained.
4. In order to work economically with an explosive charge it is necessary to
provide against the excessive loss of heat which would arise from the very high
initial temperature of the exploded charge in engines of the ordinary construction.
5. To obtain further economy the regenerative principle of working should be
adopted as far as practicable in order to economise some of the waste heat of the
Engine.
6. In applying the regenerative increment of heat to the incoming charge it is
important to add this increment as far as possible after compression.
I do not claim for these principles any novelty except as hereinafter appears.
But whereas in prior Engines, as before indicated, economy is sacrificed in one
direction in order to obtain it in another, I endeavour by my arrangement to
obtain economy in every direction without the countervailing disadvantages which
have been hereinbefore referred to by way of illustration as existing in the Otto
and Lenoir engines.
I employ a cylinder which has a chamber for compression and ignition of the
combustible charge in connection therewith forming a prolongation of the cylinder
beyond the extreme point to which the stroke of the piston reaches.
1 provide means whereby the temperature of this chamber may be maintained
at as high a point as practicable, whilst the wearing surface of the cylinder is
kept cool in the usual manner. To guard against premature and accidental
explosions and to keep the temperature of the chamber within proper limits,
I adopt the method first indicated in the Specification of C. W. Siemens N° 2074,
of the year 1860 of introducing a cooling charge into the cylinder, and expelling it
prior to the introduction of the explosive charge, I surround the walls of the
compression or ignition chamber with an air space lining or lagging so that the
heat communicated to such walls may be retained as far as possible in such walls
instead of being conducted away. I employ an explosive charge the combustion of
which is practically complete at the moment of ignition. This caloric insulation
of the compression and ignition chamber serves a two fold purpose, By preventing
the escape of heat as far as possible from the walls of the ignition chamber
I obviate the great loss of heat at the moment of ignition which is serious in the
Lenoir Engine. Moreover by retaining heat in the walls of this chamber I heat
the incoming charge regeneratively in the manner hereinafter described.

page_text: LOU
complete in three revolutions of the crank shaft. Starting from the phase or
cycle in which the piston has completed a stroke and has behind it a compressed
charge ready for ignition, the operations of the engine take place in the following
order:
1. Explosion of the charge & consequent outstroke of the piston.
2. Instroke of piston expelling products of combustion.
3. Outstroke of the piston taking in a cooling charge of atmospheric air.
4. Instroke of piston expelling cooling charge.
5. Outstroke of the piston taking in explosive mixture.
6. Instroke of the piston compressing explosive mixture.
If the insulated compression and ignition chamber hereinbefore referred to were
used with a two revolution cycle engine without the introduction of a cooling
charge it would be found that the heating of the charge due to the combined effect
of compression and the regenerative action of the lining of the compression chamber
would often fire the charge before the proper time. The introduction of a cooling
charge is therefore necessary in order to prevent this result, but I wish it to be
understood that I am aware that the use of the cycle of operations above described
in a gas engine is not new.
Commencing with the first of the six divisions of the cycle of operations, the
ignition of the compressed charge causes it to explode at once thereby producing
a very high degree of pressure and temperature. The heated gases however being
in contact during the commencement of the stroke chiefly with the walls of the
insulated ignition chamber, the loss of heat from the high initial temperature is
small, as compared with the Lenoir Engine. The piston moves forward under the
influence of the pressure, and by the time that the ignited gases come into contact
with the cooler parts of the cylinder a considerable amount of expansion and
consequent reduction of temperature have taken place. The piston completes its
stroke under the influence of the pressure of the ignited charge, expansion being
carried out as far as possible. Upon the return stroke of the piston the products
of combustion are expelled. Upon the next outstroke of the piston the charge of
cool air is drawn into the cylinder and the greater part thereof is expelled by the
next instroke of the piston. The condition of the cylinder is now as follows:-
The portion of the cylinder swept out by the piston is comparatively cool, but
the lining of the compression chamber is still highly heated and is in contact with
the remaining portion of the cooler air which has been drawn in as before
inentioned. Upon the next outstroke of the piston the explosive charge flows in
following the outward movement of the piston. It does not however immediately
come into contact with the heated lining of the compression chamber, but passes in
a stream, as indicated in dotted lines in the Figure, through the body of cooler air
which at the commencement of this outstroke fills the compression chamber.
The incoming charge comes first into contact with the working surfaces of
the cylinder, which being kept comparatively cool by the water jacket heat the
incoming charge but slightly. During the return instroke of the piston the
explosive charge is compressed but the heating effect of the lining of the compression
chamber upon the explosive charge does not take effect greatly until the instroke
of the piston is nearly completed. By this arrangement it will be seen that the
increment of heat which is added to the compressed charge is chiefly given not at
the commencement of the instroke of the piston and before compression as in the
Otto Engine, but when the compression is nearly completed, whence results a
considerable economy in working.
With the above arrangement I am enabled to work the engine more rapidly
than can be done with existing forms of gas engines, with certainty of ignition,
without risk of premature or accidental explosions, with the full advantage of
complete expansion of the ignited charge, and with the saving effect due to the
regenerative action which is involved in the arrangement, and to the economy of

page_text: heat which takes place at or about the time of ignition. Moreover the arrangement
is such that, although an explosive charge is used, there is an absence of shock
or noise.
In the drawing accompanying this specification the arrangement of parts of an
engine constructed to accomplish the objects of my invention and in accordance
therewith, is shown. The figure is a sectional plan.
A is a working cylinder surrounded with water jacket a, and having a piston B,
connected by piston rod 6 to crank C of crank shaft c, upon which
wheel D. A is the space or chamber wherein combustion of the charge takes
keyed a fly
place and as shown in the drawing is surrounded by an air space a. E is a
gearing wheel keyed on c which works by a worm or gearing the countershaft H
revolving in suitable bearings, once for three revolutions of the fly wheel shaft.
The other end of H is provided with a crank which is connected with and works
the slide F by rod f, and second admission slide I by a cam or eccentric and rod h.
The slide F and admission slide I are of any suitable known form: L is the
admission port to A¹ and A, and G is the exhaust port.
The above described arrangement shows one practical method of carrying out
my invention.
The air space may be filled if desired with slag wool, or other suitable non-
conductor of heat. Instead of an air space the chamber may be lined with
porcelain or enamel or other suitable non-conductor of heat, or may be lagged
externally. The airspace lining or lagging may extend round the back of the
combustion chamber, but the wearing surfaces of the slides should be kept cool by
water circulation as usual.
Where an arrangement of engine with two pistons working in opposite directions
in same cylinder is used the air space lining or lagging should extend round the
ignition chamber which would in this case be between the two pistons.
Having now particularly described and ascertained the nature of my said
invention, and in what manner the same is to be performed I declare that what
I claim is :-
1.) A Gas Engine arranged to utilize heat generated by a prior explosion in
order to raise the temperature of a subsequent charge in the manner herein before
described.
2.) A Gas Engine arranged to prevent the loss of heat at or about the moment
of the explosion of the charge in the manner herein before described.
3.) A three cycle Gas Engine provided with means for maintaining the
temperature of the walls of the compression and ignition chamber substantially as
hereinbefore described.
4.) A Gas Engine having a cylinder provided throughout the portion in which
the piston works with a water jacket, and having a compression and ignition space
provided with means for maintaining the temperature of the walls thereof, the
engine being arranged so as to draw in and expol a cooling charge, and then to
draw in and compress an explosive charge the combustion of which is practically
complete at the moment of ignition, substantially as herein before described.
5.) A Gas Engine having an air space or lining or lagging surrounding the
compression and ignition chamber as herein before described.
Dated this Second day of June 1886.
J. C. CHAPMAN,
Agent for Applicant.