Year: 1886

page_text: Date of Application, 29th Sept., 1885.
Complete Left, 22nd Apr., 1887.
Complete Accepted, 24th May, 1887.
I ARTHUR ROLLASON of 53 Queen Victoria Street, London in the County of
Middlesex, Engineer do hereby declare the nature of this invention to be as follows:-
This invention relates to certain improvements in gas or vapour engines similar
in construction to the engine described in the specification of my Letters Patent
No. 7427 of A.D. 1886.
The present improvements are applicable to gas or vapour engines whether the
cylinder and combustion chamber are water jacketed or otherwise.
According to the present improvements:
:
Firstly I construct and arrange the slide so that the effective area of the admission
port may vary in proportion to the speed of the piston throughout the stroke and
thereby admit to the cylinder containing a body of atmospheric air a mixture of
combustible gas or vapour combined with air, the air contained in the entire mixture
being considerably in excess of the quantity actually required for its complete
combustion when ignited; also I form the admission orifice with parallel sides by
which combined construction the agitation produced by the velocity of the incoming
mixture into a cylinder swept out by. a previous cooling charge causes the atoms
composing it to become so intimately mixed and incorporated that upon ignition the
most rapid explosion is produced and a greater quantity of heat is liberated, thus
obtaining the best expansive results from the combustion of the gascous charge.
Secondly I admit the said incoming charge into the cylinder in such order of
composition that on the completion of the back or compression stroke of the piston
and at the moment of ignition the weaker or weakest part of the compound is located
next to the firing port and the richer part next the piston. I find that the combination
of port and slide such as is hereinbefore indicated is a good method of effecting this
arrangement of charge.
Thirdly I provide means of regulating the gas consumption in exact proportion
to the work being done by the engine, by arranging the governor to work a separate
gas slide so as to cut off automatically the gas admission at any point of the stroke,
corresponding to the work required and the speed of the engine.
Dated this Twenty-ninth day of September 1886.
J. C. CHAPMAN,
70, Chancery Lane, W.C.,
Agent for Applicant,

page_text: I ARTHUR ROLLASON of 53 Queen Victoria Street, London in the County of
Middlesex, 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 certain improvements in gas or vapour engines of the type
described in the specification of my Letters Patent No. 7427, A.D. 1886.
The present improvements are applicable to gas or vapour engines whether the
cylinder or combustion chambers are water jacketed or otherwise..
In my said former specification I have shown that it is important in gas engines to
work with a rapidly burning charge in contra-distinction to a charge such as that
used in the "Otto" engine in which the combustion is not completed until nearly tho
end of the stroke.
The object of my former invention was to make provision for the use of such a
rapidly burning or explosive charge.
In my subsequent experiments I have found it to be advantageous whilst using a
charge of such a character, to increase the explosive action thereof so as to ensure
perfect combustion of the gases. In order to effect this result in a practical and
efficient manner I arrange the charge in such a manner that at the moment of ignition
the weaker or weakest part of the combustible mixture is located next to the firing
point and the richer part next to the piston. The combustion then takes place with
increasing velocity due to and in direct proportion to this order of stratification of
the gases, and the combustion is complete, whereas if the richer portion lay next the
firing point and were ignited first as is usually the case it would sometimes happen
that that portion which is weakest in explosive character being located further away
from the point of ignition would not be completely burned at the time of exhaust and
waste of combustible mixture would ensue.
I have also found it to be desirable to make provision for the thorough and intimate
mixture and incorporation of the gas and air in the charge so that as far as possible
every small portion of gas shall find in its neighbourhood the requisite quantity of
air for this combustion. With such an arrangement I am enabled to ignite a more
dilute charge than has hitherto been practically used. I find that the arrangement
hereinafter described secures also this result in an efficient manner.
In carrying my invention into practise I use a central port for the admission of gas
and air at the rear of the combustion chamber, similar to that shown in my former
specification and having parallel sides.
In order to produce the required stratification of the charge, above indicated, I provide
that the effective area of the passage through which the mixture passes to the admission
port, shall be varied throughout the stroke in proportion to the speed of the piston. In
the arrangement hereinafter described with reference to the drawings this variation of

page_text: the area of the passage is secured. The result of this arrangement is that the incoming
charge passes in an almost unbroken stream through the volume of pure air which at
the beginning of the outward stroke of the piston occupies the combustion chamber,
and follows the piston along during its stroke, this stream on reaching the piston being
turned by it and flowing back along the walls of the cylinder until a portion of it
eddies into and mixes with the volume of pure air at the rear end of the chamber.
Upon the return stroke of the piston there will be an undiluted mixture next to the
piston, whereas the portion of the mixture at the back of the combustion chamber is
diluted by the air which originally filled the combustion chamber. I find that this
method of admission secures the result of intimately mixing and incorporating the
combustible mixture. The effect of this is that the explosive power of such mixture
is considerably increased and this result has a considerable value independently of the
peculiar stratification which I have hereinbefore described.
I find that when the combustible mixture is admitted into the cylinder which has
been cleared of the products of combustion by a previous scavenger charge, and when
there is an intimate incorporation of the gas and air in the mixture I am able to ignite
and completely burn a much more diluted charge than has hitherto been found to be
practicable in gas engines. Hence to regulate the speed of the engine I am able to
make use of a governor which varies the quantity of gas admitted at each stroke.
Heretofore in the regulation of gas engines it has been found necessary that the
governor should operate either by completely cutting off the gas supply, or by leaving
it full on; it has hitherto been found to be impracticable to admit a diminished supply
of gas so as to have a more or less dilute mixture, as in such case the combustible
mixture would often be too weak to be ignited and burned under the old arrangement.
But with my improved arrangement I provide a separate gas slide which is worked
by the governor, so as to diminish the gas supply as required in order to produce
uniformity of speed.
In the accompanying drawings,
Figure 1 is a plan of engine partly in section with exhaust valve, governor, and
part of the gas regulating slide lever removed.
Figure 2 is an elevation partly in section.
Figure 3 is a back end elevation of cylinder with slide cover removed, and showing
slide and working parts connected therewith in position for ignition, showing also
governor and gas regulating slide.
Figure 3 is an alternative arrangement of electric governor.
Figure 4 is an elevation of slide cover showing gas valve partly in section.
Figure 5 is a horizontal section on line a b figure 3 with slide cover attached; and
Figure 5 is a part of same view showing an alternative arrangement of gas regulating
slide.
Figure 6 is a vertical section on line c d figure 3 showing slide moved into position
to take in the charge.
Figure 7 is a cross section on line e, f, figure 3 showing gas valve and regulating
slide.
Figuro 8 shows one method of operating the gas valve.
Figures 9 and 10 are vertical sections through exhaust valve showing means of
operating same.
Figure 11 is a part vertical section through combustion chamber showing air and
water spaces; and Figures 12 and 13 are diagrains hereinafter referred to.
In all of these figures the parts are shown in a position just previous to ignition and
similar letters of reference designate corresponding parts.
A is the working cylinder surrounded with a water jacket a and fitted with a
piston B connected by a rod b to crank C of crankshaft c upon which is keyed a fly
wheel e¹ and driving pulley all arranged in the usual manner.
A' is the combustion
chamber in connection with the working cylinder A; it is also surrounded by the
water jacket a and. the second space a² open to the atmosphere, which space may be
if desired filled with slag wool or other suitable non-conductor of heat whereby the
temperature of the chamber A¹ is maintained at as high a point as practicable and

page_text: loss of heat reduced to a minimum in the manner and for the purposes more particularly
set forth in the specification of my Letters Patent No. 7427 A.D. 1886. is a worm
or bevel wheel fast on the crank shaft gearing with a second wheel ' on the counter-
shaft D revolving in suitable bearings in the proportion of three to one, so that the
shaft D revolves once for every three revolutions of the crank shaft; on the other end
of the counter shaft D, a crank E is fixed and connected by rode to the lever e¹
centred at e connected to the slide F working between the face F' and the cover F.
The crank E is preferably a disc crank and carries on its periphery a came which at
each revolution engages with a roller upon a bent lever et suitably centred at eand
lifts the gas admission valve G in the slide cover F2 against the action of a spring g' ;
the figure of the cam e³ is such that the lift of the valve and area of port is varied
throughout the stroke in exact proportion to the varying velocity of the piston. The
passage from the valve as shown dotted in figures 4 and 5 preferably terminates on
the inner face of the cover in a suitable number of apertures g³, gª.
Upon the counter shaft D is also fixed a bevel wheel H gearing with a pinion /
working a governor which may be of any suitable centrifugal type: Or the governor
may be actuated by an electric current as shown in figure 3 wherein h is an armature
working with a solenoid connected in the usual way with any convenient generator.
The collar 2 of governor ¹, or the armature 5 of solenoid o, is connected with the
end of a bell crank lever 3 centred at and actuating a grid slide i working in any
suitable position on the outer or admission side of the gas valve G regulating the
supply of gas through pipe I, upon which is provided the usual stop cock. Or by
another arrangement a slide provided with one aperture may be fitted and
connected with the governor to work across the gas admission port g on the inner
face of the slide cover F2 as hereinafter more particularly set forth. J is the air
admission port, K is the master light, and the gas supply to same, k¹ is the gas
supply to the travelling light by means of groove 2 on inner surface of the slide
cover F2.
Figure 6 shows the passage L and ports with air passage o forming the connection
between the master and travelling lights, whereby the gas supply to the travelling
light is ignited, and the flame subsequently as shown dotted projected by the pressure
of the compression into the ignition orifice, as hereinafter described. M is the
admission and firing port having its sides parallel: N is the exhaust port in which is
fitted the valve n actuated at the proper times by a double cam as hereinafer
described. A port M is formed in the slide F as shown best in figures 5 and 5",
having three ways, the first controlling the gas supply 2, the second j controlling
the air supply J, and the third m controlling the admission port M. The engine
illustrated is a three cycle engine such as is described in the specification of my
Letters Patent before referred to.
The operation of the engine is as follows:
Commencing at the ignition of the compressed charge: The piston moves forward
and completes its stroke under the 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 cam n¹ raises the exhaust valve and the products of combustion are expelled
through port N. Upon the next outstroke of the piston the slide moves so as to open
the air port J, all other ports remaining closed, and the charge of cool air is drawn
into the cylinder and passes through the centre of the products of combustion left
in A in a stream until it meets the back of the piston, when it branches off as shown
diagrammatically by dotted lines in figure 12, the portion which has first entered
returning to the combustion chamber leaving the portion that lias entered last next
the piston and the greater part thereof together with the remaining products of
combustion is expelled by the next instroke of the piston through exhaust port N as
before described. Upon the next outstroke of the piston, the slide F is moved until
the ways m, g and j of slide port M³ coincide with the admission, gas, and air
inlets M, and J, and the explosive charge flows in following the outward movement
of the piston. At the same time the travelling light port L with its passages I assumes
the position shown in figure 6, and the gas supply k¹ to the travelling light passing

page_text: gas
along the groove on the inner face of the cover F3 is re-ignited ready to fire the
mixture as hereinafter shown.
The incoming charge becomes greatly diffused and the particles of combustible
or vapour become mechanically mixed and brought into more intimate and effective
contact with the particles of the air thus rendering the whole mixture of a much
more explosive nature: The first portion of the combustible gases taken in 'mixing
with the air in front becomes diluted and returns as described to the back of tho
chamber A and surrounds the firing port M, while the portion taken in last flows to
and remains behind the back of the piston: In this order, that is to say, the weaker
part of the mixture being next the firing port, while the richer part is next the piston
as shown diagrammatically in figure 13, the whole charge is compressed in the
chamber A: The slide is now moved from the position shown in the figures making
the connection shown dotted in figure 6, when the back pressure of the compressed
charge forces the flame down through passage through ports L and o; at this
moment the passage i opens into M, and the flame being simultaneously projected
into the combustion chamber the weaker part of the explosive mixture is ignited and
burns with great rapidity, the velocity of the combustion increasing proportionally
as it approaches the richest part of the charge, and the piston travels forward with
great velocity, the shock which would otherwise be caused by firing into the richest
part of the mixture is thus avoided.
The action of the governor is as follows:-
23
When the work is reduced the excess speed or increased electric current as the case
may be raising the governor and collar or armature ³, causes the bell crank lever
to withdraw the grid slide i: The apertures formed in this grid slide normally coincide
with the aperture of the gas supply pipe I and on the slide being with drawn as
described the solid end part of the slide comes partly over the supply pipe I, thus
varying and regulating the gas consumption at any period of the stroke in exact
proportion to the work being done by the engine. In the arrangement shown in
figure 5 the slide with its apertures ³ (normally coinciding with the gas port g³)
is controlled and actuated by the governor in an inward direction. The gas port g³
and slide port g as shown in figure 5 are in this case reversed, g³ being rectangular
and a series of apertures similar to those shown at 93 figure 4. The excess speed
of the engine due to the reduction of work raises the collar of the governor and by a
suitable compound lever, pushes the slide inward reducing the area of the gas port o³
The period at and during which the charge of gas is drawn in through admission
port M and port M' is delayed and diminished, and the richness of the explosive
charge thereby reduced.
:
Having now particularly described and. ascertained the nature of this invention
and in what manner the same is to be performed, I declare that what I claim is
1.) A gas engine arranged so that at the moment of ignition the weaker part of the
combustible mixture shall surround the point of ignition, and the richer part of such
combustible mixture shall be further away from the point of ignition substantially as
hereinbefore described.
2.) The use in a gas engine of means such as are hereinbefore described and
illustrated for securing the intimate mixture and incorporation of the gas and air
with the object of securing complete combustion, and enabling a more dilute mixture
to be used.
3.) The arrangement of gas engine hereinbefore described and illustrated by the
drawings by means of which the weaker part of the mixture is caused to surround
the firing point at the moment of ignition, and the intimate mixture and incorporation
of the gas and air is provided for.
4.) The provision in combination with an arrangement for permitting the use of a
more than ordinarily dilute mixture such as is hereinbefore described of a separate
gas slide in connection with the governor for the variation of the gas supply as
required so as to admit a more or less diluted mixture to the cylinder substantially as
hereinbefore described.

page_text: 5.) In a three cycle gas or vapour engine the combination with a cylinder provided
with a compression chamber having air space a², of admission orifice with parallel
sides and a gas admission port and valve so arranged that the effective area of
admission is varied throughout the stroke in proportion to the varying velocity of the
piston as and for the purposes set forth.
6.) In a three cycle gas engine constructed and arranged on the principles herein-
before set forth and claimed the combination with a cylinder, compression chamber
having space a², admission port with parallel sides, and gas admission port and valve
adapted to vary the effective area of admission in proportion to the varying velocity
of the piston, of separate gas slide arranged substantially as and for the purposes
hereinbefore set forth.
m
A1 1007
J. C. CHAPMAN,
70, Chancery Lane, London, W.C.,
Patent Agent for Applicant.