Improvements in Gas and Petroleum Engines.
Year: 1895

page_text: Date of Application, 2nd Oct., 1895
Complete Specification Left, 1st July, 1896-Accepted, 1st Aug., 1896
Improvements in Gas and Petroleum Engines.
I, JOHN JOHNSTON, of 2, Bush Street East, Pembroke Dock, in the County of
Pembroke, Engineer, do hereby declare the nature of this invention to be as
follows:-
My invention relates to gas and petroleum engines, and its object is to produce
a simple engine in which a power impulse is obtained at every revolution, the engine
being suitable either for gas or petroleum.
My invention consists in a special mechanical arrangement and cycle of operations
hereinafter described.
In carrying my invention into effect according to one modification I provide an
open-ended cylinder bore of two diameters, the inner cylinder is of a smaller diameter,
and it serves as the power cylinder. The outer cylinder is of larger diameter,
and the piston working in the outer cylinder connects by piston rod to the inner
piston.
The larger piston on the outstroke moving outwards creates a partial vacuum
between itself and the smaller piston. This vacuum is utilized to charge the power
end of the cylinder by first sucking out the exhaust gases left in the cylinder,
and then drawing into the cylinder a charge of gas and air. The inlet gas and
air valve is of a conical seated lift type, and the seat is provided with holes opening
into an annular channel connected to the gas supply. Assume the piston to move
out after compression and explosion, under a power impulse; then at the out end of
the stroke it over-runs the first port controlled by a lift valve opening outwards. The
cylinder discharges to atmospheric pressure through the said lift valve. On the
further movement of the piston a second port is uncovered also controlled by a
check valve opening outwards. This port opens communication between the power
side of the small piston and the side opening or openings to the larger piston.
At this position there is a partial vacuum existing in the space between the two
pistons and the exhaust gases at atmospheric pressure flow in from the cylinder into
the space, while simultaneously the gas and air charge is drawn into the cylinder at
the hereinbefore described gas and air valve, and fills the cylinder to the desired
extent. On the return stroke compression of the mixture is accomplished, and at the
termination of that stroke the charge is exploded to produce the power stroke the
ignition being accomplished in any usual manner.
During the return stroke, while compression is going on upon the inner side of
the small piston, the exhaust gases are being discharged through the check valves from
the space between the larger and the smaller pistons.
I sometimes dispense with the check valve on the outer exhaust port, and allow
the exhaust gases between the pistons to be slightly compressed until the piston
uncovers the inner port at its outside edge, through which port the gases will then
escape.
It is to be distinctly understood that both pistons move together and are
connected by one connecting rod to a common crank. Sometimes the outer and
inner pistons may be connected by a trunk, in which case a reservoir is provided
to enable the outer piston to act in exhausting and discharging the exhaust gases.
The arrangement I have described can be operated entirely by automatic valves,
but in some cases I actuate the valves positively from eccentrics or cams.

page_text: Water jackets and other arrangements are applied to the engine in the usual
manner. When the engine is used as a petroleum engine, any known device is applied
for the purpose of vapourizing the oil.
The igniter tube is preferably employed for igniting and it may be either of the
open kind, or the closed kind, operated by a timing valve.
Dated this lot dow of October 1805
MARKS & CLERK,
18 Southampton Buildings, London, W.C., and
13 Temple Street, Birmingham, Agents for the Applicant.
тар аци
I, JOHN JOHNSTON, of 2, Bush Street East, Pembroke Dock, in the County of
Pembroke, 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:-
My invention relates to gas and petroleum engines, and its object is to produce a
simple engine in which a power impulse is obtained at every revolution, the engine
being suitable either for gas or petroleum.
My invention consists in a special mechanical arrangement and cycle of operations
hereinafter described.
Referring to the accompanying sheet of drawings,
Figure 1 is a longitudinal vertical section through a gas engine constructed
according to one modification of my invention.
Figure 2 is a similar section partly in elevation of a gas engine with a modification
in the piston arrangements.
In carrying my invention into effect according to the modification shown at
Figure 1, I provide an open ended cylinder of two diameters A. B. The inner
cylinder A is the smaller one, and it serves as the power cylinder. The outer
cylinder B is a larger one and acts as a pump in a manner hereinafter described.
Two pistons a and b connected rigidly together by the piston rod C work their
respective cylinders A and B. These pistons a and b are connected in the usual
manner to a crank shaft D, as shown diagrammatically at Figure 1. The larger
piston 6 on its outstroke creates a partial vacuum between itself and the smaller
piston a. This vacuum is utilized to charge the power end A of the cylinder by first
sucking out the exhaust gases left after the working stroke, and then drawing in a
charge of gas and air. The inlet gas and air valve E is of the ordinary conical
seated type and the seat is provided with holes F. F. opening into an annular
channel G connected to the gas supply.
The cycle of operation of this engine is as follows ;-Assume the double piston a b
to move out after compression and explosion under a power impulse; then at the
out end of the stroke a groove K in the piston a communicating with the
cylinder A by means of a number of boles k k over-runs the first port H,
controlled by the conical seated lift valve I opening outwards, and the expanded
gases discharge to atmosphere. On the further movement of piston a the groove K
over-runs the annular port or groove L thus putting the front end B of the cylinder
into communication with the back end A. Simultaneously with this movement the
back end of the piston a covers the port H, thus cutting off communication between
the cylinder A and the atmosphere.
This particular position of the double piston in the cylinder is shown clearly at
Figure 1, and as there is a vacuum existing between the two pistons ab the exhaust
gases are drawn from A into B by way of the holes k groove K and annular
port L; while simultaneously the automatic gas and air valve E opens and a charge

page_text: is drawn into the cylinder A. On the return stroke, compression of the mixture
takes place, at the same time the exhaust is discharged as soon as the outer end
of the piston a over-runs the port H, slight compression of these gases taking place
until this occurs. This cycle of operation thus gives an explosion for every revolution
of the crank shaft.
Ignition of the mixture when compression is complete is arranged for in any known
manner, preferably by means of a hot igniting tube.
The valves just described are all automatic, but I may if I prefer actuate them
positively by any well-known mechanical device, such as a side shaft and timed cams,
or eccentrics and levers.
In Figure 2 I show a modification of the double pistons a b. Instead of
connecting the two pistons by a rod such as C Figure 1, 1 make a a trunk piston
formed by a reduced prolongation of b; in which case a reservoir M is provided
of sufficient volume in conjunction with the annular cylinder space B to enable the
act of exhausting the cylinder end A and similarly drawing in the necessary charge
of gas and air through the valve E to be performed. To exhaust from B on the
return stroke, a port N runs along the trunk and up to the piston rings, so that the
gases may be discharged through the exhaust valve I by way of the ports N and H.
In large engines to obviate the compression that takes place in the pump cylinder B
previous to the piston a over running the port H on its backward stroke I sometimes
place an additional exhaust valve opening outwards.
In governing the engine herein before described I preferably use a centrifugal ball
governor of the ordinary type, baving two friction cones mounted on the main
spindle. The up or down movement of these cones acts on a larger friction cone at
right angles to the main spindle. This larger cone revolves a nut which in turn
operates on a spring holding the gas and air valve to its seat. The larger cone is
thus turned either to left or right according to which of the smaller cones is put
into gear with it by the governor, and therefore the nut similarly alters by its
movement the tension on the spring and therefore the resistance to opening of the
valve.
When the engine is used as a petroleum engine the mechanism is similar to that
already described with the addition of an oil vapouriser. Water jackets, and the other
arrangements are applied to the engine in the usual manner.
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. In a gas or petroleum engine having an explosion every revolution and tandem
pistons in a cylinder of two diameters; the particular arrangement of valves ports
and passages described in the first modification with reference to Figure 1
whereby the operations of exhausting, charging and compressing air carried out
automatically.
2. In a gas or petroleum engine having an explosion every revolution and tandem
pistons in a cylinder of two diameters; the particular arrangement of valves ports
and passages in combination with the reservoir M Figure 2.
3. In a gas or petroleum engine having an explosion every revolution and tandem
pistons in a cylinder of two diameters; the particular arrangement of valves ports
and passages in conjunction with any well known devices for positively operating the
valves.
natali: 1 T..1..
MARKS & CLERK,
18, Southampton Buildings, London, W.C., and
13, Temple Street, Birmingham, Agents.