Improvements in Internal Combustion Engines.
Year: 1893

page_text: Date of Application, 8th Sept., 1893
Complete Specification Left, 8th June, 1894-Accepted, 14th July, 1894
PROVISIONAL SPECIFICATION.
Improvements in Internal Combustion Engines.
We, FRANCIS WILLIAM CROSSLEY of Crossley Brothers Limited, Openshaw,
Manchester, and JAMES ATKINSON of Amherst, Fallowfield, Manchester,
Engineers, do hereby declare the nature of this invention to be as follows:-
In internal combustion engines working on what is known as the "Otto" cycle,
that is to say, in which one outward stroke is a suction stroke drawing in the
combustible mixture, the following inward stroke is a compression stroke, the next
outward stroke is the working stroke and then an inward stroke drives out the
burnt products, a chamber usually termed the compression space is formed at the
inner end of the cylinder. The object of this invention is to clear this space more
or less completely of burnt products, and to replace them with pure air, so that the
total contents of the cylinder shut in for compression and subsequently ignited
consist almost entirely of pure air made with the combustible gas or vapour which
is used as fuel. The burnt products commonly found in engines of this type being
replaced with air, more complete and perfect combustion is ensured, also if desired
more gas can be satisfactorily burned and engines of this type being replaced with
air, more complete and perfect combustion is ensured, also if desired more gas can.
be satisfactorily burned and more power obtained from the engine.
We accomplish this object by sweeping through the compression space with
pure air at about the time when the exhaust stroke is being completed and the
suction stroke is commencing. We form the compression space, and so arrange the
air suction valve and the exhaust, that a current of air passing in through the air
valve, sweeps through this space on its way towards the exhaust valve driving
the burnt products in front of it; we have a suitable length of exhaust pipe
between the engine and any exhaust box or the atmosphere, and in this exhaust
pipe we set up a powerful current by means of the pressure left in the cylinder at
the termination of a working stroke, more or less assisted by the rapid movement
of the piston on the exhaust stroke, in such a manner that towards the end of the
exhaust stroke there is a partial vacuum in the cylinder. Before the end of the
exhaust stroke we open the air suction valve freely, also we do not close
the exhaust valve for some very considerable portion of the earlier part of the
suction stroke. During this period the induced scavenging current of pure air
sweeps out the burnt products. The air suction pipe may also be of some con-
siderable length with advantage as in case the suction valve is opened too early the
column of air in the suction pipe is not easily set in motion the wrong way.
Also this column in the air pipe being set in motion toward the cylinder by the
exhaust current and sustained afterwards by the suction stroke of the piston we
are enabled to drive more air into the cylinder at the end of the suction stroke.
A very light self-acting valve on the outer end of the suction pipe may also be
used to shut in a little extra air in the suction pipe, this being due to the ramming
action of the air in the pipe when the suction is completed; such extra pressure of
air will be of assistance in the more early starting of the scavenging action and in
preventing any reverse current in the air pipes.
To obtain the full advantage of this invention the suction and exhaust valves
must be both open at the same time for a notable proportion of a revolution; say
while the crank pin is travelling through from 60 to 90 degrees, and in a moderate
sized engine the exhaust pipe should be not less than say fifteen feet before there is
any material break in its area by any exhaust box, and it may with advantage

page_text: be longer, in some instances a light self-acting valve may also be placed on the
end of the exhaust pipe so as to obtain a partial vacuum in this pipe and in the
exhaust box, if any is used; such vacuum being due to the ramming action and
the rapid cooling of the exhaust gases.
It will be evident that an engine without any air suction pipe, or a very short
one, is capable of being scavenged by the action of the exhaust pipe only, when the
valves are actuated as described above.
Dated this Seventh day of September 1893.
Improvements in Internal Combustion Engines.
We, FRANCIS WILLIAM CROSSLEY, of Crossley Brothers Limited, Openshaw,
Manchester, and JAMES ATKINSON, of Amherst, Fallowfield, Manchester,
Engineers, 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 :-
In internal combustion engines working on what is known as the "Otto" cycle,
that is to say, in which one outward stroke is a suction stroke drawing in the
combustible mixture, the following inward stroke is a compression stroke, the next
outward stroke is the working stroke and then an inward stroke drives out the
burnt products; a chamber usually termed the compression space is formed at the
inner end of the cylinder.
The object of this invention is to clear this space more or less completely of
burnt products, and to replace them with pure air, so that the total contents of the
cylinder shut in for compression and subsequently ignited consist almost entirely
of air mixed with the combustible gas or vapour which is used as fuel.
When the burnt products commonly found in engines of this type are replaced
with air, more complete and perfect combustion is ensured, and if desired more gas
can be satisfactorily burned and more power obtained from the engine.
To enable our invention to be clearly understood we append drawings, in which
Figure 1 is an end view of the cylinder in elevation,
Fig. 2. is a sectional elevation of the end of the cylinder,
Fig. 3. is an end view in section,
Fig. 4. is a sectional plan.
In these figures like letters apply to the same parts. Also in Figures 2 and 4
the piston is shown in section in the position in which it would be at the
termination of an inward stroke, showing the shape and the capacity of the
compression space at this time.
We accomplish the object of our invention by sweeping through the compression
space A with pure air at about the time when the exhaust stroke is being completed
and the suction stroke is commencing. We form the compression space A and
arrange the air suction valve B, the suction passage D. H., the exhaust passage E,
and the exhaust valve C, so that a current of air passing in through the air
valve B sweeps uniformly through the space A as shown by the arrows on its way
towards the exhaust valve C driving the burnt products left over from the previous
working stroke in front of it. To the exhaust valve outlet we attach a long
exhaust pipe, F. It is well known that an internal combustion engine working on
what is known as the "Otto" cycle has at the time the exhaust valve is opened
(just before the completion of the working stroke) a considerable terminal pressure,
namely, about 40 lbs. above the atmosphere. This cylinder-full of hot gases at
this pressure is commonly wasted by allowing it to exhaust directly into the
atmosphere; but it will be understood that by using a long exhaust pipe the

page_text: energy in the gases may be utilised in setting up a very powerful current in
the exhaust pipe whereby some of the otherwise wasted energy is transformed into
energy represented by the long column of exhaust gases in rapid motion. This in
turn causes a material amount of suction tending to draw the remaining exhaust
gases out of the cylinder, the action being noticeable not only during the exhaust
stroke of the piston but if the exhaust pipe is of a suitable size and length it
becomes very noticeable even at the termination of the exhaust stroke about which
time it causes a partial vacuum in the compression space A.
We avail ourselves
of this partial vacuum to enable us to change the contents of the compression
space A, the burnt gases being replaced with pure air or it may be pure air and
gas. To enable this change to take place it is necessary to have both the air
valve B and the exhaust valve C open together for a notable period, in practice we
find that we can open the air valve B when the crank has, say, 45 degrees to
travel before the crank pin is on the inner centre, and also we find that we can
leave the exhaust valve C open until the crank pin during the suction stroke has
travelled 45 degrees past this inner centre so that these valves are open together
for about a quarter of a revolution of the engine. During this period the induced
scavenging current, which may be pure air or which may commence with pure air
and shortly change to a mixture of gas and air, sweeps out the burnt products.
The air and gas valves remaining open a suction then takes place in the ordinary
manner. From the action described it will be noticed that the contents of the
cylinder when shut in for compression are entirely different from the contents shut
in in "Otto" engines as they have been hitherto worked. In an engine constructed
under our Patent the cylinder contains no residuum but only pure air and gas. In
all other such engines a large percentage of the contents of the cylinder is burnt
gases or inert residuum. This great difference in the charge makes a very notable
improvement in the performance of the engines, and our experiments have proved
conclusively that an engine with the same sized cylinder can when working on our
system give some 30% more power and is also more economical to the extent of
some 15 to 20% when working with ordinary lighting gas; and when working
with weak gases, such as "Dowson gas, the improvements are still more
noticeable.
"
The air suction pipe may also be of some considerable length with advantage as
in case the suction valve is opened too early the columu of air in the pipe is not
easily set in motion the wrong way, also this column being set in motion towards
the cylinder by the exhaust current and sustained afterwards by the suction stroke
of the piston a larger charge is driven into the cylinder at the end of the suction
stroke. But we do not attach much importance to this long air pipe, good results
being obtainable without it.
The length of the exhaust pipe however is of great importance. It is controlled
to some extent by the speed at which the engine runs. At speeds commonly used
we find a length of about sixty feet gives the best results and in this length there
should be no chamber of any material capacity such as a large exhaust box.
Small exhaust boxes may be used without materially affecting the result, and also
silencing apparatus such as chambers containing gravel may be used at the end of
the exhaust pipe.
The position of the air valve B and the exhaust valve C may have to be placed
otherwise than as shown in the drawings, but in any case it is necessary to so
construct the passages connecting them to the compression space A that the current
will sweep uniformly through.
While it is obvious that an engine working under this invention is distinctly
different in results from engines working under the ordinary "Otto" cycle, we are
however aware that somewhat similar results have been obtained by the addition
of a pump to force air through at the time when in our engine the scavenging takes
place, or it may be to suck out the burnt gases; but our arrangement dispenses with
this pump.

page_text: Having now particularly described and ascertained the nature of our said
invention, and in what manner the same is to be performed, we declare that
what we claim is-
1. The general arrangement and construction of internal-combustion engines
operating on what is known as the "Otto" cycle having the compression space A
with the air passage D. H. and the exhaust passage E suitably formed; in com-
bination with the air valve B and the exhaust valve C suitably timed so that both
are open at the same time and for a notable period; also in combination with
these the use of a long exhaust pipe F substantially as and for the purpose described
and illustrated.
Dated this 7th day of June 1894