Year: 1897

page_text: Date of Application, 30th Aug., 1897
Complete Specification Left, 13th May, 1898-Accepted, 18th June, 1898
I, WILLIAM THOMAS ROWDEN, B.Sc., of Lenzie, in the County of Dumbartonshire,
Professor of Applied Mechanics in the Glasgow and West of Scotland Technical
College, do hereby declare the nature of this invention to be as follows:-
My invention relates to internal combustion engines that have tandem cylinders
with single acting pistons working in the cycle of Beau de Rochas or the four
steps' cycle.
The first part of my invention refers to the method of constructing these engines
so as to give ready access to the interiors of the cylinders for cleaning, to secure
correct alignment of the cylinders and of the pistons in their manufacture, and
to render unnecessary the disturbing of that alignment when the pistons have to
be taken out for cleaning or for repairs.
The second part refers to the arrangement for utilizing the non working side
of one cylinder and piston of a tandem pair as a pump for sending a charge of
cool air alternately through the compression spaces of the two cylinders of another
tandem pair, working on the same crank shaft, when the pistons are near the ends
of their respective exhaust strokes.
Access to the inside of the cylinder more distant from the crank shaft can be
had by removing its cover, as in an ordinary engine. This cylinder I make of
greater internal diameter than that nearer the crank by an amount sufficient to
allow the cover of the nearer cylinder to pass through. In this way, not only can
access to the inside of the cylinder nearer the crank be obtained without disturbing
the connexion between the two cylinders, but by removing the cover of the more dis-
tant cylinder the two pistons can be drawn out without such disturbance and without
detaching either of the pistons from the rod that rigidly connects them, the smaller
cover through which this rod passes remaining on the rod between the two pistons.
An additional advantage of this arrangement is that the two cylinders rigidly
connected by suitable parts may be bored at one setting, ensuring their axes being
truly in line, which line need never be subsequently disturbed.
The same is the case with the two pistons. After being secured to the inter-
mediate rod they can be turned at one setting in the lathe and the connexion remain
unbroken afterwards.
For sending a clearing charge of air through the compression space at the end
of each cylinder during the completion of each exhaust stroke, according to my
invention there are two or more pairs of tandem cylinders with pistons connected
to the same crank shaft or to crank shafts moving in unison.
The space between each tandem pair of cylinders is enclosed to form an air-
chamber which is fitted with an air admission valve. Thus, the nonworking end
of the cylinder more distant from the crank being open to this chamber its piston
practically forms the plunger of an air pump.
Taking for illustration the case of two parallel lines of cylinders side by side
with cranks 180° apart, the two cylinders on each crank working half the cycle

page_text: apart, the air in one of the chambers is always under compression at the proper
time to be sent alternately through one of the two cylinders in the other line at or
near the end of the exhaust strokes of the pistons.
The air supply pipes of one pair of tandem cylinders are connected with the
chamber of the other pair the cams of the air valves being set to lift the valves a
little before the end of the exhaust strokes. The exhaust valves are kept open a
little longer than usual to allow of the charges of air taking full effect in the
compression spaces.
The supply of air for the new charge in the working cylinder may follow the
same course as the scavenging charge just described.
The invention also applies to engines having three pairs of cylinders on the
same crank shaft with cranks about 120° apart, indeed it is not restricted to the
particular crank angles here numerically specified merely for illustration.
Dated this 28th day of August 1897.
I, WILLIAM THOMAS ROWDEN, of Lenzie, near Glasgow, Professor of Applied
Mechanics in the Glasgow and West of Scotland Technical College, do hereby
declare the nature of this invention and in what manner the same is to be per-
formed, to be particularly described and ascertained in and by the following
statement:
My invention relates to internal combustion engines that have tandem cylinders
with single acting pistons working in the cycle of Beau de Rochas, or the four
steps' cycle.
The first part of my invention refers to the method of constructing these engines
so as to give ready access to the interiors of the cylinders for cleaning, to secure
correct alignment of the cylinders and pistons in their manufacture, and to render
unnecessary the disturbing of that alignment when the pistons have to be taken out
for cleaning or repairs.
The second part refers to the arrangement for utilizing the nonworking side
of one cylinder and piston of a tandem pair as a pump for sending a charge of
cooling air alternately through the compression spaces of the two cylinders of
another tandem pair, working on the same crank shaft, when the pistons are near
the ends of their respective exhaust strokes.
In the accompanying sheet of drawings Fig. 1 is a sectional elevation and Fig. 2
a sectional plan of two pairs of vertical tandem cylinders on the same crank shaft,
with cranks 180 degrees apart.
J
The latter section is taken at the level of G 2 Fig. 1, the cover K 4 and pistons P3
and P4 being omitted.
C1, C2, C3, and C4 are four single acting cylinders, water jacketed in the usual
manner, and P1, P2, P3, P4, their respective pistons, the tops being the working
sides of the pistons.
Each is connected with an air valve, A 1, A 2, and an exhaust valve E1, E2, by
ports B above its piston as shown in Fig. 1.
The cylinders more distant from the crank shaft, (the upper cylinders in a
vertical arrangement) C1 and C3, are connected with the nearer, C2 and C4, by
chambers H1 and H2 to which they are bolted in the usual' manner as shown in
Fig. 1.

page_text: The cylinder covers K 1, K3, of the distant (here, the upper) cylinders, Fig. 1,
are secured by bolts in the usual manner, but the covers K 2, K4, of the cylinders
nearer the crank-shaft have only narrow flanges and are held in place by some
suitable device as shown at K2 in Figs. 1 and 2.
The cylinders C1 and C3 are made just large enough to pass these covers K-2
and K 4.
Access to the holding down bolts of these covers is provided for by suitable
openings in chambers H 1 and H2. Each chamber has four openings, O, in the
drawing. Fig. 2.
Thus, by removing the nuts of the holding down bolts of either of the covers K2
or K 4 'the cover itself can be easily raised and access to the inside of the cylinder
obtained without any disturbance of the alignment of the cylinders or pistons.
Moreover, the two pistons of either pair of cylinders can be taken out of their
cylinders for repairs without any disturbance of alignment.
In order that the two cylinders of a tandem pair may be finished in the boring
machine as one cylinder' so as to secure true alignment, I use some bolts solely for
holding together the chambers and the lower cylinders as shown at D between
H2 and C4, Fig. 1.
"
:
This method is only one of others that may be applied for the same purpose.
The pistons themselves of either pair of cylinders, with the finished cover in
place on the rod connecting them, may be completed at one setting in the lathe
so as to get true alignment in them also, and they can be entered into their respec-
tive cylinders without disturbing that alignment.
For sending a clearing charge of air through the compression space of each
cylinder during the completion of each exhaust stroke, according to my invention,
there are two or more pairs of tandem cylinders with pistons connected to the
same crank shaft or to shafts moving in unison.
The above named openings into the connecting chambers H 1 and H2 are closed
by airtight doors, and air valves for admission only are placed on any of them.
From each chamber an opening G1 or G 2 leads into an air pipe N 1 or N 2 for
supplying the air valves. G2 from the right hand chamber leads into pipe N 2 for
supplying the air valves A 2 on the left hand cylinders through connecting pipes L 2,
whilst G1 communicates through N 1 and pipes L 1 with the air valves A 1 on the
right hand cylinders.
Only one pipe, L2, connecting the air valves with the pipes N 1 and N 2, is shown
in Fig. 1. The other three are omitted.
At the bottom of each pipe N 1 and N2 is an inlet valve to act as auxiliary to
the admission valves, before referred to, on the doors of the chambers H1, H2.
The under sides of pistons P1 and P 3 and their respective chambers H 1 and H2
act as air pumps and reservoirs, each for scavenging the cylinders alternately on
the other line.
Thus, in the position shown in Fig. 1, P3 has compressed the charge which it
took in on its upward stroke. On the other line of pistons, suppose P2 to be at
the end of its exhaust stroke, P1 being at the end of compression. The air
valve A 2, Fig. 2, of cylinder C2 has been raised a little time before the completion
of the exhaust stroke of P2 and the compressed charge of air has rushed from G 2
through N2, L2, A2, across the cylinder, and out of the exhaust valve E 1. On
the next descent of the piston P 3, the piston P1 will be at the end of its exhaust
stroke and the charge will be sent through its cylinder.
The charges from H 1 act in the cylinders C3 and C4 in precisely the same way.
My invention also applies to engines having three pairs of cylinders with
cranks at about 120 degrees apart; indeed it is not restricted to the particular
crank angles which are here named merely for illustration.
In the case of three pairs of cylinders with cranks 120 degrees apart, the pump
on each crank has its charges ready at suitable times for the cylinders of the pair
of pistons on the crank 120 degrees in advance.

page_text: 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
First: In an internal combustion engine with tandem cylinders, the method
of construction which consists of making the cylinder more distant from the crank-
shaft larger than the other by an amount sufficient to pass the undivided cover
of the latter, for the purposes set forth.
Second: In an internal combustion engine of the Beau de Rochas cycle, with
tandem cylinders, the use of the non working side of one piston and cylinder in
one line of cylinders as an air pump for providing scavenging charges for the
cylinders of another line, for the purpose set forth and in a manner substantially
as described.
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