Improved Machinery for Utilizing the Expansion and Producing the Compression of Elastic Fluids.
Year: 1892

page_text: Date of Application, 26th May, 1892-Accepted, 16th July, 1892
COMELVIN DIMCILUATION.
Improved Machinery for Utilizing the Expansion and Producing the
Compression of Elastic Fluids.
1, WILLIAM HENRY NORTHCOTT, Hatcham Ironworks, Pomeroy Street, New
Cross, S.E., 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 improvements relate to cylinder and piston apparatus suitable for obtaining
motive power from steam and other elastic fluids, and for compressing gases. The
apparatus is described as for motive power purposes, but the construction remains
the same for compressing gases, the motion of the valves being altered to convert
the outlet for steam into the inlet for gas, and vice versa.
Fig. 1 shows my two stage engine with a steam inlet a, a steam outlet b, two
pistons c and d and a distribution valve with two discs e and f. The two pistons
move in opposite directions. They have separate piston rods as shown, that from
the upper piston going through a stuffing box in the lower piston, and they are
coupled to a crank shaft by connecting rods as will be readily understood. The
valve e, as seen is admitting steam by the port a. to the top of the piston c, which
latter is thereby forced down. The piston'd being on the same crankshaft but on
a crankpin opposite to c's crankpin, is forced upwards, and as the two pistons
approach each other the steam between them is forced out at the port under the
valve disc f, into the lower part of the valve chest, where it is free to get under
the piston d, and to leave by the exhaust pipe b. When the pistons are together,
the valve has moved down far enough to cover up the steam admission port and to
place g and h, into communication with each other. Steam from above the piston c,
now passes into the space between the pistons which are thus forced asunder.
Meanwhile steam from under d, is expelled through the port i, to the exhaust
pipe b.
Separately considered the two pistons are single acting, but together they form a
double acting compound engine. The thrust on the crankpins is constantly in the
same direction, and the two reciprocating masses counterbalance each other. In
Fig. 1 the two pistons are shown of different sizes, but this is not necessary, as
when the bore of the cylinder is uniform, and the strokes equal, the displacement.
between the pistons, is twice that above the piston c.
The strokes may however be made equal or unequal and the crankpins need not
be exactly opposite, although for reversible engines it is best to so place them.
Instead of the valve discs being arranged as in Fig. 1. the discs e and ƒ may cover
the ports g and i and admit steam to these ports by their upper edges, releasing it
at their lower edges. In this case the valve chest is extended downwards instead of
upwards, as shown, so that may be some distance below i. The port /, then
requires no valve, but the clearance space under the piston d. should be made not
less than the displacement volume of the piston c. To govern the engine, the valve
may have a variable motion under the action of a governor altering the 'lead or,
'travel,' or both, or the steam may be 'cut-off' by a separate valve before reaching
the first inlet port shown, or an ordinary throttling governor may be used. The
above refers generally to the other arrangements shown, which are modifications
or developments of Fig. 1.
Figs. 2 and 3 show respectively three and four stage engines of my improved
construction. In Fig. 2, there are two pistons c and C coupled together and
having a piston d working between them. The three pistons are shown of
different sizes, but the two upper or the two lower pistons may be made equal..
The port, h, serves for between c and d, and the port H for between d and C

page_text: In Fig. 3. there are two pairs of pistons c. C. and d. D. Each pair works
in opposite directions, i.e., one pair makes an outstroke whilst the other makes an
instroke. The steam first admitted and expanded above the piston c, is secondly
expanded between c and d, thirdly expanded between d and C, and fourthly
expanded between C and D.
Figs. 4, 5, and 6, show modifications with a central valve casing formed as a
trunk continuation of one of the pistons, but the trunk may be continued through
the cylinder cover and used as a piston rod-two of the rods shown being then
dispensed with. The central valve casing may be made also as shown in Figs. 7,
8, and 9 where it is a fixture projecting from the cylinder cover.
In this case
the pistons are annular pistons and they slide upon the central cylindrical valve
chest.
By coupling more pistons together the expansion or compression may be carried
out by more than four stages, and either of the arrangements described may be
duplicated after the manner of Fig. 10. which is a double acting development of
Fig. 1.
Two steam inlets are shown but by making the piston valve hollow, one
will suffice.
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. For the purposes named the several combinations of cylinders, pistons and
valves substantially as described.
2. The several combinations of cylinders and pistons forming stage expansion
and compression apparatus substantially as described.
3. The improved machinery for utilizing the expansion and producing the com-
pression of elastic fluids substantially as described.
Dated this 25th day of May 1892.
WILLIAM HENRY NORTHCOTT.