Improvements in Steam and other Engines.
Year: 1888

page_text: Date of Application, 11th Oct., 1888
Complete Specification Loft, 11th July,
1000
Accepted, 20th Sept., 1000
PROVISIONAL SPECIFICATION.
Improvements in Steam and other Engines.
I, HENRY GRAFTON, of 53 Chancery Lane, in the County of Middlesex Engineer
do hereby declare the nature of this invention to be as follows:-
My Invention relates to engines which, owing to the small number of their moving
parts and other special features of construction, are especially adapted to run at very
high speels. The improved high speed engine of my invention resembles that class
of engine in which two pistons move in opposite directions in the same cylinder. It
is valveless, that is to say it has no separate distribution valve, but one of the pistons
acts also as the distribution valve to control both the admission and exhaust of the
motive fluid to and from the space between the two pistons; and the invention has
for its principal object to make the moving parts of such an engine balance each other
as nearly as possible whilst obtaining by means of the piston itself, the early cut-off
heretofore only obtainable by a separate long stroke valve. To this end, the invention
consists in combining the two oppositely moving pistons (of which one is adapted to
act also as the distribution valve) with a two-throw crank shaft whose cranks are
placed at such an angle that the strokes of the pistons whilst for the most part opposite
in direction will be timed with regard to each other differently to the timing of the
said strokes in regard to the cylinder (which is necessary to enable either piston to
act as a valve) at the same time that their effective strokes are approximately equal
to their actual strokes. The combined effective operation of the two pistons upon the
crank shaft will be practically equivalent to that of a single piston of the same area
whose stroke is equal to twice the angular distance between (i.e. twice the chord of the
arc subtending) the said cranks, whilst the length of stroke of the pistons and the
necessary length of the connecting rods is only proportional to the actual radius of
the individual cranks, that is to say is little more than a fourth of that necessary with
a single piston, so that the entire length of the engine is greatly reduced.
The engine in its simplest form is single acting. The one piston may enter within
a cylindrical trunk of the other piston which trunk virtually acts as the distribution
valve. This trunk works within a guiding cylinder having an inlet port over which
travels a corresponding port in the trunk, the latter port exhausting on passing over
another port or beyond the end of the guide cylinder.
The inner piston is connected to a middle crank, and the trunk has lateral trunnions
connected to a pair of side cranks placed in line and at an angle of about 140° to the
middle crank.
The two pistons may be ordinary pistons working in a stationary cylinder and
connected in any suitable way with the cranks arranged as above described, the one
piston acting as distribution valve as before, but cutting-off against the inner face of
the working cylinder.
1030
COMPLETE SPECIFICATION.
Improvements in Steam and other Engines.
I, HENRY GRAFTON, of 53 Chancery Lane, 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—
My Invention relates to engines (worked by steam or other elastic fluid supplied

page_text: under pressure) which, owing to the small number of their moving parts and other
special features of construction hereafter referred to, are especially adapted to run at
very high speeds.
The improved high-speed engine of my invention resembles to some extent that
class of engine in which two pistons move in opposite directions in the same cylinder.
It may be said to be valveless in-as-much as it has no part acting solely as a distribu-
tion valve, but one of the pistons fulfils the function of a distribution valve wholly
controlling both the admission and exhaust as well as of a driving piston.
The Invention has for its principal object to make a simple engine whereof the
moving parts balance each other as nearly as is practically possible consistently with
the fulfilment by the piston of the function of a valve. The invention has also for
its object to obtain by means of the piston itself, an early cut-off and consequently a
high grade of expansion, such as would only be obtainable in a simple engine by
means of a very large valve having a long stroke and fulfilling no other function than
that of controlling the admission and exhaust of the steam or other motive fluid.
The grade of expansion obtained in my engine is equivalent to that only obtainable in
many engines by a complicated valve gear, or in a compound Engine.
The invention consists of an engine wherein two oppositely moving pistons (whereof
one is adapted to act also as the distribution valve) work in the same cylinder, and
are combined with a two-throw crank shaft whose cranks are placed at such an angle
that the strokes of the pistons, although for the most part opposite in direction, will
be timed with regard to each other differently to the timing of the said strokes in
regard to the cylinder, which is necessary to enable the one piston to act as a valve.
The combined effective operation of the two pistons upon the crank shaft will be
approximately equal to the sum of their actual sirokes, and equivalent to that of a
single piston of the same area whose length of stroke is equal to twice the angular
distance between (i.e. twice the chord of the arc subtending) the said cranks, whilst
the actual length of stroke of each of the pistons is only equal to twice the radius of
the individual crank to which it is connected. Moreover, the minimum length of the
connecting rod of the piston nearest to the crank shaft, being proportional to the
actual radius of the crank, is little more than a half of that necessary with a single
piston having the greater stroke above mentioned, so that the length of the engine is
much less than usual.
The advantages of this engine may be summarised as follows;-
Simplicity and cheapness of construction; high speed with durability; high grade
of expansion (five times) and consequently economy of steam, without compounding
or complication of valve gear; balanced valve with large area of port and short
passages; small radius of crank relative to effective stroke; short stroke and con-
sequently little momentum of reciprocating parts compared with effective stroke;
long connecting rods in proportion to radius of cranks and consequently little friction
on guides; approximate balancing of moving parts which are all employed in the
transmission of available power.
Reference is to be bad to the accompanying drawings forming part of this Specifica-
tion wherein :—
Fig. 1 is a vertical section of the Engine taken in the plane of the crank shaft.
Fig. 2 is a central vertical section at right angles to Fig. 1. Fig. 3. is a horizontal
section on line 1-1 Fig. 1 ; & Fig. 4 is a similar section on line 2-2 Fig. 1.
The same letters of reference indicate the same parts in all the figures.
The Engine consists of two single acting pistons A, B, both working in the bore
of a stationary cylinder C, and connected with a crank shaft common to both, the
piston A being connected with a middle crank D, by a connecting rod E, and the
other piston B with a pair of side cranks F, F, by connecting rods G, G. The
cranks F, F, are placed in line with one another, and as nearly as possible diametrically
opposite to the crank D, consistently with the operation of the piston B, as a valve.
I find in practice that a deviation of about 40 deg. from the diametrically opposite
position affords the best compromise between the irreconcileable conditions of a

page_text: perfect balance of the pistons, and the admission of steam to the cylinder. The
crank D is therefore placed at about 140 deg. from the cranks F F.
The piston B acts as the distribution valve by cutting off against the inner face of
the working cylinder C; and for this purpose the cylinder has two internal circun-
ferential grooves H, 1, which are respectively the admission and exhaust ports and
respectively communicate with the inlet and exhaust passages as shown. The piston B
which acts as a valve as well as a piston is formed with a cylindrical trunk fitting
in the cylinder C and furnished with a circumferential row of ports K which at the
proper times coincide with the admission and exhaust ports H I of the cylinder. The
piston A enters the trunk of the piston B but does not fit therein both being slightly
conical and clearance being left between them when in their closest position.
The whole Engine may be enclosed in a casing part of which is cast in one piece
with the cylinder, the steam and exhaust passages and the upper halves of the crank
shaft bearings. This part of the casing is bolted on to a box casting forming the
crank chamber in which the cranks run in a bath of oil and water, the crank shaft
bearings being provided with stuffing boxes and glands to prevent leakage. The
casing is closed at top by a hood and the crank shaft is provided with a fly wheel,
external of the casing.
The operation of the Engine is as follows;-Supposing the parts to be in the position
shown and the Engine running in the direction of the arrow, the valve piston B is
descending and about to uncover the admission port H. Immediately this occurs
steam is admitted between the pistons, and as soon as the cranks D & F have passed
what I may term their conjoint dead-centre the pistons are moved apart by the pressure
of the steam. As soon as the piston B on its upward stroke again reaches the position
shown the admission is cut off and the steam then acts expansively in the cylinder
until the ports K coincide with the exhaust port I, the momentum of the fly wheel
completing the stroke and carrying the Engine to the position shown, thus completing
a revolution; the exhaust being closed before the completion of the revolution in
order to obtain the cushion necessary to resist the momentum of the parts, and so
prevent knock.
Having now particularly described and ascertained the nature of the said.
invention, and the manner in which the same is to be performed, I declare that what
I claim is.
1. An Engine constructed and operating substantially as herein specified and con-
sisting essentially of two pistons working in the bore of the same cylinder, the one
piston being adapted to act also as a distribution valve wholly controlling both the
admission and exhaust as herein described, and the two pistons being coupled to cranks
on the same crank shaft placed at such an angular distance apart that the two pistons
will move in the cylinder in opposite directions for the greater part of the revolution
& that the one piston will act both as distribution valve & piston, substantially as set
forth.
2. The herein described Engine consisting essentially of two pistons working in the
bore of the same cylinder (and moving therein in opposite directions for the greater
part of the revolution) the one piston acting also as a distribution valve wholly con-
trolling both the admission and exhaust, and the two pistons being coupled to cranks
on the same crank shaft placed at such an angular distance apart as to cause the motion
of the pistons to be as nearly balanced as is compatible with the most effective
operation of the one piston both as a distribution valve & piston, substantially as set
forth.
3. In the herein described Engine the one piston coupled with two side cranks,
by means of connecting rods passing alongside the cylinder, in combination with the
other piston coupled with the middle crank by a single central connecting rod as set
forth.
4. In the herein described Engine having two pistons working in the same cylinder
and coupled to cranks on the same crank shaft placed at such an angular distance apart
as to cause the pistons to nearly balance each other and yet admit of the one piston

page_text: acting as distribution valve to wholly control both the admission and exhaust, the
combination of an all round circumferential row of ports in a trunk of the said piston
with all round circumferential admission and exhaust ports formed in the cylinder.
substantially as and for the purpose specified.
5. In the herein described engine having two pistons working in the same cylinder
and coupled to cranks on the same crank shaft arranged as described, the combination
with a trunk piston adapted to act as a distribution valve wholly controlling both the
admission and exhaust as described, of the second piston entering the trunk piston as
described.
1000
HENRY GRAFTON.
By A. M. & Wm. Clark,
53, Chancery Lane, London, Patent Agents.