Improvements in Single-acting Engines.
Year: 1890

page_text: Date of Application, 24th Dec., 1890-Accepted, 24th Jan., 1891
COMPLETE SPECIFICATION.
Improvements in Single-acting Engines.
I, GEORGE RICHARDS, of Altrincham, Cheshire, 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 improvements in the construction of single acting engines,
and relates particularly to that class of engines which have a piston which partially
rotates in its longitudinal movement in the cylinder for the purpose of admitting
and releasing the steam through suitable ports and steam passages.
I do not claim novelty in the general mechanism employed for giving the partial
rotation to the piston, but only in a modification of this feature of the engine, due
to the special arrangement which I make of the steam ports and passages in the
piston and cylinder for the purpose of admitting and releasing the steam. The
amount of rotation of the piston required in this class of engine depends upon the
width of the steam ports, and the distance measured on the periphery of the cylinder
from the steam ports to the exhaust ports.
It has been the practice in the construction of such engines to cast the steam
passages in both the piston and cylinder. Owing to the difficulty of doing this,
the passages have been few in number and large in area, and this has necessarily
increased the degree of rotation required by the piston to make it act as a valve.
Although I do not claim the construction of the connecting rods and the shape of
the crank shaft for the purpose of giving the pistons a partial rotation, the drawings
of the details are made complete, so as to illustrate the feature in the engine.
It will be noticed that the cranks are set at an angle with the axis of the crank shaft,
the result being, that as the crank makes a complete rotation, the angle of the crank
with reference to the axis of the bearings is reversed.
Owing to the universal joints in each end of the connecting rod, this peculiar motion
of the crank, causes the piston to rotate more or less, according to the degree of
angularity of the crank compared with the axis of the crank shaft.
The amount of rotation of the piston is in exact proportion to this angularity, and
it will be readily seen that any excess of this angularity is detrimental to the proper
working of the engine, because the end thrust of the connecting rod, tends to produce
an undue side strain in two opposite directions in each revolution.
It would also cause an undue vibration end wise on the crank shaft. In my improved
system of arranging the steam ports of the engine, this angularity of the crank is
reduced to a minimum, and the mechanical defect of the system is reduced corre-
spondingly, so as to produce a mechanically satisfactory machine.
The accompanying drawings describe the engines both in the simple and compound
form.
Referring to the drawings. In Figs. (1) and (2) is shown the general construction
of the engine using two cylinders and two pistons, both the cylinders having the
steam admitted of equal pressure. The pistons (2) are of trunk form with wrist
pins which are connected to the cranks (3) by connecting rods (4). The centres of
the cranks are placed opposite to each other, so as to balance the reciprocating motion.
In Fig. (2) a section of the cylinder and piston is shown, in which the passages (8, 8)
in the cylinder (5) are those in which the steam is brought ready to be delivered into
the ports (9, 9) in piston (2).
The piston in Fig. (2) is shown in the position for exhausting the steam at the
bottom of the stroke, through the passage (10) in the cylinder.
The exhaust steam is delivered into the casing. (7) from both cylinders, and is
collected and delivered into the air by the exhaust pipe (11).

page_text: The general arrangement of the frame of the engine, the methods of lubrication,
and the construction of the bearings are not novel, but are found from experience to
be suitable.
In Figs. (3) (4) (5) (6) (7) and (8) are shown sections and diagrams to illustrate
the special improvements which I have made in the steam ports.
In order to make clear the difference between my method of arranging the
ports, and thereby improving the oscillating motion, of the piston as compared with
the manner in which the ports in the pistons and cylinders were formerly made, I
have shown in Fig. (7) a cross section of such a piston and cylinder which is
surrounded by an exhaust case, in which (12) is the steam port in the cylinder,
and (13) is the steam port in the piston; while (14) is the exhaust port into the
exhaust casing. It will he noticed that the cored passages are square, and that owing
to their size, the distance between the inlet ports and exhaust ports is considerable.
Owing to the system of admitting and releasing the steam, it is necessary for the
piston to bring the port (13) in line with port (12) in its downward stroke, and then
to partially rotate, so that in the upward stroke, the steam port is in line with the
exhaust ports (14).
.In.order to give this considerable amount of rotation, the crank pin requires to be
set at an excessive angle as shown in the diagram Fig. (8) in which the line (a—b)
*. represents the crank, while (e-) is the axis of the crank shaft.
In Fig. (5) is shown a cross section of both pistons and cylinders in the double
cylinder engine, as I make them. The cylinder on the (B) side represents the piston
at that point of its stroke when it is exhausting the steam into the crank case (7);
while the (A) side, shows the piston with its ports in the position for receiving the steam.
In Fig. (6) is shown a diagram of the cranks represented by the lines (a-b) and (c-d)
in relation to the axis of the crank shaft represented by the line (e-) in which it
will be seen that the angularity of the cranks is very slight.
This is the result of my improvements in making a number of long and narrow
-ports in the cylinder and piston by means of drilling them to accurate sizes, each of
such-width that the total area of the ports will represent the size of steam area
necessary to develop the power of the engine.
Owing to the ports being reduced in width, and accurately machined in both the
cylinder and piston, it is possible to arrange them closely together; so that the position
of the piston when-the-steam ports and cylinder are in line, is only at a small angle
from its position when the exhaust ports and the cylinder ports are also in line.
The piston is shown separately in Fig. (3) and the cylinder in Fig. (4). There are
eight ports in the cylinder for the admission of the steam and a similar number-for
the exhaust. The steam is distributed to the steam ports in the cylinder (15) by means
of a hollow cover to the cylinder shown at (6) in Figs. (1) and (2). The steam passes down
the ports (15) to the opening shown, and from there it is admitted into the recesses (18) in
the piston as shown in Fig. (3). The steam passes from these ports through passages (17)
into the cylinder. The length of the openings in the cylinder and piston determine
the point of cut-off, which I make in practice at 3 of the stroke. When the piston is
at the bottom of the stroke, the ports at (8) come opposite to the ports (16) in
Fig. (4). These ports open directly into the exhaust casing (7). It will be noticed
that these exhaust ports are placed at a slight angle, this is so as to expose as large an
area as possible on the return stroke of the piston to give as free an exhaust as
possible. The circular motion of the piston in its upward stroke follows nearly at an
angle shown by the exhaust ports in Fig. (4).
In manufacturing the piston in Fig. (3) I pursue the following course.-The
circular ports (17) are drilled down to their full depth after which the openings (18)
are recessed to the proper depth, preferably in what is known as a cotter drilling
machine. These holes are laid out by a suitable indexing apparatus, so that they
are accurately spaced around the periphery of the piston. In like manner I prepe
the ports in the cylinder shown in Fig. (4). The steam ports are drilled a suitable
depth, and the openings (19) are recessed through the cylinder by a cotter drilling

page_text: After the
machine from the outside. These ports are also laid out by suitable index apparatus,
so that they are accurately divided on the internal surface of the cylinder.
ports (19) are machined through, a ring (20) in Fig. (4) is shrunk on the outside, so
as to effectually close the outside opening of the ports (19) so that the steam is forced
inwardly. In the same manner the exhaust ports (16) are machined through by a
cotter drilling machine, and these are also accurately laid out by suitable indexing
apparatus, so that they are equally divided on the periphery of the cylinder.
The result of this process is, that a cycle of operations of the engine is as follows:-
1st-Admitting the steam. 2nd-Cutting-off the admission at the proper part of the
stroke. 3rd-Opening the exhaust at the end of the stroke and keeping it open on
the return stroke; the full area of the passages is maintained at all times because
they coincide in every position, owing to the accurate divisions of the openings in the
circumference of the piston and cylinders. This method of manufacturing a multiple
number of long and narrow ports in the piston and cylinder for the purpose of
reducing as much as possible the angle of the crank, and the small amount of
rotation of the piston constitutes the essential features of my improvements in this
class of engines. I apply this method of manufacture of the steam ports also to the
general construction of compound engines with cylinders arranged for high and low
pressure. An engine arranged in this manner is shown in Figs. (9) (10) and (11).
The cylinders are of different diameters and are proportioned according to the
standard rules for compound engines, varying according to the steam pressure used.
The steam is admitted and exhausted from the high pressure cylinder in exactly the
same manner as described in the simple form of engines in Figs. (1) (2) and (3).
The exhaust casing referred to as (7) in Figs. (1) (2) and (3) is in the compound
engine made stronger, so as to act as a steam receiver for the steam released from the
high pressure cylinder. It is then admitted into the low pressure cylinder by ports
arranged in the manner already described for the simple engine, and is exhausted
through ports in the cylinder, and collected together in the cylinder cover of the
low pressure cylinder, and from there discharged to the atmosphere.
The novelty of the arrangement of the compound engine consists in the method of
reversing the direction of the steam in the ports in the low pressure cylinder as
compared with the direction of the steam admitted to the high pressure cylinder.
In Fig. (11) the section through the low pressure cylinder shows the ports in the
piston and cylinder in the position they occupy when the steain is being exhausted
into the atmosphere, the direction of the steam being indicated by the arrows.
The design of the compound form of the engine is similar to that of the simple
engine. I have not described the details of the compound engine in Figs. (9) (10)
and (11) because the corresponding parts are similar in arrangement to the simple
engine shown in Figs. (1). (2) and (3), and will be sufficiently clear to anyone
acquainted with this form of engine.
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
1st. In a single acting engine with one or more cylinders having the steam
admitted and exhausted by a partially rotating piston, the method of arranging and
constructing the ports for admitting and exhausting the steam for the purpose of
reducing the angularity of the crank, substantially as described.
2nd. In a compound single acting engine provided with high and low pressure
cylinders arranged with two or more steam cylinders and having the steam admitted
and exhausted by a partially rotating piston, the method of arranging and constructing
the ports for the purpose of reducing the angularity of the crank, substantially as
described.
Dated this Twenty-third day of December 1890.
GEO. RICHARDS.