Improvements in. Steam Engines.
Year: 1890

page_text: Date of Application, 29th July, 1890-Accepted, 4th Oct., 1890
COMPLETE SPECIFICATION.
Improvements in. Steam Engines.
1, CHARLES BROWN of 91 Rione Amedio Naples in the Kingdom of Italy 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 consist of
1st. An improved form of balanced rotary valve for distributing steam.
2nd. A supplementary valve for intercepting the communication between low
pressure cylinder and condenser or free exhaust in single acting compound engines.
3rd. An improved form of single acting compound engine, producing the effect of
a double-acting engine.
4th. A peculiar form of self-tightening connecting rod, and crank pin and cross-
head bearings, used in connection with the above type of engine.
Before referring to the two sheets of drawings that accompany this description,
I wish it to be understood that I do not intend to be confined to the exact details
shown therein, as they may be modified without departing from the nature of my
invention.
L
11 11
Figure 7-Section through low and high pressure valves.
Figure 8 -Section through low pressure cylinder and intercepting valve.
Figure 9: Diagram showing period of a revolution during which the intercepting
valve is open.
Figures 10, 11 and 12-Modified form of self-tightening, divided crosshead
articulation, for single acting compound tandem engine.
A. Improved rotary valve notched on the inside with a number of passages for
admitting steam to the steam ports f. f, in this instance of the number of eight a. a,
etc., in communication with the steam chamber E; and on the outside with a corre-
sponding number a¹, a¹ etc. in communication with the exhaust chamber G, for
exhausting steam from the ports f
Revolving with the valve A is the packing ring B, which, moving steamtight
against the cover H, severs the communication between the steam and exhaust
chambers E and G. B is made steamtight with the valve A by the packing ring C. C,
but so that the valve A is free to lift from its seat when water is present.
The ring B is so proportioned, that the valve A is partially relieved from steam
pressure on its back, as the pressure acts only on that area included between the two
circles 1 and 3 and this unbalanced pressure is still further reduced, because it is only
active to a full extent on those parts of the eight cylinder ports f,f,f, etc., and the
eight exhaust notches a', a' etc., which are situated immediately under the pressure
zone included between the circles with the diameters 1 and 3. The unbalanced steam
pressure on the ring B. is restricted to that acting on an area comprised between the
DOJ7

page_text: two circles with the diameters 1 and 2. B is further kept in place by the corrugated
spring h, h, when steam is off.
Valve A receives its motion from the crank shaft by the pinion D, which gears into
the circular rack A³ formed on the circumference of the valve A. The shaft C of
pinion is connected with the crank shaft by any suitable gearing, so as to cause A to
make one revolution to eight of crank shaft respectively, or so many revolutions as
there are steam ports f, f, etc. in the cylinder.
Figure 2 shews the valve in its proper position at the commencement of the stroke.
The ports being already uncovered for the admission of steam by the amount technically
known as the "lead," i.e., the distance by which the edge 4 of the valve A and the
edge 5 of the steam ports f. f, etc. are asunder. As the piston progresses the valve
continuing to revolve in the direction shown by the arrow until the edges 6 of the
eight notches a, a, etc. coincide with the edges 7 of the eight cylinder ports f, f, etc.,
when admission censes.
The notches a', a' control the periods of exhaust and compression, in a similar
manner, opening communication of the cylinder with the exhaust by their edges 8, 8,
etc., passing the edges of the ports 5, 5, and shutting off the same by their edges 9, 9,
passing the port edges 7, 7.
The spacing of the notches a, a, and a', a' and the ports f, f, are so chosen as to
control the periods of admission and exhaust according to the requirements of practice
and theory
Figures 5, 6, 7 and 8 illustrate the application of the above type of valves
to the high and low pressure cylinders of my new single acting compound
engine.
The valve A and its balancing ring B, placed in the space formed between the
covers of the high and low pressure cylinders F and J, are of the same construction
as shown on Figures 1, 2 and 3, the valve A" of the high pressure cylinder with its
balancing ring B is also identical in construction, but in an inverted position, the
valve A working on the underside of the cover of the high pressure cylinder J, and
its ring B on the cover of the cylinder F.
The valve A is further connected with its prototype A, by the carrier luga, and
the noses y, y, the whole revolving simultaneously by the pinion D gearing into the
circular rack A', said pinion being in connection with the crank shaft N as above
described.
The valve A is in all respects similar to the valve A with the exception
that it is furnished on its inner or live steam circumference with an arrange-
ment A for controlling the admission period, technically termed an
cut-off valve."
< automatic
This cut-off valve is held fast in any position by a governor, or by hand within
the limits 10 and 11; the maximum admission is when the edges of each of the
eight openings of the valve A", are shifted into the position 11; and the minimum,
the position 10, supposing the valves A and A" to move in the direction from right
to left.
On Figures 6 and 8 the supplementary valve K is shewn. This valve is in
communication at both its ends with the exhaust passages G, G and rotates with the
shaft C. Its function is to open a communication between the low pressure cylinder F,
and the condenser or exhaust during such a period of a revolution of the engine as
is indicated on the shaded position of the diagram Figure 9. In this case the exhaust
steam leaves the engine by the opening G₁. The period during which the interior of
the cylinder is in communication with the exhaust is limited to about of a complete
revolution, thus reducing the period of the cooling and re-evaporating process,
which is one cause of a useless expenditure of heat in the steam engine, to a
minimum.
Further a difficulty is found in practice in so arranging the compression in high
speed engines that it will suit equally well for an engine which has to work condensing
and non-condensing.
The valve K solves this problem, because when the engine is working with

page_text: condensation during the up and in this case working stroke of the piston J' the
connection with the condenser and cylinder F is cut off.
Therefore the pressure of the steam before and behind the piston F is the same as
at the completion of the stroke, the steam circulating freely above and below the
piston, so that, when the valve A cuts off the exhaust, a sufficient weight of steam is
imprisoned to produce a sufficient end pressure by compression, to absorb the
momentum of the piston F, and its appendages; the crosshead and crank pin
bearings are thus kept up to their work, no reversal in the direction of the forces
taking place, a silent motion is secured and pounding is avoided.
This new type of engine is composed of one single acting high pressure cylinder J,
and one single acting low pressure cylinder F; J gives the impulse during the
upstroke, and F during the downstroke.
Each cylinder has a supplementary exhaust passage Jand F which is uncovered
by its respective piston, near the end of their working strokes, giving a sudden exhaust,
clearing cylinders and pistons of moisture. These passages also prevent undue com-
pression at the end of the working strokes of each piston and form a communication
between both sides of the pistons during the period that the exhaust ports of the
valves A and A" are open, allowing the steam to circulate freely between both sides
of the pistons.
The crosshead bearings and the connecting rods of the tandem single acting
cylinders in the above described type of engine, each give an impulse during each
half of a revolution of the crank, but each in an opposite direction, therefore
any slackness in the crank and crosshead bearings would produce pounding, if
these organs were of the usual construction, the form now to be described will
prevent this.
On Figures
and 6 it will be seen that the piston rod F is hollow and is
connected only with the piston F', and with one half of divided crosshead L. and
one half of the divided connecting rod formed by M, M together with the upper half
of the crank pin bearing O. The pressure downwards of the piston F' keeps these
organs always in compression, there being no reversal in the direction of the force,
this piston and its organs of transmission being in the same condition as any single
acting engine, can be run without the other half of the bearings.
Now the piston rod J", passes freely through the hollow rod F and is connected
with the other and independent halves of the crosshead L and connecting rod M', M'
and the lower half of the crank pin bearing O¹. This piston J" always receiving the
pressure of the steam on the under side, consequently its transmitting organs are
always in tension, no reversal in the direction of force, so that this system can also
work silently and without the other half. In this manner it is evident that any
slackness in the bearings will not produce pounding, the elastic medium always
(acting from below the high pressure and from above the low pressure piston) keep
the balves of the transmission organs in contact with the bearings. When stopping
or starting the elastic medium below and above the pistons being absent, there is
nothing to prevent pounding, therefore the two crosshead halves L and L' are
connected together by the bolts and springs 1, 7 which keep the crosshead and crank
pin bearings in contact until steam is admitted.
Figures 10, 11 and 12, represent a modified form, for the application where the
crank end of the connecting rod is made as usual, i.e., not self-tightening, but the
crosshead end to be self-tightening as it is this articulation which is the most difficult
to keep in order. In this modification the piston rods J, F" are as before,
independent one of the other. The crosshead is also made in halves L and L' and
the halves are made to embrace the connecting rod pin P when the elastic medium
is absent by the bolts and springs 1, 1, as before. It is evident that when the engine
is under steam, the crosshead half L' being connected to the rod J" of the small
piston only, the force acting on the lower side of the pin P is always upwards;
producing tension in the connecting rod, and the upper crosshead half L, being
connected only with the rod F of the large piston the force acting on the upper side
of the crosshead pin P is always downwards or producing compression in the connecting

page_text: rod, it is evident that, also in this modified form of crosshead bearing, each half is kept
in contact with the connecting rod pin P, in the manner before described, for the
purpose of preventing pounding.
By the use of my invention I obtain a very simple and correct mode of distributing
steam, especially adapted for engines running at a high speed.
The cylinder ports being also very short and direct, this mode of distribution
combined with my single acting compound engine, allows the whole of the distributing
mechanism to be included in a space formed between the covers of the high and low
pressure cylinders, giving short and direct passages for the steam between the
cylinders, and involving a very slight drop in pressure and little or no loss from
wasteful radiation, and also forms a very effectual jacket for the cylinder ends.
The intercepting valve reduces the period during which the walls of the low pressure
cylinder are exposed to the refrigerating influence of condenser or exhaust, to a
minimum.
By the tandem single acting compound engine with the peculiar mode of trans-
mitting the power to the crank shaft, an engine is obtained which has the effect of a
double acting engine combined with the advantages of the single acting type of "box
engine," viz., smooth working compactness, and requiring little attention, self-
lubricating, and having no open ended cylinder in direct communication with the
"box room," the lubricant is not spoiled by the condensed water, which always finds
its way past the packings of the trunk piston of this class of engine as usually
constructed.
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 what I claim
is as follows:-
1st. The improved form of rotating balanced slide valve for distributing steam
substantially as herein shown and described on Figures 1, 2, 3, 4, 5, 6 and 7.
2nd. The valve for cutting off communication with the condenser or exhaust for
the purpose and substantially as herein shown and described on Figures 6, 7
and 9.
3rd. The improved form of single acting compound engine for the purpose and
substantially as herein shown and described on Figures 5, 6, 7, 8 and 9.
4th. The arrangement of the organs for transmitting the force on the pistons
in the manner and for the purpose substantially as herein shown and described on
Figures 5, 6, 10, 11 and 12.
Dated this 28th day of July 1890