Improvements in or relating to Steam Engines.
Year: 1890

page_text: Date of Application, 25th Mar., 1890–Accepted, 26th Apr., 1890
COMPLETE SPECIFICATION.
Improvements in or relating to Steam Engines.
A communication from JAMES BROWN STANWOOD, residing at Corner of Auburn and
Eden Avenues, Cincinnati, Ohio, United States of America, Mechanical Engineer.
I, ALFRED JULIUS BOULT of 323 High Holborn, in the County of Middlesex,
M.I.M.E., 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:-
This invention relates to that class of steam engines employing two or more steam
distributing valves each having a separate and positive actuating mechanism; its
object being to bring the entire operation of the valves under the control of a common
governor. The invention is applicable not only to automatic cut off engines where
the distribution to and from a single cylinder is effected by an ordinary controlling
valve or valves, and a cut-off valve or valves, but also and more particularly to engines
having one or more cylinders and pistons operating cranks upon a common shaft.
An important illustration of the last mentioned type of engines to which the inven-
tion is particularly applicable is the modern compound engine, where the steam
exhausted from a high-pressure cylinder is utilized at a lower pressure in one or more
secondary cylinders.
Heretofore the principle of governing automatically the steam distribution in
response to variations of load upon the engine has been applied in various forms.
But in no case, so far as I am aware, have two or more valves operated by distinct and
positive connecting mechanism from the main shaft, been brought under the control
of a common governor. By way of illustration of the approximations to this result it
may be mentioned that engines employing two cylinders have been constructed with
their cranks occupying the same or opposite radial planes, in order that the valves might
be actuated by a single eccentric in the same or in opposite directions and controlled
by a single governor.
Obviously this construction forfeits one of the greatest advantages of coupling two
cylinders to the same crank-shaft that is to say, the advantage of placing cranks ninety
degrees apart to avoid dead centres, and is inherently limited to an engine of two
cylinders and therefore cannot be applied to one of three cylinders with cranks at
one hundred and twenty degrees apart.
Another example though perhaps less pertinent is the case of compound engines of
the Corliss type in which the releasing mechanism of the admission valves only is
brought under the control of the governor. There being serious difficulty in
constructing two governors having precisely the same action, or to maintain them
in operation always in exactly the same adjustment, it is obvious that the action of two
governors in regulating the distribution of steam can never be as effective and uniform
as that of one and the same governor.
This invention obviates these difficulties, and is not subject to the limitations.
referred to. It governs the distribution of steam both as to induction and eduction,
by controlling the operation of the valve or valves at the fountain head of its or their
motion, and gives to each valve its independent actuating eccentric thus leaving the
designer free to give to each valve its appropriate motion; yet controls the position
of both eccentrics so as to respond in unison to variations of load.
The advantages of the improvement are more especially realized in compound
engines whether of two or more cylinders.
For in these where a receiver is employed and the distribution valves are controlled
by one governor and one positive valve operating mechanism, the point of cut off is
varied by varying the travel of the valves, which is attended by varying times and
degrees of compression. This of course is a serious detriment to the distribution of

page_text: steam to the high pressure cylinder, for in such case the compression in combination
with a high receiver pressure may vary from an excess of the initial boiler pressure
to the opposite extreme. It is for this reason, among others, that notwithstanding its
advantages in other respects the receiver has been in many cases abandoned, and a
single valve employed combining the functions of an initial governing valve, and an
expansion valve arranged to cut off at the expansion cylinder simultaneously with
compression in the high pressure cylinder. This latter construction, however,
introduces disadvantages of another kind; for example, leakage without that utiliza-
tion which is had in the receiver type, for there are intervals when the single
valvo forms the sole partition between high pressure steam and the exhaust passages;
also, varying conditions of pressure in the passages, which destroy the heat equilibrum,
and produce loss by condensation.
These objections also, are overcome by this invention; for by controlling two
distinct valve motions by one governor each valve motion can be designed to produce
its own variations of cut off independently, to produce the greatest efficiency of
action; and the simultaneous governing control insures the preservation of the
proper relations between them at all times.
Mechanism embodying this invention in its preferred form is illustrated in the
accompanying drawings, in which:
Figure 1 is a plan view of a two-cylinder compound engine to which the invention is
applied in the form of a centrifugal shaft governor, showing the cylinders and the
valve chests in section.
Figure 2 is a side view of the centrifugal governor, detached.
Figure 3 an edge view of the centrifugal governor with part of the pulley-rim
removed to exhibit tho eccentrics and connections.
Figure 4 a diagram of the cranks and eccentrics at 90 degrees apart showing their
relations.
Referring now to the drawings exhibiting a preferred form of the invention;
A designates the governor pulley or casing which is centred on the main shaft S of
the engine between the driving cranks xy. The governor pulley A is cast with two
sets of spokes a a¹ with a free radial space between for the play of the centrifugal
arms B B which are pivotally held in lugs at the inner side of the rim (or
between adjacent spokes) and controlled by spiral springs s s' secured and operated
in the usual manner.
The eccentrics CC are formed with or attached to arms D D' respectively pivotted
at or near the rim 90 degrees apart, as shown. The eccentrics are "split" for
convenience of attaching to or detaching from the shaft in the usual manner of such
constructions and are each provided with an elongated arc-slot the width of the
shaft S described by radii from the pivotal axis of the arms D D respectively, to
permit the necessary amount of side play upon the shaft S which passes through the
slots.
The arms B B are furnished with weights ww¹ at their extremities for centrifugal
action in opposition to the springs ss. Each of the arms B B₁ is connected by a
pair of links E or E' with a pair of plates F F¹ centred loosely on the shaft S each
pair of links connecting plates with one of the centrifugal arms, the two sets of con-
nections being at diametrically opposite points of the plates so that the action of the
centrifugal arms rotate the plates in unison, and the plates control the position of the
eccentrics by the connection about to be described.
Each plate is connected with its adjacent eccentric by a short link which for
convenience is constructed in the form of a small disc c rotating in a circular aperture
in the body of the main eccentric and eccentrically pivotted by a pin p to the adjacent
controlling plate. The parts and connections described, are all duplicates placed at
opposite sides of the pulley or casing A except that the centrifugal arms, weights,
and springs are in the central plane of the pulley at opposite sides of the centre.
In the present illustration of the invention the driving cranks of the engine are set
at 90 degrees apart radially; in which case the swinging arms D D' are placed at
corresponding angles and the eccentric slots are likewise formed for the adjustment of

page_text: the respective eccentrics across the shaft substantially at right angles as indicated in
the diagram, figure 4.
Thus o, x and o, y are the crank lines and x, o, y the angle of divergence between
the same while , o and , o are the lines of extreme throw of the eccentrics
and v, o, the angle of divergence-the adjustment of the eccentrics taking place
substantially at right angles to the respective cranks.
In figure 1, I have shown the application of the invention to two cylinder engines,
to wit: a compound steam engine having high and low pressure cylinders G G¹
placed side by side with valve chests and an intermediate receiver & placed between
the cylinders. The valves, in the form of plungers or pistons L L upon the valve
rods operate between the receiver and the steain passages d and exhaust
passages e in the usual manner and the valve rods are coupled by connecting rods r
and yokes t t to the eccentrics C C respectively, in the usual manner.
The general relations of the parts is fully shown in the drawings.
The extension of the invention to three or even four cylinder engines involves only
simple mechanical operations and I have not thought it necessary to illustrate it here ;
but it should be understood that in practically applying this invention to such uses
two or more governors in structure may be combined into one by a rigid connection
compelling their single operation as one device.
Having now particularly described and ascertained the nature of the said inven-
tion and in what manner the same is to be performed as communicated to me
by my foreign correspondent I declare that what I claim is
:-
1. In an automatic cut-off steam engine the combination of two or more distributing
valves, two or more distinct and positive valve-operating mechanisms, and a single
governor mounted upon and operated by the main shaft, substantially as set forth.
2. In an automatic cut-off steam engine, the combination of two steam distributing
valves, two distinct and positive sets of operating connections, two adjustable valve-
movers driven by the main shaft and a centrifugal governor, mounted upon and
operated by the main shaft, and connected with both valve-movers and simultaneously
controlling the position of the same, substantially as set forth.
3. In an automatic cut-off steam engine, the combination of two distributing valves,
two distinct and positive valve-operating mechanisms, two shifting eccentrics, each
independently adjustable and controlling the operation and position of one of said
valves, and a centrifugal governor connected with and controlling both of said
eccentrics simultaneously, substantially as set forth.
4. In an automatic cut-off steam engine, with two or more main cranks driving
cylinders and connections, each of said cylinders having a steam distribution valve
and independent driving eccentrics and distinct and positive operating connections
with said valves respectively, a centrifugal governor connected with and simultaneously
controlling two or more of said eccentrics, substantially as set forth.
5. In an automatic cut-off steam engine, having two or more cranks and driving
connections, a centrifugal shaft governor, in combination with two adjustable valve-
operating ecrentries arranged one at each side of said governor and connected in
common with the centrifugal arms of the governor and adjusted in union thereby,
substantially as set forth.
6. The double centrifugal governor embodying two shifting eccentrics carried upon
pivotted arins, one at each side of the governor pulley or casing, two controlling
plates or cranks pivotally connected at diametrically opposite points with the
centrifugal arms of the governor, and eccentrically connected with the adjacent valve-
moving eccentrics or their carrying arms, substantially as set forth.
Dated this 25th day of March 1890
W. P. THOMPSON & BOULT,
Agents for the Applicant.