IMPROVEMENTS IN STEAM ENGINES
Year: 1876

page_text: <<
LETTERS PATENT to Benjamin Joseph Barnard Mills, of the Firm of Harris
and Mills, of 23, Southampton Buildings, in the County of Middlesex, Patent
Agent, for the Invention of IMPROVEMENTS IN STEAM ENGINES." A com-
munication from abroad by Francesco Pasquale, of Stella, in the Province of
Savona, and Pietro Giovanni Battista Zanini, of Diano Marina, in the Province
of Porto Maurizio, both in the Kingdom of Italy.
Sealed the 23rd May 1876, and dated the 8th March 1876.
COMPLETE SPECIFICATION left by the said Benjamin Joseph Barnard Mills
at the Office of the Commissioners of Patents on the 8th March 1876.
BENJAMIN JOSEPH BARNARD MILLS, of the Firm of Harris and Mills, of 23,
Southampton Buildings, in the County of Middlesex, Patent Agent. " IMPROVE-
MENTS IN STEAM ENGINES." A communication from abroad by Francesco Pasquale,
of Stella, in the Province of Savona, and Pietro Giovanni Battista Zanini,
of Diano Marina, in the Province of Porto Maurizio, both in the Kingdom of
Italy.
These improvements have reference to a motive-power engine working with a
double oscillating piston and double cranks, but in order that the same may be
clearly understood and readily carried into effect I will proceed, aided by the
accompanying Drawings, fully to describe the same.
Figure 1 is a sectional elevation of the cylinder, the valve slide, and its eccentric
with accessory parts, drawn on the line V, Z, of Figure 3.
Figures 2 represent two different sections of one of the oscillating pistons to a
larger scale.
Figure 3 is a cross section of the cylinder with its speed regulator and other
parts, drawn on the line X, Y, of Figure 1.
Figure 4 is a plan of the valve of the speed regulator.
Figure 5 represents the excentric with its slide for supplying steam to the engine
when it is desired to work expansively.
Figures 6 represent a plan and elevation of a balanced slide, relieving it of the
pressure of the steam on its working face.
Figure 7 is a front elevation of the engine complete; Figure 8, a side elevation
of the same.
And Figure 9 is a detached front elevation of the regulator shown in Figure 3,
[Price 6d.]

page_text: but with the addition of a double-acting pump, which can be worked either by air
or water.
The following is a description of the general construction and mode of working
of the engine: The steam enters the slide box nozzle, Figure 1, and from thence
passing through the port b it enters the cylinder a successively by the two port-
holes c and c (the latter being ent through the oscillating piston shaft f), and acts
on opposite faces of the wings g and g¹ of the piston, causing them partially to
rotate simultaneously in the same direction in the cylinder. When this stroke,
consisting of a partial rotation or oscillation, is completed, fresh steam is admitted
in a similar manner on the other faces of these wings by the ports c¹ and c², whilst
ports are opened for the escape of the steam previously used, and thus an alternating
oscillating motion is obtained. c, c, are blow-off cocks adapted to the cylinder;
,, are diaphragms serving to separate the chambers in which the wings of the
piston oscillate. When the latter, impelled by the steam admitted through the
port b, arrive near the ports and c¹, the slide j closes rapidly the port b, and
consequently opens the port b¹, and then the steam entering by the ports c and c³
forces the wings g, g', to oscillate in the opposite direction. This rapid action of
the slide ȧ is due to the form of the excentric d, Figures 1 and 8, which is keyed on
main shaft h, and which acts alternately on one of the friction rollers i, i, attached
to the rod i, thus imparting to this rod a rectilinear to-and-fro motion, which is
transmitted to the slide by levers i³, i³, 17, 1º, i¹¹ (see Figure 8), jointed at ³, i, ³,
and is the stuffing box, and the slide rod.
To prevent the waste of steam, and more particularly the passage of the steam
from one chamber of the cylinder to the other, the wings g, g', of the piston are
constructed as follows, and as shewn at Figures 2:-The conical part thereof is
slidden in the boss of the cylinder shaft f, and there firmly fixed by a key inserted
at g (see Figures 2), so as to form a solid and an air-tight connection. Within
each wing g, g¹ of the piston is placed a packing piece of a trapezoidal shape,
the sides of which are accurately adjusted to the cylinder covers, and the outer
extremity of each to the inner diameter of the cylinder. This packing, which
answers the same purpose as the piston rings in an ordinary engine, is ground in
the wings, and is provided externally on one face with a packing piece g³, and
above this a thin plate g, which is attached to the wing by a sufficient number of
screws. Two spiral springs g³, g, constantly push this packing piece against the
inner diameter of the cylinder, and consequently laterally against its two covers on
account of their trapezoidal shape, and for the same reason when advanced to
compensate the wear this packing will always remain tight. In the same manner
the diaphragms k, k, are provided with two gun metal packing pieces,, which
are pushed against the boss f¹ of the cylinder shaft f by two spiral springs, with
the view of preventing steam from passing from one chamber to the other, and
again for the same purpose within the cheeks or cylinder covers a¹ (see Figure 3)
are boxed two gun metal rings l, l, having the same diameter as the boss f¹ on the
shaft, and by means of small screws or of springs they are made to adhere closely
to the boss aforesaid.
The jacket a (Figures 1 and 3), which is cast with the cylinder is supplied with
steam from the boiler for the purpose of maintaining the heat in the cylinder.
a³, a³, (Figure 3) are two stuffing boxes to prevent leakage of condensed steam,
which might occur at these places after the engine has been at work some little
time.
m² is a valve situated on the exhaust passage m. The exhaust steam raises this
valve, and passing through the parts m², m², Figure 4, cut out of this valve raises
the piston m³, on which is fixed the rod m. This mechanism constitutes the speed
regulator. The rising and falling of the piston m³ conjointly with the parts m, m
m, m7, m³ (see Figures 7, 8, and 9), imparts a rotary motion to the throttle valve me,
and thus controls the admission of steam from the boiler to the slide j. When the
oscillations of the winged piston increase a larger quantity of steam passes through
the exhaust pipe, and consequently an increase of pressure therein raises pro-

page_text: portionally the piston m³ to the extent of entirely closing the throttle valve m³,
whereon the speed diminishes, the piston m³ redescends, and the throttle valve m³
is thereby reopened. The steam and condensed steam or water escape through
holes drilled in the valve m¹ around its rod m. m10 (Figure 7) is a spring with a
regulating screw m¹, which serves to regulate the speed at which the engine is
intended to work by means of the resistance it opposes to the rising of the
piston m³.
At Figure 9 is shown a further improvement to this regulator, consisting in the
addition thereto of a double-acting pump n actuated by the engine, the piston of
which, shewn in dotted lines, is worked by a rod n¹ from below, and which is
provided with two valve boxes n², n², and with pipes n³, n³, for conducting the water
or the air to the regulator, a regulating cock n', a handle no, and an indicator ne fitted
on the plug of this cock, and a dial plate n', on which are inscribed the revolutions
to be imparted to the engine, which are regulated according to the extent to which
the said cock is opened. According to the varying speed of the engine this double-
acting pump forces a varying quantity of air or of water into the lower part of the
regulator, by which the piston m³ is raised if the quantity increases, whereas the
spring m causes it to descend if the quantity decreases. The cock n' allows the
escape of the fluid in quantities varying to the extent to which it is opened. When
the piston m³ rises it partially closes the throttle valve m³ by means of the rods
and levers above mentioned, and thus intercepting partially the supply of steam to
the engine diminishes its speed, but under these actions, the action of the pump n
being also less, the spring m2 acting against the piston m³ lowers it, and thereby
reopens the throttle valve mº. The divisions on the dial indicate the actual speed
of the engine obtained by experiments, according to the extent to which the cock n'
is opened, and when it is required to run the engine at a given speed, all that has
to be done is to turn the handle n³, and consequently the plug of the cock until the
indicator n is placed over the figure on the dial corresponding to the said speed.
m is a small safety valve kept down by a spring, and m¹ the aperture supplying
air on the upper face of the piston m³.
The oscillating motion of the engine shaft f working in blocks f, is by means of
the crank, the connecting rod f, and the crank o¹ converted into a continuous
rotary motion imparted to the driving shaft o rotating in the blocks o², and provided
with a fly wheel o³ and a pulley o' for transmitting the motion for any industrial
purpose. p represents a cock which supplies the engine with steam from the
boiler.
For the purpose of reversing the engine a link i̇ (see Figure 8) is employed,
which is attached to the axis ix of the lever i³, and provided with a curvilinear
slot having the same radius as the rod 7. In the curvilinear slot is placed a bearing
with a toothed segment 12, and in the centre of the bearing there is a hole in
which the axis of the rod is passed. The handle is made to rotate the
pinion gearing into the rack 2, which is thus lowered or raised as required.
This motion is of necessity imparted to the rod i, which falls or rises in the link i³.
Thus the working of the slide is changed, and the direction of the engine reversed.
9 (Figure 8) is a crank attached to the oscillating shaft f for the purpose of
operating the feed pump 7 by means of the rod 23; is the valve box, and the
suction cock.
Figures 6 shew an elevation and plan of a mode of arranging the slide so as to
free it of the pressure of the steam on its back. j represents the slide itself, the
outer face of which is circular, and on which is placed a ring j³, ground with emery
so as closely to fit thereon, and provided with a central hole j; above is placed a
plate mounted on four feet 77 screwed into the cylinder face; ³, ³, are small oil
holes. The steam on entering the slide box presses on the foot of the slide, and at
the same time against the plate j, preventing the pressure of the steam being
exerted on the central part of the slide. The hole is made for the purpose of
allowing the impurities to pass from the two working faces, and thus ensure easy
motion of the slide.

page_text: The pressure (which is completely lost in the waste pipe of existing engines) is
utilised in this engine for working the regulator.
This arrangement of slide valves works equally well in all positions, and is there-
foro specially applicable to locomotives and to marine engines.
The following advantages result from these improvements,―
Firstly. No steam is lost or wasted in its working.
Secondly. Simplicity of construction and facility of driving.
Thirdly. Increased power from a given quantity of steam.
Fourthly. Diminution of volume and space occupied, which render these engines
specially applicable for marine purposes.
In existing steam engines the conversion of the reciprocating rectilinear motion
of the piston into a rotary motion gives rise to a great loss of power, to avoid
which many attempts have been made to construct rotary engines. This engine
differs from rotary engines by the oscillating motion of its piston or pistons with
their axis. It is by the natural effect of this oscillating motion that power is
acquired in this ongine without the loss experienced in engines with a rectilinear
acting piston; for as the fly wheel crank approaches the dead centre, and there
loses part of its power, the piston crank augments its own, so that the loss of power
in the one is compensated by the increase of power in the other. By means of this
compensation the pistons act with an equal and constant power on the fly wheel
shaft, excepting two dead centres, which being however separated by an arc of
170 degrees are thus insignificant, and need not be taken into consideration.
The almost instantaneous action of the slide is also a source of power, for it is
well known that in existing engines much power is consumed and a certain pro-
portion of the steam wasted.
Having thus explained the nature of the said Invention, and the best known
means for carrying it into effect, I would have it understood that what I claim is,--
Firstly. The arrangement and construction of the double oscillating piston with
wings g,g, with metallic packing pieces g³, g³, g, and springs g³, g³, acting in manner
substantially as herein shown and described.
Secondly. The arrangement and construction of the cylinder a with its dia-
phragms, , and packing pieces k, l, substantially as herein shown and described.
Thirdly. The slide as constructed with reference to Figures 6, with the parts j*,
,,, substantially as herein shown and described.
Fourthly. The arrangement and construction of parts d, i, i¹, 2³, i³, i³, 2º, 2¹¹,
(Figures 1, 7, and 8) for the purpose of transmitting motion to the slide valve, sub-
stantially as herein shown and described.
Fifthly. The arrangement and construction of parts i³, 12, ¿¹³, 1, Figure 8, for the
purposes of reversing the engine, as described.
Sixthly. The arrangement and construction of the parts p, m³, m³, m³, 5º, m³,
m³, m³, conjointly with the spring m⁰ and the regulating screw m", Figure 7, for
the purpose of regulating the speed of the engine."
Seventhly. The combination with the said regulator of the cylinder n and piston
acting therewith with the parts n¹, n³, n³, n³, n³, nº, n, substantially as herein
shown and described.
And, Eighthly. The arrangement of the two cranks f³ and o¹ with the connecting
rod f (Figures 7 and 8), for the purpose of converting the oscillating motion of
the piston into a constant rotary motion of the driving shaft.
In witness whereof, I, the said Benjamin Joseph Barnard Mills, have hereunto
set my hand and seal, this Eighth day of March, in the year of our Lord
One thousand eight hundred and seventy-six.