IMPROVEMENTS IN AIR ENGINES
Year: 1858

page_text: LETTERS PATENT to Maurice Sautter, of Paris, Boulevart Montmartre, 14,
for the Invention of "IMPROVEMENTS IN AIR ENGINES."-A communication
from Mr. Joseph Gill, resident at Marsala (Sicily).
COMPLETE SPECIFICATION filed by the said Maurice Sautter at the
Office of the Commissioners of Patents, with his Petition and Declaration,
on the 12th October 1858, pursuant to the 9th Section of the Patent
Law Amendment Act, 1852.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, MAURICE
SAUTTER, of Paris, Boulevart Montmartre, 14, do hereby declare that the nature
of the Invention for "IMPROVEMENTS IN AIR ENGINES," communicated to me from
Mr. Joseph Gill, resident at Marsala (Sicily), and in what manner the same
is to be performed, to be particularly described and ascertained in and by the
following statement thereof, reference being had to the Drawing hereunto
annexed, and to the figures and letters marked thereon, that is to say:-
The practical difficulties of employing hot dry air as a motivo agent have
prevented the air engine from coming into use. To avoid these difficulties in
the improved air engine, I use moist air as the motive fluid, and employ an
injection of steam to heat and at the same time saturate it with moisture,
and an injection of cold water to absorb and remove such portions of the heat

page_text: as the so called regenerator may not recover. One form of the engine is
shewn by Figure 1, which will be observed to resemble Stirling's well-known
arrangement (1827) as regards the general action of the differential air vessels
and transferring plungers with their regenerators. The twin air vessels a, a',
communicate from above by the passages b, b', with the working cylinder c, the
piston of which transmits its effect as usual in such cases. The hollow air-
tight plungers d, d, move freely in the vessels a, a', but with as little windage
as possible, so that by moving up and down in the vessels they displace and
transfer the air or other elastic fluid contained in them from one end to the
other, causing it to pass through the central passages e, e', of the plungers,
the upper parts of which are enlarged, and contain wire gauze or equivalent
metallic arrangement, presenting extensive surfaces with numerous small
interstices in short respirators. The proportion between the differential vessels
and the cylinders should be such that the stroke or traverse of the plungers
will displace a quantity of air at least equal to the aggregate contents of the
cylinders and passages. Cold water for the injection is supplied rather in
excess by a pump (worked by the engine) the air vessel of which fallows the
excess of water to escape through a loaded valve by which the pressure in fis
regulated so as to be greater than the pressure which may oppose the play of
the injection in the vessels a, a', which takes place at proper intervals through
the tubes and cocks g, g', as described below. The warm water is discharged
from the vessels a, a', through the pipes h, h', closed above with valves opening
inwards, and below with valves opening outwards; these upper valves are
attached to levers (as shown in the Figure) actuated by the floats k, k', which
move freely up and down over the central injection pipes, and by means of
slings attached to the forked ends of the levers, raise the valves when the
surface of the water which buoys them up rises above the established level. A
steam pipe with throttle valve and regulator (as in the steam engine) conveys
steam from a boiler to the engine through the branch pipes and cocks 1, P.
The plungers d, d, are suspended in equilibrio from the extremities of the
beam m, actuated by an excentric n at right angles with the crank, so that
the simultaneous traverse of the plungers in opposite directions takes placo
(like the motion of the common slide valve of the steam engine) when the
piston is near the extremities of its stroke. When the engine is in action the
upper parts of the differential vessels are hot and their lower parts cool. The
Figure shows the piston ascending by the expansive pressure of the hot air
from a, entering beneath it through the passage b, the pressure above it being
comparatively diminished by the contraction of the air in a', which now
occupies the lower or cold part of the vessel into which the injection is playing.

page_text: с
As the piston approaches the top of its stroke the position of the plungers
changes rapidly, and.at the commencement of the return stroke their relative
position is reversed, d' being now depressed and d elevated. At this moment
the steam cock is opened (preferably by a cam or tappet motion from the
piston rod), and the pressure of the steam in the boiler being maintained higher
than the air pressure of the engine, a puff of steam enters a' and mixing with
the air already heated by its upward passage through the respirator, gives it
more heat and at the same time moisture from the accompanying conden-
sation; tho steam admission closes after the piston has performed a short part
of its stroke, the shutting off of the steam being variable at pleasure as in
expansive steam engines. Meanwhile the hot air which had effected the up
stroke will have passed down through the respirator e into the condenser, part
of a giving up part of its working heat and moisture to the wire gauze, &c.,
and the remainder to the injection water now entering through the cock g,
which has just been opened by the engine motion and is kept open during an
internal of to of the revolution of the crank. Thus the difference between
the cold pressure on one side of the piston and the hot pressure on the other
is the motive force which actuates the machine. On reversing the motions, in
anticipation of the return stroke, the cold air returns upwards through the
respirator, where it recovers part of its previous heat and moisture, the
remainder required to make up the initial quantity being given by a corre-
sponding admission of steam sent in as above described, and so the action of
the engine continues as long as steam and cold water are supplied in sufficient
quantity. The engine works a force pump for supplying air to make up for
leakages in the machine. This pump is worked at intervals, or by varying the
length of its stroke according to circumstances it may work continuously
according to the wants of the engine; the engine also actuates the boiler feed
pump supplied from the condenser water. To insure the passage of the air
or the greater part of it through the respirators, I sometimes put a zone of
light packing round the lower part of the plungers, or by lengthening the
differential vessels below the level of the floats and also the lower open parts
,, of the plungers, so that their inferior edges may always be under water
I obtain a hydrostatic packing (as in the telescopic gasometers) which is, of
course, air-tight, with but trifling friction.
To obtain more power with a given size of engine, compressed air should be
used as proposed by Sterling and Erricson more than 20 years ago, and thus
also the proportion of steam to the air is diminished. As with the improved
method of working with moist air there is no objection to the presence of
water in the machine on the score of its producing vapor, a stratum of water

page_text: on the piston will keep it air-tight at least during the down stroke, and it may
in fact work altogether under water, so as to be air-tight with very little
friction. An arrangement of the engine, including this feature, is shewn by
Figures 2, 3, 4, and 5, in which the cylinder is horizontal. The letters of
reference corresponds in these Figures. The differential vessels o, o', are
vertical, and have plungers with respirators as in Figure 1. These plungers
do not move simultaneously during their entire stroko as in the former case,
and therefore they are counterpoised independently by the weights p, p', acting
by chains over the pulleys r,, the weight of the plungers preponderating
sufficiently to cause their descent by gravity when unopposed. The axis s
carries the double beam t, t', with sectors (like the beam m, Figuro 1), from
which are slung by chains the cross-heads v, v, through central apertures, in
which the suspending rods of the plungers work freely. On the inner extremity
of the axis s is fixed the lever w, actuated through the connecting rod x, by
the crank y, which revolves in equal times with the main crank, through the
bevil wheels a, a', but with motions at right angles. The cylinder is con-
veniently constructed, as shewn in Figure 4, with a surrounding envelope,
separated into two distinct compartments by the central partition 6"; the
base c, Figure 8, is also separated into two equal compartments, as shewn by
the dotted line, so that the water may fluctuate from each differential vessel
to the cylinder and back again without interruption. The quantity of water
remaining permanently in the machine should be sufficient to keep the cylinder
always full of water. The pump supplies cold water to the vessel el,
(corresponding to f, Figure 1). The extremities of the crosshead" work the
nir compressing pump and the boiler feed pump. The crank y corresponding
to the eccentric n, Figure 1, changes the position of the plungers for the
alteration of temperature of the air in the differential vessels by allowing
them to descend alternately by gravity through a space equal to their traverse
as described of Figure 1, when they come in contact with the surface of the
water in the differential vessels, and remain floating on it while the cross-
heads v, v, continue to descend through a further space corresponding to the
descent of the plungers with the falling surface of the water which passes into
the cylinder as the piston recedes. Meanwhile this descent of either plunger
brings the fixed button on the top of its suspending rod into contact again
with the crosshead, which, anticipating the piston's action for the next stroke,
draws it up again. As with this arrangement the level of the water in
the differential vessels varies considerably by the addition and subtraction of
a cylinder full at each stroke of the piston, and the floats " are consequently
submerged part of the time during which the exit valves are fully open, and

page_text: the escape of water might be excessive, the cock g" actuated by the engine
prevents this by remaining closed while the float is submerged, and open for a
certain interval when the water in the corresponding vessel is about its lowest
level, the aperture being sufficient to allow the escape of the injection
water during this interval. The floats are prevented by stops from rising
too far.
The main features of the Invention are the employment of moist air instead
of dry, as hitherto used in air motive engines, and the injection of steam to
give heat and moisture to the air, also the injecting of cold water to remove
such portion of the heat as the respirator may not recover. Some specific
peculiarities of arrangement in the mechanism are intimately connected with
the main principle, as, for instance, the piston working under water, and the
hydrostatic packing of the differential plungers, which would not be practical
with dry air; but generally the arrangement of machinery for applying the
principle may vary considerably as seen in the steam engine. It should be
observed that, although an excess of steam may be sometimes used to modify
and increase the pressure, yet in general it is not intended that the engine
should be worked by a mixture of air and steam, but by air saturated with
moisture in all the varying conditions of pressure and temperature which it
undergoes in the action of the engine. This distinction is important, for
though hot air saturated with moisture might in the common language of
physics be called a saturated mixture of air and steam, it is not so strictly
speaking, but merely air fully charged with moisture, like damp air at common
atmospheric temperatures; it is a mixture of air and steam only so far as the
steam may be in excess.
In witness whereof, I, the said Maurice Sautter, have hereunto set my
hand and seal, this Seventh day of October, in the year of our Lord
One thousand eight hundred and fifteoight
Witness,
T. BASSET.
MAURICE SAUTTER. (L.S.)