MENTS IN HOT AIR' OR CARBONIC ACID ENGINES
Year: 1881

page_text: PROVISIONAL SPECIFICATION left by Peter Jensen at the Office of the
Commissioners of Patents on the 25th April 1881. A communication from
abroad by Moritz Honigmann, of Grevenberg, near Aix-la-Chapelle, in the
German Empire.
PETER JENSEN, of 33, Chancery Lane, in the County of Middlesex. "IMPROVE
MENTS IN HOT AIR' OR CARBONIC ACID ENGINES." A. communication from
abroad by Moritz Honigmann, of Grevenberg, near Aix-la-Chapelle, in the German
Empire,
The leading features of engines constructed according to this Invention are as
follows: The employment of high pressure, say four to ten atmospheres, the
heating of compressed air by direct influence of this air on the glowing fuel, that
is, by direct combustion under pressure, the action of the hot high pressure gases
of combustion mainly by expansive force on the acting piston and the proportioning
of the acting piston area to about three times that of the air compressor piston
which corresponds to a temperature of about 600° C. (1,112° F.)
The piston of the cylinder is formed with a trunk, and is of such a diameter
that its bottom area is about three times that of its upper or annular area. The
upper or annular part of the cylinder forms or contains the air compressor with
self acting suction valve and delivery valve; the bottom part of cylinder forms
the motor part, and has an inlet valve and outlet valve; the latter will open by
means of a spring when the hot air admitted by the former has expanded. The
inlet valve is opened by means of gear from the engine shaft, and is closed
by 1 to 10 of the piston stroke. The cut off is regulated by a handwheel on a
screw, so that when the wheel is turned down it compresses a spring and thus closes
the valve; after the valve has been closed the wheel glides past the spring. The
valves are in the form of a thin steel or iron disc welded on to a stem having a
deep guide. The combustion chamber or furnace in which the compressed air is
heated. to 400°-800°C. (750°-1,470° F.) is a wrought iron chamber having a
furnace grate below and lined with fireproof material. There is a charging
appliance at top arranged to charge with fuel without diminishing the pressure;
for this purpose it is formed as a vase or hopper having a cover at top and a cock
below; this vase having been filled with the fuel (such as coals, cokes, or wood)

page_text: the cover is put on; the cock is then opened and the charge drops into the furnace.
The furnace has also at top an outlet for chimney; this is used for starting the fire,
and then closed.
In order to watch the combustion there is a sight hole with a strong glass.
A. hand hole door above the grate and another larger door below the same, are only
used when the grate and ashpit are to be cleaned. Instead of the grate a fireproof
slab may be used.
The combustion chamber or furnace is connected with the air compressor by two
pipes, one of them entering below the grate, and the other just above the fuel
thereon.
The engine works as follows:-In the upstroke of the piston the air previously
drawn in through the air compressor suction valve is compressed and forced out
through the outlet valve; it then branches off in two pipes, one leading to the closed
ashpit, and the other, which is surrounded by a pipe or jacket containing the hot
exhaust gases from the engine, and thus is kept heated, leading to the fire box or
space above the grate. The air entering below the grate burns into carbonic acid;
should the carbonic acid, however, by reason of too small a supply, be reduced to
carbonic oxide, then this latter will be burnt by the air supplied by the pipe above
the grate; this latter pipe must consequently have its exit at or near the top of
the glowing fuel, so that the formation of an explosive mixture becomes an
impossibility. The other air supply pipe is of a larger diameter, and has a throttle
valve actuated by the engine governor, so as to close when the engine runs too fast;
hardly any coals are then burnt and only preheated air enters above the grate; in
consequence of the lowered temperature the engine will run slower. The combustion
chamber is of such a size as to correspond with a steam boiler for a steam engine,
that is, so as always to deliver equally compressed air to the working cylinder,
this air passes by a pipe to the hot air admission valve and then under the piston;
there is a pyrometer thereon, say, a copper bar, the expansion of which is shown
on a scale, so as to note the temperature of the hot gases (between 750° and
1,470° F.)
It will be observed that the heat of combustion is almost entirely utilized (which
has hitherto not been attained), because the gases of combustion act directly on
the working piston and the heat of the exhaust gases is partially utilized. This
motor hence uses only about one fifth of the fuel of a steam engine; this is rendered
possible by the complete utilization of the force of expansion and by the automatic
regulation of the combustion. This regulation is rendered possible by the dividing
in two of the compressed air, and this division again is only possible by having the
air entering just above the fire so as almost to touch the fuel. Only in this way
the danger of explosion is avoided.
For small motors, the form of engine bere more specially described is convenient,
the trunk being about 5% of the piston diameter, as the working and air compressor
space thus form one piece or cylinder.
In very large motors it may of course be necessary to make the working
cylinder and the air compressor separately.
The parts of the cylinder are so arranged that the direct mutual conduction of
heat is as much as possible guarded against.