Improvements in and Connected with Hot Air and other like Engines.
Year: 1889

page_text: Date of Application, 21st Sept., 1889-Accepted, 16th Nov., 1889
COMPLETE SPECIFICATION.
Improvements in and Connected with Hot Air and other like
Engines.
I, BENJAMIN WILLCOX of 47 Lincolns Inn Fields in the County of Middlesex,
Patent Agent, do hereby declare the nature of this Invention which has been com-
municated to me from abroad by Lucien Genty, of Tours in the Republic of France
Mining Engineer 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 certain improvements in hot air motor engines and
although this particular description of motors only is here indicated these improve-
inents are not restricted to those motors as they may be applied to any other types of
engines to which they are applicable; nor do I restrict myself to the precise details
shewn in the accompanying drawings, the same being capable of many variations
without departure from the nature of this invention.
The improvements according to this invention consist in a novel arrangement of the
furnace which enables the fuel to be burnt without the use of a grate and theroby
obviates obstruction in a fuel supply apparatus; in a peculiarly devised piston; in
a novel contrivance whereby dust is prevented from coming into contact with the
portion of the cylinder subject to friction and with the packing; in the arrangement
of the air pump; and lastly a governor for obtaining variable expansion.
The accompanying drawings illustrate a hot air motor engine provided with my
improvements, the same letters of reference designating the same parts in all the
figures.
Figure 1 is a side elevation, Figure 2 a longitudinal vertical section and Figure 3 a
cross section (through the axis of the cylinder) of the improved engine. Figures 34
and 3 respectively are detail views of the valves of the air pump and air distributor.
Figures 4 and 5 respectively are a front view and a side view partly in cross section
of the governor. Figure 6 is a plan view of the same. Figure 7 a detail view of the
cam acting upon the pulley or roller on the lever which operates the admission valve.
Figure 7 is a side elevation and Figure 7B is a detail view on an enlarged scale of
the said cam. Figure 8 is a detail view, also on an enlarged scale, of the device for
forcing pure air between the body of the cylinder and the piston, in order to prevent
dust from reaching the portions of the pision-rings and cylinder, subject to friction,
Figures 9 10 and 11 are detail views, on an enlarged scale, of the fuel supply
apparatus.
The engine operates in the following manner :-
Air is sucked in from the surrounding atmosphere by the pump A and is forced
through the pipe B into the chamber R.
It passes from this chamber, through the valve V and pipe T into the heater E
formed of a number of tubes and heated by the hot gases circulating around the said
tubes. The air heated by passing through the said tubes passes thence through the
pipe or passage 34 to the admission valve D by which it is distributed in the
furnace F.
After being further heated in the furnace the air flows into the motor cylinder
and the piston P thereof is operated upon by the hot gases which thereafter escape
through the exhaust valve G internally lined with fire clay, into the casing of
the tubular heater E and after circulating about the tubes therein are discharged
through the outlet H into the external atmosphere.
I will now proceed to describe in succession the improvements in the various
paris of the motor engine according to this Invention. The furnace is constructed

page_text: with a fire brick lining X enclosed in a metal casing. The fuel is by the arrange-
ment hereinafter described enabled to burn without a grate. The inner walls of
the furnace are so arranged as to cause the fuel to naturally form a declivity 1, 2
Figure 2. This result may be obtained, for example, by means of a contraction 3, 4,
about midway between the top and bottom of the furnace, and by widening its
lower portion (see Figure 3). The air, upon reaching the declivity thus formed, in
the widened part of the furnace, is distributed throughout the mass of fuel, which
presents to it a large open surface, and it is thereby efficiently heated.
By such means the fire bars or grate which, in engines of this description,
generally deinands constant attendance and not infrequently becomes unfit for use
can be dispensed with. The fuel is entirely consumed, without necessitating any
attendance, and the deposit of clinker which forms at the bottom of the furnace,
in no way interferes with the air supply and can easily be removed when the engine
is at rest.
These results are exceedingly important, for the difficulty of keeping up, and
attending to the fire, has hitherto proved one of the main impediments to the more
general use of hot air engines. The furnace may be of a square or rectangular
shape, and the extent of the declivity formed by the fuel will vary accordingly.
The parts in contact with the fuel are lined with an extra thickness of fireproof
material Y. This secondary lining can be formed, either by working through the
furnace door or hole (for small repairs) or by taking the furnace to pieces (when the
whole of the inner or secondary lining is to he renewed). For the latter purpose
the nuts 6, 6, Figure 1 are unscrewed, whereupon the metal case enclosing the furnace
can be removed. Fuel is supplied to the furnace by means of the apparatus shown
at O, in the sectional view Figure 2, and also, on an enlarged scale, in Figures 9,
10 and 11. This apparatus consists of a cylinder K revolving in a semi-cylindrical
piece, against which it is held by two levers N pivotted on the spindle Z and fixed
by means of bolts 21 engaging with the forked tops of the levers N and oscillating
at 22. After a charge of fuel is placed in the space O, a rotary motion is imparted
to the cylinder K either by turning the handle M or by means of gear from the
main shaft. This brings the fuel in front of the channel. U and it then descends into
the furnace.
A hole 39 provided with a glass plate serves for the inspection of the furnace when
the fuel supply apparatus assumes the position above described. To moderate the
action of beat upon the cylinder K, it is protected by a refractory covering at
which is applied in the hollow space provided for the purpose at the part of the
cylinder K which is opposite the entrance of the channel U, when the said cylinder
is in the position shewn in Figure 2 and 11.
To inspect the top of the furnace or the channel U, or to light the fire the
cylinder K should be removed from its position. This is done by simply raising
the bolts 21 from the forked tops of the levers N which levers can then be turned
on their spindles Z. The cylinder K then drops and remains suspended from the
levers N. The apparatus is moved to this position, both for lighting the fire, and
during the periods of discontinuance of operations. The piston P is hollow, and is
provided at its lower portion .e. at the part which comes in contact with the hot
gases
with a refractory covering 7. Its upper end is fitted with segments or packing
rings & forming an air tight packing. At the base of these segments or rings a
groove 9 is provided to admit à current of pure air coming direct from: chamber R
through the flexible tube t, fig. 2.
During the compression and admission of air into the furnace and the expansion,
the heated gas, carrying the dust with it, has a tendency to escape through the
packing, and thereby to damage it and the surface of the cylinder by subjecting them
to friction.
To obviate this the apparatus shewn in Figure 8 is provided. It is shown in
position at the end of the tube in Figure 2. As soon as an appreciable degree
of pressure is reached in the cylinder, the small piston p, (connected by the channel 35

page_text: with the groove 9, underneath the packing)-rises somewhat and thus opens the
orifices o permanently connected with the compressed air chamber R through the
tube t and the compressed air from the said chamber R then passes into the groove 9,
and thence forms a downward blast, towards the furnace, and into the annular
space 9 provided between the piston extension or attachment and the cylinder,
whereby the dust is prevented from coming into contact with the frictional parts
of the cylinder and packing.
At the completion of the upward stroke of the piston P, the exhaust takes place;
and at the same time the piston p is closed by coming against the projection ↳
fixed to the cylinder (fig. 2). The admission of air into the groove 9 is thus inter-
rupted during the exhaust. A spiral spring 10, figure 8, prevents the piston p from
rising during the whole of this period owing to the effect of the counter-pressure
caused by the escape.
The air pump A is arranged in line with the cylinder and is surmounted by a
cover or cap carrying all the suction and delivery valvos arranged in such a manner
as to provide for inspection.
•
The valves may be adjusted whilst in position; or, if desirable, they may be taken
out, after removing the seating A¹ (figure 3). The suction takes place through
valves 40, figure 34, and the delivery through valves 41, the former being accessible
direct. To inspect the valves 41 the plugs 42 will be unscrewed. The governing
device for variable expansion consists as follows:-The main or driving shaft is
provided with a cam e, figures 5 and 6, a plan and side view of which are shown,
respectively, in Figure 7 and 74. It is by this cam that the admission valve is
opened by acting on a roller g. The said cam c'is for this purpose provided with
a series of unequal offsets or steps 11, so arranged that the admission valve always
opens at the same period of the stroke of the piston, but does not close till after
a more or less protracted interval, according as the roller g is rolling on one or the
other offset or step of the cam. The notion of the said roller to bring it into
position over the respective offsets or steps is obtained by its connection with the
centrifugal governor, such connection being formed by the two levers and spiral
spring .
I
As the balls of the governor rise or fall, the bell crank lever turns on its centre 12
and thereby either contracts or expands the spring, which, in its turn, causes the
lever to turn on its pivot 13 and thus carry the roller onto the proper offset or
step of the cam c. The moment the roller g reaches the flat tangential surface 36,
that is, just when it has passed the angle 37 (figures 7 and 74) it is raised and
caused to open the admission valve with which it is connected by a rod 18, figures 1, 5
and 6. When the roller reaches the steps which follow the flat lifting surface 36
(figures 7 and 74) it is caused to engage with one of these steps at a suitable
distance from the edge thereof by means of an inclined surface d e f g (figure 7")
provided at the end of each step which in case the roller tends to run too near
the edge of the step shifts the roller laterally and forces it on to the next step 11,
in the example illustrated the roller being to the left of the line df; as indicated
in Figure 7 but if, on the contrary, the roller g passes to the right of the said
line df, it bears with its whole width upon the stop 11, without risk of slipping off
the edge on to the next step (116) towards the end of the piston stroke.
When the roller g is raised by the cam, it causes the arms 14 to oscillate, which
hold the shaft 16, figures 4 and 6, on which the roller y is mounted to slide. The
arms 14 are connected with the arm 17, figures 1 and 5, which pulls or releases the
rod 18 and thus, through the medium of the bell crank lever 19 opens or closes the
balanced admission valve D. A spiral spring 20 (Figure 1) acts on the lever 19,
rod 18 and three arined lever 17, 14, so as to keep the roller in contact with the cam
whilst the spring 38 tends to keep the valve D closed.
The stop Q, suitably adjusted, prevents the roller g from bearing against the
circular or concentric portion of the can its bearing only taking place when it
meets the projections. offsets or steps 11 of the cam.
The result is that no resistance

page_text: prevents the governor from moving the roller g laterally so long as the latter is not
in contact with the projections of the cam. The expansion may thus be readily
adjusted.
The compressed, and already heated, air, admitted through the yalve D enters the
passages controlled by the valve 23, figure 3B, where it is divided into two currents so
as to pass into the channels 24 and 26 in relative proportions varying according to
the position of the said valve. The air passing through channel 24 enters a
channel 25, figure 1, and flows into the furnace so as to be discharged upon the
declivity of the fuel. The air passing through the passage 26 enters the furnace
above the fuel (figure 3).
The meeting of the two currents ensures the proper combustion of the gases. The
valve 23 is connected to a lever 27 loaded with a weight 28 and acted upon by a
spring 29.
This lever, oscillating on a fixed centre 30, presses against a flexible
diaphragm 31, which is in communication with the chamber and constantly tends
to expand under the pressure which the air exercises upon it. When the pressure
in the reservoir begins to diminish, the said diaphragm accordingly tends to lower
under the action of the weight 28 and spring 29; and this motion of the diaphragm
causes the valve 23 to turn on its axis 32 so as to increase the amount of air
traversing the fuel and thereby to heighten the temperature of the air working the
engine. The reverse takes place as the pressure approaches its maximum.
After the closing of the valve D i.e. after a period of operation under full pressure,
the air previously admitted into the furnace, increases in volume, thus actuating the
motor piston and acting by expansion at the expense of its initial heat and also of
the heat taken up from the furnace.
As shown in Figure 3B the space provided above the upper seat of the valve Dis
placed in communication, by the passage 33, with the space under the lower seat of
that valve, so that the power required for moving the said valve is reduced to a
minimum.
Having now particularly described and ascertained the nature of the said inven-
tion and in what manner the same is to be performed I declare that what I
claim is
1. In hot air or other motor engines the arrangement for enabling the fuel to he
burnt without a grate and consisting in so constructing the furnace that the fuel
forms a declivity, offering a large surface to the inflowing air, in the lower enlarged
portion of the furnace substantially as herein before described.
2. In furnaces for hot air engines an improved fuel supply apparatus, substantially
as herein before described and illustrated on the accompanying drawings.
3. In hot air or other similar motor engines, the combination of an arrangement
whereby the air chamber is placed in communication with a groove or channel
provided on the piston underneath the packing, during the whole time that pressure
is kept up in the cylinder substantially as and for the purpose herein before
described.
4. In hot air engines, the arrangement of the cap or cover carrying all the suction
and delivery valves of the air pump above the cylinder, substantially is herein before
described and illustrated in the drawings.
5. The arrangement in combination with the governor of a roller moved by the
action of the governor so as to be acted upon by one or the other of offsets or steps
on a cam to regulate the admission of air, such roller coming in contact only
with the said offsets or steps of the cam, as the projections of the latter are passing
it and not with the circular or non-acting part of the cam substantially as herein
before described and illustrated in the accompanying drawings.
6. The arrangement for causing the roller to engage with a suitable width of
surface of the steps of the cam and obviating liability of the roller to slip from one
step to the other whilst the admission valve is open substantially as herein before
described and illustrated in the accompanying drawings.

page_text: 7: The general arrangement and combination of parts constituting a hot air engine
substantially as herein before described and illustrated in the accompanying
drawings.
n
شديد
1
1.
J. H. JOHNSON & Co.,
Agents.