Improvements relating to Hot-air Engines.
Year: 1887

page_text: [Communicated from abroad by BENJAMIN FRANKLIN MININLEY, O Covington,
Kentucky, United States of America.]
Improvements relating to Hot-air Engines.
I, HENRY HARRIS LAKE, of the firm of Haseltine, Lake & Co., Patent Agents,
Southampton Buildings, in the County of Middlesex, 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:-
:
My invention relates to hot-air engines and comprises improvements which secure
a greater degree of efficiency than heretofore, by rapid changes of temperature in the
regenerating chamber, the said chamber being adapted to receive a displacer,
operating in conjunction with the working piston, which latter is located in a cylinder
which is in communication with the regenerating chamber the piston and displacer
being geared together to operate so that the piston moves in the same direction with,
but after, the displacer. The heated air at the bottom of the regenerating chamber, is
forced through a regenerating packing of woven wire, or other suitable material,
which absorbs the heat, and, by producing a partial vacuum, draws back the working
piston.
This movement of the working piston causes the displacer to move in the opposite
direction, to force the comparatively cooled air back through the woven wire
regenerating surfaces, which, in giving up heat to the air, expand it, and act against
the upwardly working piston, thus securing a continuous action by the alternate
passage of the air around, and its rapid contraction and expansion in the closed
chamber.
One of the objects of my invention is to so construct and arrange the working
piston, that it will project down into the regenerating chamber a sufficient distance to
displace a considerable volume of air, thereby lessening the amount of air to be heated
and cooled.
Another object is to place a non-conducting material on the face of the working
piston, to prevent it from becoming unduly heated.
Another object of my invention is to provide suitable devices for cleaning out soot
from the combustion chamber, below the regenerating chamber.
Another object of my invention is to provide a suitable governor to regulate the
speed of the engine.

page_text: Another object of my invention is designed to secure a great degree of efficiency,
by increasing the cooling effect of a current of air passed around the outer surface of
the regenerating chamber, by charging it with vapour of water, or saturating the air
with moisture; all of which, are hereinafter set forth.
In the accompanying drawings
Figure 1 is a perspective view of my improved engine in position for usc.
Figure 2 is a central vertical section of the piston and regenerating chamber,
showing the governor and water pipes in elevation.
Figure 3 is an elevation, partly in section, of the governor and
Figure 4 is a perspective view of the soot cleaner.
A represents the shell of the engine, within which is located the combustion
chamber, and working cylinder and piston and B represents the fly-wheel.
In Figure 2 the interior construction is shown in which
represents the furnace or
fire chamber; 2 the ash pit; 3 the furnace door for introducing the fuel into the fire
chamber; and 4 the uptake.
5 represents a diaphragm covering the top of the fire chamber and which separates
the latter from the generating chamber, 6; 7 represents the displacer, which is a
circular bridge, to which is attached a cylindrical ring a and b represents a space
formed by a U-shaped corrugation of the diaphragm, as shown by c, c Figure 2, into
which the lower part of the said ring a projects.
d, d represent a similar corrugation formed upon the upper side of the regenerating
chamber, into the space of which the top portion of the annular ring a projects, the
displacer being formed of the parts 7 and ring a.
8 represents an annular regenerating space filled with material preferably composed
of woven wire cloth cut in strips and packed in the space around the annular ring a
(as shown in Figure 2) which separates the upper from the lower half of the
regenerating chamber, and through which air is forced by the reciprocation of the
displacer 7, and annular ring a.
It will be observed that the air, in passing from either side of the displacer 7,
moves through the spaces b, down around the annular ring a, thence through the wire
and thence through the spaces on the opposite side of the displacer, so that the air
travels quite a distance in moving from one side of the displacer to the other, and
gives out, or takes up heat according to the direction in which it is passed.
The sides or corrugations of the boundaries of the regenerating chamber furnish a
large amount of heating and cooling surface for the air which passes around and
impinges against them.
In addition to this, the corrugation of the diaphragm 5 at the bottom of the
regenerating chamber, allows the expansion and contraction of the metal without
danger of breaking it.
12 represents an annular flue placed around, outside the regenerating chamber, and
around the corrugated plates and d, and terminating in the annular space e around
the cylinder 14, within which the working piston 13 reciprocates.
This annular flue opens into a space D at the bottom, and communicates with the
furnace by openings h. Thus the air passes around the regenerating chamber, down
through flue 12, to take up the heat from the regenerating chamber, and is carried
directly into the furnace, and utilized in heating the lower side of the regenerating
chamber.
In order to prevent this working piston from becoming heated, I pack the face
of it with a non conducting material 15, which is preferably sheets of asbestos paper
secured thereto by bolts, or other suitable means. This packing is allowed to project
down into the upper side of the regenerating chamber, so as to lessen the volume of
air required to fill the chamber, thereby diminishing the quantity of air required to be
heated and cooled in the operation of the engine.
9 represents the escape flue from the combustion chamber, leading to the uptake
through the annular space 10, within which is placed a soot cleaner. This soot
cleaner is composed of an annular ring 11 (see Figure 4) soot cleaner plates 17
being rigidly secured to the ring, of the proper shape to fill the annular space 10,

page_text: between the plates of the air mue 12, and the annular corrugations c or the
diaphragm.
The ring 11 rests upon the top of an annular ring 8*, which is supported around
the outside of the combustion chamber, as shown in Figure 2. As the products of
combustion pass from the air chamber to the uptake, they are liable to become cooled,
and apt to condense upon the surface of the flue space 10, the soot cleaner is
therefore introduced, so that it may be rotated or oscillated and the soot knocked off.
To accomplish this, I have provided the downwardly projecting stem 22, attached to
the ring, which projects into the uptake 4; and to this stem is attached a crank
arm 23, which is projected through the pipe 4, which is slotted so as to allow it to be
moved back and forth to oscillate the soot cleaner.
The working parts of the engine consist of the piston 13, piston rod 18, connected
to the crank 19, which is keyed to a rock shaft 20, suitably journalled to the frame 24,
which frame is rigidly mounted upon the top of the cylinder A.
25 represents a crank keyed upon the end of shaft 20; 26 a pitman or connecting
rod journalled at one end, upon the pin of crank 25, and upon the other to the pin of
crank 27, that is hung upon a crapk shaft 28. 29 represents a pitman or connecting
rod journalled upon a pin of crank 27, and upon pin of crank 30, which crank is
keyed to rock shaft 31.
32, 32 represent rods connected to rods 33 by pins, which rods 33 project down
through the diaphragm, and are tapped into the annular bridge 7 of the displacer.
The operation of the engine is as follows.
Fuel is introduced into the fire chamber 1, as soon as the surfaces of the fire
chamber have become sufficiently heated to raise the heat of the air within the
regenerating chamber below the displacer, sufficient to enable the parts to work, the
fly-wheel B is started by hand, the working piston is carried upward, and before it
reaches the limit of its stroke, the displacer is started downward by the rods 33,
forcing the air out beneath it, around the outside of the annular portion of the
displacer, through the wire gauze, and around upon the side of the displacer, and
between it and the face of the piston 13.
In being forced through the regenerating wires 8, it surrenders its heat to said
wires, and to the cooler upper surfaces around the space b, which take up more heat
and contract the air, making a partial vacuum, and causing the working piston to
descend; the return motion of the displacer forces the air backward through the
regenerating gauze 8, taking up the portion of the heat previously surrendered on its
way back to chamber 6, where it is further heated by the fire in the combustion
chamber. This cooling and heating of the air is very rapid, and the difference in heat
and pressure owing to the change of the movement from the upper to the lower side
of the displacer furnishes, alternately, a sufficient amount of pressure and vacuum to
raise and lower the working piston rapidly. The efficiency of the engine is
considerably increased by cooling a current of air which passes from the normal
atmosphere outside, through the annular flue 12, into the fire chamber, giving back
its heat to be utilized, which is taken up in passing around the regenerating chamber.
In order to supply the best cooling medium, and to render the engine more effective,
I have discovered that the radiant heat given off by the surfaces of the regenerating
chamber, is not readily taken up by the current of air passing down through the
flue 12; but is taken up by the outer casing A of the engine. To obviate this, and
to accelerate the cooling, I have found that if the air passing through said flue 12 is
saturated with acqueous vapor, generated at low temperature, this radiant heat will be
taken up by said acqueous vapor, and carried along with the air to the fire chamber,
and given up as a product of combustion.
I therefore introduce a thin stratum of water which occupies the space 35 in the
channel e on the upper side of the regenerating chamber, and outside of the cylinder 14
of the working piston.
36 represents the water pipe for supplying this water. The upper surface of the
regenerating chamber, and the cylinder 14 of the working piston, are by this means
kept at a comparatively low degree of heat, say below 212, and yet sufficiently heat

page_text: the water. introduced into the said channel, to charge the air with sufficient amount of
vapour to keep up the radiant heat.
Thus the efficiency of the engine is materially increased by the cooling medium of
air charged with acqueous vapour.
In order to regulate the stroke of the engine, I provide a governor valve, which is
located at the mouth of pipe 37, shown in figures 2 and 3, which pipe is connected to
a branch 38, which is in turn provided with connecting pipes 39, that pass through
the upper plate of the regenerating chamber, communicating with the air chamber
between and around the working piston 13 and the displacer 7.
The air in the interior of said chamber being expanded by heat taken up from the
combustion chamber, tends to escape through the said valve, and thereby to lessen the
pressure on the working piston.
In order that this escape may be regulated, and thereby control the pressure upon
the under side of the working piston, provide the following instrumentalities.
40 represents a cylindrical valve within the valve chamber 41. This valve has two
seats 42, 43. 44 represents the opening above the valve, which opening when the
valve is open places the regenerating chamber in communication with the atmosphere
through pipes 37, 38, and 39. The valve is normally held closed by means of a
spring 45, which is coiled around rod 46 and bears at one end against the collar 47,
and at the other end against the collar 48. The inner end of rod 46 is pivotted to the
arm of bell crank lever 49, which lever is pivotted upon the axis 50 attached to the
frame of the governor. The free end 51 of the bell crank lever 49, is forked or
loosely connected to the valve stem 52, the construction of the parts being such that
the spring 15 retracts and lifts up the arm 51 and holds the valve 40 normally up
against its seats 42, 43. 53 represents the head of the governor valve stem.
54 represents a cross arm rigidly secured to the journal sleeve 55, of the valve stem,
so as to revolve with the supplemental valve stem 56, which supplemental valve stem
is stepped upon the valve stem 52.
Valve stem 56 journals in sleeve 58. 57 represents a bevel gear keyed to the
supplemental stem 56, which meshes in turn with bevel gear 59, which is keyed upon
the shaft 60, journalled in the sleeve 61. 62 represents a pulley over which passes a
belt 63, for driving the governor.
This belt likewise passes around a similar pulley upon the crank-shaft 28 which is
revolved by the crank 27, by which means motion is communicated to the supplemental
stem 56, revolving the governor: this governor is of ordinary construction, being
connected by the aforesaid mechanism to the supplemental valve stem and main valve
stem, and regulates the speed of the engine by controlling the escape of compressed
air from the regenerating chamber, in the following manner:
Said check valve is held normally closed by the coiled spring 45. If the engine be
running idle, the speed of the revolving balls 65 is such that they expand or rise on
their pivots, and draw the retractile springs 64 connected thereto backward or
downward. These retractile springs are connected to the head 53, and as the head is
drawn down by the rising of the balls 65, the supplemental stem 56 is drawn down upon
the head of the main valve stem 52, carrying the check valve 10 off of its seats 42, 43,
and allowing the escape of compressed air around the lower seat of the valve and
through holes in the same. As the speed of the balls is lessened, they descend,
and the check valve rises more or less against its seat, in proportion to the slacking of
the speed.
Thus, I am enabled to control the speed of the engine by regulating the pressure of
air within the regenerating chamber.
It will be observed that the pressure of the air within the air chamber, tends
to keep the valve seated, and the escape opening closed: but should the speed of the
engine decrease so that the weight of the balls on the springs 64 is not quite
balanced by the centrifugal force of the said balls, which is the case on the down
stroke of the piston when the pressure is low, the pressure of air in the displacer
chamber being less than the normal atmospheric pressure, the check valve will fall,
and air will enter into the regenerating chamber.

page_text: It will also be seen that when the engine is working up to nearly its maximum
power, there is little or no escape of the compressed air within the regenerating
chamber, except in case of a sudden lessening of the load. Consequently there is no
material loss of power by the escape of the heated air, which is the working
medium.
I do not wish to claim the details of construction of the governor, but the manner
of its connection with the air passages, and the controlling of the entrance, and the
exhausting of the air within the regenerating chamber.
Having now particularly described and ascertained the nature of the said invention
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 :-
First. A hot air engine with its regenerating chamber formed with its upper and
lower plates having the annular corrugations with the recesses bb, to receive the
cylindrical displacer a, working therein, substantially as specified.
Second. A hot air engine with its regenerating chamber formed with its upper and
lower plates having the annular corrugations with the recesses bb, to receive
the cylindrical displacer a, working therein, and the regenerating chamber filled with
wire gauze packed around said displacer a, substantially as specified.
Third. The working piston 13 arranged within the cylinder, so as to occupy a part
of the space of the regenerating chamber at the extreme limit of its downward stroke,
substantially as specified.
Fourth. The working piston 13, faced with a non-heat-conducting material,
substantially as specified.
Fifth. The soot cleaner composed of the ring 11, and scrapers 17 arranged in
the flue outside of the regenerating chamber, substantially as specified.
Sixth. In combination with the regenerating chamber 6 of a hot air engine,
a check valve connected to said chamber by pipes, and the governor acting upon
said valve, substantially as specificil.
Seventh. In a hot air engine, the combination of a check valve for admitting
air into, or allowing the escape of air from the engine, with the governor connected to
it, so that the action of the valve is regulated by the speed of the governor, substantially
as specified.
Eighth. In a hot air engine, the cooling portion of the regenerating chamber, with
the flue through which is passed a current of air charged with aqueous vapour coming
in contact with the outer surfaces of said regenerating chamber, which form the inner
surfaces of the flue, substantially as specified.
Ninth. A hot air engine employing a regenerating chamber, and having an
air cooling flue surrounding it, and a body of water above said chamber, heated
thereby, and opening into said air flue, whereby a current of air, charged with vapour
or steam, is carried through the cooling flue, substantially as specified.
Tenth. In a hot air engine, the regenerating chamber with an upper corrugated
plate, and supply pipe for introducing water into the space 35, in combination with the
air cooling flue, passing around said chamber, for cooling the parts thereof, substantially
as specified.
Eleventh. In a hot air engine, the regenerating chamber, with an upper corrugated
plate and supply pipe, for introducing water into the space 35, in combination
with the air cooling flue passing around said chamber, thence under said chamber into.
the furnace, through openings at the bottom, thence leading to the fire chamber into
which the cooling medium is introduced, substantially as specified.
HASELTINE, LAKE & Co.,
45, Southampton Buildings, London,
Agents for the Applicant.