Year: 1897

page_text: THOMAS GRIFFITHS Iron House, Kinver Stourbridge Engineer and Cycle maker do
hereby declare the nature of this invention to be as follows:-
This invention refers to that class of hot-air engines which have a closed cycle and
use the same air over and over again. It consists of means for moving the air in a
positive manner through or into close contact with a regenerator heater and cooler (in
the proper order) which may then be inade séparate from the working parts and
highly effective. In combination with this the front of the cylinder is closed in the
air is compressed on both sides of the piston. A ineans of accomplishing the proper
motion of the air without valves is described; which is much preferable. A somewhat.
similar arrangement with valves is described and the two methods may be combined
in a modified form. It also consists of means of regulating the power of the engine.
and cooling the water used.
Fig. 1 shows a vertical section of cylinder. It contains a working piston I and
displacer K this latter is moved by means hereinafter described. The working piston
may be connected to a crank shaft and fly wheel in the same manner as an ordinary..
steam engine. Fig 1 shows piston I at the end of its forward stroke and fig 2 at.
the end of its back stroke. The front of cylinder is closed in by a cover and stuffing-
box as shown, and, preferably, communicates with a reservoir for compressed air by
passage N and stopcock O.
now in
The action of the engine is as follows:-The working piston I being at the end of
its back stroke (preferably at little before) and the displacer K against the 'back
cover, on the engine being started, K begins to move forward and reaches piston I
before the latter has got far on its forward stroke, in doing this it drives the air
between them through passage D in piston and pipe E (which are
communication) into the regenerator from where it passes by pipes F and G fig 2
and recess in piston (which are now opposite) into the heater from which it comes
back by pipe H behind the displacer. In doing this it has been greatly expanded, and
drives I to forward end of its stroke. Displacer K, after overtaking piston has
followed it to nearly the end of its stroke when it begins to return, and reaches the
back cover of cylinder 'before piston has moved far on its back stroke.
it drives the hot expanded air through pipes A and B and another recess in piston
In doing this
(fig. 1) into regenerator where it parts with some of its heat, from there it goes into
The cooler and then back into cylinder by pipe C.
It doing this it has been contracted and the pressure of air on forward end of piston,
Irives it to its back stroke at the end of which the cycle of operations begins again.
The air is obliged to pass as described, because at the time there is no other way open
o it..
Fig 3 shows plan of engine with pipes etc omitted. The displacer K may be
Forked by cams T working against rollers V carried by levers U from the tops of which

page_text: rods connect with the displacer K. The cams drive displacer to back of cylinder and
hold it there till the proper moment, when they release it and the springs shown
(fig. 3) cause it to overtake piston and follow it as
described.
Fig 6 shows shape of cams and levers..
Fig 4'shows regenerator R which is a vessel filled with fine wire or other suitable
material. J'is heater in furnace S and M is cooler which is surrounded by water in
a vessel as shown. Both heater and cooler may be made of a flattened tube bent
into a spiral form or, as shown made from plates.
The pipes in fig 4 are connected to the pipes bearing the same letters on cylinder.
It will be seen that the displacer moves the whole of the working air (except a small
quantity in the pipes etc) at both the backward and forward positions of the piston I.
Fig 5 shows an arrangement for moving the air with valves. They open in the
direction shown. This may or may not form part of the working cylinder but in the
latter case all the air will not be moved at the forward position of the working piston.
If separate it may be connected to the working cylinder by the pipe W. The working
piston would in this case be a simple one without passages or recesses. The displacer
may be worked by the same means in both cases. The pipes in fig 4 are connected
to the same letters in fig 5 only in this case pipes F and G are connected together
directly.
A small compressing pump is required to make good leakage through the stuffing
boxes. It is shown at P fig 3. It inay be connected to the reservoir the stopcock of
which would be closed when the engine stopped and opened on starting to enable
engine to start at full power.
To lessen the power of the engine a stop might be placed in the way of the
displacer rods by means of a hand lever to prevent it coming forward beyond a certain
distance.
To
Or the engine might be arranged to work at two different pressures.
increase the power of the engine a fan or blower might be used to blow the fire up.
The fan might be kept constantly going and when not blowing the fire it might blow
against a coil of pipes through which the water from round cooler circulated to cool
it. These means for regulating especially apply to cases where the engine would be
used to drive horseless carriages.
A modification of fig. 5 consists in making a simple valve in K which would then
have to make twice the number of strokes. One end of it would be connected to the
regenerator. The heater and cooler would be connected to other end of regenerator
and pipes would go from them to other end of displacer cylinder.
In this case there would have to be two valves worked by cams between R and J and
R and M fig 4. .
THOMAS GRIFFITHS Iron House Kinver Stourbridge Engineer and Cycle Manu-
facturer do hereby declare the nature of my invention for improvements in hot
air engines and in what manner the same is to be performed, to be particularly
described and ascertained in and by the following statement :-
This invention reters to that class of hot air engines which have a closed cycle and
use the same air over and over again. It consists of means for moving the air in a
positive manner through or into close contact with a regenerator heater and cooler
(in the proper order) which may then be made separate from the working parts and

page_text: therefore highly effective. In combination with this the front of cylinder is closed in
and the air is compressed on both sides of the piston. Very high pressures may be
used as an effective means of preventing leakage is described. A means of
accomplishing the proper motion of the air without valves is described which is
preferable. A somewhat similar arrangement with valves is described and the two
methods may be combined in several modified forms.
The motion of the air in the proper order in this class of hot air engines is as
follows the working air should pass first into the regenerator then into the heater
and back into working cylinder, after expanding in the cylinder it goes again into
the regenerator then into the cooler and back into the cylinder after which the cycle.
begins again. I will now describe how I accomplish these results using a separate.
regenerator heater and cooler and without valves.
Fig 1 shows a vertical section of cylinder it contains working piston I and displacer
K-this latter is moved by means hereinafter described. The ends of cylinder are..
closed in and leakage prevented by method shown in Fig 1 which is as follows:-
each piston is connected by a rod to one end of a lever the other end of which is
fixed to a rocking shaft which works in a well of oil, one end of this shaft passes.
out through a stuffing box and carries another lever which being outside may be,
connected to a crank and fly wheel in the case of the working piston or cam and
spring in the case of the displacer, in any suitable way. As both stuffing boxes are
below the surface of oil and rocking shafts have little motion or wear, leakage of the..
compressed air is almost abolished.
****
The action of Fig 1 is as follows:-piston I being at back stroke (preferably a
little before) and displacer K against back cover. On the engine being: started K
begins to move forward and overtakes I before the latter has got far. on its forward
stroke. In doing this it drives the air between them through passage D.and pipe: F
(which are now opposite) into the regenerator from where it passes by F and G Fig 2
and recess in I (which are now also opposite) into heater from which it comes back
to cylinder by pipe H behind K. In doing this its pressure has been greatly
increased and it drives I to forward end of its stroke." K after overtaking I has
followed it to nearly forward end of its stroke when it begins to return and
reaches back cover before I has got far on its back stroke. In doing this it drives the '
still hot expanded air through A and B and another recess in I shown in Fig 1 into,
the regenerator where it parts with some of its heat, from there it goes into the
cooler then back into cylinder by pipe C. In doing this its pressure has been greatly
reduced and the pressure of air on the front of working piston drives it to back...
stroke, at end of which the cycle begins again. It will be seen that the air is obliged
to pass as described because there is at the time no other way open to it.
Fig 3 shows plan of engine with pipes etc omitted K may be worked by a simple
cam T (fixed on main shaft) which works a rod joined to top of lever on the rocking,
shaft. Cam T drives K to back of cylinder and holds it there till the proper moment
when it releases it and a spring (not shown) causes it to come forward and overtake,
and follow I as described.
Fig 4 shows regenerator R which is a vessel filled with fine wire or other suitable
material J is the heater in furnace S, M is the cooler surrounded by water in a vessel
as shown. Both J and M may be made of flat tube bent into a spiral forn or from.
plates as shown or in many other ways. The pipes in Fig 4 are connected to, pipes
bearing the same letters on cylinder.
11
It will be seen that K moves the whole of the air used (except a small quantity in
pipes etc) at both back and forward positions of I. The air remaining in the working
cylinder at end of forward stroke is usually neglected in other hot air engines, with
bad results.
Fig 5 shows an arrangement for moving the air with valves. They open in the
direction shown. This may or may not form part of working cylinder, but in the
latter case all the air will not be moved at forward position of working piston....
If separate it may be connected to working cylinder by W, the working piston would
in this case be a simple one without passages or recesses.. K may be worked the

page_text: same way in both cases.
The pipes in Fig 4 are connected to the same letters in
Fig 5, only in this case I and G are connected together directly.
A small compressing air pump (not shown) worked from the main shaft or in any
suitable manner would be required to make good leakage from the stuffing boxes
The same pump would deliver both oil and air leaking from stuffing boxes back inte
the wells. The pump might be arranged with a certain amount of clearance at end
of its stroke so that it could only raise a certain pressure.
A
To increase power of engine a fan or blower might be used to blow fire up, or in
case of liquid fuel more burners might be thrown into action. The same blower
might blow against coil of pipes through which water from cooler circulated, to cool
it. The fly-wheel itself might be cased in and made with vanes to act as a fan. The
power of engine might be lessened by preventing K travelling full distance.
modification of Fig 5 consists in making a simple valve in K which would then have
to make twice the number of strokes of the working piston. One end of displacer
cylinder would be connected to regenerator, the heater and cooler would be connected
to other end of regenerator and pipes would go from each of them to other end of
displacer cylinder, In this case there would have to be two valves worked by cams
between R and J; and R and M Fig 4. A further modification of this latter case
consists in forming the regenerator in the interior of the displacer K itself. But
for all purposes Fig 1 would be preferable to these latter methods.
It might be advisable to connect with the interior of the engine a small chamber
containing one of the many chemical substances having a strong affinity for oxygen,
to remove the latter gas from the air used.
* 2.71)
iny
said
Having now particularly described and ascertained the nature of
Invention and in what manner the same is to be perforined, I wish. it to be
understood that I make no general claim to the method of preventing leakage of the
compressed air, shown in Fig 1 nor to the use of a flywheel made to act as a fan but I
declare that I claim as my said invention ;-
The means shown in Fig 1 of the accompanying drawings whereby the whole of
the air used (except a small quantity in pipes etc) may at either back or forward
positions of working piston be driven in a positive manner through or into close
contact with a regenerator heater and cooler at the right moment and in
the proper order without the use of valves substantially as described herein before.
2 Tlie fneans of moving the air hereinbefore described and shown in Fig 1 by
which it is rendered possible to have regenerator heater and cooler separate from the
working parts and therefore highly effective substantially as described.
3 The means herein before described and shown in Fig 5 or any of the modifications
described whereby the whole or part of the air used may be driven in a positive
manner through or into close contact with a regenerator heater and cooler at the
right moment and in the proper order substantially as described.
4 The means of moving the air herein before described and. shown in Fig 5 or any
of the modifications described whereby it is rendered possible to have regenerator
heater and cooler separate from the working parts of the engine and therefore highly
effective substantially as described.
5 Any mere indification or combination of any of the means herein before described
of moving the air used through or into close contact with a regenerator heater and
cooler at the right moment and in the proper order substantially as described.
6 Any mere modification or combination of any of the means hereinbefore described
whereby the heater regenerator and cooler may be made separate from the working
parts substantially as described.
7 The combination of the means of preventing leakage of the compressed air as
hereinbefore described and shown in Fig 1 with my improvements in hot air engines.,
substantially as described;
"
8. The combination of the use of a flywheel made to act as a fan with my
improvements in hot air engines substantially as hereinbefore described..

page_text: 9 The combination of the use of compressed air with any of my methods of moving
the air substantially as hereinbefore described.
10 The combination of the means of increasing and regulating the power of the
engine as hereinbefore described with my improvements in hot air engines
substantially as described.
Dated this 20th day of contambo 1907