IMPROVEMENTS IN MACHINES FOR COOLING AIR OR OTHER GASES
Year: 1886

page_text: Date of Application, 7th Aug., 1886.
Complete Left, 6th May, 1887.
Complete Accepted, 10th June, 1887.
I, JAMES ATKINSON, of 3 Nassington Road, Hampstead, London N.W. Engineer
do hereby declare the nature of my invention for IMPROVEMENTS IN MACHINES FOR
COOLING AIR OR OTHER GASES to be as follows:-
This invention is for Machinery for cooling air (or other gases) by compressing it,
cooling it when compressed, and expanding it doing work, so as to deliver it in a
cold state, for refrigerating, for preserving meat or other perishable goods, for
making ice, and for other purposes for which cold air, other gases or vapours are or
may be employed. Its chief object is the simplification of such machinery and
making its action more certain, efficient and reliable.
I construct the improved machine with preferably a single-acting, horizontal
cylinder, fitted with a plunger piston; the cylinder is provided with self-acting inlet
valve (or valves) of ordinary construction, and delivery valve (or valves) operated by
an eccentric or cam. The piston has a little clearance in the space between the end
of the cylinder and the piston and in the valve passages when the piston is at the
inner end of its stroke as possible, but this space is in free communication with a
number of tubes screwed or otherwise suitably fixed in the end of the cylinder into
which the contents of the cylinder are compressed, these tubes are made as small in
diameter as possible and as numerous as convenient, they are closed at their outer
ends and are inserted or project into a water tank fixed to the cylinder end, the water
keeps the tubes and the cylinder ends cool; the cylinder and piston may also be kept
cool by water circulation. The piston has a reciprocating motion imparted to it and
requires two in and two out strokes to complete the cycle of operation.
The mechanism for imparting the reciprocations to the piston consists of a con-
necting rod connecting the piston to the crank pin of a crank fixed on a vibrating
shaft; the crank vibrates from a position more or less at right angles with the axial
line of the cylinder to a position in which the piston connecting rod and the crank
are more or less in a straight line; the vibrating shaft may be vibrated by any
suitable connection with an engine or rotating shaft. The motion of the piston will
thus be rapid when towards the outer parts of its strokes and slower when towards

page_text: the inward parts of its strokes and it can be made to remain more or less almost
stationary for comparatively a considerable period when at the inner end of its
strokes when the air is at its maximum compression, also the piston connecting rod
and crank being more or less in a straight line at this time the toggle action enables
a considerable compressing pressure to be easily obtained and the slow movements
of the piston when the air is at its maximum compression allows time for the
transmission of heat from the compressed air to the water.
The action is such that the piston during an outward stroke draws in a cylinder
full of air, on the return inward stroke this air is compressed into the cooling tubes
where the heat of compression is rapidly transmitted to the water owing to the
considerable area of cooling surface, the comparative rest of the piston and the small
isolated divisions into which it is parted by the great number of cooling tubes, their
small size ensuring the whole of the air being brought into close contact with cooling
surfaces; on the next outward stroke a considerable proportion of the power required
for compression is given out by the expanding air which by thus doing work is
cooled to a low temperature depending on the efficiency of the cooling surfaces, the
extent of the compression and the time during which the air is compressed; being
now reduced in bulk through lowered temperature it expands down to atmospheric
pressure before the piston has passed so far out as it did to draw in the charge and
prefer to open the delivery valve at this time allowing some of the previously cooled
air to pass back into the cylinder so as to prevent fresh air being drawn in to make
up the deficiency, on the return inward stroke the cold air is expelled through the
discharge valve to be utilized in any desired manner, the discharge valve is then
closed and the cycle of operations repeated.
The delivery valve (or valves) is operated by an excentric or cam on a shaft driven
at half the number of revolutions as the engine or rotating shaft which imparts
motion to the vibrating shaft.
In some instances it may be desirable to continue the motion of the piston con-
necting rod and its connected crank past the straight line, so that they vibrate on
each side of this straight line in such a manner that the two outward and two inward
strokes of the piston are obtained by one double vibration of the vibrating shaft, and
one revolution of the rotating shaft or engine driving the vibrating shaft if coupled
directly; in this caso the outward expanding stroke and inward delivery stroke may
be made shorter than the drawing in and compressing strokes so as to allow for the
reduced volumn of the cooled air; also the delivery valve excentric may be fixed on
the rotating shaft.
The centre line of the vibrating shaft may be in the same plane as the axial line
of the cylinder or a little above or below it so as to make the side thrust of the
piston on the cylinder due to the angularity of the rods as small as possible.
In a modified form I construct the machine with a separate charging cylinder
which enables all the valves to be made self-acting. The machine then consists of
two single-acting cylinders preferably placed side by side and parallel to each other,
the pistons being driven through connecting rods from a double crank shaft, the
cranks being about at right angles (more or less), the one driving the charging
piston being in advance of the one driving the working piston, the crank shaft is
rotated by an engine or any other means. The charging cylinder has self-acting
suction and delivery valves of any suitable construction, these delivery valves deliver
into a chamber which is connected by a number of shaped cooling tubes which are
always freely open to the working cylinder; the working cylinder has a number of
discharge ports placed round the cylinder near its outer end and the discharge takes
place through them when they are uncovered by the working piston when near the
outer end of its stroke.
The action is as follows.-The charging piston having drawn in a cylinder full of
air through the self-acting suction valves during its outward stroke, delivers the same
through the self-acting delivery valves on its return inward stroke, the air passing
through the cooling tubes into the working cylinder; when the charging piston has
almost completed its inward delivery stroke, the working piston has moved so far on

page_text: its inward stroke as to cover the discharge ports in the working cylinder; the two
pistons then commence to compress the enclosed air between them into the cooling
tubes, the charging piston soon completes its inward stroke, and commences an
outward drawing in stroke, the enclosed air being prevented from returning into the
charging cylinder by the self-acting delivery valves; the working piston continues to
compress the enclosed air to a high pressure into the clearance spaces (which are
inade as small as possible) and into the numerous small cooling tubes where it rapidly
gives up heat to the cooling water surrounding them, on the return stroke of the
working piston the air is expanded doing work and cooled to a low temperature by
the time it has expanded to about atmospheric pressure, at this time the working
piston reaches and uncovers the discharge ports, the sizes of the cylinders, and
positions of the cranks being so arranged as to regulate this expansion to the proper
extent, at this time the charging piston has commenced a delivery stroke, the fresh
charge of air passes through the self-acting delivery valves, through the cooling tubes
into the end of the working cylinder and drives the cold air out of the discharge
ports in front of it; the cycle is thus repeated at each revolution of the crank shaft.
In this modification there are no moving valves exposed to the cold air, so the snow
or ice formed from any moisture in the air cannot cause any damage and therefore
such a machine would be suitable for dealing with very low temperatures.
It will be seen that machines constructed in accordance with this invention have
very few joints exposed to high pressures (excepting the joints of the cooling pipes.
which are easily made perfectly tight), that none of the valves are moved under
anything but very low pressures, and that there is no necessity for any high pressure
chamber, so that much higher pressures for compression may be readily used, con-
sequently a higher efficiency is attainable and low temperatures easily obtained; they
are also simple and little liable to derangement. Much less cooling water may be
used as it may be raised to a higher temperature than is usual with machines as
hitherto constructed.
Machines constructed in accordance with this invention may be arranged to suit
the varying conditions under which they have to work, and they may have the
cylinders and working gear differently arranged, also other kinds of valves may be
used and if desired they may be operated positively by means of gearing. In all of
them however the compressing piston compresses the air into the cooling tubes which
are always in free communication with the compressing cylinder. They may be made
double-acting.
Ammonia, ether, or other vapours which liquefy entirely or partially under pressure
may be used in these machines.
The cooling tubes may be flattened or fluted locally, or through the greater part of
their length for the purpose of increasing their surface in proportion to their contents,
and they may be indented at intervals with a view to fresh portions of air being
continually brought into close contact with the cooling surfaces.
Dated this Seventh day of August 1886.

page_text: Improvements in Machines for Cooling Air or other Gases.
I, JAMES ATKINSON of 3 Nassington Road, Hampstead, London, N.W. Engineer
do hereby declare the nature of my invention for IMPROVEMENTS IN MACHINES. FOR
PRODUCING COLD AIR, OR OTHER GASES, and in what manner the same is to be
performed, to be particularly described and ascertained in and by the following
statement:
it,
This invention is for machinery for cooling air, (or other gases), by compressing
cooling it when compressed, and expanding it doing work so as to deliver it in a cold
state, for refrigerating, for preserving meat, or other perishable goods, for making
ice, and for other purposes for which cold air, other gases, or vapours, are, or may be
employed. Its chief object is the simplification of such machinery, and making its
action more certain, efficient, and reliable.
The machine may be modified in construction to suit varying sizes or conditions
of working, but the principles of operation are the same in any construction made in
accordance with this invention. That these principles may be fully understood I
show in the accompanying sheets of drawings two types of machines and also describe
modifications of these types.
One type is illustrated in sheets 1. and 2. in which Figs. 1. 2. 3 & 4, Sheet 1. are
diagramatical views showing the motion of the moving parts, and in which A.
represents the cylinder, B. the piston, C. the crank, D. the crank rod, E. the piston
connecting rod, F. the vibrating link, and G. the vibrating link centre pin. Fig. 5.
Sheet 1. is an elevation of the complete machine as arranged to be driven by a belt
from any source of power. Fig. 6. Sheet 2. is a plan partly in section; Fig. 7. Sheet 2.
is a sectional elevation, and Fig. 8. Sheet 4 is an enlarged view of one of the cooling
tubes.
The cylinder A. is fitted with a single-acting plunger piston B. which when at the
inner end of its strokes leaves as little clearance space between it and the tube plate H.
as possible; it is connected to a suction valve I. which is self-acting, and a delivery
valve K. which is operated at the proper time by a cam or eccentric on the crank
shaft C. The tube plate H. has a very large number of very small tubes L. screwed
into it, and open at their inner ends to the inside of the cylinder A. their outer ends
are closed; these tubes L. project into a cooling tank M. through which water is
circulated.
•
The action of the machine is as follows:-Commencing with the position shown in
Fig. 1. Sheet 1. the rods F. and E. are in a straight line and the piston B. is at the
end of one of its inner strokes, and the contents of the clearance spaces and tubes L.
are at atmospheric pressure or thereabouts; the crank C. revolving in the direction
shown by the arrow, by means of the peculiar motion of the working gear draws the
piston B. outwards, drawing air into the cylinder A. through the self-acting valve I.
until the position shown in Fig. 2. Sheet 1. is reached; the crank C. continuing to
revolve drives the piston into the position shown in Fig. 3. Sheet 1. at which time the
contents of the cylinder are compressed mostly into the tubes L. to a high pressure
this pressure being higher, the lower the temperature to which it is desired to reduce
the air, that is to say, if it is only desired to reduce the air a few degrees in
temperature a pressure of 30 or 40 lbs. above the atmosphere would suffice & such a
imachine would deliver very large volumes of air with a moderate reduction of

page_text: temperature, requiring only a small amount of power to drive it; if however a large
reduction in temperature is desired the pressure to which the air is compressed should
be 150 lbs. above the atmosphere, or over. From the position shown in Fig. 3.
Sheet 1. the crank continuing to revolve, the piston B is brought into position shown
in Fig. 4. Sheet 1., the compressed air having been rapidly cooled whilst under
compression now occupies less volume so that it expands down to atmospheric
pressure before the piston has travelled so far out as it did to draw in the uncooled
air. The cold air is now expelled through the discharge valve K. which is opened
during the time the engine passes from the position shown in Fig. 4. to that shown
in Fig. 1. The cycle is thus completed once for each revolution of the crank-shaft C.
a volume of air being drawn in, compressed, cooled, expanded doing work on the
piston B. and expelled. Fig. 9. Sheet 4. is a diagram showing the action of one of
these machines as arranged to deliver at a low temperature in which the line from
1. to 2. is the drawing in stroke, 2. to 3. is the compression stroke, 3 to 4. is the
expansion stroke, and 4. to 1. the delivery stroke. It will be seen from this diagram
that very little power is required to drive one of these machines, a very large pro-
portion of the power required during compression being given back during the
expansion.
The lengths of the drawing in and delivery strokes should be made in the pro-
portion of the absolute temperature of the air when drawn in, and the absolute
temperature of the air when expanded, these lengths may be proportioned by adjusting
the length of the crank rod D.
It will be observed from an inspection of Figs. 1. 2. 3. & 4, Sheet 1. that the
compression and the early part of the expansion occupy a considerable time in
relation to the time required for the later part of the expansion & the delivery, this
gives additional time for the compressed air to give up heat & reduces the time
during which the cooled air can pick up heat from the cylinder & valves.
When delivering air at low temperature the cylinder A. should be water jacketted
or cooled by any other means such as the cold air after having been used in the cold store.
It will be seen that no part of this machine is ever at a very low temperature & in
consequence there is never any difficulty caused by snow or ice forming in any part
of it, also ordinary lubrication can be used on the piston.
The machine may be modified by proportioning the rods (say by shortening the
rod D.) in such a manner that two revolutions are required for each cycle; in this
instance the piston B. is drawn outwards for the suction & expansion strokes by the
vibrating link F. being drawn upwards and never descending lower, or at any rate
very little lower, than to make it in a straight line with the piston connecting rod E.
A machine constructed in this manner would have the advantage of giving a verv
long pause when the air is under compression, but would have the disadvantage of
the piston B. travelling outwards too far during the expansion stroke & the cooled air
would be expanded below atmospheric pressure unless some of the previously cooled
air was readmitted to the cylinder by opening the discharge valve earlier than would
otherwise be necessary.
It will be seen from examining Fig. 9. Sheet 4. that the discharge valve K. opens
at the point 4 of the diagram and closes at the point 1. that is to say during the time
the piston is changing its reciprocations & therefore there is ample time for opening
& closing it, and the time of opening and closing does not require any very delicate
adjustment.
A different construction of a machine suitable for delivering large volumes in
combination with a steam engine for driving it is shown on Sheet 3. is which Fig. 10.
is a sectional plan, Fig. 11. an elevation, and Fig. 12. a large sized view of a portion
of the charging cylinder, piston, one of the suction valves, delivery valves, and
cooling tubes.
In this machine a. is the charging cylinder, b. is the expansion cylinder, c. is the
charging piston, d. the expansion piston; these pistons c. and d. are shown connected
directly to the pistons of a compound steam engine, & by means of connecting rods
to a crank shaft of which e. is the crank pin connected to the charging, piston c. and

page_text: f. is the crank pin connected to the expansion piston d. The crank pin e. is in
advance of the crank pin by 90° (more or less); the engine being drawn in the
position in which the discharge of cold air is commencing, and revolves in the
direction shown by the arrow.
The ends of the cylinders a. and b. are closed by a tube plate g. in which a number
of cooling tubes h. are placed, these cooling tubes h. project into & are surrounded by
the cooling water in the water chamber i. Between the charging piston c. and the
tube plate g., a valve plate is placed, this valve plate has a number of concentric
grooves which are closed by light thin concentric rings 1. hereinafter called the
retaining valves, these retaining valves being held in position by a number of radial
ribs which are cut out concentrically for these valves 1. The valves 1. are only
allowed a very small lift & very little space is enclosed between the valve plate j and
the tube plate g.
The piston c. is fitted with a number of suitable suction valves m.
It will be seen that both the valves 1. and m. are self-acting, and no other valves
are required in this machine, the discharge of cold air taking place through a number
of holes or slots formed in the cylinder b. opening into the passage n.
C.
The action of the machine is as follows, the charging piston c. having drawn in a
cylinder full of air through the self-acting suction valves m. during its outward stroke,
delivers the same through the self-acting retaining valves 1. on its return inward
stroke, the air passing through the cooling tubes . into the expansion cylinder b.;
when the charging piston c. has almost completed its inward delivery stroke, the
expansion piston d. has moved so far on its inward stroke as to cover & close the
discharge ports leading to the delivery passage n.; the two pistons then commence
to compress the enclosed air between, into the cooling tubes h., the charging piston
soon completes its inward stroke & commences an outward drawing in stroke,
the enclosed air being provented from returning into the charging cylinder a. by the
self acting retaining valves . The expansion piston d. continues to compress the
enclosed air up to a high pressure into the clearance spaces, (which are made as small
as possible) and into the numerous small cooling tubes . where it rapidly gives up
heat to the cooling water surrounding them; on the return stroke of the expansion
piston d. the air is expanded doing work and thereby cooled to a low temperature by
the time it is expanded to about atmospheric pressure; at this time the expansion
piston d. reaches & uncovers discharge ports opening into the discharge passage n.
and through which the cold air is driven by the next charge of air which is now being
delivered by the charging piston c. The sizes of the cylinders and the positions of
the cranks are so arranged that the expansion of the cold air reaches about atmo-
spheric pressure at the proper time, that is to say, the space in the expansion cylinder b.
at the time when the discharge of cold air commences (this being the position of the
machine shown in the drawings Figs. 10. and 11. Sheet 3.) should be large enough to
contain about a charging cylinder full of air at atmospheric pressure when reduced in
volume by its lower temperature. The cycle is thus repeated at each revolution of
the crank shaft during which time a charging cylinder full of air is drawn in,
compressed between the pistons into the cooling tubes, cooled, expanded doing work
on the expansion piston; thus returning nearly as much work to the machine as was
required for the compression, and is driven out by the next charge of air.
In this arrangement there are no moving valves exposed to the cold air and all the
valves are self-acting. It some instances however it might be modified with advantage
by causing the expansion crank f. to lead, the compression would then be done chiefly
by the charging piston c. and only partly by the expansion piston d, the discharge of
cold air would require to take place through a valve similar to the valve K in Figs. 5
& 6. Sheets 1 & 2. and operated in a similar manner.
It will be seen in Figs. 10 & 11. Sheet 3. that the small ends of the connecting
rods are placed away from the charging and expansion cylinders and these connecting
rods are made short, this is done with a view to increase the length of time the air is
under compression and being cooled, and to decrease the length of time relatively
during which the cold air is discharged.

page_text: Machines constructed in accordance with this invention have very few joints
exposed to high pressures, (excepting the joints of the cooling pipes which are easily
made perfectly tight). The valves are all very simple and if not self-acting are
opened and closed during the time that they have little or no pressure on them.
Much higher pressures for compression may be readily used, consequently a higher
efficiency is attainable and low temperatures easily obtained. They are simple in
construction, easily understood, & little liable to derangement, much less cooling
water may be used and where the cooling water (as it usually is in the tropics) is of
a high temperature a good result may still be obtained.
The arrangement of the cylinder or cylinders and the working gear may be modified
to suit the conditions of working, for instance, in the machines illustrated in sheets 1.
& 2. the vibrating link F may be made a bell crank so that the connecting rod E. and
the crank rod D. do not engage on the same pin as shown, the crank & being more
on one side instead of at the top; the machine would then be more compact and
would not require so much head room. Other kinds of valves or slides may be used
either self-acting or operated mechanically.
The cooling tubes L may be flattened or fluted, locally or throughout the greater
part of their length, for the purpose of increasing their surface in proportion to their
contents, also they may be indented at intervals with a view to fresh portions of air
being continually brought into close contact with the cooling surfaces.
In the machine as shown in sheets 1. & 2. instead of the cooling tubes L the tube
plate H. may be deeply indented from the cylinder side with narrow deep recesses,
corresponding intermediate recesses being formed from the water side providing for
the rapid transmission of heat. In some instances these narrow deep recesses may be
carried through to a plate at the back as shown in Figs. 13. and 14. Sheet 4. in which
O are the air recesses, P. the intermediate water spaces, Q are plates inserted into
the air recesses O for the purpose of increasing the cooling surface and reducing the
contents. In Fig. 14. also the suction valves are shown at the outside consisting of
light annular rings R. in a valve plate T. the air being drawn through the suction
pipe S. and through the air recesses O.
Ammonia, ether, or other vapours, which, may or may not, entirely or partially
liquify under pressure can be used.
Having now particularly described and ascertained the nature of my said invention,
and in what manner the same is to be performed, I declare that what I claim is:
1. In a machine for cooling air or other gases the employment of cooling surfaces
in direct communication with a cylinder, the piston of which wholly or partially
compresses the air, or other gases, into close contact with these cooling surfaces,
and allows the air, or other gases, to reexpand in a cooled state in the same cylinder,
from which it is subsequently expelled in the cooled state, substantially as set forth.
2. In a machine for cooling air or other gases the employment of a piston B. which
for each revolution of the crank shaft C. is enabled to make four strokes; such
strokes enabling a volumn of air to be drawn into the cylinder A, compressed into the
cooling spaces, expanded and expelled in a cooled state, as shown in Figs. 1. 2. 3. 4.
5. 6. 7. 8. 9 13 and 14. Sheets 1. 2 and 4. or any mere modification thereof.
3. In a machine for cooling air or other gases the piston c. which draws in a
volumn of air which is subsequently compressed between the pistons c. and d. into
close contact with cooling surfaces, cooled thereby, expanded doing work on the
piston d and expelled in a cooled state as shown in Figs. 10. 11. and 12. Sheet 3. or
any mere modification thereof.
4. The general arrangement and construction of Machines for cooling air or other
gases substantially as described and illustrated.