Improvements in Air Compressors and Blowing and Exhausting Machinery.
Year: 1895

page_text: Date of Application, 1st Feb., 1895
Complete Specification Left, 1st Nov., 1895-Accepted, 30th Nov.,
1895
PROVISIONAL SPECIFICATION.
Improvements in Air Compressors and Blowing and Exhausting
Machinery.
I, CARL, THOMAS ALFRED HANSSEN of 333 Lordship Lane, East Dulwich in
the County of Surrey Engineer do hereby declare the nature of this invention to
be as follows :-
Machines for compressing air for transmitting motive power or for working
blast furnaces or Bessemer converter or for compressing or exhausting gases
have heretofore been made with lifting valves or with cylindrical or flat sliding
valves. The fault of lifting valves is that they do not allow the compressor to be
driven at a high speed of rotation and that the valves constantly wear themselves
leaky. The fault of cylindrical valves is that they do not allow the delivery
valve to be shut quickly when moved by positive valve gear, and that the so-called
Corliss valve gear is not suitable for high speed of rotation. Flat slide valves as
hitherto used for air compressors have had two much clearance space in the port
openings and cylinder ends and have not, been made in such a way that the rate
of compression could be varied while the machine is running.
Having had many years experience in designing and working air compressors
I find that the following points are of great importance.
1. The inlet and outlet valves should be absolutely tight and open. and shut
quickly without noise or vibration at the exact point required and they should be
made entirely of metal and moved by a positive valve gear.
2. The clearance spaces in the cylinder and port openings should be made as
small as possible especially with sliding valves as the compressed air cannot be
re-expanded in the cylinder without unduly complicating the valve gear.
3. The air compressor should be able to work with the same speed of rotation
as is now universally and successfully used for steam engines driving dynamos and
screw propellers, as this decreases the size of the machine its first cost and also
the cost of engine house and foundations in direct proportion to the number of
revolutions made per minute by the compressor and motor.
4. The air compressor and motor should be arranged in such a manner that the
weight and momentum of the moving parts are carefully. balanced and that the
power of the steam engine or other prime mover is equal to the resistance in
the compressing machine at each point of the stroke. This is especially important
where the quantity of compressed air required per unit of time is variable as the
best way to regulate the air supply is to let the compressor stop when the air
pressure in the air receiver rises above the standard working pressure and to let it
start automatically as soon as the pressure falls below the standard working
pressure. This can only be done when the engine and the compressor are properly
balanced.
5. The air compressing cylinder or cylinders should have a large surface-cooled
outside by means of water-circulation, as it is important to keep all the surfaces
of the compressing cylinders cool in order to avoid any heating of the incoming
air and to keep the temperature during compression as low as possible, as this
increases the quantity of air compressed in a cylinder of a given capacity and
decreases the power required for doing this work.

page_text: '
6. Where it is necessary to compress air to more than 40 or 50 pounds pressure
per square inch above the pressure of the atmosphere this should be done in two
or more stages, compressing it to an intermediate pressure in the first cylinder and
cooling it to the original temperature by passing it through a cooling apparatus
which may be similar to a surface condenser, before it enters the next cylinder
to be further compressed. The power required in compressing air to high
pressures can in this manner be considerably reduced.
Air compressing blowing and exhausting machines constructed according to my
invention fulfill these conditions.
According to my invention I use a pair of single acting air compressing cylinders
with their valve chests or one commion valve chest bolted to one end of the
cylinders.
The main valves are slide valves and also the release valves which latter work
on the back of the former; each set of main valves and each set of release valves
is worked by a steep threaded screw receiving rotary motion there and back from
eccentric or cam gear. The pistons are provided with projections on one side
which fill the ports at the end of the stroke.
I use two four or a large number of single acting cylinders arranged in couples
and each pair bolted to a single valve chest, with or without partition or two valve
chests. I arrange the cylinders by preference in a vertical position. Each
cylinder is provided with a carefully fitted piston or plunger driven by means of
a connecting rod or other suitable means from a common crank shaft. The two
cylinders bolted together to a common valve chest to have cranks at opposite
angles. The air cylinders are surrounded with water jackets and the valve chest
is provided with hollow spaces wherein water can be circulated so as to keep the
walls of the cylinders perfectly cool.
The ports leading from the cylinders to the valve chest are in the cylinder ends.
They can be made double and of ample size and I fix suitable projections on the
pistons or plungers of the cylinder which nearly fill the ports when the plungers
have completed their stroke and loss of power from waste spaces is thus avoided.
For admitting air from the atmosphere to the compressing cylinders and for
releasing the air from the cylinder when sufficiently compressed I use flat slide
valves the release valve sliding on the top of the main distribution valve. I
arrange the inlet and outlet ports in such a manner that the valve chest is filled
with compressed air and the air pressure is acting on the back of the valves
pressing them against their seatings and thus keeping them air tight. Each valve
is provided with a nut suitable for working on a steep threaded screw which is
fixed in proper bearings in the valve chest in such a manner that it can be turned
through a part of a revolution by means of a short crank. The crank pin of this
short crank is provided with a bearing which may be rectangular on the outside
and work in a suitable frame which forms the end of the eccentric-rod.
The eccentric rods are moved by eccentrics or cams. The main eccentric is
keyed on to the shaft without angular advance. The main valve has therefore
no lead and only sufficient lap to keep it air-tight. I prefer to arrange the steep
screw and the crank for same in such a manner that the movement of the eccentric
is reproduced exactly in the valve as if it were moved direct.
The release valve is moved by means of a steep screw in a manner similar to
that of the main valve, and the frame which moves the pin of the small crank of
the screw through say a quarter of a revolution is actuated from an eccentric
fastened on the crank shaft. This eccentric is approximately in the opposite
position to what an eccentric for the expansion valve of a steam engine would be.
That is whereas the eccentric sheave for the expansion valve of a steam engine would
have its centre approximately opposite to the centre of the main crank pin I put
the centre of the eccentric sheave for the release valve on the same side as the
centre of the leading crank pin.
For compressors that always compress air to one definite pressure such as
blowing engines for blast furnaces.or stage compressors for large power transmission

page_text: installations the eccentric sheave for the release-valve may be keyed on the shaft
in the usual manner. Where it is necessary to alter the pressure of air to suit
varying conditions 1 vary the point of release by making the position of the
eccentric sheave on the crank shaft variable. A comparatively small twist of the
eccentric sheave makes a considerable difference in the point of release.
In order to move the eccentric sheave in the manner required while the engine
is working 1 clasp the sheave round the shaft which is provided with a collar so as
to prevent any lateral movement of the sheave. The angular position of the
sheave may be regulated by means of a sleeve which is free to slide laterally on
the crank shaft but is prevented from revolving on the same by means of one or
more feathers fastened either on the shaft or inside the sleeve and which slides in
suitable grooves. One end of this sleeve is provided with steep pitched screw
thread and a boss on the eccentric sheave is provided with corresponding female
grooves.
The other end of the sleeve is provided with a number of parallel collars shaped
so as to gear properly into the teeth of a cog wheel segment fixed under the sleeve
and held in position by a lever working with a spring catch in a notched quadrant
in the same way as the reversing lever of a locomotive or in any other well known
way. The angular position of the eccentric sheave can therefore be varied by the
lateral movement of the sleeve without interfering with the revolving of the crank
shaft.
The relative movement of the slide valves to the pistons of the two single acting
cylinders is theoretically exactly similar to the movement of the slide valves to the
piston of one double acting cylinder but in practice there is the great advantage
that the disturbing influence which the angular vibration of the piston rod has on
the valve motion of a double acting cylinder is eliminated by using two single
acting cylinders with opposite cranks and further that the cooling surface of the
two single acting cylinders and of the valve chest is much larger than the cooling
surface of one double acting cylinder.
For the purpose of driving the air compressor I use by preference a vertical
two cylinder double acting steam engine running at a high speed of rotation and
driving a crank shaft with two cranks. In order to balance the rotative force of
the engine with that of the air compressor and at the same time to balance the
moving parts of the engine as nearly as possible, I find that the leading crank of
the steam engine should be about 45° in advance of the leading crank of the air
compressor and that the second crank of the steam engine should be about 150°
to 160° behind the leading crank of the engine. The engine should have small
clearance spaces and only a small amount of compression.
The exact details of the steam distribution vary somewhat with the ratio of
compression in the air cylinders, if this ratio is small, that is when the air is
compressed to a low pressure in the air compressing cylinders then it is compara-
tively easy to arrange the steam distribution in such a manner that the rotative
effects on the four cranks are balanced at each point of their travel.
For high air pressures it is therefore of great advantage to perform the compres-
sion in two stages. This can be done without any material alteration of the
patterns or general design of the air compressor by reducing the volume of one of
the single acting air cylinders either by decreasing the diameter of the cylinder or
by decreasing the length of the crank. The air is then first compressed in one of
the cylinders from the pressure of the atmosphere into an intermediate air receiver
when it is cooled down to the initial temperature either by making the receiver
with a sufficiently large surface to lose the heat of compression by radiation or by
circulating water through the receiver as it is generally done in surface condensers
for steam engines. The air from the intermediate air receiver is then passed into
the second air cylinder and there compressed up to the required pressure. The
reduction in the ratio of compression by working in this manner is very consider-
able as the ratio of compression in each air cylinder is only equal to the square
root of the total ratio of compression. The total strain on the crank shaft and

page_text: connecting rod bearings is in this manner reduced to one fourth of what it would
be in a single cylinder of the same diameter and the losses due to heating the air
and to clearance spaces are considerably reduced.
The division wall which is provided in the valve chest when the compressor is
used as a stage compressor must be made airtight one half being used as the low
pressure valve chest and the other half being used as a high pressure valve
chest.
Dated the 1st day of February 1895.
JENSEN & SON,
77 Chancery Lane, London, W.C., Patent Agents.
Improvements in Air Compressors and Blowing and Exhausting
Machinery.
I, CARL THOMAS ALFRED HANSSEN of 333 Lordship Lane, East Dulwich
in the County of Surrey, Engineer, do hereby declare the nature of this inven-
tion and in what manner the same is to be performed to be particularly described
and ascertained in and by the following statement:-
Machines for compressing air for transmitting motive power or for working
blast furnaces or Bessemer converters or for compressing or exhausting gases
have heretofore been made with lifting valves or with cylindrical or flat sliding
valves. The fault of lifting valves is that they do not allow the compressor to be
driven at a high speed of rotation and that the valves constantly wear themselves
leaky. The fault of cylindrical valves is that they do not allow the delivery valve
to be shut quickly when moved by positive valve gear, and thus the so-called
Corliss valve gear is not suitable for high speed of rotation.
Flat slide valves as
hitherto used for air compressors have had too much clearance space in the port
openings and cylinder ends and have not been made in such a way that the rate of
compression could be varied while the machine is running.
Having had many years experience in designing and working air compressors
I find that the following points are of great importance.
1. The inlet and outlet valves should be absolutely tight and open and shut
quickly without noise or vibration at the exact point required, and they should be
made entirely of metal and moved by a positive valve gear.
2. The clearance spaces in the cylinder and port openings should be made as
small as possible especially with sliding valves as the compressed air cannot be
re-expanded in the cylinder without unduly complicating the valve gear.
3. The air compressor should be able to work with the same speed of rotation
as is now iniversally and successfully used for steam engines, driving dynamos and
screw propellers, as this decreases the size of the machine its first cost and also
the cost of engine house and foundations in direct proportion to the number of
revolutions made per minute by the compressor and motor.
4. The air compressor and motor should be arranged in such a manner that the
weight and momentum of the moving parts are carefully balanced and that the
power of the steam engine or other prime mover is equal to the resistance in
the compressing machine at each point of the stroke. This is especially important
where the quantity of compressed air required per unit of time is variable as the
best way to regulate the air supply is to let the compressor stop when the air
pressure in the air receiver rises above the standard working pressure and to let
it start automatically as soon as the pressure falls below the standard working
pressure. This can only be done when the engine and the compressor are properly
balanced.
5. The air compressing cylinder or cylinders should have a large surface cooled

page_text: outside by means of water circulation, as it is important to keep an the surfaces
of the compressing cylinders cool in order to avoid any heating of the incoming air
and to keep the temperature during compression as low as possible, as this
increases the quantity of air compressed in a cylinder of a given capacity and
decreases the power required for doing this work.
6. Where it is necessary to compress air to more. than 40 or 50 pounds pressure
per square inch above the pressure of the atmosphere this should be done in two.
or more stages, compressing it to an intermediate pressure in the first cylinder and
cooling it to the original temperature by passing it through a cooling apparatus.
which may be similar to a surface condenser, before it enters the next cylinder to
be further compressed. The power. required in compressing air to high pressures
can in this manner be considerably reduced.
Air compressing blowing and exhausting machines constructed according to my
invention fulfil these conditions.
According to my invention I use a pair of single acting air compressing cylinders
with their valve chests or one common valve chest bolted to one end of the
cylinders. The main valves are slide valves and also the release valves which latter
work on the back of the former, each set of main valves and each set of releas
valves is worked by a steep threaded screw receiving rotary motion there and
back from eccentric or cam gear. The pistons are provided with conical projec-.
tions on one side which fill the orts at the end of the stroke. For my quickly!
running air compressor and in order furthermore to adapt it to a very high speed
(that is to say high piston speed and high number of revolutions) and yet without
noise vibration and undue wear and tear I prefer to arrange the bearings of the
connecting rods and of the crank shaft in such manner that the connecting rods
are in compression during the whole of each revolution. I also prefer to provide
the valve rods of the air compressor with air buffer pistons working in suitable
cylinders in such manner that the end strain on the working parts of the valve
gear is always in the same direction. I also prefer to drive the compressor direct
by means of two single acting cylinders working according to the so-calle! Cornish
cycle.
In the accompanying drawings I shew a horizontal air compressor embodying
all the aforesaid improvements and illustrative of what I at present consider the
best mode of carrying my invention into effect, premising however that I do not
confine myself to a horizontal arrangement, nor to the combination of all the said
improvements in one machine.
Fig. 1, Sheets 1 and 2, is a part sectional side elevation and Fig. 2, Sheet 2, an
end view.
Fig. 3, Sheets 3 and 4, is a part sectional plan.
a u are a pair of single acting air compressing cylinders (but I may of course use
two or more such pairs when required) having valve chests bb (or these may be
made in one, with or without central partition). Each cylinder is provided with
carefully fitted piston h or plunger. The pistons are fixed on the piston, rods of
the two single acting steam cylinders m m which by means of connecting rods r
trausmit motion to the shaft s the two cranks t of the latter being opposite to each
other. The two steam cylinders m are bolted to a common valve chest. The air
cylinders a are surrounded with usual water jackets and the valve chests b.are also
provided with hollow spaces wherein water can be circulated so as to keep the walls
perfectly cool. oc are the passages for admitting air from a cool clean place outside
the engine room into the air compressor cylinders, and d d the pipes for passing the
compressed air to the air receivers.
The ports e, leading from the cylinders a to the valve chests are in the cylinder
ends. They may be double as shewn and are of ample size, and I fix on the
pistons suitable projections A which nearly fill the ports e when the pistons have
completed their stroke, and loss of power from waste spaces is thus avoided. As
the ports e are conical they afford communication between cylinder and valve chest
nearly the whole time while the projections enter or leave them..

page_text: For admitting air from the atmosphere by the passages e to the compressing
cylinders and for releasing the air from the cylinders when sufficiently compressed
I use slide valves by preference flat, the release valve f sliding on the top of the
main distribution valve i. I arrange the inlet ports and the outlet ports e in
such manner, (the air from the ports c' entering the hollow spaces of the main
valves and the ports e into the compressing cylinders wherefrom it is again
expelled in a compressed state through the ports e and valve ports v¹) that the valve
chest is filled with compressed air and the air pressure is acting on the back of the
valves pressing them against their seatings and thus keeping them airtight. The
main valve has the ports ee open to the inlet ports c¹ during the whole of the return
stroke and to the delivery ports v during the whole of the forward stroke. The
valves and are each provided with a nut in which works a steep threaded
screw and respectively. These screws have their spindles passing out through
stuffing boxes at one side of the machine and are made to turn through a part of a
révolution by means of a short crank and respectively. The outer continued
ends of the spindles and k work in bearings as shewn in Fig. 3, Sheet 3. To the
eranks are connected the eccentric rods n and o.
These eccentric rods are moved by the eccentrics n¹ and of Fig. 3, Sheet 4,
(or it might be by cams). The eccentric n' for the main valves is keyed on to the
shaft s without angular advance beyond 90 degrees from the crank t. The main
valves i have therefore no lead and have only sufficient lap to keep them tight.
prefer to arrange the steep screws and the cranks for same in such a manner that
the movement of the eccentric is reproduced exactly in the valves as if they were
moved direct.
The release valves are moved by means of a steep screw in a manner similar
to that of the main valves and the crank which moves the screw through say a
quarter of a revolution is actuated from an eccentric o' which may be fixed on the
crank shaft, but in the example here illustrated it is not fixed but made movable
for the purpose of varying at will the point of release. When this eccentric is a
fixed one it is placed approximately in the opposite position to what an eccentric
for the expansion valve of a steam engine would be, that is I would put the centre
of the eccentric sheave on the same side as the centre of the leading crank pin.
For compressors that always compress air to a definite pressure such as blowing
engines or blast furnaces, or stage compressors for large power transmission
installations the eccentric sheave for the release valve may be keyed on the shaft
in the usual manner. When it is necessary to alter the pressure of air to suit
varying conditions
vary the point of release by making the position of the
eccentric sheave on the crank shaft variable. A comparatively small twist of the
eccentric sheave makes a considerable difference in the point of release.
In order to move the eccentric.sheave o' in the manner required and that even
while the engine is working I clasp the sheave round the shaft which is provided
with a collars so as to prevent any lateral movement of the sheave. The angular
position of the sheave is regulated by means of a sleeve u which is free to slide
fongitudinally on the crank shafts but is prevented from turning on the same by
one or more feathers s². One end of the sleeve u is provided with steep pitched
screw thread, and a boss on the eccentric o is provided with corresponding female
screw thread. The other end of the sleeve is provided with a number of parallel
collars or ring teeth u which gear into corresponding ring teeth of a wheel which
can turn on a fixed stud a mounted in a bracket but is kept from any lateral
movement by the nut and the lock nut a. The degree of compression to which
the valve is set is indicated by the pointer against the scale on the bracket.
The angular position of the eccentric sheave o can therefore be varied by the
lateral movement of the sleeve u without interfering with the rotation of the
crank shaft. Or I may regulate the position of the sleeve u by other means as
for instance by a tooth wheel sector which gears with the collars u' and is held in
position by a lever working with a spring catch that takes into a notched quadrant
in the same way as the reversing lever of a locomotive.

page_text: The movement of the first set of valves i and f'is communicated to the second
set of valves and 1 by means of plain rods k¹ and which may be secured to
their valves by means of screw thread, cotters or other well known means.
The movement of the slide valves relatively to the pistons of the two single
acting cylinders is theoretically the same as that of the movement of the slide
valve relatively to the piston of one double acting cylinder, but in practice there
is the great advantage in my arrangement that the disturbing influence which the
angular vibration of the piston rod has on the valve motion of a double acting
cylinder is eliminated by using my two single acting cylinders with opposite cranks,
and further that the cooling surface of two single acting cylinders and of their
valve chest or chests is much larger than the cooling surface of one double acting
cylinder.
I provide the ends of the valve rods k¹ and with pistons p working in air
cylinders pl pl so arranged that the pistons uncover air holes op² at the end of
their strokes, so that the air is compressed during the instroke and re-expanded
during the return stroke thus keeping the valve rods in tension and preventing any
shock from backlash when the oscillating movement of the rods is reversed. By
connecting the openings p² with the interior of the valve chest I may obtain a
higher pressure behind the pistons p and thus if required reduce their size. In
order to reduce the clearance spaces I provide the pistons h with conical
projections p' which fit into the conical ports e.
Each air compressing cylinder is driven direct from a single acting stea n
cylinder m as shown. In order to keep the bearings of the connecting rods and
crankshaft in constant compression I only admit the steam from the boiler to the
front ends of the cylinder hence during the forward strokes the bearings are
compressed by the resistance of the air in the cylinder a, while during the return
stroke the bearings are compressed by the steam in the cylinders m. The latter
may be worked either as single cylinders or as compound cylinders but in either
case I prefer to work them as illustrated in Fig. 3 in the same manner as Cornish
pumping engines, that is to say after the steam has worked in the front end of the
cylinder it is during the forward stroke exhausted into the back end of the same
cylinder, giving equal pressure on both sides of the piston during the forward.
stroke. The exhaust takes place from the back end of the cylinders during the
return stroke. In this manner the range of temperature is considerably reduced in.
the front end of the cylinder. The cylinder have steam jackets and the air
cylinders have water jackets as usual. In case when the quantity of compressed
air is variable so that the engine cannot work continuously, I couple two or more.
sets of them together with their cranks at such angles that they become self starting,
and will stop when the air pressure exceeds that for which the power of the steam
cylinders is arranged and will start when the pressure in the air receiver falls below
this pressure.
For the purpose of driving the air compresser I may also use a vertical two
cylinder double acting steam engine running at a high speed of rotation and driving
a crank shaft with two cranks. The two single acting air compressing cylinders.
with their valve chest or chests on the top would then be driven from the said shaft
by means of cranks placed opposite to each other and connecting rods jointed to.
deep hollow plunger pistons. In order to balance the rotative force of the engine
with that of the air compressor and at the same time to balance the moving parts
of the engine as nearly as possible I find that the leading crank of the steam engine
should be about 45° in advance of the leading crank of the air compressor, and
that the second crank of the steam engine should be about 150° to 160° behind the
leading crank of the engine. The engine should have small clearance spaces and
only a small amount of compression. The exact details of the steam distribution
vary somewhat with the ratio of compression in the air cylinders, if this ratio is
small that is when the air is compressed to a low pressure in the air compressing
cylinders then it is comparatively easy to arrange the steam distribution so that the
rotative effects on the four cranks are balanced at each point of their travel.

page_text: For high air pressure it is of great advantage to perform the compression in two
stages. This can be done without any material alteration of the patterns or
general design of the air compressor by reducing the volume of one of the single
acting air cylinders either by decreasing the diameter of the cylinder or by
decreasing the length of the crank. The air is then first compressed' in one of
the cylinders from the pressure of the atmosphere into an intermediate air receiver
where it is cooled down to the initial temperature either by making the receiver
with a sufficiently large surface to lose the heat of compression by radiation
or by circulating water through the receiver as it is generally done in surface
condensers for steam engines. The air from the intermediate air receiver is
then passed into the second air cylinder and there compressed to the required
pressure. The reduction in the ratio of compression by working in this manner
is very considerable as the ratio of compression in each air cylinder is only
equal to the square root of the total ratio of compression. The total strain
on the crank shaft and connecting rod bearings is in this manner reduced
to one fourth of what it would be in a single cylinder of the same diameter
and the losses due to heating the air and' to clearance spaces are considerably
reduced.
The division wall which is provided in the valve chest when the compressor is
made as a stage compressor must be made airtight one half of the valve chest being
used as the low pressure valve chest, and the other half being used as a high pressure
valve chest.
Having now particularly described and ascertained the nature of my said inven-
tion and in what manner the same is to be performed. I declare that what I
claim is :-
)
1. The application and use of sliding valves working under compressed air
pressure in a valve chest or chests arranged at the end of single acting air
compressing cylinders and of steep thread screw gcar for working the said
valves.
2. The construction of sliding valves and gear for working the same as describe!
and shewn.
3. In combination with the eccentric for working the release valve of an air
compressor a steep threaded sleeve with means for shifting said sleeve along the
eccentric shaft and means for indicating the degree of compression of the air
substantially as described and shewn.
4. The valve chest with air inlet port c¹ and conical ports e to the air compressing
cylinder in combination with conical projections h' on the piston adapted to fill said
conical ports.
5. A pair of single acting air compressing cylinders in combination with a pair
of single acting directly driving steam cylinders and a crank shaft worked thereby
and having the cranks opposite to each other, all so arranged that the bearings of
the connecting rods and the crank shaft are kept in compression, substantially as
described.
6. The construction of air compressor shewn and described in which a pair of
single acting air compressing cylinders are driven directly from a pair of single
acting steam cylinders working with the so-called Cornish cycle.
Dated this 1st day of November 1895.
JENSEN & SON,
77, Chancery Lane, London, W.C., Patent Agents.
JENSEN & SON,
77, Chancery Lane, London, W.C., Patent Agents.