Improvements in the Method of and Apparatus for Compressing Air.
Year: 1893

page_text: Date of Application, 20th Sept., 1893
Complete Specification Left, 1st June, 1894-Accepted, 7th July, 1894
PROVISIONAL SPECIFICATION.
Improvements in the Method of and Apparatus for Compressing Air.
I THOMAS ELWELL FILS, of 194 Avenue de Paris, Plaine Saint Denis, (Seine)
France Engine Builder do hereby declare the nature of this invention to be as
follows:-
This invention relates to apparatus for compressing air in which two double
acting pumps are employed serving to compress the air in four successive stages in
capacities whose volumes diminish inversely to the pressures therein, the capacities
being calculated so that the resistance due to said pressures will be equal in both
cylinders and on each side of the pistons.
Reference is to be had to the accompanying drawings,
Figure 1 of which represents a sectional elevation, and Figure 2 a front elevation
of the apparatus.
Figure 3 is a section of the two cylinders taken on lines 1-1, 2-2 of Figure 1.
The apparatus comprises two pumps a a¹ of different dimensions, whose pistons
are operated by any suitable means, but in the example shown are driven by piston
rods c c on pistons d, the motion being regulated by means of fly wheel e on crank
shaft driven by connecting rods ee. The two compressing cylinders a a¹ are
cast in one and are enclosed in a casing containing water in which are placed two
coils the coil being the delivery pipe from the large cylinder a to the small
cylinder a' and serving as an intermediate reservoir between the cylinders while
the coil which is the delivery from the smaller cylinder a', serves to cool the air
on its passage to a filtering column or receiver. are the covers of the cylinders
furnished with suction valves jjj respectively held to their seats by means of
coiled springs, or other suitable means, and k kare the glands. The pistons b¹
are provided with valves which control communication between the opposite
ends mand and m' and n' of the cylinders a and a. o is a valve which controls
communication between the end of the cylinder a and coil h, and o' is a valve
which controls communication between the end n' of the cylinder a' and the coil h'.
The coils are provided with relief valves p p'. s is a pressure gauge on
cover of the small cylinder for indicating the pressure of air in coil h, and s¹ is a
similar gauge on coil for indicating the pressure of the air as it leaves the
apparatus. Air is drawn into the large cylinder a by piston b through the spring
pressed valves disposed around the cover i and simultaneously therewith a certain
quantity of water is introduced into the cylinder through a finely perforated pipe 7
together with a small quantity of oil supplied by a container q mounted on the
centre of the cover. The piston bin rising, compresses the air contained in the
upper end m of the cylinder and forces it together with the water into the lower
end n through the valves . The piston in its downward stroke forces out the air
from the end n into coil (which serves as an intermediate reservoir) through the
The operations of the two pistons are identical, thus the cooled air from
the coil or intermediate reservoir enters the smaller cylinder a' through valve j¹,
the piston in its upward stroke forces the air from the space m' through the valve (1
into the space n', and on its downward stroke forces the air from the space n' into
coil through the valve o'; the air then passes out from coil through the valve r
to a filtering column or receiver.
valve o.
The following are the advantages of this invention :-
(1) The employment of four successive stages of compression permits of the
employment of a relatively low pressure in the first stage, and consequently of
reducing to a minimum the unutilised pressure in the dead spaces during this stage.

page_text: (2) Effecting the four stages of compression in two cylinders separated by an
intermediate reservoir, permits of the efficient cooling of the air on its discharge
from the first cylinder or second stage, before it enters the second cylinder for
undergoing the third and fourth compressions. Moreover the passage of the air
through a coil after its final compression permits of the air being cooled before
being forced into the reservoir.
The water introduced into the compressor during the first stage and which
should circulate throughout the successive stages, is always placed above the
discharge valves so that it can be forced out immediately communication is
established between two successive stages. Were the water to remain until the end
of the stroke, accidents would be liable to occur.
As the third and fourth stages of compression are effected in a cylinder and
piston of relatively small diameter, there will be little difficulty in ensuring tight
joints.
By means of the gauges, the pressures existing in the compressor may be readily
ascertained and the working of the apparatus controlled.
The whole of the principal parts of the compressor may be readily dismounted
and the packings renewed.
Dated this 20th day of September 1902
T. ELWELL FILS,
By A. M. & Wm. Clark,
53, Chancery Lane, London, Chartered Patent Agents.
COMPLETE SPECIFICATION.
Improvements in the Method of and Apparatus for Compressing Air.
I, THOMAS ELWELL FILS, of 194 Avenue de Paris, Plaine Saint Denis, (Seine)
France, Engine Builder, 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 :—
This invention relates to an air compressor comprising two vertical double acting
pumps whereby the air is compressed by four successive stages into spaces whose
volumes diminish inversely as the pressures to be obtained, the areas being so
calculated that the pressures will be sensibly equal in both cylinders and on both
sides of the pistons.
Reference is to be had to the drawings left with my Provisional Specification,
Figure 1 of which represents a sectional elevation, and Figure 2 a front elevation
of the apparatus.
Figure 3 is a section of the two cylinders taken on lines 1-1, 2-2 of Figure 1.
The apparatus comprises two pumps a a¹ of different diameters, having trunk
pistons, the capacities being so calculated that the pressures will be sensibly
equal in each of the cylinders and at each side of the pistons bb. These pistons
may be operated by any suitable means, but in the example shown in Figures 1
and 2 they are actuated through rods e c by pistons d, the motion being regulated
by the fly wheel e on crank shaft to which the pistons are coupled by rods el el.
The two compressing cylinders a a' are cast in one and are enclosed in a casing y
containing water, in which are placed two coils /, /', the coil h being an intermediate
receiver between the large and the small cylinders while the coil A', which is the
delivery from the smaller cylinder a', serves to cool the air on leaving the compressor
and before passing to the separator or receiver. In the covers i, i, of the cylinders
are fitted suction valves j, j, j', respectively held to their seats by means of coiled
springs or other suitable means. The lower ends of the cylinders are provided
with cup leather packings retained by glands k, k¹, through which the trunks of the
pistons b, b', pass. The pistons are provided with valves 1, 1, which control com-
munication between the opposite ends m and n and m¹ and n' of the cylinders a

page_text: and a respectively, and valves o o' respectively control communication between the
end of the cylinder a and coil h, and between the end n' of the cylinder a' and the
coil . The coils h h are provided with relief valves pp' and a pressure gauge s
on the cover of the small cylinder indicates the pressure of air in coil h, whilst a
similar gauge son coil indicates the pressure of the air as it leaves the apparatus.
Air is drawn into the large cylinder a by piston b through the valves; disposed in
a circle in the cover i and simultaneously therewith a certain quantity of water is
introduced into the cylinder through a finely perforated pipe q together with a
small quantity of oil supplied by a container q' mounted on the centre of the cover.
The piston bin rising compresses the air contained in the upper end m of the
cylinder and forces it together with the water into the lower end n through the
valves . The piston in its downward stroke forces out the air from the end n
through valve o into coil which serves as an intermediate receiver. The operations
of the two pistons are identical, the cooled air from the coil or intermediate
receiver entering the smaller cylinder a through valve j', the piston in its upward
stroke forcing the air from the space m¹ through the valve into the space n', and
on its downward stroke forcing the air from the space n' through the valve o', into
coil whence the air passes through the valve r to a separator or receiver.
The following are the advantages of this invention:
h
(1) The employment of four successive stages of compression permits of a
relatively low pressure for the first stage, thus reducing to a minimum the pressure
unutilised in the clearance spaces during this stage.
(2) Dividing the four stages of compression between two cylinders separated by
an intermediate receiver, permits of the efficient cooling of the air on its discharge
from the first cylinder or second stage, before it enters the second cylinder for
undergoing the third and fourth compressions. By the passage of the air through
a coil after its final compression it is cooled before being forced into the reservoir.
(3) The water introduced into the compressor during the first stage and which
should circulate throughout the successive stages, is always above the discharge
valves so that it will be forced out immediately they open to establish communication
between two successive stages whereas were the air to be discharged before the
water accidents would be liable to occur. ""
(4) As the third and fourth stages of compression are effected by a cylinder and
piston of small diameter, tight joiuts are easily ensured.
(5) By means of the gauges the pressures may be readily ascertained and the
working of the apparatus controlled.
(6) The whole of the principal parts of the compressor may be readily dismounted
and the packings renewed.
Having now particularly described and ascertained the nature of the said
invention and in what manner the same is to be performed I declare that what
1 claim is :-
A vertical air compressor operating by four stages of compression and with an
intermediate receiver the apparatus consisting essentially of two double acting
compression pumps by which the air is compressed in four successive stages into
spaces whose capacities are inversely as the pressures, substantially as hereinbefore
described and illustrated in the drawings.
£T 1004
THOS. ELWELL FILS,
By A. M. & Wm. Clark,
53, Chancery Lane, London, Chartered Patent Agents.