Improvements in Air-compressing Apparatus.
Year: 1887

page_text: [Communicated from abroad by URIAH CUMMINGS, of Buffalo, New York, United
States of America, Gentleman.]
Improvements in Air-compressing Apparatus.
1, 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 :-
This invention relates to that class of air compressors in which the air is compressed
by a reciprocating piston moving in a cylinder and which are adapted to compress the
air to a high pressure; for instance, as a motor in rock drills and other machines. The
object of my invention is to produce an air compressor of this character which can
be operated at a high rate of speed and which is durable and easily kept in order.
In the air compressors now most generally used the heat which is liberated by com-
pressing the air is removed by injecting water into the compressing cylinder, but this
is objectionable because the water often carries solid impurities with it which injure
the contact surfaces of the cylinder and piston to such an extent as to render the
renewal of these parts necessary.
My invention is designed to overcome this difficulty and the invention consists of
the improvements hereinafter fully described.
In the accompanying drawings,
Figure 1 is a side elevation of my improved air comprssor.
Figure 2 is a top plan view of the same.
Figure 3 is a top plan view of the steam and air pipes.
Figure 4 is a longitudinal section of the cylinders and connecting parts on an
enlarged scale.
Figure 5 is a sectional view of the air escape valve on an enlarged scale.
Figure 6 is a similar view of the air inlet valve on an enlarged scale.
Figure 7 is a top plan view of my improved air compressor in a modified form.
Like letters of reference refer to like parts in the several figures.

page_text: A represents the horizontal bed of the air compressor and A1, A2, the two horizontal
cylinders secured to the same and provided respectively with pistons a, a¹ which are
secured to the ends of a piston rod a². Each cylinder is closed at its inner end by a
head b which is provided with a stuffing box through which the piston rod works.
CC represent the steam valves arranged respectively in valve chests c, c', the inner
ends of which are connected with the cylinder by ports d d' through which the steam
passes to and from the inner ends of the cylinders. E represents the steam supply
pipe provided with two branch pipes e e¹ which connect with the valve chests c c¹ and
conduct the steam to the same. ff represent the exhaust ports formed respectively
in the cylinders A' A2 and connected with an exhaust pipe F by branch pipes F¹ F.
As shown in Figures 1, 2 and 4 of the drawing the steam valves C (are constructed
in the form of rock valves and provided on the outer sides of the valve chests with
arms g g¹ which are connected by a rod g³ so that both valves move in unison. Valves
of any other suitable construction may, however, be employed, if preferred.
H represents a cross head secured to the piston rod a between the cylinders A¹ A³
and represents the horizontal guide bars on which the cross head slides and which
are supported on the bed A. I represents a horizontal shaft provided with fly
wheels and journalled in bearings i formed on the bed A in rear of the cylinder A².
J represents rods which connect the cross head H with cranks j secured to the fly
wheel shaft I and whereby said shaft is rotated. K represents an excentric secured
to the fly wheel shaft I and connected with the valve arms g by a rod k so as to actuate
the valves. The latter are so arranged with reference to their respective steam and
exhaust ports that one valve admits steam to its cylinder when the other exhausts.
L L' represent the air inlet valves arranged in the outer heads of the cylinders
in a well-known manner so as to admit the external air to the cylinder when the piston
moves towards the opposite end of the cylinder. Each of these valves is provided
with a movable disc m which is attached to a bolt m¹ and closes against an annular
seat m³. The latter is formed in a casing m³ which is provided at its outer end with
openings through which the air enters, as represented in Figure 6.
NN represent the air escape valves which may be of any suitable or well-known
construction. These valves are also arranged in the outer heads of the cylinders and
connected by branch pipes n with an air pipe n' by which the compressed air is con-
ducted to a suitable reservoir or to the machine or apparatus in which the air is to be
used. Each of these escape valves is provided with a movable disc O attached to a
stem and closing against a seat O' which is formed in the casing 03, as represented
in Figure 5.
The
In the position of the parts represented in Figure 4, the steam enters the inner end
of the cylinder A¹ through the port d and drives the piston a toward the outer end of
the cylinder, thereby compressing the air before the piston and finally forcing
such air through the air escape valve N into the compressed air conduit.
piston a¹ in the cylinder A' is at the same time moved toward the inner end of
its cylinder and the steam escapes from before the piston a' through the exhaust
port while the outer air enters the opposite end of the cylinder through the open
air inlet valve L'. During the return stroke of the pistons the steam is exhausted
from the cylinder A¹ and air is admitted to the same and steam is admitted to the
cylinder A and the compressed air is expelled from the same. In this manner each
cylinder operates alternately as a steam cylinder and as an air cylinder and
each cylinder is at every other stroke supplied with steam, whereby the inner surfaces
of the cylinders and the pistons are at short intervals supplied with moisture which
ensures the smooth running of the machine, and prevents the parts from becoming
overheated.
By connecting the pistons and valves with a fly wheel shaft the machine can be
operated at a high rate of speed. The steam valve may be so constructed that the
steam is used with a proper degree of expansion.
The heat which is generated in each cylinder by compressing the air therein is
transmitted to the steam which is admitted to the cylinders and evaporates the water
mixed with the steam, thereby raising the effective steam pressure in the cylinders

page_text: beyond the pressure in the steam supply pipe and enabling the compressor to furnish
compressed air for working purposes of equal or higher pressure than the steam by
which the compressor is actuated. The useful effect of the steam is by this means
considerably increased.
If desired, the piston rod may be extended through the outer head of one of the
cylinders and the cross head may be secured to the outer end of the piston rod instead
of being arranged between the cylinders as shown. In this case, the two cylinders
can be arranged closely together and a single steam valve may be employed for con-
trolling the flow of steam to and from both cylinders, instead of two separate valves,
as shown.
If preferred, the cylinders A¹ A² may be arranged side by side, and provided with
separate piston rods, as shown in Figure 7. In this construction a single fly-wheel I¹
is employed and the rods J are connected with the piston rods by cross heads H and
with the fly shaft by cranks j on opposite ends of the shaft whereby said shaft is
rotated.
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 :-
a
First. In a steam actuated air compressor, the combination with two actuating
cylinders of equal diameters and two pistons working in the same and connected by
piston rod, of a valve mechanism whereby steam is alternately admitted to one end of
each cylinder and exhausted therefrom, air inlet and escape valves through which the
air is alternately admitted to and emitted from the opposite end of each cylinder, and
a fly wheel and shaft rotated from said piston rod and operating said valve mechanism,
substantially as set forth.
Second. In a steam actuated air compressor, the combination with two actuating
cylinders of equal diameters and two pistons working in the same and connected by a
piston rod, of separate steam valves, one applied to each cylinder, whereby steam is
alternately admitted to each cylinder and exhausted therefrom, air inlet and escape
valves through which air is alternately admitted to and emitted from the opposite
end of each cylinder, and a fly wheel and shaft connected with the piston rod, between
the cylinders, substantially as set forth.
Third. In a steam actuated air compressor, the combination with two actuating and
compressing cylinders and two connected pistons working in the same, of a valve
mechanism whereby steam is alternately admitted to one end of each cylinder and
exhausted therefrom, air inlet valves through which external air is alternately admitted
to each cylinder, air escape valves through which the compressed air is alternately
emitted from each cylinder at the same pressure, and a fly-wheel and shaft rotated
from said pistons, substantially as set forth.
Dated this 24th day of May 1887
HASELTINE, LAKE & Co.,
45, Southampton Buildings, London, W.C.,
Agents for the Applicant.