Improvements in Air Compressors.
Year: 1893

page_text: COMPLETE SPECIFICATION.
Improvements in Air Compressors.
I, PETER BROTHERHOOD, of Belvedere Road, Lambeth, in the County of
Surrey, Engineer, 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 :-
My invention relates to the construction of an air compressor in which the
compression of the air is effected by pumps operating in 3 stages, these pumps
being arranged in a compact and accessible form, with ample means of cooling the
air during compression, as I shall describe with reference to the accompanying
drawings.
Fig. 1 is a vertical section on the line X X of Fig. 2 which is a plan ;
Fig. 3 is a part vertical section on the line Y Y of Fig. 4 which is a part sectional
plan on the line Z Z of Figure 3, and
Fig. 5 is a section of the cover on the line W W of Fig. 2.
A central cylinder A is fitted with a hollow trunk piston B. The cylinder cover
has through it passages covered by an annular valve C which is held up to its
seating by springs e encircling guide bolts attached to the valve. Through the
piston B there are passages to the annular space a surrounding the trunk, these
passages being fitted with conical eduction valves D held to their seats by springs.
From the space a at the lower end of the cylinder A there are two horizontal
passages fitted with valves E leading to the upper ends of two small cylinders a¹ a²
which are fitted with plungers 61 63, and from these cylinders there are passages
fitted with valves F to a pipe coil G, which, as well as the cylinders A, a¹ and a³,
is enclosed in a water tank H. h is the pipe which supplies water under pressure
to the lower part of the tank H, from the upper part of which there is a com-
munication to a space in the cylinder cover, from which space a pipe I extends
into the interior of the piston B. The pipe I is enclosed within another pipe J
which extends through packing up to a space in the cylinder cover and from this
space there is an outlet passage O. The trunk of the piston B passes through a
stuffing box in the bottom of the cylinder A and is attached to a crosshead N, to
which also are attached the plungers 6162 which pass through stuffing boxes into
the cylinders a¹ a² respectively. The crosshead N being caused to reciprocate by a
suitable motor engine, during the down stroke of the piston B air is drawn in
through the cover past the valve C, and air previously partly compressed in the
annular space a is expelled from a past the valves E into the cylinders a' a².
During the upstroke of the piston B the air which had been drawn into A above B
is forced past the valves D in to the annular space a, and air which had been
previously sent into the cylinders a' a² is discharged from them past the valves F
into the coil G whence it passes by an outlet pipe f to any suitable receptacle for
the air thus highly compressed by the three stages of pumping described. While
the piston B is operating on the air, it during its descent is drawing water from the
tank H by the pipe I into its interior and during its ascent it expels the water by
the pipe J circulation of water through the tank and the interior of the piston B
being thus maintained, keeping the metal and the compressed air comparatively
cool. The cylinder cover is provided with a relief valve M. Instead of only two
cylinders a¹ a there may be a greater number of these arranged around A and
having their plungers attached to the crosshead N, which, in that case, would have
a corresponding number of arms, or might be in the form of a disc.
Instead of passing the plungers 16 through stuffing boxes, they may be packed
as shewn in Fig. 6. A packing P internally coned is expanded by a cone within it
which is subject to the pressure in the cylinder space above the plunger.

page_text: Having now particularly described and ascertained the nature of this inven
tion and in what manner the same is to be performed, I declare that what I
claim is :-
1.
In an air compressor, the combination of the cylinder A. having an annularly
valved cover, the trunk piston B connected to a reciprocating crosshead N and
having through it valved passages into the annular space around the trunk, several
smaller cylinders a' a' having plungers attached to the crosshead N and valved
passages from the space a to them and valved passages from them to a pipe coil G,
the water tank H, and the concentric pipes I and J, substantially as and for the
purposes set forth.
Dated this 9th day of October 1893.
ABEL & IMRAY,
Agents for the Applicant.