Year: 1898

page_text: I, THOMAS WALTER BARBER, of 17 and 18, Tothill Street, Westminster, S.W.,
Engineer, do hereby declare the nature of this invention to be as follows:-
My improvements relate to engines for compressing air or gases in one or more
cylinders with the object of absorbing from the air or gas under compression
its heat of compression before it is delivered out of the cylinder; also to improved
positive motion for the valves of such air compressors, and to valves and gear
for utilising the pressure in the clearance spaces.
I provide the air cylinders with a number of tapered cooling tubes of copper
or bronze, fixed to the cylinder covers, and a similar number of displacers of the
same form, but slightly smaller in diameter are fixed to the piston and recipro-
cate within the tubes, the ends of which discharge past delivery valves into a
box and air main. The air is thus compressed by the piston into the tubes and
passes through them to the delivery valves.
The tubes are made either of plain metal, or may be fluted longitudinally or
grooved spirally inside and out in order to increase their cooling surface, and
they are externally cooled by either a current of air only, or air with fine water
spray, or by water sprinkled over them, or by a water bath.
I construct the tube ends to fit packing boxes, fitted with glands so that they
may be easily removed or replaced."
The delivery valves are of annular or disc form, arranged as a single valve,
covering all the tubes, or as several valves covering them in groups. They are
either lifted or partially revolved by an air piston open to the air cylinder and
taking its pressure from it, exhausting at the end of the stroke of the main piston,
the valves being kept to their seats by springs. I also use a positive gear for
operating these valves worked by cams from the engine shaft. The suction
valves are either of disc form or of the Corliss type, in the first case moved by the
frictional movement of a stuffing box on the main piston rod or in both forms of
valve by a positive gear from the main shaft.
In order to utilise the pressure of air in the clearances at the end of the stroke
I provide a valve of the slide or Corliss type which opens communication between
both ends of the cylinder at the instant the suction valve has closed, or provide
bye-pass recesses in the cylinder walls at each end of the stroke, by which nearly
all the pressure in the clearances is transferred to the fresh charge of air at the
opposite end of the cylinder.
11th date of Tatuar 1808

page_text: Improvements in Air Compressors.
I, THOMAS WALTER BARBER, of 17 and 18, Tothill Street, Westminster,
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 improvements relate to apparatus for cooling the air while under com-
pression in the cylinder before it passes the delivery valves, and to improved forms
of valves having positive movements for both inlet and delivery.
To effect the first object it is necessary to greatly increase the cooling surfaces
of the cylinder and to divide or cut up the body of air it contains into thin sheets
or films in close contact with the cold surfaces. This I effect by extending the
cylinder covers A A, Fig. 1, into a number of thin metal (preferably copper)
tubes B B, parallel with the cylinder C, their outer ends being covered by the
delivery valves D D, as in my former Patent No. 546, 1889.
Within these tubes reciprocate the plungers or displacers E E which are fixed
to the piston F and work with a small clearance between plunger and tube. The
tubes and plungers may be either tapered or parallel the plungers being preferably
of aluminium or one of its alloys.
I make the tubes and plungers with ends and packing boxes as shewn in Fig. 2
where B is the tube, having the end flanged at B₁ and packed with either a
gland B2 or as in Fig. 3 with an undercut packing groove, or as in Fig. 4, secured
with a plain flange B3 which may cover several tubes.
In each case my object is to prevent the tube being drawn out in working
and to admit of its removal for repair, as also of the plunger within it, without
removing the cylinder cover.
To increase still further the cooling surfaces I sometimes flute the tubes
externally and internally or form a spiral V grooving all over both surfaces as
shewn in Fig. 4, which nearly doubles their cooling surface. When parallel
tubes and plungers are used I join the tubes to the covers either as Figs. 2-4
or as shewn in Fig. 5 by screwed ends and a packing groove, or the tubes (taper
or parallel) may be expanded into plain holes in the covers as is commonly done
with boiler tubes.
an air
The tubes are cooled externally by (a) a current of cold air driven by
propeller (b) by water spray, or (c) by a water bath- and b may be combined.
The delivery valves may be plain circular valves lifting off their seats against
springs, or as shewn in Fig. 1, slotted circular dises D D oscillating on centre pins
and operated together by a toothed ring H to open and close the tube ends; or
one large annular disc Ġ or plate may be used in the same way as in Fig. 6 to
cover all the tube ends. To operate these valves I employ a jockey cylinder J,
Fig. 6, the piston K of which is open to the air cylinder C so that when the
pressure in the air cylinder at any point of the stroke reaches that in the delivery
main and the valve becomes in equilibrium it is partially revolved by the jockey
cylinder rod L to open the tube ends. The valve is closed at the end of the stroke
by a spring M when the jockey cylinder exhausts; or by using the air pressure
from the delivery main on the opposite side of the jockey piston K. Dashpots
are used to cushion the action of the jockey piston.
I also employ a positive motion by cams on the crank shaft to operate the
delivery valves, having a variable or automatic opening movement. This I
effect in the following way:-When a constant pressure is maintained in the air
mains a cam, Fig. 7, can be used to give an opening movement to the delivery
valve at a constant point in the stroke determined by trial, for which purpose the

page_text: angular position of the cam N as regards the crank can be adjusted by a hand-
wheel and sleeve P; the closing being effected at the end of the stroke by a
fixed cam Q, the delivery valve being of the forms in Figs. 1 or and oscillated
by the arm R.
When the pressure of air in the mains is either fixed or variable I also employ
the following modification which is automatic and requires no gear to operate it.
A jockey cylinder J, Fig. 8 has one side of its piston always open to the cylin-
der C by a port S which being covered by the main air piston C before it reaches
the end of its stroke, is opened at the end of the stroke when the piston C
it to exhaust the jockey cylinder J into the free air space C². The other side of
the jockey piston K is always open to the air main and its piston rod is connected
to the delivery valve G to give it the necessary oscillatory opening and closing
movements cushioned by dashpots as described under Fig. 6.
passes
The inlet valve, which always is required to open and close exactly at the ends
of the stroke, I make of disc form W, Fig. 9 and either move it by the friction
of a stuffing box W on the piston rod or by a cam V on the crank shaft communi-
cating its motion by rods T and levers U as in Fig. 9.
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. In an air compressor employing tubular coolers and displacers (as in my
former Patent, No, 546, 1889) the construction of the tube and displacer ends
and modes of packing same and of attachment to the cylinder covers, pistons and
delivery valve boxes, shewn and described under Figs. 2, 3, 4, 5.
2. The method of increasing the cooling surfaces of such tubes by fluting or
grooving as shewn and described under Fig. 4.
3. In an air compressor as (1) the method of cooling such tubular surfaces by
cold air, water spray or both combined as described.
4. In an air compressor employing tubular coolers and displacers as (1) the
construction and methods of working oscillating disc or plate valves, covering the
tube ends by jockey or pilot cylinders J taking air from the main air cylinder C
and automatically governed by the main air piston as shewn and described severally
under Figs. 6 and 8.
5. In an air compressor as (1) the construction and method of working disc
delivery valves as shewn and described in Figs. 1 and 6 by positive cam movement
from the crank shaft controlled for any required main pressure by the hand
governing gear as shewn and described under Fig. 7.
6. The combination of an air cylinder C, and piston C, Fig. 1, tubular
coolers B B, and displacers E E, with jockey cylinder J and gear for operating
same, an annular delivery valve G (or several disc valves as described under Fig. 1)
a disc inlet valve and cam motion for operating same, Fig. 9, as an air compressing
and cooling machine as shewn and described.
1000