IMPROVEMENTS IN APPARATUS FOR COMPRESSING OR EXHAUST- ING AIR
Year: 1878

page_text: LETTERS PATENT to William Edward Newton, of the Office for Patents,
66, Chancery Lane, in the County of Middlesex, Civil Engineer, for the
Invention of "IMPROVEMENTS IN APPARATUS FOR COMPRESSING OR EXHAUST-
ING AIR," A communication from abroad by William Frazer Garrison, of
Brooklyn, in the State of New York, United States of America.
Sealed the 7th March 1879, and dated the 18th September 1878.
PROVISIONAL SPECIFICATION left by the said William Edward Newton
at the Office of the Commissioners of Patents on the 18th September 1878.
WILLIAM EDWARD NEWTON, of the Office for Patents, 66, Chancery Lane, in the.
County of Middlesex, Civil Engineer "IMPROVEMENTS IN APPARATUS FOR COM-
PRESSING OR EXHAUSTING AIR." [A communication from abroad by William
Frazer Garrison, of Brooklyn, in the State of New York, United States of
America.]
This Invention relates more particularly to that class of air compressors or
exhausters in which two pistons are mounted on the same rod or connection, but at
opposite ends thereof, and are made to work in separate cylinders arranged on the.
same longitudinal line.
.
The two cylinders are of the same dimensions and constructed in the same
manner. They are of uniform diameter throughout, and are provided with cylinder
heads which are bolted to the end of the flange like an ordinary steam cylinder.
The said opening for the escape of the compressed air is of peculiar form. It.
consists of a narrow annular slot cut in the cylinder and communicating with an
annular passage cast on to the cylinder and to which is adapted an exit pipe which,
conducts the compressed air to any place where it may be required. This annular..
D

page_text: slot is covered by a cylindrical valve provided with a stem which passes through
an air-tight gland in the cylinder head or end plate of the cylinder. The valve
stem carries at its outer end a circular disc which works in a short cylinder cast on
or bolted to the cylinder head. By this arrangement of parts I obtain a shallow
vacant space between the cylindrical valve and the end of the cylinder, and another
space outside and between the cylinder head and the circular disc of the valve stem.
The space inside the cylinder between the valve and the end of the cylinder com-
municates with the exit air pipe, and the space outside the cylinder and between
the circular disc and the cylinder head communicates with the outer air. These two
narrow spaces therefore act as air cushions, the elasticity of the confined air serving
to bring the valves back to their normal position.
The openings for the admission of air to these spaces are so arranged that when
the cylindrical valve on the one hand, or the circular disc on the other, approach
the fixed head of the cylinder, these moving parts will cover the exit openings,
and the air confined in the narrow spaces above mentioned will be trapped.
A large central hole is drilled in each of the pistons to receive a cylindrical valve
which is capable of a limited amount of motion up and down on its seat. It is
made in the form of a hollow cylinder which is closed at the front end, but it is
open at the back which is in free communication with the external air. A number of
holes arranged in the form of a ring are drilled in the side of the valve and near
the front end thereof, and as the cylindrical valve closely fits the hole in the piston
it follows that when the front end of the valve is flush with the face of the piston
the holes in the valve will be covered and no air can pass through, but when the
valve is thrust forward the end thereof will project beyond the face of the piston
and will expose the holes, so that air from behind can pass through into the cylinder.
The cylindrical valves of the two pistons are connected together by straps or rods
so that they will act in unison. Their action is of course but limited, and when
one is opened the other is closed. To the piston rod or connecting piece of the two
pistons is attached a cross head, which is actuated by a small engine by means of
suitable connecting rods. The action of the several parts is as follows:-When one
of the pistons advances in its cylinder it will compress the air before it, and when
the pressure has arrived at a certain point the cylindrical valve will yield before it
and will be forced back, thereby uncovering the annular slot through which the com-
pressed air will rush to the exit passage. As there is a cushion of air at the back
of the cylindrical valve it will be evident that immediately the piston begins to
recede the valve will be forced forward again by the air bebind it and will cover
the narrow annular slot which constitutes the exit aperture from the cylinder.
When the piston moves back its small cylindrical valve will be opened, and the string
of holes made therein will be uncovered so that air from the outside will rush
through into the cylinder and thereby fill the latter ready to be compressed by the
next advance of the piston.
It will of course be understood that both the pistons act alternately in exactly
the same manner, one piston drawing in air while the other compresses the air
before it. These piston valves for the admission of air are so constructed that when
they move forward they meet with a cushion of air which prevents them from.
striking their seat and also serves to bring them back to their normal position.
As a modification of the above-described arrangement, the exit and supply valves
may be combined, and plain pistons of the ordinary construction may be employed.
There are two working cylinders as in the former instance, and the pistons are
mounted on the same rods at opposite ends as before, so that they will work in
unison and alternately exhaust or compress the air as may be required.
The inlet valves in the pistons may, if desired, be actuated by the rocking motion
of the cross head or by any other suitable mechanical device, although for simplicity
of construction it is considered preferable that the two pistons should be mounted
on opposite ends of the same shaft so as to work in two cylinders arranged in the
same longitudinal line, it will sometimes be found convenient (especially when more

page_text: than two compressing or exhausting cylinders are employed) to arrange the cylinders
side by side and to work the pistons separately by means of a series of cranks on
a main driving shaft.
.
'
The construction and operation of the valves are however the same in all cases.
A regulator is adapted to the apparatus at some convenient part between tho
steam or other motive-power engine and the air compressor, and is connected with
the throttle valve of the engine, so that if the flow of compressed air be suddenly
arrested (in consequence of not being required to be used for a short time) the action
of the engine may be reduced or modified accordingly, so as to produce an equilibrium
of pressure between the motive-power engine and the pressure of air in the com-
pressor.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said William Edward Newton in the Great Seal Patent Office on the 18th
March 1879.
WILLIAM EDWARD NEWTON, of the Office for Patents, 66, Chancery Lane, in the
County of Middlesex, Civil Engineer. "IMPROVEMENTS IN APPARATUS FOR COM-
PRESSING OR EXHAUSTING AIR." A communication from abroad by William
Frazer Garrison, of Brooklyn, in the State of New York, United States of
America.
This Invention of "Improvements in Apparatus for Compressing or Exhausting
Air" relates more particularly to that class of air compressers or exhausters in
which two pistons are mounted on the same rod or connection but at opposite ends
thereof, and are made to work in separate cylinders arranged on the same
longitudinal line.
In the accompanying Drawing Fig. 1 is a longitudinal vertical section of the
improved air-compressing apparatus. It will be seen that the two cylinders a, a,
are of the same dimensions and are constructed in the same manner; they are of
uniform diameter throughout and are provided with cylinder heads a' which are
bolted to the end flanges of the cylinders a, a, like the heads of an ordinary steam
cylinder. The exit opening for the escape of the compressed air is of peculiar form.
It consists of a narrow annular slot b cut in the cylinder and communicating with
an annular passage 61 cast on the cylinder, and to which is adapted an exit pipe c
hich conducts the compressed air to any place where it may be required. This
ular slot b is covered by a cylindrical valve d provided with a stem d' which
esses through an air-tight gland e in the cylinder head or end plate a¹ of the
linder. The valve stem d¹ carries at its outer end a circular disc d² which works
in a short cylinder f cast on or bolted to the cylinder head a¹. By this arrange-
ment of parts I obtain a shallow vacant space between the cylindrical valve d and
the end of the cylinder, and another space outside and between the cylinder head
and the circular disc d2 of the valve stem d. The space inside the cylinder a
between the valve d and the end a¹ of the cylinder communicates with the exit air
pipe c by a branch c¹, and the space outside the cylinder and between the circular
disc d² and the cylinder head communicates with the outer air by means of a hole f¹.
These two narrow spaces therefore act as air cushions, the elasticity of the confined
air serving to bring the valves back to their normal position. The openings for the
admission of air to these spaces are so arranged that when the cylindrical valve d
on the one hand, or the circular disc d³ on the other, approach the fixed head a¹ of
the cylinder these moving parts will cover the exit openings b and ƒ¹, and the air
confined in the narrow spaces above mentioned will be trapped. A large central
hole is bored in each of the pistons h to receive a cylindrical valve g which is
capable of a limited amount of motion up and down on its seat. It is made in the
form of a hollow cylinder which is closed at the front end but is open at the back
which is in free communication with the external air. A number of holes arranged
in the form of a ring are drilled in the side of the valve g and near the front end
thereof, and as the cylindrical valve g closely fits the hole in the piston h it follows
that when the front end of the valve g is flush with the face of the piston as in the
right-hand cylinder in Fig. 1, the holes in the valve g will be covered and no air can
pass through, but when the valve g is thrust forward the end thereof will project
beyond the face of the piston h, as shewn in the left-hand cylinder, and will expose
the holes in the valve so that air from behind can pass through the valve into the
cylinder a. The cylindrical valves g, g, of the two pistons h, h, are connected
together with straps or rods g' so that they will act in unison. Their action is of
course but limited, and when one is opened the other is closed. To the piston rod
or connecting pieces of the two pistons h is attached a cross head i which is
actuated by a small engine by means of suitable connecting rods.

page_text: The action of the several parts is as follows:-When one of the pistons h
advances in its cylinder a it will compress the air before it, and when the pressure
has arrived at a certain point the cylindrical valve d will yield before it and will be
forced back, thereby uncovering the annular slot b through which the compressed
air will rush to the exit passage c. As there is a cushion of air at the back of the
cylindrical valve d it will be evident that immediately the piston h begins to recede
the valve d will be forced forward again by the air behind it and will cover the
narrow annular slot b which constitutes the exit aperture from the cylinder a.
When the piston h moves back, its small cylindrical valve will be opened and
the string of. holes made therein will be uncovered so that air from the outside will
rush through the valve into the cylinder, and will thereby fill the latter ready to be
compressed by the next advance of the piston. It will of course be understood that
both the pistons h, h, act alternately in exactly the same manner, one piston drawing
in air while the other compresses the air before it. These piston valves g for the
admission of air are so constructed that when they move forward they meet with a
cushion of air which prevents them from striking their seat and also serves to bring
them back to their. normal position.
1.
As a modification of the above-described arrangement, the exit and supply.
valves may be combined and plain pistons of the ordinary construction may be
employed.
Fig. 2 is a longitudinal vertical section of a cylinder piston and valves constructed
on the improved plan; a is the compressing cylinder as in the former instance, but
in this case the valve d rests against a shoulder a² which forms its seat near the
outer end of the cylinder against which it is pressed by the coiled springs j. j. The
stem d' of the valve.d.is tubular and is provided internally with another tube d
which forms the bearing or guide for the stem k¹ of a disc valve k contained within
and concentric with the circular valve d. The disc valve k is kept down on its
conical seat by the coiled spring 7. The tubular stem d¹ of the valve d has openings
made in it coincident with the air supply opening m, so that the outer air has free
access through the hollow stem d¹ to the valve of the disc valve k. The operation
of the several parts is as follows:-Upon the piston h being drawn back by the:
cross head and the connecting strap h¹ a vacuum will be formed between the back of
the piston and the face of the disc valve k, the consequence will be that the pressure.
of air behind the disc k will overcome the tension of the spring and will force
forward the disc and allow air to pass its edge into the cylinder a. When the
piston h reaches the end of its stroke or begins to return the spring / will draw
back the disc k and cut off the supply of air which will be compressed in the
cylinder á until the pressure will overcome the force of the springs j, j, when the
valve d will be lifted off its sent a², and the compressed air allowed to pass to the
exit aperture n which will conduct it to where it is to be used. It will be seen that
the amount of motion of which the valve d is capable is very small, but as air can
pass in at every point throughout its entire circumference the superficial area will
be found sufficient. It will of course be understood that there are two working
cylinders as in the former instance, although only one is shewn in the Drawing, and
the pistons h, h, are mounted on the same rod or connecting strap h' but at opposite
ends, as before, so that the two pistons will work in unison and will alternately
exhaust and compress the air as may be required.
The inlet valves in the pistons in Fig. 1 may if desired be actuated by the rocking
motion of the cross head i, or by any other suitable mechanical device.
Although for simplicity of construction it is considered preferable that the two
pistons h, h, should be mounted on opposite ends of the same shaft so as to work in
two cylinders arranged in the same longitudinal line, as above shewn and described,
it will sometimes be found convenient (especially when more than two compressing
or exhausting cylinders are employed) to arrange the cylinders a, a, side by side and
to work the pistons h separately by means of a series of cranks on a main driving
shaft. The construction and operation of the inlet and outlet valves are however
the same in all cases.

page_text: A regulator may be adapted to the apparatus at some convenient part between
the steam or other motive-power engine and the air. compressor, and may be
connected with the throttle valve of the motive-power engine which actuates the
pistons of the compressing apparatus so that if the flow of the compressed air be
suddenly arrested (in consequence of it not being required to be used for a short
time) the action of the engine may be reduced or modified accordingly so as to
produce an equilibrium of pressure between the motive-power engine and the
pressure of air in the compressor.
At Fig. 3 is shewn in vertical section a form of regulator suitable for the purpose.
The regulator consists of a small cylinder o provided with a piston p and adapted
to the end of a pipe q connected with the compressed air pipe of the compressing
apparatus. Should the pressure of the air become excessive it will lift the piston p
in the cylinder o, and by means of the stem p' and lever r will close the throttle
valve on the steam pipe of the motive-power engine and thus stop the action of the
pistons h, h, of the compressing apparatus. If desired, a lateral opening s in the
regulator cylinder o may allow compressed air to pass from the pipe q to the steam
chest of the motive-power engine, so that in case the compressed air is shut off from
its regular work for any cause it will flow into the motive-power engine and produce
a partial equilibrium between the piston of the compressing apparatus and the
piston of the motive-power engine.
Having now described the Invention that has been communicated to me by my
foreign correspondent as aforesaid, and having explained the manner of carrying
the same into effect, I claim as the Invention secured to me by Letters Patent as
aforesaid,―
First. The arrangement and construction of parts shown in Fig. 1, including
particularly the annular slot b made in the compressed air cylinder for the exit
therefrom of the compressed air, also the cylindrical valve with its circular disc
working in a small cylinder cast on the cylinder head, as and for the purposes herein
set forth.
I also claim the adaptation to the piston of the inlet valve for the admission of
air to the compression cylinder, as and for the purposes herein set forth.
I further claim the combination of the inlet and outlet valves in one instrument,
as and for the purpose set forth and shewn in reference to Fig. 2.
Lastly. I claim the regulator constructed, arranged, and operating as shewn and
described in reference to Fig. 3.
In witness whereof, I, the said William Edward Newton, have hereunto set
my hand and seal, the Fifteenth day of March, in the year of our Lord
One thousand eight hundred and seventy-nine.
W. E. NEWTON. (L.S.)