Improvements in Air and Gas Pumps and Compressors.
Year: 1897

page_text: Date of Application, 14th Dec., 1897-Accepted, 22nd Jan., 1898
[Communicated from abroad. by CHARLES CAMPBELL WORTHINGTON, Mechanical
Engineer, of Irvington, in the, County of Westchester, State of New York,
United States of America.]
Improvements in Air and Gas Pumps and Compressors.
I, HENRY EDWARD NEWTON, of the Office for Patents, 6, Breams Buildings,
Chancery Lane, in the County of London, Patent Agent, 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: -
The object of the present invention is to provide an improved direct-acting air
or gas pump or compressor, and especially to provide an efficient duplex air pump
or compressor of this class...
In crank and fly wheel air pumps and compressors, the proper movement of the
plunger throughout the stroke is secured by the fly wheel, the excess of power at
the beginning of the stroke, and until the air on the force side of the plunger is
compressed, to delivery pressure, being stored up in the fly wheel, and utilized
during the latter part of the stroke.
In a direct-acting air pump or compressor, however, in which no such equalizing
device is used, but the piston and plunger are free to move in accordance with the
pressures on opposite sides, the plunger may jump through the first part of the
stroke until the pressure on the force side of the plunger is raised to the delivery
pressure, this jump increasing with the ratio of the delivery pressure to the
suction pressure, and frequently amounting to more than half a stroke, and, under
some conditions, to nearly a full stroke.
In all direct-acting air pumps and compressors, difficulty has been found in
securing the uniformity of action desirable to prevent slamming of the valves and
shock to the moving parts of the pump, and a dash-pot or an additional water
pump, actuated by the steam piston of the air pump or compressor, is frequently
used for this purpose.
In duplex pumps, that is, pumps in which the steam valves on one side are
operated from the other side of the engine, the two pistons and plungers being
timed differently,, each side of the pump opens the steam valves on the opposite
side in the latter part of the stroke, and usually commences to open them only a
little later than half stroke. Consequently if the piston and plunger jump any
considerable portion of the stroke, the steam valves on the opposite side are opened
too early, especially as the blow from the quick motion of the jumping piston will
throw the valve, and open it in advance of the 'movement of the piston and valve
rod, and the piston and plunger on the opposite side then jump in turn, and again
shift the valves on the first mentioned side, before that side has time to complete.
its stroke, the result being that the pistons and plungers take short strokes' at the"

page_text: centres of the cylinders, and if the ratios of the delivery pressure to the pressure
in the cylinder be quite high, this stroke may be so short as to prevent the pump
doing any effective work. This result is aided also by the air compressed in the
clearance space, which increases the pressure behind the plunger, and aids in
causing the jump referred to, and moreover, prevents any suction on a very short
stroke, as no suction will take place behind the plunger until the air compressed
in the clearance space on the previous forward movement of the plunger, has
expended to suction pressure.
This failure of suction in air pumps during the first part of the stroke, due to
the clearance space, is well known, and, to avoid this difficulty, wet air pumps have
been used, and various devices employed in dry air pumps for relieving the pressure
in the clearance space, when the plunger is reversed. This difficulty exists more
largely in direct-acting pumps, because a comparatively large clearance space is
required while only a small clearance is necessary in crank and fly
wheel pumps, because the movement of the piston is limited, and
concussion prevented by the crank.--In crank and fly wheel dry air
pumps, also, it has been suggested to connect the two opposite ends of the cylinder
at the end of each stroke, so as to allow the compressed air in the clearance space
to expand into the opposite end of the cylinder, thus securing suction practically
throughout the stroke, a valve construction being used which will prevent the
delivery pressure from being transmitted to the force side of the plunger.
All objectionable irregularity of action in direct-acting air pumps or compressors
is practically avoided by making the plunger load substantially uniform through-
out the stroke, and thus providing an efficient duplex air-pump or compressor of
this class. This result may be secured by admitting pressure on the force side
of the plunger from any suitable source, at or near the commencement of each
compression stroke, that is, so that the plunger shall be under substantially the
delivery load at the commencement of the stroke, or so early in the stroke as
to prevent any substantial jump of the plunger. It is preferred, however, to admit
the pressure, to secure this uniformity of load, while the plunger is at rest, before
reversing, and, by connecting the delivery and pump cylinder on the force side
of the plunger for this purpose, and it is also preferred to connect the two opposite
ends of the cylinder at the end of each stroke, before communication is thus
opened between the delivery and cylinder. In attaining this latter result, an
equalizing port is employed, which is controlled so as to secure communication
between the opposite ends of the cylinder at the end of each stroke, thus permitting
the expansion of the air in the clearance space to the force side of the plunger, so as
to lessen the pressure behind the plunger, and increase the pressure in front of
the plunger at the beginning of the next stroke, these features co-acting in tending
to equalize the plunger load throughout the stroke. It will be seen that an advan
tage is also secured, in that the plunger load is not only increased
at the beginning of the stroke, and SO aids in avoiding the jump
previously referred to, and in securing the full stroke of the plunger,
but suction is also thus secured at the beginning of the stroke,
that, even if the stroke of the plunger should be reduced somewhat, air will still
be received at the suction end, and the work done.
SO
The opening and closing of the equalizing port, and the control of the connection
between the cylinder ends and delivery to obtain the above mentioned results, may
be secured by valve constructions of different form, but it is preferred to use a
construction in which communication between the delivery and pump cylinder
on the force side of the plunger, is secured at or near the commencement of the
stroke through the regular admission and emission ports at the ends of the cylinder,
and the equalizing port is controlled by the same valve or valves that control the
delivery, and such a construction forms a part of the invention, and may
employed in single air pumps or compressors, as well as in duplex constructions.
It is evident that the invention may be embodied in constructions of widely
different form, but, for the purpose of illustrating all the features of the invention,
be

page_text: there is shown in the accompanying drawings, forming a part of this specification,
a duplex direct-acting air-pump or compressor which will be found a convenient
and efficient embodiment of the invention, and a full description of the same will
now be given, and the features forming the invention specifically pointed out in
the claims:
In the drawings:-
Fig. 1 is a side elevation of the pump, with the pump cylinder and valve on one
side shown in section.
Fig. 2 is a plan view of the same.
Referring to said drawings, A, B are the two steam cylinders; C, D the corres-
ponding pump cylinders, shown as jacketted for water circulation, as usual; a, b
the corresponding piston rods; and c, d the corresponding plungers. The con-
struction of the steam end of the cylinders and valve movement is substantially
the same as shown and described, in many prior patents, and now well known in
connection with the Worthington Duplex Pumping Engine, so that no further
description of these parts is required, it being understood that the valves on one
side of the engine are operated from the opposite side through levers e, f, actuated
by the respective piston rods a, b, and connected to the valves by the usual links.
It will be understood, however, that any other suitable construction may be used for
the steam end of the engine, that shown being selected only as forming a simple
and efficient construction well adapted for use in connection with the invention.
both
At the pump end, E is the suction and F the force main, and G a joint suction
and delivery chamber. This chamber G connects with the suction E through a
cove g on each side of the engine, and with the opposite ends of the cylinders C, D),
through admission and emission ports h, and communication through these ports is
controlled on the opposite sides by rotary valves i, k, these valves being formed
with central ports 1, 2, respectively, which connect the ports h at the opposite ends
of the cylinder, where the plunger has reached the end of its stroke, and thus form
the equalizing ports referred to above. These valves i, k, are operated from the
opposite side of the pump by means of the levers e, f, and links 10, 11, on the
opposite sides, and crank arms 12, 13, carried by the respective valve stems.
The positions of the operating parts on sides of the pump are
shown in full and dotted lines in Fig. 1, the position selected for
illustration being that in which the plunger c is at half stroke, and
the plunger d at the end of its stroke. In this position, the valve i on
the c plunger side of the pump is in such a position as to connect the suction cove g
with the suction side of the cylinder, and the delivery with the force side, while
the valve on the d plunger side of the pump has closed both the suction and
delivery, and opened communication through the port 2 between the opposite ends
of the cylinder D, so that the compressed air in the clearance space has expanded
into the opposite end of the cylinder, so as to increase the pressure on the force
side of the plunger at the beginning of the next stroke. The piston rod a is just
about to commence to shift the valves of the steam cylinder B, and the plunger d
is just about to commence its stroke in the same direction as plunger c.
As the plunger c continues its stroke, the valve k is shifted to the left in Fig. 1,
so as to open communication between the suction cove 9 and the cylinder D on the
suction side of the plunger, and it will be seen that at the same time it opens com-
munication between the delivery chamber G and the cylinder D on the force side
of the plunger, so that the delivery pressure is at once admitted on the opposite
side of the plunger, and the full final load upon the plunger secured at the com-
mencement of the next stroke, thus ensuring a uniform action, and preventing the
jump of the plunger. As the plunger c reaches the end of its stroke, the plunger d
on the opposite side of the engine reaches the middle of its stroke, and then com-
mences to shift the valve i, so as to close the suction and delivery on that side, and
to open communication between the opposite ends of the cylinder C through the
equalizing port 1, and then to close the equalizing port and open the delivery to
the opposite end of the cylinder, while the plunger c is at rest, and thus the opera-
tion is continued.

page_text: .The. constructiontshown in which a single valve on each side is employed, and
communication between the delivery and force side of the plunger at the commence-
ment of the stroke is made through the regular admission and emission ports,.is
very simple and efficient, and in itself forms a part of the invention, but it will
be understood that the invention, broadly considered, may be carried out by other
constructions.
J
It will be understood that the term duplex pump" used herein is not to be
construed as limited to, a construction in which there are only two pistons and
plungers, but that it is used in its commercial sense; to include pumps having
two or more steam cylinders with their pistons and plungers, in which the steam
valves on each cylinder are operated from the piston of one of the other cylinders,
the pistons and plungers of the different cylinders being timed differently.
Having now particularly described and ascertained the nature of the said inven-
tion and in what manner the same is to be performed, as communicated to me
from abroad; I declare that what I claim is: -
1. A duplex direct-acting air or gas pump provided with means for admitting
fluid to the cylinders in front of the plungers at or near the commencement of each
compression stroke from the delivery, or from a source of pressure substantially
equal to that of the delivery, whereby substantially the delivery load upon the
plunger is secured during the first part of the stroke, substantially as described.
2. A duplex direct-acting air or gas pump provided with means for securing
communication between the opposite ends of the respective cylinders at the end
of each stroke, and for admitting fluid to the cylinders from the delivery or other
source, to increase the pressure in front of the plungers at or near the commence-
ment of each compression stroke, substantially as described.
3. The combination with the cylinders and plungers of a duplex direct-acting
air or gas pump, of delivery valves constructed and arranged to secure communica-
tion between the delivery and the respective cylinders on the force side of the
plungers, at or near the commencement of each compression stroke and actuating
connections between said.valves and moving parts of the opposite side of the
pump, substantially as described.
4. The combination with the cylinders and plungers, of a duplex direct-acting
air or gas pump, of valves controlling the suction and delivery, and constructed
and arranged to secure communication between the delivery and cylinders in front
of the plungers, at or near the conimencement of each compression stroke, an
equalizing port on each side of the pump controlled by said valves, and connecting
the opposite ends of the cylinders at the end of each stroke, and means for actuating
the valves on each side of the pump from the opposite side, substantially as
described.
5. The combination with the cylinder and plunger of a direct-acting, air or gas
pump, of valve mechanism controlling the suction and delivery, an equalizing port
controlled by said valve mechanism, and actuating connections between said valve
mechanism and a moving part of the pump, whereby communication between the
delivery and cylinder in front of the plunger is closed, and the equalizing port
opened, by said valve mechanism, at the end of each stroke, and the equalizing
port closed, and communication between the delivery and cylinder on the force
side of the plunger secured, at or near the commencement of the next compression
stroke, substantially as described.
'
6. The combination with duplex pump cylinders C, D,, having ports h, of
oscillating valves i, k, controlling said ports, and connections between said valves
and the opposite sides of the pump, for shifting said valves, to open the delivery
on the force side of the plunger for the next stroke, before the stroke is commenced,
substantially as described..
1
i.
7. The combination with duplex pump cylinders C, D, having ports h, of
oscillating valves,,, k, controlling said ports, and having equalizing ports 1, 2,
and constructed to connect ports through the equalizing ports, when the

page_text: delivery is closed, and connections between said valves and the opposite sides of
the pump, whereby said valves are actuated, substantially as described.
8. The combination with pump cylinder C, having ports h, of oscillating valve i
provided with equalizing port 1, and constructed to connect ports h, through the
equalizing port 1, when the delivery is closed, and open the delivery to one end
of the cylinder, when the equalizing port is closed, and at or near the commence-
ment of the compression stroke, and of actuating connections between said valve
and a moving part of the pump, substantially as described.
Dated this 14th day of December 1897.
NEWTON & SON,
Agents for the Applicant.