Improvement in Compound Air Compressing or Pumping Engines.
Year: 1891

page_text: COMPLETE SPECIFICATION.
Improvement in Compound Air Compressing or Pumping Engines.
I, FRANK MOORE, residing at Braddock Avenue near Forbes Street Pittsburg,
in the County of Allegheny, and State of Pennsylvania, United States of America
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 compound pumping engines of the type which is set forth
in the Application of George Westinghouse Jr., filed in the United States
August 6, 1890, Serial No. 361,175, (English Application No. 19177/90) and its
object is to obviate liability of the high pressure piston to strike the cylinder-head
when working against a comparatively light pressure of the fluid under compression,
as well as to equalize, as nearly as may be, the traverse of the pistons under such
conditions.
To this end my invention, generally stated, consists in the combination of a
compound non-rotative direct-acting engine having the parts of its cylinders
controlled by a distribution-valve actuated primarily by the movement of the low-
pressure piston and a compound compressing-pump having its pistons connected to
and actuated by those of the engine.
The improvement claimed is hereinafter fully set forth.
In the Application of George Westinghouse Jr., as aforesaid (English
Application No. 1917700) a construction is illustrated in which the reversal of the
direction of movement of the pistons is effected by that of the high-pressure
piston, under which construction, when working against a comparatively low
pressure in the discharge-passage and storage-reservoir, the high-pressure piston
will, if the supply of motive fluid be not regulated with proper care, make a quick
stroke, and not having a sufficient resistance to oppose it will not be cushioned at
the end of its stroke, and will therefore strike the cylinder-head with greater or
less force, according to the pressure acting upon it. By reason of the com-
paratively small size of the induction-ports the steam admitted during this quick
traverse fails to fill the high-pressure cylinder at a pressure approximating that of
the supply, and consequently when exhausted into and expanded in the low-pressure
cylinder does not exert sufficient pressure therein to effect the degree of compression
desired in the pump-cylinder whose piston is connected to that of the low-pressure
piston. During this stroke of the high-pressure piston the low-pressure piston will
move much less rapidly, inasmuch as the pressure thereon is much less in excess of
the resistance against the connected pump-cylinder piston. Consequently while the
high-pressure piston makes a complete stroke the low-pressure piston moves through
only a portion of its full traverse. These conditions subsequently change, the high-
pressure piston moving more slowly and the low-pressure piston moving through a
longer traverse proportionately as the degree of compression effected by the pump
is increased.
The objections above indicated are obviated under my invention, in the operation

page_text: is
of which, when there is little or no pressure in the discharge-chamber and storage-
reservoir, the high-pressure piston of the engine will remain stationary after the
completion of its first stroke until the low-pressure piston has made a complete
stroke. The direction of movement of the pistons is then reversed by the low-
pressure piston and the air or gas in the final compression-cylinder of the pump
compressed into the discharge-chamber and storage-reservoir by the next succeeding
stroke of the high-pressure piston, after which the operation continues with a
uniform traverse of the respective pistons, the initial compression being effected to
a higher degree by reason of the complete stroke of the low-pressure piston.
In the accompanying drawings,
Figure 1 is a vertical central section through the cylinders and valves of a
compound pumping-engine embodying my invention;
Figure 2 a transverse section through the same, and
Figure 3 a plan or top view.
The compound pumping-engine, in which my invention is herein illustrated,
accords, in its general features of construction with that of the Application of
George Westinghouse Jr., aforesaid, (English Application No. 19177) and need
not, therefore, except so far as relates specifically to the application of my
improvement thereto, be fully and at length described.
As in said Application, I provide, in the practice of my invention, a compound
non-rotative direct acting engine, having a high-pressure cylinder 1 and a low-
pressure cylinder 2, whose pistons 3 and 4 are fixed upon piston rods 5 and 6,
passing through stuffing-boxes 7 and 8, and are controlled by a steam-actuated
distribution valve composed of a series of valve-pistons 14, 15, 16, 17 and 18, the
last four of which are fixed upon a common stem 19, and the piston 14 for con-
venience of construction, upon a separate stem bearing upon the piston 15. Steam
is supplied to the distribution-valve chamber 11 through a pipe connected to a
nozzle 12, and is finally exhausted from the low-pressure cylinder through a pipe
connected to a nozzle 14* on an exhaust chamber 13. The lower port 39 of the
low pressure cylinder 2 communicates with ports 42 in a bushing 40, which is also
provided with ports 41, communicating with the lower port 38 of the high-pressure
cylinder, and with ports 43 communicating with the exhaust chamber 13. The
cylinders 1 and 2 are provided with a flange 9 for connection to a fixed support, and
their lower heads are preferably cast integral with a frame or casing 10 for
connection to a compound compressing-pump, having an initial compression-
cylinder 44 and a final compression-cylinder 45, provided with suitable inlet, outlet,
and discharge valves 49, 51 and 54, discharge-port 55, and delivery-chamber 56,
and, fitted with pistons 46 and 47, are secured upon the piston-rods of the engine,
which pass through stuffing-boxes 58 and 59 on the pump-cylinders.
The admission and exhaust of motive fluid to and from the engine cylinders are
effected by the distribution-valve, which is controlled by an auxiliary slide valve, as
now to be described. The auxiliary slide valve 23 is, as in the Application
aforesaid, fitted to work in a chamber 21, which communicates by a constantly open
passage 22 with that portion of the valve chamber 11 which is continuously open to
the supply inlet 12. The valve 23 is also secured upon a stem 28, having, as in the
Application aforesaid, a collar 29 on its lower end and an upper shoulder 30; but
in lieu of being located above the high-pressure cylinder and actuated by the piston
thereof, as in the Application aforesaid, the chamber of the valve 23 is, under my
invention, fixed upon the head of the low-pressure-engine cylinder 2 and the valve
is actuated by a slotted plate 31 fixed upon the top of the piston 4 thereof, the
valve-stem 28 extending into and fitting freely within a central bore in the piston
rod 6.
In operation, assuming the high pressure piston 3 to be at the lower extremity of
its stroke, motive fluid is admitted from the valve chamber 11 through the ports 41
and 38 to the high pressure cylinder I on the lower side of its piston 3, effecting
the upward stroke of said piston and of the connected pump piston 47. These
pistons remain stationary at the termination of the upward stroke until the low

page_text: pressure piston 4 has made a complete downward stroke, (its initial downward
stroke being effected by the slight leakage of motive fluid past the high pressure
piston 3) when the slotted plate 31 of the low pressure piston 4 strikes the collar 29
of the stem of the auxiliary slide valve 23 and moves said valve downwardly, so as
to place the interior of the chamber 20 above the valve piston 14 in communication
with the exhaust chamber 13 through the ports 24 and 26 and the exhaust cavity
of the valve. The preponderance of motive fluid pressure in the valve chamber 11
on the valve piston 16, above that on the opposite valve piston 17, thereupon raises
the distribution valve, admitting motive fluid to the high pressure cylinder 1, above
its piston 3, through the ports 35 and 32, and effecting the succeeding downward
stroke of the pistons 3 and 47. The admission and exhaust of motive fluid from
the high pressure cylinder 1 to the low pressure cylinder 2 and from the low
pressure cylinder to the atmosphere or to a condenser are effected by the distribution
valve, as in the Application aforesaid, and not having special reference to my
present invention need not be herein again described.
It will be seen that, inasmuch as the auxiliary valve which controls the
movements of the main distribution valve is actuated by the low pressure piston, a
complete stroke of said piston is insured in proper relation to each stroke of the
high pressure piston, and the motive fluid is exhausted fully into the low pressure
cylinder, so as to enable the compressing effect of the piston of the latter to be
exerted to the desired degree, as well as to provide a proper cushion for the high
pressure piston at the terminals of its stroke.
The structural features of the engine herein set forth, in so far as they accord
substantially with those of the Application, Serial No. 361175 aforesaid, are not
claimed as of my invention, which is, moreover, described and shown in connection
with a further improvement, but is not claimed, in a separate Application filed by
me of even date herewith.
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 a compound pumping engine, the combination, substantially as set forth, of
a compound non-rotative direct-acting engine having a distribution valve controlling
the ports of both its cylinders and actuated primarily by the movement of the low
pressure piston, and a compound compressing pump having its pistons connected to
and actuated by those of the engine.
2. In a compound pumping engine, the combination, substantially as set forth, of
a high pressure cylinder, a low pressure cylinder, a distribution valve controlling
the ports of said cylinders, an auxiliary valve actuated by the piston of the low
pressure cylinder and controlling the movement of the distribution valve, and a
compound compressing pump having its pistons connected to and actuated by those
of the engine.
Dal
1
n 1
1001
ABEL & IMRAY,
Agents for the Applicant.