Year: 1887

page_text: 1, HERBERT JOHN ALLISON, of 52 Chancery Lane, London, in the county of
Middlesex, 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 :—
My invention relates more especially to gas compressors for refrigerating machines
which use a cooling, sealing and lubricating liquid, forming what is known also as a
liquid piston, and may be adapted to both vertical and horizontal compressors, used in
such machines, and also to use in connection with gas compressors for other than
refrigerating purposes.
In some vertical gas compressing cylinders heretofore constructed, the discharge
valve has been made to lift up into a dome or valve chamber located above the com-
pressor cylinder, and into which dome or chamber the compressed gas is discharged
by the lifting of this valve during the upward or compression stroke of the compressor
piston. The gas or oil thus discharged into the dome or valve chamber of the com-
pressor is conducted therefrom by a discharge pipe communicating therewith, and
leading to what is termed an oil separating tank. The discharge valve in such
compressors, which is preferably cup-shaped, made of metal and of necessity very
large, is also very heavy. If the height to which this valve may be raised or lifted in
the dome of the compressor is not limited by some mechanical means, the force
exerted upon it by the compressed gas entering the dome, being variable, will at times
raise the valve much higher than is really necessary to allow a free passage of the
compressed gas and oil. Besides this, the weight of the valve would cause it to
descend with considerable force and oftentimes before the end of the discharge period,
in which case it would strike the valve seat at a time when such seat was not flooded
by or submerged in oil, and thus an injury to either the valve or the valve seat would
inevitably ensue. In some gas compressors for refrigerating machines, the discharge
valve has been made to work in ways or guides, and the lift of the valve has been

page_text: limited by projections or stops on such guides; and, in some instances, the projections
for limiting the upward movement of the valve have been made to extend all around
the dome or valve chamber. It was found, however, that when these projections or
stops were located low enough to form a sufficiently small passage for the compressed
gas and oil, as that its flow into the valve chamber or dome would be retarded to the
extent requisite to cause it to exert the necessary pressure upon the valve to hold it
against such projections or stops and keep it from rescating during the discharge
period, the upper edges of the discharge valve cup soon became burred by being
constantly knocked against the stops. In consequence of this continual hammering
some portions of the valve would become larger in diameter, and it would eventually
refuse to rescat after being lifted by the discharged gas; and not only so, the valve
would sometimes break, thus causing delay and annoyance and not infrequently serious
losses to the owner of the machine who depended upon its continuous and perfect
working. Aside from this, the great and disagreeable noise which in such construc-
tion was occasioned when the machine was running at a high speed, say 50 or 60
revolutions per minute, was also a serious objection, and moreover, there was danger
of breaking the valve or guide stops by running the machine to its otherwise full
capacity, and it was, therefore, necessary in order to insure safety, that the machine
should be run at a moderate speed, which, of course, lessened its daily performance.
To avoid these objections and to prevent the delays and losses already mentioned,
as well as to increase the working capacity of the machine, is the object of my
invention, which consists in providing a buffer to receive the valve when lifted or
forced upward, without burring or breaking it; and, in addition thereto, in providing
a cushion which will render noiseless the movement of the valve against the buffer.
In the drawings, similar letters of reference represent corresponding parts.
Figure 1, is a central vertical section of a single acting gas compressor and dome
or valve chamber such as is used in some refrigerating machines which circulate a
cooling, sealing and lubricating liquid, and showing also a buffer secured within the
dome above the discharge valve which is provided with a recess or depression corre-
sponding to the head of the buffer.
Figure 2, is a central vertical section through the dome, discharge valve, diaphragm
plate and upper part of the compressor cylinder on a larger scale. In this figure the
buffer head is shown as corresponding to the valve cup, but the recess in the bottom
plate is omitted, the outlets in the upwardly projecting walls forming the valve cup
being located sufficiently high to cause the valve to retain a portion of the oil which
forms a cushion for the buffer.
Figure 3, is a like view, but shows the buffer as secured within the dome, and also
a recess in the bottom plate of the discharge valve. This figure also shows the under
side of the buffer head concave, and shows the edges of the head beveled and corre-
sponding to the beveled edges of the recess in the bottom plate of the valve.
A, represents the dome or discharge valve clamber, B the buffer, the underside of
which is preferably concave, while C represents the diaphragm plate with the valve
seaf 6, and E the outlet from the dome for the gas and oil. From this outlet the gas
and oil may pass into an oil separating tank, not shown, which, in refrigerating
machines, is generally interposed between the compressor and a gas condenser, the
latter not appearing in the drawings. In this tank to which the gas and oil flow from
the dome or valve chamber, the oil is separated from the hot, compressed gas. In all
the figures, M represents the cup-shaped discharge valve; and in figures 1 and 3,
m the projecting walls surrounding a receptacle for oil, which I sometimes make
within the base or bottom plate of the discharge valve, and which is preferably but
slightly larger than the head of the buffer B, but corresponding to it in shape as near
as may be, and into which oil receptacle the head of the buffer enters when the
discharge valve is lifted. In each figure, m² m² represent openings in the upwardly
projecting walls forming the cup of the discharge valve for alternately admitting oil
to, and discharging it from the cup of the valve M. In Figure 1, F represents the
compressor piston the piston valve, and the piston rod, G the suction nozzle or
gas inlet, the suction valve, and H the oil inlet..

page_text: The piston is actuated in the usual way and when it moves upward, a partai
vacuum is created below it, and as the suction valve g lifts, the gas fills the compressor.
Upon the downward stroke of the piston, a partial vacuum is created above it, the
piston valve lifts, and the suction valve closes and the gas passes through the
openings in the piston between the ribs d, d to the upper or compression chamber of
the compressor. During this period a certain quantity of oil under a pressure above
the pressure of the gas entering the compressor, is injected into the compressor
through the oil inlet H, either by means of a pump or other device. The piston F, near
the end of its downward stroke, dips into the oil in the bottom of the compressor, and a
quantity of oil equal to the quantity injected during the downward stroke of the
piston also passes through the openings in the piston.
Upon the return or upward stroke of the piston F, the gas contained in the
compression chamber of the compressor will be compressed to a pressure a little above
the pressure obtaining in the dome or discharge valve chamber A, when the discharge
valve M will lift and be forced against the buffer B, the head of which enters the oil
in the valve cup as shown in Figure 2, and when the valve M has the recess formed
by the walls m shown in Figures 1 and 3, the head of the buffer enters such recess by
also displacing the oil contained therein. The rapid passage of the compressed gas
through the aperture in the diaphragm plate will prevent the valve M from descending
until the moment when the oil which is laying above the piston is being forced through
the valve passage, and the valve will fall upon the oil which floods the lower portion
of the dome A, thus submerging the valve seat, and consequently the seating of the
valve will be noiseless. The oil now contained in the dome flows through the
openings m into the valve and fills its cup up to the lower edge of such openings,
and if the recess formed by the walls be present in the bottom plate of the valve M,
this recess will also be filled with oil. When the valve M is again lifted towards the
buffer B, the head of the buffer will be met by the oil contained in the valve cup which
it must displace before the valve can strike it, and if a recess be formed in the bottom
plate of the valve the buffer head must also displace the oil contained therein. In
either case the valve will be so cushioned by the oil as that the seating thereof will
be noiseless.
By constructing the discharge valve so that it will receive and retain a portion of
the oil admitted by it to the dome or chamber, such oil will always be present when
the machine is in operation, and thus a cushion will be presented to the buffer head
before the valve strikes against it, and by means of such cushion I am not only
enabled to avoid the noise occasioned by the use of large discharge valves constructed
as heretofore, but all liability of breaking the parts is obviated, and the machine can
consequently perform a greater amount of work within a given time because of the
fact that it can be run at a much higher rate of speed.
My invention may be applied to single or double acting compressors using a liquid
base and the oil may be injected into the lower or upper chamber of the compressor
and either during or after the suction stroke of the piston or during or before the com-
pression stroke. It may also be applied to horizontal compressors provided the valves
of such compression cylinders lift vertically or at right angles to the center line of
such compressors. I may employ differently shaped buffers, valves and domes from
those described, but in practice I prefer to use metallic cup-shaped valves, bell-shaped
buffers and bell-shaped domes.
The lift of the valve may be made adjustable, but having determined the proper lift
of valves of every size in compressors using a cooling, sealing and lubricating liquid,
I prefer to have the buffer stationary and thus prevent the use of unnecessary or
moving parts in the dome.
Having now particularly described and ascertained the nature of my said invention
and in what manner the same is to be performed, I declare that what I claim is :-
First. In a gas compressor having a dome or chamber, the combination of a buffer
secured in such dome or chamber with a discharge valve adapted to move toward the
said buffer, such valve having a recess or depression therein corresponding sub-

page_text: stantially to the buffer head and adapted to receive such buffer head when the valve
moves up to the same, substantially as described.
Second. In a gas compressor having a dome or valve chamber, the combination of a
buffer located within such dome or chamber, with a discharge valve adapted to hold
and retain a portion of the liquid admitted by it to the chamber, and to present the
retained liquid to the head of the buffer, whereby the valve is prevented from coming
in contact with the buffer head until it has displaced the liquid retained by the valve,
substantially as and for the purpose set forth.
Third. In a gas compressor using a cooling, sealing and lubricating liquid, the
combination of a buffer secured within the discharge valve chamber with a cup-shaped
discharge valve having therein an oil receptacle corresponding substantially to the
shape of the buffer head, and adapted to hold a liquid whereby a cushion for the buffer
may be formed of the liquid contained in such receptacle or recess, which is thus made
to neutralize or render noiseless the concussion occasioned by the forcing of the valve
up to the buffer head, substantially as described.
ALLISON BROS.,
Agents for the Applicant.