Improvements in Rotary Pumps.
Year: 1898

page_text: Date of Application, 10th May, 1898-Accepted, 10th Sept., 1898
[Communicated from abroad by HYGIENIC REFRIGERATION COMPANY, a corporation
organized under the Laws of the State of New Jersey, and having its place
of business at 11, Broadway, New York, United States of America.]
Improvements in Rotary Pumps.
I, HENRY HARRIS LAKE, of the Firm of Haseltine, Lake & Co., Patent Agents,
45, Southampton Buildings, in the County of Middlesex, 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 present invention relates to a rotary pump of that class in which a gang
of plungers are caused to reciprocate in suitable chambers or cylinders by the
relative eccentricity of a driving and a stationary member, and is embodied in a
novel construction and arrangement whereby great efficiency is obtained in a
machine of small compass, the construction and arrangement of which is such that
the machine can be inexpensively constructed.
The pump embodying the invention is mainly intended for use as a gas
compressor in refrigerating systems, although it is equally well adapted for other
purposes, such for example as compressing air for compressed air motors, etc.
The machine embodying the invention comprises a frame or casing substantially
cylindrical in shape and having a series of radial plunger chambers surrounding
a central bore or opening which is arranged to be substantially gas tight and
constitutes one of the gas chambers of the pump. Each plunger chamber com-
municates also with an annular space formed in the said casing which constitutes
the other gas chamber and is shown as provided with outlet openings adapted
to communicate with the receiver for the compressed fluid, the inner chamber in
this instance being the gas inlet chamber. Each of the radial plunger chambers
contains a plunger shown as adapted to cooperate with an eccentric which is
mounted on a shaft coaxial with the cylindrical chamber, so that in the rotation
of the said shaft the plungers are reciprocated in their respective chambers, each
plunger being provided with a valve which is adapted to open as the plunger
makes its backward stroke with relation to its chamber, and to close as the
plunger makes its forward or working stroke so that the gas in the interior of the
casing flows into the several plunger chambers as the respective plungers
move backward, and is then compressed and forced into the annular outlet chamber
aforesaid during the forward working stroke of the said plungers, and retained
by a suitable valve arranged between the plunger chamber and gas chamber.
To reduce the friction, the eccentric is surrounded by a loose or floating ring,
between which and the eccentric are interposed a number of rollers or similar
anti-friction devices, and the plungers are connected with said ring, each plunger
having a shoe connected therewith adapted to be held against the surface of the
ring by means of shoulders extending over the same, so that while the said shoes
are capable of moving along the surface of the said ring, they are held against
the said surface as it approaches and recedes from the mouths of the respective
chambers in the rotation of the shaft which carries the eccentric.

page_text: With this construction the ring will not have to rotate with the eccentric while
being revolved thereby about the axis of the shaft, and the travel of the shoes
along the surface of the ring will be only sufficient to compensate for the eccen-
tricity, there being therefore a comparatively small amount of sliding friction
developed in these parts in the operation of the machine which consequently is
capable of operating at a high speed and compressing to a high degree of pressure.
The invention further relates to certain novel details of construction and arrange-
ment, which will be hereinafter more fully described.
Fig. 1 is a side elevation partly in section of a pump embodying the invention;
and Fig. 2 is a longitudinal vertical section of the same.
The casing A may be formed, as shown, of a single casting having a standard A³
formed integral therewith, and containing a central opening or inlet chamber a
shown as provided with an inlet opening a² from the supply of gas or fluid which
is. to be compressed. The casting is provided at one side with an opening into
the central chamber a to provide for the introduction of the eccentric and co-
operative part, which will be hereinafter described, said opening being covered
by a removable bearing plate A³ held in place by a bonnet A bolted to the main
casting of the casing A. Surrounding the said central chamber a near the outer
periphery of the casing is an annular chamber b, constituting the outlet chamber
and having one or more outlet pipes 62 adapted to communicate with the receiver
for the compressed gas.
Extending from the chamber a to the chamber b are the plunger chambers or
cylinders c extending radially, or approximately so, through the casing A, it being
practicable, as shown, to bore the said chambers through from the outer wall of
the casing, each chamber then being provided with a bushing carefully finished
to cooperate with the plunger d which is movable therein, as will be described.
Each of the chambers c, therefore, affords a communicating passage from the
chamber a to the chamber 6 the gas passing through an opening in the plunger
controlled by a valve d² during the backward movement of said plunger with
relation to its chamber and then during the forward or working stroke thereof,
being forced into the chamber 6 through a valve which closes when the plunger
begins its backward stroke.
The valve is shown as cooperating with an annular valve seat c formed in
the tubular bushing, and just above the said valve seat an annular space c³
is formed, said annular space communicating with the chamber 6 by means of
one or more openings through which the gas is forced into said chamber, it being
obvious that the gas can pass through said chamber around the plunger chambers
by means of the annular space c5 aforesaid.
The bushing is shown as provided with a shoulder 20 cooperating with a
corresponding shoulder in the bore in the main casing; and the said bushing is
kept in place by means of a bonnet c which is secured to the casing by means of
bolts or cap screws c³.
This construction is very simple and has the advantage, moreover, of rendering
all parts of the machine easily accessible, it being obvious that if it is desired to
get at the interior of any of the chambers it is necessary only to remove the
bonnet when the valve and bushing c may also be removed, since the bonnet
constitutes a fastening device whereby all the parts are retained after being
assembled.
To properly pack the plunger chamber and prevent the gas from escaping
around the bonnet, the bore in the casing is shown as slightly larger at its outer
end than along the body of the same, while the upper portion of the bushing is
cut away to form an annular recess at the line of junction between the bore and
bushing in which is laid a ring of suitable material adapted to be engaged on
top by an annular tongue along the face of the bonnet thus constituting a
practically gas tight joint.
The plungers are shown as consisting of substantially cylindrical shells
having at their inner ends thimbles 3 adapted to be screwed into the ends

page_text: thereof and provided with flanges overlying a packing ring supported on a
shoulder at the outside of the plunger. Each of the said thimbles is provided
with a valve seat d5 with which cooperates the valve above named, the said
valve being shown as provided with a spring whereby it is normally held seated.
To produce the reciprocating movement of said plungers they are adapted to
cooperate with an eccentric e on a driving shaft e which is mounted in bearings
concentric with the axis of the cylinder, so that in the rotation of said shaft the
periphery of the eccentric approaches and recedes from the wall of the chamber a.
To connect the plungers d with the periphery of the eccentric which is con-
trolled by the driving shaft e each plunger is provided with a shoe de pivotally
connected to said plunger, the said shoe being shown as provided with a lug
through which extends a cross-piece in the interior of the plunger.
In order to reduce the friction, the shoes instead of being connected or
engaged directly with the eccentric e, which would necessitate a continuous
sliding friction between the surface of said eccentric and the surface of the shoes
at whatever speed the shaft was operated, are connected or engaged with a float-
ing ring 9 surrounding the eccentric &, which may thus carry said ring with a
revolving movement around the shaft, without causing the ring to have the
rotary movement of the eccentric; and between the said ring and the eccentric
are interposed anti-friction devices or rollers f, so that the eccentric can turn
within the ring with but slight friction, while the ring by reason of its non-
rotation has but slight surface movement with relation to the shoes de
To properly cooperate with the shoes the said ring is shown as provided along
its periphery with under-cut shoulders g² overlying and engaging a portion of
the shoes do, so that the shoes while free to travel along the periphery of the ring
are constantly held against the same, whereby each plunger in turn will be forced
forward into its cylinder and drawn backward therein as the periphery of the ring
approaches and recedes from that part of the wall of the inner chamber occupied
thereby. The said ring is shown as comprising two sections, each of which has
one of the under-cut shoulders g² formed therein so that the two sections can be
separated for the insertion of the shoes and then drawn together as shown and
secured by the bolts so that the shoes are retained in position by said shoulders,
the ring then practically having an under-cut groove along its periphery adapted
to retain the shoes.
In the operation of the machine it will be seen that the ring, being frictionally
engaged by the shoes when moving the plungers forward against the pressure of
the gas, will not partake of the rotary movement of the eccentric; while the
several shoes will simply travel along the periphery of the ring to a slight extent
to compensate for the eccentricity as the ring revolves or moves around the shaft,
the friction therefore being but slight and nearly all taken up by the anti-friction
devices. It is possible, however, for the ring to rotate or turn about its own
central axis so that it may remain with the plunger which at any moment has
the greatest pressure back of it. without sliding movement thereon, the slight
compensating sliding movement thus being mainly between the ring and the
shoes of the plungers against which the pressure is least.
The shaft e is shown as extending into the chamber a through a stuffing box e
and is mounted on roller bearings eat each side of the said casing, the opposite
end of the shaft extending into a chamber in the bonnet A3 which is provided
with an oil cup as shown.
The eccentric is keyed on the shaft and rests against an annular shoulder on
said shaft at the end adjacent to the closed chamber e. The gas passing through
the chamber a into the chamber e5 exerts a pressure on the end of the shaft e
tending to hold the eccentric out of engagement with the side A³ of the said
chamber. At the opposite side of the eccentric there is a thrust bearing having
anti-friction balls e to take up the friction, it being obvious that substantially all
the end thrust will be taken up at this point.

page_text: The construction herein before described of the casing is such that it is a com-
paratively simple matter to form a water jacket which is obtained as shown by
forming an annular groove h in the outer wall of the casing at each side thereof
the said grooves being connected across between the plunger cylinders by means
of transverse openings 2; while the grooves and chambers are closed to form a
receiving chamber for cold water by means of the annular plates h³ extending
along and covering the said grooves in the walls of the cylindrical casing and
shown as secured in position by means of bolts h and nuts h³, the said bolts
extending across through the transverse openings 2 as best shown in Fig. 2.
The inlet and outlet to this space may be located in any convenient position
and are not herein shown, since it is obviously necessary that the water should
be supplied and allowed to flow out continually or intermittently to carry off the
heat absorbed by it.
While in the foregoing description the chambers a and b have been referred
to respectively as the inlet and outlet chambers, it is not intended to limit the
invention to such specific arrangement since the functions of the chambers might
be reversed without departing from the invention, by making the necessary
modifications in the valves and so-forth.
Furthermore, it is not intended to limit the invention in other respects to the
specific construction and arrangement described, since such construction and
arrangement are easily susceptible to modification without departing from the
invention,
Having now particularly described and ascertained the nature of this inven-
tion and in what manner the same is to be performed, as communicated to me by
my foreign correspondents, I declare that what I claim is:-
1. A rotary pump of the kind described in which there are two gas chambers
one surrounding the other and a series of plungers in plunger chambers extending
from one of said chambers to the other, valves to control the flow of gas through
the plungers from one chamber to the other, an eccentric to operate the plungers,
a ring or float surrounding said eccentric and adapted to cooperate directly with
the plungers, and an anti-friction bearing for said ring.
2. The combination with a casing having an interior closed gas chamber, pro-
vided with an inlet for the gas to be compressed, of an annular gas chamber in
said casing surrounding said closed chamber and adapted to receive and deliver
gas after the compression thereof, a series of plunger chambers extending from
said annular gas chamber to said interior gas chamber, a plunger adapted, to
reciprocate in each plunger chamber, a shaft extending through the interior gas
chamber and having an eccentric mounted thereon, a ring or float surrounding
said eccentric, anti-friction devices or rollers between said eccentric and said ring,
a shoe connected with each plunger and having a portion to be retained in an
under-cut groove along the outer periphery of said float, a valve in each plunger
adapted to be open during the movement of said plunger towards said interior
gas chamber and to be closed during the movement of said plunger in the opposite
direction, and a valve interposed between each plunger chamber and the annular
gas chamber adapted to be open during the movement of the plunger towards the
same and to be closed during the movement of the plunger in the opposite
direction, substantially as described.
3. In a pump of the kind described the eccentric, the ring or float surrounding
the same and having an anti-friction bearing thereon, and the plunger shoes held
in under-cut guide grooves in the ring.
4. In a rotary pump of the kind described in Claim 1, the water jacket which
consists in the annular grooves and their covers and the transverse passages
between the plunger chambers.
5. In a rotary pump of the kind described in Claim 1, the bushings for the
plunger chambers having the valve seats and valves and the annular spaces com-
municating with the gas chamber, substantially as described.

page_text: 6. In a rotary pump of the kind described in Claim 1, the main shaft extending
into the closed gas chamber so as to be acted upon by pressure at its end, and the
anti-friction thrust bearing to sustain the end thrust caused by such pressure,
as shown.
HASELTINE, LAKE & Co.,
45, Southampton Buildings, London, W.C., Agents for the Applicant.