Year: 1888

page_text: Date of Application, 14th Feb., 1888
Specification Accepted, 13th Apr., 1888
I, OLIVER IMRAY of No. 28 Southampton Buildings, Chancery Lane in the County
of Middlesex, Fellow of the Institute of Patent Agents 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 improvements upon duplex rotary piston pumps or
blowers for force or exhaust purposes.
In pumps of this type the pump cylinder is cast with a vertical division wall
extending from top to bottom except as to an opening receiving the piston cylinders
thereby rendering it necessary to construct the two abutment valves in separate parts
independently mounted on their central shaft in order that they could be separately
introduced into the piston cylinder from opposite sides. thereof. In the present
invention the partition is of a special form and the abutment valves are made in one
piece and can be fitted into place from either end of the casing so as to cover both
compartments of the piston cylinder.
With this construction the fluids forced or drawn through the pump are liable to
be retained in the cut away portion of the abutinent valve and to produce a pocketing
which effects the concussive action of the piston; these objections it is the object of
the present invention to avoid.
Furthermore by the use of pumps of this form it is not possible to establish suction
and to sustain high pressures with air, water or fluids, whereas in the present invention
by a simple disposition of a valve or valves placed in the discharge pipe, I am enabled
to avoid the obiections stated.

page_text: I will describe the invention referring to the accompanying drawings.
Fig. 1 is a longitudinal section of a duplex rotary pump embodying my
improvements.
Fig. 2 is a front view of the rotary piston and abutment valve.
Fig. 3 is a transverse section of the piston and abutment valve.
Fig. 4 shews the piston engaged in the abutment valve.
Fig. 5 is a side view of the two abutment valves in one piece.
Fig. 6 is a front view of the casing and partition.
The shell or casing 1 is divided into two parallel chambers 2 and 3 by a vertical
partition 4 which is continued through the pipe 6, to the seat of the valve, or valves 40,
which are placed therein. Referring to Fig. 6, the partition 4, has an upper circular
opening 46, which receives the duplex cylinder, and a lower segmental opening +c,
separated from 4b by a ridge 4a, which fits the revolving abutments. The revolving
abutments 8, 9, are constructed in one piece in the form of a cylinder which has two
diametrically opposite recesses 10 and 11 constituting piston openings one on each
side of the partition 4, the middle part of the cylinder between them fits closely
against the partition so that there is no communication between the chambers 2 and 3.
The ends of the cylinder 8, 9 fit closely against the ends 14, of the case or shell. Two
openings 15 pass from end to end of the abutment cylinder and other openings 15*
stop at the partition 16, in the middle of the cylinder, which forms the inner wall of
the piston openings 10 and 11. These openings 10 and 11 on opposite sides of the
partition 4 with the partition itself and the ends 14 of the case from chambers for the
piston 18.
The piston cylinder 19, is made in two parts each carrying a piston 18. The ends
of the two parts are shouldered down the reduced parts entering the hole 46 in the
partition 4 in the middle of which they meet. The pistons 18, project from the piston
cylinder in diametrically opposite directions each piston having at each end a thin
wing 25.
When the piston is entering one of the openings 10 as seen in Fig. 3 there is
clearance 35, for outflow of the fluid that would otherwise be pocketted in 10 and as
the piston is passing through the opening as in Fig. 4, there is clearance space
enough to permit a considerable outflow, until the opening at 3 is sufficiently large,
whereupon the piston comes to bear on the last half of the surface of 10.
The
clearances described prevent blows or jars resulting from sudden changes of volume
within the pump.
In order to establish suction and sustain high pressures valve 40 are fitted in the
discharge pipe 6, either flap valves as shewn or other suitable valves, a separate valve
for each chamber of the piston cylinder. The object of the valve is to prevent back
flow from the discharge when the piston 18, is in the position shewn in Fig. 3 thus
leaving for a moment a passage open to the suction.
For preventing leakage past the abutment cylinder a water packing is arranged as
follows:-
Recesses 7 are formed upon the inner face of the casing separated by pads 7" parallel
to the axis of the abutment cylinder. Fluid enters these recesses slowly and forms a
packing which prevents the fluid from leaking round the abutment cylinder. The
ends of the abutment cylinder are packed in a similar manner by the fluid in the
chambers 15 revolving with the abutment cylinder in a direction opposite to the main
current in the pump. There are also grooved channels 50 formed in the ends of the
abutment cylinder for a like purpose. The efficiency of the fluid as packing results
from the circumstance that the abutment cylinder moves in a direction opposite to
that of the piston cylinder in which latter direction the main body of fluid is made to
move.
Having now particularly described and ascertained the nature of this inven-
tion and in what manner the same is to be performed, I declare that what
I claim is :-
:-
1. The construction of the abutment cylinder in one piece with opposite openings

page_text: for passage of the pistons and with interior chambers open at the ends and with
grooves for fluid packing substantially as described.
2. The arrangement of the openings in the abutment cylinder relatively to the
revolving pistons so that relief spaces are provided as the pistons enter the openings
and these spaces decrease as the pistons advance, substantially as described.
3. The combination of the casing having a lateral discharge pipe and valve the
central transverse partition extending to the valve seat, with the abutment cylinder,
and the piston cylinder co-operating therewith, substantially as described.
Datad this 14th day of Wohruary 1888
ABEL & IMRAY,
Agents for the Applicant.