US2232280A - Priming or charging arrangement for centrifugal pumps - Google Patents

Description

- Feb. 18, 1941. J. scvuTlY-IIERN l PRIMINGzOR VCIARGIYNGr ARRANGEMENT FOR CENTRIFUGAL PUMP`S Filed'July 22, 1938 2 Sheets-Sheet l El l Ill/11.1"

John Sourhve'm INVENTOR ATTORNEY Feb. 18,1941. J, SQUTHERN 2,232,280

PRIIING 0R CHARGINGYRRANG'EMENT FOR CENTRIFUGAL PUMPS v Filed July 22, 1958 7 .2 4 I, 2 m n m w if C.. .V l S 3 1o w 1 o flurry. l A .F

Patented Feb. 18, 1941 UNITED STATES PRIMING OR CHARGING ARRANGEMENT FOR CENTRIFUGAL PUMPS John Southern, London, England, assignor, to

Worthington Pump and Machinery Corporation', Harrison, N. J., a corporation of Delaware Application July In Great Britain 1 Claim.

This invention relates to priming or charging arrangements for centrifugal pumps and is particularly concerned with motor-driven pumpv units for marine and other work where the unit 'may be required to operate when submerged and under variable suction heads.

The invention will be described as applied to a vertical-shaft motor-driven self-priming pump unit of the general character described and illus' which priming pump is of 'the water-ring type f and is arranged for unloading by discharge of its sealing liquid and replacement of the discharged sealing liquid with air drawn from a supply within the bell-like enclosure.

With these and other objects in view, as mayf appear from the accompanying specification, the 26 invention consistsl of various features of construction and combination of parts, which will be rst described in connection with the accompanying drawings, showing priming or charging arrange'- ments for centrifugal pumps of the preferred form the embodying invention, and the. features forming the invention will be specicallypointed out in the claims. In the drawings: -Figure 1 is a sectional elevation of a verticalshaft centrifugal pump and combined priming pump arranged rfor motor drive and constructed in accordance with the invention.

Figure 2 is a sectional elevation of the priming pump taken on the line 2--2 of Figure 1.

Figure 3 is a `sectional elevation of the oat chamber, including the automatic valve for controlling the operation of the priming pump, taken on the line 3-3 of Figure 1.`

The invention will be described by way of example as applied to a vertical-shaft motor-driven pump unit such as may be employed in marine work for bilge pumping and other duties under conditions which may involve the complete or partial submersion or flooding of the unit. Re- 150 ferring to Figure 1 of the drawings the casing of ,the single-stage centrifugal pump indicated generally at I forms the base of the unit and the electric driving motor (not shown) is mounted above the pump and suitably coupled to the versa tical shaft 2. The motor is enclosed and the cas- 22, 1938, Serial No. 220,641

February 18, 1938 (Cl. 10S-113) ing is extended downwards as shown at 3 to form an air bell which, as described in British Patent specification No. 446,771, will entrap air and prevent water from entering the motor casing when the unit is submerged. This casing 3 constitutes 5 a part of the framework which supports the driving motor.

Mounted directly upon the shaft 2 between the i pump and the driving motor is the rotor 4 of the water-ring priming pump which is surrounded by 10 a casing supported upon rthe casing' I of the centriiugal pump and sealed about the pump sl. ift. The priming pump is arranged so that its rotor may be unloaded automatically when the centrifugal pump is fully primed as described in 15 British Patent' specification No. 470,208, but the construction of the pump is modified in certain respects as will now be described. y

The casing of the priming pump includes an outer wall 5 and an inner wall 6, the latter form- 20 ing the rotor chamber, and the two walls, enclose an annular chamber I which forms a make-up reservoir for the pump. Water or any other suitable liquid may be used as the working medium for the pump. The chamber 'I is completely en- 25 closed and is provided with a pair of upward extensions or limbs 8 and 9 which are curved inwardlyas may be seen by reference to Figure 1 and thus serve also to support a bearing I0 for the pump shaft 2. not annular in plan as will be evident from a. comparison of Figures 1 and 2 but form in effect a hollow arch and communicate at their upper ends-through the passages II and I2. It will be appreciated that these hollow arched members 35 8 and 9 constitute in effect an air bell above the make-up reservoir.

The control of the priming pump when loading and unloading is effected by means of a valve member I3 housed `in the casing of an enclosed 40 float chamber I4 which may conveniently .be arranged outside the bell or skirting 3 of the. 'motor enclosure. The oat chamber is mounted upon a branch I5 of thel main pump suction with which it communicates. A hollow float I'l is car- 45 ried by a pivotally mounted arm I8 arranged to actuate, through'a link I9, a pivoted lever arrangement indicated generally at 20 which is connected to the valve member I3. This lever arrangement is similar in all respects rto that described in British Patent specification No, 470,208 and is adapted to actuate the valve member I3 with a snap action when the float l 1 falls below a predetermined minimum level or risesvabove a predetermined maximum level: In this way the These upward extensions are 30l level in the float chamber.

valve member will always occupy either one or other of two end positions according to thewater The valve member comprises a pair of spaced piston elements 2I and 22 whichcontrol the various unloading ports as hereafter described, and is also provided with a mushroom type of valve element 23 which is adapted to vco-opera'te with a seating 24. This element, when closed, isolates the priming pump from the float chamber.

Referring now to Figure 2 of the drawings, the suction or inlet side of the priming pump communicates with a chamber 25 and thence by means of a pipe 26 with a port 21 openinginto the upper part of the bore of valve I3. A nonreturn valve which may conveniently comprise a spring-pressed ball'is preferably interposed in the pipe 26 to prevent liquid passing from the priming pump into the float chamber, although such valve is not shown in the drawings. Immediately below the port 21 is a port 28 which communicates through a pipe 29 with the upper part of the make-up reservoir formed by the arched extensions 1 and 8. This connection will be seen in Figure 2.

Towards the lower end of the bore of valve I3 is a port 30 communicating through a pipe 3l with a passage 32 and thence with the rotor chamber of the priming pump for the purpose of unloading the latter. Immediately below the port 30 is a port 33 communicating by means of pipe 34 with the lower part of the make-up reservoir. A further port 35 is connected through a pipe 36 and passage 31 with the inner wall of the rotor chamber and serves for the supply of makeup water to the rotor chamber.

The make-11p reservoir 1 has an outlet 38 controlled by a' non-return valve 39 which prevents any possibility of water entering the reservoir from outside.

The discharge side of the priming pump comthe float chamber filled with air. Under these conditions the make-up reservoir will be in communication withl the priming pump through the connecting pipe 34, ports 33 and 35, pipe 36 and passage 31, thus supplying the necessary liquid to form the water or sealing ring, the unloading port 30 being closed. The suction of the priming pump is in communication through the pipe 26' with the fioat chamber by way of the open valve 23 and the pump will therefore commence to evacuate the suction of the centrifugal pump.

The evacuated air is discharged by the priming pump into the upper part of the reservoir 1 and any access escapes through the non-return outlet valve 39. It will be notedv that the outlet 38 is within the skirting bell 3 and the air thus discharged will augment the supply of air within the bell should the unit be submerged. As soon as evacuation is complete and the pump is primed the water will rise in the iioat chamber and actua'te the valve I3 which by reason of the mechanism previously referred to will snap over into its lower end position. All communication between the priming pump and the float chamber is now cut oft by the valve 23 and at the same time the suction side is placed in communicationy with the upper end of the make-up reservoir through the port 28 and pipe 29. The downward movement of the valve I3 also affords a connection between the ports 30 and 33 while cutting off the port 35 with the result that the sealing liquid of the pump is discharged by centrifugal force through the passage 32 and returns by way of pipes 3l and 34 to the reservoir 1. It will be understood that in order to unload the pump in this way the sealing liquid discharged must be replaced by air or other gaseous medium. This is provided for by the opening of port 28 which allows the air entrapped in the upper part or bell of the reservoir 1 to pass into the pump suction.

The priming pump is now unloaded and its rotor l,

in the float chamber to fall and actuate the valve I3, upon which the priming pump will be automatically re-loaded.

The operations above will be carried out in the same way when the whole unit is submerged. The construction of the upper part of the makeup reservoir as an air bell into which the pump discharges ensures that there will always be a supply of air to unload the pump and any excess will be discharged into the main air bell or skirting surrounding the motor and thereby affords an additional safeguard against the flooding of the motor when the unit is submerged as this additional air will compensate for any loss by absorption or by other means. The provision of a nonreturn valve in this discharge prevents water from entering the make-up reservoir when, during submergence of the unit, the Water level rises in the bell above such discharge outlet.

Thus the invention provides for a self-priming pump unit and for the automatic unloading. of the priming pump under both submerged and unsubmerged conditions independently of external air supply connections with their attendant disadvantages. It will be noted that whenthe centrifugal pump is operating at full capacity the priming pump is always unloaded and conversely when the priming pump is loaded and operating the centrifugal pump will be operating under noload or very low load conditions. It follows from this that the driving motor need only be rated for the fullpump load and no allowance is necessary for the priming pump. This is an important consideration in large units as the power required by the priming pump mayh be quite considerable.

The feature of an enclosed sealing water reservoir for the priming pump prevents loss of water by evaporation both when standing and when running eithersubmerged or unsubmerged.

The invention also provides an arrangement of the priming pump and its control gear which is convenient and accessible. It is particularly to be noted that the automatic valve gear is located outside themain skirting of the motor thus greatly facilitating inspection and adjustment. The complete unit is simple in construction and has few working parts, the -Weight is low and the efliciency is high. y

It will be obvious that very many changes may be made in the form and arrangement of the various parts of the pump unit described above by way of example,

to said priming pump whereby upon removal of 1 and the invention is in no way confined to this particular construction. l

What is claimed is: In a centrifugal pumping unit, a centrifugal pump, driving means therefor, a bell-like enclosure about said driving means for preventing entry of water into 'the driving means when the f pump unit is submerged, a priming pump of the water-ring type connected to said centrifugal pump for priming it and unloaded by discharge of its sealing liquid, a container for air connected the sealing liquid from the primingpump the liquid will be replaced by air, said priming pump .having its discharge connected to saidbell-like enclosure whereby discharge from the priming pump will assist in reducing the water level in thebell-like enclosure when the pump unit is submerged, and means preventing back-now from vthe bell-like enclosure to the priming pump.

JOHN SOUTHERN.

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