US3296973A - Centrifugal pumps - Google Patents

Description

mm m WW" H. was. @MEM @22mm Y GENTRIFUGAL PUMPS Filed March 16, 1965 i 25 SheetS-Shee l SUCTHOM PUMP M SWW y/lws f: fr v Jim W9 WW? M. P. s. PMSH HM CENTRIFUGAL PUMPS Sheets-Sheet 25 Filed March 16, 1965 United States Patent O 3,296,973 CENTRIFUGAL PUMPS Harold Philip Sidney Paish, Harold Lloyd Dagwell, and Peter John Anley, all of London, England, assignors to Henry Sykes Limited, London, England, a British company Filed Mar. 16, 1965, Ser. No. 440,153 Claims priority, application Great Britain, Mar. 20, 1964, 11,939/64 12 Claims. (Cl. 103-113) This invention relates to double-entry centrifugal pumps and, more specifically, to suction pumps wherein priming is effected by means of an auxiliary vacuum pump which runs continuously to remove air which is in or enters the pump or suction pipe.

In known suction pumps of this kind, the impeller shaft has a gland seal but unsatisfactory operation is occasioned by air leaking through the gland during and after priming; in operation, this causes unsatisfactory flow of liquid through the pump. Attempts to overcome this disadvantage have produced pumps provided with gland seals which are complicated and require maintenance and may limit the range of uses to which the pumps may be applied; these seals have, nevertheless, allowed some leakage of air, particularly after a period of use.

It is an object of the present invention to provide a centrifugal pump of improved and relatively simple construction and in which the above disadvantage is at least partly overcome.

According to the present invention there is provided a double-entry centrifugal pump of the kind wherein priming is effected by means of an auxiliary vacuum pump which runs continuously to remove air which is in or enters the pump or suction pipe, the centrifugal pump comprising a chamber for the inowing liquid, a pump casing formed with a central entry in each face and mounted at least partly within said chamber so that the entries open into a lower part of the interior of the chamber, a rotary impeller mounted within the casing on `a shaft which extends through a seal in a wall of the chamber and through one of the casing entries, and a separating chamber which extends upwardly from the inner side of the seal to receive air which has leaked past said seal and conduct said air to the upper part of said chamber for removal by the vacuum pump.

Preferably, said chamber is of substantial horizontal cross-section to promote separation of said air.

Preferably also, said upper part of the chamber constitutes a iloat chamber and a oat is arranged in said chamber to control the suction effect of said vacuum pump.

An embodiment of the invention will now be described, by way of example, with reference to the accompanying drawings in which:

FIG. 1 is a side elevational view, partly broken away and shown in section, illustrating a centrifugal suction pump embodying the invention;

FIG. 2 is a plan sectional view on the line II-II of FIG. l; and,

FIG. 3 is a sectional view in elevation taken on the line III- III of FIG. 1.

The centrifugal pump shown in the drawings functions as a suction pump to deliver water against a substantial head and is provided with a continuously-running auxiliary vacuum pump 9 for priming and for removal of air during operation of the centrifugal pump.

The pump according to the invention comprises a principal chamber 10 in the lower part of which a pump casing 11 is arranged. The pump casing 11 includes a volute 12 which houses a rotary impeller 13 mounted at the end of a shaft 14 which extends through an opening 3,296,973? Patented Jan. l0, 1967 ICC 14a in a side wall 15 of the chamber 10 and through a central inlet opening 16 in a side wall 17 of the pump casing 11. A gland seal 18 is provided for the shaft 14 where it passes through the chamber wall 15 at a lower part thereof. The seal 18 is provided with a rubber or like flexible and resilient mounting 19 which is secured around its periphery by a mount 20 exteriorly of the chamber wall 15.

A second central inlet opening 21 is arranged in the opposed wall 22 of the casing 11 and a boss 23 on the end of the impeller shaft extends into the second opening 21. Thus, an annular entry passage is provided at each side of the impeller 13, these inlets communicating with the lower part of the chamber 10, the interior which is, of course, continuously water-filled after priming and during loperation of the pump.

A partition wall 24 is spaced inwardly of the wall 15 of the chamber 10 to define a separating chamber 25 which extends upwardly from around the inner side of the seal 18. The seal 18 includes an inner flange 26, and a series of, say, four castellations 27 is formed on the opposed internal face of the wall 24. It will `be appreciated that the castellations are positioned around the opening 24a in the wall 24 through which the shaft 14 passes. The shaft 14 passes freely through the opening 24a but the clearance is suiiiciently small to minimize passage of fluid through the annular gap between the shaft 14 and the opening 24a.

The upper part of the chamber 10 acts as a water reservoir and as a tioat chamber, being formed with an inlet or suction opening 28 for inflow of water and at the top with a valve-controlled opening 29 which is spaced above the suction opening and is in communica tion, through pipe 30, with the auxiliary vacuum pump 9. The opening 29 is controlled by valve 31 operated by a float 32 which is pivotally mounted at 33.. The valve 31 opens communication to the vacuum pump when the float falls below a predetermined level due to the presence of excess air in the reservoir chamber. The float 32 also operates a valve 34 to control a vent 35 to atmosphere, the vent being opened when the water level rises above a predetermined level.

The shaft 14 is `driven by any suitable means, such as an internal combustion engine, and it will be appreciated that the resilience of the seal 18 accommodates the vibration which this type of prime-mover produces. The vacuum pump may also be driven from the rotating shaft 14.

The pump volute 12 extends tangentially upwardly at 36 to open into an upper sub-chamber 37, the opening being controlled by a flap valve 38. A delivery opening 39 for outow of water is arranged in the top of the subchamber 37.

l The pumping unit described above is self priming. At the start of an operation, the flap valve 38 and the vent valve 34 are closed and the vacuum pumpextracts air from the chamber 10, and thus extracts any air which leaks past the gland seal 18, to draw Water up the suction pipe to enter the opening 28. The water fills the chamber 10 to a level above the inlet openings 16, 21 in the pump casing and is sucked through these inlet openings to be pumped upwardly by the rotating impeller 13. The upowing Water opens the flap valve 38 `and passes out through the delivery opening 39.

In operation, particularly at high suction heads and impeller speeds the inlet opening 16 is in a low-pressure region and this, of course, increases the amount or the likelihood of air leakage past the gland seal 18. However, air which does leak past the seal enters the separating chamber 25 to pass upwardly for extraction by the vacuum pump, and thus does not affect operation of the pump. It is of importance that the cross-section of chamber 25 is sufficient to allow the upiiowing air to separate from the water and so promote satisfactory extraction by the vacuum pump; it will be appreciated that the air passes upwardly due to gravity only and thus the separating chamber 25 is of great significance.

At high impeller speeds the suction on the inner face of the resiliently mounted seal 18 tends to draw the seal into contact with the adjacent part of wall 24. However, the castellations 27 prevent direct contact and minimize the possibility of leakage air passing directly into the gap between the shaft f4 and the opening 24a in wall 24. The projecting castellations also act to break the vortex which tends to build up around the adjacent part of shaft 14.

Additionally, air which is entrained with the infiowing water may rise to the surface of the water in the reservoir to be removed by the vacuum pump.

As a result of the invention, a high impeller speed and a high delivery pressure can be attained without the limitations which could be imposed due to air leakage to the eye of the impeller. Satisfactory performance is also promoted by the `provision of two inlet openings (16, 21), into the pump casing; the openings 16, 2l, which are fed from the lower part of the reservoir chamber 1t), not only provide a large inlet area but also result in the impeller 14 being axially balanced. Furthermore, the submersion of the pump casing lill compensates for any porosity in the volute l2.

The pump construction is simple and robust and it is of importance that the pump casing parts can be assembled round the impeller lf3. Also the volute casting, which presents little difficulty as regards foundry work, extends laterally to form the chamber base and upwardly to form a substantial part of the walls of the reservoir and subchamber. The chamber 10 and sub-chamber 37 are `closed by a suitable cover 40. The side wall 15 of the chamber l@ may constitute the wall of a side housing (not shown) which accommodates part of the driving equipment. The opposite wall of the chamber l comprises a flat closure plate 41 which is easily removable for inspection or servicing of the pump interior.

While we have shown and described what we believe to be the best embodiment of our invention, it will be apparent to those skilled in the art that various changes and modifications may be made therein without departing from the spirit and scope of the invention as defined in the appended claims.

We claim:

1. A centrifugal pump of the class described, comprising: a rotary shaft; an impeller mounted on said shaft for rotation therewith; pump housing means surrounding said impeller, said pump housing means comprising a volute for the delivery of liquid pumped by said impeller; means defining at least one annular inlet passage concentric with said shaft and communicating between the exterior of said pump housing means and said impeller; means defining a chamber, said pump housing means being located in a lower portion of said chamber, said shaft extending into said chamber from the exterior thereof; continuously operative suction means separate from said impeller communicating with an upper portion of said chamber above said pump housing means; a liquid inlet communicating with said chamber; control means connected to said suction means for maintaining a substantially constant liquid level above said inlet passage in said chamber independently of the operation of said impeller; gland means sealing said shaft where it enters said chamber for prevention of the yentry of air into said chamber by longitudinal flow along said shaft; and means defining a separating chamber communicating with the interior of said first-named chamber above said constant level of said liquid, the lower end of said separating chamber communicating with said gland means in close proximity thereto interiorly of said first-named chamber, said shaft passing through said separating chamber with close clearance into said first-named chamber.

2. A pump according to claim 1, wherein said means defining said inlet passage defines two annular inlet passages at opposite sides of said impeller whereby said impeller, in operation, is axially balanced.

3. A pump according to claim 1, further comprising means resiliently mounting said gland means and stop means limiting axial movement of said gland means.

4. A centrifugal pump of the class described, comprising: means defining a closed pump chamber, said means comprising first and second spaced walls; a rotary shaft extending into said pump chamber through said first wall, said shaft extending across said pump chamber into proximity to said second wall; gland means supported by said first wall in sealing engagement with said shaft; an impeller on said shaft; means defining annular inlet passages at opposite sides of said impeller, said passages communicating between said pump chamber and the central eye portions of said impeller; a third wall disposed between said first wall and the one of said annular passages nearer to said first wall, said shaft passing through said third wall into said pump chamber with close clearance, said pump chamber defining means together with said first wall and said third wall defining a separating chamber communicating with said gland means and with the upper portion of said pump chamber; liquid inlet means communicating with said pump chamber; volute means in said pump chamber surrounding said impeller; liquid outlet means communicating with said volute means; check valve means included in said outlet means for preventing the entry of fluid into said pump chamber through said outlet means; continuously operative suction means separate from said impeller communicating with said chambers for simultaneously drawing liquid into said pump chamber through said inlet means and withdrawing air above said liquid in said pump chamber and in said separating chamber; and control means connected to said suction means for maintaining the level of said liquid within said pump and separating chambers at a substantially constant height above said annular passages and said gland means.

5. A pump according to claim 4, wherein said control means comprises float-actuated valve means.

6. A pump according to claim 4, further comprising resilient means mounting said gland means on said first wall.

7. A pump according to claim 6, further comprising stop means on said third wall for limiting axial movement of said gland means into said separating chamber.

8. A pump according to claim 7, wherein said stop means is formed as a circularly arranged series of castellations concentric with said shaft yand projecting from said third wall into said separating chamber.

9. A centrifugal pump for pumping liquid, comprising a chamber for incoming liquid, said chamber being formed w1th a side wall having an opening; a pump casing having two opposed faces each of which is formed with an entry, sald casing being positioned at least partly within the lower part of said chamber; a shaft which extends through .said opening and an entry; a seal positioned in said opening between said side wall and said shaft; a rotary impeller mounted on said shaft and positioned in said casing; a vacuum pump operatively connected to the upper part of said chamber; fioat means which control the action of the vacuum pump and maintain the liquid at a predetermined level within the chamber; and `a partition wall through which said shaft passes which is generally parallel to said side wall which is positioned adjacent said sidewall between said opening and said casing, and which extends upwardly to above said predetermined level.

10. A centrifugal pump as claimed in claim 9, which comprises fiexible and resilient mounting means which support said seal within said opening.

11. A centrifugal pump as claimed in claim 10, wherein said partition wall is formed with at least one eastellation extending towards said side Wall and positioned adjacent said shaft.

12. A centrifugal pump for pumping liquid, comprising a chamber for incoming liquid, said chamber being formed with a side Wall and a partition Wall adjacent and parallel to said side Wall, said side Wall and said partition Wall being formed with rst and second openings, respectively; a pump casing having said partition Wall and having at least one castellation adjacent said second opening which extends towards said side wall; a wall formed with a third opening, said pump casing being positioned in the lower part of said chamber; a shaft which extends through said iirst, second and third openings; a rotary impeller mounted on said shaft and positioned in said pump casing; a vacuum pump operatively connected to the upper part of said chamber; and float means positioned in the upper part of said chamber, said float means controlling the `action of the vacuum pump.

References Cited by the Examiner UNITED STATES PATENTS 1/1924 Jennings 103-113 4/1926 Hariveau 103-113 2/1934 Jacobsen 103-113 9/1942 La Bour 103-113 9/1947 Schleyer 103-113 3/ 1954 Montgomery 103-1 14 8/1957 Barton 103-113 12/1964 Ross 103-104 FOREIGN PATENTS 10/ 1924 France.

10/ 1933 France.

7/1951 Sweden.

DONLEY I. STOCKING, Primary Examiner. 0 HENRY F. RADUAZO, Examiner.

Claims (1)

1. A CENTRIFUGAL PUMP OF THE CLASS DESCRIBED, COMPRISING: A ROTARY SHAFT; AN IMPELLER MOUNTED ON SAID SHAFT FOR ROTATION THEREWITH; PUMP HOUSING MEANS SURROUNDING SAID IMPELLER, SAID PUMP HOUSING MEANS COMPRISING A VOLUTE FOR THE DELIVERY OF FLUID PUMPED BY SAID IMPELLER; MEANS DEFINING AT LEAST ONE ANNULAR INLET PASSAGE CONCENTRIC WITH SAID SHAFT AND COMMUNICATING BETWEEN THE EXTERIOR OF SAID PUMP HOUSING MEANS AND SAID IMPELLER; MEANS DEFINING A CHAMBER, SAID PUMP HOUSING MEANS BEING LOCATED IN A LOWER PORTION OF SAID CHAMBER, SAID SHAFT EXTENDING INTO SAID CHAMBER FROM THE EXTERIOR THEREOF; CONTINUOUSLY OPERATIVE SUCTION MEANS SEPARATE FROM SAID IMPELLER COMMUNICATING WITH AN UPPER PORTION OF SAID CHAMBER ABOVE SAID PUMP HOUSING MEANS; A LIQUID INLET COMMUNICATING WITH SAID CHAMBER; CONTROL MEANS CONNECTED TO SAID SUCTION MEANS FOR MAINTAINING A SUBSTANTIALLY CONSTANT LIQUID LEVEL ABOVE SAID INLET PASSAGE IN SAID CHAMBER INDEPENDENTLY OF THE OPERATION OF SAID IMPELLER; GLAND MEANS SEALING SAID SHAFT WHERE IT ENTERS SAID CHAMBER FOR PREVENTION OF THE ENTRY OF AIR INTO SAID CHAMBER BY LONGITUDINAL FLOW ALONG SAID SHAFT; AND MEANS DEFINING A SEPARATING CHAMBER COMMUNICATING WITH THE INTERIOR OF SAID FIRST-NAMED CHAMBER ABOVE SAID CONSTANT LEVEL OF SAID LIQUID, THE LOWER END OF SAID SEPARATING CHAMBER COMMUNICATING WITH SAID GLAND MEANS IN CLOSE PROXIMITY THERETO INTERIORLY OF SAID FIRST-NAMED CHAMBER, SAID SHAFT PASSING THROUGH SAID SEPARATING CHAMBER WITH CLOSE CLEARANCE INTO SAID FIRST-NAMED CHAMBER.

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