US3380390A

US3380390A - Centrifugal pumps

Info

Publication number: US3380390A
Application number: US531389A
Authority: US
Inventors: Rachman David
Original assignee: Individual
Current assignee: Individual
Priority date: 1966-03-03
Filing date: 1966-03-03
Publication date: 1968-04-30
Anticipated expiration: 1985-04-30

Description

April 1968 Dv RACHMAN 3,389,390

CENTRIFUGAL PUMPS Filed Mwmh 1966 Sheets-Sheet l l L :[T I l L J IF :IL

April 30, 1968 D. RACHMAN 3,380,390

CENTRIFUGAL PUMPS Filed March 5, 1966 2 Sheets-Sheet United States Patent 3,380,390 CENTRIFUGAL PUMPS David Rachman, 29 Melrose.Ave., Rutherglen, Scotland Filed Mar. 3, 1966, Ser. No. 531,389 2 Claims. (Cl. 103113) ABSTRACT OF THE DISCLOSURE A centrifugal pump includes a single impeller contained with a pump casing and incorporating blades disposed between shrouds having smooth unbroken outer surfaces. One or more nozzles communicating with the discharge side of the pump are directed into the pump casing and are so located that the line of discharge of the nozzle is offset from the axis of the impeller and intersects the outer surface of the shroud at an acute angle such that a jet of liquid issuing from the nozzle will impact against the shroud.

This invention relates to centrifugal pumps and has for an object to provide a construction intended to facilitate priming of a centrifugal pump and/or to control the operating characteristics of a centrifugal pump and/or to prevent the formation of a vapour lock in the pump.

According to the invention a centrifugal pump having a casing containing an impeller presenting blades located between shrouds incorporates at least one passage leading from the discharge side of the pump to at least one nozzle directed into the pump casing and so located that the line of discharge of the nozzle intersects the surface of one of the shrouds.

The pump may be formed with a liquid storage space to which the impeller discharges, the passage leading from this liquid storage space to the nozzle.

The pump may incorporate several passages leading from the discharge side of the pump and terminating several nozzles so located on opposite sides of the pump impeller that the line of discharge of each nozzle intersects the shroud on the side of the impeller facing that nozzle.

A practical embodiment of the invention is illustrated in the accompanying drawings in which FIG. 1 is a vertical longitudinal section through a pump, and FIG. 2 is an outside elevation.

In the drawings, 1 denotes a pump casing containing an impeller 2 having blades 3 located between shrouds 4. 5 denotes a chamber located between the discharge end 6 of the pump 6A and a discharge pipe 7 and constituting a liquid storage space. 3 denotes nozzles formed in the pump casing 1 and disposed to discharge towards the adjacent shroud 4, the nozzles 8 being in communication by a passage 9 with the chamber 5. 10 denotes a nonreturn valve of the flap type located in the inlet passage 11 to the impeller.

In practice, the invention may be used mainly for priming a centrifugal pump, liquid from the chamber 5 which is on the discharge side flowing through the passage 9 when the pump is set in operation and issuing as jets from the nozzles 8, the jets impinging on the adjacent impeller shroud 4 as the impeller 2 rotates. The jets are broken up as they strike the moving shroud 4 and energy is added to the liquid which is spun off the upper edge of the shroud 4 as a sheet which entrains any air present,

ice

the entrained air passing along with the liquid into the pump volute 6A. Air in the inlet passage 11 to the pump flows by the shortest route to the zone of low pressure and thus tends to bypass the impeller 2 and flows towards the nozzles 8 and into the pump volute 6A between the impeller and the casing. It is known to arrange for the priming of a centrifugal pump by the provision of a return passage leading from a liquid storage space on the discharge side of the pump back to the pump but in the known construction the return passage terminates either at a point adjacent to the impeller inlet or at a point in the vicinity of the outer tips of the impeller blades. Disadvantages of the previous construction are that where the return passage terminates at the inlet of the impeller air entrained from the suction pipe passes through the impeller passages and causes eddies therein and also once the pump has been primed the return passage must be closed otherwise the operating efficiency of the pump is severely impaired, and where the return passage terminates in the vicinity of the outer tips of the impeller blades the direction of flow through the return passage reverses once the pump has become primed. In the construction according to the invention no reversal of flow takes place under optimum operating conditions and there is in fact an appreciable increase in pump performance after the pump has become primed. The nozzle or each nozzle may be so proportioned and located that the selfpriming feature is a secondary feature and the main feature provided by the construction is the increase in pumping performance.

What is claimed is:

1. A centrifugal pump, including at least one pumping stage, having a casing provided with a liquid storage chamber associated with the casing, an impeller contained within the casing, said impeller having blades supported between axially spaced shrouds, said shrouds having smooth unbroken outer peripheral surfaces, said casing having a nozzle directed at an acute angle to the axis of the impeller toward one of said smooth, unbroken surfaces and a passage means communicating with the liquid storage chamber whereby liquid will be supplied to said nozzle and will be directed against said smooth, outer surface to be discharged at the periphery of said impeller to prevent loss of prime by the impeller on r04 tation thereof.

2. A centrifugal pump in accordance with claim 1, wherein said casing includes a plurality of nozzles, each of said nozzles being directed at an acute angle to the axis of the impeller toward one of said smoot h, unbroken surfaces and a like plurality of passage means communicating with said liquid storage chamber whereby liquid is supplied to said nozzles.

References Cited UNITED STATES PATENTS 1,946,212 2/1934 Jacobsen 103 113 2,791,968 5/1957 Rupp 103 113 FOREIGN PATENTS 152,673 1922 Great Britain. 345,973 1931 Great Britain. 368,879 3/1939 Italy. 134,165 10/1929 Switzerland.

HENRY F. RADUAZO, Primary Examiner.