US2288902A - Axial flow pump - Google Patents

Description

f July 1942. 1 K. HARTMAN I AXIAL FLOW PUMP Filed Dec. 14, 1959 n WNY .mig

for; y v y Y' .{e'/fmajz Patented July 7,v 1942 UNITED' STATES Parar Fries Axial. FLow riJMr l Kante Hartman, Aurora, Ind., assigner to The American Well Works, Aurora,

tion of Illinois Ill., a corpora- Application December 14, 1989, Serial No. 309,198

6 Claims. v(Cl. 10S-89) clearance between them through which the pumped liquid can flow from the high pressure side of the impeller to the shaft. If the impeller is pumping upwardly or toward the shaft housing, high head pressure is thus transmitted through this clearance to the shaft seal. Although the leakage might be very slow, a small leak will nevertheless cause great injury in a relatively short time since the liquid `whichdoes leak through the seal accumulates above it and naturally seeps between the bearing surfaces.

According to the preferred form of the present inventiori this difficulty is overcome by combining two features, f'lrst the provision of an elongated passage between the high side of the impeller and theV shaft, and second the provision of liquid expelling means which returns such liquid as passes through this passage to the low pressure side of the impeller, thus preventing the building up of a pressure adjacent the shaft which would cause Athe liquid to penetrate through the seal.

Additional objects and advantages of the invention will be apparent from the following description and from the drawing, in which:

Fig. l is a vertical sectional view taken through the axial flow pump chosen for illustration of the invention.

Fig. 2 is a fragmentary sectional view taken approximately on the line 2-2 of Fig. l.

Fig. 3 is a fragmentary sectional view taken approximately on the line 3-8 of Fig. 1.

outside of shaft I8 and flows down thisshaft casing I3, the lower end of which may desirably be somewhat bell-shaped as seen at I4. 'I'he impeller I2 is carried by and keyed to a shaft I8 which in turn may carry a bearing sleeve Il which is journaled within a stationary bearing sleeve I8. The bearing sleeve I8 may be rigidly positioned in a housing I8 which is supported by webs 2I connecting it with the terminal casing member I8. A protecting pipe 22 surrounding pipeIB is screwed into the housing I9.

'To lubricate the bearings Il and I8 a drip feed lubricator, not shown, is provided above the surface and is` so connected that oil is fed to the under the. protection of pipe 22. Some of this oil will .enter between the bearings Il and I8 from the top of these bearings, and someof it will flow through passage 23 to an annular passage 24 below bearing I8 where the oil will have access tothe lower. portions of the bearings I'I l and I8. To prevent the oil from .flowing past the annular passage 2i, suitable shaft seal means is provided. This seal. has been illustrated as comprising two seal units 26, each of which may include a supporting ring '21 having a driven ilt with the housing I8 and a flexible seal member 28 which may be made of leather or oilresisting rubber. 'I he seal member 28 may desirably be held in contact with the shaft I8 by a coil spring 28, the parts of the unit 28 being held in assembled relation in the manner shown.

Although seal units such as the units 28 are Vvery satisfactory for most purposes, liquid may seep through them if under a substantial pressure. In the illustrated form of pump the impeller I2 should be rotated in a direction to pump liquid upwardly within the casing I8. Under s ome conditions there would therefore be a considerable head of pressure on the liquid being pumped. Since rotation necessarily occurs between the impeller I2 and the housing I8, it follows that there must be some clearance space between these members with the result that the liquid being pumped has access to the shaft I6 and the seal umts 26. Except for the present invention. therefore, the seal unit 26 would be subjected to the pressure produced by the impeller I2. The pumped liquid would accordingly seep through the seals, dilute the lubricant and corrode the bearing surfaces. Even though the seepage were small, the liquid would eventually get above lthe bearings I'I and I8 with the result that lubricant could not get downto these bearings.

According to the present invention the flow of the liquid being. pumped to the vicinity of the seal units 26 is greatly restricted by restricting at 3| the clearance space between the impeller I2 and the housing I9. To this end the impeller I2 is provided with an upwardly extending hub I9. The adjacent surfaces of these two mem- 32 which telescopes over a portion of the housing bers are cylindrically shaped and disposed cony centrically with the shaft I6. Theresult is 'that they may be fitted quite closely since the jour- I naling of the shaft Isubstantially eliminates lateral play. Nevertheless, it is not practical to prevent leakage in the clearance space even through the restricted portion 3l.

To prevent this leakage from building up a pressure which would cause leaking of the seal' such liquid being pumped as leaks through therestricted-passage 3l will now through the passage 33 and its extension 34 and be drawn'out through the outlet 3B. To be sure that the liquid will all be drawn out, a plurality of the-passages 33 and outlets 36 may be provided and the parts may be positioned to form a drainage chan' nel 3'I between the restricted portion 3l and the seal units 26.v All of the passages 33 may conveniently communicate with the drain channel 31.

The outlets 36 are illustrated as formed by notches in the bottom of the impeller I2. vIty will thus be observed that the-walls of the notches for'm radially extending Walls on each side of the notches or outlets 36, Any liquid in the outlets .36- Will thus be positively rotated with the impeller and will thereforebe subjected to centrifugal -shaft extending through the housing, an impeller mounted on the shaft and adapted to rotate in a direction to force liquid towardthe housing and forming a restricted clearance space with the housing, a seal between the housing and the shaft, the impeller having a passage communicating with the clearance lspace and having an outlet on the suction side of the impeller blade and close thereto,- a cap on the shaft beyond the impeller, and an outside casing surrounding the impeller shaped to form a Venturi passageway, the outlet being approximately at the throat of the Venturi passageway and having side walls extending generally radially 'whereby the rotation of the impeller will exert a centrifugal action on the fluid in the outlet, thus aiding the impeller in drawing the liquid from the passage.

3. An axial flow pump including a housing, a shaft extending through the housing, an impeller -mounted on the shaft and adapted to rotaie in a direction to force liquid toward the 4housing outlet on the suction side of the impeller blade force which will aid in expelling the liquid from the outlets 36.

The shaft. I6 is preferably provided `with a streamlined cap 4I screwed thereon; This cap together with the illustrated shaping of the bottom portion I4 of the casing forms a Venturi passage 42 in which the liquid being pumped is moved at high speed by the impeller I2. As is well known, liquid owing smoothly through a Venturi passage has a reduced lateral pressure fand, accordingly, the suction in the nature of and I8 may be kept thoroughly lubricated without anydanger that water will be forced through the seals 29 by the high pressure developed by the pump.

I claim:

and close thereto, .a streamlined now guide on the suction `side of the impeller, and an outside casing surrounding the impeller and extending therebeyond, spaced from and surrounding the flow guide and shaped to cooperate with the flow guide to form a Venturi passageway leading to the impeller, with said outlet approximately at the throat of the Venturi passageway.

- 4. An axial now pump including a housing, a

shaft extending through the housing, an impeller therebeyond, spaced from and surrounding the 1. An axial flow pump including ahousing, a

shaft extending through the housing, an impeller mounted on the shaft and adapted to rotate in a direction to force liquid toward the housing and forming a restricted clearance space with the housing,l a seal between the housing and the shaft,` the impeller having a passage communicating with the clearance space and -having an outlet on the suction side of the impeller blade and close thereto, a cap on the shaft beyond the iiow guide and shaped to cooperate with the flow guide to form a Venturi passageway leading to the impeller, said outlet being approximately at the throat of the Venturi passageway'and having side valls extending generally radially whereby the rotation of the impeller will exert a centrifugal action on, the iiuid in the outlet, thus aiding the impeller in drawing the liquid from the passage.

5. An axial flow pump including a housing, a shaft extending through the housing, an impeller mounted onv the shaft and adapted to rotate in a direction to force liquid toward the housing and forming a restricted clearance space with the housing, a seal between the housing and the shaft, the impeller having a passage communicating with the clearance space and having an outlet on the suction side of the leading edge of the impeller blade and close thereto, and flaringinlet guide means defining the passage adjacent the impeller blade' on the suction side thereof and so shaped as to causethe liquid to be pumped to flow smoothly past the outlet with-A out exerting a force of `momentum into the outlet, said outlet opening at a reduced portion of the flaring inlet where the liquid moves at high speed.

6. An axial flow pump including a housing, a shaft extending through the housing, an impeller mounted on the shaft, constructed to pump liquid in un axial direction, and adapted to rotate in a direction to force liquid toward the housing and forming a restricted clearance space with the housing, a seal between the housing and the shaft, the impeller having a passage communi- -cating with the Iclearance space and having an outlet on the suction side of the ieading edge of the impeller blade and close thereto, and flaring inlet guide means so shaped as-to cause the liquid 10 high speed.

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