US2349731A

US2349731A - Centrifugal pump

Info

Publication number: US2349731A
Application number: US435444A
Authority: US
Inventors: Hornschuch Hanns
Original assignee: Ingersoll Rand Co
Current assignee: Ingersoll Rand Co
Priority date: 1942-03-20
Filing date: 1942-03-20
Publication date: 1944-05-23
Anticipated expiration: 1961-05-23

Description

May 23, 194 H. HORNSCHUCH CENTRIFUGAL PUMP Filed March 20, 1942 3 Sheets-Sheet 1 INVENTOR JYarmdlioonJc/auc/a HI 5 ATTORNEY.

y 3 1944- H. HORNSCHUCH 2,349 73l CENTRIFUGAL PUMP Filed March 20; 1942 3 Sheets-Sheet 2 INVENTOR mnmiflmm/schucfb BY v H l5 ATTORNEY.

Patented May 23, 1944 'UNiTED STATE s PATENT OFFICE cnn'rairuou. rim

Hanna Hornschuch, Easton, Pa.', .assignor Ingersoll-Rand Company, New York, N. Y.,' a corporation of New Jersey Application March 20, 1942, Serial No. 435,444

' '-6 Claims. (Cl. 10

without necessitating the operation of the pump at reduced speeds. Another object is to assure the delivery of liquid to a pump impeller in a state best suited to assure maximum impelling effect upon the liquid.

Otherobjects will be in part obvious part pointed out hereinafter.

In the drawings accompanying this specifica-' tion and in which similar reference numerals refer to similar parts,

Figure 1 is an elevation, partly in section, of a centrifugal pump constructed in accordance with the practice of the invention,

Figure 2 is a view similar to Figure 1, although somewhat enlarged, showing the impelling element of the pump in section,

Figures- 3 and 4 are perspective views of the pumplmpellers, and

Figures 5 and 6 are views similar to Figure 2 showing modified forms of the invention.

Referring to the drawings and at first more particularly to Figures 1 to 4 inclusive, 20 designatesa centrifugal pump comprising a' c sing 2! having an impeller chamber 22 and an 1 et passage 23 for conveying liquid to the impeller chamber. The casing-also has an outlet passage 24 forthe discharge of liquid from the impeller chamber, and a head 25 is secured to the casin and in 21 by bolts 26 to form a closure for one end' ofthe impeller chamber 22.

The head 25 is provided than the sleeve 3! to receive packing material 3| which is disposed about the sleeve 3! for prevent ing leakage of liquid through the bore 21 exteriorlyof the sleeve. The inner end of the packing material 33 seats against an annular wearing piece 35 inserted in the bore 21. The imwith a horizontal bore 21 to receive; amongtother elements, a-shaft 23 that extends through the hub 23 of animpeller 33 peller 33 and which may be termed the main impeller issecured to the shaft 28 by clamping its hub against the sleeve 3| with a nut 38 on the outer extremity of the reducedportion 32 of the shaft.-

In order to avoid subjecting the

packing members

33 and 34 to the high pressure of the liquid in the impeller chamber 22 the impeller is provided on its end surface with radially extending vanes 31 to eject liquid from the space between the impeller and the head 'andthereby maintains a zone of low pressure adjacent the end of the bore 21.

In accordance with the practice of the invention, the liquid pumped by the impeller is delivered thereto by a second or booster impeller 38 also arranged in the impeller chamber 22. The booster impeller 33 is capable of free rotation relatively-to the main impeller and is mounted, for such rotation, upon-an end portion 39 of theshaft 23, the shaft having a sleeve 33 to provide a bearing surface for bushings ll extending into the opposite ends of thehub 32 of the impeller 33. I

A seat. in the form of a washer 43, clamped against a shoulder 34 at the juncture of the reduced and

end portions

32 and 33, respectively,

of the shaft is provided for the inner end of the sleeve 40. A cap nut 35 threaded upon the extremity of the end portion 33 of the shaft secures the sleeve 30 and the washer-l3 in assembled positions and overlies the'end of the outermost bushing ll to serve as an abutment therefor. The sleeve '40 is of such length and the cap nut and the washer 33 are, in consequence, so spaced'with'respect to each other that the impeller 331s capable of rotating freely upon the shaft withouthindrance from the elements restraining it from. endwise movement.

In the form of the invention illustrated, the eye 36 of the impeller 30 is of frusto-conical shape and itsbottom' 31 is defined by the innerwall 43 of the impeller 30. Owing to this arrangement the inner ends 49 of the vanes 53. of the impeller 33 lie at an'acute angle with respect o the axis of the shaft and the inner end portions of the water-ways in the impeller are only slightly curved as indicated at 5| so that there will be only a'small degree of deviation of the course of the'liquid within the impeller 30. The vanes 53 may be of any known design to assure desired impelling surfaces but are preferably curved as indicated more particularly in Figure 4 of the drawings. v

.It is in the booster impeller 33 that the initial 1 peller balancing function. An outlet is provided transition from axial flow to radial flow of the liquid takes place. The vanes 52 of said impeller are, as indicated more particularly in Figure 3 of the drawing, of the curved type. They extend into the radial plane of the eye of the main impeller, and operate to deliver the liquid to the main impeller in a whirling body. As a preferred arrangement the inner or discharge ends 53 of the vanes 52 are separated by a suitable space 54 from the ends 49 of the vanes 50 of the main impeller in order to assure a full supply of liquid to the main impeller in all relative positions of the impellers.

The force serving to cause rotation of the booster impeller 38 is derived from the impeller 38. To this end the main impeller is provided on the end surface confronting the booster im' peller with a plurality of radially extending ribs 55 for imparting rotary motion to the liquid in the adjacent portion of the impeller chamber 22,. The force thus generated acts against the side of a flange 55 on'the periphery of. the impeller 38 and lying closely adjacent the ribs 55. The side of the flange 58 confronting the ribs 55 may, as shown, also be provided with radially extending ribs 51 to assure the utmost utilization of the forceor thrust of the rotating body of liquid] between the impeller 38 and the flange 56.

The liquid serving the function of transmitting driving force from the impeller 38 to the impeller 38 is cast centrifugally into the impeller chamber by the ribs 55 which cause a constant circulation of liquid between the impeller and the flange 55. Such liquid, in the present instance, is derived in part from the space 54 which communicates with thespace between the impeller 38 and the flange 55 through an. annular groove 58 in the inner end of the rim 59 of the impeller38. The groove 58 is of considerable depth to accommodate an annular flange 60 on the impeller 38, and ample clearances exist between the annular surfaces of the groove 58 and the flange 58 so that liquid will flow freely through the groove. 7

Suitable balancing means are provided to assure against 'undue end thrust of the booster im- 38 in the direction of the inlet passage 23. To this end the booster impeller is provided with a cylindrical extension 5| on the endof the rim 59. The extension 5| extends rotatably into an annular groove 52 in the inner surface of a linerj3 defining the inlet passage directly adjathe bottom of the groove 82 to act against the end of the cylindrical extension for performing its for liquid from the groove 52 by passages 54 in the extension 8| and the rim 59 and leading into the groove 58. Thus, some of the liquid impelled by the ribs for driving the booster impeller 38 is also derived from the impeller chamber 22.

The operation of the device is as follows: At the beginning of rotation of the main impeller 38 the force generated by the ribs 55 may be insufllcient to overcome the resistance of the booster impeller. But upon acceleration of the impeller 38 this force will increase until it reaches a critical value sufllcient to setthe impeller 38 in motion. As the speed of the impeller 30 increases the it attains the maximum speed consistent with the force serving to drive it.

Owing to the slippage that must naturally result between the driving and driven elements the impeller 38 will, of course, operate at a somewhat lower speed than the main impeller. The extent of this differential in speed will var in accordance with variations in size of the area on the booster impeller against which the force is applied for driving it, as will be readilyunderstood. 1

During this operation of the pump the liquid flowing through the inlet passage 23 will first be handled by the comparatively slow moving impeller 38 so that a whirling motion will be imparted to .it for delivering it as a whirling body to the main impeller which will impress additional velocity to the liquid.

In practice, it has been found that, owing to the use of the booster impeller arranged and driven in the manner hereinbefore described, a

centrifugal pump of a given design may operate with increased emciency at a considerably greater suction lift or at lower positive suction head and without necessitating reduced rotative speed of the impeller than would be the case if the liquid were pumped only by the main impeller. It has further been found that these advantages may be obtained without necessitating an appreciable expenditure of additional power for driving the pump.

The modified form of the invention shown in Figure 5 differs from that previously described principally in that the impellers are mounted upon separate shafts arranged coaxiallywith respect to each other. The impeller 30 is avccdrdingly mounted upon the end of the shaft 28 which has threaded thereon a nut 35 for clamping the impeller upon the shaft. The impeller 38 is secured, in like manner, by a nut 85 upon a reduced end portion of a shaft 61.

The impeller 38 is suitably keyed to the shaft 61 and said shaft extends through a packing element 58 in the end of the casing 2| and into a bearing cage 69 exteriorly of the casing 2|. Suitable anti-friction bearings 10 are arranged in the ends of the cage 59 for the shaft 8! and the shaft preferably has shoulders H to abut the inner races of the anti-friction bearings for pre- The inlet passage 23 is, moreover, located within impeller 39 will alsoaccelerate until the head 12 and the inner end of the head forms a bounding surface for the impeller chamber 22. In this form of the invention the main impeller designated 13 is open on one side and a.

flange 14 on the periphery of the booster impeller 38 serves as a shroud for the open. side of the main impeller. The flange I4 is disposed closely adjacent the open side'of the impeller 13 so that its inner surface 15 will besubjected to frictional contact with the liquid in the main impeller and moving rotatively therewith for driving the booster impeller 38.

The booster impeller 38 is shown as being mounted rotatively upon an end portion 16 of the shaft 11 carrying the main impeller, and a collar 18 on the shaft 11 lies between the hubs of the impellers to clamp the impeller I3 against the sleeve 3| and to act as an abutmentfior the innermost of the bushings 4| in ,the booster impeller.

I claim:

1. A centrifugal pump, ,comprising a casing to absorb power from the fluid pumped by the main impeller for effecting rotation of the said second impeller.

2. A centrifugal pump, comprising a casing having an impeller chamber, an impeller in the impeller chamber, a shaft in the casing for the impeller, means for locking the impeller to the shaft, and a second impeller supported by and freely rotatable upon the said shaft to deliver liquid to the first mentioned. impeller fluid-impelling means on the side of the main impeller, and flange means on thesecond said impeller and having means on a side thereof presenting radially extending surfaces to absorb power from the fluid pumped by the said fluid-impelllng means for effecting rotation of said'second impeller.

3. A centrifugal pump, comprising a casing having an impeller chamber, a main impeller in the impeller chamber, a second impeller for delivering liquid to the main impeller, blade means on an outer side surface of the main impeller for imparting rotary motion to liquid in the impeller chamber, and blade means on the second impeller subjected to the force of the liquid rotatlng in the impeller chamber for driving the second impeller.

4. A centrifugal pump, comprising a. casing having an impeller chamber, a main impeller in the impeller chamber, ribs on the side of the main impeller to impart a whirling motion to liquid in the impeller chamber, a second impeller in the said impeller chamber to deliver liquid to the main impeller, and a flange on the second impeller arranged adjacent the said ribs and having ribs subjected to the whirling motion of the liquid impelled by the first-mentioned ribs for rotating the second impeller.

5. A centrifugal pump, comprising a casing having an impeller chamber, an open-type impeller in the impeller chamber, a second impeller to deliver liquid to the first mentioned impeller, and means on the second impeller forming a shroud for the open side of the open-type impeller.

6. A centrifugal pump, comprising a. casing having an impeller chamber, an open-type impeller in the impeller chamber, a second impeller toideliver liquid to the flrst mentioned impeller, and a flange on the second impeller forming a shroud for the open-type impeller and being subjected to the liquid passing through the open-type impeller for driving said second impeller.

HANNS HORNSCHUCH.