US3230890A

US3230890A - Centrifugal pump

Info

Publication number: US3230890A
Application number: US324065A
Authority: US
Inventors: Yokota Hidekuni; Yokota Shingo
Original assignee: Individual
Current assignee: Individual
Priority date: 1962-11-20
Filing date: 1963-11-15
Publication date: 1966-01-25
Anticipated expiration: 1983-01-25
Also published as: JPS403655B1

Description

Jan. 25, 1966 HIDEKUNI YOKOTA ETAL 3,230,890

CENTRIFUGAL PUMP 5 Sheets-Sheet 1 Filed NOV. l5 1963 FIG.

Jam 25, 1966 HIDEKUNI YOKOTA ETAL 3,230,890

CENTRIFUGAL PUMP 5 Sheets-Sheet 2 Filed NOV. l5, 1963 FIG. 5

Jan. 25, 1966 HIDEKUNI YoKoTA ETAL 3,230,890

CENTRIFUGAL PUMP 5 Sheets-Sheet 5 Filed NOV. l5, 1963 FIG. 8

FIG. 6

FIG. 7

United States Patent O 3,230,890 CENTRIFUGAL PUMP HidekuniYokota, 671 Yoshijima-ho, and Shingo Yokota,

" 1627 Midori-machi, both of Hiroshima-shi, Japan Filed Nov. 15, 1963, Ser. No. 324,065 Claims`priority, application Japan, Nov. 20, 1962, 37/52,2`59; Mar. 23, 1963, 38715329 2 Claims. (Cl. 1113-113) This invention relates to centrifugal pumps and more particularly to a new centrifugal -pump suitable for pumping high-viscosity, mud-like fluids `containing large amounts of -lbulbble's. t l

The pumping of high-viscosity, mud-like fluids containing large ainounts-of-'bubbles by means .of centrifugal pumpsis generally considered to'be'- extremely difficult.

Atthe same time, thereis `a great demand for -a simple,

' safe, and reliable'means for pumping such muddy uids containing additional foreign solid matter.

It has been found that'the reason for this difficulty of centrifugalipump Acombined with a vacuum creating means wherein the-*ingress of the fluid into lthe vacuum creating means is'eifectively prevented.

`According to the present 'invention, there is provided a centrifugal 'pump (referredto hereinafter as the main pump); adapted for pumping of the above mentioned muddyi-fluid, and in sideby-,side relation to the main pump is arranged v'another centrifugal pump (referred to" hereinafter as vthe auxiliary pump) for drawing vair .avities in the main pump. The auxiliary pump is, through 'the suction inlet thereof, in communication with the cejntralarea of the. main pump chamber and is, throughfhe discharge outlet thereof, in communication with'the suctioninlet of the .main pump. The central area of the auxiliary pump chamber is lin communication with a suitable vacuumcreating means through a suction passage,fso' ,that,airfcavities in-the main pump chamber will `betfdrawn intofand forced through vthe auxiliary pump chamber. to the vacuumcreating means in order to ensure acontinuous fiuid-iiow through the main pump chamber.f. f.

Accordingto another object of this invention, there is. provided a valve ymeansbetween the auxiliary pump and the .vacuum creating means, which valve means is constructed soas to open the suction passage from the auxiliary pump to the-vacuum creating means when the vacuum creating means is operative and to close the samewhen the'vacuum creating means is inoperative, thus preventing ingress of fluid to the vacuum creating means.v Y

The nature, principles, and details of the invention, as well as other objects and features thereof, will be more 'cl'ea'rly apparent from thefollowing description taken in connection with the accompanying drawings in which like parts are designated by like reference characters, and in which:

FIG. 1 is a side elevational view, partly in vertical materials.

ICC

section, showing a prefered embodiment of the centrifugal pump of this invention;

FIG. 2 is a section taken along the line II-II of FIG. l, the View looking in the direction of the arrows;

FIG. 3 is a section taken along the line IIL-III of FIG. l, the view looking in the direction of the arrows;

FIG. 4 is a side elevational View, partly in vertical section, showing a modified centrifugal'pump according to this invention;

FIG. 5 is a section taken along the line V-V ofFIG. 4, the viewlooking in the direction of the arrows;

FIG.6 is a section taken along the line VI-VI of FIG. 4, the view looking in the direction of the arrows;

FIG. 7 is a section taken -along the line VII--VII .of

FIG. 4, the view looking in the direction of the arrows;

l and charge outlet 5, which communicates with the .suctionV inlet 3 of the main pump A through a connecting pipe 8 and a' return passage 7 leading into the suction inlet 3:.I Within the main pump casing 1 there is an impeller 9-provided with blades 11 and theimpeller 9 is mounted on a driving shaft 10. The impeller 9 is shown as ibeing of open type having no shroud but the impeller may 4be of'any known type according to' the nature of fluid to'be treated. Between the main pump casing 1` andthe auxiliary pump casing 2 there is disposed a partition plate 6 serving as side walls of both the main and auxiliary pump casings. The partition plate 6 is provided with a centrally cut opening through which the driving shaft 10 extends. The opening of the partition plate 6 is vso formed that the diameter thereof is slightly larger' than that of the shaft 10 and increases gradually toward the auxiliary pump B. Thus, it Will be apparent that a gap 13 between the'outer face of the impeller hub and the inner surface of the opening of the partition plate 6 is greater on the side of the auxiliary pump B and smaller on the side of the main pump A. The

tapered form of vthe gap 13 serves to prevent the gap from` being clogged with foreign matter. The vmembers which form the gap 13 may be made of a combined hard material and rubber to increase their durability, or may be provided with teeth to crush foreign matter and fibrous In'any case, it is necessary to suitably throttle the inlet of the auxiliary pump Bat the gap 13 in relation to the pumping capacity of the auxiliary pump B.

Within the auxiliary pump casing 2 there is an impeller 14 having therethrough openings 15 in the central portion thereof and the impeller 14 is also mounted on the driving shaft 10. The auxiliary pump casing 2 has an air suction passage 16 which extends from the central portion of the auxiliary pump vB so as to communicate with an intake 17 of a vacuum pum-p 18, which is driven by the driving shaft 10 together with the

impellers

9 and 14. About the driving shaft 10 there is provided a stuffing box 19 containing sealing material 20 therein.

In operation, when the pump is driven with the discharge outlet 4 thereof closed, the air on the suction side of the main pump is drawn into the vacuum pump 18 through the inlet 3, the impeller 9, the gap 13, the impeller 14, the passage 16, and the intake 17 of the vacuum pump 18, and at the same time through the inlet 3, the return passage 7, the connecting pipe 8, the discharge outlet 5 of the auxiliary pump B, the impeller 14, the passage 16, and the intake 17 of the'vacuum pump 18. Thus, the vacuum established in the pum-p chamber causes vthe luid to be treated `to ow into the suction inlet 3 and thence into the chamber of the main pump A so as to fill' the chamber. The uid thus introduced into the chamber of the main pump A tends to advance to iill the return pasage 7, the connecting pipe 8, and the discharge outlet 5 of the auxiliary pump B, and reach the chamber of the auxiliary pump B. However, the auxiliary pump B is so designed that the impeller 14 thereof may operate to overcome the vacuum developed by the vacuum pump 18, and, therefore, the pump B prevents the fluid from being drawn from the pasage 7 to the auxiliary pump B, thereby functioning as a kind of check valve.

Thus, thefluid in the chamber of the main pump A ows through the gap 13 into the auxiliary pump B, and

thence through the discharge outlet 5 and the returnv pasa'ge 7 back to the chamber of the main pump A because of the fact that the gap -13 which is an inlet of the auxiliary pump B is throttled.

It will be apparent, therefore, that the fluid introduced into the auxiliary pump chamber never flows into the air suction passage 16, and the vacuum pump 18 is maintained free of the fluid.

When the uid contains much air, it is introduced into the main pump A with a number of cavities. Under such a condition, the cavities are expelled from the main pump chamber through the gap 13 into the auxiliary pump chamber. The auxiliary pump, being'also a strong centrifugal separator, centrifugally separates the air from the duid and delivers the remaining fluid from therv discharge outlet 5 back to the main pump A, thus attaining a continuous and reliable pumping operation. The openings 15 serve vto pass the cavities from the gap 13 to the passage 16.

In the practical use of the pump as described above, in case an equipment havinga positive suction head is adopted and the viscosity of the liquid to be treated is not high, a particular vacuum pump is not necessary. In this case, it is only necessary to lead the air suction passage 16 up to a position higher than the liquid suction level by means of a pipe -device and more favorable eifects can be expected by providing a check valve adapted to check suction of the external atmosphere into the passage at the extreme or intermediate portion of the passage.

Referring now to FIGS. 4 to 8, there is shown a modied form of the pump according to this invention. The construction of this modified form is substantially the same as that shown in FIGS. 1 to 3 with the exception that the modified pump is provided with a safety valve 21 which is inserted between the air suction passage 16 and the intake 17 of the vacuum pump 18 and may be positioned on the casing of the pump. The embodiment illustrates a particular exam-ple in which a semi-open type impeller and a special contrivance adapted to decrease `cavitation at the back surface of the blades are provided. In other words, at the shroud of the impeller, a slit 12 is provided along the back surface of each blade 11 so that the inside end portion of the slit 12 faces the gap 13. Accordingly, the back surfaces of the blades 11 are always in direct communication with the vacuum pressure of the vacuum pump. The safety valve 21 includes a valve casing 22, which has in the bottom plate thereof an opening 23 in which is fitted a valve seat 24. The valve casing 22 is also provided in the side wall thereof with a port 25 communicating with the intake 17 of the vacuum pump 18. In the upper part of the casing 22 there is a diaphragm 26 extending transversely thereacross and secured at its periphery to the casing 22 in air tight relation thereto. A cover 27 is secured to the upper end of the casing 22, and the cover 27 is provided with an opening 28. Immediately under the diaphragm 26, there is a valve rod 29 which extends ve-rtically and centrally through the casing 22 and which is supported by a support 30 for permitting vertical movement. The valve rod 29 is always urged upwardly by a coil spring 31 and is provided at the lower end thereof with a valve head 32 abuttingly engageable with the valve seat 24. The coil spring 31 is so designed that when the pressure in the valve casing 22 is equal to the external atmospheric pressure, that is, when the vacuum pump is inoperative, the valve head 32 is in con-tact with the valve seat 24. The diaphragm 26, in practice, may be replaced by'other' equivalent means such as a bellows or piston. l

The pump described above in connection with FIGS. 4 to 8 is suitable for use'in the case where the level of fluid to be pumped is higher than that of the pump. Then, when the pump is inoperative, the fluid to be treated is caused to ow into the pump chamber. However, the rise of Vthe fluid level in the auxiliary pump chamber is limited because the valve 21 1closes the passage 16, thus causing air to be coniined in the upper part ofthe passage 16.

In operation, when the pump is started, the fluid flows from the main pump chamber through the throttled gap 13 linto the auxiliary pump chamber,l whilethe fluid in the air suction passage 16 is delivered to the discharge out. let 5 of the auxiliary pump B by the rotating impeller 14 thus flowing back to the main pump chamber through the return passage 7. In such a condition, the 4rotating impeller 14 of the auxiliary pump B holds air cavities near the central portion thereof. ,Y l v When the pressurein the valve casing 22 decreases because of the operation ofthe vacuum pumpv18, the diaphragm 26 is displaced downwardby atmospheric pressure to cause the rodr29,to move downward againstrthe force of the spring 31, thereby permitting the valve 21 to open, whereby the pressure in t-he passage 16 is decreased together with the pressures in the central parts of the main and auxiliary pumps A and B. Thus, the required pumping oper-ation is accomplished.

If air cavities are formed in t'hercentr'al rarea of the main pump chamber by the introduction of air-containing fluid, they will be expelled into theauxiliary 'pump cham` ber and thence into the air suction passage 16. The auxiliary pump B of` this example is also of such `design that the` impeller 14 thereof umay operate to overcome the vacuum developed by the vacuum pump 18. Therefore,` the fluid being treated is prevented from entering into y' is not used. The ingress of fluid into the"vacuurnfpu'mpV 18 is undesirable and will always cause pump failure if fit is of a nature harmful to this pump.

, While we have disclosed preferred embodiments of this invention, it is to be understood that various changes and modifications may be madetherein without departing fromy the spirit and scope of lthis invention. For example, there lmay be` provided a'oat valve in the air suction passage 16 for preventinguundesirable'ingress ofthe fluid into the vacuum pump 18 inthe vcase ofdamage to the impeller 14 or of pump stoppage. The suction line between the air suction passage '16 andthe intake 17 of the vacuum pump 18 may have a fluid sumpwith a check valve for fluid disposal at the bottom thereof for the sake of safety. Furthermore, the auxiliary .pump impeller 14 may have two impeller plates for eicient centrifugalseparation of uid from air, and the openings 15 provided in the impeller 14 may be arranged eccentrically and in a staggered state.

What we claim is: Y H D 1. A centrifugal pump assemblage comprising a main pump having a casing, a driving shaft,`a main` centrifugal impelier mounted on said shaft within the casing,l a suction inlet and a discharge outlet communicating with said casing,an auxiliary pump having an auxiliary casing disposed in side-by-side relationship to the main pump casing, a common wall between said main and auxiliary casings, an auxiliary centrifugal impeller, said driving shaft extending through the auxiliary pump casing and through said common wall, said auxiliary impeller being mounted on said shaft within said auxiliary pump casing, said common wall having a central suction inlet opening therein providing communication between said main pump casing and said auxiliary pump casing, means on said shaft serving to restrict the cross sectional area of said central suction inlet opening, a discharge outlet from said auxiliary casing communicating with the suc tion inlet of the main pump casing, whereby dense tluid is discharged from said auxiliary pump casing to the suction inlet of said main pump casing, and a vacuum pump having a suction inlet in communication with said auxiliary pump casing, whereby gaseous medium is withdrawn from said auxiliary pump casing, the pumping capacity of the vacuum pump being such that the vacuum developed thereby is overcome by the pumping action of the auxiliary pump.

2. A centrifugal pump assemblage comprising a main pump having a casing, a driving shaft, a main centrifugal impeller mounted on said shaft within the casing, a suction inlet and a discharge outlet communicating with said casing, an auxiliary pump having an auxiliary casing disposed in side-hy-side relationship to the main pump casing, a common wall between said main and auxiliary casings, an auxiliary centrifugal impeller, said driving shaft extending through the auxiliary pump casing and through said common wall, said auxiliary impeller being mounted on said shaft within said auxiliary pump casing, said common wall having a central suction inlet opening therein providing communication between said main pump casing and said auxiliary pump casing, means on said shaft serving to restrict the cross sectional area of said central suction inlet opening, a discharge outlet from said auxiliary casing communicating with the suction inlet of the main pump casing, whereby dense Huid is discharged from said auxiliary pump casing to the suction inlet of said main pump casing, a vacuum pump having a suction inlet in communication with said auxiliary pump casing, whereby gaseous medium is With drawn from said auxiliary pump casing, the pumping capacity of the vacuum pump being such that the vacuum developed thereby is overcome by the pumping action of the auxiliary pump, and valve means in the suction inlet between the auxiliary pump and vacuum pump, said valve means being openable in response to the operation of the vacuum pump.

References Cited by the Examiner UNITED STATES PATENTS 3,073,249 1/1963 Yokota et al 103-113 FOREIGN PATENTS 556,579 8/ 1932 Germany. 614,571 6/ 1935 Germany.

22,806 3/ 1962 East Germany. 499,220 6/ 1930 Germany.

SAMUEL LEVINE, Primary Examiner.

HENRY F. RADUAZO, Examiner.

Claims

1. A CENTRIFUGAL PUMP ASSEMBLAGE COMPRISING A MAIN PUMP HAVING A CASING, DRIVING SHAFT, A MAIN CENTRIFUGAL IMPELLER MOUNTED ON SAID SHAFT WITHIN THE CASING, A SUCTION INLET AND A DISCHARGE OUTLET COMMUNICATING WITH SAID CASING, AN AUXILIARY PUMP HAVING AN AUXILIARY CASING DISPOSED IN SIDE-BY-SIDE RELATIONSHIP TO THE MAIN PUMP CASING, A COMMON WALL BETWEEN SAID MAIN AND AUXILIARY CASINGS, AN AUXILIARY CENTRIFUGAL IMPELLER, SAID DRIVING SHAFT EXTENDING THROUGH THE AUXILIARY PUMP CASING AND THROUGH SAID COMMON WALL, SAID AUXILIARY IMPELLER BEING MOUNTED ON SAID SHAFT WITHIN SAID AUXILIARY PUMP CASING, SAID COMMON WALL HAVING A CENTRAL SUCTION INLET OPENING THEREIN PROVIDING COMMUNICATION BETWEEN SAID MAIN PUMP CASING AND SAID AUXILIARY PUMP CASING, MEANS ON SAID SHAFT SERVING TO RESTRICT THE CROSS SECTIONAL AREA OF SAID CENTRAL SUCTION INLET OPENING, A DISCHARGE OUTLET FROM SAID AUXILIARY CASING COMMUNICATING WITH THE SUCTION INLET OF THE MAIN PUMP CASING, WHEREBY DENSE FLUID IS DISCHARGED FROM SAID AUXILIARY PUMP CASING TO THE SUCTION INLET OF SAID MAIN PUMP CASING, AND A VACUUM PUMP HAVING A SUCTION INLET IN COMMUNICATION WITH SAID AUXILIARY PUMP CASING, WHEREBY GASEOUS MEDIUM IS WITHDRAWN FROM SAID AUXILIARY PUMP CASING, THE PUMPING CAPACITY OF THE VACUUM PUMP BEING SUCH THAT THE VACUUM DEVELOPED THEREBY IS OVERCOME BY THE PUMPING ACTION OF THE AUXILIARY PUMP.