US2164869A - Pump - Google Patents

Description

F. E. BRADY, .JR 2,164,869

July 4, 1939.

4 PUMP Filed March 2, 1938 2 Sheets-Sheet 1 /N VE N TOR FRANC/5 E. BRADY df?,

ATTORNEY July 4, 1939. F. E. BRADY, JR

PUMP

Filed March 2,' 1958 2 sheets-sheet 2 HUI /NVENToR FRANC/s E. BRADY Je.

ATTORNEY Patented July 4, 1939 UNITED STATES lPA'IENT ortica PUMP Francis E. Brady, Jr., Connersville, Ind.

Application March 2,

'i Claims.

This invention relates to liquid pumps and more particularly to pumps that are adaptedto clear themselves from entrapped air or vapor.

The present application is a continuation in part of my prior application Serial No. 116,375 led December` 17, 1936.

One object of the invention is the provision of a lquid pump in which air or vapor is withdrawn from the spaces which are in communi- In cation with a common inlet passage and which exist between adjacent impeller blades of a centrifugal pump, as the impeller rotates, by a stream of liquid that is forced around the end of a blade and into the space between adjacent blades so as to scavenge air from such space, the vapor and liquid being removed together through the discharge passage of the pump.

Another object of the invention is the provision of a pumpl of the character mentioned in which the impeller chamber of the pump is arranged horizontally and is provided with an air or Vapor collecting portion which conducts the air or vapor to the discharge passage So it will not be returned to the impeller spaces.

Another object of the inventionresides in the method of operation of a centrifugal pump adapted to prime itself as above mentioned.

Another object of the invention is the provision of a self-priming pump oi the character gn mentioned and having a priming inlet reservoir which is adapted for connection to a suction pipe and which has a single outlet opening communicating directly with the inlet of the pump, the construction being such that a suitable quantity of liquid is provided in the reservoir so that an eiective pumping action will take place after the pump is started and before the liquid is exhausted from the priming reservoir. The latter is suiiiciently shallow so that air or vapor will be carried out into the pump by the. stream of air which enters the priming reservoir, and when the pump stops the priming reservoir will be full of liquid.

Other objects and advantages of the invention will be apparent from the following description, the appended claims and the accompanying drawings, in whichv Fig. l is a vertical central section through a pump embodying the present invention;

Fig. 2' is a horizontal section on the line 01 Fig. 1;

Fig. 3 is a vertical section on line 3--3 of Fig. 2, with the impeller omitted, l

Fig. 4 is a vertical section on line H or Fig. 5a 2, with the impeller omitted;

1938, Serial No. 193,416

(Cl. B-113) Fig. 5 -is a vertical sectional view of a modlfled form of the invention; and

Fig. 6 is a section on the line 6-6 of Fig. 4.

Referring more particularlyto the drawings by reference numerals, Ill generally designates a pump casing having an inlet passage II and an outlet port I2, the latter providing for substantial tangential discharge from the impeller chamber I3. The discharged fluid moves upwardly through the passage Il into a suitable discharge pipe I5.

Within the impeller chamber I3 whichis preferably of generally volute form is an impeller I1, having a series peller blades I8. The outer portions of these blades preferably extend rearwardly as indicated in Fig. 2. The spaces between adjacent blades all communicate with the common inlet, which is arranged for axfal flow 'of uid in va downward direction as shown. lThe impeller is 'car'- ried by a vertical impeller shaft which is rotatably mounted in suitable bearings 2i and which is driven by a suitable electric motor 22 or other source of power.

The axial inlet II provides the single outlet passage of a priming reservoir 24, which is preferably arranged just above the pump. As shown," the capacity of the priming reservoir is rather large compared with the volume of the-lmpeller chamber of the pump, and the priming chamber moreover, is preferably somewhat wider than it is deep in order that air or vapor will be entrained and carried from the Aupper portions of the priming chamber in the liquid stream ow- 'ing from the suction pipe 26 which extends to a suitable liquid supply, The stream issuing from the pipe 26 impinges on a surface 21 and is thus broken up to more effectively carry along any air or vapor that may be in the upper portion o! the reservoir chamber, carrying thesam along into the inlet passage Il of the pump.

The pump is oi such character as to handle free air or vapor as well as liquid, and is adapted to prime itself, the rotation oi the impeller operating to 4effectively scavenge the air which is trapped between the blades. When the pump of outwardly extending imllll is started, with the priming reservoir 2l full of liquid, and with the pump itself also full of liquid inasmuch as the discharge pipe I5 is at a comparatively high. point, the liquid will be drawn into from the priming chamber, and if the priming chamber 24 is of such capacity that a replenishing stream of liquid will start tol ilow from theJ suction pipe 26 vbefore the pump inlet Il and into, the pump all the liquid empties se `from the priming chamber there will be a conysubstantially equal to the depth tinuous stream of liquid entering the pump, this liquid carrying with itany air or vapor that might remain within the priming chamber until the latter is exhausted of air. Thus the priming chamber is promptly filled up and will be full when the pump stops. However, even if the liquid is drawn up in the suction pipe only part way up to the level of the top of the priming chamber at the moment-the liquid is exhausted from the priming chamber, the suctionwill be maintained and increased until liquid does flow into the priming chamber, sincethe pump is so constructedas to provide a continuous vapor scavenging action by reason of the rotation of the impeller. as will now be described.

As shown in Fig. 2, the wall of the pump casing, starting at a point adjacent the outlet port i2, curves inwardlyand in the direction of rotation and thus provides a surface 3b having a depth periphery, andextending inwardly at a substantial angle to a tangent line so as to direct a stream of liquid in the direction of the arrow A and into the body of air or vapor which is trapped between those blades of the impeller which are adjacent or just beyond the outlet port. This stream of liquid is produced by the rotation of the liquid in the impeller volute and by the channel 3i which is more and more restricted up to the point 32 where the wall of the casing is nearest the periphery of the impeller. The rate of ow of liquid in the circulating or volute passage which receives the fluid from the`various impeller blades may be less than the lineal speed of the impeller periphery at the outlet port but the speed of the liquid is increased by the channel 3i to exceed the lineal speed of the blade as the jet enters the impeller. 'I'he velocity jet or stream of liquid that flows into the space 33, see Fig. 2, breaks through the inner surface of the liquid which may be, for example, at the line indicated by the dash line 3l during the priming operation,v and carries into the vapor or air which lies inwardly of the line 34 so that some of the air or vapor which lies inwardly of the line 34 is mixed with or entrained in the stream of liquid breaking into the vapor space. The entrained vapor or air with the broken up or emulsiled liquid can thus travel together between the casing and the end of the blade which is just in advance of the point 32 of minimum spacing, as the wa1l` of the casing is suitably spacedl from the impellerv periphery just beyond the point of minimum spacing between casing and impeller, so that the velocity jet entering the space 33 is effective in entraining and carrylng some air or vapor outwardly of the impeller and into the circulating passage for discharge through the outlet passage I2. Some other portion of the liquid from the volute chamber will flow into the jet creating pocket or channel 3l as the impeller continues its rotation and operate in the manner just described for further priming eiect until the gas or air is scavenged out of the Pllmll 'I'he air or vapor which is carried outwardly of the periphery of thc impeller flows into the upper portion of the start of the horizontal volute or circulating chamber, which is substantially coextensive in depth with the depth of the impeller periphery throughout the extent of the channel 3l and up to the point 39 somewhat beyond the point 32. At the point 39' the volute chamber is extended upwardly as shown at 39, above the level oi' the top of the en ds of the impeller blades.

of the impeller 'Ihis upward extension continues around to the r,outlet The air or vapor forced or carried out,

4into this portion 39 and is retained in the upper part of the volute and flows circumferentially above the level of the impeller periphery to the outlet I2 without returning back into the center of the impeller.

It will be noted that a stream of liquidventering the channel 3| and supplied to the space 33 is substantially free from entrained or mixed air or vapor, since the stream of liquid entering the channel 3l comes from the lowermost portion of the impeller chamber. Any emulsiication or mixture of gas or air, and liquid that may be present at the start of the impeller chamber will have had the air or vapor substantially separated from the portion of the liquid in the bottom por--` tion of the impeller chamber by the time it reaches the outlet of the pump, it being noted that the discharge of the air or vapor takes place into the outlet passage at a point above the bottom of the chamber and above the location of the channel 3i The self-priming as above described is of extreme simplicity and is one in which the stream or jet of liquid entering the space between adjacent blades carries into a space which is in communication with the outlet and with the beginning of the circulating passage or volute chamber of the pump sothat there will be a substantial ow at this point. It has been found that it requires only a fractional part of a minute of priming operation before the air or vapor will be practically completely scavenged from the pockets between the blades, and all of the air or Vapor will be carried from the priming reservoir 24 into the pump and carried through the pump and discharged through the pipe i5, leaving the pump and the priming chamber both substantially full of liquid. After the pump stops there will-then be an adequate supply of liquid in the pump and in the priming reservoir to insure a high degree of suction and proper operation when the pump is again started.

In pumping very heavy or thick oils and the like it has been found that the scavenging of the vapor and liquid combination from the pump chamberis not as rapid as desired in a construction as just described, and for handling materials of this character the modified form of apparatus as shown in Figs. 5 and 6 may be used. In that apparatus the priming chamber 35i and the pump 35 are similar to those previously described except that an additional return line il@ 'extends from the discharge pipe 3l to a suitable point in the impeller volute spaced a considerable distance from the discharge port 3l so that oil or other similar liquid which is comparatively free from air or vapor is returned back to the impeller chamber and this liquid is then forced into the restricted channel or jet creating pocket 39 and carried inwardly in the direction of rotation between the blades which are adjacent or which have just passed the discharge port 3f?. The pipe 36 is of limiten size so that only a comparatively small portion of the discharged liquid owing from the pump is returned back to the impeller chamber through this pipe. l

While the method and forms of apparatus herein described constitute preferred embodim ts of the invention, it is to be understood that ghe invention is not limited to thisprecise method and these forms of apparatus, and that changes may be made therein without departing' from the scope of the invention which is defined in the appended claims.

What is claimed is:

l. A centrifugal pump comprising a casing providing an inlet passage, an impeller chamber and a peripheral outlet port, an impeller having a series of blades operating in said chamber, said casing having a vwall converging toward the impeller periphery from a point adjacent the end of the outlet port and having an inwardly directed terminal surface directing a liquid stream a substantial distance inwardly into the space between adjacent blades and in the general direction ofjrotation of the impeller, the wall of the casing which defines the outer part of the impeller chamber just beyond said terminal surface in the direction of rotation being located a `substantial distance. outwardly from the periphery of the impeller so that liquid and gas will be forced outwardly of the impeller periphery from said space when said receives said stream.

Y sage, means from a point ing and directed inwardly into the 2. A centrifugal pump comprising a casing providingan inlet passage, an impeller chamber and a peripheral outlet port, an impeller rotatable about a vertical axis and having a series of blades operating in said chamber, said chamber having a circulating passage extending around the impeller to the outlet port, said casing'having a liquid defiecting surface extending from a point adjacent the outlet port for creating a velocity jet of liquid just beyond the outlet port and substantially at the point of minimum spacing between the blades and the casspace between adjacent blades when thefforward end of such space is in free communication with the beginning of said circulating passage and with the inlet passage, said circulating passage having a portion extending upwardly from the periphery of the impeller for conducting gas to said outlet port.

3. A self-priming centrifugal pump comprising a casing having an axial inlet passage adapted for connection to a suction line and having a tangential outlet passage for gas and liquid, an impeller in said casing having fluid impelling blades which drive liquid from the inlet passage to the tangential outlet passage, said casing having-a portion providing a circulating passage extending around the impeller to the outlet pasfor directing a stream of liquid within the casing and in communidischarge passage around the end of a blade and in an inward direction for creating, as the rotor operates, a iet of liquid directed inwardly into the space between adjacent blades and in the general direction of rotation of the blades when such space is in free communication with the inlet passage and the circulating passage to combine vapor and liquid and discharge the same together into said circulating passage, and means holding the gas or vaporl in the circulating passage to prevent its return from the circulating passage to the impeller.

4. A centrifugal pump comprising a casing providing an axial inl't passage, Van impeller chamber and a peripheral outlet port, animpeller having a series of blades operating in said chamber, said casing having a liquid deecting surcation` with the `When such space is in face creating a velocity iet of liquidjust beyond the outlet port and just ahead of the point of the blades and the minimum spacing between casing and directed inwardly into the space between adjacent blades when such space is in communication with the inlet passage, said casing providing an air or vapor receiving chamber in communication with the outlet port and arranged to prevent return of gas or vapor to the center of the pump.

5. A centrifugal pump comp g a casing providing an axial inlet e, a volute chamber and a peripheral outlet port, an impeller having a series of outwardly extending blades providing spaces all communicating with the inlet passage, the casing wall just beyond the outlet port in the direction of rotation providing a velocity jet creating portion at the impeller periphery adapted to direct a iet of liquid inwardly into the space ahead of the blade passing the discharge port for scavenging gas from such space, said volute chamber of the casing being arranged substantially horizontally and having a portion extending' around the impeller and above the top of the ends of the impeller blades.

6. A centrifugal pump comprising a casing providing an axial inlet passage. an impeller chamber and a peripheral outlet port, said impeller chamber having a horisontally arranged circulating passage extending around the impeller to said outlet port, an impeller rotatable about a substantially vertical axis having a series of blades operating in said chamber,'said casing having a liquid deflecting surface creating a velocity jet of liquid just beyond the outlet port and just ahead of the point of minimum spacing between the blades and the'casing vand directed inwardly into the space between adjacent blades free communication with the beginning of the circulating passage.

'7. A centrifugal pump comprising a casing` providing anA axial inlet passage, an impeller chamber and an outlet port, a priming reservoir of substantial capacity arranged entirely above said chamber and adapted. for connection at vits upper end t'o a suction pipe and having at the bottom thereof a single outlet opening communicating only with the inlet passage of the pump, an impeller rotatable on a vertical axis and having a series of blades operating in said impeller chamber and providing spaces allv communicating with thev inlet passage, said casing providing a horizontally arranged circulating passage extending around the impeller to the outlet port and having meansprovided just beyond the outlet passage in the direction of rotation for directing liquid from adjacent the outlet port in the form of a jet inwardly into the space between adjacent blades when such space is in communication with the beginning of the circulating passage, chamber which denes the outer part thereof just beyond said means in the direction of rotation' being' located a substantial distance out- `-wardly from the periphery of the impeller so jet. Y

FRANCIS E. BRADY, Js.

the wall of the impeller e

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