US1847695A - Centrifugal pump - Google Patents

Description

March 1, 1932. LA BOUR 1,847,695

CENTRIFUGAL PUMP I 2 Sheets-She'et 1 Filed Aug. 5, 1929 March 1, 1932. H. E. LA BOUR CENTRIFUGAL PUMP Filed Aug. 5, 1929 2 Sheets-Sheet 2.

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w j 0 w J M x g x a w y d M /M M m w 7 A i L my a a a Patented Mar. 1, 1932 -UNITED STATES HARRY E. LA ZBCUB, OF ELKHART, INDIANA CENTRIFUGAL PUMP Application filed August 5, 1929. Serial No. 888,575.

This invention relates ingeneral to improvements in centrifugal pumps, particularly of the class disclosed in my prior Patent No. 1,578,236, and has for its principal object the improvement of the efficiency of operation of pumps of this kind.

In centrifugal pumps in which a runner is closely fitted in a c lindrical chamber and revolved therein to draw in liquid or gas,

i or both, through a central inlet port leading to the hub portion of the impeller, this liquid is discharged by centrifugal force from the impeller through a tangentialport or ports in the walls of the casing of the impeller chamber.

The preferred form of the impeller shown in said patent comprises a hub having spokes radiating therefrom and terminating in a ring upon which ring are mounted a plurality of 0 vanes or buckets which are of general rectangular shape. The liquid drawn in through the central portion of the impeller passes radially between the vanes and on opposite sides of the ring which supports them.

As is well understood; by those skilled in the art, this liquid backs up over the inner edge of the rotating vanes, and spills into the cavity or chamber between adjacent vanes, where it forms a whirl. Furthermore, this liquid leaks past the lateral sides of the vane in that space between those sides and the lateral wall-s of the chamber casing. The liquid that so leaks past the sides of the vanes also forms a whirl in these spaces between adjacent ones of the vanes.

This whirling of the liquid which leaks past the lateral edges of the vane forms a seal or labyrinth packing which seals the impeller and serves to close off the space be tween it and the walls of the casing. However, the whirling action caused by the liquid that leaks past the ends of the impeller to form this packing, interferes with the pumping efficiency of the arrangement.

In my present invention, I have improved the efficiency of the'pump by segregating the whirl caused by the leakage of liquids past the lateral sides of the vanes so that those whirls interfere less with the free flow of liquid through the pump. These whirls tend to seal the edges of the impeller a ainst the edges of the pump casing, to there reduce leakage of liquid or gas through t e space between the sides of the impeller and the walls of the casing. By segregation of the whirl produced along the edges of the buckets from the central parts of the buckets a better controlled and more orderly action is secured. The spilling of liquid over the inside edge of the vane of the impeller is retained and employed to entrain air or gas in the liquid, particularily during the priming of the pump. The pump is self-priming and operates on the principle set forth in my copending application, Serial No. 751,210, filed Novembe 21, 1924, to which application reference is here made for a discussion of the operation of the pump in priming itself. In the preferred embodiment of my present invention, I provide a hub having spokes radially' projecting therefrom and terminating in two ring-like members which are disposed on oppositesides of the spokes adjacent the outer end of them. The vanes or buckets of the pump are attached to the two rings, and are disposed radially with respect to the hub portion of the impeller.

The vanes, which are preferably of generally rectangular shape, project outward beyond the outside surfaces of the rings,

thereby forming a series of rectangular pockets, which are closed by the walls of the easm The space between the two rings is entirely open, except for the spaces occupied by the spokes and-the vanes of the pump. Adjacent vanes and the two rings cooperate to form a generally rectangular passageway, through which the main stream of liquid pumped by the pump flows radially outward through the discharge port located in the walls of the casing.

Now, to acquaint those skilled in the art with the teachings of my invention, I have illustrated a preferred embodiment of it in the accompanying drawings, in which:

Figure 1 is an elevation view, partly in section, of a pump casing and impeller;

Figure 2 is a cross-sectional view through 109 the pump casing, taken along the line 2-2 of Figure 1;

Figure 3 is a cross-sectional view through the spoke of the impeller, taken along the line 3-3 of Figure 2.

Figure 4 is a diagrammatic View taken substantially along the line 4-4 of Figure 1 looking in the direction of the arrows, and

Figure 5 is a cross-sectional View of the bearing end of the impeller shaft.

By referring to Figure 1, now, in more detail, it will be apparent that the pump casing 1 and separator (not shown) are of the type shown and described in my copending application Serial No. 374/109, filed June 28, 1929, to which application reference is here made for the details of this construction.

Briefly, however, the intake trap 2 draws liquid in through its port 3, that liquid being strained by suitable strainers disposed within the trap, to remove any solid particles that may be entrained in the liquid. The outlet port 4 of the trap 2 cooperates with the pump casing 1 to form the inlet port of the impeller chamber. This port is shaped as a conical frustum, having an opening opposite the center of the impeller hub.

The walls of thetrap 2, adjacent the impeller chamber are provided with an out-- wardly extending flange 5, the outward surface of which is offset at 6 the outer surface of the offset 6 being tapered or conical to provide a tapered seatin surface and provided with the shoulder extending radial- 1y beyond the tapered seating portion.

The pump casing 1 comprises the round flat back plate member 8 having at its peripheral margin the auxiliary extending cylindrical flange 9. The trap side next the outward end of this flange 9 is provided with the taperlO and flat seating face 11, which register with the taper 6 and flange 7 respectively of the trap to form a joint therebetween.

The washer, 12 which may be of fiber, asbestos or any other preferred gasket material is interposed between the flat surfaces 11 and 7 to make a tightly sealed joint.

The outward face of the flange 7 of the trap member 5 is provided with a ridge 13 and the outward face of the pump casing l with a plurality of bosses 14, these rims and bosses cooperating with the clamp members 15 and bolts 16 to hold the trap on the pump casing and to keep the joint closed by the gasket 12 liquid tight.

'As is brought out in my last above referred to copending application, this form of clamp connection for holding the two sections of the pump casing together is devoid of any drilled flanges through which bolts must be inserted, and therefore the one section of the pump casing is capable of rotation with respect to the other, so that the outlet ports of the pump may be-properly aligned without difiiculty.

The back side wall 8 of the pump casing is provided with a centrally located hub '17, which fits within a split clamping collar 18 to mount the pump casing upon the motor drive bracket.

The central hub portion 17 is also provided with a concentric stufiing box 19, through which the shaft 20 of the impeller is projected, the stufling box being filled with packing material 21 held therein by the packing gland 22 and the gland follower 23 to maintain a liquid tight joint between the back wall of the pump casing and the impeller shaft 20.

If the pump is to be used to pump strong acids and the like, the trap 2, and the pump casing and impeller are preferably constructed of an acid resisting material, so that their contact with the corrosive liquid will not cause rapid deterioration of these parts. If the pump is to be used to circulate non-corrosive liquid, these parts may well be made of cast iron or any other preferred material.

The impeller, which forms the subject matter of the instant invention, comprises the hollow hub portion 30, from which radiate a plurality of spokes 31. As will be best seen in Figure 3, the spokes 31 comprise a web section of generally rectangular area, and two flanges 32, which are also rectangular and located on preferably the back face of the spoke near the outer edges of it.

On the outer end of the spokes 31, I 10- cate two flat rings 33 and 34, these rings being formed integral with the spokes 31 and bosses 32 and being disposed inline with the outward ends of 'the bosses. These two rings 33 and 34 are of substantially rectangular cross-section, as will be best seen in Figure 1, and serve to support the impeller vanes or buckets 35. These vanes are evenly spaced around the rings 33 and 34 and are located radially of the impeller hub, that is, the planes of the vanes intersect each other approximately at the axis of the hub of the impeller. For best results it is essential that these vanes lie in radial planes.

The inner edges 36 of the vanes 35 are preferably but not necessarily flush with the inside edge of the rings 33 and 34, and the lateral edges 37 of the vanes project laterally beyond the outside faces of the rings 33 and 34. The outermost lateral edges of the vanes are thereby brought into juxtaposition with the interior wall 8 of the casing 1 and with the interior face of the wall 5 of the trap, those walls cooperating with adjacent ones of the projecting ends 37 of the vane, and with the rings 33 and .34, respectively, to form a plurality of rectangular pockets or buckets 38, as will be best seen in Figure 4.

Adjacent vanes 35 and the rings 33 and 34 i also form a plurality of rectangular passageways 39 through the central port-ion of the im eller.

en the impeller is running so that the rings 33 and 34 are moving to the left, as seen in Figure 4, the liquid that runs into the impeller chamber through the inlet port 4 is thrown radially outward-from thehub of the impeller, the majority of the liquid traveling through the central rectangular openings 39. A portion of the liquid, how ever, finds its way into the chambers 38 located outside of the rings 33 and 34. Since the outward ends 37 of the vanes 35 do not come in contact with the walls of the impeller chamber, part of the liquid in one of the chambers 38 leaks past the ends of the vane into the chamber immediately following that from which it started. The space between the ends of the vanes and the side walls of the chamber is small and the liquid passing through this restricted opening is given a swirling motion upon its arrival in the following chamber 38 by the motion of the impeller. This turning of the liquid that so leaks past the ends of the vane in effect forms a labyrinth packing which tends to reduce the flow of fluid through the spaces on the side faces of the impeller, that is, between the ends 37 of vanes 35, and the side walls 5 and 8, respectively, of the impeller chamber. In the impeller constructed in the manner just described, the main flow of liquid through the impeller is through the rectangular ports 39, and the whirl produced in the chambers 38 by the leakage of liquid past the ends of the vanes is prevented from entering into the main ports 39 by the rings 33 and 34. The whirl can therefore be usefully employed somewhat like a labyrinth packing to reduce leakage and increase efficiency.

When the impeller is revolving, the liquid carried into the chamber 39 builds up against the back or trailing wall of the chamber, and particularly during priming this liquid will spill over the inside face 36 of this back wall. When the liquid spills over in this manner it forms a whirl in the following chamber 39, that whirl being useful to entrain air into the liquid when the pump is being primed.

The separation of the whirls caused by the leakage of liquids passed the outside ends 37 of the Vane, from the whirl caused by the spilling of liquid over the trailing vane from one chamber into the other, does not adversely affect the usefulness of the whirl caused by this spilling over the vanes.

The outside surface 40 of each vane 35 is likewise spaced a short distance from the interior surface of the flange 9. The leakage through this clearance likewise is reduced by the whirlin or eddyin motion of the liquid in the hue rets or poc ets.

As will be seen in Figure 2, the inner edge 36 and outward edge 40 of the impeller vanes pass by the tangential openings 41 and 42 of the discharge ports 43 and 44 of the pump. These discharge ports are separated by the divlding wall 45, the entire assembly preferably being cast integral with the pump caslng 1 and located entirely within the walls of that casing.

This form of construction is described in detail in my above mentioned copending application. When the pump is being first started, the liquid contained in it is whirled bythe rotation of the impeller and discharged from the vanes 35 through the port 43.

During the whirling of this liquid a certain amount of air or as is entrained in it and discharged from t e pump with the liquid. The discharge port 43 opens into a suitable separator, shown in my above mentioned copending application, in which separator the gas or air is permitted to escape from the liquid and the liquid returned to the impeller chamber through the port 44. The

liquid is circulated and recirculated by this procedure until sufficient vacuum has been built up at the inlet port 4 to raise liquid throu h the inlet pipe and draw the same into t e pump. After suflicient suction has been built up. and liquid delivered to the impeller chamber through the inlet port 4, the vanes 35 of the impeller handle more liquid than the discharge port 43 can carry up from the chamber, and as a result the flow of liquid through the port 44 is reversed and that port serves as an auxiliary discharge port taking part of the liquid from the vanes 35 and dellvering it to the separator or other suitable discharge device. The sealing tendency of the eddies created along the sides reduces slippage of liquid through the clearance, but the spaces lying outside the rings and between pairs of vanes alsoconstitute pumping buckets. They thus perform the dual function of reducing slippage without creating eddies in the main part of the runner and also acting as pumping buckets. The passageways 41 and 42 both open across the full width of the casing so that the aforesaid parts of the buckets freely discharge their contents.

In the preferred embodiment of my invention the impeller, its hub, and shaft are all cast as an integral unit, and while this is the preferred form of the invention, obviously I am not to be limited to such construction. The hub and spokes may be cast as one unit and the rings separately mounted thereon, with the vanes attached to the rings in any preferred manner such as by welding or riveting, or any other preferred type of construction may be used within the teachings of my invention.

In the preferred em dmient, the shaft which is cast integral wit the impeller is supported in a suitable bearing shaft, which bearing shaft in turn is supported in suitable bearings as in the manner shown in my above mentioned copending application.

In the embodiment shown in this copending application, the bearing shaft is provided with a counterbore into which a reduced diameter portion of the impeller shaft is fitted, the two shafts being coupled together by a stud bolt extending through the bearing shaft and threaded into the end of the impeller shaft.

If the impeller is constructed ofan acid resistant alloy, a steel insert may be placed in the end of the shaft to receive the threaded end of the bolt that extends through the hearing shaft to lock the two together. However, this is not essential.

In Figure 5 I have shown the free end of the impeller shaft20, that end being stepped down to the reduced diameter portion 50 in two steps which form the shoulders 51 and 52. The small diameter portion 50 fits into the counterbore in the bearing shaft, that shaft butting against the shoulder 51 to rigidly hold the two shafts against endwise motion.

Within the end of the shaft 20, I have placed the counterbore 53 concentric with the shaft, and drilled a taper pin hole 54 adjacent the inner end of this counterbore. At the upper end of the shaft I have provided the threaded opening 55 into which the threaded bushing 56 is placed with its center coinciding with the center of the shaft. The bushing 56 is preferably a steel bushing having an external thread registering with the internal thread 55 in the shaft 20, and having an internalthread 57 into which the bolt employed to lock the impeller shaft 20 onto the bearing shaft, is registered to hold the two shafts together. The end of the bolt may project through the bushing 56 into the counterbore 53, and by providing a hole in that end of the bolt into which a taper pin projected through the hole 54 is inserted, the bolt may be locked against rotation in the impeller shaft.

This type of construction permits the use of an impeller and shaft constructed wholly of acid resisting material so that all parts of the impeller are'equally resistant to the cor- While I have chosen to show my improved impeller encased in a pump housing of articular design, I have done so by way 0 example only as the impeller may be used in a suitable pump casing of any design without departing from the teachings of the invention. I am not, therefore, to be limited to the specific disclosure shown, as I am aware that many modifications and adaptations can be made.

Having thus complied with the statute and shown and described a preferred embodiment of my invention, what I consider new and desire to have protected by Letters Patent is pointed out in the appended claims.

1. In a pump, a casing having an inlet and an outlet, a runner mounted therein, said runner comprising a hub, a plurality of spokes radiating therefrom, a pair of spaced rings disposed on the outward ends of said spokes, a plurality of vanes supported on said rings radially of said hub and'projecting laterally beyond said rings and communicating at their inner ends with said inlet and at their outer ends with the outlet, and a series of open ended pockets defined by adjacent projecting vanes, said rings and the side walls of said casing, said pockets being in open and free communication with both the inlet and the outlet.

2. In a pump, a casing having an inlet and an outlet, a runner mounted therein, said runner comprisin a hub, aplurality of spokes radiating there rom, a pair of s aced rings disposed on the outward ends 0 said spokes, a pluralit of vanes mounted on said rings radially of said hub andprojecting laterally beyond said rings and communicatof pockets defined by adjacent projecting vanes, said rings, and the side walls of said casing, and a second series of pockets defined by adjacent vanes, said rings and the peripheral wall of said casing, all of the pockets being in open and free communication with both the inlet and the outlet.

3. In a pump, a casing having a tangential discharge port and a central inlet port, an impeller disposed in said casing and rotatable therein to draw liquid into the pump through said inlet port and to discharge it radially through the impeller into said discharge port, vanes on said impeller, means for dividing said vanes into a large central surface with two smaller surfaces disposed on opposite edges thereof, said large surface acting on the radially moving liquid in the pump to discharge it therefrom and said smaller surfaces cooperating with the sidewalls of the casing to seal the im eller in the pump, and being in free communication with the inlet port and the discharge port.

4. In a pump of the class described, the combination of a casing having a channel,

an inlet for the pump, an impeller comprising a shaft, a plurality of spaced rings carried by the shaft and extending into said channel, and a plurality of flat transverse vanes disposed within the channel, said vanes being secured to said rings, adjacent vanes defining buckets between the rings and between each ring and the adjacent Walls of the channel, the channel having a substantially tan- Iw gential outlet through which all of said buckets are adapted to discharge their contents, and all of said buckets being also in free and open communication with the inlet.

5. In a pump of the class described, the

115 combination of a casing having a channel,

an inlet for the pump, an impeller comprising a shaft, a plurality of spaced rings carried by the shaft and extending into said channeL'and a plurality of fiat transverse vanes disposed Within the channel, said vanes being secured to said rings, adjacent vanes defining buckets between the rings and between each ring and the adjacent walls of the channel, the channel having a substantially tangential outlet through which all of said buckets are adapted to discharge their' contents and all of said buckets being also in free and open communication with the inlet, said rings being of a diameter substantially less than the inside diameter of the channel and said buckets communicating at their outer ends beyond the radial extent of said rings,

In witness whereof, I hereunto subscribe my name this 8th day of July, 1929.

HARRY E. LA BOUR.

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