US2251020A - Bearing and seal - Google Patents

Description

July 29, 1941. MURPHY I 2,251,020

' BEARING AND SEAL Filed Dec. 30, 1938 2 Sheets-Sheet 1 INVENTOR g am/W23 aw v July 29, 1941. D. MURPHY BEARING ANDSEAL Filed D96. :so, 1938 2 Sheets-Sheet 2 R o T N E V m Patented July 29, 1941 UNITED STATE s PATENT OFF-[cs V Claims. My invention relates to pumpbearings. Particularly to bearings for the impellers of centrifugal pumps. The invention consists in im-- provements and refinements in bearing construction and in organization of the bearing in a centrifugal pump. 7 r

Referring to the accompanying drawings, Fig I is a view, partly in side elevation and partly in, vertical section, of a centrifugal pump including a bearing of the invention; Fig. 11 is a fragmentary view, showing portions of the bearing structure, partly in axial section and partly in side elevation, on larger scale; Fig. 111 is a view in front elevation and on still larger scale of a particularly effective sealing device included in the bearing structure; and Fig. IV isa view in medial cross section of such sealing device, the device being shown inposition'for assembly in the struc: ture, with portions of the structure illustrated fragmentarily The exemplary pump consists in a body includingtwo sections l and 2, bolted together and ization of pump bearings, and to a consideration of I the embodiment of the invention herein illustrated. v

At the outset it will be understood that; the shaft 5 and impeller B, collectively considered, comprise a member or unit that in service rotates relatively to'the stationary body of the pump. The bearing is borne by such stationary body for the support of the rotary unit 5, 8. The bearing structure includes a tubular support-3 that provides (or carries) abearing for the impeller 8. At its right hand end the tubular support includes a radially extending portion 311 that-is rigidly secured to the body -of the pump. The support 3 is in effect a hollow cantilever beam that is adapted to carry a bearing at its distal end. i More specifically, the wall forming an involute pump chamber 4 of usual sort. A vaned impeller 8 is mounted for rotation in such chamber, and a shaft 5, profecting at in from th pummstructure, is geared to a suitable motor for driving the impeller. The pump body includes aninlet passage I, extending from above the pump chamber 4 downward. and opening centrally of the impeller vanes through the side wall of such chamber, the side wall including in this case a centrally perforate wearing disk 2| that cooperates with such vanes.

An outlet passage 8 opens tangentially through the peripheral wall of the pump chamber and extends upward to a receiver-chamber 31 included in the delivery line 310 leading from the pump, In service the rapidly rotating impeller draws liquid inward through passage I into the spaces between the vanes of the impeller, whence centrifugal force impelstheliquid radially outward into the outlet passage 8.

The liquid entering the pump is drawn upward through a duct 3| from the supply, and in the line of flow between-the duct 3i and passage 4 I a check-valve is included. The check-valve is arranged in a chamber 33, located above the pump chamber. Further reference to the construction and operation of the pump is unnecessary'to an understanding of this invention, but to the extent that such matters of detail may be-of interest I refer the reader to United States Letters Patent No. 2,179,858, granted to me November 14, 1939. As already mentioned, the present invention concerns the structure and organs against a collar 50 on the'shaft 5 and an inter of the inlet passage I of the pump includes an opening la. opposite to and in axial alignment with the inlet Zia to the pump chamber 4, and

the pump body includes a cylindrical housing portion la extending outward from and in axial alignment with such opening la. The tubular support extends through opening la, and the radial portion 3d at its proximal end is, by means of a sleeve 30 and screws 30a, clamped'rigidly against the wall portion of the pump that surrounds said opening fla. One or more'gaskets 2o insure a sealed union of the parts, with the consequence that liquid is prevented from leak 'ing' fromthe inlet passage '8 of the pump into the housing la. Within the housing la, con-' venientlywithin the sleeve 3D, a bearing is provided for. the shaft 5, and it is manifest from what has been said that such bearing is hydraulically sealed from theliquid flowing through the passage I. The bearing may consist in a conventional ball-bearing 25, held in place,

nal shoulder 84 on the, sleeve 30, by means of a keeper 35. The keeper consists in a flanged block snugly fitting the bore of the sleeve, and

secured in assembly by means of screws 36. The body of the keeper is recessed, and providedwith a packing 38 of felt or the like that serves to prevent the escape of lubricant which in service is supplied to a chamber A within the sleeve.

The shaft 5 extends from the bearing 25 through the tubular support 3, and impeller iis'secured to the inward projecting end of the shaft, as shown in Fig. II. The impeller is provided with a hub 60, which is larger than the hubs usually provided on pump impellers, and

such hub is internally recessedto receive a bearing 8 and a pair of sealing devices It and 15.

1 shall now mm- The integration of the shaft with the impeller is efl'ected by means of a member 6|, which is screwed on and locked to the end of the shaft, and it will be perceived that member 6| is secured over the open end of the hub, say by means of screws 82.

ing la is completely sealed from the liquid being pumped, and in the case oi the bearing within the hub 01' the impeller the only possible avenue through which liquid may enter is the clearance between the tubular support 3 and the periphery of the aperture 611. The sealing device i5 closes such avenue.

While various forms of sealing devices may be used, it is to be understood that the device i 5 is particularly efl'ective. This device consists in a resilient diaphragm il, a centrally perforated, circular diaphragm of sheet metal, which is mounted on and arranged radially oi the tubular support 3. The diaphragm carries a sealing ring l2 at its outer periphery; the sealing ring is held in snug contact with the wall portion of the ima pellet that surrounds aperture 6b; and the inner periphery of the diaphragm is secured and sealed upon the body of the cylindrical support 3. More specifically, the sealing ring i2 is formed in two sections Ho and l2b, as shown in Fig. IV; the

two ring sections are closed and secured upon the periphery of the diaphragm ii, by means of screws i3, and a gasket it; of rubber is interposed between the ring sections, as shown, to provide a liquid-tight union of the ring with the outer periphery of the diaphragm. The inner peripheral edge of the diaphragm is secured and sealed between the companion edges of two sleeves ii and it that are mounted with snug fit on the tubular support 3. The right-hand edge of sleeve i'i abuts against a rigid collar to on the support 3; in making the assembly the sleeve ii is mounted in the position in which it is illustrated on the cylindrical support 3, and

then the sealing device l5 and the sleeve l8 are slipped over the end 'of cylindrical support, and moved into position, as indicated by the arrows in Fig. IV. As presently will appear, the sleeves are tightly secured on the support 3, with the inner edge of the diaphragm ii clamped and sealed between the companion edges oi the sieves. With the diaphragm so assembled on the stationary support 3, the sealing ring I2 is urged and maintained in contact, as at S, with that body portion of the rotary impeller which bounds the opening 6b, through which the support and shaft assembly 3, 5 extends. Thus, it will be understood that the only avenue through which liquid may leak from the'pump into the bearing 9 is closed.

As shown in Fig. II, springs l0 may be arranged to maintain the sealing ring i 2 in the desired contact with the body of the impeller. Additionally, the inherent resilience of the diaphragm cooperates to this end-indeed, in many cases the resilience of the diaphragm will prove adequate without the springs Hi. In order to augment the efiect of the resilience oi the diaphragm, I chamfer or bevel the companion edges of the sleeves I! and i8, and the direction of 1 bevel, as may be perceived in Fig. IV, is such that (when the two sleeves are tightly clamped upon the inner edge of the diaphragm) the body of the diaphragm is flexed, in such manner that the sealing ring I! is more strongly urged and held in snug contact with the wall portion 6a of the impeller."

Other advantages attend the use of my diaphragmatic sealing device, and notable among such advantages is the feature of self-alignment. Those skilled in the art will readily understand this matter of self-alignment, and I need merely remark that the flexible diaphragm H functions in such manner that the sealing ring l2 always remains in snug contact with the body of the rotating impeller.

When the pump is in operation the suction produced by the rotating impeller will act through the clearance 6b upon the diaphragm H, and, under the influence of this suction on the dia phragm, the sealing ring I2 is held all the more snugly against the body portion 6a of the impeller. In fact, so long as the pump is in operation, there is no tendency for liquid to leak from the pump chamber 4 into the bearing chamber B within the impeller hub, rather the tendency is for the rotating impeller to suck lubricant from the bearing chamber into the pump chamber. It is only while the pump is at rest that the sealing device i5 serves to prevent the infiltration of liquid from the pump chamber 4 to the bearing chamber B. And it is important to note that the pressure head of the liquid, normally tending (when the pump is at rest) to destroy the seal provided by the device I5, is neutralized. That is, the pressure of the liquid standing in the discharge line and pump chamber is communicated through theclearance 6b to the right-hand face (Fig. IV) of the diaphragm, and such pressure on the diaphragm tends to shift the ring l2 from sealing contact with the wall portion 6a of the impeller. However, the pressure of the liquid efiective on the right-hand face of the diaphragm is also effective on the left-hand face of ring section i2b. Manifestly, the liquid pressure tending to unseat the ring l2b from wall portion 6a is in large measure neutralized, with the result that the device l5 provides an eifective seal against the infiltration of liquid to housing 60.

In the usual pump, the sealing device IE will prove adequate, but I contemplate that in some cases several sealing devices will be used. As an example I show in Fig. 11 a second sealing device I. The inner peripheral edge of the diaphragm of this second sealing device is clamped between sleeves 22 and 24, the counterparts of sleeves i1 and I8, respectively. And the ring I20 carried at the outer edge of the diaphragm bears, with liquid-sealing contact, upon the inner surface of a cup-shaped bearing retainer 26 provided in the impeller hub 60.

The end of the cylindrical support 3 is threaded, and the assembly of the bearing 9 and sealing devices I, I5 upon such support is secured by means of a single nut 21. That is to say, the nut 21 is tightened against the inner ring of ball-bearing 9, and under the thrust of the nut such ring is pressed inward on the tubular support 3. Abutting upon the left-hand edge of sleeve 24, the ring 9 0 under nut pressure forces sleeves 24, 22, l8, i! into tight edge-toedge assembly, with the inner edges of the diaphragms of scaling devices l4 and I5 clamped and sealed in the manner already described. Manifestly, the structure is easily assembled.

bearing for a pump impeller as close to the impeller as possible, in order to minimize the objectionable tendency of the rotating impeller'to vibrate and of the driveshaft to whip. In my structure the bearing 9 is arranged within the body of the impeller itself; the shaft 5, extending through or across the lower. or innerend of the inlet passage 1, is provided with bear-y ings on each side of such inlet passage, andby virtue of these and other refinements the.objections noted are effectively eliminated.

It will be perceived that the rotary shaft 5 is at-all points in its extent free from frictional contact with the stationary parts of the pump structure, and I call particular attention to the clearance C which is provided between the shaft and the cylindrical wall of the support 3. There is no wear upon the shaft. Not only are the bearings 9 and 25 enclosed and sealed from the liquid being pumped, but the shaft 5 itself is enclosed. The liquid being pumped is excluded from the shaft, and a film of lubricant may be maintained on the surface of the shaft, to inhibit rustingand corrosion. Such features as these,

while valuable in any machine, are particularly valuable in heavy-duty pumps, pumps that work upon liquid including particulate solids,such as the "slip used in potteries.

In all pumps of the sort described herein, it is desirable to provide for the axial adjustment of theimpeller, so that the free side edges of the impeller vanes may be brought to proper position with respect to the side wall 2| of the pumpchamber. Such adjustment of the impeller may be obtained in a variety of ways, and inthis case I effect it by varying the thickness of the gasket 20. That is, the gasket is made up of a plurality of thin gasket rings, and, by

, the adding or removing of such rings, the effective thickness of the gasket maybe increased or decreased. The adjustment of the axial position of not only the impeller, but of the enand hearing aslubricant. The clearance C between shaft 5 and the wall of tubular support 3 provides communication between the well A and the bearing 9 within the hub of the impeller, and thus it is that lubricant introduced to well A is delivered to both of the bearings 9 and 25. The structure provides a single lubricating system for the bearings of the pump, and the devices It and 38 close and seal the system against the escape of lubricant.

The sealing devices l4 and I5 are also lubricated, and graphite has proved to be a good lubricant. Advantageously, the rings I2, I28 of the sealing devices are provided with pockperiods of time all the lubrication that is necsar The, chamber B may be charged with a store of lubricant when the pump is assembled, but such lubricant will be a lighter,- more fluid type than the graphitic-base lubricant used in pockets 32. Of course, the wall of the hub '60 may be provided with an inlet (not shown) for charging the chamber B, but itis deemed needless to prolong this specification with such matters of detail.

Within the-terms and intent of the appended claims various modifications of the structure described lie within the fleldof my invention.

I claim as my invention: 3

l. A hearing structure for the impeller and shaft of a rotary pump including within its body an impeller chamber and an'inlet passage arranged side by side and a port establishing com-' munication therebetween, said pump being adapted to pump heavy liquid including abrasive particles, said bearing structure .including two bearings arranged outward from and on opposite sides of said chamber and passage, one of such bearings being housed within the impeller body, a tubular support secured at one end to the pump body and/extending from the region of its attachment to such body transversely through both said inlet passage and said impeller chamber, and

at its distal end extending into said impeller body and providing support for the bearing therein, said shaft extending through said tubular support and secured adjacent to the distal end thereof to said impeller, and means cooperating with such tubular support and the impeller body for sealing the bearing on the distal end of said tubular support within the impeller body.

2. A bearing structure for the impeller and shaft of a rotary pump that includes an impelelr chamber, inlet and outlet passages, a port in one sidewall of said chamber establishing communication between the chamber and said inlet passage, said impeller carrying vanes adapted to cooperate with saidrperforate side wall of the pump chamber when the pump is in operation;

' said bearing structure including a bearing orets '32 (Figs. III and IV) that open through ganized within the impeller body, and a rigid tubular support arranged to extend from said inlet passage and through said port in the side wall of the impeller chamber of the pump, with the distal end of such support'located within the impeller body and affording support for said bearing, and means providing for the axial adjustment of such tubular support, withthe effect that the impeller and bearing assembly may be adjusted and the most effective relation of the impeller vanes with respect to said perforate side wall of the impeller chamber established and maintained.

3. A pump impeller structure comprising an impeller body including a body portion that extends radially of the axis of the impeller'and includes a central perforation, said radially extending body portion carryingon one side an impeller vane and carrying on opposite side a hollow imperforate-walled hub; a tubular, cantilever-like support extending through the per-- foration in such radially extending body portion ofthe impeller, a bearing borne by the distal-end of-such support within said hub, a drive-shaft extending through said tubular support and integrated to the impeller hub, and a perforate flexible diaphragm secured and sealed at the rim of its perforation to said tubular support and at its outer peripheral edge encompassing the perforati'on in such impeller body portion and engaging such body portion of the impeller in an engagement preventative of liquid flow inward of the hollow hub and toward the bearing within.

4. A pump impeller including a bearing chamber whose walls, otherwise imperforate to liquid, include a port; a tubular cantilever-support ex tending through such port and carrying at its distal end a bearing within such chamber; and means for sealing the hearing within the impeller body, said means comprising a perforate flexible diaphragm secured and sealed at the rim of its perforation to said tubular support and at its outer rim encompassing the periphery of said port and bearing outward of the bearing chamber upon the port-encompassing body portion of the impeller, with the effect that the suction produced by the impeller within a pump in operation is eiiective upon said diaphragm to assist in holding the outer rim of the diaphragm in sealing contact with said port-encompassing body portion of the impeller.

ber whose walls, otherwise imperforate to liquid, include a port; a tubular cantilever-like support extending through such port and carrying at its distal end a hearing within such chamber; and means comprising a perforate flexible diaphragm secured and sealed at the rim of its perforation to said tubular. support and at its outer rim encompassing the periphery of said port and hearing outwardof the bearing chamber upon the port-encompassing body portion of the impeller, with the effect that the suction produced by the impeller within a pump in operation is eflective upon said diaphragm to assist in holding the outer rim of the diaphragm in liquid-excluding contact with said port-encompassing body portion of the impeller, and a second sealing device housed within the bearing chamber in said impeller and arranged between said bearing and said diaphragm in lubricant-confining contact with a rotary portion of the impeller structure. DANIEL MURPHY.

5. A pump impeller including a bearing cham-

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