US2448717A - Sealing means for pumping apparatus - Google Patents

Description

P 1948. H. w. JEFFCOCK 2,448,717

SEALING MEANS FOR PUMPING APPARATUS Filed May 1, 1945 3 Sheets-Sheat 1 I v INVENTOIYC.

Sept. 7, 1948. H. w. JEFFCOCK SEALING MEANS FOR PUMPING APPARATUS Filed May 1, 1945 3 Sheets-Sheet 2 INVENTOR- BYO P a ormgs Sept. 7, 1948. H. w. JEFFCOCK 2,443,717

SEALING MEANS FOR PUMPING APPARATUS 3 Sheets-Sheet 3 Filed May 1, 1945 INVENTOR.

(Zfiornqys Patented Sept. 7,

I 2,448,717 SEALIN GJHEAN S FOB PUMPING APPARATUS Howard W. J eflcock, Baldwinsville, N. Y., assignor to Morris Machine, Works, Baldwinsville, N. Y., a corporation of New. York Application May 1, 1945, Serial No. 591,343 8 Claims. (Cl. 103-113) This invention relates to a pumping apparatus and more particularly to a liquid or fluid seal for use in forming a friction joint between the hub of the casing of a centrifugal pump and the shaft whereby the impeller within the casing is rotated and this invention also includes improved means for priming the pump.

One of the objects of this invention is to provide a seal of this character in which fluid under pressure from an external source is caused to flow through the joint between the casing hub and the impeller shaft so as to prevent any leakage of liquid from the casing to the atmosphere.

Another object of this invention is to provide sealing means between the casing and impeller shaft of a centrifugal pump whereby a high velocity fluid flow is maintained through the sealing means and into thepump casing for thepurpose of preventing the passage of any foreign material contained in the fluid being pumped from reaching these fluid sealing means and wearing the same.

A further object of this invention is to provide sealing means of this character in which there is no mechanical contact between the rotating impeller shaft and any member ,of the sealing means, thereby avoiding friction and wear and reducing maintenance cost to a minimum.

An additional object of this invention is to pro- Vide priming means of a novel character which are utilized in connection with the above described fluid sealing means when priming of the pump is required.

In the accompanying drawings: Fig. 1 is a vertical longitudinal section showin one form of this invention embodied in a centrifugal pump in which the driving shaft of the impeller extends through the back wall of the pump casing and the fluid intake of the pump casing is arranged in the front wall of the casing, and the sealing means are combined with prim- Fig. 6 is a vertical longitudinal section showing a. modification of the sealing means between the pump casing and the impeller shaft as compared with the construction shown in Figs. 1 and 5.

Fig. '7 is a vertical cross section taken on the correspondingly numbered line in Fig. 6. x.

In the following description similar characters of reference indicate like parts in the several flgures of the drawings:

-This invention is capable of being used in connection with centrifugal pumps which differ in detailed construction, that form of the pump shown in Figs. 1-4. being an example of one suitable for this purpose and constructed as follows:

ing means whereby the pump may be primedduring its initial operation.

Fig. 2 is a vertical cross section taken on line 2-2, Fig. 1.

Fig, 3 is a fragmentary vertical section taken- V on line 33, Fig. l.

in which the impeller operating shaft extends through the rear wall of the pump casing and the fluidinlet of the casing is also formed in this 'rear'wall.

The numeral l0 represents generally the easing of a centrifugal pump, the interior of which is constructed to form a pumping chamber ll having the form of a volute into the center of which the liquid to be pumped is conducted through an inlet l2 and from the periphery of which the liquid is dischar ed tangentially through a fluid outlet l3.- This casing may be variously constructed, but as shown in Fig. l, the same comprises a front wall It whichcontains the liquid inlet ii, a rear wall I5 having ahub I6 and a peripheral wall l1 connecting the outer edges of the front and rear walls and provided with the tangential liquid outlet l3.

The liquid is drawn from the inlet l2 into the casing and moved circumferentially therein and then discharged through the outlet l3 by an impeller.which may be of any conventional form but as shown in Figs. 1 and 4, the same preferably comprises a central hub l8, 8. rear disk I9 connected with this hub, a front disk 20 having a central opening 2| arranged opposite the fluid inlet l2,'and a plurality of curved blades 22 arranged'between the rear and front impeller disks.

This impeller is rotated from the exterior of the pump casing by means which include a horizontal driving shaft 23 passing through the rear wall l5 and the hub l6 of the pump casing and having its front or inner end connected with the hub of the impeller while its outer or rear part is journalled in a stationary bearing 24 mounted in any suitable manner on the frame 25 of the pumping apparatus.

Rotation of the driving shaft and the impeller connected therewith is effected by power which maybe transmitted thereto in any well known or suitable manner, such as is now commonly employed for this purpose. a

That form of fluid sealing means shown in Figs.

The members which serve to form the several chambers or passages of the'fluid sealing means include an inner cylindrical block 26 arranged in the inner part or the casing hub and having a reduced neck 21 which extends through an open,-

in 28 in the rear wall or the pump casing and an outer head'29 secured to the-outer end of the casing hub by screws 33 and provided with a reduced neck which projects into the-outer end of the casing hub and engages its inner end with the outer end of the inner block 26.

surrounds the impeller driving shaft and is supplied with fluid under pressure by means which include a pipe 33. The pressure fluid may be of any suitable character such as water, oil or the like and may be taken from any available source and delivered under pressure to the pipe- 33 by a pump 34 or other suitable means. The central part of this liquid pressure chamber is constructed inthe form of an inwardly tapering passage or conical nozzle 35 whereby a liquid Jet of annular form is delivered from the pressure chamber 32 around the impeller shaft toward the casing. The supply pipe 33 is connected with the upper part of the casing huband the pressure liquid is carried from the supply pipe to the pressure chamber by an annular distributing chamber 36 which surrounds the pressure chamber and receives the pressure fluid from the supply pipe and from which this fluid is conducted to the pressure chamber by a plurality of passages 31 arranged in an annular row between the distributing chamber and the pressure chamber, as shown in Figs. 1 and 2. The jet of fluid flows from the nozzle 35 through an annular vacuum chamber 38 arranged on the inner side of the pressure chamber. From the central part of this vacuum chamber an annular mixing chamber 39 of restricted or small diameter extends around the impeller driving shaft toward the casing. The inner end oi this mixing, chamber opens at its inner small end into the outer end of an annular diffusing chamber or passage 40 which latter is of inwardly flaring conical form and surrounds the adjacent part of the impeller shaft and opens at its large inner end into the rear part of the pumping chamber within the pump casing.

Between the pressure chamber 32 and nozzle 35 and the head 29 of the casing hub is arranged a liquid collecting chamber or reservoir 4|, the lower part of which communicates with the corresponding part of the vacuum chamber 33 the pressure chamber 32 by a return passage 45. The central part of the collecting-chamber 4| connects with the corresponding part oi the 4 collecting chamber 4| but does not contact the adjacent part of the impeller shaft.

In the preferred construction the several chambers 32, 4| and openings 42, 43 and nozzle 35 are formed in the central part of the head 29 and its neck 3| so as to surround the shaft, the distributing chamber 36 is formed on the periphery of this head and faces the bore of the casing hub and the passages 31 extend radially inthis neck from the distributing chamber to the pressure chamber, and the mixing chamber 39 and diffusing chamber 40 are formed in nozzle 35 by a restricted clearance opening 42 oi. annular form which surrounds the adjacent ing 43 which is formed in the outer wail of the the bore of the block 26 while the vacuum chamber 38 is formed between the opposing inner end of the head 29 and the outer end of the block 26, as shown in Fig. 1.

The bore of the central opening 42 is provided with a plurality of annular grooves 44 which operate in the manner of a labyrinth or baiiie whereby any water leaking from the pressure chamber 32 through the opening #32 to the collecting chamber 4| is churned or turbulated whereby leakage through this opening is reduced to a minimum.

In the operation of these sealing means the fluid which is supplied by the pipe 33 passes into the distributing chamber 36 at a pressure somewhat higher than the pressure of the fluid in the pump casing and thence flows radially inward through the openings 31 into the pressure chamber 32. From this point the liquid flows inwardly through the nozzle 35 in the form of an annular jet and thence into the annular mixing chamber 39, Thereafter, the fluid under pressure passes from the inner end of this mixing chamber into the small outer end of the diffusing chamber 40 and escapes from the large inner end of the latter into the pump casing. A small quantity of the fluid may leak through the restricted bafile passage 42 from the pressure chamber and nozzle into the collecting chamber M which latter is open to the atmosphere due to the clearance space between the periphery of the impeller shaft and the bore of the opening 43 in the head of the casing hub.

The fluid passes at a high velocity but low pressure through the conical nozzle 35 from the pressure chamber 32 to the mixing and diffusing chambers and produces a vacuum in the vacuum chamber 38. The lower part of the collecting chamber 4| is normally connected with the corresponding part of the vacuum chamber 38 by the return passage 45 formed in the head 29 and its neck 3|, as shown in Figs. 1 and 2.

During the normal starting operation of the pump, the stream of fluid discharged from the nozzle 36 tends to draw air in the manner of a venturi from the outer atmosphere successively through the vent passage or port43. the collecting chamber 4| and the leak or baifie opening 42 and then discharge the same with the incoming stream of liquid into the mixing chamber 39 wherein the air and liquid are mixed and forced at a high speed into the diffusion chamber or passage 40 wherein the mixed air and liquid expand and move at a lower speed and become separated as they enter the pump casing. Ii

these sealing means the fluid supplied at relatively low speed andhigh pressure by the pump 34 will enter the large outer endof the nozzle II at high pressure and low speed and leave the same at low pressure and high speed, then pass through the mixing chamber 39 at high speed and low pressure, and then change back to low speed and high pressure upon passing through the diflusion chamber 40 whereby the pressure oi the sealing fluid exceeds the pressure in the casing upon entering the latter and causes a separation of the water and air of the sealing fluid before entering the casin When the pump is fully in operation very little, if any, outward leakage of fluid through the baflle passages 42 occurs into the collecting chamber and no appreciable amount of air, if any, is sucked in from the outer atmosphere after the pump has been completely primed and is operating most efllciently at its fullest capacity.

By these means a high velocity is imparted to the liquid as it flows through the mixing chamber 39 which operates to prevent all foreign material, such as grit and the like, which may be passing through the pump casing, from entering the liquid seal and-causing possible wear of the shaft. Moreover, by maintaining a higher inward fluid pressure through the mixing chamber and diffusing chamber to the pump casing these chambers orpassages are effectively flushed and kept in an open working condition so that a liquid seal is constantly maintained between the pump casing and the impeller shaft-without causing wear on the surfaces of the relatively movable parts.

By rotating the impeller shaft in a stream of liquid which is first subjected to pressure in the mixing chamber. and then permitted to expand in.

the diffusing chamber, an increased iilciency of the jet action on the liquid is obtained as it enters the casing around the impeller shaft.

Means are provided for use in connection with this liquid sealing device whereby air may be withdrawn from the liquid inlet side of the casing for the purpose of priming the pump preparatory to operating the same normally. I v

In general these priming means include an air conduit which connects the liquid inlet side of the pump casing with the fluid collecting chamber 4| of the sealing means so that the air conduit may be either connected with this collecting chamber for producing a pump priming effeet or this air conduit may be out ch from the collecting chamber after the pump has been primed.

This air removing conduit includes an air pipe 46. one end of which is connected with the liquid inlet sideof the pump casing, while its opposite end communicates with a port 41 arranged in the head 29 diametrically opposite the return passage 45. r

The means shown in Figs. 1 and 3 for controlling the connection between the pump casing and the fluid sealing means include the rotary plug 48 of a valve which turns in an'opening 49 in the head of the hub and is provided with a multiple way 50 whereby upon turning this plug into one position, as shown in Fig. 1, the collecting chamber 4| is placed in communication with the return passage 45 and any liquid delivered into the collecting chamber is delivered to the vacuum chamber 38. Upon, however, turning the valve plug 48 into a position in which it connects the collecting chamber 4| with the air port 41 and the return port or passage 45 then the suction etfect of the liquid jet passing inwardly through the nozzle ll into the mixing and diffusing chamhere 39, 40 will not only withdraw any liquid which may have escaped through the baille passage 42 into the collecting chamber but it will also produce a suction eflect through the pipe 46 from the inlet side of the pump to the vacuum chamber II and thereby cause the air contained in the pump casing to be withdrawn until a sunlcient amount of water has entered the casing to prime the pump and produce a normal operation of the same. If desired the valve plug may be turned into a position in which its multiple way 50 cuts on communication between the collecting chamber and vacuum chamber and confines the suction of the latter to the inlet side of the pump 8.

The rotary valve plug 48 may be moved into one or another of the above mentioned positions for either using the priming means in connection with the sealing means or cutting the priming means off from the sealing means. As shown in Fig. ii, this is preferably accomplished by a handle 8| arranged on the exterior of the casing hub and connected with one end of the valve plug so that the latter can be operated manually when required.

In the construction of the pump shown in Fig. 1, the inlet of the pump casing is arranged on the front side thereof, while the hub containing the fluid sealing device is arranged on the rear side of the pump casing, but if desired the front side or wall of the pump casing may be closed, as shown at 52 in Fig. 5, and the fluid inlet 63 of the pump casing containing the fluid sealing means may be mounted on the same side of the pump casing, as shown in this figure. The construction and operation, however, of the liquid sealing means are substantially the same and the description of the construction and operation as'heretofore described with reierence to the construction shown in Fig. 1, is therefore equally applicable to the construction shown in Fig. 5.

If desired this invention, so far as producing a liquid sealing effect between the pump casing and the impeller shaft, may be modified in various ,ways. an example of such modification being shown in Figs. 6 and 7 and constructed as follows:

The numeral 54 represents an inwardly flaring diflusing passage or chamber which surrounds the impeller shaft and opens at its large inner end into the interior of the pump casing. At its outer small end this diflusing chamber communicates with the inner end of a reduced mixing or concentrating chamber 5! which surrounds the adjacent part of the impeller shaft and which has its outer end communicating with an annular vacuum chamber 56 surrounding the adjacent part of the impeller shaft. 1

An annular jet of water under a pressure higher than the pressure in the pumpcasing is delivered into the outer end of the concentrating or mixing chamber through an annular inwardly tapering nozzle or passage 51 which receives water from an annular water or fluid pressure the pressure chamber N is arranged a reservoir or collecting chamber 59 which communicates 'with the outer atmosphere through a vent pasinner side communicates with the vacuum chamber 56 adjacent to the small end of the nozzle 51 by means of a leak or clearance opening Bl which surrounds the adjacent part of the impeller shaft, said openings 80, BI being larger in diameter than the respective parts of the impeller shaft so that the latter does not contact the bores of said opening.

In this construction the liquid pressure chamber 58 is formed partly in a block 62 arranged in the inner part of the hub i6 of the pump casing and partly in the head 63 of this hub and the conical nozzle 51 is formed between the outer end of the block 62 and the inner end of the head 63.

. 1 In this construction that part of the impeller shaft 64 arranged within the clearance Opening BI is somewhat enlarged and at the Junction between this enlargement and the adjacent inner part of the impeller shaft the latter is made of inwardly tapering conical form, as shown at 65, corresponding to an inwardly tapering surface 86 on the adjacent part of the'block 62 and thus produces the annular vacuum chamber 56.

The block 62 is provided with a radial passage Figs. 6 and '7 the water or other fluid, which is supplied at a pressure somewhat higher than the pressure in the pump casing, passes through the radial opening 6'! in the block 62 and into the fluid pressure chamber 58. From the latterthe fluid passes inwardly from the outer large part of the nozzle 51 to the small end thereof and into the vacuum chamber 56. From the latter this liquid flows successively through the small mixing chamber 55 and thence through the flaring diffusing chamber or passage-54 into the pump casing. While the liquid is thus flowing from the nozzle through the vacuum chamber 56. mixing chamber 55 and diffusing chamber 54, an inward suction or venturi effect is produced on the fluid received from the pressure chamber 58 and also toward the casing may vary considerably and depends greatly on the vacuum which is to be formed in the collecting chamber H or 59 for some particular installation. Generally the inward pressure of the sealing fluid would be from three to five times the pressure in the pump casing, although in actual practice inward delivery of the fluid through the sealing means and around the shaft at a pressure of 60 lbs. as against a pressure of 40 lbs. in the pump casing has been found satisfactory in some instances.

In the operation of these sealing means a high velocity fluid flow is maintained through the sealing means and into the pump casing, thereby preventing any foreign materials which may enter the pump casing from reaching the sealing means and possibly wearing the same and the shaft.

The several forms of this invention, as shown anddescribed, are comparatively simple in contively low cost. the same operate eiflciently and are not liable to get out of order, thereby enabling the pump to be maintained in an operative condition without requiring an undue amount of attention.

I claim as my invention:

1. A sealing means for a pumping apparatus comprising a casing having a fluid inlet, a fluid outlet and a hub in a wall thereof, a rotatable impeller arranged in the casing and a shaft for driving the impeller extending through the hub; said sealing means including an inwardly tapering conical nozzle surrounding said shaft and operating to change the fluid from a relatively high 5 pressure and low speed to a low pressure and high speed, and an inwardly flaring conical diffusion chamber which surrounds said shaft and has its small outer end communicating with the small inner end of said nozzle and its large inner end commumcating with said casing and operates to change the fluid from a low pressure and high 7 speed to a low speed and high pressure upon entering said casing.

2. A sealing means for a pumping apparatus comprising a casing having a fluid inlet, a fluid outlet and a hub in a wall thereof, a rotatable impeller arranged in the casing and a shaft for driving the impeller extending through the hub; said sealing means including an inwardly tapering conical nozzle surrounding said shaft and operating to receive fluid under relatively high pressure and low speed and deliver the same inwardly along said shaft at a high speed and low pressure, an air and liquid mixing chamber of relatively small diameter which surrounds said shaft and has its outer end communicating with the small inner end of said nozzle and operates to conduct liquid and air inwardly at high speed and low pressure, and an inwardly flaring diffusion chamber which surrounds said shaft and has its small outer end communicating with the inner end of said mixing chamber and its large inner end communicating with said casing and in which the air and water separate and move at low speed and high pressure to said casing.

3. A sealing means for a pumping apparatus comprising a casing having a fluid inlet, a fluid outlet and a hub in a wallthereof, a rotatable impeller arranged in the casing and a shaft for driving the impeller extending through the hub; said sealing means including an inwardly tapering conical nozzle surrounding said shaft and operating to receive fluid under relatively high pressure and low speed and deliver the same inwardly along said shaft at a high speed and low pressure, a mixing chamber of relatively small diameter which surrounds said shaft and has its outer end communicating with the small inner end of said nozzle and operates to conduct liquid and air inwardly at high speed and low pressure, an inwardly flaring-diffusion chamber which sur rounds said shaft and has its small outer end communicating with the inner end of said mixing chamber and its large inner end communicating with said casing and in which the air and liquid separate and move at low speed and high pressure to said casing, and a vacuum chamber communicating with said mixing chamber.

4. A sealing means for a pumping apparatus comprising a casing having a fluid inlet, a fluid outlet and a hub in a wall thereof, a rotatable impeller arranged in the casing and a shaft for driving the impeller extending through the hub; said sealing means including an inwardly taperstruction and capable of being produced at rela- 15 ing conical nozzle surrounding said shaft and opsaid mixing chamber and its large inner end communicating with said casing and in which the liquid and water separate and move at decreasing speed and increasing pressure, a vacuum chamber communicating with said mixing chamher, and a collecting chamber surrounding the shaft on the outer side of said nozzle and communicating with said vacuum chamber.

5. A sealingmeans for a pumping apparatus comprising a casing having a fluid inlet, a fluid outlet and a hub in a wall thereof, a rotatable impeller arranged in the casing and a shaft for driving the impeller extending through the hub: said sealing means including an inwardly tapering conical nozzle surrounding said shaft and operating to change the fluid from a relatively high pressure and low speed to a low pressur and high speed, a mixing chamber of relatively small diameter which surrounds said shaft and has its outer end communicating with the small inner end of said nozzle and operates to conduct liquid and air inwardly at high speed and low pressure, an inwardly flaring diffusion chamber; which surrounds said shaft and has its small outer end communicating with the inner end of said mixing chamber and its large inner end communicating with said casing and in which the air and liquid separate and moveat decreasing speed and increasing pressure, a vacuum chamber communicating with said mixing chamber, a collectin chamber surrounding the shaft on the outer side of said nozzle, and valve means for establishing or cutting off communication between said collecting chamber and said vacuum chamber.

6. A sealing means for pumping apparatus comprising a' casing having a fluid inlet, a fluid outlet and a hub in a wall thereof, a rotatable impeller in the casing, and a shaft for driving the means surrounding said shaft and operating to conduct fluid toward said casing at relatively increasing pressure and decreasing velocity inwardly along said shaft into said casing, and means forpriming the pumping apparatus including a conduit communicating with the inlet of said casing and with the small inner end of said sealing means.

7. A sealing means, for a pumping apparatus comprising a casing having a fluid inlet, a fluid outlet and a hub in a wall thereof, a rotatable impeller in the casing, and a shaft for driving the impeller extending through the hub; said sealing means including an inwardly tapering conical nozzle surrounding said shaft and operating to conduct fluid toward said casing at increasing pressure and decreasing speed, an inwardly flaring diffusion chamber surrounding said shaft and having its small outer end communicating with the small inner end of said nozzle and its large inner end communicating with said casing and adapted to conduct air and liquid under increasing pressure and decreasing'velocity from said nozzle to said casing. means for priming the pumping apparatus including a conduit communicating with said casing and with the small inner end of said nozzle and the small outer end of said diffusion chamber, and valve means for opening and closing said conduit.

8.A sealing means for a pumping apparatus comprising a casing having a fluid inlet, a fluid outlet and a hub in a wall thereof, a rotatable impeller in the casing, and a shaft for driving the impeller extending through the hub; said sealing means surrounding said shaft and operating to conduct fluid along said shaft into said casin and means for priming the pumping apparatus including a conduit communicating with the said casing and with said sealing means.

HOWARD W. JEFFCOCK.

aEEEaENcEs crr n file of this patent:

UNITED STATES PATENTS Number Name Date 2,331,841 Walker cm. 12, 1943 impeller extending through the hub; said sealing 2,386,898 Karassik Och-l6, 1945

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