US3194166A - Pumping plants - Google Patents

Description

July 13, 1965 G. NEIDL 3,194,166

PUMPING PLANTS Filed March 21, 1963 4 Sheets-Sheet 1 F/G. f

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PUMPING PLANTS Filed Magch 2l, 1965 4 Sheets-Sheet 2 .Madam To 6 esfzrn July 13, 1965 G. NEIDL 3,194,166

PUMPING PLANTS Filed March 2l, 1965 4 Sheets-Sheet 5 /Nrfwrop l l Georg /F/L 356 ,/Mesm, 7ans: Meien:

July 13, 1965 G. NEIDL. 3,194,166

PUMPING PLANTS Filed March 2l, 1963 4 Sheets-Sheet 4 360 357 /NVENTOP Geary /Vf/.L

United States Patent PUMPING PLANTS Georg Neidl, Matsehils, Tresen, Furstentum, Liechtenstein Filed Mar. 21, 1963, Ser. No. 267,390 Claims priority, application Germany, Mar. 23, 1962,

4 Claims. (Cl. 1025-87) This invention relates to a pumping plantwherein, preferably for purposes of the submerged mounting of the entire pump, the rotor of the electrometer driving the pump body is suspended inside the stator space.k

The invention consists in that the stator containing the electric windings is arranged together with thekwindh ings inside the casing in a water-tight manner, andthat further the bearing clearance of the top bearing, the clearance between the internal circumference of the stator and the external circumference of the rotor, and nally an annular cavity below the bottom bearing are all designed to be open towards the bottom, in such a manner that when the pump is sunk vertically into the liquid, to be let down to a prescribed maximum depth, under the action of the water pressure the air present in the said spaces is only compressed to such an extent that merely a part of the cavity below the bottom bearing is iilled withthe entering liquid.

The plant may be provided with an oblique disc pump in which, preferably for purposes of installing the whole pump under water, the stator is arranged inside the casing in a water-tight manner. In such a pump circumferential toothing is provided on the disc and a groove arrangement is provided on the internal periphery of the pump casing. However, an oblique pump disc may be used without the provision of teeth on the circumference of the disc or of grooves on the internalperiphery of the casing.

As an improvement toA and further development of the present invention, mass-produced electromotors are used which are inserted, with the interposition of an intermediate piece, between the casing of the electromotor and the casing of thepoblique disc pump. n

Further details of the invention are described in more detail with reference to the accompanying drawing,y in which:

FIGURE l is a vertical section through an underwater pump with discharge pipes which are kguided upwards around the casing of the pump; i v

FIGURE 2 is a top view of the pump according toy FIGURE 1 drawn to a reduced scale;

FIGURE 3 is a fragmentary View of a cavity, arranged below the bottom bearing of the pump, in which water FIGURE 7 is a perspective view of the pumping plant shown in FIG. 1; f

FIGURE 8 is a vertical section through a further modiice tied pumping plant; and

FIGURE 9 is again a vertical section, drawn to an enlarged scale through the upper suspension bearing of the pump shaft of the apparatus of FIGURE 8. y

In the embodiment shown in FIGURES 1 to 3 the rotor 300 of an alternating current motor is designed as a. short-circuit armature or squirrel-cage rotor. The rotor 300 has at its top andeits bottom a respective shaft stub 301, 302. The shaft stub 301 is mounted in a roller bearing 303, which has to take the actualweight of the armature 300 and the two shaft stumps and in addition ysupports the upper shaft stump 301 in the radial direction. At the upper end of the shaft stub 301 there is provided a journal 304 of smaller diameter, which is mounted in the roller bearing 303.

kThe rotor 300 is surrounded by a stator 30S, which is inserted inside the motor casing 307 by means of pressure rings 306. The windings 308 ofthe stator are connected with the stator by way of ties 309.

- .Themotor casing 307 is according to the invention, longitudinaly extended towards the top and the bottom, the free space between the ystator windings 308 and the internal surface of thecasing 307 being yoccupied by a liller material 310, which solidiies after being poured in and encloses the stator in a water-tight and airtight manner inside the casing. The pouring of this iiller material is preferably rst carried out from above. Then after cooling the casing 307 is rotated through and the corresponding cavity now at the top is likewise lled with the filler material.

The upper cover 311 is then screwed onto the casing, this cover having a sleeve 312 which ts so closely against the stator 308 and the shaft stub 301 that only a small clearance is left between theinternal face of the sleeve 312 and the shaft stub 301. On the other hand a small space must be provided between the upper end of the rotor 300 and the lower end face of the sleeve 312, in order that the rotating armature does not rub. Further the cover 311 is so designed that it encloses the roller bearing 303 as closely as possible so that the air space caused by the roller bearing is also small.

Onto the upper cover 311 is screwed a further domed cover 313 whose domed part 314 houses a terminal box with ythe terminals for the electric cable 315. On the domed cover there are provided eyes 316 for suspending the machine on lowering cables. f In the lower part of the casing 307 there is provided th-e lower cover 316 which is likewise equipped with a sleeve 317, which encloses the lower stub 302. The sleeve 317 has in' the upper part a bush 318, which surrounds the lower shaft stub 302 and thus supports it.

The lower end ofthe lower shaft stub 302 has oblique'- ly xed to it a pump-disc body 319. c On the casing 320 there are provided, diametrically opposite one another, radially directed outlet connections 321 from which by-pass discharge pipes 322 arey guided upwards, these pipes combining above the machiney casing 307 to vform a pressure manifold 323.

The sleeve 317'is welded below the bush 318 to form a cavity 324, through which the lower shaft stub 302 is guided. i The inner generatrices of the two discharge connections 321 located at the upper culmination point are in alignment with the lower edge 325 of the cavity 324. The cavity 324 is formed in this Way that its diameter aie/glee :'i d inside the sleeve 317 is greater than the diameter c of the lower shaft stub 302.

In order that, when the machine is placed in operation, the rotor together with the pump disc and the shaft stubs can take up a position symmetrically to the stator 305 inside the developing field of force, it may be advisable to design the roller bearing 303 not simultaneously as a thrust bearing, so that upon stoppage of the machine the lower end face of the rotor 300 lies on the upper end face of the sleeve 317. In this case, upon starting of the machine, the rotor 300 is attracted into the rotary field of the stator 305 and hence upwards, so that the rotor is lifted away from the end face of the lower sleeve 317.

If, according to the invention, the whole system is immersed in the fluid to be pumped, this fluid being pure water, sewage, sludge or any other desired viscous substance, then the air present in the machine casing 320 can escape via the two discharge connections 321 and the discharge pipes 322 (shown in dotted lines) into the coinmon, vertical collecting pipe 323. Hence the level of the material being pumped is theoretically fixed at the level of the edge 325. According to the depth of sinking of the pumping plant and hence according to the extent of the excess pressure, the water level 326 will rise within the cavity 324, as shown in FIGURE 3, and by selecting the size of the individual air spaces `one can achieve the result that with a maximum immersion depth, there is still an air space below the lower end face of the bush 313, so that the bush is not surrounded by fluid.

These conditions will be explained in more detail hereinafter by means of a numerical example:

Let it be assumed that the external diameter a of the rotor 300 amounts to 120 mm., whilst the internal diameter b of the stator 305 amounts to 121 mm. Then there is present between the rotor 300 and the stator 305 an air space of 0.5 mm. The length of the armature 300 is shown in FIGURE 1 at e and should be 200 mm. The diameter of the lower shaft stub 302 is designated c and should amount to 3,0 mm., whilst the internal diameter d of the cavity 325 is 40 mm. The length of the cavity 325 is designated f and is 150 mm.

Let it be assumed further that the air volume of the free space inside the roller bearing 303 including the volume of the annular gap between the shaft stub 301 and the cover 311 Vamounts to 10 cc. The air volume of the annular space between the armature and the stator is calculated as follows: The surface area of the entire stator cavity is calculated according to the formula 1r/4-1212 with a diameter of 121 mm. -at 115 cm2. From this must be deducted the surface area of the rotor which with a diameter of 120 mm. amounts to 113.1 cm2. The difference between the said surface areas gives the surface area of the annular gap=1.9 cm2. The volume of the annular gap then amounts, with the length e of 200 mm., to 1.920=38 cc.

The surface area of the cavity 324 is caljlated from Ithe 12.5 cm.2 surface area corresponding tol diameter :1:40 mm. minus the surface area of the shaft stub corresponding to its diameter :30 mm. and amounting to7.l cm?. The difference inthe surface areas at 5.4 cm.2 gives the cross-section of the annular cavity 324, the volume of which with f=150 mm. length is approximately 81 cc.

If the whole unit is immersed in the fiuid, then with an immersion depth of the magnitude zero, with respect to the lower'edge 325, the fluid level of the immersion material would be at the lower level 325. On the other hand, if the unit is immersed to a depth of m., then the immersed material, with an excess pressure of 10 m. head of liquid, and with an assumed specific weight of the immersion material of 1, penetrates via the annular surface 325 into the cavity 324 designated as a buffer chamber.

In .order to calculate this depth of penetration, we will start for the sake of simplification from a isothermal compression, for which the following formula applies: p1V1=p2-V2- Here p1 designates the pressure before the immersion=l.0 absolute pressure in atmospheres, whilst p2=2.0 absolute pressure in atmospheres, i.e. the iiuid pressure after immersion which acts in an upward direction against the annular surface 325 into the buffer space 324. V1 constitutes 4the sum of three volumes, i.e., the air space or volume of the bearing 303:10 cc., that of the gap between stator and rotor amounting to 38 cc. and that of the buffer chamber 324:81 cc. Finally V2 designates the reduced volume which occurs as a result of the pressure p2. Accordingly the following equation applies after the immersion:

Thus V2=130/2 or V2=65 cc.

Naturally the volume of the roller bearing 303 remains unchanged at l() cc. as also does the stator gap with 38 cc. This results in a volume fof 48 cc. As, however, according to the calculation, the total volume still only amounts to 65 cc., then the free volume in the buffer chamber 3 24is reduced 'to 65 minus 48, i.e. 17 cc.,.so that, as shown in FIGURE 3, water level 326 has risen in the annular cavity 324 to such an extent that a volume of 17 cc. remains between the lower face of the bush 318 and the water level 326. As the annular chamber 324 has a cross-section of 5.4 cc., the level h according to FIGURE 3 is reduced to l7+5.4=approximately 3 cm., whilst'in the first instance according to FIGURE 1, the level h amounted to 15 cm. In this calculation the annular gap between the lower shaft stub 302 and the bush 318 has been disregarded for the sake of simplicity.

It can be seen from the above that at an immersion depth of 10 m. the water cannot penetrate into the elec-v tromotor at all, because the electromotor is a filled motor with respect to its stator and rotor and secondly the lower bush 31S is not even in contact with the water.

The intermediate ring 327 designated in FIGURE 1 constitutes a simple'inventive means for lengthening the cavity 324, in order to obtain suitably prescribed immersion depths with certainty so that the water level does not reach the lower annular surface of the bush 318. The dimension f can thus be increased within certain limits. By this means notonly the bush 318 but also the entire electromotor can be kept dry. One can also increase the diameter d of the cavity 324 in relation to thel diameter c of the lower shaft stub 302 and have thus possibilities of increasing the buffer-chamber volume in both directions.

In order to keep the unit as light as possible, the sleeve 312 of the cover 311 can, as shown in FIGURE 6, be provided with cavities 328.

According to the embodiment of FIGURE 4 there are provided instead of the discharge pipes 322.0f FIGURE 1, the design of the pumping plant being otherwise the same, apertures 329 in the upper terminal wall of thepump casing 320, so that the fluid sucked up enters through these apertures an annular chamber`330 provided outside the motor casing 307, this chamber being formed by the provision of a hood 331 round the motor casing 307 tapering upwardly and opening into the discharge pipe 323. In this embodiment the current cable 315 is guided through a bore inthe hood and protected from penetration of water by a packing 332. The carrying eyes 333 are in this embodiment secured to the hood 331.

As shown in the sectional view of FIGURE 5, not only two diametrically opposite apertures 329, but also additional openings 334 are provided in the pump-casing cover 320. Finally, in order to have a particularly large transition cross-section, an annular aperture 335 may be provided in the upper casing cover as illustrated in dotted lines. The hood 331 is secured by means of a flange 336 to the pump casing 320.

invention can also be used for pumps of normal design,

that is to say for pumps wherein the pump rotor is not an oblique disc pump but, for example, a centrifugal pump impeller.

The filler mass 310 as shown in FIGURE 1 can also be used at the same time to till the intermediate spaces between the individual groups of windings 3dS. In this connection it may be expedient to use for the ller mass a material which has good heat conductivity in order to divert suliciently outwardly the joulean heat generated.

Although the lower bush 31S is, according to the invention, not wetted by the water to be pumped, it may nevertheless be advantageous in certain cases to provide a stuffing-box packing on this bush 318, so that a waterand moisture-repellent closure is obtained. y yThe unit according to the invention is, in 'contradistinction to known constructions, in full equilibrium, i.e. the unit never hangs askew, which is due particularly to the fact that the outflow of the liquid being pumped takes place by way of fully symmetrical outlet'openings and outlet pipes. i y

rFrom the perspective view in FIGURE 7 one can particularly clearly see the method of connecting the electric cable 315 and the form of the whole unit.

According to the embodiment shown iny FIGURES 8 and 9 the mass-produced electromotor 35!) is simply connected to the oblique disc pump 351 with the aid of an intermediate piece 352, without any special adaptation of the casing of the electromotor. The lower cover 353 is Iscrewed onto the flange 355 of the intermediate piece by anchor screws 354. Between the lower motor cover 353 and the upper side 356 of the intermediate piece 352 there is preferably poured an insulating composition 357 and this intermediate space is thus lled and therefore has as little air as possible particularly in the vicinity of the rotating parts of the machine shaft 358. The intermediate piece 352 has an annular space 359, in which the air is compressed by penetration of water when the pump is lowered.

If such a plant is used for example as a dredger for pumping out, then the machines at the end of the dredging operation, usually therefore at nightfall, are lifted out of the water whilst the plant idles. Accordingly the annular space 359 can lill with fresh air again. It is different in a plant, for example, which is intended to be used as a sewage-pumping mechanism. This is sunk permanently in the sewage sump. In such a case, in modification of the inventive idea, on reaching of a certain maximum sewage level inthe sewagesump, the circulating pump is automatically switched on exactly as when using normal pumps. On the other hand the stopping water level, that is to say the water level at which the machine automatically stops pumping, should not generally fall below the lowest edge 360 of the machine, because otherwise air is sucked through the machine in an undesirable manner. Generally such a machine is then switched olf when the sewage just covers the lower part of the pump casing. This ensures that the pump contains no air pockets when the water level sinks. Otherwise the machine would begin to spin and accordingly cease or almost cease to pump.

During tests on the test stand it has been ascertained that the machine according to the invention pumps completely empty, that is to say right up to its lowermost edge, Without spinning. This undesirable spinning only takes place when the water level sinks below the bottom edge 360. In order to avoid this, there is used according to the invention a stopping electrode or a stopping float arrangement which switches on a retarding relay as soon as the water level has sunk to the upper edge 361 of the circulating pump. This relay establishes a slowing-down time of the circulating pump which can be set by hand. During this slowing-down time, the water level sinks to the lower yedge 360 of the machine. At this moment frothing occurs between the sewage and the air, i.e. air enters the machine casing 362. Only then does the machine stop after release of the relay.

By using such a retarding relay one ensures that the circulating pump and hence also the air space 359 can again fill with fresh air. n

The air space inside the electrornotor is, in the design yaccording to the invention, so small that even when water does penetrate this small air space inside the electromotor, this water is evaporated on account of its small quantity in the shortest possible time by the heat produced by the running electromotor. The electromotor then runs without disturbance, except that its power factor, is increased or its elhciency somewhat reduced. This however is of `no importance in coarse underwater operation, e.g., in dredgers, for pumping out ponds and the like.

lf the motor is switched oif and remains under water, then the water vapor condenses and water again penetrates the electromotor. At the next switching on the abovedescribed operation is repeated.

lf the motor is taken out of the water after being switched off, then the water runs out of the motor again. In the latest electromotors the lacquerfor the windings and other parts of the electrornotor is of such high quality that penetration of water is to a certain extent harmless. Therefore, owing to the small extent of the empty spaces located in the motor, the penetration ofthe water is of no importance. ln this connection the water by no means needs to penetrate so far into the motor that the latter is filled right up to the top with water. Thus is may happen that only as much water penetrates from below into the electromotor as to Ilill the latter half or three-quarters with water. Even when, through the intensive external cooling of the electromotor immersed in the water or sewage, the water which has penetrated the electromotor does not evaporate, it is only a question of suchsmall quantities that the machine continues to work without disturbance. Heat is consumed bythe evaporation of the water or liquid in the filled electromotor. This favors at the same time internal cooling of the machine in an advantageous manner. The ywater vapor formed Linside the lled motor may, in accordance with the inventive idea, be considered las a gas under pressure, which offers resistance to the penetration of the water from below. If condensation of the water vapor to water again occurs through cooling of the motor owing to a fairly long switching-ott period, then the evaporation procedure is repeated yafter the electromotor is switched on.

I rclaim: f l. A totally submersible pumping plant comprising first housing means centered on a vertical axis; an electromotor in said lirst housing means having a downwardly extending vertical shaft journaled coaxially therein and carrying an armature received with peripheral clearance in said iirst housing means;

an impeller cantilever mounted at a lower extremity of said shaft for rotation about said axis thereby;

second housing means surrounding said impeller and forming a downwardly open pumping chamber' therearound, said second housing means being formed with at least one generally radial outlet communicating with said chamber;

means forming an air compartment interconnecting said clearance and said chamber, said compartment constituting substantially the sole fluid communication with said clearance;

and bearing means interposed between said iirst housing means and said shaft at the junction between said compartment and said clearance, the air-enclosing volumes of said clearance and said compartment beanotarse ing so selected that, upon submersion of said pumping plant in an upright condition, the air within said clearance and said compartment is compressed and prevents entry of liquid into said iirst housing means through said compressor beyond said bearing means.

2. A totally submersible pumping plant comprising:

irst housing means centered on a vertical axis;

an electromotor spacedly disposed in said tirst housing means and forming an annular conduit chamber therewith, said electromotor having a downwardly extending vertical shaft journaled coaxially in said Iirst housing means and carrying an armature received with peripheral clearance;

an impeller cantilever mounted at a lower extremity of said shaft for rotation about said axis thereby;

second housing means surrounding said impeller and forming a downwardly open pumping chamber therearound, said second housing means being formed with at least one generally radial outlet communicating between said pumping chamber and said conduit chamber;

means forming an air compartment interconnecting said clearance and said pumping chamber, said compartment constituting substantially the sole fluid communication with said clearance;

and bearing means interposed between said irst housing means and said shaft at the junction between said compartment and said clearance, the air-enclosing volumes of said clearance and said compartment being so selected that, upon submersion of said pumping plant in an upright condition, the air within said clearance and said compartment is compressed and prevents entry of liquid into said first housing means through said compartment beyond said bearing means.

3. A totally submersible pumping plant comprising:

iirst housing means centered on a vertical axis;

an electromotor in said irst housing means having a downwardly extending vertical shaft journaled caxially therein and carrying an armature received with peripheral clearance in said iirst housing means;

an impeller disk cantilever mounted at a lower extremity of said shaft at an angle thereto for rotation about said axis thereby and generation of a generally cylindrical surface by the periphery of said disk.

second housing means surrounding said impeller disk and forming a downwardly open substantially cylindrical pumping chamber therearound, said second housing means being formed with at least one generally radial outlet communicating with said chamber;

means forming an air compartment interconnecting said lclearance and said chamber, said compartment constituting substantially the sole uid communication with said clearance;

and bearing means interposed between said lirst housing means and said shaft at the junction between said compartment and said clearance, the air-enclosing volumes of said clearance and said compartment being so selected that, upon submersion of said pumping plant in an upright condition, the air within said clearance and said compartment is compressed and prevents entry of liquid into said rst housing means through said compartment beyond said bearing means.

4. A totally submersible pumping plant comprising:

first housing means centered on a vertical axis;

an electromotor spacedly disposed in said iirst housing means and forming an annular conduit chamber therewith, said electromotorV having a downwardly extending vertical shaft journaled coaxially in said irst housing means and carrying an armature received with peripheral clearance;

an impeller disk cantilever mounted at a lower extremity of said shaft at an angle thereto for rotation about said axis thereby and generation of a generally cylindrical surface by the periphery of said disk;

second housing means surrounding said impeller disk and forming a downwardly open substantially cylindrical pumping chamber therearound, said second housing means being formed with at least one generally radial outlet communicating between said pumping chamber and said conduit chamber;

means forming an air compartment interconnecting said clearance and said pumping chamber, saidcompartment constituting substantially the sole fluid communication with said clearance;

and bearing means interposed between said iirst housing means and said shaft at the junction between said compartment and said clearance, the air-enclosing volumes of said clearance and said compartment being so selected that, upon submersion of said pumping plant in an upright condition, the air within said clearance and said compartment is compressed and prevents entry of liquid into said irst housing means through said compartment beyondA said bearing means.

References Cited by the Examiner UNITED STATES PATENTS 2,764,943 10/56 Peters 103-87 2,839,006 6/58 Mayo 103-87 2,918,016 12/59 Olson 103--87 3,013,500 12/61 Bollinborn et al 103-87 3,041,976 7/62 Maynard 103--87 FOREIGN PATENTS 77,426 4/18 Switzerland.

LAURENCE v. EFNER, Primary Examiner.

ROBERT M. WALKER, Examiner.

Claims (1)

1. A TOTALLY SUBMERSIBLE PUMPING PLANT COMPRISING FIRST HOUSING MEANS CENTERED ON A VERTICAL AXIS; AN ELECTROMOTOR IN SAID FIRST HOUSING MEANS HAVING A DOWNWARDLY EXTENDING VERITICAL SHAFT JOURNALED COAXIALLY THEREIN AND CARRYING AN ARMATURE RECEIVED WITH PERIPHERAL CLEARANCE IN SAID FIRST HOUSING MEANS AN IMPELLER CANTILEVER MOUNTED AT A LOWER EXTREMITY OF SAID SHAFT FOR ROTATION ABOUT SAID AXIS THEREBY; SECOND HOUSING MEANS SURROUNDING SAID IMPELLER AND FORMING A DOWNWARDLY OPEN PUMPING CHAMBER THEREAROUND, SAID SECOND HOUSING MEANS BEING FORMED WITH AT LEAST ONE GENERALLY RADIAL OUTLET COMMUNICATING WITH SAID CHAMBER;

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