US2002909A - Submersible structure - Google Patents

Description

E. MENDENHALL ET AL 2,002,909

SUBMERSIBLE STRUCTURE Filed Sept. 26, 1952 7 May 28, 1935.

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Patented May 28, 1935 UNITED- STATE SUBMEBSIBLE STRUCTURE Earl Mendenhall and Junius B. van Horn, Los Angeles, Calif., asslgnors to Menhorn, Inc., Los Angeles, Calif., a corporation of California Application September 26, 1932, Serial No. 634,911

11 Claims.

Our invention relates to a submersible structure which encloses a bearing or other element which might be detrimentally afiected by contact with the liquid in which the structure is submerged. More particularly, the invention is directed to a submersible structure in which the internal pressure can be changed relative to the pressure of the surrounding liquid by means of a pumping structure or by other pressure changing means,- and is not limited to the particular element enclosed by the structure.

The present application is a continuation-inpart Of our copending application entitled Bearing structure", Serial 220,382, filed Sepl5 tember 19, 1927. That application discloses two forms of submersible structures, one in which the internal pressure is maintained substantially equal to the pressure at the depth of submergence and being of utility without regard to its use with a system for changing the internal pressure, and the other in which the internal pressure is changed relative to the pressure at this depth of submergence. It is to the latter type of structure that is particularly directed, our application Serial No. 634,908 being directed to the former type of structure and containing claims on the combination irrespective of the general use of a pumping means or other means for changing the internal pressure.

It is often desirable to. be able to maintain the pressure inside the submerged structure at a value somewhat higher than the pressure of the surrounding liquid. This is especially true 5 in certain installations. wherein segmental on sectional enclosing structures are utilized. Any differential pressure on such a segmental enclosing structure will tend to force liquid into or from the structure depending upon whether the pressure is greater outside or inside thereof.

It is sometimes difficult to maintain a fluidtight joint on such ,a segmental shell, especially after the structure long period of time. 7 diflicult to obtain castings which are entirely impervious. -Any minute pin holes in. such a casting might permit the external liquid to enter the submerged structure with possible detrimental results. 1

It is an important object of the present invention to provide a submersible structure in which the pressure inside thereof can be changed relative to the pressure at the depth of sub- 5 mergence, this pressure being usually mainthe present applicationhas been submerged for a So also, it is sometimestained somewhat above the pressure of the external liquid at the depth of submergence.

The present structure is directed to a submersible unit from which a rotatable shaft extends. To prevent the external liquid from entering the interior of the structure it is necessary to provide a suitable seal. In the preferred embodiment ofthe present invention we have found it desirable to substantially equalize the pressures on opposite sides of this seal, thereby elimi- 10 nating any pressure differential on the seal tending to force liquid therethrough and thus permitting the use of a fluid-packed seal.

It is anobject of the present invention to provide a sealed submersible structure in which 16 the pressures on opposite sides of the seal are substantially equalized at a pressure different from the pressure at the depth of submergence of the structure.

It is an object of the present invention to pro- 20 vide a structure in which the internal pressure can be built up to a value in excess of the pressure at the depth of submergence andin which this increased internal pressure is transmitted to' opposite sides of a seal acting to seal a shaft 5 with respect to the structure. 1

Further objects of the invention lie in the particular pressure-transfer system utilized.

' The-excess internal pressure can be developed by any one of several means, such, for instance, 30 a by the use of a suitable pumping means. The utilization of such systems forms a part of the present invention.

If the .pumping means is utilized, this means may-conveniently be connected tending from the structure. It is an object of the present invention to provide a pumping chamber communicating with the seal and with the pressure-transfer means, the pressure in this pumping chamber being controlled by a pump driven by the shaft.

Such a pump may be of relatively small capacity, being utilized only for the purpose of maintaining the'internal pressure. In other instancesit is convenient to utilize a larger pump means developing a suflicient head to force a considerable volume of liquid to a point above the surface of the external liquid in-which the structure is submerged. Both systems are comprehended in the present invention.

'A'further object of the invention is ,to provide a .structurein which any of the external liquid which enters the structure under the actionof the pumpingmeans passes through a u to the shaft ex- 35 restricted passage which strains therefrom any abrasive particles or other foreign matter.

Another object of the invention is to provide an improved structure which is very effectively sealed, thereby permitting the use therein of a moisture-sensitive structure.

Other objects and advantages of the invention will be made evident hereinafter.

In the drawing,

The figure is a view of one form'of the invention shown in conjunction with a turbine pump.

In the figure, we have shown the invention as applied to one form of deep-well turbine pump unit indicated in general by the numeral l0. Such a pump unit may-be submerged in the external liquid which is to be pumped and may be lowered into a well below the level of the liquid therein. In other instances the unit may be lowered beneath the surface of a lake or other body of liquid.

'Such a pump unit may conveniently comprise upper and lower bearing or enclosing structures l I and I2 separated by one or more pump bowls l3, the whole structure being suitably connected together by suitable means and being suspended on a discharge pipe H which conducts the pumped liquid upward to a point above the surface of the external liquid. A shaft 18 extends downward through the. discharge pipe I! and drives the unit.

The upper enclosing structure II is shown as including a casing 2| and a shell 22 spaced from each other to define an annular discharge passage 23, webs 24 extending across this discharge passage to support the shell inside the casing. The unit is suspended from thelower end of the discharge pipe II, this pipe being shown as threaded into the upper end of the casing 2|. The upper end of the shell 22 is closed by an upper end wall 26 which provides an opening 21 which is slightly larger in diameter than the shaft I8 to define a passage 28. This opening is enlarged to define an upper annular or auxiliary chamber 29 which surrounds the shaft.

Separating this annular chamber 29 from the interior of the shell 22 is a seal 30. Various types of well-known seals may be utilized, but for most. exacting requirements we have found it necessary to utilize a fluid-packed seal. The detion Serial No. 225,182, entitled Emulsion preventing seal, now Patent No. 1,879,626, granted September 27, 1932. Essentially, the type of seal shown comprises a cup 32 secured in fluid-tightv relationship with the shaft I8 so as to rotate therewith. This cup thusv provides an annular chamber around the shaft which chamber contains a body of sealing liquid such as mercury. Extending downward to a point below the surface of this sealing liquid is a stationary apron 33 which is secured in fluid-tight relationship to the upper end wall 26. It is usually desirable to maintain a body of internal liquid inside the shell 22, and it will thus be clear that this internal liquid communicates with one portion of the seal 30, while the liquid in the annular chamber 29 communicates with another portion of this seal. These portions will be respectively referred to hereinafter as internal and external portions, and with the type of seal shown, the surface of the sealing liquid between the cup 32 and the apron 33 may comprise the internal portion, while the surface of the sealing liquid between the shaft l8 and the apron 33 may comprise the external portion. In other types of seals these portions-will be somewhat different.

In the preferred embodiment of the invention the interior of the shell 22 is divided by a baffle 38 into a main or bearing chamber 39 and a pressure-transfer chamber 40 forming a part of the pressure-transfer system to be hereinafter described. A bearing 42 of suitable type is positioned in the chamber 39 to journal the shaft [8, this bearing being lubricated by the surrounding internal liquid.

The shaft l8 extends completely through the main chamber 39 and extends from the enclosing structure H through a lower end wall 43 of the shell 22. This end wall provides an opening 44 slightly larger than the shaft Hi to define an annular passage 45 which communicates with a lower annular or auxiliary chamber 46 formed at an intermediate section of the opening 44. The annular chamber 46 is in open communication with the upper annular chamber 29 through a passage 41 formed in the walls of the shell 22.

It is desirable to utilize a second seal 50 to seal the shaft with respect to the lower end of the enclosing structure II. We have shown this seal as being of the same type as the seal 30, including a cup 5| secured to the shaft and an apron 52 secured in fluid-tight relationship with'the baffle 38. It is preferable to position the seal 59 in a seal chamber 53 spaced from the pressure-transfer chamber 49. These chambers may be spaced vertically with respect to each other, but in view of space considerations we have shown the balance chamber as surrounding the seal chamber. This may be accomplished by the use of a downward extending portion 54 of the baffle 38. One or more openings 55 permit communication between the seal chamber 53 and the lower end of the pressuretransfer chamber 40. Similarly one or more small openings 56 permit communication between the main chamber 39 and the upper end of the presure-transfer chamber 40.

The lower end of the enclosing structure ll defines an impeller or pumping chamber 6|] in which an impeller 6| is positioned, this impeller being secured to the shaft l8 in a well-known manner. One or more of the pump bowls l3 are secured to the lower end, of the enclosing structure H and provide passages 63 through which the external liquid is drawn by the rotation of the impeller 6|, this external liquid then being forced upward through the passages 23 and to the surface of the ground through the discharge pipe H. In the form shown, two pump stages are shown, the lower stage including a pumping chamber 64 in the bowl l3 and in which an impeller 65 is positioned.

Secured below the bowl I3 is a. lower enclosing structure l2 into which the lower end of the shaft l8 extends. This lower enclosing structure is somewhat similar to the enclosing structure ll, providing a casing II and a shell 12 mounted therein, these elements being spaced from each other to define a passage 13 com- -municating with the intake of the impeller 65 and with the external liquid. The upper end of the shell 12 is in the form of an upper end wall 15 providing an opening 16 slightly larger in diameter than the shaft I8 so as to define an annular passage 11 therearound. This passage is enlarged at an intermediate section to define sage 11, the passage positioned in the bearing chamber 8| and is surrounded by the internal liquid maintained in this chamber. It will be noted that in this structure the bafile 83 extends across the lower end of the shaft I8, thus defining a pressuretransfer chamber 86 therebelow. The lower end of the pressure-transfer chamber 88 communicates with the upper annular chamber 18 through a passage 88. The lower end of the lower enclosing structure I2 is closed off by a lower end wall 89. I

When the pump unit I0 is submerged, and the shaft I8 is not rotating, it will' be clear that the pressure in the main chambers 39 and 8| will be substantially equal to the pressure at the depth of submergence of these chambers. This will be readily apparent when it is considered that the external liquid will be at a level in the pipe 'l'l corresponding to the level of the liquid in which the pump unit is submerged. The lowerend of the pressure-transfer chamber 48 thus has access to the external liquid through the annular passage 45 and the openings 55 in the portion 54 of the. baflle 38. This external liquid is ordinarily water and of greater density than the internal liquid filling the main chamber 39 so that bodies of these-liquids will be maintained in the pressure-transfer chamber 48, these bodies of liquid being in surface contact with each other, this surface of contact being indicated by the numeral 94. The openings 56 in the baffle 38 interconnect the upper end of the pressure-transfer chamber 40 and themain chamber 39 so as to insure that the pressure in this main chamber will be equal to the pressure in the pressure-transfer chamber 40. It will thus be apparent that the pressures on opposite portions of each of the seals 38 and- 50 are maintained substantially equal, for the internal portion of each seal is in open communication with the internal liquid, while the external portion of each seal is in open communication with the external liquid present in the seal chamber 53and in the annular chamber 29. The passage 4'| communicating between the upper and lower annular chambers Hand 46 insures that the pressures in these .chambers will be maintained equal, disregarding the pressure head due to the difference in elevation of these chambers. Any change in the head of the external liquid will, of. course, be transmitted through the annular passages 28 and 45 to the seals 28 and 58 and to the',pressure-transfer chamber Similarly, the pressure-transfer chamber 86' of the lower enclosing structure |2 will maintain the pressure in the main chamber 8| sub-- stantially equal to the pressure of the external liquid at the depth of submergence. In this instance, the external liquid communicates with the upper annular chamber 18 and with the outer portion of the seal through the annular pas- 88 transferringthis pressure of the external liquid in theannular chamber 18 to the lower portion of the pressurecan enter the annular passage 28.

transfer chamber 86. Contacting bodies of the internal and external liquids may thus be' maintained in the chamber 88, the surface of contact being indicated by the'numeral 95. Theopenings 81 in the baffle 83- insure that the internal liquid in the main chamber 8| will be maintained at substantially this same pressure whereby the pressures on opposite portions of the seal 80 are substantially equalized.

When the shaft I8 is rotated, as by a suitable drive means positioned above the surface of the external liquid, the rotation of the impellers 8| and 65 increases the pressure in the passages 23 and 63, thus forcing the external liquid upward in the discharge pipe l1. As the pressure inthe pumping chamber 88 increases, this increased pressure is transmitted to the pressuretransfer chamber" through the annular passage 45, this chamber acting to correspondingly build up the pressure on the internal liquid in the main chamber 39. It will be clear, however, that the position of the surface of contact 94 will not perceptibly change due to the incompressibility of the internal liquid in the main chamber So also, the increased pressure in the discharge pipe I! will be transmitted to the upper annular chamber 29 through the annular passage 28. This pressure will in turn be trans-- mitted through the passage 41 to the lower annular chamber 48.

To prevent any abrasive material carried by the pumped liquid from entering the annular passage 28 it is usually desirable to provide a suitable straining means. .In the form shown in the figure this means includes an inverted cup.

96 secured to the shaft and which extends downward over a neck .91 of the upper end wall 26. The inverted cup is, however, spaced aminute distance from the periphery of the neck 91 so as to provide anannular passage through which the external liquid must flow upward before it This re' stricted passage and the upward flow thus strains any abrasive particles from the external liquid.

Similarly, the change in pressure in the pumping chamber 64 is transmitted to the interior of the main chamber 8| through the pressuretransfer chamber, as previously described. We have shown the lower impeller as including an eye 98 extending downward around a neck 99 of the upper end vwall 15 to define a restricted throttle or-straining passage similar to the one previously described for the upper en-' closing structure II and transmitting the pressure-changes set up near the eye 98 ,of this impeller.

. In installing the pump unit the main chambers 39 and 8| may be filled with a neutral-liquid before the unit is submerged. No dimculty will be encountered with the lower enclosing struciture II, for the correct amounts of internal and external liquids may be inserted without danger of these-liquids leaking therefrom. The passage 88 retains a column of liquid which maintains the bodies of liquids in equilibrium during installation. In installing the upper enclosing structure U a greater degree of care must be exercised. The internal liquid may be inserted as this hearing structure is being'submerged, the

internal liquid being introduced through an opening I88 in suflicient quantities to maintain the surface of'contact 94 within the pressuretransfer chamber 40 and approximately in the position shown. A plug IOI may subsequently be screwed into the opening I00 to close 01f all communication therethrough. Once the upper bearing structure II is submerged, the pressuretrans'fer system will operate as previously de- 40, and 53 with the proper amounts of internal and external liquids before the unit is submerged.

While we have shown the pressure-transfer means as comprising contacting bodies of the internal and external liquids, it should be understood that we are not limited to such a construction. If desired, other pressure-transfer means may be utilized, such'as a diaphragm, collapsible bellows, or other member separating two liquids.

In conclusion, one of the important features of the invention is to utilize a pressure inside a submerged shell which is different from the pressure at the depth of submergence regardless of whether this pressure is developed by a pumping means or by other means. If the internal pressure is maintained greater than the external pressure anyv tendency toward leakage will be outward rather than inward so that none of the external liquid will enter the shell.

Another important feature of the invention which is particularly desirable in certain installations is the maintenance of a differential pressure inside and outside 'the submerged unit, together with the maintenance of substantially equal pressures on the seal.

We claim as our invention:

1. In a submersible structure adapted to be submerged in an external liquid, the combination of an enclosing structure; walls extending across the interior of said enclosing structure and dividing this interior into an upper chamber, an intermediate chamber, and a lower pressure-transfer chamber, said intermediate and said lower chambers communicating with each other; a shaft extending from said intermediate chamber through said upper chamber; a sealing means around said shaft and sealing said upper chamber from said intermediate chamber, said sealing means providing external and internal portions respectively communicating with said upper and intermediate chambers; means changing the pressure in said upper chamber 'with respect to the pressure of said external liquid in which said structure is submerged; walls forming a passage, communicating with said upper chamber and extending downward below said intermediate chamber to communicate with said lower chamber to substantially equalize the pressures on said external and internal portions of said sealing means.'

' chamber; pump means operated by said shaft for changing the pressure in said annular chamber when said shaft is rotated; a sealing means around said shaft and separating said chambers,

- said sealing means providing an internal portion communicating with said main chamber and an external portion communicating with said annular chamber; and walls defining a passage communicating between said chambers to substantially equalize the pressures therein and thus substantially equalize the pressures on said in-- ternal and external portions of said 'sealing means.

3. In a submersible structure adapted to be submerged in an external liquid, the combination of walls forming an upper chamber communicating with said external liquid; walls defining a main chamber below said upper chamber and substantially filled with an internal liquid; a rotatable shaft extending from said main chamber into said upper chamber; a sealing means around said shaft and separating the liquids in said upper and main chambers; a pump means operated by said shaft and increasing the pressure in said upper chamber when said shaft is rotated; walls defining a pressure-transfer chamber communicating with said main chamber and containing pressure-transferring bodies of said internal and external liquids; 'and walls forming a passage communicating with said upper chamber and with said pressure-transfer chamber to conduct external liquid from said upper chamber to said body of external liquid in said pressure-transfer chamber.

4. In a submersible structure adapted to be submerged in an external liquid, the combination of a shell including a main,chamber containing an internal liquid; pressure-transfer means controlling the pressure on said internal liquid; a rotatable shaft extending upward from said main chamber; a sealing means sealing the junction of said shaft and said shell; walls defining a pumping chamber above said main chamber; pump means driven by said shafr, and changing the pressure in said pumping chamber when said shaft is rotating; walls defining an auxiliary chamber around said shaft and positioned between said pumping chamber and said'main chamber to communicate with said sealing means and said pressure-transfer means; walls defining a space communicating between said pumping chamber and said auxiliary chamber to transmit to said auxiliary chamber and to said pressure-transfer means the pressure variations developed by the operation of said pump; and walls defining a passage communicating between said auxiliary chamber and said pressure-transfer means.

5. In a submersible structure adapted to be submerged in an external liquid, the combination of: walls defining a chamber; a bearing in said chamber; a shaft journalled in said chamber and-extending upward through said walls; sealing means at the junction of said shaft and said walls above said chamber and providing internal and external portions; said internal portion communicating with said chamber; walls defining a pumping chamber; a pumping means in said pumping chamber'and driven by said shaft to change the pressure therein; walls defining a passage communicating between said pumping chamberand said external portion of said sealing means whereby changes in pressure in said pumping chamber are transmitted to said external portion of said sealing means; and an auxiliary passage communicating with said first-named passage for transmitting the pressure of said first-named passage to the interior of said chamber whereby the pressure on said internal portion of said sealing means is maintained substantially equal to the pressure these pressures changing with change in pressure in said pumping chamber.

6. In a submersible structure adapted to be submerged in an external liquid. the combination of: a shell; a bafile means extending across 'said'shell to divide the interior thereof into a main chamber thereabove and a balance chamber therebelow, said baiile means defining a port through which said chambers are in communication, said main chamber being substantially fiiled with an internal liquid, and said balance chamber containing contacting bodies of said liquids; a shaft extending upward from said main chamber, the lower end of said shaft terminating above said baflie means; walls forming an auxiliary chamber around said shaft above said main chamber; a sealing means separating said main and auxiliary chambers, one portion of said sealing means communicating with said auxiliary chamber and another portion thereof communicating with said main chamber; walls defining a passage communicating between said body of external liquid in said balance chamber and said auxiliary chamber; walls defining a pumping chamber into which said shaft extends; walls defining a passage communicating with said pumping chamber and with said first-named passage and said auxiliary chamber whereby a change of pressure in said pumping chamber is transmitted to said auxiliary chamber and to said pressure-balance chamber to maintain the pressures on said portions of said sealing means substantially equal; a pump means in said pumping chamber and. driven by said shaft to change the pressure .in said pumping chamber; and walls defining a passage communicating between said external rliquidand said pumping chamber.

7. In a submersible structure adapted to be submerged in an external liquid, the combination of: submerged walls forming a main chamber containing an internal'liquid; ashaft ex-' tending from said main chamber; walls defining an annular chamber above. said main chamberand around said shaft; a sealing means separating said main chamber from said annular chamber; walls defining a restricted passage communicating between said external liquid and said annular chamber and through which said external liquid may reach said annular chamber; and means for substantially equalizing the pressures on opposite sides of said seal at a pressure higher than the pressure of said external liquid at the depth of submergence of said submergedwalls, said means including means building up .jimctionofsaidshaftandsaidwalls other of said chambers.

thepressureinoneofsaidchamberstosaid higher pressure and including pressure-transfer means said higher pressure to the defined in claim *1 in is formed at the defining 8. A combination as "which said restricted a said annular chamber.

main chamber.

9. In 'a submersible structure adapted to be submerged in an external liquid, the combination of: walls'defining a mainchamber containing an internal liquid; walls definingan auxiliary chamber at one end of said main chamber;

a pressure-transfer means including walls de- 7 fining a balance chamber containing bodies of said internal and external liquids in pressuretransferring relationship, said balance chamber.

being positioned at the other end of said main chamber; a shaft extending from said main chamber into said auxiliary chamber; a seal associated with said shaft for sealing said main chamber and said auxiliary chamber; means building up in said auxiliary chamber a pressure greater than the pressure at the depth of submergence of said structur'e whereby this increased pressure is transmittedv to that one portion of said seal communicating with said auxiliary chamber; and walls defining a passage connecting said auxiliary chamber at one end of said main chamber and said balance chamber of said pressure-transfer means. at the other end of. said main chamber to transmit pressure variations in said auxiliary chamber, which variations affect saidone portion of said seal, to said main chamber and thus to that portion of said seal communicating with said main chamber.

10. A combination as defined in claim 9 in which said passage is form ed'exterior of said 11. m a.-submersible structure adapted to be submerged in an external liquid, the combination of: walls defining a main chamber containing an internal liquid; walls defining an auxiliary chamber communicating with said external liquid; a shaft exten ber into said auxiliary c mber; a seal associated with said shaft and separating said internal liquid in saidmain cha'gmber from the external liquid in said auxiliary chamber; pressure-transfer means communicating with said main and auxiliary chambers whereby pressure variations in one of said chambers are transmitted to the other of said chambers to substantially equalize the pressures on opposite sides of said seal, said pressure-transfer means including walls defining a balance chamber containing bodies of said internal and external liquids, in pressuretransferring relationship and respectively communicating 'with said main and auxiliary chamfrom said main chambers; a pumping means operatively associated with said shaft and spaced from said auxiliary chambemand means for transmitting the pressure variations setup by said pumping means to one of said chambers, said pressure-transfer means thus transferring these pressure variations to the other of said chambers.

EARL LENDEN'HAIL.

S B. VAN HORN.

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