US2418194A - Sealing means for submersible electric motor-pump units - Google Patents

Description

Patented Apr. 1, 1947 SEALING S FOR SUBMERSIBLE ELECTRIC MOTOR-PUMP UNITS Jack E.. Riccardo, Oakland, Callfl, asslgnor to Shasta Pump Company, a corporation fornia of Call- Application April 19, 1944, Serial No. 531,822

1 4 Claims.

The invention relates to submersible electric motor-pump assemblies of the type commonly used in deep wells and other installations wherein the motor-pump unit is inserteddirectly in the fluid to be pumped.

An object of the present invention is to provide in an assembly of the character described an improved means for sealing the interior of the normally submerged electric motor from the surrounding well fluid.

Another object of the invention is to provide a sealing means of the character described utilizing a plurality of sealing fiuids cooperating with a plurality of closed chambers and automatic pressure responsive means for equalizing the pressures of the sealing fluids and the well fluid to prevent entry of the well fluid into the electric motor housing.

A further object of the invention is to. provide a sealing means of the character above which will be compact and constituted of a small number of sturdily formed parts designed, arranged and constructed to afford a more complete protection of the electric motor from the-surrounding well fluid for a longer period of time than seals heretofore available.

The invention possesses other objects and features of advantage, some of which, with the foregoing, will be set forth in the following description of the preferred form oithe invention which is illustrated in the drawings accompanying and forming part of the specification. It is to be understood, however, that variations in the showing made by the said drawings and description may be adopted within the scope of the invention as set forth in the claims.

Referring to said drawing:

Figure 1 is a longitudinal sectional View of a submersible electric motor-pump unit embodying a sealing means constructed in accordance with the present invention.

Figure 2 is an enlarged sectional detail of a portion of the sealing means.

The improved sealing means for a submersible electricmotor-pump unit of the present invention consists briefly of the combination with a closed motor housing 6 having a motor shaft 1 extending from one end 8 thereof, of a closed chamber 9 sealed to the end 8 about the shaft 1, operating fluids II' and I2 in thehousing and chamber, means l3 and It for sealing the cham- 2 ing well fluid. The unit is adapted for lowering into a well casing or other chamber from which fluid is to be pumped and is designed for direct submergence in suchfluid. As will be seen from the drawing a vertical type electric motor I 5 is positioned at the bottom of the unit, out of the path of flow of the well fluid into and from the super-imposed pump. I

j adjacent the closed bottom end of the housing. The motor shaft may be hollow or sectional,

although for simplicity of illustration here, a single, one piece shaft is shown throughout the assembly, it being understood that ordinarily the pump shaft will be separate of but suitably joined V to the motor shaft. A fluid tight, submersible type electric cable 35 is sealed in the housing end 8 and adapted for connection to a power source for energizing the motor.

Spaced axially above the motor housing and concentric to the shaft I, is a pump suction piece and strainer l8, which is here a bowl-like member having a centrally apertured bottom I 9 surrounding the shaft, a perforated, strainer, upstanding, cylindrical side wall 2| providing fluid entry to the pump, and an inturned, annuiarly flanged, top wall 22 adapted for mounting to the intake opening 23 for connection to the pump impeller.

Any of various designs for centrifugal pumps well known in the art for the purposes described herein may be used. A sleeve bearing 24 is inserted in the bottom aperture 28 of the bowl 1 member for journaling the shaft 1 thereat. Pref-' her and housing from each other and from the e'rably a sand cap 21 is mounted on the shaft for rotation therewith above the bearing 24 to centrifugally throw away fromthe shaft, sand and other solid particles which may be in the wellfluid so as to prevent movement of such particles along the. shaft to the rotary seals hereinafter described. l 1 V Inacoordance with the present invention there is provided between the upper end 8 of the motor housing and the bottom I! of the pump strain er I 8, theclosed chamber 9 which is here closed .at its iqwer and upper ends by the end wall I and wall 3 and bottom wall l9. Preferably and as here shown the wall 28 is formed as an integral part of the motor housing end 3 and is provided at its upper end with a flange 29 bolted directly to the strainer bottom l9. Desirably the wall 23 is of substantially cylindrical form having an outside diameter approximately equal to the diameters of the housing-end 8 and the bowl bottom l9 but formed with longitudinal recess portions 29 for housing within the diameter of the unit the electric cable 35 and the pressure responsive means l1 in greater detail below;

As mentioned above, sealing means 13 and i4 are provided for sealing the interior of housing 9 and chamber 9 from each other and from the I well fluid. A preferred form of such means 'is shown inthe accompanying drawing. particularly in the enlarged detail in Figure 2. Supported on and sealed to the end wall 8 and the strainer bottom l9 and surrounding the shaft in opposed relation at the bottom and top of the chamber 9, are bearing rings 3| and 32 having opposed annular bearing faces 33 and 34 arranged'in plan s perpendicular to the shaft axis. These rings may be of any suitable bearing material such as leaded bronze, porous bronze impregnated with oil, bearing bronze and carbon or graphite composition, or the like.- Surrounding the shaft 1 and adapted for rotation therewith are sealing rings 36 and 31 which abut the bear ing faces 33 and 34 of the stationary rings 3| and 32 to provid a rotating seal therebetween. The

- specially prepared for sealing rings of this character are preferred. An example of such a preferred product is neoprene. The rings 38 and 39 are each formed with a base portion 4| having a substantial dimension along the shaft and i which are sealed tightly to the shaft by suitable bonding thereto or a pressed fit or the like. Extending radially outwardly from each base portion 4| is an annular flange 42 which directly abuts and seals against the adjacent rings 36 and 31 respectivelyand which because of the pliable nature of rings 38 and 39 may flex longitudinally of the shaft axis. If desired and as here shown a compression band 43 may be placed around each base portion 4| for holding the same tightly against theshaft, and an alignment sleeve 44 placed over the periphery of the flange 42 and the adjacent ring 36-31 to insure proper engagement of these members. Compressed between th flanges 42 of the rings 38 and 39, and constantly urging the engagement of the sealing parts above discussed, is a helical spring 46 which is mounted concentrically around the shaft and supportedat its ends on inturned end portions 41 on the sleeves 44. From the foregoing it will be clear that the outstanding flanged part of ring 38 is constantly urged into sealed engagement with abutting ring 36 and the latter is in turn urged against and into sealing relation with the abutting stationary bearing ring 3| to thereby' seal ofl from the well fluid, theupp r end of chamber 9 along the engagement to thereby seal off communication between the chamber 9 and the motor housing along the shaft.

As mentioned in the foregoing and as an important feature of the present invention, operating fluids II and 12 are placed in and preferably fill the motor housing 8 and the chamber-'9. The fluid II in the housing is preferably a relatively light dielectric oilwhich will provide lubrication of the motor bearings and assist in cooling the motor parts. The fluid l2 in the chamber 9 hasin addition to its other functions herein discussed, th function of lubricating the rotary seals and may vary with the well fluid being pumped. A wide variety of fluids including oil or even clear water may be used. Where the well fluid is water and for certain other applications, I prefer to use a relatively heavy fluid such as heavier than water oil in the chamber and desirably this oil completely fllls the chamber. As will be understood from the foregoing,the well fluid, in order to reach the chamber, needs first to pass the bearing 24 to reach the rotary seal l3 at the top of the chamber, fail, the well fluid, where the same is water, will merely float on top of the heavier than water oil in the chamber. Should the lower rotary seal 14 fall, the only immediate result is to communicate the light-oil in the motor housing with the heavier oil in the chamber. Subsequently these oils may admix in part without danger to the motor parts. The water entering the top of the chamber would still not reach the motor until the heavy oil in the chamber had been displaced by gravitation into the motor housing or otherwise. Thus for an indefinitely long period of time after failure of both seals l3 and I4 the 4 .motor parts will be protected from a harmful concentration of water or other well fluid.

'The pressure responsive means l6 and 11 for equalizingthe fluid pressures in the motor housing and chamber 9 with the pressure of the well fluid, is another important feature of the present invention. Such means effectively prevents the building up of fluid pressure differentials across the rotary seals 13 and I4 and are also arranged to permit thermal expansion of the fluids particularly of the oil in the motor housing which is heated during the operation of the motor. Thus the pressure of the fluid in the chamber 9 is maintained at the same pressure as the well fluid at the top of the rotary seal i3 and there is no pressure diflerential across the seal to urge the well fluid therethrough. Likewise the pres- I sure=of the light oil in the motor housing is maintained at the same pressure as the fluid in the chamber 9'so that there is no pressure differential present to urge either of these fluids through the lower rotary seal l4. This pressure equalization is extremely important in deep well installations wher the motor-pump unit may be submerged hundreds of feet below ground level. The type shaft. Inthe same manner rings 33, 31 and 32 are urged into sealing Should this seal asiaies ing an equal pressure of the motor housing and chamber fluids. Also an increase of pressure in either compartment for whatever reason, will be immediately and automatically reflected in the other compartment so that at all times the pressure differential across the rotary seal it therebetween will be nil,

The means for equalizing the pressures of the fluids in the motor housing and chamber with that of the well fluid, here consists of a fluidv pressure passage through the side wall 28 of the chamber'9 and a fluid tight bellows 52 mounted in the channel 29 surrounding the chamber side wall, and sealed to the outer end of the passage 5!. By this arrangement the pressure of the well fluid is transmitted to the chamber 9 thus equalizing the pressure of the fluid said flange members to urge the latter and said l2 therein with the pressure of the Well fluid and automatically eliminating any pressuredifferential across the top rotary seal l3.

If desired, conduits may be connected to the motor housing and chamber 9, and extended to oil reservoirs for replenishing the fluids Hand l2.

While the present invention has been explained in connection with a submersible electric motor, it will be understood that the sealing means may have other applications in sealing from an. exterior fluid, the interiorof a housin having a rotary shaft extending therefrom.

Also while the present invention is particularly adapted for deep well pumps and reference is frequently made herein to well fluid, it will-be understood that the present invention will have applications in other than a, well pump unit,and in such cases the unit submerged in other than wells.

I claim:

1. In a sealing means for a submersible housing having a rotatable shaft extending therefrom, means providing a closed chamber sealed to said housing, about said shaft with the latter extending through said chamber, flu ds in said housing and chamber, a rotatable sealing means sealing said fluids from each other along said shaft, a second rotatable sealing means sealing said chamber from the external submersible fluid along said shaft, said first and second named rotatable sealing means comprising a pair of rings concentric to and surrounding said shaft and secured and sealed to said housing and chamber means respectively, a second pair of rings secured and sealed to said shaft concentric to said flrst rings and in sliding sealed en agement therewith, means constantly urging said rings into said sliding sealed engagement, and fluid tight pressure responsive means equalizing the pressures of the fluids in said housing and chamber with each other and with the pressure of said external fluid.

2. In a bmersible el ctric motor-pump adapted for submersion 11 well fluid, the combination with a closed motor housing of an adiacent axially aligned closed chamber, a motor driven shaft extending axially from said housing through opposite ends of said chamber and adapted for connection to a pump, means enunit rings and surfaces into engagement, a relatively light dielectric oil filling said motor housing. a fluid lubricant in said chamber, and fluid tight pressure responsive means operatively connected to said housing and chamber and well fluid for -equalizing the pressure therebetween. a

3. An electric motor unit adapted for submersion in well fluid,- including a casing, dielectric fluid filling said casing, a rotor in said casing and submerged in said dielectric fluid, a shaft driven by said rotor and extending from said casing, means to seal said well fluid from said casing fluid comprising a, member surrounding and attached in fluid-tight relation to said shaft to revolve therewith, a sliding contact member surrounding said shaft and carried by said firstmentioned member to revolve therewith, a second sliding-contact member surrounding said shaft, means independent of said shaft to support said last-mentioned member in fixed position, said sliding contact members having contacting faces forming a fluid-tight seal between them, means l to maintain said faces in fluid-tight contact, and fluid tight pressure responsive means in communication with said dielectric fluid and mounted in position exposed to said well fluid and functioning to equalize the pressure of said fluids on opposite sides of said sliding contact members. J

4. A submersible electric pump 'motor comprising; a motor housing; dielectric fluid filling said housing; a motor shaft extending through and from an endwall of said housing; means for sealing said dielectric fluid from the well fluid in which the motor is adapted for submersion including a ring member of suitable bearing material secured and sealed to said end wall in surrounding concentric relationto said shaft, 9, second ring member of suitable bearing engaged ring members.

material carried by and sealed to said shaft and movable longitudinally .onsaid shaft into fluid tight sliding contact with said flrst ring member,

spring means constantly urging said second ring member into said fluid tight sliding contact, and bellows means communicated with said dielectric fluid and positioned for communication with said well fluid on submersion of said motor and functioning to equalize-the pressures of said dielectric and well fluids at opposite sides ofsaid JACK E. FIIICCARDO.

REFERENCES cirnn The following references are of record in the file of this patent: I

nm'mns'm'ms Pam-m Holiatz Oct. '1, 1941)

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