US2974240A

US2974240A - Combined heat exchanger and protector for submergible electric motors

Info

Publication number: US2974240A
Application number: US712038A
Authority: US
Inventors: Arutunoff Armais
Original assignee: REDA PUMP CO
Current assignee: REDA PUMP CO
Priority date: 1958-01-29
Filing date: 1958-01-29
Publication date: 1961-03-07
Anticipated expiration: 1978-03-07

Description

March 7, 1961 A. ARUTUNOFF 2,974,240

COMBINED HEAT EXCHANGER AND PROTECTOR FOR SUBMERGIBLE ELECTRIC MOTORS 2 Sheets-Sheet 1 Filed Jan. 29. 1958 INVENTOR ARMA/S ARUTUIVOFF ATTORNEY March 7, 1961 A. ARUTUNOFF 2,974,240

COMBINED HEAT EXCHANGER AND PROTECTOR FOR SUBMERGIBLE ELECTRIC MOTORS 2 Sheets-Sheet 2 Filed Jan. 29, 1958 FIG. 2A INVENTOR ARMA/S ARUTUNOFF FIG. 2

ATTORNEY United States Patent F COMBINED HEAT EXCHANGER AND PROTEC- TOR FOR SUBMERGIBLE ELECTRIC MOTORS Armais Arutunoff, Bartlesville, Okla., assignor to Reda Pump Company, Bartlesville, Okla., a corporation of Delaware Filed Jan. 29, 1958, Ser. No. 712,038

7 Claims. (Cl. 310- 87) This invention relates to-submergible electric motors for use in connection with deep well pumps. More particularly, the invention consists in new and useful improvements in a combined heat exchanger and motor protecting unit for an oil filled electric motor and pumping assembly.

With pumping assemblies of this type where the elec tric motor is submerged in a well and operatively connected to the lower end of the casing which houses a coaxial pumping unit, an oil filled lubricating and protecting unit or reservoir is employed in connection with the motor unit and designed to compensate for the normal expansion and contraction of the oil in the motor, resulting from the starting and stopping of the latter. An example of such a protecting unit is illustrated and described in my earlier Patent No. 2,674,702, issued April 6, 1954, where it is explained that due to this expansion and contraction of the oil in the motor housing, there is a tendency for the surrounding well fluid to leak into the protecting and lubricating reservoir, diluting the protecting fluid and ultimately finding its way along the motor shaft to the motor unit. Hence,-it is necessary to a successful operation of the system, to provide some means for insuring against the entrance of damaging moisture into the motor structure. In my said earlier patent, there is shown a protecting unit comprising a collapsible breather diaphragm which is responsive to the pressure differential between the surrounding well fluid and the lubricating and protecting fluid in the motor.

In the operation of pumps driven by submergible electric motors, it is important to maintain the motor, bearings and other working parts at the lowest practical operating temperature. It is therefore desirable to provide, in addition to the motor protecting feature, a heat exchange system including centrifugal means associated with the motor shaft, to facilitate the circulation of the motor lubricating and protecting fluid through the heat exchange system. Such a circulating means is shown in my co-pending application Serial No. 677,097, filed August 8, 1957.

The present invention embodies a protective unit which from the standpoint of its protecting function, operates on the same basis described in my said former patent and a centrifugal circulating means generally similar to that shown in my said co-pending application, but including, in combination therewith, a novel heat exchange assembly arranged in the protecting unit, whereby the lubricating and protecting fluid in the motor unit is caused to circulate in contact with a series of cooling surfaces bearing a cooperative relationship to the collapsible breather diaphragm and the surrounding well fluid.

An object of the invention is to provide a combined heat exchanger and motor protecting unit, including a collapsible breather diaphragm, which is surrounded by nested heat exchanger sleeves arranged to provide a Patented Mar. 7, 1961 ice series of circulatory passageways adapted to cooperate with the centrifugal circulating pump in the motor unit to effect the required cooling of the circulating lubricating protecting fluid.

A further object of the invention is to provide a heat exchange system which makes possible the better utilization of the heat dissipating capacity of the housing of the submerged motor protecting unit.

Another object of the invention is to provide a system of heat exchange sleeves so arranged with respect to the collapsible breather diaphragm, as to insure an unobstructed circulation of lubricating and protective fluid, regardless of the degree of radial expansion of the diaphragm.

Another object of the invention is to provide a heat exchange system of this nature which may be easily installed and removed from the unit and which requires no major modifications of structure embodying motor protecting units such as disclosed in my said former Patent No. 2,674,702.

With the above and other objects in view which will appear as the description proceeds, the invention consists in the novel features herein set forth, illustrated in the accompanying drawings and more particularly pointed out in the appended claims.

Referring to the drawings, in which numerals of like character designate similar parts throughout the several views,

Figure 1 is a broken side elevational view of a motor and pump assembly, including the combined heat exchange and motor protecting unit of the present invention.

Figures 2 and 2A jointly represent an enlarged view, partly in section, illustrating the interior of the combined heat exchange and protecting unit and the motor unit superimposed thereon.

Figure 3 is a transverse sectional view taken on line 33 of Figure 2.

Figure 4 is a similar view taken on line 4-4 of Figure 2, and

Figure 5 is a still further enlarged fragmentary section through the lower portion of the heat exchanger and protecting unit.

In Figure 1 of the drawings, where the entire assembly is shown, 5 represents a conventional centrifugal pump unit, the casing of which is threaded at its upper end as at 6, for connection to a conventional well tubing (not shown). An oil filled motor unit 7 is concentrically connected by any suitable means to the lower end of the pump unit 5, with the motor shaft coupled to the pump shaft in the usual manner. A combined heat exchanger and protecting unit 8 is concentrically connected to the lower end of the motor unit 7 and forms the lowermost or bottom unit of the assembly.

As best seen in Figure 2, the combined heat exchanger and protecting unit 8 comprises a cylindrical housing 9 which is concentrically connected to the housing of the motor unit 7 by a coupling head and bearing support 10 provided with annular recesses 11 and 12 for receiving the adjacent ends of the housing of the motor unit 7 and the heat exchanger and protecting unit 8, respectively.

Within the lower end of the housing 9 is a compensator or protecting device generally represented by the numeral 13 and which may be of any suitable design. In the form of the invention here illustrated, the protecting unit is of the type shown and described in my earlier Patent No. 2,674,702, comprising a collapsible diaphragm or breather bag 14 formed of neoprene or any suitable material having the properties of flexibility and immunity from attack by oils and chemicals. The

bag 14 is suitably secured at its lower end as at 15, to the bottom of the housing 9, surrounding an opening 16 having a ported inlet nipple 17 in the bottom wall 18 of the housing 9. The dome-like upper end of the bag 14 rests upon a pair of wicket supports 19 and 20 which are vertically mounted at right angles to each other within the bag, by means of drilled holes in the bottom wall 18 of the housing 9.

In the use of a motor and pump assembly of the type here involved, the motor housing 7 and the protecting unit housing 9, which communicate through vertical passageways 21 in the coupling head it), are filled with a suitable lubricating and protecting fluid such as transformer oil, the weight of which normally causes the walls of the bag 14, to collapse to a certain degree into contact with the supporting wickets l9 and 2d. The interior of the bag 14, being in communication with the surrounding well fluid through opening 16 and ported nipple 17, becomes filled with said well fluid.

Thus, the collapsible diaphragm or bag 14 is responsive to the pressure differential between the lubricating and protecting fluid within the housings 7 and 9 and the surrounding well fluid, as explained in my said earlier patent. It will be understood that my reference to said patent is purely for the purposes of illustration, as the present invention is in no way restricted to use with a compensator of this particular type.

Surrounding the protector element 13 and acting jointly with the housing 9, is a heat exchanger element generally designated by the numeral 22. This element consists of an annular outer sleeve member or jacket 23, arranged concentrically within the housing 9 and spaced inwardly therefrom to provide an annular passageway 24, the lower extremity of the sleeve 23 being spaced vertically from the bottom 18 of the housing 9 and supported thereon by a series of legs 25' secured at spaced intervals around the sleeve. The legs 25 may be secured to the sleeve by welding or other suitable means as at 26, and are of a length to support the sleeve in a sufiiciently elevated position above the bottom 13, to provide an annular fluid return area 27 as will later appear. The upper end of the sleeve 23 is closed by an inverted conical top 28 which terminates in an upwardly directed neck 29 adapted to fit snugly within the lower end of a vertical tube 3t), connected into a central opening 31 in the bearing support and coupling head 16. The tube 30 and the opening 31 serve as an inlet to the central passageway 32 of the motor shaft 33, the lower end of which is rotatably mounted in a bearing assembly 34 located in the coupling head and bearing support 16. A hearing gland 35 retains the bearing assembly in place in the support 10.

Returning to the heat exhanger element 22, an inner sleeve 36 is arranged concentrically within the outer sleeve 23 and spaced inwardly therefrom to provide a second annular passageway 37. This inner sleeve is supported within the outer sleeve 23 by a series of lugs 38 (Fig. 5), spaced at suitable intervals around the lower end of the sleeve 23, and projects downwardly through the lower extremity of sleeve 23, forming a baffie which surrounds the lower end of the protecting bag 14 and, in addition, directs the fluid from the first passageway 24, to the second passageway 37. The inner sleeve 36 is spaced outwardly from the protecting bag i4 and its lower end preferably terminates in a flaring lip 39 which serves as an annular mouth for a third passageway 4 t defined by the bag and the inner sleeve 36 and opening into the upper end of the jacket or outer sleeve 23. The top of the inner sleeve terminates below the top of the outer sleeve.

The upper end of the outer sleeve 23 is secured and maintained in the proper spaced relation with respect to the casing 9 by means of a series of lugs 41 arranged at suitably spaced intervals and if desired, additional spacing and securing means may be employed between the inner and outer sleeves to assure the maintenance of an adequate passageway therebetween.

Also, if desired, an inner flexible sleeve 42 may be employed within the bag 14 to afford added radial support adjacent the lower end of the bag.

As in my co-pending application No. 677,097, now Patent No. 2,854,595, hub 43 of the shaft 33, which extends axially through and supports the rotor 50 of the motor, within the stator 51, is enlarged and solid throughout the major portion of its length, the central passageway 3 of said shaft terminating near the lower end of the hub 43 as at 44. The periphery of the hub 43 is provided with a series of annularly spaced grooves 45 extending longitudinally from a point on the hub above the upper extremity of the rotor (Figure 2A) for substantially the full length of the rotor. The closed upper end of the shafts passageway 32, is placed in communication with the lower ends of the grooves 45 by a corresponding series of radial ports .46 (Figure 2), whereby, as the motor shaft rotates, the lubricating and protecting fluid which passes upwardly through the passageway 32 from the central tube 30, is caused by centrifugal force to be ejected through the radial ports 46 into the lower ends of grooves 45. The protecting fluid is forced up the grooves 45 on the hub 43 and after passing the full length of the rotor 50 to the top of the motor, it is slung outwardly, descending through the gap 52 between the rotor and stator for return to the protecting unit 6, through passageways 21 in the coupling head 10.

As previously stated, when in operation the motor housing 7 and protector housing 9 are filled with lubricating and protecting fluid which completely surrounds the motor and fills the entire area of the housing 9 externally of the bag 14. During the operation of the motor, the lubricating and protecting fluid expands due to the increased temperature of the motor, and compensation for this expansion is taken care of by the flexible bag 14 which collapses into the spaces between the wickets 19 and 2t forcing any well fluid which is in the bag, outwardly through the nipple 17.

After the motor is stopped, the lubricating and protecting fluid cools and contracts and with it the bag 14 expands and draws the surrounding well fluid into the bag through the nipple 17 to compensate for the loss of l volume in the housings 7 and 9.

During the operation of the motor, while the lubricating and protecting fluid is being subjected to the heat developed by the motor, the centrifugal action of the hub 43 causes this fluid to circulate along the full length of the rotor, passing downwardly through the ports 21 in the coupling head 10, into contact with the conical top 28 of the outer sleeve or jacket 23. The fluid flows from this conical top downwardly through the outer passageway 24, in heat exchange contact with the inner periphery of the housing 9 which is cooled by the surrounding well fluid, and into the enlarged annular area 27 at the lower end of the protecting unit. It then passes upwardly through both

passageways

37 and 40 into the area of the jacket 23 above the bag 14 and from thence travels upwardly through the converging top 28 and tube 3i) into the central bore 32 of the motor shaft 33 from whence it repeats this cycle.

In the event the bag 14 has expanded radially to a point where the lower extremity of passageway 40 has become restricted, the continued circulation of oil is insured by the intermediate passageway 37 which is protected from any restriction, by the lower portion of the inner sleeve 36 which depends below the opening of the passageway 37.

Thus, throughout the circulation of the lubricating and protecting fluid, it is subjected to the cooling action of the extended contact surfaces formed by the inner and outer sleeves as well as the outer surface of the bag 14 and at the same time utilizes the heat dissipating capacity of the housing 9, which together with bag 14 is in contact with the cooler surrounding well fluid.

It will be apparent that a combined unit constructed in accordance with the present invention affords a compact and easily assembled unit which, in addition to compensating for expansion and contraction of the lubricating and protecting fluid upon the starting and stopping of the motor, affords an increased cooling surface area for the fluid to further protect the working parts of the motor.

From the foregoing it is believed that the invention may be readily understood by those skilled in the art Without further description, it beingborne in mind that numerous changes may be made in the details disclosed, without departing from the spirit of the invention as set forth in the following claims.

I claim:

1. In a submergible pumping assembly, including a pump unit and a coaxial, oil filled electric motor unit having a vertical shaft suspended therefrom; a combined heat exchanger and motor protecting unit, comprising a housing coaxially connected to said motor unit, a reservoir in said housing communicating with said motor unit, for receiving, protecting-and lubricating fluid, a flexible diaphragm partition in said housing, exposed on one side to the fluid pressure within said reservoir and on the other side to the pressure of the surrounding well fluid, to thereby compensate for a pressure differential Within and Without said reservoir, means associated with said motor shaft'for circulating lubricating and protecting fluid from said motor unit to and from said reservoir, and an extended surfacecontact heat exchanger in said reservoir, arranged to direct the course of circulation of said lubricating and protecting fluid to and from said motor unit, said heat exchanger comprising at least two nested, elongated cylindrical sleeves, concentrically arranged in said housing in radially spaced relation to the latter and to each other, to define intercommunicating, annular fluid passageways, one of said passageways establishing communication between said reservoir and the inlet side of said fluid circulating means and the other of said passageways establishing communication between said reservoir and the discharge side of said fluid circulating means.

2. Apparatus as claimed in claim 1, wherein said diaphragm is arranged concentrically in said housing, in spaced relation to the walls of the latter and to the innermost of said sleeves to define therewith an annular fluid passageway, the interior of said diaphragm being sealed with respect to the reservoir but in communication with the fluid surrounding the housing, said diaphragm being responsive to variations in the pressure differential within and without said housing.

3. In a submergible pumping assembly, including a pump unit and a coaxial, oil filled electric motor unit having a vertical shaft, suspended therefrom; a heat exchanger unit, comprising a housing coaxially connected to said motor unit, a reservoir in said housing communicating with said motor unit, for receiving protecting and lubricating fluid, said motor shaft being drilled longitudinally from its lower end to provide a central bore, opening into said reservoir, centrifugal means associated with said shaft for circulating fluid from said reservoir, through said bore and back to said reservoir, a concentric, elongated, cylindrical jacket in said reservoir, spaced radially from the walls of said housing, defining therewith a first annular fluid passageway, said jacket terminating at its upper end in a substantially conical top, an opening in the apex of said top which communicates with the central bore of said motor shaft, the lower extremity of said jacket being elevated from the bottom of said reservoir, a concentric cylindrical sleeve spaced inwardly from said jacket and terminating at opposite ends below the corresponding ends of said jacket, said sleeve defining with said jacket a second annular fluid v v a 6 r passageway, communicating at its lower end with said first passageway and at its upper end with the interior of said jacket, whereby protecting and lubricating fluid being circulated by said centrifugal means, is caused to flow downwardly over the top and outer surface of said jacket, through said first passageway and return upwardly through said second passageway and the interior of said jacket, to said shaft bore.

4. Apparatus as claimed in claim 3, including an oil pressure compensator comprising a substantially cylindrical, collapsible diaphragm, concentrically mounted in said reservoir, in inwardly spaced relation to said sleeve and defining therewith, a third fluid passageway, the lower end of said sleeve being spaced slightly above the bottom of said reservoir to provide an inlet for said third passageway, the outlet of which communicates with the interior of said jacket, the interior of said diaphragm being sealed with respect to the reservoir but in communication with the fluid surrounding said housing.

5. In a submergible pumping assembly, including a pump unit and a coaxial, oil filled electric motor unit having a vertical shaft, suspended therefrom; a combined heat exchanger and motor protecting unit, comprising a housing, coaxially connected with said motor unit, a

reservoir in said housing, for receiving, protecting and lubricating fluid, said motor shaft being drilled longitudinally from its lower end to provide a central bore having its inlet end in communication with said reservoir, centrifugal means associated with said shaft for circulating fluid fed from said reservoir through said bore, fluid return ports leading from said motor unit back to said reservoir, a heat exchanger assembly in said reservoir comprising a concentric, elongated, cylindrical jacket, spaced radially from the walls of said housing, defining therewith a first annular fluid passageway, said jacket terminating at its upper end in a substantially conical top lying in the line of flow from said return ports, an opening in the apex of said top which communicates with the central bore of said motor shaft, a concentric cylindrical sleeve spaced inwardly from said jacket, defining therewith a second annular fluid passageway, communicating at its lower end with said first passageway and at its upper end with the interior of said jacket, and an oil pressure compensator, comprising a substantially cylindrical, collapsible diaphragm mounted concentrically in inwardly spaced relation to said sleeve, defining therewith a third annular fluid passageway communicating at its lower end with said first and second passageways and at its upper end with the interior of said jacket, the interior of said diaphragm being sealed with respect to the reservoir but in communication with the fluid surrounding said housing.

6. A heat exchanger unit for a vertical, oil filled, submergible electric motor having a motor shaft drilled longitudinally from its lower end to form a fluid conducting bore, a centrifugal fluid circulator associated with such shaft and fed from said bore, a housing forming a lubrieating and protecting fluid reservoir, a combined coupling head and motor shaft bearing support interposed between and coaxially connecting said motor and reservoir, a series of vertical ports leading from the interior of said motor to said reservoir, a cylindrical jacket in said reservoir spaced coaxially from said housing to form therewith, an annular fluid passageway and terminating at its upper end in an inverted conical top, means placing the apex of said top in communication with the bore of said shaft, means supporting said jacket in elevated position with respect to the bottom of said reservoir, an inner sleeve coaxially spaced from said jacket to form a second annular fluid passageway, the lower end of said sleeve extending below the corresponding end of said jacket to form a fluid directing baflle, the lower end of said second passageway communicating with the lower end of said first passageway and its upper end opening within said jacket below said conical top.

7. Apparatus as claimed in claim 6 including a substantially cylindrical, collapsible diaphragm mounted concentrically in inwardly spaced relation to said sleeve, defining therewith a third annular fluid passageway, means supporting said sleeve in slightly elevated position with respect to the bottom of said reservoir to provide an inlet for said third annular fluid passageway, the discharge end of said last named passageway opening to the interior of said jacket, the interior of said diaphragm being sealed with respect to the reservoir but 10 in communication with the fluid surrounding said housing.

References Cited in the file of this patent UNITED STATES PATENTS FOREIGN PATENTS Great Britain May 14,

France Sept. 1,