US2218937A - Submersible structure - Google Patents

Description

Patented Oct. 22, 1940 UNITED STATES PATENT OFFICE 2,218,937 SUBMERSIBLE STRUCTURE poration of California Original application March 14, 1932, Serial No. 598,763. Divided and this application August 23, 1937, Serial No. 160,485

1 Claim.

This invention relates to a submersible structure, such, for example, as a power unit for pumping liquids from a well. Such a unit comprises a pump and a source of power, which may be an electric motor, for driving the pump. In a device of this character, the motor must be so. arranged that it is sealed against the entry of the well fluid.

This application is a division of an application filed in the names of Thomas G. Myers, George m T. Pfleger and Frank Mason, for Submersible power unit, Serial No. 598,763, flied March 14, 1932.

It is one of the objects of this invention to provide an electric motor power unit that is ef- 15 fectlvely and inexpensively protected againstentry of well fluid that may injure the motor, by maintaining a the motor housing.

Experience has shown that upon continued operation of such a motor, the motor windings transfer so much heat to the oil filling that the oil expands in spite of the cooling efi'ect due to the submerged condition of operation. Thus, if the casing is fluid tight, difllculty is bound to arise due to this expansion, such as the creation of an unsafe pressure in the casing. It is another object of the invention to obviate this difiiculty by providing a casing having means to ensure substantial equality of pressure within and without the casing at all times. a

This invention possesses many other advantages, and has other objects which may be made more easily apparent from a consideration of several embodiments of the invention. For this purpose there are shown a few forms in the drawing accompanying and forming part of the present specification. These forms will now be described in detail, illustrating the general principles of the invention; but it is to be understood 40 thatthis detailed description is not to be taken in' a limiting sense, since the scope of the invention is best defined by the appended claim.

Referring to the drawing:

Figure 1 is a longitudinal sectional view of a 45 submersible power unit, the motor of which embodies one form of the invention; and

Fig. 2 is a longitudinal sectional view, on a reduced scale, of the lower end of a similar motor, embodying a modified form of the invention.

5 In Fig. 1 of the drawing is illustrated a casing I having a pressure equalizing device 2 disposed at its lower end. Casing I serves to house an electric motor 3 adapted to drive a centrifugal pump 4 by means of a shaft 5, the whole forming a submersible pumping unit. This unit is insealing material, such as oil, in

tended to be submerged in a well having 3. casing 6 filled with a liquid medium I, the surface of which may be at a considerable distance above the unit, this distance sometimes being of the order of several hundred feet.

It is obviously essential to the successful and continued operation of the motor that the medium 7, which is usually water, or a mixture of water and other substances, should be entirely excluded from the casing l. Thus, an effective seal 8 must be provided for the aperture 9 in the top closure ill of the casing through which shaft 5 extends, and one capable of functioning eiiec tively for long periods without adjustments or replacements, since it is not accessible except upon removal of the entire structure from the well.

As shown, this seal has an annular sealing surface ll of large area formed between a rotating seal member I2 secured on shaft 5 by a set screw l3 and a non-rotating seal member i4 attached to cover It. Springs I 5 urge the nonrotating seal member intosealing engagement with the rotating seal member 12. Member I4 is secured to cover i 0 by a metal bellows, or Sylphon l6, which in eifect forms a flexible wall extension of easing l and permits the member to move axially into engagement with the cooperating member, at the same time maintaining it in fluid tight relation with the casing. It will be noted that the area of the sealing surface is large, thus ensuring long life of the parts; and that the quality of the seal will be improved by the relative wear of the members.

To further guard against entry of well fluid to the motor, and also as a means of equalizing the pressure within and without casing I, the casing is filled with a lubricating and insulating liquid l1 such as oil. This may be supplied through a pipe I8, which leads from the top of the well and communicates with the interior of casing I through the bottom cover IS. A check valve 20 is provided in this pipe to prevent return flow of oil from the casing.

To prevent excess pressure within the casing due to expansion of the oil H from the heat developed incident to the operation of'the motor, and also to prevent the pressure within the motor casing falling below that of the surrounding well fluid for any reason, pressure equalizing This comprises a downmeans 2 is provided. wardly extending cylindrical extension 2|, provided with a cover 22 at its lower end. A slidable piston 23 is accommodated in cylinder 2|, the upper side of the piston being subjected to the pressureof oil I! within casing l by means of taining the pressures equal.

As the liquid N is generally lighter than the well fluid and not readily miscible therewith, it is possible to dispense with a division wall between the fluids, such as the piston 28. Such an arrangement is illustrated in 2, where corresponding parts bear the same numerals as in the first form.

In this modified form, a seal is provided at the upper end of the casing as before, and the lower head26 of casing i is provided with a tubular extension 27, open to the well fluid at the bottom as indicated by as and in communication with the interior of the casing-by port 29. Here there is a contacting surface between the well fluid i and the body of oil in the casing i. As the oil it is lighter than fluid 7, it is retained inside casing i and expands or contracts against the pressure of the well fluid as before, the surface of contact 3% rising and falling in the extension 2! in the saine way. as piston 23 moves in the first form.

What is claimed is: I

In a submersible structure, a casing, a liquid fllling the casing, a, hollow extension extending outwardly from the casing and in communication therewith through a restricted port in the casing, said extension beingopen at the bottom, and a close fitting piston" in said extension, subjected on one side to the pressure in the casing and on its other side to the'pressure of the liquid in which the structure is submerged.

THOMAS G. MYERS. GEORGE T. PFLEGER. FRANK MASON.

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