US2262687A - Sealing device - Google Patents

Description

Nov. 11, 1941. A. G. LITTLE 2,252,687

SEALING DEVICE Filed March 1, 1938 2 Sheets-Sheet 1 INVENTOR lb rr L ATTORNEY A BY Ndv. 11, 1941. A. G.-LITTLE.' ,6

SEALING DEVICE Filed March 1, 1938 2 Sheets-Sheet 2 IN VEN "r02 Al'berf C L'vl'fle BY ATTORNEY Patented Nov. 11,1941

2,262,687 SEALING nnv cn Albert G. Little,- Los Angeles, Calif., assignor to U. 8. Electrical Motors, Inc., Los Angeles, Calit., a corporation of California Application March 1, 1938, Serial No. 193,312

Claims.

This invention relates to a device for sealing against the entry or exit of fluids past a wall, through which extends a rotary shaft.

Sealing devices to accomplish this general object have been proposed. especially for such structures as submersible motors for operation in well liquid.

It is one of the objects of the invention to provide a form of seal that is inexpensive and yet eilective for the purpose.

In the past, solid and liquid seals have been proposed and used. All of these seals depend upon sealing contact between relatively rotary parts, said parts being liquid or solid.

In providing solid contacting sealing members, undue or non-uniform wear, or departure from exact dimensions may result in a defective seal. It is another object of this invention to obviate such occurrences. The effectiveness of the seal, although independent of the use of a liquid, is not affected by wear or lack'of uniformity.

It is still another object of this invention to provide a semi-solid conformable sealing material that forms a tortuous contact surface with the rotary element to be sealed. In this way, the ingress or egress of fluid is greatly retarded. This efiect is secured by the aid of a finely divided solid material as the seal, such ,as graphite, mixed with a small amount of a suitable liquid, such as lubricating oil, which, when placed under pressure, will conform to the configuration of the enclosing walls, and yet which does not materially add to friction losses.

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 inthe drawings 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 that this detailed description is notto be taken in a limiting sense, since the scope of this invention is best defined by the appended claims.

Referring to the drawings: 5

Figure 1 is a sectional view showing an embodiment of one form of the invention;

Fig. 2 is a similar view showing an embodiment of another form of the invention; and

Figs. 3, 4 and 5 are iragmentarysections showing further modifications of the invention.

In Figure 1 the seal is illustrated as used to render fluid tight the casing of a submersible (Cl. cas -9) electric motor at the place where the shaft leaves the casing. Thus the casing 22, which is adapted to be submerged in a well, is shown as enclosing an electric motor 23. This motor may be of the squirrel cage induction type, having primary windings 24 mounted on the stator 25, and the rotor 26 mounted on shaft 2. The shaft extends upwardly out of casing 22 for connection to a well pump (not shown), and is supported in the top wall i of the casing by a ball bearing structure 3. The seal structure generally indicated by 21 is provided at the place where shaft 2 passes through wall I, to prevent entry of well liquid to the casing 22 at this point. To assist in excluding well liquid from the casing, provision is made to maintain it filled with air, or

, 'an inert gas, or an inert liquid under suitable pressure, as by a conduit 28, leading from the interior of the casing to a source of such gas or liquid. The lower end of the casing may be open, in which case the filling of the casing is relied on to exclude the well liquid, or it may be closed and provided with some sort of pressure equalizer. The lower end of the casing also carries an anti-friction bearing which supports the lower end of shaft 2. Since submersible motors of this type are well known, a more extensive disclosure is not necessary.

The sealing structure 27, to prevent fluid or liquid from passing either in or out of the casing around the shaft 2, will now be described. In general, provisions are made to provide a long and tortuous path for any liquid or gas that may be disposed on either side of the seal. For this purpose the shaft 2 carries a sleeve 5. This sleeve '5 is formed with a plurality of annular axially spaced flanges 6. These flanges 6 provide a tortuous surface.

In order to pack against this tortuous surface and to exclude any liquid or gas from the seal. use is made of a medium or body that is not liquid, but yet is conformable and thus can be placed readily into contact with the tortuous surface. Such abody I in this instance comprises finely divided graphite and lubricating oil. Such material is advantageous for the further reason that it does not materially increase the frictional losses by the rotation of sleeve 5. The conformable material is shown in this instance as accommodated in a member 8 having a con-v formable configuration, for example, a metal bellows. In this way pressure can be exerted upon the bellows to compress it, and thereby to force the body of material 1 in close ,contact top head I9. 1 I1 above the head- I and may be confined by with the tortuous surface formed by the annular flanges 6.

The particular means by the aid of which this result is accomplished may include the bellows heads 9 and I0, having clearance apertures for the shaft 2 and sleeve 5. The one end of the bellows 8 may be joined to head 9, as by soldering, and the other end to head III, as by the aid of the screws II, to facilitate assembly of the seal structure. The bottom head 9 may be permanently attached in fluid tight manner to the wall I, as by the aid of the flange I2 and the screws I3. I

In order to confine the body of conformable material against expression from the bellows structure, use is made of the collars I4 and I5, respectively, attached to the inner surfaces of 1 the heads I0 and 9, and. having a close running fit, respectively, with the sleeve 5 and the shaft 2.

In order .to exert a pressure upon the material I to pack it into the tortuous space, use is made i in this instance of a plurality of compression I springs I6. of the head I0.

These operate upon the top surface Thus for example, the stationary studs I I may be fastened to-the bottom head 9 and may pass through clearance holes I8 in the The springs I6 surround the studs collars I9 and nuts threaded on the studs I1.

By appropriate manipulation of the nuts 20, the

compressive force exerted on the head In may be adjusted.

The ingress of fluid or liquid exterior of the wall I is effectively prevented, for it is necessary for any such fluid or liquid to pass downwardly through the clearance aperture 2| in the head I0,

and then past the collar I4 and through the tortuous path defined between the conformable sealing material I and the flanges 6., Similarly, the egress of liquid or fluid from below the wall I is likewise prevented by the cooperation of the tortuous surfaces of the sleeve 5 andthe material 'I.

As a means of supplying the semi-solid conformable, sealing material to the seal, a conduit 29 extends to the top of the well.

A port 30 formed-in head 9, connects the end of tube 29 with the space inside the bellows, a check valve 3| serving to prevent reverse flow of the material in response to the pressure exerted by springs I6.

It may be advantageous to vary the shape of the flanges 6 of the seal. Thus, in Fig. 3 is shown a sleeve 32, adapted to be used in place of sleeve 5. In this form, the flanges 33 are shown as .of tapered cross-section. Other sections may be desirable, such as in Fig. 4, where the flanges 34 are shown as semi-circular in cross section.

Fig. 2 illustrates a more elaborate form of seal, in which the sealing effect of the semi-solid, conformable material is supplemented by that of a liquid seal. In this form, shaft 31, which may be that of a submersible pump motor similar to that of the first form, extends through the top wall 38 of the motor casing. A ball bearing 39 supports the shaft with respect to the casing,

a sealing structure 46 beingprovided to prevent passage'of fluid past the bearing. To assist in excluding the well liquid from the motor casing,

the casing is arranged to be filled with air or gas,-

or an inert liquid by a conduit 4|. A sleeve 42 having a series of annular flanges 43 is mounted on shaft 31 so as to rotate therewith. To facilitate assembly of the seal structure, the sleeve is formed in three sections, viz: upper, lower and center, indicated as 44, 46, and 45 respectively.

A cylindrical chamber 41 encompasses the center sleeve 45, the lower wall 48 of the chamber having a close running fit at 49 with the sleeve. The upper wall50 of the chamber, which is made detachable and held in place as by screws 5|, also has a close running fit with the sleeve at 52. This chamber is filled with a heavy sealing liquid, such as mercury, which is maintained under pressure. For this purpose, a gravity tank 53 may be placed a suitable distance above the seal and connected to the chamber by a conduit 54.

Chamber 4'! is supported by a metal bellows, or Sylphon 55, the flexibility of which permits the chamber to aline itself with the shaft. The upper end of Sylphon 55 is secured to the under side of wall 48, as by brazing or soldering, and the lower end of the Sylphon is detachably secured to a plate or head 56, as by screws 51. Flanges 43 of the lower sleeve member 46 rotate within this Sylphon, which is filled with a semisolid conformable sealing material 58. As in the first form, this material may be a mixture of graphite and oil. Head 56 has a clearance opening '59 through which shaft 3'! passes, and some means to seal this opening are required. A convenient way in which this may be done is to provide a stationary ring 60 about the shaft and supported above opening 59 by a Sylphon 6|. A compression spring 62 urges ring 60 into engagement with a flange .63 at the lower end of sleeve 46.

A similar chamber 64, filled with semi-solid conformable sealing material, is provided above the mercury chamber 41. Thus, Sylphon 65 is secured to the top wall 50 of the latter chamber and attached to plate 66, forming the top of the seal structure, as by screws 67. Flanges 43 of the top sleeve 44 rotate within this chamber, and a sealing ring 68, similar to ring 60, is provided to close the opening 69 where the shaft 31 passes through the top plate.

As a means of maintaining the upper and lower chambers filled with sealing material, a source of supply 10 may be provided, and under suitable pressure or gravity head. This is connected to the upper chamber 64 by a conduit II and to the lower chamber by conduit I2, and port 13 formed in plate 56.

The plate 56 carrying the entire seal structure is maintained coaxial with shaft 31 by a boss I4 formed on head 38, nuts 15 on threaded-rods 16 serving to secure it in place. The top plate 66 is provided with clearance holes 11 for these rods, and compression springs I8 confined under nuts I9 urge the plate downwardly, creating pressure on the sealing material, as in the first form.

Obviously, the source 70 might be disconnected and conduits 'II and I2 provided with check In Fig. 5 a modification of this form of seal is illustrated. In this case the pressure due the gravity head on the heavy sealing liquid in chamber 41 is dispensed with, and a compression spring is used to provide this pressure. Thus, a hollow cylindrical member 83 is attached to chamber 41 in any convenient way, as by screw threads 84 as shown, or by being formed integrally therewith. A small Sylphon, or metallic bellows 85 is supported within member 83 by having its open end 86 attached to a threaded plug 81, as by soldering or brazing. The interior of Sylphon 85 is in communication with chamber 41 by port 88 in plug 81. A cross shaped member 98 is slidable within the bore of cylin-' der 83 and is urged against the Sylphon by a compression spring 8|, confined between member 98 and the closed end 92 of member 83.

It is plain that with chamber 41 and Sylphon 85 filled with liquid and the supply opening plugged or closed by a check valve, the pressure of spring 9| will be effective to create pressure on this liquid, urging it into sealing contact with member 45.

What is claimed is:

1.'In combination, a shaft having a series of axially spaced annular flanges, means forming a series of axially spaced chambers surrounding the shaft, each of said chambers enclosing some of said flanges, and sealing materials of different characteristics in adjacent chambers and in contact with the flanges enclosed therein. K

2. In combination, a shaft having a series of axially spaced annular flanges, means forming a chamber surrounding the shaft and enclosing at least some'of said flanges, sealing material in said chamber and in contact with the flanges therein, a bellows secured to the outside of said chamber and-surrounding the shaft so as to forma second-chamber enclosing other of said flanges, sealing material in the bellows and engaging the flanges, and means exerting a compressive force on the material in said bellows:

3. In combination, a shaft, means fastened to the shaft for forming a tortuous exterior surface, means forming a series of separate chambers axially spaced along the shaft and surrounding difierent parts of said surface, a mercury sealing liquid in one of the chambers, and divided material capable of exerting a pressure in all directions in other chambers.

4. In combination, a shaft, means fastened to the shaft for forming a tortuous exterior surface, means forming a series of separate chambers axially spaced along the shaft and surrounding different parts of said surface, a mercury sealing liquid in one of the chambers, divided material capable of exerting a pressure in all directions in other chambers, and a common means for exerting a pressure on the mercury and the divided material.

' 5. In combination, a' rotary shaft having a series of axially spaced annular flanges, a hollow corrugated member capable of compression and encompassing the flanges and forming a chamber around said flanges, a top wall for said member, divided sealing and lubricating material in said chamber, and one or more springs operating on said top wall for exerting a compressive force on the hollow member.

ALBERT G. LITTLE.

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