US2610871A - Rotating shaft seal - Google Patents

Description

Sept. 16, 1952 'r. T. WOODSON ROTATING SHAFT SEAL Filed Oct. 25. 1949 n: ma 3 tw flw 3 V A 2X6 Patented Sept. 16, 1952 ROTATING SHAFT SEAL Thomasflfi- Woodson, Bridgeport,,- Conn,, assignor to General Electric Company, a corporation of I New York Application October 25, 1949,-SerialNo. 123,448

.1 Claim.

This invention :relates to improved means :for

-:sealing :rotatingtshafts against passage .of fluids,

Rotating shaft :seals ordinarily embody pairs of relatively :rotating elements maintained in resilient pressure engagement by means including .a fiexibleboot structure :carrying .one of the elements. Themeeting surfaces of the elements are lapped to provide an :area contact which is tight against passage of fluids. Usually one of the elements is-of a relatively soft material having inherent lubricity-40p example, carbon, leaded bronze and the like-because the. elements are in dryrubbing contact. The broad objectives .of my invention .areaccomplished by mounting the boot on the rotating shaft .in an improved sealing relationship therewith and by carrying the softer element at the distalv end of the boot. The softer sealing element is effectively suported by theshaft and there is no relative rotation .therebetween to. accelerate the wear .of the element. Spring .m'eans disposed within the "boot maintains the necessary resilient contact between the rotating andkstationary components of the seal. I have improved the sealing engagement between the boot and the shaft by molding a rigid ring concentrically within an enlarged end. wall through which the shaft extends. The material of the boot-rubber for exampleds squeezed radially between the shaft and the backing ring to maintaina leak-sealing relation between the :shaftand the 'boot. The internal ring structure provides an improved base for thespring means, and it stiffens the end wall of the boot so as to constitute the latter .a ,rigid neck by which the sealing assembly maybe handled. Assembly is 'facilitatedzand performance life improved by crimping the end of the flexible boot over a projecting rim of the associated seal member. With due care and handling the crimping step is equally adaptable to carbon seal elements as well as less frangible materials such as leaded bronze and the like.

Other features and advantages of the invention will be apparent from the following detailed description of a presently preferred embodiment read in connection with the acompanying drawing in which Fig. 1 is a sectional elevation of a typical application of a sealing assembly embodying the invention, and Fig. 2 is an exploded view of the respective parts, shown in half section.

My invention as shown in Fig. 1 is applied to an automatic washin machine [of the type disclosed in my presentlypending application Serial No. 551,096, :filed August "25, 1944, now Patent No. 2,527,238, for "Clutch Structure for Spinner Type Washing Machines and assigned to-the as signee 'of'this application, Such machines 'illelude a rotatable basket within which the clothes are washed by the operation of mechanical ;;a gi tating means and ,in which they are centrifugally dried by rapidly rotating the basket after the free water has been removed. The agitator is carried on the end of a shaft I extending upwardly into the basket to above the normalwater line thereof. The basket itself is carried by atubular shaft ,2 to whicha hub portion 3 of the basket supporting structure is keyed. Mechanism for selectively oscillating the shaft 1 or rotating the shaft 2 is contained within a, housing 4 having a neck portion 5, housing I and neck portion 5 constituting meansfor journaling shaft 2, i. e., a frame member on whichshaft ,2 is jour'naled.

As is explained in my aforesaid application the agitator has a central tubular post of substantially larger diameter than that of the shaft I. Incident to the operation of the machine the water rises .in the basket to overflow into the above-mentioned central post .of the agitator prevent contamination of washing liquid.

My improved seal construction comprisesthe mutually cooperating elements 6, 1 which are respectively the rotating and stationary portions of the structure. Element 6 includes a thin walled, flexible, rubber boot 8 having a thickened annular collar 9 within which is concentrically molded or otherwise disposed a rigid liner having the respective substantially vertical and horizontal wall portions 10, l l each being concentricwith the boot aperture. As is shown to better advantage in Fig. 2 the boot 8 is molded with a concentric offset portion l2 which rests upon an upper shoulder l3 of a nose piece 14 which may be of carbon, leaded bronze or other suitable metals. By a thin metal eyelet l5 the depending portion 12 of the boot may be crimped about the nose piece to maintain a fluid-tight contact 3 therewith. Within the boot I provide a light coil spring I 6 which may seat within an annular groove I! disposed within a seating part of collar 9, i. e., the projected area of the liner wall I l, and bear against the surface of the nose piece.

The fixed element 1 embodies a resilient washer 18 which seats snugly within a suitably provided pocket in the neck 5 of the casing 4. Said'washer may, if desired, be cemented to the neck to insure a sealing contact with the casing wall. The cooperating seal member comprises a metal or equivalent ring IQ of angular cross section so as to provide a flat upper bearing surface engageable by the bottom wall or mating surface of the nose piece [4 and a side wall snugly engaging the side wall of the washer l8. The respectively engaging surfaces of the nose piece 14 and the ring l9 are carefully lapped so as to make an adequate area contact sealing against the flow of-oil and water.

The wall arrangement o'f'the liner contributes importantly to the maintenance of an efiicient sealing relationship at the shaft and at the nose piece. It will be noted that wall I0 is disposed adjacent the radially outermost portion of the collar 9 andprovides a concentric outer wall of a buttressing structure which includes the contacting surface of hub 3 and the liner wall ll. Within the rigid boundaries thusestablished the flexible material of the collar is radially distorted by the shaft 2, it being understood that the collar aperture is deliberately under-sized relative to the shaft diameter. Accordingly, the shaft is engaged by a relatively large volume of material under essentially radial elastic compression. The boot necessarily rotates with the shaft, and such rotation is transmitted to the nose piece [4 through the combined effort of the boot 8 and the spring 16. It will be noted that the spring receiving channel H is immediately beneath the wall it, therefore providing a firm seat for the spring. There is no relative rotation between the nose piece and the shaft and the diameters thereof may have a close operational clearance; for example, a radial clearance of from .003 to .007 inch. Because of the absence of relativerotation this clearance will essentially be retained during use. An important advantage deriving from the support or centralizing effect of shaft 2 with respect to the nose piece [4 is the maintenance of the relative positions of .the nose piece and the cooperating fixed sealing surface I9 for effective tracking. Rotating seals soon develop a groove at their mating surfaces which is of microscopic dimension but nevertheless important to provide exactly matching profiles. Latera1 freedom of movement of the respective fixed and rotating elements allows one piece to jump. the track or groove and destroy the sealing effect. The small .4 radial clearance maintained by the support of the nose piece on the shaft 2 is within the elastic freedom of the fixed structure 1 and the dangers of accidental separation of the track surfaces is substantially eliminated.

While there has been shown and described a particular embodiment of this invention, it will be obviousto those skilled in the art that various changes and. modifications can be made therein without departing from the invention and therefore it is aimed in the appended claim to cover al1 such changes and modifications as fall within the true spirit and scope of the invention.

What I claim as new and desire to secure by I Letters Patent of the United States is:

For use with a shaft and means for journaling said shaft, a fluid seal comprising an annular member carried by said journaling means concentric about said shaft, said annular member having a bearing surface normal to the axis of said shaft, a boot disposed about said shaft and comprising an elastic collar portion spaced along said shaft from said annular member and a flexible portion extending from said collar portion along said shaft toward said annular member, an annular rigid liner molded within said collar portion and integral therewith, said rigid liner having a first wall portion parallel to the axis of said shaft and a second wall portion extending transversely to the axis of said shaft from said first wall portion but circumferentially spaced from said shaft, a first part of said collar portion being held in compression between said shaft and said first wall portion and a second seating part of said collar portion being adjacent to and backed by said second wall portion, an annular nose piece concentric about said shaft and axially movable thereon, means for fastening said nose piece in sealed relation to said flexible portion, said nose piece havin a mating surface thereon, and resilient means for urging said mating surface into sealing contact with said bearing surface, said resilient means being disposed between said boot and said, shaft and bearing axially agaimt, saidseating part which is reinforced thereagainst by said second wall portion.

THOMAS T. WOODSON.

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

UNITED STATES PATENTS 2,472,257 I v Matter June 7, 1949

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