US2584679A - Reversible packing - Google Patents

Description

Feb. 5, 1952 s. DoBRosAvLJEvlc REVERSIBLE PACKING Filed Aug. 8, 1945 www@ Fb. 5,- 1952 s. DoBRosAvLJEvlc REVERSIBLE PACKING 4 Sheets-Sheet 2 \Fi1ed Aug. 8, 194e 56. 5 Frs.

Feb' 5, 1952 s. DoBRosAvLJEvl REVERSIBLE PACKING QJ@ l J w /frv P 1 Filed Aug- 8 1946 lill Il. L@ 5 s. DoBRosAvLJEvl yFeb. 5, l9 52- REVERSIBLE PACKING v 4 sheets-sheet 4 Filed Aug. 8, 1946 .S .um

Patented Feb. 5, 1.952

REVERSIBLE PACKING Stojimir Dobrosavljevi, Paris, France, assigner, by mesne assignments, to International Engineering General Research & Licensing 'Company, Wilmington, Del.l yApplication.August 8, 1946, Serial No. 689,076

' isclaims. (c1. ese-11) The present'invention relates to a Vreversible packing, the purpose -of which is to provide imvpermeability between two mechanical parts which are in relative rotating movement.

rThe .different 'packings known at thepresent time utilize either asupple diaphragm of variable proiile,.n1ore or less flat, or a cylindrical membrane similar .to a bellows. These elements are utilizedfor their own quality oi impermeability and for their suppleness which permitsV a relative play in the axial direction, of the turning parts between which impermeability is to .be eifected. In addition-to the aforesaid .diaphragms, these packings include an elastic body, in general a coil spring, assuring the necessary average pressure between the rubbing tight surfaces which usually are, on the one hand, a thrustblock surface, and on the other hand, the Vsurface of an element (tight face) of the packing. The average pressure isrthat which the spring exerts in the average position of the thrust-block between the two extreme positions of its possible axial oscillation having an amplitude A.

In order to give greater suppleness tojthis packing, the spring has a 'relatively 'lar'genumber of'turns, and consequently a relativelygreat length.

These prior art packings present numerous inconveniences: In the iirst place, in view of the f actthat the average pressure of 'the spring is practically constant, that i`st o say, not Vproportional tothe pressure of the uid, it is 'necessary te employ 4ajspring suiciently strong to resist the maximum pressure ofthe lfluidjhence exaggeratedwear and damage is caused o n the rubbing surfaces, even `when that is not necessary, r that is to say, when vthe iiuid is at much lower pressure. This wear and damage give rise to leaks.. v

'Besides these inconveniences, cia-hydrostatic nature, there are others yofy a kinetic nature. When there is a possibility of axial displacements in the course of the relative rotation of the parts; these displacements lare produced at a relatively great speed, in the rm` of oscillations.` As a result of the inertia of vthe different parts of the packing, the tight face in particular 'has atendency `to lose close contact withits thrustblock surface at the-frequency of the oscillations. Leaksresult therefrom at each oscillation. These oscillations canalso be produced or aided by geometrical irregularities existing between the rubbing surfaces of the face -andof one ofthe parts, lMoreover, irregularities which may exist onthe' rubbingsurfaces other 'than these tight detrimental effect.

In 4addition to the aforesaid inconveniences which are sources of leaks, these packings are cumbersome, they impose special conditions to be considered in the plans for machines or inv stallations, theyv must be specially studiedrand i. designed :for Veach installation .and lfor their installation and their maintenance, qualified personnel is required. In any case, they cannot -be standardized, nor can they .in any case be utilized in a tight bearing.

The tight rpacking according .to the invention l remedies all of the aforesaid inconveniences.

Consequently, an object of this Vinvention is tov produce a'tight packing universally utilizable in all cases where it is .necessary to assure impermeability against the passage of gas, of liquds or ,of steam, between mechanical parts in and Vaxial play usually rtolerated in turning joints,

faces-'are also susceptible ofproducing thejsame 55 asin the case of a shaft in a smooth bearingand in the case 'of speeds of rotation ranging from yzero tothe maximum permitted by the` other machine parts', While permitting the reversing of direction of "rotation of the parts between which impermeability must be accomplished, The packing according-to the invention is also utilizable forall diameters of interior `or exteriors parts.

A further object vis to provide tight packing which can be utilized also as a protection lshutter against the ingress of impurities and of diiierent fluids harmfulbyreason of their high temperature o r their chemical action and against losses of oil etc. l

Other objects and advantages will become apparentA from the specification taken in conjunction with the accompanying drawingsv wherein:

Fig. 1 diagrams the extreme positions of oscillation in a packing, and is to be correlated to the diagram of Fig. 2;

Fig. 2 isa diagram showing the pressures exerted by the packing againstv a thrust-block'in terms of the relative axial displacements of the parts between which,impermeabilityshould be assured and contrastsy the pressuresof `the prior the diaphragm, the use of these washers being optional;

Fig. 9 illustrates in elevation and in partial axial section one form of a packing constructed according to this invention in a first use setting;

Fig. 10 is a corresponding plan view on the left half and a sectional view, following the line IU-I 0 of Fig. 9, on the right half;

Figs. 11 and 12 are similar views ofthe same packing, in a second use setting, and illustrating the reversible feature of the packing;

Fig. 13 is a View similar to Figs. 9 and 11, and illustrates a reversible packing with another type of diaphragm;

Figs. 14 and 15 are elevational views illustrating the tight faces or support faces seen on the two sides of the reversible packing of Fig. 13; and

Figs. 16 and 17 show two methods of installing the packing of Fig. 13 to illustrate its quality of reversibility according to this invention.

The packing according to the invention is based, like the prior art packings, on the application of a tight diaphragm, preferably metallic, having suflicient suppleness and a certain elasticity. Nevertheless, non-metallic diaphragms can be utilized by reason of their better qualities of suppleness and of exibility, but on condition that their mechanical, chemical and thermic qualities are suitable for the conditions of use.

However, to eliminate the inconveniences of the prior art devices, mentioned heretofore, the packing according to this invention includes neither a coil spring nor any elastic body subject to torsions and to resonance.

In the packing according to this invention, illustrated in medial section in Fig. 3, the annular diaphragm I is mounted between ltwo concentric . rings 2 and 3, xed in a tight manner on the outer and inner peripheries respectively-of the diaphragm I, this attachment being suiciently positive to prevent any possibility of relative rotation of the parts constitutingthe packing; for example, the latterisr set in these rings;

as seen in Fig. 1. These rings embody a system of convex and concentric bearing surfaces 4 and 5, respectively, on which the diaphragm rests at the time of a relative axial displacement in service, of the parts A and E between which impermeability is to be eiected, as shown in Fig. 4.

At the back of these convex bearing surfaces and the outside of the rings, the later present sur-V faces Sand S intended to act, either as tight faces or support faces, according to the variants of uses which will be explained hereinafter, which give to the packing the property of being reversible. There are shown in Fig. 4, in dotted lines and in solid lines, the two extreme positions which the tight face G and the diaphragm of the packing can take, at the time of relative axial displacements of the parts A and E which carry it, these extreme positions corresponding to a maximum oscillation A. (This is shown in more exaggerated ,fashion in Fig. 1.) As seen, the packing is mounted in the exterior part E, while in its center, it bears against a surface F of a 4 thrust-block B of the interior Vpart A, with a pressure resulting from the elastic deformation of the diaphragm and pressure P from the fluid itself. I1 the two bearing surfaces 4 and 5 were notprovided, this elastic deformation would be proportional to the force of action obviously according to Hookes law, and it would be approximately represented in the diagram of Fig. 2 by the straight dotted line C. By reason of the presence of the convex bearing faces 4 and 5 on which the diaphragm rests when it is deformed, the elastic reactions do not follow the lineal law of proportionality but they increase more rapidly, obviously in the form of a parabola, as represented by the line Co.

The convex profiles of the bearing surfaces are not necessarily the same for the two rings of the same packing, and it is not absolutely necessary to provide them on the two rings. By selecting these profiles in an appropriate manner and consideringthe initial elasticity characteristics of they diaphragmv l, one can obtain in each case the desired elastic reaction force UA, for the sudden reaction of the packing, maintaining at the same time the initial pressure against the surface F of the thrust-block B as low as possible, and determining with precision the initial point of the curve Co, that is to say, the point starting from which the elastic reactions will no longer be represented by the straight line C, but by the parabola Co. This point should be adjoining the straight line NN, corresponding to the average position (disregarding here the action of the convex bearing surfaces) very weak, against the thrustblock in comparison with the pressure Un of a coil spring. This weak average pressure is suficient to maintain the tight face in contact with its thrust-block, even withoutintervenion of the pressure P of the fluid. Thus, too great support pressures of the tight face against the thrust-l block are avoided when not necessary.

`By the fact that such a weak laverage sure is used, the fluid itself, for which impermeability should be realized, is permitted to exert by its own pressure P acting on the whole surface of the diaphragm, the necessary pressurel exaggerated to make it clearer, as shown by com-j parison of -the value of A on this figure and in- Fig. 4. AAThere is also seen in the diagram on an exaggerated scale in asimilar manner lthe length K representing the deformation average dip) of the packing from its position before'in-f.

stallation to its average ,positionv following-the line NN, a length which appears alsojinFig. 3,5

andere f5 4butobviously in its actual size.Y The displace-- ment K thus deflned as elastic .average dip iis then toy be .considered as determinant length-of .the elasticreactionv r., .tha'tis' to sayfof the initial pressure against the thrust-block', supposing the pressure :of fluids .equal .to zero.

By simple comparison .of the prior :art packings with the packing of this invention, it is `seen l.that .the omission of thefcoi'lA spring permits conf siderablereduction of the' I'dimensions (and :con lseqnently'all :o'f the masses` 'ofthe .packing and iti-particular of the .tight v face "whichireduces "zthel-aeifectfof all :of 'the' detrimental kinetic precision the important Vtorgive certain initial charactersticsto the-dia'- phragmwith regard'to its .':elasticit'y andgto obtain'theudesiredresult, it :maybe necessary to 'reiniorce 'thev diaphragm by 'the aid of one or two or several elastic washers such `as shown in Figs. 5 to 8. These Washers are mounted on opeside for the other, o-r on bot-h sides, on the interior periphery or on thefexterior periphery, as the casemay be. The use of vsuch Washers is particularly "desirable when using very thin or non-'metallic diaphragms. f

neither .thev .diaphragm itself, nor its isujp port washers are subject' to elastic tors'ions' (as inthe-case Uffa coil spring.) ,there i's no tangential. V."chattering of the tight .face on fthe thrusftfbloek surface. vThey `do not .give rise 4eitherfto 'phenomena of axialresonance', which suppresses all of the cause of leaks due tothese two phenomena.

'llhesudden reaction lof the packing due'ito the kpara-bolio form -of `the curve Cn, 'as diagrammed 'i-4 Vig.v 2, gives the veryrfavorable possib ,tif of using l'such a packing 'also as 'an automatic valve,

whether the parts A and E are in relative rota- 'i' tion movement or whether they are arrested.

For the same reason, it always acts as a very energetic centering element by the fact that it energetically opposes itself to the relative axial? oscillations between the parts A and E, due to the rapid movement of these parts and alsov to the fact that it tends clearly to reduce to the minimum the amplitude of these oscillations. In this manner, the packing acts at the saine time as an elastic stop-buier forming part of the bearing (whilerassuring the impermeability), and can be employed solely for this purpose.'V

Moreover, it can be employed as an elementfor taking up the play between the different me-` chanical parts, as an elastic spacing ring, etc.

inasmuch as such a packing can have smalti' packing is attached, and in solid lines, the partV carrying the thrust-block. The purpose of these methods of designation and of illustration is'l to show more clearly the reversibility of the packing.v

For greater clarity, and with the purpose of giving to the designations NN and K employed on the graph of Fig. 2, a concrete significance in the simple-st possible manner, -niee fi'sjfrepre'- 'senteatn rigs. :it and .-ri, the tight-surface F for vthe thrust-"clock B and the support surface l'c 'in 'the same plane* NN, 'the'p'la-ne NN always represenlting the average position between Ithe 'two extreme points of relative'axialdisplacement 'of lthe parts AfandE 1in the course of their possible oscillations '-'oamplitude -A, Vand Irepressenti'ng` ait fthe {same time the initial' average position, start?- ing from which the average las'ticdipordisplacement Koi the packing 'i's'ffcounted f' In Figs. Sand" lll, `arialogons arrangements Shave been" represented -w'iilfi relation t the plane Neverthelessjit vijsvt'o be noted that', for'exception'al reasons', the Ysurface `F 'should 'no't necessarily always' be in the same plane' lNN asthe surface e. `The diaphragm constructed vr'according tothi's invention `can have fthe `most diverse forms al4- though only twoare shown ifn-'the "drawings Moreover, the diaphragm can be madelof'fasingle washer vor' of several, 'of' the same proiefo-n of `different profiles, superimposed 'in a bundle.V

I-n Figs. V9 and 1'0, va iirst use setting of ka pack ing made according to the invention, has Abeen shown. The thrust-block B is shown there, "cariried by `the interior `part A, while the packing is attached in a tight manner von the exterior partI 'It is seen that the diaphragm properly speaking (which is represented for Vreasonsffo simplicity in the form of a flat washer) "is vsup'- ported, o'nboth sides, by an'interior spring washer 'L and by an exterior spring Washer L.

To assure perfect impermeab'ilty and ynot only vbetween the face G and the'surface of thrustblock B, the diaphragm I should itself be mounted 'in a '-ti'ght'manner in the rings, to "preventV any *possibili-ty'of relative rotation between the exterior and interior rings. This mounting can be vd'on'e by the setting shown, or in any 1othermanner. To facilitate the setting, two auxiliary rings T and T', of tempered steel, can be used, the form of which can vary according to the forms of the diaphragm. Thewashers L and L' are mounted and set together with the diaphragm. They rei inforce the diaphragm and they complete, if that is necessary, its characteristics of elasticity by modifying them at will according to their dimensions. The form of the washers L and L' can vary with the form of the diaphragm and according to other requirements.

For greater simplicity, in Fig. 9 the convex bearing surfaces 4 and 5 have been shown as being arcs of a circle of radii n, but these curves could be others and may be different for the two bearing surfaces, according to the desired packing characteristics, but it is necessary, however, that the support faces or tight faces S and S' of the rings 2 and 3 be arranged back of these con- Vex bearing surfaces.

The second use setting, illustrated in Figs. 11 and 12, presents appreciably the same characteristics as the device of Figs. 9 and 10, except that the thrust-block B is provided on the outer part E and that the packing is attached, in a tight manner, on the inner part A, this being possible since the packing is reversible.

In Figs. 14 and 15, it is seen that the tight faces S and S of packing of Fig. 13 can include grooves s permitting lubrication.

Fig. 13 shows a similar packing which may be mounted on the device of Fig. 16 by attachment in the seat of the outer part E while the inner ring bears by its face S on the surface'F of thrust-block B of the inner part A. When the packing is mounted in the device of Fig. 17 the the packing itself.

relationship is reversed. It is seen in Fig. 13 that the displacement K, dimension determining with relation to NN, thepinitial pressure, and

number of examples of how the reversible pack'- ing' of this invention might be used it is clear that'the objectives claimed for the packing have been attained. Numerous additional methods of using the packing will suggest themselves to those skilled in the art as will structural variations in I therefore desire, by the following claims, to include within thescope of the invention all such variations and modications by which substantially the results of my invention may be obtained through the use of substantially the same or equivalent'means.

claimz 1. A reversible packing of the type sealing between inner and outer machine members having relative rotational movement and which may be displaced slightly axially andv angularly relative to each other, including in combination two concentric rings having on their outer sides tight faces engageable, respectively, with themachine members, at least one elastic .diaphragm extending between said rings and held in a tight and relatively non-rotational manner in each of said rings, and at least one of said rings having a convex bearing surface on its inner face against which said diaphragm is adapted toV come more or less into contact as said diaphragm is axially elastically deformed by axial displacement of the machine parts and pressure exerted on the face of the diaphragm, the packing being mounted 4under tension by axial elastic deformation of said diaphragm, and the curvaturey of said -convex bearing surface being such that as said elastic diaphragm, as a result of the axial displacement of the machine members and the pressure acting on the diaphragm face, comes into contact with a greater amount of the area thereof the pressure exerted by the packing tight faces and the machine members increases parabolically.

2. A reversible packing as claimed in claim 1 wherein the inner faces of both said concentric rings are provided with convex bearing surfaces the curvature of which causes the pressure ex-r erted by the packing tight faces on the machine members to increase parabolically as a'greater amount of the area of said diaphragm comes in contact with said bearing surfaces.

3. A reversible packing as claimed in claim 1 including atleast one elastic washer interposed between said diaphragm and said convex bearing surface and held within said diaphragm in that ring having said convex bearing surface.

STOJIMIR DOBROSAVLJEVI.

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

UNITED STATES PATENTS

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