US2149294A - Hydraulic pistion packing - Google Patents

Description

- March 7, 1939. f

w. F. HucK 2,149,294

HYDRAULIC PISTON PACKING Filed sept. 3o, 195e 4 9 17./.97/4 v/8v *y /8 i 2f Iil III INVENTOR.

AT TY.

30, same for all uid'pressures whereby, under light Y, This invention relates lto pistons and-packing l rings therefor andvmore particularly to a piston Pistons for and its packing ring whichis adapted for reciprocation in the cylinders of a hydraullcpre'ss or the like. u .f

use with the cylinders oil hydraulic V presses and other mechanisms wherein comparatively highfuid pressures are :used are'usually provided with pistonfrings orA packingfsuitably formed and arranged to insure the sealing ofthe space'between the piston and the cylinder walls.

.` In someinstances split metallic ringsfare provided, lthe inherentV resilience of which, presses ythem Voutwardly against the cylinder wal1,in` other r instances auiriliary pressure lapplying means is Provided, and in' others the fluid pressure itself'is used to expand vthe split ring orrings. Aside from the use of metallic 'rings for piston packing, leather;` rubber, and composition materialjhasv been used to-advantage in pumpsl and other combined y pistoni cylinder devices. f Y

Many of the above forms-have oneor more y of the following disadvantages; lthe surface in .Contact against the cylinder'rwall creates too much pressure,v either causingfwearywhich, when split rings are used maybecome uneven,` eventually wearlngfthe cylinder ovfal in shape, or considerable friction, Ywhich`clecreases the efciency of the deil vice; ther area of 'the contacting surface is the pressures, tlie efficiency ofthe piston and cylinder isfactorily von small diam under high pressures, the' eealis not sufficient and leakage past the pistonuoccurs.

Piston rings ork piston packing of Vrubber or fibrous material have been used morejor less sateterfpistona such as are used in hand pumps andthe like. These are generally in the form of a ring, the outer free llp fof which is, in some instances, pressedagainst the cylinder wall byiluidjpressure, and in ,others by auxiliaryvexpanding means. It has been found, however, that. such material is not eflicient for usewlthpistons and cylinders designed for comparatively high pressuresand which yare substantially large in diameter. 'Even though possibly' acting to seal lthe space between the ypiston Vand cylinder when flrstappliedgpackingof the above Vnature rapidly'wear's or becomes distorted, forinstance, by curling at its free`edge,.and soon Vis yuseless for the purpose intended. Metallic split fringsjhavetherefore come into general use 'for L` thefabcve purpose, but if not properly formed land applied, these split metallic rings or packing vtrflltflioe & Co.,XInc., New York, N i f' Y w n prartion ofvNr'evvtYmik .rfn A' y. I as [l g t, Q Application september 3o, 1936', serial No. 103,32?)

often lprc've:inefficient for I iifinclude those pointed out,a.bo ve.,;l i

- One ofthe principalobjects of this inventionuis the provision of la metallic,packingor ring for .a

piston: of hydraulic and,like presses ,;k which .will

fbe ilexiblein use, in that the cylinder Wallcorftasting area will be automatically proportioned'in accordance with the pressure applied, v.whfkreby .undue wear, andineiiicient operation vvitllbe substantially overcome.y

Another object is to provide a vinevtallic piston packing, which is of"'generally,in

verted U shape incrosss`ectionandwhereinthe arms of this il, are propor'tionedvlin tliicl'nesks` r to permit expansion of `the ring tocauseth'e" portion thereof in contact 'with the cylinder walhftdbe area of y Another Objectis to 4the parts or iav."clecr'eiaisey 1n the' thereof, f

moved into closerQcontactQby the' vfluid pressure vided vwith suflcientfresiliericy to 'insure constent c`ont'afctLof its `freeedge`w1th e" cylinder wall, under; comparatively low 'dpressures,1, and which asA the', fluid pressure `increases;will contact .over a constantly increasing area', fro1nr y the free-edge thereof alongthecylinderwall, the V'proportion betweenthe pressure andthe area being determined, to permitfsubstantially,perfect 'i sealing. at minimum sealing pressure andfto permit the area oficon'tacttoincreaseasV the pressure increases without causing undue wear uponilicient operation Further objects of' this;y invention includethe 'ngring'orlpa'ckn x l ressture uponthe* cylinder wall aboutv its entire.' periphery the" provision of vnovel means' to detachably' securethis packing to the head end v of a pistonfthefprovisfion of centering;k means to'faci1itat'enrance ofthe 45 I piston with its packing into acylinder; andthe rovisicn, in combinationwithjthe `fo,regoin'g'elements, of a centering 'platef'r the same by vwhich it is substantially iloatablysecured to the piston head. n y I y,

It is also an object of the invention toprof vide a piston and apackingv ring which is adapted for reciprocation` inthe cylinder( of a hydraulic press or the like, of generally improved/construction, whereby the saine will be slrnplafdurableand inexpensive in construction, as well as convenient, practical, serviceable and efficient in its use.

the foregoing and other objects in view, which will appear as the description proceeds, the invention resides in the combination and arrangement of parts, and in the details of construction hereinafter described and claimed.

The preferred embodiment of the invention is illustrated in the accompanying drawing, wherein:

Figure 1 is a transverse section through a portion of a cylinder, piston and packing therefor, embodying the features of this invention;

Figure 2 is an enlarged section of a portion of.

the section shown in Figure 1; and

Figure 3 is an enlarged transverse section of a portionv of another form of cylinder, piston and packing therefor.

l The forms of the invention illustrated differ, primarily, in that the one shown in Figures land 2 has ,auxiliary spring actuated means to assist in pressing a portion of the packing against the cylinder wall and that the packing portion, sok acted upon, is relatively longer than the corresponding portion of the packing of the form shown in Figure 3. Otherwise the features of this invention are equally applicable to both forms. In the fol- 4 lowing description the term, fluid pressure, is to be understood to include pressure applied by means of compressed air, gas or liquids, including oil, water or molten metal.

A cylinder II, having its bore I2 connected to a suitable source of fluid pressure by a port I3, has a piston I4 disposed therein for free reciprocating movement between its walls I5. The: port I3 may serve as an inlet and exhaust port and is shown in communication with the cylinder bore I2 between the cylinder head I6 and the piston I4. The head end of the piston I4 is clrcularly recessed as at I1 and a circular plate I8 ls disposed in the recess I1. The plate I8 is adapted to freely slide longitudinally in the recess I1 and rest against the recessed surfacel I9, a bolt 2| 'being provided to prevent the plate I8 from entirely moving out of the recess, it being understood that fluid pressure imposed against the end face of the plate I8 normally holds it in the recess I1 firmly against the recessed surface I9. The plate |18 has a circular raised portion 22 upon its outwardly facing surface, which is of smaller` diameter than the plate I8 thereby providing an annular longitudinally directed shoulder v23 and an annular laterally disposed seat 24.

A metallic piston ring or packing 25, generally inverted U shaped in cross-section, and having'a laterally disposed inwardly directed annular flange 26 is provided. The internal diameter of the ange 26 is of proper dimension to snugly fit about the shoulder 23 of the raised portion 22 of the plate: I8, whereby the ring 25 is centered in respect to the plate I8 and, through it, in respect to the piston I4. Between one face'of the flange 26 and the seat 24 of the plate I8, a gasket 21 may be disposed, and an annular member 28 is placed upon the other face of the ange 26. Screws 29, passed through the member 28, the flange 26, and the gasket 21, thread into the plate I8 and securely clamp these parts thereto. The internal diameter of the member 28 also snugly nts about the shoulder 23 and the member 28 is centered thereby.

Referring now to the form shown in Figures 1 vand 2, the aange portion 2s or the piston ring 25 extends laterally from' onev arm 3 I, of the inverted U cross-sectional shape thereof, which arm 3| extends in snug contact with and along the circumferential surface of the plate I8, toward the piston wall I9. The curved portion 32 of the inverted U cross-sectional shape curves over and outwardly toward the cylinder wall I5, being spaced from the end of the piston Wall I9fa determined amount. The other arm 33 of the inverted U cross-sectional shape, is longer than the arm 3| -and extends away from the end of the piston wall I9 along, and in contact with, the cylinder wall I5. The end of the arm 33 is provided with an inclined inner surface 34 against which a correspondingly inclined outer surface 35 of a ring yshaped expander 36 is constantly pressed. The

expander 36 is provided with an annular body .portion 31 about which, at suitable intervals, is

disposed pockets 38, in each of which is a., spring 39. 'I'he springs 39 are arranged to react between the inner ends of the pockets 38 and the opposing surface 4I of the members 28 to constantly cause the inclined surface 35 to press the end of the arm 33 outwardly and tightly against the 'adjacent cylinder wall. Herein the body portion 31 of the expander 36 is disposed between the arms 3| and 33 of the inverted U cross-sectional shaped portion of the piston ring 25.

It will be understood when referring to the arms 3| and 33, that reference is made to the sides of the U cross-sectional shaped portions of the piston ring 25 and that these arms are each the cross-section of cylindricalmembers, which are connected by the annular portion, which is referred to above as being the curved portion 32. The metallic material, of which the ring 25 is made,A is preferably inherently resilient and is bent away from the outer periphery of the flange 26 to form the portion 3|, then folded over to form the portion 32, and then bent toward the flange 2,6 substantially parallel with the portion 3| to formwthe portion 33, the outer surface of which is preferably ground to fit the internal diameter of the cylinder I I.

The material constituting the flange 26 is of a determined thickness whereby it is of sufficient strength to resist bending adjacent the portion 3| when in normal use. The thickness of the material constituting the portion 3| is of a determined dimension whereby it will be maintained against the circumferential surface of the plate I8 during normal use, due to its stiffness. From the portion 3| from which the curved portion 32 extends, the material is gradually tapered or thinned to a smaller dimension adjacent the portion 33. y

The thickness of the material of the portion 32 is determined to be sufficient to permit slight bending or ,elongation of the curve laterally adjacent the portion 33, but is proportioned to prevent excessive elongation of the curve longitudinally with respect to the cylinder II, whereby it might engage with the end surface 19 of the piston I4 from which it is spaced. Fromwhere the portion 32 is adjacent the portion 33, the material constituting portion 33 is gradually tapered or thinned to the free end 46 thereof whereat vit is slightly enlarged to form a rib 41, upon the internal surface of which the inclined surface 34 is formed. The thickness of the material of the portion 33 is determined to be suflicient to insure expansion of the free end 46 into close sealing contact with the cylinder wall I5 by the inherent resiliency thereof, being assisted by the expander 36, which'is provided to act as an auxiliary expanding means to insure tight sealing between the ring end 48 and the cylinder wall yI5, to preventuid under pressure leaking therebetween, and to reinforce the free end 45 vduring the assembly of the. piston into the,v cylinder Il. Herein,as shown in Figures 1 and 2, the space 48 between the portions 3| and 33 is connected with the uid under pressure, due to the expander body 41 being spaced from the annular member '28and theportion 3|. v I

` Referring to the' forml show-n in Figure 3, the piston ring 49 is4 formed of inherently resilient metallic' material in the same manner as the ring 25, of the form shown in Figures 1 and 2. The ring 49,'however, does not have the free end 5| of the4 folded over portion 53 extended beyond its flange 54 and n'o rib nor inclined surface is proe vided.- In this form the portions 52 and 53 are connected by a curved portion 55. In this instance, thenatural inherent resiliency of the Amaterial is relied upon, due to the formation of 420 the component portions of the ring 49 to maintain the free end 5I Vthereof in close sealing'engagement withthe cylinder walll |5, and, therefore, fno auxiliary expandingmeans is provided.

An annular member 56 is provided and isl disu posed upon the flange 54 of the 4ring 49V to clamp the ring to the plate I8 by means of screws 57|,

as in the previously described form; The member 5B, however, differs from the. member 28 in that it extends-fully across the cylinder llinto 30 close relationship with the.v wan I5 tneeef 4and suitable openings 58 are provided, 'spaced at intervals to permit the nuid.- under pressure, to'

flow into the .space y5||^btween the portions 5 2 and 53. Themember 56 by overhanging the free 351 Yend 5|*of the portion 53 protects it, aswell as as- A sists in .centering the piston, as it is assembled li'fintothecylinder II.-

"'f-Due to the particular vformation of the piston f-*"ringsy25' and 49, as above described in respect to "the'r`ing 25,- it being understood' that vboth are similarly formed with the exception that the rib 41 on the ring 25 with its inclined surface'34 and ,45 theV device is in operation., When fluid under pressure is admitted-through the port I3 into the cylinder I I, between its head I6 and the piston I4, the pressure theneof is imposed upon the end of the piston through the plate I8 and upon the ring 25 or 49, by the admission of uid under pressure, into either the space .43 or 59 between the portions 3| and 33 orthe` portions 52 and 53, as the 'case may be.- Due to the inherent resiliency of` 55 the portion 33 of vthe ring 25 with the assistance `of the expander 36 and the inherent resiliency 4of the portion 53 of the ling 49, the rings 25 and 49 respectively,y are sealed against .fluid leakage between the same and the cylinder wall I5, and

60 theApiston |4 will be moved inthe cylinder I.`

' In pressure operated devices, such as hydraulic presses, `the lpressure upon the piston to moveit I during most of its stroke is less than the pressure required when'the press is operating to compress -65 the produce being acted upon and, therefore, only needs to be sufficient to overcome the weight of Athe piston'andthefriction between the movable parts of the press.l Under these conditions, the

75'within the respective spaces 48 and 59 tends to free edges thereof will be understood to be mathevcross-section with the arms of the U shape -taexpand the respective ring and separate the respective POrtions 3| and 33 or 52 and 53.

'I'he formation of the rings 25 and 49, as above described, with the portions 3| and 52 of suincient thickness to prevent bendingor stretching 5 movement; forming the respective portions 32 and by gradually tapering them in thickness between their respective jointures with the portions 3| .and 33 or 52 and 53, to insure a tapering bending tendency thereto; and forming the por- 10 tions 33-and 53 by gradually tapering them in thickness from their connections to their free end; results in the free end being increasingly pressed against the cylinder wall I5 upon the application of increasing pressures, and the contact- 16 ing area thereof increasing in proportion to the increase in the applied pressure. Due to this formation of the rings 25 and 49, the tendency to separate the portions 3| and 33 or 52 and 53, when the pressure increases, results in a move- 20 ment of the portions 33 and 53 into closer Contact with Athe cylinder wall I5, which contact gradually extends iniarea from the free end of the respective member toward vthe piston. In this manner the piston rings 25 and 49 are automatically 25 contacted against the cylinder wall I5 over gradually increasing area from the free ends of each,

"which from the beginning, are constantly in con tact with the cylinder wall, in accordance with, and proportional to, increases in pressure, and 30 without any disproportionate increasein friction,

.the friction only increasing as the area of contact increases. Thus, under low initial pressure,

vring securing means and the combined elements asabove described in the structure of a piston 45 and piston ring combination are also conducive toward the efficiency of the device. The determined amount'of taper given to the rings 25 and 49 from the respective Iflanges 26 and 54 to the 50 matically determined to cause the results above described, and the respective rings may be termed as being either substantially inverted U shape in pered in thickness a determined amount or, as 55 being of 'material in hollow cylindrical form, the waliof which is tapered a determined amount from one edge to the other, with one portion folded over the other andspaced therefrom. The rings may also be defined as being constituted by joined together superimposed hollow tapered Wall cylindrical members, the wall of the outer memvber being thinner than that of the inner member andtapered a determined amount.

It will be understood that the invention may be embodied in other specific forms without departing from the spirit or essential attributes thereof, and it is therefore desired that the present embodiment be considered in all respects as illustrative and not restrictive, and it will be further understood that each and every novel feature and combination present in or possessed by the mechanism herein disclosed. forms a part of the invention included in this application.

What I claim is:

1. In combination, a piston, a cylinder in which said piston is disposed, a plate disposed upon the end face of said piston, a metallic piston ring having an annular member disposed upon said plate, and an annular part, generally inverted U shape in cross-section, extending from and about the periphery of said member with one of the arm portions of the U shape extending over and about the periphery of said plate, with the curved base portion thereof extended toward and spaced from the end face of said piston, and with the other arm portion of the U shape extending along and in contact with the adjacent wall of said cylinder, a flat annular plate disposed upon said annular member of said ring and extending over and free from contact with said U shaped part into close proximity with the wall of said cylinder and adapted to allow fluid under pressure to be received in the U shaped part between the aforesaid arm portions thereof, means to clamp said annular plate and said 'annular member to said plate, and means to secure said plate to the end face of said piston. l

2. In combination, a piston having a circular recess in its end face, a cylinder in which said piston is disposed, a circiilar plate disposed in the aforesaid recess and extending axially outwardly from the end face of said piston, a metallic piston ring having an annular flange, said flange being disposed upon and secured to said plate, a hollow cylindrical member extending from the outer periphery of said flange toward the end face of said piston, about and in contact with the periphery of said plate, another hollow cylindrical member spaced from and overlying the first member, and in contact with the wall of said cylinder, and a curved annular member spaced from the end face of said piston and connecting said members adjacent the end face of said piston.

3. In combination, a piston having a circular recess in its end face, a cylinder in which said piston is disposed, a circular plate disposed in the aforesaid recess and extending axially outwardly from the'end face of said piston, a metallic piston, ring having an annular flange, said flange being disposed upon and secured to said plate. a hollow cylindrical member extending from the outer periphery of said flange toward the end face of said piston, about and in contact with the periphery of said plate, another hollow cylindrical member spaced from and overlying the rst member, and in contact with the wall of said cylinder, and a curved annular member spaced from the end face of said piston and connecting said members adjacent the end face of said piston, the walls of said second hollow cylindrical Ymember and of said curved annular member, being tapered in thickness a determined amount from the jointure of said curved member with said first cylindrical member to the free end of .said second cylindrical member.

4. In combination, a piston reciprocable in a cylinder, a piston ring of resilient metal having component portions including, a cylinder wall engaging first portion, hollow cylindrical in form, a piston engaging second portion disposed within said rst portion and being hollow cylindrical in form and integrally connected in union with the first portion by a curved annular third portion,

g the walls of said first and third portions being of said first and third portions being so proportioned as to permit ex'pansion of the ring to cause the area of contact of said first portion with the cylinder wall to be increased in direct proportion to the iluid pressure imposed thereon, and an annular flat member integrally formed with, extending about and from, the inner periphery of said second portion to secure the piston ring to the end of said piston.

5. A packing ring of resilient metal for a piston or the like, comprising component portions consisting of a rst and outer cylindrical hollow portion having a substantially straight outer periphery` adapted to lie flat against a cylindrical surface. an inner cylindrical hollow portion within the first portion and having substantially straight parallel inner and outer peripheral surfaces, and a connecting portion substantially semi-circular in cross section, said connecting portion and said outer cylindrical portion being respectively reduced a determined amount in wall thickness from the thickness of the wallof said inner cylindrical portion at its point of connection with the connecting portion to-thef` freeedge of said outer cylindrical portion, the'reducti'on in thickness of said connectingportion and lsaid outer cylindrical portion being so proportioned thatffluid pressure imposed `against the'ring between A,the inner 4andv outer portions will spring the outer portion outwardly, and laterally elongate the connecting portion to increase the area of 'contact of the outer portion uponthe wall of a 'cylinder' or the like in direct proportion to the pressure so imposed.

6. A packing ring of resilient metal for a piston or the like, comprising .component portions consisting of a rst and outer cylindrical hollow portion having a substantially straight outer periphery adapted to lie flat against a cylindrical surface, an inner cylindrical .hollow portion within the first portion and having substantially straight parallel inner and outer peripheral surfaces, 'and a connecting portion substantially semi-circular in cross section, said connecting portion and said outer cylindrical portion being respectively reduced a determined amount in wall thickness from the thickness of the wall of said inner cylindrical portion at its point of connection with the connecting portion to the free edge of said outer cylindrical portion, the reduction in thickness of said connecting portion and said outer cylindrical portion being so proportioned that fluid pressure imposed against the ring between t-he inner and outer portions will spring the outer portion outwardly, and laterally elongate the connecting portion to increase the area of contact of the outer portion upon the wall of a cylinder or the like in direct proportion to the pressure so imposed, and an annular flat ring shaped portion extending about and from the inner periphery of said inner cylindrical portion substantially at right angles thereto, whereby the packing ring may be secured to the end surface of a piston or the like.

'7. In combination, a piston reciprocable. in a cylinder, a piston ring of resilient metal having component portions including, a cylinder wall engaging first portion hollow cylindrical in form, a hollow cylindrical second portion disposed Within the first portion connected to the piston and being connected to the irst portion by a curved annular third portion, the walls of said first and third portions being gradually reduced in thickness from the point of connection of said third portion with said second portion to the free edge of said rst portion, the amount of such reducyns tion in wall thickness being proportioned to cause a variation in the area of contact of the first portion with the cylinder wall in direct proportion to the uid pressure imposed upon the ring between the rst and second portions thereof.

8. In combination, a piston, a circular plate mounted on the end of said piston and having a raised portion upon its outwardly facing surface of smaller diameter than said plate, a hollow piston ring seated upon said plate and surrounding said raised portion thereof to be centered thereby in respect to said piston, said ring being made of resilient metal and having a rst portion surrounding said plate and directed toward the end of said piston, a second portion hollow cylindrical in form surrounding and spaced from the first portion and extending toward the piston end, and a third portion integrally connecting said first and second portions adjacent the piston end but being spaced therefrom, said second and third portions being tapered by a reduction in wall thickness from the rst portion to the free end of said second portion, the reduction in thickness of the walls of said second and third portions being proportioned to insure that the area of contact of said second portion with the cylinder wall will vary in direct proportion with the uid pressure imposed thereon between said rst and second portions.

WILLIAMF. HUCK. u

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