US892620A - Packing. - Google Patents

Description

. 25 tion sections JOHN ij. RANDERSON, OF ALBANY, NEW YORK.

PAGKNG.

Specification of Letters Potent.

rammed July 7, 190s.

Application flied. December 19, 1907. Serial No. 407,217.

To all whom it may concern:

.Be itknown that I, JOHN P. RANDERSON, a citizen of the United States, residingy in the city of Albany, in the. Stets of New York,

have invented certain new undv useful Improvementsin Psickings, of which the followiii/Iiss specification.

'h y present invention relntes to pnckings, especially forl pistons of fluid-pressure engines such as steam, water, gas or air motors,

although in sonic forms it may bc applied to stuffing-boxes.

One ,of the best known of the ordinary piston packings is the so-called Dunbar, coni'sisting of interineshing packingiings cut into sections which nrs-zik joints so that steam I cannot blow through; these are hold in place by the live steam, which has uiircstrictml access to their rear faces and nrcsscs thcm out against theI inside sui'ffice ol thc cylindcr.

This formis uit-e oid and thouffhcxtensivol used is subject to several defects; the exccss- We pressure ot' thc Asteam causcs it to waste considerable lpower in friction, while in addileaf springs nrc used in rcnr of the,packing-riiigs, which imike them hard lo get lntblplace and tend to tilt the sections, thus o ching the ,ioints so that there is a lcakage o steam. The most sci-ions dci'oct in 3,6 this packing, however, is one that is common to all of those devices in which unrc 'stricted steam pressure is uscd to kccp the rmgs 1n close contact with thc cyhndcr, that i's,`that such packings tend to woor thel cylin- 85 der more in theiniddle than at thc ends.

This is because, after the piston hns piisscd the middle of 'the cylinder, the eut-oil acts and the pressure gradually diminishes until theexhaust opens. The efl'cct of this is that 40 only a certain part of the middleol the cylinder is traversed in both .lircctions bythe piston with steam et or about full pressure, so that the cylinder gradually becomes barrclshaped and the consequent radial movement 4 5 of the psckingwings under the varyingY stennbpressure at diicrcnt parts of thc stroke causes them to weer loosc so that thc piston soonleaksmieiiinwrcliairbillslargc. Another defect of the'oldyiistoh-lnickinifs has been yhilit'liat Where' the engine was double-acting, as

`is usually the case with steam-engines, the bull-ring or dividing-ring between the two sets of pecking-rings is npt to corrode 1n place, and this renders it -vcry difficult to get it out to inake necessary rc1-uurs, since thc entire under surface adheres to thc body ol' the iston, which often must bc taken out sind 1heated to extract thc ring. Commonly a 'lrin'g or ring of T-slnipcd cross-soction is employed as zi bull-ring', This is a further disadvantage, in that itis ncccssnry to put in the bull-ringsr bcl'ore thc rest of thc 'packing` cnn bc asscmbled, and this makes it very diliicult indeed to asscmblc the split rings upon the inner side (the sido away from thc incchanic) oll thc bull-ring. wWhilc not so diilicult vfhcrc a vcrtical cylinder is employed bccniiso thcro the piston can bo raised, even thon, .vhcrc springs arc used behind thc. split rings, it becomes troublesome; the least inzu-curncy ol' procedure is apt to lodge sonic wart oi' thc packing-rings in thc ports, whence it is diilcult to extract it. Sometimes it bccomcs ncccssary to tako the cylinder oil' thc frame to do so,

The first dillicnlty nanicd above l obvinto-by iitting to thc piston sectional pucking-rings breaking joints, and making a closc working tit 1n grooves in thc piston; and placing behind the packing-rings an expanding ring, also making n working' iit with thc groovc in which thc packing-rings -iit and provided with lubrication fire insuilicicnt to cnablc thc p'rcssurc in the con fined space between thc bucking-ring and the piston to vary freely as. thc pressure in thc cylinder varies during the travel of the iston.v A certain avcrage pressure, thereore, is for all practical purposcs'stendily nniiii'taincd against thc packing-rings while the engine is running, this avcra f c being obviously' somewhat below the ful boilerpressure, but above thc pressure to which the steam expands after the cut-oil acts. The eiiect of this arrangement is to maintain a substantiiilly uniform and constant friction between the wallsof the cylinder and the packing-rin s at all parts of the stroke, sov far as t e fluid pressure is concerned. In conjunction with -this the expanding ring to which l refer is so arranged, 'as

presently to be pointed out, that its cenhaving it rest upon a circumtmentiall shoulder'in .the body of the piston. ',B'y this constructlon the iirst set ot' packing-rings, with the,eXpanding-rings behind them, may

be put in place before the bull-ring ais inserted;.

i after-,this latter ring is in placellpesecond set of lpackinglrin s necessary iif'a doubleacting piston may e put in place and a'faceplate secured upon the piston. on the piston is turned to a close fit with the inner periphery of the bull-ring, so that when it is necessary to take down the ap,- aratus a sim le tap of the hammer will so oosen the bu l-rin thatl it may readily be lifted out. .The s oulder may he turned upon the inner peri hery of the bull-ring it desired, -but genera ly the piston is better and easier to manage.

Expanding rings have Abeen used in the rear of the sectional packing-rings in order to kee the latter in lace, but heretofore these rave generally een formed of steel and have been tempered in'order to make them hold up to their Work. The dil'liculty with this, however, is that the constant passage of the hot steam or gas through the cylinder draws the temper of the expanding rlng so that i-t loses its elasticity and fails to serve its purpose.

. The defect named is peculiarly evident in explosion engines, and particularly in those in which the compression is carried to a' high oint, so that the explosion generates great eat. In fact, thepistons of modern gasengines are often run almost red hot or at least at very high temperatures, and as no practical provision can be made for coolingthem as is done with the cylinder, there is very great friction With the cylinder walls, which do not expand proportionately. In additionthe variations of pressure in a .wasengine cylinder are very much greater t ian in the steam cylinder, and the drop is proportionately greater in the latter part of the stroke. The consequence of this is that gasengine cylinders often wear into peculiar shapes and are very difficult to lreep in order, sometimes leaking so badly as to lose a consid The shoulder seaeao erable part of the power generated by the caf es plosion. ln place of the steel, therefore, l use a substantial ring or" cast-iron, the expansion of which may be adjusted readily and Which when once adjusted will not change in this respect at the temperatures in which it is ordinarily employed. Further, if it should become necessary to cause the ring to ex andy a little more, so as 'to engage the pac .l rings more lirrnly with the surface of theirq cylinder and thus compensater for Wear, the rings may be slightl sprung with a ballpeen hammer, enou to take u any Wear which can occur in te packing W ch I- have devised.

Paclng-rings have heretofore been heldrlc in relative circumferential position by pins 5 secured in one of them and iitting'into seeliets in the other. `lll/ith this construction it is necessary 'to provide a little lost motion between the vpin and socket, otherwise the f sections ma y tilt upon the pins, opening the joints'and allowing steam to leal; past the packing; it the pin be made tight enough to prevent this the joint binds and the ring sometimes fails to expand pro erly se that contact between it and the cy inder isrot lsufficiently tight. To obviate this di'llculty I provide an abutment upon one of the pack/f." ing rings, substantially of the same crosssection as the other ring or rings which 1t protects against relative circumferential ino.- tion. In practice l have found this to be a complete remedy. An additional advantage is that the abutment may be of a size to comu pensate for the space lost by the saw-kerfs which divide the packing rings, lree ing the latter tighter than is possible with t 1e pins.l

The accompanying drawings show an env bodinient of m invention as applied to a double-acting piston used in a steam-engine. Obviously to apply the saine construction to a stulling-box or gland it would be necessary f to reverse the direction of concavity.

Figure l represents a central cross-section, partly in side elevation, of a piston provided with niy improved packing; and Fig. il 1s an end elevation of such a piston.

In the drawings, A is the piston, and B is the face late, which is held in place by the bolts G,

C is the bull-ring, of m-shaped erf-ass sec tion as shown; the ortion c being arranged to engage i'irnilv Wit the piston A and faceplate B when the bolts`are drawn tight. In the drawings the ring is shown as flush with the diameter of the piston, but it may be made, as is usual, slightly relieved so that it will not touch -the cylinder. A shoulder a is turned upon the piston, against. which the bottoni of the bull-ringrests with a close tit, so that it adjusts itself in position by simply pressing it into place.

l?, l! are paclnngrings of gnoinon-shaped cross-section, one of the longer sides of which ployed.

is turned towards the steam pressure, that is, in case of the ring D toward the face-plate B, and in case of the ring Dl toward the iston A, from which directions respective y the pressure of steam comes in the dou ble-acting engine. hComplementing the ring D D1 to form rectangles in' cross-section are the rings E E1; the two sets of rings break joints, as iscusternary in devices of this character; and to preserve their relative circumferential position the abutment H (see Fig. 2), is ein- This abutment is of the same size as the cross-section of the ring E, so that it completes thev circle formed by that ring, and is o sufficient are to compensate for the shortening of the rings E El by the saw-karts. In the rear of the rings D D* are springs F F1. These are repared from complete cast-iron rings of substantial thickness; inthe engine vfrom which the drawings are prepared, which is of 10 bo re, these rings are about 5 thick -and are, 'with the rings D, E, etc., arranged with a Working fit in the space between the and the face-plate -B on the other.

bull-ring C and the piston Apri the one side, They are carefully machined, and a small portion suf- Siv ficient to render them easily manageable is then'cut out of them. By adjusting with the hammer, as alreadyv pointed out, they may be given precisely the amount of expansion desired to keep the packing-rings always lmielyy against the sides oi the cylinder. A

lsmallclearance space c* is left in the rear of each of these rings; the expansion of the rings F Fx is' relied upon to keep the packing rings u ,.ito their work when the engine is idle. ese rings making a working fit, as already pointed out, with the other parts 'of the pislton, will withthe lubrication ordinarily em'- ployed altogether prevent too rapid changes in the pressure of steam in the spaces in the rear of the rings F F1. A

.The piston is more conveniently assemble'dthan any with which I am acquainted;

itjis best to roceed as follows; First, the

'rings D are p aired in position after the piston is inserted in the cylinder, the lone' sido of the ring Dl being placed against the piston;

then the sections of the rings El are placed iiipositions whicli`will break joints with the sections of the ring D1. The ring F1 is then sprung into place, this being easily effected by compressing it. The bull-ring (l is then paced in osition, and the operation proceeds by p acing first the sections of the ring E in place and then the sections of the ring D, breaking joints with those of the ring E,

after which ring F is s iriing into place and the face-plate B is applied, the bolts (i being screwed down so as to engage the lace-philo.

`iirmlv with the bull-ring and hohl the latter in osition.

n practice I have found the Yabove detional packing-rings breaking joints andy making a working fit in a circumferential groove in thc piston, of a cast-iron expanding ring also makiiigva working fit in such groove and 4interposed between the piston and the packing-rings.

2. in a packing, the combination, with sectional packing-rings breaking joints and means for preserving their relative circumferential position, of a cast-iron expanding ring of substantial thickness pressing the packing-rings against the surface with which they have relative motion.

3. In a packing, the (,ioinbinationl of a sectional packing-ring of gnomon cross-section, a second packing ring of cross-section completing the )arallclogram and breaking joints with the irst ring, a long side of the gnoinon being turned towards the pressure, and an expanding ring ofsubstantial thickness made of cast-iron, pressing Vthe rings against the surface to be packed; onc of lthe rings beingr prevented From circumferential movement relative to the other by an abutment of cross-section like thatof the ring and completing its circumference, the abutment being attached to the other ring.

4. ln a packing, the combina-tion, with a bull-ring of L cross-section, of sectional ico packing-rings upon each side thercoj, breaking joints with one another; one of @he rings of each set being substantiallv oi" gnomon cross-section, and the other of a section to complete the parallelogram. j

5. lIn a piston-packing, the combination, 4with a piston having a circumferential shoulder, of a bull-ring resting upon the shoulder,

packing-rings upon each side of the bull-ring,

and a face-plate.

6. ln a piston-,wicking the combination, with a piston. of a bull-ring engaging therewith by less than the width of its inner periphery, packing-rin fs on each side of the )ull-ring, and a face-p ate.

7. ln a piston-packing, the combination, with the piston, of a bull-ring of L crosssection, engaging by its inner periphery with the piston along a shoulder of less than tho w'iill.li`ol"sii .h ieriphci'y; wicking-ringsupon cach sido ol t ic bull-ring, and a hice-plato.

H. ln o piston-miching, the conibiniition, with thc piston, ol'r an L shaped bull-ring, packing-rings upon ciich side tlicreol, one

ring of cach set being of gnoiiion cross-sect ion Y @mozo and the :other of sectionA collpoting the ln Witness Whereofhave hereunoset A parallelogiam, the rings boing dlvided into name in the pesence of two Witnesses.

sections breaking joints; a. casbron expand- JGHN P. RANDERSON;

ing ring under each set of packing-rings, and

a face-plate all of the rings making a Work- Witnesses:

ing t in a ciroumferen'blal groove in the `WILLIAM EASTON, piston, as set forth. BORDEN .H. MxLLs.

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