US101792A - Improvement in piston-packing - Google Patents

Description

,itu-ital time `gallant (titille.

Leners Patat No. 101,792, dma Apt/zz 12, 1870.

IMPROVEMENT IN PISTON-PACI-KING.

The Schedule referred to in these Letters Patent and making part of the same.

To all to whom these presents shall come:

Beit known that I, ELLERY A. WALKER, of Hyannis, in the county of Barnstable and State of Massachusetts, have made an invention of a new and useful Manufacture of Pistons for Steam-Enginery; and do hereby declare the following to be a full, clear, and exact description thereof, due reference being had to the accompanying drawings making part of this specification, and in which- Figure 1 is an elevation;

Figure 2, a vertical section; and

lFigure 3, an end view, with the outer cap rennived, of a piston embodying my improvements.

The class of pistons upon which this invention is founded is that known as sectional ring-packing pistons, or those in which a series of metallic rings or sections of rings are employed, and which, by their pressure against the interior of the cylinder of the engine, serves to prevent clandestine passage of steam between the two.

Previous to the origin of the improvements herein to be described, these sectional rings have been ex-` panded in two ways: one by the direct pressure of the steam, admitted behind them in small quantities from the cylinder, and the other by the pressure of springs behind them.

The force of the steam has been found to exert too sudden and injurious' action upon the cylinder, and

' this mode of expanding the sectional rings has been generally abandoned.

The action of the springs is subject to changes in power, owing to the reduction of the periphery of the` packing-rings under wear, and, as pistons have heretofore been produced, must be frequently set out by means ofV set-screws applied to them for the purpose, this act necessitating frequent removal and dismemberment of the piston. It is well known to persons accustomed to the action of steam-engines, that the tendency ofthe piston to tilt inthe cylinder at one extreme of its traverse, and, to some extent, both, wears such cylinder at one point in its circumference, often requiring renewed boring out, or permitting escape of steam past the"A piston, owing to the fact that the rings, which perform the oiice of packing the piston, also form its entire bearing-surface. A

Attempts have been made to remedy this by the employment of a central ring of soft metal, located midway between the ends of the piston, for the purpose of centering the piston. But when the latter tilts, as above specified, it is the ends o f the piston which are liable to wear the cylinder, and therefore a inating this invention, which comprises the subject matter of these Letters Patent, has been to create upon the periphery of the piston, at or near each end, a bearing or supporting-surface or surfaces, wh-ich shall receive the general wear'upon such piston, by this means relieving the packing-rings of this duty, which has heretofore devolved upon them, and requiring them only to preserve a tight joint between the piston and cylinder.

By effecting this result I economize, to a great and valuable extent, the unequal wear of the piston upon l the component parts of which are shown in the head or block at l), the outer plates or caps at c c, and the sectional orsplit packing-rings at d d, such parts be ing produced and combined in manner substantially similar to others in use, with exceptions hereinafter stated. e

v In carrying out .my invention, I form each of the y two end caps or. plates c c,whicl1 confine the packing.-

rings in place, with a circnmscribing peripheral channel'or groove, e, and I ll this channel with Babbitt or; other soft metal, f, permitting of an excess of the same beyond the periphery of the cap, in order that it (the soft metal) alone shall come in contact with theV bore of thecylinder, with the exception of the packing-rings d (l.

These packing-rings encircle, or nearly so, the periphery of the piston-block, a shallow intervening an-v nular chamber, g, being left between Vthe twosto-receive a plurality of curved plate-springs, Vh lt, &`c.'," formed and disposed as shownin iig.3 of the drawings; that is, asexerting a pressure between-the piston-head b andthe packing-rings Y'al-1d, andforcing the latter into contact with the bore of the cylinder.

- Owing to the fact that'the cap-'platesn 'c c'of'the piston, o r their soft metal-ringsoribsservetoisustain the `thrusts^upo`nsuch piston', 'and maintaitprper position within the cylinder, the wear exerted upon the packing-rings is, comparatively, very slight, and no set-screws are needed to compensate for the increase in area of the annular i'nclosure g which now ensues, owing to the rapid wear upon the rings and' the bore of the cylinder, and thus I avoid the present unavoidable stoppage of the engine, the loss-of time, and the annoyance of removing and dismernbering the4 piston.

As the packing-rings, combined with the pistouhead in the present instance, are of one piece of metal with the abutting ends, some means becomes necessary for preventing turning of the same about the piston-head, in order to avoid coincidence of the openings of the two.

In the drawings hereto annexed I exhibit a means of eiectin g this purpose, which consists in fixing upon the inner face of each ring two projections or pins, 'i o, such pins straddling a .fin or rib, j, extending outward from the piston-head.

Although I have, in the. accompanying drawings, exhibited the-soft metal as a continuous ring, encircling each end plate of the piston, it may be. disposed in sections, as practice has ldemonstrated that a bearing-sulface for eachv end of the piston, at the top and bottom, will be suiicient.

Having described my invention, I would state that ing, and the whole operating as hereinbefore set forth' l ELLERY A. WALKER.

Witnesses FRED. CBUTIs, E. GRIFFITH.

I do not claim, broadly, the formation upon the pisc c, the latter being provided with a soft-metal bear-

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