US2246942A - Piston - Google Patents

Description

June 24, 1941. W T JANNEY TAL 2,246,942

PIsToN Filed Aug. 13, 1937 l 2 sheets-sheet v1 Patented June 24, 1941 UNHTE geen PISTON Walter T. Janney and Maximillian H. Sorensen, Philadelphia, Pa., assignor to Janney Cylinder Company, Philadelphia, Pa., a corporation of Pennsylvania Application August 13, 1937, Serial No. 158,878

6 Claims.

This invention relates to pistons, and particularly to piston plungers for pumps and the like. Plungers in parts of the oil industry must move in oil at temperatures of from 600 to 800 degrees and be subject to abrasion as well. Customarily such plungers are internally water cooled. In providing a satisfactory plunger it must be appreciated that with the exterior of the plunger at elevated temperatures and the interior Water cooled, it results in strains and distortions incident to such different temperature conditions which have previously militated against use of multiple part plungers.

It is among the objects of the invention; to

provide a plunger with an abrasion resisting sleeve; to provide a plunger with a sleeve mounted on the plunger with a push t and anchored to the plunger from one end only; to provide a compound plunger havinga sleeve and arranged to stretch the plunger with expansion of the sleeve; to provide a sleeve and a piston with a safety device permitting relative expansion of the sleeve and piston to a crushing point without distortion of the sliding surface of the plunger; and many other objects and advantages will become more apparent as the description proceeds.

In the accompanying drawings,

Fig. 1 represents an end elevation of a plunger according to the preferred form thereof,

Fig. 2 represents a fragmentary section of the end of the plunger of Fig. l, showing the anchoring ring disposition,

Fig. 2A represents a diagrammatic side elevation of an illustrative form of plunger,

Fig. 3 represents an end elevation of a modified form of plunger,

Fig. 4 represents a fragmentary section of the end of the modified form of plunger shown in Fig. 3, Y

Fig. 5 represents a fragmentary section through the end of a still further modied form of plunger showing the safety device incorporated in the anchoring end,

Fig. 6 represents a fragmentary section on an enlarged scale of the end of the plunger of Fig. 5, showing the safety grooves,

Fig. 7 represents a fragmentary section through the safety device of Fig. 5 after its subjection to crushing strains in which crushing has occurred y in both of the meeting members, and

Fig. 8 represents a similar fragmentary section through the safety device in which one of the meeting members is appreciably harder than the other to show the direction of metal now or longitudinal strains on the plunger base itunder crushing strains.

The plunger, or plunger base of the composite piston or plunger, in the preferred embodiment, comprises a hollow piston Ill having an internal bore II, terminating in a web I2. Cooling water is preferably circulated in bore II. The plunger piston l0 has a reduced or sleeve portion I3 extending practically the full length of the plunger, and terminates in a shoulder I4.

Upon the sleeve portion I3, is pressed or otherwise closely fitted the wear sleeve I5, with an end I6 abutted against shoulder I4. The free end II of the sleeve terminates preferably some little distance from the free end of the plunger. The sleeve I5 may comprise a single hardened element extending the full length, or a multiple piece sleeve I5 and I8 in abutting relation, and of different degrees of hardness from themain sleeve, as will b e pointed out later herein.

The plunger has a peripheral slot or groove 2B formed in it, with itsk side wall 2l a substantial verticalcontinuation of the end il. The end 23 of the plunger has a chamfered or inwardly tapered surface 24. A ring 25 comprised usually of two halves 26 and 2l, is provided with an'inwardly directed square flange 23, such as to be received in the peripheral recess 20, with the ring end Wall y3l) engaging both the end wall 2| of the groove and the end I'I of the sleeve I5 or I8 in alignment With the groove wall ZI. The exterior surface 3| kof the two part ring isa continuation of the surface of the sleeve I5. The end of the ring 32 merges into a chamfered or tapered wall surface 33 meeting the cooperating chamfered surface 2A of the plunger in an obtuse angle such as to effect a Valley or peripheral shallow pocket 34 to receive the Welding 35. It `will be understood that the two part ring is first clamped about the end of the plunger with the two parts in the groove and with the edges in confronting relation, after which radial lines of welding 35 and 3l, and the peripheral welding 35, are accomplished to rigidly join the two part ring into the single integral entity 25, as well as to anchor the complete ring to the end of the plunger, as will be clear.

In the disclosure of Figs. 1 and 2, the sleeve I5 is shown as engagingbetween the shoulder I4 of the plunger at one end, and the shoulder formed of the ring 25 at the other end of the plunger. It will be clear that if the sleeve is in abutting relation at each end at room temperatures, as it is, substantially, expansion of the sleeve when it contacts the hot oils, relative to the inwardly cooled plunger base, will exert tremendous axial self, which will cause the plunger to stretch between the points or lines of sleeve abutment if made of such metal as conduces toward elongation. Thus the conditions under external heat result in an elongated composite plunger. As the sleeve contracts following removal from the hot oil in the ordinary case, the sleeve and plunger base contract together to maintain the abutting relation of the sleeve and shoulders.

As shown in Figs.. 3 and 4, a modified form of fastening may be resorted to for securing some portions of the benefits derivable from the preferred form, in that the peripheral slot and the two piece ring are obviated, by drilling and tapping the end of the plunger base as at 40, and in screwing into the apertures the bolts 4I having the heads 42 protected against shearing 01T by thellet 39, which overlap the end of the plunger and sleeve to abut against the end I'I of the sleeve I 5. The bolts and bolt heads are then welded in position to prevent retraction, as indicated at 43. This is a simpler form of anchor, but has smaller bearing engagement on the end of the sleeve I5 and will not be proof against extreme differentials in inner and outer temperatures, except in relatively short plungers.

As the length of the plungers in question is sometimes appreciable, it will be clear that the differential expansion of the inner and outer members may sometimes amount to a considerable longitudinal difference, it is preferred that the split and subsequently integral flanged ring be of relatively soft material, so as to have a slight yield relative to the sleeve itself, that in addition to the relatively soft plunger base and soft flange, it is frequently desirable to insert a supplemental relatively soft ring or sleeve I8, in addition or as a part of the sleeve I5, so that the relative adjustment under differential heat conditions will be as a resultant of a slight compression of the soft sleeve I8 as well as a stretch or extension of the plunger base itself. However under certain more or less extreme conditions the foregoing may not be enough to absorb all difference in expansions of the several parts that may occur.

As an additional safety measure the split ring has a plurality of grooves 44 cut peripherally in the side wall in concentric relation so as to form a plurality of annular threads 45 in the face of the ring in axial alignment with the end of the sleeve I5 or I 8. If desired this may be the only element .so threaded or cut away, but preferably similar threads 46 are formed in the end of the sleeve I5 or I8, with the peaks of the threads 46, separated by grooves 41, in contacting alignment and registration with the threads ofthe locking ring 25. It will be obvious that if desired the locking ring 25 may be of hardened material relative to the softness of the ring or sleeve I8 an extension of sleeve I5.

As a result of undue or abnormal or excessive differential expansion, the threads disclosed as safety devices permitting the metal of the threads to iiow laterally into the adjacent grooves as they are crushed by the excess pressure. The disclosure of Fig. 7 is that of the preferred embodiment, in which the initially aligned threads 45 and 46 on the relatively soft elements, locking ring 25 and sleeve I 8 each are crushed to iiow laterally into the adjacent grooves, as at 5G. In Fig. 8 the disclosure is of one element which is hard, whether the ring 25 or sleeve I5, may make no difference but illustrated as the ring 25, abutting the threads 46 of the relatively short sleeve I8, resulting in crushing only of the soft threads 46, and their flow into the grooves 41 as at 5I.

While it will be obvious that many different materials may be used with good effect for the composite plungers of this invention, the desired characteristics are that the sleeve I5 be of hardened abrasion resisting nature so as to resist abrasion due to the high pressures of the plunger working in the packing. Preferably the expansion ratio of the plunger or piston and the sleeve should be substantially similar. The sleeve I8 may be ofthe same material as sleeve I5, but unhardened or annealed. The plunger I0 may also be annealed.

Illustratively the plunger may be comprised of forging steel, of about .20 to .30 carbon. Upon this is shrunk or hydraulically pressed a sleeve of say 14% chromium steel hardened to about 500 Brinell. 'I'he sleeve I8, which does not pass through the packing of the cylinder may be of substantially 14% chromium steel, but unhardened, as it has only to resist the corrosive action of the hot oil. If the oil be-ing pumped is not corrosive, but is only of high temperature, then the sleeve I8 may be ordinary unhardened or annealed steel.

The plungers are customarily worked until worn out, so that the initial crushing incident to expansion would be a set that would be maintained as long as the differential temperatures maintain. Obviously if the temperatures are reduced to atmospheric, a gap between an l end of the sleeve and a shoulder of the plunger might maintain, but this would promptly be closed again as soon as the plunger was again differentially heated.

We claim as our invention:

l. A composite plunger comprising a plunger body having a peripheral groove substantially close to one end, a sleeve mounted axially on the body with an end aligned with the wall of said groove, a fianged ring mounted on the body with its flange in said groove in abutting engagement with said end of said sleeve, said ring having a sleeve-engaged face having crushable face components to permit sleeve expansion.

2. A composite plunger comprising a plunger body, spaced stop means on the body, an elongated hardened sleeve on the body engaging one stop, and a supplemental short relatively softer sleeve engaging the first mentioned sleeve and the said other stop as a uniformly contoured crushable extension of the first sleeve responding to excessive temperature differentials.

3. A composite plunger comprising a plunger body having a peripheral groove at one end, a sleeve mounted on the body and having a peripheral concentric thread formed on the end of the sleeve, a ring mounted on the body and having a portion anchored in the groove in substantial abutment with the end of the sleeve, a peripheral concentric thread formed on the ring in registration with the thread on the sleeve, said registration `being such that axial pressure from the sleeve against the ring may cause collapse of the thread of the ring to absorb excess pressure safely.

4. A composite plunger comprising a plunger body having a peripheral stop at one end, a sleeve of hardened metal mounted on the body in engagement with the stop, a sleeve of unhardened metal on the body in engagement with the rst mentioned sleeve, a groove formed in the body in substantial alignment with the end of the second mentioned sleeve, a ring having a flange disposed in the groove and abutting said second mentioned sleeve.

5. A composite plunger comprising a plunger body, a sleeve on the lbody, a ring on the body engaging the end of the sleeve, threads formed on the abutting portions of the sleeve and ring to form a collapsible safety device to permit excessive expansion of the sleeve.

6. A composite plunger comprising a plunger body, a sleeve on the body having an end face,

WALTER T. JANNEY. MAXIMILLIAN I-I. SORENSEN.

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