US2164849A - Piston ring and expander - Google Patents

Description

July 4, 1939. w 2,164,849

PISTON RING AND EXPANDER Filed May 17, 1937 2 Sheets-Sheet 1 J y 4, 1939- J. WILLIAMS 2,164,849

PISTON RING AND EXPANDER Filed May 1'7, 1937 2 Sheets-Sheet 2 Patented July 4, 1939 UNITED STATES PATENT OFFICE 4 Claims.

This invention relates to an improved piston ring and expander for internal combustion engines.

In a broad sense, anobject of the invention is to provide a structure wherein the expander will effectually coact with the ring to strongly augment the expansive action thereof so that the ring will, in turn, be caused to more uniformly fit a cylinder wall and thereby provide a more perfect seal between the ring and the cylinder.

Another object of the invention is to provide a structure wherein the expander will respond to the more or less minute radial variations in the ring, as'the piston reciprocates, while at the same time maintaining outward radial pressure on the ring. Due towear, a cylinder is more often than not, out-of-round, thereby forcing a ring to constantly change in circular contour as the piston reciprocates, and as an-engine piston reciprocates with such great rapidity, an expander, to effectually serve its function of constantly pressing outwardly on the ring with uniform force, must "be capable of extremely rapid flexing movement constant and while embodying tangentially disposed springs to act on the ring will, nevertheless, be of undim-inished width and consequent durability throughout its length, free of any reduced areas, necks or slim connecting portions subject to premature failure.

'Still another object of the invention is to providean expander which may be readily fashioned from a metal strip of uniform width throughout its length and which may thus be more economically produced than heretofore.

And a further object of the invention is to provide :an expander embodying double leaf springs, the leaves of which 'are integrally connected at their outer ends, and wherein the expander may be employed in conjunction with slotted rings and so disposed that the free end portions of the springs will engage the. ring at its slotted portions without likelihood of the leaves being severed free of each other by wear.

Other and incidental objects of the invention will appear during the course of the following description and in the drawings,

Figure .1 is a horizontal sectional view through an engine :piston showing the ring and expander thereon.

Figure 2 is a .perspective view of the expander.

Figure 3 is a fragmentary vertical sectional View on the line 3-3 of Figure 1.

Figure 4 is a view similar to Figure 1, showing a modification of the invention.

Figure 5 is a perspective View of the modified expander.

Figure 6 is a fragmentary sectional view on the. 5 line 6-6 of Figure 4.

Referring now more particularly to Figures 1 to 3 of the drawings, I have shown a conventional en ine piston at It and one of the ring grooves thereof at M. More or less freely disposed in the 10 groove is a resilient piston ring l2 provided with spaced radial slots 13 disposed medially of the ring and separated by bridge members I 4 integral with the reduced fillets l5 of the ring while at the ends of the ring are similar bridge members I 6.

Fitting within the groove i I behind the ring I2 is an expander including a split circular supporting band I l about which are uniformly spaced a plurality of substantially semi-elliptic tangential springs l8, one for each of the slots 13 of the ring. The expander is formed from a single length-of suitable metal initially capable of being bent to the desired shape after which the expander is appropriately treated to impart the desired hardness and resiliency thereto.

As will be observed, the expander is fashioned from a metal strip of uniform width throughout its length and the strip is looped upon itself in the direction of its length first in one direction to provide :one end portion of each spring and then in an opposite direction to provide the other end portion of each spring. The springs may thus wellv be described as double-ended and each end portion of each spring is composed of inner and outer leaves i9 and 20 integrally connected at their outer ends. Gaps 2! are thus produced in the supporting band I! but these gaps are relatively narrow and the integral continuous outer leaves 29 of the springs extend across said gaps to impart added resiliency to said band.

The end portions of the springs l8 are curved in a direction with the supporting band l1 so that the pressure of the springs against the ring Will not be localized at the tips of the springs and preferably a pair of the springs is disposed adjacent the ends of the band. At this point, it may be emphasized that the springs are formed, as previously noted, simply by looping the initial metal strip in the direction of its length. The springs are thus initially produced in their entirety in the plane of the supporting band ll and are connected with the band by portions of the same width, character and strength as the supporting band itself. In other Words, the original blank is of uniform width from end to end and the springs are not formed from tabs at the side edges of the strip, which tabs must be subsequently bent over to provide the springs. Such a construction produces reduced areas, necks or slim connecting portions between the springs and the supporting band which necks or connecting portions are relatively fragile and delicate and are subject to premature failure. In contrast, the springs l8 are connected with the band I! by portions of undirninished width so that the entire expander is uniformly rugged throughout. Furthermore, as the original metal strip is of uniform width, a great saving of material, as contrasted with a blank with lateral tabs, is effected. Struck from the confronting ends of the pair of springs opposite the ends of the band ll are medially disposed out-turned stop lugs 22.

As brought out in Figure l, the supporting band I! is of a diameter to grip the bottom wall of the ring groove II and the expander is so arranged that the stop lugs 22 are disposed at opposite sides of the bridge members It within the adjacent ring slots [3. The lugs are thus positioned to coact with said bridge members for limiting relative rotation of the expander and ring. Thus, the springs l8 will be supported to engage the ring at the slots 13 for pressing the ring outwardly to more perfectly conform to the contour of the cylinder wall.

The inner leaves I9 of the springs it will, of course, augment the spring action of the outer leaves 20 of said springs but it has been discovered that by connecting the leaves at their outer ends, the stiffening of the springs is greatly pro-- nounced so that said springs will thus exert a correspondingly increased outward pressure on the ring. At the same time, however, the springs will sensitively respond to sinuous displacement of the ring so that the ring will be strongly urged to follow a cylinder wall as the piston reciprocates.

In connection with the foregoing, it is to be noted that, as shown in Figure 3, the springs it are preferably of a width to have a wide bearing on the inner edges of the fillets H") of the ring. Furthermore, as will be noted, the stop lugs 22 are considerably less in width than the width of the slots l3. Consequently, even should the fillets wear through the outer leaves 26 of the springs, such Wear cannot serve to sever the leaves of the springs entirely free from each other and break the integral continuity of the ex pander. For such reason, it is possible to dispose the springs at the ring slots it where the springs will have the greatest bulging effect on the ring.

In Figures 4, 5 and 6 of the drawings, I have shown a modification of the invention. A piston is indicated at 23 and one of the ring grooves thereof at 26. More or less freely disposed in said groove is a split resilient ring 25 provided at its inner face with a medially disposed annular slot 26 while at the ends of the ring are bridge members 21 adjacent which are radial openings 28 through the ring at the ends of said slot.

Fitting within the ring groove 24 of the piston behind the ring 25 is an expander indicated as a whole at 29. This expander in all respects is identical with the expander of the preferred embodiment of the invention except that in lieu of the double springs IS, the metal strip from which the expander 29 is formed is looped upon itself in the direction of its length to provide uniformly spaced single tangential springs 30 composed of inner and outer springs 3| and 32. It is to be noted, however, that the springs at one side of the expander project in a direction opposite to the springs at the other side of the expander and struck from the confronting ends of the springs opposite the ends of the expander are medially disposed out-turned stop lugs 33. As shown in Figures 4 and 6, these lugs are of less width than the width of the slot 26 of the ring 25 and are disposed in said slot at opposite sides of the bridge members 27. The lugs are therefore arranged for engagement in the openings 28 of the ring for limiting the ring and expander against relative rotation. The expander 29 will thus be supported to function in a manner identical with the expander of the preferred construction and further description in this respect would accordingly appear unnecessary.

Having thus described my invention, I claim:

1. In a structure of the class described, the combination of a split annular supporting band looped upon itself in the direction of its length to provide spaced tangential springs each having overlapping portions connected by a bight at the free ends of the springs respectively and adapted to be seated in a piston ring groove, a piston ring adapted to fit in said groove surrounding said springs to be expanded thereby and provided with prominent inner circumferential faces spaced to contact and wear against the edge margins of said springs near the bight portions thereof while the middle portions of the free ends of said springs remain out of contact with the ring to preserve the unbroken continuity of the band when the portions of the springs in contact with said faces of the ring wear through and become servered at the free ends of the springs, and stop lugs struck from the bight portions of springs opposite the ends of the band and disposed to engage the ring in the space between the prominent faces thereof for limiting the band against rotation relative to the ring.

2. In a structure of the class described, the combination of a split annular supporting band looped upon itself in the direction of its length to provide pairs of confronting spaced tangential springs each having overlapping portions connected by a bight at the free ends of the springs respectively and adapted to be seated in a piston ring groove, a piston ring adapted to fit in said groove surrounding said springs to be expanded thereby and provided at spaced points with radial slots therethrough at pairs of said springs, said slots defining prominent inner circumferential faces spaced to contact and wear against the edge margins of said springs near the bight portions thereof while the middle portions of the free ends of said springs remain out of contact with the ring to preserve the unbroken continuity of the band when the portions of the springs in contact with said faces of the ring wear through and become severed, and stop lugs struck from the bight portions of springs opposite the ends of the band and disposed to engage in certain of said slots for limiting the band against rotation relative to the ring.

3. A piston ring expander formed from a metal strip bent to provide a split annular supporting band looped upon itself away from the split in the direction of its length to provide at one circumferential half of the band a number of spaced tangential springs extending clockwise away from the split and at the other circumferential half of the band a number of spaced tangential springs extending counter-clockwise away from the split,

4. A piston ring expanded formed from a metal strip bent to provide a split annular supporting band looped upon itself away from the split in the direction of its length to provide at each circumferential half of the band a number of spaced tangential springs the overlapping portions of

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