US2694608A - Piston ring expander and rail interlock - Google Patents

Description

NOV. 16, 1954 D w HAMM PISTON RING EXPANDER AND RAIL INTERLOCK Filed Feb. 3, 1953 HUI! FIG3

' III INVENTOR. DOUGLAS w. HAMM PISTON RING EXPANDER AND RAIL INTERLOCK Douglas W. Hamm, Muskegon, Mich'., assignor to Muskegon Piston Ring Company, Muskegon, Mich., a corporation of Michigan Application February 3, 1953, Serial No. 334,909

2 Claims. (Cl. 309-43) a greater unit pressure of the outer curved bearing surfaces of piston rings or ring elements against internal combustion engine cylinder walls. One place where it has wide use is in conjunction with the steel rail piston ring combination in which, in general, two spaced thin parted steel rails are separated by a spacer and the expander engages against the inner edges of the steel rails to press them outwardly and supplies, in the main, the major portion of the pressure with which the outer edges of the thin steel rails engage the cylinder walls.

Such expander has alternate inwardly extending bowed or curved portions and outwardly extending humps also curved, the humps bearing against the inner edges of the steel rails and the bowed portions in general being pressed against the bottom of the piston ring grooves in which located. The outward force acting upon the rails is at spaced apart points in an outward radial direction.

Such humps of the present expander have merely a pressure contact therewith. With my invention, an expander of a novel form is provided which not only exerts outward pressure on such steel rails but, in a measure, is interlocked therewith so that relative up and down movement of the rails with reference to the expander is forbidden and, in some forms of pistons, where a piston ring groove may have a rather wide slotted connection with the interior of the piston, the danger of a rail changing position and escaping from the expander is eliminated. Further, with my invention, the number of spaced points at which the expander engages with and against the steel rails is increased and the distance between such points diminished getting a better and more uniform pressure effect.

An understanding of the invention may be had from the following description taken in connection with the accompanying drawing, in which,

Fig. 1 1s a fragmentary perspective view, somewhat enlarged, of a portion of an expander made in accordance with my invention, bearing against and interlocked with spaced steel rails.

Fig. 2 is a fragmentary elevation and plan view of one of the outwardly extending humps of an expander made in accordance with my invention in a different form than that shown in Fig. 1, and

Figs. 3 and 4, similarly, are fragmentary elevations and plan views thereof of two additional specifically different but equivalent forms of the expander at such humps, for attaining the same results.

Like references characters refer to like parts in the different figures of the drawing.

As is well known in the piston ring art, thin steel rails approximating .020 to .025" in thickness, substantially flat and parted at one side, are used in piston rings spaced from each other as in Fig. l with generally a spacer between the rails. With my invention the expander, which is made from thin steel ribbon stock of a width substantially equal but slightly less than the axial dimension of a piston ring groove in which installed, has alternate inwardly bowed sections 2 integrally connected by outwardly extending curved or bowed humps 3, the expander having oil passing openings in many different forms therethrough for venting one of which forms is shown in Fig. 1.

nited States Patent With my invention, instead of the hump portions 3 being of the same width as the remainder of the expander, they are reduced in width preferably by equal amounts at both upper and lower sides a distance approxi mately equal to the thickness of the steel rails 1. The inner edge portions of the steel rails thereupon extend inwardly partly over the humps, bearing against the upper and lower surfaces 4 at their inner sides, the inner edges coming against shoulders 5 which are at the ends of the narrowed hump portions 3. The expander under stress and deformation when installed in a piston ring groove will exert an outward pressure transmitted at the shoulders 5 at two spaced apart points at each of the humps 3 against the rails 1.

The invention which I have made may be embodied in other forms serving the same purpose and getting the same result, substantially equivalent to that first described and which is shown in Fig. 1. In Fig. 2, at the humps 3, the metal may be swaged and upset so that the middle portion of each hump is reduced in width, as shown at 6, providing upper and lower flat horizontal surfaces 7. The inner edge portions of the rails I extend one above the upper surface 7 and the other underneath the lower surface thereof and, at their inner edges, bear against the shoulders of the expander humps back of such surfaces 7 getting substantially the same action and result as in Fig. 1.

In Fig. 3, a part of the width of the expander at each side and at each hump 3 is cut away and, also, the metal is split from each end of the cut a short distance making tongues 8 which are bent and curved inwardly. The intermediate narrowed portion 9 at each hump 3 has upper and lower edge surfaces, similar to that at 4 in Fig. 1, bearing against the inner sides of the steel rails one over and the other below such intermediate portion 9. The inner edges of the rails 1 come against the outer rounded sides of the tongues 8.

In Fig. 4, which shows a still difierent form and one which for practical manufacturing purposes may be preferred, the ribbon stock from which the expander is made is not of uniform rectangular cross section but has a thickened intermediate portion between its opposite upper and lower edges, with narrowed portions extending above and below such thickened portion. Such ribbon stock may be formed into the expander shape identically as the present expanders are now made, so that at the humps 3 the intermediate portions 10 will project outwardly between the upper and lower rails 1, the projecting narrowed portions 11 will extend one upwardly back of the upper rail and the other downwardly back of the lower rail, and serve as stops therefor, similar to the shoulders 5 or the tongues 8 and identically with the widened portions in Fig. 2 so that the rails are held securely against any up or down movement with respect to the expander, engaging against the upper and lower flat surfaces 12 at the upper and lower edges of the thickened portion of the expander stock.

The invention has proved very useful and practical in connection with its use with the steel rail expander assembly of piston rings, maintaining the rails in proper position to the expander without undesired change of position of one to the other and with a broader base of bearing of the hump portions of the expander against the inner edges of the rails.

The invention is defined in the appended claims and is to be considered comprehensive of all forms of structure coming within their scope.

I claim:

1. In a generally circular, thin metallic ribbon piston ring expander, having alternate inwardly extending bowed sections and integral outwardly extending curved humps, the improvement comprising, an integral outwardly extending band around the outer portions of the expander of greater thickness than the parts of the expander inwardly of said band, said band at its opposite edges having surfaces in parallel planes generally perpendicular to the axis of the expander and located inwardly from the adjacent edges of the thicker portions of the expander, substantially equal distances.

2. In a generally circular, thin metallic ribbon piston ring expander, having alternate inwardly extending v 4 btowed sections and integral outwardblextending humps, References Cited in the file of this patent t eimprovement comprising; outwa-r y projecting portions on each hump having an axial dimension less than UNITED STA-TBS PATENTS the width of the remaining portions of the expander, each Number Name Date hump having opposite, generally parallel surfaces inset 5 2,236,721 Teetor Apr. 1, 1941 from the edges ofsaid expander, the thickness at the-pro- 2,436,896 Mummert Mar. 2, 1948 jectionsrbei'ng gneater'than the thickness: of the expander FOREIGN PATENTS portions above'and below: said projections.

Number Country Date 10 538,685 Great Britain Aug. 13, 1941

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