US1531721A - Piston - Google Patents

Description

March 31. 1925. 1,531,721

J. WIYLLIAMS ET AL PISTON Filed Dec. 11, 1924 Patented Man 31, 1925.

JOHN WILLIAMS AND JUDSON WILLIAMS, 0]? PHILADELPHIA, PENNSYLVANIA.

rrs'ron.

Application filed December 11, 1924. Serial No. 755,247.

To all whom it may concern:

Be it known that we, J OHN WILLIAMS and J UnsoN WILLIAMS, citizens of the Umted States, residing at Philadelphia, in the county of Philadelphia and State of Pennsylvania, have. invented certain new and useful Improvements in Pistons, of which the following is a specification.

This invention relates to an improved engine piston and seeks, among other objects,

, to provide a piston wherein, in use, looseness of the piston will, to all intents and purposes, be permanently overcome. The invention seeks, as'a further ob ect,

to provide a iston wherein so-called piston slap will be ellminated and the usual troubles resulting therefrom thus overcome.

. And the invention seeks, as a still further object, tov provide an over-size self-conforming piston which will take up wear as wear occurs While undue friction will be avoided.

Other and incidental objects will appear hereinafter.

In the accompanying drawings:

Figure 1 is a vertical sectional view on the line 1--1 of-Figure 2, looking in the direction indicated by the arrows, a cylinder being shown in dotted lines.

Figure 2 is a vertical sectional view on the line 22 of Figure 1, looking in the direction indicated by the arrows, this view illustrating the iston in position within a conventional cy inder,

Fi re 3 is a horizontal sectional view on the hue 33 of Figure 2, looking in the direction indicated b the arrows.

In accordance with the present invention,

'. the improved piston is formed with a head 10 which is provided internally with reinforcing ribs 11 and externally with an approved number of ring ooves 12 to receive expansible rings 13 1n the usual manner. The rin are conventionally shown. Depending from the head is a cyllndrical skirt 14 integral with the head and formed in the skirt at the base of. the head are oppositely disposed segmental slots 15 defining intervening webs 16 therebetween. At said webs, the skirt is formed with arallel side plates 17 which extend in chordhl relation to the circumference of the skirt, being free at their lower edges, and formed on said plates are 1 oppositely disposed wrist pin bearings 18 and opens at its lower end through the lower edge of the skirt while -at its upper end, the slot opens into one of the grooves 15. The skirt is thus severed throughout its length and it is now to be observed that the metal from which the piston is formed is resilient so that the skirt is thus adapted to flex. In

other words, the skirt may be contracted in circumference and thusv brou ht under tension,'when'the skirt will tend to expand to its normal diameter.- Any approved metal or alloy may be empl yed in forming the piston, provided the necessary resiliency is present. Formed in the skirt 14 near its lower end is I an external annular oil groove 21.

In Figure 1 of the drawings, we have shown a conventional cylinder in dotted lines at 22, and attention is now directed-to the fact that the skirt 14 of the piston is tapered from anexternal over-size diameter at the lower end of the skirt to substantially cylinder size diameter at the upper end of the skirt so that the piston is thus of truncated cone-shape. The point is stressed that the Hare of the skirt is over cylinder size as distinguished from under cylinder size. In practice, the piston is first formed in the rough. when the skirt is turned or ground externally to impart the desired taper thereto. The taper may start at a few thousandths of an inch over cylinder size at the lower end of the skirt and stop at substantially cylinder size at the level of the lower edges of the slots 15, or, as has been found expedient in some cases, the taper may stop at substantially cylinder size at a level close below said slots. In any event, the skirt is externally tapered at its lower end portion and the flare thus imparted to the skirt is over cylinder size. In Figure 1 of the drawings, the flare is exaggerated to more clearly bring out the feature. 'In Figures 2 and 3 of the drawings, we have shown the piston disposed within a conventional cylinder 1 23 and, as will be observed, the lower end portion of the skirt approached, the contraction of the skirt I gradually increases in proportion tothe are of the skirt and accordingly, the pressure of the skirt against the wall of the cylinder gradually increases from' the upper end of the skirt to the lower end thereof. A- tight fit between the piston and cylinder is thus effected and as the wall of the cylinder and the skirt of the piston wear, the skirt will, of course, expand to take up such wear so that the tight fit between thepiston and cylinder will be maintained. In this connection, it is to be noted that a piston having a straight split skirt over cylinder size would not accomplish the objects of the invention for the reason that such a skirt, when contracted to cylinder size at its upper end, by the insertion of the piston in a cylinder, would be flexed to under cylinder size at its lower end. This is due to the fact that the skirt is necessarily rein forced and braced at its upper end by the piston head while the lower-end of the skirt is free. Accordingly, a pressure at the top of the skirt suflicient to contract a straight skirt to cylinder size, would cause an over flexing of the lower end of the skirt. This result is avoided in the present invention, by tapering the skirt exterio-rly toward its upper end so that the over size lower end portion of the skirt is pressed against the cylinder.

that after the piston is wornin, as it is commonl called, the piston becomes accommodate to the exact shape of the inner surface of the c linder with the result that the piston will t en travel smoothly within the I However, no looseness is de-. veloped and the piston still expands to provide a tight joint with the cylinder wall.

Furthermore, it has been discovered that when the improved piston-is installed in an old cylinder which has become more or less worn, the piston will, after a short period of use conform to the shape of the worn cylinder and form a, tight joint therewith throu bout the inner circumference of the cylin er. We thus provide a iston which will. eliminate the various'trou les now experienced from loose or worn pistons.

Having thus described theinvention, what we claim is: y s

A piston comprising a'head having a resilient skirt provided with wrist pin bosses and being disconnected from the head between said bosses, the skirt beingprovided with a split extending from the lower end of the skirt above the plane of the axes of said bosses and being externally tapered from an over cylinder size diameter at its lower end toward its upper end whereby when the piston is inserted in a cylinder and the skirt is compressed by the cylinder wall the external surface of the skirt will bear against the cylinder wall substantially unifor y.

tures.

In testimony whereof we aflix our signa-

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