US2110346A - Piston - Google Patents

Description

March 8, 1938.

R2" TEETOR PISTON Filed July 31, 1934 Patented s, 1938" UNITED; STA ES:

.PAIIENT oar-ICE The Perfect Circle Company,

Ind.,' a corporation of Indiana Application july 31, 1934, W No. Tamar a Glahns. (ct sea-1s) This invention relates to pistons for internal combustion engines and the like.

The principal object of my invention is to pro vide a. piston so constructed-that the desired clearances between the bearing faces of the skirt and the cylinder wall may be maintained throughout the operating range of the engine. More particularly I provide a piston of aluminum alloy or the like which has the skirt connected to the head by flexible struts and which is providedwith simple and cheap means which causes 7 .the above mentioned desired clearances to be maintained and also overcomes other objection-V able defects present in aluminumpistons of the slotted skirt type now on the market. Y The above and further objects of my'invention will appear more fully from the following description, reference being had to the accompanying drawing in which: Fig} 1 is a vertical sectional view throul the piston embodying the preferred form of my invention; .j

Fig. 2 is a ve'rticalsectional view through-the piston. Fix.

Fig. 3 is 'piston' taken on the lined-I of Fig.1; V g Figs. and 5 are top plan and side elevational views respectively, of the upper cross strut of the sumand,

Fig. 6 is aside elevational view of one of the lower cross struts of the v a The'head 8 of the piston" is connected ,to'the r inner ends of the piston pin bosses I by parallel flexible-webs or hangers I Ii. The skirt I is separated from the head by the'continuous slbt ll and the bosses 9 project inwardly from the skirt and are further connected to the skirt by the integral strengthening webs t. Theopposite sides of the upper portion'of the skirt are connected together by a cross strut I! which extends at right angles to the axis of the bosses! and between the hangers II. This strut hig a lesser coeiiicient of expansion than the the strut I2 is channel-shaped-in cross section and has elongated slots 20 in its upper face and at its ends it has foldediportions ll' and--in portionsJi. -As shown'in Fig. 2pthe folded portions it are embedded in .thickened portionsli of the skirt as are the ends of the sides-of the 1 channel, and the pressedin portions ll rest Hainst" fe' inner sides of theenlarged portion sll. M

the section taken at 90 to that of 4 r f finished, as by form turningorgrinding, the el- 25 a cross sectional view through the l2 isformed of metal such as Invar or steel, hav- The opposite sides of the lower portion of the skirt are connected together by two parallel struts II which are similar in structure to the strut l2. The struts "have their'ends embedded in thick- 0 .Qned portions it of the skirtin substantially the 5 samewayasthe endportionsofthestrut flare} embeddedin the portions it of the skirt. In the piston, the inflexible struts l2 and i'lare placed in position in the 'mold and -.then the aluminum alloy is poured into the mold. 1 As. the alloy cools, it shrinks or contractsl The head shrinks more or less uniformly so that it retainsits round or cylindricalform though. its 4 diameter is reduced. The struts l2 and I1, however. prevent substantial reduction of the 15 diameter of the skirt at-right angles to the-pin so that as the skirt cools the portions of theskirtinlinewiththearedrawnin' and the skirt becomes elliptical with the bearing faces, mid

the aluminum alloy pl the struts i2 and II, which are inflexible, under constant compression. Whenthepistoniscold. theskirtissizedor bearing faces of the skirt and the cylinder wall throughout the length of the skirt. As the engine becomes heated in operation, the head expands twice as much as the skirtor thereabouts, as the head becomes much hotter than the skirt. As the head expands the distance between thehang'ers Il tends to increase but this actiondoes not mate rially aflec't'the shape of the skirt-as the arerquite thin and they flexto accommodate for the most part the difference between the expansion of the head and skirt due to the diflerence m 40 temperatures. The skirt, however, tends to expond circumferentially due to the increase in its temperature. The struts lland ll being-under constant compression (with-the bearing faces-or 7 portions of theukirt and tending to move toward each other) the;ex-. pansion of the aluminumalloy-causes thediamere:- o: the skirt at right angles to the bearing f faces to increase. That is to say, the expansion forthe takes place on the minor of the skirt. Or, instill other; words, the expansion of the aluminum of the tends-to change the skirt from its elliptical'form t nev approaching around iormby increasingthe'.v lengthoftheminorasissothatitapproachesjthelfiii between'the lying on the 2.0 "major axis. It is obvious that the shrinks 0f bearing against their ends 5 v length oi the major axis. The

latter "axis may also slightly increase." duato the slight linear expansion of the struts and the slight increase in' thickness in the aluminum of the at the end of the struts.

It will thus be seen that the diameter of .the piston skirt fromtop to bottom is properly controlled during the operating range 01' the engine so that the desired clearance between the bearing faces. and cylinder wall is maintained throughout their length, the diameter of the skirt in line with the pin homes being permitted to change without impairing the eiliciency of the engine and withoutdanger of scoring and the like.

It is understood that my invention is not limited to the details of construction shown and that other forms may be used without departing from the scope o! my invention.

U 'by' a circumterentially extending air-gap and I claim: 1. A piston comprising a head, flexible hangers depending from said head and carrying Din bosses apertured to receive a piston pin', and a skirt integrally connected to said pin bosses, all formed I 'of a metal having-a high coeflicient of expansion;

said head and skirt being axially spaced from each other throughout their entire circumierence being maintained in such relation by said flexible hangers, said hangers being spaced inwardly from v said skirt, the entire exterior surface of said skirt being generally elliptical in contour with the minor axis thereof substantially parallel to the axis of said pin bosses and the continuity of means having a'lower coem'cient o! .me'tal'oisaidskirt M It! piston pin bosses, the ends oi! saidskirtbeinginterniptedonlyby'thepin p rmr aandapairoirigid tshaving metal of said skirtdispoaed below and from said pin boaaes, the ends oi said struts embedded in the metal of said skirt.

2. A piston comprising a head,-1iexibie depending from said head and carrying pin apertured to receive a piston pin, anda shirt integrally connected to said pin bosses..all formed of ametal having a high coemcient of expansion; said:head and skirt being axially spaced spaced inwardly from said skirt, the entire exte rior surfaces of said skirt being generaily eliiptical in contour with the minor axis thereoi substantially parallel to the axis of said and the skirt having circumferential save for the piston pin apertures;

than that oi the metaloi said skirt. means being dispoled'at right angles minor axis and below and spaced from bosses;andi'urtherrigidstrutmeanshavinga lower coeillcient oi expansion than tint oi angles said'minor axis and'above andspaced from all oi meansbeingimbeddedintheme otsaid d e MPH-Emit.

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