US1686357A - Piston - Google Patents

Description

Oct. 2, 1928.

E. M. WILLIAMS PISTON Filed Oct. 27, 1921 intended for use in the cylinders oi internal- Patent'ed Get. 2, i928.

barren res:

1 v EDWARD wILLIAMsoF ELYRIA, "0310.

rrs'ron.

- Application filed. October 27, 1921. Serial No; 510,866.

. Thepresent invention relates to a piston for-use in cylinders and is more particularly combustion engines. I

piston in and this is usually taken care or by mach1n-- p Experiment has demonstrated that when a piston or usual construct-ion such as a cast iron piston is in actual operation in a cylinder of an internal combustion engine, the temperature at the top end or head'of the piston is greatest and decreasestoward the inner end or skirt of the cylinder where the tem perature is the lowest. This will be evident because the head of the piston is exposed di rectly to the heat incident to the repeated explosions I ing an integralbody, the heat which is imparted to the head of the piston is in part 7 transferred to the body of the piston in accordance with the laws of the conduction 0fing a piston so'thatit is ofslightlytapering form. The difficulties and disadvantages which are incident to the usual typeo'l' cast iron pi'stons and the leakage'oi' oil around the pistonsinto the combustion chamber of'the engine or conversely the leaking ofgasolme past a piston lnto thecrank case, and ,addi

tionally, the excessive weight 0]: cast iron pistons andthe disadvantage o'fmoving the large mass 01 iron, are alltoo' well known to require comment. a

It is the purpose ofthis' inventlon'to provide apiston which is (so constructedthat by far the greater portion'of the heat which is imparted to the piston incident to its operation is retained in the head portion of the pis? ton and only a small fraction of that heat is transmitted to the central portion of thebody of thepiston; and to the skirt. of the "piston. Additionally, provision is also made so that heat which may .be'transmitted to the body of the piston is only transmitted in diminishing degreeto the skirt portion of the piston.

This construction enables a piston tojbe I of the fuel mixture. The piston be fitted much closer within the walls a .cylind'er and this results directly in. eliminating the usual sloppy fit of a pistonand on the other hand enables that the skirt'portion-of. the piston particularly, may beifitted rather exactly and have a much closer workingiit a 7 within thewalls or the cylinder than can possibly be attainedwiththe types ofpistons, with which Iain familiar.

The cylinder also provides a construction wherein the compressionrings may be as.-;

sembledi on the piston without the necessity of removingtho pistonfifrom the cylinder in which'lt may be placed.

" Reference should behad to theacconipanying drawings. forming apart of this specificationin which Fig. 1 is .a sectiona-leleva tiono'f a piston embodying my invention; Flg. 2 is atop plan view on reduced scale;

Fig. 8 is a plan view showing the compression rings and the tension.memberwhichpushes themoutwardly.

-Referring to the drawings, 11 indicates what may be termed the body of thepiston.

anditis provided with the inwardly extend-f ed'sl'eeves such as indicated at 2ttor theres I so ception of a wrist pinfthe same as in usual ractlce' The upper end of the body lis provided withan external wIGCQSS-JOI groove 1 which is indicated'at 3, this groove being indicated for the reception of; the compression ring as will be later described;

' At thecentral portion atthetop ofthe I body portion 1 there is abossz iin to which is threaded the member which holdslthe head of the piston in its attached relationship to j the body portion: as well be later described.

Atthe lower or inner end of thebody po tion there ispalso 'aninwarclly,"extencling p I groove or recess'as indicated at 5, this groove or recess being for the-reeeption'oi' the usual oilrings/f' p The bodyporti0n1'is made hollow according'to usu'al practice. I I The head'o'f the piston is indicated at 6 andit is provided wit-ha central retaining screw 7 1 which is threaded into a suitable opening in the boss 4 thus serving as aretaining means'for the head; i ihereare {also as indicated at 8 which prevent relative turning between thebody of the piston 1 andth'e head member 6.

' provi'ded'one ormore auxiliary screws such These "various threaded p members are made to have only a fairly close fit sonthat when the head of the piston bestated.

provide a gasket 9 which is made ofany suit,

able composition or material which is efficient from the standpoint of the non-conduction of heat. Asbestos is a material from which such a gasket maybe made. This gasket is retained between thetop of the body portion 1 and the-underside of the'head when the head is secured on the b. dy portion as before The skirtmember of the piston is made as a separate element and SECUI'Lhl to the body of,

the piston at the lower or open side thereof. In the present instance this is accomplished by providing the lower portion of the body 1 with an inwardly extending shoulder 1 which is threaded upon its interior surface. The skirt'member'proper which is represented at 10 has at one end a shoulder 10 and an upstanding neck 10", which on its outer surface is threaded and may be attached to the lower portion of the piston body 1 by the screw thread engagement which is suggested. This particular method of securing the two parts together is but suggestive of anydesired method. The width of the shoulder 10 is such that whenassembling with the body 1- the outer surface of the body 6 is substan-.

tiallyin the same cylindrical plane as the outer surface of the bodyjl of the piston.

It will thus be seen that the pistons-which has beendescribed is made up of three parts which may be described as, the head, the bodyv portion and'the skirt portion- The head is preferably made of a metal which has a low oo-efficient of expansion and one which is nonwarping under the action of the-high heat to which it is subjected when'in use. The

Iniddle'section or body portion of the piston is preferably made of amuch lighter metal 1 than the other portions and for this purpose aluminum or aluminum alloy has been found to be suitable. The lower or skirt portion of the piston is made of a material having a low co-efiicient of expansion, which metal at the same time has the properties of resistant to V wear.

The head member. 6 is made of such a diameterw'ith respect to a given cylinder into which it isto befitted so that when within thecylinder and 'under'workingconditions,

the expansion ofthe head under the tempera" tures to which it is subjected to in use, will cause suiiicient expansion so that the head portion will'have a nice working fit within the cylinder. The central part or body portion ofthe piston being made of material of low specific gravity will materially reduce the weight of the combined portions of the piston so that V the total weight of the three portions may be less than the weight of the usualcast iron piston of light dimensions. The body portion is made of such diameter with respect to a given cylinder into which it is tobe used, so that under expansion the body portion of in the cylinder.

the piston will have, anice working fit with The skirt portion is madeto haveadianieter, and clearance with respect to a given cylinder so that when in use and expanded by such heat'as it. receives, it will have a nice" working fit against the wall of the piston.

WVhen such a piston as has been described is used, in an internal combustion engine, the

first application of heat incident to the running of the engine comes upon the head ofthe piston and very quickly the head of the piston expands to'its ultimate amount.

Tlhe conduction of heat from the head to;

the body portion is materially reduced due to the provision of the heat insulating means betweenthe body portion and the head so that the body portion of the cylinder can never be come ashighly heated as would be the case if the body portion and head of the piston were integral. From the foregoing it will be readily deducedthat the heat which the skirtfportion of the piston receives, is Very much less than would bethe case were thepiston made as an integral structure and, experiment has 1 demonstrated as a fact that the transfer of;

heat from the head offthe piston to the skirt portion is so reduced over what would be the case in a solid plston, that the temperature which is attained by the skirt portion will never be so hlgh as to affect the lubricat ng qualities of' the oil used in crankcase lubri; cation, whereas with the solid types of pistons.

now in use the breakingdown of the lubricatmg oil in the crank case and destroying its lubricating properties is the usual occi'irren'ce unless a very good grade of oil be used, which isof course relatively expensive. 7 By making the piston inthe three parts as above suggested, the head maybe constructed so that} it will expand in accordance with the heat which it receives and when soheated, provide a nice fit within the cylinder, also the body. portion may be so made andlmachined that it willwhen expanded the heat which it receives, have a good workingfit in the cylinder, and the same is true with respect 'to the skirt portion. Therefore with each of these partsflof the piston being particularly constructed so as to take care of the temperatures to which they are individually subjected and at the same time provide a nice fit in the hind them, thus constantly urging the ring cylinder when in heated condition, insures that the piston under worklng conditions will at all portions of itsengagement with the walls of the cylinder have a proper fit and not a loose or sloppy-fit, and thereby the passage of oil beyond the piston into the combustion chamber is minimized.-

Due to the fact that the skirt portion 10 may be so nicely fitted within the cylinder due to the construction of the piston as before explained, the skirt portion of the piston will always be in bearing relationship with the wall of the cylinder and so serve as a sort of a' cross-head, and eliminate any other movement of the piston than a true reciprocating movement.

In the groove or recess?) there is in Fig. 3 and comprises the three sections which areindicated at 11, 11 and 11 The ends of each of these sections are provided with notched extensions such as indicated at- 12, which extensions overlap'and engaging each other in the manner shown in Fig. 3.

When these sections are inserted in the groove or recess 3 a spring member 13 is placed besections outwardly and against thewall of the cylinder. Attention'is called to the fact that by-the ring construction which has been shown the piston has been in use and it is desired to place a new compression ring in thersame, the compression ring may be placed, w thout removing the piston from the cylinder.

This may be accomplished by removing the head of the engine and reciprocating the piston until the head of the piston is at the top of its stroke. The head 6 may, then be removed, thus exposing the groove 3 and permitting the removal or placement ofthe seg' ments of the compressionring.

When a new compression ring is placed in a piston it is possible to use a rather stiff spring behind the segments of the ring, and by this I mean a spring which is much stifier than would be necessary in the actual operation of the piston. This will cause the segments of the ring to exert a rather heavy outward pressure against the inner wall of the cylinder.

The head may then be placed and the engine mechanically turned over for a desired period of time, thereby wearing in the ringsl After this wearing action has been permitted for a I located the compression ring which is shown in plan vlew in the under side of a ring segment.

sufiicient length of time, the head of the piston i may be removed; and a lighter springsubstie.

tu-ted 'forthe heavy spring which hadhereto: I

fore been used behind the compression ring. Then the'head of the piston may be replaced and t'he head of the ring assembled on'th'e block thereof.

By the procedure whichhas just been out I lined it isposs ble to givethe rings a pier; liminarywearing in, which in the usual types of piston can only be accomplished by actually wearing the rings inby use. This Wearing in action makes the engine Jvery still and all this may be to a large extent obvi:

ated with the type of piston herein proposed in the manner which has just been described.

In the groove or recess 5 is positioned the oil ringas indicated at 14. This oil ring is constructed with segments the same as explained with respect to the compression ring and the segments of the oil ring are pushed outwardly by means of a spring 15 in pre cisely the same manner as has before been described. 1

lflach of the segments of the oil ring and the compression ring are retained against undue radial movement by means of pins, one

of which is 'indicated at 16 in Fig. 1, one end 7 I of the pin being secured with a driving fit in an opening in the body member 1, whlle the other end of the pin extends into a slot I such as indicated at 17, which slot is formed slot is slightly elliptical in shape so as to permit a limited'radial movement of the ring sections.

Having described my invention, I claim:-

The I V 1. A piston comprising a body: portion,

head portion, which head .pOrtion is 'separate from but secured to the body portlon,

heat insulating means interposed between the head and body. portion'and a skirt portion associated with thebody portion which is made separate from but attached to the lower part of the body port-ion, thesaid head por-' tion and the said "skirt portion beingmade of metalwhich has a low co-elfic ent of-ex-,

pansion as-compared to that of the bod-y I portion. I v V,

2. A piston provided with a rln'g groove, aring in said'groove, said ring comprlsmg a plurality oflsimilar segments wlth overlapping end joints, a spring belnnd sald-seg ments and-urging them outwardly, and pins carried by the piston and engaging anedge of each of said segments at the center thereof to limit the radial movement of the segments 3. A piston having a body portion, a head which ismade distinct therefrom and ate 125 tached thereto and a skirtportion which is made separate from the body portion and attached to the lower endv of the body portion, said head and skirt being made of metal having a lowco-efficient of expansion and said body portion being made of a metal .130

Which is. materially lighter than themet al of the head and skirt.

4. A piston havinga hollow body portion provided With means for attachment to a connecting rod, a head separate from said body portion and-attached thereto, heat inof, said head and skirt being made of metal 10 i having a low CO-GffiC-lGIlt of expansiomfand I said body portion; being made of a. metal which is materially lighter than the metal of thehead and skirt.

y In testimony whereof, I hereunto afiix 15 signature.

E WARD W LLIA S. 7

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