US2248175A - Piston - Google Patents

Description

July 8, 1941. F. JARDINE 2,248,175

PISTON Original Filed Jan. 6, 1926 ww Tb TORNEYS Patented July 8, 1941" PISTON Frank Jardine, Cleveland, Ohio, assignor, by mcsne assignments, to The Cleveland Trust Company, as trustee, Cleveland, Ohio, a corporation of Ohio Continuation of application Serial No. 79,527, January 6, 1926. This application October 22, 1932, Serial No. 639,139

14 Claims. (01. 309-13) This invention relates to pistons for internal combustion engines or the like, and more particularly to pistons made of some metal having a relatively high co-efiicient of expansion such as aluminum or aluminum alloy, or the like, to be used in a cylinder made of a material having a relatively low co-efiicient of expansion such as cast iron or the like.

This application is a continuation of my copending application, Serial No. 79,527, filed January 6, 1926. The piston forming the subject matter of this invention is an improvement on the piston claimed in the co-pending application of Jardine and Cooper, Serial No. 79,651, filed January 6, 1926, and also embodies the broad invention claimed in my co-pending application, Serial No. 47,214, filed July 31, 1925.

It is well known that such pistons possess many desirable qualities such as lightness, high heat conductivity and the like, but since the coefllcie'nt of expansion due to heat of such materials difl'ers from that of the cylinders in which they operate, difficulties and disadvantages are encountered at various temperatures, for example, pistons that will not slap when cold will stick when hot,. and vice versa.

The principal object of my invention is to provide a piston made of aluminum, aluminum alloy, or the like, which can be fitted with a very small clearance when installed and which clearance will be substantially maintained throughout the temperature ranges met in practice, without slapping, binding or scoring of the cylinder or undue wear on the piston itself.

These and other objects of my invention as well as the invention itself will be better understood from a description of one or more structures embodying the invention;

In the drawing forming a part of this specification- Figure l is a side elevation of a piston-embodying my invention;

Figure 2 is a section thereof along the line 2-2 of Figure 1;

Figure 3 is a bottom plan view thereof;

face I5 has its upper edge separated from the ring flange by an air gap ii. The piston is provided with bosses l1 and II, to receive the wrist pin, which are arranged in alignment on opposite sides of the piston and integrally connected to the head by piers depending from the ring flange. To reduce the weight of metal used to a minimum while retainingsufilcient lateral rigidity, the piers as illustrated are recessed above the wrist pin bosses l1 and I8 leaving spaced relatively wide webs l9 and 26 as shown in Figure 1 connecting the boss II to the ring flange II and corresponding spaced webs connecting the boss 18 to the ring flange, one of which is illustrated in Figure 2 at 2|. The bosses are connected to the skirt by laterally extending webs 22 and 23 integral with the bosses l1 and I8 and merging into integral enlargements 39' which in turn merge into the thrust face It near the edge thereof. In the embodiment 'disclosed no lateral connection is provided between the bosses and thrust face IS in order to permit the operation of the piston during expansion and contraction to be described hereinafter. Webs 26 are preferably arranged in the piston headabove the boss carrying piers'to strengthen the ring flange of the head at these points. The skirt is cut away as shown at 21 and "about the bosses l1 and I8 and the bosses are set within the cylinder defined by the thrust faces in order to permit expansion of the bosses along the wrist pin axis without contacting the cylinder wall of the engine. The piston skirt is made substantially continuous below the openings 21 and 26 while being provided with means to absorb the circumferential expansion of the lower part of the skirt. In this instance bands 29 and 30 integral with the thrust faces I and II constitute continuations thereof below the openings Hand 28.

The bands 29 and are provided with slots 3| and 32 respectively which are spanned on the interior of the piston by integral culvert-shaped Figure 4 is an elevation of the member A hereinafter to be particularly described.

Referring to the drawing the piston illustrated. herein embodies a head 9 having a top wall l0 and a depending cylindrical ring fiange I l grooved at I! to receive piston rings, The piston sldrt is shown generally at I3 and comprises thrust members 24'and 25 which by reason of their shape possess suflicient resiliency to permit substantial closing of the slots 3| and 32 to absorb circumferential-expansion at the bottom of the skirt and prevent this portion of the skirt from sticking in the engine cylinder. The piston skirt thrust faces I4 and l5 are connected together by members of a material having a lower coefficient of expansion than the skirt to maintain the expansion thereof constant with the expansion of the engine cylinder, or so nearly thereto,

. that though there is very little clearance at the time the pistons are installed such clearance is substantially maintained and there is no slap. no sticking and no scoring or undue wear.

In the embodiment shown, strips or plates of the desired material are used to inter-connect the parts of the skirt. These strips are members such as A, Figure 4, which are best made of iron, steel or the like, and which are formed with central openings to provide the lateral branches 33 and 34 and the vertical branches 35 and 36. The lateral branch 33 is formed with a projection 31 which assists in positioning the member A in the mold. The members A are secured in proper position in the piston by surrounding or encircling the lateral and vertical branches by integral bands of aluminum. The upper lateral branch 33 of each strut extends directly through the respective boss carrying pier between the boss and the ring flange of the head. When the piers are recessed as illustrated in Figures 1 and 2 ea-cn branch 33 extends through the webs as I! and 20 in Figure 1 so that the branch is completely surrounded by two bands of aluminum integral with the head and the respective wrist pin boss thereby preventing vertical displacement of thebranch. The vertical branches 35 and 36 are embedded in the buttresses 33 and 39' so that the material of the buttresses completely cocking out of line since the more rapidly expanding aluminum steel combinationat the bottom will compensate for lower temperatures there. Nor will there be danger of binding at the bottom of the piston skirt when the circumference of the skirt, is complete, since the slits 3| and 32 permit circumferential expansion and the resflient culverts will insure the expansion into these slits instead of outward and away from them. For while the parts 24 and 25 of the culverts expand giving the required expansion perpendicular to the wrist pin axis, circumferential expansion of the culvert, will bring the culvert ends towards each other and thus tuck in the ends of the strap- like members 29 and 30 so they will not project out radially and injure surrounds the vertical branches of the member A and prevents lateral displacement of these branches. The buttresses 39' being integral with the lateral webs 22 and 23 connected to the wrist pin bosses l1 and 18 the vertical branches of 1 the member A embedded in these buttresses are held in position with respect to the wrist pin bosses. The webs 22 and 23 and the integral buttresses 39' constitute homogeneous bands extending laterallyfrom each pin bossand surrounding or encircling one of the vertical branches of each of the struts, The lateral branches 34 pass directly through and are completely surrounded by depending projections from the bosses l1 and II which surround the branches 34 as indicated at the cylinder walls.

The operation is as follows: The piston is fitted with very little or almost no clearance. As the pistonheats, the bosses tend to move outward, for which movement there is ample allowance. The expansion in the other direction will be from, the member l4 and will be the resultant expansion of the members 33, 34, 24 and 25 plus, of course, expansion in the thrust faces, and these parts are so regulated that the piston walls will follow the cylinder walls with fidelity. Contraction will ,be in reverse of expansion.

The piston is very staunch and easily machined. The heat conduction from the head is efficient. The explosion load is best taken on the thrust face l4 and the inertia load on the face l5.

It will be seen that although I make my piston of a continuous, in fact, in the embodiment illustrated, an integral piece of aluminum or the like, I do not shackle or loop the skirt with iron bands or the like, nor do I separate or isolate the parts one from the other, but employ aluminum and 4| and 43. In order to provide the novel operation of the instant embodiment the lateral branches of the members 'A pass slidably through the material of the bosses above and below the same as indicated at 40, 4|, 42 and 43. By arranging the material of the piston in the form of bands about the various branches of the struts in this manner, it is unnecessary to attempt to secure a locked connection between the material of the members A and the aluminum of the piston. The bands of aluminum surrounding the branches of the members A effectually position the members in the piston without regard to the nature of the bond, if any, between the two different metals.

By connecting the piston skirt thrust face parts together with both iron and aluminum, I avoid slapping at the high temperatures and danger of cooking of the member l5 out of normal due to unequal heating and consequent expansion at the top and bottom of the skirt. The members 33 and 34 are usually and best made of steel which usually has a lower co-efllcient of expansion than cast iron so that the cast iron cylinder will expand away from the piston and slappingwill occur at high instead of low temperatures. By maintaining the aluminum connection circumferentially this is avoided, since the more rapidly expanding aluminum will compensate for the under expansion of the steel members with the result that the net expansion willbe substantially that of the cast iron cylinder.

There will also be no danger of the member I! iron parts 'in such arrangements that I eliminate from the pistons the faults and vices of the prior iron and aluminum pistons.

Where I have used aluminum in this specification I have meant to include aluminum alloy I also.

While I have illustrated and described the embodiment of my invention and the particular details, I wish to be limited neither to the embodiment nor the details thereof, since many departures from both may be made without departing from the spirit of the invention.

I claim:

1. A piston comprising a head, piers depending from the head, cylinder bearing portions on opposite sides of the piston, a pair of struts extending between the cylinder bearing portions, each strut being formed with an' upper branch and a lower branch, and each branch of each strut being completely encircled by the material of the piers.

2. A piston comprising a head, piers depending from the head, cylinder bearing portions on opposite sides of the piston, the head, piers and cylinder bearing portions being formed of aluminum, a pair of struts of difierent material extending between the cylinder bearing portions, each strut being held by four uninterrupted bands of aluminum which are integral with the piers and cylinder bearing portions.

3. A piston comprising a head, piers depending from the head, piston pin bosses carried by the piers, cylinder bearing portions on opposite sides of the piston, a pair of struts extending between the cylinder bearing portions, each strut extending across the piston both above and below the piston pinbosses, each strut being imbedded in a pier and being completely encircled b an uninterrupted band of the material of the ier. I

4. A piston comprising a head, piers depending from the head and carrying piston pin bosses,

terial less expansible than that of the piers,,each I strut extending across the piston both above and below the piston pin bosses, each strut being imbedded in a pier and being entirely encircled by an uninterrupted band of the material of .the

pier.

5. A piston comprising a ing from the head, piston pin head, piers dependbosses carried by the piers, cylinder bearing portions on opposite sides of the piston, a pair of struts extending betweenthe cylinder bearing portions, eachstrut extending across the piston both above and below the piston pin bosses, each strut being ontirely encircled by an uninterrupted band of the material of the pier, and a piece of material integral with and extending laterally from each pin boss and entirely encircling part of a strut.

6. A piston comprising a head, piers depending from the head and carrying piston pin bosses, cylinder bearing portions on opposite sides of the piston, the head, piers and cylinder bearing portions being formed of light weight material, a pair of struts extending between the cylinder bearing portions, the struts being formed of a material less expansible than that of the piers, each strut extending across the piston both above and below the piston pin bosses, each strut being imbedded in a pier and being entirely encircled by a continuous band of the material of the pier, and a piece of material integral with and extending laterally from each pin boss and entirely encircling part of a strut.

7. A piston comprising a head, piers depending from the head and carrying piston pin bosses, cylinder bearing portions on opposite sides of the piston, a pair ofstruts extending between the cylinder bearing portions, each strut having a central opening about the piston pin axis, the portion of each strut below the central opening being completely encircled by a continuous band of the material of a pier, and a tie extending from each piston pin boss to a cylinder bearing portion and integral therewith.

8. A piston comprising a head, piers depending from the head, and carrying piston pin bosses,

.cylinder bearing portions on opposite sides of the piston, a pair of struts extending between the cylinder bearing portions, each strut being imbeddr-d in a pier and being completely encircled by an uninterrupted band of the material of the pier.

9. Apiston comprising a head, piers depending from the head, spaced cylinder bearing portions on opposite sides of the piston, a pair of chordal struts extending between the cylinder bearing portions, each strut being formed with an upper branch and a lower branch, and each of said branches of each strut being completely encircled by the material of the piers.

10. A piston comprising a head, piers depending from the head, piston pin bosses carried by the piers, spaced cylinder bearing portions on opposite sides of the piston, a pair of chordal struts extending between the cylinder bearing portions, each strut extending across the piston both above and below the piston pin bosses, each strut being embedded in a pier and being completely encircled by an uninterrupted band of the material of the pier passing under the bottom edge of the strut and holding it against vertical movement.

11. A piston comprising a head, piers depending from the head and carrying pistompin bosses,

cylinder bearing portions on opposite sides of the piston, the head, piers and cylinder bearing portions being formed of aluminum, a pair of chordal struts comprising ferrous metal plates having central openings extending between the cylinder bearing portions, each strut extending across the piston both above and below the piston pin bosses, each strut being embedded in a pier and being entirely encircled by an uninterrupted band of the material of the pier passing under the bottom edge of the strut and holding it against vertical movement.

.12. A piston comprising a head, piers depending from the head, and carrying piston pin bosses, cylinder bearing portions on opposite sides of the piston, a pair of struts extending between the cylinder bearing portions, each strut being imbedded in a'pier and being completely encircled by an uninterrupted band of the material of the pier, and a tie extending between and integral with each piston pin boss and a cylinder bearing portion, each tie including means passing around an end edge of a strut.

13. A piston comprising a head, piers depending from the head, and carrying piston pin bosses, cylinder bearing portions on opposite sides of the piston, a pair of struts extending between the cylinder bearing portions, each strut being imbedded in a pierand being completely encircled by an uninterrupted band of the material of the pier, one of said cylinder bearing pcrtions being connected to said bosses by connectors integral therewith which are substantially rigid in the line of thrust from said bosses and the other of said cylinder bearing portions being movable with respect to said bosses.

14. A piston comprising a head, piers depending from the head and carrying piston pin bosses, cylinder bearing portions on opposite sides of the piston, the head, piers and cylinder bearing portions being formed of light weight material, a

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