US1812696A - Piston - Google Patents

Description

Patented June 30, 1931 l UNITED STATES.

PATENT OFFICE STEPHEN D. EABTOG', 0F ST. LOUIS, MISSOURI, ASSIGNOR TO HARRY J. HATER, OF

, CINCINNATI, OHIO PISTON Application. filed December 18, 192-8. Serial No. 326,832.

My invention relates to improvements in pistons, and more particularly to pistons adapted for use in internal combustion ennes.

Better results are obtainedfrom internal combustion engines having light weight reciprocating parts, such as the pistons, and the light weight metals usually utilized for this purpose are aluminum, aluminum alloy,

magnesium and similar metals. These metals have properties which must be considered in the formation of pistons, namely, a relatively low specific gravity, a relatively high thermal conductivity, and a comparativel high 15 thermal expansion ratio. It is the o ject of this invention to produce a piston using these metals, in which the latter property 1s rendered comparatively ineffective for all practical purposes.

important object of this invention,

therefore, is the production of a piston so.

constructed that the heat `of combustion, which causes undesirable expansion of the piston skirt is so diverted and impeded in the course of its transmission fromthe head of the piston to its skirt, that its influence upon the skirt of the piston is reduced to a minimum.

Another object of my invention is to produce a piston, both thrust faces of which will be in constant contact with the surface of the cylinder walls.

Figure 1 is a front elevation of my im' proved piston,

Figure2 is a side elevation thereof, A Figure 3 is a vertical central sectional View on the line 3-3 of Figure 1, Figure 4 is a transverse sectional view takenA on the line 4-4 of Figure 2, and

circumferentially extending o ening 14.

The piston skirt is relieved by eing completely cutaway4 at diametrically opposite points, and said cutaway port-ions 15 extend from points spaced from the bottom of the skirt to the opening 14. Amilo or strut 16 is arranged centrally of each cutaway portion and connects t-he head or rim 11 of the piston with the portion of the skirt forming the lower side of the cutaway portion 15. The

struts 16 are oiiset inwardly to avoid contact with the cylinder walls, and .are formed integrally with the head and skirt of the piston.

Piston pin receiving hubs or bosses 17 are integrallyuformed on the struts 16 adjacent their centers, and are provided with the l'usual bores 18. These hubs preferably eX- tend inwardly be ond the struts 16, and while they may also extend outwardly beyond the struts, they must clear the cylinder walls. Transverse struts 19 connect the hubs 17 adjacent their inner ends, with the skirt 13 at the side edges of the cutaway portions 15. The struts 19 are arranged horizontally and function to resist the side thrust to which the piston is subjected when in operation.

Reinforcing ribs 19 are arranged interiorly of the struts 19, on the upper and lower edges thereof, and increase in width from the boss 18 to the piston skirt, as shown in Figures 4 and 5.

It will be seen, then, that the hubs 17 are joined at their outer ends to .the head and the lower portion of the skirt'by the substantially vertically extending struts 16, and

joined at their inner ends to the skirt by the transverse struts 19, which are arranged substantially horizontal. At a suitable position between the struts 16 and 19 there is an opening`20 dividing the inner end of each hub from the outer end thereof, and said opening 20 may be cutafter the piston is cast, but is preferably cast with the piston. The hubs 17 are consequently separated by the opening 20 into spaced inner and outer portions, the inner portions being integrally connected with the struts 19 and the outer portion of the hubs 17 being integrally connected with the struts 16 there being no direct connection between the struts 16 and the struts 19, or between the separated portions of the hubs. The struts 16 and 19 are, therefore, independent of one another, and heat passing from the head 1() through the struts 16 will not be conducted to the struts 19 and the adjoining skirt portions.

The non-thrust side of the piston skirt is provided with an inclined slit 21 which extends in a generally vertical directionv from the bottom of the skirt to the opening 14 which separates the head from the skirt, and the thrust side of the skirt is unbroken. A substantially continuous annular bearing surface is, therefore, formed adjacent the bottom of the skirt and is unbroken except for the single slit 21 which is slightly inclined from ythe vertical. While the slit 21 completely separates the non-thrust side of the skirt, 'the arrangement of the transverse struts 19 and the portions of the skirt below the openings 15 which are braced by the struts 16, is sulicient to hold the separated parts of the non-thrust side of the skirt in position.

The arrangement of the strengthening ribs 19 gives the necessary rigidity to the separated portions of the skirt.

In the operation of my improved piston, the head portion is subjected to direct heat generated by the explosion of gases in the combustion chamber, and this heat is conducted away through the integrally connected struts 16 and through the surrounding metal of the cylinder., The struts 16 are the only portions of the piston having direct or integral connection with the head of the piston and the only path by which the heatvmay be conducted to the piston skirt. The heat is so reduced when it reaches the bottom of the skirt that very little is transmitted upwardly to the side Walls of the skirt, `and is, therefore, comparatively ineffective due to the long and circuitous route which it must travel.

It will be noted that this construction results in the inner bosses operating at a lower temperature than the outer bosses, as they are separated from the head and receive heat from the head only through the struts 16 and the lower portions of the skirt.

The slit- 21 is for the purpose of allowing for expansion, but does not materially weaken the skirt because of the arrangement of the transverse ribbed struts 19 and the substantially c'ontinuous annular bearing surface at the bottom of the skirt, said arrangement effectively bracing the split portion of the skirt.

Referring to Figure 5 it will be seen that the under side of the piston head is provided with three spaced, substantially parallel ribs 22. These ribs extend down the inner sides `of the piston head to a point adjacent the hub 18, and consequently strengthen the rib 16, as seen in F iofure 3, as Well as the head of the piston, and provide for balanced heat dissipation.

This invention is an improvement on the piston covered b my pending application No. 227,705 filed ctober 21, 1927.-

While I have shown and described the preferred embodiment of my invention it is to be understood that various changes in the size, shape and arrangement of parts may bc resorted to without departing from the spirit of my invention or the scope of the subjoined claims.

Having thus described my invention, what I claim and desire to protect by Letters Patent is:

1. A piston comprising a head, skirt and piston pin hubs, eachl of said hubs comprising spaced portions, one of said spaced portions of each hub bemg connected to the head and the lower portion of the skirt, and the other portion-of each hub being connected to the sides of the skirt, said skirt being separated by a slit inclined from the vertical on the non-thrust side thereof.

2. A piston comprising a head, skirt and iston pin hubs, said hubs being split wherey they are divided into spaced portions, one

of said portions of each hub being joined by a member with the head and skirt and the other portion of each of said hubs being joined by a member with the sides of said skirt, said skirt being separated on its nonthrust side by a substantially vertical extending slit, the separated portions of the skirt being braced by the joining members.

3. A piston comprising a head, skirt and piston pin hubs, members joining said hubs with the head and skirt, and members joining said hubs with the side portions of the skirt, said hubs being splitl between the joinlng members whereby said joining members are independent of one another, and said skirt being separated; on its non-thrust side by an inclined slit, the separated portions gf the skirt being bracedfby the joining memers.

4. A piston comprising a head, a skirt spaced from said head by a circumferentially extending opening, said skirt'being provided with diametrically opposed cutaway portions, longitudinal struts connecting the head with the portions of the skirt at the lower ends of the cutaway portions and arranged adjacent the centers o the cutaway portions,

piston comprising" a head, a 'skirt' spaced from the head and provided with diametrically opposed cutaway portions extending from the top of the skirt to a. point spaced from the bottom thereof, whereby a substantially continuous annular bearing surface is provided adjacent the l,bottom of the skirt, a longitudinal strut extending across the center of each cutaway portion and integrally connecting the head with the portion of the skirt arranged at the bottom of the cutaway portion, said strut having a piston pin hub integrally formed therewith and extending inwardly therefrom, a transverse strut integrally connecting the inner end of each piston pin hub with the portions of the skirt adjacent the side edges. of the cutaway portions, the hubs being split between the longitudinal and transverse struts whereby the struts are each divided into spaced portions, the` outer portion being connected to the longitudinal strut and the inner portion being connected to the transverse strut, the skirt being provided on its non-thrust side with an inclined slit extending from the bottom of the skirt to the s ace between the head and skirt, the separated) portions of the skirt `being braced by the portions Pof the skirt below the cutaway portions, and by the 1ongitudinal and transverse struts.

6. A piston comprising a head, skirt and piston pin hubs, members joining said head and skirt, and members joining said hubs with the side portions of the skirt, said last mentioned members having reinforcing ribs extending from a point adjacent the hubs to the piston skirt, said hubs being split between 1the joining members whereby said joining members are independent of one another, and said skirt being separated on its non-thrust side by an inclined slit, the separated portions of the skirt being braced by the joining members and strengthening ribs.

7 A piston comprising a head, skirt and piston pin hubs, struts oining said hubs with the head and skirt, struts joining said hubs with the side portions of the skirt, and reinforcin ribs on said last-mentioned struts, said ri s increasing in width from the hubs to the piston skirt, and said hubs being split between the joining struts, whereby said struts are independent of one another.

.8. A iston-comprisin la head, a skirt separated rom said. head, piston pin hubs, members joining said hubs with the head and skirt, and members joining said hubs with the side portions -of the skirt, said hubs being split between the joining members whereby said joining members are independent of o ne another, and said skirtv being separated on its non-thrust side by an inclined slit, the separated portions of the skirt being braced and held in position by the last named joining members. j

9. A piston comprising a head, a skirt spaced from said head, piston pin hubs, struts joining said hubs with the head and skirt, and struts j oining` the hubs with the side portions of the skirt.,y said hubs being split between the struts whereby said struts are 1ndependent of one another and the first named struts are the only connection between the head and skirt, and said skirt being separated on its non-thrust side by an inclined slit, the separted portions of the skirt being braced and held in position by the last named struts. In testimony whereof I affix my signature.

STEPHEN D. HARTOG.

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