US2075290A - Piston - Google Patents

Description

PISTON m O a g W W h M. a mm F i a Y w w fl fl ATTQRNEY.

March 30; 1937. P. KALB ET AL Filed Jan. 16, 1955 Patented Mar. 30, 1937 UNITED STA'iE rarest OFFICE PISTON Application January 16, 1933, Serial No. 651,996

Claims.

This invention relates to pistons for use in internal combustion engines and has among its objects the provision of an improved piston construction and method of making same.

5 A further object of our invention resides in the provision of a piston of relatively light weight and having good heat conductive and wearing qualities. This invention combines in a novel way the desirable qualities of the present day aluminum pistons with the desirable wearing qualities of the cast iron piston.

In general, our invention consists in the provision of a piston having an aluminum head and a cast iron skirt or cross-head portion, these parts being connected in an improved manner whereby in operation under the influence of heat, the piston will maintain its desired shape and other characteristics without warping and scufling.

A further feature of our invention resides in 3D the provision of a novel method of manufacturing a piston whereby the cooperating piston parts are interconnected preferably by casting one into interengaged relation with the other. In our preferred form the aluminum head is cast in interengaging relationship with the cast iron skirt portion.

In carrying out our invention in the specific form illustrated, we have provided all contacts between the aluminum and cast iron in the form 1:!) of frusto-conical surfaces whose apices lie at the intersection of the piston axis and the piston pin or boss axis. Thus, we have provided a contact between the head and skirt in the form of a frusto-conical surface whose apex lies at the in- 33 tersection of the piston and boss axes, the axis of the cone lying along the piston axis.

The piston head is formed with bosses each having an inner cylindrical bore for receiving the usual piston pin. In order to prevent binding,

under heat expansion, at the bosses, we have formed a further frusto-conical surface contact between the skirt and each boss, the apex thereof lying at the aforesaid intersection of the piston and boss axes. The axes of these cones lie along the boss or pin axes adjacent each other.

By reason of the foregoing arrangement, all contacting surfaces between the piston parts are subjected to sliding on each other, the expansion 50 and contraction. taking place with respect to a common point whereby binding tendencies are eliminated and the piston will, at all times maintain its desired cylindrical shape without diutortion heretofore experienced in composite 55 pistons.

Referring to the accompanying drawing which illustrates one embodiment of our invention,

Fig. 1 is a side elevation View of our piston, partly in cross-section to illustrate one of the bosses,

Fig. 2 is a side elevation View at right angles to that illustrated in Fig. 1,

Fig. 3 is a section along the line 33 of Fig. 2, and

Fig. 4 is a sectional elevation view of the piston skirt, illustrating in dotted lines the manner of casting the head thereto.

Reference character A represents the piston assembly comprising a head'structure H] and a skirt or cross-head structure H, the former being of a relatively light weight material having goodheat conductivity such as the usual aluminum alloy ordinarily used in pistons for example, and the skirt 1 I being of a material having good wearing qualities. with the engine cylinder, such as cast iron for example. The head H) preferably has a diameter slightly less than skirt H, the latter having a working fit with the cylinder and the head carrying the usual piston rings (not shown) for holding the pressure and for carrying off heat from head it to the cylinder walls.

Head H) has depending therefrom, the arms l2 extending inwardly of the upper end of skirt II. Each arm i2 is provided with a laterally extending boss I3, the bosses having piston pin-receiving bores I4, whose common axis l5 intersects the piston axis I6 at the point H. We have not shown the piston pin in the bores M as this 15 well known in the art and forms no part of this invention per se.

Skirt H has diametrically opposite openings receiving the respective bosses i3, these openings being in the form of a frusto-conical surface l8, whose axis is the axis [5 aforesaid. The cones including surfaces l3 are diagrammatically represented at x and m in Fig. 1, these cones having their apices at IT.

The upper end of skirt i l is formed with a circumferentially extending frusto-conical surface l9, whose axis is the axis l6 aforesaid. The cone including surface 49 is diagrammatically represented at y in Fig. 1, this cone having its apex at H.

We preferably form the head In by casting the aluminum (in a suitable mold) in the form shown whereby the head bosses l3 form companion frusto-conical surfaces H8 in engagement with surfaces 58, and also the frusto-conical annular surface it in engagement with surface [9. The head and skirt are thus interengaged or interlocked by the frusto-conical surfaces and thereby held together. Furthermore, under heat variations, relative expansion and contraction between the head and skirt will take place by a sliding of surfaces l8, l8 and l9, IS in the direction of the cones forming these surfaces, whereby binding or distorting tendencies are eliminated.

It will be noted that we have a piston which is,

free from radially abutting surfaces which would 10 bind and cause distortion under heat; in our piston all abutting surfaces radially of the piston lie in cones as aforesaid whereby to permit free relative sliding without distortion.

We desire to point out that we do not limit our invention to the particular arrangement of parts illustrated as various changes may be made within the scope of our invention as defined by the appended claims. For example, the location of thelfrusto-conical surfaces axially of the piston is not important to a successful working of our invention, as long as these surfaces are parts of cones having apioes at a common point, or approximately so, in keeping with the beneficial results desired, While the best results of our invention are obtained by locating this common point at the intersection of the pistonand. boss axes, a shifting of this point within reasonable limits may, of course, be resorted to in keeping with the teachings of our invention. What we claim as our invention is:

. 1. In a piston, a skirt structure formed with diametrically opposite openings bounded by frusto-conical surfaces respectively lying in a cone whose apex is located substantially at the 5 intersection of the piston axis and the axis of said openings, said skirt having an outer circumferential frusto-conical surface lying in a cone whose axis substantially coincides with the piston axis and whose apex is located substantially at the intersection aforesaid, and a head structure provided with bosses respectively extending into said skirt openings, said head structure having frusto-conical surfaces complementary to said skirt surfaces and in sliding contact therewith. 2. In a piston, a skirt structure formed with diametrically opposite openings bounded by frusto-conical surfaces respectively lying in a cone whose apex is located substantially at the intersection of the piston axis and the axis of said openings, said skirt having an outer circumferential frusto-conical surface lying in a cone whose axis substantially coincides with the piston axis and whose apex is located substantially at the intersection aforesaid, and a head structure provided with bosses respectively extending into the said skirt openings, said bosses having frusto-conical surfaces fitting within the surfaces of said skirt openings respectively, said head structure having a frusto-conical surface engaging said circumferential frusto-conical surface of the skirt.

3. In a piston, a head structure, a skirt structure, one of said structures having a boss adapted to receive a piston pin, said boss shaving a frustoconical surface lying in a cone whose apex lies within the piston, and whose axis lies substantially along the axis of theboss, the otherof said structures having a surface complementary to said frusto-conical surface and in sliding contact therewith whereby relative tranverse movements due to expansion may freely takeplace.

between said structures without binding and dis! tortion thereof.

4. In a piston, a head structure, a skirt structure, one of said structures having'a boss adapted to receive a piston pin, said bosshaving a frustoconical surface lying in a cone whose axis lies substantially along the axis of the boss, the other of said structures having a surface complementary to said frusto-conical surface and in sliding contact therewith, the apex of said cone lying substantially in the axis of the piston.

5.'In a piston, an aluminum head structure formed with a lateral boss, and a cast iron skirt having an opening receiving the boss, said open ing and boss having engaging frusto-conical relative sliding surfaces lying in cones having axes extending transverse to the piston, axis and their apices lying within the piston.

LEWIS. P. KALB. ANDRE J. MEYER.

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