US2136162A

US2136162A - Internal combustion engine

Info

Publication number: US2136162A
Application number: US4060A
Authority: US
Inventors: Ware Marsden
Original assignee: Packard Motor Car Co
Current assignee: Packard Motor Car Co
Priority date: 1935-01-30
Filing date: 1935-01-30
Publication date: 1938-11-08
Anticipated expiration: 1955-11-08

Description

Nov. s, 1938. M. WARE 2,136,162

INTERNAL COMBUSTION ENGINE Filed Jan. 30, 1935 Patented Nov. 8, 1938 UNITED STATES PATENT OFFICE Marsden Ware, Detroit,

Mich., assignor to Packard Motor Car Company, Detroit, Mich, a corporation of Michigan Application January 30, I935, Serial No. 4,060

6 Claims.

This invention relates to pistons for internal combustion engines and more particularly to pistons for use in such engines.

One object of the present invention is to produce a novel and improved piston for internal combustion engines which is light in weight, strong and durable in construction and having a skirt which is capable of expansion under the high temperatures to which the piston is subjected in operation without undue friction against the walls of the cylinder and which will prevent the passage between the same and the cylinder wall of a greater quantity of oil than that required for proper lubrication at any point in the periphery of the piston.

Another object 01' the invention is to produce an improved piston construction having a skirt which is integrally attached to the head to form a structure sufficiently rigid to withstand in a reliable manner the strain of piston operation, which is shaped to fit closely to the cylinder wall entirely about the periphery of the piston at one or more points axially thereof and which will yield when expanded under the high temperatures within the engine cylinder.

With the above and other objects in view the invention consists in a piston construction embodying the novel and improved features hereinafter described and particularly pointed out in the claims, the advantages of which will be readily understood by those skilled in the art.

The invention will be clearly understood from the accompanying drawing illustrating constructions embodying the invention in its preferred form and the following detailed description of the constructions therein shown.

In the drawing, Fig. l is a view partially in side elevation and partly in vertical section illustrating an engine cylinder and a piston embodying the invention engaging therein.

Fig. 2 is a view in horizontal section taken substantially on the line 2-2 of Fig 2 with portions of the piston and cylinder broken away.

Fig. 3 is a view in horizontal section taken substantially on the line 3-3 of Fig. 1.

Fig. 4 is a view in horizontal section taken substantially on the line 4-4 of Fig. 1.

Fig. 5 is a view in side elevation illustrating a piston embodying the invention having a diilerent slot arrangement than that shown in Fig. l and,

Fig. 6 is a view in side elevation illustrating a piston having a still different slot arrangement.

In the form of the invention shown in the drawing, the invention is embodied in a piston indicated as a whole at 2 and shown in Figs. 1 to (Cl. 309-1l) 4 inclusive engaging in the cylindrical bore in an engine cylinder 3. 4 indicates a connecting rod and 5 a piston pin for connecting the piston with one end of the connecting rod. The piston is provided with a head 6 formed with peripheral grooves I in which are fitted piston rings 8 and a skirt 9 integrally attached directly to the head, preferably about the greater part of the periphery of the piston. The piston is provided with piston pin bosses Ill in which the piston pin 5 engages. These bosses are integrally connected with the portion of the skirt extending between the same and the head and ribs, one of which is indicated at H, extend from the bosses along the inside of the skirt to the head to give added strength. The bosses are each directly and integrally connected at the sides with the upper part of the skirt and at the bottom with the portion of the skirt below the same. The peripheral portion of the piston adjacent the piston pin bosses is relieved as indicated at I! to provide ample clearance at all times between these portions of the piston and the cylinder wall The head is separated from the skirt on one side of the piston by a transverse slot I3 and the skirt is formed with a longitudinal slot I4 extending downwardly from the slot l3 and terminating at some distance from the lower end of the skirt. The transverse slot I3 reduces the heat conduction between the head and the skirt and the longitudinal slot l4 together with the slot i3 allow the upper portion of the skirt to yield during the expansion of the skirt.

In order to enable the portion of the skirt between the piston pin bosses and the lower end thereof to yield when expanded against the cylinder wall under the high temperatures to which the piston is subjected in the engine cylinder, the skirt, in a zone between said bosses and the lower end portion thereof, is given a cross section normal to the piston axis in which the periphery has the form of a convex curve and the diameter of the skirt in one direction is substantially greater than another diameter perpendicular thereto. In forming the piston skirt with a zone of this cross section, the bearing surface is preferably made generally elliptical or oval the term elliptical not being restricted to a bearing surface having the form of a mathematical ellipse. In the construction shown, the skirt is made elliptical in cross section normal to the axis in a zone extending on each side of the line 3-3 of Fig. l on which the section shown in Fig. 3 is taken. In forming this elliptical cross section the minor diameter or axis of the piston in said zone is preferably located substantially parallel with the axis of the piston pin bosses. The skirt along said elliptical zone is arranged to engage the wall of the cylinder at the respective ends of the major diameter or axis and for some distance on each side of the ends of said axis and to leave a clearance at and adjacent the respective ends of the minor axis as shown in Fig. 3. This clearance varies with the expansion of the piston in the cylinder.

The difference in the length of the major and minor axes of the piston in this zone may differ in pistons of different size and also may be varied in pistons of the same size. For example, it is proposed to form the cross section in this zone of a piston having a diameter of 3 at the bottom of the skirt so the major axis is at least .005 to .007 of an inch greater than the minor axis. The difference in the length of the major and minor axes may, however, be made as much as .012 of an inch or even more if desired.

To give the lower portion of the skirt a bearing against the cylinder wall about the entire periphery thereof and to prevent the passage of oil between the skirt and said wall in excess of that required for proper lubrication, the end portion of the skirt remote from the head is made substantially circular in cross section normal to the axis and is arranged to fit closely to said wall at all points in the periphery of the skirt. The skirt is preferably made substantially circular in cross section in a relatively narrow zone at the lower end thereof. This zone, however, may be given any width to furnish the desired bearing area for engagement with the wall of the cylinder and to produce the desired results in the forming of an oil film between the skirt and said wall. Fig. 4 is a section of the piston and cylinder taken through this zone. This portion of the skirt will act to spread the oil in a thin lubricating film over the inner surface of the cylinder and the lower edge of the skirt will collect the excess of oil and cause the same to be drained of! at the bottom of the cylinder.

The zone of the piston skirt having an oval or elliptical cross section preferably blends into the zone having a circular cross section as shown in Figs. 1, 5 and 6. Thus the minor axis of the skirt in this zone gradually increases from the upper to the lower portion of said zone and becomes substantially equal to the major axis at the lower end of said zone as shown in Fig. 1.

To enable the lower end portion of the skirt to expand without binding against the walls of the cylinder, the skirt is formed with one or more slots i 5 extending upwardly from the lower end of the skirt preferably to a point or points substantially opposite the lower end of the slot l4 peripherally of the piston. Figs. 1, 2 and 3 show these slots located in different positions about the periphery of the piston skirt. In the construction shown in Fig. 1 the piston is provided with a single slot l5 located on the same side of the skirt as the slot l4 and generally in line with the slot I4, axially of the piston. In the construction shown in Fig. 5 the piston is provided with two slots l5, each located. substantially degrees from the slot ll about the periphery of the piston. In the construction shown in Fig. 6, the piston is provided with a single slot I! located on the side thereof opposite the slot II and substantially degrees from the slot ll about the periphery of the piston.

In addition to the advantages above pointed out, the above construction results in a piston which is strong, sturdy and durable and in which the skirt, because of its rigid connection with the head except at the point at which the slot I3 is formed, is not liable to get out of alignment axially with the head. The strength of the construction enables the piston to be made lighter than certain constructions now in extensive use upon automobile engines. The skirt is sufficiently yielding to prevent the same from binding against the cylinder wall when expanded and at the same time has the stiffness required to enable the same to withstand in a reliable manner the strains to which it is subjected in operation. The slots l5 allow the lower end portion of the skirt, when expanded against the cylinder wall 2, to yield sufficiently to prevent the same from binding or exerting undue friction. The slots, however, extend only a short distance upwardly from the end of the piston and the lower end portion of the piston is therefore fairly stiff.

As the increase in the length of the minor axis of the skirt in the zone having an oval or elliptical cross section tends to diminish the yieldability of the skirt from the upper to ward the lower portion of said zone, the slots l5 tend to give a flexibility to this part of the skirt progressively increasing in the said direction.

It is to be understood that the invention is not limited to the particular construction of the illustrated embodiment of the invention but that the said construction is merely illustrative of the invention and that the invention may be embodied in other forms within the scope of the claims.

Having explained the nature and object of the invention and having specifically described a construction embodying the invention in its preferred form what is claimed is:

l. A piston for internal combustion engines having a head, a skirt integrally connected at its upper end directly with the head, and pin bosses integrally attached directly to the skirt, the skirt having a circular peripheral bearing surface at the end remote from the head, said skirt having its periphery relieved about the pin bosses and the peripheral bearing surface intermediate the circular bearing surface and the relieved portions being elliptical in cross section normal to the axis of the piston, the elliptical bearing surface blending into the circular bearing surface axially of the piston, said skirt having axially extending slots therein terminating short of each other in the elliptical cross sectional portion thereof.

2. A piston for internal combustion engines comprising a head, a skirt integrally connected at one end with the head and partially separated therefrom by a slot extending transversely of the piston axis, and a pair of aligned pin bosses on the skirt, a slot extending axially of the skirt between and co-extensive with the pin bosses and connected with the transverse slot, and another slot extending axially in the skirt from the end opposite the head to a point short of the other axially extending slot, said skirt being circular in cross section at the end remote from the head and ovate in cross sectional portion adjacent to and between the axially extending slots.

3. A piston for internal combustion engines comprising a head, a skirt integrally connected at one end with the head and partially separated therefrom by a slot extending transversely of the piston axis, and a pair of aligned pin bosses on the skirt, a slot extending axially of the skirt between and co-extensive with the pin bosses and connected with the transverse slot, and another slot extending axially in the skirt from the end opposite the head to a point short of the other axially extending slot, said axially extending slots being spaced circumferentially in the skirt more than 90, said skirt being circular in cross section at the end remote from the head and ovate in cross sectional portion adjacent to and between the axially extending slots.

4. A piston for internal combustion engines comprising a head, a skirt integrally connected at its upper end directly with the head and partially separated therefrom by a slot extending transversely of the piston axis, and a pair of aligned pin bosses extending interiorly of said skirt and formed therewith, said skirt having a slot extending axially thereof between the pin bosses and co-extensive therewith and connected with the transverse slot, said skirt having another axially extending slot spaced circumferentially from the first mentioned axially extending slot and extending from the end of the skirt remote from the head to a point short of the first mentioned axially extending slot, the periphery of said skirt surrounding said piston bosses being relieved, the peripheral surface at the end of said skirt remote from the head being circular and the peripheral surface of said skirt adjacent to and between the axially extending slots being formed oval in cross section.

5. A piston for internal combustion engines comprising a head, a skirt integrally connected at one end directly to the head and partially separated therefrom by a circumferentially extending slot, and a pair of aligned piston bosses extending interiorly of said skirt and formed therewith, the peripheral surface of said skirt being relieved in the zones of the piston pin bosses, said skirt having a slot therethrough extending axially between the pin bosses and from the circumfercntial slot to a point substantially on a circumferential line with the relieved peripheral zones of the skirt remote from the head, said skirt having another slot therethrough extending axially from one of the relieved peripheral zones to the skirt end remote from, the head, said skirt being circular in cross section at the end remote from the head and ovate in cross sectional portion adjacent to and between the axially extending slots.

6. A piston for internal combustion engines comprising a head, a skirt integrally connected at one end directly with the head and partially separated therefrom by a circumferentially extending slot, and a pair of aligned piston bosses extending interiorly of said skirt and formed therewith, said skirt having a slot extending axially thereof between the piston bosses and co-extensive therewith and connected with the circumferentially extending slot, the periphery of said skirt in the zones of the piston bosses being relieved, the peripheral surface at the end of said skirt remote from the head being circular and the peripheral surface of said skirt from the circular peripheral surface to the adjacent relieved portions being ovate in cross section, and said piston skirt having slots therethrough extending axially from the relieved peripheral zones to the end of the skirt remote from the head.

MARSDEN WARE.