US2067278A - Piston - Google Patents

Description

Jan. 12, 1937. NELSON 2,067,278

PISTON Filed May 28, 1935 4 Sheets-Sheet l INVENTOR: We?

MIL)

TTORNEY Jan. 12, 1937..

A. L. NELSON PISTON Filed May 28, 1955 4 Sheets-Sheet 2 10 i HQ 10 ii 122 ii mu m 116 14 :96 I INZIZNTORI BY I max

A TORNEY Jan. 12, 1937. E QN 2,067,278

PISTON Filed May 28, 1935 4 shee ts sheet 3 0 INVENTOR:

A ORNEY Jan. 12, 1937. NELSON 2,067,278

PISTON Filed May 28, 1955 4 Sheets-Sheet 4 Patented Jan. 12, 1937 PATENT OFFICE 11 Claims.

This invention relates to pistons, especially to pistons for use in internal combustion engines.

A particular object of the invention is to provide balancing ribs on the lower inner wall of the tion as hereinafter set forth and claimed.

In the drawings:

Fig. 1 is a side elevation of a piston embodying the invention;

Fig. 2 is a plan view of the lower end of the piston looking toward the head;

Fig. 3 is a sectional view on line 3--3 of Fig. 1;

Fig. 4 is a sectional view on line 4-4 of Fig; 3;

Fig. 5 is a view similar to Fig. 4, of a modification;

Fig. 6 is a sectional view on line 6-6 of Fig. 5;

Fig. 7 is a view similar to Fig. 4, but showing a modification;

Figs. 8 and 9 are views similar to Figs. 4 and 2 of a further modification.

The piston illustrated in the drawings is in general the type of piston described in my Patent No. 1,982,396. This piston includes piston pin.

bosses i0, opposite thrust faces ll, I2, and an annular part it below the pin bosses, which is reinforced by arcuate segmental ribs It covered by my Patent No. 1,830,172. The present invention relates particularly to the toothed ribs l5 located between the piston pin' bosses and the ribs iii.

Each rib i5 extends along the inner surface of the annular part i3 below a pin boss, and the ends of these ribs are spaced from each other behind the thrust faces in order to permit casting the piston in a permanent mold with a threepiece core, as fully explained in Patent No. 1,830,172. For this purpose the inner skirt wall in the vertical zone in the center of each thrust face is free of any inwardlyextending ribs or projections over a. considerable are, as will be clear from Figs. 2 and 3.

Each of the ribsi5 is cut through by one or more slots I6 which divide the rib into a plurality of separate, segmental portions. The slots l6 cut practically through the entire thickness of the rib so that outside of each slot the skirt wall has substantially its normal thickness, thus permitting the skirt to bend circumferentially at these points as freely as though the ribs i5 were not present. This free yielding of the ribs i5 is of particular importance in a strut-controlled piston of the type illustrated, as the struts tie rigidly together the parts of the skirt to which they are attached. It is obvious that the depth of the slots can be varied to alter the stiffness of the ribs.

The slots I6 are substantially parallel to the axis of the piston pin bosses, as illustrated, so as to permit casting the piston with a three-piece core. This arrangement of the slots permits moving the side cores toward the center of the piston in directions parallel to the axis of the pin bosses.

The ribs I5 are for the purpose of providing surplus material that can be machined away to bring the piston to a certain weight in order to balance it with others of a'set. This is usually done by machining away 'part of the-inner periphery of the ribs. The division of the ribs into separate tooth-like portions prevents distortion of first machined to an oversize, leaving say 10 grams of material to be removed in the final machining. Then if the final weight of the finished piston is to be 350 grams, metal is removed from the balancing ribs until the piston weighs- 360 grams. The piston is last given the finish grinding which removes the extra 10 grams from the exterior surface. If the balancing ribs were cast solid, the act of cutting away part of these ribs to balance the piston weakens the ribs and releases certain casting strains that were held incheck by the relatively stiff ribs during the preliminary machining of the piston, thus throwing the skirt out of round, twisting the pin bosses out of line, putting the ring grooves out of true, etc.

Another advantage of this construction is that the skirt remains of practically the same stifiness regardless of the amount of material removed from the ribs in balancing the piston. If the ribs were cast solid there would be a great difierence in the skirt stifiness, ranging from the full stiffening effect when the rib is left intact to the entire absence of the stiffening effect of the rib if the rib is entirely cut away. v

The toothed balancing ribs i5 can be used on any desired type of piston, and they can be 10- cated at any suitable position on the inside of the skirt. Figs. 5 and 6 show a modification in which the ribs l5 are located on the inner walls of the thrust faces in the horizontal zone of the piston pin bosses.

The reinforcing ribs It may be dispensed with, or they may be placed above the toothed ribs, as shown in Fig. 'I, which illustrates the application of the ribs to a piston of the all-aluminum trunk type.

In some forms of the invention the reinforcing ribs l4 may be attached to the toothed ribs l5, as shown in Figs. 8 and 9. In this case as much as necessary of the toothed balancing ribs Hi can be machined out, but the machining is never permitted to cut into the ribs Hi. Thus the ribs: It always provide definite minimum stifiness in the skirt even after all of the balancing ribs l5 have been cut away.

The present application is in part a continuation of my co-pending application Serial No. 631,968, filed September 7, 1932.

I claim:

1. A piston comprising a head, a skirt connected to the head, a balancing rib extending inwardly from the wall of the skirt, the balancing rib being formed with at least one slot extending toward the outer wall of the piston and dividing the rib'into a plurality of separate portions the said rib furnishing excess material and being designed to be cut away to balance the piston with others of a set without substantially altering the strength or stifiness of the skirt.

2. A piston comprising a head, a skirt connected to the head, a balancing rib extending inwardly from the wall of the skirt, the balancing rib being formed with a plurality of slots extending toward the outer wall of the piston and dividing'the rib into a plurality of separate portions the said rib furnishing excess material and being designed to be cut away to balance the piston with others of a set without substantially altering the strength or stiffness of the skirt.

3. A piston comprising a head, a skirt connected to the head, a pair of arc-shaped ribs extending inwardly at the lower part of the skirt, and located below the pin bosses, each rib being formed with at least one slot extending toward the outer wall 01 the piston and dividing the rib into a plurality of separate portions the said ribs furnishing excess material, and being designed to be cut away to balance the piston with others of a set without substantially altering the strength or stiffness of the skirt.

4. A piston comprising a head, a skirt connected to the head, a pair of arc-shaped ribs extending inwardly at the lower part of the skirt, and located below the pin bosses, each rib being formed with a plurality of slots extending toward the outer wall of the piston and dividing the rib into a plurality of separate, tooth-like portions the said ribs furnishing excess material, and being designed to be cut away to balance the piston with others of a set without substantially altering the strength or stiffness of the skirt.

5. A piston comprising a head, a skirt connected to the head and having a lower circular portion, piston pin bosses, partly-cylindrical portions extending upwardly from the circular portion, a pair of arc-shaped balancing ribs, each of the balancing ribs extending along the inner surface of the lower circular portion below a pin boss, the balancin ribs being spaced from each other at the inner surface of each of the partlycylindrical portions, each balancing rib being formed with at least one slot extending toward the outer wall of the piston and dividing the rib into a plurality of separate portions the said ribs furnishing excess material, and being designed to be cut away to balance the piston with .others of a set without substantially altering the strength or stifiness of the skirt.

6. A piston comprising a head, a skirt connected to the head and having a lower circular portion, piston pin bosses, partly-cylindrical portions extending upwardly from the circular portion, a pair of arc-shaped balancing ribs, each of the balancing ribs extending along the inner surface of the lower circular portion below a pin boss, the balancing ribs being spaced from each other at the inner surface of each of the partlycyiindrical portions, each balancing rib being formed with aplurality of slots extending toward the outer wall of the piston and dividing the rib into a plurality of separate, tooth-like portions the said ribs furnishing excess material, and being designed to be cut away to balance the piston with others of a set without substantially altering the strength or sifiness of the skirt.

7. A piston comprising a head, a skirt connected to the head, piston pin bosses, a pair of arcshaped balancing ribs extending inwardly at the lower part of the skirt, each balancing rib being formed with a plurality of slots extending toward the outer wall of the piston and dividing the rib into a plurality of separate, tooth-like portions, the slots being arranged in opposed pairs, the slots of each pair opening inwardly to-. ward each other in a direction substantially parallel to the axis of the pin bosses to permit molding the piston with a three-piece core, the said ribs furnishing excess material and being designed to be cut away to balance the piston with others of a set without substantially altering the strength or stiiiness of the skirt.

8. A piston comprising a head, a skirt connected to the head and having a lower circular portion, piston pin bosses, partly-cylindrical portions extending upwardly from the circular portion, a'

pair of arc-shaped balancing ribs, each of the balancing ribs extending along the inner surface ,of the lower circular portion below a pin boss, the

balancing ribs being spaced from each other at the. inner surface of each of the partly-cylindrical portions, each balancing rib being formed with a plurality of slots extending toward the outer wall of the piston and dividing the rib into a plurality of separate, tooth-like portions, the slots being arranged in opposed pairs, the slots of each pair opening inwardly toward each other in a direction substantially parallel to the axis of the pin bosses to permit molding the piston with a three-piece core, the said ribs furnishing excess material and being designed to be cut away to balance the piston with others of a set without substantially altering the strength or stifiness of the skirt.

9. A piston comprising ahead, a skirt connected to the head having opposite thrust faces and a lower circular portion, piston pin bosses, a pair of arc-shaped balancing ribs, each of the balancing ribs being located below a 'pin boss and extending along the inner surface of the lower circular portion, the balancing ribs being spacm from each other at the inner surface of each thrust face, the inner wall in the vertical zone in the center of each thrust face being free or any inwardly extending projections over a considerable arc, each balancing rib being formed with a plurality of slots extending transversely of the rib and dividing the rib into a plurality of toothlike portions the slots being arranged in opposed pairs, the slots of each pair opening inwardly toward each other in a direction substantially parallel to the axis of the pin bosses to permit molding the piston with a three-piececore, the said ribs furnishing excess material and being designed to be cut away to balance the piston with others of a set without substantially altering the strength or stiffness of the skirt.

10. A piston comprising a head, a skirt connected to the head and having opposite thrust faces and a lower circular portion, piston pin bosses, a pair of arcuate reinforcing ribs extending inwardly from the skirt wall, and a pair of arcuate balancing ribs, each balancing rib being divided by slots into a plurality of separate tooth-like portions, said balancing ribs furnishing excess material, and being designed to be cut away to balance the piston with others of a set without substantially altering the strength or stiiiness of the skirt.

11. A piston comprising a head, a skirt connected to the head and having opposite thrust faces and a lower circular portion, piston pin bosses, a pair of arcuate reinforcing ribs extending inwardly from the skirt wall, each of said reinforcing ribs being located with its intermediate portion below the opening of a piston pin boss, and an arcuate balancing rib located below each reinforcing rib, said balancing ribs being slotted into a plurality of separate tooth-like portions and furnishing excess material and being designed to be cut away to balance the piston with others of a set without substantially altering the strength or stifiness of the skirt.

ADOLPI-l'.

L. NELSON.

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