One piece cast steel monobloc piston

1. A piston comprising:

a piston head having a combustion bowl wall, an outer annular ring belt an inner annular wall, an annular oil gallery and an oil gallery floor;

a pair of pin bosses depending from said piston head having aligned pin bores;

a piston skirt;

said piston head, said pin bosses and said piston skirt are cast as a single piece of steel and including a plurality of ribs extending from said outer annular ring belt and from said inner annular wall into said oil gallery above said oil gallery floor, and including further ribs extending along an underside of said combustion bowl radially inwardly of said oil gallery.

2. The piston of claim 1 wherein said oil gallery floor is cast as one piece from said steel.

3. The piston of claim 2 including at least one opening cast in said oil gallery floor.

4. The piston of claim 1 wherein said ribs extend from said underside surface of said combustion bowl wall along said inner annular wall.

5. The piston of claim 4 including a plurality of ribs extending along an underside surface of said combustion bowl wall radially inwardly of said inner annular wall.

6. The piston of claim 1 wherein said pin bosses includes hollow regions communicating with said oil gallery.

7. The piston of claim 6 wherein said hollow regions are saddle-shaped and extend below said floor of said oil gallery into said pin bosses on either side of a pin bore formed in each of the pin bosses.

8. The piston of claim 4 wherein said inner annular wall is thinner in cross-section than that of said ring belt.

9. The piston of claim 8 wherein said inner annular wall is relatively thicker in cross section than that of said combustion bowl wall.

10. The piston of claim 1 including at least one window cast in said piston skirt.

11. The piston of claim 10 including four of said windows.

12. The piston of claim 1 wherein said ribs extending into said oil gallery vary in radial thickness.

13. The piston of claim 12 wherein the thickest of said ribs lie over said pin bosses in line with said pin bore axis.

14. A piston, comprising:

a piston head having an upper wall, a combustion bowl wall recessed in said upper wall and forming an associated combustion bowl, an outer annular ring belt wall extending downwardly from said upper wall, an inner annular wall spaced radially inwardly from said outer annular ring belt wall and extending downwardly from said combustion bowl wall, and a bottom wall extending between and interconnecting said outer annular ring belt wall and said inner annular wall and at least partially enclosing an annular cooling galley, each of said walls having a thickness and wherein the thickness of said outer ring belt wall is greater than the thickness of said inner annular wall, which in turn is greater than the thickness of said combustion bowl wall;

a pair of pin bosses depending from said piston head and having pin bores aligned along a common pin bore axis, said pin bosses being partially recessed such that said oil gallery extends down into hollowed regions of said pin bosses on either side of said pin bores, said bottom wall extending circumferentially between said pin bosses but being interrupted across said hollowed regions of said pin bosses, said bottom wall including at least two openings that are arranged on opposite sides of said pin bosses, said openings being spaced radially from said outer annular ring belt wall and from said inner annular wall, said openings being oblong and extending circumferentially along a length sufficient to render said oil gallery more open than closed in the circumferential direction across said bottom wall between said pin bosses; said outer annular ring belt wall and said inner annular wall including radial ribs extending into said oil gallery and at least partially across said bottom wall; and

a piston skirt, wherein said piston head, said pin bosses and said piston skirt are cast as a single piece of steel.