Monobloc piston having open floor
View Patent ↗A monobloc piston assembly has at least two parts fixedly joined together forming a piston body having an oil cooling gallery. The oil cooling gallery is defined by an upper wall, a lower wall, and a pair of radially spaced inner and outer annular walls. A skirt is formed as one piece and of the same material with at least one of the two parts and depends generally along a longitudinal axis from the lower wall. A pair of pin bosses are spaced laterally from the longitudinal axis and depend generally from the lower wall. At least one elongated opening extends generally between the pin bosses with the opening preferably spanning a substantial portion of the distance between the pin bosses. Oil flows into and out of an oil cooling gallery through the opening.
1. A monobloc piston assembly, comprising:
separately fabricated upper and lower piston crown parts joined together to form an oil cooling gallery boxed by a top wall, a pair of radially spaced side walls and a bottom wall;
a pair of pin bosses fabricated as one piece with said lower crown part;
a piston skirt fabricated as one piece with said lower crown part; and
at least one oil passage slot formed in a region of said bottom wall extending between said pin bosses on at least one side of said piston assembly and having a length in the circumferential direction of said piston assembly that is greater than a with of said at least one oil passage in a radial direction of said piston assembly.
2. The assembly of claim 1 wherein said oil cooling gallery is substantially open to the bottom on opposite sides of said piston assembly between said pin bosses.
3. The assembly of claim 1 wherein said oil cooling gallery is substantially closed in regions extending across said pin bosses.
4. The assembly of claim 1 wherein said piston skirt extends between said pin bosses and said at least one oil passage is disposed radially inwardly of said piston skirt.
5. The assembly of claim 1 wherein said at least one oil passage has a length in the circumferential direction of the piston assembly that is at least twice as great as a width of said at least one oil passage in a radial direction of said piston.
6. The assembly of claim 1 wherein said oil passage extends substantially between said pin bosses.
7. The assembly of claim 1 including at least one reinforcement web extending radially of said piston assembly and dividing said oil passage into at least two adjacent portions.
8. The assembly of claim 7 wherein said reinforcement web is substantially perpendicular to a common axis of said pin bosses.
9. The assembly of claim 1 wherein said oil passage is arcuate in shape.
10. The assembly of claim 1 wherein said upper and lower crown parts are fabricated of steel.
11. The assembly of claim 1 wherein said lower wall is fabricated as one piece with said piston skirt.
12. The assembly of claim 1 wherein there are said oil passages provided on opposite sides of said piston assembly between said pin bosses which are balanced with respect to one another.
13. The assembly of claim 12 wherein said opposite oil passages are symmetrical.
14. The assembly of claim 1 wherein said upper and lower crown parts are joined by welding.
15. The assembly of claim 1 wherein said upper and lower crown parts are joined by friction welding.
16. The assembly of claim 1 wherein said upper crown part includes a plurality of ring grooves and combustion bowl.
17. The assembly of claim 16 wherein said upper crown part includes a plurality of valve pockets.
18. The assembly of claim 1 wherein said oil passages extend no further than said piston skirt.
19. A monobloc piston assembly, comprising:
separately fabricated upper and lower piston crown parts joined together to form an oil cooling gallery boxed by a top wall, a pair of radially spaced side walls and a bottom wall;
a pair of pin bosses fabricated as one piece with said lower crown part;
a piston skirt fabricated as one piece with said lower crown part; and
at least one oil passage slot formed in a region of said bottom wall extending between said pin bosses on at least one side of said piston assembly having a length in the circumferential direction of the piston assembly that is at least twice as great as a with of said at least one oil passage in a radial direction of said piston.
20. A monobloc piston assembly, comprising:
separately fabricated upper and lower piston crown parts joined together to form an oil cooling gallery boxed by a top wall, a pair of radially spaced side walls and a bottom wall;
a pair of pin bosses fabricated as one piece with said lower crown part;
a piston skirt fabricated as one piece with said lower crown part; and
at least one oil passage slot formed in a region of said bottom wall extending between said pin bosses on at least one side of said piston assembly and including at least one reinforcement web extending radially of said piston assembly dividing said oil passage into at least two adjacent portion.