Piston with sealed cooling gallery and method of construction thereof
A piston for an internal combustion engine and method of construction thereof is provided. The piston has a piston body including an upper part and a lower part. The upper part has an upper combustion surface configured for direct exposure to combustion gases within a cylinder bore with an undercrown surface beneath the upper combustion surface. The body has a ring belt region configured for receipt of at least one piston ring adjacent the upper combustion surface with an annular cooling gallery configured radially inwardly from the ring belt region. The cooling gallery has a floor, wherein the floor has at least one through opening. A coolant medium is disposed in the cooling gallery, and a sealing member is disposed in the at least one through opening to seal off the coolant medium in the coolant gallery.
1. A piston for an internal combustion engine, comprising:
a piston body including an upper part and a lower part bounding an annular cooling gallery, said upper part having an upper combustion surface configured for direct exposure to combustion gases within a cylinder bore and an undercrown surface beneath said upper combustion surface and having a ring belt region radially outwardly from said annular cooling gallery, said lower part providing a floor of said annular cooling gallery and a pair of pin bosses depending from said floor, said pin bosses having axially aligned pin bores, with said floor being disposed adjacent said ring belt region between said undercrown surface and said pin bosses and extending radially inwardly from said ring belt region so that said annular cooling gallery is located only above said pin bores, and said floor having a through opening;
a coolant medium disposed in said annular cooling gallery; and
a sealing member hermetically sealing off said through opening and hermetically sealing said coolant medium in said coolant gallery.
2. The piston of claim 1 wherein said sealing member is fixed to said floor via one of a plastically expanded portion of said sealing member or a friction weld joint.
3. The piston of claim 2 wherein said sealing member is friction welded via said friction weld joint to an underside of said floor.
4. The piston of claim 3 wherein said sealing member has a conical surface friction welded to said underside of said floor.
5. The piston of claim 2 wherein said sealing member is an expanded rivet.
6. The piston of claim 1 further including a sealant material disposed about an outer periphery of said sealing member.
7. The piston of claim 1 wherein said through opening is formed on a non thrust side of said piston body.
8. The piston of claim 7 wherein said through opening is formed generally between said piston bosses.
9. The piston of claim 1 wherein said sealing member has a threaded shank threaded into said through opening.
10. The piston of claim 9 wherein said threaded shank is tapered and said through opening is tapered.
11. The piston of claim 9 further including a sealant material disposed about an outer periphery of said threaded shank.
12. A method of constructing a piston for an internal combustion engine, comprising:
forming a piston body including an upper part and a lower part, the upper part having an upper combustion surface configured for direct exposure to combustion gases within a cylinder bore and an undercrown surface beneath the upper combustion surface;
forming a ring belt region configured for receipt of at least one piston ring adjacent the upper combustion surface;
forming an annular cooling gallery radially inwardly from the ring belt region, the annular cooling gallery having a floor, the lower part including pin bosses depending from the floor, the pin bosses having axially aligned pin bores, with the floor being disposed adjacent to the ring belt region and spaced from the undercrown surface and between the undercrown surface and the pin bosses, the floor extending radially inwardly from the ring belt region so that the annular cooling gallery is located only above the pin bores;
forming a through opening in the floor of the cooling gallery;
disposing a coolant medium in the cooling gallery through the through opening; and
disposing a sealing member in the through opening to hermetically seal the coolant medium in the cooling gallery.
13. The method of claim 12 further including friction welding the sealing member to an underside of said floor of the cooling gallery.
14. The method of claim 13 further including providing the sealing member having a conically tapered surface and friction welding the conically tapered surface to the underside of the floor.
15. The method of claim 12 further including providing the sealing member as a rivet and expanding the rivet in the through opening.
16. The method of claim 12 further including providing the sealing member as a plug and pressing the plug in the through opening.
17. The method of claim 16 further including disposing a sealant material about an outer periphery of the plug prior to pressing the plug in the through opening.
18. The method of claim 12 further including forming the through opening on a non-thrust side said piston body.
19. The method of claim 12 further including providing the sealing member having a threaded shank and threading the threaded shank in the through opening.
20. The method of claim 19 further including providing the sealing member having a tapered threaded shank and forming the through opening having a matching taper to the threaded shank and threading the tapered threaded shank into the tapered through opening.
21. The method of claim 20 further including disposing a sealant material about an outer periphery of the threaded shank prior to threading the threaded shank in the through opening.
22. The piston of claim 1 wherein said floor includes an interior wall extending generally parallel to said ring belt region and presenting said through opening, said sealing member extends from a first free end disposed in said sealed coolant gallery to a second free end, a portion of said sealing member tapers toward said first free end and is spaced from said interior wall of said through opening, and said sealing member has a generally cylindrical shape engaging said interior wall of said floor and extending along said through opening between said tapered portion and said second free end.
23. The method of claim 12 wherein the floor includes an interior wall extending generally parallel to the ring belt region and presenting the through opening, the sealing member extends from a first free end disposed in the sealed coolant gallery to a second free end, a portion of the sealing member tapers toward the first free end and is spaced from the interior wall of the through opening, and the sealing member has a generally cylindrical shape engaging the interior wall of the floor and extending along the through opening between the tapered portion and the second free end.