Cast piston having reinforced combustion bowl edge
First Claim
Patent Images
1. A gravity cast piston which comprises:
- a piston head having a crown surface;
a piston skirt extending downwardly from said piston head;
a combustion bowl formed in said piston head, said combustion bowl having a side wall and extending downwardly from said crown surface; and
a metal insert provided in said piston head at the crown and defining an upper portion of said combustion bowl, said insert having an annular ring structure with a smooth outer wall and a flange which extends outwardly from a lower portion of the annular ring structure, said flange including a row of scallop-shaped protrusions along an outer peripheral edge thereof, said metal insert providing an undercut structure in said side wall.
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Abstract
A cast piston which includes a metal insert and a combustion bowl, with the metal insert defining a sharp undercut structure at an upper portion of the combustion bowl. The sharp undercut structure of the insert contains combustible gases and helps improve emissions. The metal insert also strengthens the head of the piston. The cast piston is fabricated by positioning the metal insert in a casting mold and casting a piston in the mold. The final shape of the combustion bowl is produced by a machining process which forms the sharp undercut structure on the insert.
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Citations
23 Claims
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1. A gravity cast piston which comprises:
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a piston head having a crown surface; a piston skirt extending downwardly from said piston head; a combustion bowl formed in said piston head, said combustion bowl having a side wall and extending downwardly from said crown surface; and a metal insert provided in said piston head at the crown and defining an upper portion of said combustion bowl, said insert having an annular ring structure with a smooth outer wall and a flange which extends outwardly from a lower portion of the annular ring structure, said flange including a row of scallop-shaped protrusions along an outer peripheral edge thereof, said metal insert providing an undercut structure in said side wall. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A method of fabricating a gravity cast piston which comprises:
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providing a piston mold; positioning a metal insert in said piston mold; gravity casting a piston in said piston mold so that said insert is positioned at a crown surface of said cast piston; and machining a combustion bowl in a head of said cast piston so that said metal insert defines an upper portion of said combustion bowl and provides an undercut structure in a side wall of said combustion bowl. - View Dependent Claims (11, 12, 13, 14, 15, 16, 17, 18, 19)
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20. A metal insert for gravity cast pistons which comprises:
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a ring structure having a smooth outer wall; and a flange provided at a lower portion of said ring structure and extending outwardly therefrom, said flange including a row of scallop-shaped protrusions along an outer peripheral edge thereof. - View Dependent Claims (21, 22, 23)
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Specification