Light metal piston for internal combustion engines and method of making the same
AssigneeIzumi Automotive Industry Co., Ltd.
InventorsMasaaki Kudou, Tosio Ogiwara
Life of this patent
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Abstract
A light metal piston for internal combustion engines has a pair of inserts on the inside of upper piston skirt made of a material of lower thermal expansion coefficient than that of the light metal, such as steel. Each insert has a pair of bands which are joined by a connecting portion of the insert in the region of the gudgeon pin boss. Each band extends circumferentially away from the gudgeon pin boss, so as to control thermal expansion of the piston skirt. A free end of each band are bent inwardly, so that the insert can be set firmly on the mold core of the piston during casting operation by snapping the bent portions of the insert into the grooves on the mold core.
Claims19
A light metal piston for internal combustion engines, having a crown, a skirt integrally connected to said crown, a pair of gudgeon pin bosses, and a pair of expansion control inserts made of a material of lower thermal expansion coefficient than that of the light metal, each insert conforming to the internal shape of the piston skirt, each said insert having:
- a connecting portion embedded in a gudgeon pin boss;
- a pair of bands, being joined by said connecting portion, and each extending from said connecting portion and conforming to said internal shape of said skirt to form a bimetallic element therewith;
- each band having a free end, and
- a pair of bent portions, one at the free end of each band, each free end being bent inwardly so that said free ends fit into grooves in a moldcore and form means for fastening said bands to a moldcore during a casting operation.
A light metal piston comprising:
- a cast metal element having a cylindrical body with an inner wall and also having the following parts all of which are integral with said body and with each other:
- a crown, a skirt and two gudgeon pin bosses,
- first and second means for controlling thermal expansion of said body when it is heated,
- each said means comprising a pair of bands and a connecting portion for interconnecting said bands, said connecting portion and its two bands constituting a unitary element,
- the connecting portion of one of said means being associated with and complementary to one of said bosses, and the connecting portion of the other of said means being associated with and complementary to the other of said bosses,
- each said connecting portion being substantially entirely embedded within, and extending about half way around, its complementary boss,
- the two bands associated with each connecting element extending, in opposite directions respectively, away from the boss in which the connecting element for the bands is embedded, and along said inner wall,
- each said band terminating in an end portion at least a part of which is at an angle to an adjacent portion of the band, and in which said part of each of said end portions turn inwardly of the piston and away from said inner wall.
In a piston:
- a cylindrical body with an inner wall and composed of molded metal having a crown and first and second bosses, and
- means for controlling thermal expansion of said body comprising first and second inserts associated with said first and second bosses respectively,
- each insert comprising two bands extending along said inner wall in opposite directions respectively from the boss with which the insert is associated, and each insert also including a connecting member interconnecting the two bands of the insert,
- each connecting member being embedded in-situ in the boss with which the insert is associated,
- each insert having free end portions that comprise resilient holding means for holding the insert onto a mold core so that the insert may be properly positioned during the molding of said body.
Dependencies are inferred from the claim text.