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Steel piston with cooling gallery and method of construction thereof

  • US 9,970,384 B2
  • Filed: 05/20/2011
  • Issued: 05/15/2018
  • Est. Priority Date: 11/06/2009
  • Status: Active Grant
First Claim
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1. A piston for an internal combustion diesel engine, comprising:

  • an upper piston part;

    a lower piston part, at least said lower piston part being fabricated from a ferrous based material, said lower piston part having a pair of pin bosses formed with associated pin bores aligned along a pin bores axis which extends transversely to a central longitudinal axis along which the piston reciprocates, said lower piston part further including a pair of piston skirt portions that are formed of one piece with said pin bosses of the same material;

    said upper and lower piston parts each including an outer annular wall and an inner annular wall spaced radially apart from one another and presenting a channel portion between each of said inner and outer walls, said inner and outer walls of said upper piston part being permanently joined across inner and outer weld joints to said respective inner and outer walls of said lower piston part to define therebetween an annular cooling gallery that has two side walls provided by the joined together inner and outer walls, an annular top wall formed by the upper piston part and a bottom wall formed by the lower piston part, said bottom wall forming a floor of said annular cooling gallery, said floor undulating relative to said central longitudinal axis along a pair of diametrically opposite low portions and a pair of diametrically opposite high portions, each of said high portions extending over separate ones of said pin bosses and each of said diametrically opposite low portions extending continuously between said pair of diametrically opposite high portions;

    said joined together upper and lower piston parts including a combustion bowl defined in part by an inner surface of said joined together inner walls, and further including a generally dome-shaped bottom wall of said combustion bowl extending radially inwardly of said inner wall of said lower piston part;

    said inner weld joint being exposed to said combustion bowl;

    said joined together piston parts including a piston height dimension, PH, measured from a bottom edge of said pin bosses to a top face of said top wall;

    said joined together piston parts including a compression height dimension, CH, measured from said pin bore axis to said top face of said top wall;

    said joined together piston parts including a piston diameter, PD, measured as the outer diameter of the top wall; and

    wherein said PD equals about 103 mm, said CH equals about 40 mm and the ratio of CH/PH equals about ⅔

    .

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