Patent ID: 6112715
Filing Date: 2000-09-05
Classification: F02B,F02F,F05C,F16J,Y02T

Abstract:
A piston for an internal combustion engine, for high speed Diesel engines used in passenger or light load cars, comprising in a single piece: a head portion (10), which has a diameter (D) of about 70 to about 100 mm and which is provided with an upper median recess defining a combustion chamber (11) having a bottom wall (12) with a thickness (E) and a plurality of peripheral grooves (13) for mounting piston rings; a skirt portion (20) extending downwardly from the lowermost peripheral grooves (13) by a first skirt axial extension (21) and a second skirt axial extension (22) diametrically opposite to the first one; and a pair of wrist pin bosses (30) connected to the bottom wall (12) of the combustion chamber (11) and to the first and second skirt axial extensions (21, 22) by respective lateral walls (23) which are radially back spaced, each wrist pin boss (30) having a hole (31) for bearing the wrist pin of the piston, characterized in that the single piece is made from an alloy with a density which is lower than about 3 g/cm.sup.3 and with a yield stress which is higher than about 120 Mpa at temperatures of about 300.degree. C. and having: a height (H) of 4-8 mm for the burning zone defined between the piston upper face and the uppermost peripheral groove (13); a thickness (E) for the bottom wall (12) of the combustion chamber (11) corresponding to 5-9% of the piston diameter (D); and a projected bearing area which is the projection of the upper half of hole (31) onto an upper transversal plane (PS) of the piston, by which the piston is supported on the wrist pin equal to twice the product of the diameter (d) of the hole (31) by its axial extension (L) and corresponding to 7-14% of the square of the piston diameter (D).