Piston assembly and piston member thereof having a predetermined

Abstract

Present day diesel engines having aluminum piston assemblies are limited to combustion chamber pressures of approximately 12,410 kPa (1,800 psi) whereas the desire is to increase such pressures up to the 15,170 kPa (2,200 psi) range. To reach such levels the instant piston assembly includes a steel piston member having an upper cylindrical portion of a diameter 'D' and a compression height 'CH'. The ratio of the compression height 'CH' to the diameter 'D' being within the range of from 60% to 45%. The piston member is preferably forged and subsequently machined to precisely controllable dimensions. Moreover, the piston assembly is preferably of the articulated type and includes a forged aluminum piston skirt connected to the piston member through a common wrist pin. Engine manufacturers are also demanding a smaller engine package size while retaining power output, improve fuel consumption and decreased emissions. The subject piston member provides a simple and inexpensive solution to the increased power output package size relationship. To insure a small engine package, the piston member has a compression height to maximum diameter ratio within the range of from 60% to 45%. The piston member is preferably made from a steel forging to insure a reduced porosity over that of existing standard castings.