US 5,076,225 AGranted

Piston for an internal combustion engine

AssigneeToyota Jidosha Kabushiki Kaisha

InventorsNoriyuki Tokoro, Roichi Shimura, Youichi Sugiura

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Abstract

A piston 2 for an internal combustion engine includes side wall portions 12 connecting skirt portions 10 to pin boss portions 6 so as to support the skirt portions 10 in a direction perpendicular to an axis 8 of the pin boss portions. The skirt supporting stiffness of each side wall portion 12 is gradually changed in an axial direction of the piston 2 so as to have a maximum stiffness at a lower end portion of the side wall portions b 12 and to decrease in the direction upwardly away from the lower end portion of the side wall portion 12. Due to this structure, the skirt portion 10 is unlikely to be deformed at its lower end portion so that a clearance between the skirt portion 10 and a cylinder bore surface 20 is maintained small. Further, the skirt portion 10 has a soft structure at the shoulder of the skirt portion 10 so that a shock at the shoulder will be decreased to prevent breakage of an oil membrane from happening at the upper portion of the skirt portion 10.

Claims9

Dependent claims

A piston for an internal combustion engine comprising:

a cylindrical top portion having an axis that defines an axis of the piston;
two pin boss portions located below the top portion on opposite sides of the axis of the piston and integrally connected to the top portion, the pin boss portions having an axis extending perpendicular to the axis of the piston;
two skirt portions located below the top portion on opposite sides of the axis of the pin boss portions and connected to the top portion;
and
side wall portions located below the top portion between the pin boss portions and the skirt portions and connecting the pin boss portions and the skirt portions so as to support the skirt portions from the pin boss portions in directions perpendicular to the axis of the pin boss portions, skirt supporting stiffness of each side wall portion being gradually changed in an axial direction of the piston as a result of the axially changing shape of the cross section of the piston, so as to have a maximum stiffness at lower portions of the side wall portions and to decrease in a direction upwardly away from the lower portions of the side wall portions.

2 more elements

Dependencies are inferred from the claim text.