Wrist pin for a two-piece piston
AssigneeMetal Leve S.A. Industria e Comercio
InventorsJose Do Ribeiro, Luis M. Lopes, Jose M. Leites
Life of this patent
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Abstract
Wrist pin for a two-piece piston, having a cylindrical external surface (41) and an internal surface with an internal diameter, throughout the length of the pin (40). The end portions of the pin have a reduced internal wall thickness between the outer half of the supporting face of the bosses (50), where there exclusively occur bending moment and shearing force applied by the inertia of the skirt (20) and of the moving assembly (100). The reduction in the internal wall thickness is obtained by the increase in the internal diameter of the pin (40) at the end portions, through two different end revolution surfaces (43, 44) each having respective a generatrix which is at least substantially straight.
Claims13
A two-piece piston having a head portion with at least one hollow pin boss, a skirt portion with holes, a connecting rod, and a tubular wrist pin inserted through said at least one boss of the piston head portion, said holes of the skirt portion for being supported on a wall surrounding the holes of said skirt portion, and said connecting rod, wherein said wrist pin resists shearing forces applied to said wrist pin during piston operation by said at least one pin boss of the piston head portion, wherein an internal surface of the tubular wrist pin having a surface of revolution defined by:
- a median section having a constant internal diameter throughout the length thereof;
- and
- end portions disposed at each end of said median section and terminating at respective free ends of said wrist pin, each of said end portions being defined by an end section extending from said free end and a transition section between said end section and said median section, said end section being defined by a tapered portion having an angle of inclination with respect to an axis transverse to a longitudinal axis of said wrist pin, and said transition section being defined by a tapered portion having an angle of inclination with respect to said transverse axis which is less than the angle of inclination of said end section.
A wrist pin for a two-piece piston to be inserted through at least one boss of a piston head portion, holes in a piston skirt portion for being supported on a wall surrounding said skirt portion holes, and a connecting rod, said wrist pin being adapted to resist shearing forces applied to said wrist pin during piston operation by said at least one pin boss of said piston head portion, wherein said wrist pin being tubular and having an internal surface of revolution defined by:
- a median section having a constant internal diameter throughout the length thereof;
- and
- end portions disposed at each end of said median section and terminating at respective free ends of said wrist pin, each of said end portions being defined by an end section extending from said free end and a transition section between said end section and said median section, said end section being defined by a tapered portion having an angle of inclination with respect to an axis transverse to a longitudinal axis of said wrist pin, and said transition section being defined by a tapered portion having an angle of inclination with respect to said transverse axis which is less than the angle of inclination of said end section.
Dependencies are inferred from the claim text.