Piston for internal combustion engine

Abstract

A piston for an internal combustion engine includes a crown part, a land part extending from the crown part, a skirt part adjoining the land part, and a linking boss protruding from a reverse surface of the crown part and forming a spherical joint with a small end of a connecting rod. The piston is divided into an upper piston part having the land part, and a lower piston part having the skirt part and a plurality of molded plate members formed by press-molding plates.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

Certain preferred embodiments of the present invention will be described in detail below, by way of example only, with reference to the accompanying drawings, in which:

FIG. 1 is a sectional view of an internal combustion engine having a piston according to a first embodiment of the present invention;

FIG. 2 is a sectional view showing the piston in conjunction with an associated connecting rod;

FIG. 3 is a perspective view of a lower piston part of the piston;

FIG. 4 is a top plan view of the lower piston part;

FIGS. 5A through 5J are views illustrating a method for manufacturing the lower piston part, wherein FIGS. 5A, 5B are top plan views of a blank, FIG. 5C is a sectional view of a deep-drawn molded material, FIG. 5D is a view showing in section and top plan the partially molded material, FIG. 5E is a sectional view of a preliminarily molded plate member, FIG. 5F is a sectional view of an upper molded plate member, FIG. 5G is a sectional view of a plate assembly, FIG. 5H is a sectional view of joining parts before welding, FIG. 5I is a sectional view of a completed lower piston part, and FIG. 5J is a sectional view of an upright lower piston part;

FIG. 6 is a sectional view showing a lower piston part according to a second embodiment of the present invention;

FIG. 7 is a sectional view showing a lower piston part according to a third embodiment of the present invention;

FIG. 8 is a sectional view showing a lower piston part according to a fourth embodiment of the present invention;

FIG. 9 is a plan view showing a lower piston part according to a fifth embodiment of the present invention; and

FIG. 10 is a sectional view showing a conventional piston for an internal combustion engine.

Claims

1. A piston for an internal combustion engine, comprising: a crown part;a land part extending in a cylindrical shape from an edge of the crown part;a skirt part adjoining the land part; anda linking boss protruding from a reverse surface of the crown part and forming a spherical joint with a small end of a connecting rod,wherein the piston is partitioned into an upper piston part having the land part, and a lower piston part having the skirt part, and the lower piston part comprises a plurality of molded plate members formed by press-molding plates.

2. The piston of claim 1, wherein a pair of the molded plate members is provided, and each of the molded plate members comprises: an outer cylinder forming the skirt part; an inner cylinder positioned inside the outer cylinder so as to be attached to a cylindrical member that constitutes the spherical joint; and a round linking plate for integrally linking both the outer cylinder and the inner cylinder, and wherein the molded plate members are brought together and the round linking plates are joined, and the lower piston part has a box structure.

3. The piston of claim 1, wherein the molded plate members are of identical shape.

4. The piston of claim 2, wherein the round linking member has a lightening hole with a burred rim.