PISTON FOR AN INTERNAL COMBUSTION ENGINE

Abstract

The invention relates to a piston for an internal combustion engine having two skirt wall (10), which are connected by connecting walls (14), which bear piston-pin bosses, wherein at least one skirt wall (10) has a greater wall thickness in a region (12) that is central along the piston periphery and in the lateral regions than between the central region (12) and each lateral region and is continuously curved on the inside of the piston in a section perpendicular to the piston axis, and wherein the wall thickness distribution is substantially constant in the direction of the piston axis.

Claims

1. A piston for an internal combustion engine comprising two skirt walls which are connected by means of connecting walls having pin bosses, wherein at least one of said skirt walls has a greater wall thickness in a region that is central along a piston circumference and in the lateral regions than between the central region and the respective lateral region, and has a constant curvature on an inner side of the piston in a section perpendicular to the piston axis, and wherein the wall thickness distribution is substantially constant in the direction of the piston axis.

2. The piston according to claim 1, wherein a point of minimum wall thickness lies between 10% and 30% as well as between 70% and 90% of the width of the shaft wall in the circumferential direction.

3. The piston according to claim 2, wherein the point of minimum wall thickness has a wall thickness of 40% to 80% of the wall thickness in the central region.

4. The piston according to claim 1, wherein in the direction of the piston axis, the wall thickness as a whole increases or remains the same towards a piston crown.

5. The piston according to claim 1, wherein the inner side of the piston is convexly curved in the central region.

6. The giston according to claim 1, wherein the lateral regions are concavely curved on the inner side of the piston.

7. The piston according to claim 1, wherein the piston is made of aluminium, an aluminium alloy or steel.

8. The piston according to claim 1, wherein the piston is manufactured by casting or forging.

Description

BRIEF DESCRIPTION OF THE DRAWING

[0018] An embodiment example will be explained in more detail below by means of the drawing.

[0019] The FIGURE shows a perspective bottom view of a skirt wall of the piston according to the invention.

[0020] As is apparent from the FIGURE, the skirt wall 10 is, on the one hand, convexly curved on the outer side to rest against a cylinder bore or liner. According to the invention, the wall thickness of the skirt wall 10 is increased in a central region. In the shown embodiment, this increased wall thickness is configured in the form of a convex curvature 12 that is apparent on the inner side of the piston. The wall thickness also increases in the direction of the two lateral regions at which the skirt wall 10 is connected to the respective connecting wall 14, such that a point 16 with the lowest wall thickness occurs in the shown case approximately halfway between the central region and the lateral edge. Here, as well as at the transition to the respective connecting wall 14, the inner side of the piston is concavely curved, whereby the transition from the convex curvature in the central region has a constant curvature, i.e. is configured without jumps in the second derivative.

[0021] At the lower end of the skirt wall which can be seen in the FIGURE, i.e. the end having a maximum distance to the piston crown, the wall additionally comprises a step. In other words, in the direction of the piston axis, the outer side of the skirt wall is several millimetres longer over approximately half its wall thickness than the inner side. The cited step serves to accommodate the piston during processing.