Method for producing a piston for an internal combustion engine, piston for an internal combustion engine, piston blank for producing the piston, and casting mold or forging die for producing a piston blank

Abstract

A method for producing a piston blank or a piston for an internal combustion engine, includes providing a thickened portion formed in at least one box wall in the direction of thickness approximately in the center thereof, which is at least partly flush with a cooling channel. A resulting piston blank or piston having these features can be made in a casting mold or forging die designed in a corresponding manner.

Claims

1. A method for producing a piston for an internal combustion engine, in which, as part of the production of a piston blank by forging, a thickened portion is formed by forging in at least one box wall in the direction of thickness in the center thereof, which is at least partly flush with a cooling channel; said at least one box wall is formed on the outside of a piston pin boss, the pin boss having a planar outer face, and said at least one box wall bulges outward beyond said planar face to form said thickened portion.

2. The method according to claim 1, wherein the piston blank is made from iron or steel.

3. The method according to claim 1, wherein the thickened portion is mechanically reworked such that at least one coolant inlet or outlet bore is formed at least partially in a funnel shape.

4. The method according to claim 1, wherein the cooling channel is filled with a fluid.

5. A piston for an internal combustion engine having at least one box wall in which a thickened portion is formed by forging in the direction of thickness in the center, which is not mechanically reworked with the exception of a bore formed therein, with at least one box wall being formed on the outside of a pin boss, the pin boss having a planar outer face, and said at least one box wall bulging outward beyond said planar face to form said thickened portion.

6. The piston according to claim 5, wherein a said bore is formed in at least one thickened portion, which is formed at least partially in a funnel shape.

7. A piston for an internal combustion engine, comprising: a piston body having a pair of pin bosses each having a planar outer face and each received between two box walls extending laterally of the pin bosses to opposite sides thereof; an annular cooling channel disposed above the pin bosses; at least one of said box walls having a locally thickened region extending in a longitudinal direction of the piston; said at least one of said box walls bulging inward of the box wall and bulging outward of the planar face of the associated pin to form said locally thickened region; and wherein said locally thickened section is provided between one of the pin bosses and a load-bearing shaft wall of said piston body, said locally thickened section includes a bore open at a bottom of the at least one thickened portion and communicating at an open end of the bore with said cooling channel.

8. The piston of claim 7, wherein a lower end of the bore is flared.

9. The piston of claim 7, wherein the bore enables the supply of cooling oil from a cooling nozzle into the cooling channel.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) A preferred embodiment example of the invention is described in more detail below with reference to the figures.

(2) FIG. 1 shows a bottom view of a piston blank according to the invention, and

(3) FIG. 2 shows a sectional view through a piston according to the invention.

DETAILED DESCRIPTION

(4) As FIG. 1 shows, a piston blank 10 according to an embodiment of the invention has two load-bearing shaft wall portions 18 and two box walls 12 which receive the piston pin bosses 16. As can further be seen in the figure, a thickened portion 14 is formed at two diametrically opposed points in the box wall, which lies approximately in the center of the box wall to the extent that the box wall would, in an imagined continued path, proceed approximately centrally through the thickened portion 14. In other words, the box wall is “bulged” in both directions, to the inside and to the outside, in order to form the thickened portion described. In other words, the respective thickened portion is preferably formed substantially symmetrically with respect to the box wall 12 as an axis of symmetry.

(5) As can be seen in FIG. 2, a bore 32 can be created in a direction approximately parallel to the piston axis (in FIG. 1 perpendicular to the reference plane, in FIG. 2 from top to bottom), said bore, as shown in FIG. 2, enabling the supply of cooling oil 34 from a cooling nozzle 36 into a cooling channel 38. In order to increase the retention rate in this connection, the bore 32 is widened in a funnel shape at its end opposite the cooling channel 38.

(6) FIG. 1 also reveals that in the case shown the box walls 12 are formed on the outside on the piston pin bosses 16. However, the piston pin bosses 16 can protrude or spring back relative to the box walls 12.