Piston For An Internal Combustion Engine and Production Method Therefore

Abstract

A piston of an internal combustion engine having a piston head which has a ring zone and is adjoined by a piston skirt which encloses an inner shape, with two box walls which lie opposite one another and are set back with respect to the outer contour of the piston and with two skirt walls which are not set back with respect to the outer contour of the piston, wherein the box walls receive hubs, wherein the piston skirt has skirt supports which are connected to the hub, wherein the width of the box wall is a point of intersection between the pin axis and the constant-curvature and constant-tangent further course of the box wall, and to a method for producing a piston for internal combustion engines.

Claims

1-9. (canceled)

10. A piston of an internal combustion engine having a piston head which has a ring zone and is adjoined by a piston skirt which encloses an internal shape, with two box walls which lie opposite one another and are set back with respect to the outer contour of the piston and with two skirt walls which are not set back with respect to the outer contour of the piston, the box walls receiving bosses, the piston skirt having skirt supports which are connected to the boss, characterized in that the width (b) of the box wall is a point of intersection between a pin axis and a continuation with a constant curvature and tangent of the box wall; wherein the direction of the skirt support is described by points of intersection (a2i, a3i, a2a, a3a), the points (a2i, a2a) being points of intersection between the continuation with the constant curvature and tangent of the box wall and the outer boss radius (r) which is situated at the level of the pin axis, and the points (a3i, a3a) being the points of intersection between the continuation with the constant curvature and tangent of the box wall and the continuation with a constant tangent of an internal shape; wherein the following geometric properties apply to the piston: a2i/a3i=from 1.05 to 1.5 and a2a/a3a=from 1.05 to 1.5.

11. The piston of claim 10 characterized in that the skirt support has a concave shape, in relation to the plane which lies through a piston stroke axis and perpendicularly with respect to the pin axis.

12. The piston of claim 10, characterized in that the skirt support is to be of identical configuration for a pressure side and a counterpressure side or is varied for the respective side of the piston in the geometric properties ratios a2i/a3i and a2a/a3a.

13. The piston of claim 12 characterized in that the width (b) of the box wall (4) is defined as follows:
b=((a1+A))/215% d.sub.k.

14. The piston of claim 10 characterized in that the width (b) of the box wall is defined as follows:
b=((a1+A))/215% d.sub.k.

15. A method for producing a piston according to claim 10, wherein the piston is produced using a casting or a forging process.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0023] The invention will be clarified further using the FIGURE which is described in the following text and in which:

[0024] FIG. 1 shows a cross section through an example piston 1 having a piston skirt 2 with a skirt support 3.

DETAILED DESCRIPTION OF THE EMBODIMENTS

[0025] In the piston 1, two walls of the piston skirt 2 which lie opposite one another are provided such that they are set back with respect to the outer contour of the piston 1. The walls which are set back are called box walls 4; the two other walls which are not set back are called skirt walls 13 and have the actual running surface of the piston skirt 2. Bosses 6 with pin bores are integrated into the box walls 4. The box walls 4 and the skirt walls 13 are connected to the underside of a piston head 11.

[0026] The box wall 4 has a width b, a diameter d and a wall thickness s. Furthermore, the piston 1 has a box wall arc 5. In addition, the bosses 6 are penetrated by a pin axis 7. The skirt support 3 has a concave shape in relation to the plane which lies through a piston stroke axis 8 and perpendicularly with respect to the pin axis 7. r denotes the outer boss radius. A describes the axial spacing in the pin direction of the securing ring groove 9, and a1 describes the axial spacing of the start of the load-bearing length in the direction of the pin axis 7.

[0027] The points a2a and a2i form points of intersection between the continuation with a constant curvature and tangent of the box wall 4 and the outer boss radius r which is situated at the level of the pin axis 7. The points a3a and a3i form points of intersection between the continuation with a constant curvature and tangent of the box wall 4 and the tangential continuation of the internal shape 10. The internal shape 10 forms part of the underside of the piston head 11. A circumferential ring zone 12 is arranged on the outer circumference of the piston head 11. The ring zone 12 is given support, in particular, by way of the skirt walls 13.

[0028] The piston 1 has the following features. The width b of the box wall 4 is the point of intersection between the pin axis 7 and the continuation with a constant curvature and tangent of the box wall 4, and is defined as follows:

b.sub.box.sub._.sub.wall=((a1+A))/215%d.sub.k,

[0029] wherein d.sub.k describes the piston diameter, A describes the axial spacing in the pin direction of the securing ring groove 9, and a1 describes the axial spacing of the start of the load-bearing length in the direction of the pin axis 7.

[0030] The width b of the box wall 4 is equal to the point of intersection of the box wall arc 5 and the pin axis 7.

[0031] The direction of the skirt support 3 is described by the points a2i, a3i, a2a and a3a, the points a2i and a2a being the points of intersection between the continuation with a constant curvature and tangent of the box wall 4 and the outer boss radius r which is situated at the level of the pin axis 7, and the points a3i and a3a being the points of intersection between the continuation with a constant curvature and tangent of the box wall 4 and the continuation with a constant tangent of an internal shape 10.

[0032] The following geometric properties apply:

a2i/a3i=1.05 . . . 1.5, and
a2a/a3a=1.05 . . . 1.5.

[0033] A minimum radius of R.sub.min0.9 d.sub.k applies here.

[0034] All radius combinations (splines, changing radii, combinations of straight lines and radii) in the abovementioned range are included in the present invention.

[0035] The skirt support 3 is to be of identical configuration for the pressure side and counterpressure side or can be varied for the respective piston side in the ratios a2i/a3i and a2a/a3a.

LIST OF DESIGNATIONS

[0036] 1 Piston [0037] 2 Piston skirt [0038] 3 Skirt support [0039] 4 Box wall [0040] 5 Box wall arc [0041] 6 Boss [0042] 7 Pin axis [0043] 8 Piston stroke axis [0044] 9 Securing groove [0045] 10 Internal shape [0046] 11 Piston head [0047] 12 Ring zone [0048] 13 Skirt wall [0049] A Axial spacing of the securing ring groove in the pin axis direction [0050] a1 Axial spacing of the start of the load-bearing length in the pin axis direction [0051] a2a Point of intersection between the continuation with a constant curvature and tangent of the box wall and the outer boss radius which is situated at the pin axis level [0052] a2i Point of intersection between the continuation with a constant curvature and tangent of the box wall and the outer boss radius which is situated at the pin axis level [0053] a3a Point of intersection between the continuation with a constant curvature and tangent of the box wall and the tangential continuation of the internal shape [0054] a3i Point of intersection between the continuation with a constant curvature and tangent of the box wall and the tangential continuation of the internal shape [0055] b Width of the box wall [0056] d Diameter of the box wall [0057] d.sub.k Piston diameter [0058] r Outer boss radius [0059] s Wall thickness [0060] R.sub.min Radius