Functionally Optimized Design of a Cylinder Liner

Abstract

A cylinder of an internal combustion engine, in which cylinder liner an oscillating piston is guided on a running surface wherein the cylinder line is fixed vertically by means of a collar between a cylinder housing and a cylinder head. The wet cylinder includes an outer side which deviates from a circular shape and/or a rotationally asymmetrical outer contour of the collar. The cylinder liner is fitted in a positionally oriented manner in a corresponding receptable of the cylinder housing.

Claims

1. The cylinder liner of a cylinder for an internal combustion engine in which a reciprocating piston is guided on a running surface, wherein the cylinder liner is attached vertically to a collar between a cylinder housing and a cylinder head, characterized in that an outer side and/or an outer contour of the collar of the wet cylinder liner are executed rotationally asymmetrically and the outer side and/or the outer contour is fitted aligned in a matching seat of the cylinder housing.

2. The cylinder liner of a cylinder for an internal combustion engine in which a reciprocating piston is guided on a running surface, wherein the cylinder liner is fixed vertically in a cylinder housing, characterized in that the cylinder liner includes in the axial direction at least two sections formed of different materials that are materially joined to form one unit and the cylinder liner can be used both as a wet and a dry cylinder liner.

3. The cylinder liner from claim 2, wherein the sections joined to form the cylinder liner are produced from materials having different strengths and/or different temperature resistance.

4. The cylinder liner from claim 1, wherein the outer side and/or the outer contour of the collar of the cylinder liner has an oval, elliptical, prismatic free form or a geometry deviating from a circular shape.

5. The cylinder liner from claim 1, wherein identical or divergent wall thicknesses (y.sub.1, y.sub.2) result towards a pressure side or a counter-pressure side of the cylinder liner that exceed the wall thicknesses (x.sub.1, x.sub.2) that are aligned along a longitudinal axis.

6. The cylinder liner from claims 1, wherein the collar of the cylinder liner forms identical or divergent collar widths (y.sub.3, y.sub.4) towards the pressure side or the counter-pressure side that exceed the collar widths aligned along the longitudinal axis.

7. The cylinder liner from claim 1, wherein in an area that lies below the BDC of the lowest piston ring of the piston towards a crankshaft the cylinder liner has a running surface for the piston on the inside only facing the pressure side and the counter-pressure side.

8. The cylinder liner from claims 1, wherein the cylinder liner includes partially oppositely located recesses in the direction of the longitudinal axis of the cylinder housing.

9. The cylinder liner from claim 1, wherein the outer side of the cylinder liner is coated at least locally.

10. A method for producing outer contours of a cylinder liner from claim 1, characterized in that oval turning or off-round turning can be used to create geometrically shaped topographies on the outer side of the cylinder liner.

11. The method for producing a cylinder liner that includes removal of material from local areas from claim 10, wherein the production includes: production of the cylinder liner or of the sections of the cylinder liner by a primary shaping process, specifically a forging or casting process; joining the sections using a positive material connection; finishing the outer side of the cylinder liner by off-round or oval turning; final machining of the inner running surface of the cylinder liner; and the cylinder liner of cooling lubricant, lubricants and adhering chips.

12. The method from claim 11 further comprising: coating of the outer side of the cylinder liner.

13. The cylinder liner from claim 2, wherein identical or divergent wall thicknesses (y.sub.1, y.sub.2) result towards a pressure side or a counter-pressure side of the cylinder liner that exceed the wall thicknesses (x.sub.1, x.sub.2) that are aligned along a longitudinal axis.

14. The cylinder liner from claim 2, wherein the cylinder liner includes partially oppositely located recesses in the direction of the longitudinal axis of the cylinder housing.

15. The cylinder liner from claim 2 wherein the outer side of the cylinder liner is coated at least locally.

16. A method for producing outer contours of a cylinder liner from claim 2, characterized in that oval turning or off-round turning can be used to create geometrically shaped topographies on the outer side of the cylinder liner.

Description

BRIEF DESCRIPTION OF THE DRAWING

[0019] Non-restrictive aspects of the cylinder liner and method are described in the following and explained using the Figures in which:

[0020] FIG. 1 shows a wet cylinder liner in the installed position in a sectioned view;

[0021] FIG. 2 shows a view onto a cylinder housing with two cylinder liners;

[0022] FIG. 3 shows a cylinder liner in a sectioned view;

[0023] FIG. 4 shows cylinder liners with an off-round collar in the installed position;

[0024] FIG. 5 shows the profile of the cylinder liner aligned to the counter-pressure side;

[0025] FIG. 6 shows the profile of the cylinder liner aligned to the pressure side; and

[0026] FIG. 7 shows a dry cylinder liner in a sectioned view.

DETAILED DESCRIPTION

[0027] FIGS. 1 and 2 show the design construction and installation position of a known cylinder liner 2. In addition, FIG. 1 shows a section of a cylinder housing 1, designated as a cylinder housing, of an internal combustion engine which is not shown in more detail. The wet cylinder liner 2, around which coolant flows directly and in which a reciprocating piston 3 is guided on a running surface, is inserted in the cylinder housing 1. The cylinder liner 2 is fitted in a seat 7 or in a guide 8 of the cylinder housing 1 using a collar 5 and, axially offset thereto, via an outer side 6. Seal rings 10, 11 are provided for effective sealing of the coolant chamber 9 offset to the collar 5 and in the area of the guide 8. FIG. 2 shows two cylinder liners 2 located in the cylinder housing 1 along a longitudinal axis 13 of the cylinder housing 1, the distance between centers of which S.sub.M is found by adding the dimensions, diameter D and a distance S between the cylinder liners 2.

[0028] FIG. 3 shows the functionally optimized cylinder liner 12 in cross-section with a rotationally asymmetrical outside 14 that deviates from a circular shape and can also be designated as a lateral surface. The oval shape of the outside can be executed in such a way that in all peripheral areas x.sub.1, x.sub.2, y.sub.1, y.sub.2 divergent wall thicknesses result that differ from the cylinder's inner bore, as can be seen from the following compilation: x.sub.1≠y.sub.1; x.sub.1≠x.sub.2; x.sub.1≠y.sub.2; y.sub.1≠x.sub.1; y.sub.1≠x.sub.2; y.sub.1≠y.sub.2; x.sub.2≠y.sub.2. Towards the pressure side and the counter-pressure side of the cylinder liner 12, which form an axis 18 running at a right angle to the longitudinal axis 13, wall thicknesses y.sub.1, y.sub.2 result that exceed wall thicknesses x.sub.1, x.sub.2 aligned to the longitudinal axis 13.

[0029] FIG. 4 shows two cylinder liners 12 set in the cylinder housing 1, with the oval outer sides 14 indicated by a broken line. The similarly oval collar 15 overlapping the outside 14 of the cylinder liner 12 is fitted as a press fit with an outer contour 16 into a matching seat 17 of the cylinder housing 1. The resulting collar widths Y.sub.3+Y.sub.4 of the collar 15 along the axis 18 exceed collar widths that result along the longitudinal axis 13. The oval shape of the collar 15, whose y-dimension clearly exceeds its x-dimension, makes possible in comparison with FIG. 2 a reduced spacing dimension S between two cylinder liners 12 that consequently determines the distance between centers S.sub.M of cylinder liners 12 and simultaneously influences a structural length of the cylinder housing 1.

[0030] FIGS. 5 and 6 show half a cross-section of the construction of the cylinder liner 12 that differ depending on their alignment. FIG. 5 shows the wall structure of the cylinder liner 12 aligned with the axis 18 and in FIG. 6 aligned with the longitudinal axis 13. Specifically to reduce the risk of cavitation, the wall thicknesses z.sub.1, z.sub.2 facing the pressure side and counter-pressure side (FIG. 5) exceed the wall thicknesses z.sub.3, z.sub.4 aligned to the longitudinal axis 13 (FIG. 6). As a supplement, it is appropriate for the exterior 14 of the cylinder liner 12 to have a partial coating that reduces the risk of cavitation. Starting from the collar 15, the wall thickness between zones z.sub.1, z.sub.2 in accordance with FIG. 5 and between zones z.sub.3, z.sub.4 in accordance with FIG. 6 can vary (for example, become thicker or thinner). The reduced wall thickness shown in this example in the thermally highly stressed zones z.sub.1, z.sub.2 promotes the cooling effect of the cylinder liner 12. As a measure to optimize costs and weight, the cylinder liner 12, as shown in FIG. 6, includes a recess 19 at the end facing away from the collar and an optional partially unmachined area 20 of the running surface 4 that extends from a zone corresponding to the BDC position of the bottom piston ring of the piston 3 to the end of the cylinder liner 12. Because the piston with the end of the skirt at BDC extends beyond the end of the liner, an unmachined area can only be located in the direction of the piston pin outside the piston skirt contact area so that this piston skirt contact area requires a machined, preferably honed liner surface.

[0031] FIG. 7 shows another functionally optimized cylinder liner 22 that, in the axial direction, includes two sections 23, 24 consisting of different materials which are materially joined into one unit. The sections 23, 24 supported over one joint plane 21 are preferably connected by friction welding. This design principle can be applied to both the dry cylinder liner 22 cast into the cylinder housing and to a wet cylinder liner.

[0032] Also conceivable is rotationally symmetrical centering in a corresponding rotationally symmetrical seat and a rotationally asymmetrical outer contour on the non-centering surfaces, e.g. surfaces bounded by water-jackets. The corresponding seat is necessary in the case of the asymmetrical collar, in all other cases the seat can be symmetrical. This means, as a supplement or alternative. for example, that an outer side 6 and/or an outer contour 16 of the collar 15 of the wet cylinder liner 12 is/are rotationally symmetrical and inserted aligned.

[0033] A further aspect can be seen in an aligned centering of the outside 6 and/or the outer contour 16 in a corresponding seat 7, 17 of the cylinder housing.