Cylinder liner for internal combustion engine

Abstract

The present invention relates to a cylinder liner (1) for an internal combustion engine, comprising: a hollow cylindrical liner body (2) extending along an axial direction (A), the inner circumferential side (3) of which along the axial direction (A) comprises at least a first and a second axial portion (4a, 4b). The inner circumferential side (3) is cylindrically formed in the first axial portion (4a) or opens towards the second axial portion (4b) at a first opening angle (α1). The second axial portion (4b) opens away from the first axial portion (4a) at a second opening angle (α2) greater than the first opening angle (α1) that may exist in the first axial portion (4a). The first surface roughness (OR1) of the inner circumferential side (3) in the first axial portion (4a) is greater than the second surface roughness (OR2) in the second axial portion (4b). The plateau appearance (PA2) R3p = Rvk / (Rpk + Rk) of the inner circumferential side (3) in the second axial portion (4b) is from 0.2 to 1.6, and its texture height (SH2) R3k = Rpk + Rk + Rvk is at most 0.4 μm.

Description

Field of the Invention

[0001] The present invention relates to a cylinder liner for an internal combustion engine and an internal combustion engine having such a cylinder liner. The present invention also relates to a motor vehicle having such an internal combustion engine. Background Art

[0002] Cylinder liners are known from the prior art that flare away from the combustion space to compensate for thermal expansion occurring mainly above the combustion space. Such cylinder liners are disclosed, for example, by DE 1 576 404 A1 and DE 10 2013 013943 B3.

[0003] Cylinder liners are also known from the prior art in which the surface roughness of the inner circumferential side of the liner varies. In this context, DE 11 2014 003421 T5 proposes to provide surfaces with a high roughness both in the region of the top and at the bottom turning points of the piston sliding along the cylinder liner. At the two turning points, high pressures can develop due to the pressure present at these locations and a possible "tilt" of the piston. The deep roughness texture of the surface thus serves to store oil that allows for effective lubrication of the piston in this region. In the region between the two turning points where the piston can move quickly, the sliding friction occurring between the piston or its piston rings and the inner circumferential side of the cylinder liner can be kept low by providing a surface with a low roughness, i.e., by providing a smooth (smoother) surface.

[0004] DE10 2014 017 361 A1 combines the above idea with the idea of widening the cylinder liner in the middle region, where the additional clearance resulting in the middle region also reduces the sliding friction occurring between the piston and the cylinder liner or its piston rings. Summary of the Invention

[0005] It is an object of the present invention to show a new way of developing a cylinder liner for an internal combustion engine.

[0006] This object is achieved by the subject matter of the independent claims. Preferred embodiments are the subject matter of the dependent claims.

[0007] Accordingly, the basic idea is that, along the axial direction of the cylinder liner, both the liner diameter and the surface roughness defining the liner diameter on the inner circumferential side of the cylinder liner vary. Here, what is important for the present invention is that a first axial portion of the cylinder liner is provided with a greater surface roughness than a second axial portion that is further away from the top reversal point, and this first axial portion is assigned to the top reversal point of the piston when used in an internal combustion engine, that is, facing the combustion space. According to the present invention, the increase in the liner diameter in the first axial portion of the cylinder liner is selected to be smaller in the axial direction from the first to the second axial portion than in the second axial portion. This ensures that in the first axial portion of the cylinder liner facing the combustion space, the piston is guided with low radial clearance and good lubrication, even under high gas pressure. In the second axial portion that is further away from the combustion space, the sliding friction between the piston and the cylinder liner is kept very low due to the resulting greater radial clearance and reduced surface roughness. Here, for the present invention, it has been confirmed to be important that the overall texture height of the surface and the plateau aspect are small in the second axial portion.

[0008] These features are illustrated based on the characteristic variables Rk, Rvk, and Rpk as defined in standard DIN EN ISO 13565-2. Accordingly, Rk is the depth of the roughness core profile, which is also referred to by those skilled in the art as the name "core peak to valley height". In addition, Rpk is the average height of the peaks protruding from the core region, which is also well-known to those skilled in the art as the term "reduced peak height". Finally, Rvk is the average depth of the valleys protruding from the core region, which is known to those skilled in the art as the term "reduced valley depth". Rpk describes the running-in performance of the peak region and thus the surface of the inner circumferential side. Rk describes the core region as the load-bearing part of the profile. Rvk describes the valley and hole regions and thus affects the oil retention volume and long-term performance.

[0009] The above-mentioned texture height on the inner circumferential side in the second axial portion is defined as R3k = Rpk + Rk + Rvk.

[0010] The above-mentioned plateau aspect on the inner circumferential side in the second axial portion is defined as R3p = Rvk / (Rpk + Rk).

[0011] R3p, that is, the plateau aspect, describes the characteristics of the contact and core regions related to the surface valleys. R3k, that is, the texture height SH2, describes the overall roughness of the honing texture without extreme peak and valley regions.

[0012] The plateau appearance on the inner circumferential side in the second axial part according to the invention is from 0.2 to 1.6, preferably from 0.6 to 1.6, and most preferably from 0.6 to 0.8. The texture height on the inner circumferential side in the second axial part according to the invention is at most 0.4 μm. Experimental investigations have shown that, thereby, a surface with the characteristics of a finely ground extended surface can be created. Thereby, a particularly thin oil film can be achieved in the second axial part such that a piston moving at a relatively high speed in the second axial part only needs to push a relatively small amount of oil in front of it. This results in a favourably reduced frictional effect.

[0013] Consequently, a cylinder liner is created in which an internal combustion engine piston can be guided in a mechanically precise manner with particularly low sliding friction.

[0014] The cylinder liner for an internal combustion engine according to the invention comprises a hollow cylindrical liner body extending along the axis. Its inner circumferential side comprises along the axis at least one first axial part and at least one second axial part. Preferably, the inner circumferential side in a longitudinal section along the axis is cylindrically formed in the first part, or opens in the first axial part at a first opening angle towards the second axial part, i.e. preferably conically. This means that the liner diameter of the liner body determined by the inner circumferential side has a constant value along the axis in the first axial part, or this value increases along the axis. In the latter case, the first axial part thus tapers away from the second axial part.

[0015] Furthermore, the second axial part opens at a second opening angle away from the first axial part - i.e. preferably opens conically, where the second opening angle is greater than (if applicable) the first opening angle similarly present in the first axial part. This means that the value of the liner diameter of the liner body determined by the inner circumferential side in the second axial part along the axis, i.e. away from the combustion space of the internal combustion engine towards the crankshaft, increases. Here, the value of the liner diameter increases more in the second axial part than in the first axial part. The typical value range for the opening angle in the first axial part is from 0 to 5 angular minutes. The typical value range for the opening value in the second axial part is from 4 to 25 angular minutes.

[0016] According to the invention, the first surface roughness of the inner circumferential side in the first axial part is greater than the second surface roughness of the inner circumferential side in the second axial part. According to the invention, the plateau appearance on the inner circumferential side in the second axial part as defined above is from 0.2 to 1.6, preferably from 0.6 to 1.6, and most preferably from 0.6 to 0.8. The texture height on the inner circumferential side in the second axial part as defined above is defined as R3k = Rpk + Rk + Rvk, and according to the invention is at most 0.4 μm, preferably at most 0.2 μm.

[0017] By determining the texture height and platform appearance according to the present invention, since the ring packing in the main hydrodynamic region uses a small oil retention volume and pushes a significantly reduced amount of oil in front of it, the friction developed between the piston and the cylinder liner can be reduced. According to a preferred embodiment, the first surface roughness of the inner circumferential side in the first axial part is RpK < 0.15 μm, where Rk < 0.5 μm and Rvk is 0.2 μm to 1.5 μm.

[0018] According to another preferred embodiment, the second surface roughness of the inner circumferential side in the second axial part is Rpk < 0.05 μm, where Rk < 0.15 μm, and Rvk < 0.2 μm.

[0019] According to a further advantageous development, the bushing body may include a third axial part in which the inner circumferential side is formed cylindrically or flares away from the second axial part at a third flare angle, preferably flaring conically. This means that the bushing diameter determined by the inner circumferential side of the bushing body either remains the same axially or further increases axially in the third axial part. In this further development, the second axial part is thus axially disposed between the first and third axial parts. In this further development, due to the additional radial clearance present in the third part, the sliding friction occurring between the cylinder liner and the piston guided in the cylinder liner is further reduced.

[0020] Particularly preferably, the third surface roughness of the inner circumferential side in the third axial part is less than the first surface roughness of the first axial part. This scale is also accompanied by improved friction characteristics, especially a reduced friction value of the cylinder liner.

[0021] According to a further advantageous further development, the radial widening of the cylinder liner measured perpendicular to the axial direction - based on the central longitudinal axis of the cylinder liner - can be up to 100 μm, preferably approximately 50 μm. These values are preferred for cylinder liners with a typical inner diameter range of 120 to 140 mm for heavy vehicles. Regardless of the diameter of the cylinder liner involved, a measured widening radially extending from the central longitudinal axis in the range of 0.025% to 0.05% of the cylinder liner diameter is considered particularly advantageous. The accompanying increasing radial clearance axially particularly advantageously reduces the sliding friction occurring between the piston and the cylinder liner.

[0022] In practice, in the first axial part and alternatively or additionally in the second axial part, the generatrix on the inner circumferential side can travel along a curved path in the longitudinal section along the axis. Alternatively or additionally, in the first axial part and alternatively or additionally in the second axial part, the generatrix on the inner circumferential side can travel along a straight line. Although a straight generatrix can define a conical or cylindrical space, a curved generatrix can produce a widening that progresses in the direction of the crankshaft from the combustion space - especially a horn or bell shape. Thus, it is feasible to finely adapt the profile of the inner circumferential side of the bushing body to the specific requirements of the user.

[0023] According to an advantageous further development, in the case where the bushing body further includes the above-mentioned third axial part, the inner circumferential side in the longitudinal section along the axis can travel along a curved path in the third axial part. However, alternatively to this solution, it is also conceivable that, in the longitudinal section along the axis, the inner circumferential side travels along a straight line in the third axial part. Thus, it is also feasible to finely adapt the profile of the inner circumferential side of the bushing body to the specific requirements of the user.

[0024] In a further preferred variant, it is conceivable that one or more (first) sub-parts of the first, second, and / or third axial parts 4a, 4b, 4c are formed in a straight line, and one or more (second) sub-parts of the first, second, and / or third axial parts 4a, 4b, 4c are designed to be curved.

[0025] In a further preferred embodiment, the second axial part directly follows the first axial part along the axis. This embodiment requires particularly little installation space axially.

[0026] In a further preferred embodiment, the third axial part directly follows the second axial part along the axis. This embodiment also requires particularly little installation space axially.

[0027] The invention also relates to an internal combustion engine for a motor vehicle, which has at least one cylinder bore defined on the circumferential side by the above-mentioned cylinder liner according to the invention. The advantages of the above-mentioned cylinder liner thus also apply to the internal combustion engine according to the invention. A piston of the internal combustion engine is arranged in the cylinder bore - which is adjustable along the axis of the cylinder liner between a top dead center and a bottom dead center. Obviously, the internal combustion engine can also include two or more cylinder bores, each having a cylinder liner according to the invention and a piston as described above. According to the invention, the top dead center is arranged in the first axial part of the cylinder liner.

[0028] According to a preferred embodiment, where the cylinder liner is specifically formed without a third axial part, the bottom dead center is arranged in the second axial part of the cylinder liner.

[0029] According to an alternative preferred embodiment, the bottom return point of the piston may be exactly arranged in the third axial part of the cylinder liner, where the cylinder liner includes the above-mentioned third axial part.

[0030] Finally, the invention relates to a motor vehicle having an internal combustion engine according to the invention and thus having at least one cylinder liner according to the invention. The advantages of the above-mentioned internal combustion engine according to the invention or the cylinder liner according to the invention thus also apply to the internal combustion engine according to the invention.

[0031] Other important features and advantages of the invention are obtained from the dependent claims, the drawings and the associated description of the drawings by means of the drawings.

[0032] It is to be understood that the features described above and to be explained below can be used not only in the respective combinations mentioned, but also, without going beyond the scope of the invention, in other combinations or individually.

[0033] Preferred exemplary embodiments of the invention are shown in the drawings and are explained in more detail in the following description, wherein the same reference numerals refer to the same or similar or functionally identical components. Description of the Drawings

[0034] Each schematically shows:

[0035] Figure 1 A first example of a cylinder liner according to the invention, wherein the first axial part on the inner circumferential side is formed cylindrically, i.e., without an opening angle.

[0036] Figure 2 A second example of a cylinder liner according to the invention, wherein the first axial part on the inner circumferential side tapers towards the second axial part. Detailed Description of the Invention

[0037] Figure 1 A first example of a cylinder liner 1 for an internal combustion engine (not shown) of a motor vehicle according to the invention is shown in a longitudinal section along the axial direction A. The cylinder liner 1 includes a hollow cylindrical liner body 2 extending along the axial direction A, and its inner circumferential side 3 includes a first axial part 4a, a second axial part 4b, and a third axial part 4c along the axial direction A. The second axial part 4b is arranged between the first axial part 4a and the third axial part 4c along the axial direction A.

[0038] The axial direction A extends along the central longitudinal axis M of the liner body 2, and the radial direction is perpendicular to the axial direction A and extends away from the central longitudinal axis M. The circumferential direction U extending perpendicular to both the axial direction A and the radial direction R surrounds the central longitudinal axis M. In a simplified variant (not shown) of the example, the third axial part 4c can be omitted.

[0039] Feasible materials for the bushing body 2 are, for example, aluminum, steel, or cast iron.

[0040] In Figure 1 the example of, as shown, the inner circumferential side 3 is cylindrically formed in the first axial part 4a - that is, without flaring, without narrowing, and thus the flaring angle is zero. Thus, the inner circumferential side 3 extends along the axial direction A and parallel to the central longitudinal axis M in the first axial part 4a. This means that the bushing diameter d determined by the generatrix of the inner circumferential side 3 of the bushing body 2 has a constant value d1 along the axial direction A in the first axial part 4a.

[0041] Figure 2 An alternative scenario of this embodiment is shown. Accordingly, the first axial part 4a can flare towards the second axial part at a first flaring angle α1, preferably in a conical shape, that is, narrow away from the second axial part 4b, preferably in a conical shape. In the longitudinal section shown along the axial direction A, the flaring angle α1 corresponds to the intermediate angle between the first axial part 4a of the inner circumferential side 3 and the central longitudinal axis M of the bushing body 2. This means that along the axial direction A, in the first axial part 4a, the value d1' of the bushing diameter d of the bushing body 2 determined by the generatrix of the inner circumferential side 3 increases along the axial direction A.

[0042] In Figure 1 the example of and in Figure 2 both examples of, the second axial part 4b flares away from the first axial part at a second flaring angle α2, that is, preferably in a conical shape. In the longitudinal section shown along the axial direction A in each figure, the flaring angle α2 corresponds to the intermediate angle between the second axial part 4b of the inner circumferential side 3 and the central longitudinal axis M of the bushing body 2.

[0043] This means that the value d2 of the bushing diameter d of the bushing body 2 determined by the inner circumferential side 3 increases along the axial direction A in the second axial part 4b. Here, the second flaring angle α2 of the second axial part 4b is greater than the possible first flaring angle α1 of the first axial part 4a. This means that the value d2 of the bushing diameter d in the second axial part 4b increases more than the value d1' of the bushing diameter d in the first axial part 4a. In Figure 1 and Figure 2 for better illustration, the two flaring angles α1, α2 are shown enlarged. The typical value range for the flaring angle α1 is from 0 to 5 angular minutes. The typical value range for the flaring angle α2 is from 4 to 25 angular minutes.

[0044] In addition, the bushing body 2 can be as in Figure 1 and 2In the two examples shown, a third axial part 4c is included, in which the inner circumferential side 3 is formed cylindrically, or flares away from the second axial part 4c at a third flare angle α3, preferably flares conically (shown by dashed lines in each of Figure 1 and 2 ). This means that the value d3 of the bushing diameter d of the bushing body 2 determined by the inner circumferential side 3 has a constant value d3 or increases along the axis A in the third part 4c. In a respective simplified variant of both the example of Figure 1 and Figure 2 , the third axial part 4c can be omitted.

[0045] In each of the above exemplary scenarios, the widening of the cylinder bushing 1 starting from the central longitudinal axis M measured along the radial direction R, i.e., perpendicular to the axis A, can be up to 100 μm, preferably approximately 50 μm.

[0046] In Figure 1 and Figure 2 's examples, the first surface roughness OR1 of the inner circumferential side 3 in the first axial part 4a is greater than the second surface roughness OR2 in the second axial part 4b. In addition, the third surface roughness OR3 of the inner circumferential side 3 in the third axial part 4c (if this third part 4c exists) is less than the first surface roughness OR1. In a variant of an embodiment, the third surface roughness OR3 can be equal to the second surface roughness OR2, but alternatively, it can also be less than or greater than the second surface roughness OR2. Thus, the surface roughness of the inner circumferential side 3 in the region of the first axial part 4a is the greatest, i.e., OR1 > OR2. OR1 > OR3 can also be applicable as appropriate.

[0047] For example, the first surface roughness OR1 of the inner circumferential side 3 in the first axial part 4a can be characterized by the following values: Rpk < 0.15 μm, Rk < 0.5 μm and Rvk is from 0.2 μm to 1.5 μm. In addition, the second surface roughness OR2 of the surface of the inner circumferential side 3 in the second axial part 4b can have the following values: RpK < 0.05 μm, and Rk < 0.15 μm, and Rvk < 0.2 μm. Here, Rk is the roughness of the roughness core profile, i.e., the so-called "core roughness". In addition, RpK is the average height of the peaks protruding from the core region, i.e., the so-called "reduced peak height". Finally, Rvk is the average depth of the valleys protruding from the core region, i.e., the so-called "reduced valley depth".

[0048] The platform appearance PA2 of the inner circumferential side 3 in the second axial part 4b is defined as R3p = Rvk / (Rpk + Rk), and is from 0.2 to 1.6, preferably from 0.6 to 1.6, and most preferably from 0.6 to 0.8. The texture height SH2 of the inner circumferential side 3 in the second axial part 4b is defined as R3k = Rpk + Rk + Rvk, and is at most 0.4 μm, preferably at most 0.2 μm.

[0049] Thereby, R3p characterizes the contact and core regions related to the surface valleys. R3k thereby characterizes the overall roughness of the honing texture without extreme peak and valley regions.

[0050] Desired surface roughness and platform appearance PA2 and texture height SH2 can be created by honing the axial parts 4a, 4b, 4c of the inner circumferential side 3 involved. It is also conceivable to apply a texture to the axial parts 4a, 4b, 4c of the inner circumferential side 3 involved, for example by means of a suitable laser or etching process.

[0051] In the two Figure 1 and longitudinal sections shown along the axis A, the inner circumferential side 3 travels in a straight line in each of the first axial part 4a, the second axial part 4b, and the third axial part 4c. However, it is also conceivable that two or all of the three axial parts 4a, 4b, 4c are designed to be bent (not shown in the drawings for clarity). It is also conceivable that one or more (first) sub-parts of the first axial part 4a, the second axial part 4b, and / or the third axial part 4c are formed in a straight line, and one or more (second) sub-parts of the first axial part 4a, the second axial part 4b, and / or the third axial part 4c are formed in a bent shape.

[0052] In Figure 1 and Figure 2 example, the second axial part 4b directly follows the first axial part 4a along the axis A. Similarly, the third axial part 4c directly follows the second axial part 4b along the axis A. Thereby, the three parts 4a, 4b, 4c are directly joined to each other.

[0053] In a first alternative variant of the example, an axial intermediate part (not shown) with a suitable outer contour of the inner circumferential side 3 between the first axial part 4a and the second axial part 4b can be formed cylindrically or have an opening angle, and can be straight or bent.

[0054] In a second alternative variant of the example, an axial intermediate part (not shown) with a suitable outer contour of the inner circumferential side 3 between the second axial part 4b and the third axial part 4c can be formed cylindrically or have an opening angle, and can be straight or bent. The first variant can be combined with the second variant.

[0055] Figure 1 and Figure 2 The cylinder liner 1 can be used in an internal combustion engine 10 such that it circumferentially delimits the cylinder bore 5 of the internal combustion engine. Here, the internal combustion engine 10 includes a piston (not shown in the drawings for clarity) adjustably disposed in the cylinder bore 5 between a top dead center OP and a bottom dead center UP.

[0056] As shown in the drawings, the top dead center OP is disposed in the first axial portion 4a of the cylinder liner 1. The bottom dead center UP is disposed in the third axial portion 4c. In the case of a simplified variant of the cylinder liner 1 that does not have the above-mentioned third axial portion 4c, the bottom dead center UP can be disposed in the second axial portion 4b.

Claims

1. A cylinder liner (1) for an internal combustion engine, - having a hollow cylindrical liner body (2) extending along an axial direction (A), and an inner circumferential side (3) of the hollow cylindrical liner body along the axial direction (A) including a first axial portion (4a) and a second axial portion (4b), - wherein the inner circumferential side (3) is cylindrically formed in the first axial portion (4a) or flares towards the second axial portion (4b) at a first flare angle (α1), - wherein, the second axial portion (4b) flares away from the first axial portion (4a) at a second flare angle (α2), and the second flare angle is greater than the first flare angle (α1) that could suitably exist in the first axial portion (4a), - wherein a first surface roughness (OR1) of the inner circumferential side (3) in the first axial portion (4a) is greater than a second surface roughness (OR2) in the second axial portion (4b), - wherein a plateau appearance (PA2) R3p = Rvk / (Rpk + Rk) of the inner circumferential side (3) in the second axial portion (4b) is 0.2 to 1.6, - wherein a texture height (SH2) R3k = Rpk + Rk + Rvk of the inner circumferential side (3) in the second axial portion (4b) is at most 0.4 μm.

2. The cylinder liner according to claim 1, characterized in that the first surface roughness (OR1) of the inner circumferential side (3) in the first axial portion (4a) is Rpk < 0.15 μm, where Rk < 0.5 μm and Rvk is 0.2 μm to 1.5 μm.

3. The cylinder liner according to claim 1 or 2, characterized in that the second surface roughness (OR2) of the inner circumferential side (3) in the second axial portion (4b) is Rpk < 0.05 μm, where Rk < 0.15 μm and Rvk < 0.2 μm.

4. The cylinder liner according to claim 1 or 2, characterized in that the liner body (2) includes a third axial portion (4c), in which the inner circumferential side (3) is cylindrically formed or flares away from the second axial portion (4b) at a third flare angle (α3), wherein the second axial portion (4b) is disposed between the first axial portion and the third axial portion (4c) in the axial direction (A).

5. The cylinder liner according to claim 4, characterized in that a third surface roughness (OR3) of the inner circumferential side (3) in the third axial portion (4c) is less than the first surface roughness (OR1) in the first axial portion (4a).

6. The cylinder liner according to claim 1 or 2, characterized in that a radial widening (W) of the cylinder liner (1) measured perpendicular to the axial direction (A) is 1 μm to 100 μm.

7. The cylinder liner according to claim 1 or 2, characterized in that - In a longitudinal section along the axial direction (A), the generatrix of the inner circumferential side (3) in the first axial part (4a) and / or the second axial part (4b) follows a curved path; and / or in that - In a longitudinal section along the axial direction (A), the generatrix of the inner circumferential side (3) in the first axial part (4a) and / or the second axial part (4b) follows a straight line.

8. The cylinder liner according to claim 4, characterized in that - In a longitudinal section along the axial direction (A), the generatrix of the inner circumferential side (3) in the third axial part (4c) follows a curved path; and / or in that - In a longitudinal section along the axial direction (A), the generatrix of the inner circumferential side (3) in the third axial part (4c) follows a straight line.

9. The cylinder liner according to claim 1 or 2, characterized in that the second axial part (4b) directly follows the first axial part (4a) along the axial direction (A).

10. The cylinder liner according to claim 4, characterized in that the third axial part (4c) directly follows the second axial part (4b) along the axial direction (A).

11. The cylinder liner according to claim 1, characterized in that the inner circumferential side (3) tapers towards the second axial part (4b) at the first opening angle (α1) in the first axial part (4a).

12. The cylinder liner according to claim 1, characterized in that the second axial part (4b) tapers away from the first axial part (4a) at the second opening angle (α2).

13. The cylinder liner according to claim 1, characterized in that the platform appearance (PA2) R3p = Rvk / (Rpk + Rk) is 0.6 to 1.

6.

14. The cylinder liner according to claim 1, characterized in that the platform appearance (PA2) R3p = Rvk / (Rpk + Rk) is 0.6 to 0.

8.

15. The cylinder liner according to claim 1, characterized in that the texture height (SH2) R3k = Rpk + Rk + Rvk is at most 0.2 μm.

16. The cylinder liner according to claim 4, characterized in that in the third axial part, the inner circumferential side (3) tapers away from the second axial part (4b) at the third opening angle (α3).

17. The cylinder liner according to claim 6, characterized in that the radial widening (W) is 50 μm.

18. An internal combustion engine (10) for a motor vehicle, - having at least one cylinder bore, which is defined on the circumferential side by a cylinder liner (1) according to any one of claims 1 to 17, - having a piston that is adjustably arranged in the cylinder bore between a top reversal point (OP) and a bottom reversal point (UP) along the axial direction (A) of the cylinder liner (1), - wherein, The top reversal point (OP) is provided in the first axial portion (4a) of the cylinder liner (1).

19. The internal combustion engine according to claim 18, characterized in that the bottom reversal point (UP) is provided in the second axial portion (4b) of the cylinder liner (1).

20. The internal combustion engine according to claim 18, characterized in that the bottom reversal point (UP) is provided in the third axial portion (4c) of the cylinder liner (1).

21. A motor vehicle having an internal combustion engine according to any one of claims 18 to 20.

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