Sliding arrangement

Abstract

A sliding arrangement for use in an internal combustion engine is described, comprising a cylinder liner (1) and at least one piston ring (10), wherein the liner (1) has a through-bore defining an inner surface (S) which in turn defines three sections: a first section (2) near the end of the piston stroke, facing the cylinder head (at top dead center, TDC); a second, middle section (3); and a third section (4) near the end of the piston stroke, facing the crankshaft of the engine (at top dead center, TDC), wherein (i) the TDC section (2) of the liner (1) has a surface finish with a first roughness value defined by a structure of recesses and projections (“valleys” and “raised areas”); the middle section (3) of the liner (1) has a surface finish with a second roughness value defined by a structure of recesses and projections (“valleys” and “raised areas”);(1) the BDC section (4) of the cylinder liner (1) has a surface finish with a third roughness value defined by a structure of recesses and projections (“valleys” and “raised areas”), and the roughness value of the middle section (3) is significantly lower than the roughness value of the TDC section (2), and is defined by an essentially very smooth structure of recesses and projections (“valleys” and “raised areas”); and (ii) a ceramic coating (R) is applied to at least part of the contact surface of the piston ring (10) by the physical vapor deposition (PVD) process.

Description

[0001] The present invention relates to a sliding arrangement formed by a cylinder liner and a piston ring according to the preamble of claim 1.

[0002] A sliding arrangement according to the preamble of claim 1 is known from German patent application DE 695 05 467 T2. Further arrangements are described in German patent applications US 2006 / 0269790 A1, US 9650986 B2, and DE 10312227 A1.

[0003] The cylinder liner according to the present invention has an inner wall with a surface roughness such that, considering the reciprocating motion of a piston inside the liner, the central section has a lower roughness than the two boundary sections of the cylinder's stroke. The piston ring, in turn, has a ceramic coating deposited by physical vapor deposition (PVD), and this coating, in conjunction with the properties of the liner's contact surface, ensures high resistance to ring wear. Description of the state of the art

[0004] In an internal combustion engine, the greatest wear of the piston rings occurs due to the increased contact pressure at the free ends (tips) or in their vicinity.

[0005] In particular, the wear at the tips of the ring can be up to three times greater than in other areas of the part, with the occurrence of the phenomenon of chipping and peeling of the coating concentrated at this point.

[0006] Various techniques have been developed to reduce wear at the piston ring ends, but these efforts primarily focus on the piston ring itself. The different techniques developed for cylinder liners generally aim to reduce friction.

[0007] A first development is disclosed in patent DE 10 2006 057 111 A1 of the same applicant, which relates to a cylinder liner, wherein the roughness varies along its length in the direction of the piston's displacement within the liner. In particular, the section of the piston adjacent to the maximum stroke towards the cylinder head has a region with a first roughness, and the central region of the liner, with respect to the piston's stroke, has a second roughness, wherein the roughness value at the central section of the working surface of the liner exceeds the roughness value at the endpoints.However, the focus of this document is solely on the design of the bore, without relating this to the type of ring that will slide within this bore, and without specifying the distribution of valleys and elevations (mean roughness depth (Rz), core roughness depth (Rk), reduced peak height (Rpk)) on the surface of the bore.

[0008] Patent DE 10 2009 010 791 B4 discloses a cylinder liner provided with a surface roughness that is higher at the endpoints than in the central region. However, the method used to achieve these structures results in recesses of varying depths (with significant fluctuations in depth), thus reducing the potential effectiveness of this solution as a lubricating oil collection pocket. Furthermore, this document focuses solely on the design of the cylinder liner, without addressing the type of ring that will slide within it.

[0009] Patent DE 196 05 588 C2 relates to a cylinder liner whose inner surface has higher roughness values ​​at the end points than in the middle section. However, to achieve this result, the honing process is used, which has several technical parameters for treating the surface of the end point areas, while different parameters are used in the middle section. Furthermore, the focus of this document is solely on the design of the cylinder liner, without any connection to the type of ring that will slide within this cylinder liner.

[0010] Patent JP 2004 / 176556 defines a cylinder liner in which the angle between the recesses is variable and is larger at the end of the piston stroke (angle α) than at the middle section (angle γ). At the intermediate sections, between the middle section and each of the endpoints, the angle (β) is intermediate.

[0011] Finally, patent specification FR 2 884 889 B1 relates to a cylinder liner whose sliding surface has three roughness values, with (i) a first value S1, which is lower (less rough) in the endpoint section facing the cylinder head, the middle section, and the opposite endpoint; (ii) a second roughness value S2 of medium roughness, which is applied between the endpoint section facing the cylinder head and the middle section; and finally (iii) a third, higher roughness value S3, which is applied between the middle section and the endpoint section opposite the endpoint section facing the cylinder head. Here again, the focus is solely on the design of the liner, without any connection to the type of ring that will slide within this liner.

[0012] With the aim of reducing this wear, the applicant has developed the present sliding arrangement, wherein the cylinder liner has an inner wall exhibiting a variation in the roughness of the contact surface such that, considering the reciprocating motion of a piston within the liner, the central section has a roughness lower than that of the two limiting sections of the piston's stroke (top dead center (TDC) and bottom dead center (BDC)). In the present solution, although the roughness varies, the structure of the recesses and projections ("valleys" and "ridges") defining the roughness is essentially uniform, which allows for a more detailed examination and greater efficiency of the recesses with regard to their function as oil reservoirs.

[0013] As far as the piston ring is concerned, it has a ceramic coating applied by means of the physical vapor deposition process (PVD), and this coating, together with the properties of the contact surface of the cylinder liner, ensures a high resistance to wear. Objectives of the invention

[0014] One of the problems underlying the present invention relates to a sliding arrangement formed by a cylinder liner and a piston ring, wherein the cylinder liner has an inner wall which has a change in the roughness of the contact surface such that, taking into account the reciprocating movement of a piston inside the liner, the central section has a lower roughness than that of the two sections near the piston stroke (in particular near top dead center, TDC), thereby enabling a reduction in the wear of the piston ring, which has a ceramic coating applied by means of the physical vapor deposition (PVD) process.

[0015] A further object of the present invention relates to a sliding arrangement formed by a cylinder liner and a piston ring, wherein the cylinder liner has an inner wall which has a change in the roughness of the contact surface such that, taking into account the reciprocating movement of a piston inside the liner, the central section has a lower roughness than that of the two limiting sections of the piston stroke (particularly in the vicinity of top dead center, TDC), wherein the presence of the structure of the deepest recesses (“valleys”) in the area near top dead center enables a reduction in the wear of the piston ring, which is provided with a ceramic coating applied by means of the PVD process, in particular due to chipping. Brief description of the invention

[0016] The problems of the present invention are solved by a sliding arrangement for use in an internal combustion engine, comprising a cylinder liner and at least one piston ring, wherein the liner is provided with a continuous cavity defining an inner surface which in turn defines three sections, namely a first section near the limit of the piston stroke, facing the cylinder head of the engine (near top dead center, TDC), a second, middle section, and a third section near the limit of the piston stroke, facing the crankshaft of the engine (near top dead center, TDC), wherein: (i) the TDC section of the cylinder liner has a surface finish with a first roughness value defined by a structure of recesses and projections (“valleys” and “raised areas”); the middle section of the cylinder liner has a surface finish with a second roughness value defined by a structure of recesses and projections (“valleys” and “raised areas”); the BDC section of the cylinder liner (1) has a surface finish with a third roughness value defined by a structure of recesses and projections (“valleys” and “raised areas”), wherein the roughness value provided by the middle section is significantly lower than the roughness value of the TDC section, and has a structure of recesses and projections (“valleys” and “raised areas”) which define this structure substantially uniformly; and (ii) the roughness of the TDC section and the roughness of the BDC section are essentially the same; and (iii) the roughness of the central section of the cylinder liner has values ​​of substantially up to 0.10 Rpk, 0.10 to 0.40 Rk and up to 1.0 RvK, in micrometers, or the roughness of the central section of the cylinder liner has values ​​of substantially up to 0.30 Rpk, 0.15 to 0.65 Rk and 1.1 to 2.1 RvK, in micrometers.

[0017] Essential to the invention is that the piston ring provides at least a portion of the contact surface onto which a ceramic coating is applied by the physical vapor deposition process. Furthermore, it is essential to the invention that the surface finish of the TDC section of the cylinder liner has a honing angle in the range of 20° to 25°, and the surface finish of the central section of the cylinder liner has a honing angle of approximately 155°. Summary description of the characters

[0018] The present invention is explained in more detail below on the basis of an exemplary embodiment shown in the drawings.

[0019] The figures show: Fig. 1 a cross-sectional view of the cylinder liner forming part of the sliding arrangement according to the invention. Fig. 2 a schematic view of the in Fig. 1 illustrated cylinder liner, which shows the schematic representation of the roughness of the sliding surface along its longitudinal length. Fig. 3 a schematic view of the in the Fig. 1 and Fig. 2 illustrated bushings, which show the schematic representation of the roughness of the sliding surface along its longitudinal length, and diagrams which demonstrate the average roughness value at different sections. Fig.4 a schematic cross-sectional view of the cylinder liner and piston ring belonging to the sliding arrangement of the present invention, wherein the ring is installed in the groove of a piston. Fig. 5 an enlarged, schematic cross-sectional view of a part of the cylinder liner and piston ring forming part of the sliding arrangement subject of the present invention. Fig. 6 a diagram of the relationship between the coefficient of friction µ and the displacement velocity of the piston / ring on the surface of a cylinder liner, taking into account different honing angles. Fig.7 a diagram showing the thickness of the oil film varying as a function of the crankshaft angle, taking into account a cylinder liner with a high roughness (plateau), low roughness (sliding) and the technological subject matter of the present invention, wherein there is a change in the roughness of the contact surface such that the middle section has a roughness that is less than that provided by the upper limiting section of the piston stroke (near top dead center, TDC). Fig.8 a diagram which shows the power lost through friction as a function of the crankshaft angle, taking into account a cylinder liner with high roughness (plateau), low roughness (sliding) and the technological subject matter of the present invention, wherein there is a change in the roughness of the contact surface such that the middle section has a roughness that is lower than that provided by the upper limiting section of the stroke of the piston (near top dead center, TDC). Detailed character description

[0020] The present invention relates to a sliding arrangement comprising a cylinder liner 1 and at least one piston ring 10, both of which have been specially developed, wherein the cylinder liner defines an inner wall which has a change in the roughness of the contact surface such that, taking into account the reciprocating movement of the ring inside the liner, the central section has a lower roughness than that of the two sections near the limits of the piston stroke (top dead center, TDC, and bottom dead center, BDC). The piston ring has a ceramic coating R which has been applied by means of the physical vapor deposition process (PVD process).

[0021] The arrangement of the present invention reduces wear on the piston ring coating by providing large-volume, uniformly spaced recesses on the running surface. This reduction in wear decreases the occurrence of spalling.

[0022] To describe the sliding arrangement, the object of the present invention, in more detail, the cylinder liner 1 is provided with a continuous cavity with a longitudinal / axial length C, in the interior of which the piston ring 10 is positioned. Fig. Figure 4 illustrates the piston with its respective rings, where at least one of these rings is ring 10, which is provided with a ceramic coating R applied by physical vapor deposition. The continuous cavity defines an inner surface S.

[0023] The piston ring 10 can be configured in any required or desired manner. Preferably, the ring 10 is a first grooved ring, or compression ring, with a metal base; however, it is obvious that it can also assume the configuration of a second grooved ring or even an oil scraper ring, the resulting sliding arrangement being also included within the scope of protection of the appended claims.

[0024] Similarly, the base material of the ring 10 can be freely chosen, provided that it allows the application of a ceramic coating R, such as chromium nitride, niobium nitride or others, by means of the physical vapor deposition process PVD.

[0025] The cylinder liner 1 is usually made of iron alloys, cast iron, or steel; however, it is obvious that it can be made of any other required or desirable material (such as aluminum alloys), and it should also be noted that the resulting invention is likewise included within the scope of the appended claims. Similarly, the cylinder liner 1 can have any required or desirable format, provided it is functional.

[0026] The surface S defines 3 main sections, which are located in the Fig. 2 and Fig.3 are clearly recognizable, showing: a first section 2 corresponding to the area near the limit of the piston stroke, which faces the cylinder head (top dead center, TDC), hereinafter referred to as the TDC section; a second, middle section 3; and a third section 4 corresponding to the area near the limit of the piston stroke, but opposite (facing the crankshaft of the machine, bottom dead center, BDC), hereinafter referred to as the BDC section.

[0027] It is further evident that the length and area of ​​each of the sections 2, 3, 4, depending on the diameter of the cylinder liner, the stroke of the piston and the axial length of the cylinder liner, among other variables, is arbitrarily variable.

[0028] Regardless of the design of the cylinder liner 1, and taking into account the three sections 2, 3, 4 defined on the inner surface S, it is essential that these are formed in such a way that: (i) the TDC section (2) has a surface finish with a first roughness value defined by a structure of recesses and protrusions (“valleys” and “high points”); (ii) the middle section (3) has a surface finish with a second roughness value defined by a structure of recesses and protrusions (“valleys” and “raised areas”); and (iii) the BDC section (4) has a surface finish with a third roughness value defined by a structure of recesses and protrusions (“valleys” and “raised areas”).

[0029] Preferably, the TDC section 2, the middle section 3, and the BDC section 4 are given a surface finish such that they achieve the respective first, second, and third roughness values ​​through the honing process. Some solutions known from the prior art employ other surface finishing processes to achieve different roughness standards in the longitudinal view of the cylinder liner; however, the present invention uses honing and controls the process changes in such a way that significantly different roughness values ​​are obtained on the same surface S, while additionally ensuring the control of the angle of the grooves inherent in this type of process, which will be explained below.

[0030] Furthermore, it is an essential condition for the cylinder liner 1 that the second roughness value (represented by the central section 3) is significantly lower than the roughness value of the TDC section 2, with the aim of ensuring maximum performance with regard to the engine's operating efficiency and reducing ring wear, particularly at the tips. Preferably, but not necessarily, the roughness value of the BDC section 4 is also higher than that of the central section 3. A more detailed explanation of the reason for the greater efficiency of the cylinder liner 1 compared to the others, which is the subject of the present invention, is given below.

[0031] Another essential feature of the arrangement of the present invention lies in the control of the honing process of the cylinder liner 1, the subject of the present invention, on the TDC, middle, and BDC sections 2, 3, 4, to ensure that the structure of the recesses and projections (“valleys” and “raised areas”) on each of these sections is substantially uniform over the entire surface on which it is distributed.

[0032] In other words, with respect to the respective roughness value at each of sections 2, 3, 4, the microscopic recesses (“valleys”) have the same average depth with low standard deviation, in the same way as the protrusions (“elevations”) have the same average height with equally low standard deviation.

[0033] In this way, it is ensured that, with regard to the recesses, the depth and volume provided are ideal for storing lubricating oil, and that, with regard to the protrusions, the avoidance of very high protrusions is achieved, which prolongs the break-in period of the piston and also leads to an increase in fuel consumption and a temperature increase, both of which are undesirable.

[0034] Another essential property provided by the liner 1 is that the roughness value provided by the middle section 3 is significantly lower than the roughness values ​​of the TDC and BDC areas 2, 4.

[0035] In this regard, it should be noted that during operation of the internal combustion engine, the linear velocity of the piston decreases at the end points (limitation of the stroke, corresponding to top dead center TDC and bottom dead center BDC) and increases in the middle section of the cylinder liner (at half the stroke). This fact results in significant fluctuations in the loads to which the piston P and ring 10 are subjected.

[0036] In situations near the limit of the stroke (i.e., near TDC and BDC sections 2 and 4 of the surface S of the cylinder liner 1), the linear velocity of the piston is low, regardless of whether it is accelerating or decelerating. In this situation, the low velocity results in less friction loss because the distance traveled by the piston per unit of time is short. In the case of the cylinder liner 1, the higher surface roughness, in addition to the low velocity resulting in less wear, leads to the presence of high-height projections and deep recesses such that the oil contained within them significantly contributes to preventing ring / surface friction, thereby ensuring less wear on the rings, especially at their tips.In other words, the essentially uniform structure of the recesses and projections, which defines the second roughness value provided by the second section 3, allows the recesses to be dimensioned more efficiently to act as oil reservoirs.

[0037] Furthermore, the speed of linear displacement of the piston in the central section 3 of the cylinder liner 1 is high, and simultaneously the surface roughness is low (due to the fact that the surface roughness provided by the second section 3 is significantly lower than that provided by the TDC and BDC sections 2 and 4). This configuration reduces friction-induced engine losses, with this effect theoretically being more pronounced in the central section for the same surface roughness due to the greater distance traveled by the piston per unit of time.

[0038] In the middle section 3, the piston / ring speed is higher. A larger hydrodynamic film is generated. The forces exerted by the gases on the compression ring are lower, which is why a smaller oil reservoir is required. Furthermore, due to the higher speeds, frictional (power) losses are greater.

[0039] In this area, the proposed solution of lower roughness produces smaller oil films and friction losses, without a significant impact on wear.

[0040] Preferably, but not necessarily, the roughness provided by BDC section 4 and the roughness provided by TDC section 2 are essentially the same; however, they may differ from each other, provided that they are lower than the second roughness, with the aim of improving the performance of the liner 1. In any case, it is sufficient that the roughness at TDC section 2 is greater than the roughness of the middle section 3.

[0041] The table below presents three possible embodiments for the bushing 1, object of the present invention, each designated as “evolution A”, “evolution B” and “evolution C”. Design A Design B embodiment C Rpk RK Rvk Rpk RK Rvk Rpk RK Rvk TDC 0.10 to 0.30 0.80 to 1.10 2.1 to 2.8 0.15max 0.80 to 1.10 2.1 to 2.8 like version A (possibly like B) center 0.25max 0.15 to 0.65 1, 1 to 2, 1 0.10max 0.10 to 0.40 1, 0max BDC same as TDC same as TDC same as TDC Honwinke1 50 to 60° 50 to 60° 20 to 25° amTDC, about 155° in the middle. At the BDC, as seems easiest.

[0042] Design A has the following values, in micrometers: (i) The roughness of TDC section 2 has values ​​of essentially 0.10 to 0.30 RpK, 0.80 to 1.10 Rk and 2.1 to 2.8 Rvk. (ii) The roughness value of the middle section 3 (referred to as ‘middle’ in the table) has values ​​of essentially up to 0.30 RpK, 0.15 to 0.65 Rk and 1.1 to 2.1 Rvk, and (iii) The roughness value of BDC section 4 has values ​​of essentially 0.10 to 0.30 RpK, 0.80 to 1.10 Rk and 2.1 to 2.8 Rvk.

[0043] In contrast, embodiment B has the following values ​​(in micrometers): (i) The roughness value of TDC section 2 has values ​​of essentially up to 0.15 RpK, 0.80 to 1.10 Rk and 2.1 to 2.8 Rvk. (ii) The roughness value of the middle section 3 (referred to as ‘middle’ in the table) has values ​​of essentially up to 0.10 RpK, 0.10 to 0.40 Rk and up to 1.0 Rvk. (iii) The roughness value of BDC section 4 has values ​​of essentially up to 0.15 RpK, 0.80 to 1.10 Rk and 2.1 to 2.8 Rvk.

[0044] Finally, the third embodiment, C, offers the same values ​​as embodiments A or B with respect to the three roughness values ​​(also in micrometers), but with changes in the angle of the recesses (channels) resulting from the honing process. Although the relevant literature indicates that larger angles lead to increased friction, which is undesirable in the middle of the stroke, the computer simulations performed by the applicant show that changing the angle along the stroke offers the additional advantage of the smaller (horizontal) angle at the TDC (Total Displacement Center), resulting in greater oil retention due to the recesses being perpendicular to the piston / ring movement. In the middle of the stroke, the largest (more vertical) angle of the recesses facilitates oil flow, contributing to both a reduction in the thickness of the recess and the resulting friction.

[0045] In order to demonstrate the advantages of the present invention, the applicant has carried out a series of comparative studies analyzing the performance of a bushing such as that of the present invention in comparison with conventional solutions, the latter being a bushing in which the entire surface S offers a high roughness (a solution referred to as plateau) and a bushing in which the entire surface S offers a low roughness (a solution referred to as sliding).

[0046] The investigations concern a compression ring 10 and a cylinder liner for an engine having a cylinder diameter of 70.9 mm, a piston stroke of 75.6 mm, a connecting rod with a length of 144 mm, taking into account a constant rotation at 2000 rpm under full load and using a lubricating oil of specification SAE 20W50 at a temperature of 200 °C.

[0047] The solution referred to as plateau (roughest) has the advantage of forming a thick film on the surface S, accompanied by greater friction, while the solution referred to as sliding has significantly less friction, but accompanied by a thinner oil film, disadvantageous in borderline lubrication situations.

[0048] The present invention offers the advantages of plateau and sliding solutions without their respective disadvantages, thus combining the best of each. Investigations carried out by the applicant have shown that the present invention ensures a thick oil film on the TDC section 2, resulting in reduced wear at this point, and simultaneously low roughness in the central section, ensuring lower frictional losses (power wasted due to friction).

[0049] In particular, the present solution offers a 15% reduction in friction losses compared to the plateau (roughest) solution, which is very close to the reduction achieved by the sliding solution (reduction of 21%), while simultaneously providing a film thickness in the TDC section 2 of 1.5 µm, which is essentially twice the thickness achieved by the sliding solution (0.7 µm).

[0050] The graphic from Fig. Figure 7 illustrates the oil film thickness varying as a function of the crankshaft angle, with a cylinder liner having high plateau roughness, low sliding roughness and the technological subject matter of the present invention.

[0051] Analysis of this graph clearly shows that the oil film of the solution of the present invention is practically identical to the oil film provided by the plateau solution at the piston's reversal points (TDC 2 and BDC 4 sections), which are represented in the graph by the crankshaft angle markings 0°, 180°, 360°, 540° and 720°, while the oil film in the middle section 3 is greatly reduced, represented in the graph by the crankshaft angle markings 90°, 270°, 450° and 630°, than in the sliding solution.

[0052] The graphic of Fig.Figure 8 illustrates the power lost due to friction as a function of the crankshaft, showing a cylinder liner with high plateau roughness, low sliding roughness, and the technological subject matter of the present invention. It is clearly evident that the solution according to the invention offers significantly lower values ​​for power lost due to friction than the plateau solution, and values ​​that are practically identical to the sliding solution, only being higher in sections TDC 2 and BDC 4.

[0053] These results confirm that the solution of the present invention offers all the advantages of plateau and sliding solutions without entailing their respective disadvantages.

[0054] The present sliding arrangement, as demonstrated by the aforementioned investigations, results not only in an increase in the service life of the coating R of the piston ring, but also in a reduction in the fuel consumption of the engine equipped with it by up to 1%.

[0055] In the context of the description of a preferred embodiment, it should be noted that the scope of protection of the present invention covers other possible variations, which is limited only by the content of the attached claims, which contain possible correspondences.

Claims

[1] Sliding arrangement for use in an internal combustion engine, comprising a cylinder liner (1) and at least one piston ring (10), wherein the cylinder liner (1) is provided with a continuous cavity defining an inner surface (S) which in turn defines three sections, namely a first (TDC) section (2) near a limit of the piston stroke, facing a cylinder head (near top dead center, TDC), a second, middle section (3), and a third (BDC) section (4) near the limit of the piston stroke, facing a crankshaft of the internal combustion engine (near bottom dead center, BDC), (i) wherein the TDC section (2) of the cylinder liner (1) has a surface finish with a first roughness value defined by a structure of recesses and projections (“valleys” and “raised areas”); the middle section (3) of the cylinder liner (1) has a surface finish with a second roughness value defined by a structure of recesses and projections (“valleys” and “raised areas”); the BDC section (4) of the cylinder liner (1) has a surface finish with a third roughness value defined by a structure of recesses and projections (“valleys” and “raised areas”), wherein the roughness value of the middle section (3) is significantly lower than the roughness value of the TDC section (2) and is defined by a substantially uniform structure of recesses and projections (“valleys” and “raised areas”); and (ii) wherein the roughness of the TDC section (2) and the roughness of the BDC section (4) are essentially the same; and (iii) the roughness of the central section (3) of the cylinder liner (1) has values ​​of substantially up to 0.10 Rpk, 0.10 to 0.40 Rk and up to 1.0 RvK, in micrometers, or the roughness of the central section (3) of the cylinder liner (1) has values ​​of substantially up to 0.30 Rpk, 0.15 to 0.65 Rk and 1.1 to 2.1 RvK, in micrometers, characterized by , that - the piston ring (10) provides at least a part of the contact surface onto which a ceramic coating (R) is applied by a physical vapor deposition process, and that - the surface finish of the TDC section (2) of the cylinder liner (1) has a honing angle in the range between 20° and 25°, - the surface finish of the middle section (3) of the cylinder liner (1) has a honing angle of approximately 155°. [2] Sliding arrangement according to claim 1, characterized by , that if the roughness of the middle section (3) of the cylinder liner (1) has values ​​of substantially up to 0.30 Rpk, 0.15 to 0.65 Rk and 1.1 to 2.1 RvK, in micrometers, the roughness of the TDC section (2) of the cylinder liner (1) has values ​​of substantially 0.10 to 0.30 Rpk, 0.80 to 1.10 Rk and 2.1 to 2.8 RvK, in micrometers. [3] Sliding arrangement according to claim 1, characterized by , that if the roughness of the middle section (3) of the cylinder liner (1) has values ​​of substantially up to 0.30 Rpk, 0.15 to 0.65 Rk and 1.1 to 2.1 RvK, in micrometers, the roughness of the BDC section (4) of the cylinder liner (1) has values ​​of substantially 0.10 to 0.30 Rpk, 0.80 to 1.10 Rk and 2.1 to 2.8 RvK, in micrometers. [4] Sliding arrangement according to claim 1, characterized by, that if the roughness value of the middle section (3) of the cylinder liner (1) has values ​​of substantially up to 0.10 Rpk, 0.10 to 0.40 Rk and up to 1.0 RvK, in micrometers, the roughness value of the first section (2) of the cylinder liner (1) has values ​​of substantially up to 0.15 Rpk, 0.80 to 1.10 Rk and 2.1 to 2.8 RvK, in micrometers. [5] Sliding arrangement according to claim 1, characterized by , that if the roughness of the middle section (3) of the cylinder liner (1) has values ​​of substantially up to 0.10 Rpk, 0.10 to 0.40 Rk and up to 1.0 RvK, in micrometers, the roughness of the BDC section (4) of the cylinder liner (1) has values ​​of substantially up to 0.15 Rpk, 0.80 to 1.10 Rk and 2.1 to 2.8 RvK, in micrometers.

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