EP3203059B1 - Cylinder bearing face of a cylinder of a reciprocating piston engine - Google Patents

Description

The invention relates to a cylinder running surface of a cylinder of a reciprocating piston engine.

Out DE 43 16 012 A1 a method for the finishing of bore walls in the cylinder of an internal combustion engine is known, according to which intersecting depressions in the form of grooves are to be produced in the surface by blasting. It should be noted that the grooves can be oriented differently depending on area-dependent wear within the cylinder. In this context, small intersection angles of the grooves of 5 ° to 30 ° in the area of the top dead center, somewhat larger intersection angles of 30 ° to 60 ° in a central area and parallel grooves in the axial direction in the area of the bottom dead center are proposed. It is also described that a plurality of plateau grooves with a smaller depth can be arranged between two grooves. No reference is made to a specific orientation of the plateau grooves and a specific arrangement between grooves and plateau grooves. Machining bores by means of plateau honing is described as negative on the grounds that plateau honing requires contact pressure that can lead to deviations in the bore cross-section from the ideal circular shape.

Out DE 10 2007 032 370 A1 a method for machining cylinder running surfaces of internal combustion engines is known, which is used for the production of cross-over grooves known as honing marks. It is pointed out that the grooves can be arranged in such a way that in different regions of a cylinder (viewed in the axial direction) different angles of intersection (referred to as honing angles in the document) are formed between the grooves that cross one another. In one embodiment, it is proposed to generate overlap angles of 140 ° in an upper and a lower area, which include the upper and lower dead center of the internal combustion engine and are thus reversal areas of the piston, and overlap angles of 50 ° in a central area. In another exemplary embodiment, a reverse selection of the intersection angles is described. Possible angle differences between the intersection angles are given as angle differences of 10 ° to 60 ° and 90 ° to 110 ° or more are referred to, with no indication of which angle differences should be suitable when.

Out DE 196 07 774 A1 a method for honing machining of cylinder running surfaces of reciprocating piston power and working machines is known, according to which grooves designated as twist honing marks and plateau grooves designated as honing marks are to be produced. With regard to the grooves, large intersection angles of 120 ° to 170 ° are proposed. With regard to the plateau grooves, small angles of 30 ° to 90 ° are suggested. The grooves and the plateau grooves each have the same orientation over the entire cylinder surface.

Out JP S59 196 954 A a cylinder running surface for an internal combustion engine is known. By honing, grooves are made in the cylinder surface and plateau grooves between the grooves. The angle of intersection between the grooves should be less than 30 °, and the angle of intersection between the plateau grooves should be at least 5 ° more than the angle of intersection between the grooves. The grooves and plateau grooves each have the same orientation over the entire cylinder surface.

The invention is based on the object of providing a cylinder running surface for a reciprocating piston machine, by means of which a particularly low-friction operation of a reciprocating piston machine is made possible.

The object is achieved according to the invention with the features of the independent claims. Further practical embodiments and advantages of the invention are described in connection with the dependent claims.

A cylinder running surface according to the invention of a cylinder for a reciprocating piston engine, in particular a reciprocating internal combustion engine or other reciprocating piston working machine, for example a reciprocating piston pump, has depressions in the form of spaced apart grooves, whereby plateaus are formed between adjacent grooves. With grooves that are spaced apart from one another, it is meant that, viewed in the vertical direction of the cylinder running surface, ie parallel to the central axis, two adjacent grooves are at a distance from one another. The grooves are formed consistently over the entire working height of the cylinder running surface with the same angle of intersection. Furthermore, the cylinder running surface has depressions in the form of plateau grooves formed in the region of the plateaus, first plateau regions being formed with a first orientation of plateau grooves and at least second plateau regions are formed with a second orientation of plateau grooves. The first orientation and the second orientation differ from one another. The grooves mentioned have a greater depth than the plateau grooves. The invention makes use of a principle determined by simulation calculations, according to which the orientation of the grooves is decoupled from the orientation of the plateau grooves. For example, in one embodiment of the invention, on a cylinder running surface according to the invention with - viewed over the entire cylinder height - grooves oriented only in one direction or with grooves that intersect at a constant angle of intersection only in a certain groove structure on the plateaus formed between the grooves Depending on the area, be arranged in first plateau areas in a first orientation and in second plateau areas in a second orientation. Thus, by a suitable choice of the orientation of the plateau grooves, the friction occurring during operation of the reciprocating piston machine can be minimized.

Likewise, on cylinder running surfaces with grooves crossing each other at a first angle of intersection, plateau grooves can be formed on plateaus between these flutes which intersect at a different angle of intersection and / or are otherwise oriented in another way, e.g. in that the central axis is pivoted with respect to the first intersection angle.

The invention thus particularly takes into account the fact that in cylinders of reciprocating piston machines a reciprocating piston is usually guided by the cylinder running surface and lubricant, in particular oil, is used to reduce friction. Because the reciprocating piston constantly changes its direction of movement during operation of reciprocating piston machines, it moves in a central area at relatively high speeds, while in the reversal areas it comes to a standstill or is only moved at low speeds. Lubricant collects in the grooves and plateau grooves and is intended to reduce friction by making it easier for the piston to slide off the cylinder running surface by means of a lubricating film. With an embodiment of a cylinder running surface according to the invention, the friction in a reciprocating piston machine can be reduced by optimizing the plateau grooves depending on the speed of the piston in certain areas of the cylinder running surface with the aid of simulation calculations. It has been shown that an optimization of the orientation of the plateau grooves that is decoupled from the orientation of the grooves can contribute to a significant reduction in friction. The orientation of the plateau grooves is particularly important in the reversal areas, since the piston only moves at a very low speed there becomes. In these areas, through a suitable design of the plateau grooves - in particular regardless of the orientation of the grooves in this area - particularly good results with regard to a reduction in friction can be achieved.

In the present case, grooves and plateau grooves are understood to mean in particular depressions extending over the circumference of a cylinder running surface and at least over a height range, which can be produced, for example, by honing and are formed helically on the cylinder running surface with a uniform rotational speed and uniform advance of the tool. This results in grooves and plateau grooves at equal distances from one another at every point on the circumference, viewed in the vertical direction of the cylinder. By varying the rotational speed and / or the tool feed, different designs can also be produced, in particular wave-shaped patterns of grooves and / or plateau grooves.

As already mentioned above, in practice intersecting grooves and plateau grooves are often formed with - at least in certain areas - constant overlapping angles on cylinder running surfaces. Simulation calculations carried out in connection with the invention were determined in particular on cylinder running surfaces in which plateau grooves intersecting at an intersection angle β are formed in first plateau areas and / or in second plateau areas. In this context, the angle of intersection β is understood to mean that angle which is formed between two plateau grooves in the vertical direction of the cylinder and which sweeps over the plane perpendicular to the central axis of the cylinder and running through the intersection of the plateau grooves. In the first plateau areas and in the second plateau areas, different intersection angles β and / or the same intersection angles, but the plateau grooves can be formed in different orientations to the plane perpendicular to the central axis. All variants are orientations that differ from one another within the meaning of the invention. It was found that with intersecting plateau grooves and / or grooves the transport of lubricant between individual plateau grooves or grooves is improved and the friction is reduced. It is particularly preferred if intersecting arrangements are selected for both the grooves and the plateau grooves, in particular by means of plateau honing at - within a range - constant rotational speed and constant feed, so that parallelogram-shaped patterns of grooves and plateau grooves are created.

In the case of a particularly low-friction cylinder running surface, plateau grooves intersecting at an intersection angle β _A are formed in the first plateau areas and plateau grooves intersecting at an intersection angle β _{B are} formed in the second plateau areas, the intersection angles being at least 30 ° apart. This embodiment of the invention has been made in particular in connection with plateau grooves with intersecting angles which are arranged symmetrically to planes (transverse planes) which are perpendicular to the vertical direction. However, it can be implemented independently of this orientation, ie also in connection with overlapping angles that are rotated with respect to the transverse planes. It has been shown that it is preferred if the distance between the intersection angles is at least 55 ° and particularly preferably at least 70 °. Such a distance between the overlap angles has proven to be advantageous in order to adapt the cylinder running surface to the frictional forces between the cylinder running surface and the reciprocating piston, which differ greatly, particularly in the central area and in the reversal areas.

If the first plateau areas are arranged in at least one reversal area of the cylinder and / or the second plateau areas are arranged in a central area deviating from the reversal area and the plateau grooves are suitably designed in these areas, a reciprocating piston engine operates with particularly low friction. This applies in particular to cylinder running surfaces which are divided into a central area (or several central areas) with high piston speeds and reversing areas with lower piston speeds. In the present case, the term reversal area means an area of a cylinder running surface which also includes at least the top dead center of the first piston ring or bottom dead center of the lowest piston ring (oil control ring) of a reciprocating piston guided in the cylinder or is directly adjacent to this area. In the case of pistons with several piston rings, such a region can, for example, start from the outermost piston ring, e.g. starting from the top edge of the top piston ring of a piston with several piston rings at top dead center, extend over 0.5 to 2 times the distance from the top piston ring to the bottom piston ring (oil control ring).

Alternatively and / or in addition, a reversal area can also be defined starting from the upper edge of the uppermost piston ring of the total stroke, for example as a maximum of 5% of the total stroke (working height H) from one of these dead centers. Due to the different speeds in the different areas, the friction changes. With an embodiment of a cylinder running surface according to the invention, one can be special for each area suitable design of the plateau grooves can be realized, not only taking into account the grooves formed in these areas, taking into account the interaction with the grooves, but also with regard to the piston speeds occurring in these areas. This takes place particularly advantageously through the arrangement of first plateau areas with plateau grooves which intersect at an intersection angle β _A in reversal areas and through the arrangement of second plateau areas with intersection angles β _B in a central area. The cylinder running surface can thus be optimally adapted to the design and the speed profile as well as to the formation of the grooves on the cylinder running surface. It is particularly preferred if first plateau areas with the same design of the plateau grooves and / or grooves are arranged both in the upper reversal area and in the lower reversal area.

According to the alternative definition, the top reversal area, which includes the top dead center of the first piston ring or which is located in the vicinity of the top dead center, is preferably one that extends along the central axis M over a height of 2 to 10% of the total working height H of the reciprocating piston Area set. As the lower reversal area, which includes the bottom dead center of the lowest piston ring (oil control ring) or which is arranged in the vicinity of the bottom dead center, an area extending along the central axis M over a height of 5 to 20% starting from the bottom dead center is preferred lowest piston ring (oil control ring). The central area accordingly preferably extends over a height of 60 to 93% of the working height H between the respective reversal areas.

In the simulation calculations carried out, it has also been shown to be particularly preferred if the plateau grooves are designed in such a way that an obtuse overlap angle β _A (ie an angle between 90 ° and 180 °) in first plateau-like areas, in particular in a reversal area, and / or an acute overlap angle β _B (ie an angle between 0 ° and 90 °) results in second plateau-like areas, in particular in a central area. A particularly clear friction-reducing effect always arises when plateau grooves with an obtuse intersection angle are formed in at least one reversal region. It is accordingly particularly preferred if an intersection angle β _{A is} at least 90 °, more preferably at least 100 ° and particularly preferably at least 110 °. A preferred range of values for β _A is between 100 ° and 170 °, more preferably between 110 ° and 150 ° and particularly preferably between 120 ° and 140 °. The intersection angle β _B in a central area is preferably between 10 ° and 50 ° are selected, more preferably between 20 ° and 40 ° and particularly preferably between 25 ° and 35 °.

The decoupling already described at the beginning is particularly friction-reducing if the orientation of the plateau grooves is at least partially different from the orientation of the grooves immediately surrounding these plateau grooves at least in a partial area of the cylinder. This means all embodiments in which the direction of the plateau grooves differs from the direction of the grooves immediately surrounding the plateau grooves, in particular if the grooves and plateau grooves do not have a curved course. This is particularly the case when the grooves and plateau grooves are produced by means of honing with a constant rotational speed and constant tool feed. In this case, the grooves and the plateau grooves do not run parallel on plateaus formed between the grooves.

In a further advantageous embodiment, the grooves have an area proportion of at least 20% of the total cylinder running surface. The proportion of the area of the grooves on the entire cylinder running surface is preferably 30% to 60%. In the present case, the area proportion of the grooves is understood to mean the proportion of the total cylinder running surface which includes grooves.

An exemplary calculation of the area share is given below in connection with Fig. 3 explained. The proportion of the area of the grooves is determined in particular by the number of grooves and the width of the grooves. The larger the area proportion of the grooves, the smaller the area proportion of the plateaus and thus the area available for plateau grooves. It should be pointed out that instead of the area share, approximately the value Mr2 of an Abott curve can also be used as the basis for calculating the area share of the grooves, the area share roughly corresponding to the value (1-Mr2). To this extent it is advantageous if a maximum of 80% is specified as the value Mr2, preferably a maximum of 70% and more preferably a maximum of 60%. The area proportion of the grooves is preferably chosen between 20% and 50%.

With grooves which at least partially have an acute angle of intersection α, particularly good results with regard to a reduction in friction were achieved in several simulation calculations. It has been shown that overlap angles α of 20 ° to 40 ° are preferred, those of 25 ° to 35 ° are particularly preferred, and those between 28 ° to 32 ° are more preferred. This applies above all to cylinder running surfaces according to the invention where the grooves are formed consistently over the entire working height H of the reciprocating piston with the same angle of intersection α. In this case, the production is also inexpensive because the grooves are produced consistently over the entire working height H. A change or complicated programming of tool parameters is not necessary in this case.

In a further practical embodiment, both the grooves and the plateau grooves each have an acute intersection angle α and β in the central region. In particular, it is simple and inexpensive if the intersection angles α of the grooves and the intersection angles β of the plateau grooves are designed to be the same in the central region. In this case, grooves and plateau grooves in the central area - apart from the depth of penetration - can be produced with the same tool angle settings.

In principle, a geometric configuration of a cylinder running surface as described above can be produced flexibly with any suitable method. However, it is particularly preferred and particularly cost-effective if the grooves and / or the plateau grooves are produced by honing. In particular, the so-called plateau honing can take place here in the form of multi-stage honing machining. Usually, in a first processing stage, grooves of a certain depth are produced in a cylinder running surface, whereby plateaus are formed between two adjacent grooves. In a second processing stage, plateau grooves are then formed on the plateaus between grooves, the plateau grooves likewise having a depth which, however, is less than the depth of the grooves. For the sake of completeness, reference is made to the fact that other mechanical and / or optical methods are also suitable for producing a cylinder running surface according to the invention, in particular beam methods, etching methods and laser methods.

In addition to the orientation of the grooves and plateau grooves and the angles of intersection, the depth and width of the grooves and plateau grooves can also be varied. With regard to the depth of the grooves, a depth of at least 1 μm has proven to be advantageous.

Furthermore, grooves and plateau grooves with different contours (cross-sectional shapes) can be produced; for example, the grooves or plateau grooves can have w-shaped, v-shaped, u-shaped or rectangular cross-sectional shapes. Different cross-sectional shapes can only be selected for grooves and plateau grooves in different areas.

Different widths of both the plateau grooves and the grooves can also be selected. These can also be designed differently in different areas. Grooves preferably have a greater width than plateau grooves.

The surface properties of cylinder running surfaces can be measured in particular using a laser, profilometer or scanning probe microscope. A so-called Abbott curve can be created and analyzed for characterization. Various parameters that characterize the surface are determined. Conclusions about the surface properties can be drawn from these parameters, in particular the core roughness R _k , the reduced peak _height R _pk , and the reduced groove depth R _vk as well as the material proportion Mr1 of so-called peaks and the material proportion Mr2 of so-called valleys. The value Mr2 represents a measure of the area portion of the grooves. Individual values of a so-called Abbott curve can also be specified for the production of desired surface properties, in particular if production is carried out by means of plateau honing.

• R_k: 0.05 - 0.4 µm, insbesondere 0,1 - 0,3 µm,
• R_pk: ≤0.2 µm, insbesondere ≤0,1 µm, bevorzugte Wertebereiche sind 0,04 µm - 0,14 µm, weiter bevorzugt 0,06 µm +/- 0,04µm,
• R_vk: 0.4 - 4.0 µm, insbesondere 0,8 - 3.0 µm.

In the present case, particularly good cylinder running surfaces with surfaces with parameters in the following value ranges were achieved, with the value ranges of individual parameters being advantageous both on their own and in combination with value ranges of other parameters:

• R _k : 0.05-0.4 µm, especially 0.1-0.3 µm,
• R _pk : ≤0.2 µm, in particular ≤0.1 µm, preferred value ranges are 0.04 µm - 0.14 µm, more preferably 0.06 µm +/- 0.04 µm,
• R _vk : 0.4-4.0 µm, in particular 0.8-3.0 µm.

• Flächenanteil der Riefen: 20 - 50 Prozent, insbesondere 30 - 50 Prozent oder alternativ: Mr2=80 - 50 Prozent, insbesondere 70 - 50 Prozent,
• Riefentiefe: 0,5µm - 4 µm, insbesondere 1 µm - 3 µm und bevorzugt 2 µm +/- 0,5 µm,
• Überschneidungswinkel im oberen Umkehrbereich: α = 30° (+/- Toleranz), β_A = 130° (+/-Toleranz),
• Überschneidungswinkel im Mittelbereich: α = 30° (+/- Toleranz), β_B = 30° (+/- Toleranz),
• Überschneidungswinkel im unteren Umkehrbereich: α = 30° (+/- Toleranz), β_A = 130° (+/- Toleranz),
• Die vorstehend genannten Toleranzen, insbesondere für β_A, können bis zu 30° betragen. Sie betragen vorzugsweise 10°, besonders bevorzugt 5° und weiter bevorzugt 3°,
• Prozentuale Verteilung der Gesamthöhe H des Zylinders auf einen oberen Umkehrbereich, einen Mittelbereich und einen unteren Umkehrbereich: vorzugsweise wie vorstehend beschrieben, insbesondere ausgehend von dem oberen Totpunkt eines ersten Kolbenrings: das 0,5 bis 2-fache des Abstands zwischen dem ersten Kolbenring und dem untersten Kolbenring (Ölabstreifring) und/oder 5 Prozent +/- 3 Prozent für den oberen Umkehrbereich,
  ausgehend von dem unteren Totpunkt eines untersten Kolbenrings (Ölabstreifring) das 0,5-fache bis 2-fache des Abstands zwischen dem ersten Kolbenring und dem untersten Kolbenring (Ölabstreifring) und/oder 10 Prozent +/- 5 Prozent für den unteren Umkehrbereich und
  den sich dazwischen ergebenden Bereich als Mittelbereich, d.h.
  Gesamthub zuzüglich dem Abstand zwischen dem ersten Kolbenring und dem untersten Kolbenring abzüglich des oberen Umkehrbereichs und des unteren Umkehrbereichs oder bei prozentualer Definition: 85 Prozent +/- 5 Prozent für den Mittelbereich.

From simulations and tests, the following arrangement of grooves and plateau grooves was found to be particularly low-friction:

• Area proportion of the grooves: 20 - 50 percent, in particular 30 - 50 percent or alternatively: Mr2 = 80 - 50 percent, in particular 70 - 50 percent,
• Groove depth: 0.5 µm - 4 µm, in particular 1 µm - 3 µm and preferably 2 µm +/- 0.5 µm,
• Overlap angle in the upper reversal area: α = 30 ° (+/- tolerance), β _A = 130 ° (+/- tolerance),
• Overlap angle in the middle area: α = 30 ° (+/- tolerance), β _B = 30 ° (+/- tolerance),
• Overlap angle in the lower reversal area: α = 30 ° (+/- tolerance), β _A = 130 ° (+/- tolerance),
• The tolerances mentioned above, in particular for β _A , can be up to 30 °. They are preferably 10 °, particularly preferably 5 ° and more preferably 3 °,
• Percentage distribution of the total height H of the cylinder over an upper reversal area, a central area and a lower reversal area: preferably as described above, in particular starting from the top dead center of a first piston ring: 0.5 to 2 times the distance between the first piston ring and the lowest piston ring (oil control ring) and / or 5 percent +/- 3 percent for the upper reversal area,
  starting from the bottom dead center of a bottom piston ring (oil control ring) 0.5 to 2 times the distance between the first piston ring and the bottom piston ring (oil control ring) and / or 10 percent +/- 5 percent for the lower reversal range and
  the area resulting in between as the middle area, ie
  Total stroke plus the distance between the first piston ring and the bottom piston ring minus the upper reversal area and the lower reversal area or with a percentage definition: 85 percent +/- 5 percent for the central area.

Fig. 1

einen Ausschnitt eines Zylinderblocks zur Führung eines nicht dargestellten Kolbens einer Hubkolbenbrennkraftmaschine mit einer Zylinderlauffläche in einer perspektivischen und teilweise geschnittenen Darstellung,

Fig. 2

eine vergrößerte Darstellung des in Figur 1 mit II gekennzeichneten Ausschnitts,

Fig. 3

einen Querschnitt durch eine Zylinderlauffläche zur vergrößerten Darstellung von Riefen und Plateaurillen in der Zylinderlauffläche in einer schematischen Darstellung,

Fig. 4

einen Ausschnitt einer sich über die Arbeitshöhe H erstreckenden Zylinderlauffläche der in Figur 1 gezeigten Hubkolbenbrennkraftmaschine mit hinsichtlich der Riefen und Plateaurillen unterschiedlich bearbeiteten Bereichen A, B und C in einer schematischen Darstellung und

Fig. 5

eine exemplarische Darstellung eines Kolbens in seinem oberen Totpunkt und in seinem unteren Totpunkt zur Erläuterung einer alternativen Definitionsmöglichkeit von unterschiedlich bearbeiteten Bereichen A, B und C.

Further practical embodiments of the invention are described below in connection with the drawings. Show it:

Fig. 1

a section of a cylinder block for guiding a piston, not shown, of a reciprocating internal combustion engine with a cylinder running surface in a perspective and partially sectioned illustration,

Fig. 2

an enlarged view of the in Figure 1 section marked with II,

Fig. 3

a cross section through a cylinder running surface for an enlarged representation of grooves and plateau grooves in the cylinder running surface in a schematic representation,

Fig. 4

a section of a cylinder running surface of the in Figure 1 shown reciprocating internal combustion engine with differently processed areas A, B and C with regard to the grooves and plateau grooves in a schematic representation and

Fig. 5

an exemplary representation of a piston in its top dead center and in its bottom dead center to explain an alternative definition of differently processed areas A, B and C.

In Fig. 1 a section of a cylinder block of a reciprocating piston engine in the form of a reciprocating piston internal combustion engine 10 is shown, which can be used, for example, to drive a motor vehicle. The cylinder block has a bore 12 for receiving and guiding a reciprocating piston (not shown) in a cylinder 22 produced by the bore. The bore 12 is surrounded by a cylinder running surface 14 for the reciprocating piston. Based on Figures 2 to 4 In the following, geometric designs of embodiments of cylinder running surfaces 14 according to the invention are described.

A cutout of the cylinder running surface 14 rolled into a plane according to the cutout marked II in FIG Figure 1 is in Figure 2 shown. The thick, parallel lines in Figure 2 These are depressions in the form of intersecting grooves 16. Between the grooves 16 there are plateaus 20 (hereinafter also referred to as plateau-like surfaces) which, in the embodiment shown, are designed in the form of a parallelogram. On these plateau-like surfaces 20, recesses with intersecting plateau grooves 18 are arranged at regular intervals. The plateau grooves 18 likewise enclose partial surfaces 26 which are embodied in the form of parallelograms and which are overlaid by the plateau-like surfaces 20 in parallelogram configuration. The height H _{T of} the parallelogram-shaped partial surfaces 26 formed by the plateau grooves 18, extending in the vertical direction of the cylinder 22, is in the present case smaller than the height H _{F of} the parallelogram-shaped plateau-like surfaces 20, which extends in the vertical direction of the cylinder 22. As a result, each parallelogram formed by plateau grooves 18 is from at least one groove 16 penetrates.

The representation according to Figure 2 was chosen in order to make the formation and arrangement of the grooves 16 and the plateau grooves 18 clearly visible in a common representation. In practice, the height H _{F is} preferably a multiple of the height H _T , in particular at least 3 times, at least 5 times or even at least 10 times. The plateau grooves 18 are preferably arranged in such a way that a factor between 3 and 20 results between the height H _F and the height H _T. Regardless of the type of surface shapes, the plateau grooves 18 are preferably arranged relative to the grooves 16 such that the plateau grooves 18 within a plateau-like surface 20 between 10 and 1000 partial areas 26 are formed, preferably 15 to 500 partial areas and particularly preferably 20 to 300 partial areas.

The intersecting grooves 16 are arranged in the transverse direction of the cylinder 22 with an intersection angle α to one another. The intersecting plateau grooves 18 on the plateau-like surfaces 20 are arranged at an intersection angle β to one another.

Figure 3 shows a schematic representation of a cylinder running surface 14 of a cylinder 22, the geometry of the cylinder running surface 14 in cross section after a first processing stage of plateau honing (far right) and after a second processing stage of plateau honing. After the second processing stage, the plateau-like surfaces 20 and the grooves 16 surrounding them are in the in Figure 2 shown condition. Even smoother plateau-like surfaces 20 can be produced by further processing stages.

As far right in Figure 3 is indicated, in a first processing stage, grooves 16 are first made in the cylinder running surface 14, so that a uniform, serrated profile with tips 24 protruding to the inside of the cylinder 22 and grooves 16 already formed with the desired depth results. In the present case, the grooves 16 are V-shaped in cross-section, and the ratio between the depth of the grooves 16 and the distance between the grooves 16 running parallel to one another in the cylindrical wall is selected so that a zigzag profile cross-section results after the first processing stage . The invention is not restricted to this possibility. In this respect, it is pointed out that any other shapes, depths and distances between the grooves 16 can be selected, which can also result in other cross-sectional geometries, for example tooth-shaped geometries with flank-like flattened areas between two adjacent grooves 16 and / or w-shaped, u- shaped or otherwise shaped grooves (not shown).

As shown on the left - viewed from the right - first groove 16, in a second processing stage between two grooves 16, plateau-like surfaces 20 extending parallel to central axis M of cylinder 22 are produced, in which plateau grooves 18 are formed.

Based on Figure 3 is explained below by way of example how the area portion of the grooves 16 is to be understood and how it can be calculated. It is assumed in the example that the ratio of grooves 16 to plateaus in the in Figure 3 The linear cross-sectional area shown is representative of the area ratio of the total cylinder surface area. In practice, the calculation can also be carried out on the basis of a representative partial area or on the basis of the entire cylinder surface area. In the present case, the area proportion of the grooves 16 in the region of the length L is determined. The area portion results from the sum of the individual widths of the grooves 16 within the area divided by the length of the area L, ie (R1 + R2 + R3 / L). The point with the greatest width of the groove 16 is defined as the width. R1 and R3 designate half the width of a groove 16 in the selected area, whereas R2 indicates the entire width of the groove 16.

In Fig. 4 the cylinder running surface 14 of the cylinder 22 is off Figure 1 Shown over the entire working height H, the working height H in this embodiment being the height range of the cylinder 22 over which the reciprocating piston (not shown) moves up and down along the cylinder running surface 14 when the reciprocating internal combustion engine shown is used as intended. As shown, the cylinder running surface 14 is divided into three areas A, B and C, the area A including the top dead center of the cylinder 22 shown and the area C including the bottom dead center of the cylinder 22 shown. The areas A and C are therefore reversal areas for the piston guided in the cylinder 22 (not shown). The area B is accordingly a central area. With regard to the speeds of the reciprocating piston, not shown, it can therefore be qualitatively determined that the reciprocating piston reaches the highest speed in the central area B compared to the cylinder running surface 14, while it is moved in the reversing areas A and C at lower speeds compared to the cylinder running surface 14. At the top dead center and at the bottom dead center, the speed even drops briefly to zero, which results in high static friction.

In the three areas A, B and C, grooves 16 and plateau grooves 18 are formed with partially different intersection angles α and β, both grooves 16 and plateau grooves 18 being shown only in partial areas and only schematically as straight lines. In fact, the grooves 16 and plateau grooves 18 extend helically over the entire circumference of the cylinder running surface 14 with a constant slope in the respective areas A, B and C. These can actually be designed differently, in particular as explained below.

In the embodiment shown, the cylinder running surface 14 has over all three areas A, B and C, i. Over the entire working height H, grooves 16 with a constant intersection angle α, which is selected between 20 ° and 40 °, preferably between 25 ° and 35 ° and particularly preferably between 28 ° and 32 °. In the embodiment shown, an overlap angle α of 30 ° is formed. It has been shown that groove intersection angles support the hydrodynamic pressure build-up in these value ranges and the solid body contact, i.e. the friction between the reciprocating piston and the cylinder running surface 14 is also reduced.

In the embodiment shown, the plateau grooves 18 are formed with different intersection angles β _A , β _B , β _C depending on the region A, B or C. In areas A and C, an intersection angle β _A and β _C of at least 90 °, preferably at least 100 ° and particularly preferably more than 110 °, is selected. The angle of intersection β _B is preferably selected between 10 ° and 50 °, preferably between 20 ° and 10 ° and particularly preferably between 25 ° and 35 °. In the embodiment shown, the angles of intersection β _A and β _{C are} 120 ° and the angle of intersection β _{B is} 30 °. The grooves 16 and the plateau grooves 18 in the central region B preferably have the same intersection angle α or β _B for reasons of processing technology. However, values that differ from one another can also be selected for the intersection angles β _A and β _C , in particular within the aforementioned value ranges.

Figure 5 shows a piston 28 which is shown in a cylinder 22, shown only schematically, with a cylinder running surface 14 in its top dead center (upper illustration) and in a lower dead center (below illustration). A first piston ring 30, a middle piston ring 32 and a lowermost piston ring (oil control ring) 34 are arranged on the piston 28, oriented toward the cylinder running surface 14. The distance between the first piston ring 30 and the lowermost piston ring 34 is marked with Z. An upper reversal region preferably extends in a region from the arrow O in the direction of the arrow A over a length of 0.5Z to 2Z.

Optionally, an area C can also be defined as the lower reversal area. Such a reversal area preferably extends from the arrow U, which indicates the position of the lowest piston ring 34 at bottom dead center, by 1Z to 4Z upwards, in particular by 2Z.

In particular for manufacturing reasons, it can be suitable to machine the reversal areas A, C from the area marked with O upwards and / or from the area marked with U downwards - possibly up to the upper or lower edge of the cylinder as in the adjacent areas A and C.

The central area B extends in this case between the areas A and C.

List of reference symbols

10

Reciprocating internal combustion engine

12

drilling

14th

Cylinder surface

16

Shouts

18th

Plateau grooves

20th

plateau-like area / plateau

22nd

cylinder

24

sharpen

26th

Partial areas

28

piston

30th

first piston ring

32

middle piston ring

34

lowest piston ring (oil control ring)

α

Intersection of grooves

β

Intersection of plateau grooves

Claims (10)

1. Cylinder running surface of a cylinder of a reciprocating piston engine with recesses in the form of grooves (16) spaced apart from one another, whereby plateaus (20) are formed between adjacent grooves (16) and with recesses in the form of plateau grooves (18) in the region of the plateaus (20), wherein the grooves (16) are formed consistently over the entire working height (H) of the cylinder running surface with the same intersection angle (α), the grooves (16) having a greater depth than the plateau grooves (18) and the first plateau regions are formed with a first orientation of plateau grooves (18),
   characterized in that,
   at least second plateau regions are formed with a second orientation of plateau grooves (18), the first orientation and the second orientation differing from one another.
2. Cylinder running surface according to the preceding claim, characterized in that in the first plateau regions and/or in the second plateau regions there are formed plateau grooves (18) which cross at an intersection angle (β).
3. Cylinder running surface according to the preceding claim, characterized in that plateau grooves (18) intersecting at an intersection angle (β_A) are formed in the first plateau regions and plateau grooves (18) intersecting at an intersection angle (β_B) are formed in the second plateau regions, wherein the intersection angles are spaced apart by at least 30°.
4. Cylinder running surface according to one or more of the preceding claims, characterized in that the first plateau regions are arranged in at least one reversal region (A, C) of the cylinder (22) and/or in that the second plateau regions are arranged in a central region (B) deviating from the reversal regions (A, C).
5. Cylinder running surface according to one of the two preceding claims, characterized in that the plateau grooves (18) are designed such that there is an obtuse intersection angle (β_A) and/or an acute intersection angle (β_B).
6. Cylinder running surface according to one or more of the preceding claims, characterized in that the orientation of the plateau grooves (18) is designed at least partially differently in at least a portion of the cylinder (22) compared to the orientation of the grooves (16) immediately surrounding these plateau grooves (18).
7. Cylinder running surface according to one or more of the preceding claims, characterized in that the grooves (16) have an area proportion of at least 20 percent of the total cylinder running surface (14).
8. Cylinder running surface according to one or more of the preceding claims, characterized in that the grooves (16) at least partially have an acute intersection angle (α).
9. Cylinder running surface according to one or more of the preceding claims, characterized in that the grooves (16) and the plateau grooves (18) each have an acute intersection angle (α, β) in a central region (B).
10. Cylinder running surface according to one or more of the preceding claims, characterized in that the grooves (16) and/or the plateau grooves (18) are produced by honing processing.

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