DE102016223772A1 - Method for machining a cylinder wall and cylinder crankcase with machined cylinder wall - Google Patents

Abstract

The present invention relates to a method for machining a cylinder wall (11) of a longitudinally extending cylinder bore (10) of an internal combustion engine. The method comprises activating the cylinder wall (11) by inserting an anchoring structure (20), and applying a coating (30) serving as a running surface to the activated cylinder wall (11), the coating engaging the anchoring structure (20). The coating is applied in such a way that a thickness (D) of the coating in the longitudinal direction (L) varies according to the anchoring structure (20) and additionally according to a thickness profile (D1) superimposed on the anchoring structure. The present invention further relates to a cylinder crankcase manufactured according to this method.

Description

The invention relates to a method for processing a cylinder wall of a cylinder bore extending in a longitudinal direction of an internal combustion engine, in which the cylinder wall is first activated and then a serving as a running surface coating is applied to the activated cylinder wall. In particular, the invention relates to a method for processing a cylinder wall, wherein an anchoring structure is introduced into the cylinder wall, in which the coating can engage and thereby adheres particularly well to the cylinder wall. The invention further relates to a cylinder crankcase produced according to such a method.

Internal combustion engines in motor vehicles are formed for weight reasons regularly with a cylinder crankcase made of light metal, in particular aluminum. The problem with this, however, is that the inner walls of the cylinders formed by the cylinder block due to the tribological properties of the light metal, in particular the relatively poor wear resistance, are insufficiently suitable as running surfaces for the pistons.

For this reason, in some internal combustion engines with a cylinder crankcase made of light metal liners, eg. From gray cast iron, used, whereby the advantages of the light metal (light weight) with those of the gray cast iron (good tribological properties) can be combined.

Alternatively, it is known to provide the cylinder walls of the cylinder bores with a coating in order to realize the desired tribological properties for the treads. The coating is thereby realized regularly by melting a coating material and spraying onto a possibly pretreated cylinder wall.

Of particular importance in the coating of cylinder walls is the realization of good adhesion of the coating to the base material, i. on the cylinder wall. For this purpose, it is known to activate the cylinder wall of the cylinder crankcase prior to coating in order to increase the contact area between the layers. The activation can be done, for example, by roughening the cylinder wall, for example by introducing grooves or other depressions. The depressions introduced by the activation into the cylinder wall for improving the adhesion of the coating are referred to herein as the anchoring structure.

The molten coating material can engage in the recesses of the anchoring structure and thereby firmly anchored to the cylinder wall.

Various methods for introducing an anchoring structure into a cylinder wall are known.

For example, from the publication DE 10 2009 027 200 B3 it is known to introduce a spiral groove into the cylinder wall in a first method step for roughening a cylinder wall. In a second step, the web which runs in a spiral between the groove is then plastically deformed in sections, in order to form undercuts. To insert the groove, a tool is used, which has a cutting edge, wherein the tool is both rotationally driven and moved axially along the longitudinal axis of the cylinder.

Alternative methods of activating cylinder walls for a subsequent coating include chemical and electrical roughening, brushing and priming.

The coating should on the one hand provide good wear resistance and durability and on the other hand provide a suitable tribological system in cooperation with the piston.

In view of this difficulty, the invention has for its object to provide a coated cylinder wall for an internal combustion engine and a method for their production, which achieves particularly good results both in terms of their wear resistance and in view of the provided friction properties.

This object is achieved by a method of o.g. Art solved with the features characterized in claim 1 and by a cylinder crankcase with the feature according to claim 13. Advantageous embodiments of the invention are described in the dependent claims.

In the method according to the invention, it is provided that the coating serving as a running surface is applied in a predetermined varying thickness profile on the cylinder wall. In this case, the thickness of the coating varies according to the anchoring structure and additionally in the longitudinal direction according to the thickness profile superimposed on the anchoring structure.

Since the coating is applied to the anchoring structure and engages the anchoring structure, the thickness of the coating (at least after smoothing of the coating surface, for example by honing) varies according to the profile of the anchoring structure. In other words, the coating engages the recesses of the anchoring structure and thus anchors to the cylinder wall so that the thickness of the coating varies on a first (smaller) length scale according to the anchoring structure.

According to the invention, however, the thickness of the coating additionally varies according to a thickness profile which varies at least in sections in the longitudinal direction of the cylinder bore and which superimposes the anchoring structure. In other words, the anchoring structure represents a "micro-profile" followed locally by the thickness of the coating, and the thickness profile represents a "macro-profile" followed by the thickness of the coating on a second (larger) length scale. In this case, the thickness profile of the coating preferably varies in the longitudinal direction of the cylinder bore, but is preferably constant in the circumferential direction of the cylinder bore in cutting planes running perpendicular to the longitudinal direction. For example. For example, the anchoring structure is formed as a plurality of anchoring elements such as micro-recesses or engagement grooves in the cylinder wall. The variations of the thickness profile have a larger dimension than these anchoring elements of the anchoring structure and can each overlap a plurality of anchoring elements or each extend over a plurality of anchoring elements. For example. At least in sections, the thickness profile of the coating in the longitudinal direction of the cylinder bore increases gradually and / or gradually, over a dimension that extends over a plurality of anchoring elements of the anchoring structure. Alternatively or additionally, the thickness profile locally has one or more sections of greater coating thickness, which extend in the longitudinal direction in each case over a plurality of anchoring elements. In the section of greater coating thickness of the thickness profile, the thickness of the coating may on average be more than 30%, preferably more than 50%, in particular more than 100% thicker than in other sections of the thickness profile.

The invention is based on the recognition that a coating of the cylinder wall can have the effect of a thermal insulator, by means of which, during operation of the internal combustion engine, heat dissipation in the direction of a main body of the cylinder crankcase can be slowed down. A locally thicker coating can therefore lead to a locally varying temperature profile during operation of the internal combustion engine. Therefore, the running area of the cylinder bore in a thick coating portion is warmer than the running area of the cylinder bore in a thinner coating portion during operation of the internal combustion engine. A following the thickness profile of the tread profile of the tread in the longitudinal direction of the cylinder bore due to the associated different oil temperatures a corresponding friction profile between the tread and the piston. In other words, the piston in a thicker coating section "slides" better than in a thinner coating section due to the higher local oil temperature.

Due to the thickness profile of the coating provided according to the invention, therefore, local influence on the sliding properties of the tribological system of piston and running surface can be taken. If, in a certain area of the cylinder bore, more or less heat transfer through the coating into the cylinder crankcase makes sense, the thickness profile of the coating can be locally reduced or enlarged in accordance with the invention.

According to a first embodiment, the thickness profile in the longitudinal direction of the cylinder bore is gradually increased at least in sections (for example over a section of 5 mm or more and 5 cm or less in the longitudinal direction) in order to at least increase the slidability in the depth direction of the cylinder bore towards the lower point of reversal of the piston to increase in sections. Alternatively or additionally, the thickness profile in the longitudinal direction of the cylinder bore is formed gradually decreasing at least in sections (for example over a section of 5 mm or more and 5 cm or less in the longitudinal direction) in order to at least partially increase the sliding against the depth direction of the cylinder bore towards the upper reversal point increase.

In some embodiments of the invention, the thickness profile has at least one local broadening. In the area of local broadening, the thickness of the coating may on average be 30% or more, preferably 50% or more, more preferably 100% or more, greater than in an adjacent area of the coating.

The average thickness of the coating in the area of the at least one local broadening relative to an adjoining section of the coating preferably increases by 80 μm or more and / or 800 μm or less, in particular by 150 μm or more and / or 400 μm or less.

The local broadening may extend in the longitudinal direction of the cylinder bore over 3 mm or more and / or 80 mm or less, preferably over 8 mm and more and / or 50 mm or less, in particular over 15 mm or more and / or 30 mm or less.

At least one local broadening of the thickness profile can be arranged in a lower half of the cylinder bore, in particular in a lower third of the cylinder bore, wherein the widening in the longitudinal direction can extend over 15 mm or more. In this way, local influence on the slidability of the piston in a lower region of the cylinder bore, for example at a lower reversal point, can be taken. In other words, the slidability in a lower portion of the cylinder bore can be changed relative to the slidability in another portion of the cylinder bore. For example. For example, it may be useful to provide high lubricity in a region of the cylinder bore where the piston moves at a slower rate.

In a particularly preferred embodiment of the invention, the thickness profile is formed according to a friction profile to be obtained in the longitudinal direction of the cylinder bore between the running surface and a piston.

For example, the thickness profile of the coating has a local broadening with an increased average coating thickness in order to locally adapt the friction force between the running surface of the cylinder bore and the piston in the area of the local broadening, in particular to reduce or increase the lubricity.

According to a preferred embodiment of the invention, a longitudinally extending depth profile is introduced into the cylinder wall in addition to the anchoring structure according to the invention. The depth profile may, in some embodiments of the invention, be introduced into the cylinder wall prior to activation of the cylinder wall. Alternatively, the depth profile can be introduced simultaneously with the activation of the cylinder wall in the cylinder wall.

As already explained above, the anchoring structure can be formed by anchoring elements in the cylinder wall, such as depressions and / or engagement grooves, and form a "microprofile".

The depth profile may be formed as a diameter of the cylinder bore which varies gradually and / or stepwise in the longitudinal direction and form a "macroprofile" which superimposes the anchoring structure. For example. For example, the diameter of the cylinder wall is made larger in a broadening portion, and the broadening portion may extend in the longitudinal direction over 3 mm or more and / or over 80 mm or less.

The diameter of the cylinder wall may, for example, increase by 100 μm or more, preferably by 160 μm or more, in particular by 200 μm or more, particularly preferably by 500 μm or more, in the widening section.

The depth profile introduced into the cylinder wall preferably corresponds essentially to the thickness profile of the coating. In other words, the coating is particularly thick in sections of increased diameter of the cylinder wall, while the coating is correspondingly thinner in sections of smaller diameter of the cylinder wall.

In a particularly preferred embodiment of the invention, the thickness profile of the coating corresponds to the depth profile of the cylinder wall, so that (despite locally variable average coating thickness), a substantially constant diameter of the coated cylinder bore over the thickness profile can result. The coated cylinder bore or the running surface preferably has a substantially constant diameter over more than 50% of its length, preferably over more than 80% of its length, in particular over 95% or more of its length. In some embodiments, the length of the cylinder bore in the longitudinal direction is about 140 mm.

The depth profile can be introduced by irradiating the cylinder wall with a medium under high pressure in the cylinder wall. For example. The depth profile is introduced by high-pressure water jets in the cylinder wall.

In order to produce a depth profile with a diameter of the cylinder wall varying in the longitudinal direction, at least one irradiation parameter can be varied according to the course of the depth profile during irradiation. For example. The cylindrical wall is irradiated in a section of the depth profile with high depth longer or more intense. For example. an irradiation tool is moved through the cylinder bore at a varying speed in order to make the depth of the cylinder wall or the diameter of the cylinder bore to be coated locally different. In some embodiments, an irradiation pressure, an irradiation intensity, an irradiation duration, and / or an irradiation intensity are varied according to the profile of the depth profile to be achieved.

By irradiating the cylinder wall with a medium under high pressure, the cylinder wall can also be activated at the same time. In particular, the irradiation can serve Insert micro-grooves in the cylinder wall, in which the coating applied to it can anchor well. Due to the high-pressure irradiation, the multiplicity of micro-recesses introduced can increase the surface area of the cylinder wall, and at the same time, by means of an increased density, the meshing engagement between the cylinder wall and the coating can be realized. A further advantage may be that the irradiation of the cylinder wall may render unnecessary the cleaning which is regularly required in conventional mechanical roughening.

According to one embodiment of the invention, high-pressure irradiation of the cylinder wall simultaneously introduces an anchoring structure having numerous microwells and a "macroscopic" depth structure, wherein the depth structure is characterized by a diameter of the cylinder wall (before its coating) that varies in the longitudinal direction of the cylinder bore.

Alternatively or additionally, the depth profile can be introduced into the cylinder wall by mechanical material removal in accordance with the profile of the depth profile, for example by machining such as a bore and / or milling to obtain a varying bore diameter. In this case, the cylinder wall with the depth profile introduced therein can subsequently be activated by introducing the anchoring structure.

As already explained, the anchoring structure can be introduced by irradiating the cylinder wall with a medium, in particular a liquid such as water, under high pressure, wherein micro-depressions can be introduced into the cylinder wall by the high-pressure irradiation. The irradiation can be carried out with a pressure of 1500 bar or less, in particular with a pressure between 500 bar and 1500 bar.

Alternatively or additionally, the anchoring structure can be introduced by introducing circumferential grooves into the cylinder wall by machining. For example, an annular saw blade is used to introduce the grooves, which is provided at its periphery with a plurality of cutting teeth, wherein the saw blade can be rotated about its longitudinal axis and on a circular path. The circular path is typically not circular; For example, the ring path is star-shaped. The width of the incisors can correspond to the intended width of the grooves. For acceleration, a plurality of saw blades arranged in parallel can be used, wherein preferably the distance between adjacent saw blades can be a multiple of the width of webs formed between the grooves.

In some embodiments, the lands formed between the grooves are reshaped to form undercuts. Through the undercuts, the anchoring of the coating in the grooves can be improved. The webs are formed, for example, by means of rolling.

In this case, a forming tool, in particular a roller burnishing tool, can be used, with sections radially expandable diameter. In this way, such webs can be formed, which are arranged in a section with locally enlarged diameter of the cylinder bore.

It is also conceivable to irradiate the groove structure formed thereby subsequently under high pressure in order to introduce micro-depressions into the vertexes of the webs and / or into the groove bottoms. The adhesion of the coating to the cylinder wall can thereby be further improved.

According to a preferred embodiment of the invention, the coating is applied to the activated cylinder wall by means of a thermal spraying process. For example. the coating is applied by means of a plasma spraying process or by means of arc wire spraying.

In order to achieve a coating thickness which varies in the longitudinal direction according to the thickness profile, at least one coating parameter can be varied during the coating in accordance with the profile of the thickness profile. For example. The coating tool is driven in sections at a slower speed through the cylinder bore to locally achieve a greater coating thickness. Alternatively or additionally, the coating thickness and / or the coating intensity can be temporarily increased during coating in order to achieve a larger coating thickness locally. According to some embodiments, a coating speed, a coating duration, and / or a coating thickness in coating are varied according to the profile of the thickness profile.

According to some embodiments of the invention, the coated cylinder bore is subsequently honed. Preferably, a cylindrical honing tool is used so that a substantially (or nearly exactly) cylindrical, coated cylinder bore can be created.

The cylinder crankcase and the cylinder wall are preferably formed of an aluminum alloy.

The coating is preferably an iron-based alloy which offers a particularly high resistance to wear in the cured state.

In another aspect, the invention relates to a cylinder crankcase having at least one longitudinally extending cylinder bore with a cylinder wall. An anchoring structure is introduced into the cylinder wall into which engages a coating applied to the cylinder wall, wherein the coating serves as a running surface.

According to the invention, the thickness of the coating varies in accordance with the anchoring structure and additionally according to a thickness profile that overlaps the anchoring structure in the longitudinal direction of the cylinder bore.

Preferably, the thickness profile in the longitudinal direction varies at least in sections, but is substantially constant in the circumferential direction with respect to the axis of the cylinder bore in sectional planes perpendicular to the axis.

The anchoring structure can be formed by anchoring elements introduced into the cylinder wall, such as microwells and / or grooves, in which the coating can engage and thereby anchor itself to the cylinder wall.

The thickness profile can be characterized by a mean thickness of the coating that changes gradually or stepwise in the longitudinal direction of the cylinder bore, at least in sections. For example. For example, the thickness profile has a broadening portion in which the average thickness of the coating is increased by 30% or more, preferably by 50% or more, more preferably by 100% or more, from an adjacent portion of the coating. The broadening portion may have a dimension of 3 mm or more and 80 mm or less in the longitudinal direction.

The diameter of the cylinder wall may be formed varying prior to coating in the longitudinal direction of the cylinder bore. In other words, a depth profile extending in the longitudinal direction of the cylinder bore can be introduced into the cylinder wall. For example. For example, the depth profile has at least a portion of increased diameter of the cylinder wall.

According to a particularly preferred embodiment of the invention, the depth profile of the cylinder wall extends substantially in accordance with the thickness profile of the coating. In this way it can be made possible that a substantially constant diameter of the coated cylinder bore results across the thickness profile.

The thickness profile may have a local broadening with an increased coating thickness in order to locally adjust the friction force between the tread and a piston, in particular to reduce it.

The thickness profile may extend between the tread and a piston according to a friction profile to be obtained in the longitudinal direction.

• 1 eine schematische Schnittdarstellung einer gemäß dem erfindungsgemäßen Verfahren bearbeiteten Zylinderwand (linke Seite) zusammen mit dem Dickenprofil (rechte Seite),
• 2 eine schematische Schnittdarstellung einer gemäß dem erfindungsgemäßen Verfahren bearbeiteten Zylinderwand (linke Seite) zusammen mit dem Dickenprofil (rechte Seite),
• 3 eine vergrößerte Schnittansicht einer gemäß dem erfindungsgemäßen Verfahren bearbeiteten Zylinderwand,
• 4A und 4B eine Mikroschliffdarstellung einer gemäß dem erfindungsgemäßen Verfahren bearbeiteten Zylinderwand vor dem Honen (4A) und nach dem Honen (4B),
• 5 eine Mikroschliffdarstellung einer gemäß dem erfindungsgemäßen Verfahren bearbeiteten Zylinderwand;
• 6 eine Mikroschliffdarstellung einer gemäß dem erfindungsgemäßen Verfahren bearbeiteten Zylinderwand; und
• 7 ein Flussdiagramm, das die Schritte des erfindungsgemäßen Verfahrens veranschaulicht.

The invention will be explained in more detail below with reference to the drawing. This shows in

• 1 a schematic sectional view of a processed according to the inventive cylinder wall (left side) together with the thickness profile (right side),
• 2 a schematic sectional view of a processed according to the inventive cylinder wall (left side) together with the thickness profile (right side),
• 3 an enlarged sectional view of a processed according to the inventive cylinder wall,
• 4A and 4B a microsection of a processed according to the inventive cylinder wall before honing ( 4A ) and after honing ( 4B )
• 5 a microsection of a machined according to the inventive cylinder wall;
• 6 a microsection of a machined according to the inventive cylinder wall; and
• 7 a flow chart illustrating the steps of the method according to the invention.

1 shows a schematic sectional view of a processed according to the inventive cylinder wall 11 (left side) together with the corresponding thickness profile D1 a coating (right side).

The cylinder wall 11 surrounds itself in a longitudinal direction L about an axis extending cylinder bore 10 a cylinder crankcase of an internal combustion engine.

Before coating with a coating 30 becomes the cylinder wall 11 by the introduction of an anchoring structure 20 activated. The anchoring structure 20 can be formed by a multiplicity of microwells, for example small craters and holes, which are formed by irradiating the cylinder wall in FIG these can be introduced. The depressions of the anchoring structure 20 are in 1 through a roughened surface of the cylinder wall 11 illustrated schematically. Details of the anchoring structure 20 are not shown.

If the coating 30 is applied to the anchoring structure in the liquid state, the coating may during drying in the anchoring structure 20 anchor so that they fit particularly well on the cylinder wall 11 liable. As a result, the coating forming the running surface of the cylinder 30 wear and abrasion resistant trained.

As in 1 is shown, the thickness varies D the coating not only according to the anchoring structure 20 but additionally according to a longitudinal direction L varying thickness profile D1 , The thickness profile D1 is on the right side of Figure as a function of the extension of the cylinder bore in the longitudinal direction L shown.

In the example shown, the thickness profile D1 a widening section 40 in which the thickness of the coating 30 opposite an adjacent coating section 41 is enlarged. For example, the (average) thickness of the coating is in the widening section 40 more than 30% larger than in the adjacent section 41 ,

The broadening section 40 can be in the longitudinal direction L extend over more than 5 mm and less than 50 mm.

The broadening section 40 can be in a lower half or in a lower third of the cylinder bore 10 be arranged to locally reduce the friction between the piston and tread there.

In 1 is further shown that the diameter of the cylinder wall 11 (without coating) in the longitudinal direction L can be arranged varying according to a depth profile. Thus, in the illustrated embodiment, the diameter of the cylinder wall is in the broadening section 40 the coating 30 increased.

In this case, the depth profile of the cylinder wall 11 essentially the thickness profile D1 the coating 30 correspond. In other words, the radius of the cylinder wall 11 with introduced depth profile in the longitudinal direction L the cylinder bore according to the thickness profile D1 vary.

If the depth profile of the cylinder wall 11 the thickness profile D1 the coating applied thereto 30 corresponds, despite a varying coating thickness in the longitudinal direction L, a constant diameter X the coated cylinder bore 10 result.

The depth profile can be introduced by irradiating the cylinder wall with a medium under high pressure in the cylinder wall, wherein an irradiation parameter can be varied according to the depth profile. At the same time, the cylinder wall can be activated or roughened by the introduction of microwells through the irradiation medium.

The coating 30 can then be applied by means of a thermal spraying process.

After completion of the coating, the surface of the coating can be honed, for example, to remove unevenness of the coating caused by the anchoring structure, to introduce a desired fine grinding into the coating surface and / or preferably to provide a cylindrical profile of the coated cylinder bore.

2 shows a schematic sectional view of a processed according to the inventive cylinder wall (left side) together with the thickness profile (right side).

Essential details of the coated cylinder wall correspond to those in 1 shown cylinder wall, so that reference may be made to the above statements, which will not be repeated here.

The course of the thickness profile D1 in 2 differs from the course of the thickness profile in 1 , The thickness profile D1 the coating in 2 has an at least partially gradually increasing (or decreasing) thickness of the coating 30 on. For example. can change the thickness of the coating 30 over 3 mm or more, preferably over 10 mm or more in the longitudinal direction L gradually increase (or alternatively decrease) to gradually change the friction characteristics between the piston and the tread in a given portion of the cylinder bore.

The depth profile T1 the (uncoated) cylinder wall 11 corresponds essentially to the thickness profile D1 the coating 30 , so that one in the longitudinal direction L cylindrical (coated) cylinder bore 10 results.

3 is an enlarged sectional view of a processed according to the inventive cylinder wall 11 ,

Essential details of the coated cylinder wall 11 correspond to the in 1 shown cylinder wall, so that reference may be made to the above statements, which will not be repeated here.

So has the thickness profile of the coating 30 a widening section 40 in which the (average) thickness D the coating 30 opposite an adjacent coating section 41 is enlarged. For example, the (average) thickness of the coating is in the widening section 40 by more than 30% or more than 50% larger than in the adjacent section 41 ,

Due to the thick coating 30 in the distribution section 40 This can be between the piston 5 and the tread 6 acting fluid to a higher first temperature T1 heat up as in the adjacent section 41 with thinner coating thickness in which the fluid may have a smaller second temperature T2. The result is a friction profile corresponding to the thickness profile in the longitudinal direction.

The broadening section 40 can be in the longitudinal direction L extend over more than 5 mm and less than 50 mm.

The course of the depth profile of the (uncoated) cylinder wall 11 can thereby the course of the thickness profile of the coating 30 match, leaving a cylindrical (coated) cylinder bore 10 can result.

Unlike the in 1 The embodiment shown is the anchoring structure 20 in 3 not by high pressure jets in the cylinder wall 11 brought in. Rather, the anchoring structure has circumferential grooves in the cylinder wall, wherein the webs formed between the grooves are deformed to form undercuts. Due to the undercuts, the coating may be 30 anchor very well.

The cylinder wall 11 can be mechanically preprocessed before introducing and forming the grooves, so that they in the longitudinal direction L has a varying according to the depth profile radius. The subsequently introduced grooves can be reshaped by means of a roller burnishing tool with sections radially expandable diameter.

The broadening section 40 extends in the longitudinal direction over a plurality of anchoring elements of the anchoring structure, for example. Over two or more, in particular a plurality of grooves and webs.

4A is a microsection of a processed according to the inventive cylinder wall 11 before honing.

4B is a microsection of the machined cylinder wall 11 out 4A after honing.

It is the distribution section 40 and the adjacent section 41 a coating 30 represented with a thickness profile, which essentially the thickness profile 1 equivalent.

The almost exactly cylindrical course of the coated bore is evident despite varying coating thickness and varying depth of the (uncoated) cylinder wall 11 recognizable.

5 is a microsection of a processed according to the inventive cylinder wall 11 ,

Shown is an anchoring structure formed from formed webs 20 where the thickness of the coating 30 increases at least in sections in the longitudinal direction L according to a thickness profile and / or decreases. The portion of increasing coating thickness extends over a plurality of anchoring elements of the anchoring structure, for example via a plurality of grooves and webs.

6 is a microsection of a processed according to the inventive cylinder wall 11 ,

It is the distribution section 40 and the adjacent section 41 a coating 30 represented with a thickness profile, which essentially the thickness profile 3 equivalent.

The running surfaces are not yet honed.

7 is a flowchart illustrating the steps of the method according to the invention.

In the (optional) box 710 becomes a cylinder wall in a longitudinal direction L extending cylinder bore of an internal combustion engine provided with a predetermined depth profile. The depth profile may be designed such that the diameter of the cylinder wall in the longitudinal direction L the cylinder bore varies at least in sections.

In box 720 the cylinder wall is activated by the introduction of an anchoring structure. The anchoring structure can be manufactured simultaneously with the depth profile or after the depth profile.

The anchoring structure may be in the form of numerous anchoring elements, such as depressions or grooves, into which the coating to be applied thereto can engage and in which it can become anchored. The variations of the depth profile thereby extend in the longitudinal direction in each case over a plurality of anchoring elements of the anchoring structure.

Subsequently, in box 730 applied as a tread coating applied to the activated cylinder wall, wherein the coating engages in the anchoring structure. The coating is applied in a longitudinal direction according to a thickness profile varying thickness. The variations of the thickness profile extend in the longitudinal direction in each case over a plurality of anchoring elements.

The running surface of the coating can then be honed, for example to provide a cylindrical coated cylinder bore.

LIST OF REFERENCE NUMBERS

5

piston

6

tread

10

bore

11

cylinder wall

20

anchoring structure

30

coating

40

dissemination section

41

adjacent section

710,720,730

boxing

D

Thickness of the coating

D1

thickness profile

L

longitudinal direction

T1

depth profile

X

Diameter of the cylinder bore

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 102009027200 B3 [0008]

Claims (16)

A method of machining a cylinder wall (11) of a longitudinally extending cylinder bore (10) of an internal combustion engine, comprising: (i) activating the cylinder wall (11) by inserting an anchoring structure (20); and (ii) applying a coating (30) serving as a running surface to the activated cylinder wall (11), wherein the coating engages the anchoring structure (20), characterized in that a thickness (D) of the coating according to the anchoring structure (20) and additionally varies in the longitudinal direction (L) according to a thickness profile (D1) overlying the anchoring structure. Method according to Claim 1 , characterized in that before or simultaneously with the activation of the cylinder wall (11) in the longitudinal direction (L) varying depth profile (T1) is introduced into the cylinder wall (11). Method according to Claim 2 , characterized in that the depth profile (T1) introduced into the cylinder wall essentially corresponds to the thickness profile (D1) of the coating, so that a substantially constant diameter (X) of the cylinder bore (10) results across the thickness profile. Method according to Claim 2 or 3 , characterized in that the depth profile is introduced by irradiating the cylinder wall with a medium under high pressure in the cylinder wall (11), wherein at least one irradiation parameter such as an irradiation pressure, an irradiation intensity or an irradiation time according to the course of the depth profile (T1) is varied. Method according to Claim 2 or 3 , characterized in that the depth profile (T1) is introduced by mechanical material removal according to the course of the depth profile in the cylinder wall (11). Method according to one of the preceding claims, characterized in that the coating (30) is applied by means of a thermal spraying process, wherein at least one coating parameter such as a coating speed or a coating thickness in coating according to the course of the thickness profile (D1) is varied. Method according to one of the preceding claims, characterized in that the anchoring structure (20) is introduced by irradiating the cylinder wall (11) with a medium under high pressure in order to introduce micro-depressions in the cylinder wall. Method according to one of Claims 1 to 7 characterized in that the anchoring structure (20) is machined by inserting circumferential grooves into the cylinder wall (11), preferably forming the webs formed between the grooves to form undercuts, and more preferably by forming the webs by means of rolling , Method according to one of Claims 1 to 8th , characterized in that the thickness profile (D1) and / or the depth profile (T1) in the longitudinal direction (L) gradually increasing gradually, gradually decreasing, stepwise, and / or a local widening (40) is formed having at least partially. Method according to one of Claims 1 to 9 , characterized in that the thickness profile at least one local widening (40) by 80 microns or more and 800 microns or less, in the longitudinal direction (L) preferably over 3 mm or more and 80 mm or less, in particular over 10 mm or more and extends 30 mm or more. Method according to Claim 10 , characterized in that the local widening (40) of the thickness profile in the lower half, in particular in the lower third of the cylinder bore (10) is arranged. Method according to one of Claims 1 to 10 , characterized in that the coating (30) is subsequently honed. Cylinder crankcase with at least one extending in a longitudinal direction (L) cylinder bore (10) having a cylinder wall (11), wherein an anchoring structure (20) is introduced into the cylinder wall, in which a cylinder wall applied to the coating (30) engages, as Running surface (6), characterized in that a thickness (D) of the coating (30) in the longitudinal direction (L) according to the anchoring structure (20) and additionally in accordance with an anchoring structure cross-thickness profile (D1) varies. Cylinder crankcase after Claim 13 , characterized in that a depth profile (T1) of the cylinder wall (11) extends substantially in accordance with the thickness profile (D1) of the coating (30), so that preferably a substantially constant diameter (X) of the coated cylinder bore (10) over the Thick profile results across. Cylinder crankcase after Claim 13 or 14 , characterized in that the thickness profile of a local widening (40) with an increased Coating thickness has to reduce the frictional force between the tread (6) and a piston (5) locally. Cylinder crankcase after one of the Claims 13 to 15 , characterized in that the thickness profile is formed according to a friction profile to be obtained in the longitudinal direction between the running surface (6) and a piston (5).

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