Selective surface texturing for cylinder liners

Abstract

The present disclosure relates to selective surface texturing for cylinder liners. A method includes spraying a coating onto an engine cylinder bore surface, honing the coated surface to form a honed surface region, and cleaning the honed surface region to remove material from the surface pores. The honed surface region includes a plurality of surface pores and an upper region, a middle region, and a lower region. Cleaning the honed surface region produces an upper region surface porosity, a middle region surface porosity, and a lower region surface porosity, wherein the middle region porosity is greater than at least one of the upper porosity and the lower porosity.

Description

Technical Field

[0001] The present disclosure relates to selective surface texturing of cylinder liners and methods of cleaning cylinder liners. Background Art

[0002] The engine block (cylinder block) may include one or more cylinder bores that accommodate the pistons of an internal combustion engine. The engine block may be cast, for example, from cast iron or aluminum. Aluminum is lighter than cast iron and may be selected to reduce the weight of the vehicle and improve fuel economy. The aluminum engine block may include a cylinder liner, such as a cast iron cylinder liner. If there is no cylinder liner, the aluminum engine block may include a coating on the cylinder bore surface. Cast iron cylinder liners typically increase the weight of the cylinder block and may cause a thermal mismatch between the aluminum cylinder block and the cast iron cylinder liner. Cylinder blocks without cylinder liners may receive a coating (e.g., a plasma coating cylinder bore process) to reduce wear and / or friction.

[0003] Prior to applying the coating, the inner surface of each cylinder bore is machined to impart the surface with suitable wear resistance and strength for automotive applications. The machining process may include roughening the inner surface, applying the metal coating to the roughened surface, honing the metal coating to obtain a finished inner surface, and cleaning the inner surface to remove burrs and debris. Summary of the invention

[0004] According to an embodiment, a method is disclosed, the method comprising: spraying a coating onto a surface of an engine cylinder bore, honing the surface after coating to form a honed surface region, and cleaning the honed surface region to remove material from the surface pores. The honed surface region includes a plurality of surface pores and an upper region, a middle region, and a lower region. Cleaning the honed surface region produces an upper region surface porosity, a middle region surface porosity, and a lower region surface porosity, wherein the middle region porosity is greater than at least one of the upper porosity and the lower porosity.

[0005] According to one or more embodiments, the average porosity of the middle region may be greater than the porosity of the upper region and the porosity of the lower region. In one or more instances, the cleaning step may include spraying a pressurized fluid onto the surface area after honing. The spraying in the cleaning step may include spraying the pressurized fluid through a nozzle having a plurality of controlled orifices of different diameters. The spraying in the cleaning step may include moving a nozzle having a single orifice relative to the surface of the engine cylinder bore and changing the spray pressure of the pressurized fluid based on the region. In another embodiment, the cleaning step may include masking at least one area of ​​the surface after honing and removing material from the surface holes in the unmasked area by gas combustion. In other embodiments, the cleaning step may include spraying an abrasive high-pressure fluid onto the surface area after honing and changing the spray pressure based on the region. The abrasive high-pressure fluid may be compressed air or a dry ice jet.

[0006] According to an embodiment, a method is disclosed, the method comprising: spraying a coating onto a surface of an engine cylinder bore, honing the coated surface to form a honed surface region having a plurality of surface pores, and cleaning the honed surface to selectively remove material from the surface pores. The honed surface region comprises a first region and a second region. Cleaning the honed surface region produces a first region average surface porosity and a second region average surface porosity, the first region average surface porosity being greater than the second region average surface porosity.

[0007] According to one or more embodiments, the first area may be a middle area of ​​the honed surface area, and the second area may be an upper ring and a lower ring of the honed surface area. In one or more embodiments, the cleaning step may include spraying a pressurized fluid onto the honed surface area. The spraying in the cleaning step may include spraying the pressurized fluid through a nozzle having a plurality of controlled orifices of different diameters. The spraying in the cleaning step may include moving a nozzle having a single orifice relative to the surface of the engine cylinder bore and changing the spray pressure of the pressurized fluid based on the area. In another embodiment, the cleaning step may include masking an area in the honed surface area and removing material from the surface holes in the unmasked area by gas combustion. In other embodiments, the cleaning step may include spraying an abrasive high-pressure fluid onto the honed surface area and changing the spray pressure based on the area. The abrasive high-pressure fluid may be compressed air or a dry ice jet.

[0008] According to an embodiment, a method is disclosed, the method comprising: spraying a coating onto a surface of an engine cylinder bore; honing the coated surface to form a honed surface region having a plurality of surface pores and an upper region, a middle region, and a lower region; and cleaning the honed surface region to remove material from the surface pores in the middle region.

[0009] According to one or more embodiments, the middle region may be a majority of the honed surface region, and the upper and lower regions may be upper and lower rings of the honed surface region. In one or more instances, the cleaning step may include selectively spraying a pressurized fluid or abrasive pressurized fluid onto the middle region. In another embodiment, the cleaning step may include masking the upper and lower regions of the honed surface region and removing material from the surface pores in the middle region by gas combustion. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1 is a schematic perspective view of an engine block;

[0011] Figure 2 is a perspective view of a cylinder liner according to an embodiment;

[0012] Figure 3 is a schematic partial cross-sectional view of an engine cylinder bore after coating according to an embodiment;

[0013] Figure 4 is a schematic partial cross-sectional view of an engine cylinder bore after coating according to an embodiment. DETAILED DESCRIPTION

[0014] As required, detailed embodiments of the present invention are disclosed herein; however, it should be understood that the disclosed embodiments are merely examples of the present invention, and the present invention may be implemented in various alternative forms. The drawings are not necessarily drawn to scale; some features may be exaggerated or minimized to show details of particular components. Therefore, the specific structural and functional details disclosed herein should not be interpreted as limiting, but only as a representative basis for teaching those skilled in the art to utilize the present invention in various forms.

[0015] Reference Figure 1 , an engine block or cylinder block 10 is shown. The engine block 10 may include one or more cylinder bores 12, which may be configured to accommodate pistons of an internal combustion engine. The engine block body may be made of any suitable material, such as aluminum, cast iron, magnesium, or alloys thereof. In at least one embodiment, the engine block 10 is a linerless engine block. In these embodiments, the cylinder bores 12 may have a coating thereon. In at least one embodiment, the engine block 10 may include cylinder liners 14, such as liner 14, inserted or cast into the cylinder bores 12. Figure 2 The cylinder liner 14 may be a hollow cylinder or tube having an outer surface 16 , an inner surface 18 , and a wall thickness 20 .

[0016] If the parent material of the engine block is aluminum, a cast iron liner or coating may be provided in the cylinder bore to provide the cylinder bore with increased strength, rigidity, wear resistance or other properties. For example, a cast iron liner may be cast into the engine block or pressed into the cylinder bore after the engine block has been formed (e.g., by casting). In another example, the aluminum cylinder bore may be liner-free, but may be coated after the engine block has been formed (e.g., by casting). In another embodiment, the parent material of the engine block may be aluminum or magnesium, and an aluminum liner or a magnesium liner may be inserted or cast into the engine bore. The casting of an aluminum liner into an aluminum engine block is described in U.S. Publication No. 2017 / 0175668, published on June 22, 2017, the entire disclosure of which is incorporated herein by reference.

[0017] Thus, the bore surface of the cylinder bore can be formed in a variety of ways and from a variety of materials. For example, the bore surface can be a cast iron surface (e.g., from a cast iron engine block or a cast iron cylinder liner) or an aluminum surface (e.g., from an aluminum block or an aluminum liner without a cylinder liner). The disclosed variable coating can be applied to any suitable bore surface, and thus, the term bore surface can apply to the surface of a cylinder block without a cylinder liner or to the surface of a cylinder liner or sleeve that has been disposed in the cylinder bore (e.g., by an interference fit or by casting).

[0018] Reference Figure 3 , a cylinder bore 30 having a coating 32 is disclosed. Although a cylinder bore is shown and described, the present disclosure may be applied to any article of a body including at least one sliding surface wall having a longitudinal axis. Before applying the coating 32, the cylinder bore surface 34 may be roughened. Roughening the cylinder bore surface 34 may improve the bonding or adhesive strength of the coating 32 to the cylinder bore 30. The roughening process may be a mechanical roughening process, such as using a tool with a cutting edge, sandblasting, or a water jet. Other roughening processes may include etching (e.g., chemical or plasma), spark / discharge, or other. In the illustrated embodiment, the roughening process may be multi-step. In a first step, material may be removed from the cylinder bore surface 34 to form a protrusion 36 (shown in dotted lines). In a second step, the protrusion may be changed to form an overhanging projection 38 having an undercut 40. The protrusion may be changed using any suitable process, such as rolling, cutting, milling, pressing, sandblasting, or other.

[0019] The coating 32 may be applied to the roughened cylinder bore surface. In one embodiment, the coating may be a sprayed coating, such as a thermally sprayed coating. Non-limiting examples of thermal spraying techniques that may be used to form the coating 32 may include plasma spraying, detonation spraying, arc spraying (e.g., plasma transferred wire arc or PTWA), flame spraying, high velocity oxygen fuel (HVOF) spraying, thermal spraying, or cold spraying. Other coating techniques may also be used, such as vapor deposition (e.g., PVD or CVD) or chemical / electrochemical techniques. In at least one embodiment, the coating 32 is a coating formed by plasma transferred wire arc (PTWA) spraying.

[0020] A device for spraying the coating 32 may be provided. The device may be a thermal spray device including a spray gun. The spray gun may include spray gun parameters such as atomizing gas pressure, current, plasma gas flow, wire feed rate, and spray gun movement speed. The spray gun parameters may be variable so that they are adjustable or variable during the operation of the spray gun. The device may include a controller that may be programmed or configured to control and change the spray gun parameters during the operation of the spray gun. As described in U.S. Application No. 15 / 064,903 filed on March 9, 2016 (the entire disclosure of which is incorporated herein by reference), the controller may be programmed to change the spray gun parameters to adjust the porosity of the coating 32 in the longitudinal and / or depth directions. The controller may include a system of one or more computers, one or more computers may be configured to perform specific operations or actions by software, firmware, hardware, or a combination thereof installed on the system, which software, firmware, hardware, or a combination thereof causes the system to perform the disclosed actions in operation. One or more computer programs may be configured to perform specific operations or actions by including instructions that cause the device to perform actions when executed by the controller.

[0021] The coating 32 may be any suitable coating that provides sufficient strength, rigidity, density, wear performance, friction, fatigue strength and / or thermal conductivity for the engine block cylinder bore. In at least one embodiment, the coating may be an iron coating or a steel coating. Non-limiting examples of suitable steel compositions may include any AISI / SAE steel grade from 1010 steel to 4130 steel. The steel may also be stainless steel, such as those in the AISI / SAE 400 series (e.g., 420). However, other steel compositions may also be used. The coating is not limited to iron or steel, and the coating may be formed of or contain other metals or nonmetals. For example, the coating may be a ceramic coating, a polymer coating, or an amorphous carbon coating (e.g., DLC or the like). Therefore, the type and composition of the coating may vary based on the application and the desired performance. In addition, a variety of coating types may be present in the cylinder bore 30. For example, different coating types (e.g., compositions) may be applied to different regions of the cylinder bore (described in more detail below), and / or the coating type may vary with the depth of the entire coating (e.g., layer by layer).

[0022] Typically, the process of applying the coating 32 and ultimately determining the size and performance of the cylinder bore can include multiple steps. First, the cylinder bore surface can be prepared to receive the coating. As described above, the cylinder bore surface can be a cast engine cylinder bore or a cylinder liner (cast-in or interference fit), so it can be used interchangeably below and is not intended to be limiting. Surface preparation can include roughening and / or cleaning the surface to improve the bonding / adhesion of the coating. Next, the deposition of the coating can be started. The coating can be applied in any suitable manner, such as spraying. In one example, the coating can be applied by thermal spraying, such as PTWA spraying. The coating can be applied to the cylinder bore surface by rotating spraying of the coating. The nozzle, the cylinder bore surface, or both can be rotated to apply the coating. As described in U.S. Application No. 15 / 064,903, the deposition parameters can be adjusted (e.g., by a controller) to produce different levels of porosity in the coating. The adjustment can be made while the coating is being applied, or the coating can be paused to adjust the parameters. The same or further adjusted deposition parameters can be used to apply other layers of the coating.

[0023] After the coating is applied, it can be honed to the final bore diameter based on the specified engine bore size. In some embodiments, in order to reduce the amount of cutting during honing, optional machining operations such as drilling, cutting, etc. can be performed before honing. Generally, the honing process involves inserting a rotating tool with abrasive particles into the cylinder bore to remove material to achieve a controlled diameter. The abrasive particles can be attached to a separate piece called a honing stone, and the honing tool can include multiple honing stones. The honing process can include one or more honing steps. If there are multiple honing steps, the parameters of the honing process (such as grit size and applied force) can be varied from step to step. Figure 3 In the illustrated embodiment, the coating 32 may initially be deposited to an initial thickness 52, as shown in dashed lines. The honing process may remove material from the coating 32 and provide a highly cylindrical bore wall 54 having a final bore diameter. As described herein, the coating surface may be a surface resulting from the honing process, a surface area after honing, rather than the initial surface after deposition (e.g., a bore wall 54 rather than the initial thickness 52).

[0024] As used herein, a surface region after honing can be a region in a coating that includes the surface of the coating and a relatively small depth below the surface (e.g., 5 μm, 10 μm, 25 μm, or 50 μm below the surface). It has been found that the porosity of the surface region after honing (i.e., the average surface porosity) can generally be described by two types of pores, which can be referred to as primary pores and secondary pores. The primary pores can be those pores generated during the coating process (e.g., spraying). For example, the type of porosity is generally mentioned in U.S. Application No. 15 / 064,903. These pores (e.g., porosity and size) can generally be controlled by coating parameters. Secondary pores can be those pores formed or generated after the coating is deposited.

[0025] During the honing process, material removed from the coated cylinder bore surface or burrs or edges of the hole may be smeared on the hole surface or may fill into the hole. This results in lower surface porosity and significantly reduces the oil retention capacity of the hole. Therefore, the cleaning process cleans the cylinder liner surface to expose the hole. The cleaning process may include performing one or more cleaning processes on the cylinder bore coating surface. In one embodiment, the cleaning process may include a high-pressure water jet. The jet may be controlled with a spray pattern, such as a fan-shaped spray pattern (e.g., a substantially 2D spray pattern). Other cleaning methods that may be suitable include ice blasting (e.g., water-based or CO2-based), brushing, or very fine abrasive media. However, these methods are examples and are not intended to be limiting.

[0026] The cleaning process can remove material (such as debris or burrs) generated by previous mechanical operations (such as previous honing steps or drilling operations). As a result, loose material present in the pores of the coating can be removed to expose the pores and allow the pores to retain oil. During a specific coating process, particles in the coating material (for example, in the form of solid particles (cold spray) or molten balls (thermal spray)) can be accelerated toward the cylinder bore surface. These particles can accumulate with each other to form a substantially continuous coating. The particles can generally deform or merge to form a relatively uniform coating, however, some particles may remain more discrete than other particles or more weakly bonded to the coating than other particles. In addition, in specific areas, the layer of the coating may not be fully adhered or not adhered as strongly as in other areas. These particles and areas can be potential sites (e.g., nucleation sites) for creating new pores during the cleaning process.

[0027] The cleaning process may cause these particles or layers to debond or delaminate, respectively, or may create residual stresses in the coating at or near the particles. Thus, the cleaning process may perform at least two functions: 1) remove existing debris and burrs from the coating surface, and 2) create nucleation sites on the coating surface. Thus, the cleaning process may allow the honed surface to have not only a similar porosity to the bulk of the coating, but also an increased porosity due to the additional pores created. In some embodiments, the cleaning process (or a similar cleaning process) may be repeated after the final honing process to remove any final debris, remove any burrs, or remove any other loose material from the cylinder bore surface or within the bore.

[0028] The use of surface pores and surface porosity to improve oil retention in a cylinder bore surface (such as a cylinder liner or bore wall) requires a cleaning process to remove burrs and debris to improve lubricant distribution to reduce hydrodynamic drag and piston ring roughness. While common cleaning processes are described above, specific bores require more controlled and selective processes to adequately minimize wear and friction. Additionally, a cylinder bore may require a designated area with more drag reduction to retain more lubricant, resulting in a need for areas with higher surface porosity or more pores exposed by cleaning.

[0029] According to an embodiment, a selective cleaning process is disclosed. The selective cleaning process removes material from the hole in a controlled process to expose the hole to a certain extent in a specific area of ​​the cylinder bore or the area of ​​the surface area after honing, thereby producing a tailored surface texture. The selective cleaning process exposes or exposes the debris filled or smeared on the hole during the operation of honing the cylinder surface to a specific extent, or exposes or exposes the debris in a specific area of ​​the cylinder bore surface. For example, the cylinder bore surface where the piston ring assembly travels consists of designated areas (some areas that require a higher average surface porosity than other areas). By tailoring the cleaning process to the designated area, lubricant deposition can be precisely improved where the piston ring travels. In general, most of the cylinder bore surface will benefit from exposing more holes through cleaning, while the upper ring reverse area and the lower ring reverse area (or the upper area and the lower area) of the cylinder bore surface can include fewer exposed holes than the middle area (most of them). By selectively cleaning the surface area after honing, the surface texture can be tailored to appropriately expose pores on the surface after the coating is applied.

[0030] like Figure 4As shown, the middle region 48 can be disposed between the upper region and the lower region 46. Depending on the crank angle of the piston, the middle region 48 can include a large portion of the cylinder liner or cylinder bore wall or cover a specific height of the cylinder bore. Similar to the crank angle, the upper and lower regions 46 and the middle region 48 can cover an area (e.g., a height range) of the cylinder bore surface corresponding to where the piston has a certain speed. For exemplary purposes, crank angle is discussed for these regions, but other attributes may also apply. Although Figure 4 4. Although not shown, the upper and lower regions 46 may or may not have the same height and may be embodied on the upper and lower rings. Thus, the crank angle range may be asymmetric and may extend from any value disclosed above for the upper region 46 to any region for the lower region 46. For example, the ratio of the lengths of the upper, middle, and lower regions may be, but are not limited to, approximately 0.05:0.9:0.05 to 0.1:0.8:0.1 or approximately 0.05:0.9:0.05 to 0.15:0.7:0.15, respectively. In other embodiments where the upper and lower regions 46 may not have the same height, the ratio of the lengths of the upper, middle, and lower regions may be, for example, but not limited to, approximately 0.03:0.9:0.07 to 0.08:0.8:0.12 or approximately 0.07:0.9:0.03 to 0.12:0.8:0.08. In embodiments, the upper and lower regions 46 may include, for example, at least 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, or 10% of the honed surface area in total, and up to 10%, 15%, 20%, 25%, or 30% of the honed surface area in total. In some embodiments, each of the upper and lower regions 46 may individually be, for example, at least 1%, 2%, or 3% of the surface area after honing, and at most approximately 5%, 10%, or 15% of the surface area after honing, and the upper and lower regions 46 may or may not represent the same percentage of the surface area after honing.

[0031] In one embodiment, the surface porosity (e.g., average surface porosity) of the upper and lower regions 46 can have an average surface porosity of up to 3%. For example, the upper and lower regions 46 can have, but are not limited to, a porosity of up to 2.5%, 2%, or 1.5%. In one embodiment, the upper and lower regions 46 can have a honed surface porosity of 0.1% to 3%, or any sub-range therein, such as 0.5% to 3%, 0.5% to 2.5%, 0.5% to 2%, 1% to 2.5%, or 1% to 2%. As disclosed herein, "average surface porosity" can refer to surface porosity, or the percentage of the surface of the coating that is composed of pores (e.g., spaces or air before the introduction of a lubricant).

[0032] The surface porosity of the middle region 48 may be greater than the surface porosity of the upper region and / or the lower region 46. In one embodiment, the middle region 48 may have a surface porosity (e.g., average surface porosity) of at least 2%, for example, at least 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, 15%, or 20%. In another embodiment, the middle region 48 may have a surface porosity of 2% to 20% or any sub-range thereof, such as 3% to 20%, 5% to 20%, 10% to 20%, 2% to 15%, 3% to 15%, 5% to 15%, 7% to 15%, 3% to 12%, 3% to 10%, 4% to 10%, 5% to 10%, or 5% to 8%.

[0033] The size or diameter of the pores in the low honing surface porosity region and the high honing surface porosity region, the pore depth and / or the pore distribution can be the same or can be different based on the selective cleaning process that exposes the pores in the region. In one embodiment, based on the selective cleaning process, the average pore size of the upper region / lower region 46 and the middle region 48 can be the same or similar, while the surface porosity is different. The average pore size of the upper region / lower region 46 and the middle region 48 can be, but is not limited to, 0.1 to 750 μm or any sub-range thereof, such as 0.1 to 500 μm, 0.1 to 250 μm, 0.1 to 200 μm, 1 to 750 μm, 1 to 500 μm, 1 to 300 μm, 1 to 200 μm, 10 to 300 μm, 10 to 200 μm, 20 to 200 μm, 10 to 150 μm or 20 to 150 μm. In another embodiment, based on diameter or pore depth, the pores can be selectively exposed during the cleaning process, but not limited to about 10% to 95%, about 15% to 90%, about 20% to 85%, or about 25% to 80% of the pore size / pore depth to obtain a selective surface texture. In another embodiment, the pore distribution based on the surface porosity can be selectively exposed based on the region. A specific region can have a higher percentage of exposed pores. For example, the pores in the upper and lower regions can be exposed to have a surface porosity of about 0.1% to 3%, while the middle region can be exposed to have a surface porosity of about 2% to 20%. To achieve surface porosity, the cleaning process may expose pores in selected regions based on diameter or pore depth to about 10% to 95%, about 15% to 95%, about 20% to 95%, about 25% to 95%, about 10% to 90%, about 15% to 90%, about 20% to 90%, about 25% to 90%, about 10% to 85%, about 15% to 85%, about 20% to 85%, about 25% to 85%, about 10% to 80%, about 15% to 80%, about 20% to 80%, or about 25% to 80% of the pore size / pore depth. In other embodiments, the pore size / pore depth may remain uniform across the region, but more pores may be selectively exposed in the middle region 48 compared to the upper / lower regions 46 to achieve the desired surface porosity.

[0034] The selective cleaning step may include processes such as high-pressure fluid (e.g., air or water) jets, ice jets, or mechanical cleaning (e.g., brushing). Therefore, increasing or decreasing the intensity of the cleaning process at various locations within the cylinder bore may affect the extent to which the hole is exposed in the surface area after honing. In one embodiment, increasing the intensity of the cleaning process may increase the removal of material from the hole, and vice versa. Increasing the intensity at different areas of the cylinder bore may change the surface porosity of the surface area after honing as more or less holes are exposed between the various areas. For example, if a high-pressure water jet is used, increasing the pressure of the jet passing through a specific area may increase the intensity of the cleaning process. Similarly, if mechanical cleaning is used, the applied force may be increased, the speed of cleaning may be increased, or other parameters that make the cleaning more intense in a specified area of ​​the cylinder bore may be increased. Another way to increase or decrease the intensity may be to change the number of cleaning processes in the cleaning process. Additional cleaning processes may remove more material, while fewer cleaning processes may remove less material. Varying the cleaning intensity of the zones provides a controlled method of cleaning the cylinder bore to achieve selective surface texturing of the honed surface.

[0035] According to an embodiment, in order to achieve a customized cleaning method for selective surface texture, a high-pressure fluid can be applied by a pressurized nozzle. In some embodiments, the pressurized nozzle may include a plurality of controlled orifices with different diameters to generate different pressures so that the surface holes are exposed to different degrees. In other embodiments, the pressurized nozzle may include a single orifice that can move relative to the cylinder liner, and the pressure varies according to the position of the nozzle in the cylinder liner to expose the holes to different degrees. According to another embodiment, a gas combustion process can be used to customize the cleaning process. Specific areas of the cylinder liner can be masked so that a combustion event sufficient to burn off burrs and particle debris on the surface of the hole can be used to expose the holes in the unmasked area of ​​the cylinder liner. According to yet another embodiment, a high-pressure fluid with an abrasive effect (such as a compressed air / dry ice jet) can be used to provide a selective surface texture. A high-pressure fluid with an abrasive effect can be implemented together with a nozzle that can move relative to the cylinder liner, and the pressure varies according to the position of the nozzle in the cylinder liner to expose the holes to different degrees.

[0036] Although the coating 32 on the cylinder bore 30 having two different surface porosity regions has been described above, there may be more than two different surface porosity regions, such as 3, 4, 5 or more different regions. In order to affect the surface porosity gradient and variation between regions, the pore size and exposure level will be based on selective cleaning accordingly. In some embodiments, instead of discrete regions, there may be a gradient of surface porosity along the height of the cylinder bore 30, depending on the cleaning process used to expose the pores. The change in surface porosity may be continuous and may be a linear / constant increase / decrease or may be a curve. The change in surface porosity may also include multiple small stages in surface porosity having two or more regions (e.g., 2 to N regions).

[0037] Thus, a customized cleaning process for providing selective surface texture is provided. The process provides a low cost and fast cycle time method to expose the bore to different degrees so that thermal spray coatings can be effectively used to reduce weight and production costs. The bore can be exposed to different degrees according to selected areas of the surface area after honing of the cylinder bore.

[0038] Although exemplary embodiments are described above, it is not intended that these embodiments describe all possible forms of the present invention. On the contrary, the words used in the specification are descriptive rather than restrictive words, and it should be understood that various changes may be made without departing from the spirit and scope of the present invention. In addition, the features of the various embodiments implemented may be combined to form further embodiments of the present invention.

Claims

1. A method for processing an engine cylinder bore, comprising: Spraying the coating onto the surface of the engine cylinder bore; Honing the coated surface to form a honed surface region including an upper region, a middle region, and a lower region, each of the upper region, the middle region, and the lower region having surface pores; Cleaning the surface area after honing to selectively remove material from the surface pores, wherein different cleaning processes are performed on at least one area of ​​the upper area and the lower area and the middle area, respectively, so that the surface pores in the at least one area and the surface pores in the middle area are exposed to different degrees, so that the porosity of the middle area is greater than the porosity of the at least one area.

2. The method of claim 1, wherein: The average porosity of the middle region is greater than the porosity of the upper region and the porosity of the lower region.

3. The method of claim 1, wherein: The cleaning step involves spraying a pressurized fluid onto the honed surface area.

4. The method of claim 3, wherein: Spraying the pressurized fluid onto the honed surface area includes spraying the pressurized fluid through a nozzle having a plurality of controlled orifices of varying diameters.

5. The method of claim 3, wherein: Spraying the pressurized fluid onto the honed surface area includes moving a nozzle having a single orifice relative to the engine bore surface and varying the spray pressure of the pressurized fluid based on the area.

6. The method of claim 1, wherein: The cleaning step includes masking portions of the honed surface area and removing material from the surface pores in the unmasked areas by gas combustion.

7. The method of claim 1, wherein: The cleaning step includes spraying an abrasive high pressure fluid onto the honed surface area and varying the spray pressure based on the area.

8. The method of claim 7, wherein: The abrasive high pressure fluid is compressed air or a dry ice blast.

9. A method for processing an engine cylinder bore, comprising: Spraying the coating onto the surface of the engine cylinder bore; Honing the coated surface to form a honed surface region having a plurality of surface pores and including a first region and a second region; The honing surface area is cleaned to selectively remove material from the surface pores, wherein different cleaning processes are performed on the first area and the second area respectively to expose the surface pores in the first area and the surface pores in the second area to different degrees, so that the average surface porosity of the first area is greater than the average surface porosity of the second area.

10. The method of claim 9, wherein: The first region is a middle region of the honed surface region, and the second region is an upper ring region and a lower ring region of the honed surface region.

11. The method of claim 9, wherein: The cleaning step involves spraying a pressurized fluid onto the honed surface area.

12. The method of claim 11, wherein: Spraying the pressurized fluid onto the honed surface area includes spraying the pressurized fluid through a nozzle having a plurality of controlled orifices of varying diameters.

13. The method of claim 11, wherein: Spraying the pressurized fluid onto the honed surface area includes moving a nozzle having a single orifice relative to the engine bore surface and varying the spray pressure of the pressurized fluid based on the area.

14. The method of claim 9, wherein: The cleaning step includes masking an area of ​​the honed surface area and removing material from the surface pores in the unmasked area by gas combustion.

15. The method of claim 9, wherein: The cleaning step includes spraying an abrasive high pressure fluid onto the honed surface area and varying the spray pressure based on the area.

16. The method of claim 15, wherein: The abrasive high pressure fluid is compressed air or a dry ice blast.

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